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University of Michigan
1.
Sawant, Amit.
High quantum efficiency segmented detectors for megavoltage x -ray imaging using indirect detection active matrix flat panel imagers.
Degree: PhD, Biomedical engineering, 2006, University of Michigan
URL: http://hdl.handle.net/2027.42/125874 
► Electronic portal imaging devices (EPIDs) based on indirect-detection, active matrix flat panel imagers (AMFPIs) have become the technology of choice for geometric verification of patient…
(more)
▼ Electronic portal imaging devices (EPIDs) based on indirect-detection, active matrix flat panel imagers (AMFPIs) have become the technology of choice for geometric verification of patient localization and dose delivery in external beam radiotherapy. However, the imaging performance of current AMFPI EPIDs is severely limited by the fact that these devices are based on relatively thin, powdered-phosphor screens that make use of only ∼2% of the incident radiation. This work reports on the investigation of a highly efficient form of EPID based on a 2D matrix of thick, optically-isolated, scintillating elements that are dimensionally matched to the pixels of an underlying active matrix array. Two types of such segmented detector designs were explored, segmented phosphors and segmented crystals. Theoretical calculations based on cascaded systems modeling and Monte Carlo simulations were performed to estimate the upper limits of imaging performance, as quantified by the frequency-dependent detective quantum efficiency (DQE), for a variety of detector configurations. Engineering prototypes of segmented phosphor and crystal detectors were fabricated and empirical characterization of imagers incorporating these detectors was performed to determine x-ray sensitivity, modulation transfer function, noise power spectrum, and DQE under radiotherapy imaging conditions. Segmented phosphor-based imagers achieved ∼3 times higher x-ray quantum efficiency compared to a conventional EPID, while exhibiting comparable MTF and zero-frequency DQE. However, the DQE performance of these prototype imagers at higher spatial frequencies was significantly lower than the conventional imager. In the case of segmented crystals, a prototype based on a 40 mm thick CsI(Tl) detector, corresponding to a quantum efficiency of ∼55%, exhibited significantly superior DQE compared to the conventional imager across all spatial frequencies, with a zero-frequency DQE of ∼22% (compared to ∼1% for the conventional imager). Furthermore, Monte Carlo-based theoretical calculations indicate that, with further optimization, segmented crystal-based imagers could achieve DQE values up to 50%. It is anticipated that the realization of such very high-DQE megavoltage imagers would enable the visualization of soft tissue structures at very low doses in megavoltage tomographic and projection imaging – a highly desirable goal for modern, image-guided radiotherapy.
Advisors/Committee Members: Antonuk, Larry E. (advisor).
Subjects/Keywords: Active; Detection; Flat Panel Imagers; High; Indirect; Matrix; Megavoltage X-ray Imaging; Quantum Efficiency; Segmented Detectors; Using
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APA (6th Edition):
Sawant, A. (2006). High quantum efficiency segmented detectors for megavoltage x -ray imaging using indirect detection active matrix flat panel imagers. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/125874
Chicago Manual of Style (16th Edition):
Sawant, Amit. “High quantum efficiency segmented detectors for megavoltage x -ray imaging using indirect detection active matrix flat panel imagers.” 2006. Doctoral Dissertation, University of Michigan. Accessed January 20, 2021.
http://hdl.handle.net/2027.42/125874.
MLA Handbook (7th Edition):
Sawant, Amit. “High quantum efficiency segmented detectors for megavoltage x -ray imaging using indirect detection active matrix flat panel imagers.” 2006. Web. 20 Jan 2021.
Vancouver:
Sawant A. High quantum efficiency segmented detectors for megavoltage x -ray imaging using indirect detection active matrix flat panel imagers. [Internet] [Doctoral dissertation]. University of Michigan; 2006. [cited 2021 Jan 20].
Available from: http://hdl.handle.net/2027.42/125874.
