Computed-Assisted Tomography (CAT Scanning) Certificate Exam
Question 1: Which of the following best describes the primary principle behind Computed
Tomography (CT) imaging?
A: It uses magnetic fields to generate images.
B: It rotates an X‐ray source and detectors around the patient to create cross-sectional images.
C: It uses ultrasound waves to produce images.
D: It captures light emitted by radioactive tracers.
Answer: B
Explanation: CT imaging involves an X‐ray source and detectors rotating around the patient to
create cross-sectional images that can be reconstructed into a 3D image.
Question 2: What historical development was most critical in the evolution of CT
technology?
A: The discovery of X‐rays by Wilhelm Röntgen.
B: The invention of the computer algorithm for image reconstruction.
C: The development of ultrasound imaging.
D: The creation of MRI scanners.
Answer: B
Explanation: While the discovery of X‐rays was fundamental, the creation of sophisticated
computer algorithms for reconstructing images from X‐ray data was critical for CT development.
Question 3: In CT scanning, what does the acronym “ALARA” stand for?
A: As Low As Radiologically Acceptable.
B: As Light As Reasonably Achievable.
C: As Low As Reasonably Achievable.
D: As Low As Radiation Allows.
Answer: C
Explanation: ALARA is a radiation safety principle that stands for “As Low As Reasonably
Achievable,” ensuring patient exposure is minimized.
Question 4: Which type of CT scanner is designed to acquire multiple slices
simultaneously?
A: Single-slice CT scanner.
B: Multi-slice (or multi-detector) CT scanner.
C: Cone-beam CT scanner.
D: Spiral CT scanner.
Answer: B
Explanation: Multi-slice CT scanners use several detectors to capture multiple slices
simultaneously, improving speed and resolution.
Question 5: What is the significance of gantry in a CT scanner?
A: It powers the computer system.
B: It houses the X‐ray tube and detectors during the scan.
,C: It is used for patient positioning only.
D: It controls the contrast injection.
Answer: B
Explanation: The gantry is the part of the CT scanner that rotates around the patient and contains
both the X‐ray tube and detectors, which are essential for image acquisition.
Question 6: How does helical (spiral) CT differ from traditional axial CT scanning?
A: It uses lower doses of contrast agent.
B: It collects data continuously as the table moves, forming a spiral path.
C: It only scans the head region.
D: It requires no reconstruction algorithms.
Answer: B
Explanation: Helical CT continuously collects data while the patient moves through the scanner,
allowing for rapid imaging and 3D reconstructions.
Question 7: Which parameter in CT scanning affects both image quality and radiation
dose?
A: kVp (kilovolt peak).
B: Field of view.
C: Patient age.
D: Scanner brand.
Answer: A
Explanation: kVp influences the energy of the X‐ray beam and therefore has a direct impact on
both image quality and the patient’s radiation dose.
Question 8: In CT imaging, why is slice thickness an important parameter?
A: It determines the speed of the scan.
B: It affects image resolution and noise level.
C: It changes the type of contrast agent used.
D: It only matters for head CT scans.
Answer: B
Explanation: Slice thickness impacts the resolution and noise; thinner slices provide higher
resolution but may increase noise, while thicker slices reduce noise at the cost of detail.
Question 9: Which contrast agent is commonly used in CT scans to enhance vascular
structures?
A: Barium sulfate.
B: Iodine-based contrast.
C: Gadolinium.
D: Technetium-99m.
Answer: B
Explanation: Iodine-based contrast agents are widely used in CT to improve the visibility of
blood vessels and soft tissues.
Question 10: What is the primary role of reconstruction algorithms in CT imaging?
A: To compress the image files.
,B: To convert raw data into clinically useful images.
C: To enhance the contrast agent properties.
D: To determine patient positioning.
Answer: B
Explanation: Reconstruction algorithms process the raw data from detectors to generate the final
cross-sectional images seen by clinicians.
Question 11: Which artifact is most commonly associated with patient movement during a
CT scan?
A: Beam hardening.
B: Motion artifact.
C: Metal artifact.
D: Partial volume artifact.
Answer: B
Explanation: Motion artifacts are frequently seen when a patient moves during the scan, leading
to blurred or distorted images.
Question 12: What is the importance of calibrating a CT scanner regularly?
A: To reduce scanning time.
B: To ensure accuracy of the images and maintain quality control.
C: To allow the use of different contrast agents.
D: To upgrade the software automatically.
Answer: B
Explanation: Regular calibration of CT scanners is vital to maintain image quality and ensure
accurate diagnostic results.
Question 13: Which detector technology is used in most modern CT scanners?
A: Scintillation crystals coupled with photodiodes.
B: Mechanical film detectors.
C: Liquid crystal arrays.
D: Optical sensors.
