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A schematic of the pixel array arrangement(left). Red circles represent the large size diodes placed at 100 µm pitch (Pixels). Cyan circles represent the small size diodes placed at 50 µm pitch (Sub-Pixels). A block diagram of the internal architecture of the DynAMITe detector (left).
Source publication
In many biomedical imaging applications Flat Panel Imagers (FPIs) are currently the most common option. However, FPIs possess several key drawbacks such as large pixels, high noise, low frame rates, and excessive image artefacts. Recently Active Pixel Sensors (APS) have gained popularity overcoming such issues and are now scalable up to wafer size...
Contexts in source publication
Context 1
... each cell of the DynAMITe matrix is fitted with multiple diodes: four diodes of small size (50 µm side), referred to as Sub-Pixels, and one diode of large size (100 µm side), referred to as Pixel. The whole matrix comprises 1260 ×1280 Pixels and 2520 × 2560 Sub-Pixels (see figure 2 (left)). Each light-converting element is designed in a standard 3-T architecture [9], allowing a reasonably high Fill Factor (70%) and Quantum Efficiency (QE) estimated as 45% for 523 nm light. ...
Context 2
... these design choices the DynAMITe detector represents a new type of active image sensor capable of simultaneous low noise and high resolution, due to the Sub-Pixels, and a high dynamic range with a low noise due to the Pixels. A block diagram of the sensor is shown in figure 2 (right) where four independent read out circuits (addressing and decoders) are shown. In fact the readout, performed on a column parallel basis, is designed with two independent readout circuits for both small and large diodes matrices to perform dual readout addressing for each diode. ...
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Citations
... To overcome these drawbacks, active pixel sensors came into the picture and received good fame by having features like low noise, high frame rate, and high pixel resolution, low power consumption, and low manufacturing cost. Esposito et al. [46] developed a new radiation-hard monolithic active pixel sensor called (Dynamic range Adjustable for Medical Imaging Technology) DynAMITe. This imager consists of two separate resolutions with different saturation performances and different noise in the same pixel array. ...
... It is available at an affordable price, which is disposable and recyclable, but the system is very slow and limited to non-fluorescence imaging. DynAMITe [46] has two-side buttable technology with two different pixel sizes, which yields more pixel size imager in biomedical imaging. It offers high frame rates and high spatial resolution. ...
According to the Center for Disease Control and Prevention (CDC), the average human life expectancy is 78.8 years. Specifically, 3.2 million deaths are reported yearly due to heart disease, cancer, Alzheimer’s disease, diabetes, and COVID-19. Diagnosing the disease is mandatory in the current way of living to avoid unfortunate deaths and maintain average life expectancy. CMOS image sensor (CIS) became a prominent technology in assisting the monitoring and clinical diagnosis devices to treat diseases in the medical domain. To address the significance of CMOS image ‘sensors’ usage in disease diagnosis systems, this paper focuses on the CIS incorporated disease diagnosis systems related to vital organs of the human body like the heart, lungs, brain, eyes, intestines, bones, skin, blood, and bacteria cells causing diseases. This literature survey’s main objective is to evaluate the ‘systems’ capabilities and highlight the most potent ones with advantages, disadvantages, and accuracy, that are used in disease diagnosis. This systematic review used PRISMA workflow for study selection methodology, and the parameter-based evaluation is performed on disease diagnosis systems related to the human body’s organs. The corresponding CIS models used in systems are mapped organ-wise, and the data collected over the last decade are tabulated.
... An in-depth description of the background is given in sec- [114]. The quantum efficiency of the sensor was measured by others for green light (wavelength of 523 nm) and was found to be 45% (64% including a fill factor of 70%) [115]. The quantum efficiency at the peak wavelength of the scintillation spectrum is not known. ...
... Those stitch blocks represent the maximum sub-unit of a composed CMOS sensor. The resulting noise pattern is also called Fixed-Pattern Noise (FPN)[115]. The top sub-figure within figure 3.8 reveals a cluster of about twenty faulty pixels which is intercepted by a faulty pixel column near column number 400. ...
