Evaluation of staff whole body doses and extremity doses during PET-procedures before and after the introduction of automated dispensing and injection

It is generally known that significant staff exposure is expected during PET‐  and PET/CT‐ applications. As well whole body doses as extremity doses are usually higher compared to SPECT‐ applications. Dispensing individual patient doses and manual injection involves high extremity doses even when heavy weighted syringe shields are used. In some cases the external radiation causes an exposure to the fingertips of more than 500mSv/y. Whole body doses per procedure are relatively lower compared to extremity doses and are generally spread over the entire procedure i.e. during injection, escorting and positioning the patient on the camera. Optimisation of the individual technologist workload is often used to restrict staff doses. Many PET‐centres face however the need for further optimisation to reduce staff doses to an acceptable level. During this study the use of an automated dispensing and injection system for 18FDG was evaluated. Detailed dosimetry studies using thermoluminescent and direct ion storage dosimetry were carried out before and after the introduction of this system. The results show that the extremity doses can be reduced by more than 99% up to a median level of 4µSv per handled GBq. At the same time whole body doses can be halved during injection of the tracer which results in a dose reduction of 20% during the PET‐procedure of injection, escorting and positioning. In this way, the study shows that with the use of automated dispensing and injection a considerable staff dose reduction can be obtained.