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 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: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) 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： To determine and compare the contents of catalpol and aucubin in different parts （root， stem， leaf and flower） of wild Centranthera grandiflora， and to provide reference for the selection of medicinal parts and source development. METHODS： HPLC method was used to determine the contents of catalpol and aucubin in root， stem， leaf and flower of wild C. grandiflora， and the contents of different parts were analyzed comparatively. The determination of catalpol was performed on Agilent TC-C18 column with mobile phase consisted of methanol-0.1％ phosphoric acid （1 ∶ 99， V/V） at the flow rate of 1 mL/min； the detection wavelength was set at 210 nm， and sample size was 20 μL. The column temperature was 35 ℃； the determination of aucubin was performed on SPHERI-5RP-C18 column with mobile phase consisted of acetonitrile-water （3 ∶ 97， V/V） at the flow rate of 1 mL/min； the detection wavelength was set at 205 nm， and sample size was 20 μL； the column temperature was 25 ℃. RESULTS： The linear range of catalpol and aucubin were 0.061 5-3.321 and 0.000 36-0.216 mg/mL （all r＝0.999 9）. The limits of detection were 0.016 and 0.007 μg/mL. The limits of quantitation were 0.052 and 0.023 μg/mL. RSDs of precision， stability （24 h） and reproducibility tests were all lower than 2.00％ （n＝6）. The average recoveries were 99.34％ and 99.61％， and RSDs were 1.06％ and 1.12％， respectively （n＝6）. The average content of catalpol in root， stem， leaf and flower wild C. grandiflora were 1.609， 3.030， 11.095 and 1.921 mg/g， respectively. The contents of aucubin in different parts were 0.441， 0.020， 0.005 and 0.006 mg/g，respectively. CONCLUSIONS：The established HPLC method meets the requirements of quantitative analysis. Catalpol is mainly distributed in the leaves of wild C. grandiflora， and aucubin is mainly distributed in the roots of wild C. grandiflora. The experimental conclusion provides a reference for the reasonable selection of different medicinal parts as raw materials to develop medicine with different efficacy.

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.

Objective To develop the methodology for using TLDs and films to measure absorbed dose and 2D dose distribution produced by the multi-leaf collimator (MLC) in intensity modulated radiotherapy (IMRT),in order to provide the guidance on dose quality audit in IMRT.Methods A total of 30 different-typed accelerators were selected from 27 hospitals in Jiangsu,Sichuan,Hubei and Henan provinces,including 17 Varian accelerators,10 Elektas and 3 Simens.The same batch of films and TLDs were put in a 2 cm-thick solid plate for fixation and then loaded in a 15 cm × 15 cm × 15 cm polysyrene solid phantom supplied by International Atomic Energy Agency(IAEA) in terms of 90 cm SSD,19 cm depth,10 cm × 10 cm field at different doses.The standard dose curves wcrc established for film and TLD,respectively.The irradiated film was measured and then sent to the External Audit Group (EAG) in China.The TLD-and film-absorbed doses were compared with TPS-calculated doses.The 2D dose distribution on the IRMT MLC field was measured using films.The homogeneous phanton of 30 cn × 30 cm was scanned by CT and the image was transferred to the TPS.The IMRT was implemented with 6 Gy fractionated irradiation by placing a 25 cm × 25 cm film on the phantom surface at 95 cm SSD and at 5 cm depth.The irradiated film was sent to the IAEA dosimetry laboratory for measurement and calculation.2D dose distribution verification was conducted in thc same way consistent with the procedure of international multi-radiotherapy center.The 3 mm/3％ passing rate was calculated for 2D dose distribution and compared with the film-measured and TPS calculated result.Results IAEA requires the relative deviation of TLD and film measured absorbed dose are with in ± 5％.The relative deviation of TLD-and filmmeasured to TPS-calculated absorbed dose was within the range of ±0.7％-± 8.5％ and within ±0.3％ ±7.8％ in Jiangsu,Sichuan,Hubei and Henan provinces,respectively.IAEA requires the 3 mm/3％ passing rate of film-measured 2D distribution to be 90％.The result of the present study were up to 94.0％.The verification result of 2D dose distribution were within 70.0％-99.9％ in Sichuan,Jiangsu,Hubei and Henan provinces.Conclusions The adsorbed dose and 2D distribution can be audited using TLDs and films for MLC in IRMT.The method is scientific and applicable,economical and convenient for development of dose quality audit for a wide range of IRMT.

