阳江高本底辐射地区的个人外照射剂量估算和人员的剂量分组

目的为了更好地进行剂量与效应关系的分析，将高本底辐射地区（ＨＢＲＡ）的人员按村平均的环境γ外照射水平及各自的居留因子估算的村平均有效剂量分成“高”、“中”、“低”三个剂量组和相邻的正常本底地区（ＣＡ）的一个对照组。方法在进行辐射剂量与效应关系的研究时，采用环境γ外照射辐射水平（卧室、室内、外和田野）的测量和个人累积剂量（ＴＬＤ）的两种测量方法给出ＨＢＲＡ和ＣＡ各组人员平均有效剂量。结果这两种方法的测量结果：ＨＢＲＡ分别是２１１８６×１０－５Ｓｖ·ａ－１和２０６７５×１０－５Ｓｖ·ａ－１；ＣＡ分别是６８６０×１０－５Ｓｖ·ａ－１和６７１１×１０－５Ｓｖ·ａ－１。两种不同测量方法所估算的村平均有效剂量有很好的相关性，它们的直线回归方程为Ｙ＝０．９３３７Ｘ＋６．０４４４，相关系数ｒ＝０．９９４９。结论环境γ外照射辐射水平测量方法的总的不确定度为１５％。作者分析了引起人员误分组的原因，并认为人员的误分组的可能性不会超过１％，它不会影响分组作用的有效性。

Estrus Grouping in Sheep Treated with Melengestrol Acetate （MGA）

In Mexico the predominant sheep production system is the semi-extensive with grazing during the day and stanchion afternoon and night. Sheep herd are usually small, approximately 10 to 75 heads. The objectives of these systems are savings and marketing of lambs. Meat is the main economic product of this kind, the breeding is long, which do not control the delivery dates and ages of the sheep are not uniform, affecting the demand for the local market （for the months of June and December）. Therefore the aim of this work was implement a technology that allows the grouping of the estrus and therefore group deliveries for batches of uniform lambs. This technology was designed to suppress the estrus and heifers growth promoter of feedlots, this technology is melengestrol acetate （MGA） which is a synthetic progesterone oral administration that it is easy to manage in the food or alone, economic that it does not represent any risk for sheep females of abortive type, evaluating the effect of the MGA on rate of estrus and gestation in sheep. Work developed in the municipality of Charo from Michoac^in State, M6xico, 20 hair sheep divided in two groups of 10 female, group one treated with MGA and group tow was the whitens. 100% of the sheep treated with a dose of 0.45 mg MGA/head/day for 17 days orally, presented estrus grouped in 5-10 days; however only 50% of the sheep of the witness group presented estrus. In the experimental group there was a rate of 70% with a gestation difference time of no more than ten days gestation and witness group 50%. The MGA is an efficient alternative for the producer of sheep when administered 0.45 mg MGA/head/day for 17 days because inhibits the estrus and once withdrawn treatment manifests estrus synch with which get a rate of gestation elevated by natural riding.

Effect of carboxymethyl cellulose on dissolution kinetics of carboxymethyl cellulose-sodium carbonate two-component tablet

Sodium carbonate and carboxymethyl cellulose powders are compressed into two-component tablets with three mass ratios,97%:3%,95%:5% and 93%:7%.The dissolution tests for two-component tablets and reference pure sodium carbonate tablets are carried out at various temperatures.The dissolution process of each tablet is measured by electrical conductivity tracking method and the concentration of dissolved sodium carbonate is quanti fied with calibrated conductivity-concentration converting equation of sodium carbonate.The quanti fied dissolution data is fitted with both surface reaction model and diffusion layer model and the results clearly show that surface reaction model is suggested as the appropriate dissolution model for all measured tablets.Therefore,it is determined that carboxymethyl cellulose is a stable element to remain the dissolution mechanism of tablet unchanged.The dissolution rate constant quanti fied with surface reaction model presents that carboxymethyl cellulose-sodium carbonate two-component tablets obtain signi ficant higher dissolution rate constant than pure sodium carbonate tablet and higher proportion of carboxymethyl cellulose leads to apparent higher dissolution rate constant.The results prove for the usage of carboxymethyl cellulose in most practical applications at a relative low-level,the effect of carboxymethyl cellulose is effective and positive for two-component tablet to enhance the dissolution process and improve dissolution rate constant and this effect is speculated coming from its dynamic physical transforming process in water including dilation and conglutination.

