TY - JOUR A1 - Treutwein, Marius A1 - Steger, Felix A1 - Löschel, Rainer A1 - Kölbl, Oliver A1 - Dobler, Barbara T1 - The influence of radiotherapy techniques on the plan quality and on the risk of secondary tumors in patients with pituitary adenoma JF - BMC cancer N2 - BACKGROUND: This planning study compares different radiotherapy techniques for patients with pituitary adenoma, including flatness filter free mode (FFF), concerning plan quality and secondary malignancies for potentially young patients. The flatness filter has been described as main source of photon scatter. MATERIAL AND METHODS: Eleven patients with pituitary adenoma were included. An Elekta Synergy™ linac was used in the treatment planning system Oncentra® and for the measurements. 3D plans, IMRT, and VMAT plans and non-coplanar varieties were considered. The plan quality was evaluated regarding homogeneity, conformity, delivery time and dose to the organs at risk. The secondary malignancy risk was calculated from dose volume data and from measured dose to the periphery using different models for carcinoma and sarcoma risk. RESULTS: The homogeneity and conformity were nearly unchanged with and without flattening filter, neither was the delivery time found substantively different. VMAT plans were more homogenous, conformal and faster in delivery than IMRT plans. The secondary cancer risk was reduced with FFF both in the treated region and in the periphery. VMAT plans resulted in a higher secondary brain cancer risk than IMRT plans, but the risk for secondary peripheral cancer was reduced. Secondary sarcoma risk plays a minor role. No advantage was found for non-coplanar techniques. The FFF delivery times were not shortened due to additional monitor units needed and technical limitations. The risk for secondary brain cancer seems to depend on the irradiated volume. Secondary sarcoma risk is much smaller than carcinoma risk in accordance to the results of the atomic bomb survivors. The reduction of the peripheral dose and resulting secondary malignancy risk for FFF is statistically significant. However, it is negligible in comparison to the risk in the treated region. CONCLUSION: Treatments with FFF can reduce secondary malignancy risk while retaining similar quality as with flattening filter and should be preferred. VMAT plans show the best plan quality combined with lowest peripheral secondary malignancy risk, but highest level of second brain cancer risk. Taking this into account VMAT FFF seems the most advantageous technique for the treatment of pituitary adenomas with the given equipment. KW - Adenoma/radiotherapy KW - Age Factors KW - Female KW - Humans KW - Male KW - Pituitary Neoplasms/radiotherapy KW - Radiotherapy Dosage KW - risk factors Y1 - 2020 U6 - https://doi.org/10.1186/s12885-020-6535-y VL - 20 SP - 1 EP - 13 PB - Springer ER - TY - JOUR A1 - Treutwein, Marius A1 - Löschel, Rainer A1 - Hipp, Matthias A1 - Kölbl, Oliver A1 - Dobler, Barbara T1 - Secondary malignancy risk for patients with localized prostate cancer after intensity-modulated radiotherapy with and without flattening filter JF - The Journal of Applied Clinical Medical Physics (JACMP) N2 - Men treated for localized prostate cancer by radiotherapy have often a remaining life span of 10 yr or more. Therefore, the risk for secondary malignancies should be taken into account. Plans for ten patients were evaluated which had been performed on an Oncentra (R) treatment planning system for a treatment with an Elekta Synergy (TM) linac with Agility (TM) head. The investigated techniques involved IMRT and VMTA with and without flattening filter. Different dose response models were applied for secondary carcinoma and sarcoma risk in the treated region and also in the periphery. As organs at risk we regarded for carcinoma risk urinary bladder, rectum, colon, esophagus, thyroid, and for sarcoma risk bone and soft tissue. The excess absolute risk (EAR) was found very similar in the treated region for both techniques (IMRT and VMAT) and also for both with and without flattening filter. The secondary sarcoma risk resulted about one magnitude smaller than the secondary carcinoma risk. The EAR to the peripheral organs was statistically significant reduced by application of the flattening filter free mode concerning the flattening filter as main source of scattered dose. Application of flattening filter free mode can thus support to reduce second malignancy risk for patients with localized prostate cancer. KW - 2ND PRIMARY CANCERS KW - ARC THERAPY VMAT KW - BEAM KW - CARCINOMA KW - flattening filter free KW - IMPACT KW - IMRT KW - localized prostate cancer KW - PHOTON KW - RADIATION-THERAPY KW - RECTAL-CANCER KW - secondary malignancy risk KW - SOFT-TISSUE SARCOMA KW - VMAT Y1 - 2020 U6 - https://doi.org/10.1002/acm2.13088 VL - 21 IS - 12 SP - 197 EP - 205 PB - Wiley ER - TY - GEN A1 - Treutwein, Marius A1 - Hipp, Matthias A1 - Löschel, Rainer A1 - Kölbl, Oliver A1 - Dobler, Barbara T1 - Second cancer risk after radiation of localized prostate cancer with and without flattening filter T2 - Radiotherapy and oncology Y1 - 2017 U6 - https://doi.org/10.1016/S0167-8140(17)32050-9 VL - 123 IS - 1 PB - Elsevier ER - TY - JOUR A1 - Maerz, Manuel A1 - Treutwein, Marius A1 - Nabo, Jan A1 - Dobler, Barbara T1 - Three-dimensional printers applied for the production of beam blocks in total body irradiation treatment JF - Journal of Applied Clinical Medical Physics N2 - Purpose: Total body irradiation (TBI) in extended source surface distance (SSD) is a common treatment technique before hematopoietic stem cell transplant. The lungs are organs at risk, which often are treated with a lower dose than the whole body. Methods: This can be achieved by the application of blocks. Three-dimensional (3D) printers are a modern tool to be used in the production process of these blocks. Results: We demonstrate the applicability of a specific printer and printing material, describe the process, and evaluate the accuracy of the product. Conclusion: The blocks and apertures were found to be applicable in clinical routine. KW - 3D printer KW - electron beam apertures KW - photon beam blocks KW - Radiotherapy KW - STEM-CELL TRANSPLANTATION KW - TBI KW - total body irradiation Y1 - 2022 U6 - https://doi.org/10.1002/acm2.13592 VL - 23 IS - 5 SP - 1 EP - 8 PB - Wiley ER -