Rao K S
Acta Med Pol. 1989;30(3-4):147-67.
This abstract summarizes the results of a research project undertaken during 1983 to 1985 to evaluate the dose to the surrounding tissue contributed by secondary electrons originating from metallic surgical sutures and total hip prosthesis implanted in human tissue, upon interaction with high energy photons during radiation therapy. To date, no such work, has been undertaken on metallic prostheses or sutures but the effect of breast prosthesis made of silicone gel, during radiation therapy with high energy photons and electrons has been reported in two research papers. In this investigation, film and TLD methods of dosimetry are used to evaluate the dose due to these secondary electrons in a polystyrene phantom. Two types of films are used: they are Dupont 7L and Dupont 6 PLUS. Calibrated beams of X-ray photons of 4 MeV and electrons of 8.6 MeV energy are used as the sources of X-ray photons and electrons. The difference in optical density with film and the difference in response in the case of TLDs with and without the metallic objects is a measure of the dose contributes by the secondary electrons. This dose is taken off from the corresponding calibration curves for film and TLDs and this dose varies from 2.5% to 6.72% to soft tissue and the dose to bone varies from 4% to 12% approximately. In certain clinical situations, this amount of dose could be quite significant. Knowing such contribution, a more effective course of radiation therapy can be planned.
本摘要总结了1983年至1985年期间开展的一项研究项目的结果，该项目旨在评估在放射治疗期间，植入人体组织中的金属手术缝线和全髋关节假体产生的二次电子与高能光子相互作用时，对周围组织造成的剂量。迄今为止，尚未针对金属假体或缝线开展此类研究，但已有两篇研究论文报道了硅胶制成的乳房假体在高能光子和电子放射治疗期间的影响。在本研究中，采用胶片和热释光剂量测定法来评估聚苯乙烯模型中这些二次电子产生的剂量。使用了两种类型的胶片：杜邦7L和杜邦6 PLUS。能量为4 MeV的X射线光子校准束和8.6 MeV的电子校准束用作X射线光子和电子源。胶片光密度的差异以及有和没有金属物体情况下热释光剂量计响应的差异是二次电子贡献剂量的一种度量。该剂量从胶片和热释光剂量计相应的校准曲线中得出，该剂量对软组织的影响在2.5%至6.72%之间，对骨骼的剂量约在4%至12%之间。在某些临床情况下，这一剂量量可能相当可观。了解此类贡献后，可制定更有效的放射治疗方案。
