Objective To introduce a finger leaf design that is applied to dual layer MLCs.Methods An optimization model was firstly constructed to describe the problem of determining leaf end shapes,and the corresponding problems were then solved by the simplex search method or the simulated annealing technique.Optimal parameters for arc shapes of leaf end projections were obtained,and a comparison was done between optimized MLCs and conventional MLCs in terms of field conformity.The optimization process was based on 634 target fields selected from the patient data base of a treatment planning system.Areas of these fields ranged from 20.0 to 602.7 cm with a mean and its standard deviation of (125.7 ±0.0) cm~2.Results The optimized leaf end shapes projected to the isocenter plane were semicircles.With the finger leaf design,the total area of discrepancy regions between MLC fields and target fields was reduced by 32.3% .Conclusions The finger leaf design improves the conformity of the MLC shaped fields to the desired target fields.

Purpose: To analyze factors which influence the precision & accuracy of target positions in Alderson Head phantom and(or) patients.Materials and Methods: A target position simulator was used to determine the precision and accuracy of target localization while Alderson head phantom used to determine the overall precision and accuracy through the treatment procedure.Results: The overall precision and accuracy through the treatment procedure was found to be 1.72?0.60mm, and its contribution from CT localizing step, which was 1.4?0.3mm。Conclusion: Since there are more factors related to patients' treatment, the precision and accuracy of simulating in Alderson phantom is the best estimate for patient treatment.

Niclosamide is the most commonly used molluscicide. Along with a lot of application of niclosamide more and more scientists studied its toxic effects to aquatic organisms as well as the related cell toxicity mechanism. This paper summariz?es the toxicity on cell organelle enzyme cell signaling pathway and genetic material caused by niclosamide and puts for?ward the future research direction.

Objective To design leaf patterns for Multileaf Collimator(MLC)routine quality assurance(OA)with a 2D diode array.Methods According to the detector distribution characteristic of the 2D diode array and basillg on the"picket fence"pattern,design the"stepwise"pattern.For each diode involving MLC QA,a calibration curve of relative output versus leaf positioning error was measured through delivering a set of patterns with different intentionally introduced positioning errors.When this proposed technique was delivered,the referenced patterns were exposed,and the calibration curves were used as a mean to quantitative determination of the leaf possible positioning errors through the detector readings.Results Compared with the"picket fence"pattern,the"stepwise"pattern not only had a high detecting efficiency,but also increased the dosimetric sensidvity to leaf positioning error.A 1 mm Ieaf positioni.error corresponds to a dose variation of 25% for the"stepwise"pattern,while for the"picket fence"pattern the same positioning error just causes a 17% dose vailation.Conclusions The new"stepwise"pattern is more efficient to be carried out,and more sensitive to sub-millimeter changes of leaf positioning.

Objective To evaluate the improvement of cone beam CT (CBCT) image quality by using bewtie filter (F_1) and water calibration. Methods First the multi-level gain calibration of the detector panel with the method of Cal_2 calibration was performed, and the CT images of CATPHAN503 with F_0 and bowtic filter were collected, respectively. Then the detector panel using water calibration kit was calibrated, and images were acquired again. Finally, the change of image quality after using F_1 and (or) water calibration method was observed. The observed indexes included low contrast visibility, spatial uniformity, ring artifact, spatial resolution and geometric accuracy. Results Comparing with the traditional combination of F_0 filter and Cal_2 calibration, the combination of bowtie filter F_1 and water calibration improves low contrast visibility by 13.71%, and spatial uniformity by 54. 42%. Water calibration removes ring artifacts effectively. However, none of them improves spatial resolution and geometric accuracy. Conclusions The combination of F_1 and water calibration improves CBCT image quality effectively. This improvement is aid to the registration of CBCT images and localization images.

Objective:Through the discussion on the purchasing mode of hospital equipment in China, fully understand the advantages and disadvantages of various procurement ways, choose reasonable acquisition method, optimize acquisition method, standardize the procurement management objective.Methods: By using the method of analogy, comparison of the four main acquisition methods. By the comparative analysis, the scope of each purchase way was confirmed. Results: Public bidding was better for more than 500000 yuan or the treasury payment items, competitive negotiation approach applies to 50000 yuan-500000 yuan purchase project. Consultation approach can be applied to 50000 yuan purchase project. Information project procurement preferred to methods of government procurement.Conclusion: Reasonable choices of purchasing and proper optimization has significant meaning for equipment purchasing and management in hospital.

Objective To investigate the molluscicidal effect of 5%niclosamide ethanolamine granules against Oncomela-nia hupensis in a marshland field. Methods The 5%niclosamide ethanolamine granules were sprayed at a dose of 40 g/m2 on 3 snail-breeding marshlands in Yangzhong City of Jiangsu Province to assess its field molluscicidal actions while 26%suspension concentrate of metaldehyde and niclosamide MNSC) at a dose of 4 g/m2 and fresh water served as controls. Results After seven days spraying, 5%niclosamide ethanolamine granules resulted in a of snail mortal85.42%ity while the mortality rates of snails were 82.35% and 2.86% in the MNSC and water control groups respectively. Conclusion 5% niclosamide ethanol-amine granules exhibit a high molluscicidal activity which is suitable to be used in the mashland.

