22 board-style nuclear medicine questions for the NMTCB (CNMT) and ARRT(N) exams, covering all five domains. Try each one, then open the answer for the full explanation. No sign-up needed.
Radiation Safety · Radiopharmaceuticals · Instrumentation & QC · Clinical Procedures · Patient Care
1. The NRC annual occupational whole-body dose limit is:
Answer: B — 5 rem (50 mSv)
10 CFR Part 20 sets the occupational whole-body limit at 5 rem (50 mSv) per year. ALARA goals aim for doses well below this limit.
2. The principle of ALARA stands for:
Answer: D — As Low As Reasonably Achievable
ALARA (As Low As Reasonably Achievable) is the guiding principle of radiation protection, meaning doses should be kept as low as practicable beyond regulatory limits.
3. The dose limit for the lens of the eye for radiation workers is:
Answer: A — 15 rem/year
Per NRC regulations (10 CFR 20.1201), the annual occupational dose limit for the lens of the eye is 15 rem (150 mSv).
4. Technetium-99m is produced from which parent radionuclide in a generator?
Answer: B — Molybdenum-99
Tc-99m is produced by the decay of Mo-99 (T½ = 66 hr) via beta decay. Mo-99 is adsorbed on an alumina column in the generator; Tc-99m elutes with saline. This is the basis of the Mo-99/Tc-99m generator.
5. The half-life of Technetium-99m is:
Answer: D — 6.0 hours
Tc-99m has a physical half-life of 6.02 hours. This relatively short half-life limits patient dose while allowing adequate imaging time for most nuclear medicine procedures.
6. Tc-99m emits a gamma ray with an energy of approximately:
Answer: C — 140 keV
Tc-99m emits a 140 keV gamma ray, which is nearly ideal for gamma camera imaging — energetic enough to escape tissue but low enough for efficient collimation and detection.
7. The mechanism of Tc-99m MDP uptake in bone is:
Answer: D — Chemisorption onto hydroxyapatite crystal surfaces at active bone sites
Tc-99m MDP (methylene diphosphonate) localizes to bone through chemisorption onto hydroxyapatite crystals. Uptake is greatest at sites of increased osteoblastic activity and blood flow.
8. Which Tc-99m agent is used for myocardial perfusion imaging and works by passive diffusion across cell membranes with mitochondrial retention?
Answer: D — Tc-99m Sestamibi (MIBI)
Tc-99m Sestamibi (MIBI) diffuses passively into myocardial cells and is sequestered in mitochondria based on the large negative membrane potential. It shows minimal redistribution, unlike Tl-201.
9. The gamma camera detector is composed of which two primary components?
Answer: D — Sodium iodide (NaI) crystal and photomultiplier tubes
The gamma camera detector consists of a large NaI(Tl) scintillation crystal (typically 3/8 inch thick) coupled to an array of PMTs. Gamma photons create light flashes in the crystal; PMTs convert light to electrical signals and determine the location and energy of each event.
10. The primary purpose of the collimator on a gamma camera is to:
Answer: C — Define the direction of accepted gamma rays, for image formation
The collimator (typically parallel-hole lead) limits gamma photons to those traveling in a specific direction (perpendicular to the detector). It provides the spatial encoding necessary to form an image, at the cost of sensitivity.
11. A low-energy high-resolution (LEHR) collimator should be used for imaging which radionuclide?
Answer: C — Tc-99m (140 keV)
LEHR collimators are designed for low-energy photons (< 150 keV) like Tc-99m. Using LEHR with higher-energy photons causes septal penetration, degrading image quality. In-111 requires medium-energy and I-131 requires high-energy collimators.
12. Which collimator provides the BEST spatial resolution for gamma camera imaging?
Answer: D — Low-energy high-resolution (LEHR)
LEHR collimators have longer, narrower septa (holes) which accept a more restricted cone of gamma rays, providing the best spatial resolution. The trade-off is lower sensitivity (fewer counts per unit time).
