Radiation exposure from patients treated with 165Dy-ferric hydroxide

Dosimetry perspectives in radiation synovectomy

Rheumatoid arthritis (RA) is a chronic inflammatory disease that can potentially damage the synovial joints. One of the effective treatment modality for RA is radiation synovectomy (RSV) where properly selected radionuclide is injected into the joint space, enabling controlled destruction of diseased synovial membrane via radiation exposure. Radiation dosimetry in RSV appears challenging due to the heterogeneous nature of synovial membrane, nonuniform distribution and leakage of radionuclide from the synovial cavity. This article reviews the dosimetric perspective pertaining to RSV. Specifically, characteristics of radionuclide for RSV and radiation dose to target and non-target (i.e., articular cartilage, bone, bloodstream, gonads, etc.) tissues of patient have been discussed. The personal dose H_p(0.07) to the hands of medical staff (i.e., radiochemist, therapist physician, nurse) may be considerably high due to handling of high specific activities (∼500 MBq/ml for Y-90); such doses are typically measured using thermoluminescence dosimeters (TLD) ring dosimeters and ranges from 1 to 21.5, 0.1 to 40 and 0.1 to 5 µSv/MBq for the radiochemist, therapist physician and the nurse, respectively. Methods to minimize radiation doses to the patient, medical staff and public are elaborated. Contamination risks and precautionary measures are also reported.

Management of chronic radiation enteritis with intestinal obstruction

AIM: To evaluate the effect of various treatment methods for chronic radiation enteritis with concurrent intestinal obstruction.

METHODS: The clinical data for 21 patients with chronic radiation enteritis and intestinal obstruction was retrospectively analyzed.

RESULTS: Five of seven patients who received conservative treatment experienced relapse, and the cure rate was only 28.6%. Fourteen patients who underwent surgical treatment (of them ten patients underwent intestinal resection and anastomosis) had satisfactory outcome, and the cure rate was as high as 90.0%. One patient developed intestinal fistula, and re-operation confirmed that it was caused by residual radiation enteritis.

CONCLUSION: Surgical treatment is the best way for treatment of chronic radiation enteritis with intestinal obstruction. All intestinal lesions should be surgically removed to avoid intestinal fistula.

Applied radioactivity in radiation synovectomy with [188Re]rhenium sulfide suspension

BACKGROUND

Early experience demonstrated absorbed dose in radiation synovectomy is about 100 Gy. For reaching this dose, the applied radioactivity should be calculated.

METHOD

Twenty-nine synovitic models of rabbit were treated by intra-articular injection of [(188)Re]rhenium sulfide and histological changes of synovium and cartilage were examined. The applied radioactivity was calculated by method of absorbed dose factor. In clinical, eleven haemophilic patients with haemarthrosis were performed radiation synovectomy with treated [(188)Re]rhenium sulfide. The synovial thickness was evaluated by MR and its value was used to calculate the applied radioactivity. After radiation synovectomy, all patients were followed up by synovial thickness, regional inflammation, and clinical course including bleeding frequency.

RESULTS

In rabbit models, the synovitic membrane can be eliminated by calculated radioactivity as planed without damaging the joint cartilage. In patients study, all patients exhibited significant reductions in synovial thickness and inflammation after radiation synovectomy with the planed radioactivities of [(188)Re]rhenium sulfide. Post-procedure bleeding frequency reduction in excellent and good reached to 63.6% by 18 months. In the cases of joint bleeding, the need for antihaemophilic factor treatment decreased immensely. Most of the recurrent episodes of bleeding were mild, subsiding with local means.

CONCLUSION

The applied radioactivity in radiation synovectomy could be calculated according to thickness of inflamed synovium. Further study including comparison therapeutic results from calculated individual activities with results from fixed activities and long-term follow-up is warranted.

Radiation protection in radiosynovectomy of the knee

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.