Calibration of strontium-90 eye applicator using a strontium external beamstandard

Four techniques for measuring the dose rate from Sr-90 concave eye plaques are presented. The techniques involve calibrating a concave eye plaque agai nst a Sr-90 teletherapy unit using X-Omat him, radiochromic film, black LiF TLD discs and LiF chips. The mean dose rate predicted by these dosimeters is 7.5 cGy s(-1). The dose rate quoted by the manufacturer is 33% lower tha n this value, which is consistent with discrepancies reported by other auth ors. Calibration against a 6 MV linear accelerator was also carried out usi ng each of the above dosimetric devices, and appropriate sensitivity correc tion factors have been presented.