PIV Measurement of Fluid Flow Inside a Human Uterus Model for Cryoablation :: essays research papers

PIV MEASUREMENT OF FLUID FLOW INSIDE A HUMAN UTERUS MODEL FOR CRYOABLATION Xiaolong Luo1, Jim S.J. Chen1, Marla Wolfson2, Charles Philips2, Thomas Shaffer2 1Department of Mechanical Engineering, Temple University 2Temple University School of Medicine Abstract – A new technique has been proposed that allows cryoablation to be achieved on the entire inner surface of the endometrium by circulating very cold perfluorochemical (PFC) fluid inside the human uterus. To understand the PFC flow field inside the uterus during cryoablation, a uterus model was constructed; a fluid delivery system including the fluid delivery probe was designed and built to simulate the PFC flow during cryosurgery. With particle image velocimetry (PIV), the fluid flow inside the uterus was investigated at room temperature to display a 2-D whole field velocity contour and vector plot. Keywords: PIV, cryoablation, PFC, endometrium I. INTRODUCTION Menorrhagia is medically defined as excessive bleeding at menses, in duration or amount. A frequent cause of menorrhagia is uterine fibroid growth. Traditionally, hysterectomy is the main treatment for menorrhagia. Several cryosurgery methods such as localized cryoprobes [1] and balloon ablation [2] have been developed as alternatives to hysterectomy to treat the dysfunction of the endometrium. However, these are localized techniques and sometimes there is still proliferation of the endometrium. A new technique is proposed that allows cryoablation to be achieved on the entire inner surface of the endometrium using a PFC fluid [3]. The objective of this project is to develop an efficient treatment method for abnormal uterine bleeding by freezing the endometrium. It has been shown that a temperature of –30 C is required for destroy tissue necrosis [4]. The heat transfer process during cryoablation was investigated experimentally and numerically (1-D) with good agreement [5], in which a uniform fluid temperature boundary condition was used in the 1-D finite difference method to determine the temperature history in the human uteri of eight patients. This assumed that the fluid flow inside the uterus is uniform, repeatable and controllable. During the experiments it was found that the temperature difference at the inlet and outlet of the insertion probe varied from 10Â ºC to 50Â ºC. Inconsistent fluid temperatures may be caused by inadequate circulation of PFC liquid, i.e., recirculation within the uterus. The goal of this study is to understand the flow field inside the uterus cavity during cryoablation so that the desired flow field and uniform temperature field can be obtained, thus proposing an optimal insertion probe design so that minimum PFC liquid and surgery time is used.