Inverse Compton radiation: a novel x-ray source for K-edge subtraction angiography?

Abstract

Coronary angiography is clinically used worldwide to diagnose diseases of coronary arteries. Despite its effectiveness, this technique is quite invasive and it is associated to significant risks due to the arterial catheterisation needed to inject the contrast agent. A valid alternative is using the K-edge subtraction method, which is based on the subtraction of two images acquired at energies bracketing the K-edge of the contrast element. The enhanced sensitivity of K-edge subtraction allows the intravenous injection of the contrast agent, thus reducing the risks of catheterisation.This technique can be effectively implemented by using intense and quasi-monochromatic X-ray beams. Synchrotron radiation has been proven to work well for this purpose, but its cost and size prevent a widespread clinical application. Inverse Compton sources are among the most promising innovative sources of intense and quasi-monochromatic X-rays. These sources are intrinsically more compact than those based on synchrotron radiation. In this work, the potential application of inverse Compton radiation to K-edge subtraction angiography is investigated. To this purpose, after a short review of the physics behind the inverse Compton process, an analytical framework is described. The proposed model is based on the application of the K-edge subtraction algorithm to calculate the SN R of details inside a suitable mathematical phantom. That allowed us to identify the characteristics of an inverse Compton source required for K-edge subtraction imaging. In particular, it was estimated that a photon fluence of 10 8 ph mm −2 is necessary to detect signals of clinical interest. Novel sources based on inverse Compton promise to achieve this requirement with an acquisition time of few hundreds of ms. This feature, together with compactness, broad two-dimensional radiation field, absence of harmonic contamination and the ability to deliver high photon fluxes also at high energies, makes this kind of sources promising for K-edge subtraction angiography and other diagnostic applications.

Dual-Energy X-ray Medical Imaging with Inverse Compton Sources: A Simulation Study

“…A fluence of about 1 ×10 7 ph mm −2 is barely sufficient to image the smallest vessels considered here (2.5 mm diameter) with a contrast medium concentration of 10 mg mL −1 . Higher values of fluence guarantee a better visibility of the smaller details with less contrast medium, as estimated in our previous work [54]. Our results are also compatible with past studies aimed at investigating the effects of energy separation [61] and energy spread [53] in KES imaging.…”

“…Indeed, the signal of the bone competes with the signal of the small blood vessels perfused with the contrast medium. Furthermore, coronary angiography is much more demanding in terms of X-ray beam intensities, due to the significant attenuation of surrounding tissues in the chest [54]. A careful setting of the ICS X-ray beams is mandatory to obtain a correct reconstruction of the mass thickness of the iodinated structures, a sufficient SNR in the contrast image and a good rejection of the bone signal (coronary angiography).…”

Spectroscopic imaging at compact inverse Compton X-ray sources

“…In a simulation study, Paterno et al [67] evaluated the applicability of KES at ICSs for a realistic dilution of the iodine contrast agent in arteries and the projected beam parameters of the proposed BriXS project [28]. They found that ICSs have to deliver a fluence of 10 8 ph/mm 2 at the sample plane to image most arteries with sufficient contrast and acquisition times of a few hundred milliseconds, which is significantly higher than demonstrated up to now.…”

A new method for spatial mode shifting of a stabilized optical cavity for the generation of dual-color X-rays

“…X-ray imaging tests with ICS sources using contrast agents have been reported with (quasi-)monochromatic beam at a single energy above the K-edge of iodine [16,17], as well as using filtration of the same material used as contrast medium and specific reconstruction algorithms [18,19]. Also, simulations of the application of KES technique with X-ray beams of proposed ICS facilities demonstrated the potential of these sources in the case of coronary angiography and contrast-enhanced dual-energy mammography [20,21]. Nonetheless, dualenergy KES experiments with ICS have never been carried out so far, due to the lack of an effective implemen-tation of a fast dual-energy switch.…”