NEOPLASTIC TRANSFORMATION BY NEUTRONS AND GAMMA RAYS

中子剂量对体外肿瘤转化的促进作用 据报道，在剂量低于1Gy时(100rad或100cGy时)进行延长 阿贡国家实验室(ANL)Janus反应堆产生的裂变 中子。因为这种效应与当前关于 在单细胞水平上的密集电离辐射的影响，我们 最近试图在类似的情况下重现其中一些观察结果 暴露条件，但没有测量到剂量率效应。本研究旨在 AT：(1)根据剂量-反应关系建立剂量-反应关系 肿瘤效应的裂变中子速率，(2)确定 裂变中子相对于~(60)Coγ射线的相对生物学(RBE) 射线及其对中子剂量和剂量率的依赖关系，(3)测试 作为对剂量的可能解释而提出的主要假说- 报道了Janus中子的速率效应。 我们将使用来自小鼠胚胎细胞的C3H/10T1/2细胞 通过对堆积的焦点在 融合的单层。实验将在37摄氏度的条件下进行 积极发展的文化。在解决前两个问题的实验中 AIMS，细胞将暴露在0.05至0.9Gy裂变中子或 以0.0025~1.2GY/分钟或高剂量率照射伽玛射线， 0.3Gymin(中子)或1Gymin(伽玛射线)。高、低剂量率 将进行固定剂量的中子或伽马射线照射 在同一天。在解决第三个目标的实验中，细胞将 长期暴露在0.075-0.9Gy裂变中子剂量下 超过照射时间T=0.5、1、2或3小时。 裂变中子剂量率将通过比较 长时间或急性暴露(T=45秒至3秒)诱导的转化体 Min)在固定剂量下。 曝光将由TRIGA反应堆和钴设施提供，地址为 马里兰州贝塞斯达的武装部队放射生物学研究所。辐射 AFRRI反应堆产生的剂量平均线能量为71keV/um。

An enhancement of neoplastic transformation in vitro due to neutron dose protraction at doses less 1 Gy (100 rads or 100 cGy) has been reported for the Argonne National Laboratory (ANL) JANUS reactor-produced fission neutrons. Since such an effect contradicts current theories of the effects of densely-ionizing radiation at the single cell level, we recently tried to reproduce some of these observations under similar exposure conditions, but measured no dose-rate effect. This study aims at: (1) establishing the dose-response relationship in terms of dose- rate of fission neutrons for neoplastic effects, (2) determining the relative biological (RBE) of fission neutrons relative to 60Co Gamma- rays, and its dependence on neutron dose and dose rate, (3) testing a leading hypothesis put forward as a possible explanation of the dose- rate effects reported for JANUS neutrons. We will use C3H/10T1/2 cells derived from mouse-embryo cells in which transformation is assessed by scoring piled-up foci on the top of a confluent monolayer. Experiments will be performed at 37 degrees C with actively growing cultures. In the experiments addressing the first two aims, cells will be exposed to 0.05 to 0.9 Gy of fission neutrons or to 0.25 to 1. 2 Gy of Gamma-rays at 0.0025 Gy/min or at high dose rates, 0.3 Gy/min (neutrons) or 1 Gy/min (gammas). High and low dose rate irradiations at fixed doses of neutrons or Gamma-rays will be performed on the same day. In experiments addressing the third aim, cells will be exposed to doses of fission neutrons from 0.075 to 0.9 Gy protracted over irradiation time period T = 0.5, 1,2, or 3 h. The effect of fission neutrons dose rate will be measured by comparing the number of transformants induced by protracted or acute exposures (T = 45 sec to 3 min) at a fixed dose. Exposures will be provided by the TRIGA Reactor and Cobalt Facilities at the Armed Forces Radiobiology Institute, Bethesda, Maryland. Radiation field from the AFRRI reactor has the dose-mean lineal energy 71 keV/um.