Investigation of beam property correlation in a mixed field beam using collimators of different compositions

Concrete-polyethylene interchangeable collimators are used to determine the field size and allow for flexibility in treatment planning at the Northern Illinois University Institute for Neutron Therapy at Fermilab. New collimator material is being evaluated to improve durability and safety during use. To this end, an effort has been undertaken to design epoxy-based versions that could effectively replace the current models. The leading candidate of the epoxy-based collimators was chosen to undergo beam property investigations and comparisons between the two collimator models were made. Dose buildup measurements were taken and dose components of the mixed field were calculated using the epoxy and concrete-polyethylene collimators. Beam properties tested were found to deviate by less than 3% between the different collimators in both areas of this investigation.