Objective To measure the doses to eye lens and hands of workers,using thermo luminescent dosimeter (TLD) and optically stimulated luminescence dosimeter (OSLD).Methods TLDs in the same batch were annealed,packed and stuck to the flat abdomen of Alderson-Phantom at a distance of about 15 cm from 125I seed source,while irradiated at different doses:1.0,1.5,3.0,5.0,10.0,12.0,20.0,25.0,30.0,50.0 and 60.0 μ Gy.And then TLDs were measured by dosimeters to establish a dose calibration curve.By implanting seed source into the selected lung for 14 cases,belly for 10 cases,pelvic for 5 case and neck for 6 cases while placing calibrated TLDs on the left,middle and right above eyes,left and right hands of the workers to obtain the location-specific kerma values.Finally,the conversion factors Hp (3) and Hp (0.07) were used to calculate the values of dose equivalent to eye lens and hands.Additionally,OSLDs were used to measure the doses to workers in the same way.Results The TLD-measured eye lens dses to the operator and his assistant were 0.8 and 1.6 mSv in lungs,1.3 and 1.2 mSv in bellies,0.9 and 0.6 mSv in pelves,0.3 mSv in necks,respectively.Meanwhile,hand doses to the operator and his assistant were 1.4 and 2.1 mSv in lungs,1.2 and 1.0 mSv in bellies,0.5 and 0.9 mSv in pelves,0.1 mSv in necks,respectively.The maximum doses to eye lens and hands were 1.2 and 1.0 mSv,respectively in a single treatment.OSLD-measured dose equivalents from lung therapy were 0.2 and 0.1 mSv for eye lens of the operator and his assistant and 0.4 and 0.6 mSv for hands.For belly therapy,the accumulated dose equivalent to hands of the operator was 0.1 mSv while those for other types of therapy were 0 mSv.Conclusions TLDs have the capability to measure not only accumulated dose but also dose equivalent from a single therapy According to ICRP 118 publication and as estimated in the present study,the number of therapy should be not more than 17 every year.OSLDs only give the accumulated dose,the accuracy of which needs to be studied in low-dose measurement.

Objective To develop the methods for using 0.015 cc pinpoint chambers, 0.007 cc miniature chambers and diode detector to measure Multi-leaf collimator (MLC) small field in IMRT.Methods MAX4000 and Unidos electrometers were connected with different types of small chambers and diode detectors.MLC shaped fields of10 cm×10 cm, 6 cm×6 cm, 4 cm×4 cm, 3 cm×3 cm, 2 cm× 2 cm were defined at 100 cm SSD.The field sizes for the Varian accelerator were defined by the tertiary MLC, while the secondary jaws were kept at 10 cm × 10 cm field, with the monitor units of 250 MU.Each field was measured three times to obtain the average value.The readings of all small fields were normalized to 10 cm × 10 cm field values for comparison of measured and published output factors.Results The relative deviations of the MLC small field output factors from the published outputs are 1.0％ , 1.7％ , 1.5％ and 2.4％, respectively, for Unidos electrometer connected with 0.015 cc pinpoint chamber;0.2％, 0.8％, 0.8％ and 1.4％, respectively, for Unidos electrometer connected with 0.007 cc miniature chamber;and 0.1％, 0.5％, 0.5％ and 0.9％, respectively, for MAX4000 electrometer connected with 0.007 cc miniature chamber.Conclusions The 0.015 cc chamber-measured MLC output factors for 3 cm × 3 cm and 2 cm × 2 cm fields are excellent.As required by IAEA, the relative deviations of the measured output factor from the published output factor are within ± 2％ for 2 cm × 2 cm fields and ± 3％ for larger fields.The results measured using 0.007 cc chamber are better than those measured using 0.015 cc chamber.The measured results using the diode detector, normalized to the 10 cm × 10 cm field, are consistent with the minimum requirements and excellent when being normalized to the 4 cm × 4 cm field.For dosimetric consideration, MLC small field output factor should be measured using small chamber and diode detector.The method is accurate and reliable, therefore, all measured output factors for MLC small fields should be input into radiation treatment plan system.