Tomographic radionuclide angiography (TRNA) can monitor cardiac function in patients receiving cardiotoxic chemotherapy. Gamma cameras using CZT detectors enable dose reduction and quicker acquisitions. We report 80 patients who underwent a 7-minute TRNA acquisition after injection of 550-MBq Tc-labeled human serum albumin. Data were analyzed full and half. Image quality was not visually decreased. There was no significant difference in left ventricular systolic and diastolic volumes and in left and right ventricular ejection fractions between full and half data acquisitions (P < 0.0001). When injecting half activity, effective dose could be reduced to 1.92 mSv.