Separation of ^44mSc/^44gSc Nuclear Isomers Based on After-Effects

44gSc presents a particular interest for application in nuclear medicine for positron emission tomography (PET) due to its favorable nuclear decay properties (t1/ 2 = 3.97 h, Emax = 1.47 MeV, branching ratio 94.3% ss+). Its nuclear isomer 44mSc (t1/ 2 = 58.61 h) decays by isomeric transition (IT) into 44gSc, accompanied by approximate to 12% of conversion electron emission, which can cause a partial release of the daughter 44gSc from the chelate complex. A 13 MeV cyclotron at TRIUMF was used to produce both 44mSc and 44gSc via the natCa(p,n)44m,gSc reaction. A 44mSc/44gSc generator was designed by using a Strata C-18E cartridge. After several tested systems, a successful separation method was developed using DOTATOC as a chelator, a Strata C-18E cartridge as a generator column, and an elution solution of 0.1 M NH4-a-HIB. The yield of the generator with the daughter 44gSc release was equal to 9.8 +/- 1.0% (or approximate to 80% per portion of conversion). This result shows the important role of after-effects in the design of radionuclide generators. Nuclear cross-section calculations were applied using the TALYS code to allow for the determination of the most promising alternative routes for 44mSc production, which will enable the development of a full-scale 44mSc/44gSc radionuclide generator based on after-effects.