Objective: To develop the methodology for using TLD and radiochromic film to measure the planned target volume (PTV) and organ at risk (OAR) doses and 2D dose distribution in IMRT, in order to provide technical guidance on the dose quality audit in IMRT at home. Methods: China has participated in the research project launched by the international multi-radiotherapy centre (IMRC). IMRT polystyrene phantom provided by IAEA was scanned by CT scanner and then the scanned images were transmitted to TPS to outline prescribed dose to PTV and to OAR. The former was limited to 400 cGy while the latter limited to 200 cGy. IMRT was implemented with the phantom irradiated using 6 MV X-ray. The irradiated TLDs and films were sent to IAEA dosimerty laboratory for measurement and calculation. Jiangsu, Sichuan, Hubei and Henan provinces were selected to engage with this study for their variety of accelerators and highly skilled physicists. The procedures used were the same as in the IMRC and the irradiated TLDs and films were required to send to external audit group for measurement and calculation. Results: According to IAEA requirement, the relative deviations of the TLD-measured and TPS planned doses are within ±7.0% for PTV and OAR. The China′s research results at the IMRC have shown that the relative deviation of TLD-measured and TPS-planned values for the upper and lower PTV were -0.2% and 0.8%, respectively, consistent with the IAEA requirement, and the values for upper and lower OAR were -0.6% and -1.0%, respectively, consistent with the requirement. As the results have shown in four provinces, the relative deviations of the TLD-measured and TPS-planned were within 0 to 10.6% for upper and lower PTV and -0.6% to 20.9% for upper and lower OAR. According to IAEA requirement, the passing rate should be greater than 90% for 3 mm /3% for 2D dose distribution. China′s result at the IMRC is 100%, being excellent. The four provinces′ results have shown that 2D dose distribution pass rate of 3 mm/3% was in the range of 45.0%-100.0%. Conclusions The uses of TLD in quality audit for PTV and OAR doses and the radiochromic film in 2D dose distribution pass rate in IMRT are characterized by scientific feasibility, strong operability, easy-to-mail and data realibility. They are can be applied to quality assurance and audit in medical institutions in the country to on a large scale.

Objective: To validate the method for measuring the TPV and OAR doses and 2D dose distribution in IMRT through using TLD and radiochromic film. Methods: Eight medical linear accelerators (Valian, Elekta, Siemens) were selected. The polystyrene phantom provided by IAEA was CT scanned and the image obtained was transferred to TPS for formulation of treatment plan, prescription of PTV and OAR doses and calculation of corresponding monitoring unit (MU), IMRT was performed on the phantom using 6 MV X-ray. Irradiated TLDs and films were measured and evaluated at the Secondary Standard Dosimetry Laboratory at the Radiation Safety Institute of Chinese Center for Disease Control and Prevention. Results: According to IAEA requirement, the relative deviations between TLD-measured and TPS-planned doses were within ±7.0% for the prescribed PTV and OAR doses. As measured result, the PTV values for 8 accelerators were in the range of 0.6% to 5.9%, consistent with the IAEA requirements, whereas the OAT values for 8 accelerators were within -0.6% to 7.0%, consistent the requirements. As IAEA required, the 2D dose distribution passing rate of 3 mm/3% should be higher than 90%. The film-measured and TPS-planned values for 8 accelerators were within 90.2% to 100.0%, consistent with the requirements. Conclusions TLD and radiochromic film are feasible in validating the PTV and OAR doses and the 2D dose distribution pass rate in IMRT. This method can be widely used in quality audit and internal verification in IMRT in medical institutiions on a large scale.