Council of Science Editors:
Sawant A. High quantum efficiency segmented detectors for megavoltage x -ray imaging using indirect detection active matrix flat panel imagers. [Doctoral Dissertation]. University of Michigan; 2006. Available from: http://hdl.handle.net/2027.42/125874
2.
Wang, Yi.
High Detective Quantum Efficiency Electronic Portal Imaging Devices Based on Segmented Crystalline Scintillators and Mercuric Iodide Photoconductors.
Degree: PhD, Biomedical Engineering, 2009, University of Michigan
URL: http://hdl.handle.net/2027.42/63728
► Electronic portal imaging devices (EPIDs) based on active matrix, flat-panel imagers (AMFPIs) have been widely used for patient set-up verification in radiotherapy, and are being…
(more)
▼ Electronic portal imaging devices (EPIDs) based on active matrix, flat-panel imagers (AMFPIs) have been widely used for patient set-up verification in radiotherapy, and are being investigated for megavoltage (MV) cone-beam computed tomography (CBCT). However, the performance of conventional AMFPI-based EPIDs is limited by their relatively low detective quantum efficiency (DQE) at radiotherapy energies, ~1% for 6 MV X rays. Consequently, MV CBCT carried out with these inefficient EPIDs requires impractically high doses to achieve soft-tissue visualization. In order to significantly improve DQE, this research work examined thick mercuric iodide (HgI2) photoconductors in the form of particle in binder (PIB) and thick, segmented scintillators consisting of 2D matrices of scintillating crystals separated by septal walls.
Through simulation of radiation transport, quantum efficiency (QE), modulation transfer function (MTF) and DQE were studied as a function of the thickness of PIB-HgI2 photoconductors. Simulations of radiation and optical transport were carried out to investigate how various geometric and optical properties affect the DQE for segmented CsI:Tl and BGO scintillators. Four prototype EPIDs, employing three CsI:Tl scintillators (11.4, 25.6 and 40.0 mm thick) and one BGO scintillator (11.3 mm thick), were evaluated using a 6 MV photon beam. Finally, the potential MV CBCT performance provided by segmented scintillators was investigated by simulation of radiation transport.
Compared to conventional EPIDs, PIB-HgI2 photoconductors up to 6 mm thick have the potential to provide up to a factor of ~5 improvement in DQE. Segmented CsI:Tl and BGO scintillators up to 40 mm thick can provide DQE improvement of up to a factor of ~29 and 42, respectively, through optimization of optical properties. The three CsI:Tl prototypes demonstrated DQE improvement of up to a factor of ~25 at low spatial frequencies, while the BGO prototype exhibited an improvement of a factor of ~20 at zero frequency and over a factor of ~10 at the Nyquist frequency. The simulation results indicate that CsI:Tl and BGO scintillators up to 40 mm thick can provide dose reduction for MV CBCT of up to a factor of ~51 and 59, respectively, creating the possibility of providing soft-tissue visualization at clinically acceptable doses.
Advisors/Committee Members: Antonuk, Larry E. (committee member), Rogers, W. Leslie (committee member), Clarke, Roy (committee member), Clinthorne, Neal H. (committee member).
Subjects/Keywords: Active Matrix, Flat-panel Imager; Electronic Portal Imaging Devices; Megavoltage Cone-beam CT; Segmented Crystalline Scintillators;
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APA (6th Edition):
Wang, Y. (2009). High Detective Quantum Efficiency Electronic Portal Imaging Devices Based on Segmented Crystalline Scintillators and Mercuric Iodide Photoconductors. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/63728
Chicago Manual of Style (16th Edition):
Wang, Yi. “High Detective Quantum Efficiency Electronic Portal Imaging Devices Based on Segmented Crystalline Scintillators and Mercuric Iodide Photoconductors.” 2009. Doctoral Dissertation, University of Michigan. Accessed January 20, 2021.
http://hdl.handle.net/2027.42/63728.
MLA Handbook (7th Edition):
Wang, Yi. “High Detective Quantum Efficiency Electronic Portal Imaging Devices Based on Segmented Crystalline Scintillators and Mercuric Iodide Photoconductors.” 2009. Web. 20 Jan 2021.
