Dsouza Rechal Nisha, Sharan Krishna, Sukumar Suresh, Chandraguthi Srinidhi G, Rao Shreekripa, Lewis Shirley, Palaniappan Senthil Manikandan
Department of Radiation Oncology, Manipal College of Health Professions, Manipal Academy of Higher Education, Manipal, Karnataka, India.
Department of Radiation Oncology, Justice K S Hegde Charitable Hospital, Deralakatte, Mangalore, Karnataka, India.
Asian Pac J Cancer Prev. 2025 Apr 1;26(4):1343-1351. doi: 10.31557/APJCP.2025.26.4.1343.
The small fields are used in the treatment of stereotactic radiosurgery (SRS), stereotactic radiotherapy (SRT), and stereotactic body radiation therapy (SBRT). The aim of this study is to compare and assess various small-volume radiation detectors for small-field dosimetry.
The small field dosimetry was performed with the High Definition Versa Linear Accelerator (HD-LINAC) from Elekta. The 6MV flattening filter (FF) and 6MV flattening filter free (FFF) radiation energies were chosen for the measurement. The field sizes of 2x2cm2, 4x4cm2, 5x5cm2, 7x7cm2, 8x8cm2, and 10x10cm2 were selected. The quality assurance (QA) included percentage depth dose (PDD), dose profile measurement, and output factor (OF) measurement. The three radiation detectors, pinpoint ionization chamber type 31014, microDiamond detector type 60019, and Dosimetry diode SRS detector type 60018, from PTW-Freiburg, Germany, were utilized for the dosimetry. The measurements were performed with a radiation field analyzer (RFA) water phantom from PTW Freiburg.
PDD values for all the detectors were similar except for Ds, which increased with the increase in field size in all detectors for the 6MV FF and 6MV FFF beams. Beam profile data gave similar results in all the detectors, with penumbra width having statistically significant differences in the 6MV FF beam between the three detectors. Penumbra width was found lower in pinpoint and microDiamond detectors for both energies compared to the SRS dosimetry diode.
The performance of all the detectors used in this study was similar with less noticeable differences between each other. As there was no great difference found in the results between the detectors, it can be concluded from this study that all three radiation detectors are suitable for the small field dosimetry performed for SRS and SBRT treatments.
小射野用于立体定向放射外科治疗（SRS）、立体定向放射治疗（SRT）和立体定向体部放射治疗（SBRT）。本研究的目的是比较和评估用于小射野剂量测定的各种小体积辐射探测器。
使用医科达公司的高清Versa直线加速器（HD-LINAC）进行小射野剂量测定。选择6MV均整滤过器（FF）和6MV无均整滤过器（FFF）的辐射能量进行测量。选择2×2cm²、4×4cm²、5×5cm²、7×7cm²、8×8cm²和10×10cm²的射野尺寸。质量保证（QA）包括百分深度剂量（PDD）、剂量分布测量和输出因子（OF）测量。使用德国PTW-弗莱堡公司生产的三种辐射探测器，即31014型针点电离室探测器、60019型微钻石探测器和60018型SRS剂量测定二极管探测器进行剂量测定。测量在PTW弗莱堡公司的射野分析仪（RFA）水模体上进行。
除Ds外，所有探测器的PDD值相似，在6MV FF和6MV FFF射束下，所有探测器的Ds均随射野尺寸的增加而增加。所有探测器的射束分布数据结果相似，在6MV FF射束下，三种探测器之间的半值层宽度存在统计学显著差异。与SRS剂量测定二极管相比，两种能量下针点探测器和微钻石探测器的半值层宽度均较低。
本研究中使用的所有探测器性能相似，彼此之间差异不明显。由于探测器之间的结果差异不大，因此本研究可以得出结论，所有三种辐射探测器都适用于SRS和SBRT治疗的小射野剂量测定。
