Infra-fraction motion of the prostate was recorded during 721 fractions of image guided radiotherapy (IGRT) in 28 patients, 14 of which were treated by intensity modulated radiation therapy (IMRT), and 14 of which were treated by volumetric arc therapy (VMAT).

The prostate was imaged by three-dimensional and time-resolved transperineal ultrasound (4D-US) of type Elekta Clarity. The prostate volume was registered and the prostate position (center of volume) was recorded at a frequency of 1.6 samples per second. This raw data set contains a total of 380.199 prostate and patient couch positions over a time span of 5 hours, 47 minutes and 29 seconds of life radiotherapy as exported by the instrument software.