Alanine/EPR dosimetry in brachytherapy

The paper reports the experimental procedure adopted to determine the absorbed dose rate in water per reference air kerma rate, DKr(d,θ), along the transverse bisector axis of a 137Cs brachytherapy source. The dose rate measurements have been carried out at difference distances, d, from the source using alanine dosemeters in a water phantom. The reference air kerma rate, K radicalr, was determined adopting a 'direct procedure' that uses a spherical ionization chamber in air. The dose rate constant of the source examined was DKr(1,π/2=0.99±0.03cGyh-1(μGyh-1)-1. The values of the radial dose function along the transverse axis, g(d), determined with an uncertainty of 3.4% (1σ), were found to be in good agreement with the results reported in the literature. The uncertainty in dose rate value has been estimated as 2.8% (1σ) for distances from the source up to 7 cm. K radical, has been determined with 1.2% (1σ) uncertainty. So DKr(d,π/2) values were determined with 3% (1σ) uncertainty. (author)