Abstract: Fast reconstruction methods are provided for 3D time-of-flight (TOF) positron emission tomography (PET), based on 2D data re-binning. Starting from pre-corrected 3D TOF data, a re-binning algorithm estimates for each transaxial slice the 2D TOF sinogram. The re-binned sinograms can then be reconstructed using any algorithm for 2D TOF reconstruction. A TOF-FORE (Fourier re-binning of TOF data) algorithm is provided as an approximate re-binning algorithm obtained by extending the Fourier re-binning method for non-TOF data. In addition, two partial differential equations are identified that must be satisfied by consistent 3D TOF data, and are used to derive exact re-binning algorithms and to characterize the degree of the approximation in TOF-FORE.

Abstract: An apparatus for detecting a greater number of lines of response (LOR) within a subset of azimuthal angles of a positron emission tomography scanner. In a positron emission tomography (PET) scanner, the detectors are configured to detect a greater number of lateral LORs than the number of anterior/posterior LORs passing through a patient. The increased sensitivity to the lateral LORs compensates for the increased distance that the lateral LORs travel through the patient than the anterior/posterior LORs. In one embodiment, at least one pair of partial rings are positioned adjacent fixed detector rings. In another embodiment, panel detectors with a longer length than the other detectors are positioned to be responsive to the lateral LORs. In still another embodiment, detectors rotated with a variable angular speed, spending more time measuring lateral LORs than measuring anterior/posterior LORs.

Abstract: A method for fabricating an array adapted to receive a plurality of scintillators for use in association with an imaging device. The method allows the creation of a detector array such that location of the impingement of radiation upon an individual scintillator detector is accurately determinable. The array incorporates an air gap between all the scintillator elements. Certain scintillators may have varying height reflective light partitions to control the amount of light sharing which occurs between elements. Light transmission is additionally optimized by varying the optical transmission properties of the reflective light partition, such as by varying the thickness and optical density of the light partitions. In certain locations, no light partitions exist, thereby defining an air gap between those elements. The air gap allows a large increase in the packing fraction and therefore the overall sensitivity of the array.

Abstract: A device and method for on-line correction of patient motion in three-dimensional positron emission tomography. The devices encompass an on-line hardware pipelining architecture to support 3D translation, normalization, and weighted histogramming as required. Five stages of processing for the PET event stream are utilized in the present invention. Each stage feeds the next with progressively modified event packets proceeding at a processing speed of at least 10M packets/sec. Stage 1 calculates an event correction factor (ECF) for each incoming detector-pair event packet. This ECF is incorporated into the event packet for use later in Stage 5. Stage 2 converts the detector-index-pair content of each packet into (x,y,z) pair content. Specifically, the representation of each detector element is converted from a discrete crystal index into a 3-D coordinate index. Stage 3 transforms the (x,y,z) pair into an (x?,y?,z?) pair. Stage 4 converts the (x?,y?,z?) pair into a bin address.

Abstract: A method for detecting Alzheimer's disease using positron emission tomography. A normal population mean is obtained using PET. The normal population mean is obtained through the assimilation of a number of normal brain scans. Non-AD images and AD images are compared to observe differences in the uptake of FDG. PET scan results are expressed as relative uptake intensities and indexed by Brodmann's areas. An image is tested by comparing the distance of each mean for each Brodmann's area from the normal distribution. A Receiver Operating Characteristic curve is plotted based on the variation of deviation for the total population of both normal and probable Alzheimer's brain images. Variations in FDG uptake in a brain image as compared to the normal distribution confirms the probability of AD.

Abstract: A projection data rebinning device for nearest-neighbor rebinning in Positron Emission Tomography (PET) using on-line 3D axial LOR-to-bin mapping. The PETLINK™ DMA Rebinner (PDR) of the present invention includes a PCI card for on-line translation of detector-pair event packets into bin-address packets. The PDR delivers accurate axial and transaxial LOR nearest-neighbor rebinning and enables the more oblique LOR to be mapped into the proper sinogram bins. The PDR is used in association with hardware architecture in electrical communication with a medical imaging device. The data acquisition architecture includes a processor, random access memory (RAM), an operating system, and a data storage device. The PDR includes a plurality of FPGAs and flash chips. The FPGAs are in communication with each other via a high-bandwidth connection. The flash memory chips are used for look-up tables. The PDR performs on-line translation of detector-pair event packets into bin-address packets.

