Term
| 1. An average range for activated PTT is: a. 10-12 seconds b. 17-21 seconds c. 25-35 seconds d. 45-55 seconds |
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Definition
| c. 25-35 seconds The partial thromboplastin time (PTT) is a laboratory measure of blood coagulation. This value is used for screening of patients for invasive procedures. because of individual laboratory practices, the average range may fluctuate slightly. |
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Term
2. Which of the following is the correct angle of insertion for placing a butterfly needle into a vein for intravenous administration of a contrast agent?
a. 5 degrees
b. 15 degrees
c. 45 degrees
d. 60 degrees |
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Definition
b. 15 degrees
A butterfly needle should be inserted at an angle of 15 degrees for the intravenous administration of contrast material. It is also important that the vein be properly stabilized and that the needle be inserted gently with the bevel facing upward. |
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Term
3. A total volume of 125 mL of an iodinated contrast agent is administered intravenously via automatic injector in 50 seconds. The flow rate for this injection is:
a. 0.75 mL/sec
b. 1.25 mL/sec
c. 1.75 mL/sec
d. 2.5 mL/sec |
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Definition
d. 2.5 mL/sec
The flow rate may be calculated by divinding the total contrast volume by the time of the injection. In this example, the total contrast volume is 125 mL and the time for the injection is 50 seconds. the flow rate programmed for the injection would be 125/50, or 2.5 mL per second. |
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Term
4. The acronym CTDI is used to describe which of the following?
a. a specialized CT imaging technique used to measure bone mineral density.
b. a quality control test that measures the accuracy of the laser lighting system.
c. the radiation dose to the patient during a CT scan.
d. a high-speed CT scanner used for cardiac imaging. |
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Definition
c. the radiation dose to the patient during a CT scan.
The CT dose index (CTDI) is used to quantify the radiation dose received by the patient during a CT scan. It involves the use of an ionization chamber to accurately measure radiation exposure for a given set of technical factors. |
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Term
While one is obtaining a thorough history from a patient prior to the intravenous injeciton of an iodinated contrast material, which of the folowing topics should be included?
1. any prior allergic reactions to contrast media
2. presence of HIV or hepatitis infection
3. history of ashtma
a. 1 only
b. 1 and 2 only
c. 1 and 3 only
d. 1, 2, and 3 |
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Definition
c. 1 and 3 only
Prior reactions to contrast media and a history of asthma are factors that increase the incidence of adverse reaction to iodinated contrast media. It is therefore vital to question the patient regarding these factors prior to contrast agent administration. Teh presence of the human immunodeficiency virus (HIV) or hepatitis does not increase the incidence of adverse reaction to ionidated contrast media. Because universal precautions govern the protection of all patients and health care professionals, there is no need to question the patient regarding these factors. |
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Term
6. Which of the following factors may affect a patient's calculated glomerular filtration rate (GFR)?
1. age
2. sex
3. race
a. 1 and 2 only
b. 2 and 3 only
c. 1 and 3 only
d. 1, 2, and 3 |
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Definition
d. 1, 2, and 3
GFR is calculated using the patient's measured serum creatinine level and takes into account the patient's age, sex, and race. |
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Term
7. which of the following intravenous contrast agent administration methods provides the greatest overall plasma iodine concentrated?
a. drip infusion
b. bolus technique
c. biphasic technique
d. CT portography |
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Definition
b. bolus technique
A bolus administration of contrast agent requires the entire volume of material to be injected over the shortest possible time. Accomplished by hand or with the use of an automatic injector, bolus administration provides the maximum plasma iodine concentration and subsequent tissue enhancement. |
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Term
8. A patient in shock may exhibit which of the following symptoms?
1. tachycardia
2. rapid, shallow breathing
3. cyanosis
a. 1 only
b. 1 and 2 only
c. 1 and 3 only
d. 1, 2, and 3 |
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Definition
d. 1, 2, and 3
General signs and symptoms that a patient is going into shock include: rapid breathing, tachycardia, hypotension, weak pulse, pallor, cyanosis, and cold, clammy skin. |
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Term
9. The drug SOLU-CORTEF may be classified as which of the following?
a. anticholinergic
b. bronchodilator
c. antihistamine
d. corticosteroid |
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Definition
d. corticosteroid
SOLU-CORTEF is a brand name for hydrocortisone, which is a type of corticosteroid. This drug, or other types of corticosteroids, may be used during the treatment of anaphylactoid reactions to iodinated contrast materials. |
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Term
10. Which of the following technical factos has a direct effect on patient dose?
a. matrix size
b. algorithm
c. mAs
d. window level |
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Definition
c. mAs
With no consideration of image quality, reductions in mA and/or scan time (seconds) are direct methods of decreasing paitent dose during a CT exam. |
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Term
11. Which of the following is a non-ionic contrast material?
a. iodamide
b. iotahlamate
c. iohexol
d. diatrizoate |
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Definition
c. iohexol
non-ionic contrast media include iopamidol (Isovue), iohexol (Omnipaque), and iopromide (Ultravist). |
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Term
12. which of the following terms is used to describe a patient who is having difficulty breathing?
a. dyslexia
b. dyspnea
c. dysphagia
d. dysphasia |
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Definition
b. dyspnea
The term dyspnea may be defined as the condition of difficult breathing. |
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Term
13. Which of the following devides is used to measure the patient dose from a CT examination?
a. Geiger counter
b. Proportional counter
c. ionization chamber
d. film badge |
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Definition
c. ionization chamber
An ionization chamber is a device used to accurately measure radiation exposure. Radiation causes ionization within the chamber, which is measured by an electrode. The amount of charged particles is proportional to the radiation exposure. The ionization chamber is an extremely accurate device that is used to quantify radiation exposure from a CT scan. |
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Term
14. Which of the following describes the situation in which an assumption is made that an unconscious or otherwise physically unable patient consents to medical treatment?
a. informed consent
b. witnessed consent
c. patient proxy
d. implied consent |
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Definition
d. implied consent
Implied consent occurs when a patient is in need of immediate medical services but is unconscious or physically unable to consent to treatment. The assumption is made that the patient would consent is able. |
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Term
15. Complete cardiac diastole corresponds to which portion of the cardiac cycle on an electrocardiogram (ECG)?
a. P wave
b. QRS complex
c. Alpha wave
d. T wave |
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Definition
d. T wave
Complete cardiac diastole is the period of atrial and ventricular relaxation after heart contraction. The T-wave of an ECG corresponds to cardiac diastole. |
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Term
16. During CT arthrography, iodinated contrast media is injected directly into the:
a. joint space
b. intrathecal space
c. subarachnoid space
d. venous bloodstream |
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Definition
a. joint space
Iodinated water-soluble radiopaque contrast media (RCM) are injected directly into the joint space of interest during CT arthrography. |
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Term
17. Which of the following is considered one of the iso-osmolar contrast media (IOCM)?
a. iodixanol
b. iopamidol
c. iohexol
d. ioversol |
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Definition
| a. Iodixanol Iodixanol (Visipaque) is an example of a non-ionic iso-osmolar contrast agent. Iohexol (Omnipaque), isopamidol (Isovue), and ioversol (Optiray) are all non-ionic low-osmolar contrast media (LOCM). |
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Term
18. A common site for the IV administration of iodinated contrast media is the anterior recess of the elbow, otherwise known as the :
a. brachial fossa
b. olecranon fossa
c. retro-ulnar space
d. antecubital space |
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Definition
d. antecubital space
Antecubital space refers to the anterior recess of the elbow. It contains the basilic vein medially and the cephalic vein laterally. Both veins are common sites for the IV administration of iodinated contrast media. |
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Term
19. The potentially serious decline in renal function following the IV administration of contrast material is called:
a. anaphylaxis
b. brochospasm
c. contrast-induced nephrotoxicity (CIN)
d. urticaria |
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Definition
c. contrast-induced nephrotoxicity
Contrast-induced nephrotoxicity (CIN) is a potentially serious delayed effect of contrast agent administration. It is a considerable decline in renal function that can occur after a patient receives an IV contrast agent. CIN is typically marked by an increase in serum creatinine concentration in comparison with a baseline measurement obtained prior to contrast agent administration. |
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Term
| 20. The quantity of absorbed radiation dose based on the radiosensitivity of a particular tisure type is called: a. stochastic dose b. kerma c. effective dose d. CTDI |
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Definition
| c. effective dose Effective dose accounts for the type of tissue that the radiation is deposited in. Different tissues are assigned weighting factors on the basis of their individual radiosensitivities. Effective dose approximates the relative risk from exposure to low doses of ionizing radiation. The unit of measurement for effective dose is the sievert (Sv). |
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Term
| 21. Advantages of a saline flush immediately following the IV administration of iodinated contrast material include: 1. reduction in required contrast agent dose 2. reduction in the incidence of contrast-induced nephrotoxicity (CIN) 3. reduction of streaking artifact from dense contrast agent in the vasculature a. 1 only b. 3 only c. 2 and 3 only d. 1, 2, and 3 |
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Definition
| d. 1, 2, and 3 The use of a saline flush also improves the overall contrast agent utilization efficiency of the CT examination. |
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Term
22. Which of the following medications may be administered to dilate the coronary vasculature prior to a cardiac CT examination?
