Occupational Doses from the use of Thoriated Optical Components

As a compound of high refractive optical glasses, thorium still is present in some professionally used systems-especially in optical equipment with military use. The possible exposure concerns the head and especially the eye lens, whose radiation sensitivity has been reevaluated. The dose rate measurements of the contribution of beta- and gamma-emission by the nuclei of the decay chain of Th are presented for isolated lenses and for the entire optical system, and the dose quantities H'(0.07) and H*(10) are identified. Exposure scenarios for optical technicians and users are evaluated separately. The levels of dose rates for the inspected optical systems are below those requiring radiation protection measures even for extended working time or unintentional use.