Vancouver:
Wang Y. High Detective Quantum Efficiency Electronic Portal Imaging Devices Based on Segmented Crystalline Scintillators and Mercuric Iodide Photoconductors. [Internet] [Doctoral dissertation]. University of Michigan; 2009. [cited 2021 Jan 20].
Available from: http://hdl.handle.net/2027.42/63728.
Council of Science Editors:
Wang Y. High Detective Quantum Efficiency Electronic Portal Imaging Devices Based on Segmented Crystalline Scintillators and Mercuric Iodide Photoconductors. [Doctoral Dissertation]. University of Michigan; 2009. Available from: http://hdl.handle.net/2027.42/63728
3.
Liang, Albert.
Investigation of the Performance of Photon Counting Arrays Based on Polycrystalline Silicon Thin-Film Transistors.
Degree: PhD, Biomedical Engineering, 2018, University of Michigan
URL: http://hdl.handle.net/2027.42/144006
► Projection x-ray imaging is commonly employed to visualize internal human anatomy and used to produce diagnostic images. Modern projection imaging is typically performed using an…
(more)
▼ Projection x-ray imaging is commonly employed to visualize internal human anatomy and used to produce diagnostic images. Modern projection imaging is typically performed using an active matrix, flat panel imager that is comprised of a converter layer overlying a pixelated array. The images are formed by converting x-ray photons into electrical signals, and then integrating those signals over a frame time – a method referred to as fluence integration.
Recently, imagers employing a second method for creating x-ray images – referred to as photon counting – have been developed and used to perform mammographic imaging (a form of projection imaging). Photon counting involves measuring the energy of each interacting x-ray photon and storing digital counts of the number of photons exceeding one or more energy thresholds. Because the imaging information is stored digitally, photon counting imagers are less susceptible to noise than fluence-integrating imagers – which improves image quality and/or decreases the amount of radiation required to acquire an image.
Current photon counting mammographic imagers are based on crystalline silicon and are limited in detection area. In order to produce an image, the array is moved in a scanning motion across the object of interest. A photon counting imager with larger detection area would benefit other projection imaging modalities – such as radiography (which produces, for example, chest x-ray images) or fluoroscopy (which is used for non-invasively inserting stents and other medical devices). However, techniques to increase detection area, such as tiling multiple arrays, result in increased imager complexity or cost. For this reason, our group has been exploring the possibility of creating photon counting arrays using a different semiconductor material, referred to as polycrystalline silicon (poly-Si). This material is fabricated using a thin-film process, which allows the economic manufacture of monolithic, large-area arrays and has favorable material properties for creating complex, high speed circuits.
Using poly-Si, a set of prototype arrays have been designed and fabricated. The design of the arrays consists of four components: an amplifier, a comparator, a clock generator, and a counter. Several circuit variations were created for each component, and circuit simulations were performed in order to determine energy resolution and count rate values for each variation of each component.
For the amplifier component, all circuit variations were determined to have an energy resolution of ~10% when presented with a 70 keV input x-ray photon (a typical photon energy level used in diagnostic imaging). This energy resolution value is comparable to those reported for photon counting imagers fabricated using crystalline silicon. In addition, while count rate values for the amplifier component were roughly one order of magnitude too low for radiographic and fluoroscopic applications (which require count rates on the order of 1 million counts per second per square millimeter…
Advisors/Committee Members: Antonuk, Larry E (committee member), Fessler, Jeffrey A (committee member), Goodsitt, Mitchell M (committee member), Lam, Kwok Leung (committee member).
