EXAM QUESTIONS AND CORRECT ANSWERS
(VERIFIED ANSWERS) Q&A 2026 |INSTANT
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1. Which imaging plane divides the body into anterior and
posterior sections?
A. Sagittal
B. Coronal
C. Axial
D. Oblique
Answer: B. Coronal
Rationale: The coronal plane runs vertically and divides the
body into front (anterior) and back (posterior) portions. Sagittal
divides left/right, axial divides top/bottom.
2. What is the primary purpose of a CT contrast agent?
A. To reduce radiation dose
B. To enhance tissue differentiation
C. To speed up scan time
D. To clean the imaging detector
Answer: B. To enhance tissue differentiation
Rationale: CT contrast agents increase the visibility of
,structures by changing the attenuation of X-rays, highlighting
organs, vessels, and pathology.
3. What is the typical Hounsfield Unit (HU) value for water?
A. 0
B. +100
C. -100
D. +1000
Answer: A. 0
Rationale: Hounsfield Units measure CT density. Water is
defined as 0 HU, air is approximately -1000 HU, and bone is
+1000 HU.
4. Which CT acquisition parameter primarily affects spatial
resolution?
A. kVp
B. mAs
C. Slice thickness
D. Table speed
Answer: C. Slice thickness
Rationale: Thinner slices improve spatial resolution, allowing
better visualization of small structures, while thicker slices
reduce resolution.
,5. What is the most common artifact caused by patient
motion?
A. Ring artifact
B. Beam hardening
C. Motion artifact (streaking)
D. Partial volume artifact
Answer: C. Motion artifact (streaking)
Rationale: Patient movement during scanning can create
streaking and blurring artifacts, affecting image quality.
6. What type of CT detector is most commonly used today?
A. Gas-filled ionization chamber
B. Scintillation detector
C. Photographic plate
D. Film-screen
Answer: B. Scintillation detector
Rationale: Modern CT scanners primarily use scintillation
detectors, which convert X-ray photons into light and then into
an electrical signal for image formation.
7. Which CT window setting is ideal for viewing lung
parenchyma?
A. Soft tissue window
B. Bone window
, C. Lung window
D. Brain window
Answer: C. Lung window
Rationale: Lung windows optimize visualization of air-filled
structures, allowing detection of nodules, consolidations, and
other lung pathology.
8. What is the effect of increasing kVp on CT imaging?
A. Increases image contrast
B. Reduces patient dose
C. Increases X-ray penetration
D. Decreases scatter radiation
Answer: C. Increases X-ray penetration
Rationale: Higher kVp increases photon energy, improving
penetration of dense tissues but decreasing image contrast.
9. What is the recommended patient positioning for a CT scan
of the head?
A. Prone, arms overhead
B. Supine, head first
C. Supine, feet first
D. Lateral decubitus
Answer: B. Supine, head first
Rationale: Standard CT head scans are performed supine, head