a. sublingual nitroglycerine
b. a B-adrenergic receptor blocking agent (B-blocker)
c. atropine
d. albuterol |
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Definition
a. sublingual nitroglycerine
If not contra-indicated, sublingual nitroglycerine may be administered just prior to the cardiac multislice CT (MSCT) study to cause dilation of the coronary vessels, improving their visualization. Please consult the referring physician and/or department protocol for further information regarding pharmaceutical administration for cardiac CT procedures. |
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Term
23. A normal range for distolic blood pressure in an adult is:
a. 40-60 mm Hg
b. 60-90 mm Hg
c. 80-120 mm Hg
d. 95-140 mm Hg |
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Definition
b. 60-90 mm Hg
The normal range for diastolic blood pressure in adults is 60-90 mm Hg. Diastolic pressure is the measurement of blood pressure at its lowest point, in betweet contractions of the heart. |
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Term
Which of the following is a parenteral route of medication administration?
a. sublingual
b. intramuscular
c. transdermal
d. oral |
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Definition
b. intramuscular
Parenteral administration involves the injection of medication into the body. Common routes of parental medication administration include intramuscular, intravenous, intradermal, and subcutaneous. |
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Term
25. which of the following methods may be employed to reduce the radiation dose to the pediatric patient undergoing CT?
1. reduce mA
2. limit phases of acquisition
3. increase pitch
a. 1 only
b. 1 and 2 only
c. 1 and 3 only
d. 1, 2, and 3 |
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Definition
d. 1, 2, and 3
The selected mA shoud be adapted to each patient according to size and/or weight. Eliminating unnecessary CT scans at the discretion of the physician is an additional way to reduce pediatric dose. |
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Term
26. Radiatio exposure and its potentially harmful effects have a relationship that is termed ______ in nature.
a. stochastic
b. nonstochastic
c. neglible
d. somatic |
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Definition
a. stochatic
Certain harmful effects of exposure to diagnostic x-rays, such as cancer formation and genetic mutations, are said to be random, or stochastic, in nature. A stochastic effect is one that has no threshold dose but increases in probability with increasing dose. |
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Term
27. Which of the following types of isolation techniques protects against infection transmitted through fecal material?
a. acid-fast bacillus isolation
b. contact isolation
c. enteric precautions
d. drainage-secretion precautions |
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Definition
c. enteric precautions
Enteric precautions attempt to protect from the spread of infection through direct or indirect contact with fecal matter. Gowns and gloves are common protective devices used for enteric precautions. The use of a surgical mask is not warranted. |
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Term
28. Which of the following is considered one of the ionic radiopaque contrast media (RCM)?
a. iohexol
b. iothalamate meglumine
c. iopamidol
d. ioversol |
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Definition
b. iothalamate meglumine
Ionic contrast media are salts consisting of sodium and/or meglumine. |
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Term
29. The radiation dose index calculation that takes into account the variations in absorption across the field of view due to beam hardening is termed:
a. CTDIw
b. CTDI100
c. CTDIvol
d. MSAD |
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Definition
a. CTDIw
CTDIw is calculated from measurements made with dosimeters positioned at the center and periphery of a phantom and accounts for the variance in dose distribution due to the effects of beam hardening. |
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Term
30. Direct contraindications to the administration of iodinated contrast material include:
1. prior life-threatening reaction to iodinated contrast material
2. multiple myeloma
3. diabetes
a. 1 only
b. 1 and 2 only
c. 1 and 3 only
d. 1, 2, and 3 |
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Definition
a. 1 only
Several factors may be regarded as contraindications to administration of iodinated contrast material, including known allergy to iodine, prior severe reaction, and renal insufficiency. Multiple myelome and diabetes, although not absolute contraindications to IV administration of iodinated contrast agents, do require attention to the patient's hydration level to limit renal complications. |
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Term
31. Which of the following units is used to express the total patient dose from a helically aacquired CT examination?
a. roentgens (R)
b. curies (Ci)
c. R-cm (roentgens per centimeter)
d. mGy-cm (milligrays per centimeter) |
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Definition
d. mGy-cm (milligrays per centimeter)
The dose length product (DLP) is the total patient dose over a given scan acquisition length (z)and can be illustrated as the product of CTDIvol and scan length. The DLP is expressed in units of milligrays per centimeter (mGy-cm). |
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Term
32. Components of a comprehensive CT stroke management protocol typically include:
1. pre-contrast sequence of the brain
2. CTA of the brain and carotids
3. CT perfusion (CTP) of the brain
a. 2 only
b. 1 and 2 only
c. 2 and 3 only
d. 1, 2, and 3 |
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Definition
d. 1, 2, and 3
Found typically in the emergency setting, a comprehensive acute stroke CT imaging protocol begins with a pre-contrast sequence to evaluate for hemorrhage. After the IV administration of an iodinated contrast agent, a CTA acquisition is performed through the carotid vessels and brain. CTP is then performed to evaluate potential cerebral perfusion defects secondary to stroke. |
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Term
Fig. 5-1 33. Number 1 on the figure corresponds to which of the following?
a. left pulmonary artery
b. ascending aorta
c. inferior vena cava
d. descending aorta |
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Definition
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Term
Fig. 5-1
34. Which number on the figure corresponds to the superior vena cava?
a. 2
b. 3
c. 4
d. 5 |
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Definition
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Term
Fig. 5-1
35. The abnormal density located in the posterior portion of the left lung field on the figure has an average attenuation value of +5.0 Housnfield units. This density most likely represents:
a. pneumothorax
b. hermothorax
c. atelectasis
d. pleural effusion |
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Definition
d. pleural effusion
Pleural effusions are commonly seen in the posterior portion of the lung field on images obtained with the patient in a supine position on the CT table. Differentiation between pleural effusion and pleural thickening is made when region of interest (ROI) measurements reveal fluid with density readings at or slightly above zero. Pleural effusion may be caused by multiple pathologic processes including infection, neoplasm, and congestive heart failure. |
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Term
36. Simple cysts of the kidney have average attentuation values in the range of
a. -40 to 0 Hounsfield units
b. 0 to +20 Hounsfield units
c. +30 to +50 Hounsfield units
d. above +60 Hounsfield units |
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Definition
b. 0 to +20 Hounsfield units
Simple cysts contain primarily water and therefore exhibit CT numbers ranging from approximately 0 (or slightly below) to +20 Hounsfield units. |
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Term
37. After iniation of rapid bolus administration of an iodinated contrast agent, the 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 |
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Definition
b. 25-35 seconds
The arterial phase is the period of peak arterial enhancement typically occurring at 25-35 seconds after the iniation of contrast agent administration. During this phase, hypervascular tumors or tumors supplied by the hepatic artery undergo maximal enhancement. |
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Term
Fig. 5-2 38. Number 2 on the figure corresponds to which of the following?
