Large area CMOS active pixel sensor x‐ray imager for digital breast tomosynthesis: Analysis, modeling, and characterization

Purpose: Large area x‐ray imagers based on complementary metal‐oxide‐semiconductor (CMOS) active pixel sensor (APS) technology have been proposed for various medical imaging applications including digital breast tomosynthesis (DBT). The low electronic noise (50–300 e−) of CMOS APS x‐ray imagers prov...

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Bibliographic Details
Published in:Medical physics (Lancaster) 2015-11, Vol.42 (11), p.6294-6308
Main Authors: Zhao, Chumin, Kanicki, Jerzy, Konstantinidis, Anastasios C., Patel, Tushita
Format: Article
Language:English
Subjects:
60 APPLIED LIFE SCIENCES
active pixel sensor
Biological material, e.g. blood, urine
Haemocytometers
biomedical equipment
Biomedical imaging
Biomedical instrumentation and transducers, including micro‐electro‐mechanical systems (MEMS)
BIOMEDICAL RADIOGRAPHY
Breast Neoplasms - diagnostic imaging
cascaded system analysis
CMOS image sensors
CMOS x‐ray detector
Computer Simulation
Computer-Aided Design
Contrast
diagnostic radiography
digital breast tomosynthesis
Digital computing or data processing equipment or methods, specially adapted for specific applications
dosimetry
Dosimetry/exposure assessment
Equipment Design
Equipment Failure Analysis
Female
Humans
Image data processing or generation, in general
Image sensors
Imager structures
KERMA
MAMMARY GLANDS
Mammography - instrumentation
Medical image noise
medical image processing
Medical X‐ray imaging
Metal insulator semiconductor structures
microcalcifications
Models, Theoretical
MONOCHROMATIC RADIATION
Noise
Photons
PITCHES
QUANTUM EFFICIENCY
RADIATION DOSES
Radiographic Image Enhancement - instrumentation
Reproducibility of Results
Scintigraphy
SEMICONDUCTOR MATERIALS
Semiconductors
Sensitivity and Specificity
SENSORS
SIMULATION
SYNCHROTRON RADIATION
SYSTEMS ANALYSIS
Transducers
TRANSFER FUNCTIONS
Transforming light or analogous information into electric information
X RADIATION
X‐ray detectors
X‐ray imaging
X‐rays
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Summary:Purpose: Large area x‐ray imagers based on complementary metal‐oxide‐semiconductor (CMOS) active pixel sensor (APS) technology have been proposed for various medical imaging applications including digital breast tomosynthesis (DBT). The low electronic noise (50–300 e−) of CMOS APS x‐ray imagers provides a possible route to shrink the pixel pitch to smaller than 75 μm for microcalcification detection and possible reduction of the DBT mean glandular dose (MGD). Methods: In this study, imaging performance of a large area (29 × 23 cm2) CMOS APS x‐ray imager [Dexela 2923 MAM (PerkinElmer, London)] with a pixel pitch of 75 μm was characterized and modeled. The authors developed a cascaded system model for CMOS APS x‐ray imagers using both a broadband x‐ray radiation and monochromatic synchrotron radiation. The experimental data including modulation transfer function, noise power spectrum, and detective quantum efficiency (DQE) were theoretically described using the proposed cascaded system model with satisfactory consistency to experimental results. Both high full well and low full well (LFW) modes of the Dexela 2923 MAM CMOS APS x‐ray imager were characterized and modeled. The cascaded system analysis results were further used to extract the contrast‐to‐noise ratio (CNR) for microcalcifications with sizes of 165–400 μm at various MGDs. The impact of electronic noise on CNR was also evaluated. Results: The LFW mode shows better DQE at low air kerma (Ka < 10 μGy) and should be used for DBT. At current DBT applications, air kerma (Ka ∼ 10 μGy, broadband radiation of 28 kVp), DQE of more than 0.7 and ∼0.3 was achieved using the LFW mode at spatial frequency of 0.5 line pairs per millimeter (lp/mm) and Nyquist frequency ∼6.7 lp/mm, respectively. It is shown that microcalcifications of 165–400 μm in size can be resolved using a MGD range of 0.3–1 mGy, respectively. In comparison to a General Electric GEN2 prototype DBT system (at MGD of 2.5 mGy), an increased CNR (by ∼10) for microcalcifications was observed using the Dexela 2923 MAM CMOS APS x‐ray imager at a lower MGD (2.0 mGy). Conclusions: The Dexela 2923 MAM CMOS APS x‐ray imager is capable to achieve a high imaging performance at spatial frequencies up to 6.7 lp/mm. Microcalcifications of 165 μm are distinguishable based on reported data and their modeling results due to the small pixel pitch of 75 μm. At the same time, potential dose reduction is expected using the studied CMOS APS x‐ray imager.
ISSN:0094-2405
2473-4209
DOI:10.1118/1.4932368