Xeroradiography

Boag, J. W.

doi:10.1088/0031-9155/18/1/001

Cited by 105 publications

(37 citation statements)

References 41 publications

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“…The optimum thickness depends on the radiation energy and also on the charge transport parameters, µ e τ e and µ h τ h , as shown previously [25]. There are experiments reported in the past that clearly show that the X-ray sensitivity has a maximum as a function of photoconductor thickness [2,26].…”

Section: Stabilized A-sesupporting

confidence: 62%

“…For liquid development systems, introduced later, the a-Se thickness was 320 m. The surface of the a-Se layer was coated by a thin organic layer (e.g., cellulose acetate) for protection and for electrostatic charge retention. Xeroradiography produced high quality mammographic images, and enjoyed a special attribute, called edge enhancement, which amplified the contrast at object edges and thereby facilitated diagnosis [2][3][4]. Xerox Medical Systems was eventually closed and xeroradiography became obsolete by the mid-1990s.…”

Section: Feature Articlementioning

confidence: 99%

“…While the atomic number (34) for Se is not as high as some of the other X-ray photoconductors, it can, nonetheless, absorb X-rays, especially in the mammographic range. In the general radiology range, it is obviously less efficient in X-ray absorption than its high atomic number competitors such as HgI 2 and PbO. The X-ray photogeneration efficiency in a-Se depends strongly on the field.…”

Section: Stabilized A-sementioning

confidence: 99%

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Amorphous selenium and its alloys from early xeroradiography to high resolution X‐ray image detectors and ultrasensitive imaging tubes

Kasap¹,

Frey²,

Belev³

et al. 2009

Physica Status Solidi (b)

148

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We describe the progress in the science and technology of stabilized a‐Se from its early use in xerography and xeroradiography to its present use in commercial modern flat panel X‐ray imagers and ultrasensitive video tubes which utilize impact ionization of drifting holes. Both electrons and holes can drift in stabilized a‐Se, which is a distinct advantage since X‐ray photogeneration of charge carriers occurs throughout the bulk of the photoconductive layer. An a‐Se photoconductor has to be operated at high fields to ensure that the photogeneration efficiency is sufficiently large to provide reasonable X‐ray sensitivity. However, at high fields, the dark current is unacceptably large in simple metal/a‐Se/metal devices, and special multilayer device structures need to be designed. The dark current decays with time and increases with the nominal applied field. The reduction of the dark current to a tolerable level was one of the key factors that lead to the commercialization of a‐Se X‐ray detectors. We discuss the origin of the dark current, and highlight some of the current challenges in the design of next generation detectors. We also discuss the origin of impact ionization in a‐Se, and its fruitful utilization in ultrasensitive imaging devices, including the Harpicon, which are likely to lead to new high detective quantum efficiency detectors.

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Section: Stabilized A-sesupporting

confidence: 62%

Section: Feature Articlementioning

confidence: 99%

Section: Stabilized A-sementioning

confidence: 99%

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Amorphous selenium and its alloys from early xeroradiography to high resolution X‐ray image detectors and ultrasensitive imaging tubes

Kasap¹,

Frey²,

Belev³

et al. 2009

Physica Status Solidi (b)

148

View full text Add to dashboard Cite

show abstract

“…A-Se is also used as the x-ray photoconductor in a large area imaging system known as xeroradiography. 6 In xeroradiography an a-Se layer between 150 and 300 m thick is vacuum deposited onto an aluminum substrate typically 9.5ϫ14Љ ͑24.1ϫ35.6 cm͒. These layers are charged with gaseous ions and the readout uses toner in much the same manner as a photocopier.…”

Section: B A-sementioning

confidence: 99%

“…[3][4][5] Since that time, tremendous improvements have been made in the field of x-ray photoconductors, most notably with the photoconductor amorphous selenium ͑a-Se͒. 6 By incorporating these improved x-ray photoconductors into a large area vidicon, it should be possible to produce a device suitable for medical fluoroscopy. Thus the x-ray vidicon becomes an alternative to the XRII and television camera combination ͑XRII/TV͒.…”

Section: Introductionmentioning

confidence: 99%

Feasibility of a large area x‐ray sensitive vidicon for medical fluoroscopy: Signal and noise factors

Luhta

Rowlands

1997

Medical Physics

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A large area x-ray sensitive vidicon is being investigated as an alternative to the x-ray image intensifier and television camera combination for medical fluoroscopy. Signal generation in an x-ray vidicon involves an x-ray photoconductive layer whose surface is scanned by an electron beam. The single x-ray to electron conversion stage of the x-ray vidicon offers a greatly improved modulation transfer function (MTF) over the x-ray image intensifier. This superior MTF allows signal and x-ray quantum noise at high spatial frequencies to be passed to the preamplifier with less attenuation. In cardiac cine applications this would allow quantum noise limited operation at higher spatial frequencies than is possible with the x-ray image intensifier system.

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Mammography

Lin¹

2006

Encyclopedia of Medical Devices and Instrumentation

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X‐ray mammography has been the primary imaging modality employed in the early detection of breast cancer for the past three decades. This article covers a brief historical development, in parallel with discussions in some details, with respect to the physics of mammography. The hardware of mammography equipment including the X‐ray tubes, generators, and the image receptors are manufactured with different engineering implementation. Thus, specific commercial products are introduced to describe the technological achievements of typical representative designs. Since the radiology community as a whole is gearing toward the filmless “digital” era, the screen‐film mammography is briefly discussed while the digital mammography including computed radiography (CR) and digital radiography (DR) are given more attention in this article. Mammography products that are readily available in the U.S. market are described. This is due primarily to the fact any medical devices are regulated by the U.S. Food and Drug Administration (FDA) in the United States, but had profound effect on the equipment design and development of mammography products. The mammography related equipment, in particular, is regulated under the Mammography Quality Standards Act (MQSA), originally enacted in 1990.

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Xeroradiography

Cited by 105 publications

References 41 publications

Amorphous selenium and its alloys from early xeroradiography to high resolution X‐ray image detectors and ultrasensitive imaging tubes

Amorphous selenium and its alloys from early xeroradiography to high resolution X‐ray image detectors and ultrasensitive imaging tubes

Feasibility of a large area x‐ray sensitive vidicon for medical fluoroscopy: Signal and noise factors

Mammography

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