a. left internal jugular vein
b. left external carotid artery
c. left internal carotid artery
d. left external jugular vein |
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Definition
| c. left internal carotid artery |
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Term
fig. 5-2
39. Number 5 on the figure corresponds to which of the following?
a. right internal jugular vein
b. right external carotid artery
c. right internal carotid artery
d. right external jugular vein |
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Definition
| a right internal jugular vein |
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Term
fig. 5-2
40. Number 1 on the figure corresponds to which of the following?
a. vocal cords
b. uvula
c. aryepiglottic fold
d. epiglottis |
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Definition
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Term
41. The abdominal aorta bifurcates at the level of:
a. T10
b. T12
c. L2
d. L4 |
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Definition
D. L4
The abdominal aorta descends to the level of the fourth lumbar vertebra (L4), where it bifurcates into the left and right common iliac arteries. |
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Term
42. On an ECG of the complete cardiac cycle, at which portion of the R-R interval is the heart muscle in diastole?
a. 10%-20%
b. 35%-50%
c. 55%-75%
d. 85%-95% |
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Definition
c. 55%-75%
The least heart motion occurs at approximately 55% to 75% of the R-R interval, typically corresponding to the point of mid-diastole. |
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Term
43. The accumulation of gas within a degenerating intervertebral disc is called the:
a. aeration effect
b. vacuum phenomenom
c. oxygen saturation point
d. carbonization sign |
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Definition
b. vacuum phenomenon
Small amounts of gas may appear in the areas of degenerated intervertebral discs. The accumulation of gases such as nitrogen occurs as a by-product of the physical breakdown of the disc material. |
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Term
44. During a spiral or helical CT examination, the scanner acquires data:
1. continuously as the patient travels through the gantry
2. one section at a time
3. in the form of a complete volumetric data set
a. 1 only
b. 2 only
c. 1 and 3 only
d. 2 and 3 only |
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Definition
c. 1 and 3 only
Spiral/helical CT examinations are obtained with the scanner continuously acquiring data as the patient travels through the gantry. The data acquired are volumeteric, containing all of the attentuation information for a given area of anatomy. |
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Term
45. Which of the following CT studies of the head is typically performed without a contrast agent?
a. CT angiogram for circle of Willis
b. coronal scan to rule out (R/O) pituitary tumor
c. CT of brain to R/O subdural hematoma
d. CT of brain to R/O metastatic disease |
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Definition
c. CT of brain to R/O subdural hematoma
Because of their increase in CT number, subdural hematomas may be well visualized without the IV administration of an iodinated contrast agent. |
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Term
46. Which of the following phases of renal contrast enhancement best demonstrates transitional cell carcinoma (TCC) of the bladder?
a. early arterial
b. corticomedullary
c. nephrographic
d. excretory |
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Definition
d. excretory
Excretory phase acquisitions after a delay of 3 to 15 minutes demonstrate the urinary tract while it is opacified with a contrast agent. Transitional cell lesions of the urothelium appear as filling defects within the bladder, ureters, and/or renal pelvis. |
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Term
fig. 5-3
47. Number 5 on the figure corresponds to which of the following?
a. transverse colon
b. stomach
c. duodenum
d. hepatic flexure |
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Definition
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Term
fig. 5-3
48. Which of the following most likely describes the patient position during the formation of the image in the figure?
a. supine
b. prone
c. left lateral decubitis
d. right lateral decubitis |
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Definition
| d. right lateral decubitis |
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Term
fig. 5-3
49. CT examinations of the abdomen are often performed in the position on the figure to demonstrate the relationship between the:
a. ureters and renal collecting systems
b. duodenum and pancreatic head
c. large and small colon
d. liver and gallbladder |
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Definition
| b. duodenum and pancreatic head |
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Term
fig. 5-3
50. Number 3 on the figure corresponds to which of the following?
a. right ureter
b. inferior vena cava
c. renal calculi
d. right renal artery |
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Definition
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Term
51. Which of the following sets of section width and spacing would be most suitable for a general survery CT of the neck?
a. 0.75 mm thick every 0.75 mm
b. 3 mm thick every 5 mm
c. 3 mm thick every 3 mm
d. 10 mm thich every 10 mm |
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Definition
c. 3 mm thick every 3 mm
A continuous study with section widths ranging from 3 to 6 mm is sufficient for a general survey CT study of the neck. |
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Term
52. The still viable ischemic cerebral tissue that surrounds the infarct core in a patient with and acute stroke is termed the:
a. thrombolytic zone
b. hemorrhage focus
c. ischemic penumbra
d. stroke volume |
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Definition
| c. Penumbra is the ischemic, yet still viable tissue immediately surrounding the infarct core. It can be described as the region of ischemic brain parenchyma where cerebral blood volume (CBV) is compromised but still higher than 2.5 mL per 100 g of tissue. |
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Term
53. Complex fractures of the wrist are most common in which of the following carpal bones?
a. hamate
b. scaphoid
c. capitate
d. triquetrum |
|
Definition
b. scaphoid
The wrist's scaphoid bone (navicular) is a common location for complex fracture. |
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Term
54. A complete CT study of the orbits shoud include:
a. 5 mm x 5 mm axial secions only
b. 10 mm x 10 mm axial and coronal sections
c. 3 mm x 3 mm coronal sections only
d. 2.5 mm x 2.5 mm axial and coronal sections |
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Definition
| d. 2.5 mm x 2.5 mm axial and coronal sections Narrow section (1-3 mm) are required in both the axial and coronal planes to properly demonstrate the orbits. Isotropic MDCT acquisition may provide multiplanar reformation images of sufficient quality to preclude the need for an additional scan in a second plane. |
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Term
55. High-resolution compuoted tomography (HRCT) is most commonly used for the evaluation of the:
a. pancreas
b. brain
c. lungs
d. pelvis |
|
Definition
c. lungs
High-resolution CT is a specialized technique using narrow section widths and a high-resolution algorithm for image reconstruction. It is used to maximize detail of high spatial frequency tissue, such as the lungs and bony structures. |
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Term
56. Which of the following technical maneuvers may be used to remove unwanted pulsation artifacts from cardiac motion during a CTA of the ches tfor pulmonary embolism?
a. automated bolus tracking
b. automatic tube current modulation
c. retrospective ECG gating
d. saline flush |
|
Definition
c. retrospective ECG gating
Electrocardiographic (ECG) gating can be utilized to eliminate pulsation artifacts due to cardiac motion during the study. Retrospective gating involves scanning throughout the entire cardiac cycle. Only data from specific user-determined portions of the ECG waveform are reconstructed into images. |
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Term
57. During a general CT examination of the abdomen, an intravenous contrast agent is indicated and is administered with the aid of an automatic injector. Which of the following ranges of flow rate should be used?
a. 0.2-1.0 mL/sec
b. 1.0-3.0 mL/sec
c. 4.0-6.0 mL/sec
d. 7.0-10.0 mL/sec |
|
Definition
b. 1.0-3.0 mL/sec
The flow rate range 1.0 to 3.0 mL/sec should be sufficient to provide the nehancement necessary for proper evaluation of the abdomen. This is a general range that may be adjusted to meet the needs of the exam at the discretion of the physician and medical personnel involved for each patient. |
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Term
58. Diffuse fatty infiltration of hte hepatic parenchyma may be referred to as:
a. chromatosis
b. steatosis
c. cirrhosis
d. lipomatosis |
|
Definition
b. steatosis
Fatty liver disease, or heptic steatosis, is a condition in which large quantities of fats (lipids) are retianed within the liver. Whereas normal liver parenchyma exhibits attenuation values approxiamtely 10 HU higher than those of the spleen, the liver with steatosis has attenuation values at least 10 HU below those of the spleen. |
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Term
fig. 5-4
59. Which of the following corresponds to the low attentuation area indicated by Number 3 on the figure?
a. renal cortex
b. renal pelvis
c. renal calyx
d. renal pyramid |
|
Definition
|
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Term
| fig. 5-4 60. The data for this reformatted image of the abdomen was most likely acquired in which of the following renal enhancement phases? a. pre-contrast b. corticomedullary c. nephrographic d. excretory |
|
Definition
b. corticomedullary
Â
Beginning 30 to 40 seconds after the initiation of contrast agent administration, the corticomedullary phase demonstrates optimal enhancement of the renal cortex with maximum differentiation of the cortex from the renal medulla. |
