Chua K J, Chou S K, Ho J C
Department of Mechanical Engineering, National University of Singapore, 9 Engineering Drive 1, 117576 Singapore.
J Biomech. 2007;40(1):100-16. doi: 10.1016/j.jbiomech.2005.11.005. Epub 2005 Dec 20.
The aim of cryosurgery is to kill cells within a closely defined region maintained at a predetermined low temperature. To effectively kill cells, it is important to be able to predict and control the cooling rate over some critical range of temperatures and freezing states in order to regulate the spatial extent of injury during any freeze-thaw protocol. The objective of manipulating the freezing parameters is to maximize the destruction of cancer cells within a defined spatial domain while minimizing cryoinjury to the surrounding healthy tissue. An analytical model has been developed to study the rate of cell destruction within a liver tumor undergoing a freeze-thaw cryosurgical process. Temperature transients in the tumor undergoing cryosurgery have been quantitatively investigated. The simulation is based on solving the transient bioheat equation using the finite volume scheme for a single or multiple-probe geometry. Simulated results show good agreement with experimental data obtained from in vivo clinical study. The calibrated model has been employed to study the effects of different freezing rates, freeze-thaw cycle(s), and multi-probe freezing on cell damage in a liver tumor. The effectiveness of each treatment protocol is estimated by generating the cell survival-volume signature and comparing the percentage of cell damaged within the ice-ball. Results from the model show that employing freeze-thaw cycles has the potential to enhance cell destruction within the cancerous tissue. Results from this study provide the basis for designing an optimized cryosurgical protocol which incorporates thermal effects and the extent of cell destruction within tumors.
冷冻手术的目的是杀死处于预定低温的紧密限定区域内的细胞。为了有效杀死细胞，能够在某些关键温度范围和冷冻状态下预测和控制冷却速率，以便在任何冻融方案中调节损伤的空间范围，这一点很重要。操纵冷冻参数的目的是在限定的空间域内最大化癌细胞的破坏，同时最小化对周围健康组织的冷冻损伤。已经开发了一个分析模型来研究在进行冻融冷冻手术过程的肝肿瘤内细胞破坏的速率。对进行冷冻手术的肿瘤中的温度瞬变进行了定量研究。该模拟基于使用有限体积格式求解单探针或多探针几何形状的瞬态生物热方程。模拟结果与从体内临床研究获得的实验数据显示出良好的一致性。已使用校准模型来研究不同冷冻速率、冻融循环次数和多探针冷冻对肝肿瘤细胞损伤的影响。通过生成细胞存活体积特征并比较冰球内受损细胞的百分比来评估每种治疗方案的有效性。模型结果表明，采用冻融循环有可能增强癌组织内的细胞破坏。本研究结果为设计一种优化的冷冻手术方案提供了基础，该方案纳入了热效应和肿瘤内细胞破坏的程度。
