Which of the following sets of reconstructed section widths and intervals would be best suited for a general CT study of the Abdomen and Pelvis in a patient with a history of lymphoma?

A. 0.625 mm x 0.625 mm

B. 1.25 mm x 2.5 mm

C. 5.0 mm x 5.0 mm

D. 10 mm x 15 mm

Answer: C. 5.0 mm x 5.0 mm

General Survey CT studies for lymphoma are typically performed contiguously with section widths ranging from 3.0 mm to 5.0 mm for routine review. Data acquistion 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.

Which of the following is NOT an improvement in CT chest imaging due to the development of multidetector technology?

A. An overall reduction in patient radiation dose

B. Reduction in Partial Volume Artifact

C. Elimination of misregistration Artifact

D. Improved Contrast enhancement

Answer: A. An overall reduction in Patient radiation dose

The speed of MDCT systems allow for image s of the entire chest to be volumetrically acquired in just a few seconds. Fast, single-breath-hold acquistions greatly reduce artifact 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 technological advancements work to limit any increase in dose from MDCT exams.

[image]

Number 3 Corresponds to which of the following?

A. External Iliac Artery

B. Femoral Artery

C. External Iliac Vein

D. Femoral Vein

An Agaston Score of 250 on an MDCT cardiac examination for Coronary Artery calcification is rated as:

A. Minimal

B. Mild

C. Moderate

D. Extensive

Answer: C. Moderate

The Agaston system quantifies coronary artery calcium as minimal (1-10), mild (11- 100), moderate (101-400), and extensive (>400).

Number 2 corresponds to which of the following?

A. Anterior Cerebral Artery

B. Third Ventricle

C. Fourth Ventricle

D. Optic Tract

[image]

Which of the following scan parameters is commonly used during a radiation therapy planning CT study of the prostate gland?
(1) Patient placed on flat table top

(2) Small DFOV used to include only the prostate gland

(3) CT scan performed with patient in exact position used for radiation treatment

A. 1 only

B. 1 and 3 only

C. 2 and 3 only

D. 1, 2, and 3

Answer: B. 1 and 3 only

CT scans are commonly performed for radiation therapy planning. The purpose of the exam is to precisely locate the area of interest for therapeutic treatment with irradiation. It is important that the patient position during the CT exam is exactly the same as that used during radiation therapy. This includes using a flat table top, via a board or foam insert. Equally important is the DFOV chosen by the technologist. It must be large enough to include the entire surface of the anatomic part.

In 1979, the scientists ___________ and ____________ shared the Nobel Prize for their research in Computed Tomography.

A. Watson and Crick

B. Olendorf and Hounsfield

C. Hounsfield and Cormack

D. Hounsfieild and Ambrose

Answer: C. Hounsfield and Cormack

Dr. Godfrey Hounsfield and Dr. Allan Cormack shared the Nobel prize for their work on the development of computed tomography in 1979.

The portion of the primary beam interacting with a single detector is known as a:

A. Ray

B. View

C. Profile

D. Sample

Answer: A. Ray

The term ray is used to describe the portion of the xray beam that falls upon a single detector.

The addition of _______ makes an auto clave more efficient at sterilization than an oven.

A. Antiseptic solution

B. moisture

C. Extreme pressure

D. Ultraviolet light

Answer: B. Moisture

An autoclave is a mechanical device used for sterilization. It involves the use of heat and steam under pressure to eliminate microbes. An oven only uses high heat and is not as efficient as an autoclave.

Which of the following components of CT image quality is/are being evaluated?

(1) linearity

(2) section width

(3) spatial resolution

A. 1 only

B. 1 and 2 only

C. 3 and 3 only

D. 1, 2, and 3

[image]

Answer: B. 1 and 2 only

A linearity phantom contains 4 inserts of various materials surrounded by water. Known ranges or CT values are compared with those obtained by CT acquisition to ensure system accuracy and linearity. This American College of Radiology (ACR) phantom also contains two ramps consisting of a series of wires spaces 0.5 mm apart along the phantoms z-axis. The accuracy of the selected section width is evaluated by counting the number of wires visable in cross-section.

Infection may occur indirectly through contact with contaminated objects known as:

A. Vectors

B. Fomites

C. Vehicles

D. hosts

Answer: B. Fomites

Fomites are objects that have been contaminated by an infectious organism or microbe. The spread of the infection may occur when someone comes in contact with the fomite. This is an indirect means of infection transmission.

Which of the following units is used to quantify effective dose?

A. Roentgens (R)

B. Grays (Gy)

C. Sieverts (Sv)

D. Curies (Ci)

Answer: C. Sieverts (Sv)

Effective dose approximates the relative risk from exposure to ionizing radiation and is based on the radiosensitivity of a given tissue type. It is measured in Sieverts (Sv).

The ability of a CT scanner to image a small high density object is controlled by the __________ of the scanner.

A. Contrast Resolution

B. Spatial Resolution

C. Sensitivity

D. Both A and C

Answer: B. Spatial Resolution

The spatial resolution of a CT scanner controls its ability to image small structures.

The normal range of Cerebral blood volume (CBV) contained within 100 g of Brain Tissue is:

A: 0.6-1.0 mL/100 g

B. 4-5 mL/100 g

C. 15-19 mL/100 g

D. 30-40 mL/100 g

Answer: B. 4-5 mL/100 g

Number 2 corresponds with which of the following?

A. Incus

B. Cochlea

C. Semicircular Canal

D. Vestibule

[image]

The type of MSCT detector array that contains midline narrow elements flanked by wider detectors is called a(n):

A. Uniform Matrix Array

B. Adaptive Array

C. Hybrid Array

D. Stationary Array

Answer: C. Hybrid Array

A hybrid array consists of two detector sizes. The narrower detectors are positioned midline, flanked by the wider detectors. For example, the central rows of a 16-channel MDCT system are 0.625 mm with the remaining peripheral rows at 1.25 mm.

Number 1 corresponds with which of the following?

A. Ileum

B. Cecum

C. Jejunum

D. Duodenum

[image]

Which of the following azimuth settings was used to produce the localizer image?

A. 0 Degrees

B. 90 Degrees

C. 180 Degrees

D. 270 Degrees

[image]

Answer: A. 0 Degrees

The azimuth setting refers to the relationship between the x-ray tube and detectors during scout or localizer production. A 0-Degree azimuth describes the situation in which the x-ray tube and the detectors do not rotate but remain above and below the patient, providing a frontal projection.

The role of computed tomography during combined PET-CT includes:

(1) anatomic location of tumor activity

(2) attenuation correction of emitted photons

(3) reduction in overall patient dose

A. 1 only

B. 1 and 2 only

C. 2 and 3 only

D. 1, 2, and 3

Answer: B. 1 and 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.

Following the injection of intravenous contrast media during a CT examination of the brain, which of the following anatomic areas does not enhance?

A. Anterior communicating artery

B. Choroid plexus

C. Posterior horn of lateral ventricle

D. Dura Mater

Answer: C. Posterior Horn of Lateral Ventricle

The posterior horn of the lateral ventricle contains cerebrospinal fluid and does not enhance following the intravenous administration of contrast material. Areas with a good blood supply, such as the cranial blood vessels, choroid plexus, and dura mater do enhance during a contrast study of the brain.

The degenerative pathologic process of the spine known as spondylolysis invloves a defect in the:

A. Spinous Process

B. Transverse Process

C. Pars interarticularis

D. Intervertebral disc

Answer: C. Pars Interarticularis

Spondylolysis involves a defect in the pars interarticularis commonly caused by osteophyte formation. The pars interarticularis is the area of the vertebrae between the inferior and superior articular processes ( neck of the "scotty dog").

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

A. 1 only

B. 3 only

C. 1 and 2 only

D. 2 and 3 only

Answer: D. 2 and 3 only

The ability of a CT scanner to accurately image objects with similar densities is termed contrast resolution or sensitivity. A CT scanner with poor contrast resolution or low sensitivity has difficulty seperating tissues whose linear attention coefficients are nearly equal.

Normal unenhanced hepatic parenchyma exhibits CT densities within the range of:

A. -20 to 0 HU

B. +15 to +30 HU

C. +45 to +65 HU

D. +80 to +105 HU

Answer: C. +45 to +65 HU

Normal unenhanced hepatic parenchyma is homogenous in apperance 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.

The approximate radiation dose measured during a scan of 100-mm pencil ionization chamber is termed the:

A. MSAD

B. Effective dose

C. CTDIvol

D. CTDI

Answer: D. CTDI

CTDI is a fixed measurement taken with a 100-mm long pencil ionization chamber inserted into an acrylic phantom. The CTDI standardized the dose measurement from a single axial scan and can be used to compare doses from different scan techniques.

The stanford type B dissecting aneurysm affects which portion of the aorta?

A. Ascending Thoracic

B. Descending Thoracic

C. Abdominal

D. Birfurcation

Answer: B. Descending Aorta

Stanford type B dissecting aneurysms affect the descending aorta. Stanford Type A dissecting aneurysms affect the ascending aorta.

Parenteral contrast administration refers to which of the following?

