Final answer:
When using rectangular collimation with the paralleling technique, one must use a Short PID (Position Indicating Device).
Step-by-step explanation:
When using rectangular collimation with the paralleling technique, one must use a Short PID (Position Indicating Device).
The paralleling technique is a method used in dental radiography to produce accurate and consistent images. Rectangular collimation refers to the use of a rectangular beam shape to limit the radiation exposure to the area of interest and reduce scatter radiation.
A Short PID is necessary for rectangular collimation because it allows for better control of the x-ray beam and restricts the radiation to a smaller area, reducing the chance of unnecessary radiation exposure to the patient.