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Term
fig 5-4
61. Number 2 on the figure corresponds to which of the following?
a. hepatic vein
b. suprarenal lymph node
c. adrenal gland
d. common bile duct |
|
Definition
|
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Term
fig. 5-4
62. Number 6 on the figure corresponds to which of the following?
a. psoas muscle
b. omentum
c. piriforms
d. erector spinae muscle |
|
Definition
|
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Term
63. CT images of the chest should be acquired with the patient:
a. at full inspiration
b. breathing quietly
c. at full expiration
d. breathing normally |
|
Definition
a. at full inspiration
Patient inspriation provides optimal chest expansion and allows for better demonstration of anatomic structures. |
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Term
64. During CT scanning of the head, the gantry should be angled:
a. 15 degrees above the infraorbital-meatal line (IOML)
b. 10 degrees below the IOML
c. 0 degrees
d. 20 degrees above the skull base |
|
Definition
a. 15 degrees above the infraorbital-meatal line (IOML)
Routine CT scanning of the head should be performed with the gantry angled 15 degrees above the infraorbital-meatal line. This angle produces axial sections of the brain while limiting beam-hardening artifacts and direct orbital exposure. |
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Term
65. During CT examination of the larynx, the patient is often instructed to phonate the letter "E" in order to properly evaluate the:
a. epiglottis
b. uvula
c. trachea
d. vocal cords |
|
Definition
d. vocal cords
The patient should be instructed to phonate the letter "E" during CT scanning of the larynx. As data are acquired during scanning, the patient's phonation requires vibration of the vocal cords, thus allowing for thorough evaluation of their mobility. |
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Term
fig. 5-5
66. NUmber 2 corresponds to which of the following?
a. carotid canal
b. incus
c. cochlea
d. vestibule |
|
Definition
|
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Term
fig. 5-5
67. Number 4 corresponds to which of the following?
a. external auditory meatus
b. internal auditory canal
c. vestibule
d. carotid canal |
|
Definition
|
|
Term
fig. 5-5
68. Which of the follwing display field of view (DFOV) values was most likely used to display the image?
a. 9.6 cm
b. 18.0 cm
c. 25.6 cm
d. 51.2 cm |
|
Definition
a. 9.6 cm
Targeted reconstructions should be performed bilaterally utilizing a small display field of view (DFOV) or a higher zoom factor to maximize resolution of the small bony components of the inner ear. |
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Term
fig. 5-5
69. Number 3 on the figure corresponds to which of the following?
a. vestibule
b. semicircular canal
c. cochlea
d. incus |
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Definition
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Term
70. During a CT examination of a female pelvis for a suspected malignancy, ascites may be present in an area posterior to the utuerus and ovaries known as:
a. the cul-de-sac
b. Morison's pouch
c. the space of Retzius
d. The prevesical compartment |
|
Definition
a. cul-de-sac
The cul-de-sac is the area posterior to the uterus and ovaries in the female patient. It is a common site for ascites in the patient with pelvic pathology. |
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Term
71. Which of the following pathologic processes may be considered an interstitial disease of the lungs?
a. bronchiectasis
b. mediastinal lymphadenopathy
c. pulmonary metasis
d. bronchogenic carcinoma |
|
Definition
a. bronchiectasis
Interstitial diseases of the lungs are usually diffuse pathologic processes involving the intersititium, or framework, of the lungs. Examples of interstitial diseases are bronchiectasis, emphysema, asbestosis, and sarcoidosis. |
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Term
72. An enterovesical fistula is an abnormal communication between the bowel and the:
a. uterus
b. bladder
c. vagina
d. umbilicus |
|
Definition
b. bladder
An enterovesical fistula is an abnormal communicaiton between the bowel and the bladder. It typically results from the inflammatory processes of the colon such as diverticulitis. |
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Term
73. Prior to a CT colonography, the patient may undergo a process of bowel cleansing termed:
a. purgation
b. hydration
c. catharsis
d. fasting |
|
Definition
c. catharsis
Catharsis describes the process of bowel cleansing that is required to improve the exam quality of CT colonography. A combination of resticted diet and bowel cleansing with polyethylene glycol (PEG) or magnesium citrate is used to achieve catharsis. |
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Term
74. Positioning the patient with the knees flexed over a foam cushion during a CT examiniation of the lumber spine assists in:
1. decreasing the kyphotic curvature of the lumber spine
2. making the patient more comfortable throughout the exam.
3. decreasing the lordotic curvature of the lumbar spine
a. 1 only
b. 2 only
c. 3 only
d. 2 and 3 only |
|
Definition
d. 2 and 3 only
During a CT examination of the lumbar spine, a foam cushion should be placed under the patient's flexed knees. This maneuver reduces strain on the lower back, making hte patient more comfortable and cooperative. It also reduces the lordotic curve of the lumbar spine, allowing for more accurate imaging of the intervertebral disc spaces. |
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Term
75. The imaging plane that is parallel to the foot's plantar surface is called the:
a. coronal plane
b. sagittal place
c. axial plane
d. oblique axial plane |
|
Definition
c. axial plane
The axial plane is prarllel to the foot's plantar surface. The oblique axial plane is parallel to the metatarsals, approxiamtely 20 to 30 degrees caudal from the direct axial plane. |
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Term
76. The condition of intermittent cramping pain in the legs due to poor circulation is called:
a. varices
b. claudication
c. stenosis
d. thrombosis |
|
Definition
b. claudication
Claudication refers to the condition of intermittent cramping pain in the legs due to poor circulation. |
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Term
fig. 5-6
77. The pathologic process indicated by number 3 on the figure most likely corresponds to:
a. atelectsis
b. lymphadenopathy
c. pleural effusion
d. ground-glass opacity |
|
Definition
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Term
| fig 5-6 78 Number 1 on the figure corresponds to which of the following? a. right atrium b. pulmonary trunk c. ascending aorta d. right ventricle |
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Definition
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Term
fig. 5-6
79. This HRCT image of the chest was most likely acquired with a section width of:
a. 1 mm
b. 5 mm
c. 7 mm
d. 10 mm |
|
Definition
a. 1 mm
HRCT acquisitions of the chest should be performed with thin sections, within the range of 1 to 2 mm. |
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Term
fig. 5-6
80. Number 2 on the figure corresponds to which of hte following?
a. left mainstem bronchus
b. anterior segment of left upper lobe bronchus
c. posterior segment of left upper lobe bronchus
d. anterior segment of left lower lobe bronchus |
|
Definition
| b. anterior segment of left upper lobe bronchus |
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Term
81. The pituitary gland is best demonstrated during CT in which of the following imaging planes?
a. axial
b. coronal
c. sagittal
d. transaxial |
|
Definition
b. coronal
The pituitary and other structures involving the sella turcica are usually imaged in the coronal plane with CT. The coronal plane provides the best visualization of the pituitary gland with regard to its position within the sella turcica and involves less partial volume averaging of the pituitary with surrounding structures than scans obtained in the axial plane. |
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Term
82. The most common site of organ injury due to blunt abdominal trauma is the:
a. liver
b. kidney
c. spleen
d. pancreas |
|
Definition
c. spleen
The spleen is the most common site of organ injury due to blunt abdomnial trauma. Hematoma, hemorrhage, and laceration are typical signs of traumatic splenic injury. |
