American Registry of Radiologic Technologists (ARRT) Practice Exam

What is assessed with a synchronous spinning top test in three-phase equipment?

1. Tube cooling rate

2. Rectifier function and timer accuracy

3. Film speed calibration

4. Exposure duration

The correct answer is: Rectifier function and timer accuracy

The synchronous spinning top test is a specific quality control procedure used to evaluate the performance of three-phase radiographic equipment. When performing this test, it primarily assesses the rectifier function and timer accuracy of the x-ray machine. In three-phase systems, rectifiers convert alternating current (AC) into direct current (DC), which is necessary for the operation of the x-ray tube. The spinning top test provides a visual representation of the exposure duration by producing a series of dots on the film. The pattern and spacing of these dots indicate how well the timing system is functioning and whether the rectification is occurring as expected. If there are inconsistencies in the dot pattern, it may suggest issues with either the rectifiers or the timing mechanism itself. This method is not intended to measure tube cooling rates, calibrate film speed, or directly determine exposure duration in a practical sense, as those aspects are evaluated through different tests or procedures tailored to those needs. Thus, the focus of the synchronous spinning top test is accurately on the rectifier function and timer accuracy.