A. Oral Administration

B. Rectal administration

C. Intravenous administration

D. Nasogastric administration

Answer: C. Intravenous administration

The injection of a medication or contrast agent directly into the bloodstream is a type of parenteral administration. Other parenteral routes include intramuscular, subcutaneous, intradermal, and intrathecal.

Which of the following is not a category of isolation technique?

A. Enteric precautions

B. gram-negative isolation

C. Contact isolation

D. Strict Isolation

Answer: B. gram-negative isolation

The categories of isolation technique are: Drainage-secretion precautions; acid-fast bacillus isolation; respiratory isolation; contact isolation; and strict isolation.

A solitary pulmonary nodule can be assumed benign when its average density is within which of the following ranges?

A. 10-30 HU

B. 45-80 HU

C. 100-140 HU

D. 165-200 HU

Answer: D. 165-200 HU

Pulmonary Nodules appearing on CT examinations of the lungs may be determined as benign if their average density is more that 164+ HU. 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.

Which of the following window settings would optimally display CT colonography images?

A. Level= -400, width= 1600

B. Level= +50, width= 400

C. Level= +150, width= 1000

D. Level= +250, width= 4000

Answer: A Level= -400, width= 1600

CT colonography images are best displayed in a wide "lung-type" window setting.

Parenteral routes of medication administration include which of the following?

(1) subcutaneous

(2) intradermal

(3) transdermal

A. 1 only

B. 1 and 2 only

C. 2 and 3 only

D. 1, 2, and 3

Answer: B. 1 and 2 only

Parenteral routes of medication administration include intramuscular, intravenous, intradermal, and subcutaneous.

The portion of the male reproductive system responsible for the storage of the majority of mature sperm is the:

A. Seminal Vesicles

B. Vas Deferens

C. Testes

D. Prostate Gland

Answer: B. Vas Deferens

The majority of mature sperm is stored in the Vas Deferens. Sperm is produced in the seminiferous tubules and passes through the epididymus, where a small amount may be stored.

A Stereotactic unit would be used for which of the following specialized CT examinations?

A. CT-guided fine-needle aspiration of an abdominal abscess

B. 3D CT angiogram

C. CT-guided biopsy of the brain

D. Dual window scanning

Answer: C. CT-guided biopsy of the brain

Steriotactic biopsy units are specialized units designed specifically for CT-guided biopsies. They are most commonly used for intercranial lesions, for which precision and accuracy are extremely important.

Number 5 Corresponds to which of the following?

A. Duodenum

B. Descending Colon

C. Jejunum

D. Ascending Colon [image]

Which of the following vessels would not be used as a site for the injection of Iodinated contrast material?

A. Cephalic Vein

B. Brachial Artey

C. Antecubital vein

D. Basilic Vein

Answer: B. Brachial Artery

Common sites for intravenous contrast injection include the antecubital, basilic, cephalic, and accessory cephalic veins. Intrarterial injections of contrast material are not routinely performed for CT examinations. The only exceptions occur during hepatic CT portography, in which contrast agent may be administered through a catheter placed in the hepatic, superior mesentaric, or splenic artery.

Which of the following is a typical protocol for a CT study of the brain for a patient with a history of dizziness?

A. 10-mm x 10-mm sections from the skull base through the vertex

B. 7-mm x 7-mm sections from the skull base through the posterior fossa

C. 2.5-mm x 2.5-mm sections through the posterior fossa, 5 mm x 5 mm to vertex

D. 1.5-mm x 1.5-mm sections from skull base to vertex

Answer: D. 2.5-mm x 2.5-mm sections through the posterior fossa, 5 mm x 5 mm to vertex

Patients with histories of headaches and/or dizziness should be evaluated for abnormalities of the inner ear. Thin sections (1-3 mm) are required throught the posterior fossa in order to best demonstrate the small anatomic structures and improve image quality.

The spatial resolution of a CT scanner is usually given in the unit of measure:

A. HU

B. lp/cm

C. µ

D. Hz

Answer: B. lp/cm

The spatial resolution of a scanner quantifies its ability to visually seperate small objects in the image. The unit used to describe the spatial resolution is tested by scanning a phantom with an embedded resolution test pattern consisting of a series of small lead lines the decrease in size and spacing. The smallest, most closely spaces set of lead lines is said to be the spatial resolution of the CT scanner. A line pair (lp) consists of one lead line and a space immeiately next to it.

The graph represents which of the following?

A. modulation transfer function (MTF)

B. signal-to-noise ratio (SNR)

C. views per rotation (VPR)

D. Slice Sensitivity profile (SSP) [image]

Answer: Slice Sensitivity profile (SSP)

The section width (slice) for a volumetric acquisition may be graphically displayed as a slice sensitivity profile (SSP). The SSP represents the degree of broadening that occurs along the z-axis during volumetric data acquisition.

The typical range for possible pixel values in a modern CT system is between:

A. -512 HU and +512 HU

B. -1000 HU and +1000 HU

C. -1024 HU and +3071 HU

D. -4096 HU and +4096 HU

Answer: C. -1024 HU and +3071 HU

The typical range of Hounsfield scale CT numbers is -1024 to +3071 HU. This range equals the 4096 different values possible when one is using a 12-bit system. (212=4096)

The duodenum is suspended from the diaphragm by the:

A. ligamentum teres

B. diaphragmatic crus

C. falciform ligament

D. ligament of Treitz

Answer: D. Ligament of Treitz

The suspensory ligament of the diaphragm is commonly referred to as the ligament of Treitz.

Number 5 corresponds to which of the following?

A. iliopsoas muscle

B. sartorius muscle

C. obtruator internus muscle

D. gluteus minimus muscle [image]

The quantity of radiation dose recieved by the patient from a series of CT scans is reffered to as the:

A. MSAD

B. XCAL

C. CTDI

D. MTF

Answer: A. MSAD

The multiple-scan average dose (MSAD) is used to quantify the amount of exposure a patient recieves 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.

During a Coronary Artery CTA, single-segment reconstruction of a 400-msec rotation scan results in a temperal resolution of:

A. 100 msec

B. 200 msec

C. 400 msec

D. 800 msec

Answer: B. 200 msec

During single-segment, or half-scan reconstruction, data from only half a gantry rotation is used, resulting in a temperal resolution equal to one-half the gantry rotation time.

The dimensions of a voxel may be calculated as the product of which of the following?

A. matrix size and pixel size

B. Pixel size and section width

C. DFOV and matrix size

D. DFOV and pixel size

Answer: B. pixel size and section width

The pixel is a two-dimensional representation of a vocel. The section width is equal to the length of the voel. To calculate the dimensions of a voxel, the pixel dimension must be multiplied by the section width.

Pixel x section width= voxel

An injury to the brain at a location opposite to the site of tramatic impact is referred to as:

A. Coup

B. Contracoup

C. Subdural

D. Epidural

Answer: B. Contracoup

The contracoup type of acute brain injury occurs at a location on the opposite side of the head from the point of impact. As he moving skull rapidly decelerates prior to impact, the portion of the brain opposite to the impact site temporarily pulls away from the skull before forcibly recoiling back into its original position, resulting in tramatic injury. In comparison, coup injuries to the brain occur at the actual site of tramatic impact.

Number 1 corresponds to which of the following?

A. renal artery

B. hepatic vein

C. superior mesenteric artery

D. celiac trunk

[image]

Which of the following mathmatical functions may be used to quantify the spatial resolution of a CT scanner?

(1) PSF

(2) MTF

(3) LSF

A. 2 only

B. 1 and 2 only

C. 2 and 3 only

D. 1, 2, and 3

Answer: D. 1, 2, and 3

The line spread function (LSF), point spread function (PSF), and modulation transfer function (MTF) are each used to quantify the spatial resolution of a CT scanner. The LSF measures the ability of a CT scanner to clearly image an edge or a line. The PSF does the same for extremely small, point-like structures. The MTF examines the fidelity of the spatial frequency as it represents tissues with varying densities. The MTF is derived from the measurement of LSF and PSF.

Which of the following is an advantage of automatic CO insufflation for CT- Colonography?

(1) cheaper cost

(2) lower risk of anaphylaxis

(3) lower risk of perforation

A. 1 only

B. 3 only

C. 1 and 2 only

D. 2 and 3 only

Answer: B. 3 only

Advantages of automatic CO insufflation include better overal distention and lower risk of perforation. Also, owing to the faster absorption rate of CO, there is a reduction in post-procederal discomfort in the patient.

Number 1 corresponds to which of the following?

A. external iliac artery

B. femoral artery

C. External iliac vein

D. Femoral vein

[image]

Number 1 corresponds with which of the following?

A. corpus callosum

B. internal capsule

C. septum pellucidum

D. Putamen

[image]

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

A. 1 only

B. 1 and 2 only

C. 2 and 3 only

D. 1, 2, and 3

Answer: A. 1 only

Temporal resolution quantifies the CT system ability to freeze motion and provide an image free of blurring. The controlling factors of temporal resolution of a CT system are the gantry rotation speed and reconstructin method.

Which of these numbers correspond to the genu of the corpus collosum?[image]

The water-soluble oral contrast agents used for CT scans of the abdomen and pelvis should contain approximately__________ iodine.

