Term
| A patient is required to have the following radiographic examinations: CT of the abdomen, GI series, and a barium enema. The correct order for the scheduling of these procedures would be: |
|
Definition
| CT of the abdomen, barium enema, GI series |
|
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Term
A patient is scheduled for an intravenous iodinated contrast-enhanced CT scan of the kidneys. Prior to the injection, the involved medical personnel should examine recently measured laboratory values for which of the following?
1. CBC
2. Creatinine
3. PT |
|
Definition
|
|
Term
Which of the following is an acceptable form of immobilization during a CT examination?
1. Suspended respiration
2. Use of cushioned hook-and-loop (Velcro) strap
3. Use of medical tape |
|
Definition
|
|
Term
| The average range for normal prothrombin (PT) time is approximately: |
|
Definition
|
|
Term
| The acronym PTT is used for which of the following laboratory tests? |
|
Definition
| Partial thromboplastin time |
|
|
Term
| A normal range for systolic blood pressure in an adult is: |
|
Definition
|
|
Term
| The average range for normal adult BUN levels is approximately: |
|
Definition
|
|
Term
The assessment of D dimer concentration is used to diagnose which of the following pathologic conditions?
1. Dissecting aortic aneurysm
2. Pulmonary embolism
3. Deep vein thrombosis (DVT) |
|
Definition
|
|
Term
| Which of the following corresponds to the period of the cardiac cycle known as ventricular systole? |
|
Definition
| Contraction of the left and right ventricles |
|
|
Term
| Which of the following corresponds to the period of the cardiac cycle known as atrial systole? |
|
Definition
| Contraction of the left and right atria |
|
|
Term
Which of the following refers to the period of the cardiac cycle known as complete cardiac diastole?
1. Contraction of the left and right ventricles
2. Relaxation of the heart muscle
3. The QRS complex of the electrocardiogram (ECG) |
|
Definition
|
|
Term
| Cardiac CT images are typically acquired during which phase of the heart’s cycle? |
|
Definition
|
|
Term
| Normal range of GFR is __ ± __ mL/min/m2 for women |
|
Definition
|
|
Term
| Normal range of GFR is __ ± __ mL/min/m2 for men |
|
Definition
|
|
Term
| The normal range for the International Normalized Ratio (INR) for prothrombin time (PT) results is: |
|
Definition
|
|
Term
| A patient with an elevated level of D dimer in the bloodstream may be at increased risk for which of the following? |
|
Definition
|
|
Term
| The medication known as Coumadin, or its generic name warfarin, is often used to treat: |
|
Definition
|
|
Term
Which of the following statements is true regarding patients receiving metformin therapy for type 2 diabetes and IV contrast-enhanced CT examinations?
1. Metformin therapy is a direct contraindication to administration of IV contrast agents.
2. The patient should not take metformin for up to 2 days following administration of an IV contrast agent.
3. After administration of an IV contrast agent, the patient may need renal function testing before resuming metformin therapy. |
|
Definition
|
|
Term
| The term vasovagal pertains to: |
|
Definition
| systemic hypotension often leading to cerebral ischemia |
|
|
Term
| Which of the following is a correct difference between ionic and nonionic iodinated contrast media? |
|
Definition
| Nonionic iodinated contrast media have a lower osmolality and are associated with a lower incidence of adverse reaction than ionic contrast media. Both types of materials contain iodine in varying concentrations. |
|
|
Term
| Contrast materials that dissociate into charged particles when placed into solution are termed: |
|
Definition
|
|
Term
| A patient has a severe vagal reaction to iodinated contrast material that includes bradycardia. Initial treatment may consist of: |
|
Definition
|
|
Term
| The term used to describe the ability of a fluid to flow is: |
|
Definition
|
|
Term
| Iodine is commonly used in radiopaque contrast media because of its: |
|
Definition
| Iodine’s high atomic number causes it to attenuate a large portion of the primary beam. Introducing iodine into tissue changes the subject contrast of the enhanced anatomic area. |
|
|
Term
| A high-osmolar contrast material has an average osmolality of: |
|
Definition
| 1000 to 2400 mOsm/kg water |
|
|
Term
| Which of the following terms is used to describe a patient having difficulty swallowing? |
|
Definition
|
|
Term
| Which of the following symptoms indicate(s) a vagal reaction to an iodinated intravenous contrast agent? |
|
Definition
| Bradycardia & Systolic pressure below 80 mm Hg |
|
|
Term
| The maximum dose of intravenous iodinated contrast for a child should not exceed: |
|
Definition
|
|
Term
Examples of moderate adverse reactions to iodinated intravenous contrast media are:
1. Shock
2. Faintness
3. Severe vomiting |
|
Definition
|
|
Term
| Severe reactions to intravenous iodinated contrast material occur in approximately __________ of all patients |
|
Definition
|
|
Term
| Hypovolemic shock is caused by an insufficient volume of circulating blood. The common signs and symptoms of hypovolemic shock are pallor (absence of color in the skin), hypotension, tachycardia, and oliguria (decreased urine production). |
|
Definition
- Pallor (absence of color in the skin), hypotension
-Tachycardia,
-Oliguria (decreased urine production) |
|
|
Term
Parenteral routes of medication administration include which of the following?
1. Subcutaneous
2. Intradermal
3. Transdermal |
|
Definition
|
|
Term
| The propensity of a contrast agent to cause fluid to move from the extravascular space to the intravascular space is called: |
|
Definition
|
|
Term
| The best method of reducing the risk of contrast-induced nephrotoxicity (CIN) is: |
|
Definition
| Adequate patient hydration |
|
|
Term
| Prior to resuming normal breastfeeding, it is recommended that a patient who has undergone IV administration of an iodinated contrast agent should pump and discard breast milk for a period of: |
|
Definition
|
|
Term
| The plasma half-life of intravenously administered iodinated contrast material is approximately: |
|
Definition
|
|
Term
| Which of the following is not a category of isolation technique? |
|
Definition
|
|
Term
| Which of the following is the correct order for the stages of infection? |
|
Definition
| Incubation, prodromal, active, convalescence |
|
|
Term
| Infection may occur indirectly through contact with contaminated objects known as: |
|
Definition
|
|
Term
| Which of the following types of isolation precautions is used to protect immunosuppressed patients from possible infection? |
|
Definition
|
|
Term
| CT scanners use between ___ and ___ kVp, yielding x-ray energies with averages between ___ and ___ keV |
|
Definition
|
|
Term
| Owing to the high-energy beam used in CT, the _____ _____ is the predominant interaction between x-ray and matter |
|
Definition
|
|
Term
| When one is using a third-generation CT scanner, it is important that reference detectors positioned at the peripheral portions of the detector array be exposed to: |
|
Definition
|
|
Term
| In 1979, the scientists __________ and __________ shared the Nobel Prize for their research in computed tomography |
|
Definition
|
|
Term
| The type of compensating filter used at the x-ray tube of a CT scanner is called a: |
|
Definition
|
|
Term
| The interaction between x-ray and matter that is responsible for the production of the scatter radiation absorbed by the patient and detectors is: |
|
Definition
|
|
Term
The types of detectors used in computed tomography are:
1. Gas ionization
2. Stimulable phosphor
3. Scintillation |
|
Definition
|
|
Term
| Which of the following is used in gas ionization CT detectors? |
|
Definition
|
|
Term
Which of the following statements concerning the translate-rotate mode of CT data acquisition is/are correct?
1. 360-degree circular detector arrays are used
2. Data are collected only during translation
3. Was used in first- and second-generation CT scanners |
|
Definition
|
|
Term
Which of the following technologic advances has led to the development of spiral/helical CT scanning?
1. Slip-ring technology
2. Electron beam technology
3. High-efficiency x-ray tubes |
|
Definition
|
|
Term
| For a given CT acquisition, the calculated mAs applied to each reconstructed slice may be referred to as the: |
|
Definition
|
|
Term
| The approximate inherent filtration of the CT x-ray amounts to an aluminum equivalent of: |
|
Definition
|
|
Term
| Which of the following acquisitions may be characterized as noncontiguous? |
|
Definition
5.0-mm sections reconstructed every 7.5 mm
Noncontiguous images are images acquired with an interval greater than the section width. For example, 5.0-mm sections reconstructed every 7.5 mm fail to evaluate the intermittent 2.5 mm of tissue. |
|
|
Term
| Which of the following acquisitions may be characterized as overlapping? |
|
Definition
2.5-mm sections reconstructed every 1.25 mm
Overlapping images are reconstructed with a section interval that is less than the section width. A percentage value may be assigned to the degree of overlap. For example, 2.5-mm-thick images reconstructed every 1.25 mm are said to possess a 50% overlap |
|
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Term
| An acquisition is made on a 4-slice MSCT system with a detector array of 16 x 1.25-mm detector elements along the z-axis. With a selected beam width of 20 mm, what beam pitch would result in the table moving 35.00 mm for each rotation of the gantry? |
|
Definition
In multislice CT (MSCT), the beam pitch is equal to the table feed per rotation divided by the:
Total Collimation
The beam pitch, which is unique to multislice CT, is equal to the table feed per rotation divided by the total collimation. The total collimation is equal to the combined thickness of all of the sections that are simultaneously acquired with each gantry rotation. |
|
|
Term
| An acquisition is made on a 4-slice MSCT system with a detector array of 16 x 1.25-mm detector elements along the z-axis. With a selected beam width of 20 mm, what beam pitch would result in the table moving 35.00 mm for each rotation of the gantry? |
|
Definition
1.75
The beam pitch for a given acquisition is equal to the table feed per rotation divided by the total collimation. The total collimation for this acquisition is equal to the total number of sections (detectors) multiplied by the detector dimension, or 16 multiplied by 1.25 mm. The beam pitch may be therefore calculated by dividing 35.00 by 20, or 1.75. |
|
|
Term
| In an MSCT system, the detector array is composed of multiple rows of individual detector elements along the: |
|
Definition
|
|
Term
| _____ _______ refers to the number, length, and organization of the individual detector elements in an MSCT system |
|
Definition
|
|
Term
| The type of MSCT detector array that contains midline narrow elements flanked by wider detectors is called a(n): |
|
Definition
|
|
Term
| A 64-slice MSCT system employs an array of 64 detectors, each with a dimension of 0.625 mm. What beam collimation is required to expose the middle 32 detectors of the array to transmitted x-radiation? |
|
Definition
20mm
The selected 32 detectors, each with an individual dimension of 0.625 mm, would require a beam collimation of 20 mm to expose each to transmitted radiation (32 ✕ 0.625 = 20 mm) |
|
|
Term
| The component of the DAS responsible for strengthening the signal emitted from a detector is termed the: |
|
Definition
|
|
Term
Which of the following technical parameters would greatly improve the quality of CT studies requiring multiplanar reformation (MPR) images?
