NMTCB Radiation Physics & Detection 2

Question 1

Which interaction mechanism is primarily responsible for photoelectric absorption in diagnostic nuclear medicine energy ranges?

Accepted Answer

Ejection of an inner-shell electron by a photon that is completely absorbed

Answer

In photoelectric absorption, an incident photon transfers all its energy to an inner-shell electron, ejecting it and leaving no scattered photon.

Question 2

The Q-value of a nuclear reaction represents:

Accepted Answer

The net energy released or absorbed in a nuclear reaction

Answer

The Q-value is the difference in rest-mass energy between reactants and products, indicating whether energy is released (positive Q) or required (negative Q).

Question 3

In a sodium iodide (NaI) detector, thallium doping primarily serves to:

Accepted Answer

Shift the emission spectrum to visible light wavelengths detectable by the PMT

Answer

Thallium impurities create luminescence centers that emit visible light (~415 nm) compatible with photomultiplier tube sensitivity.

Question 4

The dead time of a radiation detector refers to:

Accepted Answer

Period after an event during which the detector cannot register another event

Answer

Dead time is the minimum time interval that must elapse after detecting one event before the detector can register a subsequent event.

Question 5

Which property makes technetium-99m particularly ideal for nuclear medicine imaging?

Accepted Answer

140 keV gamma emission with 6-hour half-life and no particulate radiation

Answer

Tc-99m emits a 140 keV gamma ray ideal for gamma camera collimation, has a 6-hour half-life minimizing patient dose, and produces no particulate radiation.

(NMTCB) Nuclear Medicine Technology Certification Board Practice Test

(NMTCB) Nuclear Medicine Technology Certification Board Practice Test

NMTCB Radiation Physics & Detection 2