Yoshiyuki Katsuta1, Noriyuki Kadoya2, Yukio Fujita3, Eiji Shimizu4, Kazuhiro Majima4, Haruo Matsushita5, Ken Takeda6, Keiichi Jingu5. 1. Department of Radiology, Takeda General Hospital, Aizuwakamatsu, Japan; Department of Radiation Oncology, Tohoku University Graduate School of Medicine, Sendai, Japan. 2. Department of Radiation Oncology, Tohoku University Graduate School of Medicine, Sendai, Japan. Electronic address: kadoya.n@rad.med.tohoku.ac.jp. 3. Department of Radiation Oncology, Tokai University Graduate School of Medicine, Isehara, Japan. 4. Department of Radiology, Takeda General Hospital, Aizuwakamatsu, Japan. 5. Department of Radiation Oncology, Tohoku University Graduate School of Medicine, Sendai, Japan. 6. Department of Radiological Technology, Tohoku University Graduate School of Medicine, Sendai, Japan.
Abstract
PURPOSE: The log file-based method cannot display dosimetric changes due to linac component miscalibration because of the insensitivity of log files to linac component miscalibration. The purpose of this study was to supply dosimetric changes in log file-based patient dose calculations for double-arc volumetric-modulated arc therapy (VMAT) in head-and-neck cases. METHODS AND MATERIALS: Fifteen head-and-neck cases participated in this study. For each case, treatment planning system (TPS) doses were produced by double-arc and single-arc VMAT. Miscalibration-simulated log files were generated by inducing a leaf miscalibration of ±0.5 mm into the log files that were acquired during VMAT irradiation. Subsequently, patient doses were estimated using the miscalibration-simulated log files. RESULTS: For double-arc VMAT, regarding planning target volume (PTV), the change from TPS dose to miscalibration-simulated log file dose in Dmean was 0.9 Gy and that for tumor control probability was 1.4%. As for organ-at-risks (OARs), the change in Dmean was <0.7 Gy and normal tissue complication probability was <1.8%. A comparison between double-arc and single-arc VMAT for PTV showed statistically significant differences in the changes evaluated by Dmean and radiobiological metrics (P < 0.01), even though the magnitude of these differences was small. Similarly, for OARs, the magnitude of these changes was found to be small. CONCLUSIONS: Using the log file-based method for PTV and OARs, the log file-based method estimate of patient dose using the double-arc VMAT has accuracy comparable to that obtained using the single-arc VMAT.
PURPOSE: The log file-based method cannot display dosimetric changes due to linac component miscalibration because of the insensitivity of log files to linac component miscalibration. The purpose of this study was to supply dosimetric changes in log file-based patient dose calculations for double-arc volumetric-modulated arc therapy (VMAT) in head-and-neck cases. METHODS AND MATERIALS: Fifteen head-and-neck cases participated in this study. For each case, treatment planning system (TPS) doses were produced by double-arc and single-arc VMAT. Miscalibration-simulated log files were generated by inducing a leaf miscalibration of ±0.5 mm into the log files that were acquired during VMAT irradiation. Subsequently, patient doses were estimated using the miscalibration-simulated log files. RESULTS: For double-arc VMAT, regarding planning target volume (PTV), the change from TPS dose to miscalibration-simulated log file dose in Dmean was 0.9 Gy and that for tumor control probability was 1.4%. As for organ-at-risks (OARs), the change in Dmean was <0.7 Gy and normal tissue complication probability was <1.8%. A comparison between double-arc and single-arc VMAT for PTV showed statistically significant differences in the changes evaluated by Dmean and radiobiological metrics (P < 0.01), even though the magnitude of these differences was small. Similarly, for OARs, the magnitude of these changes was found to be small. CONCLUSIONS: Using the log file-based method for PTV and OARs, the log file-based method estimate of patient dose using the double-arc VMAT has accuracy comparable to that obtained using the single-arc VMAT.
Authors: Hannes A Loebner; Werner Volken; Silvan Mueller; Jenny Bertholet; Paul-Henry Mackeprang; Gian Guyer; Daniel M Aebersold; Marco F M Stampanoni; Peter Manser; Michael K Fix Journal: Med Phys Date: 2022-05-04 Impact factor: 4.506