Noncontiguous scans
Wide section thicknesses
Contiguous scans with wide section thickness
Overlapping scans with narrow sections |
|
Definition
| Overlapping scans with narrow sections |
|
|
Term
| In 1917, Austrian mathematician __________ proved that it was possible to reconstruct a three-dimensional object from the infinite set of all of its projections |
|
Definition
|
|
Term
| Which of the following types of image reconstruction was used in the first prototype CT scanner? |
|
Definition
|
|
Term
| During CT angiography, images may be reconstructed using only the greatest density encountered along each ray. This type of specialized CT image is called a(n): |
|
Definition
|
|
Term
| CT images that have been reconstructed from a portion of the data acquisition process in the hopes of reducing patient motion artifacts are called: |
|
Definition
|
|
Term
| Which of the following is not an iterative method of CT image reconstruction? |
|
Definition
|
|
Term
Which of the following manipulations involves the use of image data?
Adjusting the width and level of a window setting
Decreasing the DFOV
Changing the algorithm selection
Increasing the matrix size |
|
Definition
| Adjusting the width and level of a window setting |
|
|
Term
| As a solid-state CT detector measures transmitted radiation, it emits a proportional response in the form of a(n): |
|
Definition
|
|
Term
| During a CT scan, each sample of ray sum measurements made by the data acquisition system (DAS) is called a: |
|
Definition
|
|
Term
| The ability of an object to attenuate the x-ray beam is assigned a value known as the: |
|
Definition
| Linear Attenuation Coefficient |
|
|
Term
| Which of the following mathematical techniques is used for the reconstruction of volumetric MDCT images? |
|
Definition
| 180-degree interpolation (180LI) |
|
|
Term
| The primary advantage of an isotropic MDCT data set is: |
|
Definition
| High-quality multiplanar reformations(MPRs) |
|
|
Term
| The technique that allows the user to select the range of pixel values used in a 3-D CT reformation is termed: |
|
Definition
|
|
Term
| A voxel may be defined as which of the following? |
|
Definition
|
|
Term
| The portion of the primary beam interacting with a single detector is known as a: |
|
Definition
|
|
Term
| A pixel may be defined as: |
|
Definition
|
|
Term
| Which of the following is not a typical matrix size used with a modern CT scanner? |
|
Definition
|
|
Term
| A 512✕512 matrix will consist of how many pixels? |
|
Definition
|
|
Term
| The Hounsfield value of a pixel is directly related to which of the following? |
|
Definition
| μ (linear attenuation coefficient) of H2O |
|
|
Term
| The dimensions of a voxel may be calculated as the product of which of the following? |
|
Definition
| Pixel size and section width |
|
|
Term
| Which of the following formulas may be used to calculate the dimensions of a pixel? |
|
Definition
| Pixel size = DFOV/matrix size |
|
|
Term
| A CT scanner measures the linear attenuation coefficient of a voxel of tissue as 0.40. The linear attenuation coefficient of water for this scanner equals 0.20. The CT number assigned to the pixel representing this voxel of tissue equals: |
|
Definition
|
|
Term
| A voxel’s dimension may be decreased by which of the following? |
|
Definition
| Decreasing the section width |
|
|
Term
| Two adjacent pixels are measured to have a difference of 1 HU. This amounts to a tissue density difference of approximately: |
|
Definition
|
|
Term
| Which of the following corresponds to the longitudinal dimension of the CT image voxel? |
|
Definition
|
|
Term
| The volume of a voxel may be calculated by multiplying the pixel dimension (mm2) by the: |
|
Definition
|
|
Term
| In a modern CT system, the total number of possible Hounsfield values that may be assigned to any one pixel is approximately: |
|
Definition
|
|
Term
| The typical range for possible pixel values in a modern CT system is between: |
|
Definition
|
|
Term
| The human eye is capable of differentiating approximately __________ shades of gray |
|
Definition
|
|
Term
| A CT system measures the average linear attenuation coefficient of a voxel of tissue to be 0.189. The linear attenuation coefficient of water for this scanner equals 0.181. The CT number assigned to the pixel representing this voxel of tissue equals: |
|
Definition
|
|
Term
| A CT image is reconstructed using a 5122 matrix and a display field of view of 17 cm. What is the linear dimension of each pixel? |
|
Definition
|
|
Term
| The volume of a voxel may be calculated by multiplying the pixel dimension (mm2) by the: |
|
Definition
|
|
Term
| In a modern CT system, the total number of possible Hounsfield values that may be assigned to any one pixel is approximately: |
|
Definition
|
|
Term
| The typical range for possible pixel values in a modern CT system is between: |
|
Definition
|
|
Term
| The human eye is capable of differentiating approximately __________ shades of gray |
|
Definition
|
|
Term
| A CT system measures the average linear attenuation coefficient of a voxel of tissue to be 0.189. The linear attenuation coefficient of water for this scanner equals 0.181. The CT number assigned to the pixel representing this voxel of tissue equals: |
|
Definition
|
|
Term
| A CT image is reconstructed using a 5122 matrix and a display field of view of 17 cm. What is the linear dimension of each pixel? |
|
Definition
|
|
Term
Which of the following may be used for the archival storage of CT images?
1. CD-ROM
2. VHS tape
3. Magnetic optical disk |
|
Definition
|
|
Term
| The computer technique used to reduce the size and storage requirements of digital CT image data is called: |
|
Definition
|
|
Term
| __________ is the term used to describe the ability of a PACS to transmit data from the imaging facility to an off-site location |
|
Definition
|
|
Term
| Increasing the detector pitch during a spiral CT examination adversely affects the spatial resolution along which of the following? |
|
Definition
|
|
Term
| Which of the following would increase the signal-to-noise ratio of a CT image? |
|
Definition
|
|
Term
| The term __________ describes the ability of a CT scanner to differentiate objects with minimal differences in attenuation coefficients |
|
Definition
|
|
Term
Which of the following term(s) is/are commonly used to describe a CT scanner’s ability to differentiate objects with similar linear attenuation coefficients?
1. Spatial resolution
2. Sensitivity
3. Contrast resolution |
|
Definition
|
|
Term
| Which of the following types of image noise can be most easily reduced by the CT technologist? |
|
Definition
|
|
Term
| The ability of a CT scanner to image a small high-density object is controlled by the __________ of the scanner |
|
Definition
|
|
Term
Which of the following quality control tests should be performed daily on a CT scanner?
1. Check CT number calibration
2. Examine noise levels (standard deviation) of a water phantom
3. Test accuracy of laser localization device |
|
Definition
|
|
Term
| The largest deterrent of a CT scanner’s contrast resolution is: |
|
Definition
|
|
Term
| The spatial resolution of a CT scanner is often measured using the MTF of the system, which is an acronym for: |
|
Definition
| Modulation Transfer Function |
|
|
Term
| Areas of a CT image containing abrupt changes in tissue density are electronically represented by: |
|
Definition
|
|
Term
Which of the following technical adjustments would decrease the quantum noise of a CT image?
1. Increase mAs
2. Decrease section width
3. Increase section width |
|
Definition
|
|
Term
| A CT scanner with a limiting resolution of 15 lp/cm can resolve an object as small as: |
|
Definition
|
|
Term
Which of the following mathematical functions may be used to quantify the spatial resolution of a CT scanner?
1. PSF
2. MTF
3. LSF |
|
Definition
|
|
Term
| Which of the following would increase the noise apparent on a CT image? |
|
Definition
| Decrease in aperture size |
|
|
Term
| Which of the following adjustments in technical factors will result in an increase in spatial resolution? |
|
Definition
Increase in sampling frequency
The sampling frequency, or views per rotation (VPM), controls the volume of transmission data acquired for each gantry rotation. Very small objects exhibit high spatial frequencies that only systems with high sampling rates will be capable of resolving. |
|
|
Term
| The broadening of the slice sensitivity profile inherent to helical CT acquisition is said to negatively affect the: |
|
Definition
Longitudinal Spatial Resolution
Longitudinal spatial resolution describes the degree to which patient movement during volumetric acquisition can negatively affect image detail |
|
|
Term
| The degree of CT section broadening that occurs along the z-axis during volumetric data acquisition is represented graphically by the: |
|
Definition
| Slice Sensitivity Profile (SSP) |
|
|
Term
| The full width at half maximum (FWHM) of a slice sensitivity profile diagram indicates the: |
|
Definition
Effective Section Width
The effective section width is defined as the full width at half maximum (FWHM) of the SSP. It is measured by examining the slice sensitivity profile at half of its maximum height |
|
|
Term
Which of the following technical factors exhibits an effect upon longitudinal spatial resolution?
1. Detector pitch
2. Interpolation algorithm
3. Display field of view (DFOV) |
|
Definition
|
|
Term
| In 1917, Austrian mathematician __________ proved that it was possible to reconstruct a three-dimensional object from the infinite set of all of its projections |
|
Definition
|
|
Term
| Which of the following technical adjustments would result in a decrease in the signal-to-noise ratio (SNR)? |
|
Definition
| Reducing the section width |
|
|
Term
| Phantom measurement of the uniformity of a CT system is performed primarily to assess the negative effects of: |
|
Definition
|
|
Term
| Which of the following will serve to decrease the noise of a CT image? |
|
Definition
Decrease in matrix size
A decrease in matrix size will cause a subsequent increase in pixel dimension. This larger size causes an increase in the number of x-rays passing through each pixel, thereby increasing the signal-to-noise ratio. |
|
|
Term
| The term beam hardening is used to describe which of the following physical phenomena? |
|
Definition
The increase in average photon energy of a heterogeneous x-ray beam
Beam hardening occurs as the x-ray beam traverses the patient. The x-ray beam used in CT is composed of x-ray photons with numerous different energies. The heterogeneous beam undergoes an increase in average photon energy as it passes through the patient and the lower-energy photons are absorbed. |
|
|
Term
| Which of the following technical changes may increase the partial volume effect present on a spiral CT scan? |
|
Definition
Increase in pitch
When the pitch is increased during a spiral CT scan, either the section width or the table speed has been increased. The effects of increased section width on the partial volume effect are obvious. The increased table speed also plays a role in increasing partial volume averaging. Because the table moves through the gantry at a faster rate, each rotation of the tube and detectors is responsible for recording more information. This causes a broadening of the section sensitivity profile (SSP), which manifests as partial volume averaging. |
|
|
Term
| A CT image of a homogeneous material contains variations in CT number from pixel to pixel. This image is said to have: |
|
Definition
Noise
A CT image of a homogeneous material should have pixels with the same CT number. Any variation in CT number between pixels indicates that noise has entered the system, causing a loss in accuracy. |
|
|
Term
| The ability of the CT system to reduce involuntary motion artifacts and provide CT images free of motion artifact is determined by which of the following components of image quality? |
|
Definition
Temporal resolution
The stop-motion capability of a CT system is referred to as temporal resolution. Temporal resolution quantifies the CT system’s ability to freeze motion and to provide an image free of blurring. |
|
|
Term
Which of the following technical adjustments may be employed to improve the temporal resolution of an MDCT system?
