摘要:
A CT imaging system and method are provided in which groups of adjacent detector elements of a detector array are ganged in an x-direction; and an object is scanned using the ganged groups of adjacent detector elements to acquire projection data. In one embodiment, to reduce degradation of images resulting from the ganged detector elements, an image of the object is reconstructed utilizing the acquired projection data and an adjusted iso-channel of the multislice detector array different from an iso-channel defined for scans performed without utilizing ganged groups of detector elements.
摘要:
A CT system includes a rotatable gantry having an opening for receiving an object to be scanned, and a controller. The controller is configured to apply a first kVp for a first time period, apply a second kVp for a second time period, integrate two or more view datasets during the first time period, integrate one or more view datasets during the second time period, and generate an image using the datasets integrated during the first time period and during the second time period.
摘要:
A method and apparatus for tailoring the profile of an x-ray beam for radiographic imaging for a specific subject is disclosed. The invention includes a filter assembly having a pair of filters, each of which may be dynamically controlled by a motor assembly during data acquisition. The filters are positionable in the x-ray beam so as to shape the intensity profile of the x-ray beam. In one exemplary embodiment, the filters are dynamically positioned during CT data acquisition based on the shape of the subject. A method of determining the shape of the subject prior to CT data acquisition is also disclosed.
摘要:
A method and apparatus for tailoring the profile of an x-ray beam for radiographic imaging for a specific subject is disclosed. The invention includes a filter assembly having a pair of filters, each of which may be dynamically controlled by a motor assembly during data acquisition. The filters are positionable in the x-ray beam so as to shape the intensity profile of the x-ray beam. In one exemplary embodiment, the filters are dynamically positioned during CT data acquisition based on the shape of the subject. A method of determining the shape of the subject prior to CT data acquisition is also disclosed.
摘要:
A method and apparatus for tailoring the profile of an x-ray beam for radiographic imaging for a specific subject is disclosed. The invention includes a filter assembly having a pair of filters, each of which may be dynamically controlled by a motor assembly during data acquisition. The filters are positionable in the x-ray beam so as to shape the intensity profile of the x-ray beam. In one exemplary embodiment, the filters are dynamically positioned during CT data acquisition based on the shape of the subject. A method of determining the shape of the subject prior to CT data acquisition is also disclosed.
摘要:
There is therefore provided, in one aspect, a method for imaging an object utilizing a computed tomographic (CT) imaging system having a rotating gantry, a multislice detector array on the rotating gantry and using at least n>1 rows of detector channels, and a radiation source on the rotating gantry configured to project a beam of radiation towards the multislice detector array through an object to be imaged. The method includes helically scanning the object with the CT imaging system at a pitch p>n to acquire projection data from the n rows of detector channels; applying a combined helical weight and conjugate weight to at least a portion of the acquired projection data to produce virtual projection data compensating for incomplete helical row data of the acquired projection data; and reconstructing an image of the object utilizing the acquired projection data and the virtual projection data.
摘要:
Precise alignment of the focal spot position on an x-ray CT system is achieved using a deflection coil that produces a magnetic field which acts on the electron beam path in the x-ray tube. A variable current power supply drives the deflection coil and is controlled by input signals to align the focal spot at a static reference position, to correct for focal spot drift between scans, and to wobble the focal spot position during a scan or between scans.
摘要:
A CT system includes a rotatable gantry having an opening for receiving an object to be scanned, and a controller configured to obtain kVp projection data at a first kVp, obtain kVp projection data at a second kVp, extract data from the kVp projection data obtained at the second kVp, add the extracted data to the kVp projection data obtained at the first kVp to generate mitigated projection data at the first kVp, and generate an image using the mitigated projection data at the first kVp and using the projection data obtained at the second kVp.
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 spectral correction algorithm for correcting dense object-induced spectral artifacts is described. In one embodiment, a calibration object, representative of typical head scanning conditions is scanned and the data reconstructed to provide an image. A water or water-equivalent cylinder of about the same diameter also is scanned and reconstructed, on the same display field of view (DFOV). These two images are designated respectively by BWEQ and WEQ. The ratio of images BWEQ and WEQ is then evaluated, and a region of interest extracted by multiplying the ratio by a function II(r), to obtain a calibration pattern CP. The calibration pattern is then averaged in azimuth to obtain a calibration vector. This calibration vector is fitted with low--order polynomial, and then divided by the fitting polynomial, to take out from the vector the low frequency components that, for instance, would be introduced on an "ideal" scanner. By subtracting 1.0 from the ratio, and multiplying by a CT number scale factor (ctscale) and an apodizing window Aw(r), a calibration error vector CEV is obtained that is representative of the circularly symmetric image error introduced by the non-corrected bone-induced artifact. The corresponding error calibration vector can be expanded into a circularly symmetric image error pattern I[CEV(r)], and subtracted from the calibration image, to provide a substantially artifact free image. The method can be extended to extract and correlate error vectors on an image segment basis such that the resulting error image pattern is not circularly symmetric.