Nuclear Medicine Practice Exam – NMTCB/ARRT Preparation
Nuclear Medicine Practice Exam – 2026/2027 Insider Test Bank
NMTCB/ARRT Certification Preparation | Complete Q&A | 150 Questions
Select the BEST answer for each question. All correct answers are indicated in bold cyan.
Section I: Radiation Physics & Instrumentation (Questions 1–18)
1. What is the primary function of the collimator in a gamma camera?
A. Detect gamma photons and convert them to B. Limit the direction of photons reaching the
light detector
C. Amplify electrical signals from the D. Convert light photons to electrical signals
photomultiplier tube
Answer: B. Limit the direction of photons reaching the detector — The collimator allows only photons traveling in
specific directions to reach the crystal, providing spatial information for image formation.
2. Which type of collimator is most appropriate for low-energy radionuclides such as Tc-99m (140 keV)?
A. High-energy collimator B. Medium-energy collimator
C. Low-energy all-purpose (LEAP) collimator D. Pinhole collimator
Answer: C. Low-energy all-purpose (LEAP) collimator — The LEAP collimator is designed for low-energy photons (~140
keV) and offers a good balance of resolution and sensitivity.
3. The NaI(Tl) crystal in a gamma camera converts incident gamma photons into:
A. Electrical signals B. Ultraviolet light
C. Visible light photons D. X-ray fluorescence
Answer: C. Visible light photons — Sodium iodide doped with thallium (NaI(Tl)) is a scintillation crystal that absorbs
gamma photons and emits visible light (scintillations).
4. What is the purpose of photomultiplier tubes (PMTs) in a gamma camera?
A. To collimate incoming photons B. To convert scintillation light into an amplified
electrical signal
C. To generate gamma photons for imaging D. To filter scattered radiation
Answer: B. To convert scintillation light into an amplified electrical signal — PMTs detect the scintillation light from the
crystal, multiply the signal through a cascade of dynodes, and produce a measurable electrical pulse.
5. In SPECT imaging, the gamma camera rotates around the patient to acquire data from multiple angles.
This data is used to reconstruct:
A. 2D planar images only B. 3D tomographic slices
C. 4D dynamic images D. Whole-body scans
Answer: B. 3D tomographic slices — SPECT acquires projections at multiple angles around the patient and uses filtered
back-projection or iterative reconstruction to generate axial, coronal, and sagittal slices.
6. Positron emission tomography (PET) detects which of the following?
A. Single gamma photons of 140 keV B. Pairs of 511 keV annihilation photons emitted at
180 degrees
1
, Nuclear Medicine Practice Exam – NMTCB/ARRT Preparation
C. Beta-minus particles D. Alpha particles
Answer: B. Pairs of 511 keV annihilation photons emitted at 180 degrees — PET radionuclides emit positrons, which
annihilate with electrons to produce two 511 keV photons emitted in opposite (approximately 180°) directions.
7. What is coincidence detection in PET imaging?
A. Detection of a single photon event B. Simultaneous detection of two 511 keV photons
by opposing detectors
C. Detection of scattered photons only D. Detection of random background noise
Answer: B. Simultaneous detection of two 511 keV photons by opposing detectors — Coincidence detection identifies
valid annihilation events by registering near-simultaneous photon detection in opposing detectors within a narrow time
window.
8. F-18 FDG (fluorodeoxyglucose) is primarily used to image:
A. Bone metabolism B. Blood perfusion
C. Glucose metabolism D. Thyroid function
Answer: C. Glucose metabolism — FDG is a glucose analog taken up by metabolically active cells (e.g., cancer cells), making
it the primary PET tracer for oncology, neurology, and cardiology.
9. Spatial resolution of a gamma camera is defined as:
A. The minimum detectable photon energy B. The ability to distinguish between two closely
spaced radioactive sources
C. The maximum count rate the system can handle D. The thickness of the NaI(Tl) crystal
Answer: B. The ability to distinguish between two closely spaced radioactive sources — Spatial resolution refers to the
camera’s ability to resolve two point sources as separate entities and is typically expressed in millimeters at a specified
distance.