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Term
fig. 5-7
83. Number 7 on the figure corresponds to which of the following?
a. duodenum
b. pancreatic head
c. jejunum
d. gallbladder |
|
Definition
|
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Term
fig. 5-7
84. Number 2 on the figure corresponds to which of the following?
a. superior mesenteric vein
b. superior mesenteric artery
c. renal artery
d. portal vein |
|
Definition
| a. superior mesenteric vein |
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Term
fig. 5-7
85. Number 8 on the figure corresponds to which of the following?
a. duodenum
b. descending colon
c. jejunum
d. ascending colon |
|
Definition
|
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Term
86. The adult spinal cord ends at what vertebral level?
a. T11-T12
b. L1-L2
c. L3-L4
d. superior portion of the coccyx |
|
Definition
b. L1-L2
The spinal cord extends to the lower margin of the first or upper margin of the second lumbar vertebra. At this level it tapers to a point known as the conus medullaris. |
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Term
87. Which of hte following protocols would provide the best image quality for a 3D disarticultion study of the hip?
a. 10 mm x 15 mm sections, standard algorithm
b. 10 mm x 10 mm sections, bone algorithm
c. 1.5 mm x 1.0 mm sections, bone algorithm
d. 5 mm x 7 mm sections, standard algoithm |
|
Definition
c. 1.5mm x 1.0 mm sections, bone algorithm
Three-dimensional studies are best perfomed with the use of narrow sections acquired with no spacing or, preferably , an overlap. A detail (bone) algorithm is used for optimal demonstration of bony structures. |
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Term
88. Which of the follwing terms is used to describe a fibroid tumor of hte uterus?
a. leiomyoma
b. cystic teratoma
c. endometriosis
d. corpus luteum |
|
Definition
a. leiomyoma
A leiomyoma is a benign mass of smooth muscle. It commonly occurs in the uterus and is readily identified on CT examination as a bulky, nonspecific uterine enlargement. |
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Term
fig. 5-8.
89. Number 1 on the figure corresponds to which of the following?
a. sphenoid sinus
b. ethmoid sinus
c. frontal sinus
d. maxillary sinus |
|
Definition
|
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Term
fig. 5-8
90. The section thickness that would demonstrate the greatest detail of the paranasal sinuses is:
a. 3 mm
b. 5 mm
c. 7 mm
d. 10 mm |
|
Definition
a. 3 mm
The section thickness of a CT scan directly affects the detail and spatial resolution of the image. Narrow section widths result in greater detail for imaging of small anatomic parts such as the sinuses. |
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Term
fig. 5-8
91. Which number on the figure corresponds to the zygomatic bone?
a. 3
b. 1
c. 2
d. 6 |
|
Definition
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Term
92. Which of the following anatomic organs is located within the peritoneal cavity?
a. pancreas
b. kidneys
c. uterus
d. liver |
|
Definition
d. liver
the peritonial cavity is formed by the membranous sac called the peritoneum. It contains the stomach, liver, gallbladder, spleen, ovaries, transverse colon, and most of the small bowel. |
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Term
93. Which of the following may be included as part of a routine preparation for a general contrast-enhanced CT examination of the abdomen and pelvis?
1. instructing the patient to take nothing by mouth (NPO) for 4 hours prior to exam
2. 1200 mL or oral contrast agent administered 90 minutes prior to exam
3. having the patient drink 4 liters of polyethylene glycol (PEG) 24 hours prior to exam.
a. 1 only
b. 2 only
c. 1 and 2 only
d. 1 and 3 only |
|
Definition
c. 1 and 2 only
Routine preparations for genrela studie sof the abdomenn and pelvis include the administration of an oral contrast agent for opacificaiton of the GI tract. Patients are typically instructed to refrain from eating or drinking anything else for up to 6 hours prior ro the exam. Polyethylene glycol (PEG) is used for bowel cleansing prior to a colonoscopy and may have certain applications for CT preparation limited to CT colography. |
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Term
94. During a complete CT scan of the pelvis, sections should be obtained from the:
a. iliac crests to the pubic symphysis
b. kidneys through the bladder
c. bottom of the kidneys to the pubic symphysis
d. iliac crests to the lesser trochanter |
|
Definition
a. iliac crests to the pubic symphysis
Complete CT scans of the pelvis should include from the iliac crests to the pubic symphysis. This scan range may be extended if clinically warranted. Scan parameters (i.e., slice thickness, incrementation) can be adjusted to correlate with the patient's clinical history. |
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Term
95. The recommended scan field of view (SFOV)for a CT examination of the cervical spine is:
a. 9.6 cm
b. 15.0 cm
c. 25.0 cm
d. 50.0 cm |
|
Definition
d. 50.0 cm
Acquisistion of the cervical spine is performed with a large SFOV, 48 to 50 cm. |
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Term
fig. 5-9
96. Number 4 on the figure corresponds to which of the following?
a. navicular
b. cuboid
c. calcaneus
d. talus |
|
Definition
|
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Term
fig. 5-9
97. Which of the following best describes the type of image displayed in the figure?
a. sagittal maximum intensity projection (MIP)
b. direct sagittal acquisition
c. sagittal multiplanar reformation (MPR)
d. volume-rendered 3D |
|
Definition
| c. sagittal multiplanar reformation (MPR) |
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Term
fig. 5-9
98. Number 6 on the figure corresponds to which of the following?
a. navicular
b. cuboid
c. calcaneus
d. talus |
|
Definition
|
|
Term
fig. 5-9
99. Number 1 on the figure corresponds to which of the following?
a. navicular
b. cuboid
c. calcaneus
d. talus |
|
Definition
|
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Term
100. Because of its inherent iodine concentration, the thyroid gland appears ________on CT images.
a. hypodense
b. isodense
c. hyperdense
d. mottled |
|
Definition
c. hyperdense
In comparison with the surrounding soft tissues, the thyroid gland is hyperdense on CT because it naturally contains iodine. This density increases further with administration of a n iodinated contrast agent. |
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Term
101. Air trapping within the trachea and bronchial tree may be optimally demonstrated with multiplanar volume reconstructions (MPVRs) of the thorax known as:
a. maximum intensity projections (MIPs)
b. 3D volume renderings
c. shaded-surface displays (SSDs)
d. minimum intensity projections (min-IPs) |
|
Definition
d. minimum intensity projections (min-IPs)
In the minimum intensity projection technique, displayed pixels represent the minimum attenuation value encountered along each sampled ray. Also referred to as min-IP, this type of multiplanar volume reconstruction (MPVR) can be applied to a volume of the thorax to demonstrate air trapping within the trachea and bronchial tree. |
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Term
fig. 5-10
102. Which number on the figure corresponds to the anterior horn of the lateral ventricle?
a. 1
b. 5
c. 3
d. 2 |
|
Definition
|
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Term
fig. 5-10
103. Number 3 on the figure corresponds to which of the following?
a. caudate nucleaus
b. thalamus
c. third ventricle
d. pineal gland |
|
Definition
|
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Term
fig. 5-10
104. Which number on the figure corresponds to the septum pellucidum?
a. 2
b. 3
c. 4
d. 5 |
|
Definition
|
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Term
105. Which of the following is NOT a portion of the small bowel?
a. duodenum
b. jejunum
c. ileum
d. cecum |
|
Definition
d. cecum
The small bowel consists of the duodenum, the jejunum, and the ileum. The cecum is the proximal portion of the large bowel; it is connected to the small bowel at the ileocecal valva. |
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Term
106. Which of the following is used as the IV-administered radiopharmaceutical during a PET-CT fusion examination?
a. technetium Tc 99m
b. iodine I 131
c. fludeoxyglucose F 18 (FDG)
d. strontium chloride Sr 89 |
|
Definition
c. fludeoxyglucose F 18 (FDG)
Positron emission tomography (PET) is a functional nuclear medicine study utilizing fluorodeoxyglucose F18 (FDG) as a radiopharmaceutical. |
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Term
107. The specialized CT examination of the bladder in which an iodinated contrast agent is directly administered under gravity into the bladder via Foley catheter is termed:
a. CT IVP
b. CT urogram
c. CT enteroclysis
d. CT cystography |
|
Definition
d. CT cystography
A CT cystogram involves the administration of an iodinated contrast agent directly into the bladder via a Foley catheter. |
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Term
108. Which of the following best describes the shape of the x-ray beam utilized in MDCT?
a. pencil beam
b. fan-shaped
c. eletron beam
d. cone-shaped |
|
Definition
d. cone-shaped
Multislice CT (MSCT) utilizes a cone-shaped beam that is incident upon an expanded array of detectors. The detector array consists of multiple rows along the z-axis and requires a cone-shaped beam to measure incident radiation. |
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Term
109. Collimatin of hte CT x-ray beam occurs:
1. at the x-ray tube, regulating slice thickness
2. just beyond the patient, focusing off-axis transmitted radiation
3. before the detectors, limiting hte amount of scatter radiation absorbed.
