@article{TreutweinStegerLoescheletal., author = {Treutwein, Marius and Steger, Felix and L{\"o}schel, Rainer and K{\"o}lbl, Oliver and Dobler, Barbara}, title = {The influence of radiotherapy techniques on the plan quality and on the risk of secondary tumors in patients with pituitary adenoma}, series = {BMC cancer}, volume = {20}, journal = {BMC cancer}, publisher = {Springer}, doi = {10.1186/s12885-020-6535-y}, pages = {1 -- 13}, abstract = {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.}, language = {en} } @article{TreutweinLoeschelHippetal., author = {Treutwein, Marius and L{\"o}schel, Rainer and Hipp, Matthias and K{\"o}lbl, Oliver and Dobler, Barbara}, title = {Secondary malignancy risk for patients with localized prostate cancer after intensity-modulated radiotherapy with and without flattening filter}, series = {The Journal of Applied Clinical Medical Physics (JACMP)}, volume = {21}, journal = {The Journal of Applied Clinical Medical Physics (JACMP)}, number = {12}, publisher = {Wiley}, doi = {10.1002/acm2.13088}, pages = {197 -- 205}, abstract = {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.}, language = {en} } @misc{TreutweinHippLoescheletal., author = {Treutwein, Marius and Hipp, Matthias and L{\"o}schel, Rainer and K{\"o}lbl, Oliver and Dobler, Barbara}, title = {Second cancer risk after radiation of localized prostate cancer with and without flattening filter}, series = {Radiotherapy and oncology}, volume = {123}, journal = {Radiotherapy and oncology}, number = {1}, publisher = {Elsevier}, doi = {10.1016/S0167-8140(17)32050-9}, language = {en} } @article{MaerzTreutweinNaboetal., author = {Maerz, Manuel and Treutwein, Marius and Nabo, Jan and Dobler, Barbara}, title = {Three-dimensional printers applied for the production of beam blocks in total body irradiation treatment}, series = {Journal of Applied Clinical Medical Physics}, volume = {23}, journal = {Journal of Applied Clinical Medical Physics}, number = {5}, publisher = {Wiley}, doi = {10.1002/acm2.13592}, pages = {1 -- 8}, abstract = {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.}, language = {en} }