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Session: Poster session I
Session starts: Thursday 24 January, 15:00

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Rene Verhaart (Hyperthermia Unit, Department of Radiation Oncology, Daniel den Hoed Cancer Center, Erasmus MC, Groene Hilledijk 301, 3075 EA Rotterdam, The Netherlands)
Valerio Fortunati (Biomedical Imaging Group of Rotterdam, Department of Medical Informatics and Radiology, ErasmusMC, Dr. Molewaterplein 50/60, 3015 GE Rotterdam, The Netherlands)
Jifke Veenland (Biomedical Imaging Group of Rotterdam, Department of Medical Informatics and Radiology, ErasmusMC, Dr. Molewaterplein 50/60, 3015 GE Rotterdam, The Netherlands)
Theo van Walsum (Biomedical Imaging Group of Rotterdam, Department of Medical Informatics and Radiology, ErasmusMC, Dr. Molewaterplein 50/60, 3015 GE Rotterdam, The Netherlands)
Wiro Niessen (Biomedical Imaging Group of Rotterdam, Department of Medical Informatics and Radiology, ErasmusMC, Dr. Molewaterplein 50/60, 3015 GE Rotterdam, The Netherlands)
Gerard van Rhoon (Hyperthermia Unit, Department of Radiation Oncology, Daniel den Hoed Cancer Center, Erasmus MC, Groene Hilledijk 301, 3075 EA Rotterdam, The Netherlands)
Maarten Paulides (Hyperthermia Unit, Department of Radiation Oncology, Daniel den Hoed Cancer Center, Erasmus MC, Groene Hilledijk 301, 3075 EA Rotterdam, The Netherlands)

Abstract:
Introduction In the hyperthermia (HT) unit of the Daniel den Hoed cancer center in Rotterdam an applicator for heating deeply seated head and neck (H&N) tumors has been developed and clinically integrated [1]. The treatment is given to stimulate the effectiveness of the concurrent chemo or radiotherapy treatment. Accurate hyperthermia treatment planning (HTP) is needed to optimize thermal dose delivery. The treatment plan is made patient specific by delineating the tissues in the H&N area by hand. Up to now, the sensitivity of HTP to (inter and intra) observer variations in deliniation was unknown. Methods Three trained medical radiation technologist delineated 17 different tissues on computed tomography (CT) images of 7 patients. The patient group was chosen such that it represents the tumor types normally treated with H&N HT. Inter and intra observer variations were quantified using the Dice similarity coefficient (DC) and the mean distance (MD). The sensitivity of HTP was quantified by determining the two sd error of the average specific absorption rate in the tumor (SARIEEE-1g, tumor) at 1 W input power. Results The inter observer variation (DC: 0.7, MD: 0.8 mm) was higher compared to the intra observer variation (DC: 0.8, MD: 0.5 mm). The two sd error of the average SARIEEE-1g, tumor was 0.015 W/kg at 1 W input power. Conclusion In this sensitivity study, we showed that a variation in tissue delineation leads to a small change in the SARIEEE-1g, tumor. To minimize difference in HTP it is advised to use a well defined delineation protocol. Furthermore, the development of automatic delineation algorithms will minimize HTP differences. Reference [1] Paulides, M.M. et al., Int. J. Hyperthermia, 2007, 23(7):567-576