טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentGeva Adam
SubjectX-Ray Computed Tomography through Scatter
DepartmentDepartment of Electrical Engineering
Supervisor Professor Yoav Schechner
Full Thesis textFull thesis text - English Version


Abstract

X-ray Computed Tomography (CT) scanning was introduced in the 1970’s. The number of annual CT scans in the United States has increased from 3 million in 1980 to over 80 million scans in 2018.

Presently, it is considered the leading man-made source of radiation that is affecting our body. The effects of this radiation on our health is an active field of research and debate. CT is a life-saving invention that has deeply influenced the way medicine is conducted today. It is used in the management of many injuries and diseases, such as tumor detection, strokes, traumatic brain injuries, and many others.

In current CT scanners, tomographic reconstruction relies only on directly transmitted photons. The models used for reconstruction have regarded photons scattered by the body as noise or disturbance to be disposed of, either by acquisition hardware (an anti-scatter grid) or by the reconstruction software. This increases the radiation dose delivered to the patient. Treating these scattered photons as a source of information, we solve an inverse problem based on a 3D radiative transfer model that includes both elastic (Rayleigh) and inelastic (Compton) scattering. We further present ways to make the solution numerically efficient. The resulting tomographic reconstruction is more accurate than traditional CT, while enabling significant dose reduction and chemical decomposition. Demonstrations include both simulations based on a standard medical phantom and a real scattering tomography experiment.