a. 1 only
b. 1 and 2 only
c. 1 and 3 only
d. 1, 2, and 3 |
|
Definition
c. 1 and 3 only
Collimation of the x-ray beam in CT is accomplished by both pre-patient and pre-detector collimators, or detectors. The pre-patient detectors restrict the field size, directly influencing the reconstructed section thickness. The pre-dector or post-patient detectors absorb scatter radiation before it contributes to the signal produced by the detector array. |
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Term
110. CT numbers are usually provided in the form of:
a. Hounsfield units
b. EMI numbers
c. Cormacks
d. u |
|
Definition
a. Housnfield units
The CT number is a relative value based on the attenuation that occurs within a voxel of tissue. The Hounsfield unit is used for this value. |
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Term
111. Teh mathematical technique allowing the reconstruction of motion-free images from helically acquired CT data is called:
a. convolution
b. radon transformation
c. interpolation
d. Fourier reconstruction |
|
Definition
c. interpolation
Interpolation is the mathematical process whereby data from tube rotations just above and just below a given slice postion are used for image reconstruction. Interpolation allows for the reconstruction of a thin, motion-free image from a volumetric data set acquired from a moving patient. |
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Term
112. The full width at half maximum (FWHM)of a CT scanner is used to describe:
a. spatial resolution
b. contrast resolution
c. noise
d. calibration accuracy |
|
Definition
a. spatial resolution
The spatial resolution of a CT scanner can be measured by studying the amount of blurring that occurs around a point within the CT image. Known as the point spread function (PSF), this image unsharpness may be graphically represented. The spatial resolution can then be quantified by measuring the graph at half its maximum value. This measurement, called the full width at half-maximum (FWHM), is used to illustrate the spatial resolution of a CT scanner. |
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Term
113. A first-generation CT scanner consists of an x-ray tube and two detectors that translate across the atient's head while rotating in 1-degree increments for a total of:
a. 45 degrees
b. 90 degrees
c. 180 degrees
d. 360 degrees |
|
Definition
c. 180 degrees
First-generation CT scanners were based on a translate-rotate principle. The x-ray tube and detectors would translate across the patient's head and then rotate 1 degree. This process would repeat in a semicircular fashion, for 180 degrees around the patient's head. |
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Term
114. Which of the following abbrevations is used to identify a computerized network that stores, retrieves, communicates, and displays digital medical images?
a. WORM
b. PACS
c. DICOM
d. HIPAA |
|
Definition
b. PACS
Picture archival and communications systems (PACS) are computerized networks charged with the responsibility of storing, retrieving, distributing, and displaying CT and other digital medical images. |
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Term
115. The CT "window" controls the______ of the CT image as it appears to the viewer.
a. density and detail
b. spatial and contrast resolution
c. contrast and brightnes
d. attentuation coefficient and Hounsfield value |
|
Definition
c. contrast and brightness
The operator may control the contrast and brightness of the CT image by adjusting the "window" setting. As a form of gray-scale mapping, the window determines the pixels assigned shades of gray on the basis of their CT numbers. |
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Term
116. Voxels with equal dimensions along the x-, y-, and z-axes are referred to as:
a. prospective
b. isotropic
c. retrospective
d. anisotropic |
|
Definition
b. isotropic
Isotropic is used to describe voxels with equal dimensions along the x-, y-, and z-axes. The ability to acquire an isotropic data set is a distinct advantage of MDCT. |
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Term
117. Which of the following artifacts is not affected by the CT technologists?
a. motion
b. partial volume
c. edge gradient
d. ring |
|
Definition
d. ring
Although the CT technologist must be able to readily identify them, ring artifacts are caused by detector malfunction and are beyond his/her control. Patient motion, partial volume averaging, and edge gradient artifacts can all be limited by the CT technologist through adequate preparation and careful scan procedures. |
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Term
118. When one is viewing a multiplanar reformation (MPR) image, each pixel represents:
a. the maximum attenuation occurring within the voxel.
b. the average attentuation occurring within the voxel.
c. the minimum attenuation occurring within the voxel
d. all attenuation occurring within the voxel above a set threshold value |
|
Definition
b. the average attenuation occurring within the voxel.
A standard MPR image is 1 voxel thick, with the pixels facing the viewer each representing the average attenuation occurring within the represented voxels. |
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Term
119. Statistical noise appears as ______on a CT image.
a. decreased contrast
b. increased brightness
c. concentric circles
d. graininess |
|
Definition
d. graininess
Statistical noise is a term that may be used for quantum noise, or mottle. Caused by an insufficient number of photons being detected, this type of noise appears as graininess on the CT image. |
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Term
120. An acquisition is made on a 64-slice MSCT system in which each detector element has a z-axis dimension of 0.625 mm. With a selected beam width of 40 mm and the beam pitch st at 1.50, how much will the table move with each rotation of the gantry?
a. 20 mm
b. 40 mm
c. 60 mm
d. 80 mm |
|
Definition
c. 60 mm
The beam pitch for a given acquisition is equal to the table feed per rotation divided by the total collimation. The total collimation for this acquisition is equal to the total number of sections (detectors)multiplied by the detector dimension, or 64 x 0.625 nn, thetable feed per rotation can be calculated as the product of the total collimation and the beam pitch, or 40 mm x 1.5, and equals 60 mm for the example provided. |
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Term
121. The component of the CT computer system responsible for the data processing of image reconstruction is the:
a. pipeline memory
b. array processor
c. hard disk drive
d. RAM microprocessor |
|
Definition
b. array processor
The primary data processing component of the CT system is the array processor. It is responsible for receiving scan data from the host computer, performing all of the major processing of the CT image, and returning the reconstructed image to the storage memory of the host computer. |
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Term
122. For single-slice CT (SSCT) systems, which of the following statements regarding retrospective image reconstruction is FALSE?
a. The algorithm, matrix size, and DFOV may all be changed.
b. The slice thickness and SFOV may be changed.
c. Scan (raw)data must be available
d. Retrospective image reconstruction may be used to adjust the center of the image |
|
Definition
b. The slice thickness and SFOV may be changed
Retrospective reconstruction uses scan or "raw" data to change the matrix, DFOV, center, and/or algorithm used for a CT image. The slice thickness and SFOV are specifically used for data acquisition and cannot be altered retrospectively with a single-slice CT (SSCT) system. The advent of multisplice CT (MSCT) technology has made retrospective adjustments in section width possible. The scan field of view (SFOV) remains an item that may not be altered retrospectively. |
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Term
123. The loss of anatomic information between contiguous sections due to inconsistent patient breathing is called:
a. cupping artifact
b. misregistration
c. overshoot artifact
d. out-of-field artifact |
|
Definition
b. misregistration
Misregistration is an artifact that occurs when a patient suspends respiration at different depths during consecutive scans. It results in the loss of anatomic information. |
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Term
124. Before a CT image can be reconstructed by a computer, the transmission signal produced by the detectors must be converted into numerical information by a (n):
a. kernal
b. analog-to-digital converter (ADC)
c. array processor
d. digital-to-analog (DAC) |
|
Definition
b. analog-to-digital converter (ADC)
The analog-to-digital converter is responsible for transforming the analog signal from the detectors into a digital form that may be used by the computer. Analog information is based on a scale, whereas digital information is in numerical form. |
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Term
125. A CT image is formed in part by projecting back all of the attentuation values recorded during data acquisition onto a:
a. pixel
b. voxel
c. matrix
d. reformat |
|
Definition
c. matrix
The back-projection method of image reconstruction involves the acquisition of attenuation values, which are then projected back onto a matrix for subsequenet display. |
|
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Term
126. Which of the follwing archival media is capable of storing the largest number of CT images?
a. floppy disk
b. magnetic tape
c. VHS tape
d. optical disk |
|
Definition
d. optical disk
Magnetic optical disks vary in storage capacity, with some capable of sotring several thousand 512(squared) matrix CT images. This is considerably more than magnetic tape, which had previously been the standard choice for CT image archival. |
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Term
127. Areas of a CT image that contain abrupt changes in tissue density are electronically represent by which of the following?
