The presence of magnetic fields in a magnetic resonance accelerator (MR-linac) can affect the reference dosimetry, and thus the existing Code of Practices (CoPs) are inadequate for MR-linac. In this article, the characteristics of adsorbed dose to water and ionization chamber response in the presence of magnetic fields were introduced and a formalism for reference dosimetry in MR-linac was developed based on the existing CoPs, aiming to provide reference for dosimetric quality control and research work of MR-linac in China.

Objective To compare the performance of two different deep learning models,VTcGAN and Pix2pix,in generating synthetic computed tomography(sCT)from magnetic resonance imaging(MRI)of nasopharyngeal carcinoma(NPC),and to evaluate their accuracies in treatment planning dose calculations.Methods MRI and CT images as well as treatment planning data of 115 NPC patients were retrospectively selected,and paired dataset was obtained through rigid image registration,with 105 cases as the training set,and the remaining 10 cases as the test set.Two kinds of models,namely Pix2pix model based on conventional convolutional neural network and the improved VTcGAN model based on Transformer network,were constructed with the consistent structure except for the bottleneck network in the generator.The generated sCT images(sCTPix2pix and sCTVTcGAN)were assessed in terms of image quality,intensity value and dosimetric differences.Results For the cases in test set,the mean error,mean absolute error,peak signal-to-noise ratio,and structural similarity index between the ground truth CT images and the sCTPix2pix were(-0.86±12.42)HU,(40.77±3.06)HU,(33.45±0.62)dB,and 0.928±0.013,respectively;and those between the ground truth CT images and the sCTVTcGAN were(-1.10±8.56)HU,(37.40±2.08)HU,(34.33±0.45)dB,and 0.936±0.009,respectively.For the criterion of 1 mm/1%,the averaged gamma passing rates of sCTPix2pix and sCTVTcGAN were(96.62±1.08)%and(96.88±0.99)%at a dose threshold of 10%,(94.31±1.03)%and(94.72±0.91)%at a dose threshold of 50%,(84.62±1.74)%and(86.06±1.41)%at a dose threshold of 80%,respectively.Conclusion The proposed VTcGAN model is superior to the traditional Pix2pix model in terms of accuracy in generating sCT from MRI of NPC,and it can fulfill the requirements for dose calculation in the MRI-Only workflow.

Objective To compare the performance of two different deep learning models,VTcGAN and Pix2pix,in generating synthetic computed tomography(sCT)from magnetic resonance imaging(MRI)of nasopharyngeal carcinoma(NPC),and to evaluate their accuracies in treatment planning dose calculations.Methods MRI and CT images as well as treatment planning data of 115 NPC patients were retrospectively selected,and paired dataset was obtained through rigid image registration,with 105 cases as the training set,and the remaining 10 cases as the test set.Two kinds of models,namely Pix2pix model based on conventional convolutional neural network and the improved VTcGAN model based on Transformer network,were constructed with the consistent structure except for the bottleneck network in the generator.The generated sCT images(sCTPix2pix and sCTVTcGAN)were assessed in terms of image quality,intensity value and dosimetric differences.Results For the cases in test set,the mean error,mean absolute error,peak signal-to-noise ratio,and structural similarity index between the ground truth CT images and the sCTPix2pix were(-0.86±12.42)HU,(40.77±3.06)HU,(33.45±0.62)dB,and 0.928±0.013,respectively;and those between the ground truth CT images and the sCTVTcGAN were(-1.10±8.56)HU,(37.40±2.08)HU,(34.33±0.45)dB,and 0.936±0.009,respectively.For the criterion of 1 mm/1%,the averaged gamma passing rates of sCTPix2pix and sCTVTcGAN were(96.62±1.08)%and(96.88±0.99)%at a dose threshold of 10%,(94.31±1.03)%and(94.72±0.91)%at a dose threshold of 50%,(84.62±1.74)%and(86.06±1.41)%at a dose threshold of 80%,respectively.Conclusion The proposed VTcGAN model is superior to the traditional Pix2pix model in terms of accuracy in generating sCT from MRI of NPC,and it can fulfill the requirements for dose calculation in the MRI-Only workflow.

