Free Nuclear Medicine Exam Questions That Helps Candidates Pass

Comprehensive and Detailed Explanation: The usual adult dose of Tc-99m MDP or HDP is 20–30 mCi (740–1110 MBq). Pediatric doses are scaled by body weight or surface area. Higher activities increase radiation dose without proportional gain in diagnostic information. Technologists must assay the dose accurately, ensure proper hydration after injection, and schedule imaging 2–4 hours later to allow soft-tissue clearance. Knowledge of the standard dose range helps prevent dosing errors and supports ALARA practice while still providing adequate count density for high-quality planar and SPECT images.

Comprehensive and Detailed Explanation: Investigation levels are set below regulatory limits so that higher-than-usual exposures can be reviewed before limits are approached. When a ring-badge reading exceeds the investigation level, the radiation safety officer must be notified. Together the RSO and technologist examine recent work habits, shielding use, time spent handling sources, and possible contamination of the badge. Corrective actions (additional shielding, practice changes, retraining) are implemented. Ring badges can be affected by geometry and contamination, but elevated readings are never ignored. Documentation of the investigation is required. Prompt attention prevents further unnecessary extremity dose and demonstrates a functioning ALARA program.

Comprehensive and Detailed Explanation: Geometry testing evaluates how changes in sample volume, vial or syringe size, or position within the chamber affect the calibrator reading. Correction factors are established when significant differences are found. The test is performed at installation and after major repairs or when new container types are introduced. Daily constancy and quarterly linearity tests serve different purposes. Accurate geometry correction prevents systematic errors when assaying doses in containers different from those used for calibration. Technologists must apply the correct geometry factor when required by institutional protocol.

Comprehensive and Detailed Explanation: Tc-99m sodium pertechnetate is taken up by gastric mucosa and is therefore the agent of choice for detecting Meckel’s diverticulum that contains ectopic gastric mucosa. Sequential imaging of the abdomen is performed for 30–60 minutes after injection. Premedication with H2 blockers, pentagastrin, or glucagon may be used according to institutional protocol to enhance uptake or reduce intestinal motility. Sulfur colloid, MDP, and MAA have different biodistributions and are not appropriate. Technologists must know the correct timing, positioning (including lateral views if needed), and possible pharmacologic interventions so that ectopic mucosa is not missed and so that physiologic gastric activity is correctly interpreted.

Comprehensive and Detailed Explanation: A three-phase bone scan consists of a dynamic flow (perfusion) phase acquired immediately after bolus injection of Tc-99m MDP or HDP, a blood-pool (soft-tissue) phase obtained a few minutes later, and delayed static or SPECT images acquired 2–4 hours post-injection. The dynamic flow phase shows arterial delivery of the tracer and is useful for evaluating vascularity of lesions such as osteomyelitis, reflex sympathetic dystrophy, or tumors. The blood-pool phase reflects soft-tissue hyperemia. Delayed images demonstrate osteoblastic activity. Proper timing, patient positioning, and framing rates are essential. Misidentifying the phases can lead to incorrect interpretation of infection versus other pathology. Nuclear medicine technologists must know the clinical indications that require a three-phase study versus a routine delayed bone scan and must ensure the radiopharmaceutical is injected as a rapid bolus for optimal flow images.