In the treatment of head-neck, rectal and lung cancers, modern hybrid imaging based radiotherapy recently showed some promising results. Positron emission tomography computed tomography (PET/CT), used with 18F- fluorodeoxyglucose (18F-FDG) allows to quantify the metabolic activity of a tumor and became a gold standard for diagnosing cancers nowadays. In these multi-modality based radiotreatments, the outcome is strictly related to the accuracy of the tumor volume delineation during the treatment planning. Furthermore, interobserver variability of contouring tumor volumes does not ease the planning process. Of the...

70 patients diagnosed with head and neck cancer and receiving PET/CT based radiotherapy in the Kaposvar University Dept. of Oncoradiology were enrolled in our retrospective study. For all the patients manual and autosegmentation methods were also applied for BTV definition in the ARIA Eclipse Treatment Planning System (TPS) segmentation module. (Fig. 1.) 5 independent observer visually defined BTV and autosegmentation were also performed in all cases. Intra- and interobserver analysiswere applied to define the reliability and accuracy of the different contouring processes. For statistical analysis...

The correlation between the measured BTV volume definitions (each observer, mean of observers, autosegmentational algorithm, referring physician) shown a few (n=21/6) statistically significant differences (p<0,05). (Fig. 2., 3.) The 4th observer made the largest amount of mistakes compared to other observers based on Friedman analysis. Measured volumes of the referring physician significantly correlated with the autosegmentational module (p=0,76). (Fig. 3.)

Integrating the modern hybrid imaging methods into the 3D based radiotherapy has become a standard method. [3] Based on our results the use of autosegmentation technique in BTV definition in a modern TP Systems is a reliable method, but verification of these results is essential. Our interobserver variability data have shown differences in the contoured volumes, but standardization of these results should be a valuable option of BTV definition. Further evaluation is essential to justify these methods.

A. Kedves University of Pecs Faculty of Health Sciences Diagnostical Institute, University of Pecs Faculty of Health Sciences Institute of Health Insurance, Dr. József Baka Diagnostic, Radiation Oncology, Research, and Teaching Center, “Moritz Kaposi” Teaching Hospital, Kaposvar, Hungary Szent Imre street 14/b 7400 Kaposvar, Hungary Phone: + 3682501500 e-mail: [email protected]

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