Objective:To solve the problems in intensity-modulated radiation therapy (IMRT) planning, such as large labor cost and high dependence on the experience of physicists and great inconsistency in the quality of plan, and to discuss an unsupervised automatic treatment planning procedure of IMRT.Methods:The eclipse scripting application programming interface (ESAPI) within the Eclipse treatment planning system (TPS) 15.6 and optimization parameters tree search algorithm (OPTSA) were used to emulate and realize the whole planning process. Interacted with the TPS through ESAPI, relevant dosimetric parameters were input and output. The OPTSA evaluated the plan qualities based on dosimetric parameters of the targets and organs at risk (OARs) and iteratively adjusted the optimization objective parameters to achieve a progressively improving IMRT plan. In order to verify the effectiveness of the automatic planning, twenty historical rectum cancer cases were selected from the clinical database, and the dose distribution and specific dosimetric parameters were compared between the plans generated by the OPTSA and the manual plans under the same constraints.Results:All the auto plans have met clinical requirements. Furthermore, 90% and 10% of the auto plans were deemed as clinically improved and equally compared with the manual plans, respectively. The average CI for the PTV was 0.88 and 0.80 for the auto and manual plans respectively. Compared with the manual plans, the mean doses of all the OARs in the auto plans were reduced by 11% in average. The average elapsed time of automatic planning and manual planning was (28.15±3.61) and (36.7±4.6) min, respectively.Conclusions:The plans created by the proposed algorithm have been shown to be at least as good as the manual plans. In addition, this method can shorten the labor time in plan designing while ensuring the plan quality and consistency of the plan.

Objective:To investigate the performance of W2 plastic scintillator in megavolt photon and electron beams.Methods:The photon and electron beam energy provided by linear accelerator was used to collect data of the W2 scintillator. The parameters include the electrometer reading stability, W2 dose and dose rate linearity, and angular response. And the dose uncertainty of the W2 correction factors was also investigated.Results:The standard deviation of the electrometer reading stability was between 0.03 and 0.47. The linear regression factors of W2 dose were all 1.0; the maximum deviation of the dose rates was 0.61%. The Cerenkov light radiation correction factor(CLR) for 6 and 10 MV were 0.741 and 0.746, respectively, and the CLR for 6, 9, 12 and 15 MeV were 0.750, 0.753, 0.757 and 0.757, respectively. The maximum deviation of dose uncertainty for 15 MeV was 3.15%.Conclusions:The signal obtained by the blue and green channel was no angular dependence, the same as the high-energy electron beam, which verified that the Cerenkov radiation correction factor has good linearity. W2 plastic scintillator can be applied to non-coplanar radiotherapy dosimetry.