The presence of magnetic fields in a magnetic resonance accelerator (MR-linac) can affect the reference dosimetry, and thus the existing Code of Practices (CoPs) are inadequate for MR-linac. In this article, the characteristics of adsorbed dose to water and ionization chamber response in the presence of magnetic fields were introduced and a formalism for reference dosimetry in MR-linac was developed based on the existing CoPs, aiming to provide reference for dosimetric quality control and research work of MR-linac in China.

Objective To investigate the surgical method and clinical outcome using the free anterolateral thigh flap with the medial gastrocnemius artery as the recipient artery for the repair of complex wounds in the lower leg. Methods A retrospective analysis was conducted on the clinical data of 11 patients with complex wounds in the lower leg admitted to Suzhou Ruihua Orthopedic Hospital from October 2020 to September 2022. All patients had extensive skin and subcutaneous soft tissue defects in the lower leg and received free anterolateral thigh flap repair with the medial gastrocnemius artery as the recipient artery. The skin of donor site was directly sutured. Results All 11 free skin flap survived in 11 patients, and both the donor and recipient sites healed in stage I. All patients were followed up after discharge, with a follow-up time of 12 to 35 months. The follow-up results at 12 months postoperatively showed good wound healing, good flap appearance and elasticity, restoration of normal knee and ankle joint function, and independent living ability. The donor site wounds healed well without significant scar hyperplasia. At the last follow-up, the flap sensory function was graded as S₃ in 2 patients and S₂ in 9 patients. The functional score of the affected limb was excellent in 5 patients and good in 6 patients, with an excellent and good rate of 100%. Conclusion The medial gastrocnemius artery has a suitable vessel caliber for anastomosis and a constant location. The use of the free anterolateral thigh flap with this artery as the recipient artery for the repair of severe wounds in the lower leg can effectively cover soft tissue defects and avoid injuring the residual main vessels in the lower leg, resulting in satisfactory outcomes.

Objective:To explore the clinical outcomes of locking compression plating (LCP) in the treatment of periprosthetic fracture (PPF) of the distal femur in the aged patients.Methods:A retrospective study was performed to analyze the 31 aged patients who had been treated at Department of Orthopedic Surgery, The Affiliated Hospital to Nantong University for PPF of the distal femur with LCP between June 2012 and May 2023. There were 27 females and 4 males with an age of (80.2±6.1) years. According to the Unified Classification System (UCS), 18 PPFs were classified as type Ⅴ.3B1 and 6 PPFs as type Ⅴ.3B2 after total knee arthroplasty and 7 PPFs as type Ⅳ.3C after total hip arthroplasty. The patients were fixated with a lateral single plate in 25 cases, and with lateral and medial dual plates in 6 cases. The surgical time, intraoperative blood loss, hospitalization time, postoperative weight-bearing time, fracture healing time, and knee joint function and complications during follow-up were recorded.Results:For the 25 patients undergoing fixation with a lateral single plate, the surgical time was (58.7±7.9) minutes, the intraoperative blood loss (78.0±15.1) mL, the hospitalization time (6.9±1.6) days, the postoperative weight-bearing time (5.9±1.4) days, and the follow-up time 37 (15, 51) months. For the 6 patients undergoing fixation with lateral and medial dual plates, the surgical time was (186.6±9.8) minutes, the intraoperative blood loss (1,256.7±231.2) mL, the hospitalization time (17.8±3.3) days, the postoperative weight-bearing time (3.6±0.6) days, and the follow-up time 17 (16, 21) months. The fracture healing time was (14.9±2.0) and (18.7±2.6) weeks, respectively, for patients fixed with single and double steel plates. By the scoring criteria of the American Hospital for Special Surgery (HSS), the knee joint function was evaluated at the last follow-up as excellent in 10 cases and as good in 15 cases for the 25 patients undergoing fixation with a lateral single plate, and as good for all the 6 patients undergoing fixation with lateral and medial dual plates. No patient experienced such complications as incision infection, bone nonunion, or internal fixation failure during the follow-up period.Conclusions:LCP fixation can achieve satisfactory outcomes in the treatment of PPF of the distal femur in the aged patients. As fixation with a single lateral femoral plate is suitable for most of the aged patients with PPF of the distal femur, it can be used as the first choice. Fixation with dual plates can provide stronger stability, but its indications should be strictly controlled.

