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Characterisation of a pixel readout chip for medical X-ray imaging
Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Nuclear and Particle Physics.
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2004 In: Nuclear Instruments and Methods in Physics Research A, ISSN 0168-9002, Vol. 525, no 1-2, 217-220 p.Article in journal (Refereed) Published
Place, publisher, year, edition, pages
2004. Vol. 525, no 1-2, 217-220 p.
URN: urn:nbn:se:uu:diva-92180OAI: oai:DiVA.org:uu-92180DiVA: diva2:165163
Available from: 2004-09-24 Created: 2004-09-24Bibliographically approved
In thesis
1. DIXI – a Hybrid Pixel Detector for X-ray Imaging
Open this publication in new window or tab >>DIXI – a Hybrid Pixel Detector for X-ray Imaging
2004 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Medical X-ray imaging is an important tool in diagnostic radiology. The ionising-radiation dose to the patient is justified by the clinical benefit of the examination. Nonetheless, detectors that operate at even lower doses and provide more information to the radiologist are desired. A hybrid pixel detector has the potential to provide a leap in detector technology as it incorporates a more advanced signal-processing capability than currently used detectors.

The DIXI digital detector is a hybrid pixel detector developed for X-ray imaging. It consists of a readout chip and a semiconductor sensor. The division in two parts makes it possible to optimise each part individually. The detector is divided into square pixels with a size of 270 x 270 μm2. DIXI has the ability to count single photons and every readout pixel has two embedded counters to allow the acquisition of two images close in time. A discriminator enables the selection of photons with energies above a preset threshold level.

The readout chip Angie has been developed and its performance has been evaluated in terms of noise, threshold variation and capability to perform energy weighted counting. Silicon sensors have been fabricated, and a control system for DIXI has been designed and built. An electroless process for deposition of Ni/Au bumps on the chip and sensor has been optimised as a preparation for the assembly of a complete detector, which is being assembled by flip-chip bonding using anisotropic conductive film.

A simulation library for the DIXI detector has been set up and results on the image quality are reported for different exposures and working conditions. A theoretical model for hybrid pixel detectors based on the cascaded linear system theory has been developed. The model can be used to investigate and optimise the detector for different detector configurations and operating conditions.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2004. 65 p.
Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1104-232X ; 1018
Radiation sciences, hybrid pixel detector, photon-counting, X-ray, imaging, simulation, Strålningsvetenskap
National Category
Radiology, Nuclear Medicine and Medical Imaging
urn:nbn:se:uu:diva-4572 (URN)91-554-6050-X (ISBN)
Public defence
2004-10-15, Polhemsalen, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, 13:30
Available from: 2004-09-24 Created: 2004-09-24 Last updated: 2013-09-13Bibliographically approved

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