PIXSCAN: Pixel detector CT-scanner for small animal imaging

Abstract

A paraître dans NIMAInternational audienceThe PIXSCAN is a small animal CT-scanner based on hybrid pixel detectors. These detectors provide very large dynamic range of photons counting at very low detector noise. They also provide high counting rates with fast image readout. Detection efficiency can be optimized by selecting the sensor medium according to the working energy range. Indeed, the use of CdTe allows a detection efficiency of 100% up to 50 keV. Altogether these characteristics are expected to improve the contrast of the CT-scanner, especially for soft tissues, and to reduce both the scan duration and the absorbed dose. A proof of principle has been performed by assembling into a PIXSCAN-XPAD2 prototype the photon counting pixel detector initially built for detection of X-ray synchrotron radiations. Despite the relatively large pixel size of this detector (330×330 $\mu$m$^2$), we can present three-dimensional tomographic reconstruction of mice at good contrast and spatial resolution. A new photon counting chip (XPAD3) is designed in sub-micronique technology to achieve 130×130 $\mu$m$^2$ pixels. This improved circuit has been equipped with an energy selection circuit to act as a band-pass emission filter. Furthermore, the PIXSCAN-XPAD3 hybrid pixel detectors will be combined with the Lausanne ClearPET scanner demonstrator. CT image reconstruction in this non-conventional geometry is under study for this purpose

A geometrical calibration method for the PIXSCAN micro-CT scanner

“…The usual approach is to use the projection data of a known calibration object to deduce the calibration parameters [1,2]. In this framework, we propose a method based on the least square regression to calibrate the PIXSCAN [3], an X-ray micro-CT scanner demonstrator developed at CPPM. The geometrical configuration of the PIXSCAN is described in section 2.…”

“…In this framework, we propose a method based on the least square regression to calibrate the PIXSCAN [3], an X-ray micro-CT scanner demonstrator developed at CPPM. The geometrical configuration of the PIXSCAN is described in section 2.…”

“…The PIXSCAN is a small animal X-ray CT scanner based on ultra fast hybrid pixel detector. It consists of a step rotating animal holder placed between a fixed X-ray source and a fixed detector [3] (figure 1).…”

Simulation of PIXSCAN, a photon counting micro-CT for small animal imaging

“…Moreover the correct simulation of a system allows the unfolding of the different components that act on the detector response, hence providing a complete understanding of the data. This paper describes the simulations of PIXSCAN-XPAD2 [1], a micro-CT scanner for small animals. The good agreement between data and simulation validates the use of these tools for the design and data analysis of the next version of the scanner, PIXSCAN-XPAD3 [2].…”

“…The PIXSCAN-XPAD2 is a cone beam micro-CT scanner demonstrator for small animals. The system consists of a rotating platform placed between an X-ray source 1 and the photon detector. The mouse stands on the platform (fixed to a mouse holder), while the platform rotates 360 o , step by step (typically, 1 o /step).…”