| Part 1 Study on dynamic change of radiation dose rate and estimating effective half-life of 1311 in patients with differentiated thyroid carcinoma after 1311 treatmentObjectiveStudy the dynamic change of radiation dose rate with time and distance in patients with differentiated thyroid carcinoma (DTC) after 1311 treatment. Estimating the effective half-life of 131I according the radiation dose rate at the distance of 1 m.Materials and MethodsWe collected postoperative patients with DTC (n = 141) who were treated in our department from May 2015 to October 2015. According the number of 1311 treatment, we divided patients into the first therapy (FT) and repeated therapy (RT, the number of 1311 treatment> 2). We measured the radiation dose rate at the time of 1,2,3,4,5,6,7,14,21,28 days after administered 1311 in the distance at 0.5,1,2,3 m. Radiation dose rate were recorded respectively D1, D2, D3, D4, D5, D6, D7, D14, D21, D28, the units was uSv/h. We observed the dynamic change of radiation dose rate. At the same time, we estimated the effective half-life of 1311 with DTC patients according to the radiation dose rate at the distance of 1 m. Using SPSS 19.0 statistics software for analysis, normal distribution measurement data with the average+/-standard deviation records, using t test; Non-normal distribution measurement data with a maximum, minimum, median records, using nonparametric rank test. There had significant difference (P< 0.05).Results141 cases of patients,40 males and 101 females, the mean age (40.8 ± 12.5) years. Including FT 79 cases,22 males and 57 female ((M:F = 1:2.6), mean age (36.4 + 14.7) years, the administered 131Ⅰ dose 2590 to 7030MBq, the mean dose (5220.7+ 1058.2) MBq; RT 62 cases,18 males and 44 female ((M:F = 1:2.4), mean age (42.3 +13.6) years, the administered 131Ⅰ dose 4440 to 9250MBq, the mean dose (6682.2 + 1076.7) MBq. The gender and age between two groups had no significant difference (P> 0.05); the mean administered 131Ⅰ dose of FT was less than RT, had significant difference (P< 0.05).The radiation dose rate declined rapidly with the extension of time and distance in DTC patients after administered 131Ⅰ treatment. The radiation dose rate decreased more rapidly at the fist 4days after administered 131Ⅰ in FT group patients, there had significant difference multiple comparisons (P< 0.05). After 4 days, the radiation dose rate declined slowly and there had no significant difference between each measuring point (P>0.05); In RT group patients, there had significant difference between the first 2days (P< 0.05), there had no significant difference between each measuring point after 2 days (P>0.05); the FT radiation dose rate were higher than RT in any time and distance, there had significant difference between two groups in 2 and 3 daysfter administered 131Ⅰ (all P＜0.05), the rest of the different distance and time had no significant difference between two groups (all P> 0.05); the effective half-life of 131Ⅰ in DTC patients extended with time, the effective half-life of 131Ⅰ in FT group was longer than RT group. The mean effective half-life of 131Ⅰ of FT and RT group were 1.08days and 0.54 days respectively in the first 3 days after administered 131, there had significant differences (all P< 0.05), but there had no significant differences between two groups after 3days (all P> 0.05). After 7 days, the effective half-life of 131Ⅰ was close to its physical half-life in two group patients.ConclusionThe radiation dose rate declined rapidly with the extension of time and distance in DTC patients after administered 131Ⅰ treatment. The radiation dose rate declined more rapidly in RT group patients. The rate of descent became slow after 4 days in the FT group. The rate of descent became slow after 2 days in the RT group; the effective half-life of 1311 extended with time. The mean effective half-life was 1.08 days and 0.54 days in the FT, RT group patients in the first 3 days after administered 1311, all patients with an average of 0.81 days. After 7 days, the effective half-life of 1311 was close to its physical half-life