Objective To compare the dosimetric verification results of Varian Portal Dosimetry and Matrixx,and to assess the reliability of the clinical application of electronic portal imaging device (EPID) verification.Methods Varian TrueBeam linear accelerator,which was equipped with a 120-leaf multileaf collimator and an amorphous silicon EPID,as well as portal dose prediction software.IBA I′mRT Matrixx ion chamber array was used.EPID algorithm configuration,dose calibration,and testing before use were performed.The sliding-window protocol was used.There were 77 patients with tumors involving the head and neck (mainly nasopharyngeal carcinoma),mediastinum,abdomen,and pelvic cavity were selected.The verification plan of the portal dose was created with a source-detector distance of 100 cm,and the gantry angle was kept the same as the treatment plan.The verification plan was carried out in the TrueBeam machine,and the data were collected at the same time by EPID.Comparison between the measured and calculated dose images was performed,and the evaluation standard was gamma index (3%/3 mm).The paired t-test was used for difference analysis.Results For the 77 patients,the Gamma passing rates of both methods were above 97%.Except for head and neck carcinoma were a significant difference between the results of dosimetric results using EPID and Matrixx in intensity-modulated radiotherapy (P=0.018) other remaining all P> 0.05.Conclusions The dosimetric verification results of EPID are consistent with those of Matrixx.EPID can be used for dosimetric verification,and Matrixx ion chamber array can be used only in case of a low Gamma passing rate.

Objective To investigate the effect of general anesthesia combined with epidural block anesthesia on intestinal barrier function in patients with gastric cancer after radical resection.Methods 90 patients with gastric cancer undergoing laparoscopic radical resection were selected.They were randomly divided into observation group (epidural anesthesia plus general anesthesia) and control group (general anesthesia),45 cases in each group.The intraoperative blood loss,intraoperative infusion volume,postoperative exhaust time,postoperative complications and the function of intestinal barrier effects were compared between the two groups.Results The total incidence rate of postoperative complications in the observation group(8.89％) was significantly lower than that in the control group (28.89％) (x2 =4.83,P ＜ 0.05).The hospital stay in the observation group [(12.5 ± 4.23) d] was significantly shorter than that in the control group [(17.5 ± 5.26) d] (t =3.27,P ＜ 0.05).The two amine oxidase [(3.88 ± 0.98) U/L],D-lactic acid [(7.44 ± 5.23) mg/L],endotoxin [(13.44 ± 2.12) U/L] levels of the observation group were significantly lower than those of the control group [two amine oxidase (11.33 ± 1.25) U/L,D-lactic acid (15.34 ±3.21) mg/L,endotoxin (21.03 ± 0.82) U/L] (t =5.63,5.02,4.19,all P ＜ 0.05).Conclusion Compared with total intravenous anesthesia,total intravenous anesthesia combined with epidural anesthesia is beneficial to the recovery of intestinal barrier function after radical gastrectomy,and can shorten the postoperative hospital stay.It is worthy of clinical application and popularization.

Objective:To evaluate the combined effect of an trajectory log field based(LBF)and two commercial dose reconstruction systems on volume-modulated arc therapy(VMAT)dose verification of lung cancer.Methods:An in-house program was developed to introduce errors in trajectory log of TrueBeam to the origin plan and recalculate the dose of the error plan in treatment planning system(TPS). A total of 18 lung cancer cases treated by two-arc VMAT were selected to perform on LINAC and measured by ArcCheck simultaneously. Then, the reconstructed doses were obtained by 3DVH. The mode of reconstruction was calculated by LFB and Compass. Five of the 18 cases were performed on LINAC two times in four hours and measured by ArcCheck to evaluate the stability of the TrueBeam performance. The 18 plans were recalculated and performed on LINAC with a solid water phantom with 5 cm build-up, 4 cm back scattering thickness and a FC65-G detector in the center. The measured dose by detector was compared with the reconstructed dose by three systems.Results:TheTruebeam performance was stable. For all of the 18 cases, the point dose measured by FC65-G and reconstructed by three systems had a deviation of less than 2% to the TPS calculated. For all of the organs reconstructed by LBF and most organs reconstructed by 3DVH and Compass, the γ pass rate between them and TPS all exceeded 90% under all criteria, as well as the ArcCheck measured results. For all the organ dose difference between reconstructed and TPS, LBF system had the smallest difference, followed by the Compass system except the lung, and the 3DVH had the highest difference.Conclusions:LBF, 3DVH and Compass can reflect the VMAT dose verification results of lung cancer from different perspectives. The combined application of three systems can demonstrate the verification results in an intuitive manner, which is beneficial for subsequent analysis.

