Treatment planning comparison of volumetric modulated arc therapy with the trilogy and the Halcyon for bilateral breast cancer

Purpose To compare radiotherapy plans between an O‐ring and a conventional C‐arm linac for hypofractionated high‐dose prostate radiotherapy in terms of plan quality, dose distribution, and quality assurance in a multi‐vendor environment. Methods Twenty prostate cancer treatment plans were irradiated on the O‐ring Varian Halcyon linac and were re‐optimized for the C‐arm Elekta Synergy Agility linac. Dose‐volume histogram metrics for target coverage and organ at risk dose, quality assurance, and monitor units were retrospectively compared. Patient‐specific quality assurance with ion chamber measurements, gamma index analysis, and portal dosimetry was performed using the Varian Portal Dosimetry system and the ArcCHECK® phantom (Sun Nuclear Corporation). Prostate‐only radiotherapy was delivered with simultaneous integrated boost (SIB) volumetric modulated arc therapy (VMAT) in 20 fractions of 2.5/3.0 Gy each. Results For both linacs, target coverage was excellent and plan quality comparable. Homogeneity in PTVBoost was high for Synergy as well as Halcyon with a mean homogeneity index of 0.07 ± 0.01 and 0.05 ± 0.01, respectively. Mean dose for the organs at risk rectum and bladder differed not significantly between the linacs but were higher for the femoral heads and penile bulb for Halcyon. Quality assurance showed no significant differences in terms of ArcCHECK gamma pass rates. Median pass rate for 3%/2 mm was 99.3% (96.7 to 99.8%) for Synergy and 99.8% (95.6 to 100%) for Halcyon. Agreement between calculated and measured dose was high with a median deviation of −0.6% (−1.7 to 0.8%) for Synergy and 0.2% (−0.6 to 2.3%) for Halcyon. Monitor units were higher for the Halcyon by approximately 20% (p < 0.001). Conclusion Hypofractionated high‐dose prostate cancer SIB VMAT on the Halcyon system is feasible with comparable plan quality in reference to a standard C‐arm Elekta Synergy linac.

Section: Discussionsupporting

confidence: 82%

Section: Discussionmentioning

confidence: 86%

Comparison of treatment plans for hypofractionated high‐dose prostate cancer radiotherapy using the Varian Halcyon and the Elekta Synergy platforms

Tamihardja

Razinskas

Exner

et al. 2021

“…This double‐staggered MLC has an effective leaf resolution of 5 mm. Several studies have compared the plan quality between a Halcyon and a TrueBeam, which comprises 40 central leaf pairs with a width of 5 mm and 20 peripheral leaf pairs with a width of 10 mm 9,10 . These studies have found that the Halcyon could provide a plan quality similar to that of the TrueBeam for VMAT techniques.…”

Section: Discussionmentioning

confidence: 99%

Effect of the simulated half leaf width of a multileaf collimator on volumetric modulated arc therapy plan quality in hippocampal avoidance whole‐brain radiotherapy

