An outline of separated calibration service currently under development

我が国の治療用線量計の2次校正機関である医用原子力財団では，校正サービスの次のステップとして，電位計と電離箱のそれぞれを単独に校正する分離校正の準備を進めている。分離校正の利点は，校正機関側では，ユーザー電離箱を，高分解能・全自動の標準電位計に接続して校正ができ，電離箱校正に限れば，精度を保ちつつも供給能力が上がることであり，ユーザ側からみれば，故障・修理の際，修理した電位計または電離箱のみを校正依頼できる．電離箱と電位計を自由に組み合わせられる（線量計の冗長性が確保できる）ことなである。現在，校正のための機器の整備および手順確定などがほぼ終了し，平成29年度の校正開始に向け，システムの構築および製品評価技術基盤機構への登録事業者申請および技能試験実施のための準備を進めている

Absorbed dose to water calibration coefficient by types of ionization chambers

Purpose: In Japan, calibration of therapy-level dosimeter with absorbed dose to water have been performed by Association for Nuclear Technology in Medicine (ANTM) as the Secondary Dosimeter Laboratory (SSDL) since 2012. Purpose of this study is to investigate the variation in absorbed dose to water calibration coefficients among chambers of the same type.Results: For shallow type chambers, PTW 34001 is the least variable (1.2% standard deviation. IBA NACP-02 and PTW 23343 chamber exhibit the most variation (3.9% and 4.3% standard deviation) respectively. For almost all types of cylindrical chambers, variations of coefficients are less than those of shallow type chambers. And it is showed that both for cylindrical chamber and for shallow chamber, the smaller collecting volume leads to the more variation of coefficients.Conclusion: Absorbed dose to water calibration coefficient by types of ionization chamber were collected by ANTM. It is found that a tendency of coefficients distribution is different for each chamber type, and small chamber volume leads to more variable of coefficients

External dose audits for high energy X-rays used in radiotherapy by ANTM

In 2007, the Association for Nuclear Technology in Medicine (ANTM) set up an external audit system to check doses of high energy X-rays used in radiotherapy. The audits are based on measurements made with glass dosimeters (GD-302M, Ashahi Technoglass, Co.) that consist of fluorescent glass of rod type. In the audit, glass dosimeters are sent to institution by delivery service according to the request. After the irradiation of certain dose glass dosimeters are returned to ANTM, and the dose given to dosimeter is evaluated at ANTM Dose Calibration Center. The dose is compared with the one stated by the institution, and results of the audit are reported to the institution. Initially, audits by ANTM were limited to outputs of standard condition. However, from 2010, objects of the audit have been expanded to field and wedge conditions. By the end of 2010, 499 beams of 187 treatment machines have been audited by this system. For 320 beams of reference condition the mean and standard deviation of the ratio of doses were 1.043 and 0.0101. In 2010 (the first year of non-reference condition service), the numbers of beams checked with wedge factor and for field factor were 53 and 126, respectively.Japan-Korea Joint Meeting on Medical Physics and 11th Asia-Osecania Congress of Medical Physic