A method is disclosed for carrying out a positron emission tomography of an examination object in a hybrid system. In N consecutive time intervals, the following is carried out. For n=1 to n=N−1, nth magnetic resonance data and nth positron emission data is acquired in the nth time interval and as a function of this data, nth provisional attenuation correction values and nth provisional positron emission tomographies are determined during the (n+1)th time interval. In the Nth time interval Nth magnetic resonance data and Nth positron emission data is acquired and overall attenuation correction values are determined as a function of the Nth magnetic resonance data and the first to (N−1)th attenuation correction values and also a positron emission tomography is determined as a function of the overall attenuation correction values, the Nth positron emission data and the first to (N−1)th provisional positron emission tomographies.
