Second cancer risk after radiation therapy of ependymoma using the flattening filter free irradiation mode of a linear accelerator

URN zum Zitieren dieses Dokuments: urn:nbn:de:bvb:355-epub-376282

Alvarez Moret, Judit, Obermeier, Tina, Pohl, Fabian, Loeschel, Rainer, Koelbl, Oliver und 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 xx (x), S. 1-8.

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Andere URL zum Volltext: http://doi.org/10.1002/acm2.12438, https://aapm.onlinelibrary.wiley.com/doi/abs/10.1002/acm2.12438

Zusammenfassung

Zusammenfassung

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 VMATFFF. The EAR calculated based on DVH in the brain could not be reduced using FFF mode. VMATFFF 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 VMATFFF. Therefore, for radiotherapy of ependymoma patients, VMATFFF may be considered advantageous for the combination of Elekta Synergy linac and Oncentra External Beam planning system used in this study.

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Dokumentenart:

Artikel

Datum:

19 August 2018

Institutionen:

Medizin > Lehrstuhl für Strahlentherapie

Projekte:

Open Access Publizieren (DFG)

Identifikationsnummer:

Wert	Typ
10.1002/acm2.12438	DOI

Stichwörter / Keywords:

children, EAR, ependymoma, ﬂattening ﬁlter free, radiation therapy, second cancer risk

Dewey-Dezimal-Klassifikation:

600 Technik, Medizin, angewandte Wissenschaften > 610 Medizin

Status:

Veröffentlicht

Begutachtet:

Ja, diese Version wurde begutachtet

An der Universität Regensburg entstanden:

Eingebracht am:

24 Aug 2018 10:04

Zuletzt geändert:

24 Aug 2018 10:04

Dokumenten-ID:

37628

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