1. Decreased scan time
2. Decreased section width
3. Decreased DFOV |
|
Definition
|
|
Term
| Which of the following components of the CT system is the most common cause of ring artifacts on the reconstructed CT image? |
|
Definition
Detector
Ring artifacts are typically caused by faulty detectors. An error in a detector results in the back-projection of an incorrect ring of density on the reconstructed CT image. |
|
|
Term
| Which of the following types of algorithms would be best suited to demonstrate the bony details of the shoulder joint in the figure? |
|
Definition
High spatial frequency
High spatial frequency algorithms demonstrate the greatest spatial resolution and are best suited for imaging sharp density changes, such as those occurring with bone tissue. Bone, edge, and detail are names commonly given to high spatial frequency algorithms. |
|
|
Term
| Which of the following is used to archive a hard copy of a CT image? |
|
Definition
|
|
Term
| Which of the following types of gas is commonly used for gas ionization CT detectors? |
|
Definition
|
|
Term
| For single-slice CT (SSCT) systems, which of the following statements regarding retrospective image reconstruction is FALSE? |
|
Definition
The slice thickness and SFOV may be changed
Retrospective reconstruction uses scan or "raw" data to change the matrix, DFOV, center, and/or algorithm used for a CT image. The slice thickness and SFOV are specifically used for data acquisition and cannot be altered retrospectively with a single-slice CT (SSCT) system. The advent of multidetector CT (MDCT) technology has made retrospective adjustments in section width possible. The scan field of view (SFOV) remains an item that may not be altered retrospectively.
Retrospective reconstruction uses scan or "raw" data to change the matrix, DFOV, center, and/or algorithm used for a CT image. The slice thickness and SFOV are specifically used for data acquisition and cannot be altered retrospectively with a single-slice CT (SSCT) system. The advent of multidetector CT (MDCT) technology has made retrospective adjustments in section width possible. The scan field of view (SFOV) remains an item that may not be altered retrospectively. |
|
|
Term
For a single-slice CT (SSCT) system, which of the following statements regarding pre-patient collimation is true?
1. An increase in pre-patient collimation increases patient radiation dose.
2. Pre-patient collimation is used to focus radiation through the section of interest
3. Pre-patient collimation directly controls slice thickness |
|
Definition
3 Only
Pre-patient collimation influences the slice thickness by reducing the size of the primary beam. This is accomplished with the use of lead shutters that absorb the outer margins of the primary beam. Increases in pre-patient collimation diminish patient radiation dose by reducing the number of x-ray photons that reach the patient. |
|
|
Term
| Which of the following is a typical protocol for a CT study of the brain for a patient with a history of dizziness? |
|
Definition
2.5-mm × 2.5-mm sections through the posterior fossa, 5 mm × 5 mm to vertex
Patients with histories of headaches and/or dizziness should be evaluated for abnormalities of the inner ear. Thin sections (1 to 3 mm) are required through the posterior fossa in order to best demonstrate the small anatomic structures and improve image quality. |
|
|
Term
| Which of the following describes the scout (localizer) projection used to prescribe an axial CT acquisition of the brain? |
|
Definition
Lateral
A lateral projection of the head, including from below the skull base through the vertex, is used as a scout image (scanogram) for a CT scan of the brain. CT systems utilizing automatic tube current modulation (ATCM) software may also require the acquisition of an anteroposterior (AP) scout or localizer projection. |
|
|
Term
| Which of the following is the primary interaction between x-ray photons and tissue during computed tomography? |
|
Definition
|
|
Term
| The assignment of different generations to CT scanners is based on the configuration of the: |
|
Definition
|
|
Term
| When one is using a third-generation CT scanner, it is important that reference detectors positioned at the peripheral portions of the detector array be exposed to: |
|
Definition
|
|
Term
| In 1979, the scientists __________ and __________ shared the Nobel Prize for their research in computed tomography |
|
Definition
|
|
Term
| The type of compensating filter used at the x-ray tube of a CT scanner is called a: |
|
Definition
|
|
Term
| The interaction between x-ray and matter that is responsible for the production of the scatter radiation absorbed by the patient and detectors is: |
|
Definition
|
|
Term
The types of detectors used in computed tomography are:
1. Gas ionization
2. Stimulable phosphor
3. Scintillation |
|
Definition
|
|
Term
| Which of the following is used in gas ionization CT detectors? |
|
Definition
|
|
Term
Which of the following statements concerning the translate-rotate mode of CT data acquisition is/are correct?
1. 360-degree circular detector arrays are used
2. Data are collected only during translation
3. Was used in first- and second-generation CT scanners |
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Definition
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| Which of the following terms accurately describes the type of x-ray beam used in a third-generation CT scanner? |
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Definition
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Which of the following technologic advances has led to the development of spiral/helical CT scanning?
1. Slip-ring technology
2. Electron beam technology
3. High-efficiency x-ray tubes |
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Definition
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| For a given CT acquisition, the calculated mAs applied to each reconstructed slice may be referred to as the: |
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Definition
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| The quantity of radiation dose received by the patient from a series of CT scans is referred to as the: |
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Definition
MSAD
The multiple-scan average dose (MSAD) is used to quantify the amount of exposure a patient receives from a series of CT scans. It is calculated from the computed tomography dose index (CTDI) through a series of equations. The quantity of radiation per scan is measured with an ionization chamber. |
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| Which of the following technical characteristics of a CT system does NOT directly affect patient dose? |
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Definition
Filament Size
Although they are beyond the control of the operator, the source-to-detector distance, filtration, and detector efficiency of a CT system all directly affect patient dose. The selected filament size does have geometric ramifications with regard to spatial resolution. A smaller filament results in improved spatial resolution. Patient dose is not affected by filament selection, provided that the mAs value remains constant. |
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| Which of the following statements most accurately describes the relationship between slice sensitivity profile (SSP) and dose profile? |
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Definition
The dose profile is always wider than the SSP
The term slice sensitivity profile (SSP) may be used to describe the reconstructed CT section. However, the section of tissue exposed to ionizing radiation, or dose profile, is greater in width than the SSP. |
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Term
| The approximate radiation dose measured during a scan of a 100-mm-long pencil ionization chamber is termed the: |
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Definition
CTDI(100)
CTDI100 is a fixed measurement taken with a 100-mm-long pencil ionization chamber inserted into an acrylic phantom. The CTDI100 standardizes the dose measurement from a single axial scan and can be used to compare doses from different scan techniques. |
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Term
| The calculation of the average cumulative dose to each section within an acquisition of multiple sections is termed the: |
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Definition
MSAD
The multiple-scan average dose (MSAD) is a calculation of the average cumulative dose to each section within the center of a scan consisting of multiple sections. Because of the contribution of scatter along the z-axis length of an acquisition, the MSAD for each section is higher than the dose from an acquisition of a single section. |
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Term
| The multiple-scan average dose (MSAD) is used to describe the: |
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Definition
Average dose to a single section within a scan of multiple sections
The multiple-scan average dose (MSAD) is used to quantify the average cumulative dose to each section within the center of a scan consisting of multiple sections. |
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| Which of the following units is used to quantify absorbed dose? |
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Definition
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| Which of the following units is used to quantify effective dose? |
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Definition
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| The acronym DLP is used to describe which of the following? |
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Definition
The radiation dose to the patient during a CT scan
Dose length product (DLP) is an internationally accepted measure of CT patient dose defined as: DLP = MSAD × slice width (cm) × No. of slices in scan volume. |
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| A best practice for the use of in-plane bismuth shielding requires the: |
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Definition
Placement of shield after the acquisition of scout (localizer) images
While in-plane bismuth shielding is designed to be used within the acquisition range, it should be placed on the patient after the localizer (scout) image(s) has/have been acquired. This is important for proper functioning of the automatic tube current modulation (ATCM) systems employed by modern CT scanners. |
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| Which of the following is the unit of radiation exposure? |
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Definition
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| When employing in-plane bismuth shielding, a thin spacer material may be positioned to reduce: |
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Definition
Streaking Artifact
A disadvantage of bismuth shielding is the streaking artifact that may occur on the image. A thin foam spacer may be placed between the patient surface and the bismuth shielding material to reduce the scatter artifact. |
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Term
A dose check system features which of the following?