Subjects/Keywords: photon counting; circuit simulation; active matrix flat panel imager; polycrystalline silicon; energy resolution; count rate; Biomedical Engineering; Engineering
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APA (6th Edition):
Liang, A. (2018). Investigation of the Performance of Photon Counting Arrays Based on Polycrystalline Silicon Thin-Film Transistors. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/144006
Chicago Manual of Style (16th Edition):
Liang, Albert. “Investigation of the Performance of Photon Counting Arrays Based on Polycrystalline Silicon Thin-Film Transistors.” 2018. Doctoral Dissertation, University of Michigan. Accessed January 20, 2021.
http://hdl.handle.net/2027.42/144006.
MLA Handbook (7th Edition):
Liang, Albert. “Investigation of the Performance of Photon Counting Arrays Based on Polycrystalline Silicon Thin-Film Transistors.” 2018. Web. 20 Jan 2021.
Vancouver:
Liang A. Investigation of the Performance of Photon Counting Arrays Based on Polycrystalline Silicon Thin-Film Transistors. [Internet] [Doctoral dissertation]. University of Michigan; 2018. [cited 2021 Jan 20].
Available from: http://hdl.handle.net/2027.42/144006.
Council of Science Editors:
Liang A. Investigation of the Performance of Photon Counting Arrays Based on Polycrystalline Silicon Thin-Film Transistors. [Doctoral Dissertation]. University of Michigan; 2018. Available from: http://hdl.handle.net/2027.42/144006
4.
Liu, Langechuan.
Design Optimization Studies for Active Matrix Flat Panel Imagers Based on Segmented Crystalline Scintillators for Radiotherapy Imaging.
Degree: PhD, Physics, 2015, University of Michigan
URL: http://hdl.handle.net/2027.42/111394
► In this dissertation, a series of theoretical studies were performed using Monte Carlo simulation to optimize the design of active matrix flat panel imagers (AMFPIs)…
(more)
▼ In this dissertation, a series of theoretical studies were performed using Monte Carlo simulation to optimize the design of active matrix flat panel imagers (AMFPIs) based on segmented scintillators for radiotherapy imaging. The influence of imager design specifications (such as use of a focused geometry, as well as the physical size and optical properties of scintillator elements) on imaging performance at megavoltage (MV) energies has been systematically investigated.
The first study, involving simulation of radiation transport only, examined focused segmented scintillators as a potential solution to counter the detrimental effect of beam divergence. A focused planar geometry was found to effectively eliminate degradation in spatial resolution and detective quantum efficiency due to beam divergence, and to achieve uniform imaging performance across the entire detection area for thick, large-area, segmented scintillators.
The second study, which involved simulation of both radiation and optical transport using a novel hybrid modeling technique, was performed to examine the influence of optical effects on the imaging performance of segmented scintillators. Based on the theoretical examination of various scintillator designs, an optimization map, which takes into account contrast-to-noise ratio and spatial resolution performance, was generated to guide decision-making in scintillator design.
The final study explored the possibility of extending the clinical application of thick, segmented scintillators to include kilovoltage (kV) imaging using an extended hybrid modeling technique. A methodology was presented for identifying the most favorable design of a dual energy imager based on segmented scintillators. Such a design maintains the desirably high level of imaging performance at MV energies made possible by thick, segmented scintillators, while helping to provide performance comparable to that of commercial imagers at kV energies.
The studies presented in this dissertation, which build upon the results of earlier empirical and theoretical characterizations of engineering prototypes, provide valuable insight for the design of future prototypes. It is anticipated that, through careful design assisted by theoretical modeling and empirical measurements, AMFPIs based on segmented scintillators can provide significantly improved performance compared to that of existing imagers in the treatment room, thereby increasing the clinical utility of in-room kV and MV imaging.
Advisors/Committee Members: Antonuk, Larry E. (committee member), Balter, James M. (committee member), Becchetti Jr., Frederick D. (committee member), Gull, Emanuel (committee member), Kurdak, Cagliyan (committee member).