a. positive CT numbers
b. high spatial frequencies
c. negative CT numbers
d. low spatial frequencies |
|
Definition
b. high spatial frequencies
The contrast of a CT image is controlled by the spatial frequencies of the tissue(s) within the section. Tissues of differing densities are represented electronically by different spatial frequencies. Adjacent tissues that greatly differ in density are represented by high spatial frequencies. |
|
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Term
fig. 5-11
128. Which of the following components of CT image quality are being evaluated in the figure?
1. low-contrast detectability
2. noise
3. uniformity
a. 2 only
b. 1 and 2 only
c. 1 and 3 only
d. 2 and 3 only |
|
Definition
d, 2 and 3 only
Noise is most commonly measured by scanning a water-filled phantom with a consistent set of technical factors. The image noise is equal to the standard deviation of pixel values within a region of interest (ROI) measurement of the image. Uniformity may also be evaluated by positioning several ROI measurements at different locations along the center and periphery of the image. The CT values should not differ by more than 2 HU from one location to another. |
|
|
Term
fig. 5-11
129. The differences in Hounsfield value exhibited in the ROIs measured on this CT image of a water-filled phantom are most likely due to the phenomenon referred to as:
a. partial volume averaging
b. noise
c. beam hardening
d. detector drift |
|
Definition
c. beam hardening
Beam hardening occurs as low-energy x-ray photons are absorbed while 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. |
|
|
Term
fig. 5-11
130. Which region of interest (ROI) on the figure demonstrates the greatest amount of image noise?
a. 1
b. 2
c. 3
d. impossible to determine from the information provided |
|
Definition
a. 1
The image noise is equal to the standard deviation of pixel values within an ROI measurement of the image. ROI number 1 on the figure demonstrates the highest value for standard deviation (SD = 2.87). |
|
|
Term
131. Which of the following terms is used to describe a set of rules for solving a mathematical problem?
a. reconstruction
b. algorithm
c. function
d. array |
|
Definition
b. algorithm
An algorithm may be defined as a set of rules or steps used to solve a mathematical problem. The programs used by the CT computer to reconstruct the image are often referred to as algorithms. |
|
|
Term
132. Which of the following factors does not affect the dimensions of a voxel?
a. slice thickness
b. matrix size
c. kernel
d. display field of view |
|
Definition
c. kernel
The dimensions of a voxel are determined by multiplying the pixel dimensions by the slice thickness. The dimensions of a pixel are directly controlled by the matrix size and the field of view. |
|
|
Term
133. The size of the CT image displayed on a computer monitor can be enlarged by increasing the:
1. DFOV
2. SFOV
3. image magnification
a. 1 only
b. 3 only
c. 1 and 2 only
d. 1 and 3 only |
|
Definition
b. 3 only
Increasing the display field of view (DFOV) for a reconstructed CT image decreases its displayed size. Electronically magnifying the image on the display system results in a larger displayed image but has no effect on pixel or voxel dimension. |
|
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Term
134. The average photon energy of the primary beam of a CT a scanner operating at tube potential of 120 kVp is approximately:
a. 50 keV
b. 70 keV
c. 100 keV
d. 120 keV |
|
Definition
b. 70 keV
The average photon energy of the primary beam used in CT is approximately 70 keV. The average photon energy of any radiographic primary beam is typically 30% to 40% of the applied kilovoltage. The average photon energy of the CT beam is increased through beam filtration. |
|
|
Term
135. MSCT systems typically employ which of the following detector geometries?
a. first-generation
b. second-generation
c. third-generation
d. fourth-generation |
|
Definition
c. third-generation
All MSCT systems utilize third-generation geometry and solid-state scintillation detectors. |
|
|
Term
136. The acquisition of a series of CT images at a single anatomic location over a set period is referred to as:
a. ultrafast CT
b. cine CT
c. conventional CT
d. temporal CT |
|
Definition
b. cine CT
Cine CT acquisition involves multiple axial scans obtained at a single anatomic level over a predetermined period. Clinical applications of cine CT acquisition include contrast bolus tracking, dynamic imaging of physiologic processes such as respiration, swallowing, and the cardiac cycle as well as for CT perfusion studies. |
|
|
Term
137. The rate at which a quantity of x-radiation emitted from a CT tube passes through a unit area over a unit of time is called the:
a. effective mAs
b. photon flux
c. constant mAs
d. photon fluence |
|
Definition
b. photon flux
The rate at which a quantity of radiation (photon fluency) passes through a unit area over unit time is termed the photon flux. It may also be referred to as the fluence rate. |
|
|
Term
138. An average CT number value for bone is:
a. +100 HU
b. +500 HU
c. +1000 HU
d. +3000 HU |
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Definition
c. +1000 HU
An average CT number value for bone is approximately +1000HU. This may vary widely with the density of the particular bone in question and with the be a quality of the CT scanner. |
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Term
139. A standard CT image reconstructed on a 512(squared) matrix has a digital size of approximately:
a. 0.5 MB
b. 3.0 MB
c. 5.0 MB
d. 10.0 MB |
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Definition
a. 0.5 MB
Each CT image reconstructed on a 512(squared) matrix is approximately 0.5 megabytes (MB) in digital size. |
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Term
140. The term used to describe the relationship between the linear attenuation coefficient of an object and the calculated CT numbers is:
a. linearity
b. mottle
c. quantum noise
d. spatial resolution |
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Definition
a. linearity
Linearity describes the relationship between the CT number and actual linear attenuation coefficients of an object. It is used to measure the accuracy of a CT scanner. |
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Term
141. Quality control measurements to test the accuracy of the CT scanner's calibration should be performed:
a. daily
b. weekly
c. monthly
d. annually |
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Definition
a. daily
It is important that the calibration of a CT scanner be checked daily by the operator. CT units should be calibrated with their reference CT number for water at approximately zero. The CT number for air should be at approximately -1000. |
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Term
142. The 3D CT technique that includes all of the acquired voxel information in the reconstructed model with adjustments to its opacity is termed:
a. surface rendering
b. maximum intensity projection (MIP)
c. curved multiplanar reformation
d. volume rendering |
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Definition
d. volume rendering
Volume rendering adjusts the opacity of voxels included in the 3D model according to their tissue characteristics. Unlike the thresholding concept used for shaded-surface display (SSD), or surface rendering, volume rendering does not exclude voxels, but instead alters their appearance so that the 3D model contains the entire volume dataset. |
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Term
143. Where is the high-frequency generator often located in a modern CT scanner?
a. inside the gantry
b. just outside the scan room
c. beneath the CT table
d. inside the operator's console |
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Definition
a. inside the gantry
The high-frequency generator used to produce the three-phase power used in modern CT scanners is located inside the gantry. It may be positioned in a corner of the gantry or fixed to the rotating tube assembly. |
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Term
144. The smallest unit of information used in the binary language of computers is the:
a. bit
b. chip
c. base
d. byte |
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Definition
a. bit
The bit is the smallest unit of information within the binary system. Its name is derived from the term "binary digit" and can appear as either a number 1 or 0. A sequence of eight bits constitutes a byte. |
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Term
145. The continuous gantry rotation required by helical CT acquisition is made possible by the application of:
a. electromagnetic bushings
b. titanium bearings
c. slip-rings
d. oil-cooled couplings |
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Definition
c. slip-rings
Eliminating the need for cables, slip-ring technology allows for continuous gantry rotation by utilizing a system of contact brushes that supply electricity to power the system, enabling the passage of transmission data to the computer system. |
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Term
146. The process of applying a mathematical filter to remove blurring from the reconstructed CT image is termed:
a. convolution
b. interpolation
c. iteration
d. z-filtration |
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Definition
a. convolution
The process known as convolution is applied to reduce image unsharpness. An algorithm, or convolution kernel, acts as a mathematical filter, modifying the ray sum data and removing the unwanted blurring effect of the back-projection. |
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Term
147. Which of the following acquisitions may be characterized as contiguous?
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 |
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Definition
c. 3.75-mm sections reconstructed every 3.75 mm
Contiguous images are those acquired with equal section thickness and interval. For example, 3.75-mm sections reconstructed every 3.75 mm completely cover a given volume of tissue with no unmeasured tissue. |
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Term
148. Pixels representing tissues with average attenuation coefficients greater than that of water have which of the following types of values?
