Production of actinium-225 from a (n,p) reaction: Feasibility and pre-design studies

Actinium-225 is used in nuclear medicine for the treatment of malignant tumours. It can be applied to produce Bi-213 in a reusable generator or can be used alone as an agent for radiation therapy, in particular for targeted alpha therapy. However, the availability of Ac-225 for worldwide use, particularly in low- and middle-income countries, is limited. We present a feasibility study employing GATE, an open-source Monte Carlo simulation toolkit, on the production of Ac-225 from a neutron generator. This work suggests that a design consisting of three concentric cylinders, the innermost a Cf-252 neutron source, the middle nickel cylinder acting as a proton-producing target and the outer cylinder a RaCl2 target may provide a feasible design outline for an Ac-225 generator

Estimation of Thermal & Epithermal Neutron Flux and Gamma Dose Distribution in a Medical Cyclotron Facility for Radiation Protection Purposes Using Gold Foils and Gate 9

The aim of this study is to characterise the neutron flux generated directly behind targets used in medical cyclotrons. The characterisation process aims at determining the feasibility of using the generated neutrons for research purposes in neutron activation analysis. The study was performed by activating gold foils placed directly behind the cyclotron targets. The thermal and epithermal neutron flux were found to be 4.5E+05 ± 8.78E+04 neutrons cm-2 s-1 and 2.13E+06 ± 8.59E+04 neutrons cm-2 s-1, respectively. The flux value is the same order of magnitude listed in the manual produced by the cyclotron manufacturer. The results are encouraging and show high potential for using the cyclotron facility as a thermal neutron source for research purposes. However, it is important radiation protection procedures be followed to ensure the safety of researchers due to the high gamma dose rate measured directly behind the target at 2.46 Sv/h using an OSL chip during the beam on time

Simulation of Coplanar Proximity Charge Sensing Electrodes in CZT Detectors

The concept of applying proximity charge sensing electrodes to semiconductor radiation detectors is a novel technique that has distinct advantages over directly deposited electrodes. This paper evaluates the application of proximity charge sensing onto a CdZnTe (CZT) semiconductor crystal using ANSYS Maxwell simulation software to calculate the weighting potential across the detector depth, the weighting potential across the detector width, and the electric field (E) generated inside the detector volume for multiple designs. To accomplish this goal, several variables are studied in the simulated designs: (1) a high resistivity thin-film material that is applied to the detector proximity surface from the anode side, (2) an appropriate metal that acts as an Ohmic contact to dissipate generated charges on the CZT anode side, and finally (3) an insulating layer (dielectric) to isolate the CZT detector body from the proximity electrodes. The results of the generated weighting potentials for both directly deposited electrodes and proximity-sensing electrodes, having the same electrode width and pitch, have been quantitatively compared using a figure of merit (FOM). The FOM compares the weighting potential created by each simulated design for weighting potential uniformity and weighting potential similarity