13. What is the purpose of the pulse height analyzer (PHA) in a gamma camera?
Answer: D — Accepts only pulses within an energy window to reject scatter
The PHA accepts PMT pulses whose height (proportional to photon energy) falls within the selected energy window around the photopeak. This rejects Compton-scattered photons that have lost energy, improving image contrast and accuracy.
14. The STANDARD preparation for a Tc-99m MDP bone scan includes patient instructions to:
Answer: A — Hydrate and void frequently after injection
After Tc-99m MDP injection, patients are instructed to drink plenty of fluids and void frequently. This reduces soft tissue and bladder radioactivity (background), improving bone-to-soft tissue contrast for better image quality.
15. For a three-phase bone scan, which of the following is the correct sequence of image acquisition?
Answer: B — Flow → Blood pool → Delayed static images
A three-phase bone scan consists of: Phase 1 (flow/angiographic): rapid sequential images during injection; Phase 2 (blood pool): immediate static images (2-5 min post-injection); Phase 3 (delayed): static bone images at 2-4 hours.
16. Abnormal findings on a three-phase bone scan showing increased uptake in all three phases is most consistent with:
Answer: C — Osteomyelitis with bone involvement
Osteomyelitis shows increased uptake in all three phases (flow, blood pool, and delayed), reflecting increased blood flow, hyperemia, and bone remodeling. Cellulitis shows increased flow and blood pool but normal delayed (no bone involvement).
17. During a lung perfusion scan using Tc-99m MAA, which patient position should be used for injection?
Answer: D — Supine (lying flat)
The patient should be supine during injection to ensure uniform distribution of MAA throughout both lungs. Injecting in an upright position causes gravitational redistribution, with excess MAA depositing in the lung bases, mimicking perfusion defects.
18. A V/Q scan shows multiple bilateral segmental perfusion defects with normal ventilation in a patient with pleuritic chest pain. According to PIOPED II criteria, this is:
Answer: A — High probability for PE
Two or more large (>75% of segment) or ≥2 moderate segmental V/Q mismatches (perfusion defects with normal ventilation) in the setting of clinical suspicion constitutes high probability for pulmonary embolism per PIOPED II criteria.
19. Which of the following correctly identifies a patient using two identifiers before a nuclear medicine procedure?
Answer: A — Have the patient state their name, confirm DOB or MRN
The Joint Commission requires two patient identifiers before any procedure, drawn from at least two of: full name, date of birth, medical record number, or another assigned ID number. Having the patient actively state their name and then confirming date of birth or MRN is the standard. Asking the name alone is insufficient, the chart alone does not confirm the person in front of you, and room number or physical location is explicitly not an acceptable identifier.
20. A patient refuses to have an intravenous line placed for a nuclear medicine scan, citing needle phobia. The MOST appropriate response is to:
Answer: C — Acknowledge the concern, explain the need for IV access
Respecting patient autonomy while providing compassionate care is paramount. Acknowledge the fear, explain why the IV is necessary, and offer strategies to minimize discomfort (topical EMLA cream, smaller gauge needle, warm compress, distraction techniques). Informed refusal must ultimately be respected.
21. Before administering a radiopharmaceutical to a female patient of childbearing age, the technologist MUST:
Answer: D — Ask about last menstrual period and possible pregnancy.
For all female patients of childbearing potential (typically 12-55 years), the technologist must ask about last menstrual period and possibility of pregnancy before any radioactive administration. This is fundamental radiation protection for the fetus.
22. Informed consent for nuclear medicine procedures typically requires the physician to explain:
Answer: B — The purpose, benefits, risks, and alternatives.
Informed consent requires disclosure of: (1) nature and purpose of the procedure, (2) expected benefits, (3) potential risks (including radiation exposure), (4) alternatives to the procedure, and (5) what will happen if the patient declines. The patient must understand and voluntarily agree.
The full bank has 500 NMTCB and ARRT(N) questions, 100 in each domain, plus clinical case studies, timed mock exams and flashcards. Every answer is explained the same way.
How the two exams are structured, the published content weightings, and how this question bank maps to them: NMTCB and ARRT(N) exam overview →
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