1. A respiration determination apparatus ( 1 ) for determining respiration of a person ( 3 ), the apparatus comprising: a bronchial tree image data set providing unit ( 12 ) for providing a bronchial tree image data set ( 25 ) showing a bronchial tree ( 26 ), a bronchial tree detection unit ( 14 ) for detecting the bronchial tree ( 26 ) in the bronchial tree image data set ( 25 ), a respiratory information determination unit ( 30 ) for determining information about the respiration from the detected bronchial tree ( 26 ).