Estimating and analysis of personnel doses from activated nuclides in radiotherapy place of a proton accelerator / 中华放射医学与防护杂志

ABSTRACT

Objective To ascertain the dose levels to personnel from the activation products in the radiotherapy place of a proton acceterator and to provide technical basis for protection design of the treatment place and the personnel's radiation protection.Methods A PROTEUS 235 proton therapy system was analyzed for the potentials to produce activated nuclides in the air during its operation.The concentrations of the main radionuclides and the resultant personnel doses were estimated.Results The activity concentrations of activated nuclides were 15O 4.1 × 10-2,13N 3.3 × 10-2,41 Ar 6.2 × 10-3 and 11 C 2.0 × 10-2 Bq · cm-3,respectively,in proton accelerator hall,whereas those in the proton beam radiotherapy room were only about 5％ of the corresponding values in the proton accelerator hall.The annual doses to the radiation workers from immersion external exposure due to air activation were less than 1 and 0.1 mSv,respectively,when entering the proton accelerator hall 5 and 30 min after beam stopping;whereas those were 1.3-2.0,0.7-1.2 and 0.3-0.6 mSv,respectively,when entering the therapy hall 0,5 and 15 min after beam stopping.Conclusions The personnel doses received from activated nuclides in the air in the radiotherapy place of a proton acceterator are unignorable.The contribution to doses from immersed external exposure of 15O,13N,41Ar and 11C should be taken into full considerations,with necessary protection measures needed.