ARRT Scan Protocols 3 — Questions and Answers
Question 1: For a CT coronary angiography (CCTA) protocol, which heart rate range is generally ideal to minimize motion artifact?
- <65 bpm (Correct answer)
- 65–80 bpm
- 80–100 bpm
- >100 bpm
Correct answer: <65 bpm
Heart rates below 65 bpm allow longer diastolic rest periods, reducing cardiac motion artifact during CCTA acquisition.
Question 2: When scanning for acute aortic dissection, the scan range should include:
- Chest only
- Abdomen and pelvis only
- Chest, abdomen, and pelvis (Correct answer)
- Head and neck only
Correct answer: Chest, abdomen, and pelvis
Aortic dissection can extend from the aortic root to the iliac arteries, so the entire aorta from chest through pelvis must be imaged.
Question 3: A CT myelography protocol requires which patient preparation step unique to this exam?
- Oral bowel prep the night before
- Intrathecal injection of iodinated contrast (Correct answer)
- IV injection of gadolinium contrast
- Fasting for 6 hours prior
Correct answer: Intrathecal injection of iodinated contrast
CT myelography requires intrathecal (subarachnoid) injection of water-soluble iodinated contrast to opacify the spinal canal.
Question 4: Which pitch factor would result in the longest scan time for a given scan range?
- 0.5 (Correct answer)
- 1.0
- 1.5
- 2.0
Correct answer: 0.5
A lower pitch means the table moves more slowly relative to rotation speed, resulting in more overlap and a longer scan time.
Question 5: In a CT urography (CTU) protocol, the excretory phase is typically acquired how long after IV contrast injection?
- 10–20 seconds
- 30–50 seconds
- 5–10 minutes (Correct answer)
- 20–30 minutes
Correct answer: 5–10 minutes
The excretory (nephrographic) phase of CTU is acquired 5–10 minutes post-injection to allow contrast to opacify and distend the collecting system and ureters.
Question 6: Which window setting is most appropriate for evaluating acute intracranial hemorrhage on a non-contrast head CT?
- Lung window (WW 1500, WL -500)
- Bone window (WW 2000, WL 300)
- Brain window (WW 80, WL 35) (Correct answer)
- Soft tissue window (WW 400, WL 50)
Correct answer: Brain window (WW 80, WL 35)
The brain window (narrow width ~80 HU, level ~35 HU) provides optimal contrast between hyperdense blood and surrounding brain tissue.
Question 7: For a CT scan of the spine performed to evaluate for disk herniation, which reconstruction kernel is preferred?
- Lung (high-frequency) kernel
- Bone (high-frequency) kernel
- Standard soft tissue kernel (Correct answer)
- Ultra-high-resolution kernel
Correct answer: Standard soft tissue kernel
A standard or intermediate soft tissue kernel is preferred for disk and neural structure evaluation, reducing noise while preserving relevant detail.
ARRT Scan Protocols 3
For a CT coronary angiography (CCTA) protocol, which heart rate range is generally ideal to minimize motion artifact?