Which isotope is commonly used for calibration in nuclear medicine?

The isotope commonly used for calibration in nuclear medicine is indeed 68Ge. This isotope is particularly valued because it has a well-characterized decay scheme and emits gamma radiation at energies that are convenient for calibration of detectors used in nuclear medicine imaging.

68Ge is often used as a standard for measuring the response of gamma cameras in imaging studies due to its relatively long half-life and consistent emission characteristics. This consistency helps ensure that the calibration remains valid over time, which is crucial for accurate imaging and dosimetry in nuclear medicine.

While the other isotopes mentioned also have important applications in nuclear medicine—such as 99mTc being the most widely used radiopharmaceutical for a variety of scans due to its favorable properties and 201Tl being used in myocardial perfusion imaging—they are not primarily utilized for calibration purposes. 153Sm is used in therapeutic applications for pain relief in metastatic bone cancer but does not serve the same role in calibration as 68Ge.