The value of syringe shields in a nuclear medicine department

The radiation dose to the pulp of both index fingers has been measured in a radiopharmacy supplying 11 000 patient doses a year, in a hospital dispensary (4500 doses a year) and in its injection area. Tungsten syringe shields were used for one week and not used during the other week. In the radiopharmacy and the dispensary the highest finger dose recorded was 6.8 mSv, which corresponds to an annual figure of 330 mSv. Syringe shields gave a protection factor of less than two, and the dose to the left hand was approximately half that to the right. When giving injections the corresponding weekly and annual doses were 4.6 and 220 mSv respectively. If all injections had been given by a single person the corresponding annual dose would have been 430 mSv. Using syringe shields this could be reduced by factors of at least eight for the right hand but only 1.3 for the left hand. Dose rates for unshielded syringes expressed per 10 GBq handled are similar to other data in the literature. However, syringe shields reduce the dose rates less than anticipated. Tungsten 1.94 to 3.05 mm thick would be expected to give an attenuation factor of 27 to 178.