Objective:To investigate the influence of contrast-enhanced computed tomography(CECT)on dose calculation in magnetic resonance imaging(MRI)-guided online adaptive radiotherapy(oART)based on the electron density(ED)assignment method for rectal cancer.Methods:A retrospective analysis was conducted on the medical data of 15 patients with locally advanced rectal cancer at middle-low segments,who admitted to the Chinese PLA General Hospital between December 2023 and April 2025.All patients underwent both plain computed tomography(PCT)and CECT scans during location.The average HU and ED value of all organs that were extracted from PCT and CECT images in the treatment plan system were obtained,and the influences of contrast agent of intake on image characteristics of the structure of each organ(small intestine,femoral head,bladder)were analyzed.PCT was used as referred image to design reference plan(Pref).The synthetic CT(sCT)was simulated and generated on the basis of PCT and CECT,respectively.The beam flow field that was same with Pref was used to recalculate dose on sCT,and then,the online plan(PPCT)based on PCT,and the online plan(PCECT)based on CECT were obtained,respectively,which can simulate the online dose calculation of MRI-guided online adaptive radiotherapy(oART).The Pref was used as reference to compare dosimetric parameters for target region and organ at risk(OAR)through dose volume histogram(DVH)and planed evaluation indicators.Additionally,three dimension(3D)slicer software was used to perform γ analysis for the results of dose distribution,and explore the differences among PPCT,PCECT and Pref on dose distribution.Results:In terms of image characteristics,the HU values of soft-tissue organs(intestine,bladder,spinal cord,soft tissue)and planning target volume(PTV)in CECT were higher than those in PCT,and the differences of them were statistically significant(Zintestines=-2.188,Zbladder=-3.196,tspinal cord=-3.767,tsoft tissue=-10.083,tPTV=-4.693,P<0.05),while its influence was less on bone tissue.The statistical results of ED were consistent with those of HU.Regarding to dosimetric parameters,there was no statistically significant difference in target coverage rate between PPCT and Pref(P>0.05),and the D50%of the PPCT[(2724.25±19.91)cGy]was higher than that of the Pref[(2718.99±21.13)cGy],and the difference was statistically significant(t=-3.679,P=0.002).However,the target coverage rate of PCECT was 94.65(94.04,95.27)%,and the difference of that between PCECT and Pref was statistically significant(Z=-2.158,P=0.031).For OAR,the differences of Dmax value of the small intestine,and the V20 of the left femoral head between PPCT and Pref were significant(Z=-2.556,-2.529,P<0.05).The differences of the Dmax of small intestine,and the D50%of bladder between PCECT and Pref were significant(t=-4.821,2.171,P<0.05).The comparative γ passed rates of PPCT,PCECT and Pref under the standards of 3 mm/3%and 2 mm/2%were all above 95%,and the differences were not significant(P>0.05).Conclusions:The influence of CECT on dose calculation in MRI-guided oART based on ED assignment method for rectal cancer is relatively small,which can be directly used in the design of reference plan,but the maximum dose of radiation-sensitive organs such as the small intestine should be paid attention.