Objective: To study a method to measure the doses to planned target volume (PTV) and organ at risk (OAR) and 2D dose distribution in IMRT by using TLD and radiochromic film for a verification purpose. Methods: Totally 7 different types of medical linear accelerators were selected from seven hospitals in Hubei province. A polystyrene phantom provided by IAEA was CT scanned and then the scanned images were returned to the Treatment Planning System (TPS) for determining the prescribed doses to PTS and OAR and the corresponding MU. After the phantom was irradiated with 6 MV X-ray, the TLDs and films were transmitted to the secondary standard dosimetry laboratory of China CDC for measurement and estimation. Results: The IAEA required the relative deviations between TLD-measured and TPS-planned doses to OAR and PTV be within ±7.0%. For PTV, the measured-to-planned deviation values for 7 accelerator were within -5.4% to 6.5%, all consistent with the IAEA requirements. For OAR, the values for 5 accelerators were within -2.2% to 6.7%, not consistent the requirements, whereas the values for the other 2 were -8.6% and 8.2% respectively, beyond the required values. The IAEA required that the 2D dose distribution 3 mm/3% pass rate be higher than 90%. The measured values for 7 accelerators were in the range of 90.3%-98.9%, all consistent with the requirements. Conclusions It is feasible scientifically and easy to operate in practice for using TLD and film to carry out dose verification in IMRT. It would be advisable to apply this method to quality verification in IMRT in medical institutions to the extent possible.

Objective: To use TLDs and radiochromic films to verify the prescribed doses to both planned target volume (PTV) and organ at risk (OAR) and the 2D dose distribution in IMRT. Methods: Eight accelerators of different models were selected in Henan province. The polystyrene phantom provided by IAEA was scanned using CT scanners and then the scanned images were transmitted to treatment planning system (TPS) for prescribing respectively the doses to PTV and OAR. IMRT was performed with phantom exposed to a 6 MV X-rays. The irradiated TLDs and films were delivered for measurement and estimation at Secondary Standard Dosimetry Laboratory at National Institute for Radiological Protection, Chinese Center for Disease Control and Prevention. Results: According to IAEA requirements, the relative deviations of the TLD-measured and TPS-planned values were within ±7.0% for the prescribed doses to PTV and OAR. The measured results for PTV have shown that the relative deviation of TLD-measured and TPS-planned values were within -0.3% to 6.9% for 8 accelerators, all consistent with the IAEA requirements. For OAR, the relative deviations of TLD-measured and TPS-planned were within -7.0% to 0.3% for 6 accelerators, consistent with the requirements, whereas those for other 2 accelerators were within -10.8% to -8.4%, not up to the requirements. IAEA required that, for 2D dose distribution, the pass rate of 3 mm/3% be ≥90%. The measured values for 7 accelerators were from 90.2% to 99.9%, consistent with the requirements, whereas that for another one was 70.0%, not meeting the requirement. Conclusions The method to verify, using radiochromic film and TLD, the prescribed doses to PTV and OAR and the pass rate of 2D dose distribution is simple and reliable. It is an important step to implement quality control for IMRT and can provide effective support for medical or third-party service institution to verify clinically prescribed dose.

Objective: To study a method for verifying the doses to PTV and OAR as well as the 2D dose distribution arising from IMRT through using radiochromic films and TLDs. Methods: Totally 7 medical electronic linear accelerators from Varian, Siemens and Elekta were selected. The polystyrene phantom provided by IAEA was conducted with CT scan. After irradiation with 6 MV X-rays, the TLDs and films were returned to the secondary standard dosimetry laboratory of China CDC for measurement and estimation. Results: According to the IAEA requirements, the relative deviations between TLD-measured and TPS-planned values for PTV and OAR doses were both within ±7.0%. For PTV, the measured relative deviations for 5 accelerators were in the range of -4.0% to 3.4%, consistent with the IAEA requirements, whereas the values for the other 2 accelerators were in the range of -7.0% to 10.6%, not consistent with the requirements. For OAR, the values for 4 accelerators were in the range of -5.6% to 3.3%, consistent with the IAEA requirements, whereas the values for the other 3 accelerators were in the range of -20.8% to 11.5%, not meeting the requirements. As required by the IAEA, the 2D dose distribution 3 mm/3% pass rate should be higher than 90%. The measured values for 5 accelerators were in the range of 91.8% to 98.5%, consistent with the requirements, whereas the values measured for the other 2 were 45.0% and 77.0% respectively, not meeting the requirements. Conclusions It is feasible for using TLDs and radiochromic films to verify the doses to PTV and OAR and the 2D dose distribution in IMRT. This method should be applied to not only quality verification but also hospital internal audit to the extent possible.

