A practical individualized radiation precaution based on the dose rate at release time after inpatient 131I ablation therapy.

INTRODUCTION: Retained radioactivity of 131I after ablation therapy largely differs in each patient according to factors including the amount of remnant thyroid tissue, renal function, and use of recombinant human thyroid-stimulating hormone. To reduce unnecessary restriction of patient's daily life after inpatient 131I ablation therapy, we propose a practical individualized method for radiation precaution based on dose rate at release time. METHODS: We evaluated 215 patients with differentiated thyroid cancer who underwent inpatient 131I ablation therapy following total thyroidectomy. Effective dose equivalent rates at 1-m distance were measured upon release (EDRR) on day 2 and during delayed whole-body scan (EDRD) visits on day 6‒8 after 131I administration. The biexponential model was designed to estimate total effective dose equivalent to others. To assess conservativeness of our model, EDRD estimated by our model was compared with measured EDRD. EDRR-based periods of precaution not to receiving 1 mSv of radiation exposure were estimated and compared with those based on administered radioactivities on American Thyroid Association (ATA) recommendations. RESULTS: The EDRR ranged from 1.0-48.9 µSv/hr. The measured EDRD were equal to or lower than estimated EDRD in all patients, except for one, indicating that our model is sufficiently conservative. According to our model, no subjects needed additional daytime restriction after release. The maximum permissible times for public transportation use were longer in all patients compared with those based on administered radioactivities. Nighttime restriction periods were significantly shorter than those based on administered radioactivity; median periods requiring sleeping apart were 0 (range, 0‒5), 4 (range, 1‒14), and 3 (range, 2‒13) days after release in patients treated with radioactivity doses of 2.96, 5.50, and 7.40 GBq, respectively, needing 8, 16, and 19 additional days, respectively, based on administered radioactivity. CONCLUSIONS: Radiation safety instructions using proposed method based on EDRR of individual patient could safely reduce the burden of radiation precaution.

Estimated Internal and External Radiation Exposure of Caregivers of Patients With Pediatric Neuroblastoma Undergoing 131I Metaiodobenzylguanidine Therapy: A Prospective Pilot Study.

PURPOSE: Current recommendations suggest that family members should participate in the care of children receiving in-hospital I metaiodobenzylguanidine (MIBG) therapy for neuroblastoma. The present study aimed to measure the external radiation exposure and estimate the internal radiation exposure of caregivers during the hospital stay for I MIBG therapy. MATERIALS AND METHODS: Caregivers received radiation safety instructions and a potassium iodide solution for thyroid blockade before patient admission. External radiation exposure was determined using a personal pocket dosimeter. Serial 24-hour urine samples were collected from caregivers during the hospital stay. Estimated internal radiation exposure was calculated based on the urine activity. RESULTS: Twelve cases (mean age, 6.2 ± 3.5 years; range, 2-13 years) were enrolled. The mean administered activity was 233.3 ± 74.9 (range, 150.0-350.0) mCi. The mean external radiation dose was 5.8 ± 7.2 (range, 0.8-19.9) mSv. Caregivers of children older than 4 years had significantly less external radiation exposure than those of children younger than 4 years (1.9 ± 1.0 vs 16.4 ± 5.0 mSv; P = 0.012). The mean estimated internal radiation dose was 11.3 ± 10.2 (range, 1.0-29.8) µSv. CONCLUSIONS: Caregivers receive both external and internal radiation exposure while providing in-hospital care to children receiving I MIBG therapy for neuroblastoma. However, the internal radiation exposure was negligible compared with the external radiation exposure.

[Changes in quality of life and related factors in thyroid cancer patients with radioactive iodine remnant ablation].

PURPOSE: To investigate changes in Quality of life (QOL) and related factors in patients with thyroid cancer undergoing Radioactive Iodine remnant ablation (RAI). METHODS: Data were collected longitudinally 3 times for 6 months (2 weeks post-surgery, post RAI, 3 months post RAI) in a hospital located in Seoul. Questionnaires were used to measure levels of physical symptoms, anxiety, depression, and QOL. Ninety-eight patients with thyroid cancer who had RAI were included in the analysis. Data were analyzed using SPSS (18.0). RESULTS: Findings for the three data collection times respectfully were: mean scores for physical symptoms, 0.53, 1.21 and 0.62, patients with depression, 47%, 36.7% and 37.7%, patients with anxiety, 18.4%, 19.4% and 20.4%, mean scores for QOL, 7.06, 7.01 and 7.28. QOL score was highest 3 months post RAI (p=.031). In the stepwise multiple regression analysis, depression and fatigue were predicting factors for low QOL at all data collection times. Dysponia was a predicting factor for low QOL post RAI and 3 months post RAI. CONCLUSION: To increase QOL, it is necessary to provide information in advance regarding physical & psychological symptoms and to develop nursing intervention programs to decrease depression and fatigue.