gms | German Medical Science

27. Deutscher Krebskongress

Deutsche Krebsgesellschaft e. V.

22. - 26.03.2006, Berlin

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Intracranial arteries as organs at risk in intensity-modulated radiotherapy for skull base tumors

Meeting Abstract

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  • corresponding author presenting/speaker Carsten Nieder - Klinikum rechts der Isar der T.U. München, Deutschland
  • Anca L. Grosu - Klinikum rechts der Isar der T.U. München
  • Sabrina Astner - Klinikum rechts der Isar der T.U. München
  • Raymonde Busch - Klinikum rechts der Isar der T.U. München
  • Peter Kneschaurek - Klinikum rechts der Isar der T.U. München
  • Michael Molls - Klinikum rechts der Isar der T.U. München

27. Deutscher Krebskongress. Berlin, 22.-26.03.2006. Düsseldorf, Köln: German Medical Science; 2006. DocPO267

Die elektronische Version dieses Artikels ist vollständig und ist verfügbar unter: http://www.egms.de/de/meetings/dkk2006/06dkk377.shtml

Veröffentlicht: 20. März 2006

© 2006 Nieder et al.
Dieser Artikel ist ein Open Access-Artikel und steht unter den Creative Commons Lizenzbedingungen (http://creativecommons.org/licenses/by-nc-nd/3.0/deed.de). Er darf vervielfältigt, verbreitet und öffentlich zugänglich gemacht werden, vorausgesetzt dass Autor und Quelle genannt werden.

Gliederung

Text

Purpose: To examine the dose distribution in fractionated stereotacticand intensity-modulated radiotherapy (FSRT, IMRT) of skull base tumors with regard to the large skull base/intracranial arteries.

Methods: Retrospective evaluation, treatment period Sept. 2002 – Nov. 2004,56 patients with skull base tumors adjacent to at least one major artery (which therefore had to be included into the clinical target volume). The strategy for all patients was to perform FSRT by use of a modified linear accelerator (BrainLAB system). The dose per fraction was 1.8 Gy. The planning target volume (PTV) was to be enclosed by the 95% isodose (minimum PTV dose 1.71 Gy). The maximum dose was 107% (1.93 Gy) and dose limits were applied to established organs at risk such as brain stem and optic nerves. The maximum dose to these structures was 1.85 Gy per fraction. No dose limits were defined for the arteries. If FSRT planning failed to meet any of these criteria, IMRT was planned with the same system and objectives. The maximum dose to the internal carotid arteries andbasilar artery was determined retrospectively.

Results: The median PTV was 31 cm3, the median minimum dose to the PTV96%. In 31 patients (55%, median PTV 23 cm3), the FSRT plan fulfilled all evaluation criteria. None of these patients had a dose ≥105% in one of the large arteries. Twenty-five patients (45%, median PTV 39 cm3) had unsatisfactory FSRT plans and needed IMRT planning. This resulted in satisfactory plans in 14/25 (56%, median PTV 35 cm3). However, in 11/25 patients (44%, median PTV 85 cm3) no plan satisfying all our criteria could be calculated. Only in this group of 11 patients, high maximum doses to the vessels were observed. One patient had >110% to one carotid artery and 6 others had 106-110% to one of the large arteries. The median PTV of these 7 patients was 121 cm3, the median dose gradient within the PTV 29% (p=0.04 and <0.001, when compared to the 14 patients with satisfactory IMRT plans). Three out of 4 paranasal sinus tumors belonged to this group.

Conclusion: The large arteries should be considered as organs at risk in IMRT planning of skull base tumors if a homogenous dose distribution of 95-107% within the PTV can not be obtained becauseof its size or inclusion of large air cavities.