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Journal of the Korean Society for Therapeutic Radiology 1988;6(1): 109-116. |
Contamination of an Alcyon Co-60 gamma rays by Electrons |
Meong Jin Yoo, Dong Won Kim, Chul Soo Kim, Woon Hyuk Chung |
1Department of Therapeutic Radiology, Pusan National University Hospital, Pusan, Korea. 2Department of Radiation Oncology, Pusan Paik Hospital, Pusan, Korea. 3Department of Physics, Pusan National University University, Pusan, Korea. |
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ABSTRACT |
The Alcyon Co-60 gamma rays was studied for electron contamination. The surface dose, attributable almost entirely to contamination electrons, has a linear dependence on field width for square fields and an inverse square dependence on distance from the bottom of the fixed head assembly. Build-up and surface dose measurements were taken with and without an acrylic blocking tray in place. Further measurements were made with a copper filter designed to reduce secondary electrons emitted by photon interactions with the acrylic tray. The results are discussed in relation to skin sparing effect for radiation therapy patients. And to achieve the maximum skin sparing effect, the selection of the optimum SSD and TSD is needed. |
Key Words:
Electron contamination, Electron filter, SSD, TSD, Surface dose |
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