Acoustic waves characterize proton beams

Proton therapy’s main advantage for cancer treatment lies in the protons’ steep dose gradient at the Bragg peak. However, uncertainties in the exact Bragg peak location necessitate the use of larger-than-desirable target margins, resulting in deliberate over- and undershoot of the proton beam into healthy tissue. To fully exploit the advantages of the proton Bragg peak, it is critical to reduce the range uncertainties.