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Medical quantum X-ray imaging with 2D detectors

Jürgen Giersch 

Universität Erlangen-Nürnberg, Physikalisches Institut 4, Erwin-Rommel-Straße 1, Erlangen 91052, Germany

Abstract

After W. C. Roentgen has discoverd his X-rays the benefit for medical diagnostics has been perceived very early. Since then a lot of improvements have been achieved, but modern radiographic systems use still the same principle: the energy of the photons hitting a picture element are integrated over the exposure time. This means that the information about the indiviual photon energy is lost.
In medicine it is important to get as much information as possible by the dose being applied. A so-called quantum imaging system is capable of discerning and processing each single X-ray quantum and is therefore very attractive for medical application. A first step in this direction are photon counting detectors, where each pixel determines the number of the incident photons.
Recent developments have lead to a hybrid pixel detector concept which is a very promising approach for quantum imaging. These detectors are sandwich structures consisting of two flip chiped layers - an X-ray absorbing semiconductor and a read out electronic chip. Both layers are connected by bump bonding technology.
The Medipix2 detector is a very powerful realisation of such a photon counting system. The Medipix2 has an active area of 1.4 by 1.4 cm2 consisting of 65000 parallel working photon counting pixel cells with a size of 50 μm. The Medipix2 readout chip can be combined with different absorbing materials like Silicon, Gallium Arsenide or Cadmium Telluride.
The challenge in hybrid pixel detectors for medical application is the realisation of large area detectors. But there are already proposals on how to overcome the smallness of a single detector.
Photon counting detectors like Medipix2 might be just the beginnig of a new exciting evolution, the aim could be a spectroscopic pixel detector which is capable of measuring the energy of each single photon. Monte Carlo simulations show that such a detector would lead to a big benefit in X-ray imaging in future.

 

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Presentation: invited oral at E-MRS Fall Meeting 2004, Symposium D, by Jürgen Giersch
See On-line Journal of E-MRS Fall Meeting 2004

Submitted: 2004-06-27 01:07
Revised:   2009-06-08 12:55