[en] Magnetic resonance imaging (MRI) provides high-resolution anatomical information. In this study, we investigated the usefulness of an MRI-constrained method for image reconstruction of positron emission tomography (PET). We started the reconstruction process with a conventional Bayesian reconstruction (BAY) method. Typically after 7 iterations, we calculated the apparent radioactivity ratio between gray matter and other tissues such as white matter and cerebrospinal fluid from both the PET image and tissue classification probability images generated from segmented MR images, and then increased this ratio to enhance the functional boundary gradient. We multiplied the apparent ratio by 2.0. Subsequently, the cross-correlation between anatomical and enhanced functional boundary maps was incorporated into BAY using the weighted line site method. This algorithm was tested with simulated PET projection data generated from an MRI-based three-dimensional brain phantom, including the effects of resolution, attenuation, scatter and Poisson noise. The reconstructed images were evaluated in terms of root mean square distance (RMSD) from the true image. This method improved RMSD by 39.6%, 33.5%, and 33.0% on average, compared to the filtered backprojection method, the maximum-likelihood expectation-maximization method and BAY method, respectively. Our preliminary results suggest that incorporation of both anatomical and tissue classification information into the image reconstruction process is useful for improving the qualitative and quantitative accuracy of PET images. (author)

[en] Objective: To evaluate the clinical efficacy of ¹²⁵I seed-strip combined with biliary stent implantation in treating malignant obstructive jaundice. Methods: During the period from June 2011 to October 2013, a total of 40 patients with malignant obstructive jaundice were admitted to authors' hospital. Biliary stent implantation was employed in 18 patients (control group) and ¹²⁵I seed-strip combined with biliary stent implantation was earned out in 22 patients (study group). Perculaneous transhepatic cholangial drainage (PTCD) was performed in all patients of both groups. Results: The mean biliary patency time of the study group and the control group was (8.7 ± 0.7) months and (6.2 ± 0.4) months respectively, and the difference between the two groups was statistically significant (P < 0.05). The mean survival time of the study group and the control group was (11.4 ± 0.8) months and (8.7 ± 0.5) months respectively, and the difference between the two groups was statistically significant (P < 0.05). No statistically significant difference in short-term efficacy and incidence of complications existed between the two groups (P > 0.05), although significant difference in long-term efficacy existed between the two groups (P < 0.05). Conclusion: The survival time and the biliary patency time in the study group were obviously longer than those in the control group. Further clinical study on the prolongation of biliary patency time for malignant obstructive jaundice is needed. (authors)

[en] Objective: To explore the best time point for the ipsilateral hepatocellular apoptosis and the contralateral hepatic hypertrophy after selective portal vein embolization (SPVE) in rabbit. Methods: In a randomized study design, forty rabbits were divided into 5 groups with 8 rabbits per-group, including one as the control and the other 4 were treated with SPVE during open surgery. the rabbits were killed postoperatively, in 3, 7, 14, 21 days respectively after the embolization. The hepatic lobes volume, the ipsilateral hepatocellular necrosis rates and apoptosis index, and liver functions were determined as well. Results: In the treatment groups, the average amount of the right liver volumes decreased from 46.4 cm³ preoperatively to 46.0, 44.4, 42.0, 39.7 cm³ in groups of 3, 7, 14, 21 days postoperatively; meanwhile, the left liver volumes increased from 54.0 cm³ preoperatively to 54.5, 56.3, 61.7, 63.9 cm³ respectively during 3, 7, 14, 21 days after the procedures. The rates of future remaining live volumes (FRLV) increased from 53.8% preoperatively to 54.2%, 55.9%, 59.0%, 61.0% at 3, 7, 14, 21 days postoperatively. The apoptosis indexes of hepatocells from group A to E were 8.1%, 12.2%, 19.4%, 20.1%, 14.2% respectively. Conclusions: SPVE leads to atrophy of the ipsilateral hepatic lobe and hypertrophy of contralateral lobe, indicating that hepatocytes undergone apoptosis, rather than necrosis. The time point is 7 to 14 days. (authors)

