利用迴旋加速器加速質子，並使其轟擊靶物質以產生核反應，已被廣泛應用於生產人造放射性同位素，其中放射性同位素氟-18可製成各類癌症診斷藥物，因而受到各界矚目。 照射靶的設計對於提升氟-18產率有重大的影響，設計者通常在製作過程中遭遇耐蝕及散熱兩大問題，因氟酸具有很強的腐蝕性，所以必須尋找可抵抗氟酸侵蝕的材料，同時又要考慮材料必須具備良好的熱傳導能力，使照射過程中靶體不致過熱熔毀，但通常現有材料只能滿足其中之一。 本研究旨在設計一個可在高功率條件下，穩定運行的照射靶系統，並且嘗試在銀製靶體內濺鍍一層抗腐蝕的鉭，以期望可以兼得耐蝕與散熱性佳的效果。 經過實際照射實驗後，已證實本研究的照射靶系統可以在總功率1020(W)的條件下穩定地運行，且可達成80%的理論產率，然而濺鍍鉭層在實驗進行中卻發生剝離現象，顯見銀與鉭的結合度不佳，故找尋適當的材料配對將是今後的研究重點。中子通量實驗結果，未能據以判斷靶腔中氧-18水的有無，必須另行實驗才能獲得進一步的結論。 ;The use of cyclotrons to accelerate protons via the bombardment of target substances to produce nuclear reactions has been widely used in the production of artificial radioisotopes, in which the radioisotope fluorine-18 can be made into various types of cancer diagnostic drugs, and thus attracted attention from all walks of life.
The design of the irradiation target has a significant effect on the improvement of the yield of fluorine-18. The designer usually encounters two critical yet conflicting problems during the production process, i.e., corrosion resistance and heat dissipation. Owing to the strong corrosive nature of the fluoric acid, it is necessary to find a target material that is resistant to fluoric acid. In the meantime, a target material should also possess a good heat transfer capability to minimize the overheating phenomenon during the irradiation. However, the existing materials typically cannot meet both requirements simultaneously.
The aim of this study is to design a radiation target system that can operate stably under high power conditions and attempt to sputter a layer of corrosion-resistant tantalum on top of the silver target in an attempt to concurrently achieve good corrosion and heat dissipation.
After the actual irradiation experiment, it has been confirmed that the irradiation target system of this study can run stably under the total power of 1020 (W) and can reach 80% theoretical yield. However, the sputtered tantalum layer undergoes peeling during the irradiation experiment, which clearly indicates the poor adhesion between the silver substrate and sputtered tantalum layer. Therefore, finding the proper intermediate layers to significantly promote the adhesion will be the focus of future research. Neutron flux experiment results, failed to determine the presence of oxygen-18 water in the target cavity, the need for additional experiments in order to obtain further conclusions.