Particle beam therapy (PBT) is a form of radiation therapy that is used for cancer treatment. Recently, interest in scintillator-based detectors for the measurement of depth-dose curves of therapeutic particle beams has been growing. In this work, a novel range telescope based on plastic scintillator and read out by a large-scale CMOS image sensor is presented. The detector is made of a stack of 49 plastic scintillator sheets with a thickness of 2–3mm and a transverse area of 100 times 100mm2. A novel Bragg curve model that incorporates scintillator quenching effects was developed for the beam range reconstruction from depth-light curves with low depthresolution. Measurements to characterise the performance of the detector were carried out at three different PBT centres across Europe. The maximum difference between the measured proton range and the reference range was found to be 0.46 mm. An evaluation of the radiation hardness proved that the range reconstruction algorithm is robust following the deposition of 6,300 Gy peak dose into the detector. Variations in the beam spot size, the transverse beam position and the beam intensity were shown to have a negligible effect on the range reconstruction accuracy. Range measurements of helium, carbon and oxygen ion beams were also performed. A novel technique for online range verification based on a mixed helium/ carbon ion beam and the range telescope was investigated. The helium beam range modulation by a narrow air gap of 1mm thickness in a plastic phantom that affected less than a quarter of the beam particles was detected, demonstrating the outstanding sensitivity of the mixed-beam technique. Using two anthropomorphic pelvis phantoms it was shown that small rotations of the phantom as well as simulated bowel gas movements cause detectable range changes. The future prospects and limitations of the helium-carbon mixing as well as its technical feasibility are discussed.
... A CMOS Active Pixel Sensor, named DynAMITe, whose performance for proton imaging has been extensively studied both with experimental data [23][24][25] and simulations [29], has been used to compare the response of the PRaVDA CMOS sensors for individual proton imaging. Details of the sensor architecture, electro-optical performance and radiation hardness are reported elsewhere [19,22,28]. Electro-optical performance parameters for this sensor are reported in table 2, for comparison with the PRaVDA CMOS APSs. ...
There is an increased interest in developing imaging systems in proton therapy, with the aim of reducing range uncertainty in treatment planning, assisting in patient positioning and verifying anatomical changes at the time of the treatment. Recently, the PRaVDA collaboration has developed two different solid-state detector technologies for imaging in proton therapy: Silicon Strip Detectors and CMOS Active Pixel Sensors (APSs). This paper reports on the design and optimisation process of the PRaVDA CMOS APSs. Optimisation of parameters, such as epitaxial thickness and resistivity, and performance for individual proton detection and proton radiography are reported.
... Complementary metal-oxide semiconductor (CMOS) x-ray detectors offer a compelling alternative to a-Si:H FPDs for such high-resolution applications, owing to their higher readout speed, up to 10× lower electronic noise, and finer pixel pitch (~0.05-0.1 mm). [33][34][35][36] In the recent years, CMOS detectors emerged as an attractive option for indirect detection xray detectors. Early interest in medical applications of CMOS sensors has been primarily focused on breast imaging. ...
Purpose:
Quantitative assessment of trabecular bone microarchitecture in extremity cone-beam CT (CBCT) would benefit from the high spatial resolution, low electronic noise, and fast scan time provided by complementary metal-oxide semiconductor (CMOS) x-ray detectors. We investigate the performance of CMOS sensors in extremity CBCT, in particular with respect to potential advantages of thin (<0.7 mm) scintillators offering higher spatial resolution.
Methods:
A cascaded systems model of a CMOS x-ray detector incorporating the effects of CsI:Tl scintillator thickness was developed. Simulation studies were performed using nominal extremity CBCT acquisition protocols (90 kVp, 0.126 mAs/projection). A range of scintillator thickness (0.35-0.75 mm), pixel size (0.05-0.4 mm), focal spot size (0.05-0.7 mm), magnification (1.1-2.1) and dose (15-40 mGy) was considered. Detectability index was evaluated for both CMOS and a-Si:H flat-panel detector (FPD) configurations for a range of imaging tasks emphasizing spatial frequencies associated with feature size aobj Experimental validation was performed on a CBCT test-bench in the geometry of a compact orthopedic CBCT system (SAD = 43.1 cm, SDD = 56.0 cm, matching that of the Carestream OnSight 3D system). The test-bench studies involved a 0.3 mm focal spot x-ray source and two CMOS detectors (Dalsa Xineos-3030HR, 0.099 mm pixel pitch) - one with the standard CsI:Tl thickness of 0.7 mm (C700) and one with a custom 0.4 mm thick scintillator (C400). Measurements of modulation transfer function (MTF), detective quantum efficiency (DQE), and CBCT scans of a cadaveric knee (15 mGy) were obtained for each detector.