Abstract: A device for improved on-line histogramming of data acquired in a Positron Emission Tomography (PET) scan. The device is a Smart DRAM (SD) PCI card, of which more than one can be used in combination within a PC-based architecture for on-line histogramming. The SD PCI card is applied as either of a Gating Buffer, a histogramming card, and a normalization buffer. The Gating Buffer card alternately stores an arriving PET data packet stream into two dedicated DRAM banks. The two DRAM banks store and retransmit the packet stream in the order of arrival for an entire physiological cycle. The histogramming SD RMW PCI cards provide a very high rate of histogramming. The extendible daisy-chain of SD RMW PCI cards supports large memory banks across potentially hundreds of SD RMW PCI cards. Under a single PC, a multiple PCI Expansion chassis is employed such that a large number of PCI cards are supported.

Abstract: A normalization apparatus and method for a PET scanner with panel detectors for obtaining an estimate of a normalization array, for correction for count rate effects on the normalization array, and for measurement of the relation between the normalization array and the count rate. The method of the present invention is based on two quasi-independent radial and axial components, which are count rate dependent due to sensitivity changes across the detector blocks. A scatter source is disposed at the center of the FOV and a scatter-free source is disposed at the outer edge of the FOV. The method computes the normalization array through several steps which evaluate the geometric profile, the axial profile, and the correction factor. A count rate correction is introduced to extend the normalization array to any count rate.

Abstract: A device and method for on-line correction of patient motion in three-dimensional positron emission tomography. The devices encompass an on-line hardware pipelining architecture to support 3D translation, normalization, and weighted histogramming as required. For the 3D translation circuit, a first digital pipeline latch is provided for receiving data as it is collected by the PET scanner. A bank of multiplier circuits receives the PET scan data. Each multiplier circuit receives and multiplies a portion of the entire scan data simultaneous with each other multiplier circuit. The product of each multiplier circuit is output to a second digital pipeline latch. The data is then passed to a bank of adders, each of which supports four input variables. While a specific LOR and a current object orientation are input to the first digital pipeline latch, processing for a different LOR and an earlier object orientation are stored in the second digital pipeline latch.

Abstract: Apparatus and methods for three dimensional image reconstruction from data acquired in a positron emission tomograph (PET). This invention uses a parallel/pipelined architecture for processing the acquired data as it is acquired from the scanner. The asynchronously acquired data is synchronously stepped through the stages performing histogramming, normalization, transmission/attenuation, Mu image reconstruction, attenuation correction, rebinning, image reconstruction, scatter correction, and image display.

Abstract: A method for improving clinical data quality in Positron Emission Tomography (PET). The method provides for the processing of PET data to accurately and efficiently determine a data signal-to-noise ratio (SNR) corresponding to each individual clinical patient scan, as a function of a singles rate in a PET scanner. The method relates an injected dose to the singles rate to determine SNR(Dinj), and provides an accurate estimate of a quantity proportional to SNR, similar in function to the SNR(Dinj). Knowledge of SNR(Dinj) permits determination of peak SNR, optimal dose, SNR deficit, dose deficit, and differential dose benefit. The patient dose is fractionated, with a small calibration dose given initially. After a short uptake, the patient is pre-scanned to determine T, S, and R. An optimal dose is then determined and the remainder injected.

Abstract: A method and apparatus for determining and correcting the baseline of a continuously sampled signal for use in positron emission tomography. The method employs continuous signal sampling to determine the signal level at time t(0) so that an accurate determination of an integrated signal may be calculated, resulting in an accurate energy estimate for an ac-coupled, continuously-sampled signal at various count rates. The device includes a front-end electronics processing channel including primarily an analog CMOS ASIC, a bank of ADCs, an FPGA-based digital sequencer, and two RAMs. The processing electronics perform continuous digital integration of PMT signals to obtain normalized position and energy. Continuous baseline restoration (BLR) is used, wherein the baseline of the signal pulses are placed at mid-scale by continuously sampling the ADC, thus always making available the past history. A correction signal is generated for use in negative feedback control of the baseline.

Abstract: A rail system for supporting a patient gantry including a fixed rail assembly mounted on a support surface and a service rail assembly releasably securable to the fixed rail assembly. Each rail assembly includes a bar and a top rail. An alignment device is provided for aligning the top rails of each assembly and is configured so that the rails cannot be interchanged. A lever is provided for positively securing the service rail assembly to either the fixed rail assembly or in a first receptor defined by a mounting block secured to a bearing block and on which is mounted the patient gantry. A toggle clamp includes a pin selectively received in a locating hole defined in the fixed rail assembly. If the toggle clamp has not been engaged and the lever does not engage the first receptor, the lever is received by a second receptor to prevent derailment.

