The Determination of Absorbed Dose in a Proton Beam for Purposes of Charged-Particle Radiation Therapy

Abstract

Methods [4] were described for measuring absorbed dose in a proton beam extracted from the 160-MeV Harvard cyclotron. The standard dosimetry, used to determine doses for patient treatments, is based upon an absolute measurement of particle flux using a Faraday cup. Other means of measurement use a parallelplate ionization chamber; a thimble ionization chamber with 60Co calibration; and a tissue-equivalent calorimeter. The calorimeter, which provides an independent check of the dosimetry, agreed with the standard dosimetry at 5 different depths within a range from 0.8-2.6%.