Biogenic molluscicides refer to the use of plants,animals and micro?organisms or their metabolites,and synthesis biomimetic molluscicides to kill Oncomelania hupensis snails. With the rapid development of science and technology,new bio?genic molluscicides are continuously emerging and the category also continues to expand. According to the molluscicidal active ingredient and sources,at present,the biogenic molluscicides with in?depth studies include plant?derived molluscicides,micro?organism molluscicides,microbial metabolite molluscicides and animal molluscicides. This paper reviews the advances in the re?searches of biogenic molluscicides in recent years.

BACKGROUND: Fibronectin serves not only as the supporter for cells,but also as an important intracellular linkage, possessing opsonic-like functions. It can promote the phagocytic function of mononucleophages and the repair in inflammation and trauma.OBJECTIVE: Type O plasma was freshly obtained from healthy males in search of the optimal preparation method for lower sampling, convenient and higher-yielding of fibronectin.DESIGN: Open experiment.SETTING: Institute of Traumatic Surgery, Fourth Affiliated Hospital of Guangzhou Red Cross Hospital, Jinan University.MATERIALS: This experiment was carried out in the Institute of Traumatic Surgery of Guangzhou Red Cross Hospital between July 2000 and July 2002. The major materials consisted of type O fresh plasma from healthy males, gelatin, sepharose 4B activated with cyanogen bromide,sephadex G-25, urea, and trishydroxymethylaminomethane.METHODS: Affinity column constituted by gelatin coupling with sepharose 4B activated with cyanogen bromide was used to purify fibronectin. ① Human plasma was added: 150 mL type O plasma was freshly obtained from healthy males and added into the column once by 25 mLat an interval of 20 minutes, the speed of flow was 3.5 mL/min. ② Removing mixed protein: the column was rinsed by Tris-sodium citrate equilibrium liquid (pH 7.5) until the absorbency of flow-out fluid decreased to ＜ 0.02 at 280 nm. Again lmol/L NaCl containing Tris-sodium citrate was used to wash off other mixed proteins. ③ Collecting fibronectin: the column was rinsed by urea-Trispurge Fluid (3 mol/L) to collect fibronectin.④ Removing urea from fibronectin collection: fibronectin collection liquid was filtrated by Sephade G-25 to remove urea. ⑤Disinfection: 0.22 μmgermtight filter was used for disinfection.MAIN OUTCOME MEASURES: ①Results of sodium dodecyl benzene sulfonate-polyacrylamide gel electrophoresis. ② The influence of retention time on the yield of purified fibronectin. ③ The influence of plasma quantity on the yield of purified fibronectin.RESULTS: ① Results of sodium dodecyl benzene sulfonate-polyacrylamide gel electrophoresis: The density of separation gel and condensed gel was 7% and 3%, respectively; fibronectin was electrophoresized into single protein lane. ② The influence of retention time on the yield of purified fibronectin: The yield of fibronectin was (65.24±3.45) %, (74.77±4.05) %,(86.99±4.10) %, and (80.47±3.75) %, respectively, when the loading amount of fibronectin was 150 mL with non-retention time and retention time of 10, 20 and 30 minutes. ③ The influence of plasma quantity on the yield of purified fibronectin: The yield of fibronectin was (72.56±3.63) %,(77.61±3.14) %, (86.99±4.12) %, and (74.67±3.05) % when the column retention time was controlled at minute 20 with the loading amount of 100,130, 150 and 180 mL, respectively.CONCLUSION: In a given column volume of gelatin, the quantity of purified fibronectin was closely related with the plasma retention time in column and the total loading amount of plasma. As a result, the optimal loading amount of plasma was 150 mL, and the retention time was 20 minutes.The preparation method, herein, has been proved to require small amounts of plasma and yield large amounts of fibronectin.

ObjectiveBoth kilovolt (KV) cone-beam computed tomography (CBCT) and KV radiography can determine set-up errors for patients with head-and-neck cancer.This study is to compare their performance.Methods16 patients with head and neck cancer were enrolled in this study.There were 160 sets of CBCT and corresponding orthogonal radiography images.Through registration of CBCT images with the planning CT images,and registration of radiography images with the digitally reconstructed radiographs,translational set-up errors were determined along left-right (x),super-inferior (y),and anterior-posterior (z) directions.Pearson correlation analysis was performed to evaluate the correlation of the set up errors determined by the two methods,and Bland-Altman plot analysis was used to assess the coincidence of these two methods.ResultsThe Pearson coefficient of correlation along all three directions was less than 0.01,and R2 was 0.95,0.84,0.81 on x,y,z,respectively.That means high correlation for two methods.The Bland-Altman plot analysis showed that the 95％ agreement limits of agreement were within preset 2 mm tolerance (x[ 1.3mm,- 1.2mm],y[ 1.6mm,- 1.1mm],z[0.8mm,-1.4 mm] ),which indicates an agreement exists for two methods.ConclusionsFor determination of set-up errors for patients with head and neck cancer,KV radiography is equivalent to CBCT.Considering CBCT delivers higher dose than KV radiography,but provides more soft tissue information.We suggest to use these two methods combinative in clinic.