Computer Simulation of X-Ray Capillary Optics for Digital Mammography PDF Download
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Languages : en
Pages : 42
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Book Description
Polycapillary x-ray optics, arrays of hollow capillary tubes used to guide x-rays by total reflectance, are now being used in increasing numbers of applications, such as materials analysis, microelectronics manufacturing, x-ray astronomy and medical imaging. Because each optic contains hundreds of thousands of precisely shaped and located hollow channels, it is desirable to assess the feasibility of a variety of capillary geometries for a new application without physically constructing the optic. This assessment requires increasingly sophisticated modeling capability as new applications with more stringent requirements are developed. Previous analysis has shown that high-energy applications such as hard x-ray astronomy and medical imaging are particularly sensitive to optic profile errors such as channel waviness. A more physical model for surface waviness has been developed and included in optics simulations. The results are compared to measured data and to the results of other numerical simulation programs. Directed digital mammography can avail itself the advantages of digital processing, including tolerance to under- and over-exposure and image enhancement. In addition, a new technology, polycapillary optics, has been shown to produce clearer image by increasing contrast and resolution. Capillary optics, consisting a array of hollow glass tubes, is a relatively new technology for controlling x-ray beams. Thousands of individual capillary fiber can be strung together to form a multifiber optic. These arrays of curve polycapillary fiber can be used to focus, collimate, and filter x-ray radiation. A number of borrosilicate glass capillary fibers have been measured and simulated in the energy range 10-80 keV. The result shown potential for mammography applications, with transmission of 70% at 20 keV.
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Publisher:
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Category :
Languages : en
Pages : 42
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Book Description
Polycapillary x-ray optics, arrays of hollow capillary tubes used to guide x-rays by total reflectance, are now being used in increasing numbers of applications, such as materials analysis, microelectronics manufacturing, x-ray astronomy and medical imaging. Because each optic contains hundreds of thousands of precisely shaped and located hollow channels, it is desirable to assess the feasibility of a variety of capillary geometries for a new application without physically constructing the optic. This assessment requires increasingly sophisticated modeling capability as new applications with more stringent requirements are developed. Previous analysis has shown that high-energy applications such as hard x-ray astronomy and medical imaging are particularly sensitive to optic profile errors such as channel waviness. A more physical model for surface waviness has been developed and included in optics simulations. The results are compared to measured data and to the results of other numerical simulation programs. Directed digital mammography can avail itself the advantages of digital processing, including tolerance to under- and over-exposure and image enhancement. In addition, a new technology, polycapillary optics, has been shown to produce clearer image by increasing contrast and resolution. Capillary optics, consisting a array of hollow glass tubes, is a relatively new technology for controlling x-ray beams. Thousands of individual capillary fiber can be strung together to form a multifiber optic. These arrays of curve polycapillary fiber can be used to focus, collimate, and filter x-ray radiation. A number of borrosilicate glass capillary fibers have been measured and simulated in the energy range 10-80 keV. The result shown potential for mammography applications, with transmission of 70% at 20 keV.
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Category :
Languages : en
Pages : 72
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An extensive computer modeling for polycapillary optics that includes realistic models for the effects of profile defects shows good agreement with measured data. Measured polycapillary fiber transmission is in excess of 65% at 20 keV for borosilicate glass optics, and is in excess of 42% for short leaded glass optics. Measured high angle transmission which corresponds to scatter transmission is lower than 1% for 12 cm long borosilicate optics at 20 kev and less than 4% for 3 cm long leaded glass optics at 80 keV. A long prototype borosilicate magnifying tapered monolithic optic has demonstrated contrast enhancement due to removal of scatter transmission, while at the same time increasing the system MTF performance at all spatial frequencies. Computer modeling, measurement and defect studies have led to better manufacturing capabilities for monolithic optics. The newly magnifying monolithic optics have a high transmission efficiency. Multitaper optics have been produced and tested. Image analysis have provided the means for the image artifact analysis and reduction.
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Languages : en
Pages : 64
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The overall objective of this proposal is to develop a mammographic system with extremely high scatter rejection and dynamic range, good resolution and low patient dose. This will be accomplished by developing a direct x-ray detector interfaced with a capillary x-ray optic. Capillary x-ray optics, invented in the mid-eighties, provide an innovative new way to control x-ray beams. A number of promising geometries are being studied: collimating optics with long and short focal lengths, with and without antiscatter optics, monolithic linear magnifying tapers, and monolithic focusing, demagnifying optics. The collimating optics have transmissions in excess of 30% at their design energies, with collection angles ranging from 8 to 12 degrees. Scatter rejection is very high from al the optics. The linear tapers resulted in nearly ideal contrast enhancements and simultaneously increase in MTF at all spatial frequencies. The rapidly growing modeling capability has lead to improvements in the manufacturing processes. Direct digital detectors owe their high efficiency and resolution to the direct detection of x-ray photons without requiring phosphors for the conversion to visible light. One dimensional "imaging" was demonstrated with the CZT linear array. CID two-dimensional arrays with small pixel sizes are another promising new technology for mammography.
