A small animal radiation platform equipped with on-board cone-beam CT and conformal irradiation capabilities is being constructed for translational research. To achieve highly localized dose delivery, an x-ray lens is used to focus the broad beam from a 225 kVp x-ray tube down to a beam with a full width half maximum (FWHM) of approximately 1.5 mm in the energy range 40-80 keV. Here, we report on the dosimetric characteristics of the focused beam from the x-ray lens subsystem for high-resolution dose delivery. Using the metric of the average dose within a 1.5 mm diameter area, the dose rates at a source-to-surface distance (SSD) of 34 cm are 259 and 172 cGy min(-1) at 6 mm and 2 cm depths, respectively, with an estimated uncertainty of +/-5%. The per cent depth dose is approximately 56% at 2 cm depth for a beam at 34 cm SSD.

Multilayer optics is one of the widely applied optics for conditioning an X-ray beam in the region of X-ray diffraction. Multilayer optics offers a well-balanced performance. The beam conditioned by a multilayer optic is characterized by low divergence, good spectrum purity, and high intensity. This article will start with a short historical note of the development of X-ray multilayer and a summary on the basic performance characteristics of X-ray multilayer, then move on to the discussion on the design principle of one- and two-dimensional optics. Both parallel beam optics and focusing optics will be addressed. As examples, selected applications of multilayer optics are also briefly discussed. Finally, the main problems associated with the application of multilayer optics are identified and the future developments are discussed.

An approach to using multilayer optics for SAXS is discussed. The approach consists of employing a two-dimensional multilayer focusing optic to monochromatize and intensify the x-ray beam, and a pinhole system to further shape the beam. Depending on the sample scattering power, different pinhole systems can be used. With a two-pinhole system, high flux can be achieved but with nonblocked parasitic scattering from the pinholes and scattering from multilayer reflectors.With a three-pinhole system, parasitic scattering and scattering from multilayer are completely shielded beyond certain angular range for weak scattering samples. Using raytracing method, the performances of the proposed systems are compared to the most commonly used graphite-pinhole system and found to provide a factor 10 more flux for similar resolution and background requirements.

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