TY - JOUR A1 - Richter, Anne A1 - Polat, Bülent A1 - Lawrenz, Ingulf A1 - Weick, Stefan A1 - Sauer, Otto A1 - Flentje, Michael A1 - Mantel, Frederick T1 - Initial results for patient setup verification using transperineal ultrasound and cone beam CT in external beam radiation therapy of prostate cancer JF - Radiation Oncology N2 - Evaluation of set up error detection by a transperineal ultrasound in comparison with a cone beam CT (CBCT) based system in external beam radiation therapy (EBRT) of prostate cancer. Methods: Setup verification was performed with transperineal ultrasound (TPUS) and CBCT for 10 patients treated with EBRT for prostate cancer. In total, 150 ultrasound and CBCT scans were acquired in rapid succession and analyzed for setup errors. The deviation between setup errors of the two modalities was evaluated separately for each dimension. Results: A moderate correlation in lateral, vertical and longitudinal direction was observed comparing the setup errors. Mean differences between TPUS and CBCT were (−2.7 ± 2.3) mm, (3.0 ± 2.4) mm and (3.2 ± 2.7) mm in lateral, vertical and longitudinal direction, respectively. The mean Euclidean difference between TPUS and CBCT was (6.0 ± 3.1) mm. Differences up to 19.2 mm were observed between the two imaging modalities. Discrepancies between TPUS and CBCT of at least 5 mm occurred in 58 % of monitored treatment sessions. Conclusion: Setup differences between TPUS and CBCT are 6 mm on average. Although the correlation of the setup errors determined by the two different image modalities is rather week, the combination of setup verification by CBCT and intrafraction motion monitoring by TPUS imaging can use the benefits of both imaging modalities. KW - prostate cancer KW - transperineal ultrasound KW - IGRT KW - setup verification KW - cone beam CT Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-147677 VL - 11 IS - 147 ER - TY - JOUR A1 - Tamihardja, Jörg A1 - Razinskas, Gary A1 - Exner, Florian A1 - Richter, Anne A1 - Kessler, Patrick A1 - Weick, Stefan A1 - Kraft, Johannes A1 - Mantel, Frederick A1 - Flentje, Michael A1 - Polat, Bülent T1 - Comparison of treatment plans for hypofractionated high-dose prostate cancer radiotherapy using the Varian Halcyon and the Elekta Synergy platforms JF - Journal of Applied Clinical Medical Physics N2 - 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. KW - acute toxicity KW - dose evaluation KW - Halcyon KW - hypofractionation KW - prostate cancer KW - Synergy Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-260722 VL - 22 IS - 9 ER -