Dosimetry of Brachytherapy Sources In Millimeter Range

描述(申请人提供)：最近，放射治疗已被证明是 是预防术后再狭窄的有效治疗方法 血管成形术。在基于导管的血管内近距离放射治疗(IVB)系统中 放射源被放置在距离目标较近的管腔内， 通常为1到3毫米。伽马和贝塔发射器目前都用于IVB。 所有源产生的剂量分布在靶区具有陡峭的剂量梯度 几毫米大小的体积。然而，高能光子 发射体(例如(192)Ir)、低能光子发射体(例如(103)Pd)或Beta 发射体(例如(90)Sr/(90)Y)具有非常不同的剂量学和物理特性 关于深度剂量穿透、衰减效应和 屏蔽要求。基于(192)Ir和(90Sr/90Y)的IVB输出器 已经商业化，基于(103)Pd的一种正在进行中 发展。现在迫切需要获得以下剂量参数： 这些用于确定靶区和靶区剂量分布的系统 周围的卷。有必要修改剂量计算公式 适用于点状间隙的AAPM任务组的第43号 近距离放射治疗来源。提出了一种基于圆柱体的计算公式 坐标，它更适合基于导管的P/B的几何形状 消息来源。此外，迫切需要验证制造商的 使用两种剂量测量的独立调查的剂量数据 和计算。我们建议使用两种独立的剂量测定方法 (辐射变色薄膜和热释光[TL]片剂量学)和蒙特卡罗 计算(ITS、MCNP和EGS4代码)以相互比较各种结果和 获得一组准确的IVB系统剂量学参数。我们的假设 成功实施各种国际年生物多样性系统需要更好的 了解毫米距离的剂量学问题。校长 目的是确定邻近地区的剂量学参数 各种放射性核素(光子发射体和贝塔) 发射器)，并批判性地检查 静脉内引流术预防术后再狭窄的临床应用 血管成形术。该项目的目标是开发优化工具 在靶体积内产生的剂量分布和剂量均匀度 沿着血管和围绕着血管。

DESCRIPTION (provided by applicant): Recently, radiotherapy has been shown to be an effective treatment for the prevention of restenosis following angioplasty. In catheter-based systems for intravascular brachytherapy (IVB) a radioactive source is placed in the lumen at a short distance from the target, typically 1 to 3 mm. Both gamma and beta emitters are currently in use for IVB. All sources produce dose distributions with a steep dose gradient in the target volume with dimensions of a few millimeters. However, high energy photon emitters (e.g. (192)Ir), low energy photon emitters (e.g. (103)Pd) or beta emitters (e.g. ((90)Sr/(90)Y) have very different dosimetric and physical characteristics in terms of depth dose penetration, attenuation effects and shielding requirements. IVB delivery devices based on (192)Ir and (90Sr/90Y) have become commercially available and one based on (103)Pd is under development. There is now a critical need to obtain dosimetry parameters for these systems for the determination of dose distributions in the target and surrounding volumes. There is a need to modify the dose calculation formalism of the AAPM Task Group No. 43, which is suited to point-like interstitial brachytherapy sources. We propose a calculation formalism based on cylindrical coordinates, which is better suited to the geometry of catheter-based P/B sources. Also, there is a critical need to validate the manufacturers' dosimetry data by independent investigations using both dosimetry measurements and calculations. We propose to use two independent dosimetry methods (radiochromic film and thermoluminescent [TL} sheet dosimetry) and Monte Carlo calculations (ITS, MCNP and EGS4 codes) to intercompare various results and obtain an accurate set of dosimetry parameters for IVB systems. Our hypothesis is that successful implementation of the various IYB systems requires a better understanding of dosimetry issues at millimeter distances. The principal objective is to determine the dosimetry parameters in the immediate vicinity (within mm) of the various radionuclides (both photon emitters and beta emitters) and to examine critically the dosimetry issues of importance in the clinical implementation of IVB for prevention of restenosis following angioplasty. The goals of the project are to develop tools for the optimization of dose distributions produced within a target volume and uniformity of dose along and around a blood vessel.