On-line Temperature Detection Technology In Microwave Hyperthermia Machine

Tumor hyperthermia is a treatment that heats tumor cells to a temperature of medical significance for apoptosis without affecting normal cells.Microwave hyperthermia machine is the core instrument to complete this process by microwave heating.Hyperthermia requires accurate and real-time temperature detection.In the microwave field,because the traditional temperature measuring devices are made of metal materials,it is impossible to measure the temperature accurately due to electromagnetic interference and other problems.In this thesis,a temperature detection system based on the temperature measurement technology of fluorescent fiber is designed,which can effectively avoid electromagnetic interference,and has small size,strong corrosion resistance and high resolution.It has good application effect in temperature measurement of thermotherapy machine.Firstly,the principle of temperature measurement of fluorescent fiber was analyzed through literature review.The temperature measuring system is designed based on the theory of fluorescence lifetime temperature measurement and fluorescent fiber optic temperature sensor is used as the core device of temperature measurement.On this basis,through the in-depth study of data processing methods to meet the needs of hyperthermia.Secondly,building a temperature detection system based on excitation unit,photoelectric conversion unit,amplifying circuit unit and data acquisition unit.Through comparative analysis,red powder is selected as temperature sensitive material,which has good temperature sensitive characteristics.Ultraviolet laser diode is selected as the excitation light source to match with the fluorescent material.The weak signal amplifying link is analyzed and the amplifying circuit is designed.The data acquisition module is selected to be completed by USB2851 data acquisition card.MATLAB was used to write the program of the least squares fitting method,FFT fitting method and integral area ratio method for the single exponential model.The advantages and disadvantages of the three algorithms are compared by theoretical derivation.Considering the complexity of the actual situation,the l-m algorithm and prony algorithm are applied to the data processing of fluorescence temperature measurement.The theoretical feasibility is analyzed and the program is programmed.The sensitivity and accuracy of temperature measurement are improved by simulation.Then the five programs are nested into the Labview program to design the upper computer display interface.Finally,the hardware circuit of each part is adjusted.The probe performance was debugged and its sensitivity was analyzed.Then the temperature calibration experiment is carried out to obtain the temperature measurement formula.At last finish the whole machine experiment.It is shown that the temperature measuring system can work stably.The precision is within 0.2? and the system achieve the effect of real-time temperature monitoring.