1. Dose notification
2. Dose alert
3. Dose report |
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Definition
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| Current CT systems employ which of the following image reconstruction methods to reduce patient radiation dose? |
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Definition
Iterative reconstruction
Iterative reconstruction techniques may be used by a CT system to reduce patient dose. As compared with the standard filtered back-projection method of CT image reconstruction, iterative reconstruction can reduce image noise associated with the low-dose techniques employed to reduce patient exposure. |
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Term
| Current industry standards require that data related to the tube output during CT acquisition be documented in the RDSR which stands for: |
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Definition
| Radiation Dose Structured Report |
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Term
During CT data acquisition, the section of the patient exposed to radiation may be referred to as the:
1. Slice
2. Dose profile
3. Pitch |
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Definition
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Term
| Which of the following statements regarding CT image noise is TRUE? |
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Definition
| As patient size decreases, noise decreases |
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Term
| Which of the following describes the system that adjusts the mA setting according to part size variations along the z-axis? |
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Definition
Longitudinal tube current modulation
Longitudinal (z-axis) tube current modulation adjusts the mA setting as the scan proceeds along the z-axis of the patient. |
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| Which of the following descriptors accounts for the dose effects of image spacing during axial acquisition? |
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Definition
MSAD
MSAD accounts for the effects of image spacing, or bed index, on the patient dose during axial scanning. During axial scanning, overlapping scans increase the patient radiation dose, whereas gaps between slices decrease it. |
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Term
| The CT dose index (CTDI) is calculated for the central slice in a series that is surrounded by ______ slices on each side. |
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Definition
Seven
The CT dose index (CTDI) is an approximate measure of the dose received in a single CT section or slice. It is calculated for the central slice in a series that is surrounded by seven slices on each side. |
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Term
| When the slice thickness for a given CT acquisition equals the image spacing, the: |
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Definition
| MSAD is equal to the CTDI |
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Term
| The dose length product of a CT acquisition may be calculated as the product of the CTDIvol and the: |
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Definition
Scan Length
The DLP may be illustrated as the product of CTDIvol and scan length and is given in units of milligray-centimeters (mGy-cm). |
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Term
| A CT system may employ a focal spot tracking system to precisely direct the x-ray beam toward the detector array in an effort to reduce: |
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Definition
Overbeaming
Some CT manufacturers employ focal spot tracking systems to finely control the position of the x-ray beam on the detectors, reducing overbeaming and subsequent radiation exposure. |
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Term
| Iterative reconstruction of CT data reduces patient exposure by limiting image: |
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Definition
Noise
Iterative reconstruction techniques may be used by a CT system to reduce patient dose. As compared with the standard filtered back-projection method of CT image reconstruction, iterative reconstruction can reduce image noise associated with the low-dose techniques employed to reduce patient exposure. |
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Term
| The x-ray beam used in a multidetector CT system may be best described as a: |
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Definition
Cone Beam
To expose the widened detector array equally, MDCT utilizes a cone-shaped beam instead of the fan-shaped beam traditionally used by single-slice CT (SSCT) systems. |
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Term
| ______________ describes the overall ability of CT detectors to measure transmitted x-ray photons as it relates to their spatial arrangement within the gantry. |
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Definition
Geometric efficiency
The geometric efficiency of a detector array describes the spatial arrangement of detector elements, including the amount of interspace material required between adjacent elements. |
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Term
| During helical CT acquisition, there is a small amount of x-ray exposure just before and immediately following the anatomical volume of interest. This may be referred to as: |
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Definition
Overranging
Overranging occurs when radiation dose is applied before and after the acquisition volume to ensure sufficient data collection for the interpolation algorithms inherent in spiral CT. |
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Term
| When employing ECG-triggered tube current modulation during a cardiac CT, as the patient heart rate increases, the radiation dose savings: |
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Definition
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[image]
Which of the following window level and width settings were used to display this image? |
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Definition
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[image]
Which of the following is the best choice for scan field of view (SFOV) for the acquisition of the image in this figure? |
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Definition
Head (25cm)
The scan field of view (SFOV) chosen for any CT study must be larger than the anatomic part of interest. Specific scan field of view choices such as the head incorporate special correction factors for their respective anatomic areas and should be used when applicable. |
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Term
| Which of the following conditions or indications would not require the injection of iodinated contrast material for proper visualization during a CT examination of the brain? |
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Definition
S/P MVA 3 days ago; R/O subdural hematoma
Subdural hematomas caused by relatively recent trauma appear as hyperdense areas on CT images of the brain. Intravenous iodinated contrast media is not necessary for their visualization and may act to conceal them. Contrast media are extremely valuable for visualization of intracranial tumors. |
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Term
| A stereotactic unit would be used for which of the following specialized CT examinations? |
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Definition
CT-guided biopsy of the brain
Stereotactic biopsy units are specialized units designed specifically for CT-guided biopsies. They are most commonly used for intracranial lesions, for which precision and accuracy are extremely important. |
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Definition
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Term
| Which of the following most accurately describes the proper position of the patient for a CT examination of the brain? |
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Definition
Supine with chin down
CT images of the brain should be acquired parallel to the skull base. Placing the patient in the supine position with the chin down facilitates the axial acquisition at an angle 15 degrees above the infraorbitomeatal line (IOML) |
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Definition
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Definition
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Term
| In which of the following cranial nerves would an acoustic neuroma be found? |
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Definition
Eighth
An acoustic neuroma (schwannoma) arises from Schwann cells of the eighth cranial nerve, or the vestibulocochlear nerve. This type of cranial mass may be imaged with CT examinations of the internal auditory canals. |
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Term
| Which of the following types of pathologic conditions cannot be easily diagnosed from a CT scan of the brain? |
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Definition
| Alzheimer’s disease is not easily diagnosed from a CT scan of the brain. Alzheimer’s disease may present with enlargement of the temporal horns but this is typically not specific on CT examinations. |
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Term
[image]
This type of image is referred to as a(n): |
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Definition
MPR Image
Multiplanar reformation (MPR) describes the process of displaying CT images in a different orientation from the one used in the original reconstruction process. MPR images may be constructed in the coronal, sagittal, or any other two-dimensional plane. MPR images are typically formed from a vertical stack of contiguous, helically acquired axial CT images. |
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Definition
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Term
[image]
Number 3 indicates that this image was generated from a series of __________ CT images. |
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Definition
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Term
| In an effort to reduce radiation exposure to the orbits during a CT examination of the brain, the gantry may be angled: |
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Definition
15 degrees superior to the infraorbital-meatal line (IOML)
Acquisition for a brain CT may be performed at an angle 15 degrees above the IOML, parallel to the skull base, to reduce orbital radiation dose and minimize beam-hardening artifact. |
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Term
Unless the use of iodinated contrast media is contraindicated, which of the following pathologic conditions require(s) the administration of such media for optimal visualization on CT examination?
1. Suspected neoplasm
2. Arteriovenous malformation (AVM)
3. Acute hemorrhage |
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Definition
1 & 2
Noncontrast CT examinations of the brain are routinely indicated to diagnose intracranial hemorrhage or hematoma, because contrast enhancement may mask subtle signs of hemorrhage. |
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Term
High-resolution CT examinations of the temporal bones and internal auditory canal should include which of the following technical parameters?
1. 5- to 7-mm section width
2. Small (less than 10 cm) targeted DFOV
3. Soft-tissue kernel |
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Definition
2 Only
CT studies of the temporal bones and internal auditory canal require a high-resolution imaging technique. The tenets of high-resolution CT include thin sections (1 to 2 mm), a small targeted DFOV, and the use of a high-resolution algorithm (kernel) for reconstruction. |
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Term
Which of the following technical parameters is NOT a necessary component of a high-resolution CT examination of the internal auditory canals (IAC)?
1-mm section width
Targeted 10-cm DFOV
Sagittal MIP Images
Bone Algorithm |
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Definition
Sagittal MIP Images
CT studies of the temporal bones and internal auditory canal require a high-resolution imaging technique. The tenets of high-resolution CT include thin sections (1 to 2 mm), a small targeted DFOV, and the use of a high-resolution algorithm (kernel) for reconstruction. |
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Definition
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[image]
Name the anatomical plane |
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Definition
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[image]
Name the anatomical plane |
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Definition
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Definition
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Definition
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Definition
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Definition
| Partially calcified choroid plexuses of the posterior horns of the lateral ventricles |
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Definition
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Term
| Multiplanar reformation (MPR) images along the long axis of the optic nerve would be best described by which of the following anatomic planes? |
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Definition
Oblique sagittal
The optic nerve runs along a lateral-to-medial path from the orbit anteriorly and to the optic chiasma posteriorly. Oblique sagittal MPR images will demonstrate the optic nerve in a profile parallel to its long axis. |
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Term
Which of the following may be used to reduce metal streak artifact on coronal-plane CT images of the orbits?
1. Retrospective reconstruction of targeted images with reduced display field of view (DFOV)
2. Metallic artifact reduction (MAR) software to improve image quality
3. Construction of coronal multiplanar reformation (MPR) images from the acquired axial-plane images |
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Definition
2 & 3 Only
Volumetric MDCT axial acquisition through the orbits, sinuses, and so on allows for high-quality coronal MPR images without metal streaking artifact. CT manufacturers may offer metallic artifact reduction (MAR) software in an effort to reduce streaking artifact from metal substances. Targeted reconstructions would eliminate only the streak artifact at the periphery of the field and would not remove unwanted streak artifact appearing through the area(s) of interest. |
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Term
| Coronal imaging through the paranasal sinuses is typically performed with the plane of imaging: |
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Definition
| Perpendicular to the hard palate |
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Term
Which of the following statements accurately describes the effects of administering an iodinated IV contrast agent during Imaging Procedures of the brain?
1. The contrast agent increases the attenuation values for normal gray matter.
2. The contrast agent improves the differentiation of subtle hemorrhage.
3. The contrast agent enhances neoplasms that have disrupted the blood–brain barrier. |
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Definition
1 & 3 Only
During CT imaging for suspected intracranial bleeding, contrast administration is initially contraindicated because the associated enhancement may mask subtle signs of hemorrhage. |
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Term
Which of the following is NOT a component of the blood supply to the brain commonly referred to as the circle of Willis?
Right middle cerebral artery
Left posterior communicating artery
Anterior communicating artery
Left posterior cerebral artery |
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Definition
Right middle cerebral artery
The circle of Willis is composed of the anterior cerebral, anterior communicating, internal carotid, posterior cerebral, and posterior communicating arteries. The basilar artery and middle cerebral arteries are important vessels supplying blood to the brain, but they do not form a part of the circle of Willis. |
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Term
Which of the following methods may be used to determine the appropriate injection delay for optimal vessel enhancement during a CTA examination of the brain?
