Free Nuclear Medicine Exam Questions That Helps Candidates Pass

Comprehensive and Detailed Explanation: Tc-99m MDP (or HDP) is the standard agent for three-phase bone scintigraphy used to evaluate suspected acute osteomyelitis. Hyperperfusion and hyperemia in the flow and blood-pool phases combined with increased uptake on delayed images support the diagnosis, especially when radiographic changes are absent. Sulfur colloid is used for bone-marrow imaging or liver-spleen studies. Ga-67 and labeled leukocytes are reserved for more complex or chronic infection cases or when the bone scan is equivocal. Technologists must acquire true dynamic flow images (rapid sequential frames), a blood-pool image within a few minutes, and delayed images at 2–4 hours. Proper injection technique (bolus) and positioning are critical for diagnostic quality.

Comprehensive and Detailed Explanation: A “Caution – Radioactive Materials” sign is posted at entrances to rooms or areas where radioactive materials are used or stored in quantities exceeding regulatory thresholds. The sign alerts personnel and visitors that radioactive materials are present so that appropriate precautions can be taken. It does not by itself indicate a high-radiation area (which requires a different posting when dose rates exceed 100 mrem/hr at 30 cm). The sign does not eliminate the need for dosimetry or training. Proper posting is a basic regulatory requirement and is checked during inspections. Technologists must ensure that signs are visible, accurate, and removed when no longer applicable.

Comprehensive and Detailed Explanation: A four-quadrant bar phantom or orthogonal-hole phantom is imaged to assess spatial resolution (the smallest bars that can be clearly distinguished) and spatial linearity (straightness of the bars). The test is performed intrinsically or extrinsically at regular intervals. Loss of resolution or appearance of distortion indicates problems with the crystal, PMTs, or electronics. Energy resolution requires a pulse-height spectrum; dose-calibrator testing is separate. Routine resolution testing helps ensure the camera can produce diagnostically adequate images before patient studies are performed.

Comprehensive and Detailed Explanation: Peaking a well counter (or gamma camera) centers the pulse-height window on the photopeak so that the maximum number of primary photons is accepted while scatter and background are minimized. Incorrect peaking reduces counting efficiency and can introduce errors in quantitative measurements such as thyroid uptake, wipe tests, or blood-volume calculations. The procedure should be performed whenever a different radionuclide is counted or when instrument stability is in question. Technologists must verify the correct isotope setting and window width before acquiring patient or quality-control counts.

Comprehensive and Detailed Explanation: The standardized solid-meal gastric-emptying protocol uses Tc-99m sulfur colloid thoroughly mixed into scrambled egg whites or a whole-egg sandwich so that the tracer remains bound to the solid phase. Liquid emptying is studied with In-111 DTPA or Tc-99m DTPA in water. MAA and MDP are not appropriate. Technologists must prepare the meal exactly according to the protocol, ensure the patient consumes it within the required time, and acquire images at the prescribed intervals (typically up to 4 hours). Accurate quantification of the percentage of meal retained depends on consistent technique and proper decay correction.