10. Energy resolution of a gamma camera is best described as:
A. The range of photon energies the crystal can B. The ability to distinguish the photopeak from
detect scattered radiation
C. The total number of photons absorbed by the D. The collimator’s septal penetration rate
crystal
Answer: B. The ability to distinguish the photopeak from scattered radiation — Energy resolution reflects the detector’s
ability to differentiate the photopeak (full-energy deposition) from Compton-scattered and other lower-energy photons.
11. Dead time in a nuclear medicine detection system refers to:
A. The time a radioactive source takes to decay B. The period after a detected event during which
the system cannot process additional events
C. The time required for image reconstruction D. The interval between patient injections
Answer: B. The period after a detected event during which the system cannot process additional events — Dead time
is the interval during which the detector is busy processing one event and cannot record incoming photons, leading to count
loss at high count rates.
12. Which type of dead time results in a count rate that eventually decreases with increasing activity?
A. Paralyzable dead time B. Non-paralyzable dead time
C. Fixed dead time D. Resolving time
Answer: A. Paralyzable dead time — In paralyzable (extendable) dead time, each event extends the dead period, causing the
measured count rate to peak and then decline as activity increases.
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, Nuclear Medicine Practice Exam – NMTCB/ARRT Preparation
13. Linearity testing of a gamma camera evaluates:
A. Uniformity of detector response B. The relationship between count rate and source
activity
C. Image sharpness at the edges of the field of view D. Collimator hole alignment
Answer: B. The relationship between count rate and source activity — Linearity ensures that the count rate measured by
the system is directly proportional to the activity of the source across the full range of clinical activities.
14. A pinhole collimator produces which type of image?
A. An inverted (upside-down) magnified image B. A minified image
C. A true-sized image D. A double-inverted image
Answer: A. An inverted (upside-down) magnified image — The pinhole collimator produces an inverted and magnified
image, useful for small organs such as the thyroid or pediatric imaging.
15. What is the primary advantage of PET/CT over standalone PET?
A. Lower radiation dose to the patient B. Elimination of attenuation correction
C. Anatomical localization of metabolic findings via D. Reduced scan acquisition time
CT
Answer: C. Anatomical localization of metabolic findings via CT — PET/CT combines metabolic PET data with
anatomical CT images, allowing precise localization of abnormal FDG uptake to specific anatomical structures.
16. The half-value layer (HVL) for Tc-99m (140 keV) in lead is approximately:
A. 0.03 mm B. 0.25 mm
C. 2.5 mm D. 6.5 mm
Answer: B. 0.25 mm — The HVL of 140 keV photons in lead is approximately 0.25 mm, meaning 0.25 mm of lead reduces the
photon intensity by half.
17. Which reconstruction algorithm is most commonly used in modern SPECT imaging?
A. Back-projection only B. Filtered back-projection (FBP)
C. Ordered-subsets expectation maximization D. Fourier transform reconstruction
(OSEM)
Answer: C. Ordered-subsets expectation maximization (OSEM) — OSEM is the preferred iterative reconstruction
algorithm because it produces better image quality with less noise than FBP, especially at lower count densities.
18. Septal penetration in a collimator is most likely to occur with:
A. Low-energy photons and a high-energy B. High-energy photons and a low-energy
collimator collimator
C. Low-energy photons and a low-energy D. High-energy photons and a high-energy
collimator collimator
Answer: B. High-energy photons and a low-energy collimator — When high-energy photons strike a collimator designed
for low-energy radionuclides, photons can penetrate the septa, degrading image contrast and resolution.
