Chemical radioanalysis of production of positron-emitting radioisotope Gallium-68 via (p,n) and (p,2n) reactions using compact cyclotron for tomography applications

In this study, the proton-induced reactions of 68Zn and 69Ga aimed at generating 68Ga were simulated and modeled using Talys code and neural network software. In the first step, both targets were simulated under different proton energies and at different bombardments times to generate a total of six thousand data. Then, the obtained data from the Talys, including the various cross-sections, contaminations, the main product i.e. 68Ga, and other options were completely saved in the output file. Afterwards, the inputs of the neural network were selected from the output of the Talys by analyzing and considering most of the key features. A total of four inputs, two of which are different energies related to the reaction, the other is the process sequence and the fourth input is the bombardment time, were recognized as suitable inputs and the model was trained differently depending on the type of target. The selected model was a feed-forward neural network with 5 nodes in a middle layer, which was able to estimate the output of Talys code by changing the input parameters with extremely high accuracy. Two different models including the main model for estimating the output of the main sample (product) and the sub-model for estimating process pollution or impurity were trained, and then the trained model was tested on the deduced process data. The implementation results fully demonstrated the high accuracy of the method. The neural network model is much easier to implement than the Talys code, and its execution speed is very high. In addition, it can be used appropriately as a system alternative for optimization and different structures in medical and biological engineering.

Production of medical isotope 68Ge based on a novel chromatography separation technique and assembling of 68Ge/68Ga generator

A double-column chromatography separation technique was involved for isolation of ⁶⁸Ge from a bombarded Ga-Ni alloy target. About 185 MBq ⁶⁸Ge obtained was used for assembling SnO₂-based ⁶⁸Ge/⁶⁸Ga generator. Approximately 70% of ⁶⁸Ga in high radioactivity concentration was eluted from generator with excellent radionuclidic, radiochemical and chemical purity. ⁶⁸Ga was quite adequate for radiolabeling with DOTATATE or PSMA-617 with a high labelling efficiency of >92%. The double-column chromatography technique possessed a potential application prospect of ⁶⁸Ge/⁶⁸Ga production, aiding the development of ⁶⁸Ga in nuclear medicine.

Preparation and evaluation of SnO2-based 68Ge/68Ga generator made from 68Ge produced through (nat)Zn(α,xn) reaction

(68)Ge was produced by (nat)Zn(α,xn)(68)Ge reaction and its production yield was 31.82 kBq/μAh (0.86 μCi/μAh) at the end of irradiation (EOI). A simple chromatographic method using a SnO2 column was employed to separate (68)Ge from the target material and the co-produced non-isotopic radioisotope impurities. (68)Ge retained in the column served as the (68)Ge/(68)Ga generator. Elution efficiency of the column was about 60%. First 2 ml of the eluate contained more than 95% of the elutable activity. Post-elution purification cum concentration was done with a small cation exchange resin column. The presence of the inactive tin ions in the (68)Ga eluate was determined by the ICP-OES technique and was found to be about 0.03 ppm. Radiochemical purity of the final (68)Ga preparation was more than 99.99% and it was found to be suitable for making complex with ethylenediamine-N,N,N',N'-tetrakis(methylene phosphonic acid) (EDTMP).

Long-circulating non-toxic blood pool imaging agent based on hyperbranched polyglycerols

PURPOSE

Currently, in vivo or in vitro(99m)Tc-radiolabelled red blood cells are the standard blood pool imaging agents. Due to risks associated with handling of blood and the problems with the current (99m)Tc shortage, we were interested in a long-circulating biocompatible synthetic macromolecule that would be simple to prepare and could also be used for PET imaging.

METHODS

A high molecular weight hyperbranched polyglycerol (HPG) of 500 kDa was derivatized to coordinate radioactive gallium and to establish its labelling efficiency, stability and pharmacokinetics.

RESULTS

The resulting radiopharmaceutical in kit form was labelled rapidly within a couple of minutes at room temperature, was stable in transferrin and EDTA challenge tests, and was non-toxic in both cell viability and different hemocompatibility assays. A pharmacokinetic biodistribution study showed that the (67)Ga-HPGN was confined to the blood compartment with a biological half life of 50.7h.

CONCLUSION

(67)Ga-HPGN is thus a simple to prepare blood pool imaging agent for applications where a long biological half-life is essential, i.e., the diagnosis of internal bleeding. Since radiolabelling of the same kit with (68)Ga was also confirmed, we plan to evaluate it shortly as a PET blood pool imaging agent for cardiac applications.