A non-transitory computer-readable medium stores instructions executable by a processor to perform an acquisition and reconstruction method for a first image acquisition device. The method includes determining a scheduled acquisition time based on an attenuation map derived from imaging data from a second image acquisition device and a sensitivity matrix of the first image acquisition device; acquiring emission imaging data using the first image acquisition device, where the acquiring is scheduled to be performed over the scheduled acquisition time; during an initial portion of the acquiring, measuring a count or count rate of the acquired emission imaging data; adjusting the scheduled acquisition time based on the measured count or count rate to generate an adjusted acquisition time while continuing the acquiring; stopping the acquiring at the adjusted acquisition time; and reconstructing the emission imaging data acquired over the adjusted acquisition time to generate one or more reconstructed images.