Harrison R M, Wilkinson M, Rawlings D J, Moore M
Regional Medical Physics Department, Newcastle General Hospital, Newcastle upon Tyne NE4 6BE, UK.
Br J Radiol. 2007 Dec;80(960):989-95. doi: 10.1259/bjr/32814323.
The development of conformal radiotherapy carries with it the implication of an increased number of imaging procedures at various stages throughout the overall treatment, principally for verification at some, or all, of the treatment fractions. This raises the issue of the balance between the benefit of these additional imaging exposures and the associated risk of radiocarcinogenesis arising from them. As such, it is necessary to appreciate the doses to critical organs for which individual carcinogenic risks have been estimated. In this study, doses to these organs have been measured with lithium fluoride thermoluminescence dosimetry loaded in anthropomorphic phantoms and subjected to realistic radiotherapy treatments of the larynx and breast, including concomitant CT and electronic portal imaging exposures associated with localization and verification of these treatments. Even for large numbers of concomitant images of either modality, arising from imaging at every fraction, the leakage and scatter from the radiotherapy itself is shown to dominate the overall organ dose, with imaging procedures generally contributing 5-20% of the total organ dose.
适形放疗的发展意味着在整个治疗的各个阶段需要增加成像程序的数量，主要用于在部分或全部治疗分次中进行验证。这就引发了一个问题，即这些额外的成像照射的益处与由此产生的放射性致癌相关风险之间的平衡。因此，有必要了解已估算出个体致癌风险的关键器官所接受的剂量。在本研究中，通过将氟化锂热释光剂量计置于人体模型中，并对喉部和乳腺进行实际的放射治疗，包括与这些治疗的定位和验证相关的同步CT和电子射野成像照射，来测量这些器官所接受的剂量。即使对于因每次分次成像而产生的大量任何一种模态的同步图像，放疗本身的泄漏和散射也被证明在总体器官剂量中占主导地位，成像程序通常占总器官剂量的5% - 20%。