1. Measuring the patient’s pulse rate
2. Performing a bolus-timing sequence
3. Utilizing bolus-tracking software |
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Definition
2 & 3 Only
Although pulse rate may provide an indication of the patient’s overall cardiac function, it is not utilized to determine injection delays for angiographic Imaging Procedures. Empiric delays, bolus-timing sequences, and bolus-tracking software may all be used to accurately acquire CTA studies during peak vasculature enhancement. |
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Term
| During a CTA of the brain’s circle of Willis, if an iodinated contrast agent is injected at a rate of 3 to 4 mL/sec, an adequate delay for optimal vessel opacification would be in the range of: |
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Definition
12 to 20 seconds
An empiric delay of 12 to 20 seconds would be adequate to ensure good vessel opacification of the circle of Willis. |
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Term
| Evaluation of the venous vascular structures of the brain is known as: |
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Definition
CT venography
CT venography (CTV) of the brain is a variation of the CTA technique whereby the timing of data acquisition is optimized for the period of peak venous opacification. |
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Term
| The primary indication for CT perfusion of the brain is: |
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Definition
Acute Stoke
CT perfusion (CTP) evaluates cerebral perfusion by monitoring the initial passing of iodinated contrast media through the vasculature of the brain. The primary indication for CTP is in the evaluation of acute stroke. |
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Term
| During CT perfusion studies, the quantity of blood (in mL) contained within 100 g of brain tissue is termed the: |
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Definition
Cerebral blood volume (CBV)
Cerebral blood volume (CBV) describes the quantity of blood (in mL) contained within a 100-g volume of brain tissue. Normal range is 4 to 5 mL/100 g. |
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Term
| During CT perfusion studies, the measured time (in seconds) required for blood to pass through an area of brain tissue is termed the: |
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Definition
Mean Transit Time (MTT)
Mean transit time (MTT) describes the average time, in seconds, for blood to pass through a given region of brain tissue. MTT varies with the distance traveled between arterial inflow and venous outflow for a particular area. |
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Term
| Which of the following correctly illustrates the central volume principle of cerebral perfusion? |
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Definition
CBF = CBV/MTT
The central volume principle is described by the formula CBF = CBV/MTT. It illustrates the relationship of cerebral blood flow as a factor of the volume of blood within a given area of brain tissue and the time it takes for that blood to pass through the area. Reduced CBF may indicate ischemia resulting from stroke or other brain abnormalities. |
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Term
| The normal range of cerebral blood flow (CBF) through 100 g of the brain’s gray matter is: |
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Definition
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Term
| The normal range of cerebral blood volume (CBV) contained within 100 g of brain tissue is: |
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Definition
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Term
| Ischemic brain tissue is identified as an infarct core when cerebral blood volume (CBV) falls below: |
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Definition
2.5 mL/100 g
Brain parenchyma with a CBV less than 2.5 mL/100 g is identified as the infarct core |
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Term
| The type of hemorrhage that occurs between the skull and outer layer of the dura in traumatic brain injury is referred to as a(n): |
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Definition
Epidural Hematoma
An epidural hematoma occurs between the skull and the outermost meningeal covering of the brain called the dura mater. Subdural hematomas occur between the dura mater and the next inner layer of the meninges, known as the arachnoid. The innermost layer of the meninges is called the pia mater. |
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Term
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Definition
| Left Common Carotid Artery |
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Term
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Definition
| Right Internal Jugular Vein |
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Term
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Definition
| Sternocleidomastoid muscle |
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Definition
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Definition
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Definition
| Pharyngeal constrictor muscle |
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Definition
| Right external carotid artery |
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Term
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Definition
| Left common carotid artery |
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Term
[image]
Which of the following pathologic conditions could be exhibited by the structure labeled as number 3? |
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Definition
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Term
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Definition
| Right internal jugular vein |
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Term
| The tortuous S-shaped portion of the internal carotid artery as it enters the bony skull may be referred to as the carotid: |
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Definition
Siphon
Carotid siphon refers to the portion of the internal carotid artery as it enters the bony skull and bifurcates into the anterior cerebral and middle cerebral arteries. |
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Term
| Which of the following patient positions is best suited for CT evaluation of the chest? |
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Definition
Supine
CT examinations of the chest usually require that the patient be placed in the supine position. Patients may also be scanned in the prone position, to increase aeration of the posterior lung base, or in a lateral decubitus position, to help differentiate certain types of pathology. |
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Term
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Definition
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Term
| Which of the following types of CT scanners is best suited for the evaluation of coronary artery disease? |
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Definition
Electron beam CT (EBCT)
Electron beam CT (EBCT) scanners are designed to acquire information at an extremely rapid rate. With the use of electron beam technology, these ultrafast CT systems can greatly reduce cardiac and pulmonary motion, allowing detailed evaluation of anatomic areas such as the coronary arteries. |
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Term
| High-resolution computed tomography (HRCT) of the chest incorporates which of the following protocols? |
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Definition
1-mm sections, bone algorithm
High-resolution computed tomography (HRCT) of the chest is used to examine diffuse pulmonary disease. This technique offers excellent visualization of the lungs, airways, and pulmonary hilum. HRCT involves the use of narrow sections (1 to 3 mm) and a high-resolution algorithm. |
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Term
| A solitary pulmonary nodule can be assumed benign when its average density is within which of the following ranges? |
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Definition
165-200 HUs
Pulmonary nodules appearing on CT examinations of the lungs may be determined as benign if their average density is more than +164 Hounsfield units. Although there have been conflicting studies in this area, researchers tend to agree that density values approaching +200 HU make the benign diagnosis more certain. |
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Term
Which of the following contrast media may be used during a CT examination of the chest?
1. Diatrizoate meglumine
2. Barium sulfate
3. Iopamidol |
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Definition
1, 2, & 3
Diatrizoate meglumine is an ionic intravenous contrast material, and iopamidol is a nonionic one. Both may be used for soft-tissue enhancement during CT of the chest. A barium sulfate contrast agent, usually in the form of a paste, may also be used to outline the esophagus, when necessary. |
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Term
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Definition
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Term
| The __________ gland is located in the anterosuperior portion of the mediastinum and is often identified with CT during scanning of younger patients |
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Definition
Thymus
The thymus gland may be found in the anterosuperior portion of the mediastinum. It is most easily visible prior to puberty. After puberty it becomes increasingly infiltrated with fat, so it is more difficult to image with computed tomography |
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Term
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Definition
| Right Brachiocephalic Vein |
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Term
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Definition
| Left Common Carotid Artery |
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Definition
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Term
[image]
Which of the following algorithm type, matrix size, and section thickness parameters were used for the image? |
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Definition
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Term
[image]
Which of the following technical changes would serve to improve the quality of the image? |
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Definition
Decrease DFOV size
The image was reconstructed in a DFOV larger than necessary. The image appears minified because of this error. The DFOV chosen for an image should be slightly larger than the diameter of the area of interest. The DFOV used here was 48 cm. This image would appear significantly larger with a DFOV of 36 to 40 cm. |
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Term
Which of the following improvements in CT chest imaging is a direct result of the advent of multidetector CT (MDCT)?
1. Reduction in misregistration artifacts
2. Increased examination speed
3. Reduction in patient dose |
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Definition
1 & 2
Speed is one of the key attributes of helical MDCT. The ability to volumetrically acquire images of the entire chest in a single breath-hold has greatly reduced the occurrence of misregistration artifacts. For many applications, MDCT may result in greater patient radiation dose than single-slice CT (SSCT) |
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Term
| Which of the following is NOT an improvement in CT chest imaging because of the development of multidetector technology? |
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Definition
An overall reduction in patient radiation dose
The speed of MDCT systems allow for images of the entire chest to be volumetrically acquired in just a few seconds. Fast, single-breath-hold acquisitions greatly reduce artifacts from breathing motion and allow for more efficient utilization of iodinated contrast agents. The ability to retrospectively reconstruct thin-section images can effectively eliminate the partial volume artifact on small areas of pathology. The drawback to MDCT is the potential for an increase in overall patient radiation dose. However, careful protocol optimization and continued technologic advancements work to limit any increases in patient radiation dose from MDCT examinations. |
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Term
| For general contrast-enhanced MDCT of the chest, sufficient opacification of vascular structures can be typically obtained with injection rates of: |
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Definition
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Term
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Definition
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Term
| During HRCT of the lungs, image acquisition upon full expiration may be performed to improve demonstration of: |
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Definition
Air trapping from COPD
Suspension of breathing at the end of forced expiration (static expiratory HRCT) may be utilized to demonstrate air trapping in patients with suspected small airway disease, such as chronic obstructive pulmonary disease (COPD), and emphysema |
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Term
Primary technical considerations for a CTA of the chest to rule out pulmonary embolism include:
1. Short acquisition in a single breath-hold from diaphragm to lung apex
2. Bolus injection of iodinated contrast agent at 4 to 5 mL/sec
3. Portal-phase acquisition at 60 to 70 seconds |
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Definition
1 & 2
CTA acquisition for pulmonary embolism must occur during peak contrast enhancement of the pulmonary arteries. Test bolus and automated bolus tracking methods are available to ensure appropriate scan delay for acquisition during the arterial phase of vessel opacification. Additional technical parameters include thin-section (0.5 to 1.25), caudocephalad acquisition with the use of a saline flush immediately following the administration of 80 to 150 mL of low-osmolar or iso-osmolar contrast media. |
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Term
| Why is it recommended that data acquisition for a CTA of the pulmonary arteries be performed in the caudocephalad direction? |
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Definition
Less streaking artifact from dense contrast in the superior vena cava
Scanning is best performed in the caudocephalad direction because there is reduced streaking artifact from dense contrast in the superior vena cava as the scan progresses. Also, if the patient is unable to hold the breath for the entire scan, motion artifacts are reduced higher in the chest. |
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Term
| Following a CTA of the chest for pulmonary embolism, an additional acquisition may be performed through the lower extremities to evaluate for: |
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Definition
| Deep Vein Thrombosis (DVT) |
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Term
| For a given CTA examination of the pulmonary arteries, 100 mL of a low-osmolar iodinated contrast agent is administered at a rate of 4 mL/sec. Peak pulmonary artery opacification should occur at approximately: |
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Definition
20-25 Seconds
Empiric scan delays for CTA of the pulmonary arteries vary between 20 and 25 seconds. Peak contrast opacification of the pulmonary arteries depends heavily on the rate of injection and the cardiac output of the patient. Performing a test bolus sequence and utilizing bolus-tracking software are valuable methods of ensuring that acquisition occurs during the period of maximum vessel opacification. |
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Term
| The primary indication for a noncontrast cardiac MDCT examination is: |
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Definition
| Coronary Artery Calcium Quantification |
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Term
| Prospectively gated cardiac CT data acquisition occurs only during the portion of the ECG termed the: |
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Definition
T-Wave
With prospective electrocardiography (ECG) monitoring, scanning only occurs during diastole, when the heart demonstrates the least motion. A user-defined percentage of the R-R interval is set as the trigger for data acquisition to occur during the T wave of the ECG. |
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Term
| For MDCT, identified areas of calcium must demonstrate relative attenuation values greater than: |
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Definition
+130 HU
On MDCT cardiac examinations for coronary artery calcification (CAC) quantification, areas of calcium are identified as those greater than 1 mm2 in area with Hounsfield values above 130. |
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Term
| An Agatston score of 250 on an MDCT cardiac examination for coronary artery calcification is rated as: |
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Definition
Moderate
The Agatston scoring system quantifies coronary artery calcium as minimal (1 to 10), mild (11 to 100), moderate (101 to 400), and extensive (>400). |
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Term
| An Agatston score of 5 on an MDCT cardiac examination for coronary artery calcification is rated as: |
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Definition
Minimal
The Agatston scoring system quantifies the volume and density of calcium within the coronary arteries. A score of 1-10 is minimal. A score between 11-100 is mild. A score between 101-400 is moderate. A score greater than 400 is extensive. |
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Term
| In patients who are right dominant, the posterior descending artery branches from the: |
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Definition
Right Coronary Artery (RCA)
85% of the population is said to be right dominant, meaning that the posterior descending artery (PDA) branches from the right coronary artery (RCA) |
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Term
| In patients who are left dominant, the posterior descending artery branches from the: |
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Definition
Left Circumflex Artery
8% of the population is said to be left dominant, meaning that the posterior descending artery (PDA) branches from the left circumflex artery (LCX). |
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Term
| Patients whose posterior descending artery branches from the right coronary artery and whose left posterior ventricular branches arise from the left circumflex artery, are said to be: |
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Definition
Codominant
7% of the population is said to be codominant, meaning that the posterior descending artery (PDA) is supplied by the right coronary artery (RCA), and the left posterior ventricular branches arise from the left circumflex artery (LCX). |
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Term
| Which of the following conditions absolutely prohibits a patient from undergoing a coronary CTA? |
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Definition
| Contraindication to iodinated contrast agents |
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Term
The branches of the left coronary artery include the:
1. Sinus node artery
2. Left anterior descending artery
3. Left circumflex artery |
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Definition
|
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Term
| During a coronary artery CTA, single-segment reconstruction of a 400-msec rotation scan results in a temporal resolution of: |
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Definition
200 msec
During single-segment, or half-scan reconstruction, data from only half a gantry rotation is used, resulting in a temporal resolution equal to one half the gantry rotation time. |
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Term
| The primary advantage of prospective ECG gating for cardiac CT over retrospective ECG gating is: |
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Definition
| The main benefit of prospective ECG gating is the potential for up to a 70% reduction in patient radiation dose. Prospective ECG gating requires a steady heartbeat to limit motion artifact, and the evaluation of cardiac function is not possible because data is acquired only during diastole. |
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Term
| The Stanford type B dissecting aneurysm affects which portion of the aorta? |
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Definition
| Stanford type B dissecting aneurysms affect the descending aorta. Stanford type A dissecting aneurysms affect the ascending aorta. |
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Term
| During prospectively ECG-gated cardiac CTA studies, the scanning acquisition mode may be best described as: |
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Definition
Axial "step-and-shoot."
