@article{RichterPolatLawrenzetal.2016, author = {Richter, Anne and Polat, B{\"u}lent and Lawrenz, Ingulf and Weick, Stefan and Sauer, Otto and Flentje, Michael and Mantel, Frederick}, title = {Initial results for patient setup verification using transperineal ultrasound and cone beam CT in external beam radiation therapy of prostate cancer}, series = {Radiation Oncology}, volume = {11}, journal = {Radiation Oncology}, number = {147}, doi = {10.1186/s13014-016-0722-7}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-147677}, year = {2016}, abstract = {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.}, language = {en} } @article{ToussaintRichterManteletal.2016, author = {Toussaint, Andr{\´e} and Richter, Anne and Mantel, Frederick and Flickinger, John C. and Grills, Inga Siiner and Tyagi, Neelam and Sahgal, Arjun and Letourneau, Daniel and Sheehan, Jason P. and Schlesinger, David J. and Gerszten, Peter Carlos and Guckenberger, Matthias}, title = {Variability in spine radiosurgery treatment planning - results of an international multi-institutional study}, series = {Radiation Oncology}, volume = {11}, journal = {Radiation Oncology}, number = {57}, doi = {10.1186/s13014-016-0631-9}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-146687}, year = {2016}, abstract = {Background The aim of this study was to quantify the variability in spinal radiosurgery (SRS) planning practices between five international institutions, all member of the Elekta Spine Radiosurgery Research Consortium. Methods Four institutions provided one representative patient case each consisting of the medical history, CT and MR imaging. A step-wise planning approach was used where, after each planning step a consensus was generated that formed the basis for the next planning step. This allowed independent analysis of all planning steps of CT-MR image registration, GTV definition, CTV definition, PTV definition and SRS treatment planning. In addition, each institution generated one additional SRS plan for each case based on intra-institutional image registration and contouring, independent of consensus results. Results Averaged over the four cases, image registration variability ranged between translational 1.1 mm and 2.4 mm and rotational 1.1° and 2.0° in all three directions. GTV delineation variability was 1.5 mm in axial and 1.6 mm in longitudinal direction averaged for the four cases. CTV delineation variability was 0.8 mm in axial and 1.2 mm in longitudinal direction. CTV-to-PTV margins ranged between 0 mm and 2 mm according to institutional protocol. Delineation variability was 1 mm in axial directions for the spinal cord. Average PTV coverage for a single fraction18 Gy prescription was 87 ± 5 \%; Dmin to the PTV was 7.5 ± 1.8 Gy averaged over all cases and institutions. Average Dmax to the PRV_SC (spinal cord + 1 mm) was 10.5 ± 1.6 Gy and the average Paddick conformity index was 0.69 ± 0.06. Conclusions Results of this study reflect the variability in current practice of spine radiosurgery in large and highly experienced academic centers. Despite close methodical agreement in the daily workflow, clinically significant variability in all steps of the treatment planning process was demonstrated. This may translate into differences in patient clinical outcome and highlights the need for consensus and established delineation and planning criteria.}, language = {en} } @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{MantelMuellerKleineetal.2021, author = {Mantel, Frederick and M{\"u}ller, Elena and Kleine, Philip and Zimmermann, Marcus and Exner, Florian and Richter, Anne and Weick, Stefan and Str{\"o}hle, Serge and Polat, B{\"u}lent and H{\"o}cht, Stefan and Flentje, Michael}, title = {Chemoradiotherapy by intensity-modulated radiation therapy with simultaneous integrated boost in locally advanced or oligometastatic non-small-cell lung cancer-a two center experience}, series = {Strahlentherapie und Onkologie}, volume = {197}, journal = {Strahlentherapie und Onkologie}, number = {5}, issn = {1439-099X}, doi = {10.1007/s00066-021-01756-7}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-264821}, pages = {405-415}, year = {2021}, abstract = {Purpose Integrating moderate hypofractionation to the macroscopic tumor with elective nodal irradiation while sparing the organs at risk (OAR) in chemoradiotherapy of locally advanced non-small-cell lung cancer. Methods From 2010-2018, treatment, patient and tumor characteristics of 138 patients from two radiation therapy centers were assessed. Chemoradiotherapy by intensity-modulated radiation therapy (IMRT) with a simultaneous integrated boost (SIB) to the primary tumor and macroscopic lymph node metastases was used. Results A total of 124 (90\%) patients received concurrent chemotherapy. 