A. 2%-5%

B. 8%-12%

C. 15%-20%

D. 25%-40%

Answer: A. 2%-5%

A solution of 2%-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 flavoring agent to the solution or used a flavored contrast for ease of consumption. Common water-soluble contrast media include gastrografin and hypaque.

The primary advantage of an isotropic MDCT data-set is:

A. reduced scan time

B. increased signal-to-noise ration (SNR)

C. improved raw data convolution

D. high-quality multiplanar reformations (MPR)

Answer: D. high-quality multiplanar reformations (MPR)

An isotropic volumetric data set yeilds high-quality images with equal resolution in any reconstucted plane. Reconstruction of isotropic, overlapping, thin-section MDCT images greatly reduces the "step" artifact that can negatively affect the quality of MPR and 3D CT images.

The number, length, and organization of the individual detector elements in an MSCT system are referred to as the:

A. detector configuration

B. array pitch

C. CT generation

D. detector pitch

Answer. A. detector configuration

Detector configuration refers to the number, length, and organization of the individual detector elements in an MSCT system.

Prospectively gated cardiac CT data acquisition occurs only durning the portion of the ECG termed the:

A. P wave

B. QRS complex

C. ST Segment

D. T wave

Answer: D. 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 intercal is set as the trigger for data acquisition to occur during the T wave of the ECG.

High-resolutino CT examinations of the temporal bone 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

A. 1 only

B. 2 only

C. 1 and 3 only

D. 1, 2, and 3

Answer: B. 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 (1-2 mm), a small targeted DFOV, and the use of high-resolution algorithm (kernel) for reconstruction.

Which of the following statements most accurately describes the relationship between slice sensitivity profile (SSP) and dose profile?

A. The SSP is alway wider than the dose profile

B. The SSP is equal in width to the dose profile

C. The dose profile is always wider than the SSP

D. The SSP has no effect on the dose profile.

Answer: C. 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.

Which of the following numbers: 6, 3, 7, or 2 does not branch off from the aortic arch?

[image]

Answer: A. 6

The subclavian (3), brachiocephalic (7), and common carotid (2) arteries all branch off the superior portion of the aortic arch. The left (1) and right (6) brachiocephalic veins originate from the superior vena cava.

Number 1 corresponds to which of the following?

A. Iliacus muscle

B. gluteus minimus muscle

C. superior glueteal artery

D. psoas major muscle

[image]

Which of the following window level and width settings were used to display this image?

A. Level=-700, Width=2000

B. Level=+50, Width=400

C. Level=+150, Width=1000

D. Level=+250, Width=4000

[image]

Answer: D. Level=+250, Width=4000

An extremely wide window should be used to display images containing tissues with varying density ranges. A width such as 4000 is sufficient to display the dense bone of the mastoid tip and internal auditory canals. The level is set at the approximate average value of the tissues displayed. A level of +250 is the approximate average of all tissues within this anatomic region.

The average range for normal adult BUN levels is approximately:

A. 1-4 mg/dL

B.5-20 mg/dL

C. 23-30 mg/dL

D. 45-60 mg/dL

Answer: B. 5-20 mg/dL

The average range for normal adult blood urea nitrogen (BUN) levels is approximately 5-20 mg/dL.

A Voxel may be defined as which of the following?

A. The portion of the CRT displaying the image

B. A miniature image

C. A volume element

D. An arrangement of pixels

Answer: C. A volume element

A Voxel may be defined as a volume element. It is represented within a matrix by a pixel.

Which number corresponds with the left lobe of the liver?

[image]

Answer: Number 1

The technique that allows the user to select the range of pixel values used in a 3D CT reformation is termed:

A. Thresholding

B. Windowing

C. Retrospective reconstruction

D. Targeting

Answer: A. Thresholding

The selected threshold allows the user to select the range of pixel values rendered in the 3D model. For example, a higher, bone threshold (>300 HU) can be chosen to build a skeletal model of the patient's skull. Decreasing the threshold to include voxels with lower attenuation values results ina 3D model with the patients soft tissues included.

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 disc herniation?

A. 5mm x 5mm

B. 1.25mm x 1.25mm

C. 5mm x 7mm

D. 10mm x 10mm

Answer: B. 1.25mm x 1.25mm

Contiguous acquisition with narrow slice thickness is preferred during CT examination of the cervical spine. Section widths of 1.25mm or less should be used with no gap or even an overlap, thus ensuring thorough evaluation of the relatively small intervertebral disc spaces.

The oral administration of barium and iodinated contrast media prior to CT colonography serves the primary purpose of:

A. lesion enhancement

B. Insufflation

C. Catharsis

D. polyp tagging

Answer. D 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 differentation of polyp from fecal matter and improves the visualization of polyps that may be surrounding by residual fluid.

Which of the following corresponds to the period of the cardiac cycle known as atrial systole?

A. Relaxation of the left and right atrial

B. Contraction of the left and right atria

C. Relaxation of the left and right ventricles

D. Contraction of the left and right venticles

Answer: B. Contraction of the left and right atria

Atrial systole describes the period of the cardiac cycle when the left and the right atria are contracting.

The multiple-scan average dose (MSAD) is used to describe the:

A. Dose recieved in a single CT section

B. Amount of radiation absorbed in a quantity of air

C. Average dose to a single section within a scan of multiple sections

D. Cumulative dose for an entire helical scan

Answer: C. 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.

Which Number corresponds to the common carotid artery?

[image]

Which of the following is a malignant tumor of the skeletal system?

A. Chondroblastoma

B. Osteochondroma

C. Enchondroma

D. Osteosarcoma

Answer: D. Osteosarcoma

Malignant tumors of the skeletal system include osteosarcoma, chondrosarcoma, and multiple myeloma.

Which of the following is not a typical matrix size used with a modern CT scanner?

A. 80 x 80

B. 320 x 320

C. 512 x 512

D. 1024 x 1024

Answer: A. 80 x 80

Modern CT scanners are large matrices for image reconstruction and display. Typical sizes include 320 x 320, 512 x 512, and 1024 x 1024

The type of compensating filter used at the x-ray tube of a CT scanner is called a:

A. Kernel

B. Water Bath

C. Bow-tie filter

D. Wedge filter

Answer: C. Bow-tie filter

The bow-tie filter used at the x-ray tube of a CT scanner absorbs a larger amount of radiation at the periphery of the patient, where the part thickness is reduced. The center of the patient is places at the center of the filter, where the largest amount of radiation is allowed to pass through. The use of this type of filter attempts to compensate for the differences in thickness of the often oval-shaped patient.

Which of the following formulas may be used to calculate the dimensions of a pixel?

A. Pixel size= matrix size/DFOV

B. Pixel size=DFOV x matrix size

C. Pixel size= slice thickness/matrix size

D. Pixel size= DFOV/matrix size

Answer: D. Pixel Size=DFOV/matrix size

The dimensions of a pixel may be calculated by dividing the DFOV by the matrix size. Keep in mind that the pixel is a square with four equal sides and the dimension of one side is usually given in millimeters (mm). The area of the pixel is calculated by squaring the dimension, and the units are then adjusted to square millimetes (mm2).

Number 1 corresponds with which atomic structure?

[image]

Multiplanar reformation (MPR) images along the long axis of the optic nerve would be best describes by which of the following planes?

A. Sagittal

B. Coronal

C. Oblique Sagittal

D. Oblique Coronal

Answer: C. 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.

The primary indication for a non-contrast cardiac MDCT examinatuib is:

A. coronary artery stenosis

B. Aortic aneurysm

C. Coronary artery calcium quantification

D. Pulmonary embolism

Answer: C. Coronary Artery calcium quantification

The primary indication for non-contrast cardiac MDCT is coronary artery calcium (CAC) quantification for the assessment of atherosclerotic disease.

Following the intravenous administration of iodinated contrast media, a hepatic hemangioma may become _________ and may no longer appear on the CT image.

A. Hypodense

B. Radiolucent

C. Isodense

D. Hyperdense

Answer: C. 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.

After initiation of rapid bolus administratin of an iodinated contrast agent, the corticomedullary phase of renal contrast enhancement occurs at approximately:

A. 20-25 seconds

B. 30-40 seconds

C. 70-90 seconds

D. 3 to 5 minutes

Answer: B. 30-40 seconds

The corticomedullary phase is a late arterial phase beginning 30-40 seconds after the initiation of contrast agent administration. Optimal enhancement of the renal cortex and renal veins occurs during this period.

Number 4 corresponds with which atomic structure?

[image]

Which of the following aquistions may be characterized as noncontiguous?

A. 2.5 mm sections reconstructed every 1.25 mm

B. 5.0 mm sections reconstructed every 7.5 mm

C. 3.75 mm sections reconstructed every 3.75 mm

D. 20-second cine acquisition with 1.25 mm sections

Answer: B. 5.0 mm sectinos recontructed every 7.75

Noncontiguous images are images aquired with an interval greater than the section width. For example, 5.0 mm secions reconstructed every 7.5 mm fail to evaluate the intermittent 2.5 mm of tissue.

Number 1 corresponds to which of the following?

