External Exposure Of Patients With ^99mTc-MDP Bone Scanning And Evaluation Of Shielding Effect About Lead Protective Clothing

Objective:The aim of this study was to monitor the environmental radiation dose of bone scanning patients who was injected different radioactivity 99 m Tc-MDP at different time and various distances and analyze the protective effects of 99 m Tc Gamma ray about lead protective clothing with different kinds of lead equivalent.Methods:1. Randomly select 180 bone scanning patients who can move freely in Department of Nuclear Medicine,the Second Hospital of Jilin University from July to November,2015.And divide them into three groups randomly.Every group included 60 patients.The bone imaging agent was 99 m Tc-MDP.The radioactivity by intravenous injection was respectively about 15 m Ci,18 m Ci and 20 m Ci（ 555 MBq,666MBq and 740MBq）.Patients injected drugs all undertook bone scanning examinations after 2 to 5 hours.Detect the dose equivalent rates of the injecting room and the scanning room respectively as the background dose equivalent rates with multifunctional ray detector.2. Randomly select 48 patients every groups for a total of 144 patients.They all lay on the scanner bed when they were detected dose equivalent rates.Choose the points which are respectively 0.05 m,0.5m,1.0m,1.5m and 2.0m distant from the body surface of patients’ waist lateral as environmental measurement points.Detect the dose equivalent rates of the patients at various points immediately after the patients were injected 99 m Tc-MDP and 2,3,4,5 hours later.Then detect the dose equivalent rates of the patients with multifunctional ray detector which is respectively shielded with 0.25 mm Pb and 0.5mm Pb lead protective clothing on the same environmental measurement points and at the same time points.3.The rest 36 patients sat on the seat besides the window of the injecting room immediately after the patients injected drugs.Also choose the points which are respectively 0.05 m,0.5m,1.0m,1.5m and 2.0m distant from body surface of patients’ middle of the lower back as environmental measurement points.And detect the dose equivalent rates of the patients with different radioactivity at above-mentioned environmental measurement points.Then detect the dose equivalent rates of the patients with multifunctional ray detector which is respectively shielded with0.25 mm Pb and 0.5mm Pb lead protective clothing at above-mentioned environmental measurement points.4.We respectively used the dose equivalent rates detected without lead clothing,with 0.25 mm Pb lead protective clothing and with 0.5mm Pb lead protective clothing to make one-way analysis of variance.Every group of data was taken a homogeneity test for variance by means of Levene’s test.If the variance is equal,the two-two comparisons among the means were done by S-N-K method.If the variance is unequal,the two-two comparisons among the means were done by Dunnett’s T3 test.If P<0.05,the results were statistically significant.We compared the dose equivalent rates with or without lead protective clothing and two kinds of lead protective clothing to judge whether it had statistically significant.Results:1.The dose equivalent rates at different time and different distances after the patients injected different radioactivity 99 m Tc-MDP in supine positionThe dose equivalent rates detected from the patients injected different radioactivity drugs at different time and at 0.05 m distant from body surface of the patients’ waist lateral were all higher than target management value 2.5μSv/h which calculated from the basic standard of ionizing radiation protection and radiation sources safety in our country（GB18871-2002）.The dose equivalent rates detected from the patients at different time and at more than 0.5m distant from body surface of the patients’ waist lateral were all lower than target management value 2.5μSv/h except the dose equivalent rates detected immediately after the patients injected drugs,but still higher than the background dose equivalent rates.The general trend was the more the injected dose was,the nearer the distance was,or the shorter the time was,the higher the dose equivalent rates were.The dose equivalent rates gradually reduced with the time’s going and the distance’s increase.According to the distance,the decreasing amplitude from 0.05 m to 0.5m immediately after the patients injected drugs was largest,reaching 89.65% to 91.46%.According to the time, the decreasing amplitude at 0.05 m from body surface immediately after the patients injected drugs to 2h was largest,reaching 56.95% to 76.14%.The dose equivalent rates still decreased at more than 0.5m and 2 hours later,but the decreasing amplitude slowed down quite markedly.From the decline of the dose equivalent rates provided by three doses 99 m Tc-MDP,with the increase of dose,whether the extension of time or the increase of the distance,the decline of the dose equivalent rates gradually reduced instead.2.The dose equivalent rates shielded with 0.25 mm Pb and 0.5mm Pb lead protective clothing at different time and different distances after the patients injected different radioactivity 99 m Tc-MDP in supine position0.25 mmPb and 0.5mmPb lead protective clothing all had the obvious shielding effect on different dose 99 m Tc-MDP gamma ray.It can respectively decrease77.46%,75.73% and 75.67% gamma ray using 0.25 mm Pb lead protective clothing in0.05 m apart from patients immediately after the patients injected 15 m Ci,18 m Ci and20 m Ci 99 m Tc-MDP.It can respectively decrease 88.81%,86.13% and 86.59% gamma ray using 0.25 mm Pb lead protective clothing in 0.05 m apart from patients immediately after the patients injected 15 m Ci,18 m Ci and 20 m Ci 99 m Tc-MDP.The shielding effect of 0.5mm Pb lead protective clothing was stronger than the0.25 mm Pb lead protective clothing（P<0.05）.3.The dose equivalent rates at different distances immediately after the patients injected different radioactivity 99 m Tc-MDP in sitting positionThe dose equivalent rates detected from the patients immediately after injecting different radioactivity drugs at different distances from body surface of patients’ middle of the lower back in sitting position were higher than the corresponding values in supine position.The dose equivalent rates in sitting position respectively53.92%,43.87% and 58.64% higher than the dose equivalent rates in supine position at 0.05 m.4.The dose equivalent rates shielded with 0.25 mmPb and 0.5mmPb lead protective clothing at different distances after the patients injected different radioactivity 99 m Tc-MDP in sitting position0.25 mm Pb and 0.5mm Pb lead protective clothing all had the obvious shielding effect on different dose 99 m Tc-MDP gamma ray.It can respectively decrease73.87%⁷7.76% and 87.85%⁹1.12% gamma ray using 0.25 mm Pb and 0.5mm Pb lead protective clothing in 0.05 m apart from patients immediately after the patients injected 15 m Ci,18 m Ci and 20 m Ci 99 m Tc-MDP.The shielding effect of 0.5mm Pb lead protective clothing was stronger than the 0.25 mm Pb lead protective clothing（P<0.05）.Conclusions:1.The radiation dose forming from the patients immediately after injecting^99mTc-MDP at 0.05 m distant from body surface are largest.The dose equivalent rates gradually reduced with the time’s going and the distance’s increase.The decreasing amplitude is largest at 0.05 m distant from body surface or in two hours.2.In the case of same dose,the dose equivalent rate monitored at the same time with the same environmental measurement points in sitting position is significantly higher than the supine position.3.Whether supine position or sitting position,0.25 mmPb and 0.5mmPb lead protective clothing all have the obvious shielding effect on different dose 99 m Tc-MDP gamma ray.The shielding effect of 0.5mm Pb lead protective clothing is stronger than the 0.25 mm Pb lead protective clothing.4.In daily work,the nurses who inject drugs should wear in 0.5mmPb lead protective clothing.The technicians don’t need to wear lead protective clothing when they are more than 0.5m distant from the patients who need to be placed and should wear in 0.5mm Pb lead protective clothing when they are less than 0.5m distant from the patients.5.On the premise of satisfying the condition of bone scanning,we should try to reduce the dose of 99 m Tc-MDP to reduce the radiation dose to outside,at the same time to reduce the illuminated dose of patients own.