@misc{oai:repo.qst.go.jp:00074844,
 author = {Sakata, Suoh and 高瀬, 信宏 and 山下, 航 and 遠藤, 真広 and Sasaki, Yosuke and Hoteida, Masahiro and Okuyama, Hiroaki and Ushiroda, Tota and Mizuno, Hideyuki and Narita, Katuhisa and 福村, 明史 and Sakata, Suoh and Takase, Nobuhiro and Yamashita, Wataru and Endo, Masahiro and Mizuno, Hideyuki and Fukumura, Akifumi},
 month = {Nov},
 note = {Purpose: In the separated calibration, the ionization chamber and electrometer constituting the dosimeter are calibrated individually, and calibration coefficient is given for each. This method has some advantages for both the calibration laboratory and users. In 2018, the Association for Nuclear Technology in Medicine (ANTM) has started a separated calibration organization. 
Methods: The main equipment used in calibration system are standard electrometer and standard electric charge source. The standard electrometer self-calibrates the sensitivity with a standard capacitor and a DC voltage source inserted in the negative feedback circuit of the electrometer. Both the standard capacitor and the DC voltage source are calibrated by the National Metrological Institute of Japan. The standard charge source was assembled from a DC current generator and a current shutter controlled by a timer. This charge source can be calibrated by reading the charge generated with the standard electrometer.
Results: The calibration coefficient of user’s electrometer, kelec is determined using charges supplied from standard charge source and readings of electrometer. The uncertainty of kelec is 0.078% in the range of 2-200 nC. In the calibration of user’s ionization chamber, the chamber is installed in the gamma ray standard field and connected to the standard electrometer. The water absorbed dose calibration coefficient, ND,w is decided by comparing the standard field output with the standard electrometer reading. 
Conclusions: In Japan, it has been possible to calibrate the ionization and electrometer separately. The improvement of uncertainty and redundancy are expected in therapeutic lever dosimetry., 18th Asia-Oceania Congress of Medical Physics (AOCMP) & 16th South-East Asia Congress of Medical Physics (SEACOMP)},
 title = {A separated calibration system for therapy level dosimeter by ANTM},
 year = {2018}
}