A feasibility study for the in vivo measurement of beryllium by photonuclear activation.

Diagnosis of the beryllium-induced disease, berylliosis, is often difficult and always requires that the presence of the metal in tissue be demonstrated. The feasibility of developing an in vivo method of measurement, which exploits the uniquely low photonuclear reaction threshold of 1.67 MeV in beryllium, has been investigated. Suitable photon sources and detector systems were assessed, both experimentally by phantom studies and theoretically by use of a Monte-Carlo neutron transport code. It is concluded that by using a filtered source of 124Sb for bilateral irradiation of the chest, and an array of twenty BF3 counters, beryllium could be measured to an accuracy of 0.33 mg per lung, which corresponds to a 2 SD detection limit of 0.67 mg, for a skin dose of 50 mGy delivered within a period of 90s. Such a facility would be capable of contributing to the aetiology of the disease in a large proportion of cases, but the wider use of the method for screening exposed workers would require further improvements in detection efficiency.