SPECT assay of radiolabeled monoclonal antibodies. Final performance report, March 1992--November 1995

Research is described in the following areas: development and evaluation quantitatively of reconstruction algorithms with improved compensations for attenuation, scatter, and geometric collimator response; evaluation of single photon emission computed tomography (SPECT) quantification of iodine 123 and astatine 211; and the development and evaluation of SPECT pinhole imaging for low and medium energy photons

Internal radionuclide dosimetry of model and patient based voxelised phantoms using the GATE toolkit

The desire for realistic patient specific dosimetry estimates of internally distributed radioactivity are realised by using Monte Carlo simulations of voxelised phantoms. The purpose of this thesis was to validate the GATE Monte Carlo package as a dosimetry tool and to investigate the accurate application of model and patient specific voxelised phantoms. Validation of the GATE Monte Carlo package was performed by simulating the absorbed fractions of simple geometric spheres of uniform radioactivity compared to accepted values. Voxelised spheres have also been simulated and it was found that the GATE Low Energy physics package was the most suitable for simulations of voxelised phantoms. The simulation of the scalable XCAT voxelised phantom has been performed to evaluate the effect of voxel size and patient organ mass on the calculation of dose factors. It was found that for organ self-irradiation significantly small voxels are required to ensure that insufficient voxel sampling does not effect the absorbed dose calculation. A retrospective absorbed dose calculation of true patient images was then performed with a correction for insufficient voxel sampling. In this work the scalable XCAT phantom has also been used to show that a voxel size of 2 mm or less is suitable for accurate calculations of organ cross dose. By comparing the scaled XCAT phantoms with patient and traditional phantoms it was concluded that considerable care is required when adapting model-based phantom results to individual patients. As differences in patient anatomy contribute significant variability to the dosimetry calculation, it is therefore recommended that where available individual patient specific dosimetry should be calculated using direct Monte Carlo simulation in favor of organ mass scaling