@article{oai:repo.qst.go.jp:00043503,
 author = {Kanai, Tatsuaki and Fukumura, Akifumi and Kusano, Yohsuke and Shinbo, Munefumi and Nishio, Teiji and 金井 達明 and 福村 明史 and 新保 宗史 and 西尾 禎治},
 journal = {Physics in Medicine and Biology},
 month = {Feb},
 note = {The calibration coefficinets of a parallel plate ionization chamber are examined by comparing the coefficients obtained through three methods: a calculation from a Co-60 calibration coefficient, N[D,w,Co-60], a cross-calibration of a parallel plate ionization chamber using a cylindrical ionization chamber at the plateau region of a mono-energetic beam and a cross-calibration of the chamber using a cylindrical chamber at the middle of the SOBP of the therapeutic beams,  This paper also examines reference conditions for determining absorbed dose to water in the cases of therapeutic carbon and proton beams,  In the dose calibration procedure recommended by IAEA, irradiation fields should be larger than 10 cm in diameter and the water phantom should extend by at least 5 cm beyond each side of the field.  These recommendations are experimentally verified for proton and carbon beams. For proton beams, the calibration coefficients obtained by these three methods epproximately agreed.  For carbon beams, the calibration coefficients obtained by the second method were about 1.0 % larger thanthose obtained by the third method, and the calibration coefficinets obtained by cross-calibration using 290 MeV/u beams were 0.5% lower than those obtained using 400 MeV/u beams.  The calibration coefficinet obtained by the first method agreed roughly with the results obtained by SOBP beams.},
 pages = {771--781},
 title = {Corss-calibration of ionization chambers in proton and carbon beams},
 volume = {49},
 year = {2004}
}