[image]

Answer: B. Fovea Capitis

In effort to reduce radiation exposure to the orbits during a CT examination of the brain, the gantry may be angled:

A. perpendicular to the hard palate

B. Parallel to the hard palate

C. 15 degrees superior to the infraorbital meatal line (IOML)

D. 15 degrees inferior to the infraorbital meatal line (IOML)

Answer: C. 15 degrees superior to the infraorbital meatal line (IOML)

Aquisition for a brain CT may be preformed at an angle 15 degrees above the IOML, parallel to the skull base, to reduce orbital radiation dose and minimize beam hardening artifact.

The IV administration of iodinated contrast media requires strict adherence to:

A. Contact isolation and sterile technique

B. Enteric precautions and aseptic technique

C. Contact isolation and aseptic technique

D. Standard precautions and aseptic technique

Answer: D. standard precautions and aseptic technique

Standard precautions refers to the principle that all blood, body fluids, and secretions may contain transmissible infectious disease. The practice of standard precautions applies to all patients recieving patient care, regardless of medical history. The technique and procedures constituting standard precautions are hand washing and the wearing of gloves, masks, goggles, gowns, etc. Similar in purpose aseptic technique refers to the specific procedures that a practioner employs to reduce the risk of infection during IV administraion of contrast agent. Examples are through hand washing between patients, wearing gloves, and cleansing the IV site with alcohol.

Which of the following areas of the head commonly become calcified?

(1) Thalamus

(2) Pineal Gland

(3) Choroid plexus

A. 2 only

B. 1 and 3 only

C. 2 and 3 only

D. 1, 2, and 3

Answer: C. 2 and 3 only

The choroid plexus and pineal gland are common areas of calcification in the brain. These areas of increased attenuation and density are easily identified on the CT image.

Which of the following is the correct order for the stages of infection?

A. Incubation, prodromal, active, convalescence

B. Convalescence, active, prodromal, incubation

C. Prodromal, incubation, convalesence, active

D. Incubation, convalescense, prodromal, active

Answer: A. incubation, prodromal, active, convalescence

The course of an infection can be divided into 4 stages. The incubation stage begins when a pathogenic organism enters the host. The prodromal stage is characterized by the appearance of early signs and symptoms fo the disease process. The active or full stage consists of the maximum appearance of the signs and symptoms of the disease. During the last stage, convalescence, the symptoms begin to diminish and may eventually completely subside.

A CT scanner with a limiting resolution of 15 lp/cm can resolve an object as small as:

A. 0.1 mm

B. 0.3 mm

C. 0.6 mm

D. 1.0 mm

Answer: 0.3 mm

The minimum object size that a CT scanner can resolve may be calculated by taking the reciprocal value of the scanner's limiting resolution. The reciprocal of 15 lp/cm is 1/15 lp/cm. This is equivalent to 10/15 lp/cm, which equals 0.6 mm/lp. Because a line pair (lp) is equivalent to a line and space adjacent to it, this value may be divided in half to provide the minimum object that this scanner can resolve: 0.3

By CT criteria, a solitary pulmonary nodule may be defined as a focal area of increased density in the lung that is smaller than:

A. 1 cm

B. 3 cm

C. 5 cm

D. 10 cm

Answer: B. 3 CM

Solitary pulmonary nodules are typically ovid focal areas of increased density that are less than 3 cm in diameter. Any lesion larger than 3 cm is reffered to as a focal mass, with an increase propensity for malignancy.

Number 3 corresponds to which atomic structure?

[image]

When one is choosing a window to display a CT image, the width defines the:

A. midpoint of the range of pixels displayed

B. range of CT numbers (pixels) to be displayed

C. Range of pixel values included in an ROI

D. Average CT number of the tissue of interest

Answer: B. Range of CT numbers (Pixels) to be displayed

The width of a CT window controls the range of pixel values that are assigned to a shade of gray. The width is centered to a level that is equal to the value of the tissue of interest.

The ability of a CT scanner to image a small high-density object is controlled by the ____________ of the scanner.

A. Contrast Resolution

B. Spatial Resolution

C. Sensitivity

D. Both A and C

Answer: B. Spatial resolution

The spatial resolution of a CT scanner controls its ability to image small structures

Which of the following is/are included in the signs and symptoms of hypovolemic shock?

(1) hypertension

(2) oliguria

(3) pallor

A. 1 only

B. 1 and 3 only

C. 2 and 3 only

D. 1, 2, and 3

Answer: C. 2 and 3 only

Hypovolemic shock is caused by an insufficient volume of circulating blood. The common signs and symptoms of hypocolemic shock are pallor (absence of color in the skin), hypotension, tachycardia, and oliguria (decrease urine output)

In 1917, Austrian mathematician _______ proved that it was possible to recontruct a three-dimensional object from the infinate set of all of its projections.

A. Radon

B. Tsien

C. Bracewell

D. Cormack

Answer: A. Radon

J. Radon, an Austrian mathematician was responsible for some of the earliest scientific research for the reconstruction principles used in computed tomography. In 1917 he proved that it was possible to build an image of an object through the use of an extremely large set of his projections.

Which of the following may be used for the archival storage of CT images?

(1) CD-ROM

(2) VHS tape

(3) Magnetic optical disc

A. 1 only

B. 1 and 3 only

C. 2 and 3 only

D. 1, 2, and 3

Answer: B. 1 and 3 only

CD-ROM and magnetic optical disc (MOD) are two media commonly employed for CT image archival.

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) measurement of the patient's pulse rate

(2) performing a bolus-timing sequence

(3) utilizing bolus-tracking software

A. 1 only

B. 1 and 3 only

C. 2 and 3 only

D. 1, 2, and 3

Answer: C. 2 and 3 only

Although pulse rate may provide an indication of the patients overall cardiac function, it is not utilized to determine injection delays for angiographic procedures. Emperic delays, bolus timing squences, and bolus tracking software may all be used to accurately acquire CTA studies during peak vascularture enhancement.

Which of the following corresponds to the longitudinal dimenion of the CT image voxel?

A. x-axis

B. Y-axis

C. z-axis

D. orthogonal axis

Answer: C. z-axis

The longitudinal dimension of the voxel corresponds to the z-axis of scanning, with a voxel depth equal to the reconstructed section width.

________ is a term that refers to an excessive amount of nitrogenous materials in the blood and is a symptom of renal failure.

A. Hydronephrosis

B. Azotemia

C. Oliguria

D. Diuresis

Answer: B. Azotemia

Azotemia describes the condition 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.

Evaluation of the venous vascular structures of the brain is known as:

A. CT angiography

B. CT perfusion

C. CT Runoff

D. CT venography

Answer: D. CT Venography

CT Venography (CTV) of the brain is a cariation of the CTA technique whereby the timing of data acquisition is optimized for the period of peak venous opacification.

Which of the following adjustments in technical factors will result in increase in spatial resolution?

A. increase in tube filament

B. increase in sampling frequency

C. Increase in section width

D. Increase in display field of view (DFOV)

Answer: B. increase in sampling frequency

The sampling frequency, or views per rotaion (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.

After initiation of rapid bolus administration of an iodinated contrast agent, the excretory phase of renal contrast enhancement occurs at approximately:

A. 20-25 seconds

B. 30-40 seconds

C. 70-90 seconds

D. 3-5 minutes

Answer: D. 3-5 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 real 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).

Which number corresponds to the left brachiocephalic vein?

[image]

The Propensity of a contrast agent to cause fluid to move from the extravascular space to the intravascular space is called:

A. Toxicity

B. Solubility

C. Concentration

D. Osmolality

Answer: D. Osmolality

An important characteristic of iodinated radiopaque contrast media, osmolality describes the propensity of the agent to cause fluid from outside the blood vessel (extravascular space) to move into the bloodstream (intravascular space).

In multislice CT (MSCT), the beam pitch is equal to the table feed per rotation divided by the:

A. Number of detectors

B. Pre-patient collimation

C. Total collimation

D. Number of channels

Answer: C. 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.

The full width at half maximum (FWHM) of a slice sensitivity profile diagram indicates the:

A. Limiting resolution

B. Signal-to-noise ratio (SNR)

C. Dose profile

D. Effective section width

Answer: D. 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.

The detectors of a PET system absorb and measure what type of radiation?

A. Xray photons

B. Annihilation photons

C. Light photons

D. Ultraviolet photons

Answer: B. 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.

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:

A. 5-10 sec

B. 20-25 sec

C. 50-60 sec

D. 80-90 sec

Answer: B. 20-25 sec

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 valuble methods of ensuring that acuisition occurs during the period of maximum vessel opacification.

For a given CT acquisition, the calculated mAs applied to each reconstructed slice may be referred to as the:

A. effective mAs

B. peak mAs

C. absorbed mAs

D. constant mAs

Answer: A. effective mAs

Effective mAs describes the calculated mAs per acquired slice. The primary influencing factor for effective mAs is table speed, which is an important component controlled by the selected detector pitch. The detector pitch chosen by the CT operator directly affects the speed at which the patient travels through the gantry. The mAs divided by the pitch yields the effective mAs for each slice in a given CT acquisition.

Number 2 corresponds to which anatomic structure?

[image]

Number two corresponds to which anatomical structure?