Results:
Optimal detectability for high-frequency tasks (feature size of ~0.06 mm, consistent with the size of trabeculae) was ~4x for the C700 CMOS detector compared to the a-Si:H FPD at nominal system geometry of extremity CBCT. This is due to ~5x lower electronic noise of a CMOS sensor, which enables input quantum-limited imaging at smaller pixel size. Optimal pixel size for high-frequency tasks was <0.1 mm for a CMOS, compared to ~ 0.14mm for an a-Si:H FPD. For this fine pixel pitch, detectability of fine features could be improved by using a thinner scintillator to reduce light spread blur. A 22% increase in detectability of 0.06 mm features was found for the C400 configuration compared to C700. An improvement in the frequency at 50% modulation (f50 ) of MTF was measured, increasing from 1.8 lp/mm for C700 to 2.5 lp/mm for C400. The C400 configuration also achieved equivalent or better DQE as C700 for frequencies above ~2 mm(-1) . Images of cadaver specimens confirmed improved visualization of trabeculae with the C400 sensor.
Conclusions:
The small pixel size of CMOS detectors yields improved performance in high-resolution extremity CBCT compared to a-Si:H FPDs, particularly when coupled with a custom 0.4 mm thick scintillator. The results indicate that adoption of a CMOS detector in extremity CBCT can benefit applications in quantitative imaging of trabecular microstructure in humans. This article is protected by copyright. All rights reserved.
... For the purposes of this study, only Sub-Pixels are considered. A more detailed description of the pixel architecture, read out modalities and electro-optical performance are reported in [7][8][9]. ...
Geant4 is an object-oriented toolkit for the simulation of the interaction of particles and radiation with matter. It provides a snapshot of the state of a simulated particle in time, as it travels through a specified geometry. One important area of application is the modelling of radiation detector systems. Here, we extend the abilities of such modelling to include charge transport and sharing in pixelated CMOS Active Pixel Sensors (APSs); though similar effects occur in other pixel detectors. The CMOS APSs discussed were developed in the framework of the PRaVDA consortium to assist the design of custom sensors to be used in an energy-range detector for proton Computed Tomography (pCT). The development of ad-hoc classes, providing a charge transport model for a CMOS APS and its integration into the standard Geant4 toolkit, is described. The proposed charge transport model includes, charge generation, diffusion, collection, and sharing across adjacent pixels, as well as the full electronic chain for a CMOS APS. The proposed model is validated against experimental data acquired with protons in an energy range relevant for pCT.
... High performance x-ray detectors based on the complementary metal-oxide-semiconductor (CMOS) active pixel sensor (APS) have been recently studied for digital breast tomosynthesis (DBT) (Naday et al 2010, Choi et al 2012, Patel et al 2012, Park et al 2014, Zhao et al 2015a, 2015b, Kim et al 2016, Peters et al 2016. In comparison to conventional DBT systems based on amorphous silicon (a-Si:H) thin-film transistor (TFT) passive pixel sensor (PPS), the advantages of CMOS APS detectors are the smaller pixel pitch (40-75 µm), low electronic noise (50-165 e − ) and faster frame rate (20-30 fps) (Bohndiek et al 2009, Esposito et al 2011, Konstantinidis et al 2013. The high pixel resolution and low noise floor of CMOS APS detectors improves the two-dimensional (2D) imaging performance in compariso n to a-Si:H TFT PPS detectors especially in high spatial frequency range (above 5 mm −1 ) (Choi et al 2012, Patel et al 2012, Zhao et al 2015a, 2015b, Peters et al 2016. ...