Abstract: A patient bed for use with at least one imaging device in which a plurality of scans to be correlated are performed, as well as in a continuous motion scanner used to compile whole-body scans. The patient bed includes a horizontal rail base and a movable patient surface. Electronic controllers are provided for controlling the horizontal and vertical positioning of the patient surface. The horizontal rail base is secured to the support proximate the scanner. A linear motor is used to generate horizontal motion of the patient bed. The linear motor is controlled using a motion controller in communication with a computer associated with the imaging device. A pedestal is provided for mounting a vertical carriage assembly. A vertical track is carried by the pedestal for controlling vertical travel of the patient bed. A motor is provided for controlling vertical motion. A pallet support member is cantilevered from the vertical carriage assembly for carrying a pallet.

Abstract: A detector for use in imaging applications includes at least one detector array, an array of photodetectors, and a continuous light guide disposed between the detectors and the photodetectors. The light guide is continuous over the entire area of the photodetectors and detectors. The thickness of the light guide is optimized based on the shape of the photodetector array. Each detector array includes a plurality of scintillator elements disposed in an M×N array, where “M” and “N” are independently selectable and are each at least one. A mechanism for maintaining the relative positions of the individual scintillator elements with respect to each other is provided. The retainer is further provided to enhance the separation between the individual detector arrays to define distinct boundaries between the position profiles of the scintillator arrays.

Abstract: A method and apparatus for on-line DOI rebinning for LSO PET/SPECT to improve spatial resolution, for use in a hybrid Positron Emission Tomography (PET)/Single Photon Emission Computed Tomography (SPECT) system running in PET-mode. Data acquisition hardware is used to feed a detector pair coincidence event stream to an on-line rebinner. Gamma centroid location measurements are made by rastering assumed transaxial and radial head positions and the corresponding rebinning maps for optimal back-projected image resolution. Optimal positions are found by collecting a 64-bit list mode file, assuming a crystal position as the centroid for each of the heads, defining a sequence for varying the assumed positions, making the rebinning look-up tables, rebinning the list mode data, histogramming and reconstructing the image, assessing the image resolution, recording the best resolution number and the associated trial position variables, repeating these on the next trial variable set.

Abstract: A method for producing a high resolution detector array so as to provide very high packing fraction, i.e., the distance between scintillator elements is minimized so the detector efficiency will be higher than is currently achievable. In the preferred embodiment of the present invention, the fabrication methodology is enhanced by handling LSO bars rather than single crystals when gluing on the Lumirror® as well as etching the LSO. Namely, an LSO boule is cut into wide bars of a selected dimension, for example 30 mm, which are then acid etched or mechanically polished. A selected number, N, of these LSO bars can then be glued together with Lumirror® sheets between each bar (coating the LSO disks and Lumirror® sheets with Epotek 301-2). The glued bar block is then cut again into bars in a perpendicular direction, and these new LSO-Lumirror® bars are etched.

Abstract: A method for fabricating a detector or light guide using laser technology. The method yields a detector component such as a scintillator, light guide or optical sensor which provides for the internal manipulation of light waves via the strategic formation of micro-voids to enhance control and collection of scintillation light, allowing for accurate decoding of the impinging radiation. The method uses laser technology to create micro-voids within a target media to optically segment the media. The micro-voids are positioned to define optical boundaries of the optically-segmented portions forming virtual resolution elements within the scintillator. Each micro-void is formed at its selected location using a laser source. The laser source generates and focuses a beam of light into the target media sequentially to form the micro-voids. The laser beam ablates the media at the focal point, thereby yielding the micro-void.

Abstract: A patient handling system (10) for use with a medical imaging or radiation therapy device, and an associated pallet mounting apparatus (12) for releasably mounting a pallet (18) on the pallet support assembly (16) of a patient handling system. The patient handling system (10) includes a pallet (18) for supporting a patient, and a pallet support assembly (16) for supporting the pallet (18) and for positioning the pallet (18) to facilitate the scanning of a patient positioned on the pallet (18) using the medical imaging device, or to facilitate the application of radiation therapy to a patient using a radiation therapy device.

Abstract: A detector array including a plurality of scintillators for use in association with an imaging device. The detector array is provided for accurate determination of the location of the impingement of radiation upon an individual scintillator detector. An air gap is disposed between the scintillator elements, thereby increasing the packing fraction and overall sensitivity of the array. The amount of light transmitted down the scintillator element and the amount of light transmitted to adjacent elements is modified to optimize the identification of each element in a position profile map by adjusting the surface finish of the detector elements.