Adac Laboratories, Inc.

Steven M Jones

Xiaohan Wang

John R Liebig

Horace H Hines

Thomas F Lang

Michael J Janicki

J Keenan Brown

Ronald Koops

Brian J Walsh

Robert L Kay

Paul M Hug

David A Chan

Matthew J Murphy

Thomas E Lang

Kenneth G Bayer

A method of performing image reconstruction in a gamma camera system comprises the steps of performing a transmission scan of an object about a number of rotation angles to collect transmission projection data and performing an emission scan of the object about numerous rotation angles to collect emission projection data. The outer boundary of the object is then located based on the transmission projection data. Information identifying the boundary is then either stored in a separate body contour map or embedded in an attenuation map. The information identifying the boundary can be in the form of flags indicating whether individual pixels are inside or outside the boundary of the object. The emission projection data is then reconstructed, using the attenuation map if desired, to generate transverse slice images. By using the body boundary information, portions of the emission projection data representing points outside the boundary of the object are not reconstructed in order to reduce total reconstruction time.

Use of body boundary information to perform iterative reconstruction in

A method of coregistering medical image data of different modalities is provided. In the method, an emission scan of an object is performed using a nuclear medicine imaging system to acquire single-photon emission computed tomography (SPECT) image data. A transmission scan of the object is performed simultaneously with the emission scan using the same nuclear medicine imaging system in order to acquire nuclear medicine transmission image data. The emission scan is performed using a roving zoom window, while the transmission scan is performed using the full field of view of the detectors. By knowing the position of the zoom windows for each detection angle, the nuclear medicine transmission image data can be coregistered with the SPECT emission image data as a result of the simultaneous scans. Image data of a modality other than SPECT, such as x-ray computed tomography (x-ray CT) data, magnetic resonance imaging (MRI) data, or positron emission tomography (PET) data, is also provided, which it is desired to have coregistered with the SPECT emission data. The nuclear medicine transmission image data is therefore coregistered with the image data of the different modality. As a result, the image data of the different modality becomes coregistered with the SPECT image data.

Coregistration of multi-modality data in a medical imaging system

A scan speed procedure and method wherein a minimum radiation exposure period is determined on an object by object basis for a transmission study. Two transmission scans are performed including a prescan followed by a second transmission scan phase. The first transmission prescan is performed using a radiation source over the object. This prescan is of a rapid and predetermined duration (Tp). A resultant count density associated with the object is then generated and examined. The portion having the smallest count density (Cm) is determined and a value (Co) representing the minimum required number of counts for transmission study is given. From the above, a transmission period (Ts) is determined by the system and the second transmission scan phase is performed for the duration Ts using a multi-pass scan phase. The computed duration Ts represents the minimum exposure duration required to collect transmission data to ensure that the count density distribution associated with the object will contain at least Cm count density over each portion of the object.

Scan speed for transmission exposure reduction in a nuclear medicine

A method and apparatus for collecting transmission information utilizing a large field of view of a detector and for collecting emission data using a small field of view window of the same detector. The system employs the large field of view of a scintillation detector in order to collect transmission data for the entire body being scanned. Such a technique improves the quantitative capability of emission data by acquiring non-truncated attenuation factors. The emission data of a small field of view window is collected so that high resolution image pixels are used for processing the emission data (e.g., of a particular body organ). Since a large field of view is used for collecting the transmission data, the imaging pixels for transmission data are of lower resolution than the emission data. The emission data can be collected using a roving zoom technique during an ECT scan. A computation adjusts the transmission data to account for the known location of the emission zoom window on the crystal and for the different pixel sizes between the full field of view transmission scan of the body and the smaller roving electronic field of view emission scan of the body organ.

Large field of view transmission and small field of view emission scan

A mechanism and method for performing transmission and emission scanning sessions with two line sources and two detectors wherein two sliding transmission detection windows are employed to differentiate between transmission and emission photons. Transmission and emission data can be collected simultaneously. This system provides that the dual transmission detection windows are each associated with a particular line source and move in synchronization with the associated line source. Further, the two line sources and the two detector windows all move in synchronization in the direction of the long axis of the object being scanned and at any given position all are within a given spatial plane that is transverse to the long axis of the object. In this configuration, the system can effectively reduce the amount of cross-talk detected by a detector (e.g., cross-talk being scattered photon radiation detected by a given detector but not originating from the detector's associated line source). The configuration of this system also effectively operates in conjunction with systems employing tracking zoom regions across detector surfaces (e.g., used for cardiac studies).

Dual synchronized sliding transmission detection windows for dual

A variable filter arrangement wherein differently sized and shaped filters are automatically selected and installed from a collection of filters housed within a configuration for use with a radiation source. The line source is typically used for transmission scanning to collect attenuation correction factors. A line source is utilized in the preferred embodiment and a series of filters (e.g., differently sized 'bow-tie' filters) are rotatably attached to a central junction so that a particular filter can be rotated into an installed position. When installed, the filter acts to attenuate the radiation emitted from the line source to reduce radiation emitted on an otherwise unobstructed area of a scintillation detector. Differently sized filters are advantageously used to accommodate differently sized patents and also to accommodate different unobstructed parts of a detector for different angles of rotation during an ECT transmission scan. The system includes processing intelligence to automatically select the proper filter given body contour (e.g., profile) information.

Variable filters used with radiation source to reduce unobstructed

A system for automatically positioning zoom regions located on imaging surfaces of an ECT camera system during ECT rotation to track relative movement of an object that is located offset from the center of rotation of the ECT camera system. During an ECT scan session, the imaging surfaces of the camera system rotation about an object of interest that is located offset from the center of rotation of the camera system in order to minimize the separation between the imaging surfaces and the object surface. Since the object of interest is offset from the center of rotation, a predetermined zoom region located on the imaging surfaces must alter its position relative to the imaging surface during an ECT scan session in order to remain aligned with the object being imaged. The system determines this alignment position and thereby adjusts, in real-time, the location on the imaging surface of the zoom regions for increased image quality.

Apparatus and method for automatic tracking of a zoomed scan area in a

A direct measurement system for proximity detection of a body profile for use within nuclear medicine. The measurement system includes two or three proximity detector units mounted on a gantry structure of a nuclear medicine camera which each emit an energy beam which is swept across a portion of a target body. Each detector is capable of directly measuring the distance from the proximity detector unit to the target body with a beam sample. The detectors then create a body profile of the target body which is used to minimize the distance between the collimator of a scanning camera and the target body surface thus improving image quality of the scanning camera. There is relative motion between the object and the gantry along a cranial-caudal axis of a target body for scanning successive body profiles. Successive body profiles are combined together to achieve a complete body contour of the target body. The proximity detector units are stationary with respect to movement of the scanning camera toward said target body. Body contour data is also used for attentuation correction.

Proximity detector for body contouring system of a medical camera

A system for automatically positioning zoom regions located on imaging surfaces of an ECT camera system during ECT rotation to track relative movement of an object that is located offset from the center of rotation of the ECT camera system. During an ECT scan session, the imaging surfaces of the camera system rotate about an object of interest that is located offset from the center of rotation of the camera system in order to minimize the separation between the imaging surfaces and the object surface. Since the object of interest is offset from the center of rotation, a predetermined zoom region located on the imaging surfaces must alter its position relative to the imaging surface during an ECT scan session in order remain aligned with the object being imaged. The system determines this alignment position and thereby adjusts, in real-time, the location on the imaging surface of the zoom regions for increased image quality.

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Pleasanton, CA, United States of America

Steven M Jones