... The wafer-scale (12.8 cm × 13.1 cm) x-ray detector used in this study (named DynAMITe: Dynamic Range Adjustable for Medical Imaging Technology) is based on a three-transistor (3-T) CMOS APS pixel architecture (Esposito et al 2011, Konstantinidis et al 2012a. DynAMITe can operate both in a high dynamic range (68 dB), full pixel mode (P mode, 100 µm pixel pitch) and a low dynamic range (65 dB), subpixel mode (SP mode, 50 µm pixel pitch). ...
High-resolution, low-noise x-ray detectors based on the complementary metal-oxide-semiconductor (CMOS) active pixel sensor (APS) technology have been developed and proposed for digital breast tomosynthesis (DBT). In this study, we evaluated the three-dimensional (3D) imaging performance of a 50 ��m pixel pitch CMOS APS x-ray detector named DynAMITe (Dynamic Range Adjustable for Medical Imaging Technology). The two-dimensional (2D) angle-dependent modulation transfer function (MTF), normalized noise power spectrum (NNPS), and detective quantum efficiency (DQE) were experimentally characterized and modeled using the cascaded system analysis at oblique incident angles up to 30��. The cascaded system model was extended to the 3D spatial frequency space in combination with the filtered back-projection (FBP) reconstruction method to calculate the 3D and in-plane MTF, NNPS and DQE parameters. The results demonstrate that the beam obliquity blurs the 2D MTF and DQE in the high spatial frequency range. However, this effect can be eliminated after FBP image reconstruction. In addition, impacts of the image acquisition geometry and detector parameters were evaluated using the 3D cascaded system analysis for DBT. The result shows that a wider projection angle range (e.g. ��30��) improves the low spatial frequency (below 5 mm-1) performance of the CMOS APS detector. In addition, to maintain a high spatial resolution for DBT, a focal spot size of smaller than 0.3 mm should be used. Theoretical analysis suggests that a pixelated scintillator in combination with the 50 ��m pixel pitch CMOS APS detector could further improve the 3D image resolution. Finally, the 3D imaging performance of the CMOS APS and an indirect amorphous silicon (a-Si:H) thin-film transistor (TFT) passive pixel sensor (PPS) detector was simulated and compared.
... The dynamic range of a CIS-based imaging system can be evaluated from the ratio of the MFWC and the MRN as follows; DR = 20 log (MFWC/MRN). Figure 3 shows the measured PTC of the fabricated CIS from which major electro-optical parameters mentioned in the above were estimated and listed in the table 2 together with those of Dexela 2923 [15] and DynAMITe sensors [16]. As we see in the table 2, compared with the Dexala 2923 and the DynAMITe sensors, the measured G_ADC from the extrapolation of the shot noise is much larger, and the absolute value of the read and shot noise are much smaller. ...
A CMOS image sensor (CIS) with a large area for the high resolution X-ray imaging was designed. The sensor has an active area of 125 × 125 mm² comprised with 2304 × 2304 pixels and a pixel size of 55 × 55 μm². First batch samples were fabricated by using an 8 inch silicon CMOS image sensor process with a stitching method. In order to evaluate the performance of the first batch samples, the electro-optical test and the X-ray test after coupling with an image intensifier screen were performed. The primary results showed that the performance of the manufactured sensors was limited by a large stray capacitance from the long path length between the analog multiplexer on the chip and the bank ADC on the data acquisition board. The measured speed and dynamic range were limited up to 12 frame per sec and 55 dB respectively, but other parameters such as the MTF, NNPS and DQE showed a good result as designed. Based on this study, the new X-ray CIS with ~ 50 μm pitch and ~ 150 cm² active area are going to be designed for the high resolution X-ray NDT equipment for semiconductor and PCB inspections etc.
... CMOS APS detectors overcome the drawbacks of conventional detectors by using a pixel amplifier that effectively reduces the noise floor (Fossum 1995, El Gamal andEltoukhy 2005). During the past few years, large area CMOS APS x-ray imagers with small pixel pitches ranging from 40 to 75 μm, low electronic noise of 50-165 e − , dynamic range of 63-69 dB, fast frame rate of 20-30 fps have been developed (Bohndiek et al 2009, Konstantinidis et al 2013, Esposito et al 2011. Specifically, the 2D projection image quality of a CMOS APS x-ray imager with a 75 μm pixel pitch (Dexela 2923 MAM) has been intensively evaluated for breast imaging applications such as mammography and digital breast tomosynthesis (DBT) (Choi et al 2012, Konstantinidis et al 2012a, Patel et al 2012. ...
