Department of Oral and Maxillofacial Radiology, Institute of Health Biosciences, University of Tokushima Graduate School, Japan.
J Radiat Res. 2012;53(1):130-7. doi: 10.1269/jrr.11102. Epub 2012 Jan 6.
A high-dose-rate (HDR) 192-Ir brachytherapy using a customized intraoral mold is effective for superficial oral cavity cancer, and the surrounding normal tissue is kept away from the radioactive source with gauze pads and/or mouth piece for reducing the dose on the normal tissues. In the Tokushima university hospital, the mold has a lead shield which utilizes the space prepared with sufficient border-molding by a specific dental technique using modeling compound. In HDR 192-Ir brachytherapy using a lead shielded customized intraoral mold, there are no reports measuring the absorbed dose. The purpose of the present study is to measure the absorbed dose and discuss the optimum thickness of lead in HDR 192-Ir brachytherapy using a customized intraoral mold with lead shield using a 1 cm thickness mimic mold. The thickness of lead in the mold could be changed by varying the arrangement of 0.1 cm thickness sheet of the acrylic resin plate and lead. The measured doses at the lateral surface of the mold with thermo-luminescence dosimeter were reduced to 1.12, 0.79, 0.57, 0.41, 0.31, 0.24 and 0.19 Gy and the ratios to the prescription dose were reduced to 56, 40, 29, 21, 16, 12 and 10 percent as lead thickness increased from 0 to 0.6 cm in 0.1 cm increments, respectively. A 0.3 cm thickness lead was considered to be required for a 1 cm thickness mold, and it was necessary to thicken the lead as much as possible with the constraint of limited space in the oral cavity, especially at the fornix vestibule.
一种使用定制口腔内模具的高剂量率（HDR）192-Ir 近距离放疗对于表浅口腔癌是有效的，并用纱布垫和/或口塞将周围正常组织与放射源隔开，以减少正常组织的剂量。在德岛大学医院，模具带有一个铅屏蔽，利用特定的牙科技术用模型化合物准备的足够边界成型空间。在使用带铅屏蔽的定制口腔内模具的 HDR 192-Ir 近距离放疗中，尚无测量吸收剂量的报道。本研究的目的是使用带有铅屏蔽的定制口腔内模具（带有 1 cm 厚的模拟模具）测量吸收剂量，并讨论 HDR 192-Ir 近距离放疗中铅的最佳厚度。通过改变厚度为 0.1 cm 的丙烯酸树脂板和铅的排列方式，可以改变模具中的铅厚度。用热释光剂量计测量模具侧面的剂量分别降低到 1.12、0.79、0.57、0.41、0.31、0.24 和 0.19 Gy，与处方剂量的比值分别降低到 56、40、29、21、16、12 和 10%，当铅厚度从 0 增加到 0.6 cm 时，厚度分别增加 0.1 cm。考虑到需要 0.3 cm 厚的铅来制作 1 cm 厚的模具，因此有必要在口腔内有限的空间限制下尽可能增加铅的厚度，特别是在穹窿前庭处。