Section II: Radiopharmacy & Radiochemistry (Questions 19–35)
19. The Tc-99m generator uses which parent radionuclide adsorbed onto an alumina column?
A. Tc-99 B. Mo-99
C. I-131 D. F-18
3
Nuclear Medicine Practice Exam – 2026/2027 Insider Test Bank
NMTCB/ARRT Certification Preparation | Complete Q&A | 150 Questions
Select the BEST answer for each question. All correct answers are indicated in bold cyan.
Section I: Radiation Physics & Instrumentation (Questions 1–18)
1. What is the primary function of the collimator in a gamma camera?
A. Detect gamma photons and convert them to B. Limit the direction of photons reaching the
light detector
C. Amplify electrical signals from the D. Convert light photons to electrical signals
photomultiplier tube
Answer: B. Limit the direction of photons reaching the detector — The collimator allows only photons traveling in
specific directions to reach the crystal, providing spatial information for image formation.
2. Which type of collimator is most appropriate for low-energy radionuclides such as Tc-99m (140 keV)?
A. High-energy collimator B. Medium-energy collimator
C. Low-energy all-purpose (LEAP) collimator D. Pinhole collimator
Answer: C. Low-energy all-purpose (LEAP) collimator — The LEAP collimator is designed for low-energy photons (~140
keV) and offers a good balance of resolution and sensitivity.
3. The NaI(Tl) crystal in a gamma camera converts incident gamma photons into:
A. Electrical signals B. Ultraviolet light
C. Visible light photons D. X-ray fluorescence
Answer: C. Visible light photons — Sodium iodide doped with thallium (NaI(Tl)) is a scintillation crystal that absorbs
gamma photons and emits visible light (scintillations).
4. What is the purpose of photomultiplier tubes (PMTs) in a gamma camera?
A. To collimate incoming photons B. To convert scintillation light into an amplified
electrical signal
C. To generate gamma photons for imaging D. To filter scattered radiation
Answer: B. To convert scintillation light into an amplified electrical signal — PMTs detect the scintillation light from the
crystal, multiply the signal through a cascade of dynodes, and produce a measurable electrical pulse.
5. In SPECT imaging, the gamma camera rotates around the patient to acquire data from multiple angles.
This data is used to reconstruct:
A. 2D planar images only B. 3D tomographic slices
C. 4D dynamic images D. Whole-body scans
Answer: B. 3D tomographic slices — SPECT acquires projections at multiple angles around the patient and uses filtered
back-projection or iterative reconstruction to generate axial, coronal, and sagittal slices.
6. Positron emission tomography (PET) detects which of the following?
A. Single gamma photons of 140 keV B. Pairs of 511 keV annihilation photons emitted at
180 degrees
1
, Nuclear Medicine Practice Exam – NMTCB/ARRT Preparation
C. Beta-minus particles D. Alpha particles
Answer: B. Pairs of 511 keV annihilation photons emitted at 180 degrees — PET radionuclides emit positrons, which
annihilate with electrons to produce two 511 keV photons emitted in opposite (approximately 180°) directions.
7. What is coincidence detection in PET imaging?
A. Detection of a single photon event B. Simultaneous detection of two 511 keV photons
by opposing detectors
C. Detection of scattered photons only D. Detection of random background noise
Answer: B. Simultaneous detection of two 511 keV photons by opposing detectors — Coincidence detection identifies
valid annihilation events by registering near-simultaneous photon detection in opposing detectors within a narrow time
window.
8. F-18 FDG (fluorodeoxyglucose) is primarily used to image:
A. Bone metabolism B. Blood perfusion
C. Glucose metabolism D. Thyroid function
Answer: C. Glucose metabolism — FDG is a glucose analog taken up by metabolically active cells (e.g., cancer cells), making
it the primary PET tracer for oncology, neurology, and cardiology.
9. Spatial resolution of a gamma camera is defined as:
A. The minimum detectable photon energy B. The ability to distinguish between two closely
spaced radioactive sources
C. The maximum count rate the system can handle D. The thickness of the NaI(Tl) crystal
Answer: B. The ability to distinguish between two closely spaced radioactive sources — Spatial resolution refers to the
camera’s ability to resolve two point sources as separate entities and is typically expressed in millimeters at a specified
distance.