During prospective ECG-gated cardiac CTA, data are acquired in an axial "step-and-shoot" mode. The x-ray and data acquisition systems are activated only during the diastolic portion of the R-R interval. Retrospective ECG gating involves a volumetric helical acquisition with only the diastolic portion of the data used for image reconstruction. Cine CT involves a series of acquisitions of a limited area over time. Routinely used in perfusion CT studies, cine acquisitions may have certain cardiac applications, such as the evaluation of valves, specific vessels, and cardiac perfusion. |
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Term
| The quantity of blood pumped out of a ventricle every heartbeat is termed the: |
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Definition
|
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Term
| On axial CT images of the chest, the region between the ascending aorta and descending aorta just below the aortic arch is commonly referred to as the: |
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Definition
| Aortic-pulmonary (AP) window |
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Term
| By CT criteria, a solitary pulmonary nodule may be defined as a focal area of increased density in the lung that is smaller than: |
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Definition
3 cm
Solitary pulmonary nodules are typically ovoid focal areas of increased density that are less than 3 cm in diameter. Any lesion larger than 3 cm is referred to as a focal mass, with an increased propensity for malignancy. |
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Term
| The exaggeration of displayed calcification within the coronary arteries during a cardiac MDCT study is referred to as: |
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Definition
Blooming
Blooming refers to the potential overestimation of vessel calcification because of partial volume artifact. During cardiac MDCT studies, blooming may be somewhat mitigated by improving the spatial resolution of a given acquisition or choosing an appropriately wide window setting (1500 HU) to reduce the appearance of the artifact. |
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Term
Differentiation between the duodenum and head of the pancreas is best accomplished with:
1. An oral contrast agent administered 30 to 45 minutes prior to scanning
2. Pre- and post-contrast images of the abdomen
3. Placement of the patient in the right lateral decubitus position prior to scanning |
|
Definition
1 & 3
The duodenum and pancreatic head are often difficult to distinguish. This is one important reason why the small bowel must be properly opacified. To accomplish adequate opacification, an oral contrast agent should be administered at least 30 minutes prior to scanning. Positioning the patient in a right lateral decubitus position is also helpful in ensuring opacification of the duodenum, which surrounds the pancreatic head. |
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Term
| __________ is a term that refers to an excessive amount of nitrogenous materials in the blood and is a symptom of renal failure |
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Definition
Azotemia
Azotemia describes the condition of excessive nitrogenous materials in the blood. This condition is also commonly called uremia. Azotemia is a symptom of renal insufficiency and may occur during chronic renal failure. |
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Term
| CT images of the abdomen should be acquired with the patient: |
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Definition
At full expiration
Suspended respiration at the end of full expiration is the most reproducible point in the respiratory cycle. It results in less misregistration artifact during CT examinations of the abdomen. |
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Term
| Following the intravenous administration of iodinated contrast media, a hepatic hemangioma may become __________ and may no longer appear on the CT image |
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Definition
Isodense
The diagnosis of hemangioma is confirmed on CT by evaluation of its pattern of enhancement. Hemangiomas enhance from the periphery inward, until they become isodense with the surrounding hepatic tissue. Once isodense, the hemangioma attenuates the beam in the same way as the hepatic tissue. The CT numbers of the hemangioma and hepatic tissue become equal and the structures may become impossible to differentiate. |
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Term
| Which of the following would most likely require the intravenous injection of an iodinated contrast agent for accurate differentiation during a CT study of the abdomen? |
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Definition
Renal Cyst
The diagnosis of simple cyst is accurately made with proper CT examination. Pre- and post-contrast images must be obtained to measure enhancement. The attenuation values for the cystic area should be at or near zero. The diagnoses of angiomyolipoma, renal stone, and diverticulitis can be made without the intravenous injection of contrast material. |
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Term
| The presence of outpocketings in the wall of the colon is referred to as: |
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Definition
|
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Term
| Often seen in pediatric patients, a specific type of renal mass arising from immature kidney cells is referred to as: |
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Definition
Wilm's Tumor
Wilms tumor is a specific type of renal mass that develops from immature renal parenchyma. It may also be referred to as nephroblastoma and occurs in pediatric patients, usually between ages 1 and 5 years. |
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Term
| During a CT examination of the abdomen including intravenous administration of an iodinated contrast agent, which of the following abnormal findings could appear hyperdense in comparison with surrounding tissue? |
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Definition
Gallstone
Owing to their relatively high CT numbers, gallstones usually appear hyperdense in comparison with the bile-filled gallbladder. Some gallstones having lower attenuation values can appear isodense on a CT scan of the abdomen. |
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Term
| CT-guided needle biopsies are most commonly performed on which of the following anatomic areas? |
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Definition
|
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Term
| Which of the following sets of reconstructed section widths and intervals would be best suited for a general survey CT study of the abdomen and pelvis in a patient with a history of lymphoma? |
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Definition
5.0mm X 5.0mm
General survey CT studies for lymphoma are typically performed contiguously with section widths ranging from 3.0 to 5.0 mm for routine review. Data acquisition with an MDCT system may involve the use of a thinner detector configuration, such as 0.625 mm. Thicker section widths are reconstructed for review, with thinner images used for multiplanar reformation (MPR) or for areas of specific concern. |
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Term
| The water-soluble oral contrast agents used for CT scans of the abdomen and pelvis should contain approximately __________ iodine. |
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Definition
2%-5%
A solution of 2% to 5% iodinated water-soluble contrast agent and water provides sufficient bowel opacification for CT studies of the abdomen and pelvis. Some institutions may use a flavored contrast agent or add a flavoring agent to the solution for ease of consumption. Common water-soluble contrast media include Gastrografin and Hypaque. |
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Term
Which of the following statements is true concerning CT scans of the abdomen for the differentiation of renal cysts?
1. Acquisitions through the kidneys should be performed before and after administration of an IV contrast agent.
2. ROI measurements of the cyst should be made to help determine its composition.
3. The patient should refrain from urination for 2 hours prior to the examination. |
|
Definition
|
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Term
| Which of the following abnormal findings will reduce the density of the liver? |
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Definition
Fatty infiltrate
The density of the liver decreases with the presence of fatty infiltrates. The minimal attenuation of fat and its low CT number cause an overall decrease in the attenuation and CT number of the hepatic parenchyma. |
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Term
| CT scanning of the liver for tumor evaluation should NOT be performed during which of the following phases of contrast enhancement? |
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Definition
Equilibrium phase
Contrast enhancement is at its lowest point during the equilibrium phase. This phase is apparent when the aorta and inferior vena cava differ by less than 10 HU. It is during this phase that hepatic lesions may become isodense with the surrounding hepatic parenchyma. Noncontrast scanning of the liver is actually preferred to scanning during the equilibrium phase. |
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Term
| The kidneys are usually located anatomically between which vertebrae? |
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Definition
|
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Term
| The majority of pancreatic tumors occur in the pancreatic: |
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Definition
|
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Term
| The majority of pancreatic tumors are |
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Definition
|
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Term
| Normal unenhanced hepatic parenchyma exhibits CT densities within the range of: |
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Definition
+15 to +30 HU
Normal unenhanced hepatic parenchyma is homogenous in appearance with CT densities between +45 and +65 Hounsfield units (HU). The CT density of the unenhanced liver is normally slightly greater than the densities of blood vessels and the splenic parenchyma. |
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Term
| Which of the following is an example of a hypovascular hepatic mass? |
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Definition
Hepatic cyst
The hallmark CT finding for a cyst is lack of enhancement with IV contrast agent administration. Cysts are therefore characterized as hypovascular. Hemangiomas, hepatocellular carcinomas (HCC), focal nodular hyperplasia (FNH), and certain metastatic lesions are all examples of hypervascular tumors of the liver. |
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Term
Malignant neoplasms of the liver include which of the following?
1. Focal nodular hyperplasia (FNH)
2. Cavernous hemangioma
3. Hepatocellular carcinoma (HCC) |
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Definition
3 Only
Hepatocellular carcinoma (HCC) and metastases are the most common malignant neoplasms of the liver. Hemangiomas and focal nodular hyperplasia (FNH) are both examples of benign hepatic tumor. |
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Term
Contrast enhancement phases of the liver include which of the following?
