Experimental and theoretical optimization of laser-produced x-ray spectra for vascular imaging

Experimental and theoretical studies of image quality using iodinated contrast agent and x-ray spectra generated by laser-based x-ray source were performed A TableTop Terawatt (T-3) laser(intensity: 10(17)-10(19) W/cm(-2), pulse duration: 150 fs or 450 fs, with or without controlled pre-pulse) was used to create x-ray source. Infrared and/or green beams were utilized. Ba, La, Ce, Nd, and Gd laser targets were used. For each target, a number of suitable filters was utilized to produce optimized xray spectra for a specific imaging task The MTF function due to the focal spot was obtained A simple theoretical model of x-ray detector response was developed. An index of image quality (Detective Image Quality) as well as a figure of merit for dual energy imaging FOM(DESA)were defined and optimized via x-ray spectrum manipulation. The optimum, for a specific imaging task, technique parameters such as: target/filter combination, focal spot size, laser-light wavelength and surface power density, laser pulse duration, pre-pulse delay and contrast ratio, and hot electrons temperature were obtained experimentally and confirmed theoretically. We found that an optimized laser-based x-ray source can outperform conventional x-ray tube-based source in application to vascular imaging in terms of contrast resolution and spatial resolution.