Healthcare – Clinical Imaging Projects
X-ray interferometry imaging is poised to be the next major advance in diagnostic radiology. X-ray interferometry can be implemented as projection radiography, tomosynthesis, and CT, improving state of the art across all types of diagnostic x-ray applications. Refined Imaging will construct, as seen below, an x-ray interferometry system for projection radiography of lungs and conduct a small pilot study to illustrate its diagnostic capabilities.
The figure above is a sketch of an interferometry radiographic unit to image the chest cavity.
Grating interferometry imaging can enhance the utility of x-ray imaging by providing additional information beyond traditional absorption imaging. Due to the limits of radiographic contrast, conventional imaging is not effective as one might desire for imaging of tissues such as liver, prostate, uterus, and lung. X-ray interferometry simultaneously provides three complementary and correlated images in a single scan: the traditional absorption image, a dark-field (showing tissue scattering) image, and a differential phase contrast (showing tissue interfaces) image.
Refined Imaging LLC (RI) will develop the microfabricated optics, instrumentation, and software for a COVID-19 lung imaging X-ray interferometer system. The optics will be configured as a retrofit package for installation in existing clinical X-ray radiography equipment already used at the patient bedside for speed of deployment.
The above figure is a Talbot-Lau interferometer for lung imaging, a human cadaver. (A) A thick fan-beam is scanned across the lungs. (B) The image contrast is formed by X-ray scattering in healthy lung tissue, depicted as the circular sample (B). Scattering features in healthy lung alveoli, with Lm 150 μm, will appear bright. Damaged lung alveoli with Lm > 600 μm will appear dark in the scattering image. The above figure taken from the work of Prof. Franz Pfeiffer, Technical University of Munich.
Gratings, whether fabricated for X-ray or neutron interferometry, and their unique characteristics (compositions, periods, aspect ratio) are the backbone of Refined Imaging’s research and development technology. Since the discovery of X-rays in 1895 by Wilhelm Röntgen, all industrial and medical imaging has used only the absorption imaging modality. In comparison, visible light microscopy has developed absorption, phase contrast, and dark-field imaging modalities. In 2006, researchers in Switzerland and Japan employed microfabricated gratings of gold on silicon wafers to create an X-ray interferometry imaging system. Now, the advantages of phase contrast and dark-field imaging can be applied to industrial and medical applications. The benefits to society are improved images in soft tissue such as diseased lungs and complex structures such as additive manufacturing (hip cups and cranial implants).
Gratings can be fabricated by multiple mechanisms; lithography/LIGA (LIGA, German acronym for “Lithographie, Galvanoformen, Abformung” meaning “lithography electroplating, molding”), 3D printed, micro-milled, laser milled, Deep Reactive Ion Etching (DRIE), MacEtch, are some of the fabrication techniques. Gratings are also fabricated using various materials, at differing periods (spacing), to create both absorption and phase gratings. Refined Imaging is using several conventional methods as well as some proprietary techniques to fabricate gratings. Refined Imaging will continue to explore different manufacturing techniques and mathematically align the gratings to achieve the maximum image resolution.
The figures above are DRIE microfabricated gratings prior to infilling with metal nanoparticles. Metal infilling is being developed as a much faster route to absorption gratings than gold electroplating
Material Science Non-Destructive Evaluation (NDE) X-ray
Refined Imaging has developed high-aspect-ratio microfabricated optics using a combination of deep-reactive ion etching of silicon wafers, infilling with metal nanoparticles, and precision stacking of multiple units. These fabrication methods for gratings and data analysis algorithms will increase the available X-ray energy from less than 100 kVp to 450 kVp (necessary to image titanium and steel components). These smaller period gratings will increase the current technology of 50-micron image resolution to submicron image resolution, necessary for porosity and delamination inspection.
The figure above is Refined Imaging’s optic installed in a North Star Imaging (NSI) X5000 at the NSI product demonstration lab in Rogers, MN.
Refined Imaging will join with other collaborators to test a blockchain/interferometry procedure for secure AM parts tracking from initial print to end-of-life. The procedure is resistant against parts forgery, design theft, substitution, modification, misuse, and reuse. The testing procedure is configured in a round-robin style performed with a prototype and lab-based AM prints in a 12month program. Follow-on port and shipboard validations are planned.
The integration of secure information transfer with tangible objects is challenging. The approach encodes digital information inside the AM part, not on the surface. Some of the digital information can only be readout with interferometry imaging to defeat duplication, either X-ray or neutron. For detection of sabotage attempts by extraction of the digital information and its re-insertion into a bogus part, the digital information is dispersed through the AM part, with dispersal distances validated via interferometry.
We note some prior theoretical discussion of blockchain to secure AM parts supply chain, including procedures described in the patent literature. Some proposed procedures have employed blockchain encoded information in labels affixed to AM parts, a procedure we think is easily susceptible to duplication and sabotage.
It is essential to internalize the blockchain information within the AM part, hide some of the blockchain information from standard non-destructive evaluation imaging methods, and detect when the blockchain AM region(s) has/have been altered.