[en] Objective: To estimate the effective radiation annual dose level of residents caused by the well which gross α activity is beyond the national standard, and evaluate the health affection on residents that ingesting the well water consistently. Methods: Estimates of the effective annual dose and evaluate of the health effect by using the related knowledge of radiation dosimetry. Results: If residents drink the well water for long-term, the effective annual dose they arcumulated ranges for 0.22∼0.80 mSv/a and the mean value is 0.44 mSv/a, single radionuclide ²²⁶Ra and the contribution to the annual dose is estimated to be 0.10∼0.35 mSv/a which were higher than the drinking water guidance level 0.1 mSv/a. Conclusion: The content of ²²⁶Ra is high in the well and exceeds the guidance level of radioactive nuclide concentration recommended by WHO health effects caused by drinking water. ²²⁶Ra is a highly toxic radioactive species. If residents drinking it for long-term it will cause hazards on their health. (authors)

[en] In this paper, the changes of mechanical properties and surface properties of QF-162 polyurea coating after soaking in seawater for 120 days were studied. The changes of internal chemical bonds before and after coating corrosion were observed with Fourier Transform infrared spectroscopy (FT-IR). The results of mechanical properties study showed that after soaking in seawater for 120 days, the tensile strength of QF-162 polyurea coating decreased by 4.23%, the elongation at break decreased by 7.10%. The hardness changed slightly and Shore A hardness decreased by 3.23%. Surface performance results showed that the contact angle of QF-162 polyurea coating decreased with the increase of soaking time, and the surface energy showed a trend of increase. After soaking 120 days, the contact angle of polyurea coating decreased by 6.08%, surface energy increased by 15.83%. FT-IR microscopic results showed that there was no obvious fracture phenomenon in the internal chemical bonds of QF-162 polyurea coating and the coating had good anti-corrosion to seawater soaking. (paper)

[en] Objective: To understand the levels of radon concentration and γ radiation in the stations of Nanning Metro Line 1, and evaluate the radiation dose exposed to the subway staff. Methods: With scintillation flask and instantaneous monitoring instrument, the radon concentrations and the gamma instantaneous dose rates of Nanning Metro Line 1 were determined, and the data were analyzed and compared. According to the evaluation method recommended by United Nations Scientific Committee on the effects of atomic radiation, the annual effective radiation dose caused by radon and its progeny and γ radiation, and its health effects on subway workers were estimated. Results: the average radon concentration in Nanning Metro Line 1 was 18.5 Bq/m³; the average annual effective dose of radon and its decay products was 0.133 mSv/a; the average gamma radiation level was 0.097 u Sv/h; the annual effective dose exposed to subway workers was 0.194 mSv/a, and the combined dose was 0.327 mSv/a. Conclusion: Radon concentration level and γ instantaneous dose rate of Nanning Metro Line 1 will not cause an additional health deterioration on the subway staff and passengers. (authors)

[en] Objective: To investigate and master the radioactivity level of artificial radionuclide ¹³⁷Cs in Guangxi food and estimate the committed effective dose of dietary intake in different populations and assess the health risk. Methods: According to the national standards GB/T 16145-1995 'gamma ray spectrum analysis method for radionuclide in biological samples' and GB/T 11713-2015 'general method of gamma spectrometry analysis of high purified Ge', 202 samples of 7 categories (including grain, vegetables, seafood, freshwater fish, poultry meat, tea and milk powder) collected in Guangxi were monitored and determined. The data were compared and evaluated. Results: The detection rate of ¹³⁷Cs was 91.6 % (185/202), the specific activity ranged from 0.011 to 0.931 Bq/kg (for fresh weight). The content of ¹³⁷Cs in tea was the highest in the samples, and the mean value in tea was 0.263 ± 0.067 Bq/kg and ranged from 0.164 to 0.735 Bq/kg. The average annual committed effective dose by ¹³⁷Cs intake for school-age infants, children, young men/male adult and young women/female adults was 0.141 μSv/a, 0.189μSv/a, 0.251 μSv/a and 0.152 μSv/a, respectively. The risk of lifetime cancer caused by ¹³⁷Cs intake was (0.74 ∼ 1.33) × 10-6. Conclusion: ¹³⁷Cs radioactivity level in Guangxi food is far below the national standard limit, the dose burden for the population is slight and it will not affect human health. (authors)

