K-edge subtraction imaging for iodine and calcium separation at a compact synchrotron x-ray source

Computational method for the optimization of quasimonoenergetic laser Compton x-ray sources for imaging applications

The development of compact quasimonoenergetic x-ray radiation sources based on laser Compton scattering (LCS) offers opportunities for novel approaches to medical imaging. However, careful experimental design is required to fully utilize the angle-correlated x-ray spectra produced by LCS sources. Direct simulations of LCS x-ray spectra are computationally expensive and difficult to employ in experimental optimization. In this manuscript, we present a computational method that fully characterizes angle-correlated LCS x-ray spectra at any end point energy within a range defined by three direct simulations. With this approach, subsequent LCS x-ray spectra can be generated with up to 200 times less computational overhead.

Numerical evaluation of high-energy, laser-Compton x-ray sources for contrast enhancement and dose reduction in clinical imaging via gadolinium-based K-edge subtraction

Conventional x-ray sources for medical imaging utilize bremsstrahlung radiation. These sources generate large bandwidth (BW) x-ray spectra with large fractions of photons that impart a dose, but do not contribute to image production. X-ray sources based on laser-Compton scattering can have inherently small energy BWs and can be tuned to low dose-imparting energies, allowing them to take advantage of atomic K-edge contrast enhancement. This paper investigates the use of gadolinium-based K-edge subtraction imaging in the context of mammography using a laser-Compton source through simulations quantifying contrast and dose in such imaging systems as a function of laser-Compton source parameters. Our simulations indicate that a K-edge subtraction image generated with a 0.5% BW (FWHM) laser-Compton x-ray source can obtain an equal contrast to a bremsstrahlung image with only 3% of the dose.

Spectroscopic imaging at compact inverse Compton X-ray sources

While K-edge subtraction (KES) imaging is a commonly applied technique at synchrotron sources, the application of this imaging method in clinical imaging is limited although results have shown its superiority to conventional clinical subtraction imaging. Over the past decades, compact synchrotron X-ray sources, based on inverse Compton scattering, have been developed to fill the gap between conventional X-ray tubes and synchrotron facilities. These so called inverse Compton sources (ICSs) provide a tunable, quasi-monochromatic X-ray beam in a laboratory setting with reduced spatial and financial requirements. This allows for the transfer of imaging techniques that have been limited to synchrotrons until now, like KES imaging, into a laboratory environment. This review article presents the first studies that have successfully performed KES at ICSs. These have shown that KES provides improved image quality in comparison to conventional X-ray imaging. The results indicate that medical imaging could benefit from monochromatic imaging and KES techniques. Currently, the clinical application of KES is limited by the low K-edge energy of available iodine contrast agents. However, several ICSs are under development or already in commissioning which will provide monochromatic X-ray beams with higher X-ray energies and will enable KES using high-Z elements as contrast media. With these developments, KES at an ICS has the ability to become an important tool in pre-clinical research and potentially advancing existing clinical imaging techniques.