[image]

Which of the following technical factor(s) play(s) a role in the production of an isotropic dataset?

(1) section width

(2) scan field of view (SFOV)

(3) display field of view (DFOV)

Answer: 1 and 3 only

Isotropic resolution is approached by choosing the thinnest detector collimation availible to to produce the thinnest slices availible and by reconstructing the acquired data with the smallest DFOV allowed according to the part of interest. Minimizing these two factors results in voxels approaching equal lengths in all directions.

This Image of the Abdomen was most likely acquired in which phase of renal enhancement?[image]

Answer: Nephrographic Phase

The Neprographic phase occurs between 70-90 seconds after the start of the injection. Enhancement between renal cortex and medulla reaches equilibrium, providing optimal sensitivity for parenchymal lesions.

The articulation between the dista tibia and fibula is called the:

A. Synarthrosis

B. Amphiarthrosis

C. Synostoses

D. Syndemosis

This type of image is referred to as a(n):

[image]

Answer: 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, sagitaal, or any other two dimensional plane. MPR images are typically formed from a vertical stack of contiguous, helically acquired axial CT images.

This image of the abdomen was most likely acquired in which renal enhancement phase?

[image]

Answer: B. Corticomedullary phase

Beginning 30-40 seconds after initiation of contrast agent administration, the corticomedullary phase demonstrates optimal enhancement of the renal cortex with maximum differentiation from the renal medulla.

Automatic tube current modulation (ATCM) software is utilized by the CT system in an effort to:

A. improve temporal resolution

B. decrease patient dose

C. save on energy costs

D. improve spatial resolution

Answer: B. decrease patient dose

Automatic tube current modulation (ATCM) is a form of automatic exposure control (AEC) for CT systems. This type of software automatically decreases applied dose on the basis of the size, density, and overall attenuation of the part being examined.

After initiation of rapid bolus administration of an iodinated contrast agent, the hepatic venous phase of contrast enhancement occurs at approximately:

A. 15-20 seconds

B. 25-25 seconds

C. 60-70 seconds

D. 120-180 seconds

Answer: C. 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 60-70 seconds after the initiation of rapid bolus administration of a contrast agent.

The ability of an object to attenuate the x-ray beam is assigned a value known as the:

A. Linear attenuation coefficient

B. Hounsfield value

C. CT number

D. ray sum

Answer: A. Linear attenuation coefficient

Number 7 corresponds to which anatomic structure?

[image]

The computer technique used to reduce size and storage requirements of digital CT image data is called:

A. Archival

B. Compression

C. Encryption

D. Rendering

Answer: B. Compression

Image compression is a complex computer technique that reduces the size of digital CT image data. Compression of CT images reduces the storage requirements and increases the speed at which the CT images may be transmitted across computer systems.

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?

A. 10 mm

B. 20 mm

C. 32 mm

D. 64 mm

Answer: B. 20 mm

The selected detector configuration for a given acquisition determines the necessary beam collimation. 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 x 0.625= 20 mm).

Which of the following is a correct difference between ionic and nonionic iodinated contrast media?

A. nonionic media have a higher osmolality than ionic media

B. ionic contrast media contain iodine, whereas nonionic media do not

C. nonionic contrast media have lower osmolality than ionic media

D. ionic contrast media are associated with a lower incidence of adverse reactions than nonionic media

Answer: C. nonionic contrast media have lower osmolality than ionic media

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.

Number 3 corresponds to which muscle?

[image]

Number 4 corresponds to which structure?

[image]

Number 4 corresponds to which anatomic structure?

[image]

Number 5 corresponds to which muscle?

[image]

Which of the following technical facotors exhibits an effect upon longitudinal spatial resolution?

(1) detector pitch

(2) interpolation algorithm

(3) display field of view (DFOV)

A. 1 only

B. 3 only

C. 1 and 2 only

D. 1 and 3 only

Answer: C. 1 and 2 only

The factors that affect longitudinal spatial resolution and the SSP include the type of spiral interpolation algorithm inherent to the system and the selected detector pitch.

Increasing the detector pitch during a spiral CT exam adversely affects the spatial resolution along which of the following?

A. axial plane

B. x-axis

C. y-axis

D. z-axis

Answer: D. Z-axis

The spatial resolution alond the z-axis is decreased when the detector pitch is increased. An increase in detector pitch causes less information to be acuired for each section reconstructed. The section sensitivity profile (SSP) is broadened, and the spatial resolution is reduces.

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:

A. homogeneous radiation

B. unattenuated radiation

C. monochromatic radiation

D. remnant radiation

Answer: B. unattenuated radiation

Reference detectors are used to measure incident radiation intensity. This information is used by the computer during the calculation of the linear attenuation coefficient. If the patient is places incorrectly within the gantry, the reference detectors may be partially blocked causing an out-of-field artifact.

The quantity of blood pumped out of the ventricle every heartbeat is termed the:

A. end-diastolic volume

B. ejection fraction

C. end-systolic volume

D. injection fraction

Answer: B. Ejection fraction

Ejection fraction describes the percentage of blood pumped out of a cardiac ventricle during each contraction. It is a measure of cardiac function and can be accurately determined during a cardiac CT examination. With system software, the ejection fraction can be calculated from a comparison between colume of blood within a ventricle at the end of filling (end-diastolic volume) and the volume at the end of contraction (end-systolic volume)

The liver has dual blood supply and recieves 25% of its blood from the:

A. Hepatic artery

B. Superior mesenteric artery (SMA)

C. Portal vein

D. Superiod mesenteric vein (SMV)

Answer: A. Hepatic Artery

The liver has a dual blood supply, receiving 75% of its supply from the portal vein, and the remaining 25% from the hepatic artery.

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:

A. CT enteroclysis

B. CT colonography

C. CT enterography

D. CT colonoscopy

Answer: C. CT enterography

CT enterography does not involve contrast agent administration through a nasogastric tube and is therefore less invasive than CT enteroclysis.

The computerized communication system used by a PACS to transmit data is referred to as a:

A. Convolution

B. Hierarchy

C. Network

D. Matrix

Answer: C. Network

A PACS communicates with the CT system(s) and other modalities and peripherals via a computerized communication system, or network.

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:

A.5-8 seconds

B. 20-30 seconds

C. 45-60 seconds

D. 70-90 seconds

Answer: B. 20-30 seconds.

Dual-phase imaging including the arterial phase (20-30 seconds) and portal venous phase (60-70 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.

Number 1 corresponds to which anatomic structure?

[image]

The streaking artifact in the image is most likely due to:

[image]

Answer: Beam hardening

Streaking artifacts such as the one in the figure commonly occur during CT scanning of thick body parts like the shoulder. The x-ray beam changes in quality as it passes through different densities. These beam energy changes sometimes manifest as streak artifacts.

Patients whose posterior descending artery branches from the right coronary atery, and whose left posterior ventricular branches arise from the left circumflex artery, are said to be:

A. Right dominant

B. Left dominant

C. Codominant

D. Posteriorly dominant

Answer: C. Codominant

7% of the population is said to be codominant, meanind the posterior descending artery (PDA) is supplied by the right coronary artey (RCA), and the left posterior ventricular branches arise from the Left circumflex artery (LCX)

During post-contrast CT imahing of the abdomen, the degree of hepatic parenchymal enhancement depends on:

(1) the iodine concentration of the contrast agent

(2) the rate of contrast injected

(3) the osmolality of the contrast media

A. 1 only

B. 1 and 2 only

C. 2 and 3 only

D. 1,2, and 3

Answer: B. 1 and 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.

Which of the following is NOT a component of the blood supply to the brain commonly referred to as the circle of willis (COW)?

A. Right middle cerebral artery

B. Left posterior communicating artery

C. Anterior communicating artery

D. Left posterior cerebral artery

Answer: A. 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 and middle cerebral arteries are important vessels supplyaing blood to the brain, but they do not form a part of the circle of willis.

Number 1 corresponds to which anatomic structure?

[image]

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):

A. Subdural hematoma

B. Epidural Hematoma

C. Subarachnoid Hematoma

D. Subcutaneous Hematoma

Answer: B. Epidural Hematoma

An epidural hematoma occurs between the skull and the outtermost 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.

Which of the following technical adjusments would decrease the quantum noise of a CT image?

(1) Increase mAs

(2) decrease section width

(3) Increase sectin width

A. 1 only

B. 1 and 2 only

C. 1 and 3 only

D. 1, 2, and 3

Answer: C. 1 and 3 only

The quantum noise of a CT image can be reduced by an increase in the number of x-ray photons reaching the detectore. This reduction may be accomplished by increasing mAs or section width (decreased collimation).

Cerebrospinal fluid (CSF) is produces in the:

A. tentorium cerebelli

B. pineal gland

C. corpus callosum

D. choroid plexuses

Answer: D. Choroid plexuses

The cerebrospinal fluid is secreted by the choroid plexuses that are located in each of the four ventricles of the brain.

Number 1 corresponds with which muscle?