Single-versus multi-fraction radiation treatment for metastatic spinal cord compression:functional outcome study

Objective:The optimal treatment of patients with metastatic spinal cord compression(MSCC) is still being debated.This randomized trial was planned to compare the functional outcome and its related prognostic factors,toxicity and in-field recurrence of the three schedules of radiotherapy.Methods:Two hundred and eighty five patients enrolled in the study of which 95 received 1 × 8 Gy,100 received 10 x 3 Gy and 90 received the radiation treatment of 20 × 2 Gy.Irradiation was performed with 6-10 Mv linear accelerators or cobalt-60 units by single posterior field or parallel opposed fields according to depth of irradiation spines.Premedication with dexamethasone was started from the first day of clinico-radiologic diagnosis till 4-5 days after the end of radiotherapy(RT) then tapered off during 10 days.Potential prognostic factors were evaluated with respect to functional outcome.Results:All groups were balanced for patient's characteristics and potential prognostic factors.No statistically significant difference was observed between the 3 groups as regard functional outcome and toxicity while single fraction was associated with higher in-field recurrences(22.8%) with statistically significant difference between the 3 groups(P = 0.01).Functional outcome was significantly better with younger age(≤ 60 y),Eastern Cooperative Oncology Group performance status(ECOG-PS) of 1-2,involved vertebra of 1-2,favorable tumor type,absence of visceral or other bone metastasis,decreased time of developing motor deficit before radiotherapy,long interval between cancer diagnosis to metastatic spinal cord compression,and normal ambulatory status.Conclusion:The three schedules provided similar functional outcome.Single-radiation dose was associated with higher in-field recurrence.To minimize treatment time and costs,the dose of 1 × 8 Gy is recommended for patients with poor predicated survival and 10 × 3 Gy for other patients.

Observation of Intensity-Modulated Radiotherapy with Different Fractionated Doses Used in 58 Cases with Astrocytoma

OBJECTIVE To analyze the therapeutic effects and side effects of intensity-modulated radiotherapy （IMRT） with different fractionated doses in treating astrocytoma.METHODS During a period from October 2001 to December 2006, 58 patients with astrocytoma were treated using IMRT. Based on the World Health Organization （WHO） classification, 32 of the 58 cases were grade-Ⅱ, 20 grade-Ⅲ and 6 grade-IV （glioblastoma multiforme, GBM）. Thirty-two of the 58 patients （3 with grade IV, 11 with grade Ⅲ, and the other 18 with grade II who were over 40 years） were treated with hyperfractionated IMRT （Hyper Fr IMRT）, and the other 26 patients were treated with standard fractionated IMRT （St Fr IMRT）.RESULTS The 1-, 3- and 5-year overall survival （OS） rates were respectively 86%, 52%, and 45%, and the 1-, 3- and 5-year progression-free survival （PFS） rates were respectively 77%, 38%, and 25%. Using an analytical hierarchy process it was shown that concerning the patients with grade II astrocytoma classified based on WHO grading, the therapeutic effect was much better in the group of Hyper Fr IMRT than in the St Fr IMRT group. There was no statistical significance of the differences in the OS and PFS rates between the 2 groups （P = 0.049 and P = 0.006）. The OS and PFS rates of the patients with grade-III astrocytoma were both higher in the group with Hyper Fr IMRT than in the St Fr IMRT group. However, there was no statistical significance of the differences between the 2 groups. Advanced RTOG grade-Ⅲ（radiation therapy oncology group, RTOG） neurotoxicity occurred only in 1 of the cases.CONCLUSION Compared with the St Fr IMRT, the Hyper Fr IMRT may help to prolong the survival of patients with astrocytoma.

