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Technology |
Theory |
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Exclusive Wide-Beam
ReconstructionTM(WBR) Technology |
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Resolving the
Age-old Trade-off between |
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Sensitivity and
Resolution in Nuclear Imaging |
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General |
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WBR is a patented, innovative technology
that is revolutionizing NM imaging. It virtually resolves the well-recognized,
age-old trade-off between image resolution and image sensitivity inherent in
current gamma cameras. With WBR, SPECT acquisitions can be made twice as fast,
or even four times as fast, without sacrificing image resolution.
Alternatively, patient radiopharmaceutical doses can be reduced, again without
compromising image quality. Or, if required, resolution can be doubled without
lengthening the acquisition time. The WBR technology has been incorporated in
the Xpress.CardiacTM,
Xpress3.CardiacTM and
Xpress/Xact.BoneTM applications packages. These products
have been cleared for sale in the U.S. and Europe and are already in operation
in hundreds of leading NM imaging centers worldwide. |
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The Problem in
Current Gamma Cameras |
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The resolution and sensitivity trade-off problem in gamma cameras is systemic;
the image resolution and the image sensitivity of the collimation system are
inversely related. The collimator geometry required to produce high-resolution
images, namely long-bore, small-hole and thick-septa collimation, limit the
number of photons reaching the detector crystal to the ones that are nearly
perpendicular to it. This results in lower image sensitivity. The more limiting
the collimators are, the higher the image resolution that can be obtained.
However, as resolution is improved, sensitivity is compromised. Thus, there is
a clear trade-off between the sensitivity and resolution of the system. Reduced
sensitivity is generally compensated for by long acquisition times and/or high
radiopharmaceutical doses typical of Nuclear Imaging. |
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The Theory behind
WBR |
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WBR, UltraSPECT's
exclusive reconstruction algorithms technology resolves the sensitivity and
resolution trade-off problem that is inherent to the gamma camera, and which is
critical in SPECT imaging. In SPECT the patient data acquired in a series of
2-dimensional (2D) images, or projections, are back-projected in the
reconstruction process into a virtual 3D space yielding an image, or a series
of images, very similar to the real 3D distribution of the radioisotope within
the body.
Unlike current SPECT reconstruction technologies, WBR does not assume the
photon rays detected by the detector crystal to be perpendicular to it. Rather,
it employs an intelligent and accurate, iterative image reconstruction process
that enables simultaneous resolution and contrast recovery coupled
with noise suppression based on an accurate physical modeling of the
photon emission and detection. The model compensates for the collimator's "beam
spread function" effect and automatically adjusts for the distance from the
patient. The WBR advantage is utilized to either dramatically shorten the
acquisition time or significantly improve image quality for the same
acquisition parameters—same application, same camera, same collimator, same
patient and same radiopharmaceutical dose. Additionally, WBR can be utilized to
lower the radiopharmaceutical dose administered to the patient, maintaining the
same image quality and acquisition parameters—same application, same camera,
same collimator, same patient and same scan time.
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The WBR Hardware
Platform |
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Compatible with
most major manufacturers' cameras and workstations, WBR products offer
virtually seamless integration into the department network. The hardware
platform, based on a quad-core CPU with embedded software, can be installed in
a couple of days, offering a transparent interface between the gamma
camera and workstation. |