106 (76\%) patients had UICC (Union for International Cancer Control) stage ≥IIIB and 21 (15\%) patients had an oligometastatic disease (UICC stage IV). Median SIB and elective total dose was 61.6 and 50.4 Gy in 28 fractions, respectively. Furthermore, 64 patients (46\%) had an additional sequential boost to the primary tumor after the SIB-IMRT main series: median 6.6 Gy in median 3 fractions. The median cumulative mean lung dose was 15.6 Gy (range 6.2-29.5 Gy). Median follow-up and radiological follow-up for all patients was 18.0 months (range 0.6-86.9) and 16.0 months (range 0.2-86.9), respectively. Actuarial local control rates at 1, 2 and 3 years were 80.4, 68.4 and 57.8\%. Median overall survival and progression-free survival was 30.0 months (95\% confidence interval [CI] 23.5-36.4) and 12.1 months (95\% CI 8.2-16.0), respectively. Treatment-related toxicity was moderate. Radiation-induced pneumonitis grade 2 and grade 3 occurred in 13 (9.8\%) and 3 (2.3\%) patients. Conclusions Chemoradiotherapy using SIB-IMRT showed promising local tumor control rates and acceptable toxicity in patients with locally advanced and in part oligometastatic lung cancer. The SIB concept, resulting in a relatively low mean lung dose, was associated with low numbers of clinically relevant pneumonitis. The overall survival appears promising in the presence of a majority of patients with UICC stage ≥IIIB disease.}, language = {en} } @article{ZimmermannRichterWeicketal.2022, author = {Zimmermann, Marcus and Richter, Anne and Weick, Stefan and Exner, Florian and Mantel, Frederick and Diefenhardt, Markus and Fokas, Emmanouil and Kosmala, Rebekka and Flentje, Michael and Polat, B{\"u}lent}, title = {Acute toxicities of patients with locally advanced rectal cancer treated with intensified chemoradiotherapy within the CAO/ARO/AIO-12 trial: comparing conventional versus VMAT planning at a single center}, series = {Scientific Reports}, volume = {12}, journal = {Scientific Reports}, doi = {10.1038/s41598-022-25647-8}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-301255}, year = {2022}, abstract = {In locally advanced rectal cancer (LARC) neoadjuvant chemoradiotherapy is regarded as standard treatment. We assessed acute toxicities in patients receiving conventional 3D-conformal radiotherapy (3D-RT) and correlated them with dosimetric parameters after re-planning with volumetric modulated arc therapy (VMAT). Patients were randomized within the multicenter CAO/ARO/AIO-12 trial and received 50.4 Gy in 28 fractions and simultaneous chemotherapy with fluorouracil and oxaliplatin. Organs at risk (OAR) were contoured in a standardized approach. Acute toxicities and dose volume histogram parameters of 3D-RT plans were compared to retrospectively calculated VMAT plans. From 08/2015 to 01/2018, 35 patients with LARC were treated at one study center. Thirty-four patients were analyzed of whom 1 (3\%) was UICC stage II and 33 (97\%) patients were UICC stage III. Grade 3 acute toxicities occurred in 5 patients (15\%). Patients with acute grade 1 cystitis (n = 9) had significantly higher D\(_{mean}\) values for bladder (29.4 Gy vs. 25.2 Gy, p < 0.01) compared to patients without bladder toxicities. Acute diarrhea was associated with small bowel volume (grade 2: 870.1 ccm vs. grade 0-1: 647.3 ccm; p < 0.01) and with the irradiated volumes V5 to V50. Using VMAT planning, we could reduce mean doses and irradiated volumes for all OAR: D\(_{mean}\) bladder (21.9 Gy vs. 26.3 Gy, p < 0.01), small bowel volumes V5-V45 (p < 0.01), D\(_{mean}\) anal sphincter (34.6 Gy vs. 35.6 Gy, p < 0.01) and D\(_{mean}\) femoral heads (right 11.4 Gy vs. 25.9 Gy, left 12.5 Gy vs. 26.6 Gy, p < 0.01). Acute small bowel and bladder toxicities were dose and volume dependent. Dose and volume sparing for all OAR could be achieved through VMAT planning and might result in less acute toxicities.}, language = {en} }