摘要:
Scintillators having a geometric configurations that substantially prevent x-ray beams from passing entirely through a gap between adjacent scintillators are described. More particularly, if the scintillators are cut on an angle to form parallelogram or trapezoidal shapes, or if the detector module is tilted in the x-ray beam z-axis, an x-ray beam will not pass through a non-scintillating gap between adjacent scintillators over the range of focal spot positions. Such scintillators have an increased geometric efficiency compared to known scintillator constructions.
摘要:
The present invention is, in one aspect, an imaging system having a detector that has multiple detector cells extending along a z-axis, the detector being configured to collect multiple slices of data; and a scalable data acquisition system configured to convert signals from the detector to digital form, the scalable data acquisition system having a plurality of converter boards each with a plurality of channels, the channels and detector cells having an interweaved coupling to reduce susceptibility to band artifact.
摘要:
A method is described for optimizing signal-to-noise performance of an imaging system, including the steps of scout-scanning an object to obtain scout scan data; determining a plurality of normalized x-ray input signal factors using the scout scan data; using the normalized x-ray input signal factors to determine at least one system input signal; selecting at least one gain for the object scan using the system input signal; and applying the selected gain corresponding to the system input signal in the object scan.
摘要:
Methods and apparatus for reducing spectral artifacts in a computed tomography (CT) system are described. In one embodiment, the CT system includes a plurality of multislice detector modules, a detector housing and a collimator adjacent the detector modules. Each detector module is mounted to the detector housing and includes a scintillator array. The collimator includes a plurality of plates that are positioned so that a x-ray beam shadow is centered over gaps in the scintillator array. In operation, the collimator separates the x-ray beams so that the scintillator gaps are protected and the x-ray beams are prevented from projecting through the scintillator array elements along a shortened length path.
摘要:
A CT system includes a rotatable gantry having an opening for receiving an object to be scanned, and a controller configured to apply a first kVp for a first time period, apply a second kVp for a second time period, wherein the second time period is different from the first time period, acquire a first asymmetric view dataset during at least a portion of the first time period, acquire a second asymmetric view dataset during at least a portion of the second time period, and generate an image using the acquired first and second asymmetric view datasets.
摘要:
A method of manufacturing a collimator mandrel having variable attenuation characteristics is presented. The manufacturing process includes the placement of a layer of attenuating material on a core of base material. The layer of attenuating material is relatively thin and varies in thickness circumferentially around the core. The collimator mandrel may be manufactured by placing a cast about a core of non-attenuating material, filling a void between the cast and the core with an attenuating material, allowing the material to cure, and removing the cast from the assembly.
摘要:
A system and method of diagnostic imaging is provided that includes determining a position of a subject in a scanning bay and tailoring x-ray attenuation such that the specific position of the subject is taken into consideration. The present invention automatically selects a proper attenuation filter configuration, corrects patient centering, and corrects noise prediction errors, thereby increasing dose efficiency and tube output.
摘要:
The present invention is, in one embodiment, a method for determining tracking control parameters for positioning an x-ray beam of a computed tomography imaging system having a movable collimator positionable in steps and a detector array including a plurality of rows of detector elements. The method includes steps of obtaining detector samples at a series of collimator step positions while determining a position of a focal spot of the x-ray beam; determining a beam position for each detector element at each collimator step utilizing the determined focal spot positions, a nominal focal spot length, and geometric parameters of the x-ray beam, collimator, and detector array; and determining a calibration parameter utilizing information so obtained. For example, in determining a target beam position at which to maintain the x-ray beam, a detector element differential error is determined according to ratios of successive collimator step positions; and a target beam position is selected for an isocenter element in accordance with the determined element differential errors.
摘要:
Methods and apparatus for dose reduction in a computed tomography (CT) system are described. In one embodiment, the CT system includes a configurable multislice detector array and an adjustable source collimator. The detector array includes a photodiode cell array optically coupled to a scintillator array. The photodiode array includes a plurality of photodiodes arranged in rows and columns that may be combined to collect slice data from a number of inner and outer slices. The CT system also includes an x-ray source and a collimator. The x-ray source generates an x-ray beam that is collimated by the collimator to define the thickness of each outer slice. In operation, an operator determines the quantity and thickness of inner slices and the thickness of each outer slice. After altering the detector and collimator configuration, as defined by an operator, slice data for each inner slice and each outer slice is gathered.
摘要:
An x-ray CT system acquires scout data over a region of a patient prior to performing a scan. The scout data is employed to locate the patient in a succession of slices over the region. Geometric scan parameters including display field of view (DFOV), scan field of view (SFOV) and patient centering offsets (X.sub.OFF,Y.sub.OFF) are calculated from the scout data, displayed to the operator, and used as default values in the subsequent scan of the region.