1. Corticomedullary
2. Arterial
3. Portal venous |
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Definition
2 & 3 Only
The primary hepatic phases of contrast enhancement are the arterial, portal venous, and equilibrium phases. The early arterial and delayed phases of hepatic enhancement are also noted. |
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Term
| After initiation of rapid bolus administration of an iodinated contrast agent, the hepatic venous phase of contrast enhancement occurs at approximately: |
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Definition
60-70 Seconds
The hepatic (or portal) venous phase is the period of peak hepatic parenchymal enhancement during which contrast material redistributes from the blood into the extravascular spaces. It occurs at approximately 60 to 70 seconds after the initiation of rapid bolus administration of a contrast agent. |
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Term
| After initiation of rapid bolus administration of an iodinated contrast agent, the early arterial phase of hepatic contrast enhancement occurs at approximately: |
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Definition
15-20 Seconds
Occurring at 15 to 20 seconds after the initiation of contrast administration, the early arterial phase of contrast enhancement is the optimal phase for angiographic applications of liver CT. During this phase, the hepatic arterial supply is well opacified with little or no parenchymal enhancement. |
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Term
| The period of peak hepatic parenchymal enhancement following rapid bolus injection of iodinated contrast is termed the: |
|
Definition
Portal Venous Phase
The portal (or hepatic) venous phase is the period of peak hepatic parenchymal enhancement during which contrast material redistributes from the blood into the extravascular spaces. It occurs at approximately 60 to 70 seconds after the initiation of rapid bolus contrast administration. |
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Term
| The presence of stones within the gallbladder is termed: |
|
Definition
Cholelithiasis
The condition of stones within the gallbladder is referred to as cholelithiasis. Choledocholithiasis is the presence of gallstones within the bile ducts. |
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|
Term
| The hallmark CT finding for focal nodular hyperplasia (FNH) of the liver is: |
|
Definition
Central scar that remains hypodense after initial contrast agent administration
Focal nodular hyperplasia (FNH) is a common vascular lesion often identified along the surface of the liver. It is characterized by intense homogeneous enhancement with contrast agent administration. There is usually a central scar that remains hypodense until delayed imaging, when it may also enhance. |
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Term
| Portal venous phase imaging of the liver is used to optimally demonstrate which of the following? |
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Definition
| Hypovascular hepatic metastases |
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Term
During post-contrast CT imaging of the abdomen, the degree of hepatic parenchymal enhancement depends on:
1. The iodine concentration of the contrast agent
2. The rate if contrast agent injection
3. The osmolality of the contrast medium |
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Definition
1 & 2 Only
The extent of hepatic parenchymal enhancement depends on the overall dose of iodine delivered. The iodine dose may be increased directly by utilizing a contrast agent with a higher concentration, or indirectly by increasing the injection rate. |
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Term
| The approximate CT density of the unenhanced spleen is: |
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Definition
|
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Term
| Which of the following phases of contrast enhancement optimally demonstrates the relationship between pancreatic neoplasm and the surrounding vasculature? |
|
Definition
Arterial phase
During arterial phase acquisition through the pancreas, there is maximum opacification of the surrounding vasculature, including the aorta and superior mesenteric artery. An important goal of pancreatic CT is to evaluate the involvement of surrounding vessels by pancreatic neoplasm. |
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Term
| Which of the following technical considerations is necessary to differentiate hydronephrosis from parapelvic cysts on CT examination? |
|
Definition
Administration of an iodinated IV contrast agent
Parapelvic cysts are simple cysts arising within the renal pelvis. They are similar in appearance to the distention of the pelvis and calyces known as hydronephrosis. Delayed imaging after IV contrast agent administration opacifies the renal pelvis, clearly differentiating hydronephrosis from parapelvic cysts. |
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Term
| After initiation of rapid bolus administration of an iodinated contrast agent, the corticomedullary phase of renal contrast enhancement occurs at approximately: |
|
Definition
30 to 40 seconds
The corticomedullary phase is a late arterial phase beginning 30 to 40 seconds after the initiation of contrast agent administration. Optimal enhancement of the renal cortex and renal veins occurs during this period. |
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|
Term
| After initiation of rapid bolus administration of an iodinated contrast agent, the excretory phase of renal contrast enhancement occurs at approximately: |
|
Definition
3 to 5 minutes
The excretory phase is a delayed-imaging phase that begins approximately 3 minutes after the initiation of contrast agent administration. During this phase, contrast material has been excreted into the renal calyces, opacifying the renal pelvis and the remainder of the urinary collecting system (ureters, bladder). The excretory phase best demonstrates the filling defects and potential lesions involving the urothelium, such as those from transitional cell carcinoma (TCC) |
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|
Term
| The period of peak enhancement of the renal cortex following rapid bolus injection of an iodinated contrast agent is termed the: |
|
Definition
Corticomedullary phase
The corticomedullary phase is a late arterial phase beginning 30 to 40 seconds after the initiation of contrast agent administration. Optimal enhancement of the renal cortex and renal veins occurs during this period |
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|
Term
| Which of the following phases of renal contrast enhancement provides maximum sensitivity for parenchymal lesions? |
|
Definition
Nephrographic
During the nephrographic phase, enhancement between renal cortex and medulla reaches equilibrium, providing optimal sensitivity for parenchymal lesions. The nephrographic phase occurs between 70 and 90 seconds after the start of injection. |
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Term
| An abnormal connection between the intestine and an adjacent anatomic structure is called a(n): |
|
Definition
Fistula
A fistula is an abnormal connection between the intestine and an adjacent structure. Fistulas are commonly associated with inflammatory bowel disease. |
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Term
| Which of the following phases of IV contrast agent administration provides the best gastric and intestinal wall enhancement? |
|
Definition
|
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Term
| Which of the following oral contrast agents offers the best visualization of the enhancing GI wall on post-IV contrast CT examination? |
|
Definition
Water
Water as a negative oral contrast agent improves visualization of the enhancing enteral wall when an IV contrast agent is administered. Other agents, such as VoLumen and milk, may also be effective as agents capable of distending the bowel while allowing for wall visualization. |
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Term
| The term appendicolith is applied to which of the following pathologic conditions of the appendix? |
|
Definition
|
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Term
| Assuming a bolus injection of iodinated contrast agent at a rate of at least 4 mL/sec, an appropriate scan delay for a CTA examination of the mesenteric vasculature would be in the range of: |
|
Definition
20 to 30 seconds
Dual-phase imaging including the arterial phase (20 to 30 seconds) and portal venous phase (60 to 70 seconds) is typically performed for complete evaluation of the mesenteric vasculature. The use of bolus-tracking software or test bolus technique is recommended to ensure appropriate scan timing |
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Term
| An IV contrast enhanced specialized CT evaluation of the small bowel after the oral administration of a low-density (0.1%) barium sulfate solution is termed: |
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Definition
CT enterography
CT enterography does not involve contrast agent administration through a nasogastric tube and is therefore less invasive than CT enteroclysis |
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Term
| During CT colonography examinations, tagged fecal matter appears __________ on the image |
|
Definition
White
Dual-agent tagging involves the oral administration of both barium and water-soluble iodinated contrast agent. The barium tags residual stool and coats the surface of polyps. The iodine contrast tags residual fluid. Tagged fluid and fecal matter exhibit high CT density and appear white on the CTC image. Tagging allows for differentiation of polyp from fecal matter and improves the visualization of polyps that may be surrounded by residual fluid |
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|
Term
| The oral administration of barium and iodinated contrast media prior to CT colonography serves the primary purpose of: |
|
Definition
Polyp tagging
Dual-agent tagging involves the oral administration of both barium and water-soluble iodinated contrast. The barium tags residual stool and coats the surface of polyps. The iodine contrast tags residual fluid. Tagged fluid and fecal matter exhibit high CT density and appear "white" on the CTC image. Tagging allows for differentiation of polyp from fecal matter and improves the visualization of polyps that may be surrounded by residual fluid |
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Term
Which of the following contrast agents may be used for the purpose of colon insufflation during a CT colonography examination?
1. Room air
2. CO2
3. Normal (0.9%) saline |
|
Definition
1 & 2
Colon insufflation involves the introduction of room air or carbon dioxide into the colon for the purpose of bowel wall distention |
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|
Term
Which of the following is an advantage of automatic CO2 insufflation for CT colonography?
1. Cheaper cost
2. Lower risk of anaphylaxis
3. Lower risk of perforation |
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Definition
3 Only
Advantages of automatic CO2 insufflation include better overall distention and lower risk of perforation. Also, owing to the faster absorption rate of CO2, there is a reduction in post-procedural discomfort in the patient |
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|
Term
Advantages of automatic CO2 insufflation for CT colonography include:
1. Better distention
2. Lower risk of perforation
3. Improved patient comfort |
|
Definition
|
|
Term
| Which of the following window settings would optimally display CT colonography images? |
|
Definition
Level= −400, width= 1600
CT colonography images are best displayed in a wide "lung-type" window setting |
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Term
| The portion of the male reproductive system responsible for storage of the majority of mature sperm is the: |
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Definition
|
|
Term
Which of the following scan parameters is commonly used during a radiation therapy planning CT study of the prostate gland?
1. Patient placed on a flat tabletop
2. Small DFOV used to include only the prostate gland
3. CT scan performed with patient in exact position used for radiation treatment |
|
Definition
1 & 3 Only
CT scans are commonly performed for radiation therapy planning. The purpose of the examination is to precisely locate the area of interest for therapeutic treatment with irradiation. It is important that the patient position during the CT examination is exactly the same as that used during radiation therapy. This includes using a flat tabletop, via a board or foam insert. Equally important is the DVOV chosen by the technologist. It must be large enough to include the entire surface of the anatomic part |
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|
Term
Which of the following types of contrast material may be used during CT evaluation of the pelvis?
1. An intravenous iodinated contrast agent
2. Low dense barium sulfate solutions
3. Oil-soluble contrast material |
|
Definition
1 & 2
During CT examination of the pelvis, both intravenous and oral contrast agents are commonly administered. An intravenous contrast agent is important in differentiating pelvic blood vessels from lymph nodes. An oral contrast agent serves to opacify the small and large colon and greatly improves their visualization. Oil-based contrast media are not commonly used for CT Imaging Procedures |
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|
Term
Which of the following are reasons why intravenous contrast is administered during CT evaluation of the pelvis?
