Bruce W. Wieland

Evaluation of an internal cyclotron target for the production of 211At via the 209Bi (α,2n)211At reaction

Abstract Astatine-211 is a 7.2 h half-life α-emitting radionuclide which has shown great promise for targeted radiotherapy. It is generally produced by cyclotron bombardment of bismuth metal targets with 28 MeV α-particles via the 209 Bi(α,2n) 211 At reaction. In order to provide 211 At activity levels anticipated for clinical investigations, an internal target system has been designed and evaluated. The system has a grazing-angle configuration and leading- and trailing-edge monitors. Both aluminum and copper target backings were evaluated. With approx. 28MeV α-particles, the 211 At production efficiency was 41 ± 7 MBq/ μ A·h, compared with 10.6 ± 1.2 MBq/ μ A·h for an external target. Radionuclidic purity of 211 At was high with no evidence of 210 At.

Radiation-hard non-contact fluid sensor for radionuclide production applications

Abstract It is often necessary to be able to detect the presence or absence of fluids in tubing located in high γ-ray or neutron flux areas. Non-contact methods are essential when direct electrode contact with the fluid has the potential for generating impurities. Optical sensing utilizing a light source and a photodetector is probably the most prevalent method used for non-contact fluid measurement. However, this method is not always suitable for use in high radiation flux area because the phototransistor or photodiode used for light detection can be susceptible to radiation damage. The sensor described here detects changes in capacitance between two electrodes located on the outside of a length of non-conductive tubing. This sensor can be used for remote indication of target filling operations, as well as for fluid sensing in automated radiopharmaceutical synthesis systems.

Simulation, design, and testing of a high power collimator for the RDS-112 cyclotron

A high power [F-18] fluoride target package for the RDS-112 cyclotron has been designed, tested, and commercially deployed. The upgrade includes the CF-1000 target, a 1.3kW water target with an established commercial history on RDS-111/Eclipse cyclotrons, and a redesigned collimator with improved heat rejection capabilities. Conjugate heat transfer analyses were employed to both evaluate the existing collimator capabilities and design a suitable high current replacement.

Monte Carlo analysis of multi-layer targets for production of 15O

A Monte Carlo simulation code was written to analyze multi-layer targets for production of 15O. The code models beam-particle transport through the target and production and transport of generated radionuclides; it can be used to assess the effects on radionuclide production of several beam and target design variables. A pathlength correction feature is included that relaxes restrictions inherent in previous ion transport codes and a variance reduction procedure is implemented that significantly improves code efficiency.