Technetium-99m (99mTc) pertechnetate is a radioisotope that may be attached to various substrates for use in bone scanning. It may be used to label polyphosphate (rarely used today), diphosphonate 1).
Technetium-99m is a metastable nuclear isomer of technetium-99 (itself an isotope of technetium), symbolized as 99mTc, that is used in tens of millions of medical diagnostic procedures annually, making it the most commonly used medical radioisotope.