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Abstract

It is well known, that intrafractional tumor motion can be remarkable in prostate and lung radiotherapy, but the clinical impact on single patients and patient populations is still under investigation. In this work, real-time motion data of implanted transponders gathered with an electromagnetic tumor tracking system during two clinical trials performed at dkfz was used for evaluations concerning this matter. For both tumor entities the occurring motion was characterized and quantified, first. Based on this data, investigations for prostate radiotherapy deal with implications of this motion on the size of safety margins and the experimental and computational quantification of dosimetric consequences for individual patients. In this first clinical trial on electromagnetic tumor tracking in lung, analyses focused on the quantification of inter- and intrafractional variations of the transponder geometry due to breathing motion and tumor shrinkage. Additionally, the correlation between internal measured lung tumor motion and external chest motion was assessed. According to our results, we conclude that real-time monitoring of the internal motion is necessary for both tumor entities to enable motion management reducing dosimetric consequences, in particular if a hypofractionated radiotherapy is applied. For lung patients it is additionally required to perform a regular control of internal tumor and transponder geometry through patient imaging.