超高剂量率照射与常规照射后胶质瘤小鼠血浆代谢物时序性特征对比分析

目的探究超高剂量率照射(FLASH-RT)和常规照射(CONV-RT)对胶质瘤小鼠血浆代谢物的影响。方法胶质瘤模型雄性C57BL/6J小鼠21只, 按随机数表法分成健康对照组(3只)、CONV-RT组(9只)和FLASH-RT组(9只)。CONV-RT组以0.4 Gy/s的剂量率对小鼠头部进行单次24 Gy照射, FLASH-RT组以60 Gy/s的剂量率对小鼠头部进行单次24 Gy照射, 健康对照组以相同条件给予0 Gy假照射。两照射组照射后1、3、7 d分别收集小鼠眼内眦静脉血并分离血浆。健康对照组于假照射后7 d收集小鼠眼内眦静脉血并分离血浆。采取基于液相色谱质谱串联平台的非靶向代谢组学方法检测胶质瘤小鼠血浆代谢物的变化。结果胶质瘤小鼠受不同方式照射后, 血浆中代谢物均发生显著变化。FLASH-RT组和CONV-RT组3个时间点分别与健康对照组相比筛选出12和5种差异代谢物, 照后1 d血浆代谢物差异最大, 照后3和7 d血浆代谢物差异减小。FLASH-RT组筛选出的花生四烯酸与异戊酸也存在于CONV-RT组中, 其余10种差异代谢物仅存在FLASH-RT组, 主要涉及能量代谢和...     

超高剂量率照射和常规照射对小鼠肝脏辐射损伤的转录组学比较研究

目的研究超高剂量率照射(FLASH-RT)和常规照射(CONV-RT)对小鼠肝脏基因表达谱的影响, 为揭示FLASH-RT的潜在作用机制提供理论依据。方法将11只C57BL/6J雄性小鼠, 按照随机数字法分为健康对照组(Ctrl组)、常规照射组(CONV-RT组)和超高剂量率照射组(FLASH-RT组)。CONV-RT组和FLASH-RT组采用相应的方式对小鼠进行腹部照射, 剂量均为12 Gy, 照后将小鼠脱颈处死, 分别收集肝脏组织, 提取总RNA。通过转录组测序技术和生物信息学分析方法, 探究小鼠受照后肝脏组织基因表达谱变化。利用实时定量PCR法对3个基因(Stat1、Irf9和Rela)表达水平进行验证分析。结果 FLASH-RT组与CONV-RT组之间共发现1 762个差异表达基因(DEGs), 其中上调基因660个, 下调基因1 102个;FLASH-RT组与Ctrl组之间共发现1 918个差异表达基因, 其中上调基因728个, 下调基因1 190个;CONV-RT组与Ctrl组之间共发现1 569个差异表达基因, 其中上调基因1 046个, 下调基因523个。基因本体论(G...     

基于FMECA方法的高剂量率后装放疗中人因可靠性研究

目的 研究高剂量率( high dose rate,HDR)后装放疗中的人因可靠性,找出人因风险较高的操作并提出合理可行的控制措施,从而提高HDR后装放疗的临床应用安全.方法 采用现场调研、流程分析和专家评分的方法获得基础数据,并基于失效模式、影响及危害度分析( failure mode,effects and criticality analysis,FMECA)方法 对HDR后装治疗实施中的人因可靠性进行研究.结果 建立了HDR后装放疗的FEMCA人因分析模式,得出实施HDR后装放疗177步骤中相对风险高的有25个,占14.1％.结论 采用FMECA方法研究HDR后装放疗人因失误是可行的.针对较高风险步骤提出了降低人因失误的措施,为提高HDR后装放疗的临床应用安全提供了重要参考依据.     

Radiation dose rate affects the radiosensitization of MCF-7 and HeLa cell lines to X-rays induced by dextran-coated iron oxide nanoparticles

Background and purpose: The aim of radiotherapy is to deliver lethal damage to cancerous tissue while preserving adjacent normal tissues. Radiation absorbed dose of the tumoral cells can increase when high atomic nanoparticles are present in them during irradiation. Also, the dose rate is an important aspect in radiation effects that determines the biological results of a given dose. This in vitro study investigated the dose-rate effect on the induced radiosensitivity by dextran-coated iron oxide in cancer cells.

Materials and methods: HeLa and MCF-7 cells were cultured in vitro and incubated with different concentrations of dextran-coated iron oxide nanoparticles. They were then irradiated with 6?MV photons at dose rates of 43, 185 and 370 cGy/min. The MTT test was used to obtain the cells’ survival after 48?h of irradiations.

Results: Incubating the cells with the nanoparticles at concentrations of 10, 40 and 80?μg/ml showed no significant cytotoxicity effect. Dextran-coated iron oxide nanoparticles showed more radiosensitivity effect by increasing the dose rate and nanoparticles concentration. Radiosensitization enhancement factors of MCF-7 and HeLa cells at a dose-rate of 370 cGy/min and nanoparticles’ concentration of 80?μg/ml were 1.21?±?0.06 and 1.19?±?0.04, respectively.

Conclusion: Increasing the dose rate of 6?MV photons irradiation in MCF-7 and HeLa cells increases the radiosensitization induced by the dextran-coated iron nanoparticles in these cells.