Direct production of the highly utilized radioisotope 99mTc is a practical approach to self-sufficiency of supply. A TRIUMF-led consortium developed 100Mo coating technology to manufacture high current targets (Schaffer et al., J Nucl Med 2015; 56 Supp. 3: 164) and demonstrated the routine production and purification of 99mTc.
The aim of this work is to implement these processes on an IBA Nirta® target station and Synthera® Extension automated synthesis units. The project was implemented as discrete activities due to the geographical spread of the participants. At TRIUMF 100Mo pellets of 0.9 grams and 12.4 mm diameter were pressed and sintered. Using the method described in Zeisler et al. (http://www.qucosa.de/recherche/frontdoor/?tx_slubopus4frontend[id]=16606) these pellets were bonded to copper alloy backings sized to fit the Nirta® target station. At the Cardiff IBA Cyclone® 18 facility three targets were irradiated at 50 μA and 18 MeV for one hour and three for six hours. Target yields were estimated by measuring the whole target plate in a dose calibrator to obtain a decay curve from which the 99mTc component was extracted. At TRIUMF, separation and purification of 99mTc from 100Mo was carried out using two IBA Synthera® Extension modules. Each unit provides one syringe pump and ten pinch valves. The separation and purification scheme follows that published by Bénard et al (J Nucl Med 2014; 55:1910-1914). Initial testing used a mock solution of a dissolved target with no radioactivity. Parameters were adjusted to minimize the molybdenum content in the final product as measured by colorimetric test strips (LaMotte). When process parameters were optimized the mock dissolved target solution was spiked with 99mTc obtained from a generator. The target appearance was unaffected by irradiation. The decay curve analysis showed 13.5 ± 1.4 GBq of 99mTc for the one hour irradiation and 63 ± 6 GBq for the six hour irradiation, both corrected to EOB. These values are lower than the predicted values of 19 and 87 GBq, respectively, as they do not take into account geometric and self-shielding factors. In the purification tests, molybdenum content of the purified mock target solution was < 0.5 ppm while the mock solution spiked with 99mTc gave a purification efficiency of 98 %.
In conclusion, an IBA Cyclone® 18 equipped with a Nirta® solid target station and two Synthera® Extension automated synthesis units can produce and purify up to 60 GBq of 99mTc pertechnetate in a single 6 hour irradiation.
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