Low-cost digital x-ray detectors using liquid crystals
Principal Investigator: John Rowlands
Affiliation: Sunnybrook Health Sciences Centre
Abstract: The broad, long-term objective of this proposal is to develop low cost direct digital x-ray imaging systems for general application in radiology and radiation therapy. The Specific Aims are (1) to measure the imaging properties of an XLV (x-ray sensitive light valve) based on the use of a-Se (amorphous-selenium) and a TN (twisted nematic) and ECB (electrically controlled birefringence) liquid crystal cells and develop a theoretical model that can predict the behavior precisely, (2) to design and construct XLV optimized for specific imaging tasks, (3) to challenge the XLV technology to perform in a quantum limited manner for the three radiographic procedures (chest radiography, mammography, and portal imaging) by independent evaluation of XLV/scanner imaging prototypes. The health relatedness of the project is that it will provide a low cost system for any application in radiology and radiation therapy that will maintain or surpass currently available image quality, produce images quickly while doing so at greatly reduced cost, particularly the capital cost. The system has the potential to be manufactured locally in every country with sufficient infrastructure making this an empowering technology for developing countries as well as a cost effective solution for clinics in North America. The research design is that we will combine three well-established technologies, using a-Se as an x-ray to image charge transducer, liquid crystal display technology, and digital optical readout to achieve our goal. The concept is that the latent charge image created on the a-Se layer by interaction with x-rays is made into visible image by physically coupling it to a liquid crystal display. This visible image is then readout optically by a digital camera. The Methods to be used are linear systems analysis, Monte Carlo simulation, detective quantum efficiency (DQE) measurement, phantom tests, as well as comparison of performance with state of the art flat panel imagers.
Funding Period: 2003-09-19 - 2009-07-31
more information: NIH RePORT
- The x-ray light valve: a low-cost digital radiographic imaging systemIvaylo Koprinarov
Med Phys 34:4609-11. 2007..The results demonstrate that our proposed x-ray light valve system has excellent spatial resolution and adequate sensitivity compared to existing technologies...
- The x-ray light valve: a low-cost, digital radiographic imaging system--spatial resolutionRobert D MacDougall
Imaging Research, Sunnybrook Health Sciences Centre, Department of Medical Biophksics, University of Toronto, 2075 Bayview Avenue, Toronto, Ontario M4N 3M5, Canada
Med Phys 35:4216-27. 2008..From this, the authors can conclude that the XLV has an adequate resolution for general radiography. The XLV/scanner also has the potential to eliminate aliasing while maintaining a MTF that exceeds that of a flat-panel imager...
- The x-ray light valve: a potentially low-cost, digital radiographic imaging system-concept and implementation considerationsChristie Ann Webster
Imaging Research, University of Toronto, Sunnybrook Health Sciences Centre, 2075 Bayview Avenue, Toronto, Ontario M4N 3M5, Canada
Med Phys 35:939-49. 2008..The results of our analysis indicate that the XLV can potentially be adapted to a wide variety of radiographic tasks...
- The x-ray light valve: a potentially low-cost, digital radiographic imaging system--a liquid crystal cell design for chest radiographyTimothy C Szeto
Imaging Research, University of Toronto, Sunnybrook Health Sciences Centre, 2075 Bayview Avenue, Toronto, Ontario, M4N 3M5, Canada
Med Phys 35:959-67. 2008..The feasibility of the shift of the characteristic curve is shown experimentally. The experimental results thus demonstrate that an XLV based on the r-ECB cell design exhibits a characteristic curve suitable for chest radiography...
- Digital radiography using amorphous selenium: photoconductively activated switch (PAS) readout systemNikita Reznik
Imaging Research, Sunnybrook Health Sciences Centre, Department of Medical Biophysics, University of Toronto, 2075 Bayview Avenue, Toronto, Ontario, M4N 3M5, Canada
Med Phys 35:1039-50. 2008..This demonstrates that a-Se based x-ray detectors using photoconductively activated switches could form a basis for a practical integrated digital radiography system...
- The optimal optical readout for the x-ray light valve--document scannersP Oakham
Imaging Research, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, Ontario, Canada
Med Phys 35:5672-83. 2008..This combination of criteria shows that a document scanner can be used as a digitization method for the XLV...
- Characterization of a novel anthropomorphic plastinated lung phantomSungwon Yoon
Department of Electrical Engineering, Stanford University, Stanford, California 94305, USA
Med Phys 35:5934-43. 2008..A second generation phantom, which eliminates most of the by-products, is presented. Such anthropomorphic phantoms can be used to evaluate a wide range of novel imaging systems...