Objective:To observe the tumor control and the degree of radiation-induced lung injury (RILI) between FLASH irradiation and conventional dose rate (CONV) irradiation, and compare the changes in plasma proteomic profiles of mice following whole-lung FLASH and CONV irradiation using proteomics method.Methods:A mouse model with metastatic lung cancer was established. After whole-lung irradiation, changes in normal lung capacity were monitored using CT scans. Then, a RILI model was constructed to examine pathological alterations in lung tissues following whole-lung CONV and FLASH irradiation. Plasma samples were collected from mice receiving whole-lung CONV irradiation ( n = 5) and whole-lung FLASH irradiation ( n = 5), followed by comparison with samples from the control group of healthy mice (also referred to as the healthy control group). These plasma samples were analyzed using isobaric tags for relative and absolute quantification (iTRAQ)-based proteomics, followed by the screening and identification of differentially expressed proteins using high-throughput bioinformatics. Moreover, protein-protein interaction (PPI) network analysis was conducted to identify hub genes using the STRING database and Cytoscape software. Results:Whole-lung FLASH and CONV irradiation produced consistent tumor control, with the former significantly reducing RILI compared to the latter. A total of 609 proteins were identified through proteomic analysis. Among them, 89 differentially expressed proteins were detected in the whole-lung FLASH group. Gene Ontology (GO) enrichment analysis indicated that up-regulated genes were primarily associated with stress and inflammatory responses, whereas down-regulated genes were related to ATP metabolism and angiogenesis regulation. Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis revealed that up-regulated genes were predominantly enriched in unfolded protein response pathways, while down-regulated genes were mainly involved in metabolic pathways and oxidative phosphorylation. Integrated PPI analysis and subsequent validation via reverse transcription-polymerase chain reaction (RT-PCR) revealed four key genes.Conclusions:Compared to the whole-lung CONV irradiation, whole-lung FLASH irradiation reduces the RILI of normal lung tissues while maintaining equivalent tumor control in metastatic lung cancer. Proteomic analysis of differentially expressed proteins in plasma after whole-lung FLASH and CONV irradiation provides valuable insights into the molecular mechanisms underlying the FLASH effect.

Objective:To conduct a comparative analysis of the oxygen depletion and oxygen effect of FLASH irradiation and conventional irradiation by direct measurement of oxygen content.Methods:The oxygen content in different tissues and organs of mice was measured using a phosphorescent probe. A subcutaneous xenograft tumor model in mice was established, to receive electron-beam irradiation at different doses and dose rates. The oxygen depletion of tumor and normal tissue was analyzed, and tumor control was evaluated. The oxygen depletion of conventional irradiation and FLASH irradiation was further analyzed using an in vitro model. The survival fraction (SF) of normal cells after conventional irradiation and FLASH irradiation was calculated using colony formation assay under different partial pressures of oxygen, and the data were fitted to the oxygen enhancement ratio (OER) curve. Results:The mean oxygen content of subcutaneous xenograft tumor in mice was 1.28%, suggesting hypoxia. The mean oxygen content of normal tissue ranged from 3.51% to 6.53%, suggesting physioxia. In animal experiments, oxygen depletion was not observed during conventional irradiation. High-dose-rate (20 Gy/s) and ultra-high-dose-rate (FLASH, 40 Gy/s) irradiation produced oxygen depletion. During FLASH irradiation, with the increase of oxygen content, the oxygen depletion was 0.1-0.2 mm Hg/Gy for tumor tissue and 0.19-0.21 mm Hg/Gy for skin tissue, which tended to stabilize. FLASH irradiation maintained equivalent tumor control compared to conventional irradiation. The tumoricidal effect was significantly enhanced with the increase of oxygen content in the tissue ( t=3.46, P<0.01). In in vitro experiments, the mean oxygen depletion rate was about 0.16 mm Hg/Gy for conventional irradiation and 0.16-0.18 mm Hg/Gy for FLASH irradiation, which did not change significantly with the increase of oxygen content. FLASH irradiation was associated with an oxygen effect. When the partial pressure of oxygen decreased from physioxia to hypoxia, the OER value significantly reduced. Conclusions:Normal tissues and organs are in physioxia, which exhibits a lower oxygen content than that in the air. FLASH irradiation can consume a proportion of oxygen, producing an oxygen effect. When oxygen content decreases, the oxygen depletion rate slows down after FLASH irradiation.

