Alhujaili Sultan Fahad, Biasi Giordano, Alzorkany Faisal, Grogan Garry, Al Kafi Muhammed A, Lane Jonathan, Hug Benjamin, Aldosari Abdullah H, Alshaikh Sami, Farzad Pejman Rowshan, Ebert Martin A, Moftah Belal, Rosenfeld Anatoly B, Petasecca Marco
Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW, Australia.
Radiology and Medical Imaging Department, College of Applied Medical Sciences, Aljouf University, Aljouf, Saudi Arabia.
J Appl Clin Med Phys. 2019 Jan;20(1):76-88. doi: 10.1002/acm2.12496. Epub 2018 Nov 22.
The aim of this work was to evaluate the use of an angularly independent silicon detector (edgeless diodes) developed for dosimetry in megavoltage radiotherapy for Cyberknife in a phantom and for patient quality assurance (QA).
The characterization of the edgeless diodes has been performed on Cyberknife with fixed and IRIS collimators. The edgeless diode probes were tested in terms of basic QA parameters such as measurements of tissue-phantom ratio (TPR), output factor and off-axis ratio. The measurements were performed in both water and water-equivalent phantoms. In addition, three patient-specific plans have been delivered to a lung phantom with and without motion and dose measurements have been performed to verify the ability of the diodes to work as patient-specific QA devices. The data obtained by the edgeless diodes have been compared to PTW 60016, SN edge, PinPoint ionization chamber, Gafchromic EBT3 film, and treatment planning system (TPS).
The TPR measurement performed by the edgeless diodes show agreement within 2.2% with data obtained with PTW 60016 diode for all the field sizes. Output factor agrees within 2.6% with that measured by SN EDGE diodes corrected for their field size dependence. The beam profiles' measurements of edgeless diodes match SN EDGE diodes with a measured full width half maximum (FWHM) within 2.3% and penumbra widths within 0.148 mm. Patient-specific QA measurements demonstrate an agreement within 4.72% in comparison with TPS.
The edgeless diodes have been proved to be an excellent candidate for machine and patient QA for Cyberknife reproducing commercial dosimetry device measurements without need of angular dependence corrections. However, further investigation is required to evaluate the effect of their dose rate dependence on complex brain cancer dose verification.
本研究的目的是评估一种为射波刀兆伏级放射治疗剂量测定而开发的角度独立硅探测器（无边缘二极管）在体模和患者质量保证（QA）中的应用。
使用固定和虹膜准直器在射波刀上对无边缘二极管进行了特性表征。对无边缘二极管探头进行了基本QA参数测试，如组织体模比（TPR）、输出因子和离轴比的测量。测量在水模和水等效体模中进行。此外，已将三个患者特定计划分别在有和没有运动的情况下输送至肺部体模，并进行了剂量测量，以验证二极管作为患者特定QA设备的工作能力。将无边缘二极管获得的数据与PTW 60016、SN边缘、PinPoint电离室、Gafchromic EBT3胶片和治疗计划系统（TPS）进行了比较。
无边缘二极管进行的TPR测量显示，与PTW 60016二极管在所有射野尺寸下获得的数据一致性在2.2%以内。输出因子与经射野尺寸依赖性校正的SN EDGE二极管测量值的一致性在2.6%以内。无边缘二极管的射野轮廓测量与SN EDGE二极管匹配，测量的半高宽（FWHM）在2.3%以内，半值层宽度在0.148毫米以内。患者特定QA测量显示与TPS相比一致性在4.72%以内。
无边缘二极管已被证明是射波刀机器和患者QA的优秀候选者，无需角度依赖性校正即可重现商业剂量测定设备的测量结果。然而，需要进一步研究以评估其剂量率依赖性对复杂脑癌剂量验证的影响。
