Content area
Full Text
Abstract
XCP dental x-ray film positioning devices help to increase the dimensional accuracy of dental x-ray images. (XCP stands for "extension cone paralleling." Some dental assistants refer to them as "Rinn" devices, after a company that manufactures them.) The XCP device has a collimator ring that is parallel with the film-holding plane of the x-ray film holder. This positioning helps an assistant to align the plane of the unseen, intraorally located x-ray film parallel with the plane of the cross section of the x-ray beam. XCP devices also help to prevent dental x-ray film cone cuts, since the extraoral collimator ring helps to indicate the boundary of the unseen x-ray film. Unfortunately, the devices can be confusing to assemble because each device consists of three pieces that can be assembled in multiple ways, and there are three types of such devices for anterior, posterior and bitewing radiographs (in addition to a fourth accessory device for taking endodontic radiographs). It can be challenging to determine which piece goes with which type of XCP, and to choose the correct XCP assembly for taking a desired x-ray. This article describes some clinical techniques of assembling XCP radiographic film-holding devices, describes the clinical use of XCP devices, and ways of overcoming intraoral obstacles to device placement.
The XCP film holder consists of three parts: a filmholding piece with two fused planes angled at 90 degrees to each other, a large round collimator ring and a metal rod that connects the ring with the film holder (Figure 1,page 10). One plane ofthe film-holding piece contains a slot in which the x-ray film is inserted, while the other plane serves as a platform on which the patient bites down, This platform also contains the insertion holes for the prongs ofthe metal rod to insert into to connect the collimator ring with the film-holding piece. The collimator ring itself contains a slot which slides into the side ofthe metal rod that is opposite the side containing the prongs. Sliding the ring along the rod brings the ring as close to the patient s cheek as possible. Thisallowstheopeningofthex-raytube^placedup against the collimator ring, to be as close to the film as possible. The plane of the collimator ring is parallel with the...