31 results about "X-Ray Tube Current" patented technology

The present invention provides an X-ray CT apparatus capable of obtaining each tomographic image indicative of X-ray tube voltage dependent information of a subject with the optimum image quality by less reduced exposure. The X-ray CT apparatus includes device for setting a plurality of X-ray tube voltages and sets imaging conditions used in the photography using the respective X-ray tube voltages in such a manner that respective image noise of tomographic images photographed at the X-ray tube voltages become substantially identical to one another. The setting of the imaging conditions is the setting of X-ray tube currents. The X-ray tube currents are set based on geometrical characteristic amounts of the subject determined from each scout image in such a manner that the respective image noise of the tomographic images photographed at the plurality of X-ray tube voltages become substantially identical to one another.

An X-ray CT apparatus is provided with an X-ray tube current modulation pattern calculation means that calculates an X-ray tube current modulation pattern based on a 3-dimensional model of an object calculated based on a scanogram image of the object, start-up shape acquisition means that acquires a start-up shape of CT values of a predetermined region of the object or CT value time differences after injecting contrast agent into the object, time contrast curve prediction means that predicts a time contrast curve indicative of a time sequential change of contrast in a diagnostic portion of the object at each slice position at a scan time based on the acquired start-up shape of the CT values or CT value time differences, object 3-dimensional model modification means that modifies a 3-dimensional model of the object based on the predicted time contrast curve, and X-ray tube electric current modulation pattern modification means that modifies the X-ray tube electric current modulation pattern based on the modified 3-dimensional model of the object.

In a method for controlling the modulation of the tube current of an X-ray tube in the production of images using computed tomography, a single topogram of the examination subject is obtained and an orthogonal attenuation value is calculated therefrom, also making use of geometrical information associated with the position of the table on which the examination subject is disposed. In a subsequently-obtained computed tomography scan, the tube current is controlled using the orthogonal patient attenuation.

An X-ray CT apparatus includes: an X-ray source which emits X-rays while rotating around a subject; a compensation filter which adjusts at least one of the output distribution and the spectral distribution of the X-rays emitted from the X-ray source to the subject; an X-ray detector which is disposed opposite to the X-ray source with the subject interposed therebetween, rotates together with the X-ray source, and detects the amount of X-rays transmitted through the compensation filter and the subject; an image operation unit which reconstructs a tomographic image of the subject on the basis of the detected amount of X-rays; a display unit which displays the tomographic image; a control unit which controls each of the constituent components; and a compensation unit which compensates for deterioration of image quality, which is based on the amount of displacement between the rotation center of the X-ray source and a desired position of the subject, by changing an X-ray tube current modulation pattern indicating a time-series change of emission of the X-rays and / or by moving the position of the subject.

Approaches for acquiring CT image data corresponding to a full scan, but at a reduced dose are disclosed. In one implementation, X-ray tube current modulation is employed to reduce the effective dose. In other implementations, acquisition of sparse views, z-collimation, and two-rotation acquisition protocols may be employed to achieve a reduced dose relative to a full-scan acquisition protocol.