Sources of Radiation Dose to Technologists by FDG-PET

Introduction:
The aim of this study was to identify the main sources of radiation doses to technologists during PET studies to minimize the radiation exposure in routine F-18-FDG scanning.

Materials and methods:
The radiation exposure, personal dose and hand dose to technologists were measured during preparation and performance of F-18-FDG-PET scans.
The PET studies included dynamic brain scans with manual blood sampling, as well as heart and whole body scans without blood sampling. The injected activities varied between 260 and 370 MBq.
Transport of radiopharmaceutical (max. 7 GBq) in a lead container, 3 cm wall thickness. Preparation of the syringes in a lead box with window of 3 cm lead-equivalent. During injection the syringes were handled with a special pair of tongs. The syringe was shielded with an 8 mm tungsten wall. To protect the technologist from radiation emitted by the patient during manual blood sampling a movable radiation shield (2 cm lead) was placed between patient and technologist.

Results and conclusions:

Personal dose [µSv] at: syringe preparation - <=1; injection - 3; blood sampling - 28; patient handling - 15. Hand dose (rings) [µSv]: 27 left, 13 right. Hand dose (tapes) [µSv]: 710 left and right.
Assuming 13 PET studies/week and 52 working weeks/year the personal dose may lead to about 10 mSv/a.
Our measurements indicate that the maximal allowed hand dose per year will be reached after preparations of 500 syringes. Therefore, in PET facilities with a high patient throughput an automatic filling device has to be used.