What does a positive beam limitation (PBL) device primarily assist with?

A positive beam limitation (PBL) device is primarily designed to assist with collimation. It ensures that the X-ray beam is confined to the area of interest being imaged, thus reducing unnecessary radiation exposure to surrounding tissues and improving the quality of the images obtained. The PBL device automatically adjusts the size of the X-ray field to match the dimensions of the imaging receptor based on the selected examination protocol. This improves both patient safety and diagnostic efficacy by minimizing scatter radiation and enhancing image contrast.

Other options, such as exposure time control, filtration, and digital image processing, refer to different aspects of radiographic technique and image quality but are not the primary functions of a PBL device.