Hamm P C, Bakker E J, van den Berg A P, van den Aardweg G J, Visser A G, Levendag P C
Department of Radiation Oncology, University Hospital Rotterdam-Daniel den Hoed Cancer Centre, The Netherlands.
Br J Radiol. 2000 Jul;73(871):762-70. doi: 10.1259/bjr.73.871.11089469.
An experimental brachytherapy model has been developed to study acute and late normal tissue reactions as a tool to examine the effects of clinically relevant multifractionation schedules. Pig skin was used as a model since its morphology, structure, cell kinetics and radiation-induced responses are similar to human skin. Brachytherapy was performed using a microSelectron high dose rate (HDR) afterloading machine with a single stepping source and a custom-made template. In this study the acute epidermal reactions of erythema and moist desquamation and the late dermal reactions of dusky mauve erythema and necrosis were evaluated after single doses of irradiation over a follow-up period of 16 weeks. The major aims of this work were: (a) to compare the effects of iridium-192 (192Ir) irradiation with effects after X-irradiation; (b) to compare the skin reactions in Yorkshire and Large White pigs; and (c) to standardize the methodology. For 192Ir irradiation with 100% isodose at the skin surface, the 95% isodose was estimated at the basal membrane, while the 80% isodose covered the dermal fat layers. After HDR 192Ir irradiation of Yorkshire pig skin the ED50 values (95% isodose) for moderate/severe erythema and moist desquamation were 24.8 Gy and 31.9 Gy, respectively. The associated mean latent period (+/- SD) was 39 +/- 7 days for both skin reactions. Late skin responses of dusky mauve erythema and dermal necrosis were characterized by ED50 values (80% isodose) of 16.3 Gy and 19.5 Gy, with latent periods of 58 +/- 7 days and 76 +/- 12 days, respectively. After X-irradiation, the incidence of the various skin reactions and their latent periods were similar. Acute and late reactions were well separated in time. The occurrence of skin reactions and the incidence of effects were comparable in Yorkshire and Large White pigs for both X-irradiation and HDR 192Ir brachytherapy. This pig skin model is feasible for future studies on clinically relevant multifractionation schedules in a brachytherapy setting.
已开发出一种实验性近距离放射治疗模型，用于研究急性和晚期正常组织反应，作为检验临床相关多分次照射方案效果的工具。猪皮被用作模型，因为其形态、结构、细胞动力学和辐射诱导反应与人类皮肤相似。使用带有单步源和定制模板的微型Selectron高剂量率（HDR）后装治疗机进行近距离放射治疗。在本研究中，在16周的随访期内，对单次照射后的急性表皮反应（红斑和湿性脱屑）和晚期真皮反应（暗紫红色红斑和坏死）进行了评估。这项工作的主要目的是：（a）比较铱-192（192Ir）照射与X线照射后的效果；（b）比较约克郡猪和大白猪的皮肤反应；（c）规范方法。对于皮肤表面100%等剂量的192Ir照射，估计基底膜处的95%等剂量，而80%等剂量覆盖真皮脂肪层。约克郡猪皮肤经HDR 192Ir照射后，中度/重度红斑和湿性脱屑的ED50值（95%等剂量）分别为24.8 Gy和31.9 Gy。两种皮肤反应的相关平均潜伏期（±标准差）均为39±7天。暗紫红色红斑和真皮坏死的晚期皮肤反应的ED50值（80%等剂量）分别为16.3 Gy和19.5 Gy，潜伏期分别为58±7天和76±12天。X线照射后，各种皮肤反应的发生率及其潜伏期相似。急性和晚期反应在时间上有很好的区分。对于X线照射和HDR 192Ir近距离放射治疗，约克郡猪和大白猪的皮肤反应发生情况和效应发生率相当。这种猪皮模型对于未来在近距离放射治疗环境中研究临床相关多分次照射方案是可行的。
