School of Chemistry & Physics, University of Adelaide, South Australia 5005, Australia.
J Appl Clin Med Phys. 2011 Nov 15;12(4):3464. doi: 10.1120/jacmp.v12i4.3464.
The MammoSite radiation therapy system is a novel technique for treatment of patients with early-stage breast cancer. It was developed to overcome the longer schedules associated with external-beam radiation therapy. It consists of a small balloon (4 cm in diameter) connected to an inflation channel and a catheter for the passage of a high dose rate 192Ir brachytherapy source. The device is placed into the tumor resection cavity and inflated with a mixture of saline and radiographic contrast agent to a size that fills the cavity. A high dose rate 192Ir source is driven into the balloon center using a remote afterloader to deliver the prescribed dose at a point 1 cm away from the balloon surface. There are several uncertainties that affect the dose distribution in the MammoSite brachytherapy. They include source position deviation, balloon deformation, and the concentration of the contrast medium inside the balloon. The purpose of this study is to investigate the extent of the dose perturbation for various concentrations of the contrast medium in a MammoSite balloon using Monte Carlo simulations and thermoluminescent dosimetry. This study also combines the impact of these uncertainties on the MammoSite treatment efficacy. The current study demonstrates that the combined uncertainties associated with the MammoSite brachytherapy technique--up to the value of 2 mm balloon deformation, 1 mm source deviation, and 15% contrast concentration--have no impact on the tumor control probability.
MammoSite 放射治疗系统是一种治疗早期乳腺癌患者的新方法。它的开发是为了克服与外部束放射治疗相关的较长时间表。它由一个小气球（直径 4 厘米）连接到一个充气通道和一个用于通过高剂量率 192Ir 近距离放射治疗源的导管组成。该设备被放置在肿瘤切除腔中，并通过生理盐水和造影剂的混合物充气，使其大小填满腔。高剂量率 192Ir 源通过远程后装器驱动到气球中心，以在距离气球表面 1 厘米的位置提供规定的剂量。有几个不确定因素会影响 MammoSite 近距离放射治疗中的剂量分布。它们包括源位置偏差、气球变形和气球内造影剂的浓度。本研究的目的是使用蒙特卡罗模拟和热释光剂量测定法研究各种浓度的造影剂对 MammoSite 气球的剂量扰动程度。本研究还结合了这些不确定性对 MammoSite 治疗效果的影响。本研究表明，MammoSite 近距离放射治疗技术的综合不确定性——高达 2 毫米的气球变形、1 毫米的源偏差和 15%的造影剂浓度——对肿瘤控制概率没有影响。