Chen

Chang

et al. 2022

Whole-brain radiotherapy (WBRT) is commonly used in patients with multiple brain metastases. Compared with conventional WBRT, hippocampal avoidance WBRT (HA-WBRT) more favorably preserves cognitive function and the quality of life. The hippocampal volume is considerably small (approximately 3.3 cm 3 ). Therefore, downsizing the leaf width of a multileaf collimator (MLC) may provide higher spatial resolution and better plan quality. Volumetric modulated arc therapy (VMAT) could simulate the half MLC leaf width through couch shifting between arcs. This study investigated changes in VMAT quality for HA-WBRT with a simulated fine MLC leaf width. Methods: We included 18 patients with brain metastasis. All target and avoidance structures were contoured by an experienced radiation oncologist. The prescribed dose was 30 Gy in 10 fractions. For each patient, three different treatment plans were generated for comparison: VMAT with couch-shift, VMAT without couch-shift, and TomoTherapy. All treatment plans fulfilled Radiation Therapy Oncology Group (RTOG) 0933 criteria for HA-WBRT. The Wilcoxon paired signed-rank test was used to compare different treatment plans. Results: VMAT with couch-shift had the better average conformity index (0.823) with statistically significant difference compared to VMAT without couch-shift (0.810). VMAT with couch-shift (0.219) had a more favorable average homogeneity index (HI) than did VMAT without couch-shift (0.230), although the difference was not significant. TomoTherapy had an optimal average HI of 0.070. In terms of the hippocampus, all three treatment plans met the RTOG 0933 criteria. VMAT with couch-shift had a lower average D max (15.2 Gy) than did VMAT without couch-shift (15.3 Gy, p = 0.071) and TomoTherapy (15.5 Gy, p = 0.133). The average D 100% of hippocampus was the same for both VMAT with and without couch-shift (8.5 Gy); however, TomoTherapy had a lower average D 100% value of 7.9 Gy. The treatment delivery time was similar between VMAT with and without couch-shift (average, 375.0 and 369.6 s, respectively). TomoTherapy required a long average delivery time of 1489.9 s. Conclusion:The plan quality of VMAT for HA-WBRT was improved by using the couch-shift technique to simulate the half MLC leaf width. However, the improvement was not statistically significant except conformity index. The downsizing This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

“…Some studies have compared dosimetric differences between plans of breast cancer with those of Halcyon TM and other conventional linac. Sun et al compared the dosimetric difference between different arc plans with Halcyon TM and Trilogy, 20 with the prescription dose of 50 Gy per 25 fractions to the PTV. For the heart, Halcyon TM 4arc-plans reduced the V 30Gy value; however, D mean increased compared with Trilogy 8arc-plans (V 30Gy = 0.8% ± 0.5%, 1.8 ± 1.7%; D mean = 5.6 ± 0.6, 3.9 ± 1.1 Gy).…”

Section: Discussionmentioning

confidence: 99%

Dosimetric comparison of VitalBeam^® and Halcyon^TM 2.0 for hypofractionated VMAT with simultaneous integrated boost treatment of early‐stage left‐sided breast cancer

Heo

Park

et al. 2021

This study compared the quality of treatment plans for early-stage, left-sided breast cancer, as planned for and delivered by the Halcyon TM and VitalBeam ® . Materials and methods: Fifteen patients diagnosed with early-stage leftsided breast cancer, who had received VMAT with hypofractionated SIB, were recruited. All cases were planned using Halcyon TM comprising a dual-layer MLC (DL-MLC) and VitalBeam ® with a Millennium 120 MLC (VB-MLC). For the PTVs, the quality of coverage (QC), conformity index (CI), and homogeneity index (HI) were calculated for each plan. The dosimetric differences between the two treatment plans were statistically compared using the Wilcoxon signed-rank test (p < 0.05). To evaluate delivery efficiency, the average delivery time for each patient's treatment plan was recorded and compared. Results: For the PTVs, the two plans (DL-MLC and VB-MLC) were comparable in terms of the QC, CI, and HI. However, V 30Gy and D mean for the heart in the DL-MLC plan were significantly reduced by 0.49% and 14.6%, respectively, compared with those in the VB-MLC plan (p < 0.05). The D mean value for the ipsilateral lung in the DL-MLC plan significantly decreased by 5.5%, compared with that in the VB-MLC plan (p < 0.05). In addition, the delivery times for the DL-MLC and VB-MLC plans were 79 ± 10 and 101 ± 11 s, respectively. Conclusions: DL-MLC plans were found to improve OAR sparing. In particular, when treating left-sided breast cancer via DL-MLC plans,the risk of heart toxicity is expected to be reduced. K E Y W O R D S dosimetric comparison, Halcyon TM , left-sided breast cancer, VitalBeam® INTRODUCTIONBreast cancer is the most commonly diagnosed cancer in women worldwide. The American Cancer Society estimated that there were 2 261 410 new femaleThis is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.