Objective:Surgical site infection (SSI) can markedly prolong postoperative hospital stay, aggravate the burden on patients and society, even endanger the life of patients. This study aims to investigate the national incidence of SSI following abdominal surgery and to analyze the related risk factors in order to provide reference for the control and prevention of SSI following abdominal surgery.Methods:A multicenter cross-sectional study was conducted. Clinical data of all the adult patients undergoing abdominal surgery in 68 hospitals across the country from June 1 to 30, 2020 were collected, including demographic characteristics, clinical parameters during the perioperative period, and the results of microbial culture of infected incisions. The primary outcome was the incidence of SSI within postoperative 30 days, and the secondary outcomes were ICU stay, postoperative hospital stay, cost of hospitalization and the mortality within postoperative 30-day. Multivariable logistic regression was used to analyze risk factors of SSI after abdominal surgery.Results:A total of 5560 patients undergoing abdominal surgery were included, and 163 cases (2.9%) developed SSI after surgery, including 98 cases (60.1%) with organ/space infections, 19 cases (11.7%) with deep incisional infections, and 46 cases (28.2%) with superficial incisional infections. The results from microbial culture showed that Escherichia coli was the main pathogen of SSI. Multivariate analysis revealed hypertension (OR=1.792, 95% CI: 1.194-2.687, P=0.005), small intestine as surgical site (OR=6.911, 95% CI: 1.846-25.878, P=0.004), surgical duration (OR=1.002, 95% CI: 1.001-1.003, P<0.001), and surgical incision grade (contaminated incision: OR=3.212, 95% CI: 1.495-6.903, P=0.003; Infection incision: OR=11.562, 95%CI: 3.777-35.391, P<0.001) were risk factors for SSI, while laparoscopic or robotic surgery (OR=0.564, 95%CI: 0.376-0.846, P=0.006) and increased preoperative albumin level (OR=0.920, 95%CI: 0.888-0.952, P<0.001) were protective factors for SSI. In addition, as compared to non-SSI patients, the SSI patients had significantly higher rate of ICU stay [26.4% (43/163) vs. 9.5% (514/5397), χ 2=54.999, P<0.001] and mortality within postoperative 30-day [1.84% (3/163) vs.0.01% (5/5397), χ 2=33.642, P<0.001], longer ICU stay (median: 0 vs. 0, U=518 414, P<0.001), postoperative hospital stay (median: 17 days vs. 7 days, U=656 386, P<0.001), and total duration of hospitalization (median: 25 days vs. 12 days, U=648 129, P<0.001), and higher hospitalization costs (median: 71 000 yuan vs. 39 000 yuan, U=557 966, P<0.001). Conclusions:The incidence of SSI after abdominal surgery is 2.9%. In order to reduce the incidence of postoperative SSI, hypoproteinemia should be corrected before surgery, laparoscopic or robotic surgery should be selected when feasible, and the operating time should be minimized. More attentions should be paid and nursing should be strengthened for those patients with hypertension, small bowel surgery and seriously contaminated incision during the perioperative period.

