Speaker
Description
Laser-based accelerators offer a compact and cost-effective alternative to conventional accelerators for X-ray production, enabling applications in medicine and industry. However, their ultrashort radiation pulses can lead to pile-up effects in conventional spectrometers, motivating the use of passive detectors such as Image Plates (IPs) which integrate the X-ray energy over the exposure time. In this work, we present the characterization and absolute calibration of a system of reusable IPs and a scanner designed for dental applications using an X-ray tube source. The study includes IP reproducibility, signal linearity, resolution dependence, and temporal fading. Results show a reproducible and linear response, with rapid signal fading within the first 30 min, requiring a correction curve to be applied to the measurements. The scanner does not normalize the IP signal, and the output is expressed in instrument-specific units rather than PSL, as commonly used for passive detectors, making an absolute calibration necessary. An X-ray fluorescence-based setup is employed to establish the signal-photon energy relationship using nine elemental targets to generate well-defined characteristic lines while avoiding contributions from the continuous X-ray tube spectrum. We present a calibration curve in the 8-30 keV range, showing good agreement with published results at low energies. Finally, an iterative algorithm for spectral reconstruction is developed using the energy-dependent transmission functions obtained from the measurements of the IP irradiated after a stack of 13 um Al filters, and the number of incident photons. The X-ray tube spectrum is accurately reconstructed by this model at two operating energies, 30 and 50 keV. Future work will focus on recovering the laser-driven X-ray spectrum available at our laboratory (Laser Laboratory for Acceleration and Applications) using the developed algorithm.