Jung J, Cho W, Lee J, Kim D, Kim M, Suh T
Department of Biomedical Engineering, Research Institute of Biomedical Engineering, The Catholic University of Korea, Seoul.
Konkuk University Medical Center, Seoul.
Med Phys. 2012 Jun;39(6Part18):3829. doi: 10.1118/1.4735626.
The aim of this study is to evaluate the accuracy the collapsed cone convolution (CCC) algorithm for dose calculation in a radiation treatment planning system (TPS).
We modeled various photon beams for various setup conditions in a radiation treatment planning system (CorePLANTM, Seoul C&J, Korea). The beam models were generated at various set-up conditions such as open beam or wedged beam, 6 MV or 15 MV beam and field sizes from 4×4 cm to 40 × 40 cm . Each beam model was optimized by spectrum modeling from measured percent depth dose (PDD) data, dose profile modeling from a measured profile at a specific depth (10 cm) data. Dose calculation was performed using conventional CCC algorithm. All measured data were acquired from a Clinac 21EX (Varian Medical System, Palo Alto, CA, USA) linear accelerator with the setting of SSD = 100 cm. All calculated PDD and dose profiles at various depths from generated beam models were compared to the measured data.
Calculated dose data from each beam model showed good agreements within 2% of difference to the measured PDD and within 3% dose profiles at various depths. Some regions such as penumbra region at 20 × 20 cm field size and horn region at wedge field showed dose discrepancies over 3%. The results of PDD at all situations showed well agreement with measured data under the 10×10 cm field size. For wedged cases, however, under the 5 cm depths, some inconsistency at penumbra region were appeared.
In this study, we verified the accuracy of CCC algorithm in the TPS. Calculated results by our implemented algorithm was well satisfied with measured dose at small field size (〈20 7 times; 20 cm ). Our next study will perform to compensate theses inconsistencies.
本研究旨在评估放射治疗计划系统（TPS）中用于剂量计算的坍缩圆锥卷积（CCC）算法的准确性。
我们在放射治疗计划系统（CorePLANTM，韩国首尔C&J公司）中针对各种设置条件对不同的光子束进行建模。束模型在多种设置条件下生成，如开野束或楔形束、6兆伏或15兆伏束以及4×4厘米至40×40厘米的射野尺寸。每个束模型通过从测量的百分深度剂量（PDD）数据进行能谱建模、从特定深度（10厘米）处的测量轮廓数据进行剂量分布建模来优化。使用传统的CCC算法进行剂量计算。所有测量数据均从配备SSD = 100厘米设置的Clinac 21EX（美国瓦里安医疗系统公司，帕洛阿尔托，加利福尼亚州）直线加速器获取。将从生成的束模型计算得到的不同深度处的所有PDD和剂量分布与测量数据进行比较。
每个束模型计算得到的剂量数据与测量的PDD相比，在2%的差异范围内显示出良好的一致性，在不同深度处的剂量分布差异在3%以内。一些区域，如20×20厘米射野尺寸下的半影区和楔形野的角区，显示出超过3%的剂量差异。在所有情况下，10×10厘米射野尺寸下PDD的结果与测量数据显示出良好的一致性。然而，对于楔形情况，在5厘米深度下，半影区出现了一些不一致性。
在本研究中，我们验证了TPS中CCC算法的准确性。我们实施的算法计算结果在小射野尺寸（〈20×20厘米）下与测量剂量非常吻合。我们的下一步研究将致力于补偿这些不一致性。
