A Fluorescence based Wireless Capsule Endoscopic Tool for Screening Gastrointestinal Cancer
Date
2020-08-06
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
ORCID
0000-0002-9737-2032
Type
Thesis
Degree Level
Doctoral
Abstract
Colorectal cancer is the second leading cause of cancer related deaths in the United States
when men and women are combined. It is also the third most common type of cancer diagnosed
in both women and in men. The phase at which the cancer is diagnosed is an important factor in
deciding the prognosis of the patient. Despite the technological advancement in therapeutic and
diagnostic field, the colorectal cancers are often spotted in advanced stage which affects the
survival rate of patients adversely. Thus, early detection of cancer is important to improve the
survival rate of patients.
The conventional wired endoscopic system is an invasive process in which a flexible and
long cable is inserted into the digestive tube which makes the process uncomfortable and painful
for the patients. This makes the patient to not want to go through the procedure, ultimately
hampering the early detection process. In order to relieve the patient’s suffering and visualize the
gastrointestinal (GI) tract, Wireless Capsule Endoscopy (WCE) is introduced. A typical WCE is a
pill-sized swallowable capsule integrated with electronics, camera, optics and wireless
connectivity feature, which provides an opportunity to diagnose the GI tract through a simple and
pain-free procedure. However, there are still several limitations of this technology which limits its
functionality in the modern-day healthcare system. One of these challenges is related to image
quality and frame rate. Higher frame rate and improved resolution increases the ability to detect
more landmarks and lesions while decreasing the probability of missing important information.
Although capturing of high-resolution image is now possible due to the rapid advancement in
imaging technology, integrating such cameras into the world of WCE and transmitting high quality
captured images would significantly affect the battery life. Therefore, a high-quality compression
method is required that would reduce the impact on battery life while preserving image quality.
However, the available compression algorithms are lossy and needs complex system architecture
and on-chip memory. Moreover, this technology captures thousands of images from each
examination. As these capsules are not able to automate the detection of abnormality, the doctors
are required to go through each frame in search of abnormality which is time-consuming and
tiresome. Thus, alternate methods are needed to be explored.
Fluorescence imaging is widely used in various fields for selective and specific detection
of target. In order to test the principle of fluorescence imaging, a fluorometer is designed in this
work to detect breast cancer cells (MDA-MB-231) and colorectal cancer cells (HCT116). The
breast cancer cells are conjugated with Green Fluorescent Protein (GFP) while the colorectal
cancer cells are conjugated with IRFP702 fluorophore as explained in Chapter 4 and 5 respectively.
The excitation and emission wavelength of GFP and IRFP702 fluorophores are different. The
developed fluorometer can detect both breast cancer cells and colorectal cancer cells when
excitation and emission components are modified to cover the excitation and emission
wavelengths of respective conjugated fluorophores.
After the proof-of-concept is established, a WCE prototype is developed which utilizes the
principle of fluorescence for automating the detection of colorectal cancer. The prototype is tested
on porcine intestine and liquid phantom. The developed device can detect low-level of
fluorescence emitted by fluorophore. This was tested by first spraying varying concentration of
fluorescein (18 nM to 231μM) on top of the swine intestine and testing with the developed device.
This device paves a way for pain-free, non-invasive screening for early stage detection of cancer
promoting mass-screening and ultimately improving the survival rate of the patients. By utilizing
the proposed capsule with targeted molecular contrast agents, which are selectively probed to the cancerous cells, early detection of the multiple types of cancer could be possible with increased
sensitivity and at a relatively low cost.
Description
Keywords
Wireless capsule endoscopy, Colorectal cancer, Fluorescence, Non-invasive
Citation
Degree
Doctor of Philosophy (Ph.D.)
Department
Electrical and Computer Engineering
Program
Electrical Engineering