Photon beam relative dose validation of the DPM Monte Carlo code in lung-equivalent media.
Photon beam relative dose validation of the DPM Monte Carlo code in lung-equivalent media.
复制标题
在肺等效介质中对 DPM 蒙特卡罗代码进行光子束相对剂量验证。
DOI：
10.1118/1.1555671
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发表时间：
2003
期刊：
影响因子：
3.8
通讯作者：
Bielajew,AlexF
中科院分区：
文献类型：
--
作者：
Chetty,IndrinJ;Charland,PauleM;Tyagi,Neelam;McShan,DanielL;Fraass,BenedickA;Bielajew,AlexF
验证实验已经进行了使用6和15 MV光子在不均匀（水/肺/水）介质中的基准的准确性的theDPM蒙特卡罗代码的光子束剂量计算。选择小场尺寸（低至）和低密度介质进行本研究，因为目的是在强调横向电子不平衡效应的条件下测试DPM代码。使用BEAMnrc代码模拟Varian 21 EX直线加速器的治疗头组件，包括钳口（定义射野尺寸为2×2、3×3和10×10）。将相空间文件集成到DPM代码系统中，并将中心轴深度剂量和轮廓计算与均匀水体模中的二极管测量进行比较，以验证相空间。均质体模研究结果表明，DPM计算值与测量值之间的相对误差在±1%以内（基于均方根偏差）的深度剂量曲线;相对轮廓剂量差异平均在±1%/1 mm范围内。使用离子室和胶片进行深度剂量和轮廓测量，在由嵌入固体水中的6 cm肺等效材料板组成的非均匀体模内。对于非均匀体模实验，DPM深度剂量计算值在测量值的±1%范围内（基于均方根偏差）;肺内和肺外深度的相对轮廓差异平均在内部和外部射束区域的±2%范围内，在半影区域的一致距离在1-2 mm范围内。2-3%数量级的相对点差异在估计的实验不确定性范围内。这项工作表明，在横向电子不平衡效应明显的情况下，theDPM蒙特卡罗代码能够准确的光子束剂量计算。
Validation experiments have been conducted using 6 and 15 MV photons in inhomogeneous (water/lung/water) media to benchmark the accuracy of theDPMMonte Carlo code for photon beam dose calculations. Small field sizes (down to and low‐density media were chosen for this investigation because the intent was to test theDPMcode under conditions where lateral electronic disequilibrium effects are emphasized. The treatment head components of a Varian 21EX linear accelerator, including the jaws (defining field sizes of 2×2, 3×3 and 10×10 were simulated using theBEAMnrc code. The phase space files were integrated within theDPMcode system, and central axis depth dose and profile calculations were compared against diode measurements in a homogeneous water phantom in order to validate the phase space. Results of the homogeneous phantom study indicated that the relative differences betweenDPMcalculations and measurements were within ±1% (based on the rms deviation) for the depth dose curves; relative profile dose differences were on average within ±1%/1 mm. Depth dose and profile measurements were carried out using an ion‐chamber and film, within an inhomogeneous phantom consisting of a 6 cm slab of lung‐equivalent material embedded within solid water. For the inhomogeneous phantom experiment,DPMdepth dose calculations were within ±1% (based on the rms deviation) of measurements; relative profile differences at depths within and beyond the lung were, on average, within ±2% in the inner and outer beam regions, and within 1–2 mm distance‐to‐agreement within the penumbral region. Relative point differences on the order of 2–3% were within the estimated experimental uncertainties. This work demonstrates that theDPMMonte Carlo code is capable of accurate photon beam dose calculations in situations where lateral electron disequilibrium effects are pronounced.