Computed Tomography Flashcards
7 cards from real Computed Tomography Test practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Computed Tomography flashcards as text
Which CT acquisition mode collects data continuously as the table moves through the gantry?
Answer: Helical (spiral) mode
Helical CT rotates the X-ray tube continuously while the table advances, creating a spiral data set that allows retrospective reconstruction at any slice position.
What is the primary advantage of dual-energy CT (DECT) over single-energy CT?
Answer: Material decomposition enabling differentiation of tissues with similar HU values
DECT acquires data at two kVp settings, enabling material decomposition algorithms that distinguish substances like iodine, uric acid, and calcium that may overlap in attenuation at single energy.
Which structure is best identified on a CT image using a bone window with a window level of approximately 300–700 HU?
Answer: Cortical bone and fracture lines
Bone windows use high window levels centered on dense cortical bone (≈400–1000 HU), which optimizes visualization of fractures, bony trabecular detail, and periosteal changes.
A pregnant patient requires abdominal CT for suspected appendicitis. Which statement about fetal radiation risk is most accurate?
Answer: Fetal risk is negligible at typical diagnostic doses below 50 mGy, but benefits must outweigh risks
At diagnostic CT doses typically below 25 mGy, deterministic fetal effects are extremely unlikely; however, the ALARA principle still applies and clinical benefit must justify the exposure.
What does 'multiplanar reformation' (MPR) allow in CT post-processing?
Answer: Display of axial raw data in coronal, sagittal, or oblique planes
MPR resamples the volumetric CT dataset to display images in any desired plane, allowing evaluation of anatomy that is difficult to assess on axial images alone.
Which factor most significantly increases the risk of contrast extravasation during CT power injection?
Answer: Using a small-gauge hand or wrist vein at high flow rates
Small, fragile distal veins of the hand or wrist are more prone to rupture at high injection rates, and extravasation of large volumes of contrast can cause tissue necrosis.
What is the main clinical application of CT fluoroscopy?
Answer: Real-time guidance for percutaneous biopsies and drainage procedures
CT fluoroscopy provides continuous or near-continuous CT imaging to guide needle placement during interventional procedures such as lung biopsies or abscess drainage.