A colon imaging capsule has been developed by Check-Cap Ltd (C-Scan<sup>® </sup>Cap). For the procedure, the patient swallows
a small amount of standard iodinated contrast agent. To create images, three rotating X-ray beams are emitted towards the
colon wall. Part of the X-ray photons are backscattered from the contrast medium and the colon. These photons are
collected by an omnidirectional array of energy discriminating photon counting detectors (CdTe/CZT) within the capsule.
X-ray fluorescence (XRF) and Compton backscattering photons pertain different energies and are counted separately by
the detection electronics.
The current work examines a new statistical approach for the algorithm that reconstructs the lining of the colon wall from
the X-ray detector readings. The algorithm performs numerical optimization for finding the solution to the inverse problem
applied to a physical forward model, reflecting the behavior of the system.
The forward model that was employed, accounts for the following major factors: the two mechanisms of dependence
between the distance to the colon wall and the number photons, directional scatter distributions, and relative orientations
between beams and detectors. A calibration procedure has been put in place to adjust the coefficients of the forward model
for the specific capsule geometry, radiation source characteristics, and the detector response.
The performance of the algorithm was examined in phantom experiments and demonstrated high correlation between
actual phantom shape and x-ray image reconstruction. Evaluation is underway to assess the algorithm performance in
An ingestible capsule for colorectal cancer screening, based on ionizing-radiation imaging, has been developed and is in advanced stages of system stabilization and clinical evaluation. The imaging principle allows future patients using this technology to avoid bowel cleansing, and to continue the normal life routine during procedure. The Check-Cap capsule, or C-Scan ® Cap, imaging principle is essentially based on reconstructing scattered radiation, while both radiation source and radiation detectors reside within the capsule. The radiation source is a custom-made radioisotope encased in a small canister, collimated into rotating beams. While traveling along the human colon, irradiation occurs from within the capsule towards the colon wall. Scattering of radiation occurs both inside and outside the colon segment; some of this radiation is scattered back and detected by sensors onboard the capsule. During procedure, the patient receives small amounts of contrast agent as an addition to his/her normal diet. The presence of contrast agent inside the colon dictates the dominant physical processes to become Compton Scattering and X-Ray Fluorescence (XRF), which differ mainly by the energy of scattered photons. The detector readout electronics incorporates low-noise Single Photon Counting channels, allowing separation between the products of these different physical processes. Separating between radiation energies essentially allows estimation of the distance from the capsule to the colon wall, hence structural imaging of the intraluminal surface. This allows imaging of structural protrusions into the colon volume, especially focusing on adenomas that may develop into colorectal cancer.
The Check-Cap capsule, C-Scan Cap, performs intraluminal imaging of the human colon based on X-Ray scatter processes. Basic performance of such a system can be demonstrated using various tube-like phantom objects. Also, from a perspective of capsule dynamics, actuators can and have been used for capsule manipulation. Nevertheless the actual situation of a capsule in use is extremely complex, both in terms of the imaging-target object itself and the capsule dynamics within the same. In order to allow study of imaging system performance in a pseudo-clinical environment, a specialized phantom system has been developed. A tissue-equivalent material has been developed in-house, so as to allow simple usage and flexibility for making a wide variety of phantoms, simple tubes as well as extremely complex segments of the human colon which can possibly demonstrate adenomas. The material itself is durable, flexible, and very similar to water in terms of X-Ray scattering. Based on real abdominal CT images, real colon segments have been extracted to become 3D molds, which were used for producing a set of pseudo-clinical human colon segments. In the aspect of capsule and colon dynamics, capsule propulsion within these phantoms is based on the contents, i.e. capsule is hydro-dynamically propelled by surrounding medium rather than actuators. In addition, a system for generating peristaltic contractions along these colon segments has been developed; this system allows stimulation of the colon and the capsule within using arbitrary programmable contraction waves. This phantom system allows demonstration of pseudoclinical imaging scenarios in the lab.