Assessment of a New High-Performance Small-Animal X-Ray Tomograph

Abstract

Abstract-We have developed a new X-ray cone-beam tomograph for in vivo small-animal imaging using a flat panel detector (CMOS technology with a microcolumnar CsI scintillator plate) and a microfocus X-ray source. The geometrical configuration was designed to achieve a spatial resolution of about 12 lpmm with a field of view appropriate for laboratory rodents. In order to achieve high performance with regard to per-animal screening time and cost, the acquisition software takes advantage of the highest frame rate of the detector and performs on-the-fly corrections on the detector raw data. These corrections include geometrical misalignments, sensor non-uniformities, and defective elements. The resulting image is then converted to attenuation values. We measured detector modulation transfer function (MTF), detector stability, system resolution, quality of the reconstructed tomographic images and radiated dose. The system resolution was measured following the standard test method ASTM E1695-95. For image quality evaluation, we assessed signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) as a function of the radiated dose. Dose studies for different imaging protocols were performed by introducing TLD dosimeters in representative organs of euthanized laboratory rats. Noise figure, measured as standard deviation, was 50 HU for a dose of 10 cGy. Effective dose with standard research protocols is below 200 mGy, confirming that the system is appropriate for in vivo imaging. Maximum spatial resolution achieved was better than 50 micron. Our experimental results obtained with image quality phantoms as well as with in-vivo studies show that the proposed configuration based on a CMOS flat panel detector and a small micro-focus X-ray tube leads to a compact design that provides good image quality and low radiated dose, and it could be used as an add-on for existing PET or SPECT scanners.

Software architecture for multi-bed FDK-based reconstruction in X-ray CT scanners

“…This module includes misalignment and linearization corrections, which can also be performed during acquisition. A more detailed description can be found in [5].…”

“…This system is fully described in [5]. Detector misalignment correction was performed during acquisition.…”

“…This configuration presents advantages over other alternatives used in clinical and preclinical applications: reduction of acquisition time, large axial field of view (FOV) without geometrical distortions, and optimization of radiated dose [5]. proposed by Feldkamp et al (FDK) [6] are still widely used for solving the 3D reconstruction task because of their straightforward implementation and computational efficiency [4].…”

“…This configuration presents advantages over other alternatives used in clinical and preclinical applications: reduction of acquisition time, large axial field of view (FOV) without geometrical distortions, and optimization of radiated dose [5]. Despite the existence of a remarkable progress in statistical reconstruction algorithms, approximate methods based on the algorithm are numerous additional details to consider in order to obtain good quality images at a reasonable computational cost.…”

Comparative study of two flat-panel X-ray detectors applied to small-animal imaging cone-beam micro-CT

“…However, most of them are focused on CCD based detectors and do not take into account the data readout of the different devices [1][2][3]. There are also some works such as [4][5][6][7], which assess the performance of flat-panel detector based tomography systems, measuring the quality of the obtained tomographic data.…”