[image]

After initiation of rapid bolus administratino of an iodinated contrast agent, the early arterial phase of hepatic contrast enhancement occurs at approximately:

A. 15-20 seconds

B. 25-35 seconds

C. 60-70 seconds

D. 120-180 seconds

Answer: A. 15-20 seconds

Occuring at 15-20 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 the phase, the hepatic arterial supply is well opacified with little or no parenchymal enhancement.

Which of the following manipulations involes the use of image data?

A. adjusting the width and level of a window

B. decreasing the DFOV

C. changing the algorithm selection

D. increasing the matrix size

Answer: A. adjusting the width and level of a window

The adjustment of the window width or level is a computer manipulation of the image data. The image has already been reconstructed from scan or "raw" data. The window changes only the range of pixel values that will be assigned a shad of gray. Adjustments in the algorithm, DFOV, or matrix require the raw data so that the image may be retrospectively reconstructed.

Number 3 correspond with which anatomic structure?

[image]

Which of the following components of CT image quality may be controlled by the technologist?

(1) Spatial resolution

(2) contrast resolution

(3) noise

A. 2 only

B. 3 only

C. 1 and 3 only

D. 1, 2, and 3

Answer: D. 1, 2, and 3

Each component of CT image quality may be affected-either positively or negatively-by the CT technologist. Spatial resolution is affected by geometric factors such as focal spot size and slice thickness. Contrast resolution may be altered by slice thickness, algorithm selection, and noise. The noise level on an image is dependent upon several facots, including patient dose and pixel dimension. Each of these factors must be considered by the CT technologist in an effort to provide high quality CT studies.

Number 4 corresponds with which anatomic structure?

[image]

CT images of the abdomen should be acquired with the patient:

A. at full inspiration

B. breathing quietly

C. at full expiration

D. breathing normally

Answer: C. at full expiration

Suspended respiration at the end of full expiration is the most reproductable point in the respiratory cycle. It results in a less misregistration artifact during CT examinations of the abdomen.

What is the display field-of-view used for a 3202matrix image with a pixel dimension of 0.75 mm x 0.75 mm?

A. 12 cm

B. 24 cm

C. 36 cm

D. 48 cm

Answer: B. 24 cm

The display field of view may be calculated by multiplying the pixel dimension by the matrix size. In this example, one side of the pixel measures 0.75 and the matrix used is 3202. The DFOV is 240mm or 24 cm.

Coronal imaging through the paranasal sinuses is typically performed with the plane of imaging:

A. parallel to the infraorbital-meatal line

B. perpendicular to the gabellomeatal line

C. parallel to Reid's baseline

D. perpendicular to the hard palate

Answer: D. perpendicular to the hard palate

The imaging plane should be positioned perpendicular to the hard palate for coronal evaluation of the paranasal sinuses. This may be achieved by positioning the patient supine, head extended-back position, or with the patient in the prone position. In either case, appropriate angulation of the gantry can help achieve an aquisition angle that is perpendicular to the hard palate. Alternatively, multiplanar reformation (MPR) images may be produced at an angle perpendicular to the axial acquisition, also resulting in coronal images through the paranasal sinuses.

Number 2 corresponds with which anatomic structure?

[image]

The dimensions of a voxel may be calculated as the product of which of the following?

A. matrix size and pixel size

B. pixel size and section width

C. DFOV and matrix size

D. DFOV and pixel size

Answer: B. pixel size and section width

The pixel is a two-dimensional representation of a voxel. The section width is equal to the length of the voxel. To calculate the dimensions of a voxel, the pixel dimension must be multiplied by the section width.

Which of the following would increase the noise apparent on a CT image?

A. increase in mAs

B. decrease in aperature size

C. increase in filtration

D. decrease in matrix size

Answer: B. decrease in aperature size

A decrease in aperature size reduces the amount of x-ray photons exposing the tissue. This will cause a decrease in the signal-to-noise ratio. Keep in mind that the collimators used to adjust the size of the aperature absorb radiation as they restrict the beam.

Number 5 corresponds to which anatomical sturcture?

[image]

Answer: Petrous bone

Which of the following units is used to quantify absorbed dose?

A. roentgens

B. grays (Gy)

C. sieverts (Sv)

D. curies (Ci)

Answer: B. grays (Gy)

Absorbed dose describes the amount of x-ray energy absorbed in a unit of mass. It is measured in grays (Gy).

Number 2 correspons with which anatomical strucure?

[image]

What scan field of view (SFOV) value was most likely used for the aquisition of this CT image?

[image]

A. 9.6 cm

B. 15.0 cm

C. 25.0 cm

D. 50.0 cm

Answer: D. 50.0 cm

The acquisition was most likely made with use of a large scan field of view (SFOV), 48-50 cm. Any smaller SFOV would result in out-of-field artifact, because portions of the upper shoulder area would lie beyond the range or the detector array. A smaller display field-of-view (DFOV) value was used for image reconstruction, targeting the side of interest.

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?

A. 0.033 mm

B. 0.3 mm

C. 3.01 mm

D. 30.1 mm

Answer: B. 0.3 mm

The dimension of a pixel may be calculated by dividing the field of view by the matrix size. The DFOV of 17 cm must first be converted into 170 mm. This is then divided by 512 mm, for a pixel dimension of 0.33 mm. Keep in mind that the pixel is a two-dimensional item, square in shape, and the measurement of 0.33 mm corresponds to only one side.

The portion of the nephron responsible for filtration of unwanted materials from the blood plasma is called the:

A. afferent arteriole

B. Proximal tubule

C. efferent arteriole

D. glomerulus

Answer: D. glomerulus

The glomerulus is the portion of the nephron responsible for filtering unwanted substances from blood plasma. The blood enters into the glomerulus through the afferent arteriole and exits through the efferent arteriole. The waste fluid leaves the glomerulus through the proximal tubule.

The ability of an MDCT system to freeze heart motion during a cardiac CT is described by its:

A. detector resolution

B. spatial resolution

C. temporal resolution

D. contrast resolution

Answer: C. temporal resolution

The temporal resolution of an MDCT system describes its ability to freeze the motion of the heart as well as the arterial motion velocity within the coronary vasculature.

Number 2 corresponds with which anatomical structure?

[image]

Which of the following types of image noise can be most easily reduced by the CT technologist?

A. electronic noise

B. artifactual noise

C. quantum noise

D. detector noise

Answer: C. quantum noise

The quantum or statistical noise of a CT image can be reduced by increasing the number of x-ray photons absorbed by the detectors for each voxel of tissue. This can be accomplished with increased in technique (mAs) and with increases in the pixel and voxel and dimensions.

In multislice CT (MSCT), the beam pitch is equal to the table feed per rotation divided by the:

A. number of detectors

B. pre-patient collimators

C. total collimation

D. number of channels

Answer: C. 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.

The term beam hardening is used to describe which of the following physical phenomena?

A. the decrease in average photon energy of a heterogenous x-ray beam

B. the increase in average photon energy of a homogenous x-ray beam

C. the increase in average photon energy of a heterogenous x-ray beam

D. the decrease in average photon energy of a homogenous x-ray beam

Answer: C. the increase in average photon energy of a heterogenous 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 heterogenous beam undergoes an increase in average photon energy as it passes through the patient and the lower-energy photons are absorbed.

During IV contrast agent administration for peripheral CTA examinations, the bolus duration should be equal to the scan time minus:

A. 0 seconds

B. 5 seconds

C. 15 seconds

D. 30 seconds

Answer: B. 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 sec) to the end of data acquisition.

Two adjacent pixels are measured to have a difference of 1 HU. This amounts to a tissue density difference of approximately:

A. 0.1%

B. 1.0%

C. 10%

D. 25%

Answer: A. 0.1%

Pixels that differ by only 1 Hounsfield unit represent tissue whose attenuation coefficient differ by only 0.1%

Which of the following types of algorithms would be best suited to demonstrate the bony details of the shoulder joint in the figure?

A. high spatial frequency

B. soft tissue

C. standard

D. low spatial frequency

Answer: A. high spatial frequency

Hugh spatial frequency algorithms demonstrate the greatest spatial resolution and are best suited for imaging sharp density changes, such as those occuring with bone tissue. Bone, edge, and detail are names commonly given to high spatial frequency algorithms.

Which of the following technical adjustments may be emplayed to improve the temporal resolution of an MDCT system?

(1) decreased scan time

(2) decrease section width

(3) decreased DFOV

A. 1 only

B. 1 and 2 only

C. 2 and 3 only

D. 1, 2, and 3

Answer: A. 1 only

Temporal resolution quantifies the CT system's ability to freeze motion and to provide an image free of blurring. The controlling factors of the temporal resolution of a CT system are the gantry rotation speed and reconstruction method.

Which of the following technical characteristics of a CT system does NOT directly affect patient dose?

A. source-to-detector distance

B. filtration

C. detector efficiency

D. filament size

Answer: D. 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.

Number 6 corresponds to which anatomical structure?

[image]

Severe reactions to intravenous iodinated contrast material occur in approximately ________ of all patients.

A. less than 1%

B. 3%

C. 5%

D. 10%

Answer: A. less than 1%

Severe reactions to intravenous iodinated contrast media occur in less than 1% of all patients. Examples of severe reactions are shock, myocardial infarction, and death.

In which of the following cranial nerves would an acoustic neuroma be found?

