Free Nuclear Medicine Exam Questions That Helps Candidates Pass

Comprehensive and Detailed Explanation: Accuracy testing compares the dose calibrator’s reading of calibrated reference sources with their known activities and is performed at installation and at least annually thereafter (or more frequently if required by the manufacturer or license conditions). Daily constancy checks monitor short-term stability; linearity and geometry tests are typically quarterly. Failure of an accuracy test indicates that the instrument may be giving systematically incorrect readings and must be repaired or recalibrated before further clinical use. Documentation of annual accuracy results is required for regulatory compliance.

Comprehensive and Detailed Explanation: Peaking centers the pulse-height analyzer window on the photopeak so that the maximum number of primary photons is accepted while scatter is minimized. Modern cameras often perform automatic peaking, but the technologist must still verify that the correct isotope is selected and that the window width is appropriate. Incorrect peaking reduces sensitivity, increases noise, and can introduce artifacts. Peaking should be confirmed whenever a different radionuclide is used or when the camera has been idle. It is a fundamental daily quality-control step.

Comprehensive and Detailed Explanation: A pinhole collimator provides magnified images with very high spatial resolution, making it ideal for small structures such as the thyroid gland, pediatric hips, or other superficial organs. Sensitivity is low because only photons passing through the small aperture are accepted, so longer imaging times or higher activities are often required. It is not suitable for large organs or whole-body imaging. Technologists must position the pinhole carefully at the correct distance to achieve the desired magnification and must ensure that the organ of interest remains within the field of view. Proper use of the pinhole collimator significantly improves diagnostic detail for the indicated studies.

Comprehensive and Detailed Explanation: Tc-99m MDP or HDP is the standard agent for three-phase bone scintigraphy. The flow phase evaluates perfusion, the blood-pool phase evaluates soft-tissue hyperemia, and the delayed phase evaluates osteoblastic activity. This sequence is particularly useful for differentiating osteomyelitis from cellulitis and for evaluating other inflammatory or vascular conditions. Sulfur colloid, DTPA, and MAA have different biodistributions and are not appropriate. Technologists must inject the tracer as a rapid bolus, begin dynamic imaging immediately, and maintain consistent positioning across all three phases.

Comprehensive and Detailed Explanation: The traditional unit of radioactivity is the curie (Ci), originally defined as the activity of 1 gram of radium-226 and now defined as 3.7 × 10¹⁰ disintegrations per second. The SI unit is the becquerel (1 Bq = 1 dps). Absorbed dose is measured in rad or gray; equivalent dose in rem or sievert. Although SI units are preferred, many package inserts, dose calibrators, and written directives still use millicuries. Technologists must be fluent in converting between systems (1 mCi = 37 MBq) to avoid dosing errors. Accurate unit conversion is a basic competency tested on certification examinations.