Moret, Judit Alvarez and Obermeier, Tina and Pohl, Fabian and Loeschel, Rainer and Koelbl, Oliver and Dobler, Barbara (2018) Second cancer risk after radiation therapy of ependymoma using the flattening filter free irradiation mode of a linear accelerator. JOURNAL OF APPLIED CLINICAL MEDICAL PHYSICS, 19 (5). pp. 632-639. ISSN 1526-9914,
Full text not available from this repository. (Request a copy)Abstract
Pediatric patients suffering from ependymoma are usually treated with cranial or craniospinal three-dimensional (3D) conformal radiotherapy (3DCRT). Intensity-modulated techniques spare dose to the surrounding tissue, but the risk for second malignancies may be increased due to the increase in low-dose volume. The aim of this study is to investigate if the flattening filter free (FFF) mode allows reducing the risk for second malignancies compared to the mode with flattening filter (FF) for intensity-modulated techniques and to 3DCRT. A reduction of the risk would be advantageous for treating pediatric ependymoma. 3DCRT was compared to intensity-modulated radiation therapy (IMRT) and volumetric-modulated arc therapy (VMAT) with and without flattening filter. Dose volume histograms (DVHs) were compared to evaluate the plan quality and used to calculate the excess absolute risk (EAR) to develop second cancer in the brain. Dose verification was performed with a two-dimensional (2D) ionization chamber array and the out-of-field dose was measured with an ionization chamber to determine the EAR in peripheral organs. Delivery times were measured. Both VMAT and IMRT achieved similar plan quality in terms of dose sparing in the OAR and higher PTV coverage as compared to 3DCRT. Peripheral dose in low-dose region, which is proportional to the EAR in organs located in this region, for example, gonads, bladder, or bowel, could be significantly reduced using FFF. The lowest peripheral EAR and lowest delivery times were hereby achieved with VMAT(FFF). The EAR calculated based on DVH in the brain could not be reduced using FFF mode. VMAT(FFF) improved the target coverage and homogeneity and kept the dose in the OAR similar compared to 3DCRT. In addition, delivery times were significantly reduced using VMAT(FFF). Therefore, for radiotherapy of ependymoma patients, VMAT(FFF) may be considered advantageous for the combination of Elekta Synergy linac and Oncentra External Beam planning system used in this study.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | FREE PHOTON BEAMS; PHASE-II TRIAL; FRACTIONATED RADIOTHERAPY; INTRACRANIAL EPENDYMOMAS; LOCALIZED EPENDYMOMA; CHILDHOOD EPENDYMOMA; IMRT; CHILDREN; BOMB; DISTRIBUTIONS; children; EAR; ependymoma; flattening filter free; radiation therapy; second cancer risk |
| Subjects: | 600 Technology > 610 Medical sciences Medicine |
| Divisions: | Medicine > Lehrstuhl für Strahlentherapie |
| Depositing User: | Dr. Gernot Deinzer |
| Date Deposited: | 09 Jan 2020 12:44 |
| Last Modified: | 09 Jan 2020 12:44 |
| URI: | https://pred.uni-regensburg.de/id/eprint/13969 |
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