Objective:Surgical site infection (SSI) is the most common infectious complication after emergency abdominal surgery (EAS). To a large extent, most SSI can be prevented, but there are few relevant studies in China. This study mainly investigated the current situation of SSI occurrence after EAS in China, and further explored risk factors for SSI occurrence.Methods:Multi-center cross-sectional study was conducted. Clinical data of patients undergoing EAS in 33 hospitals across China between May 1, 2019 and June 7, 2019 were prospectively collected, including perioperative data and microbial culture results from infected incisions. The primary outcome was the incidence of SSI after EAS, while the secondary outcomes were postoperative hospital stay, ICU occupancy rate, length of ICU stay, hospitalization cost, and mortality within postoperative 30 days. Univariate and multivariate logistic regression models were used to analyze the risk factors of SSI after EAS.Results:A total of 660 EAS patients aged (47.9±18.3) years were enrolled in this study, including 56.5% of males (373/660). Forty-nine (7.4%) patients developed postoperative SSI. The main pathogen of SSI was Escherichia coli [culture positive rate was 32.7% (16/49)]. As compared to patients without SSI, those with SSI were more likely to be older (median 56 years vs. 46 years, U=19 973.5, P<0.001), male [71.4% (35/49) vs. 56.1% (343/611), χ 2=4.334, P=0.037] and diabetes [14.3% (7/49) vs. 5.1% (31/611), χ 2=5.498, P=0.015]; with-lower preoperative hemoglobin (median: 122.0 g/L vs. 143.5 g/L, U=11 471.5, P=0.006) and albumin (median: 35.5 g/L vs. 40.8 g/L, U=9452.0, P<0.001), with higher blood glucose (median: 6.9 mmol/L vs. 6.0 mmol/L, U=17 754.5, P<0.001); with intestinal obstruction [32.7% (16/49) vs. 9.2% (56/611), χ 2=25.749, P<0.001], with ASA score 3-4 [42.9% (21/49) vs. 13.9% (85/611), χ 2=25.563, P<0.001] and with high surgical risk [49.0% (24/49) vs. 7.0% (43/611), χ 2=105.301, P<0.001]. The main operative procedure resulting in SSI was laparotomy [81.6%(40/49) vs. 35.7%(218/611), χ 2=40.232, P<0.001]. Patients with SSI experienced significantly longer operation time (median: 150 minutes vs. 75 minutes, U=25 183.5, P<0.001). In terms of clinical outcome, higher ICU occupancy rate [51.0% (25/49) vs. 19.5% (119/611), χ 2=26.461, P<0.001], more hospitalization costs (median: 44 000 yuan vs. 15 000 yuan, U=24 660.0, P<0.001), longer postoperative hospital stay (median: 10 days vs. 5 days, U=23 100.0, P<0.001) and longer ICU occupancy time (median: 0 days vs. 0 days, U=19 541.5, P<0.001) were found in the SSI group. Multivariate logistic regression analysis showed that the elderly (OR=3.253, 95% CI: 1.178-8.985, P=0.023), colorectal surgery (OR=9.156, 95% CI: 3.655-22.937, P<0.001) and longer operation time (OR=15.912, 95% CI:6.858-36.916, P<0.001) were independent risk factors of SSI, while the laparoscopic surgery (OR=0.288, 95% CI: 0.119-0.694, P=0.006) was an independent protective factor for SSI. Conclusions:For patients undergoing EAS, attention should be paid to middle-aged and elderly patients and those of colorectal surgery. Laparoscopic surgery should be adopted when feasible and the operation time should be minimized, so as to reduce the incidence of SSI and to reduce the burden on patients and medical institutions.

Objective:Surgical site infection (SSI) can markedly prolong postoperative hospital stay, aggravate the burden on patients and society, even endanger the life of patients. This study aims to investigate the national incidence of SSI following abdominal surgery and to analyze the related risk factors in order to provide reference for the control and prevention of SSI following abdominal surgery.Methods:A multicenter cross-sectional study was conducted. Clinical data of all the adult patients undergoing abdominal surgery in 68 hospitals across the country from June 1 to 30, 2020 were collected, including demographic characteristics, clinical parameters during the perioperative period, and the results of microbial culture of infected incisions. The primary outcome was the incidence of SSI within postoperative 30 days, and the secondary outcomes were ICU stay, postoperative hospital stay, cost of hospitalization and the mortality within postoperative 30-day. Multivariable logistic regression was used to analyze risk factors of SSI after abdominal surgery.Results:A total of 5560 patients undergoing abdominal surgery were included, and 163 cases (2.9%) developed SSI after surgery, including 98 cases (60.1%) with organ/space infections, 19 cases (11.7%) with deep incisional infections, and 46 cases (28.2%) with superficial incisional infections. The results from microbial culture showed that Escherichia coli was the main pathogen of SSI. Multivariate analysis revealed hypertension (OR=1.792, 95% CI: 1.194-2.687, P=0.005), small