COMPARISON OF GRAPHITE-TO-WATER ABSORBED-DOSE TRANSFERS FOR CO-60 PHOTON BEAMS USING IONOMETRY AND FRICKE DOSIMETRY

To derive the absorbed dose to water from a standard of absorbed dose to graphite, the metrology laboratories which apply such a method usua lly make use of cavity ionization chambers as transfer instruments. In addition, the BNM-LPRI has tested, as such instruments, two types of Fricke dosimeter in its cobalt-60 beam The two procedures are compared and their results are found to be in good agreement (the difference i s less than 0.1%). Both procedures are then taken into account for the calculation of the reference value of absorbed dose to water.