Answer: A
Explanation: Modern CT scanners commonly use scintillation crystals with photodiodes to
convert X‐ray photons into electrical signals for image formation.
Question 14: What does the term “pitch” refer to in CT scanning?
A: The frequency of the X‐ray pulses.
B: The ratio of table movement per rotation to slice thickness.
C: The angle of the gantry rotation.
D: The energy level of the X‐ray beam.
Answer: B
Explanation: Pitch is defined as the ratio of the table feed per rotation to the thickness of the CT
slice, affecting image quality and scan time.
Question 15: How do CT technologists minimize radiation exposure to patients?
A: By increasing the contrast agent dose.
, B: By using optimized protocols and shielding techniques.
C: By performing more scans per session.
D: By reducing the image reconstruction time.
Answer: B
Explanation: Radiation exposure is minimized through careful selection of scanning parameters,
optimized protocols, and appropriate shielding techniques.
Question 16: Which of the following best explains the role of a scintillation crystal in a CT
detector?
A: It filters the X‐rays before they reach the patient.
B: It converts X‐ray photons into visible light.
C: It amplifies the X‐ray beam intensity.
D: It controls the gantry rotation speed.
Answer: B
Explanation: Scintillation crystals absorb X‐ray photons and convert them into visible light,
which is then detected and processed.
Question 17: What is the primary benefit of using a multi-detector CT scanner over a
single-slice CT scanner?
A: Lower initial equipment cost.
B: Faster acquisition of images and improved resolution.
C: Reduced need for contrast agents.
D: Simpler maintenance requirements.
Answer: B
Explanation: Multi-detector CT scanners provide faster imaging and higher resolution by
capturing multiple slices in one rotation.
Question 18: Which of the following is a key consideration in patient preparation for a CT
scan?
A: Ensuring the patient has fasted if required by the protocol.
B: Asking the patient to exercise before the scan.
C: Providing the patient with a sedative regardless of condition.
D: Performing the scan without any prior instructions.
Answer: A
Explanation: Depending on the type of CT scan, fasting may be necessary to improve image
quality and reduce complications from contrast agents.
Question 19: In CT imaging, what is the purpose of multiplanar reformatting (MPR)?
A: To reduce the radiation dose.
B: To generate images in different anatomical planes from the same dataset.
C: To increase the speed of the scan.
D: To automatically adjust contrast settings.
Answer: B
Explanation: MPR allows radiologists to view images in different anatomical planes (sagittal,
coronal, etc.) from the original axial data.
Question 1: Which of the following best describes the primary principle behind Computed
Tomography (CT) imaging?
A: It uses magnetic fields to generate images.
B: It rotates an X‐ray source and detectors around the patient to create cross-sectional images.
C: It uses ultrasound waves to produce images.
D: It captures light emitted by radioactive tracers.
Answer: B
Explanation: CT imaging involves an X‐ray source and detectors rotating around the patient to
create cross-sectional images that can be reconstructed into a 3D image.
Question 2: What historical development was most critical in the evolution of CT
technology?
A: The discovery of X‐rays by Wilhelm Röntgen.
B: The invention of the computer algorithm for image reconstruction.
C: The development of ultrasound imaging.
D: The creation of MRI scanners.
Answer: B
Explanation: While the discovery of X‐rays was fundamental, the creation of sophisticated
computer algorithms for reconstructing images from X‐ray data was critical for CT development.
Question 3: In CT scanning, what does the acronym “ALARA” stand for?
A: As Low As Radiologically Acceptable.
B: As Light As Reasonably Achievable.
C: As Low As Reasonably Achievable.
D: As Low As Radiation Allows.
Answer: C
Explanation: ALARA is a radiation safety principle that stands for “As Low As Reasonably
Achievable,” ensuring patient exposure is minimized.
Question 4: Which type of CT scanner is designed to acquire multiple slices
simultaneously?
A: Single-slice CT scanner.
B: Multi-slice (or multi-detector) CT scanner.
C: Cone-beam CT scanner.
D: Spiral CT scanner.
Answer: B
Explanation: Multi-slice CT scanners use several detectors to capture multiple slices
simultaneously, improving speed and resolution.
Question 5: What is the significance of gantry in a CT scanner?
A: It powers the computer system.
B: It houses the X‐ray tube and detectors during the scan.
,C: It is used for patient positioning only.
D: It controls the contrast injection.
Answer: B
Explanation: The gantry is the part of the CT scanner that rotates around the patient and contains
both the X‐ray tube and detectors, which are essential for image acquisition.
Question 6: How does helical (spiral) CT differ from traditional axial CT scanning?
A: It uses lower doses of contrast agent.
B: It collects data continuously as the table moves, forming a spiral path.
C: It only scans the head region.
D: It requires no reconstruction algorithms.
Answer: B
Explanation: Helical CT continuously collects data while the patient moves through the scanner,
allowing for rapid imaging and 3D reconstructions.
