Study of the effects of source type and magnetic field on the spatial distribution of positron annihilation events in PET/MRI applicationsWeiling Zheng, Xingzhong Cao, Chong Li, Yuxiao Li, Baoyi Wang, Zhenjie Han, Fuyan Liu, Zhiming Zhang and Long WeiEur. Phys. J. Plus, 134 3 (2019) 85DOI: https://doi.org/10.1140/epjp/i2019-12445-1