An infusion system may include a radioisotope generator that generates a radioactive eluate via elution, a beta detector, a gamma detector, and a controller. The beta detector and the gamma detector may be positioned to measure beta emissions and gamma emissions, respectively, emitted from the radioactive eluate. In some examples, the controller is configured to calibrate the infusion system using the gamma detector. For example, the controller may generate a radioactive eluate and measure the activity of the radioactive eluate using both the beta detector and the gamma detector. The high accuracy of the activity measured by the gamma detector may be used to calibrate the infusion system. In subsequent use, the infusion system calibrated using the gamma detector may adjust measurements made to monitor and/or control patient infusion procedures.