131I therapy in thyroid cancer and benign thyroid diseases: personal dose equivalent HP(10) assessment in patient’s close family members

Introduction - The aim is to quantify the personal dose equivalent HP(10) in the family members (FMs) of the patients (PATs) undergoing iodine-131 thyroid cancer (TC) therapy and benign thyroid diseases (BTD) and to compare the HP(10) values of children and adults. Methods - An observational study with convenience sampling was performed, including 83 FMs (59% ♂) of 48 PATs (72.9% ♀). All FMs wore a whole body TLD for 21 days and received instructions on radiation protection, based on Euratom recommendations. All FMs were provided with relevant instructions for TLD use and answered a questionnaire. Two groups were defined: Group-TC, included 65 FMs (5 children below the age of 10) of 37 PATs treated for TC with average (ᾱ) activity of 3434MBq (range 1110–5920MBq); Group-BTD included 18 FMs adults of 11 PATs treated for BTD with ᾱ activity of 336.4MBq (range 185–555MBq). The in-PATs of Group-TC were discharged 48h after therapy. All ethical principles of the investigation were respected. Results - When the PATs of Group-TC were discharged the ᾱ effective dose rate measured at a 1-metre distance was 10.4μSv/h (range 2–28μSv/h). The ᾱ value of HP(10) in FMs were: 0.14mSv (range 0.00-3.37mSv) for Group-TC and 0.37mSv (range 0.01-2.40mSv) for Group-BTD. The HP(10) value depended on the degree of relationship (p=0.008) and the age of the FMs (p=0.007). HP(10) of the FMs were moderately associated to administered activity (ρsp=-0.319; p=0.010) in Group-TC. No association was found between HP(10) FMs and the administered activity in Group-BTD (ρsp=0.139; p=0.583). Conclusions - The FMs of the PATs submitted 131I therapy for BTD received higher doses when compared to FMs of TC PATs. The HP(10) of the FMs depended to the degree of relationship and the age of the FMs. In the PATs submitted 131I therapy for BTD, the HP(10) of the FMs is not associated with the administered activity. The personal dose equivalent in these FMs does not reach the dose limits recommended by ICRP 97 and ICRP 94.info:eu-repo/semantics/publishedVersio

Assessment of iodine-131 in the urine of the patient’s family members after differentiated thyroid carcinoma therapy

Introduction - The aim is to evaluate the internal exposure of the family members (FMs) of the patients (PATs) undergoing iodine-131 (131I) thyroid cancer (TC) therapy and quantify the amount of 131I in the FMs, excreted through the urinary. Methods - An observational study with convenience sampling was performed, including 25 PATs and 34 FMs. The PATs, who underwent 131I treatments for TC, were discharged from hospital 48h after therapy. All FMs received instructions on radiation protection, based on Euratom recommendations use and submitted to a questionnaire. A urine sample was collected from every FMs about 70h after discharge of the PAT. Samples of urine were analyzed by gamma spectrometry and counted for 24h. All ethical principles of the investigation were respected. Results - The average activity of 131I given to the PATs (52.9% ♀) was 3266.4 ±1120.2MBq. When the PATs have discharged the average (ᾱ) effective dose rate measured at a 1-metre distance was 7.9±5.8μSv/hr (range 1-25μSv/hr). In the 34 FMs (52.9% ♂) with ᾱ of 48.1±18.6years, only in 3FMs 131I wasn’t detected in the urine. In the other 31 samples urines, the specific activities of 131I have ᾱ of 97.4Bq/L (range 0.0-1146Bq/L). The specific activity of 131I in urine: it is not the same among the classes of the administered activity (p=0.019); don’t is the same on the different classes of FMs ages (p=0.470) and the different degree of relationship (p=0.744). We observed a moderate correlation between the specific activity of 131I in the urine and the activity administered to the PATs (ρsp=0.540; p=0.001) and also between the effective dose rate in the PATs (ρsp=0.730; p<0.001). With a CI of 95%. Conclusions - The PATs are a radioactive source that can cause exposure of the FMs to ionizing radiation. The specific activity of 131I in the urines of the FMs is related to the activity administered to the PAT. It is clear that FMs of PATs submitted to radioiodine therapy can be subject to internal contamination.info:eu-repo/semantics/publishedVersio