How It Works

Exclusive Wide-Beam Reconstruction™(WBR) Technology

Resolving the Age-old Trade-off between
Sensitivity and Resolution in Nuclear Imaging

General
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.

The Problem in Current Gamma Cameras
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.

The Theory behind WBR
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.

The WBR Hardware Platform
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.