Calculation of patient doses using a human voxel phantom of variable diameter

The voxel phantom Golem was used for the dosimetric part of the EU research project 'Predictivity and Optimisation in Medical Radiation Protection'. A risk-related dose quantity, H-Golem, was evaluated using calculated organ equivalent dose conversion coefficients and entrance air kerma values measured during the clinical examinations. Two types of examinations were considered: chest PA examinations, which were performed in 16 groups involving different speed classes, mean optical densities, tube voltages and methods of scatter reduction; and lumbar spine AP examinations, for which four different combinations of speed class and tube voltage were used. For the chest examinations, the expected effects of different examination techniques are clearly mirrored by the dosimetric results. For the lumbar spine examinations, part of the expected results was concealed by the unwanted influence of the patient diameters on the doses, which could be partially eliminated by adapting the voxel phantom to different sizes.