% Chapter 1 \chapter{Introduction} % Main chapter title \label{Chapter1} % For referencing the chapter elsewhere, use \ref{Chapter1} \lhead{Chapter 1. \emph{Introduction}} % This is for the header on each page - perhaps a shortened title %---------------------------------------------------------------------------------------- Many of the profound innovations in science and engineering start with metaphors presented in the science fictions. The wireless information networking industry was motivated by the Captain Kirk's communicator in the 1960s science fiction series ``Star Trek''. The idea was formed in the early 1980s; the Federal Communications Commission (FCC) released the Industrial, Scientific and Medical (ISM) bands; the IEEE 802.11 standardization committee created the WLAN standard in 1997 \cite{pahlavan1985wireless, pahlavan1995trends, pahlavan1988voice, pahlavan1989multipath, zhang1989slotted, howard1990measurement}. After almost half a century, modern smart phones are what the evolution of the ``Star Trek'' communicator fantasy brought to us. Recently, another 1960s science fiction, the ``Fantastic Voyage'', in which a space craft with its crew were shrunken to become a micro-device capable of traveling inside human body to remove a brain clot, has stimulated a new wave of innovative science and engineering for the Body Area Network (BAN) \cite{chen2011body, astrin2009standardization, pahlavan2012rf}. That space craft lost its navigation capabilities and went through an unguided dramatic traveling experience within the human body before it exits through tears from the eye of the human subject. Today, wireless endoscopic capsules are traveling inside the digestive system in the same way as the space craft in the fantastic voyage traveled and one can envision emergence of a number of other similar applications for micro-robots inside the human body. \section{Evolution of Wireless Capsule Endoscopy (WCE)} Endoscopy \cite{vakil1995measurement} is a medical procedure used to examine the interior wall of the digestive system. According to a study conducted in 2002 \cite{costamagna2002prospective}, approximately 19 million people in the United States were estimated to be affected by disorders of the small intestine. This statistic indicates that effective advancements in endoscopy technology are extremely worthy of investigation. When using the conventional endoscopic instrument, a long flexible tube with a miniature camera needs to be inserted through the mouth or the anus in order to get into the gastrointestinal (GI) tract. Owing to its rigidity and large size, it causes much discomfort to whoever undergoes this procedure. This generally limits the willingness of patients to have their GI tract examined regularly. Furthermore, the lack of capability to reach the entire small intestine is also a significant shortcoming of the current wired endoscope. Wireless Capsule Endoscopy (WCE) \cite{rondonotti2005complications, mishkin2006asge, el2008wireless, iddan2000wireless}, a significant step in the efforts of developing a more effective endoscopy technique, was invented to overcome the above limitations. The first WCE prototype for the small intestine was approved by the Food and Drug Administration (FDA) in 2001. Over subsequent years, this technology has been evolving into one of the most popular non-invasive imaging tools of the intestinal disease diagnosis. WCE is a pill-shaped device which consists of a short focal length CMOS camera, light source, battery and radio transmitter \cite{li2012wireless, pan2011swallowable}. After the endoscopic capsule is swallowed by a patient , this miniature device propelled by peristalsis of GI tract begins to work and record images at least 2 frames per second (permitting the acquisition of over 50 000 images) while moving along the GI tract. At the same time, images are sent out wirelessly in Ultra High Frequency (UHF) at 432 MHz to a small portable recorder attached to the waist \cite{li2009texture}. The images are subsequently downloaded from the portable recorder to a workstation for analysis off line. The whole examine process takes about 8 h, during this period, the patient do not need to be confined to a hospital or clinic environment during the examination and is free to continue their daily routine. Up to now, WCE has been used to detect the following diseases \cite{adler2003wireless, ge2004capsule, lee2004diagnosis} small intestinal blooding, Crohn disease, ulcer, tumors, vascular lesions and colon cancers. %---------------------------------------------------------------------------------------- \section{Motivation} Although WCE provides a non-invasive wireless imaging technology for observing the entire GI tract, one significant drawback of this technology is that it cannot localize itself during its several hours journey. Therefore, when an abnormality is detected by the video source, the physicians have limited idea where the abnormality is located which prevents the following up therapeutic operations being executed immediately. Therefore, having a precise localization system for the endoscopic capsule would greatly enhance the benefits of WCE. However, localization of the WCE inside the human body is not trivial. There are some fundamental technical challenges which make accurate localization inside human body a difficult task. \begin{itemize} \item First, we don't have a clear map of inside human body. A map of the digestive system plays a very important role in refining the localization results \cite{fu2013heterogeneous, zheng2012performance, pahlavan2011principles} since everything goes through the GI tract follows the same route. However, existing computed tomography (CT) and magnetic resonance imaging (MRI) imaging tools are not able to provide enough resolution to extract the path of the small intestine. \item Second, conventional single source localization techniques, for example RF localization techniques, cannot provide satisfactory localization results due to the non-homogeneity and severe attenuation of body tissues \cite{alomainy2009modeling}. We need to design more complicated hybrid localization algorithms that integrate all possible data sources to enhance the localization accuracy. To do this, we need researchers with multidisciplinary background including wireless localization, robotics and image processing etc. \item Third, validation of existing localization algorithms are challenging. After the capsule is swallowed by the patient, we have limited control of the endoscopic capsule. Exploratory clinical procedures such as planar X-ray imaging and Ultrasound cannot be