@article{TamihardjaRazinskasExneretal.2021,
  author    = {Tamihardja, J{\"o}rg and Razinskas, Gary and Exner, Florian and Richter, Anne and Kessler, Patrick and Weick, Stefan and Kraft, Johannes and Mantel, Frederick and Flentje, Michael and Polat, B{\"u}lent},
  title     = {Comparison of treatment plans for hypofractionated high-dose prostate cancer radiotherapy using the Varian Halcyon and the Elekta Synergy platforms},
  series = {Journal of Applied Clinical Medical Physics},
  volume    = {22},
  journal   = {Journal of Applied Clinical Medical Physics},
  number    = {9},
  doi       = {10.1002/acm2.13380},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-260722},
  pages     = {262-270},
  year      = {2021},
  abstract  = {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.},
  language  = {en}
}
@article{RichterWegenerBreueretal.2021,
  author    = {Richter, Anne and Wegener, Sonja and Breuer, Kathrin and Razinskas, Gary and Weick, Stefan and Exner, Florian and Bratengeier, Klaus and Flentje, Michael and Sauer, Otto and Polat, B{\"u}lent},
  title     = {Comparison of sliding window and field-in-field techniques for tangential whole breast irradiation using the Halcyon and Synergy Agility systems},
  series = {Radiation Oncology},
  volume    = {16},
  journal   = {Radiation Oncology},
  doi       = {10.1186/s13014-021-01942-y},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-265704},
  year      = {2021},
  abstract  = {Background To implement a tangential treatment technique for whole breast irradiation using the Varian Halcyon and to compare it with Elekta Synergy Agility plans. Methods For 20 patients two comparable treatment plans with respect to dose coverage and normal tissue sparing were generated. Tangential field-in-field treatment plans (Pinnacle/Synergy) were replanned using the sliding window technique (Eclipse/Halcyon). Plan specific QA was performed using the portal Dosimetry and the ArcCHECK phantom. Imaging and treatment dose were evaluated for treatment delivery on both systems using a modified CIRS Phantom. Results The mean number of monitor units for a fraction dose of 2.67 Gy was 515 MUs and 260 MUs for Halcyon and Synergy Agility plans, respectively. The homogeneity index and dose coverage were similar for both treatment units. The plan specific QA showed good agreement between measured and calculated plans. All Halcyon plans passed portal dosimetry QA (3\%/2 mm) with 100\% points passing and ArcCheck QA (3\%/2 mm) with 99.5\%. Measurement of the cumulated treatment and imaging dose with the CIRS phantom resulted in lower dose to the contralateral breast for the Halcyon plans. Conclusions For the Varian Halcyon a plan quality similar to the Elekta Synergy device was achieved. For the Halcyon plans the dose contribution from the treatment fields to the contralateral breast was even lower due to less interleaf transmission of the Halcyon MLC and a lower contribution of scattered dose from the collimator system.},
  language  = {en}
}