Research Summary
Development of Monte Carlo codes for radiotherapy, in particular the BEAMnrc code which simulates radiotherapy accelerators and 60Co units, the DOSXYZnrc code which calculates the dose in a patient based on CT information and the BrachyDose code which models brachytherapy applied in for prostate, breast and eye-plaque treatments.

Development of general purpose codes for simulating transport of electrons and photons in arbitrary geometries. The EGSnrc code, an improved version of the EGS4 code, was released in May 2000 and is updated annually in collaboration with NRC. Careful benchmarks against measured data are carried out.

Application of Monte Carlo techniques to calculate correction factors required for primary radiation standards and dosimetry protocols.

Studies of fundamental physics related to dosimeters such as ion chambers and diode dosimeters. Recent experimental and computational work showed that the standard pressure-temperature correction does not work for x-ray beam dosimetry.

Simulation studies of off-focal radiation from x-ray tubes and improved efficiency of x-ray tube simulations.

Spearheaded the development of the AAPM's TG-51 protocol for external beam radiotherapy reference dosimetry.