Cheung Joel Y C, Tang Fuk-hay
Department of Oncology, Princess Margaret Hospital, Hong Kong.
Health Phys. 2007 Oct;93(4):267-72. doi: 10.1097/01.HP.0000264450.81683.51.
Materials with high atomic numbers experience the occurrence of the photoelectric effect when they are irradiated by low energy photons. A short range dose enhancement, due to the dominant photoelectric effect, close to platinum implants (Z = 78) in diagnostic radiography cannot be easily measured experimentally. The enhanced dose may increase the risk for adverse health effects from cancer or may damage vital brain structures close to the high atomic number implants. In the present work, Monte Carlo simulation using the LSCAT version of PRESTA EGS4 was employed to investigate the resulting dose enhancements. The results show that the highest estimated dose enhancement of 79% for brain tissues close to platinum implants was calculated for 65 kV x-ray energy and 180% for 120 kV x-ray energy.
原子序数较高的材料在受到低能光子照射时会发生光电效应。在诊断放射成像中，由于占主导地位的光电效应，靠近铂植入物（Z = 78）处会出现短程剂量增强，这很难通过实验轻易测量。增强的剂量可能会增加患癌症等不良健康影响的风险，或者可能会损害靠近高原子序数植入物的重要脑结构。在本研究中，使用PRESTA EGS4的LSCAT版本进行蒙特卡罗模拟，以研究由此产生的剂量增强情况。结果表明，对于靠近铂植入物的脑组织，在65 kV X射线能量下计算出的最高估计剂量增强为79%，在120 kV X射线能量下为180%。
