Research On Wireless Capsule Endoscopy System

At present, digestive diseases are important factors to harm people’shealth. Endoscopy is effective method for diagnosing digestive diseases.However the existing endoscopy technologies are based on the traditionalmechanical-type gastrointestinal push-type endoscope. Under this manner ofEndoscopic diagnosis, there are two-thirds of the small intestine can not bereached, and the whole digestive tract testing is unable to be completelychecking. At the same time, putting the catheter into human’s body will notonly brings pain and irritation to the patients, but also injures the stomachwall and causes cross-infection.With the rapid development of semiconductor technology, wirelesscommunication technology, integrated circuit technology and LEDillumination technology, it becomes possible that wireless capsule endoscope(WCE) will replace the traditional push-type endoscopy. Wireless capsuleendoscope can overcome the shortcomings of traditional endoscope, and it isswallowable. After swallowed by a patient, the capsule endoscope is propelled by peristalsis of gastrointestinal while it collects images of thegastrointestinal tract and transmits the image data out of human’s body. Sothat doctors can easily detect the whole digestive tract without causing painor invasiveness on patientsThis thesis relies on the National Natural Science Foundation(No.60875061), National High Technology Research&DevelopmentProgram (863Program) of China (No.2006AA04Z368,2007AA04Z234,2008AA04Z201) and Key Project of Shanghai Science and TechnologyCommission (No.05111021,09DZ1907400) and is dedicated to make researchon novel WCE system which can be used for clinical diagnosis. Starting fromthe systematic development, this thesis has studied and realized two types ofWCE system:1. Digital wireless capsule endoscope based on the JPEG image formathas been explored, and the capsule endoscopy system is realized. This systemconsists of image capsule endoscope, vitro receiver and image workstation inhost computer. Most of the existing capsule endoscopes transmit the image inBayer format out of the body through analog wireless communication.Analog wireless communication has many advantages such as widefrequency bandwidth, faster speed, but the analog signals are susceptible tointerference and its circuit is complex, which seriously affects image’s quality and miniaturization of capsules. JPEG format based digital wireless capsuleendoscopy obtains images of gastrointestinal tract and converts the imagesinto digital signals through ADC(Analog-to-Digital Converter), andcompresses the images into JPEG format. Then the JPEG image is to betransmitted out of human’s body through the digital wireless communicationmodule, which saves the power caused by D/A conversion and enhances thesignal noise immunity for signal. Vitro receiver receives the image data andsends them to the image workstation of host computer. The applicationinstalled in host computer is utilized to display and process the image.Compare to the analog one, digital capsule endoscope has goodanti-interference with clear image and is conducive to clinical diagnosis.2. Wireless power transmission and wireless transmission of NTSCvideo data have been researched, and the NTSC capsule endoscopy systembased on wireless power has been realized. Current battery-powered capsuleendoscope with frame rate of2f/s can maintain its working in human’s bodyaround4to8hours while clinicians can not make out the details of thedigestive tract movement under frame rate of2f/s. With low forward speed ofcapsule endoscopy,4to8working hours results that the capsules may lay offbefore its entry into the small intestine because of energy depletion. In thatcase, this paper study on NTSC capsule endoscopy system based on wireless power. This system consists of wireless capsule endoscope, wireless powertransmission devices, wireless receiver and the image workstation. Capsuleendoscope carries out NTSC format video data and transmits them out ofbody through the RF circuit. Vitro wireless receiver sends the video datareceived to image workstation. Image acquisition card in the workstationcollect the images and display them real-timely with frame rate of30f/s.Wireless energy supply device consists of outside wireless powertransmitting device and internal wireless power receiving subsystem incapsule endoscope. The outside wireless power transmitting device cangenerate uniformed changing magnetic field in the special space, and thewireless power receiving subsystem receive electric power which allows anflexible working duration and solves the existing energy problems in currentcapsule.