Ring Badge and Hand Dose in a PET Radiopharmacy
A radiopharmacist prepares F-18 FDG doses. Her ring badge (Hp(0.07)) reads 38 mSv for the quarter, and her whole-body badge reads 1.2 mSv. She reports tingling in her fingertips but no skin changes. The facility uses 0.5 mL syringes with no shielding during dose drawing, and she draws 20 doses per day, 5 days per week. The extremity limit is 500 mSv/y. The RSO must decide whether to (a) accept the dose, (b) add syringe shields and re-evaluate, or (c) refer for medical evaluation and restrict her work.
1. Calculate the projected annual extremity dose and interpret it against the limit.
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Quarterly ring dose = 38 mSv. If the workload is constant, annual = 38 × 4 = 152 mSv, which is below the 500 mSv/y extremity limit but well above the 20 mSv/y whole-body limit and above the 150 mSv/y lens limit. The ring badge is worn on the hand and measures Hp(0.07), which is the appropriate quantity for skin. The projected annual dose is about 30% of the extremity limit, so it is not an overexposure, but it is high enough to warrant ALARA action. The tingling is not a recognized deterministic effect at this dose (skin effects generally appear above 1–2 Gy), so it is more likely a work-related musculoskeletal issue, but it should be evaluated medically.
2. What is the best course of action?
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Option (b): add syringe shields and re-evaluate, and also refer for medical evaluation of the tingling without restricting her work on the basis of dose. The RSO should (1) introduce shielded syringe carriers and drawing shields, (2) review technique (distance, time, shielding), (3) consider automating dose drawing, (4) re-measure ring dose after the change and compare, (5) document the ALARA review. Option (a) is not acceptable because ALARA requires reducing dose when reasonably achievable. Option (c) is partly right - the tingling should be evaluated - but restricting her work is not justified by a dose that is 30% of the limit.