A phantom and simulation study on body-shields to cope with radioactivity outside the field of view in 3D PET

Basic physics characteristics of body-shields to screen out radioactivity outside the field of view were analyzed by phantom experiments and Monte-Carlo simulation. The shielding effect depended primarily on the geometrical condition as in the case of end-shields. However, body-shields became more effective by increasing the shield thickness more than 10 mm as not in the case of end-shields. This characteristic difference was related with the fractions of un-scattered and shield-scattered components. A body-shield could be as effective as an end-shield if a good geometrical condition was kept with sufficient shield thickness.