Errors in Ferrous Sulphate Dosimetry

Abstract

A statistical analysis is made of 83 values of the Fe3+ extinction coefficient in direct 'liV spectrophotometry. Six of these coefficients have been obtained in this work by the same experimentalists and equipment by varying the source of standard ferric solution. The results show that errors in Fricke dosimetry arise from the preparation of the reference Fe37 solution as well as in the spectrophotometer. The effect of KaCI on the extinction coefficient is shown to be negligible in 0.8 N but not in 0.1 N H$04 solution. A recommended procedure of establishing the Fe3+ extinction coefficient is proposed.

G(Fe3+) values in the FBX dosemeter

“…The ferric ion solution was prepared by dissolving either crystalline ferric ammonium sulphate or Analar grade iron wire in sulphuric acid. Pejuan and Kiihn (1981) preparation of ferric ion solution is given by Broszkiewicz and Bulhak (1970) and by Eggermont et a1 (1978). The molar absorption coefficient was obtained from the slope of the plot of optical density against ferric ion concentration and the irradiations were done using the Philips ' ' CO teletherapy machine.…”