Question 7: Which parameter in CT scanning affects both image quality and radiation
dose?
A: kVp (kilovolt peak).
B: Field of view.
C: Patient age.
D: Scanner brand.
Answer: A
Explanation: kVp influences the energy of the X‐ray beam and therefore has a direct impact on
both image quality and the patient’s radiation dose.
Question 8: In CT imaging, why is slice thickness an important parameter?
A: It determines the speed of the scan.
B: It affects image resolution and noise level.
C: It changes the type of contrast agent used.
D: It only matters for head CT scans.
Answer: B
Explanation: Slice thickness impacts the resolution and noise; thinner slices provide higher
resolution but may increase noise, while thicker slices reduce noise at the cost of detail.
Question 9: Which contrast agent is commonly used in CT scans to enhance vascular
structures?
A: Barium sulfate.
B: Iodine-based contrast.
C: Gadolinium.
D: Technetium-99m.
Answer: B
Explanation: Iodine-based contrast agents are widely used in CT to improve the visibility of
blood vessels and soft tissues.
Question 10: What is the primary role of reconstruction algorithms in CT imaging?
A: To compress the image files.
,B: To convert raw data into clinically useful images.
C: To enhance the contrast agent properties.
D: To determine patient positioning.
Answer: B
Explanation: Reconstruction algorithms process the raw data from detectors to generate the final
cross-sectional images seen by clinicians.
Question 11: Which artifact is most commonly associated with patient movement during a
CT scan?
A: Beam hardening.
B: Motion artifact.
C: Metal artifact.
D: Partial volume artifact.
Answer: B
Explanation: Motion artifacts are frequently seen when a patient moves during the scan, leading
to blurred or distorted images.
Question 12: What is the importance of calibrating a CT scanner regularly?
A: To reduce scanning time.
B: To ensure accuracy of the images and maintain quality control.
C: To allow the use of different contrast agents.
D: To upgrade the software automatically.
Answer: B
Explanation: Regular calibration of CT scanners is vital to maintain image quality and ensure
accurate diagnostic results.
Question 13: Which detector technology is used in most modern CT scanners?
A: Scintillation crystals coupled with photodiodes.
B: Mechanical film detectors.
C: Liquid crystal arrays.
D: Optical sensors.
Answer: A
Explanation: Modern CT scanners commonly use scintillation crystals with photodiodes to
convert X‐ray photons into electrical signals for image formation.
Question 14: What does the term “pitch” refer to in CT scanning?
A: The frequency of the X‐ray pulses.
B: The ratio of table movement per rotation to slice thickness.
C: The angle of the gantry rotation.
D: The energy level of the X‐ray beam.
Answer: B
Explanation: Pitch is defined as the ratio of the table feed per rotation to the thickness of the CT
slice, affecting image quality and scan time.
Question 15: How do CT technologists minimize radiation exposure to patients?
A: By increasing the contrast agent dose.
, B: By using optimized protocols and shielding techniques.
C: By performing more scans per session.
D: By reducing the image reconstruction time.
Answer: B
Explanation: Radiation exposure is minimized through careful selection of scanning parameters,
optimized protocols, and appropriate shielding techniques.
Question 16: Which of the following best explains the role of a scintillation crystal in a CT
detector?
A: It filters the X‐rays before they reach the patient.
B: It converts X‐ray photons into visible light.
C: It amplifies the X‐ray beam intensity.
D: It controls the gantry rotation speed.
Answer: B
Explanation: Scintillation crystals absorb X‐ray photons and convert them into visible light,
which is then detected and processed.
Question 17: What is the primary benefit of using a multi-detector CT scanner over a
single-slice CT scanner?
A: Lower initial equipment cost.
B: Faster acquisition of images and improved resolution.
C: Reduced need for contrast agents.
D: Simpler maintenance requirements.
Answer: B
Explanation: Multi-detector CT scanners provide faster imaging and higher resolution by
capturing multiple slices in one rotation.
Question 18: Which of the following is a key consideration in patient preparation for a CT
scan?
A: Ensuring the patient has fasted if required by the protocol.
B: Asking the patient to exercise before the scan.
C: Providing the patient with a sedative regardless of condition.
D: Performing the scan without any prior instructions.
Answer: A
Explanation: Depending on the type of CT scan, fasting may be necessary to improve image
quality and reduce complications from contrast agents.
Question 19: In CT imaging, what is the purpose of multiplanar reformatting (MPR)?
A: To reduce the radiation dose.
B: To generate images in different anatomical planes from the same dataset.
C: To increase the speed of the scan.
D: To automatically adjust contrast settings.
Answer: B
Explanation: MPR allows radiologists to view images in different anatomical planes (sagittal,
coronal, etc.) from the original axial data.
