Source of Support: None, Conflict of Interest: None
Ferrous ammonium sulphate benzoic acid xylenol orange dosimeter (FBX) developed to detect and measure radiation doses in the clinical range recommended the use of triple distilled water for its preparation and its shelf life was claimed to be two weeks. To be of use as a clinical dosimeter for routine use, preparation of this dosimeter with distilled water generated in the pharmacy department of our hospital was tried. The rapid auto-oxidation encountered forced us to undertake a systematic experimental study. The modification made in the concentration of sulphuric acid significantly increased its shelf life and hence it is referred to modified FBX (MFBX). Doses measured under various conditions were checked against ionization measurements with secondary standard dosimeter to show that MFBX can be used with confidence as a reliable clinical dosimeter. It is shown that measurement of doses with volumes as small as 0.6 - 0.7 ml is possible. Besides, MFBX can be used for output check as well as for verifying beam parameters of teletherapy units.