Free Nuclear Medicine Exam Questions That Helps Candidates Pass

Comprehensive and Detailed Explanation: A wipe (swipe) of the external surface of an incoming radioactive package is required to detect removable contamination. The wipe is counted and the result compared with regulatory limits (typically 2 200 dpm/100 cm²). Elevated contamination indicates possible leakage or damage and must be reported to the radiation safety officer and the carrier. The external dose-rate survey measures penetrating radiation but does not detect loose contamination. Technologists must wear gloves, use proper technique, and document both dose-rate and wipe-test results. This procedure protects staff and is a standard regulatory requirement.

Comprehensive and Detailed Explanation: After reconstitution, most Tc-99m kits are stored at room temperature or under refrigeration as specified in the package insert, and they must be used within the stated beyond-use time (often 6–12 hours). Freezing can damage the formulation; excessive heat or light can reduce stability and radiochemical purity. The technologist must record the time of preparation and the expiration time on the vial and on unit-dose labels. Using a kit beyond its expiration time risks reduced labeling efficiency and altered biodistribution. Institutional policies often require radiochemical purity testing near the end of the shelf life or when visual changes are noted.

Comprehensive and Detailed Explanation: Center-of-rotation (COR) calibration determines any offset between the mechanical axis of the gantry and the electronic center of the detector matrix. Small misalignments produce blurring and circular artifacts in reconstructed SPECT images. The calibration is performed with a point or line source at regular intervals and after service. Technologists must verify that the correct COR file is selected for the collimator and orbit type. Accurate COR calibration is essential for high-quality cardiac, brain, and skeletal SPECT studies.

Comprehensive and Detailed Explanation: Strontium-89 is a pure beta emitter used for the palliation of bone pain from osteoblastic metastases. Because it emits no gamma photons, it cannot be imaged with a gamma camera and delivers a local radiation dose to bone with minimal external exposure hazard after administration. Tc-99m and I-123 are gamma emitters used for diagnostic imaging; F-18 is a positron emitter. Other pure or predominantly beta emitters used in therapy include P-32, Y-90, and Sm-153 (the latter also emits a low-abundance gamma). Technologists must understand that pure beta emitters require different handling, survey, and patient-release considerations than gamma-emitting radiopharmaceuticals.

Comprehensive and Detailed Explanation: The usual adult dose of Tc-99m MAG3 is 5–10 mCi (185–370 MBq). Lower activities may be used in pediatric patients scaled by body weight or surface area. Higher doses increase radiation exposure without proportional diagnostic benefit. Technologists must assay the dose accurately, inject as a bolus for perfusion assessment, and begin dynamic imaging immediately. Proper hydration and timing of furosemide (when used) are critical for accurate interpretation of obstruction. Knowledge of standard dose ranges helps prevent under- or over-dosing and ensures compliance with ALARA principles and institutional protocols.