Production of curie quantities of 68Ga with a medical cyclotron via the 68Zn(p,n)68Ga reaction.

PET imaging with 68Ga-labeled tracers has seen a dramatic increase over the past five years primarily due to the increased accessibility of 68Ge/68Ga generators, the availability of tracers with superb targeting properties for labeling, straightforward labeling procedures and the approval of these tracers by regulatory entities. Available 68Ge/68Ga generators nominally deliver up to 1.85 GBq (50mCi) when fresh limiting production and distribution of 68Ga-labeled tracers to a few daily doses per generator. The focus of this study was to provide a simple and efficient method for 68Ga production in clinically relevant quantities using a low energy medical cyclotron with a solid target.

Target optimization for the photonuclear production of radioisotopes.

In this paper we discuss the optimum shape of a target for photonuclear production of radioisotopes using an electron linear accelerator. Different target geometries such as right cylinder, conical frustum, Gaussian volume of revolution and semi-ellipsoid have been considered for the production of (67)Cu via (68)Zn(γ,p)(67)Cu photonuclear reaction. The specific activity (SA) of (67)Cu was simulated for each target shape. Optimum ratio of radius to height for cylindrical targets was found to be between 0.2 and 0.25 for target masses ranging from 20 g to 100 g. It was shown that while some unconventional target shapes, such as semi-elliptical volume of revolution, result in slightly higher specific activities than cylindrical targets, the advantage is not significant and is outweighed by the complexity of the target production and handling. Power deposition into the target was modeled and the trade-off between the maximization of (67)Cu yield and the minimization of target heating has been discussed. The (67)Cu case can easily be extended for production of many other isotopes.

Evaluation of excitation functions of the (68,67,66)Zn(p,xn)(68,67,66)Ga and 67Zn(p,α)64Cu reactions: validation of evaluated data through comparison with experimental excitation functions of the (nat)Zn(p,x)(66,67)Ga and (nat)Zn(p,x)64Cu processes.

Experimentally available cross section data for formation of the radionuclides (68)Ga, (67)Ga, (66)Ga and (64)Cu in proton induced reactions on enriched (68)Zn, (67)Zn and (66)Zn were evaluated by comparison with the excitation functions calculated by the nuclear model codes, EMPIRE and TALYS, followed by statistical fitting of the selected data. The recommended cross sections were used to obtain the integral yields. The validation of the recommended excitation functions was also attempted by normalization to (nat)Zn and comparison with the experimental data for the (nat)Zn(p,x)(67)Ga, (nat)Zn(p,x)(66)Ga and (nat)Zn(p,x)(64)Cu processes.

Nuclear model analysis of excitation functions of proton and deuteron induced reactions on (64)Zn and (3)He- and α-particle induced reactions on (59)Co leading to the formation of copper-61: Comparison of major production routes.

Cross section data for formation of the medically important radionuclide (61)Cu (T½=3.33h) in proton and deuteron induced reactions on enriched (64)Zn and in (3)He- and α-particle induced reactions on (59)Co were analyzed by using the nuclear model calculational codes, EMPIRE and TALYS. A well-defined statistical procedure was then employed to derive the recommended excitation functions, and therefrom to obtain integral yields. A comparison of major production routes of (61)Cu was done.

Excitation functions of proton-induced reactions in (nat)Cu in the energy range 7-17 MeV.

Elemental production cross sections were measured for (p,x) reactions on natural Cu targets, leading to the formation of (62,63,65)Zn. These reactions are generally used for monitoring the proton beam intensity and energy e.g. in isotope production facilities. Cross sections were obtained by activation of stacked foils and subsequent gamma spectroscopy. The production data for (62,63,65)Zn between 7 and 16.5 MeV proton energy are presented as well as comparisons with literature values. Good agreement with the evaluated values was found for most of the cross-section values.