A. third

B. eighth

C. tenth

D. twelfth

Answer: B. Eighth

An acoustic neuroma (Schwannoma) arises from the 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.

Because of its excessive density, barium sulfate may be used in CT only in suspensions with concentrations of:

A. 1-3% barium sulfate

B. 5-7% barium sulfate

C. 10-13% barium sulfate

D. 25-30% barium sulfate

Answer: A. 1-3% barium sulfate

Barium sulfate is normally too dense to be useful in CT imaging. Even when diluted with water, barium's high attenuation characteristics can cause streaking artifacts on the CT image. Some commercially availible CT oral contrast media preperations do contain barium sulfate in 1-3% suspensions. The suspension contains additives that are designed to prevent settling of barium sulfate, which could cause inhomogenous opacification of the gastrointestinal system.

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 attenuation values for normal gray metter.

(2) The contrast agent improves the differentiation of subtle hemorrhage

(3) The contrast agent enhances neoplasms that have disrupted the blood-brain barrier.

Answer: 1 and 3 only

During CT imaging for suspected intracranial bleeding, contrast administration is initially contraindicated because the associated enhancement may mask subtle signs of hemorrhage.

Phantom measurement of the uniformity of a CT system is performed primarily to assess the negative effects of:

A. partial volume averaging

B. noise

C. detector drift

D. beam hardening

Answer: D. beam hardening

The uniformity of a CT system describes its ability to maintain relatively consistent CT values acress the entire image of an object of equal density, such as a water-filled phantom. Beam hardening occurs as low-energy x-ray photons are absorbed when the beam passes through the patient. The average photon energy of the beam increases along the path and may result in a loss of system uniformity.

Which of the following correctly illustrates the central volume principle of cerebral perfusion?

A. CBF=CBV/MTT

B. CBF=CBV MTT

C. MTT=CBV CBF

D. CBF=MTT/CBV

Answer: A. 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 colume of blood within a given area of brain tissue and the time it takes for that blood to pass through the area. Reduces CBF may indicate ischemia due to stroke or other brain abnormalities.

Number 1 corresponds with which anatomic structure?

[image]

In this image at the level of the L4-L5 disc space, number 6 corresponds to which anatomical strucure?

[image]

Answer: Cauda Equina

The spinal cord extends inferiorly from the brain's medulla and terminates at approximately the level of T12-L1. At its distal end, the spinal cord tapers into the conus medullaris. The cauda equina is the nerve bundle extending inferiorly from the spinal cord.

The image is displayed in which anatomic plane?

[image]

Answer: Axial

The axial plane divides the body into inferior and superior portions. The section bisects the foot perpendicular to its long axis and is said to be an axial image in referrence to the standard anatomic position.

Which of the following components of the CT system is the most common cause of ring artifacts on the reconstructed CT image?

A. x-ray tube

B. collimator

C. slip ring

D. detector

Answer: D. detector

Ring artifacts are typically cause by faulty detectors. An error in a detecor results in back-projection of an incorrect ring of density on the reconstructed CT image.

Which of the following correctly describes the position of the seminal vesicles in the male pelvis?

A. posterior to the bladder and anterior to the rectum

B. superior to the rectum and inferior to the bladder

C. anterior to the bladder and superior to the prostate

D. inferior to the bladder and posterior to the rectum

Answer: A. posterior to the bladder and anterior to the rectum

The seminal vesicles are located posterior to the bladder and anterior to the rectum on a cross section of the male pelvis.

Cardiac CT images are typically acquired during which phase of the heart's cycle?

A. systolic phase

B. equilibrium phase

C. diastolic phase

D. ejection phase

Answer: C diastolic phase

The heart optimally imaged with the least artifact from motion during its period of relaxation, otherwise known as the diastolic phase of the cardiac cycle.

Answer: Modulation transfer function

The modulation transfer function (MTF) is a mathmatical method of quantifying the spatial resolution of a CT scanner.

Each iliac artery bifurcates into the internal and external iliac arteries at about the level of:

A. L4

B. L5-S1

C. the pubic symphysis

D. the patella

Number 1 corresponds to which anatomic structure?

[image]

Which of the following technical considerations is necessary to differentiate hydronephrosis from parapelvic cysts on CT examination?

A. administration of an iodinated IV contrast

B. prone acquisition

C. administration of an oral contrast agent

D. Valsalva maneuver

Answer: A. administration of an iodinated IV contrast

Parapelvis 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.

Where should the tourniquet be positioned during preparation of a patient for intravenous contrast administration?

A. directly over the injection site

B. proximal to the injection site

C. distal to the injection site

D. below the injection site

Answer: B. proximal to the injection site

Prior to the intravenous injection of contrast media, a tourniquet is placed proximal to the injection site. The tourniquet helps distend the vein, making needle insertion easier.

During combined PET-CT imaging, abnormal physiologic uptake of radiopharmaceuticals can occur in patient muscle due to:

A. low blood glucose

B. pre-examination fasting

C. strenuous activity

D. high blood pressure

Answer: C. strenuous activity

Strenuous physical activity can cause abnormal physiological 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.

The volume of a voxel may be calculated by multiplying the pixel dimension (mm2) by the:

A. Display field of view (DFOV)

B. section width

C. pitch

D. scan field of view (SFOV)

Answer: B. Section width

As a geometric cuboid, the volume of a voxel may be calculated as the product of the pixel area dimension (mm2) and the section width (mm). The pixel dimension (d) must be first calculated by dividing the display field of view (DFOV) by the matrix size. The area of the pixel may then be found by squaring the value of d (mm). The unit of measurement for voxel of volume is mm3.

Which of the following is the primary interaction between x-ray photons and tissue during computed tomography?

A. bremsstrahlung

B. Characteristic

C. Compton effect

D. coherent scatter

Answer: C. Compton effect

Owing to the high-energy beam used in CT the compton effect is the predominant interaction between x-ray and matter. CT scanners use between 120 and 140 kVp, yielding x-ray energies with averages between 70 and 80 KeV.

Number 3 corresponds to which anatomic structure?

[image]

Which of the following technical adjustments would result in a decrease in patient dose?

(1) decrease mAs

(2) increase detector pitch

(3) decrease kVp

A. 2 only

B. 1 and 2 only

C. 1 and 3 only

D. 1, 2, and 3

Answer: D. 1, 2, and 3

The relationship between mAs and dose is directly proportional. Any reduction in mAs results in a reduction in dose when all other factors remain equal. Increasing detector pitch raises the rate at which the patient moves through the gantry during data acquisition; when all other factors remain constant, increases in detector pitch reduce patient dose. A decrease in kVp also results in lower patient dose primarily through the reduction in overall beam energy at lower tube potentials. This may seem counterintuitive to those who recall the use of high-kVp techniques in radiography as a means of lowering required mAs and the associated patient dose. When we reduce kVp to reduce patient dose in CT.

The normal pulse rate range in a child is:

A. 30-50 beats per minute

B. 60-100 beats per minute

C. 70-120 beats per minute

D. 110-150 beats per minute

Answer: C. 70-120 beats per minute

The normal range for pulse rate in a child is 70-120 beats per minute. This is slightly higher than the range of 60-100 beats per minute for an adult.

The normal range of respirations for an adult is:

A. 5-10 breaths per minute

B. 12-20 breaths per minute

C. 20-30 breaths per minute

D. 35-50 breaths per minute

The process of scanning a phantom device of known density to improve the accuracy of CT attenuation measurement may be referred to as:

A. Hounsfield correction

B. linearity

C. uniformity

D. calibration

Answer: D. calibration

During the process of calibration, CT acquisitions are made of a phantom of a known density (i.e. water) or an empty gantry field (air). The CT system makes corrections of the data acquired, ensuring that the calculations of linear attenuation and Hounsfield values during clinical procedures are accurate.

Number 4 corresponds to which anatomic structure?

[image]

The average range for normal prothombin (PT) time is approximately:

A. 3-5 seconds

B. 7-9 seconds

C. 12-15 seconds

D. 18-23 seconds

Answer: C. 12-15 seconds

Normal prothrombin (PT) times are lab-specific and range between approximately 11 and 15 seconds. This test is used to evaluate the coagulation ability of a patient scheduled to undergo an invasive CT procedure.

A high-osmolar contrast material has an average osmolality of:

A. 100-300 mOsm/kg water

B. 600-850 mOsm/kg water

C. 1000-2400 mOsm/kg water

D. 4000-7000 mOsm/kg water

Answer: C. 1000-2400 mOsm/kg water

The osmolality of a contrast material is a measure of the number of particles per kg of water. Osmolality is factor in determining the potential for adverse reactions to iodinated contrast material. Ionic contrast media, which dissolves into a large number of anions and cations in solution, have an average osmolality between 1000 and 2400 mOsm/kg.

The technique that provides the detail of the outer portions of the 3D model while maintaining the typical CT detail of the lungs inside is called:

A. Maximum intensity projection (MIP)

B. Surface rendering

C. Summed projection

D. Voxel gradient

Answer: B. surface rendering

Computer programs are capable of constructing 3D models of anatomy with several different types of rendering techniques. A surface-rendered 3D model provides excellent surface anatomy while maintaining the normal cross-sectional anatomy apperance of the volume inside the model.

