Three-dimensional Far-infrared Thermal Imaging And Its Temperatue Measurements For Medical Applications

Any of the various kinds of malignant neoplasms is a killer of humanbeings. Research on the novel medical imaging approaches for tumourimmunization, detection and therapy has become a hot topic in the biomedicalengineering community. The far-infrared (FIR) thermography, characterized bynoninvasive, real-time, dynamic functional imaging, can assist doctors indiagnosing different diseases. However,2D thermography can only providelimited information concerning the skin surface temperature. Therefore, it isassumed that the3D partial-and whole-body thermography can be realizedthrough combining3D surface models with2D thermal images. Furthermore,the3D thermography can obtain information of the inner abnormal heat sourcewhich includes the depth, shape and temperature. In spite of the obvioussignificance of these techniques, there remain some questions unanswered suchas the high-speed, high-resolution, accurate body surface acquisition, the3DFIR thermography and the non-invasive inner temperature measurements. To answer these questions, we carried out the following technicalprocedures to achieve the goals. Step1: The high-resolution3D measurementshave been developed for surface acquisition of the partial-and whole-body. Step2: The high-resolution3D FIR imaging technique has also been developed for3D thermography of the partial-and whole-body. Step3: The non-invasive innertemperature measurements based on3D FIR thermography have been proposed.To better understand the technical procedure, the following six problems havebeen addressed.1. High-resolution3D body imaging technique based on fringe projectionThe characteristics of the3D imaging system based on trigonometry havebeen analyzed. The innovation of the vertical-shifted pattern projection methodrealizes high-resolution3D imaging for parts of the body at a high speed. Then,optimal layout of fringe projection for3D measurements has been developed toavoid ambiguity. Therefore, the effective view of the3D measurement systemhas been modeled for optimal design.2.3D whole-body scanner based on fringe projection and synchronous opticalpath rotationThe novel wide angle-of-view3D imaging system based on rotation ofoptical paths and vertical-shifted fringe projection has been developed. Theoptical paths of the projector and the receiver can be rotated synchronously when the scanning mirror sways under stepping motor control. The wideangle-of-view3D imaging system achieves3D dada acquisition of whole-bodysurface. Then, we have achieved the modeling mathematical analyses of blurringphenomena in the image sequence by scanning the whole-body at the maximumspeed.3. Calibration of3D imaging systemsA novel calibration board based on the plane display screen has beeninvented. Then, the system calibration has been performed, which includeslocation and shape calibration of structured light slices. Meanwhile, we haveproposed two methods of structured light calibration through multi-point fittingof the light slices: one is based on the known location of the target plane and theother is the stereo vision idea. Afterwards, the calibration procedure of thewhole-body imaging system has also been developed. According to ourexperimental results, the proposed method improves3D measurement accuracysignificantly in comparison with previous methods.4. A high-resolution3D FIR thermal and true-color imaging systemThe paper has developed an imaging-sensor integrated system that cansynchronously acquire high-resolution3D FIR thermal and true-color images ofthe body surface. The proposed system integrates one FIR camera and one colorcamera with a3D structured light binocular profilometer. Afterwards, the precise 3D surface was fused with undistorted thermal and color images. Thus, over40,0003D thermal and over150,0003D color points can be obtained afterreconstruction. For the further application, the ROI (Region of Interest) in the2D temperature or color image can be checked and located on the correspondingposition on the other image through coordinate system transformation.5. A wide angle-of-view thermal imaging utilizing optical path rotationA wide angle-of-view FIR system based on the method of optical pathrotation has also been invented. The system has integrated one FIR camera andone rotating gold-sprayed mirror controlled by one stepping motor. The FIRcamera takes the image sequence from the rotating mirror in the real-timecapture mode. Meanwhile, the speed of pixel movement on the FIR imagingplane has been analyzed to obtain the fastest data acquisition without blurring.Besides, the view range of the proposed system is considered. Then, theprototype has been designed according to the simulation results. The experimentdata has verified the theory of motion blur and3D imaging. This thermalimaging technique can be integrated with3D whole-body scanner.6. Non-invasion inner temperature measurements based on3D FIRthermographyThe principles of the heat transfer have been introduced. A series ofexperiments have validated that the temperature field of the point heated source is distributed in the form of isothermal spherical surface. The isothermal curvecan be acquired by the3D thermography. Then, the variation of the isothermalcurves with different parameters of the heat sources involving the depth, shape,and temperature have also been investigated. Afterwards, according to theFourier’s law, non-invasive temperature measurements based on3D FIRthermography for the inner heated source can be achieved in the invariable heatfield. And the performance of this method has been experimentally evaluated.These research results can be widely applied to clinical medical engineeringand industrial automation.