Position denotes the placement of the patient’s body, specifically the portion of the patient’s anatomy that is in contact with the Bucky. However, when one deals with the head, neck, or body trunk, the lateral and oblique projections are further clarified by the specific “position” of the patient. In the extremities, lateral projections are similarly described by the direction of the central ray hence, mediolateral and lateromedial projections are possible. For example, A denotes an anteroposterior (AP) projection and B a posteroanterior (PA) projection. The term radiographic “projection” references the path of the central ray as it exits the x-ray tube and passes through the patient’s body. An increase in mAs is required if the bony detail is present but the overall appearance of the film is too light.įIG 3-4 Radiographic views. When a film is critiqued, if the bony detail is too light so as to appear nonexistent, a 15% increase in kVp provides the necessary penetration. There may be instances when a change in penetration, or kVp, is necessary. Corrections for individual variations in machines are made by adjusting the mAs only because the chart was formulated using the fixed kV technique. The techniques contained in the chart provide a starting point of adequate exposures for a radiographic system similar to the one listed. When a fixed kV system is used, only one exposure factor, the mAs, needs to be changed to correct for errors. The reverse is true for films that are overexposed. To correct the exposure factors in a film that is underexposed, the mAs must be changed by a minimum of 30% to note a detectable change or by 100% for a significant change. In this system, the milliampere-seconds (mAs) is variable, and corrections in exposure factors require changing the mAs only. In smaller patients, the lower spectrum of the kV range is used in larger patients, the upper range of kV is used. The suggested technique is within a fixed kilovolt (kV) range per body part.
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