Research On Key Techinology In Body Fat Thickness Measurement With Monte Carlo Simulation

With the progress of society and the improvement of people's living standard,the proportion of obese or overweight people is increasing.Obesity is often accompanied by a variety of chronic diseases,which seriously affects people's health and quality of life.It has become a serious public health problem facing all countries in the world.In clinical,obesity is classified into two categories,subcutaneous fat accumulation and visceral fat accumulation.Subcutaneous fat accumulation type is characterized by the fat distribution mainly in the subcutaneous tissue,and visceral fat accumulation type is characterized by the fat mainly in the abdominal cavity.As an important indicator of body fat,fat thickness can be used to evaluate the degree of obesity,to guide reasonable nutrition and exercise.Although subcutaneous fat thickness can be measured in a variety of ways,near-infrared light measurements are easily accepted by the public because of their simplicity,convenience and convenience.However,when measuring with near-infrared light,the relative position of the detector and the light source,the wavelength of the beam and other factors significantly affect the measurement results.In this paper,the Monte Carlo method is used to simulate the random walk of the photon in the biological tissue.The optimal measurement parameters are determined by analyzing the outgoing photon to improve the accuracy of the measurement of human fat.First,the study of key technology of subcutaneous fat thickness measurement.The subcutaneous fat-muscle tissue model was established,and the walking path of all photons in the tissue was obtained by Monte Carlo simulation method.All the number of photons emitted from the upper surface of the subcutaneous fat layer was counted and the photon emission ratio OPR was customized.At the same time,setting the constraint condition,the maximum depth of Z-axis direction in the range of 0.9 d_sf¹.1d_sff photon were defined as the effective photon,where d_sff said subcutaneous fat layer thickness,and customizing the effective photon ratio EPR.Study the effective photon emission position within the subcutaneous fat thickness d_sf=0.1².0cm to determine the optimal distance between the detector and the light source under different subcutaneous fat thickness.The results show that the photon emission ratio increased with the fat thickness increasing,the effective photon ratio decreased with the fat thickness increasing,and the linear regression equation between the optimal detection distance and the subcutaneous fat thickness was obtained l=0.7597d_sf+0.1133.Second,the study of multi-wavelength subcutaneous fat thickness measurement.The skin-dermis-subcutaneous fat-muscle tissue model was established and simulated using the incident light with wavelength?=400¹000nm.Setting the constraint condition,the maximum depth of Z-axis direction in the range of 0.9 d_ssf¹.1d_ssfsf photon were defined as the effective photon,where d_ssfsf said?skin thickness+subcutaneous fat layer thickness?,and customizing the effective photon ratio EPR.At the same time,analysis the optimal detection distance between the detector and the light source under different wavelengths.The results show that the OPR achieves the maximum value in the wavelength?=800⁹00nm,and the effective photon ratio increases with the wavelength increasing.The wavelength has no effect on the optimal detection distance,and the optimal detection wavelength is 1000nm.Finally,the study of key technology of visceral fat thickness measurement.Visceral fat is mainly distributed in the human abdomen.First of all,establish abdominal subcutaneous fat-muscle tissue-visceral fat-intestinal model.Then setting the constraint condition,the maximum depth of Z-axis direction in the range of0.9 d_smv¹.1d_smvmv photon were defined as the effective photon,where d_smvmv said?subcutaneous fat layer thickness+muscle layer thickness+visceral fat thickness?,and customizing the effective photon ratio EPR.The effective photon ratio decreased with the fat thickness increasing.Study the effective photon emission position within the visceral fat thickness d_vf=0.5⁶.0cm,to determine the optimal distance between the detector and the light source under different visceral fat thickness,and the mathematical model between the optimal detection distance and visceral fat thickness was established.A method for measuring visceral fat content in human body based on body size and body subcutaneous fat thickness was proposed.This study provides a solution to the problem of determining the wavelength of the incident light,the position of the light source and the detector,and provides a theoretical basis for the development of measuring device and carrying out human experiment.