Is one hand enough? Evaluation of the need for bilateral TLD extremity readings in a busy PET/CT imaging department

Objectives In many Functional Imaging departments it is common practice for PET technologists to wear only one extremity ring dosimeter on the dominant hand. The aim of this study is to compare the measured radiation dose received to the dominant and non dominant hands for PET technologists working in a busy stand-alone PET/CT imaging department (25 to 30 studies per day).

Methods 7 full-time PET technologists (FTT) were issued a second thermoluminescence dosimeter (TLD) ring to wear on their non dominant hand. Extremity ring readings were collected and the results for the dominant and non dominant hands were compared. The rings were exchanged monthly and TLD extremity readings were obtained from Health Canada's National Dosimetry Service (NDS). The radiation exposure values obtained from each hand were compared using a paired two-tailed t-test.

Results Over a one month period evaluating FTTs (n=7), the dominant hand recorded an average exposure of 8.97 ± 2.43 mSv (mean ± st. dev), while the non dominant hand had an average exposure of 12.86 ± 4.83 mSv. The readings were significantly higher (p=0.025) for the non dominant hand, with a mean difference of 3.89 mSv (95% CI = 7.09 - 0.68).

Conclusions PET departments should initially monitor TLD extremity readings for technologists on both hands to ensure annual extremity dose results are a reliable indication of maximum dose and within acceptable radiation exposure limits. If monthly reports reveal a significant difference between hands, department procedures and individual techniques should be adjusted. Given the significance of our initial findings, additional data will be collected to see if this trend continues