Laser-wakefield accelerators as hard x-ray sources for 3D medical imaging of human bone

A bright μm-sized source of hard synchrotron x-rays (critical energy Ecrit > 30 keV) based on the betatron oscillations of laser wakefield accelerated electrons has been developed. The potential of this source for medical imaging was demonstrated by performing micro-computed tomography of a human femoral trabecular bone sample, allowing full 3D reconstruction to a resolution below 50 μm. The use of a 1 cm long wakefield accelerator means that the length of the beamline (excluding the laser) is dominated by the x-ray imaging distances rather than the electron acceleration distances. The source possesses high peak brightness, which allows each image to be recorded with a single exposure and reduces the time required for a full tomographic scan. These properties make this an interesting laboratory source for many tomographic imaging applications

High-resolution μCT of a mouse embryo using a compact laser-driven X-ray betatron source

High-resolution microcomputed tomography with benchtop X-ray sources requires long scan times because of the heat load limitation on the anode. We present an alternative, high-brightness plasma-based X-ray source that does not suffer from this restriction. A demonstration of tomography of a centimeter-scale complex organism achieves equivalent quality to a commercial scanner. We will soon be able to record such scans in minutes, rather than the hours required by conventional X-ray tubes

Development of a Soft X-ray Microprobe for Radiobiology Studies

The King's College London (KCL) first X-ray microprobe (MKI) and the third generation microfocus X-ray sources (MKIII) are intended to be used for various applications including the study of physical and biological interactions at the atomic and molecular scales. The microfocus ultra-soft X-ray sources (MKI and MKIII) with interchangeable targets will provide a superior spatial resolution (a focal spot a few hundreds of nanometres in diameter can be achieved) and the control of the dose delivered to irradiated cells. This will require characterization of the spectra and intensities of the source, measurements of the focus intensities and spot sizes of suitable X-ray optics such as zone plates, grazing incidence microstructured optical arrays and multilayer mirrors

Measurements of self-guiding of ultrashort laser pulses over long distances

We report on the evaluation of the performance of self-guiding over extended distances with $f/20$ and $f/40$ focussing geometries. Guiding over $39\,\mathrm{mm}$ or more than 100 Rayleigh ranges was observed with the $f/20$ optic at ${n}_{e}=1.5\times {10}^{18}\,{\mathrm{cm}}^{-3}$. Analysis of guiding performance found that the extent of the exiting laser spatial mode closely followed the matched spot size predicted by 3D nonlinear theory. Self-guiding with an $f/40$ optic was also characterised, with guided modes observed for a plasma length of $90\,\mathrm{mm}$ and a plasma density of ${n}_{e}=9.5\times {10}^{17}\,{\mathrm{cm}}^{-3}$. This corresponds to self-guided propagation over 53 Rayleigh ranges and is similar to distances obtained with discharge plasma channel guiding

High-resolution tomographic imaging using coherent hard x-rays from compact laser driven accelerators

Extremely bright coherent femtosecond x-ray pulses are generated in compact laserdriven electron accelerators. Micro-tomography obtained with the Gemini laser indicates the usefulness of these sources in research and clinical applications