Characterization and Testing of LAS: A Prototype `Large Area Sensor' With Performance Characteristics Suitable for Medical Imaging Applications

The Large Area Sensor (LAS) is a 1350 times1350 array of active pixels on a 40 Im pitch fabricated in a 0.35 im CMOS process. Stitching technology is employed to achieve an area of 5.4 cm times5.4 cm. The sensor includes 'regions of reset', whereby three different integration times can be set on the array to achieve a large imaging range for static scenes. Characterization of the noise performance included temporal and fixed pattern sources. LAS was found to have a read noise of 62 e-, a full well capacity of 61 times103 e- and a conversion gain of 5 e- per digital number (DN). The fixed pattern noise (FPN) was evaluated at half saturation; within a single stitched section of the array, column-to-column FPN was found to be 0.6%, while the pixel-to-pixel FPN was 3%. Both FPN sources were found to be gain related and could be corrected via flat fielding. Based on the results of characterization, LAS was coupled to a structured CsI:Tl scintillator and included in an X-ray diffraction system developed for the analysis of breast biopsy samples. Data acquired with plastic test objects agrees with that acquired by a previous prototype sensor. It is demonstrated that an imaging output range of 140 dB can be achieved using integration times of 0.1 ms to record the transmitted X-ray beam and 2.3 s to record the lower intensity scattered radiation.

[1]  P M Evans,et al.  An investigation into the use of CMOS active pixel technology in image-guided radiotherapy. , 2008, Physics in medicine and biology.

[2]  Eric R. Fossum,et al.  CMOS image sensors: electronic camera on a chip , 1995, Proceedings of International Electron Devices Meeting.

[3]  R Turchetta,et al.  Empirical electro-optical and x-ray performance evaluation of CMOS active pixels sensor for low dose, high resolution x-ray medical imaging. , 2007, Medical physics.

[4]  Sarah Elizabeth Bohndiek.  Active pixel sensors for breast biopsy analysis using X-ray diffraction , 2008 .

[5]  Robert D. Speller,et al.  Optical characterisation of a CMOS active pixel sensor using periodic noise reduction techniques , 2010 .

[6]  James R. Janesick,et al.  Photon Transfer DN → λ , 2007 .

[7]  Danny Scheffer,et al.  A wafer scale active pixel CMOS image sensor for generic x-ray radiology , 2007, SPIE Medical Imaging.

[8]  Hao Min,et al.  Modeling and estimation of FPN components in CMOS image sensors , 1998, Electronic Imaging.

[9]  S.E. Bohndiek,et al.  Comparison of Methods for Estimating the Conversion Gain of CMOS Active Pixel Sensors , 2008 .

[10]  Sarah E Bohndiek,et al.  A CMOS active pixel sensor system for laboratory- based x-ray diffraction studies of biological tissue , 2008, Physics in medicine and biology.

[11]  Sarah E. Bohndiek,et al.  A 54mm x 54mm — 1.8Megapixel CMOS image sensor for medical imaging , 2008, 2008 IEEE Nuclear Science Symposium Conference Record.

[12]  Robert D. Speller,et al.  The Multidimensional Integrated Intelligent Imaging project (MI-3) , 2009 .