Objective To investigate the influence of preoperative splenectomy on the prognosis after liver transplantation.Methods The retrospective cohort study was conducted.The clinical data of 95 patients who underwent liver transplantation in the Third Affiliated Hospital of Sun Yat-sen University between January 2004 and January 2014 were collected.Thirty-five patients undergoing preoperative splenectomy and pericardial devascularization and 60 undergoing spleen-preserving liver transplantation were allocated into the study group and control group,respectively.All patients received modified piggyback liver transplantation by the same team.Observation indicators:(1) intra-and post-operative situations;(2) follow-up and survival.The follow-up using telephone interview and outpatient examination was performed once every a week within 3 months postoperatively,once every one month within 6 months postoperatively and once every 3 months after 1 year postoperatively up to January 2016,including routine blood test,plasma-drug concentration of immunosuppressive agent and function of liver and kidney.Ultrasound and abdominal CT were used to monitor the long-term complication and survival.The measurement data with normal distribution were represented as (x)±s,and comparison between groups was done by the t test.Comparison of count data was done by the chi-square test.Results (1) Intra-and post-operative situations:all patients underwent successful liver transplantation.The operation time,volumes of intraoperative blood loss and blood transfusion were (483 ± 136) minutes,(5 683±2 950) mL,(4 887±3 682) mL in the study group and (392± 103)minutes,(3 522± 1 885)mL,(3 455±2 630)mL in the control group,respectively,with statistically significant differences between groups (t=3.683,4.358,2.202,P＜0.05).Six patients in the study group had intraoperative portal vein thrombosis (PVT),including 4 in level 1,1 in level 2 and 1 in level 3,and no patients in the control group,showing a statistically significant difference between groups (x2 =1.979,P＜0.05).Five patients with PVT in level 1 or 2 underwent thrombectomy and then end-to-end anastomosis of PV.One patient with PVT in level 1 had PVT recurrence and was cured by postoperative thrombolytic therapy.One patient with PVT in level 3 received PV reconstruction using artificial blood vessels,and had PVT recurrence and then was cured.There was no PV stenosis between groups.The levels of platelet at 1,3 and 7 days postoperatively were (75±60)× 109/L,(71± 45)×109/L,(111±73)×109/L in the study group and (57±32) ×109/L,(52±46) ×109/L,(87±53)×109/L in the control group,respectively,with statistically significant difference between groups (t =1.909,1.957,1.848,P＜ 0.05).The levels of platelet at 14 and 30 days postoperatively were respectively (230± 152)× 109/L,(310± 140)× 109/L in the study group and (193± 125)× 109/L,(286±62)× 109/L in the control group,with no statistically significant difference between groups (t=1.284,1.199,P＞0.05).The cases with postoperative infection,acute rejection,new-onset PVT in level 1-2 and 3-4 and PV stenosis were respectively 23,0,2,0,2 in the study group and 35,1,2,0,1 in the control group,with no statistically significant difference between groups (x2 =1.171,0.590,0.547,1.184,P＞0.05).Patients with postoperative infection and acute rejection were improved by symptomatic treatment.Two patients in the study group with PVT underwent anticoagulant and thrombolytic therapy,including 1 receiving interventional thrombectomy therapy.Two patients in the control group with new-onset PVT were cured by anticoagulant and thrombolytic therapy.Three patients with PV stenosis underwent percutaneous transhepatic portography (PTA) for balloon dilation,including 1 in the study group with good improvement after stent implantation.(2) Follow-up and survival:95 patients were followed up for 3-24 months,with an average time of 18 months.During the follow-up,the rate of chronic rejection in study and control groups was 5.7％(2/35) and 5.0％(3/60),showing no statistically significant difference between groups (x2 =0.023,P＞0.05).The 1-and 2-year accumulative survival rates were respectively 91.4％ (32/35),82.9％ (29/35) in the study group and 93.3％ (56/60),76.7％(46/60) in the control group,with no statistically significant difference between groups (x2 =0.780,P＞0.05).Conclusion The splenectomy before liver transplantation is easy to form PVT,increase time and difficulty of transplantation surgery,however,it doesn't increase complication risk after transplantation and affect postoperative survival.

Objective To introduce the simplified "All in one" hepatic vein reconstruction in right split liver transplantation, and to investigate the clinical indications, surgical procedures and clinical prognosis of this technique. Methods Clinical data of 2 recipients undergoing right split liver transplantation were retrospectively analyzed, and the simplified "All in one" hepatic vein reconstruction of right liver lobe was summarized and analyzed. In 2 cases, the right liver lobe was split in vivo. In case 1, the liver parenchyma was split until the first and second porta hepatis, and then the liver was obtained by whole-liver perfusion after cutting off the right hepatic duct, and the hepatic blood vessels were isolated ex vivo. In case 2, the left liver lobe was obtained during splitting in vivo and the right liver lobe was obtained after perfusion in vivo. During donor liver splitting in two cases, the common trunk of the middle hepatic vein was maintained in the left liver lobe, the S5 and S8 hepatic veins of the right liver lobe were reconstructed by the same donor iliac artery, and directly anastomosed with the gap between the left and middle hepatic veins of the inferior vena cava, thus reconstructing the integrity of the posterior inferior vena cava. Results The simplified "All in one" right hepatic vein reconstruction was adopted. The anhepatic phase of two recipients undergoing liver transplantation was 41 and 36 min. After the liver was incised open, the blood flow of the donor liver was normal, the iliac artery bypass was fully filled, liver congestion or swelling was not observed, and liver function was properly recovered after surgery. Two recipients were subject to postoperative follow-up for 23 and 10 months, respectively, No complications related to hepatic venous outflow tracts were noted, such as hepatic vein and inferior vena cava. Conclusions "All in one" hepatic vein reconstruction may simplify the procedures of hepatic venous outflow tract reconstruction, shorten the anhepatic phase and reduce the incidence of postoperative hepatic vein complications in complete right liver split transplantation.