Which of the following display fields-of-view (DFOV) should be chosen for a CT examination of the thoracic soine of a patient whose thorax measures 40 cm?

A. 15 cm

B. 25 cm

C. 32 cm

D. 42 cm

Answer: A. 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 magnigication of the CT image. Although in this patient measures 40 cm, the DFOV of 15 cm will be suffivient to target the spine and enlarge its image on the viewing monitor.

Number 1 corresponds with which anatomic structure?

[image]

The Hounsfield value of a pixel is directly related to which of the following?

A. Window width

B. Field of view size

C. μ of HO

D. Window Level

Answer: C. μ of HO

The value of a pixel in Hounsfield units is calculated through a comparison of the linear attenuation coefficient (μ) of a voxel of a tissue to that of water.

Which of the following is an advantage of nonionic contrast media of ionic media?

A. lower cost

B. decreased nephrotoxicity

C. decreased enhancement

D. reduced incidence of adverse reaction

Answer: D. reduced incidence of adverse reaction

Nonionic contrast material is associated with a lower incidence of adverse reactions than ionic media. Nonionic media are also higher is cost but unfortunately offer no reduction in renal toxicity.

Which of the following CT image archival media is capable of storing the greatest amount of information?

A. magnetic tape

B. 5-inch floppy disk

C. 3-inch floppy disk

D. magnetic optical disk

Answer: D. magnetic optical disk

With storage capabilities of severeal gigabytes (GB) of digital information, the magnetic optical disk has the highest storage capacity of the acrhival media listed.

During CT perfusion studies, the quanity of blood (in mL) contained within 100g of brain tissue is termed the:

A. mean transit time (MTT)

B. cerebral blood flow (CBF)

C. cerebral blood volume (CBV)

D. percent-washout value (PWV)

Answer: C. cerebral blood volume (CBV)

Cerebral blood volume (CBV) describes the quantity of blood (in mL) contained within 100-g volume of brain tissue. Normal range is 4-5mL/100g.

The graph is used to evaluate which component of CT image quality?

[image]

Answer: Spatial resolution

The MTF of a CT system is an objective measurment of a system's in-plane spatial resolution. By evaluating an MTF curve of the particular image, the operator can assess the spatial resolution of a CT system and appraise changes in spatial resolution due to adjustments in technical factors.

Number 3 corresponds with whcih anatomic structure?

[image]

Number 4 corresponds to what anatomic structure?

[image]

Number 4 corresponds to which anatomic structure?

[image]

Number 1 corresponds to which anatomic stucture?

[image]

The approximate inherent filtration of the CT x-ray amounts to an aluminum equivalent of:

A. 1.2 mm

B. 3.0 mm

C. 5.8 mm

D. 10.0 mm

Answer: 3.0 mm

The tube housing, cooling oil, and so on, consitite the inherent filtration, which amounts to approximately 3.0 mm of aluminum equivalent filtration.

The branches of the left coronary artery include the:

(1) sinus node artery

(2) left anterior descending artery

(3) left circumflex artery

A. 2 only

B. 1 and 2 only

C. 2 and 3 only

D. 1, 2, and 3

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

A. 1 only

B. 1 and 3 only

C. 2 and 3 only

D. 3 only

Answer: B. 1 and 3 only

Iodinated intravenous contrast agents alter the CT image by increasing the density of enhanced structures. Organs, blood vessels, and so on, containing iodine attenuate a greater portion of the primary beam, thereby increasing their attenuation value. This permits greater differentiation of anatomic structures and pathologic processes. Any "enhanced" structure has an increased attenuation value (and subsequent image density) that its normal, unenhanced state.

Ischemic brain tissue identified as an infarct core when cerebral blood volume (CBV) falls below:

A. 2.5 mL/100g

B. 5.0 mL/100g

C. 10.0 mL/100g

D. 50.0mL/100g

Answer: A. 2.5 mL/100g

Brain parenchyma with a CBV less than 2.5 mL/100g is identified as the infarct core.

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:

A. -956 HU

B. -173 HU

C. +44 HU

D. +1044 HU

Answer: C. +44 HU

The CT number of a pixel may be calculated by subtracting the linear attenuation coefficient of water from the linear attenuation coefficent of the tissue within the voxel. This number is divided by the linear attenuation coefficient of water. The quotient is multiplied by a contrast factor of 1000 to yield the value of the pixel in Hounsfield units.

0.189-0.181=.008

.008/0.181=0,044

0.044x1000=44

The exaggeration of displayed calcification within the coronary arteries during a cardiac MDCT study is reffered to as:

A. aliasing

B. blooming

C. star artifact

D. penumbra

Answer: B. blooming

Blooming refers to the potential overestimation of vessel calcification due to 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 apperace of the artifact.

The typical dose of the radiopharmaceutical F-18-fluorodeoxyglucose (FDG) for combined PET-CT examination is within the range of:

A. 0.3 to 0.8 millicuries (mCi)

B. 1.5 to 3.0 mCi

C. 5.0 to 7.0 mCi

D. 10.0 to 15.0 mCi

Answer: D. 10.0 to 15.0 millicuries

Typical dose consistes of 10-15 millicuris (mCi) of FDG administered intravenously.

This image of the pelvis was most likely acquired in which phase of IV enhancement?

[image]

Answer: excretory phase

The well-opacified ureters indicate that the acquisition of this image occured during the excretory phase of IV contrast enhancement.

Which of the following may be used to reduce metal streak artifact on coronal plane CT images of the orbits?

(1) retrospective recontruction of targeted images with reduces 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

A. 1 only

B. 3 only

C. 2 and 3 only

D. 1, 2, and 3

Answer: C. 2 and 3 only

Volumetric MDCT axial acquisition through the orbit, sinuses, and so on, allows for high quality coroanl MPR imaged without metal streaking artifact. CT manufactuers 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.

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?

A. 1-3 mL

B. 5-9 mL

C. 12-14 mL

D. 18-22 mL

Answer: C. 12-14 mL

A common range of contrast agent volume for an intrathecal injectin during post-myelographic CT is 12-14 mL in an adult patient. The total volume should not exceed approximately 17 mL, so as to keep the iodine dose below 3 g.

Which of the following oral contrast agents offers the best visualization of the enhancing GI wall on post-IV contrast CT examination?

A. low-osmolar water-soluble iodinated contrast

B. high-osmolar water-soluble iodinated contrast

C. water
D. barium sulfate suspension

Answer: C. 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.

Number 2 corresponds to which anatomic structure?

[image]

The maximum dose of intravenous iodinated contrast for a child should not exceed:

A. 1 mg/kg body weight

B. 3 mg/kg body weight

C. 5 mg/kg body weight

D. 10 mg/kg body weight

Answer: B. 3 mg/kg body weight

The maximum dose of intravenous iodinated contrast agent should not exceed 3 mg per kg of body weight during pediatric CT examinations. Contrast loads in excess of this limit have been reported to cause acute osmolar poisoning in children.

The component of the DAS responsible for strengthening the signal emitted from the detector is termed the:

A. digital-to-analog converter (DAC)

B. preamplifier

C. high-resolution comb

D. bow-tie filter

Answer: B. preamplifier

The weak electronic signal emitted from the detectors in response to the measurement of transmitted radiation must be strengthened before it is utilized for image reconstruction. The preamplifier is the component of the data acquisition system (DAS) responsible for amplifying the detector signal.

Number 5 corresponds to which anatomic structure?

[image]

Which of the following matrices would provide the greatest spatial resolution?

A. 256x256

B. 320x320

C. 512x512

D.1024x1024

Answer: D. 1024x1024

A larger matrix size consists of an increased number of pixels. The computer is then able to assign less information into each pixel, allowing the image to display extremely small objects seperately from one another. This increases the spatial resolution of the CT scanner.

The human eye is capable of differentiating approximately _________ shades of gray.

A. 10-25

B. 60-80

C.100-120

D. 250-256

Answer: B. 60-80

The human eye is capable of differentiating only about 60-80 individual shades of gray. The 256 shades utilized in CT are therefore sufficient to represent the total range of pixel values possible in a 12-bit system.

Number 1 corresponds to which anatomic structure?

[image]

A dermoid tumor of the ovary may also be referred to as a :

A. leiomyoma

B. cystic teratoma

C. germ cell tumor

D. hemorrhagic cyst

Answer: B. 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.

After initiation of rapif bolus administration of an iodinated contrasr agent, the equilibrium phase of hepatic contrast enhancement occurs at approximately:

A. 15-20 seconds

B. 25-35 seconfs

C. 60-70 seconds

D. 120-180 seconds

Answer: D. 120-180 seconds

The equilibrium phase of hepatic contrast enhancement usually occurs 2-3 minutes after the initiation of contrast agent administration. During this phase, hepatic parenchymal enhancement dissipates and there is minimal difference in contrast enhancement beterrn the intravascular and extravascular spaces.

Which of the following technologic advances has led to the develpment of spiral/helical CT scanning?

(1) slip-ring technology

(2) electron beam technology

(3) high-efficiency x-ray tubes