Quality assurance and quality control of delivered dose are important in proton therapy. The delivered proton dose is controlled using a dose monitor system which consists of two ionization chambers filled with free air. Response of the monitor for the delivered dose changes under the influence of temperature and pressure of surrounding air. In the dose monitor system at the National Cancer Center Hospital East, the monitor is near an X-tray tube which operates at a high temperature and is frequently used in every patient setup. Therefore the response of the dose monitor changes a lot with the temperature of the X-ray tube. In this report, temperature and pressure influence on the dose monitor was investigated in detail. Furthermore, a new method was presented to correct the monitor response using the real-time data of temperature and pressure at any time for each patient. This method improved the accuracy of delivered dose from 1 to 0.5.
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机译：在质子治疗中，质量保证和给药剂量的质量控制非常重要。输送的质子剂量使用剂量监测系统进行控制，该系统由两个充满自由空气的电离室组成。监测仪对输送剂量的响应在周围空气的温度和压力的影响下变化。在国家癌症中心医院东区的剂量监测系统中，监测器靠近一个 X 托盘管，该 X 托盘管在高温下工作，并且经常用于每个患者设置。因此，剂量监测仪的响应随X射线管的温度而变化很大。在本报告中，详细研究了温度和压力对剂量监测器的影响。此外，提出了一种新方法，利用每个患者随时的温度和压力的实时数据来校正监测仪的反应。该方法将递送剂量的准确性从1%提高到0.5%。
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