The Use of Compensators and Multiple Static Fields for IMRT of the Breast

External beam radiotherapy of the breast has been shown to lead to a significant reduction in the incidence of local recurrence [1]. Unfortunately these gains are partially offset by side effects, such as ischaemic heart disease, arm lymphoedema, brachial plexopathy, breast pain, poor cosmesis and pneumonitis. A major contributing factor to these complications is believed to be the inhomogeneity of the dose distribution from tangential irradiation which often exceeds the figure of 10% considered to be acceptable.