intestine as surgical site (OR=6.911, 95% CI: 1.846-25.878, P=0.004), surgical duration (OR=1.002, 95% CI: 1.001-1.003, P<0.001), and surgical incision grade (contaminated incision: OR=3.212, 95% CI: 1.495-6.903, P=0.003; Infection incision: OR=11.562, 95%CI: 3.777-35.391, P<0.001) were risk factors for SSI, while laparoscopic or robotic surgery (OR=0.564, 95%CI: 0.376-0.846, P=0.006) and increased preoperative albumin level (OR=0.920, 95%CI: 0.888-0.952, P<0.001) were protective factors for SSI. In addition, as compared to non-SSI patients, the SSI patients had significantly higher rate of ICU stay [26.4% (43/163) vs. 9.5% (514/5397), χ 2=54.999, P<0.001] and mortality within postoperative 30-day [1.84% (3/163) vs.0.01% (5/5397), χ 2=33.642, P<0.001], longer ICU stay (median: 0 vs. 0, U=518 414, P<0.001), postoperative hospital stay (median: 17 days vs. 7 days, U=656 386, P<0.001), and total duration of hospitalization (median: 25 days vs. 12 days, U=648 129, P<0.001), and higher hospitalization costs (median: 71 000 yuan vs. 39 000 yuan, U=557 966, P<0.001). Conclusions:The incidence of SSI after abdominal surgery is 2.9%. In order to reduce the incidence of postoperative SSI, hypoproteinemia should be corrected before surgery, laparoscopic or robotic surgery should be selected when feasible, and the operating time should be minimized. More attentions should be paid and nursing should be strengthened for those patients with hypertension, small bowel surgery and seriously contaminated incision during the perioperative period.

Objective:Surgical site infection (SSI) is the most common infectious complication after emergency abdominal surgery (EAS). To a large extent, most SSI can be prevented, but there are few relevant studies in China. This study mainly investigated the current situation of SSI occurrence after EAS in China, and further explored risk factors for SSI occurrence.Methods:Multi-center cross-sectional study was conducted. Clinical data of patients undergoing EAS in 33 hospitals across China between May 1, 2019 and June 7, 2019 were prospectively collected, including perioperative data and microbial culture results from infected incisions. The primary outcome was the incidence of SSI after EAS, while the secondary outcomes were postoperative hospital stay, ICU occupancy rate, length of ICU stay, hospitalization cost, and mortality within postoperative 30 days. Univariate and multivariate logistic regression models were used to analyze the risk factors of SSI after EAS.Results:A total of 660 EAS patients aged (47.9±18.3) years were enrolled in this study, including 56.5% of males (373/660). Forty-nine (7.4%) patients developed postoperative SSI. The main pathogen of SSI was Escherichia coli [culture positive rate was 32.7% (16/49)]. As compared to patients without SSI, those with SSI were more likely to be older (median 56 years vs. 46 years, U=19 973.5, P<0.001), male [71.4% (35/49) vs. 56.1% (343/611), χ 2=4.334, P=0.037] and diabetes [14.3% (7/49) vs. 5.1% (31/611), χ 2=5.498, P=0.015]; with-lower preoperative hemoglobin (median: 122.0 g/L vs. 143.5 g/L, U=11 471.5, P=0.006) and albumin (median: 35.5 g/L vs. 40.8 g/L, U=9452.0, P<0.001), with higher blood glucose (median: 6.9 mmol/L vs. 6.0 mmol/L, U=17 754.5, P<0.001); with intestinal obstruction [32.7% (16/49) vs. 9.2% (56/611), χ 2=25.749, P<0.001], with ASA score 3-4 [42.9% (21/49) vs. 13.9% (85/611), χ 2=25.563, P<0.001] and with high surgical risk [49.0% (24/49) vs. 7.0% (43/611), χ 2=105.301, P<0.001]. The main operative procedure resulting in SSI was laparotomy [81.6%(40/49) vs. 35.7%(218/611), χ 2=40.232, P<0.001]. Patients with SSI experienced significantly longer operation time (median: 150 minutes vs. 75 minutes, U=25 183.5, P<0.001). In terms of clinical outcome, higher ICU occupancy rate [51.0% (25/49) vs. 19.5% (119/611), χ 2=26.461, P<0.001], more hospitalization costs (median: 44 000 yuan vs. 15 000 yuan, U=24 660.0, P<0.001), longer postoperative hospital stay (median: 10 days vs. 5 days, U=23 100.0, P<0.001) and longer ICU occupancy time (median: 0 days vs. 0 days, U=19 541.5, P<0.001) were found in the SSI group. Multivariate logistic regression analysis showed that the elderly (OR=3.253, 95% CI: 1.178-8.985, P=0.023), colorectal surgery (OR=9.156, 95% CI: 3.655-22.937, P<0.001) and longer operation time (OR=15.912, 95% CI:6.858-36.916, P<0.001) were independent risk factors of SSI, while the laparoscopic surgery (OR=0.288, 95% CI: 0.119-0.694, P=0.006) was an independent protective factor for SSI. Conclusions:For patients undergoing EAS, attention should be paid to middle-aged and elderly patients and those of colorectal surgery. Laparoscopic surgery should be adopted when feasible and the operation time should be minimized, so as to reduce the incidence of SSI and to reduce the burden on patients and medical institutions.

