Single isocenter SRS using CAVMAT offers improved robustness to commissioning and treatment delivery uncertainty compared to VMAT

Abstract

In this study, we evaluate and compare single isocenter multiple target VMAT (SIMT) and Conformal Arc Informed VMAT (CAVMAT) radiosurgery's sensitivity to uncertainties in dosimetric leaf gap (DLG) and treatment delivery. CAVMAT is a novel planning technique that uses multiple target conformal arcs as the starting point for limited inverse VMAT optimization.Methods: All VMAT and CAVMAT plans were recalculated with DLG values of 0.4, 0.8, and 1.2 mm. DLG effect on V 6Gy [cc], V 12Gy [cc], and V 16Gy [cc], and target dose was evaluated. Plans were delivered to a Delta 4 (ScandiDos, Madison, WI) phantom and gamma analysis performed with varying criteria. Log file analysis was performed to evaluate MLC positional error. Sixteen targets were delivered to a SRS Map-CHECK (Sun Nuclear Corp., Melbourne, FL) to evaluate VMAT and CAVMAT's dose difference (DD) as a function of DLG.Results: VMAT's average maximum and minimum target dose sensitivity to DLG was 9.08 AE3.50%/mm and 9.50 AE 3.30%/mm, compared to 3.20 AE 1.60%/mm and 4.72 AE 1.60%/mm for CAVMAT. For VMAT, V 6Gy [cc], V 12Gy [cc], and V 16Gy [cc] sensitivity was 35.83 AE 9.50%/mm, 34.12 AE 6.60%/mm, and 39.23 AE 8.40%/mm. In comparison, CAVMAT's sensitivity was 23.19 AE 4.50%/mm, 22.45 AE 4.40%/mm, and 24.88 AE 4.90%/mm, respectively. Upon delivery to the Delta 4 , CAVMAT offered superior dose agreement compared to VMAT. For a 1%/1 mm gamma analysis, VMAT and CAVMAT had a passing rate of 94.53 AE 4.40% and 99.28 AE 1.70%, respectively. CAVMAT was more robust to DLG variation, with the SRS MapCHECK plans yielding an absolute average DD sensitivity of 2.99 AE 1.30%/mm compared to 5.07 AE 1.10%/mm for VMAT. Log files demonstrated minimal differences in MLC positional error for both techniques.Conclusions: CAVMAT remains robust to delivery uncertainties while offering a target dose sensitivity to DLG less than half that of VMAT, and 65% of that of VMAT for V 6Gy [cc], V 12Gy [cc], and V 16Gy [cc]. The superior dose agreement and reduced

Pylinac: Image analysis for routine quality assurance in radiotherapy

“…Pylinac has been used widely in literature since its release in 2014, either validation of the algorithms for use by individual clinics (Boudet et al, 2022;Bredikin & Walsh, 2022;Ji & Cong, 2022;Lay, Chuang, Wu, et al, 2022), as a research tool for other ends (Alexander et al, 2021;Al-Kabkabi et al, 2022;Bozhikov et al, 2019;Cullom et al, 2021;Hu et al, 2022;Huang et al, 2021;Mendes et al, 2022;Pant et al, 2020;Pearson et al, 2022;Salari et al, 2023;Tegtmeier et al, 2022;Wang et al, 2020;Wojtasik et al, 2020), or used within other packages (Chuang et al, 2021;Oliver et al, 2022) assurance of IMRT using UNet++: Classification, gamma passing rates prediction, and dose difference prediction. Frontiers in Oncology, 11. https://doi.org/10.3389/fonc.2021.700343…”

Assessing the sensitivity and suitability of a range of detectors for SIMT PSQA

“…• EBT3 and EBT-XD Radiochromic Film 12 (Ashland Specialty Products, Wilmington, Delaware, USA) • Low and high detector-density ion chamber/diode arrays: ⚬ SRS MapCHECK, 13,14 ArcCHECK, 15 and MapCHECK 2 16 (Sun Nuclear Corporation, Melbourne, Florida, USA). ⚬ PTW Octavius, Octavius II, Octavius Detector 1600 SRS 17 PTW Freiburg GmbH, Freiburg, Germany) ⚬ IBA myQA SRS Detector (IBA International, Louvain-La-Neuve, Belgium) • Small-volume ion chambers/diamond detectors (point dose measurements) • Electronic Portal Imaging Device (EPID) based 2D or 3D back projection reconstruction techniques:…”

“…A range of quality assurance (QA) tools are reported for use in the QA of stereotactic ablative body radiotherapy (SABR) and SIMT treatment plans. Some commonly available methods and sample publications are listed below: EBT3 and EBT‐XD Radiochromic Film 12 (Ashland Specialty Products, Wilmington, Delaware, USA) Low and high detector‐density ion chamber/diode arrays: SRS MapCHECK, 13 , 14 ArcCHECK, 15 and MapCHECK 2 16 (Sun Nuclear Corporation, Melbourne, Florida, USA). PTW Octavius, Octavius II, Octavius Detector 1600 SRS 17 PTW Freiburg GmbH, Freiburg, Germany) IBA myQA SRS Detector (IBA International, Louvain‐La‐Neuve, Belgium) Small‐volume ion chambers/diamond detectors (point dose measurements) Electronic Portal Imaging Device (EPID) based 2D or 3D back projection reconstruction techniques: Varían Portal Dosimetry (PD) (Varían Medical Systems, Palo Alto, California, USA) Sun Nuclear 3DVH, PerFRACTION VIPER 18 Calvary Mater Newcastle Hospital, New South Wales, Australia) Polymer Gel dosimetry 19 Machine delivery log files and independent recalculation (Mobius 3D, Varian Medical Systems, Palo Alto, California, USA) 20 , 21 …”

“…SRS MapCHECK, 13 , 14 ArcCHECK, 15 and MapCHECK 2 16 (Sun Nuclear Corporation, Melbourne, Florida, USA).…”

Single isocenter HyperArc treatment of multiple intracranial metastases: Targeting accuracy

“…The introduction of HyperArc (HA) (Varian Medical System, Palo Alto, CA), an automated noncoplanar volumetric modulated arc therapy (VMAT) approach, has generated widespread discussion in the literature 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 on the topic of single‐isocenter stereotactic radiosurgery (SRS) and stereotactic radiotherapy (SRT) of multiple brain metastases. Treatments conducted with a single isocenter have the obvious advantage of reducing treatment time.…”