Dose-efficient system for digital mammography

Danielsson, Mats; Bornefalk, Hans; Cederstroem, Bjoern; Chmill, V.; Hasegawa, B.H.; Lundqvist, Mats; Nygren, D. R.; Tabar, Tamas

doi:10.1117/12.384498

Cited by 16 publications

(10 citation statements)

References 10 publications

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“…The imaging system is said to be "quantum limited" [29,30]. With a pixel size of 50 µm (10 lp/mm), Sectra asserts that good quality imaging is obtained for 1/5 of the usual doses [34,35].…”

Section: Scanning Systemsmentioning

confidence: 99%

Digital detectors for mammography: the technical challenges

Noël¹,

Thibault

2004

Eur Radiol

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This paper reviews the different techniques available and competing for full-field digital mammography. The detectors are described in their principles: photostimulable storage phosphor plates inserted as a cassette in a conventional mammography unit, dedicated active matrix detectors (i.e., flat-panel, thin-film transistor-based detectors) and scanning systems, using indirect and direct X-ray conversion. The main parameters that characterize the performances of the current systems and influence the quality of digital images are briefly explained: spatial resolution, detective quantum efficiency and modulation transfer function. Overall performances are often the result of compromises in the choice of technology.

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Section: Scanning Systemsmentioning

confidence: 99%

Digital detectors for mammography: the technical challenges

Noël¹,

Thibault

2004

Eur Radiol

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“…Due to the recent advances in chip level multichannel detector electronics, faster and more powerful computers, and new detector technologies, photon counting x-ray imaging detectors have come closer to their practical realization. 16,32,33 In the present study, a photon counting detector based on MCP was developed and evaluated for x-ray imaging. The system has shown that the spatial resolution and noise are acceptable for medical x-ray imaging.…”

Section: Discussionmentioning

confidence: 99%

“…However, the count rate requirement can be satisfied using multichannel ASIC readout electronics, 32,33 where an independent amplifier-counter chain reads out each of the anode strips. This electronics has recently been developed for x-ray detectors based on semiconductors such as a-Si 16 and CdZnTl. 34 Currently, the pulse shaping time of the ASIC electronics can be as short as 50-100 ns, and count rate can reach up to 2 MHz/channel, with approximately 10% dead time.…”

Section: Discussionmentioning

confidence: 99%

“…The possibility of motion artifacts due to long image acquisition time has previously been investigated and shown to be insignificant. 13,14 A number of scanning slit x-ray imaging systems are currently under investigation for mammography 15,16 and general radiography. 17 Recently, we have reported the initial results for a scanning slit x-ray imaging system based on an ''edge-on'' MCP detector.…”

Section: Introductionmentioning

confidence: 99%

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Scanning‐slit photon counting x‐ray imaging system using a microchannel plate detector

Shikhaliev

Lê

et al. 2004

Medical Physics

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An experimental prototype of a novel photon counting x-ray imaging system was evaluated. This system is based on an "edge-on" microchannel plate (MCP) detector and utilizes scanning slit imaging configuration. The detector is capable of photon counting, direct conversion, high spatial resolution, controllable physical charge amplification, quantum limited and scatter free operation. The detector provides a 60 mm wide field of view (FOV) and its count rate is 200 kHz for the entire FOV. The count rate of the current system is limited by the position encoding electronics, which has a single input for all events from the entire detector, and incorporates a single channel ADC with 1 micros conversion time. It is shown that the count rate can potentially be improved to clinically acceptable levels using multichannel application specific integrated circuit (ASIC) electronics and multi-slit image acquisition geometry. For a typical acquisition time used in this study, the image noise was measured to be less than the typically acceptable noise level for medical x-ray imaging. It is anticipated that the noise level will be also low after the implementation of the ASIC electronics. The quantum efficiency of the detector was measured to be 40%-56% for an energy range of 50-90 kVp for MCPs used in this study and can be improved to > 80% using MCPs with the optimized parameters. Images of resolution and anthropomorphic phantoms were acquired at an x-ray tube voltage of 50 kVp. The value of contrast transfer function for the detector was measured to be 0.5 at a spatial frequency of 5 lp/mm. The intrinsic spatial resolution of the system is 28 microm FWHM and was limited by the accuracy of the time-to-digital conversion of the position encoding electronics. Given the advantages of the edge-on MCP detector such as direct conversion and physical charge amplification, it can potentially be applied to mammography and chest radiography.

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“…Photon-counting X-ray detectors applied to mammography and radiography have shown a dose reduction of 40% to 400% while maintaining sufficient contrast for these applications [4], [5]. Simulations have shown that photon-counting along with optimal energy weighting can increase dose efficiency up to 40% for digital mammography as compared to a conventional integrating system [6]. One group has reported that the lesion detection signal to noise ratio is significantly affected by the energy dependence of the detector’s quantum efficiency and the varying contrast carried by different energies in the beam spectrum [4].…”

Section: Introductionmentioning

confidence: 99%

Photon Counting Energy Dispersive Detector Arrays for X-ray Imaging

Iwanczyk

Nygård

Meirav³

et al. 2009

IEEE Trans. Nucl. Sci.

257

144

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The development of an innovative detector technology for photon-counting in X-ray imaging is reported. This new generation of detectors, based on pixellated cadmium telluride (CdTe) and cadmium zinc telluride (CZT) detector arrays electrically connected to application specific integrated circuits (ASICs) for readout, will produce fast and highly efficient photon-counting and energy-dispersive X-ray imaging. There are a number of applications that can greatly benefit from these novel imagers including mammography, planar radiography, and computed tomography (CT). Systems based on this new detector technology can provide compositional analysis of tissue through spectroscopic X-ray imaging, significantly improve overall image quality, and may significantly reduce X-ray dose to the patient. A very high X-ray flux is utilized in many of these applications. For example, CT scanners can produce ~100 Mphotons/mm2/s in the unattenuated beam. High flux is required in order to collect sufficient photon statistics in the measurement of the transmitted flux (attenuated beam) during the very short time frame of a CT scan. This high count rate combined with a need for high detection efficiency requires the development of detector structures that can provide a response signal much faster than the transit time of carriers over the whole detector thickness. We have developed CdTe and CZT detector array structures which are 3 mm thick with 16×16 pixels and a 1 mm pixel pitch. These structures, in the two different implementations presented here, utilize either a small pixel effect or a drift phenomenon. An energy resolution of 4.75% at 122 keV has been obtained with a 30 ns peaking time using discrete electronics and a 57Co source. An output rate of 6×106 counts per second per individual pixel has been obtained with our ASIC readout electronics and a clinical CT X-ray tube. Additionally, the first clinical CT images, taken with several of our prototype photon-counting and energy-dispersive detector modules, are shown.

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Dose-efficient system for digital mammography

Cited by 16 publications

References 10 publications

Digital detectors for mammography: the technical challenges

Digital detectors for mammography: the technical challenges

Scanning‐slit photon counting x‐ray imaging system using a microchannel plate detector

Photon Counting Energy Dispersive Detector Arrays for X-ray Imaging

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