A preliminary biodistribution study of [^99mTc]sodium pertechnetate prepared from an electron linear accelerator and...

Production of ⁹⁹Mo/^99mTc using an electron linear accelerator (linac) and activated carbon (AC)-based ^99mTc generator (linac-AC) is an alternative approach to the conventional fission production of ⁹⁹Mo/^99mTc. As a preliminary investigation of the clinical applicability of a linac-AC-derived ^99mTc radiopharmaceutical, the biodistribution of linac-AC-derived [^99mTc]sodium pertechnetate ([^99mTc]NaTcO₄) was measured and compared against fission-derived [^99mTc]NaTcO₄ at one time point.

⁹⁹Mo was produced by irradiating nonenriched MoO₃ targets with bremsstrahlung photons generated from 55.5-MeV linac electron beams. ^99mTc was then separated and purified from the ⁹⁹Mo using an AC-based ^99mTc generator. Subsequently, biodistribution of the linac-AC-derived [^99mTc]NaTcO₄ in healthy female Slc:ICR mice (n = 6) was measured by dissection and compared with that of fission-derived [^99mTc]NaTcO₄ (n = 4) at 30 min after injection.

The two types of [^99mTc]NaTcO₄ exhibited similar biodistribution in all the organs and tissues examined: the uptakes of [^99mTc]NaTcO₄ prepared from the linac-AC method and those prepared from the fission method were 138.9 ± 69.9%ID/g and 160.6 ± 49.2%ID/g in the thyroids, respectively, 33.4 ± 5.5%ID/g and 29.4 ± 9.1%ID/g in the salivary glands, respectively, and less than 10%ID/g in blood and all the other organs. No adverse effects were observed in the mice administered with either [^99mTc]NaTcO₄.

The clinical applicability of linac-AC-derived [^99mTc]NaTcO₄ was suggested by its similar biodistribution with fission-derived [^99mTc]NaTcO₄ at one time point. Further biodistribution studies at multiple time points are encouraged to demonstrate the bioequivalence between linac-AC- and fission-derived [^99mTc]NaTcO₄.