Objective:To observe the tumor control and the degree of radiation-induced lung injury (RILI) between FLASH irradiation and conventional dose rate (CONV) irradiation, and compare the changes in plasma proteomic profiles of mice following whole-lung FLASH and CONV irradiation using proteomics method.Methods:A mouse model with metastatic lung cancer was established. After whole-lung irradiation, changes in normal lung capacity were monitored using CT scans. Then, a RILI model was constructed to examine pathological alterations in lung tissues following whole-lung CONV and FLASH irradiation. Plasma samples were collected from mice receiving whole-lung CONV irradiation ( n = 5) and whole-lung FLASH irradiation ( n = 5), followed by comparison with samples from the control group of healthy mice (also referred to as the healthy control group). These plasma samples were analyzed using isobaric tags for relative and absolute quantification (iTRAQ)-based proteomics, followed by the screening and identification of differentially expressed proteins using high-throughput bioinformatics. Moreover, protein-protein interaction (PPI) network analysis was conducted to identify hub genes using the STRING database and Cytoscape software. Results:Whole-lung FLASH and CONV irradiation produced consistent tumor control, with the former significantly reducing RILI compared to the latter. A total of 609 proteins were identified through proteomic analysis. Among them, 89 differentially expressed proteins were detected in the whole-lung FLASH group. Gene Ontology (GO) enrichment analysis indicated that up-regulated genes were primarily associated with stress and inflammatory responses, whereas down-regulated genes were related to ATP metabolism and angiogenesis regulation. Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis revealed that up-regulated genes were predominantly enriched in unfolded protein response pathways, while down-regulated genes were mainly involved in metabolic pathways and oxidative phosphorylation. Integrated PPI analysis and subsequent validation via reverse transcription-polymerase chain reaction (RT-PCR) revealed four key genes.Conclusions:Compared to the whole-lung CONV irradiation, whole-lung FLASH irradiation reduces the RILI of normal lung tissues while maintaining equivalent tumor control in metastatic lung cancer. Proteomic analysis of differentially expressed proteins in plasma after whole-lung FLASH and CONV irradiation provides valuable insights into the molecular mechanisms underlying the FLASH effect.

Objective:To conduct a comparative analysis of the oxygen depletion and oxygen effect of FLASH irradiation and conventional irradiation by direct measurement of oxygen content.Methods:The oxygen content in different tissues and organs of mice was measured using a phosphorescent probe. A subcutaneous xenograft tumor model in mice was established, to receive electron-beam irradiation at different doses and dose rates. The oxygen depletion of tumor and normal tissue was analyzed, and tumor control was evaluated. The oxygen depletion of conventional irradiation and FLASH irradiation was further analyzed using an in vitro model. The survival fraction (SF) of normal cells after conventional irradiation and FLASH irradiation was calculated using colony formation assay under different partial pressures of oxygen, and the data were fitted to the oxygen enhancement ratio (OER) curve. Results:The mean oxygen content of subcutaneous xenograft tumor in mice was 1.28%, suggesting hypoxia. The mean oxygen content of normal tissue ranged from 3.51% to 6.53%, suggesting physioxia. In animal experiments, oxygen depletion was not observed during conventional irradiation. High-dose-rate (20 Gy/s) and ultra-high-dose-rate (FLASH, 40 Gy/s) irradiation produced oxygen depletion. During FLASH irradiation, with the increase of oxygen content, the oxygen depletion was 0.1-0.2 mm Hg/Gy for tumor tissue and 0.19-0.21 mm Hg/Gy for skin tissue, which tended to stabilize. FLASH irradiation maintained equivalent tumor control compared to conventional irradiation. The tumoricidal effect was significantly enhanced with the increase of oxygen content in the tissue ( t=3.46, P<0.01). In in vitro experiments, the mean oxygen depletion rate was about 0.16 mm Hg/Gy for conventional irradiation and 0.16-0.18 mm Hg/Gy for FLASH irradiation, which did not change significantly with the increase of oxygen content. FLASH irradiation was associated with an oxygen effect. When the partial pressure of oxygen decreased from physioxia to hypoxia, the OER value significantly reduced. Conclusions:Normal tissues and organs are in physioxia, which exhibits a lower oxygen content than that in the air. FLASH irradiation can consume a proportion of oxygen, producing an oxygen effect. When oxygen content decreases, the oxygen depletion rate slows down after FLASH irradiation.

