Radiation protection in radiosynovectomy of the knee

Abstract

Radiosynovectomy is a widely available therapeutic option that involves radiopharmaceutical injections into joints to treat rheumatoid arthritis. However, data on the beta-radiation dose equivalents for the staff performing such treatments are limited. The aim of this study was to determine the personal dose equivalents H(P)(0.07) to the skin of the hands of the treating physician under several exposure scenarios. An activity of 185 MBq (90)Y was used. Thermoluminescence detectors were attached at the finger tip of the thumb, forefinger, and middle finger of the treating physician. Measurements of beta-exposures were made during treatment of 70 knees with (90)Y under the following exposure scenarios: group 1, the radiosynovectomy was performed with syringe shield with Perspex (Plexiglas, Röhm GmbH, Germany) (thickness of 5 mm); group 2, additionally a manipulator was used for fixation of the needle; group 3, radiation-resistant gloves were added to the measures in groups 1 and 2. For group 1, the highest beta doses were measured at the forefinger (22.1 microSv MBq(-1)) (22,100 microrem/27 microCi) and thumb with 16.5 microSv MBq(-1) (16,000 microrem/27 microCi) at the left hand, which holds the needle (right-handed physician). In group 2, the radiation doses were reduced to 0.6 microSv MBq(-1) (60 microrem/27 microCi) at the left forefinger and 0.5 microSv MBq(-1) (50 microrem/27 microCi) at the left thumb. The use of a manipulator and special radiation resistant gloves reduced the radiation dose to 0.4 microSv MBq(-1) (40 microrem/27 microCi) at the left forefinger and to 0.3 microSv MBq(-1) (30 microrem/27 microCi) at the left thumb in group 3. It was concluded that while performing radiosynovectomy without a manipulator for fixation of the needle, the dose measured at the left forefinger could exceed the German limit of 500 mSv (50 rem) per year for the official dosimetry at the skin. Using holding forceps allows compliance with the legal limit and could considerably reduce the beta dose. The use of radiation-resistant gloves reduced the beta dose at the skin only slightly.