![]() ![]() ![]() Full body machine showing the different axis. If a general radiology unit is used, a technique involving 60 to 85 kVp, about 10 mA, and an FFD/SID of 12 to 16 inches can be used. Transferring an anesthetized patient to another room can often be hectic. The drawback to this unit is that it may already be in use and is not portable thus, using it to produce dental radiographs is inefficient. 2 The tube head must be maneuverable into multiple different planes to obtain diagnostic views. Try to maintain a short FFD/SID to obtain a sharp image. Focal film distance (FFD) or source image distance (SID) is the distance from the tube head to the recording surface, film, or receptor. These units can be used only if the tube head and the focal film distance are adjustable ( FIGURE 2 ). Veterinary medical x-ray units can also be used to produce dental radiographs. In this article, we assume that all angle meters on dental units are set to be 0 degrees when perpendicular to the ground. However, some models have the angle meter set to 90 degrees when perpendicular to the ground or floor. This angle meter is typically set up to with the angle perpendicular to the ground at zero degrees. These units often have predetermined angles marked beside the tube head to help with dental radiography positioning. The time is adjusted to accommodate the thickness of the area of interest being imaged. These units often have fixed or preset peak kilovoltage (kVp) and milliamperage-seconds (mAs) and a variable exposure time. They have flexible arms that allow for optimal positioning and keep exposure to a minimum. These units are portable or wall mounted. An example of a wall mounted dental x-ray unit.ĭ ental x-ray units ( FIGURE 1 ) are most commonly purchased and used to produce dental radiographs. Exposure will be minimized if all personnel practice ALARA. Minimize the length of exposure by using the shortest exposure time required to get a diagnostic image, and strive to achieve the best diagnostic image in the fewest exposures possible. 3 This shielding can consist of lead aprons that include a thyroid shield or a full-length lead shield. If staff cannot be at least 6 feet from the primary beam, they should try to use approved 0.5-mm lead shielding. Staff should remain at a maximum distance from the x-ray beam to reduce exposure to scatter. The inverse square law states that the x-ray beam intensity decreases to one fourth if the distance from the primary beam is doubled. 3 In dental radiography, distance is the most helpful method. Radiation exposure can be minimized by using three simple methods: distance, shielding, and exposure time. Staff should leave the room whenever possible. 3 All personnel must be aware of their own radiation exposure and take all precautions necessary to reduce exposure. Radiation exposure in dental radiography is comparatively low, but one should always practice ALARA (as low as reasonably achievable). Safety is always important when it comes to the production of x-rays. With correct equipment and practice, all technicians can safely and efficiently produce high-quality dental radiographs.
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