Kerma area product (KAP) and scatter measurements for intraoral X-ray machines using three different types of round collimation compared with rectangular beam limiter.

Although, US FDA regulations allow a maximum beam size of 38.5 cm2 on the patient skin, this study suggests that the use of rectangular collimators provide clinically relevant dose reduction for patients, even when using smaller round collimation, hence the use of rectangular collimation for all intraoral radiographic procedures is highly recommended.