Abstract: Based on the proton beam of the newly built 100MeV cyclotron,according to IAEA TRS-398 report,proton beam Bragg peak measurement was carried out.Considering the principle of water absorption dose measurement and influencing factors,appropriate water phantom and ionization chamber were selected..Based on Bragg-Gray cavity theory and proton-matter interaction principle,the percentage depth dose curve of proton beam extended by graphite energy degarder was measured by PTW-30013 ionization chamber,MP3-P three-dimensional scanning water phantom and MEPHYSTO Navigator software.The percentage depth dose curve of proton beam was measured under the same experimental condition,the measurements were analyzed by software,with highest dose as a baseline the radiation parameters such as Bragg peak,peak width,pratical range,residual range and plateau height of the proton beam are obtained,The Bragg peak width of the proton beam is about 1.21 mm,and the reference depth is about 43.63 mm.

Key words: Proton beam, Bragg peak, Ionization chamber, Three-dimensional water phantom, Percentage depth dose curve of proton beam