Exit dose

In external-beam photon radiotherapy, the beam enters the body, makes its way to the tumour, then makes its way out. As it makes its way out, it inevitably harms some healthy cells. We call this the exit dose This happens in all photon radiotherapy modalities — Tomotherapy and Cyberknife included. In fact, Tomotherapy and Cyberknife tend to lead to higher entrance dose and higher exit dose compared to conventional external-beam radiotherapy. Hadrontherapy is revolutionary in terms of low entrance dose and lose exit dose. The Bragg peak is far higher than the enrance and exit doses. Hadrontherapy includes proton and carbon therapies.