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Category :
Languages : en
Pages : 31
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Capillary optics, which use total external reflection to transmit x rays, have been proved to have great advantages in scatter reduction and resolution improvement in mammography application. The purpose of the proposed work is to perform lens simulation and image artifact elimination as part of the work of capillary optical mammography research. A lens simulation extended from the-previous single fiber simulation has been implemented, a lens for the protocol mammography system has been re-measured in an extended energy range and analyzed with the program. The simulation has been proved to be helpful in understanding the lens performance. Modulation Transfer Function (MTF) is the most fundamental measurement of spatial resolution used in radiology. Non-uniform transmission introduces difficulties in MTF measurement. A method to measure MTF by taking an edge image and processed with background reduction technique has been developed. The modeling capability has been extended and has lead to a real development of understanding of the nature of polycapillary defects, which is already leading to improvements in the manufacturing processes. Further, the increased confidence in the modeling allows future lens geometries to be effectively "tested" in simulation so that design parameters can be rapidly optimized.
Author: David George Kruger
Publisher:
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Category :
Languages : en
Pages : 270
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Category :
Languages : en
Pages : 0
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Results of extensive mammography screenings have shown the need for detection of breast cancer at earlier and more curable stages to have any significant impact on the mortality rate. While new imaging technologies for breast cancer diagnosis like magnetic resonance imaging, breast ultrasound and breast specific positron emission tomography are being developed, x%ray imaging continues to function as a convenient and economical choice for early detection.
Author: Carla D. Bradford
Publisher:
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Category :
Languages : en
Pages : 192
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Author: Ulrich Bick
Publisher: Springer Science & Business Media
ISBN: 3540784500
Category : Medical
Languages : en
Pages : 222
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Book Description
Digital Radiography has been ? rmly established in diagnostic radiology during the last decade. Because of the special requirements of high contrast and spatial resolution needed for roentgen mammography, it took some more time to develop digital m- mography as a routine radiological tool. Recent technological progress in detector and screen design as well as increased ex- rience with computer applications for image processing have now enabled Digital Mammography to become a mature modality that opens new perspectives for the diag- sis of breast diseases. The editors of this timely new volume Prof. Dr. U. Bick and Dr. F. Diekmann, both well-known international leaders in breast imaging, have for many years been very active in the frontiers of theoretical and translational clinical research, needed to bring digital mammography ? nally into the sphere of daily clinical radiology. I am very much indebted to the editors as well as to the other internationally rec- nized experts in the ? eld for their outstanding state of the art contributions to this v- ume. It is indeed an excellent handbook that covers in depth all aspects of Digital Mammography and thus further enriches our book series Medical Radiology. The highly informative text as well as the numerous well-chosen superb illustrations will enable certi? ed radiologists as well as radiologists in training to deepen their knowledge in modern breast imaging.
Author: Carmen Celeste Abreu
Publisher:
ISBN:
Category : Breast
Languages : en
Pages : 111
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Author:
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Category :
Languages : en
Pages : 0
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Collimated (parallel) beams can be used to remove scatter and improve resolution. Monochromatic x rays can be used to produce higher contrast images. Polycapillary x-ray optics technology can produce a highly parallel, monochromatic, x-ray beam from a conventional radiographic source. Two prototype collimating optics were characterized. The one with the higher transmission was used for monochromatic imaging. The transmission for prototype II optic with a focal distance of 250 mm was 37 % at 17.5 keV. The optic had good field uniformity and collected efficiently from a source up to 0.7 mm in diameter. The divergence of collimation was only 3.9 + 0.3 mrad. This shows the efficiency with which the beam can be monochromatized. These data were verified with computer simulations of ideal collimating optics. The contrast results agreed with the theoretical calculations at 8 keV. The monochromatic values are on the average 5 times higher than the polychromatic case. At mammographic energies, 20 keV, the expected contrast enhancement is 2.0 for 60 mm thick phantoms in addition to the contrast enhancement achieved from scatter reduction. The high contrast achievable with monochromatic parallel beam imaging has thus been demonstrated with a conventional source.