Subjects/Keywords: active matrix flat panel imagers; Monte Carlo simulation; segmented scintillators; medical imaging; Physics; Science
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APA (6th Edition):
Liu, L. (2015). Design Optimization Studies for Active Matrix Flat Panel Imagers Based on Segmented Crystalline Scintillators for Radiotherapy Imaging. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/111394
Chicago Manual of Style (16th Edition):
Liu, Langechuan. “Design Optimization Studies for Active Matrix Flat Panel Imagers Based on Segmented Crystalline Scintillators for Radiotherapy Imaging.” 2015. Doctoral Dissertation, University of Michigan. Accessed January 20, 2021.
http://hdl.handle.net/2027.42/111394.
MLA Handbook (7th Edition):
Liu, Langechuan. “Design Optimization Studies for Active Matrix Flat Panel Imagers Based on Segmented Crystalline Scintillators for Radiotherapy Imaging.” 2015. Web. 20 Jan 2021.
Vancouver:
Liu L. Design Optimization Studies for Active Matrix Flat Panel Imagers Based on Segmented Crystalline Scintillators for Radiotherapy Imaging. [Internet] [Doctoral dissertation]. University of Michigan; 2015. [cited 2021 Jan 20].
Available from: http://hdl.handle.net/2027.42/111394.
Council of Science Editors:
Liu L. Design Optimization Studies for Active Matrix Flat Panel Imagers Based on Segmented Crystalline Scintillators for Radiotherapy Imaging. [Doctoral Dissertation]. University of Michigan; 2015. Available from: http://hdl.handle.net/2027.42/111394
University of Michigan
5.
Boudry, John Moore.
Evaluation of hydrogenated amorphous silicon photodiodes and field-effect transistors for use as elements of two-dimensional x-ray imaging arrays.
Degree: PhD, Pure Sciences, 1996, University of Michigan
URL: http://hdl.handle.net/2027.42/129840
► Imaging arrays fabricated from hydrogenated amorphous silicon (a-Si:H) have shown great potential for application in radiotherapy and diagnostic x-ray imaging. One particular design of array…
(more)
▼ Imaging arrays fabricated from hydrogenated amorphous silicon (a-Si:H) have shown great potential for application in radiotherapy and diagnostic x-ray imaging. One particular design of array under development consists of a regular two-dimensional pattern of pixels, each pixel comprised of an a-Si:H photodiode, which indirectly detects the incident x-ray flux, and an a-Si:H field-effect transistor (FET), which allows readout of the charge information stored in the photodiode. Present-day arrays of this design allow real-time, digital x-ray imaging over a large area (i.
e., 25 x 25 cm) with resolution as high as ∼100 μm. A useful component in the development of such a-Si:H arrays is characterization of the properties of the individual devices which make up the arrays, namely the a-Si:H photodiode and FET. Device characterization helps determine the degree to which the arrays are viable for x-ray imaging applications and also enables optimization of array design and operation. In this thesis, measurements of the noise and radiation-damage properties of a-Si:H photodiodes and FETs are presented. Measurements were performed for devices of various design operated at voltages similar to those anticipated for array operation. For the noise properties, current-noise-power spectral density measurements were carried out. Such measurements enabled prediction of device spectral noise levels for arrays of various design and operational parameters. For the radiation-damage measurements, device signal and noise properties were examined as a function of dose using a
60Co (∼1.25 MeV) source to maximum cumulative doses of ∼2 × 10
4 Gy. Annealing of device properties affected by the radiation was also examined. It was generally concluded from the radiation-damage measurements that the devices exhibited the necessary radiation tolerance for x-ray imaging applications. In addition to the noise and radiation-damage measurements, a noise model for predicting the lower noise limit of an a-Si:H array is detailed. The model uses results from the device spectral noise measurements and predicts that for most x-ray imaging applications FET thermal noise will be the dominant noise source.
Advisors/Committee Members: Antonuk, Larry E. (advisor), Longo, Michael J. (advisor).
