Intensity-modulated radiation therapy (IMRT) is a type of external beam radiation therapy used in cancer treatment. In IMRT, the prescribed radiation dose can be administered such that it is maximized on the cancerous tumor while sparing the surrounding healthy tissues. The total dose is divided into fractions across time intervals, called a fractionation scheme. To find the best fractionation scheme and beamlet intensities for total dose, optimization models are used. In this paper, a non-convex mixed-integer nonlinear programming model has been proposed wherein the spatiotemporal changes of the biological properties of the tumor due to tumor cell re-oxygenation, redistribution, and re-population that occur as the treatment progresses have been considered. Also, the dose constraints over both cumulative limits and per-fraction limits have been considered in the model. The output of this model is called the fractionation scheme and beamlet intensities considering biological changes in tumor cells (FBBTs). When the FBBTs are compared with conventional fractionation scheme and beamlet intensities (CFB) which do not include the biological properties of the tumor, it is observed that the FBBTs are more efficacious than the CFBs. To get FBBTs for datasets that resemble realistic tumors, an algorithm based on simulated annealing has been developed and used.

中文翻译：

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改变癌症肿瘤特性的强度调制放射治疗中的分割方案和小束强度的优化

调强放射疗法（IMRT）是用于癌症治疗的一种外部束放射疗法。在IMRT中，可以给予规定的放射剂量，以使其在癌性肿瘤上最大化，同时保留周围的健康组织。在整个时间间隔内将总剂量分为几部分，称为分馏方案。为了找到总剂量的最佳分级方案和小束强度，使用了优化模型。在本文中，已经提出了一种非凸混合整数非线性规划模型，其中随着治疗的进行，由于肿瘤细胞的重新充氧，重新分布和重新分布，导致了肿瘤生物学特性的时空变化。经过考虑的。还，在模型中考虑了累积限制和每个分数限制的剂量限制。考虑到肿瘤细胞（FBBT）的生物学变化，该模型的输出称为分离方案和子束强度。当将FBBT与不包括肿瘤生物学特性的常规分级方案和子束强度（CFB）进行比较时，观察到FBBT比CFB更有效。为了获得类似于真实肿瘤的数据集的FBBT，已经开发并使用了基于模拟退火的算法。当将FBBT与不包括肿瘤生物学特性的常规分级方案和子束强度（CFB）进行比较时，观察到FBBT比CFB更有效。为了获得类似于真实肿瘤的数据集的FBBT，已经开发并使用了基于模拟退火的算法。当将FBBT与不包括肿瘤生物学特性的常规分级方案和子束强度（CFB）进行比较时，观察到FBBT比CFB更有效。为了获得类似于真实肿瘤的数据集的FBBT，已经开发并使用了基于模拟退火的算法。