Eye dose monitoring of PET/CT workers

The objective of the study was to measure eye dose [Hp(3)] to workers in a busy positron emission tomography (PET)/CT centre. Doses were compared with the proposed new annual dose limit of 20 mSv.

We used a newly designed dosemeter to measure eye dose [Hp(3)]. Eye dosemeters were worn with an adjustable headband, with the dosemeter positioned adjacent to the left eye. The whole-body dose was also recorded using electronic personal dosemeter (EPD® Mk2; Thermo Electron Corporation, Waltham, MA). Exposed staff included radiographers, nurses and healthcare assistants.

The radiographers received the highest exposure of the staff groups studied, with one radiographer receiving an exposure of 0.5 mSv over the 3-month survey period. The estimated maximum eye dose for 1 year is approximately 2 mSv. The numeric value for eye dose was compared with the numeric value for personal dose equivalent to see if one could be used as an indicator for the other. From our data, a conservative estimate of eye dose Hp(3) (mSv) can be made as being up to approximately twice the numeric value for whole-body dose [Hp(10)] (mSv).

Eye dose was found to be well within the new proposed annual limit at our PET/CT centre. Routine whole-body dose measurements may be a useful starting point for assessing whether eye dose monitoring should be prioritized in a PET facility.

Following the proposal of a reduced eye dose limit, this article provides new measurement data on staff eye doses for PET/CT workers.