Objective:To investigate the influence of contrast-enhanced computed tomography(CECT)on dose calculation in magnetic resonance imaging(MRI)-guided online adaptive radiotherapy(oART)based on the electron density(ED)assignment method for rectal cancer.Methods:A retrospective analysis was conducted on the medical data of 15 patients with locally advanced rectal cancer at middle-low segments,who admitted to the Chinese PLA General Hospital between December 2023 and April 2025.All patients underwent both plain computed tomography(PCT)and CECT scans during location.The average HU and ED value of all organs that were extracted from PCT and CECT images in the treatment plan system were obtained,and the influences of contrast agent of intake on image characteristics of the structure of each organ(small intestine,femoral head,bladder)were analyzed.PCT was used as referred image to design reference plan(Pref).The synthetic CT(sCT)was simulated and generated on the basis of PCT and CECT,respectively.The beam flow field that was same with Pref was used to recalculate dose on sCT,and then,the online plan(PPCT)based on PCT,and the online plan(PCECT)based on CECT were obtained,respectively,which can simulate the online dose calculation of MRI-guided online adaptive radiotherapy(oART).The Pref was used as reference to compare dosimetric parameters for target region and organ at risk(OAR)through dose volume histogram(DVH)and planed evaluation indicators.Additionally,three dimension(3D)slicer software was used to perform γ analysis for the results of dose distribution,and explore the differences among PPCT,PCECT and Pref on dose distribution.Results:In terms of image characteristics,the HU values of soft-tissue organs(intestine,bladder,spinal cord,soft tissue)and planning target volume(PTV)in CECT were higher than those in PCT,and the differences of them were statistically significant(Zintestines=-2.188,Zbladder=-3.196,tspinal cord=-3.767,tsoft tissue=-10.083,tPTV=-4.693,P<0.05),while its influence was less on bone tissue.The statistical results of ED were consistent with those of HU.Regarding to dosimetric parameters,there was no statistically significant difference in target coverage rate between PPCT and Pref(P>0.05),and the D50%of the PPCT[(2724.25±19.91)cGy]was higher than that of the Pref[(2718.99±21.13)cGy],and the difference was statistically significant(t=-3.679,P=0.002).However,the target coverage rate of PCECT was 94.65(94.04,95.27)%,and the difference of that between PCECT and Pref was statistically significant(Z=-2.158,P=0.031).For OAR,the differences of Dmax value of the small intestine,and the V20 of the left femoral head between PPCT and Pref were significant(Z=-2.556,-2.529,P<0.05).The differences of the Dmax of small intestine,and the D50%of bladder between PCECT and Pref were significant(t=-4.821,2.171,P<0.05).The comparative γ passed rates of PPCT,PCECT and Pref under the standards of 3 mm/3%and 2 mm/2%were all above 95%,and the differences were not significant(P>0.05).Conclusions:The influence of CECT on dose calculation in MRI-guided oART based on ED assignment method for rectal cancer is relatively small,which can be directly used in the design of reference plan,but the maximum dose of radiation-sensitive organs such as the small intestine should be paid attention.

ObjectiveTo investigate the contamination status of Staphylococcus aureus in food and the presence of enterotoxin genes in Jiading District， Shanghai， and to provide a basis for the prevention and treatment of foodborne Staphylococcus aureus disease. MethodsFrom 2021 to 2023， 15 types of food were sampled for S. aureus testing， and the presence of five enterotoxin genes， including sea⁃see， was tested in the strains. ResultsOut of 705 food samples， 88 （12.48%） were positive for S. aureus. S. aureus was detected in 12 of the 15 food types， with the three food types with the highest positive rates being cold noodles （45.00%）， raw poultry （26.25%）， and vegetable salads （20.00%）. The enterotoxin gene carriage rate was 32.95% in food strains. The carriage rates for sea， seb， and sec were 7.95%， 12.50%， and 14.77%， respectively. Neither sed nor see was detected. The detection rate of strains carrying two types of enterotoxin genes was 2.27%. The enterotoxin carriage rates in strains from vegetables， beverages， and raw meat were 57.14%， 40.00%， and 30.00%， respectively. ConclusionThe S. aureus detection rate in food in Jiading District is much higher than the national average. The enterotoxin gene carriage rates are high， with food strains carrying sea， seb， and sec， with sec being the most prevalent. There is a need to enhance monitoring of S. aureus and enterotoxins， especially in high-risk foods such as noodles， vegetables， and non-packaged beverages.

