Wulff Jörg, Jany David, Zink Klemens
Institut für Medizinische Physik und Strahlenschutz, Fachhochschule Giessen-Friedberg, Wiesenstrasse 14, D-35390 Giessen.
Z Med Phys. 2008;18(3):203-10. doi: 10.1016/j.zemedi.2007.12.005.
The new German DIN 6800-2 (2008) dosimetry protocol introduces a perturbation factor pdelta which accounts for the ionization chamber specific cutoff energy delta in the calculation of the Spencer-Attix stopping-power ratios. Quantitative values are not included in the protocol. In this study the perturbation factor was calculated for different types of ionization chambers using Monte Carlo simulations. For the choice of the cutoff energy the mean chord length of electrons in air filled cavities was calculated in a water phantom and for different beam qualities. The influence of different cutoff energies is not exceeding 0.1% for conventional ionization chambers.
新的德国DIN 6800 - 2（2008）剂量测定协议引入了一个扰动因子pδ，该因子在计算斯宾塞 - 阿蒂克斯阻止本领比时考虑了电离室特定的截止能量δ。该协议中未包含定量值。在本研究中，使用蒙特卡罗模拟计算了不同类型电离室的扰动因子。对于截止能量的选择，在水模体中针对不同的射束质量计算了充气腔体内电子的平均弦长。对于传统电离室，不同截止能量的影响不超过0.1%。
