Monitoring the Bragg peak location of 73 MeV/u carbon ions by means of prompt γ-ray measurements

By means of a time-of-flight technique, we measured the longitudinal profile of prompt γ-rays emitted by 73 MeV/u 13C ions irradiating a polymethyl methacrylate target. This technique allowed us to minimize the shielding against neutrons and scattered γ-rays, and to correlate prompt gamma emission to the ion path. This correlation, together with a high counting rate, paves the way toward real-time monitoring of the longitudinal dose profile during ion therapy treatments. Moreover, the time correlation between the prompt gamma detection and the transverse position of the incident ions measured by a beam monitor can provide real-time three dimensional control of the irradiation