Seifert H, Licht N, Leetz H K
Institut für Radiologische Physik, Universitätskliniken des Saarlandes, Homburg/Saar.
Strahlenther Onkol. 1994 Aug;170(8):471-8.
A computerized dosimetry system for calibration of the dose monitor of a medical accelerator was developed with the aim of saving time and reducing errors during measurement and analysis of measured data.
The PC-based part of the programme system controls measurements with dosimeters of type Dosimentor using an interface IF4. After transmission of the measured data to an UNIX-network the other part of the programme system serves as a tool for analysis. That means in particular the calculation of the absorbed dose in water per monitor unit and the conversion of measured data to basic data for treatment planning.
In the case of the compact ionization chamber M233641 the relative uncertainty of the monitor calibration amounts to 3.5% and 3.3% for photons and electrons, respectively. Using the flat ionization chamber of Markus type M23343 for measuring electrons a relative measuring uncertainty of 2.1% results.
For high-energy photons and electrons with energies above 10 MeV the greatest contribution to the relative uncertainty of the monitor calibration is caused by the uncertainty of the calibration factor for the compact ionization chamber M233641. If it is possible to reduce this error to a value of 2% the relative measuring uncertainty would be smaller than 3%. In the case of high-energy electrons it can be concluded that the precision of the monitor calibration is higher with a flat ionization chamber of Markus type M23343 than with a compact ionization chamber M233641.
开发一种用于校准医用加速器剂量监测器的计算机剂量测定系统，旨在节省测量时间并减少测量数据的分析误差。
程序系统基于PC的部分通过IF4接口控制使用Dosimentor型剂量计的测量。将测量数据传输到UNIX网络后，程序系统的另一部分用作分析工具。这尤其意味着计算每个监测单元在水中的吸收剂量，并将测量数据转换为治疗计划的基础数据。
对于紧凑型电离室M233641，光子和电子的监测器校准相对不确定度分别为3.5%和3.3%。使用Markus型M23343扁平电离室测量电子时，相对测量不确定度为2.1%。
对于能量高于10 MeV的高能光子和电子，紧凑型电离室M233641校准因子的不确定度对监测器校准相对不确定度的贡献最大。如果能够将此误差降低到2%的值，则相对测量不确定度将小于3%。对于高能电子，可以得出结论，Markus型M23343扁平电离室的监测器校准精度高于紧凑型电离室M233641。
