Aluminum disk xray filtration skin#
The low energy photons will not be filtered out and will add entrance skin exposure to patients, increasing their overall dose. and Papp would result in added dose to patient. According to Table 7-1 in Papp and Table 3: HVL results, no corrective action is required.ĭetermining HVL is important and failure to comply to standards defined by S.C. This test is done using a 2.3mm thick piece of aluminum and a dosimeter and should not replace the HVL measurement during quality control testing. However, this test only determines if adequate filtration is present and doesn't account for the total amount of filtration. The amount of additional filtration (from Aluminum layers) needed in order to establish standard x-ray qualities to be used in. Aluminum layers, on the other hand, show good performances to reduce the beams to the desired levels. X-ray taken at 90 kVp and 45 mAs with 1 mm Al added filtration. X-ray taken at 90 kVp and 45 mAs with 1 mm Al and 0.1 mm Cu added filtration. Another test can be performed to determine if adequate filtration is present, if HVL cannot be determined. suitable forthis purpose as most of the x-ray was absorbedin the material. X-ray taken at 85 kVp and 45 mAs without additional filtration. So by measuring the HVL, it doesn't matter what material is in the path of the beam, as long as sufficient beam quality is obtained. filtration and added filtration were tested by taking several images and also incorporating varying thicknesses of aluminum (Al) and copper (Cu). The filament evaporates as the tube is used, adding a layer of tungsten to the inside of the x-ray tube window. The best way to determine if adequate filtration exists is to measure HVL as it is not possible to measure inherent filtration.
The materials necessary and the setup are outlined below in Figure 1.Īccording to Papp, a filtration check is performed before new equipment is used and then annually, unless service has been performed on the x-ray tube or collimator. In this experiment, the purpose is to measure the quality of the x-ray beam. It also helps to determine the type and thickness of shielding required in the facility. HVL is an important quality control test as it is used to measure whether or not there is sufficient filtration in the x-ray beam to remove low energy radiation, which can be damaging.
HVL is an indirect measure of photon energy or beam hardness. The HVL of an x-ray beam is defined as the amount of absorbing material that is needed to reduce the beam to half of its original potential. In radiography, technologists use the half value layer (HVL) to measure the quality or intensity of the beam. Reduction in the intensity of the beam can be affected by the atomic number of the absorbing material or beam energy. The intensity of an x-ray beam is an important property in radiography and can be reduced as it penetrates an object by absorption or scattering.
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