ObjectiveTo investigate the prevalence of Staphylococcus aureus in patients with diarrhea, and to analyze the genes carriage of enterotoxin in the strains of these patients in Jiading District, Shanghai. MethodsFrom 2021 to 2023, anal swabs of diarrhea outpatients from one sentinel hospital and nine community health service centers in different townships in Jiading District, Shanghai, were tested for Staphylococcus aureus, from which five enterotoxin virulence genes such as SEA, SEB, SEC, SED, and SEE were tested simultaneously. ResultsA total of 1 080 anal swabs were collected, 81 of which were tested positive for S. aureus, with a detection rate of 7.50%, and the detection rate of S. aureus was similar in patients with diarrhea from 2021‒2023. There was no statistically significant difference in detection rates between males and females (χ²=0.821, P=0.365). S. aureus detection rate was highest in infants and young children with diarrhea (29.51%), followed by 14.06% in the people aged between 4‒<31 years, and 2.99% in those aged ≥31 years. Significant differences were observed in the detection rate of S. aureus in the diarrhoeal patients from different townships of Jiading District(χ²=66.134,P<0.05). The carriage rates of the 5 enterotoxin genes, namely SEA, SEB, SEC, SED, SEE, were 13.58%, 14.81%, 11.11%, 7.41%, and 0, respectively. ConclusionThe prevalence of S. aureus among the patients with diarrhea in Jiading District is relatively stable but with distinct geographical patterns. Children and adolescents are high-risk groups. SEB were the dominant gene, followed by SEA.

Objective:To compare and study the improvement of different iterative reconstruction(IR)algorithms of the tomotherapy(TOMO)Radixact system on the image quality of megavoltage computed tomography(MVCT)imaging system,and the influence of that on the precision of automatic registration,and to explore the reconstruction algorithm that is suitable for clinical application.Methods:Using the MVCT imaging system to respectively scan the Tomo-Phantom HE phantom and the Catphan 604 phantom,and to analyze three groups of images were generated by three kinds of reconstruction algorithms,which included the Standard(STD)algorithm,IR General(IR-G)algorithm and IR Soft Tissue(IR-ST)algorithm,in MVCT image.The noise index(NI),uniformity index(UI)of image,modulation transfer function(MTF),low contrast visibility(LCV)index and contrast-to-noise ratio(CNR)of three groups of images were calculated respectively.The Lucy phantom was used to test the accuracy of automatic registration algorithm.The registration data of four dimensions,included left-right(X-axis),head-foot(Y-axis),vertical(Z-axis)and free rotation(Roll)around the Y-axis,were used to conduct verification analysis for the influences of them on the precision of automatic registration.Results:The NI values of IR-G and IR-ST reconstruction algorithms were respectively 39.58±0.10 and 14.62±0.26,which were better than 39.58±0.10 of STD algorithm,and the UI values of them were respectively 19.87±0.83 and 15.84±2.51,which were better than 24.51±1.81 of STD algorithm,and LCV values of them were respectively 2.50±0.03 and 1.74±0.11,which were better than 3.67±0.04 of STD algorithm.All of them appeared significant increase,but the resolution with high contrast of MTF were respectively 0.23 and 0.21,which were lower than 0.32 of STD.The overall image quality of the IR algorithms was superior to that of the STD algorithm.In the accuracy test of the automatic registration algorithm,the registration precisions of IR-G and IR-ST algorithms on Y-axis were respectively(0.360±0.142)mm and(0.245±0.050)mm,which were significantly higher than 0.145±0.136 of STD algorithm,and the differences of them were significant(Z=6.0,15.0,P<0.05).The differences of registration precisions of other directions were not significant(P>0.05).Conclusion:The IR algorithm has advantages in terms of noise,uniformity and resolution with low-contrast,however,it shows reduction on resolution with high-contrast.This reduction of resolution with high-contrast do not lead to the decrease of the precision of automatic registration.

