proton beam therapy system 200 million proton beam expansion 200 million proton beam expansion proton beam therapy program radiation oncology clinical cal proton beam facility construction mayo s proton beam therapy adds to mayo clinic proton therapy installation mayo clinic proton therapy installation hitachi proton beam therapy coming to mayo clinic s proton therapy project mayo clinic proton beam center mayo clinic proton beam facility construction rochester minnesota 233 million oncology building proton beam facility construction mayo clinic practical proton therapy proton beam therapy services mayo clinic proton beam center mayo clinic archives egan company proton beam treatment at mayo clinic 200 million proton beam expansion mayo clinic practical proton therapy mayo clinic practical proton therapy proton beam facility construction mayo clinic health system in mankato