Absorbance measurement with a helium-neon laser for chemical dosimetry

A laser-based system for absorbance measurement has been developed for use in chemical dosimetry as an alternative to the spectrophotometer. The system incorporating a Helium-Neon laser operating at 543.5 nm is designed specifically for measurement of absorbed doses below 10 Gy with the ferrous sulphate-benzoic acid-xylenol orange (FBX) dosimeter. Absorbance measurement for the FBX dosimeter is normally carried out at 540 nm with a spectrophotometer. The performance of the laser-based system in measurement of absorbance is comparable to that of a standard spectrophotometer and it is concluded that the absorbance measurement technique is not the limiting factor in the sensitivity of the FBX dosimeter for absorbed doses below 1 Gy.