Objective To investigate the anatomical classification of left intrahepatic bile duct (LHD) and the pattern of bile duct reconstruction during pediatric split liver transplantation and their relationship with postoperative biliary complications. Methods Clinical data of 75 pediatric recipients undergoing split liver transplantation were analyzed retrospectively. Before splitting the donor liver, iopromide injection was used for retrograde cholangiography through the common bile duct. According to the patterns of intrahepatic bile ducts in the second, third and fourth segments, the anatomical classification of LHD of the donor liver was determined. The biliary reconstruction regimens for different classification types of LHD were summarized. The incidence and treatment of biliary complications after pediatric split liver transplantation were analyzed. Results Among 75 donor livers, the anatomical classification of LHD included 57 cases (76%) of type Ⅰ, 9 cases (12%) of type Ⅱ, 4 cases (5%) of type Ⅲ and 5 cases (7%) of type Ⅳ LHD, respectively. Among 75 pediatric recipients, 69 cases (53 cases of type Ⅰ, 8 type Ⅱ, 4 type Ⅲ and 4 type Ⅳ) underwent the left hepatic duct-jejunum Roux-en-Y anastomosis, 1 case received common bile duct-jejunum Roux-en-Y anastomosis (type Ⅳ), and 5 cases underwent the left hepatic duct-common bile duct end-to-end anastomosis (4 cases of type Ⅰ and 1 type Ⅱ). Postoperative biliary complications occurred in 6 cases (8%), including 3 cases of biliary anastomotic stenosis, 2 cases of biliary anastomotic leakage and 1 case of bile leakage on the hepatic resection surface. Among 6 recipients, 4 cases were classified as type Ⅰ and 2 cases of type Ⅲ LHD. No significant difference was observed in the incidence of biliary complications between typical type and anatomical variant type of LHD (all P > 0.05). Among 3 recipients with biliary anastomotic stenosis, 2 cases underwent percutaneous transhepatic cholangial and drainage (PTCD) and 1 case repeatedly received biliary-intestinal anastomosis. Two cases of biliary anastomotic leakage underwent PTCD and 1 case of bile leakage on the hepatic resection surface received local drainage. All 6 children survived after treatment. Conclusions Anatomical variation of LHD can be observed in 24% of donor livers, and type Ⅱ accounts for the highest proportion of 12%. Prior to donor liver splitting, routine cholangiography and fine biliary anastomosis may effectively lower the incidence of biliary complications. The incidence of postoperative biliary complications is not significantly associated with the anatomical classification of LHD.

Objective:To assess the three-dimensional dose distribution in radiotherapy plans using the structural similarity index(SSIM), compare the performance of SSIM with commonly used quality assessment indices, and develop a SSIM-based quality assessment method of multiple prescribed doses.Methods:The SSIM was introduced to providea quality score of various voxels by comparing actual and ideal three-dimensional dose data and combining the spatial location information of the voxels. Then the average value in a region of interest (ROI) was calculated as the quality score of the region. Fifty-three cases of cervical cancer were selected to analyze the correlation of the SSIM with the uniformity index (HI), conformity index (CI) of the dose distribution in various ROIs and to explore the capability of the SSIM to reflect the uniformity and conformity of dose distribution.Two types of quality defects were individually introduced into two of 53 radiotherapy plans. Then the two plans were compared with normal plans to characterize the response of the SSIM.Results:There was no correlation between HI and SSIM in positive lymph nodes(PGTVnd) due to the decrease in the HI sensitivity, while there was a significant negative correlation between them in regions where PGTVnd was removed from the planning target volume(PTV, R=-0.86, P<0.01). Meanwhile, there was a significant positive correlation between CI and SSIM in PGTVnd ( R=0.83, P<0.01). Therefore, the SSIM can be used to identify the artificial design defects in plans by determining abnormal dose gradients. Conclusions:Apart from reducing the defects of previous assessment parameters, the SSIM has the capability to assess the quality of radiotherapy plans by combining the uniformity and conformity of dose distribution and can provide accurate feedback on the spatial locations of quality defects.

