Clinical trials using accelerated heavy charged-particle beams for tre
ating cancer and other diseases have been performed for nearly four de
cades. Recently there have been worldwide efforts to construct hospita
l-based medically dedicated proton or light-ion accelerator facilities
. To make such accelerated heavy charged-particle beams clinically use
ful, specialized instruments must be developed to modify the physical
characteristics of the particle beams in order to optimize their biolo
gical and clinical effects. This article reviews the beam modifying de
vices and associated dosimetric equipment developed specifically for c
ontrolling and monitoring the clinical beams.