Electron beam energy degradation by low density scattering material
| Autor: | Robert James Stewart, Chavalit Wongse‐Ek', Christopher Karolis |
|---|---|
| Rok vydání: | 1981 |
| Předmět: |
Cancer Research
Radiation business.industry Isocenter Collimator Electrons Electron Linear particle accelerator law.invention Radiotherapy High-Energy Optics Radiation Protection Oncology law Homogeneity (physics) Cathode ray Medicine Humans Radiology Nuclear Medicine and imaging Irradiation Nuclear medicine business Beam (structure) Filtration |
| Zdroj: | International journal of radiation oncology, biology, physics. 7(3) |
| ISSN: | 0360-3016 |
| Popis: | Low density filters have been used successfully for many years to degrade the normally available electron beams from medical linear accelerators for the treatment of skin disorders and chest wall irradiation. In the former case the filter is generally far removed from the patient for whole body irradiation while in the latter case the filter is in contact with patient's skin. In the case of our 18 MeV accelerator', where the cones are 5 cm short of the isocenter, placing filters at the cone face leads to a reduction in beam homogeneity at the patient. The reduction has been found to be as high as 80 % in some cases and is a function of filter thickness, nominal beam energy and cone size. Placing filters at the collimator face, with the electron applicator attached, leads to acceptable field homogeneity but significantly reduces the electron output with a small increase in X ray contamination. In this study, high impact polystyrene and acrylic sheets have been used as filters to degrade the incident electron beam energies normally available on our accelerator. The effects of placing these filters at varous sites in the beam have been examined in detail. Our results show that electron beam energy degradation using filters is a trade off between homogeneity on the one hand and X ray contamination and output on the other. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
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