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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-offs 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. 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 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 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. |
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The WBR Hardware
Platform |
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Compatible with
most major manufacturers' cameras and workstations, WBR products offer seamless
integration into the department network. The hardware, consisting primarily of
a dual Pentium processor with embedded software, can be installed in a matter
of hours, offering a transparent interface between the Gamma Camera and
workstation. |