Objective:To study the changing characteristics and impact factors of helical tomotherapy (HT)for longitudinal dose fall-off outside the target, in order to guide the plan junction or pretreatment target and implementation efficiency in clinical.Methods:Eight patients with head and neck tumors admitted to the Department of Oncology Radiotherapy of the First Affiliated Hospital of Zhengzhou University in December 2019 were retrospectively selected as the research objects. The planning target area and dose drop structure were outlined in the head and neck images with a thickness of 1 mm obtained by Siemens SOMATOM Definition AS positioning computerized tomography (CT). Different field widths (FW, 5.0 cm/2.5 cm/1.0 cm) and pitches (0.430/0.287/0.215) were assembled for planning with the same modulation factor (1.8), finest does calculation grid (0.195 cm ×0.195 cm) and other planning parameters were consistent. The plans were designed by different parameters, and the result was analyzed by univariate analysis.Results:The that different pitch curves coincided under the same field width by comparative analyzing, so pitchs had no effect on dose drop. The different field width curves were independent of each other, indicating that the field width had an effect on dose drop in the head and foot direction. The relationship between the longitudinal dose drop speed outside the target and the change of the field width was inversely correlated: the larger field widths meant the slower dose fall-off and the larger penumbra, while the smaller field widths meant the faster fall-off and the smaller penumbra. When the dose fall-off to 50% of the prescribed dose, the distance from the target was approximately equal to half the field widths, and the pitchs had not affect the rate of dose-drop, while the dose at different distances from the target boundary could be calculated by the fitting formulas. The field widths and pitchs had little effect on the CI and HI index of the target, relatively, the target area was best when the field width was 2.5 cm. The total beam-on time gradually decreased with the increase of the field widths and pitches.Conclusions:When segment target therapy needs to consider planning junction, execution efficiency, and controlling longitudinal dose fall-off and considered the execution, the optimal planned parameters such as field widths and pitches could be selected or the target at the junction regions could be adducted according to the longitudinal dose drop formula, so as to achieve the ideal dose distribution.

Objective To investigate the clinical features,complications,treatment and prognosis of patients with Pcutz-Jeghers syndrome.Methods The clinical data of thirty-one cases of Pcutz-Jeghers syndrome treated in the First Hospital of Shanxi Medical University from January 1998 to December 2016 was analyzed retrospectively.Results There were11 cases with definite family history(35%,11/31).There were 21 cases of mucocutaneous pigmentation(67.7%,21/31),31 cases of gastrointestinal polyps(100%,31/31), including 8 cases of canceration(25.0%,8/31),24 cases of digestive tract bleeding(77.4%,24/31),20 cases of intussusception(64%,20/31),and 1 case of intestinal perforation(3.2%,1/31).6 cases were treated with endoscopic high frequency electrocoagulation,12 cases received polypectomy,17 cases underwent resection of intestinal tract.3 patients with intractable intussusception underwent plication of small intestine,and 4 patients with colon cancer underwent total colectomy combined with lymph node dissection.Conclusion Peutz-Jeghers syndrome often induce intractable intestinal obstruction and gastrointestinal tumor,resection of intestinal lesions should be favorable.For small intractable intussusception,the plication of small intestine has certain value; for its potential malignancy,it should be strictly monitored and actively treated.Gene therapy and drug therapy will guide for the future development.

Objective:To compare and investigate the effects of laparoscopy and open colorectal cancer on the intestinal barrier function in patients with colorectal cancer.Methods:Sixty-two patients with colorectal cancer admitted in our hospital from January 2015 to October 2016 were selected and divided into laparoscopic surgery group with thirty-four patients and open surgery group with twenty-eight patients. The changes of postoperative intestinal barrier function were compared between the two groups.Result:The levels of plasma D-lactate, plasma diamine oxidase (DAO) and bacterial endotoxin in the laparoscopic surgery group were significantly lower than those in the open surgery group ( P<0.05). Conclusion:Laparoscopic and open colorectal cancer surgery can cause damage to intestinal barrier function, but the damage of laparoscopic colorectal cancer surgery is lower than that of open colorectal surgery.

Objective:To perform testing and clinical application of a volumetric-modulated arc therapy (VMAT) dosimetry verification system based on three-dimensional dose reconstruction of patient anatomical structures.Methods:ArcCheck array calibration was performed. Then, 200 MU was delivered with a 10 cm×10 cm field when the source to center of ArcCheck was 100 cm to calibrate the absolute dose and the dose was simultaneously measured by a FC65-G detector in the center of the ArcCheck. The absolute dose calibration value or the CT value of ArcCheck was adjusted to minimize the differences between the planning and measurement values of FC65-G, reconstructed value by 3DVH and reconstructed percent depth dose by 3DVH. 10 lung and 10 cervical cancer VMAT cases were selected and measured by ArcCheck and FC65-G under the delivery of a TrueBeam LINAC. The three-dimensional doses of all cases were reconstructed by 3DVH and compared with the planning and measurement values.Results:Different array calibration files of ArcCheck exerted different effect upon the two-dimensional dose measured by ArcCheck and three-dimensional dose reconstructed by 3DVH. The optimal reconstructed dose was obtained when self-calibration file was adopted and 249.96 cGy was regarded as the absolute dose calibration value. The deviations of the mean dose (D mean) and D 95% of the target were within ±4.2% and parameters of some organs at risk significantly differed compared with the reconstructed and planning dose for all cases. A negative mean point dose difference was obtained and the reconstructed dose was closer to the measured value. The γ-passing rate of the target for some cases was low, the proportion of regions irradiated by 50% prescription dose was slightly higher and the proportion of other organs was relatively high. Conclusion:The 3DVH model can be accurately established and tested with the acceptance test method in the present study, which can provide detailed information for dose verification.