... Technical details on this detector will be discussed in section 2.1. Fundamental electro-optical properties of the DynAMITe x-ray detector were previously investigated (Esposito et al 2011(Esposito et al , 2014. Konstantinidis et al (2012b) show that a high contrast-to-noise ratio (CNR) and acceptable contrast-detail performance for mammography application can be achieved using the DynAMITe x-ray detector. ...
... The wafer scale (12.8 × 13.1 cm 2 ) DynAMITe CMOS APS x-ray detector was fabricated using the standard 0.35 μm CMOS technology (Scheffer 2007). Since the detector is two-side buttable, a 2 × 2 tiling of sub-detectors can cover a large area of 25.6 × 26.2 cm 2 suitable for DBT application (Esposito et al 2011). ...
Wafer-scale CMOS active pixel sensors (APSs) have been developed recently for x-ray imaging applications. The small pixel pitch and low noise are very promising properties for medical imaging applications such as digital breast tomosynthesis (DBT). In this work, we evaluated experimentally and through modeling the imaging properties of a 50 μm pixel pitch CMOS APS x-ray detector named DynAMITe (Dynamic Range Adjustable for Medical Imaging Technology). A modified cascaded system model was developed for CMOS APS x-ray detectors by taking into account the device nonlinear signal and noise properties. The imaging properties such as modulation transfer function (MTF), noise power spectrum (NPS), and detective quantum efficiency (DQE) were extracted from both measurements and the nonlinear cascaded system analysis. The results show that the DynAMITe x-ray detector achieves a high spatial resolution of 10 mm(-1) and a DQE of around 0.5 at spatial frequencies <1 mm(-1). In addition, the modeling results were used to calculate the image signal-to-noise ratio (SNRi) of microcalcifications at various mean glandular dose (MGD). For an average breast (5 cm thickness, 50% glandular fraction), 165 μm microcalcifications can be distinguished at a MGD of 27% lower than the clinical value (~1.3 mGy). To detect 100 μm microcalcifications, further optimizations of the CMOS APS x-ray detector, image aquisition geometry and image reconstruction techniques should be considered.
... 12 The advantages of CMOS APS technology over PPS are (i) small pixel pitch (25-100 µm), (ii) low electronic noise (50-300 e − ), (iii) fast frame rate [up to 30 frames per second (fps)], and (iv) full circuit integration. 13,14 In the past few years, wafer scale (∼10 cm) CMOS APS arrays have been developed for medical imaging applications. [14][15][16][17] A number of wafer scale CMOS APS arrays can be tiled together to achieve a large detector area with the dimension of ∼20 × 30 cm 2 that is suitable for digital mammography and DBT. ...
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).
... The DynAMITe CMOS APS [10,11], an imaging detector designed for bio-medical applications, was used for the experiments described in this paper. DynAMITe was fabricated in a standard, incorporating radiation hardness by design, 0.18 µm CMOS technology using reticle stitching [12], covering a total active area of 12.8 × 13.1 cm 2 . ...
Since the first proof of concept in the early 70s, a number of technologies has been proposed to perform proton CT (pCT), as a means of mapping tissue stopping power for accurate treatment planning in proton therapy. Previous prototypes of energy-range detectors for pCT have been mainly based on the use of scintillator-based calorimeters, to measure proton residual energy after passing through the patient. However, such an approach is limited by the need for only a single proton passing through the energy-range detector in a read-out cycle. A novel approach to this problem could be the use of pixelated detectors, where the independent read-out of each pixel allows to measure simultaneously the residual energy of a number of protons in the same read-out cycle, facilitating a faster and more efficient pCT scan.
This paper investigates the suitability of CMOS Active Pixel Sensors (APSs) to track individual protons as they go through a number of CMOS layers, forming an energy-range telescope. Measurements performed at the iThemba Laboratories will be presented and analysed in terms of correlation, to confirm capability of proton tracking for CMOS APSs.