Objective:To explore the feasibility of applying ArcherQA to independent dose verification of MR-guided online adaptive radiotherapy (ART) plans performed on Elekta Unity 1.5 Tesla (T) magnetic resonance-linear accelerator (MR-Linac).Methods:The dose calculation accuracy of ArcherQA under a specific magnetic field was validated using a homogeneous water phantom. A total of 32 patients who received MR-guided online ART on Elekta Unity were randomly selected by lottery, with 32 offline plans and 177 online plans for five treatment sites (brain, mediastinum, liver, kidney, and vertebral body) enrolled. Finally, the γ pass rates (threshold: 10%; criteria: 3 mm/3% and 2 mm/2%) were compared among the result upon independent dose verification of ArcherQA, measurements of ArcCheck, and calculations using the Monaco treatment planning system (TPS) to quantitatively evaluate the accuracy and efficiency of ArcherQA in independent dose verification of online plans on Elekta Unity.Results:ArcherQA was proven accurate in calculating the dose distribution of therapeutic photon beams under the specific magnetic field. With the 3 mm/3% criterion, the γ pass rates of verification result exceeded 99% in all square fields of a water phantom. Under the stricter 2 mm/2% criterion, the γ pass rates also surpassed 95% in all square fields except 20 cm × 20 cm field. Regarding the verification of treatment plans, the ArcherQA result were found to be highly consistent with those measured or calculated using ArcCheck and Monaco TPS, with the average γ pass rates exceeding 99% under the 3 mm/3% criterion and above 97% under the 2 mm/2% criterion. ArcherQA was acceptably efficient for independent dose verification of online plans, with 50 to 150 s, (108 s on average) required to complete the independent dose verification of 177 online plans.Conclusions:ArcherQA allows for accurately and efficiently calculating the dose distribution of therapeutic photon beams under a specific magnetic field, establishing it as an effective supplementary tool for independent dose calculation of MR-guided offline and online ART plans, thereby ensuring the safety of patient treatment plans.

Objective:To explore the relationship between childhood trauma and anxiety in vocational school students, and to analyze the mediating role of emotion dysregulation.Methods:A cross-sectional survey was conducted in one vocational school in Ganzhou, all students completed a series of questionnaires, including the childhood trauma questionnaire (CTQ), difficulties in emotion regulation scale (DERS), and generalized anxiety disorder scale (GAD-7).The cut-off score for anxiety symptom was set GAD-7≥5.The data were analyzed using SPSS 23.0 and SPSS macro program PROCESS V4.0.Results:(1) The rate of anxiety in vocational school students was 42.96%, and girls were 27.1% higher than boys ( OR=1.271, 95% CI=1.095-1.474).(2) The CTQ (44(38, 51)) and DERS (98(89, 111)) in students with anxiety were both significantly higher than those in students without anxiety (39(34, 45), 81(73, 90), Z=-17.910, -33.859, both P<0.001).(3) Regression analysis showed that girls ( β=0.240, OR=1.271, 95% CI=1.095~1.474), childhood trauma ( β=0.028, OR=1.028, 95% CI=1.019~1.037), and emotion dysregulation ( β=0.076, OR=1.080, 95% CI=1.073-1.086) were significant predictors for anxiety.(4) Path analysis and mediating effect showed that childhood trauma positively predicted anxiety ( β=0.059, 95% CI=0.048-0.071) and emotion dysregulation ( β=0.802, 95% CI=0.749-0.854), and emotion dysregulation positively predicted anxiety ( β=0.139, 95% CI=0.132-0.145).Emotion dysregulation had a significant mediating effect (effect value=0.112, 95% CI=0.101-0.121) in the relationship between childhood trauma and anxiety, with the indirect effect accounting for 65.50% of the total effect. Conclusion:The incidence of anxiety symptoms is high among vocational school students, and childhood trauma not only directly affects anxiety symptoms, but also indirectly affects anxiety symptoms through emotion dysregulation.