An Assessment of Ingestion Dose due to the Intake of ^210Po and ^210Pb through Drinking Water of Eloor, Ernakulam District, Kerala, India

The present study aims at measuring the activity concentrations of ^210Po and ^210Pb in the potable water of Eloor, a major industrial belt in the Ernakulam district of Kerala, India with an aim of evaluating resultant ingestion dose to critical population. The industrial units located in Eloor discharge their treated effluents into the river Periyar and the surrounding environs. The two major industries of interest with respect to NORMs are the fertilizer plant, processing rock phosphate and the monazite processing plant, which had been in operation for the last 50 years. For sampling, Eloor region was divided into four zones and a total of 55 water samples from different locations were collected and analysed as per standard analytical procedure manual of BARC. The ^210Po concentration ranged between 0.3 to 4.7 mBq.L^-1 and ^210Pb ranged from 0.6 to 4.3 mBq.L^-1. All values are well below the limit of 0.1 Bq.Ll recommended by World Health Organization. Statistical analysis shows a good co-relation between ^210Po and ^210Pb in the water samples analyzed and the mean activity concentration is found to be relatively high in the western region of Eloor compared to other regions. The annual effective dose equivalent to man from ^210Po and ^210Pb through drinking water intake were estimated and found to be 1.13 μSv.y^-1 and 0.99 μSv.y^-1 respectively, which is well below the reference level of committed effective dose （100 μSv.y^-1） recommended by WHO.

阳江天然放射性高本底地区剂量调查的新进展

作者报告了阳江天然放射性高本底地区环境辐射水平的测量和居民吸收剂量估算方面近几年的调查结果。根据辐射流行病学调查的需要，将高本底地区因外照射所致居民的年吸收剂量，按村庄平均分成高、中、低３个组。对照地区将根据分组人数的配对要求，仅在以前调查过的对照地区选部分村庄。高本底地区有３８４个村庄，对照地区有１４２个村庄。现阶段调查的目的是要给出调查地区每个人员的个人累积剂量。为此，自１９９１年以来，已连续４次开展了个人和环境中的累积剂量调查。回收并能提供实际测量值的人数，高本底地区和对照地区分别为３９００人和１３０４人，他们的平均年个人累积剂量分别是２１０．９８×１０￣（－５）Ｇｙ·ａ￣（－１）和７０．１７×１０￣（－５）Ｇｙ·ａ￣（－１）。高本底地区的女性吸收剂量稍比男性高（Ｐ＝０．１８），０～７岁组的年吸收剂量明显高于其他四个年龄组（Ｐ＜０．０５），４１～６０岁年龄组低于其他４个年龄组（Ｐ＜０．０５），而８～１６，１７～４０和６０岁以上年龄组间差异无显著性（Ｐ＞０．０５）。对照地区的性别和各年龄组之间均无明显差异（Ｐ＞０．０５）。高本底地区的居民以居住在砖瓦结构房屋的个人剂量非常明显高于居住在其他建筑材料类型的?

Laboratory Testing of Magnetic Tracers for Soil Erosion Measurement

Soil erosion, which includes soil detachment, transport, and deposition, is one of the important dynamic land surface processes. The magnetic tracer method is a useful method for studying soil erosion processes. In this study, five types of magnetic tracers were made with fine soil, fly ash, cement, bentonite, and magnetic powder （reduced iron powder） using the method of disk granulation. The tracers were uniformly mixed with soil and tested in the laboratory using simulated rainfall and inflow experiments to simulate the interrill and rill components of soil erosion, in order to select one or more tracers which could be used to study detachment and deposition by the erosive forces of raindrops and surface flow of water on a slope. The results showed that the five types of magnetic tracers with high magnetic susceptibility and a wide range of sizes had a range of 0.99-1.29 gcm-3 in bulk density. In the interrill and rill experiments, the tracers FC1 and FC2 which consisted of fly ash and cement at ratios of 1：1 and 2：1, respectively, were transported in phase with soil particles since the magnetic susceptibility of sediment approximated that of the soil which was uneroded and the slopes of the regression equations between the detachment of sediment and magnetic tracers FC1 and FC2 were very close to the expected value of 20, which was the original soil/tracer ratio. The detachment and deposition on slopes could be accurately reflected by the magnetic susceptibility differences. The change in magnetic susceptibility depended on whether deposition or detachment occurred. However, the tracer FS which consisted of fine soil and the tracers FB1 and FB2 which consisted of fly ash and bentonite at ratios of 1：1 and 2：1, respectively, were all unsuitable for soil erosion study since there was no consistent relationship between sediment and tracer detachment for increasing amounts of runoff. Therefore, the tracers FC1 and FC2 could be used to study soil erosion by water.