Subjects/Keywords: Amorphous; Arrays; Dimensional; Effect; Elements; Evaluation; Field; Hydrogenated; Imaging; Photodiodes; Ray; Silicon; Transistors; Two; Use
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APA (6th Edition):
Boudry, J. M. (1996). Evaluation of hydrogenated amorphous silicon photodiodes and field-effect transistors for use as elements of two-dimensional x-ray imaging arrays. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/129840
Chicago Manual of Style (16th Edition):
Boudry, John Moore. “Evaluation of hydrogenated amorphous silicon photodiodes and field-effect transistors for use as elements of two-dimensional x-ray imaging arrays.” 1996. Doctoral Dissertation, University of Michigan. Accessed January 20, 2021.
http://hdl.handle.net/2027.42/129840.
MLA Handbook (7th Edition):
Boudry, John Moore. “Evaluation of hydrogenated amorphous silicon photodiodes and field-effect transistors for use as elements of two-dimensional x-ray imaging arrays.” 1996. Web. 20 Jan 2021.
Vancouver:
Boudry JM. Evaluation of hydrogenated amorphous silicon photodiodes and field-effect transistors for use as elements of two-dimensional x-ray imaging arrays. [Internet] [Doctoral dissertation]. University of Michigan; 1996. [cited 2021 Jan 20].
Available from: http://hdl.handle.net/2027.42/129840.
Council of Science Editors:
Boudry JM. Evaluation of hydrogenated amorphous silicon photodiodes and field-effect transistors for use as elements of two-dimensional x-ray imaging arrays. [Doctoral Dissertation]. University of Michigan; 1996. Available from: http://hdl.handle.net/2027.42/129840
University of Michigan
6.
Siewerdsen, Jeffrey Harold.
Signal, noise, and detective quantum efficiency of amorphous-silicon:hydrogen flat-panel imagers.
Degree: PhD, Pure Sciences, 1998, University of Michigan
URL: http://hdl.handle.net/2027.42/131326
► Flat-panel imagers based upon the technology of thin-film amorphous silicon transistors and photodiodes are under investigation for a wide variety of medical imaging applications. This…
(more)
▼ Flat-panel imagers based upon the technology of thin-film amorphous silicon transistors and photodiodes are under investigation for a wide variety of medical imaging applications. This thesis presents quantitative empirical and theoretical investigations of the imaging performance of such imaging systems. Performance was evaluated in terms of imager signal size, spatial resolution, noise characteristics, and signal-to-noise ratio for a wide variety of imaging system configurations and exposure conditions relevant to medical imaging. A theoretical model based upon cascaded systems analysis allowed prediction of imager signal, noise, and detective quantum efficiency (DQE), and theoretical results were found to agree well with empirical measurements. The empirical and theoretical analyses yielded quantification of the performance of existing imager designs, allowed investigation of the potential performance of future flat-panel imaging systems, and provided a methodology for identifying optimal imager configurations for various applications and imaging tasks. There is every indication that flat-panel imagers could provide performance superior to that of existing clinical imaging technologies. For example, in general x-ray radiography, mammography, and radiotherapy portal imaging, such systems could provide DQE exceeding 60%, 80%, and 1.5%, respectively, approximately twice that of film-based systems. However, for applications involving very low exposures per image,
e.g., real-time fluoroscopy, such systems may suffer from reduced signal-to-noise ratio. The analyses developed in this thesis provide an effective means of identifying strategies for improved imager performance and will facilitate the realization of optimized flat-panel imagers that physically achieve their maximum theoretical performance.
Advisors/Committee Members: Antonuk, Larry E. (advisor), Longo, Michael J. (advisor).
Subjects/Keywords: Amorphous Silicon; Detective; Effici; Flat Panel Imagers; Hydrogen; Noise; Quantum Efficiency; Si; Signal
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APA (6th Edition):
Siewerdsen, J. H. (1998). Signal, noise, and detective quantum efficiency of amorphous-silicon:hydrogen flat-panel imagers. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/131326
Chicago Manual of Style (16th Edition):
Siewerdsen, Jeffrey Harold. “Signal, noise, and detective quantum efficiency of amorphous-silicon:hydrogen flat-panel imagers.” 1998. Doctoral Dissertation, University of Michigan. Accessed January 20, 2021.
http://hdl.handle.net/2027.42/131326.
