中文摘要：

采用放射生物学方法,研究了放射性核素靶向治疗中细胞群大小对EUD和TCP的影响,并以宏观与微观结合的方法,分析了肿瘤中心活性缺失情况下所对应的特征。研究表明,在活性均匀分布的情况下,EUD随细胞群（肿瘤）增大而增大。若考虑细胞间液活性的影响,EUD还会增加约47%。当肿瘤内部活性缺失时,若以TCP=0.90作为衡量标准,周围细胞的211Atα粒子的交叉效应,对于细胞核源最大可弥补边长为4层细胞的肿瘤活性中空,而其它源可弥补边长为6层细胞的肿瘤活性中空。临床治疗中,医师按照模拟结果参考给药时,应参考细胞面源的指导药量,以免由于剂量不足而造成的肿瘤控制的局部失败。TCP可以清晰地表现剂量足与不足时的差异,但是当剂量充足或过量时效果就要差些,因此它比较适合于治疗计划的制定。EUD常用于比较不同活性分布的差异,但用户在使用时一定要注意保持前后模型形状、体积的一致性。

英文摘要：

The influence of cell cluster dimension on EUD and TCP for targeted radionuclide therapy was studied using the radiobiological method.The radiobiological features of tumor with activity-lack in core were evaluated and analyzed by associating EUD,TCP and SF.The results show that EUD will increase with the increase of tumor dimension under the activity homogeneous distribution.If the extra-cellular activity was taken into consideration,the EUD will increase 47%.Under the activity-lack in tumor center and the requirement of TCP=0.90,the α cross-fire influence of 211↑At could make up the maximum（48 μm）3 activity-lack for Nucleus source,but（72 μm）3 for Cytoplasm,Cell Surface,Cell and Voxel sources.In clinic,the physician could prefer the suggested dose of Cell Surface source in case of the future of local tumor control for under-dose.Generally TCP could well exhibit the effect difference between under-dose and due-dose,but not between due-dose and over-dose,which makes TCP more suitable for the therapy plan choice.EUD could well exhibit the difference between different models and activity distributions,which makes it more suitable for the research work.When the user uses EUD to study the influence of activity inhomogeneous distribution,he should keep the consistency of the configuration and volume of the former and the latter models.