Hadrontherapy

In comparison to photon or electron beams used in conventional radiation therapy, high-energy proton-and heavy-ion beams offer favorable conditions for the treatment of deep-seated local tumors. Their physical depth-dose distribution in tissue is characterized by a small entrance dose and a distinct maximum (Bragg peak) near the end of range with a sharp fall-off at the distal edge. The well-defined range and the small lateral beam spread make it possible to deliver the dose with millimetre precision. Heavy ions, in addition, have an enhanced biological effectiveness in the Bragg peak region which is caused by the dense ionization and the resulting reduced cellular repair rate and make them very attractive for the treatment of radio-resistant local tumors. The article gives an introduction to hadrontherapy, including remarks on the history, basic physical and radiobiological principles, techniques of beam delivery and dose verification, and clinical experiences.