Potential gains using high-energy protons for therapy of malignant tumours

High-energy protons have physical properties that virtually always will res ult in geometrically better dose distributions than can be achieved using p hotons or electrons. The clinical gains in terms of the probability of high er tumour control and/or the reduced probability of normal tissue complicat ions are, however, not completely known. Comparative model dose planning st udies using real patients offer the possibility of estimating the potential gains using a new technique. Several recently completed model studies, inc luding clinically relevant endpoints, indicate that protons map have advant ages, even when compared with the conventional treatment that is likely to be introduced at the most advanced hospitals world-wide within the next dec ade. These advantages can be seen not only in well-demarcated targets close to risk organs, but also when irradiating extended irregular tissue volume s at risk of containing tumour cells.