Objective To explore the protective effect of polypeptide Apelin on podocyte mitochondria in diabetic nephropathy and underling mechanisms.Methods Human renal podocytes were divided into four experimental groups:control group,high glucose(HG)group(glucose 25 mmol/L,48 h),Apelin intervention HG group(Ape-lin-13 1 μmol/L,48 h)and Apelin group(Apelin-13 1 μmol/L,48 h).The podocyte apoptosis was observed by TUNEL staining,the expression of mitochondrial membrane protein FUNDC1 was detected by Western blot,and the binding of mitochondrial fission protein DRP1 to FUNDC1 was examined by immunoprecipitation.The 8-week-old male mice were divided into three experimental groups:control group,diabetes group(intraperito-neal injection of streptozotocin 150 mg/kg,only one time)and Apelin intervention DM group(intraperitoneal injection of Apelin-13 0.3 μmol/kg,daily).The morphology of renal was observed by PAS staining and trans-mission electron microscopy.Plasma creatinine(Cr),urea nitrogen,urinary albumin and creatinine were de-tected by ELISA kit.The level of creatinine clearance rate(Ccr)and urinary albumin/creatinine(ACR)was calculated.Results Compared with the control group,the podocyte apoptosis and expression of FUNDC1 in the HG group increased significantly(P＜0.05),and the combination of mitochondrial fission division protein DRP1 to FUNDC1 raised.Meanwhile,compared with the HG group,the number of apoptosis,the expression of FUNDC1(P＜0.05),and the combination of DRP1 to FUNDC1 all reduced in Apelin intervention HG group.Animal experiments showed that the kidney structure of the control group was intact.In the DM group,the num-ber of podocytes decreased significantly,the foot processes were fused and dropped off.In the Apelin intervention DM group,podocyte lesions were less severe than those in the DM group.Compared with the control group,the level of plasma Cr,BUN and urine ACR in the DM group increased,while the level of Ccr decreased significantly(P＜0.05).However,compared with the DM group,the level of above biomarkers in the Apelin intervention DM group was improved(P＜0.05).Conclusions Apelin keeps mitochondrial homeostasis and reduces podocyte ap-optosis by inhibiting the expression of mitochondrial membrane protein FUNDC1,which may contribute to allevia-tion of diabetic nephropathy.

Objective To analyze the individualized CTV-to-PTV margin dose and positioning errors in radiotherapy for esophageal cancer for improving the treatment accuracy while meeting dose requirements.Methods Fifty-four esophageal cancer patients admitted to Sun Yat-sen University Cancer Center at Huangpu District from June 2021 to June 2022 were enrolled.All of the patients underwent CBCT scans in each fraction,and a total of 1283 CBCT images were collected.The image registration between CBCT image before radiotherapy and planning CT image was carried out to obtain errors in vertical(VRT),longitudinal(LNG),lateral(LAT),Roll,Pitch,and YAW directions.The mean values of six-dimensional positioning errors in the first 5 fractions were calculated,and the results were compared with the total fractional errors using the single sample t-test method for determining the differences.The CTV-to-PTV margin was calculated with the formula(margin=2.5∑+0.7δ),and the calculated margins were divided into 5 groups:Group A(5 mm expansion in all directions),Group B(7.9 mm expansion in LAT direction,and 5 mm expansion in other directions),Group C(11.03 mm expansion in LNG direction,and 5 mm expansion in the other directions),Group D(6.36 mm expansion in VRT direction,and 5 mm expansion in the other directions),and Group E(7.9 mm expansion in LAT direction,11.03 mm expansion in LNG direction,and 6.36 mm expansion in VRT direction).Simulation planning was conducted for 10 patients.Results The proportions of differences between the mean values of six-dimensional errors in the first 5 fractions and the total fractional errors in 54 patients were analyzed.There was no significant difference in 192 out of the 324 directions in 54 patients,accounting for 59.26%(P>0.05).Among them,the LAT,LNG,VRT,Pitch,Roll and YAW directions accounted for 64.81%,57.41%,51.85%,64.81%,57.41%and 59.26%of the total cases.The calculated CTV-to-PTV margin was 7.90,11.03 and 6.36 mm in LAT,LNG and VRT directions.The statistical analysis showed that the differences in the coverage rates of organs-at-risk and target areas among the 5 groups of CTV-to-PTV margins were trivial(P>0.05).Conclusion Using the positioning errors in the first 5 fractions of radiotherapy for esophageal cancer to predict subsequent positioning errors is feasible.The reasonable individualized margin in radiotherapy for esophageal cancer can reduce the inter-fractional off-target rate without increasing the dose delivered to organs-at-risk.The study provides a reference for the target volume margin of esophageal cancer and an important basis for precision treatment.