Materials: The new material consists of polystyrene beads coated in a
polymerizing substance that when dampened, hardens within 10 min. Resu
lts and conclusions: It has a density of less than a tenth of that of
water and so is light-weight, a CT number of less than -800 and a mini
mal effect on the build-up of megavoltage photon beams. (C) 1998 Elsev
ier Science Ireland Ltd.