Objective:To conduct a comparative analysis of the radiation damage to zebrafish embryos and the associated biological mechanism after ultra-high dose rate (FLASH) and conventional dose rate irradiation.Methods:Zebrafish embryos at 4 h post-fertilization were exposed to conventional and FLASH irradiation (9 MeV electron beam). The mortality and hatchability of zebrafish after radiation exposure were recorded. Larvae at 96 h post-irradiation underwent morphological scoring, testing of reactive oxygen species (ROS) levels, and analysis of changes in oxidative stress indicators.Results:Electron beam irradiation at doses of 2-12 Gy exerted subtle effects on the mortality and hatchability of zebrafish embryos. However, single high-dose irradiation (≥ 6 Gy) could lead to developmental malformation of larvae, with conventional irradiation showing the most significant effects ( t = 0.87-9.75, P < 0.05). In contrast, after FLASH irradiation (≥ 6 Gy), the ROS levels in zebrafish and its oxidative stress indicators including superoxide dismutase (SOD), catalase (CAT), and malondialdehyde (MDA) were significantly reduced ( t = 0.42-15.19, P < 0.05). There was no statistically significant difference in ROS levels in incubating solutions after conventional and FLASH irradiation ( P > 0.05). Conclusions:Compared to conventional irradiation, FLASH irradiation can reduce radiation damage to zebrafish embryos, and this is in a dose-dependent manner. The two irradiation modes lead to different oxidative stress levels in zebrafish, which might be a significant factor in the reduction of radiation damage with FLASH irradiation.

FLASH radiotherapy (FLASH-RT) has garnered considerable attention globally in recent years. Compared to conventional radiotherapy, FLASH-RT can deliver the total radiation dose to the target volume in an extremely short time, reducing the radiation-induced damage to normal tissue while maintaining similar anti-tumor effects. FLASH-RT has been in the clinical trial stage, with several clinical research result being reported. Based on the collected global clinical research result of FLASH-RT in recent years, this study systematically reviewed FLASH-RT′s safety, radiation-related side effects, treatment efficacy, opportunities, and challenges in clinical trials.

Objective:To investigate the accuracy of magnetic resonance imaging (MRI) cine sequences in determining the range of tumor motion in radiotherapy, providing a basis for the precise delineation of the target volume in motion for radiation therapy.Methods:A modified chest motion phantom was placed in a MRI scanner, and a water-filled sphere was used to simulate a tumor. True fast imaging with steady precession (TrueFISP) MRI cine sequences from Siemens were used to capture the two-dimensional motion images of the simulated tumor. The phantom experiments were divided into three modes: head-foot motion mode, rotation motion mode, and actual respiratory waveform mode. In the head-foot motion mode, respiratory motion period (3, 4, 5, 6, 7 and 8 s), amplitude (5, 10 and 15 mm), and respiratory waveform of the simulated tumor (sin and cos4) were set, resulting in a total of 36 motion combinations. In the rotation motion mode, a cos4 waveform was used for respiration, with respiratory periods of 3, 4, 5, 6, 7 and 8 s, head-foot motion set amplitudes of 5, 10 and 15 mm, and anterior-posterior (AP) and left-right (LR) motion set amplitudes in three combinations ([2.5, 2.5] mm, [2.5, 5.0] mm, [5.0, 5.0] mm), resulting in a total of 54 motion combinations. In the actual respiratory waveform mode, respiratory waveforms of 5 randomly selected patients from Affiliated Cancer Hospital of Zhengzhou University were obtained. Under each motion combination, TrueFISP cine images (30 frames, with an acquisition time of 11 s per frame) were obtained. The code was used to automatically identify the two-dimensional coordinates of the center of the simulated tumor in each image, and sin and cos4 functions were separately employed to fit the tumor position in the motion direction, thereby obtaining the fitted motion period and amplitude. The difference between the maximum and minimum values of the tumor's center coordinates in the head-to-foot direction is taken as the range of movement, referred to as the calculated amplitude. For the actual respiratory waveform, the distance between the measured maximum and minimum positions is used to calculate the amplitude.Results:In the head-foot motion mode, the fitted amplitudes of both sin and cos4 waveforms deviated from the set amplitudes by 0-0.51 mm, with relative deviations of 0%-4.2%. The deviation range between the calculated amplitudes and the set amplitudes of the two waveforms were 0.08-0.94 mm, with relative deviations of 1.1%-6.3%. In the rotation motion mode, the fitted amplitudes deviated from the set amplitudes by 0-0.61 mm, with relative deviations of 0%-6.2%. And the deviation range between the calculated amplitudes and the set amplitudes were 0.16-0.94 mm, with relative deviations of 0%-6.3%. In the actual respiratory waveform motion mode, the deviation range between the calculated amplitudes and the set amplitudes were 0.10-0.48 mm, with relative deviations of 2.2%-8.6%.Conclusion:TrueFISP cine sequences show minimal deviations in determining the range of tumor head-foot motion and effectively captures the tumor's movement state, thereby providing important support for the precise definition of the tumor movement target area during radiotherapy .

