A Monte Carlo simulation study to investigate the potential of diffraction enhanced breast imaging

Recent studies have demonstrated that image contrast in X-ray mammography could be enhanced by making use of both the transmitted and scattered radiation. At small angles coherently scattered photons undergo interference effects which can be used as a means of tissue characterisation. Several form factor data from X-ray diffraction measurements are now available. The authors implemented these data in the EGS4 code so as to use realistic breast tissues (both tumour and healthy tissue) for a Monte Carlo simulation. A breast imaging system which makes use of a combined scatter/transmission signal has been modelled. Results of the authors' simulation confirmed that the contrast between healthy and tumour tissue provided by small-angle scatter radiation is greater than that of primary image for object thicknesses of mammographic interest. Analysis of beam polychromaticity effects in coherent scattering showed that material discrimination is still possible with the conventional X-ray sources currently used. In the design of a diffraction enhanced breast imaging system signal-to-noise ratio performance must be considered in order to fully assess the increase in diagnostic capability effected by this approach

End-user survey for digital sensor characteristics: a pilotquestionnaire study

12nonenoneG LI; PF VAN DER STELT; JGC VERHEIJ; R SPELLER; A GALBIATI; F PSOMADELLIS; R TURCHETTA; S THEODORIDIS; G HALL; BS AVSET; FA TRIANTIS; LONGO R.G., Li; PF VAN DER, Stelt; Jgc, Verheij; R., Speller; A., Galbiati; F., Psomadellis; R., Turchetta; S., Theodoridis; G., Hall; Bs, Avset; Fa, Triantis; Longo, Renat

Characterisation of the components of a prototype scanning intelligent imaging system for use in digital mammography: The I-ImaS system

The physical performance characteristics of a prototype scanning digital mammography (DM) system have been investigated. The I-ImaS system utilises CMOS MAPS technology promoting on-chip data processing; consequently statistical analysis is therefore achievable in real-time for the purpose of exposure modulation via a feedback mechanism during the image acquisition procedure. The imager employs a dual array of twenty CMOS APS sensing devices each individually coupled to a 100 μm thick thallium doped structured CsI scintillator. The x-ray performance of the sensors was characterised where the presampled modulation transfer function (MTF), normalised noise power spectrum (NNPS), and the detective quantum efficiency (DQE) was determined. The presampled MTF was measured utilising the slit technique and was found to be 0.1 at 6 lp/mm. The NNPS measured utilising a W/Al target/filter combination hardened with 38 mm PMMA was seen to decrease with increasing exposure as expected and the manifesting DQE was 0.30 at close to zero spatial frequency at an exposure of 1.75 mR. Preliminary image stitching of the individual steps acquired from the scanning system is presented. A conventionally acquired image that is without the implementation of beam modulation or off-line intelligence is compared and contrasted to an intelligently off-line processed image. Results indicate the implementation of real-time intelligence into the image acquisition phase of digital mammography is foreseeable. © 2006 IEEE

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 x 1350 array of active pixels on a 40m pitch fabricated in a 0.35m CMOS process. Stitching technology is employed to achieve an area of 5.4 cm x 5.4 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 x 10 3 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. © 2009 IEEE