MLA Handbook (7th Edition):
Siewerdsen, Jeffrey Harold. “Signal, noise, and detective quantum efficiency of amorphous-silicon:hydrogen flat-panel imagers.” 1998. Web. 20 Jan 2021.
Vancouver:
Siewerdsen JH. Signal, noise, and detective quantum efficiency of amorphous-silicon:hydrogen flat-panel imagers. [Internet] [Doctoral dissertation]. University of Michigan; 1998. [cited 2021 Jan 20].
Available from: http://hdl.handle.net/2027.42/131326.
Council of Science Editors:
Siewerdsen JH. Signal, noise, and detective quantum efficiency of amorphous-silicon:hydrogen flat-panel imagers. [Doctoral Dissertation]. University of Michigan; 1998. Available from: http://hdl.handle.net/2027.42/131326
University of Michigan
7.
Jee, Kyung-Wook.
Theoretical and empirical system performance of active matrix flat -panel imagers.
Degree: PhD, Biomedical engineering, 2002, University of Michigan
URL: http://hdl.handle.net/2027.42/132166
► Active matrix flat-panel imagers (AMFPIs) are large-area, digital x-ray imaging systems incorporating a thin-film-based flat-panel array. While such flat-panel imagers offer numerous advantages over other…
(more)
▼ Active matrix flat-panel imagers (AMFPIs) are large-area, digital x-ray imaging systems incorporating a thin-film-based flat-panel array. While such flat-panel imagers offer numerous advantages over other existing radiographic and fluoroscopic devices, it is important to quantify performance of these imagers objectively since such a performance assessment can aid to identify problems or weaknesses in the present technology thereby furthering the goal of achieving maximum theoretical performance. As an extension of our group's general approach to develop optimized designs, system performance of existing and hypothetical AMFPIs was evaluated theoretically and empirically for the applications of radiotherapy imaging, fluoroscopy, and mammography. This performance assessment was based on performance metrics such as x-ray sensitivity, spatial resolution (i.
e., MTF), noise characteristics (i.
e., NPS), and the transfer efficiency of signal-to-noise information (i.
e., DQE). Theoretical investigation was performed based on a linear systems model using a mathematical formalism called cascaded systems formalism. Furthermore, the theoretical model was used to examine the performance of existing imager designs as well as hypothetical designs incorporating a variety of strategies to overcome factors limiting the performance of the present AMPFI technology.
Advisors/Committee Members: Antonuk, Larry E. (advisor), Rogers, W. Leslie (advisor).
Subjects/Keywords: Active Matrix; Digital X-ray Imaging; Empirical; Flat-panel Imagers; Quantum Efficiency; System Performance; Theoretical
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APA (6th Edition):
Jee, K. (2002). Theoretical and empirical system performance of active matrix flat -panel imagers. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/132166
Chicago Manual of Style (16th Edition):
Jee, Kyung-Wook. “Theoretical and empirical system performance of active matrix flat -panel imagers.” 2002. Doctoral Dissertation, University of Michigan. Accessed January 20, 2021.
http://hdl.handle.net/2027.42/132166.
MLA Handbook (7th Edition):
Jee, Kyung-Wook. “Theoretical and empirical system performance of active matrix flat -panel imagers.” 2002. Web. 20 Jan 2021.
Vancouver:
Jee K. Theoretical and empirical system performance of active matrix flat -panel imagers. [Internet] [Doctoral dissertation]. University of Michigan; 2002. [cited 2021 Jan 20].
Available from: http://hdl.handle.net/2027.42/132166.
Council of Science Editors:
Jee K. Theoretical and empirical system performance of active matrix flat -panel imagers. [Doctoral Dissertation]. University of Michigan; 2002. Available from: http://hdl.handle.net/2027.42/132166
. 
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