Dose escalation to high-risk sub-volumes based on non-invasive imaging of hypoxia and glycolytic activity in canine solid tumors: a feasibility studyReportar como inadecuado




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Radiation Oncology

, 8:262

Radiation Biology and Molecular Radiation Oncology

Abstract

IntroductionGlycolytic activity and hypoxia are associated with poor prognosis and radiation resistance. Including both the tumor uptake of 2-deoxy-2- F-fluorodeoxyglucose FDG and the proposed hypoxia tracer copperIIdiacetyl-bisN-methylsemithio-carbazone Cu-ATSM in targeted therapy planning may therefore lead to improved tumor control. In this study we analyzed the overlap between sub-volumes of FDG and hypoxia assessed by the uptake of Cu-ATSM in canine solid tumors, and evaluated the possibilities for dose redistribution within the gross tumor volume GTV.

Materials and methodsPositron emission tomography-computed tomography PET-CT scans of five spontaneous canine solid tumors were included. FDG-PET-CT was obtained at day 1, Cu-ATSM at day 2 and 3 3 and 24 h pi

GTV was delineated and CT images were co-registered. Sub-volumes for 3 h and 24 h Cu-ATSM Cu3 and Cu24 were defined by a threshold based method. FDG sub-volumes were delineated at 40% FDG40 and 50% FDG50 of SUVmax. The size of sub-volumes, intersection and biological target volume BTV were measured in a treatment planning software. By varying the average dose prescription to the tumor from 66 to 85 Gy, the possible dose boost DB was calculated for the three scenarios that the optimal target for the boost was one, the union or the intersection of the FDG and Cu-ATSM sub-volumes.

ResultsThe potential boost volumes represented a fairly large fraction of the total GTV: Cu3 49.8% 26.8-72.5%, Cu24 28.1% 2.4-54.3%, FDG40 45.2% 10.1-75.2%, and FDG50 32.5% 2.6-68.1%. A BTV including the union ∪ of Cu3 and FDG would involve boosting to a larger fraction of the GTV, in the case of Cu3∪FDG40 63.5% 51.8-83.8 and Cu3∪FDG50 48.1% 43.7-80.8. The union allowed only a very limited DB whereas the intersection allowed a substantial dose escalation.

ConclusionsFDG and Cu-ATSM sub-volumes were only partly overlapping, suggesting that the tracers offer complementing information on tumor physiology. Targeting the combined PET positive volume BTV for dose escalation within the GTV results in a limited DB. This suggests a more refined dose redistribution based on a weighted combination of the PET tracers in order to obtain an improved tumor control.

Electronic supplementary materialThe online version of this article doi:10.1186-1748-717X-8-262 contains supplementary material, which is available to authorized users.

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Autor: Malene M Clausen - Anders E Hansen - Per Munck af Rosenschold - Andreas Kjær - Annemarie T Kristensen - Fintan J McEvo

Fuente: https://link.springer.com/







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