73 research outputs found

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

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    INTRODUCTION: Glycolytic activity and hypoxia are associated with poor prognosis and radiation resistance. Including both the tumor uptake of 2-deoxy-2-[(18) F]-fluorodeoxyglucose (FDG) and the proposed hypoxia tracer copper(II)diacetyl-bis(N(4))-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 (64)Cu-ATSM in canine solid tumors, and evaluated the possibilities for dose redistribution within the gross tumor volume (GTV). MATERIALS AND METHODS: Positron emission tomography/computed tomography (PET/CT) scans of five spontaneous canine solid tumors were included. FDG-PET/CT was obtained at day 1, (64)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 (64)Cu-ATSM (Cu3 and Cu24) were defined by a threshold based method. FDG sub-volumes were delineated at 40% (FDG40) and 50% (FDG50) of SUV(max). 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 (D( B )) was calculated for the three scenarios that the optimal target for the boost was one, the union or the intersection of the FDG and (64)Cu-ATSM sub-volumes. RESULTS: The 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 D( B ) whereas the intersection allowed a substantial dose escalation. CONCLUSIONS: FDG and (64)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 D( B ). This suggests a more refined dose redistribution based on a weighted combination of the PET tracers in order to obtain an improved tumor control

    Feasibility of using growth band counts in age determination of four crustacean species in the northern atlantic

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    The age information of commercially important species is crucial in fisheries management. Age of various fish and molluscan species has routinely been determined by counting annual growth bands deposited within the hard structures. In crustaceans such structures were previously believed to be lost and replaced due to molting. However, a technique was recently developed to use growth bands deposited in hard structure retained through molting as an age indicator. In the present study, the applicability of the novel technique is investigated for four crustacean species collected from Northern Atlantic for the first time: European lobster, Homarus gammarus (Linnaeus, 1758); Norway lobster, Nephrops norvegieus (Linnaeus, 1758); Atlantic rock crab, Cancer irroratus Say, 1817; and northern shrimp, Pandalus borealis (Kroyer, 1838). The gastric mill ossicles in the first three species were processed to show the growth bands while the eyestalk was used in the shrimp species. Four growth bands were visible in European lobster hatched in a Norwegian hatchery and maintained alive for four years before prior processing. Band counts in the other three species were identical to size-at-age interpretation determined from length-frequency analysis. Validation of the periodicity of annual deposition of growth bands is essential before applying the technique on a wider scale
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