Objective:To develope an automatic volumetric modulated arc therapy (VMAT) planning for rectal cancer based on a dose-prediction model for organs at risk(OARs) and an iterative optimization algorithm for objective parameter optimization.Methods:Totally 165 VMAT plans of rectal cancer patients treated in Peking University Cancer Hospital & Institute from June 2018 to January 2021 were selected to establish automatic VMAT planning. Among them, 145 cases were used for training the deep-learning model and 20 for evaluating the feasibility of the model by comparing the automatic planning with manual plans. The deep learning model was used to predict the essential dose-volume histogram (DVH) index as initial objective parameters(IOPs) and the iterative optimization algorithm can automatically modify the objective parameters according to the result of protocol-based automatic iterative optimization(PBAIO). With the predicted IOPs, the automatic planning model based on the iterative optimization algorithm was achieved using a program mable interface.Results:The IOPs of OARs of 20 cases were effectively predicted using the deep learning model, with no significantly statistical difference in the conformity index(CI) for planning target volume(PTV)and planning gross tumor volume(PGTV)between automatic and manual plans( P>0.05). The homogeneity index (HI) of PGTV in automatic and manual plans was 0.06 and 0.05, respectively( t=-6.92, P< 0.05). Compared with manual plans, the automatic plans significantly decreased the V30 for urinary bladder by 2.7% and decreased the V20 for femoral head sand auxiliary structure(avoidance)by 8.37% and 15.95%, respectively ( t=5.65, 11.24, P< 0.05). Meanwhile, the average doses to bladder, femoral heads, and avoidance decreased by 1.91, 4.01, and 3.88 Gy, respectively( t=9.29, 2.80, 10.23, P< 0.05) using the automatic plans. The time of automatic VMAT planning was (71.49±25.48)min in 20 cases. Conclusions:The proposed automatic planning based on dose prediction and an iterative optimization algorithm is feasible and has great potential for sparing OARs and improving the utilization rate of clinical resources.

Objective To compare two pretreatment plan QA methods for HalcyonTM accelerator using Portal Dosimetry (PD),and PTW OCTAVIUS 1500 detector array + Octagonal phantom (Oct 1500)respectively.Methods Parallel measurement-based pretreatment QA using two methods was performed for 22 IMRT/VMAT plans (74 fields) that have been used to treat 20 patients recruited in the Halcyon clinical trial.Several γ 2D comparisons were also applied to provide guidelines for Halcyon planning QA.Results Using Oct1500 method,the γ 2D passing rates for 74 fields in 22 Plans were 95.26±3.59,95.01±3.62 (Local Dose),99.05± 1.35,98.57± 1.96 (Max Dose) respectively.Two-related samples non-parametric tests suggested that the differences between the evaluation criteria were of statistical significance (Z =-7.220,-4.108,P＜0.05).For PD method,the γ 2D passing rates were 84.11％ ± 1.35％ (1 mm/1％),99.07％± 1.35％ (2 mm/2％),and 99.86％ ± 1.35％ (3 mm/3％).Two-related samples non-parametric tests suggested that the differences between evaluation criteria of PD method were statistically significant (Z =-7.475,-7.475,-6.906,P＜0.05).For 74 fields and max dose,3 mm/3％ evaluation criteria,two-related samples non-parametric tests suggested that the differences between PD and Oct1500 method were statistically significant (Z=-5.072,P＜0.05).Conclusions Both methods can be used for Halcyon pretreatment plan QA.PD is superior to Oct1500 with respect to efficiency and spatial resolution-induced verification accuracy.The criteria of 2 mm/2％ for PD,and Max Dose/3 mm/3％ for Oct1500 was suggested.

