J. Phys. IV France 11 (2001) Pr2-429-Pr2-432
Laser produced X-ray source in the 10-60 keV range at 1 kHz. Modified irradiation schemes in order to reach medical imaging qualityF. Albert1, A. Sjögren1, C.-G. Wahlström1, S. Svanberg1, C. Olsson2 and H. Merdji3
1 Lund Institute of Technology, Atomic Physics Division, Box 118, 22100 Lund, Sweden
2 Department of Diagnostic Radiology, Lund University Hospital, 22285 Lund, Sweden
3 CEA-DSM, DRECAM-SPAM, 91191 Gif-sur-Yvette, France
By tightly focusing ultra-short pulses from a Ti : sapphire terawatt laser onto a high-Z metallic target, hard x-ray pulses of short duration are produced. In most of our previous work concerning x-rays, a 150 mJ laser pulse with a 110 fs duration has been used. Using mostly tin and tantalum targets, hard x-rays in the 10-60 keV range have been produced and used in differential absorption imaging around the [MAT] absorption edge of a contrast agent and also in imaging employing gated viewing for suppression of scattered radiation. In order to increase the x-ray yield (shortening the acquisition time) an increase in the laser repetition rate is desirable while still staying in the [MATH] energy regime. We have used a 1 kHz repetition-rate laser delivering 35 fs pulses in order to work towards these goals. We have clear evidence of hard x-ray generation above 30 keV, even for low laser pulse energies. We also studied the effect of a fs prepulse. The medical imaging capability of the source was explored. The use of a prepulse has been optimized in order to improve the image quality as well as the overall x-ray generation yield.
© EDP Sciences 2001