What degree of accuracy is required and can be achieved in photon and neutron therapy?

Mijnheer, B. J., Battermann, J. J., & Wambersie, A. (1987). What degree of accuracy is required and can be achieved in photon and neutron therapy? Radiotherapy & Oncology, 8(3), 237-252. https://doi.org/10.1016/s0167-8140(87)80247-5 (Original work published 1987)