The preliminary studies on production of Pd-103 therapeutic isotope at the U-120 cyclotron

All the radioisotopes used in nuclear medicine are produced artificially using either a nuclear reactor or a cyclotron. By attaching suitable chemical labels to the radioisotopes, radiopharmaceuticals are obtained, which can be made to seek a desired organ by taking part in the metabolic processes. When radiopharmaceuticals are injected into the human body and specifically taken up by an organ of choice, a lack of uptake, or delay in uptake, denotes loss of function in the organ. Therapeutic radioisotopes are used in a range of different techniques and which can be divided into teletherapy, brachytherapy or radiopharmaceutical methods. Although the majority of the radioisotopes used in nuclear medicine have been produced from research reactors for over 45 years and the methods are generally well established, several new initiatives and developments have occurred recently. One example is 103 Pd which is one of the few accelerator generated isotopes to be in common use for therapy, in this case as a short-lived isotope for permanent implant treatment of prostate cancer. Historically, 103 Pd used to be generated via the 102 Pd(n,γ)103 Pd reaction which relied on the availability of 1% naturally abundant 102 Pd in an enriched form and its moderately high neutron capture cross section. However this method would not produce sufficient amounts of this short-lived isotope, which needed regular, supply cycle of 2-4 weeks. So a new method was devised based on the reaction 103 Rh(p,n)103 Pd by using the accelerators with rather low energy protons (8-18 MeV). Starting with 1987 the encapsulated 103 Pd source became commercially available in the USA, where a company now operates more than 10 dedicated accelerators to produce this nuclide. Recently a manufacturer in Europe also brought his patent type of 103 Pd seed implants to the world market. The primary objective of the present Project is to extend the related applications for radioisotope production of our U-120 Cyclotron (p, d, 14 MeV max. energy). The preliminary experiment were made using the stacked foil activation technique. Four stacks containing high purity 25 μm thick Rh foils were irradiated in the external beam of the U-120 Cyclotron. The incident energy of protons was 14 MeV. The X-ray complexes of the de-excitation of the 103 Rh daughter nuclei (Kα and Kβ) and the 39.7 keV γ-line were analyzed. Specific technologies will be developed for the construction materials used in production target, target chemistry, the transport and interaction of particle beams and irradiation conditions. The existing technology in the world for the electrodeposition of Rh onto metal plates (Cu, Al etc.) and chemical removal of Rh, the electroplating of Pd on graphite sheet or an adsorption of Pd on a resin will be studied also. It is also expected that using theoretical and experimental investigation carried out in the framework of this project, the existing knowledge related to the cross-section and yield of nuclear reactions: 103 Rh(p,n) 103 Pd and 103 Rh(d,2n)103 Pd well be extended. A special attention will be paid to the collaboration between our institute and medical research centers in order to perform, for the first time in our country, this 103 Pd clinical using and to establish the standard procedures for its uses. 103 Pd is a short-lived radioisotope and therefore is very difficult to obtain it from other countries. The production cost of this isotope will be an important aspect. The research will be finalized with quality assurance (QA) procedure standards. According to specific objectives mentioned above, the work plan for this project is the following: A) Design and adaptation of a dedicated beam line at IFIN-HH Cyclotron for the 103 Pd experiments; B) Experiments to choose the optimum beam parameters and to select between proton and deuteron beams; C) Experiments to chose and optimise the target and irradiation conditions; D) Experiments to establish the procedures for the post irradiation characterization of the 103 Pd radioisotope according to the radiobiological rules and the requests of medical specialists. This project is partially financed by IAEA Vienna. (authors)