Objective:To quantitatively analyze the differences in image quality and generated synthetic-computed tomography(sCT)between cone beam CT(CBCT)and iteration CBCT(iCBCT),which based on filtered back projection(FBP)and iterative reconstruction(IR)techniques of Varian Ethos adaption system.Methods:Using the special Catphan604 phantom of the test of CT image quality,five times of scanning series of CBCT and iCBCT were respectively performed based on thoracic and abdominal scanning protocols,so as to obtain four sets of images,and each set of image included the CBCT image,the composited sCT and iCBCT images based on CBCT,the composited sCT bases on iCBCT.The noise power spectrum(NPS),image uniformity(UI),modulation transfer function(MTF),low-contrast visibility(LCV)and contrast-to-noise ratio(CNR)of them were analyzed.Additionally,a retrospective analysis was conducted on images of six patients who underwent clinical radiotherapy,and the images of them were obtained by using thoracic and abdominal scanning protocols.The sCT images,which were generated by deformable registrations on the basis of CBCT and iCBCT,were analyzed,and they were compared with located CT images,and their mean absolute error(MAE)and root mean square error(RMSE)were further quantitatively analyzed.Results:Compared to CBCT,iCBCT significantly reduced NPS(thoracic images reduced by 0.08,abdominal images reduced by 0.06).The UI values of thoracic images and abdominal images of iCBCT were respectively 0.37 and 0.28,and those of CBCT were respectively 0.65 and 0.39.The LCV values of thoracic images and abdominal images of iCBCT were respectively 0.67 and 0.56,and those of CBCT were respectively 0.93 and 0.90.The MTF50％were 0.28 lp/mm except abdominal image of iCBCT was 0.29 lp/mm.The resolution rate of high contrast between iCBCT and CBCT was basic consistency.The differences of similarity analysis of the generated sCT and located CT bases on CBCT and iCBCT was no significant(P＞0.05).Conclusion:The image quality of iCBCT is superior to conventional CBCT.The accuracy of CT value of generated sCT bases on CBCT and iCBCT can meet requirement,and both of them can be used in the dose calculation of adaptive radiotherapy.

ObjectiveTo investigate the prevalence of Staphylococcus aureus in a hospital in Jiading District， Shanghai， and to determine the enterotoxin gene profiles of Staphylococcus aureus isolated from patients and environment. MethodsSpecimens were collected from environment and patients from a hospital for Staphylococcus aureus isolation and identification. Furthermore， enterotoxin genes （SEA‒SEE） of Staphylococcus aureus were detected. ResultsA total of 54 Staphylococcus aureus strains were isolated from 780 hospital environmental specimens from 2018 to 2021， with a prevalence of 6.92%. In the armrests in the wards， patient’s pillows/quilts， and bedside cupboards， the prevalence was determined to be 20.00%， 20.00% and 16.67%， respectively. In contrast， in the computer’s mouse and keyboard and work clothes of physicians and nurses， the prevalence was 17.42% and 16.67%， respectively. Meanwhile， from 2018 to 2021， a total of 75 strains were collected from patients， of which 36.00%， 14.67% and 14.67% were from the departments of intensive care medicine （ICU）， neurosurgery and orthopedics， respectively. The prevalence of Staphylococcus aureus enterotoxin genes were 48.15% and 61.33% in the environment and patients， respectively. Furthermore， the prevalence of SEA， SEB， SEC， SED， and SEE genes were 14.67%， 41.33%， 9.33%， 1.33%， 1.33% in patients， respectively ， whereas 20.37%， 25.93%， 1.85 %， 1.85% and 0% in environmental specimens， respectively. In the environmental specimens isolated from comprehensive ICU， the prevalence of enterotoxin genes was 77.27%. In the patient's specimens， Staphylococcus aureus was mostly isolated in sputum. Additionally， the prevalence of enterotoxin genes was high in the patients of departments of respiratory medicine， ICU， and orthopedics. ConclusionPrevalence of Staphylococcus aureus remains moderate in the hospital environment. Enterotoxin genes of Staphylococcus aureus are common， with seb gene as the most common gene， followed by SEA gene. It warrants strengthening the disinfection and control of Staphylococcus aureus in the hospital， especially in the ICU.

ObjectiveTo investigate the contamination status and drug resistance of Campylobacter spp. in poultry sold in Jiading District， Shanghai. MethodsFour types of poultry meats （chickens， ducks， geese and pigeons） were sampled from commercial markets， and potential Campylobacter spp. contamination was isolated and identified. Furthermore， resistance of isolated Campylobacter spp. to 15 commonly used antibiotics was tested. ResultsTotally 29 Campylobacter jejuni strains and 34 Campylobacter. coli were isolated from 236 commercial poultry samples. The most severe contamination of Campylobacter spp. was found in chicken samples， with a detection rate of 34.04%， while the lowest detection rate of Campylobacter spp. was found in duck （19.67%）. Contamination status was categorized with different storage conditions. The lowest detection rate of 6.67% was noted under frozen condition， while highest detection rate of 41.27% was noted under cold storage. Campylobacter jejuni was completely resistant to cefazolin， ciprofloxacin， nalidixic acid and tetracycline， and Campylobacter coli was completely resistant to cefazolin， cefoxitin and nalidixic acid； Campylobacter spp. showed the lowest resistance to imipenem. Multi-drug resistant strains accounted for 100.00% of the isolated strains. 96.83% of the strains were resistant to more than 5 drugs， with the highest number reaching 14 kinds of antibiotics. ConclusionThere is a significant difference in the contamination status and drug resistance of Campylobacter spp. isolated from four types of poultry meats sold in Jiading District， Shanghai， and the drug resistance is serious. It is strongly recommended that the use of antibiotics should be strictly controlled. Freezing can effectively reduce Campylobacter spp. pollution.

