Absorbed dose measurements using parallel plate polystyrene ionization chambers in polystyrene phantoms
International Journal of Radiation Oncology*Biology*Physics(1979)
摘要
Ionometric methods are commonly used for the routine calibration of high energy photon and electron beams. Since the basis for all ionometric dose measurements for high energy radiation is the Bragg-Gray relation, the dosimeter and phantom used clearly must achieve close approximation to ideal Bragg-Gray conditions. A polystyrene parallel plate ionization chamber used by the authors in polystyrene phantoms is described which closely fulfills the Bragg-Gray conditions. Intercomparison of dose measurements made in a polystyrene phantom with this chamber and a tissue-equivalent (A-150) calorimeter are described for cobalt-60 gamma rays and 10 MV X-rays, as well as for 11 MeV electrons and 20 McV electrons. The agreement between the two methods was within 1.3% or better. From this it is concluded that the use of a polystyrene parallel plate ionization chamber in a polystyrene phantom provides an accurate, reliable and simple method for the calibration of high energy photon and electron beams.
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关键词
Dosimetry,Ionization chambers,Calibration of high energy X-ray and electron beams Absorbed dose intercomparison
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