Heidelberg 2006 – scientific programme

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ST: Strahlen- und Medizinphysik

ST 11: Verbesserung der Bestrahlungsplanung

ST 11.10: Talk

Tuesday, March 14, 2006, 18:20–18:30, D

Activation Products in Different Brands of Medical Linear Accelerators — •Ben Tabot and Helmut W. Fischer — Universität Bremen, Landesmessstelle für Radioaktivität

A portable high resolution gamma spectrometer was used to determine radioisotopes generated in different brands of medical linear accelerators in the high energy photon mode under clinical irradiation scenarios. The results from the spectroscopic analysis were used to compute the No-dqapparentNo-dq activity at the isocenter and the resulting dose rate. In all accelerators the same isotopes are dominating in terms of dose rate: Al-28 (2.3min), Cu-62 (9.7min), Mn-56 (2.6h), Cu-64 (12.7h) and W-187 (23.8h). The sum of the contributions of all isotopes was calculated from the data and compared to dose rate measurements obtained using a portable dose rate meter. Measured values range from 1.4 to 4.6 uSv/h 2min after beam off for a 400MU irradiation. Calculated values are lower, but show the same behaviour with time. The difference is attributed to beta radiation. Detailed results and conclusions for radiation protection of clinical and service staff will be presented.