ObjectiveTo investigate the contamination status， serotype distribution and drug resistance of Salmonella in retail poultry in Jiading District， Shanghai. MethodsFour types of poultry （chicken， duck， goose and pigeon） have been sampled from commercial markets. Salmonella contamination has been isolated and identified using serotype analysis. Furthermore， resistance of isolated Salmonella strains towards 16 commonly used antibiotics has been determined. ResultsA total of 60 Salmonella strains were isolated from 80 poultry samples. The detection rates of Salmonella in pigeon， goose， duck and chicken were 86.67%， 81.82%， 72.73% and 59.38%， respectively. Contamination status has been categorized by storage conditions. Lowest detection rate （65.63%） has been noted in poultry samples under refrigeration storage. The majority serotypes of Salmonella have been revealed as Salmonella typhimurium， Salmonella enteritidis and Salmonella corvallis. Relatively higher drug resistance was discovered with tetracycline， nalidixic acid， ampicillin and chloramphenicol， with drug resistance rate of 60.00%， 58.33%， 50.00% and 48.33%， respectively. Low drug resistance was revealed with cefotaxime. In addition， these Salmonella strains were completely sensitive to imipenem. Significant difference in drug resistance was identified across the types of poultry or Salmonella serotypes. The 11.67% of Salmonella strains were non-resistant to any tested drugs. Multi-drug resistant strains accounted for 46.67% of isolated strains， which were resistant to 13 different antibiotics. Ampicillin-tetracycline or chloramphenirol-cefazolin drug resistance pattern suggested that the Salmonella strain was multi-drug resistant. ConclusionSalmonella contamination remains high in retail poultry in Jiading District， Shanghai. Drug resistance to antibiotics is increasing. Therefore， monitoring and control of Salmonella should be strengthened.

ObjectiveTo investigate the contamination situation， serotype distribution and drug resistance of salmonella in poultry sold in Jiading District， Shanghai. MethodsBetween 2019 and 2020， four types of poultry meat （chicken， duck， goose and pigeon） were sampled from markets， and potential salmonella contamination was isolated and identified via serotyping. Furthermore， resistance detection of isolated salmonella to 13 commonly-used antibiotics was conducted. ResultsA total of 32 salmonella strains were isolated from 156 commercial poultry samples. No salmonella was identified in pigeon samples， while the most severe contamination was detected in goose samples， with a detection rate of 28.00%. Contamination situation was categorized with different storage conditions. The lowest detection rate of 12.90% was noted under cold storage， while the highest rate of 26.67% was detected under frozen condition. The major serotypes of salmonella were Salmonella typhimurium， Salmonella enteritidis and Salmonella Argonne. Relatively higher drug resistance was detected with nalidixic acid and tetracycline， with drug resistance rate of 59.38% and 40.63%， respectively. Low drug resistance was detected with cephalosporins， and no drug resistance was detected with imipenem. Significant difference in drug resistance was noted in the serotype of Salmonella isolated from meat of chicken， duck and goose. Three major salmonella strains had different drug resistance. 21.88% （7/32） of salmonella strains were non-resistant to any tested drugs. Multi-drug resistant strains accounted for 31.25% （10/32） of the isolated strains. At most， salmonella was resistant to 11 kinds of different antibiotics. ConclusionThere is a significant difference in the contamination situation and drug resistance of Salmonella isolated from four types of poultry meat sold in Jiading District， Shanghai. It is strongly recommended that different supervision strategies and management upon classification be implemented.