Free Nuclear Medicine Exam Questions That Helps Candidates Pass

Comprehensive and Detailed Explanation: Photomultiplier-tube (PMT) gain drift or complete failure is a frequent cause of abrupt degradation in spatial resolution and the appearance of cold spots or distorted images. Temperature changes of a few degrees rarely produce measurable effects on modern cameras. Collimator selection and energy-window settings affect performance but are operator-controlled and would be noticed immediately. Daily flood and resolution checks (bar phantoms) detect such problems before patient imaging. When resolution deteriorates, the technologist should acquire an intrinsic flood and bar-phantom image, inspect the PMT map if available, and contact service. Continued use of a camera with a failed PMT can produce diagnostic errors and must be avoided.

Comprehensive and Detailed Explanation: Patients receiving therapeutic I-131 must be given clear written and verbal instructions on radiation precautions. These typically include maintaining distance from others (especially pregnant women and children), sleeping alone, using separate utensils and towels, careful hygiene to avoid contamination from urine and saliva, and the length of time the restrictions apply. The instructions are based on the administered activity and residual dose-rate measurements. Providing and documenting these instructions is a regulatory requirement and an essential part of patient care. Technologists often review the instructions with the patient before release and answer questions to ensure understanding and compliance.

Comprehensive and Detailed Explanation: Hepatobiliary scintigraphy with Tc-99m IDA compounds (mebrofenin or disofenin) is the nuclear-medicine study of choice for suspected acute cholecystitis. Non-visualization of the gallbladder despite adequate hepatic uptake and biliary excretion indicates cystic-duct obstruction. Morphine augmentation or delayed imaging may be used when the gallbladder is not seen on early images. Sulfur colloid, MDP, and MAA are not excreted by the hepatobiliary system. Technologists must verify patient fasting status, administer the correct agent, and follow the timed imaging sequence so that the presence or absence of gallbladder filling can be reliably determined.

Comprehensive and Detailed Explanation: Occupational radiation exposure is monitored with personnel dosimeters—typically a whole-body badge worn at the collar or chest and a ring badge worn on the dominant hand under the glove and syringe shield. Dosimeters must be worn whenever working with or around radioactive material, stored away from radiation sources when not in use, and exchanged at the prescribed frequency (usually monthly or quarterly). The results are reviewed by the radiation safety officer and reported to the worker. Blood tests are not a substitute for dosimetry. Proper use and timely return of dosimeters are regulatory requirements and essential components of an ALARA program.

Comprehensive and Detailed Explanation: A new cold defect on a daily flood most commonly indicates photomultiplier-tube failure, loss of optical coupling, or crystal damage. Continuing to image patients can produce artifacts that mimic disease. The technologist should repeat the flood to confirm the finding. If the defect remains, the camera must be taken out of clinical service until it is repaired and re-qualified. Simply applying an old uniformity map will not correct a hardware failure. Prompt recognition and response protect patients from nondiagnostic studies and are required by quality-assurance standards.