in all patients.Part 2Estimating the hospitalization time of patients with differentiated thyroid carcinoma after 1311 treatmentObjectiveMonitored the radiation dose rate of DTC patients after administered 1311 treatment, we determined the patients’ hospitalization time on the basis of the radiation dose rate at 1 m distance.Materials and MethodsWe prepared 400MBq 1311 standard source and measured its radiation dose rate at lm and 1.5m from the ground, the unit was uSv/h; measured the background radiation dose rate for 5 times; we divided the 141 cases into two groups according the number of administered 1311, including FT and RT groups. We monitored the radiation dose rate of DTC patients after 1 day administered 1311 until the radiation dose rate less than or equal to the radiation dose rate of 400MBq. The monitoring interval time was 24 hours. We observed the change of hospital discharged rate with time and evaluated the hospitalization time of DTC patients which judged by the 1311 residual activity for 1110MBq and 400MBq.ResultsThe background radiation dose rate was 0.35uSv/h, the radiation dose rate of 400MBq 1311 was 30.12uSv/h (equal to 30.47-0.35uSv/h), remembered 30uSv/h. The discharged rate increased with time extend after administered 131I treatment, the increased speed was most fastest after administered 13112 days, and the increased speed in RT group was more faster than in FT. According to the 131I residual activity for 400MBq (the dose rate 30usv/h or less at lm):the discharged rate was higher in FT than RT after administered 131I 1day, there were 8.9%(7/79) and 4.8%(2/62). The time of all FT and RT patients could be released from hospital were after administered 131Iseven and four days, the isolated time of two groups were (2.4±1.1)x(2.0±0.4) days. After 3 days administered 1311, 9.2%( 13/141)patients ’radiation dose rate were higher than 30 uSv/h, 11 FT cases included, the B ultrasound of thyroid, pre-therapy thyroid static imaging and post-treatment 131I-WBS showed thyroid tissue remained obviously; Another 2 cases were RT patients and their 131I-WBS showed multiple bone metastases.According to the 1311 residual activity for 1110MBq (the dose rate 70usv/h or less at 1m):in FT and RT group, the rate of radiation dose rate at lm lowed 70uSv/h were 54.4% and 64.5%after administered 1311 lday. All patients could be released from hospital were five (FT) and two (RT) days after administered 1311. The mean isolated time of two groups were (1.5±0.7)、(1.3±0.5) days.ConclusionThe radiation dose rate declined rapidly with time at lm after administered 1311 treatment. We determined the patients’ hospitalization time according the 1311 residual activity for 1110MBq (the dose rate 70usv/h or less at lm):the all FT patients could be discharged from hospital after 5 days who were administered 1311, the mean hospitalization time was (1.5±0.7) days.The all RT patients could be released isolation after 2 days who were administered 131I, the mean hospitalization time was (1.3±0.5) days. According to the current and latest standards of our country, that was the 1311 residual activity for 400MBq (the dose rate 30usv/h or less at lm):the all FT patients could be discharged from hospital after 7 days, the mean hospitalization time was (2.4±1.1) days.The all RT patients could be released after 4 days, the mean hospitalization time was (2.0±0.4) days. In short, it was enough safe that the DTC patients were isolated 3 days after administered 1311, besides the patients who had obvious thyroid tissue residual and multiple bone metastases.Part 3 Radiological protection recommends for surrounding peoplewith differentiated thyroid carcinoma after 131Ⅰ treatmentObjectiveBased on the change of radiation dose rate with time and distance inDTC patients after 131Ⅰ treatment, it aimed to estimate the exposure dose that the medical staff, patients’ caregivers, family members and the general public received in the process of contact with the patients, calculate the restricted period for thesesurrounding people at different time and distance, formulate the personalized