Objective:To explore the characteristic pathological manifestations of non-HLA antibodies after kidney transplantation (KT) and examine the differences of MFT values of non-HLA antibodies in different pathological manifestations.Methods:The study was conducted on KT recipients at the First Affiliated Hospital of Zhengzhou University from February 2021 to June 2023 with unexplained elevated serum creatinine. Patients undergoing pathological puncture and concurrent HLA antibody testing were included, focusing on those with DSA (MFI>4 000) and non-HLA antibody negativity. According to the detection results of non-HLA and HLA antibodies, they were assigned into two groups of non-HLA antibody positive (45 cases) and HLA-DSA positive (28 cases). Both non-HLA and HLA antibodies were detected by luminex single antigen microbeads, χ2, t or Mann-Whitney U nonparametric tests were utilized for examining the inter-group differences in pathological manifestations. The recipients with positive non-HLA antibodies were grouped according to the differential pathological features[microvascular inflammation group (22 cases) and non-microvascular inflammation group (23 cases), interstitial fibrosis group (39 cases) and non-interstitial fibrosis (9 cases) ]. MFI values of non-HLA antibodies were standardized and heat map was generated with R language ComplexHeatmap package. The differences of response values of non-HLA antibodies with different pathological manifestations were examined by rank-sum test. Results:The positive rates of microvascular inflammation were 48.9% (22/45) and 82.1% (23/28) in HLA-DSA positive and non-HLA antibody positive groups with statistical significance ( χ2=8.073, P=0.006). The positive rates of interstitial fibrosis in two groups were 80.8% (36/45) and 53.6% (15/28) and the difference was statistically significant ( χ2=5.726, P=0.021). The relative levels of anti-arachnotoxin receptor 1 (Latrophilin 1, LPHN1), keratin 8 (KRT8), keratin 18 (KRT18) and Sjogren's syndrome antigen B (SSB) were higher in microvascular inflammation group than those in non-microvascular inflammation group. The differences were statistically significant [559.50 (262.00, 801.25) vs 285.00 (183.00, 460.00), P=0.024; 504.50 (369.5, 725.25) vs 317.00 (231.50, 458.00), P=0.014; 672.50 (454.50, 969.50) vs 399.00 (246.50, 772.50), P=0.030; 967.50 (482.00, 2 066.50) vs 399.00 (246.50, 772.50), P=0.033]. The relative levels of anti-cyclic citrullinate peptide (CCP), colony-stimulating factor 2 (CSF2), intercellular adhesion molecule 1 (ICAM1) and collagen Ⅳ antibody were higher in interstitial fibrosis group than those in non-interstitial fibrosis group with statistical significance [100.00 (79.88, 167.50) vs 64.50 (37.00, 89.00), P=0.016; 146.25 (93.38, 244.75) vs 87.00 (66.00, 105.00), P=0.041; 132.50 (106.38, 229.50) vs 95.00 (55.00, 125.00), P=0.037; 432.50 (280.75, 653.75) vs 208.00 (192.00, 301.00), P=0.028]. Conclusions:As compared with HLA-DSA, the characteristic pathological manifestations of non-HLA antibodies post-KT include a lower incidence of microvascular inflammation and a higher incidence of interstitial fibrosis. For non-HLA antibody response values of characteristic pathological manifestations, the expressions of different non-HLA antibodies vary statistically.

