NMTCB CNMT Practice Exam 2026/2027 | 300+ Nuclear
Medicine Technology Questions, Correct Answers & Detailed
Rationales
DOMAIN I — RADIATION PHYSICS & DETECTION
1. Which type of radioactive decay results in the emission of a helium
nucleus?
A. Beta-minus decay
B. Alpha decay
C. Positron decay
D. Isomeric transition
Correct Answer: B
Rationale: Alpha decay releases an alpha particle, which consists of two
protons and two neutrons and is identical to a helium-4 nucleus.
2. During beta-minus decay, a neutron is converted into:
A. A proton, electron, and antineutrino
B. A proton, positron, and neutrino
C. Two protons and an electron
D. An alpha particle and neutrino
Correct Answer: A
Rationale: In beta-minus decay, a neutron becomes a proton while
emitting an electron and an antineutrino. The atomic number increases
by one while the mass number remains unchanged.
,3. Positron emission changes the atomic number by:
A. Increasing it by 2
B. Increasing it by 1
C. Decreasing it by 1
D. Leaving it unchanged
Correct Answer: C
Rationale: In positron emission, a proton converts into a neutron,
decreasing the atomic number by one while the mass number remains
unchanged.
4. Electron capture results in:
A. Conversion of a neutron to a proton
B. Conversion of a proton to a neutron
C. Emission of an alpha particle
D. Emission of two gamma photons
Correct Answer: B
Rationale: The nucleus captures an inner-shell electron, causing a
proton to become a neutron. The atomic number therefore decreases
by one.
5. Which radiation has the greatest mass?
A. Gamma photon
B. Beta particle
,C. Alpha particle
D. X-ray photon
Correct Answer: C
Rationale: Alpha particles contain two protons and two neutrons and
therefore have substantially more mass than electrons or photons.
6. Gamma radiation is best described as:
A. A helium nucleus
B. A high-energy electromagnetic photon
C. A negatively charged electron
D. A positively charged electron
Correct Answer: B
Rationale: Gamma radiation is electromagnetic radiation emitted from
the nucleus. It has no mass and no electrical charge.
7. Which radionuclide is commonly used for routine gamma-camera
imaging?
A. Tc-99m
B. Sr-90
C. Ra-226
D. Am-241
Correct Answer: A
, Rationale: Tc-99m emits a 140-keV gamma photon and has a physical
half-life of approximately six hours, making it highly suitable for
diagnostic nuclear medicine.
8. What is the physical half-life of Tc-99m?
A. 30 minutes
B. 6 hours
C. 24 hours
D. 60 days
Correct Answer: B
Rationale: Tc-99m has a physical half-life of approximately 6 hours.
9. If a radionuclide has a physical half-life of 8 hours, what fraction
remains after 24 hours?
A. 1/2
B. 1/4
C. 1/8
D. 1/16
Correct Answer: C
Rationale: Twenty-four hours represents three half-lives. After three
half-lives, the remaining activity is (1/2)³ = 1/8.
10. A sample initially contains 80 mCi. How much remains after two
half-lives?
Medicine Technology Questions, Correct Answers & Detailed
Rationales
DOMAIN I — RADIATION PHYSICS & DETECTION
1. Which type of radioactive decay results in the emission of a helium
nucleus?
A. Beta-minus decay
B. Alpha decay
C. Positron decay
D. Isomeric transition
Correct Answer: B
Rationale: Alpha decay releases an alpha particle, which consists of two
protons and two neutrons and is identical to a helium-4 nucleus.
2. During beta-minus decay, a neutron is converted into:
A. A proton, electron, and antineutrino
B. A proton, positron, and neutrino
C. Two protons and an electron
D. An alpha particle and neutrino
Correct Answer: A
Rationale: In beta-minus decay, a neutron becomes a proton while
emitting an electron and an antineutrino. The atomic number increases
by one while the mass number remains unchanged.
,3. Positron emission changes the atomic number by:
A. Increasing it by 2
B. Increasing it by 1
C. Decreasing it by 1
D. Leaving it unchanged
Correct Answer: C
Rationale: In positron emission, a proton converts into a neutron,
decreasing the atomic number by one while the mass number remains
unchanged.
4. Electron capture results in:
A. Conversion of a neutron to a proton
B. Conversion of a proton to a neutron
C. Emission of an alpha particle
D. Emission of two gamma photons
Correct Answer: B
Rationale: The nucleus captures an inner-shell electron, causing a
proton to become a neutron. The atomic number therefore decreases
by one.
5. Which radiation has the greatest mass?
A. Gamma photon
B. Beta particle
,C. Alpha particle
D. X-ray photon
Correct Answer: C
Rationale: Alpha particles contain two protons and two neutrons and
therefore have substantially more mass than electrons or photons.
6. Gamma radiation is best described as:
A. A helium nucleus
B. A high-energy electromagnetic photon
C. A negatively charged electron
D. A positively charged electron
Correct Answer: B
Rationale: Gamma radiation is electromagnetic radiation emitted from
the nucleus. It has no mass and no electrical charge.
7. Which radionuclide is commonly used for routine gamma-camera
imaging?
A. Tc-99m
B. Sr-90
C. Ra-226
D. Am-241
Correct Answer: A
, Rationale: Tc-99m emits a 140-keV gamma photon and has a physical
half-life of approximately six hours, making it highly suitable for
diagnostic nuclear medicine.
8. What is the physical half-life of Tc-99m?
A. 30 minutes
B. 6 hours
C. 24 hours
D. 60 days
Correct Answer: B
Rationale: Tc-99m has a physical half-life of approximately 6 hours.
9. If a radionuclide has a physical half-life of 8 hours, what fraction
remains after 24 hours?
A. 1/2
B. 1/4
C. 1/8
D. 1/16
Correct Answer: C
Rationale: Twenty-four hours represents three half-lives. After three
half-lives, the remaining activity is (1/2)³ = 1/8.
10. A sample initially contains 80 mCi. How much remains after two
half-lives?
