Computed Tomography Test Computed Tomography Knowledge Questions and An 2 — Questions and Answers
Question 1: Which windowing preset is most appropriate for evaluating pulmonary nodules on CT?
- Bone window (W:2000, L:400)
- Lung window (W:1500, L:-600) (Correct answer)
- Soft tissue window (W:400, L:40)
- Brain window (W:80, L:40)
Correct answer: Lung window (W:1500, L:-600)
Lung window settings (wide width, negative level) optimize contrast for air-filled lung parenchyma and nodule detection.
Question 2: What is the primary advantage of dual-energy CT (DECT) over single-energy CT?
- Faster scan acquisition time
- Ability to characterize tissue composition based on material decomposition (Correct answer)
- Lower radiation dose per examination
- Superior soft tissue spatial resolution
Correct answer: Ability to characterize tissue composition based on material decomposition
DECT acquires data at two energy levels, enabling material decomposition to distinguish substances like iodine, uric acid, and calcium.
Question 3: A CT scan shows an adrenal lesion with an unenhanced attenuation of 8 HU. What is the most likely diagnosis?
- Adrenal adenoma (Correct answer)
- Adrenal carcinoma
- Pheochromocytoma
- Adrenal metastasis
Correct answer: Adrenal adenoma
Adrenal lesions with unenhanced HU ≤10 are consistent with lipid-rich adenomas due to intracellular fat content.
Question 4: What does the term 'partial volume averaging' refer to in CT imaging?
- Averaging of multiple scan acquisitions to reduce noise
- Blending of attenuation values from different tissues within a single voxel (Correct answer)
- Reduction in FOV to improve spatial resolution
- Use of partial rotation for faster data acquisition
Correct answer: Blending of attenuation values from different tissues within a single voxel
Partial volume averaging occurs when a voxel contains more than one tissue type, resulting in an averaged attenuation value that misrepresents both tissues.
Question 5: Which reconstruction algorithm produces sharper edges but increased image noise in CT?
- Smooth/soft-tissue kernel
- Standard kernel
- Bone/sharp kernel (Correct answer)
- Ultra-low-dose kernel
Correct answer: Bone/sharp kernel
Sharp (bone) kernels apply high-frequency enhancement to improve edge definition, which amplifies noise compared to smooth kernels.
Question 6: In CT angiography, what is the purpose of a test bolus or bolus tracking technique?
- To determine patient weight-based contrast volume
- To optimize scan timing relative to contrast arrival in the target vessel (Correct answer)
- To assess patient allergy risk before full injection
- To calibrate the CT detector gain before contrast injection
Correct answer: To optimize scan timing relative to contrast arrival in the target vessel
Bolus tracking and test bolus methods synchronize scan initiation with peak contrast enhancement in the target vessel to ensure optimal opacification.
Question 7: What is the typical scan direction for most helical CT acquisitions?
- Inferior to superior
- Superior to inferior (Correct answer)
- Alternating with each rotation
- Determined by patient positioning only
Correct answer: Superior to inferior
Most helical CT acquisitions proceed from superior to inferior (craniocaudal), though specific protocols may vary for certain applications like runoff studies.
Computed Tomography Test Computed Tomography Knowledge Questions and An 2
Which windowing preset is most appropriate for evaluating pulmonary nodules on CT?