聚焦超声消融肝癌时大血管位置对热场分布的影响

采用有限元方法研究了聚焦超声消融肝脏肿瘤时，大血管存在于肿瘤附近不同位置对温度分布以及热剂量分布的影响．建立基于大血管对流效应的生物传热模型，基于不同的加热方案进行3-D温度瞬态仿真．仿真针对四种情况进行计算：模型中无血管，血管分别距离肿瘤1mm、2mm、3mm．仿真结果表明使用聚焦超声进行快速加热可以使能量集中在目标治疗区域．但是当肿瘤组织的近距离内（1mm）存在大血管且加热时间较长时（〉2s），肿瘤组织靠近血管的边界部分仍然会受到大血管冷却效应的影响，这种影响会导致肿瘤治疗不彻底．当肿瘤距离大血管3ram以上时，大血管在聚焦超声治疗中的冷却效应不再明显．

The Impact of Large Blood Vessel Location on Thermal Dose Distribution during Focused Ultrasound Surgery for Hepatic Tumor Ablation

The effects of presence of a large blood vessel and its distance to a tumor on lesion sizes during focused ultrasound surgery were studied.A finite element method(FEM) was used to obtain the temperature distribution for bioheat transfer equation(BHTE) with the consideration of the large blood vessels convection effect.In the 3-D FEM simulation,a 4-mm diameter,10-mm height cylindrical tumor tissue was heated using different heating schemes.The distance between the blood vessel and the tumor tissue varied from 1mm to 3mm.The model without blood vessel was also studied.Simulation results quantitatively show that the domain of thermal lesion can effectively cover the desired therapeutic region with short ultrasound exposure times(2s),however, if the large blood vessel is near the tumor with the distance of 1mm,the blood flow may play an important role in the thermal dose distribution on tumor boundary.Underdosed areas might be present from which the tumor can regenerate.When the distance of the longer blood vessel from the tumor is longer than 3mm,the cooling effect of large blood vessels is not significant in focused ultrasound surgery.