10. Energy resolution of a gamma camera is best described as:
A. The range of photon energies the crystal can B. The ability to distinguish the photopeak from
detect scattered radiation
C. The total number of photons absorbed by the D. The collimator’s septal penetration rate
crystal
Answer: B. The ability to distinguish the photopeak from scattered radiation — Energy resolution reflects the detector’s
ability to differentiate the photopeak (full-energy deposition) from Compton-scattered and other lower-energy photons.
11. Dead time in a nuclear medicine detection system refers to:
A. The time a radioactive source takes to decay B. The period after a detected event during which
the system cannot process additional events
C. The time required for image reconstruction D. The interval between patient injections
Answer: B. The period after a detected event during which the system cannot process additional events — Dead time
is the interval during which the detector is busy processing one event and cannot record incoming photons, leading to count
loss at high count rates.
12. Which type of dead time results in a count rate that eventually decreases with increasing activity?
A. Paralyzable dead time B. Non-paralyzable dead time
C. Fixed dead time D. Resolving time
Answer: A. Paralyzable dead time — In paralyzable (extendable) dead time, each event extends the dead period, causing the
measured count rate to peak and then decline as activity increases.
2
, Nuclear Medicine Practice Exam – NMTCB/ARRT Preparation
13. Linearity testing of a gamma camera evaluates:
A. Uniformity of detector response B. The relationship between count rate and source
activity
C. Image sharpness at the edges of the field of view D. Collimator hole alignment
Answer: B. The relationship between count rate and source activity — Linearity ensures that the count rate measured by
the system is directly proportional to the activity of the source across the full range of clinical activities.
14. A pinhole collimator produces which type of image?
A. An inverted (upside-down) magnified image B. A minified image
C. A true-sized image D. A double-inverted image
Answer: A. An inverted (upside-down) magnified image — The pinhole collimator produces an inverted and magnified
image, useful for small organs such as the thyroid or pediatric imaging.
15. What is the primary advantage of PET/CT over standalone PET?
A. Lower radiation dose to the patient B. Elimination of attenuation correction
C. Anatomical localization of metabolic findings via D. Reduced scan acquisition time
CT
Answer: C. Anatomical localization of metabolic findings via CT — PET/CT combines metabolic PET data with
anatomical CT images, allowing precise localization of abnormal FDG uptake to specific anatomical structures.
16. The half-value layer (HVL) for Tc-99m (140 keV) in lead is approximately:
A. 0.03 mm B. 0.25 mm
C. 2.5 mm D. 6.5 mm
Answer: B. 0.25 mm — The HVL of 140 keV photons in lead is approximately 0.25 mm, meaning 0.25 mm of lead reduces the
photon intensity by half.
17. Which reconstruction algorithm is most commonly used in modern SPECT imaging?
A. Back-projection only B. Filtered back-projection (FBP)
C. Ordered-subsets expectation maximization D. Fourier transform reconstruction
(OSEM)
Answer: C. Ordered-subsets expectation maximization (OSEM) — OSEM is the preferred iterative reconstruction
algorithm because it produces better image quality with less noise than FBP, especially at lower count densities.
18. Septal penetration in a collimator is most likely to occur with:
A. Low-energy photons and a high-energy B. High-energy photons and a low-energy
collimator collimator
C. Low-energy photons and a low-energy D. High-energy photons and a high-energy
collimator collimator
Answer: B. High-energy photons and a low-energy collimator — When high-energy photons strike a collimator designed
for low-energy radionuclides, photons can penetrate the septa, degrading image contrast and resolution.
Section II: Radiopharmacy & Radiochemistry (Questions 19–35)
19. The Tc-99m generator uses which parent radionuclide adsorbed onto an alumina column?
A. Tc-99 B. Mo-99
C. I-131 D. F-18
3