Cycloaddition Reaction ; Molecular Structure ; Alkadienes

Objective:To explore the efficacy and safety of low-dose rabbit anti-human thymocyte globulin (rATG) for induction therapy of kidney transplantation (KT) in children.Methods:From October 2018 to May 2021, clinical data were reviewed retrospectively for 77 pediatric KT recipients on a low-dose rATG induction protocol.Recipient/graft survival rate, renal function recovery, acute rejection (AR) and adverse reactions were observed at 1 year post-operation.The postoperative changes of renal function were examined by Friedman’s test; According to the preoperative baseline data, Pearson’s Chi-square or Fisher's exact test was utilized for examining the influencing factors of postoperative AR.Results:A total of 16(20.78%) recipients had AR within the first 6 months post-operation.The incidence of delayed graft function (DGF) was 14.29%(11/77); The incidence of severe infection post-transplantation 18.18%(14/77), the infection rate of BK virus 25.97%(20/77) and the incidence of neutropenia 32.47%(25/77).The recipient/graft survival rate at 1 year post-operation was 97.40%(75/77) and 94.81%(73/77) respectively.Chi-square test indicated that the incidence of postoperative infection in children with body weight ≤30 kg and height ≤138 cm was 28.95%(11/38) and 27.50%(11/40) respectively, Both were higher than 7.69%(3/39) and 8.11%(3/37) of children with body weight >30 kg and height>138 cm.The difference between groups was statistically significant ( P=0.016 and 0.028). Conclusions:Low-dose rATG is generally excellent in preventing AR in pediatric KT recipients.And the risk of related AR may be lower.The infection rate of recipients with decent preoperative development is low.

Objective:To compare the effects on DNA strand break induced by ultra-high dose rate (FLASH) electron beam and conventional irradiation, and investigate whether FLASH effect was correlated with a reduction of radiation response.Methods:Aqueous pBR322 plasmid was treated with FLASH (125 Gy/s) and conventional irradiation (0.05 Gy/s) under physioxia (4% O 2) and normoxia (21% O 2). Open circle DNA and linear DNA were detected by agarose gel electrophoresis, and the plasmid DNA damage was quantified with an established mathematical model to calculate the relative biological effect (RBE) of DNA damage. In some experiments, Samwirin A (SW) was applied to scavenge free radicals generated by ionizing radiation. Results:Under physioxia, the yields of DNA strand breakage induced by both FLASH and conventional irradiation had a dose-dependent manner. FLASH irradiation could significantly decrease radiation-induced linear DNA compared with conventional irradiation ( t=5.28, 5.79, 7.01, 7.66, P<0.05). However, when the aqueous plasmid was pretreated with SW, there was no difference of DNA strand breakage between FLASH and conventional irradiation ( P>0.05). Both of the yields of open circle DNA and linear DNA had no difference caused by FLASH and conventional radiotherapy at normoxia, but were significantly higher than those under physioxia. In addition, the yields of linear DNA and open circle DNA induced by FLASH irradiation per Gy were (2.78±0.03) and (1.85±0.17) times higher than those of conventional irradiation, respectively. Conclusions:FLASH irradiation attenuated radiation-induced DNA damage since a low production yield of free radical in comparison with conventional irradiation, and hence the FLASH effect was correlated with oxygen content.