1. Distention and contrast enhancement of the bladder
2. Visualization of the rectosigmoid junction
3. Differentiation of blood vessels and pelvic lymph nodes |
|
Definition
1 & 3
Intravenous contrast agent administration during a CT examination of the pelvis is valuable for several reasons. The bladder is easily visualized when filled with contrast material, and differentiation between blood vessels and enlarged pelvic lymph nodes is improved. The rectosigmoid junction may be better visualized once opacification has been attained through the use of oral or enema administration of a contrast agent |
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Term
| Which of the following algorithm types would provide the greatest soft tissue detail during a CT study of the pelvis? |
|
Definition
Low spatial frequency
Low spatial frequency algorithms are usually referred to as standard or soft tissue algorithms. They filter out high spatial frequency information, such as that pertaining to bone, and provide maximum details of soft tissue structures |
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Term
| Which of the following correctly describes the position of the seminal vesicles in the male pelvis? |
|
Definition
| Posterior to the bladder and anterior to the rectum |
|
|
Term
| Which layer of the uterine wall brightly enhances after IV administration of an iodinated contrast agent? |
|
Definition
| Myometrium (Highly vascular) |
|
|
Term
| A dermoid tumor of the ovary may also be referred to as a: |
|
Definition
Cystic teratoma
A dermoid cyst is a mature cystic teratoma that is characterized on CT imaging by areas of widely varying densities including fat, fluid, and calcifications |
|
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Term
| Axial CT sections of the lumbar spine for intervertebral disk evaluation should be reconstructed with the plane of imaging: |
|
Definition
Parallel to the plane of the intervertebral disk spaces
For best demonstration of lumbar vertebral disk spaces, the plane of imaging should be parallel to the plane of the disk spaces. This may be accomplished with individual axial acquisitions through each disk space with the gantry angled parallel to the plane of the intervertebral disk. With the volumetric acquisition capabilities of MDCT, multiplanar reformation (MPR) images may be reconstructed from a single complete data set acquired with a perpendicular gantry position |
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|
Term
| Which of the following sets of section widths and intervals is best suited for a CT examination of the cervical spine to rule out intervertebral disk herniation? |
|
Definition
1.25 mm × 1.25 mm
Contiguous acquisition with narrow slice thickness is preferred during CT examination of the cervical spine. Section widths of 1.25 mm or less should be used with no gap or even an overlap, thus ensuring thorough evaluation of the relatively small intervertebral disk spaces |
|
|
Term
| Quantitative computed tomography (QCT) is a specialized technique used most often for the diagnosis of: |
|
Definition
Osteoporosis
Quantitative computed tomography (QCT) is used to measure the mineral content of bone. Density measurements of the patient’s bone are compared with density measurements of a reference phantom. The bone mineral density (BMD) values are compared with normal values to assess osteoporosis |
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|
Term
| Which of the following would be a suitable range for contrast agent volume for an intrathecal injection during a postmyelogram CT examination of the lumbar spine in an adult patient? |
|
Definition
12 to 14 mL
A common range of contrast agent volume for an intrathecal injection during post-myelographic CT is 12 to 14 mL in an adult patient. The total volume should not exceed approximately 17 mL, so as to keep the iodine dose below 3 g |
|
|
Term
| Which of the following display fields of view (DFOV) should be chosen for a CT examination of the thoracic spine on a patient whose thorax measures 40 cm? |
|
Definition
15 cm
During a CT examination of the spine, the display field of view should be one that displays the spine enlarged on the monitor. Commonly referred to as targeting, this technique provides the viewer with an enlarged image of the spine without the loss of detail that accompanies magnification of the CT image. Although in this example the patient measures 40 cm, the DFOV of 15 cm will be sufficient to target the spine and enlarge its image on the viewing monitor |
|
|
Term
| A portion of a herniated intervertebral disk that has migrated from its normal position is called a(n): |
|
Definition
|
|
Term
| The degenerative pathologic process of the spine known as spondylolysis involves a defect in the: |
|
Definition
|
|
Term
| Malignant tumors of the skeletal system include _______, ________, and ______ _______ |
|
Definition
| Osteosarcoma, Chondrosarcoma, & Multiple Myeloma |
|
|
Term
| During IV contrast agent administration for peripheral CTA examinations, the bolus duration should be equal to the scan time minus: |
|
Definition
5 Seconds
The duration of scan acquisition for peripheral CTA will be based on the anatomic length of the study and the capabilities of the particular CT system in use. Faster scanners run the risk of "outrunning" the bolus by completing the acquisition before the entire contrast volume has been administered. Bolus duration, or the time required to inject a specific volume of contrast, may be calculated as the product of injection flow rate and total contrast agent volume. The subtraction of 5 seconds allows the scanner to maintain pace with the contrast agent as it moves down the aorta and results in the cessation of contrast agent administration just prior (5 seconds) to the end of data acquisition |
|
|
Term
| The most common indication for CT-guided radiofrequency ablation (RFA) is in treatment of neoplasms involving the: |
|
Definition
|
|
Term
| The detectors of a PET system absorb and measure what type of radiation? |
|
Definition
Annihilation photons
Annihilation photons are emitted from the radionuclide F-18-fluorodeoxyglucose (FDG) that has been taken up by the tumor cells. PET detectors absorb the emitted photons, measuring the activity of a given area of potential malignancy |
|
|
Term
The role of computed tomography during combined PET-CT includes:
1. Anatomic location of tumor activity
2. Attenuation correction of emitted photons
3. Reduction of overall patient dose |
|
Definition
1 & 2 Only
The process of attenuation correction utilizes the transmission data acquired in the corresponding CT analysis to account for the change in energy that occurs as annihilation photons emitted from decaying radionuclide travel through the patient. The CT image data is utilized for tumor localization and results in an increase in patient dose. |
|
|
Term
| What is the maximum allowable blood glucose measurement for patients scheduled to undergo PET-CT examination? |
|
Definition
150 mg/dL
The patient’s blood glucose may be measured prior to the injection of F-18-fluorodeoxyglucose (FDG). It should be below 150 mg/dL to prevent FDG uptake inhibition by glucose circulating in the bloodstream. |
|
|
Term
| The typical dose of the radiopharmaceutical F-18-fluorodeoxyglucose (FDG) for combined PET-CT examination is within the range of: |
|
Definition
|
|
Term
| During combined PET-CT imaging, abnormal physiologic uptake of radiopharmaceutical can occur in patient muscle because of: |
|
Definition
Strenuous Activity
Strenuous physical activity can cause abnormal physiologic uptake of FDG in muscle. Therefore, the patient is instructed to avoid such activity prior to the injection and during the delay for imaging. In addition, all patient activity and speech are limited for up to 60 minutes after the injection of FDG. |
|
|
Term
The purpose of intravenous contrast agent administration during a CT study is to:
1. Increase the contrast between adjacent structures
2. Increase the overall image density
3. Increase beam attenuation of enhanced structures |
|
Definition
|
|
Term
| The excretion half-time of intravenous iodinated contrast media in a patient with normal renal function is between: |
|
Definition
1 & 2
Excretion half-time is a value describing the amount of time necessary for 50% of the contrast agent administered to be filtered by the renal system. In patients with normal renal function, the half-time is usually between 1 and 2 hours. |
|
|
Term
| A common formula used to calculate dosage of intravenous iodinated contrast material in the pediatric patient is: |
|
Definition
|
|
Term
Which of the following may be considered as advantages of spiral/helical CT over conventional CT scanning?
1. Reduced scan time
2. Reduction of misregistration artifacts
3. Decreased patient radiation dose |
|
Definition
|
|
Term
Which of the following technical factor(s) play(s) a role in the production of an isotropic data set?
1. Section width
2. Scan field of view (SFOV)
3. Display field of view (DFOV) |
|
Definition
|
|
Term
| CTA of the renal arteries should be performed using a section width of: |
|
Definition
|
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Term
| Axial CT images of the knee may be acquired in four separate series with gantry angulations of 0, 30, 45, and 60 degrees in order to demonstrate the: |
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Definition
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Term
| On an ECG of the complete cardiac cycle, at which portion of the R-R interval is the heart muscle in diastole? |
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Definition
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Term
| Which of the following protocols would provide the best image quality for a 3-D disarticulation study of the hip? |
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Definition
Overlapping 1.5-mm-thick sections, bone algorithm
Three-dimensional studies are best performed with the use of narrow sections acquired with no spacing (contiguous) or, preferably, with a reconstruction an overlap (e.g., 1.5-mm-thick section reconstructed every 1.0 mm). A detail (bone) algorithm is used for optimal demonstration of bony structures. |
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Term
| Which of the following sets of section width and spacing would be most suitable for a general survey CT of the neck? |
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Definition
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Term
| Which of the following technical maneuvers may be used to remove unwanted pulsation artifacts from cardiac motion during a CTA of the chest for pulmonary embolism? |
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Definition
Automatic tube current modulation
Electrocardiographic (ECG) gating can be utilized to eliminate pulsation artifacts because of cardiac motion during the study. Retrospective gating involves scanning throughout the entire cardiac cycle. Only data from specific user-determined portions of the ECG waveform are reconstructed into images. |
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Term
| The ideal scan field of view (SFOV) for a CT examination of the cervical spine would be: |
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Definition
50.0 cm
Acquisition of the cervical spine is performed with a large SFOV, 48 to 50 cm. Targeted reconstructions are made using a display field of view (DFOV) between 10 and 15 cm. Larger DFOV reconstructions may be used to retrospectively display a greater anatomic area as clinical indication dictates. Utilizing a SFOV that is too small for the lower cervical spine region (shoulder girdle) would result in an out-of-field artifact. |
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Term
Vascular components of the brain’s blood supply known as the circle of Willis include the:
1. Internal carotid arteries
2. Basilar artery
3. Anterior communicating artery |
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Definition
1 & 3 Only
The circle of Willis is composed of the anterior cerebral, anterior communicating, internal carotid, posterior cerebral, and posterior communicating arteries. The basilar artery is an important vessel supplying blood to the brain, but it is not part of the circle of Willis. |
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Term
Retrospective ECG gating utilizes which of the following portions of the cardiac cycle for image reconstruction?
1. Atrial systole
2. Ventricular systole
3. Cardiac diastole |
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Definition
3 Only
Complete cardiac diastole is the period of relaxation after heart contraction. Diastole is the portion of the cardiac cycle when coronary artery motion is the slowest and cardiac motion is at its lowest. For evaluation of the coronary arteries, the MDCT system utilizes only the diastolic portion of the acquisition in the reconstruction process. |
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Term
| An enema is indicated prior to a CT examination of the pelvis to administer positive contrast material into the large bowel. Which of the following dosages would be sufficient to opacify the rectosigmoid region? |
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Definition
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Term
| The Stanford type A dissecting aneurysm affects which portion of the aorta? |
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Definition
Ascending thoracic
Stanford type A dissecting aneurysms affect the ascending aorta. Stanford type B dissecting aneurysms affect the descending aorta. |
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Term
Often evaluated during body CTA examinations, the branches of the celiac axis are the:
1. Left gastric artery
2. Common hepatic artery
3. Splenic artery |
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Definition
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Term
Vital components of a CT urogram (CT-IVP) protocol include:
1. Administration of 1200 to 1500 mL of a positive oral contrast agent 90 minutes prior to examination
2. Thin-section excretory phase imaging of the entire urinary tract
3. Volume-rendered 3-D and maximum intensity projection (MIP) imaging of the urinary tract |
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Definition
2 & 3
Water is the preferred oral contrast material for CT urograms, because its use avoids the interference seen with denser materials when one is producing volume-rendered and MIP images. Additional protocol considerations include pre-contrast acquisition of the urinary tract and post-contrast nephrographic phase imaging. Excretory phase imaging occurs after a delay of 5 to 15 minutes and may be aided by the IV drip administration of approximately 250 mL of normal (0.9%) saline to improve urinary tract opacification. |
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