Ramachandran Prabhakar, Tajaldeen Abdulrahman, Taylor David, Wanigaratne Derrick, Roozen Karl, Geso Moshi
Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia.
Medical Radiation Discipline, School of Health and Biomedical Science, RMIT University, Bundoora, Victoria, Australia.
J Med Phys. 2017 Oct-Dec;42(4):251-257. doi: 10.4103/jmp.JMP_132_16.
The aim of this study is to assess the use of ArcCHECK (AC) as an alternative method to replace film dosimetry for pre-treatment quality assurance (QA) of three-dimensional conformal radiation therapy, intensity-modulated radiation therapy (IMRT), and volumetric-modulated arc therapy (VMAT) stereotactic ablative radiotherapy (SABR) treatment plans.
Twenty-five patients with a varied diagnosis of lung, spine, sacrum, sternum, ribs, scapula, and femur undergoing SABR were selected for this study. Pre-treatment QA was performed for all the patients using ionization chamber and film dosimetry. Measurements were also carried out on an AC phantom. The planned and measured doses from the AC device and EBT3 films were compared using four different gamma criteria: 2%/2 mm, 3%/2 mm, 3%/1 mm, and 3%/3 mm.
The mean gamma passing rates at 3%/3 mm for all non-spine SABR cases were 98.79 ± 0.96 and 99.27 ± 1.03 with AC and films, respectively. The mean passing rates at 3%/2 mm for AC and films were 98.76 ± 0.42 and 99.43 ± 0.27 respectively for spine VMAT SABR, and 87.15 ± 2.45 and 99.79 ± 0.14 respectively for spine IMRT SABR. In the case of spine tumors, the gamma criterion was tightened due to the proximity of spinal cord to the planning target volume. Our results show that AC provides good results for all VMAT SABR plans.
The AC results at 3%/3 mm were in good agreement with film dosimetry for most cases. We observed a significant reduction in QA time on using AC for SABR QA. This study showed that AC results are comparable to film dosimetry for all studied sites except for spine IMRT SABR.
本研究旨在评估使用ArcCHECK（AC）作为替代方法，以取代胶片剂量测定法，用于三维适形放射治疗、调强放射治疗（IMRT）和容积调强弧形治疗（VMAT）立体定向消融放疗（SABR）治疗计划的治疗前质量保证（QA）。
本研究选取了25例接受SABR治疗的患者，其诊断包括肺部、脊柱、骶骨、胸骨、肋骨、肩胛骨和股骨等多种疾病。对所有患者使用电离室和胶片剂量测定法进行治疗前QA。同时也在AC模体上进行测量。使用四种不同的伽马标准（2%/2 mm、3%/2 mm、3%/1 mm和3%/3 mm）比较AC设备和EBT3胶片的计划剂量和测量剂量。
对于所有非脊柱SABR病例，AC和胶片在3%/3 mm时的平均伽马通过率分别为98.79±0.96和99.27±1.03。对于脊柱VMAT SABR，AC和胶片在3%/2 mm时的平均通过率分别为98.76±0.42和99.43±0.27；对于脊柱IMRT SABR，分别为87.15±2.45和99.79±0.14。对于脊柱肿瘤，由于脊髓靠近计划靶体积，伽马标准更为严格。我们的结果表明，AC对于所有VMAT SABR计划都能提供良好的结果。
在大多数情况下，AC在3%/3 mm时的结果与胶片剂量测定法高度一致。我们观察到使用AC进行SABR QA时，QA时间显著缩短。本研究表明，除脊柱IMRT SABR外，AC在所有研究部位的结果与胶片剂量测定法相当。
