Measurement of absorbed dose from radionuclide solutions mixed intimately with the FBX dosimeter

Chemical dosimeters are used widely for accurate measurement of large radiation doses due to external beam irradiation from radionuclide sources and from particle accelerators. Their use for measurement of absorbed doses from radioactive solutions mixed in the dosimeter solution was reported as early as 1952, but the large activities needed to produce suitable absorbance values in the relatively insensitive dosimeters of that time discouraged further work. This manuscript reports the results of an investigation into the suitability of the ferrous sulfate-benzoic acid-xylenol orange (FBX) dosimeter for measurement of small absorbed doses caused by radionuclide solutions mixed with the dosimeter solution. The FBX dosimeter exhibited a linear dose response as a function of activity for two common radiopharmaceuticals, 99mTc sodium pertechnetate and 131I sodium iodide. Conditions under which the FBX dosimeter may be used with radionuclide solutions were studied and were found to be amenable to routine use by laboratories possessing relatively unsophisticated instrumentation. That any radionuclide could be studied using this dosimeter appears likely.