Effects of scintillator on the detective quantum efficiency (DQE) of a digital imaging system

Farman, Taeko T.; Vandre, Robert H.; Pajak, John C.; Miller, Stuart; Lempicki, Alex; Farman, Allan G.

doi:10.1016/j.tripleo.2005.07.032

Cited by 19 publications

(7 citation statements)

References 17 publications

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“…[30][31][32] Although the introduction of high DQE indirect-conversion aSi:H FPDs into CBCT systems is a significant technical advancement, these detectors still have a slightly inferior DQE compared with the detectors traditionally used in MDCT systems. 8,33 This remains one of the technical challenges limiting low-contrast detectability in most CBCT systems.…”

Section: Dqementioning

confidence: 99%

Conebeam CT of the Head and Neck, Part 1: Physical Principles

Miracle¹,

Mukherji²

2009

AJNR Am J Neuroradiol

325

223

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SUMMARY: Conebeam x-ray CT (CBCT) is a developing imaging technique designed to provide relatively low-dose high-spatial-resolution visualization of high-contrast structures in the head and neck and other anatomic areas. This first installment in a 2-part review will address the physical principles underlying CBCT imaging as it is used in dedicated head and neck scanners. Concepts related to CBCT acquisition geometry, flat panel detection, and image quality will be explored in detail. Particular emphasis will be placed on technical limitations to low-contrast detectability and radiation dose. Proposed methods of x-ray scatter reduction will also be discussed.C onebeam x-ray CT (CBCT) is a relatively recent installment in the growing inventory of clinical CT technologies. Although the first prototype clinical CBCT scanner was adapted for angiographic applications in 1982, the emergence of commercial CBCT scanners was delayed for more than a decade. 1 The arrival of marketable scanners in the last 10 years has been, in part, facilitated by parallel advancements in flat panel detector (FPD) technology, improved computing power, and the relatively low power requirements of the x-ray tubes used in CBCT. These advancements have allowed CBCT scanners to be sufficiently inexpensive and compact for operation in office-based head and neck as well as dental imaging applications. These systems are distinguished by a conical x-ray beam geometry and the use of 3D reconstruction algorithms; most recent models are also fit with FPDs. As they are employed for specific imaging tasks in restricted anatomic regions such as the head and neck, preliminary research suggests that they can produce images with high isotropic spatial resolution while delivering a relatively low patient dose. This first part in a series of 2 articles will review the physical principles underlying CBCT as it is employed in head and neck diagnostic imaging. C-arm CBCT systems used in the interventional suite and CBCT systems used in radiation therapy have been the subject of other reviews.2-4 Although there are numerous differences between CBCT and conventional fan-beam CT techniques, many of the fundamental physical concepts are the same. Fundamental Principles of CTThe original clinical CT scanner was introduced by Sir Godfrey N. Hounsfield in 1967. Data acquisition was based on a translaterotate parallel-beam geometry wherein pencil beams of x-rays were directed at a detector opposite the source and the transmitted intensity of photons incident on the detector was measured. The gantry would then both translate and rotate to capture x-ray attenuation data systematically from multiple points and angles.5 Although x-ray sources, acquisition geometries, and detectors have rapidly evolved since Hounsfield's original scanner, the theory behind CT has not changed.The attenuation of a monochromatic x-ray beam through a homogeneous object is described by the Lambert-Beer law:where I is the transmitted photon intensity, I o is the original intensity, x is the lengt...

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Section: Dqementioning

confidence: 99%

Conebeam CT of the Head and Neck, Part 1: Physical Principles

Miracle¹,

Mukherji²

2009

AJNR Am J Neuroradiol

325

223

View full text Add to dashboard Cite

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“…Also, other activators were used, especially for lasing in Lu 2 O 3 sintered transparent bodies [20,21]. With its impressive density of 9.84 g/cm 3 , high effective Z-number (63.7) and light yield similar to Gd 2 O 2 S-based phosphors [3,22,23,24] both lutetia powders and sintered ceramics were considered attractive for X-ray scintillator detectors [3,22,25]. Furthermore, with an energy band gap of about 5.85 eV [25], Lu 2 O 3 :Eu was recognized to have potential to produce as much as about 75,000 ph/MeV upon ionizing radiation excitation.…”

Section: Introductionmentioning

confidence: 99%

Flux-Aided Synthesis of Lu2O3 and Lu2O3:Eu—Single Crystal Structure, Morphology Control and Radioluminescence Efficiency

2014

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Li2SO4 or (Li2SO4 + SiO2)-mixture fluxes were used to prepare a Lu2O3:Eu powder phosphor as well as an undoped Lu2O3 utilizing commercial lutetia and europia as starting reagents. SEM images showed that the fabricated powders were non-agglomerated and the particles sizes varied from single microns to tens of micrometers depending largely on the flux composition rather than the oxide(s)-to-flux ratio. In the presence of SiO2 in the flux, certain grains grew up to 300–400 μm. The lack of agglomeration and the large sizes of crystallites allowed making single crystal structural measurements and analysis on an undoped Lu2O3 obtained by means of the flux technique. The cubic structure with a = 10.393(2) Å, and Ia space group at 298 K was determined. The most efficient radioluminescence of Lu2O3:Eu powders reached 95%–105% of the commercial Gd2O2S:Eu.

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“…However, in comparison with conventional CT, CBCT suffers from increased x-ray scatter, reduced dynamic range, and inferior detector quantum efficiency (DQE). [1][2][3] Additionally, the polychromatic nature of the x-ray beam results artifacts such as beam hardening and metal streak in both conventional CT and CBCT.…”

Section: Introductionmentioning

confidence: 99%