Objective: To achieve quantitative analysis of image quality parameters and establish warning and action thresholds for the on-board imaging (OBI) system of linear accelerator. Methods: The Catphan604 phantom was repeatedly scanned in the Full-Fan and Half-Fan CBCT scanning modes on a Varian EDGE linear accelerator, and the software based on Python language development in-house was utilized to analyze image quality parameters, such as CT number linearity, geometric consistency, slice thickness, spatial resolution, uniformity and low-contrast resolution. The quantitative analysis results of each image quality parameter obtained from 16 times of scanning within 16 months were normalized to the mean and the standard deviations were recorded. A run chart analysis was created to determine the warnings and action thresholds. Results: The software built in-house can quantitatively analyze the image parameters of the two scanning modes of OBI system. The low-contrast resolution of Half-Fan was better than that of Full-Fan, whereas the spatial resolution of Full-Fan was superior to that of Half-Fan. One standard deviation (1σ) was set as the warning threshold and 2 standard deviations (2σ) as the action threshold, respectively. The tolerance level of Half-Fan was smaller than that of Full-Fan. Conclusion Self-developed software enables quantitative analysis of accelerator image quality parameters, establishes warning and action tolerance of quality assurance and provides guidance for image quality assurance under image-guided radiotherapy specification.

Objective:To investigate the advantages of Da Vinci robotic thyroidectomy in treatment of the unilateral papillary thyroid microcarcinoma (PTMC).Methods:The clinical data of 49 patients with unilateral thyroid cancer admitted to the First Hospital of Shanxi Medical University from June 2018 to March 2020 were retrospectively analyzed, and they were divided into Da Vinci robotic group (the experimental group, 18 cases) and conventional surgery group (the control group, 31 cases) according to the surgical method. The clinicopathological characteristics, perioperative and postoperative related indexes changes, length of hospital stay, incidence of surgical complications, and operation cost of both groups of patients were analyzed. Visual analogue scale (VAS) was used to evaluate postoperative pain.Results:There were statistically significant differences in age, marriage and education background of both groups (all P < 0.05). There were statistically significant differences in the number of central lymph node dissection [(4.3±2.0) vs. (6.5±3.9)], operation time [198.5 min (166.3 min, 228.5 min) vs. 82.0 min (60.0 min, 102.0 min)], pain score of 24 h after surgery [3 scores (3 scores, 4 scores) vs. 2 scores (2 scores, 3 scores)], postoperative total drainage volume [49.0 ml (40.8 ml, 56.5 ml) vs. 37.0 ml, (29.0 ml, 44.0 ml)], operation cost [33,200 yuan (33,100 yuan, 34,000 yuan) vs. 5,200 yuan (4,200 yuan, 5,900 yuan)], and differences were statistically significant (all P < 0.05). No postoperative complications such as hemorrhage, fat liquefaction and subcutaneous ecchymosis occurred in all patients of the two groups. Conclusion:Da Vinci robotic thyroidectomy is safe and reliable in treatment of the unilateral PTMC, and it has good therapeutic effects.

Objective To investigate the optimal distance between upper and lower target volumes and their correlated planning parameters by analyzing the dose distribution in the abutment regions during total body irradiation ( TBI) using helical tomotherapy. Methods A total of 10 patients with acute leukemia and with a height around 120 cm were enrolled. All patients were scanned by a Siemens simulation computerized tomography (CT) at a slice thickness of 5 mm. A lead wire was placed 10. 0 cm above the patella as a marker of the separation boundary for the upper and lower target volumes. The delineations of target volumes and organs at risk ( OARs ) were performed in the Varian Eclipse 13. 5 workstation with targets shrunk beyond the separation boundary at different distances. After contours and CT images were transferred to HT workstation, treatment plans were designed with different field width (FW, 5. 0 cm/2. 5 cm/1. 0 cm) and pitch values (0. 430/0. 287) at a modulation factor of 1. 8. All the plans were optimized with a dose calculation grid of 0. 195 cm × 0. 195 cm and identical planning parameters. The correlation between treatment planning parameters and targets shrunk distances were investigated by analyzing the dose distributions in the abutment area. Results The study demonstrated that the dose distributions in the abutment area were influenced only by the field width parameters: when the gap distance between the upper and lower targets was 5. 0 cm, the optimal FW is 5. 0 cm;Similarly when the gap distances were 2. 0 cm and 1. 0 cm, and the optimal FW 2. 5 cm and 1. 0 cm, respectively. In another words, the dose distribution of the abutment region was optimal when the target gap distance was equal to FW. Pitch values did not affect the quality of dose distribution in the abutment region and the overall treatment time ratio. Overall treatment time was inversely related to the FW. Conclusions Consistent target distance and FW is helpful to improve the dose homogeneity in the abutment area during TBI with HT. Appropriate planning parameters is critical to balance the treatment efficacy and efficiency.