Objective To explore the diagnostic value of endoscopic ultrasonography(EUS)for the minimal submucosal invasion of early gastrointestinal tumor. Methods A total of 242 patients with early gastrointestinal tumor,who underwent endoscopic submucosal dissection,were retrospectively analyzed. The accuracy of EUS diagnosis was calculated based on postoperative histopathological findings as the golden standard,and influencing factors were also analyzed. Results Overall diagnostic accuracy of EUS for sub-mucosal invasion of early gastrointestinal tumors was 72. 3%(175/ 242),with an overstaging rate of 21. 5%(52/ 242)and an understaging rate of 6. 2%(15/ 242).Tumor size(P = 0. 018)and location(P = 0. 005) had significant effects on the diagnostic accuracy of the minimal submucosal invasion of early gastrointestinal tumor by EUS. The overstaging rate in the lesion length of diameter>3 cm was higher than those of 3 cm or less[27. 0%(33/ 122)VS 15. 8%(19/ 120),P = 0. 807],the overstaging rates of early colonrectal and gastric cancer were also significantly higher than the understaging rate[ Colonrectum:12. 2%(9/ 74)VS 2. 7%(2/ 74),P= 0. 028;Stomach:26. 9%(28/ 104)VS 2. 9%(3/ 104),P = 0. 000]. Conclusion Endoscopic ultrasonography is of diagnostic value for the invasion depth of early cancer in gastrointestinal tract. However,precaution should be taken in large lesions and the tendency of overstaging in gastrointestinal tract.

Objective To determine the effects and dosage of N?acetylcysteine( NAC) in the im?provement of the visibility in esophagogastroduodenoscopy( EGD) . Methods A prospective randomized con?trolled study was performed on 193 patients scheduled for EGD from November 2014 to July 2015 were ran?domized into five groups using digital table. In group A, 100 mg dimethicone and 2 g NaHCO3 were given. In group B,100 mg dimethicone, 2 g NaHCO3 and 20 000 U pronase were given. Group C received 100 mg dimethicone, 2 g NaHCO3 and 200 mg NAC. Group D received 100 mg dimethicone, 2 g NaHCO3 and 400 mg NAC and group E 100 mg dimethicone, 2 g NaHCO3 and 600 mg NAC.The agents were dissolved in 100 ml water for each patient.Endoscopy was completed by one endoscopist and the score of image visibility assessment was completed by 2 other endoscopists. The 3 endoscopists were unaware of grouping. The total scores, the time of washing, the time of examination and complications were compared and analysed. The total image scores of group A, B, C,D and E were 30?83±3?78, 35?69±2?88, 33?16±3?90, 34?95±3?46 and 36?76±2?91, respectively. Group A was the lowest(P<0?05),followed by group C(P<0?05). There were no differences among group B,D, and E(P>0?05).Images that were scored 3 were the most in group E.The washing times of each group were 38?00±19?10, 17?03±11?44, 15?92±10?81, 15?78 ±10?24 and 15?55±9?69, and the examination times of each group were 13?49±2?49, 9?41±1?86, 9?08± 1?80, 8?73±1?91 and 8?78±1?79 minutes.Group A was the longest in these two indices(P<0?05). There were no significant differences among group B, C, D and E ( P<0?05) . There were no significant differences in adverse effects among groups after EGD( P>0?05) . Conclusion The preoperative NAC can improve the visibility in EGD. The best dose is 600 mg, whose effects and safety were similar to those of 20 000 U, but yield to less washing time and the examination time in EGD.

The deoxyribonucleic acid (DNA) molecule damage simulations with an atom level geometric model use the traversal algorithm that has the disadvantages of quite time-consuming, slow convergence and high-performance computer requirement. Therefore, this work presents a density-based spatial clustering of applications with noise (DBSCAN) clustering algorithm based on the spatial distributions of energy depositions and hydroxyl radicals (·OH). The algorithm with probability and statistics can quickly get the DNA strand break yields and help to study the variation pattern of the clustered DNA damage. Firstly, we simulated the transportation of protons and secondary particles through the nucleus, as well as the ionization and excitation of water molecules by using Geant4-DNA that is the Monte Carlo simulation toolkit for radiobiology, and got the distributions of energy depositions and hydroxyl radicals. Then we used the damage probability functions to get the spatial distribution dataset of DNA damage points in a simplified geometric model. The DBSCAN clustering algorithm based on damage points density was used to determine the single-strand break (SSB) yield and double-strand break (DSB) yield. Finally, we analyzed the DNA strand break yield variation trend with particle linear energy transfer (LET) and summarized the variation pattern of damage clusters. The simulation results show that the new algorithm has a faster simulation speed than the traversal algorithm and a good precision result. The simulation results have consistency when compared to other experiments and simulations. This work achieves more precise information on clustered DNA damage induced by proton radiation at the molecular level with high speed, so that it provides an essential and powerful research method for the study of radiation biological damage mechanism.
Algorithms ; Computer Simulation ; DNA ; radiation effects ; DNA Damage ; Linear Energy Transfer ; Monte Carlo Method ; Protons

Aiming at the disadvantages of traditional direct aperture optimization (DAO) method, such as slow convergence rate, prone to stagnation and weak global searching ability, a gradient-based direct aperture optimization (GDAO) is proposed. In this work, two different optimization methods are used to optimize the shapes and the weights of the apertures. Firstly, in order to improve the validity of the aperture shapes optimization of each search, the traditional simulated annealing (SA) algorithm is improved, the gradient is introduced to the algorithm. The shapes of the apertures are optimized by the gradient based SA method. At the same time, the constraints between the leaves of multileaf collimator (MLC) have been fully considered, the optimized aperture shapes are meeting the requirements of clinical radiation therapy. After that, the weights of the apertures are optimized by the limited-memory BFGS for bound-constrained (L-BFGS-B) algorithm, which is simple in calculation, fast in convergence rate, and suitable for solving large scale constrained optimization. Compared with the traditional SA algorithm, the time cost of this program decreased by 15.90%; the minimum dose for the planning target volume was improved by 0.29%, the highest dose for the planning target volume was reduced by 0.45%; the highest dose for the bladder and rectum, which are the organs at risk, decreased by 0.25% and 0.09%, respectively. The results of experiment show that the new algorithm can produce highly efficient treatment planning a short time and can be used in clinical practice.