[en] Objective: To investigate radioactivity levels in the main agriculture products around a uranium mine in Northern Guangxi. Methods: The agriculture products and soil samples were collected and analyzed by using HPGe gamma ray spectrometer. Results: The specific activity of ²²6^Ra in radish (including leaf), radish leaves and radish, collected in one place, were 45.0, 66.7 and 32.3 Bq/kg, respectively. Those of ²²⁶Ra and ²³⁸U in the radish soil collected in the same place were 19672 and 85917 Bq/kg, respectively. The transfer coefficients of soil-to-radish and soil-to-leaves were 1.61 × 10^-3 and 3.40 × 10^-3, consistent with those reported in relevant literature. Radioactivity levels in agricultural products in another survey was in consistence with those in the national survey for food products. Radioactivity levels in soil elsewhere near the radish site was consistent with the results of the national soil radioactivive background survey. Conclusions: The soil in this place has been contaminated by the nearby uranium mine. It is important to investigate this place further and take the necessary measures. (authors)

[en] Objective: To investigate and master food radioactivity background levels in the area around the FangChengGang Nuclear Power Plant before operation. And the internal doses of local residents by ingestion were estimated. The work aims to accumulate baseline data for nuclear accident emergency response and health impact assessment, and to provide a scientific basis for the government to formulate emergency measures for nuclear accidents. Methods: HP-Ge gamma spectrometer was used to detect and analyze the food collected in the range of 30 km around the nuclear power station. Results: ¹³⁷ Cs, ²³⁸U, ²²⁶Ra, ²³²Th and ⁴⁰K were detected in food samples. Their average radioactivity was (0.063 ± 0.252), (0.146 ± 0.172), (0.326 ± 0.678 ), (1.080 ± 2.139 ), (107.7 ± 130.5) Bq/kg; Their Specific activity range were (0.008∼2.498 ), (0.469∼0.821), (0.007∼3.423 ), (0.012∼9.812), (30.52∼672.1) Bq/kg. Conclusion: The radioactivity concentration of food in the surrounding area of Fangchenggang nuclear power station is within the national standard limit. The committed effective dose of all radionuclides by ingestion food is 197.16 μSv/a, and man-made ¹³⁷Cs contributes to 0.158 μSv/year. Its additional dose to the public is below the national limit and will not affect the health of the human body. (authors)

[en] Objective: To investigate the entrance surface doses to the patients undergoing diagnostic X-ray examinations in Guangxi. Methods: A total of 2236 patients who have received diagnostic X-ray examinations were investigated at 25 randomly selected hospitals at different levels where dthermoluminescence dosimeters were used to measure the entrance surface doses in different hospitals with different equipment and different positions. Results: The entrance surface dose from X-ray imaging, computed radiography (CR) and digital radiography (DR) were in the range of 0.08-31.51, 0.11-4.25 and 0.05-35.63 mGy, respectively. The entrance doses to abdomen (AP), pelvis (AP), head (LAT), head (PA), chest (PA), chest (LAT), thoracic vertebra (AP), thoracic vertebra (LAT), lumbar vertebra (AP), lumbar vertebra (LAT) were 0.08-19.53, 0.15-18.78, 0.08-9.87, 0.06-9.24, 0.05-2.71, 0.13-2.93, 0.15-19.01, 0.07-25.33, 0.16-27.23, and 0.11-35.63 mGy, respectively. Conclusions: The average dose to patients from X-ray diagnosis in Guangxi was in accordance with the relevant standards, but DR could partly lead the chest (PA) dose to exceed the guidance levels of medical exposure. (authors)