radiological protection recommends for different crowds.Materials and Methods141 postoperative patients with DTCwho were treated in our department were collected from May 2015 to October 2015. According the number of 131Ⅰ treatment, we divided these patients into FT and RT groups, measured the radiation dose rate at the time of 1,2,3,4,5,6,7,14,21,28 days after administered 131Ⅰ in the distance 0.5,1,2, 3 m.Based on the regulations about annual dose limit for surrounding people in GB 18871-18871 "basic criterion on ionizing radiation protection and radiation sources safety ", assumed that the medical staff work 240 days per year, worked 8 hours per day; the caregiver cared a DTC patient per year, worked 24 hours per day; family members contacted two DTC patients within a year and stayed 8 hours a day; general public contacted one DTC patient within a year and stayed 8 hours a day, we figured out their days’ limit dose.Unprotected conditions contacted with DTC patients, when the exposure time over 8 hours,24 hours,8 hours,8 hours, that would lead these peoples’ exposure dose beyond their days’ limit dose, the point time was named critical point. The periods before critical point time called restricted period. At the same time, we calculated the time limits that different crowds contacted with DTC patients at different distance.ResultsWe calculated the day dose limit of the medical staff, patients’ caregivers, family members and the general public according to Mountford method, that were 83.33uSv/h,166.67uSv/h,16.67uSv/h and 33.33uSv/h; for diagnoses and treatment, the mean time limit that the medical staff contacted with FT and RT patients at 0.5m was 1.32 and 1.67 hours per day during the hospitalization; the restricted period of the medical staff, patients’ caregivers, family members and the general public contacted with FT group patients at 0.5,1,2,3m distance were respective fifth, fourth, third, second day, fifth, fourth, third, third day, seventh, fifth, fifth, fourth day, sixth, fifth, fourth, third day; their restricted periodcontacted with RT group patients at 0.5,1,2, 3m distance were respective fourh,third, third, second day, fifth, fourth, third, third day, sixth, fifth, fourth, fourth day, fifth, fourth, third, third day; the restricted period at 0.5m should be extended to 28 days after 131Ⅰ treatment in several patient who had obvious thyroid tissue residual and multiple bone metastases.ConclusionBy monitoring the radiation dose of DTC patients at different time and distance in the study, we estimated the time limit that different people contacted with patients at different time and distance according the annual dose limit. During the hospitalization, for diagnoses and treatment, the mean time limit that themedical staff contacted with FT and RT patients at 0.5m was 1.32 and 1.67 hours; at 0.5,1,2,3m, all patients’ mean restricted period were seventh, fifth, fifth, fourth days after administered 131Ⅰ; the restricted period at 0.5m should be extended to 28 days after 131Ⅰ treatment in these patient who had obvious thyroid tissue residual and multiple bone metastases. The surrounding people should comply with the time limitduringthe restricted period,it was enough to ensure the exposure dose meted the relevant criterion for all personnel.Part 4The analysis of influencing factors on decline of radiation dose ratewith differentiated thyroid carcinoma after 1311 treatmentObjectiveBe aimed to analyze influencing factors on decline of radiation dose rate with differentiated thyroid carcinoma after 1311 treatment, guide the nuclear medicine physician evaluating the radiation risk and formulating the personalized protective recommendations for DTC patients.Materials and MethodsWe collected postoperative patients with DTC (n= 141) who were treated in our department from May 2015 to October 2015. Including patients pathologically confirmed DTC. Exclusion criteria:difficult action and can’t cooperate with measurement of DTC patients. All DTC patients were demanded to avoid iodine diet 1 month and stop takingL-thyroxine3-4 weeks before administered 1311 treatment. 