Cellular response to modulated radiation fields
Cellular response to modulated radiation fields
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DOI：
10.1088/0031-9155/52/18/001
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发表时间：
2007-09-21
影响因子：
3.5
通讯作者：
Jackson, M.
中科院分区：
文献类型：
--
作者：
Mackonis, E. Claridge;Suchowerska, N.;Jackson, M.
对暴露于由调强放射治疗（IMRT）产生的空间调制射束后的细胞存活情况进行了研究。利用恶性黑色素瘤细胞（MM576）进行了体外实验，这些细胞暴露于治疗用兆伏级光子射束。我们比较了调制射野中的细胞存活情况与均匀对照射野中的细胞存活情况。使用了射野的三种不同空间调制方式：一种是对照“均匀”射野，其中烧瓶中的所有细胞均均匀受照；一种是“四分之一”射野，其中烧瓶一端25%的细胞受照；还有一种是“条纹”射野，其中25%的细胞以三条平行条纹的形式受照。通过克隆形成试验测定的调制射野中受屏蔽区域和未受屏蔽区域的细胞存活情况，与均匀射野中的细胞存活情况进行了比较。我们区分了细胞存活受邻近细胞命运影响的三种方式。其中第一种（I型效应）是先前报道的经典旁观者效应，即当与受照射细胞进行通讯时细胞存活率降低。我们发现了两种新的旁观者效应类型。II型效应是当附近细胞接受致死剂量时观察到的细胞存活率增加。III型效应是当附近细胞接受低剂量时，接受高剂量辐射的细胞存活率增加。这些对旁观者效应的观察结果强调了改进放射生物学模型的必要性，这些模型应包括通讯效应并考虑调制剂量分布的影响。
Cell survival following exposure to spatially modulated beams, as created by intensity-modulated radiotherapy (IMRT), is investigated. In vitro experiments were performed using malignant melanoma cells (MM576) exposed to a therapeutic megavoltage photon beam. We compared cell survival in modulated fields with cell survival in uniform control fields. Three different spatial modulations of the field were used: a control 'uniform' field in which all cells in a flask were uniformly exposed; a 'quarter' field in which 25% of cells at one end of the flask were exposed and a 'striped' field in which 25% of cells were exposed in three parallel stripes. The cell survival in both the shielded and unshielded regions of the modulated fields, as determined by a clonogenic assay, were compared to the cell survival in the uniform field. We have distinguished three ways in which cell survival is influenced by the fate of neighbouring cells. The first of these (type I effect) is the previously reported classical Bystander effect, where cell survival is reduced when communicating with irradiated cells. We find two new types of Bystander effect. The type II effect is an observed increase in cell survival when nearby cells receive a lethal dose. The type III effect is an increase in the survival of cells receiving a high dose of radiation, when nearby cells receive a low dose. These observations of the Bystander effects emphasize the need for improved radiobiological models, which include communicated effects and account for the effects of modulated dose distribution.