Implementation and validation of a lung x-ray interferometry imaging system, with applications to COPD, COVID-19 and other lung diseases

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Abstract Lung diseases ranging from cancer to chronic obstructive pulmonary disease (COPD) affect large numbers of men and women worldwide each year. Current news reports describe the respiratory impact of COVID-19; likewise, the past year has seen extensive coverage of the respiratory problems caused by vaping. Worldwide, lung diseases of all types result in millions of deaths per year at a staggering cost of trillions of dollars annually. Radiography and CT are the primary diagnostic imaging tools for lung diseases. Radiography and CT do well at visualizing denser structures such as tumors, but low x-ray absorption and small local changes in density that characterize many lung diseases limit the visualization of lung tissue itself. While techniques such as radiomics can extract additional information from images, suboptimal lung image quality inherently limits diagnostic interpretation. The development of a low-cost, safe, non-invasive diagnostic imaging technique that provides improved visualization of lung tissue and lung diseases is highly desirable. X-ray interferometry imaging potentially answers the need for better diagnostic imaging of lung diseases of many types. Radiography and CT are relatively insensitive to loss of alveolar tissue and small-scale structural changes in the lung. By comparison, x-ray interferometry is highly sensitive to tissue structural changes at these length scales, due to the physics of diffraction and scattering of x-rays. Interferometry simultaneously provides a conventional absorption image with two types of interferometric images: dark-field and phase contrast. The “dark-field” image is especially well-suited to visualizing small changes in lung structure. Refined Imaging LLC, in collaboration with Louisiana State University (LSU) and Pennington Biomedical Research Center (PBRC), will construct an x-ray interferometry system for projection radiography of lungs, and conduct a small pilot study to illustrate its diagnostic capabilities. Our goal is to demonstrate visualization capabilities that compare favorably to CT, but with the low dose and convenience of planar radiography. Our interferometer acquires a scanned image of the lungs of a standing person in a single breath hold. Key design targets include a scan time of 5 seconds and an effective dose less than 35 µSv. The pilot study will acquire interferometry images for 15 COPD patients and 5 healthy volunteers recruited by LSU pulmonologists. Interpretation of interferometry images is benchmarked against pulmonary function test, radiography and CT. Refined Imaging LLC and LSU have the technical expertise and experience to construct the proof-of-concept interferometry imaging system. Our colleagues at PBRC have substantial experience with clinical studies, while LSU radiologists and pulmonologists provide expertise in diagnosis imaging and management of lung disease. Ultimately, Refined Imaging LLC will partner with a medical imaging systems manufacturer to commercialize clinical X-ray interferometry technology, which will provide fast high-quality lung imaging with less radiation dose and lower cost than currently available from lung CT.