Gopalakrishnan Zhenia, Nair Raghuram K, Raghukumar P, Menon Sharika V, Bhasi Saju
Division of Radiation Physics, Regional Cancer Centre, Thiruvananthapuram, Kerala, India.
J Med Phys. 2018 Oct-Dec;43(4):264-269. doi: 10.4103/jmp.JMP_112_18.
The aim of this study is to measure and compare the surface dose of treated breast and contralateral breast with the treatment planning system (TPS) calculated dose using calibrated optically stimulated luminescent dosimeter (OSLD) in an indigenous wax breast phantom.
Three-dimensional conformal plans were generated in eclipse TPS v. 13 to treat the left breast of a wax phantom for a prescribed dose of 200 cGy. The plans were calculated using anisotropic analytical algorithm (AAA) and Acuros algorithm with 1-mm grid size. Calibrated OSLDs were used to measure the surface dose of treated and contralateral breasts.
Large differences were observed between measured and expected doses when OSLDs were read in "reading mode" compared to the "hardware mode." The consistency in the responses of OSLDs was better (deviation <±5%) in the "hardware mode." Reasonable agreement between TPS dose and measured dose was found in regions inside the treatment field of treated breast using OSLDs for both algorithms. OSLD measured doses and TPS doses, for the points where the angle of incidence was almost normal, were in good agreement compared to all other locations where the angle of incidence varied from 45° to 70°. The maximum deviation between measured doses and calculated doses with AAA and with Acuros were 2.2% and-12.38%, respectively, for planning target volume breast, and 76% and 77.51%, respectively, for the opposite breast.
An independent calibration factor is required before using the OSLDs for dose measurements. With reference to measured doses using OSLD, the accuracy of skin dose estimation of TPS with AAA was better than with Acuros for both the breasts. In general, a reasonable agreement between TPS doses calculated using AAA and measured doses exists in regions inside treatment field, but unacceptable differences were observed for the points lateral to the opposite breast for both AAA and Acuros.
本研究旨在使用校准后的光激励发光剂量计（OSLD）在自制蜡质乳房体模中，测量并比较经治疗乳房和对侧乳房的表面剂量与治疗计划系统（TPS）计算剂量。
在Eclipse TPS v. 13中生成三维适形计划，以200 cGy的规定剂量治疗蜡质体模的左侧乳房。使用各向异性分析算法（AAA）和Acuros算法，网格大小为1毫米来计算计划。使用校准后的OSLD测量经治疗乳房和对侧乳房的表面剂量。
与“硬件模式”相比，在“读取模式”下读取OSLD时，测量剂量与预期剂量之间存在较大差异。在“硬件模式”下，OSLD的响应一致性更好（偏差<±5%）。使用OSLD对两种算法而言，在经治疗乳房的治疗野内区域，TPS剂量与测量剂量之间存在合理的一致性。与入射角在45°至70°之间变化的所有其他位置相比，对于入射角几乎为法线的点，OSLD测量剂量与TPS剂量吻合良好。对于计划靶体积乳房，使用AAA和Acuros时，测量剂量与计算剂量之间的最大偏差分别为2.2%和 -12.38%，对于对侧乳房分别为76%和77.51%。
在使用OSLD进行剂量测量之前，需要一个独立的校准因子。参照使用OSLD测量的剂量，对于两个乳房，使用AAA的TPS皮肤剂量估计准确性优于使用Acuros的情况。总体而言，使用AAA计算的TPS剂量与治疗野内区域的测量剂量之间存在合理的一致性，但对于AAA和Acuros而言，在对侧乳房外侧的点观察到不可接受的差异。
