Imaging with high Dynamic using an Ionization Chamber

TL;DR

This paper presents a novel ionization chamber with MicroCAT structure combining gas gain and electronics to achieve an extremely high dynamic range suitable for advanced medical imaging and scattering applications.

Contribution

The work introduces a new detector design integrating gas amplification with spatial resolution, enabling high dynamic range and adjustable gas gain for optimized imaging performance.

Findings

Achieves a dynamic range of 8-9 orders of magnitude.

Supports frame rates up to 10 kHz.

Provides single photon resolution at low fluxes.

Abstract

In this work a combination of an ionization chamber with one-dimensional spatial resolution and a MicroCAT structure will be presented. The combination between gas gain operations and integrating front-end electronics yields a dynamic range as high as eight to nine orders of magnitude. Therefore this device is well suitable for medical imaging or applications such as small angle x-ray scattering, where the requirements on the dynamic of the detector are exceptional high. Basically the described detector is an ionization chamber adapted to fan beam geometry with an active area of 192 cm and a pitch of the anode strips of 150 micrometer. In the vertical direction beams as high as 10 mm can be accepted. Every read-out strip is connected to an analogue integrating electronics channel realized in a custom made VLSI chip. A MicroCAT structure utilized as a shielding grid enables frame rates as high as 10kHz. The high dynamic range observed stems from the fact that the MicroCAT enables active electron amplification in the gas. Thus a single photon resolution can be obtained for low photon fluxes even with the integrating electronics. The specialty of this device is that for each photon flux the gas amplification can be adjusted in such a fashion that the maximum DQE value is achieved.