Computed Tomography Test CT Equipment and Technology 1 — Questions and Answers
Question 1: What is the primary component responsible for X-ray production in a CT scanner?
- Detector array
- X-ray tube (Correct answer)
- Collimator
- Gantry motor
Correct answer: X-ray tube
The X-ray tube generates the X-ray beam used for CT imaging through thermionic emission, converting electrical energy into X-ray photons.
Question 2: What technology allows modern helical CT scanners to rotate continuously without stopping?
- Electromagnetic braking
- Cable drive system
- Slip ring technology (Correct answer)
- Gear reduction transmission
Correct answer: Slip ring technology
Slip ring technology enables continuous electrical contact between the rotating gantry and stationary components, allowing uninterrupted 360° rotation.
Question 3: What is the primary function of the pre-patient collimator in a CT scanner?
- To filter scattered radiation from the patient
- To define the width of the X-ray beam along the z-axis (Correct answer)
- To focus the X-ray beam onto the detector
- To reduce the energy of the X-ray beam
Correct answer: To define the width of the X-ray beam along the z-axis
The pre-patient collimator controls beam width along the z-axis, defining the nominal slice thickness for CT acquisition.
Question 4: Which detector material is most commonly used in modern solid-state CT detectors?
- Sodium iodide (NaI)
- Cesium iodide (CsI)
- Gadolinium oxysulfide (GOS) (Correct answer)
- Bismuth germanate (BGO)
Correct answer: Gadolinium oxysulfide (GOS)
Gadolinium oxysulfide is widely used in modern CT detectors due to its high X-ray absorption efficiency, fast afterglow decay, and mechanical stability.
Question 5: What is the 'gantry' in a CT scanner?
- The patient support table
- The rotating frame housing the X-ray tube and detector array (Correct answer)
- The computer processing unit
- The high-voltage power supply
Correct answer: The rotating frame housing the X-ray tube and detector array
The gantry is the large donut-shaped housing that contains the rotating X-ray tube, detector array, and associated electronics.
Question 6: What is the purpose of the bow-tie (wedge) filter in CT?
- To increase radiation dose to the center of the patient
- To compensate for the varying thickness of the patient's body cross-section (Correct answer)
- To remove high-energy photons from the beam
- To reduce motion artifacts
Correct answer: To compensate for the varying thickness of the patient's body cross-section
The bow-tie filter attenuates the beam more at the periphery (thinner patient edges) than at the center, equalizing detector signal and reducing skin dose.
Question 7: What is the typical gantry rotation time for a modern high-speed CT scanner?
- 2–5 seconds per rotation
- 0.27–0.5 seconds per rotation (Correct answer)
- 1–2 seconds per rotation
- 0.05–0.1 seconds per rotation
Correct answer: 0.27–0.5 seconds per rotation
Modern multi-detector CT scanners complete a full 360° rotation in as little as 0.27 seconds, enabling fast cardiac and dynamic imaging.
Computed Tomography Test CT Equipment and Technology 1
What is the primary component responsible for X-ray production in a CT scanner?