Objective To develop measurement methodology using film for the positioning accuracy of MLC leaves in IMRT.Methods The solid water phantom of 30 cm x 30 cm was scanned and the scanned images were transferred to TPS for treatment plan formulation.The five MLC strip picket fence pattern was formed by MLC leaves,each 3.0 cm long × 6.0 mm wide.The separation between strip and strip is 3.0 cm.SAD is 100 cm at dmax for 6 MV X-ray,with 250 MU per MLC strip.EBT2 radiochomic film was put on the phantom for delivery of IMRT,for each MLC strip.The present study focused on 30 accelerators of Varian,Elekta and Siemens designs at 27 hospitals with highly skilled physicists all over Jiangsu,Sichuan,Hubei and Henan provinces.The study was conducted in the same way as used in international multi-radiotherapy center (IMRC).The irradiated films were sent respectively to IAEA dosimetry laboratory and external audit group (EGA) of China for measurement,analysis and calculation.Results According to IAEA requirements,the differenc of film-measured and TPS-planned of MLC leaf position for each strip should be within ±0.5 mm.China had participated in the research of IMRC,with the result of 0.3,0.2,0.0,-0.1,and-0.2 mm,respectively.For 30 accelerators in four provinces involved in the study,the IAEA's verification results of MLC leaf position were within 0.6-1.0 mm for 5 accelerators and within ± 0.5 mm for other 25 ones.Whereas the verification results of EAG were within 0.6-1.0 mm for 6 accelerators and within ±0.5 mm for other 24 ones.According to IAEA requirements,the film-measured MLC leaf position deviation for each pair of leaves and average all pairs of leaves should be within ±0.5 mm.China had participated in IMRC's research,with the measured result being 0.04 mm.The verification result of EGA for 30 accelerators showed the measured MLC leaf position deviations were all ＜0.3 mm per strip,consistent with IAEA requirements.The IAEA's result showed the measured deviations of MLC leaf position for 29 accelerators were within ±0.5 mm,with only other one being-0.7 mm not consistent with the IAEA requirements.As required by IAEA,the difference of film-measured difference of MLC opening width should be within ±0.75 mm between each pair and average all pairs of leaves.China's result in research of IMRC showed the difference of minimum width to mean width was-0.2 mm whereas the difference of maximum width to mean width was 0.4 mm.For 30 accelerators involved in IAEA'verification study,the measured result shown that the difference between maximum and average of filmmeasured of MLC leaf width,and between minmum and average,were within ± 0.75 mm for 24 accelerators,in line with the IAEA requirements.For other 6 ones,the values were beyond ±0.75 mm,not in line with the IAEA requirements.For the verification result of EAG,the difference between maximum and average widths and between minmum and average widths for 25 accelerators were within ±0.75 mm as required by IAEA,whereas for other 5 ones the value were beyond ±0.75 mm,not consistent with IAEA requirements.The standard deviation of film-measured MLC opening width between each pair and average all pairs should be within 0.3 mm as required by IAEA.China's IMRC result was 0.12 mm.The verification result of IAEA shown the standard deviation of MLC opening position were ＜0.3 mm for 26 accelerators and ＞ 0.3 mm for other 4 accelerators.EAG verification result were the same as IAEA result.Conclusions The method using radiochromic film for measuring accuracy of MLC leaf position is convenient and practicable as a quality audit.It is suitable for quality verification in medical institutions owing to easy to post and repeated measurements.