Comparison of ionization, ferrous sulphate and thermoluminescence dosimetry of megavoltage photons

Abstract

For V o y-radiation and 8, l 5 a 1 ~1 33 Jlv x-rays, dose measurements made, using (a) a calihrated Farmer-Baldwin dosemeter and CA values recommended by I.C.R.C., and ( b ) FeSO, solution and G-values recommended by I.C.R.L*., are compared. Differences between the results are within 506, and increase with increasing photon energy, FeSO, results always being the greater. The relative response of LiF TLD powder to these radiations has also been compared n-ith ionization measurements. On the assumption that the C,\ values are substantiall>-correct, and that for T o radiation G = 15.3, the data give FeSO, G-values of 16.1 i 0.2 at 8 JIv, 15.9 0.2 a t l 5 J I r and 16.3 k 0 . 2 a t 33 3lr. These are in good agreement, with the few literature yalues for phot'ons in this energy region, but are not consistent with literaturc values for high energy electrons.