a. extremely small
b. positive
c. negative
d. low contrast |
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Definition
b. positive
When calculated by a formula comparing the attenuation coefficient of tissue with that of water, materials whose coefficients are greater than that of water are assigned positive CT numbers. |
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Term
149. For a single-slice CT (SSCT) system, which of the following statements regarding pre-patient collimation is true?
1. An increase in pre-patient collimation increases patient radiation dose.
2. Pre-patient collimation is used to focus radiation through the section of interest.
3. Pre-patient collimation directly controls slice thickness.
a. 2 only
b. 3 only
c. 1 and 2 only
d. 2 and 3 only |
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Definition
b. 3 only
Pre-patient collimation influences the slice thickness by reducing the size of the primary beam. This is accomplished with the use of lead shutters that absorb the outer margins of the primary beam. Increases in pre-patient collimation diminish patient radiation dose by reducing the number of x-ray photons that reach the patient. |
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Term
150. Digital CT images are networked and archived in accordance with a standardized computer protocol identified by which of the following abbreviations?
a. HIPAA
b. HTTP
c. TCP/IP
d. DICOM |
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Definition
d. DICOM
The Digital Imaging and Communications in Medicine (DICOM) standard confirms the process of recording, storing, printing, and transmitting medical image data. |
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Term
151. The contrast resolution of a CT scanner is NOT related to which of the following?
a. focal spot size
b. section width
c. reconstruction algorithm
d. signal-to-noise ratio |
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Definition
a. focal spot size
The contrast resolution of a CT scanner depends on several factors, including section width, algorithm selection, detector sensitivity, and noise. The focal spot size is a geometric factor that influences the spatial resolution of a CT scanner. |
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Term
fig. 5-12
152. The artifact present on the lateral borders of the image in the figure most likely represents which of the following?
a. edge gradient
b. out-of-field artifact
c. tube arcing
d. beam hardening |
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Definition
b. out-of-field artifact
The artifact present in the figure most likely represents an out-of-field artifact. This relatively large patient was incorrectly positioned, and a portion of the anatomy lies outside the scanned field of view. This improperly centered anatomy interferes with the reference detectors, thus causing a streak artifact near the unscanned area. |
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Term
fig. 5-12
153. The image in the figure was produced using the following parameters: large (full) SFOV; maximum DFOV (48 cm); 200 mA, 120 kVp; soft tissue algorithm. Which of the following technical adjustments would serve to reduce the artifact present?
a. switching to a detail or bone algorithm
b. using a smaller SFOV
c. increasing the mA to 240 and the kVp to 140
d. centering the patient within the SFOV |
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Definition
d. centering the patient within the SFOV
The out-of field artifact present in this image could be easily reduced by properly centering the patient within the scan field-of-view. |
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Term
154. The average photon energy of the CT x-ray beam can be increased by:
a. increasing mAs
b. increasing filtration
c. increasing collimation
d. all of the above |
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Definition
b. increasing filtration
Increases in filtration cause a greater amount of low-energy x-ray photons to be absorbed, thereby increasing the average photon energy of the beam. Higher mAs values increase the intensity of the beam but do not affect average photon energy. |
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Term
155. Which of the following is a solid-state device used to record the light flashes given off by a scintillation crystal?
a. photomultiplier tube
b. anode
c. photodiode
d. input phosphor |
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Definition
c. photodiode
Scintillation crystals are used in cooperation with photodiodes in a scintillation-type CT detector. The photodiode is a solid-state device that absorbs the light flashes given off by the crystal. The photodiode then emits an electrical signal in response to this light. |
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Term
156. Automatic tube current modulation (ATCM) software is used in current MDCT systems to control:
a. patient radiation dose
b. cardiac motion
c. timing of contrast agent bolus
d. tissue perfusion assessment |
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Definition
a. patient radiation dose
Automatic tube current modulation (ATCM) programs adjust the mA throughout an acquisition to reduce patient radiation dose to a minimum. ATCM automatically alters the applied mA on the basis of a predetermined noise index the is acceptable for appropriate image quality. |
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Term
157. The type of MSCT detector array that contains multiple rows of detector elements, each of the same length, is called a(n):
a. uniform matrix array
b. adaptive array
c. hybrid array
d. a stationary array |
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Definition
b. adaptive array
The width of a window determines the range of pixel values that will be assigned shades of gray around a given level. In this example, all pixels within the range of -250 to +250 HU will be assigned shades of gray. Pixels below -250 HU will appear black, and pixels above +250 HU will appear white. |
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Term
159. Reformatted CT image planes that lie perpendicular to the original plane of acquisition may be described as:
a. oblique
b. orthogonal
c. obtuse
d. orthographic |
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Definition
b. orthogonal
Orthogonal planes are at right angles to each other. Orthogonal reformations are perpendicular to the original plane of data acquisition. |
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Term
160. Segmenting the data acquisition process into separate components of smaller rotation angels may improve which of the following components of CT image quality?
a. temporal resolution
b. longitudinal spatial resolution
c. contrast resolution
d. in-plane spatial resolution |
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Definition
a. temporal resolution
The controlling factors of the temporal resolution of a CT system are the gantry rotation speed and reconstruction method. Temporal resolution can be improved by segmenting the data acquisition process into separate components smaller rotation angles. Single-segment or half-scan acquisitions reconstruct data obtained from half of the rotation time. For example, this type of segmentation would yield a 250-msec temporal resolution from a 0.5-sec gantry rotation time. |
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Term
161. Which of the following image artifacts is unique to multislice CT (MSCT) systems?
a. step artifact
b. aliasing artifact
c. out-of-field artifact
d. cone beam artifact |
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Definition
d. cone beam artifact
Cone beam artifacts are unique to the cone beam geometry of MDCT systems and typically manifest much like partial volume artifacts. |
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Term
162. Which of the following is considered an analytic form of image reconstruction?
1. iterative technique
2. Fourier reconstruction
3. filtered back-projection
a. 1 only
b. 1 and 2 only
c. 2 and 3 only
d. 1, 2, and 3 |
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Definition
c. 2 and 3 only
The analytic methods of CT image reconstruction include the filtered back-projection and the Fourier transform method. These techniques are called analytic because they utilize precise formulas for image reconstruction. |
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Term
163. A 16-slice MSCT system utilizes an adaptive array of 24 detectors, each ranging in size from 0.625 to 1.25 mm. What is the maximum number of sections the system can acquire with each rotation of the gantry?
a. 8
b. 16
c. 32
d. 64 |
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Definition
b. 16
The number of data channels controls the number of sections the scanner can simultaneously acquire with each gantry rotation. A 16-slice system possesses 16 data channels and is capable of acquiring 16 images per gantry rotation. The configuration of the detector array with regard to the size of individual detector elements controls the possible section widths for each reconstructed CT image. |
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Term
164. The measurement of transmitted radiation made by an individual detector is called a(n):
a. attenuation coefficient
b. Hounsfield value
c. CT number
d. ray sum |
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Definition
d. ray sum
The measurement of transmitted radiation made by an individual detector is called a ray sum. It equals the total attenuation occurring along a straight-line path from tube to detector. |
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Term
165. The information included during the 3D reconstruction of a CT scan is controlled by the:
a. algorithm
b. window setting
c. threshold setting
d. gray-scale map |
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Definition
c. threshold setting
The threshold setting is used to include and exclude information during the 3D reconstruction of a CT scan. For example, a high threshold (+150 HU) may be set to produce a 3D model of a bony structure. This threshold eliminates any density value below +150 HU from the data set. The reconstructed 3D model would include only bone tissue or any other substance with a Hounsfield value above +150. |
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