A device for locally resolved control of a radiation dose applied with a pulsed particle beam in particle beam therapy, with a processing unit, which is set up to detect continuously a count rate of x-ray quanta measured with a positron emission tomograph and to determine the applied radiation dose from the pattern of the measured count rate, by determining by computation from the measured pattern of the count rate the time intervals, in which an interaction of the particle beam takes place at the application site and by rejecting these time intervals for the determination of the applied radiation dose.