Measurement Technology Of Blood Flow Based On Frequency Domain Optical Coherence Tomography

In the early process of biological heart development,cardiovascular blood flow to their internal development is very important.Abnormal blood flow may cause congenital heart defects and other diseases,a serious impact on people's health or even death.The force applied to the biomechanics of blood flow could affect endothelial cell gene expression,changes in gene expression in heart development which affects the structure and function,leading to further changes biomechanical factors.During early embryonic development,blood flow and shear are two key factors,but there is no direct tool can accurately direct measurement of the specific parameters in order to study the vascular shear stress,we need to select the appropriate method be measurement.Optical coherence tomography is a noninvasive blood testing technology,which can achieve noninvasive detection of heart disease at an early stage.It is of great significance for early diagnosis of heart disease.Optical coherence tomography(OCT)is an imaging method based on the theory of low-coherence interferometry,which can be used to obtain the image in different depth positions of highly scattering medium,such as biological tissue.OCT technology with no radiation,non-invasive,high-resolution and high detection sensitivity,etc.,as a reliable medical diagnostic tool,has become an important means of biomedical imaging.According to different imaging theory,OCT can be divided into two categories:time domain optical coherence tomography(TD-OCT)and frequency domain optical coherence tomography(FD-OCT).When imaging the traditional time-domain OCT technology requires scanning the reference arm,which correspond to different depths of the sample.The reference arm scanning is slow,limiting the signal acquisition rate of the time-domain OCT.In order to improve acquisition speed,frequency domain OCT technology emerges.Compared with the time-domain OCT technology,it has a great advantage in acquisition speed,signal to noise ratio and sensitivity.As a branch of the frequency domain OCT technology,swept source OCT technique using a wavelength tunable laser,the imaging speed and depth have been further improved.This paper introduces the research meaning of measurement technology of blood flow and development background of OCT,Through the study of the basic principles of OCT,we designed and built quickly swept sourbasic configuration of the system.Starting from optical interferometer,a major ce OCT systems,introducing the component of the system,including the interferometer part,scanning systems and signal acquisition system is analyzed and designed in detail.Considering the various factors to select source,we select the appropriate swept laser source.Interference spectrum signals are processed through shaping spectral,reducing the DC term and dispersion compensation.The basic theories and measure methods of wall shear stress is introduced first.Then we measure the chick embryonic heart blood flow velocity and wall shear stress.There will have the phenomenon of phase wrapping when measuring wall shear stress,leading to erroneous measurement results.And a new approach for the emergence of the phenomenon of the phase wrapping is proposed.