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. This is a diploma paper on thin metal films as soft x-ray filters. 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. When the x-ray beam is produced, many energies of photons exist. The use of filters produce a cleaner image by. Filtration is required to absorb the lower-energy x-ray photons emitted by the tube before they reach the target. Another test can be performed to determine if adequate filtration is present, if HVL cannot be determined. Title: X-ray Filtration 1 X-ray Filtration. At x-ray energies, filters consist of material placed in the useful beam to absorb, preferentially, radiation based on energy level or to modify the spatial distribution of the beam.
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. 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. Consists of a metal plate or disk made from lead. 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. The effect of filtration on x ray beam is absorption of most of long wave length photons. 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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