Objective:To evaluate the usability of Gafchromic HD-V2 film for dose dosimetry in the ultra-high dose-rate (UD) electron beam from a modified medical linac, and to investigate the response between the energy and dose-rate dependence to the film.Methods:The HD-V2 film was utilized to measure the average dose-rate of the UD electron beam. The measured result was compared with those by advanced Markus chamber and alanine pellets. And characteristics of the UD electron beam were also measured by HD-V2 film. Energy dependence of HD-V2 film at three beam energies (6 MV X-ray, 9 MeV and 16 MeV electron beam) was investigated by obtaining and comparing the calibration curves based on the clinical linear accelerator in the dose range of 10-300 Gy. The dose-rate dependence of HD-V2 film was also studied by varying the dose rate among 0.03 Gy/s, 0.06 Gy/s and 0.1 Gy/s, and range of 100-200 Gy/s.Results:The measured average maximum dose-rate of 9 MeV UD electron beam at source skin distance (SSD) 100 cm was approximately 121 Gy/s using HD-V2 film, consistent with the results by advanced Markus chamber and alanine pellets. The measured percentage depth dose (PDD) curve parameters of the UD electron beam were similar to the conventional 9 MeV beam. The off-axis dose distribution of the UD electron beam showed the highest central axis, and the dose was gradually decreased with the increase of off-axis distance. The energy dependence of HD-V2 film had no dependency of 6 MV and 9, 16 MeV while measuring the dose in the range from 20 to 300 Gy. The HD-V2 film had no significant dose-rate dependency at the dose rate of 0.03 Gy/s, 0.06 Gy/s and 0.1 Gy/s for the clinical linear accelerator. Likewise, there was also no dose-rate dependence in the range 100-200 Gy/s in the modified machine.Conclusion:HD-V2 film is suitable for measuring ultra-high dose rate electron beam, independent of energy and dose rate.

Objective:To compare the radiation chemistry effects on water molecules after ultra-high dose rate (FLASH) and conventional irradiation.Methods:Both FLASH and conventional irradiation were applied to ultrapure water, with the hydroxyl radical yield in the homogeneous phase detected using electron paramagnetic resonance (EPR) and the hydrogen peroxide (H 2O 2) yield in the diffusion phase analyzed uuxing fluorescence probe. The liposome model was then established to investigate the radiation chemistry effect of FLASH and conventional irradiation in inducing lipid peroxidation. Results:Radiation chemistry reactions were observed in water molecules after irradiation. In the homogeneous phase, the yield of free radicals using FLASH irradiation is similar to those from conventional irradiation ( P>0.05). In the diffusion phase, the amount of H 2O 2 produced by FLASH irradiation was significantly lower than those from conventional irradiation ( t=0.49-12.81, P<0.05). The liposome model confirmed that conventional irradiation could significantly induce lipid peroxidation through the radiation chemistry effect in water molecules as compared with FLASH irradiation ( t=0.31-11.73, P<0.05). Conclusions:The radiation chemistry effect in water molecules after FLASH irradiation was significantly lower than that from conventional irradiation. This could be one of the mechanisms of FLASH effect.

Objective:To propose an automatic planning approach for Eclipse15.6 planning system based on Eclipse scripting application programming interface (ESAPI) and evaluate its clinical application.Methods:20 patients with nasopharyngeal carcinoma and 20 cases of rectal cancer were selected in the clinical planning. The developed automatic planning script SmartPlan and RapidPlan were used for automatic planning and dosimetric parameters were compared with manual planning. The differences were compared between two groups by using Wilcoxon signed rank test. Results:The dosimetric results of automatic and manual plans could meet clinical requirements. There was no significant difference in target coverage in nasopharyngeal carcinoma planning between two groups ( P>0.05), and automatic plans were superior to manual plans in organs at risk sparing ( P<0.05). Except for the homogeneity index of PTV and the maximum dose of bowel in rectal cancer plans, the other dosimetric parameters of the automatic plans were better than those of the manual plans (all P<0.05). Conclusions:Compared with the manual plans, the automatic plans have the same or similar target coverage, similar or better protection of organs at risk, and more convenient implementation. The developed SmartPlan based on ESAPI has clinical feasibility and effectiveness.