1. What is the primary principle behind computed tomography
(CT) imaging?
A) Electromagnetic waves
B) X-rays and computer processing
C) Ultrasound and frequency waves
D) Nuclear magnetic resonance
Answer: B) X-rays and computer processing
Rationale: CT imaging works by using X-rays to create cross-
sectional images of the body. A computer processes the X-ray data to
generate detailed images of tissues and organs.
2. What type of radiation does a CT scanner use to create images?
A) Radio waves
B) X-rays
C) Gamma rays
D) Visible light
Answer: B) X-rays
Rationale: CT scanners use X-rays, which are a form of ionizing
radiation, to produce detailed images of the body’s internal structures.
3. Which of the following is the primary advantage of using helical
(spiral) CT scanning over traditional step-and-shoot CT scanning?
A) Faster imaging
B) Higher resolution
C) Lower radiation dose
D) Reduced need for contrast agents
Answer: A) Faster imaging
Rationale: Helical CT provides continuous, spiral data acquisition,
,resulting in faster imaging, which is especially beneficial in trauma
cases or for imaging moving organs.
4. Which of the following factors has the greatest influence on the
quality of a CT image?
A) The amount of contrast used
B) The number of X-ray tubes in the scanner
C) The slice thickness and reconstruction algorithms
D) The patient's body position
Answer: C) The slice thickness and reconstruction algorithms
Rationale: The quality of CT images is highly dependent on the slice
thickness and the algorithms used for reconstruction. Thinner slices
often provide higher image resolution, and advanced algorithms
improve clarity and detail.
5. What is the purpose of using a contrast agent in a CT scan?
A) To reduce the exposure to radiation
B) To make the blood vessels and certain organs more visible
C) To enhance the scanning process and reduce artifacts
D) To correct for motion during the scan
Answer: B) To make the blood vessels and certain organs more visible
Rationale: Contrast agents, typically iodine-based, are used in CT
scans to improve the visibility of blood vessels, soft tissues, and organs,
enhancing the ability to detect abnormalities.
6. In CT imaging, what is the term for the unit of measurement
used to quantify the attenuation of X-rays?
A) Gray
B) Sievert
, C) Hounsfield unit
D) Decibel
Answer: C) Hounsfield unit
Rationale: The Hounsfield unit (HU) is used to measure the
attenuation of X-rays by different tissues. Water is assigned a value of
0 HU, and air has a value of -1000 HU, with various tissues and
substances falling between these values.
7. Which of the following organs or tissues has the highest
attenuation on a CT scan?
A) Bone
B) Fat
C) Liver
D) Air
Answer: A) Bone
Rationale: Bone has a high attenuation on a CT scan because it absorbs
more X-rays compared to other tissues. This results in it appearing
white or bright on the scan images.
8. Which type of CT scanner utilizes multiple rows of detectors
for data acquisition?
A) Single-detector CT
B) Multi-detector CT (MDCT)
C) Positron emission tomography (PET)
D) Helical CT
Answer: B) Multi-detector CT (MDCT)
Rationale: Multi-detector CT (MDCT) uses multiple rows of detectors
to capture data, which increases the speed of scanning and improves
image resolution compared to single-detector systems.
(CT) imaging?
A) Electromagnetic waves
B) X-rays and computer processing
C) Ultrasound and frequency waves
D) Nuclear magnetic resonance
Answer: B) X-rays and computer processing
Rationale: CT imaging works by using X-rays to create cross-
sectional images of the body. A computer processes the X-ray data to
generate detailed images of tissues and organs.
2. What type of radiation does a CT scanner use to create images?
A) Radio waves
B) X-rays
C) Gamma rays
D) Visible light
Answer: B) X-rays
Rationale: CT scanners use X-rays, which are a form of ionizing
radiation, to produce detailed images of the body’s internal structures.
3. Which of the following is the primary advantage of using helical
(spiral) CT scanning over traditional step-and-shoot CT scanning?
A) Faster imaging
B) Higher resolution
C) Lower radiation dose
D) Reduced need for contrast agents
Answer: A) Faster imaging
Rationale: Helical CT provides continuous, spiral data acquisition,
,resulting in faster imaging, which is especially beneficial in trauma
cases or for imaging moving organs.
4. Which of the following factors has the greatest influence on the
quality of a CT image?
A) The amount of contrast used
B) The number of X-ray tubes in the scanner
C) The slice thickness and reconstruction algorithms
D) The patient's body position
Answer: C) The slice thickness and reconstruction algorithms
Rationale: The quality of CT images is highly dependent on the slice
thickness and the algorithms used for reconstruction. Thinner slices
often provide higher image resolution, and advanced algorithms
improve clarity and detail.
5. What is the purpose of using a contrast agent in a CT scan?
A) To reduce the exposure to radiation
B) To make the blood vessels and certain organs more visible
C) To enhance the scanning process and reduce artifacts
D) To correct for motion during the scan
Answer: B) To make the blood vessels and certain organs more visible
Rationale: Contrast agents, typically iodine-based, are used in CT
scans to improve the visibility of blood vessels, soft tissues, and organs,
enhancing the ability to detect abnormalities.
6. In CT imaging, what is the term for the unit of measurement
used to quantify the attenuation of X-rays?
A) Gray
B) Sievert
, C) Hounsfield unit
D) Decibel
Answer: C) Hounsfield unit
Rationale: The Hounsfield unit (HU) is used to measure the
attenuation of X-rays by different tissues. Water is assigned a value of
0 HU, and air has a value of -1000 HU, with various tissues and
substances falling between these values.
7. Which of the following organs or tissues has the highest
attenuation on a CT scan?
A) Bone
B) Fat
C) Liver
D) Air
Answer: A) Bone
Rationale: Bone has a high attenuation on a CT scan because it absorbs
more X-rays compared to other tissues. This results in it appearing
white or bright on the scan images.
8. Which type of CT scanner utilizes multiple rows of detectors
for data acquisition?
A) Single-detector CT
B) Multi-detector CT (MDCT)
C) Positron emission tomography (PET)
D) Helical CT
Answer: B) Multi-detector CT (MDCT)
Rationale: Multi-detector CT (MDCT) uses multiple rows of detectors
to capture data, which increases the speed of scanning and improves
image resolution compared to single-detector systems.