Objective:To investigate the anatomic classification and reconstruction of right intrahepatic bile duct in the donor liver of split liver transplantation (SLT).Methods:The retrospective and descriptive study was constructed. The clinical data of 85 patients who underwent SLT in the Third Affiliated Hospital of Sun Yat-sen University from July 2014 to January 2022 were collected. There were 65 males and 20 females, aged 45(range, 1-82)years. Observation indicators: (1) surgical conditions; (2) anatomy of right intrahepatic bile duct; (3) bile duct reconstruction; (4) postoperative biliary complications; (5) follow-up. Measurement data with normal distribution were represented as Mean± SD, and measurement data with skewed distribution were represented as M(range) or M( Q1, Q3).Count data were described as absolute numbers or percentages, and comparison between groups was conducted using the chi-square test or Fisher exact probability. Results:(1) Surgical conditions. Of the 85 donor livers, 11 donor livers were split between the left and right hemilivers, and 74 donor livers were split between the classic right trilobe and left lateral lobe. The cold ischemia time of 85 donor livers was 291(273, 354)minutes, and the operation time, anhepatic phase time and volume of intraoperative blood transfusion of 85 recipients were (497±97)minutes, 51(40, 80)minutes and 8(7, 12)U. (2) Anatomy of right intrahepatic bile duct. Of the 85 donor livers, there were 47 donor livers with classic bile duct anatomical model (type 1), of the ratio as 55.3%(47/85), and 38 donor livers with anatomical variants, of the ratio as 44.7%(38/85). Of the 38 donor livers with anatomical variants, 7 donor livers were type 2, 16 donor livers were type 3a, 2 donor livers were type 3b, 2 donor livers were type 3c, 1 donor liver was type 4, 3 donor livers were type 5a, 4 donor livers were type 5b, 3 donor livers were type 6. For bile duct splitting patterns of the 85 donor livers, 84 donor livers were split with the main trunk of common hepatic duct preserving in the right hemiliver or right trilobe, and 1 donor liver were treated with complete left and right hemiliver splitting to preserve the main trunk of the common hepatic duct in the left hemiliver and the right hemiliver in the right hepatic duct (type 1 bile duct anatomical model). There were 84 donor livers with only one bile duct opening, and 1 donor liver with two bile duct openings (type 3c bile duct anatomical model). (3) Bile duct reconstruction. Of the 85 recipients, there were 69 recipients with common bile duct end-to-end anastomosis to common bile duct of donor liver (38 donor livers with type 1 bile duct anatomical model, 5 donor livers with type 2 bile duct anatomical model, 14 donor livers with type 3a bile duct anatomical model, 2 donor livers with type 3b bile duct anatomical model, 1 donor liver with type 4 bile duct anatomical model, 3 donor livers with type 5a bile duct anatomical model, 4 donor livers with type 5b bile duct anatomical model, 2 donor livers with type 6 bile duct anatomical model), 11 recipients with jejunum anastomosis to common bile duct of donor liver (7 donor livers with type 1 bile duct anatomical model, 2 donor livers with type 2 bile duct anatomical model, 1 donor liver with type 3c bile duct anatomical model, 1 donor liver with type 6 bile duct anatomical model), 3 recipients with jejunum anastomosis to common hepatic duct of donor liver (1 donor liver with type 1 bile duct anatomical model, 2 donor livers with type 3a bile duct anatomical model), 1 recipient with jejunum anastomosis to right hepatic duct of donor liver (type 1 bile duct anatomical model), 1 recipient with common hepatic duct end-to-end anastomosis to right posterior branch of donor liver combined with jejunum of the recipient Roux-en-y anastomosis to common hepatic duct of donor liver (type 3c bile duct anatomical model). (4) Postoperative biliary complications. Of the 85 recipients, 6 cases had postoperative biliary complications, with an incidence of 7.1% (6/85). Of the 6 recipients with postoperative biliary complications, there were 5 recipients with donor liver with type 1 bile duct anatomical model, including 3 cases undergoing postoperative biliary stricture with biliary leakage and 2 cases undergoing postoperative biliary anastomotic stricture, 1 recipient with donor liver with type 3b bile duct anatomical model and undergoing postoperative biliary anastomotic stricture and bile leakage in the liver section. Cases with biliary complications were 5 in the 47 recipients with donor liver with classic bile duct anatomical model and 1 in the 38 recipients with donor liver with anato-mical variants, showing no significant difference between them ( P>0.05). (5) Follow-up. There were 83 recipients receiving followed up for 52(12,96)months. During the follow-up period, 2 recipients died due to non-biliary complication factors (1 donor liver with type 1 bile duct anatomical model and 1 donor liver with 3a bile duct anatomical model). Conclusion:The anatomical classification of right intrahepatic bile duct of donor liver in SLT is mainly classical bile duct anatomical model, and the bile duct reconstruction scheme is mainly common bile duct of donor liver end-to-end anasto-mosis to common bile duct of recipient.

Objective To investigate the safety and feasibility of a simplified protocol combining with mesenchymal stem cell (MSC) in ABO-incompatible (ABO-I) liver transplant patients. Methods Twelve ABO-I liver transplant patient who received the therapy of a simplified protocol combining with MSC in the Third Affiliated Hospital of Sun Yat-sen University between January 2014 and September 2015 were recruited in this prospective study. Ten cases were male and 2 were female, with a mean age of (39±13) years old. The informed consents of all patients or their families were obtained and the local ethical committee approval was received. A immunologic tolerance induction protocol, plasma exchange + rituximab + intravenous immunoglobin + MSC (simplified protocol combining with MSC and without splenectomy and graft local infusion), was used to prevent the antibody-mediated rejection (AMR) after liver transplantation (LT). The perioperative condition and postoperative outcome of the patients were observed. Results Three death cases were observed after LT including 2 cases died of multiple organ failure and 1 of gastrointestinal hemorrhage. The other cases survived. Two cases developed acute cellular rejection and no AMR case was observed. Biliary complication was observed in 3 cases, hepatic artery stenosis in 1 case and infection in 6 cases. Conclusion The simplified protocol combining with MSC is safe and effective in preventing the AMR after ABO-I LT.