easily used for verifying the position and motion status of the capsule due to their high cost and potential risk to the patient's health. \item Last but most importantly, operating experiments inside human body is extremely difficult. As we mentioned previously, there are practical challenges to verify the performance of any localization algorithm. Moreover, human subjects are different from one and another, we need a uniform platform to do comparative performance evaluation for different algorithms. \end{itemize} These challenges make deign of an accurate localization system for the WCE inside human body a unsolvable engineering problem for more than 13 years. And this became the motivation of my research : To design a localization system that is able to precisely localize the endoscopic capsule as it travels along the digestive system and meanwhile reconstruct the map inside of the small intestine. %---------------------------------------------------------------------------------------- \section{Contributions} To meet the challenges introduced above, in this dissertation, we present an in-body simultaneous localization and mapping technique (Body-SLAM) to enhance the positioning accuracy of WCE inside the small intestine and meanwhile reconstruct the trajectory the capsule has traveled. The contributions of this multi-disciplinary and inter-disciplinary dissertation are: \begin{itemize} \item Design and performance evaluation of a Body-SLAM algorithm to accurate localize the position of WCE and reconstruct the 3D map the capsule has traveled. The proposed Body-SLAM technique estimates the speed and orientation of the endoscopic capsule by analyzing displacements of feature points between consecutive images and this motion information is integrated with the RF measurements by employing a Kalman filter to smooth the localization results and the generated 3D map. \item To achieve this objective, we modeled the motion of the endoscopic capsule using empirical data obtained from a actual patients. This motion model is further imported into a emulation testbed for performance evaluation. \item We designed a tested for performance evaluation of hybrid localization algorithms that benefits from content of the endoscopic images as well as the features of the RF signal emitted from the video capsule. We used this testbed to demonstrate the effectiveness of hybrid localization algorithms for Body-SLAM inside small intestine. \end{itemize} The specific contributions of mine are reflected in the following publications: \begin{enumerate} \item K. Pahlavan, G. Bao, Y. Ye, S. Makarov, U. Khan ... K. Sayrafian, ``Rf localization for wireless video capsule endoscopy''. International Journal of Wireless Information Networks, Vol.19 (4), pp.326-340, 2012. \item G. Bao, Y. Ye, U. Khan, X. Zheng and K. Pahlavan, ``Modeling of the Movement of the Endoscopy Capsule inside GI Tract based on the Captured Endoscopic Images'', The 2012 International Conference on Modeling, Simulation and Visualization Methods (MSV), Las Vegas, USA, July, 2012. \item G. Bao and K. Phalavan, ``Motion Estimation of the Endoscopy Capsule using Region-based Kernel SVM Classifier'', 2013 IEEE International Conference on Electro/Information Technology (EIT), Rapid City, SD, May 9-11, 2013. \item G. Bao, L. Mi and K. Phalavan, ``Emulation on Motion Tracking of Endoscopic Capsule inside Small Intestine'', 2013 World Congress in Computer Science,Computer Engineering, and Applied Computing (WORLDCOMP'13), Las Vegas, USA, 2013. \item G. Bao, L. Mi and K. Phalavan, ``A Video Aided RF Localization Technique for the Wireless Capsule Endoscope (WCE) inside Small Intestine'', 8th International Conference on Body Area Networks, Boston, Massachusetts, United States, September 30 - October 2, 2013. \item L. Mi, G. Bao and K. Phalavan, ``Design and Validation of a Virtual Environment for Experimentation inside the Small Intestine'', 8th International Conference on Body Area Networks, Boston, Massachusetts, United States, September 30 - October 2, 2013. \item R. Fu, G. Bao and K. Pahlavan, ``Activity Classification with Empirical RF Propagation Modeling'', 8th International Conference on Body Area Networks, Boston, Massachusetts, United States, September 30 - October 2, 2013. \item L. Mi, G. Bao and K. Pahlavan, ``Geometric Estimation of Intestinal Contraction for Motion Tracking of Video Capsule Endoscope'', SPIE Medical Imaging: Image-Guided Procedures, Robotic Interventions, and Modeling, San Diego, California, February 15-20, 2014. \item G. Bao, L. Mi, Y. Geng and K. Pahlavan, ``A Computer Vision based Speed Estimation Technique for Localizing the Wireless Capsule Endoscope inside Small Intestine,'' submitted to Signal Processing Letters, IEEE, April, 2014. \item G. Bao, L. Mi, Y. Geng, M. Zhou and K. Pahlavan, ``A Video-based Speed Estimation Technique for Localizing the Wireless Capsule Endoscope inside Gastrointestinal Tract, '' submitted to IEEE Engineering in Medicine and Biology Society (EMBC 14), March, 2014. \item M. Zhou, G. Bao and K. Pahlavan, ``Mutual Information based Motion Tracking Technique for the WCE inside Large Intestine'', submitted to IEEE Engineering in Medicine and Biology Society (EMBC 14), March, 2014. \item G. Bao, L. Mi and K. Pahlavan, ``Hybrid Localization of Micro-robotic Endoscopic Capsule inside Small Intestine by Data Fusion of Vision and RF Sensors'', submitted to Sensor Journal, IEEE, March, 2014. \end{enumerate} A full publication list can be found in Appendix~\ref{AppendixA}. \section{Outline of the Dissertation} This dissertation focuses on the hybrid localization which we called ``Body-SLAM'' for the wireless capsule endoscopy and testbed design for comparative performance evaluation of various localization algorithms inside human body. The rest of the dissertation is organized as follows: in chapter 2, we give a overview of the existing localization technologies of WCE and addressed the technical challenges in this field. In Chapter 3, we present a hybrid localization technique, which we called ``Body-SLAM'', that uses endoscopic images for motion tracking and combines the motion information with the RF signal radiated from the capsule to enhance the localization accuracy, and meanwhile reconstruct the trajectory the capsule has traveled. In chapter 4, performance evaluation of the proposed localization algorithm are given by using empirical data and design of emulation testbed. Finally, we conclude the dissertation in chapter 5 and give the suggested direction of future work. %----------------------------------------------------------------------------------------