Investigation On Whole Body Hyperthermia Method Through Directly Heating Blood Vessel Interior

The treatment of advanced cancer has long been the most challenge issue for biomedical and clinical researchers. The whole body hyperthermia (WBH) is being regarded as a rather important way capable of efficiently treating patient with tumors already disseminated throughout the human body. However, there is currently a strong lack of a simple, easy to administrate and minimally invasive heating strategy, which impedes the wide acceptance of WBH in tumor clinics. This thesis is dedicated to present a comprehensive investigation on WBM method from both theoretical and experimental approaches. Progresses achieved were as follows:In this thesis, theoretical evaluations on four typical WBH heating methods with boundary conditions close to reality were performed using finite element method. The heating efficiency for different WBH approaches was comprehensively examined and compared. Approaches for innovating conventional WBM method was suggested.Aiming to tackle the bottle neck problem encountered by current WBH, we established a new conceptual minimally invasive WBH method through directly heating the vessel by micro heating probe and the subsequent heat transport due to blood flow to the whole body, which termed as interventional whole body hyperthermia (IWBH). An experimental system for simulating the WBH was constructed to test the heating capacity of the present methods and effect of heat to the hemo dynamics parameters of flow. Further, theoretical analysis was performed to justify the feasibility of the new therapy. Both theory and experiments indicate the advantage of the vessel heating WHB.Among the factors to determine a successful IWBH, a most challenging task is to in situ monitor the temperatures of the heating needle and the blood running around it. In this study, an indirect method was developed which can accurately measure the temperatures of the needle while performing its heating role. The resistance-temperature relation of the heating needle was calibrated and the temperature of the heating needle was determined during heating in the simulating blood flow. The information acquired in the simulated experiments and theoretical analyses were combined to evaluate the temperature variation of the blood during IWBH.We established a compartmental heat transfer model for human body in order to carry out a comprehensive evaluation on several existing typical WBH methods. The working performance of four heating strategies such as contact-heating-based WBH, radiative-heating-based WBH, extracorporeal circulative-heating-enabled WBH as well as interventional WBH were compared and evaluated. The characteristics of different WBH methods were assessed in detail from the engineering perspective. The power limit requested to induce whole body hyperthermia was clearly given.A novel interventional whole body hyperthermia system, which integrated the tablet PC, PLC, power module, temperature measurement & monitoring system module, the heating needle, as well as the supporting software, was successfully developed. Comprehensive evaluations demonstrated that the new device is highly efficient, easy to administrate and reliable in raising patient's body core temperature to the clinical value.In order to clearly understand the working features of the new system, experiments on large mammal (canine) were performed in vivo during IWBH for the first time. The first hand data about IWBH with animal was obtained. The changes in cardiovascular, respiratory, hemo dynamic indices as well as temperature response of the experimental canine were monitored. All the experiments demonstrate the high performance and safety of the new system.A spatial heating method via using laser to heat the blood vessel interior was presented. A simplified energy equation with spatial heating source was used to model the heat transfer inside the blood vessel interior and a numerical solution was obtained. For the important issue of brain protection during WBM, theoretical evaluation on the cooling efficiency of endovascular cooling as well as surface cooling was also performed. The reason why endovascular cooling is more efficient than surface cooling in lowering body core temperature was interpreted.