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 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 investigate the effect of respiratory motion on inadvertent irradiation dose (ⅡD)to the microscopic disease(MD)and expanding margin of target volume in stereotactic body radiotherapy for lung cancer. Methods Based on the pattern of respiration-induced tumor motion during lung radiotherapy, a probability model of MD entry into or exit from internal target volume(ITV)was established and the theoretical dose to MD was calculated according to the static dose distribution by four-dimensional computed tomography. The experimental dose to MD during respiratory motion was measured using a respiration simulation phantom and optically stimulated luminescence(OSL)and then compared with the theoretical value for model validation.Results For the target volume in periodic motion,the deviation of the theoretical dose to MD from the experimental value measured by OSL was less than 5%. A 10-mm margin around ITV received a biological dose higher than 80 Gy. Conclusions The dose model established in this study can accurately predict the irradiation dose to MD in the target volume in periodic motion. Respiratory motion increases ⅡD to MD and there is no need to expand clinical target volume.

Objective To investigate the efficacy and toxicity of stereotactic ablative radiotherapy for stage Ⅰ peripheral non-small cell lung cancers.Methods Thirty six patients of stage Ⅰ peripheral non-small cell lung cancers were treated with stereotactic ablative radiotherapy.The prescription dose was 12 Gy per fraction ×4 fraction in one to two weeks.The 100％ planning target volume (PTV) was covered by the isodose curve of 95％ prescription dose.Organs at risk and their respective tolerance doses used during treatment planning were developed from the research scheme of the Radiation Therapy Oncology Group 0236.Before the radiation delivery,all patients were scanned by the fan beam CT or the cone beam CT for image guidance and registration.The follow-up for the patients was given to observe the toxicity and efficacy of stereotactic ablative radiotherapy (SABR).Results The median follow-up time was 18.7 months (range of 4 to 36 months).After treatment,the overall response rate was 88.9％,with complete response (CR) 17 cases(47.2％),partial response (PR) 15 cases(41.7％),and stable disease (SD) 4 cases(11.1％).The estimated overall survival rate at 1 and 3 years was 92.3％ (95％ confidence interval [CI],86.3％ ～97.1％) and 85.3％ (95％ CI,80.5％ ～90.6％).The estimated local control rate at 3 years was 90.2％ (95％ CI,85.7％ ～94.8％).There was no gradeⅢ or above toxicity related to treatment.Conclusions The stereotactic ablative radiotherapy attains good local control and survival efficacy for the stage Ⅰ peripheral non-small lung cancer patients.It is well tolerated owing to low toxicity.

OBJECTIVETo analyze the factors that affect oculomotor nerve function recovery time in patients receiving balloon embolization for oculomotor nerve palsy caused by traumatic carotid cavernous sinus fistula.

METHODSThe clinical data were collected from 87 patients undergoing balloon embolization for oculomotor nerve palsy due to traumatic carotid cavernous sinus fistula from July 2005 to July 2013 and the factors affecting oculomotor nerve function recovery time was analyzed using a self-made questionnaire.

RESULTS AND CONLUSIONOculomotor nerve function recovery time ranged from 1 to 6 months (mean 33.32 ± 16.76 days) in these patients. Age, severity of preoperative oculomotor nerve paralysis, injury-to-treatment time, and number of balloon used were positively correlated with nerve function recovery time, and the flow volume of traumatic carotid cavernous sinus fistula was negatively correlated with the recovery time.