Abstract: The radioisotope of 123I (13.2 h) is widely used in nuclear medicine diagnosis studies using single photon emission computed tomography (SPECT). At present, it is mostly produced by proton irradiation of highly enriched 124Xe in a gas target and based on the decay chain of 123Cs®123Xe®123I. Achievement of high purity and high activity of 123I requires the characterization and the optimization of production conditions such as geometry of gas chamber and optimum range of the projectile particle energy. In this research work, for achieving the maximum purity and high activity, the excitation functions of 124Xe(p, 2n)123Cs, 124Xe(p, pn)123Xe and 124Xe (p, 2p)123I reactions were calculated using five different nuclear models. The theoretical results were compared with the experimental obsetvations. By using the excitation functions, the optimum range of the production was selected. The Monte Carlo method indicated the beam transport situation in the target body and energy distribution of protons in the gas. For this purpose the calculations were carried out by using MCNPX and SRIM codes. Then, the target geometry was designed as a Frustum-shaped. Finally, by means of the MCNPX code, the 123I production yield was estimated. Good agreement between the simulated results and the theoretical yields, as well as the experimental yields was observed.

Keywords: 123I, 124Xe gas, Target design, MCNPX code
J. of Nucl Sci. and Tech 71