National Board Dental Hygiene Examination (NBDHE) Dental Hygienist Practice Test

Which of the following is NOT a correct regulation regarding PID and tubehead sizes?

1. Circular tubeheads must be at least 2 3/4" in diameter

2. Aluminum filters must be at least 1.5 mm thick for exposures below 70 kVp

3. Rectangular tubeheads must be at least 1 3/8 by 1 3/4" in diameter

4. PID lengths must be at least 6"

The correct answer is: PID lengths must be at least 6"

The regulation regarding PID lengths stipulates that they must be a minimum of 6 inches, which is typically accurate for many dental settings; however, the dimension can vary depending on the specific device and the standards set forth by regulatory bodies. In practice, many PIDs in use may be longer than 6 inches to optimize the beam collimation and minimize patient exposure. The other statements provide accurate information regarding the regulations for tube head and PID specifications. For example, the standard diameter for circular tubeheads is established at a minimum of 2 3/4 inches to ensure adequate exposure area and image quality. The requirement for aluminum filters is also to ensure safety; having a minimum thickness of 1.5 mm for exposures lower than 70 kVp helps filter out low-energy x-rays that contribute to patient dose without improving image quality. Lastly, rectangular tubeheads are specifically designed for efficiency in imaging with a minimum width of 1 3/8 by 1 3/4 inches to provide a targeted beam, reducing unnecessary radiation exposure to surrounding tissues. In summary, while the regulation for PID lengths typically indicates a minimum of 6 inches, it is not universally applicable, making it the choice that does not conform to established regulations