## 4 Matters in \({}^{68}\)Ga Cyclotron Production
### Expansion of Solid Target \({}^{68}\)Ga Preparations  
The production of radionuclides with solid targets requires technical skills and knowledge, such as target preparation, irradiation, target transport, and dissolution methods. Recent developments, such as the automated target transport and dissolution system allow minimal work, consequently reducing radiation exposure and improving product consistency. For future expansion, a solid [\({}^{68}\)Zn]ZnO target should be commercially available to complement the advances in automated target transport and dissolution systems. Experience suggests that the electroplated target offers a higher EOB yield with less [\({}^{68}\)Zn]ZnO than the foil and pressed target, despite the long and tedious procedure. This would be advantageous for central nuclear pharmacies only if the cost of the commercially available electroplated [\({}^{68}\)Zn]ZnO target was economical. In addition, cassette-based synthesis should be readily available for cost efficiency and reliable production, which minimizes the influence of human error and enables more consistent production [57]. Sustainable Practice in Cyclotron-Produced \({}^{68}\)Ga: [\({}^{68}\)Zn]ZnO Target Reprocessing  
The cost of upgrading the cyclotron to produce \({}^{68}\)Ga radiopharmaceuticals for liquid targets appears to be much lower than that for solid targets, allowing access to and continuity of service, especially in developing countries [58]. Priority should be given to reprocessing the recovered \({}^{68}\)Zn target to maximize resource use and increase cost effectiveness. The investigation of the reprocessing of \({}^{68}\)Zn targets is presented in Table 9. [PERSON] and group [36] and [PERSON] and group [35] reprocessed the recovered \({}^{68}\)Zn with purities up to 99%, the former using a cation exchange resin (AG-50 WX8) and the latter using a drying method. Only minor impurities were detected which shows that reprocessing the recovered \({}^{68}\)Zn target is possible with minimal labor. Further experiments should be performed to evaluate the quality of the irradiated reprocessed \({}^{68}\)Zn. Metal impurities in the [68 Zn]ZnO target affect the EOB and the final product, especially if \({}^{66}\)Ga and \({}^{67}\)Ga are present. Several precautions should be taken to prevent metal contamination of reprocessed [68 Zn]ZnO during pre-processing, processing, and post-processing. In general, the use of metals should be avoided, including contact with metal equipment. As described in Table 10, pre-processing precautions include using trace metal-free water and HNO\({}_{3}\) specifically in the production of [68 Zn]ZnO and any chemicals that come into contact with [68 Zn]ZnO during production. To recover [68 Zn]ZnO, a clean, sterile vial with a coated or plastic needle is preferred. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Step** & & **Preccution Measure** \\ \hline Pre-processing & 1. & Use ultra-trace metal grade water to prepare the [68 Zn]ZnO target. \\  & 2. & Use trace metal grade HNO\({}_{3}\) to prepare for [68 Zn]ZnO target. \\  & 3. & Avoid any contact with metal during the preparation of the [68 Zn]ZnO target. \\  & 4. & Ensure that the chemicals used to capture and purify \({}^{68}\)Ga are trace metal grade. \\  & 5. & Collect the \({}^{68}\)Zn recovery in a clean, sterile vial. \\  & 6. & Never use a metal needle to collect the \({}^{68}\)Zn recovery. \\  & 7. & Clean the target with trace metal grade HNO\({}_{3}\). \\  & 8. & Ensure that the proton irradiation energy does not co-produce \({}^{67}\)Ga via the \({}^{68}\)Zn(p,2n)\({}^{67}\)Ga route. \\ \hline Processing & 1. & Use ultra-trace metal water. \\  & 2. & Use trace metal analysis grade of HNO\({}_{3}\). \\  & 3. & Use clean equipment cleaned with ultrapure water. \\  & 4. & Minimize any contact with metallic equipment for drying or removing moisture. \\ \hline \hline \end{tabular}
\end{table} 
Table 10: Preccution measures to be considered for [68 Zn]ZnO reprocessing.