文献类型：期刊文献

英文题名：A new approach to feedback control of radiofrequency ablation systems for large coagulation zones

作者：Zhang, Bing[1,2];Moser, Michael A. J.[3];Zhang, Edwin M.[4];Luo, Yigang[3];Zhang, Wenjun[1,2,5]

机构：[1]East China Univ Sci & Technol, CISR Lab, Shanghai, Peoples R China;[2]Univ Saskatchewan, Div Biomed Engn, Saskatoon, SK, Canada;[3]Univ Saskatchewan, Dept Surg, Saskatoon, SK, Canada;[4]Univ Toronto, Div Vasc & Intervent Radiol, Dept Med Imaging, Toronto, ON, Canada;[5]Univ Saskatchewan, Dept Mech Engn, 57 Campus Dr, Saskatoon, SK S7N 5A9, Canada

年份：2017

卷号：33

期号：4

起止页码：367

外文期刊名：INTERNATIONAL JOURNAL OF HYPERTHERMIA

收录：;WOS:【SCI-EXPANDED(收录号:WOS:000401144500001)】；

基金：This article was supported by the Saskatchewan Health Research Foundation (SHRF) through the "BioNEMS Phase I" grant [grant no. 2539] and the National Natural Science of China [grant no. 51375166]. The first author (Bing Zhang) also received financial support from the China Scholarship Council (CSC) for the study.

语种：英文

外文关键词：Finite element model; large coagulation zone; liver tumour; mono-polar electrode; temperature-controlled radiofrequency ablation

摘要：Aim: The aim of this study was to investigate the feasibility of achieving relatively large coagulation zones (i.e. 3cm in diameter) with radiofrequency ablation (RFA) by using a broad control system.Materials and methods: A broad control system consists of information such as (i) the area of the tumour tissue for feedback control, (ii) the set-point temperature and (iii) the control law. The proposed approach has advanced knowledge in (i) and (ii) in particular. RFA is known to be limited by tissue dehydration that occurs around the electrode, which results in impedance such that no further energy can be delivered to the tissues. We proposed the notion of energy gate, an area on the electrode, which is not covered by the dehydrated tissue and through which energy can still be delivered to the surrounding tissues. Given a specific size of energy gate, both (i) the area of the tissue in which the temperature is monitored and (ii) the set-point temperature were determined. A reliable finite element model or simulator for a commercially available electrode was used and the tissue surrounding the RFA electrode was divided into three areas for a comprehensive study of the issues (i) and (ii). Porcine liver tissue (30 specimens in total) and a custom-made RFA device with a RF power generator (100 W and 46030kHz) and a Covidien cool-tip electrode (17 gauge and 30mm exposure) were used to validate the findings regarding the area of the tissue for feedback control and the set-point temperature.Results: The size of coagulation zone achieved was maximised when the area of tissue surrounding the middle part of the active tip (i.e. Point 7) was used for feedback control and when the set-point temperature was set to 90 (<^>) C (this temperature is determined based on the energy gate through a trial-and-error procedure). At both 80 and 90 (<^>) C, the coagulation zones generated using Area II were significantly larger than that generated using Area I (p = 0.0028 and 0.0003, respectively) and Area III (P = 0.0010 and < 0.0001, respectively). A similar finding regarding the control area and set-point temperature was confirmed by the in-vitro experiment. When compared with Point a (p < 0.0001) and Point c (p < 0.0001), the largest coagulation zone (1066.7 +/- 36.1mm(2)) was achieved by controlling the temperature of the tissue area surrounding the middle part of the active tip (i.e. Point b) at 90(<^>) C.Conclusion: The judicious selection of the control area within the biological tissue for temperature monitoring and the set-point temperature for feedback control is critical in increasing the size of the coagulation zone in the treatment of RFA.