141 cases were divided into two groups according to the radiation dose rate at lm whether it was or less 30usv/h after 48 hours administered 1311. All patients included age, gender, pathological type,1311 dosage, treatment times, TSH, sTg, urine iodine, neck ultrasound,iodine uptake rate of 24h, pre-therapy thyroid static imaging, post-treatment 131I-WBS, metastases (without metastases, lymph node metastases, lung metastases, bone metastases). SPSS 19.0 statistical software was used,x2 test, t test, and logistic regression analysis to filter out the factors for influencing the decline of radiation dose rate with differentiated thyroid carcinoma after 1311 treatment.Results141 cases of patients,121 cases were standard,37 cases aged<45 years,84 cases aged≥45 years,35 males and 86 females (M:F = 1:2.5),5 cases 1311 dosage≤3700MBq,95 cases 1311 dosage range 3700 to 7400MBq,21 cases 1311 dosage≥7400MBq,10 cases TSH<30＜30μIU/m,111 cases TSH>30μIU/m,48 cases sTg≤1.4μg/1,50 cases sTg range 1.4 to 78μg/1,23 cases sTg≥78μg/1,101 cases of urinary iodine 100 ug/l or less,20 cases urinary iodine>100 ug/l,84 cases iodine uptake rate of 24h<1%,32 cases iodine uptake rate of 24h range 1% to 10%, 5 cases 84 cases iodine uptake rate of 24h≥10%,58 cases RT,63 cases FT,113 cases were PTC,8cases were FTC,96 casesneck ultrasound revealed thyroid tissue no residues,25 casesresidues,78 cases pre-therapy thyroid static imagingrevealedno residues,43 cases thyroid tissue residues,30 cases post-treatment 131I-WBS were negative,38 cases showed metastases,53 cases showed thyroid tissue remained,13 cases no metastases,92 cases lymph node metastases,11 cases lung metastases,5 cases bone metastases;20 cases were under standard,10 cases aged<45 years,10 cases aged≥45 years,6 males and 14 females (M:F = 1:2.3),3 cases 1311 dosage≤3700MBq,15 cases 1311 dosage range 3700 to 7400MBq,2 cases 1311 dosage≥7400MBq,5cases TSH<30μIU/m,15 cases TSH≥30μIU/m,3 cases sTg≤1.4μg/1,13 cases sTg range 1.4 to 78μg/1,4 cases sTg≥78μg/1,16 cases of urinary iodine 100 ug/1 or less,4 cases urinary iodine>100 ug/1,4 cases iodine uptake rate of 24h≤%,1 case iodine uptake rate of 24h range 1% to 10%,15 cases iodine uptake rate of 24h≥10%,4 cases RT,16 cases FT,18 cases were PTC,2cases were FTC,7 cases neck ultrasound revealed no thyroid tissue residues,13 cases residues,3 cases pre-therapy thyroid static imaging revealed no thyroid tissue residues,17 casesresidues,2 cases post-treatment 131I-WBS were negative,1 case showed metastases,17 cases showed thyroid tissue remained,2 cases no metastases,14 cases lymph node metastases,2 cases lung metastases,2 cases bone metastases.Univariate analysis showed the TSH, iodine uptake rate of 24h, treatment times, neck ultrasound, pre-therapy thyroid static imaging and post-treatment 131I-WBS were significant factors (alLP<0.05), but 1311 dosage, age, gender, primary tumor types, levels of sTg, metastaseswere no significant difference (all P>0.05). On multivariate logistic regression, iodine uptake rate of 24h were statistically difference (all PO.05), but TSH, treatment times, neck ultrasound, pre-therapy thyroid static imaging and post-treatment 131I-WBS were no significant difference (all P>0.05).ConclusionPatients’age, gender,1311 dosage, sTg, urine iodine, primary tumor pathological type and metastases had nothing to do with the decline of radiation dose rate with DTC patients after 1311 treatment. The number 1311 treatment, TSH, iodine uptake rate of 24h, neck ultrasound, pre-therapy thyroid static imaging and post-treatment 131I-WBS showed thyroid tissue remained had connection with it. What’s the more, iodine uptake rate of 24h was the independent factors affecting he decline of radiation dose rate with DTC patients after 1311 treatment. Therefore, we should consider the clinical information roundly when we evaluated the DTC patients’ isolated time, especially iodine uptake rate of 24h. That was conductive to evaluating the radiation risk and formulating the personalized protective recommendations for DTC patients. |
PDF Full Text Request