Radiation therapy is a key component in the multimodal management of p
ediatric tumors. Although success rates are increasing steadily, delay
ed morbidity remains a problem. Susceptibility is greatest for tissues
with high cell turnover rates, including the tissues of children. Exp
osure of normal tissues to radiation leads to growth disorders and to
neurologic and neuropsychologic deficits. Conformal radiation therapy
is external radiation beam therapy that is planned in such a way as to
conform the prescription dose to well-defined targets, thereby sparin
g normal tissues from high doses of radiation.