Dosimetry of Brachytherapy Sources In Millimeter Range

描述（由申请人提供）：最近，放射治疗已被证明， 是预防术后再狭窄的有效治疗方法， 血管成形术在用于血管内近距离放射治疗（IVB）的基于导管的系统中， 放射源被放置在离目标较短距离处的管腔中， γ和β发射器目前都用于IVB。 所有源产生的剂量分布在目标中具有陡峭的剂量梯度 体积尺寸为几毫米。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β 发射体（例如（90）Sr/（90）Y）具有非常不同的剂量学和物理特性。 在深度剂量穿透、衰减效应和 屏蔽要求。基于（192）Ir和（90 Sr/90 Y）的IVB输送装置 已经商业上可获得，基于（103）Pd的一种在 发展现在迫切需要获得剂量测定参数， 这些用于确定目标中的剂量分布的系统 周围的体积。需要修改剂量计算形式 AAPM任务组第43号，这是适合点状填隙 近距离放射治疗源我们提出了一个计算形式的基础上圆柱 坐标，更适合基于导管的P/B的几何结构 源此外，还迫切需要验证制造商的 使用两种剂量测定方法进行独立调查获得的剂量测定数据 和计算。我们建议使用两种独立的剂量测定方法 （辐射变色胶片和热释光[TL]片剂量测定）和蒙特卡罗 计算（ITS，MCNP和EGS 4代码），以相互比较各种结果， 获得一套准确的IVB系统剂量测定参数。我们的假设 各种国际生物年系统的成功实施需要一个更好的 了解毫米距离的剂量测定问题。校长 目的是确定附近的剂量学参数 各种放射性核素（光子发射体和β射线）的放射性浓度（mm内） 放射源），并严格审查放射治疗中的重要剂量学问题。 IVB预防术后再狭窄的临床实施 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性 沿着和围绕血管。

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.