Betatron radiation from laser wakefield accelerated electrons and X-rays scattered off a counter-propagating relativistic electron bunch are collimated and hold the potential to extend the energy range to hard X-ray or gamma ray band. The peak brightness of these incoherent radiations could reach the level of the brightest synchrotron light sources in the world due to their femtosecond pulse duration and source size down to a few micrometers. In this article, the principle and properties of these radiation sources are briefly reviewed and compared. Then we present our recent progress in betatron radiation enhancement in the perspective of both photon energy and photon number. The enhancement is triggered by using a clustering gas target, arousing a second injection of a fiercely oscillating electron bunch with large charge or stimulating a resonantly enhanced oscillation of the ionization injected electrons. By adopting these methods, bright photon source with energy over 100 keV is generated which would greatly impact applications such as nuclear physics, diagnostic radiology, laboratory astrophysics and high-energy density science.

Accepted 22 June 2013 Published 24 July 2013 We apply different polarization imaging techniques for cancerous liver tissues, and compare the relative contrasts for difference polarization imaging (DPI), degree of polarization imaging (DOPI) and rotating linear polarization imaging (RLPI). Experimental results show that a number of polarization imaging parameters are capable of differentiating cancerous cells in isotropic liver tissues. To analyze the contrast mechanism of the cancer-sensitive polarization imaging parameters, we propose a scattering model containing two types of spherical scatterers and carry on Monte Carlo simulations based on this bi-component model. Both the experimental and Monte Carlo simulated results show that the RLPI technique can provide a good imaging contrast of cancerous tissues. The bi-component scattering model provides a useful tool to analyze the contrast mechanism of polarization imaging of cancerous tissues.