X-ray tube-based phase CT: spectrum polychromatics and imaging performance

Abstract

Owing to its advantages in differentiating low-atomic materials over the conventional attenuation-based CT, the x-ray refraction-based phase contrast CT implemented with grating interferometer (namely grating-based differential phase contrast CT) has drawn increasing attention recently. Through the Talbot-effect, the phase variation of an object is retrieved and reconstructed to characterize the object's refraction property. The Talbot-effect is wavelength dependent, and a quantitative investigation into the influence of x-ray source spectrum polychromatics on the imaging performance of the grating-based differential phase contrast CT can provide guidelines on its architecture design and performance optimization. In this work, we conduct a computer simulation study of the x-ray grating-based differential phase contrast CT imaging under the condition of both monochromatic and polychromatic x-ray sources. The preliminary data shows that, the modulation transfer function (MTF) of a grating-based differential phase contrast CT with polychromatic source changes little in comparison to that with a monochromatic one. Furthermore, it is shown that the spectrum polychromatics leads to a remarkable improvement in the contrast-to-noise ratio of a grating-based differential phase contrast CT, which implies that a commercially available x-ray tube can be well suited to build a differential phase contrast CT with a grating-based interferometer to image the refractive property of an object.