Abstract: In order to provide an X-ray CT apparatus and the like that reconstruct an image using an iterative approximation method which ensures stable convergence and can be executed at high speed, a computation device 5 of an X-ray CT apparatus 1 calculates matrices A, B, D, R, and R? on the basis of the scanning conditions input through an input device 6 (step 1). Then, the computation device 5 calculates each element of a matrix I??(SBTDA+?SR) (step 2). Then, the computation device 5 calculates the operator norm ?I??(SBTDA+?SR)? of the matrix I??(SBTDA+?SR) (step 3). Then, the computation device 5 determines a relaxation coefficient ? such that a predetermined conditional expression is satisfied (step 4).

Abstract: In order to provide a technique of obtaining an image having high diagnosability without degrading the operability in an X-ray CT apparatus that suppresses the amount of exposure of an object by controlling the amount of radiation by setting a target image SD and determining the imaging conditions (tube current) satisfying the target image SD, there is provided an X-ray CT apparatus that controls the amount of radiation according to the size of an object in consideration of the contrast by simply inputting one image quality level as a reference of the image quality level that the operator desires. The input image quality level is set as a target image SD when scanning an object having a standard size with a standard tube voltage.

Abstract: In order to provide a reconstruction computing device, a reconstruction computing method, and an X-ray CT apparatus capable of improving the image quality while reducing the amount of computation when reconstructing an X-ray CT image using an iterative method, a reconstruction computing device divides an initial image 50 reconstructed using an analytical method such as an FBP method into a bed region 51, an object region 52, and the other air region 53, sets reconstruction conditions including at least convergence conditions and a pixel size for each of the divided regions, updates estimation images by performing an iterative process, and fixes estimation images or forward projection data of a subset satisfying the convergence conditions until other subsets satisfy the convergence conditions.

Abstract: There are provided an X-ray CT scan simulator and an X-ray CT apparatus in which a lesion postulated by an operator can be displayed on a simulation image and a high-precision simulation containing a postulation of occurrence of a new lesion can be performed. They comprise an image storing device for storing a reference image, a target noise value setting device for setting a target noise value of a desired image, a simulated lesion setting device for setting a condition for a simulated lesion postulated by the operator, a simulation image generating device for generating a simulation image containing a simulated lesion by using the reference image on the basis of the set target noise value and the condition for the simulated lesion, and an image display device for displaying the simulation image containing the simulated lesion.

Abstract: Provided is an X-ray CT apparatus which can perform CT scan of multi-energy scanning at a high speed and can obtain an image having an excellent substance distinguishing ability. The X-ray CT apparatus includes: means to continuously perform a first CT scanning using a first X-ray energy and a second CT scanning using a second X-ray energy without interrupting CT scan; means to transit the X-ray energy emitted from the X-ray during a transition period TR including an end of the first CT scanning and a beginning of the second CT scanning from the first X-ray energy to the second X-ray energy; and means to compensate the scan data in the transition period by the opposing data in the residual scan period so as to reconstruct an image.

Abstract: 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 modifi

Abstract: 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

Abstract: An X-ray CT apparatus comprising: a scanner unit for rotating one or more X-ray sources for applying X-ray beams having different energy spectra to an object, and detectors disposed opposed to the X-ray sources for detecting transmitted X-ray data on the object, around the object while applying X-rays, reconstructing means for reconstructing a tomogram of the object by acquiring transmitted X-ray data on the object including the two or more different energy spectra by using the scanner, and display means for displaying the reconstructed tomogram; the X-ray CT apparatus further comprising input means for inputting information on an identification tissue of the object to be identified and a separate tissue to be separated from the identification tissue from the tomogram and scanning condition determining means for determining the scanning condition for identifying the identification tissue from the tomogram. With this, an optimum scanning condition of a multi-energy X-ray CT apparatus can be determined.

Abstract: In order to provide a CT image forming method that can reduce an artifact caused by an image reconstructing method, and an X-ray CT apparatus using the same, an X-ray CT image forming method according to the invention is characterized in that an artifact component caused by the image reconstructing method of the projection data is obtained by calculation; the determined artifact component is subtracted from the projection data to create corrected projection data containing an inverted artifact component, and image reconstruction is executed on the corrected projection data to obtain a reconstructed image from which the artifact is reduced. The inverted artifact component is obtained as differential between the projection data and re-projection data obtained by inversely projecting a reconstructed image which is obtained by reconstructing the projection data concerned.

Abstract: An image processing method comprises: an inputting step of inputting image data which is obtained by imaging a subject for a predetermined period of time with a medical imaging apparatus and is arranged in time series; an extracting along the time axis step of extracting pixels which satisfy a predetermined condition along the time axis from all the pixels arranged in time series for each pixel coordinate position with respect to each pixel in the image data; and a constructing step of constructing a two-dimensional or three-dimensional image based on the pixels extracted along the time axis in the extracting along the time axis step.

Abstract: An X-ray CT apparatus acquires a scanogram of an object to be examined, generates an ellipse model having an X-ray attenuation coefficient equivalent to that of water and approximated to a tomographic image of the obtained imaged portion from the feature quantity of the projection value profile, determines whether or not the generated elliptic model is adequate as a model of the imaged portion from another feature quantity with respect to the projection value profile, generates a corrected elliptic model according to yet another feature quantity with respect to the projection value profile if the elliptic model is determined to be inadequate, and controls the modulation of the tube current in an X-ray source so that a predetermined target SD value is maintained in any scanning position when a tomographic image is reconstructed according to X-rays transmitted through the object by using the elliptic model or the corrected elliptic model.

Abstract: There is provided an X-ray CT apparatus that can control an irradiation X-ray dose in accordance with a displacement of an internal organ due to breathing of an examinee or the like with satisfying both of enhancement of image quality and lessening of exposed dose. In preparation processing before scan is started, an X-ray CT apparatus 1 generates a three-dimensional cross-section model from scanogram projection data of an examinee. An operator is made to input a site of interest, an assumed displacement amount of the site and a desired image quality index value. A scan planning unit 405d calculates an X-ray attenuation index from the three-dimensional cross-section model, and corrects the calculated X-ray attenuation index on the basis of the input site of interest, assumed displacement amount and image quality index value. The scan planning unit 405d further determines a tube current modulating pattern (irradiation X-ray dose modulating pattern) on the basis of the corrected X-ray attenuation index.

Abstract: A radiographing apparatus according to an aspect of the present invention is characterized in that an image processing device comprises an acquisition device which acquires projection data of a first energy spectrum and projection data of a second energy spectrum, and a synthetic image generating device which synthesizes a first image on the basis of the projection data of the first energy spectrum, and a second image on the basis of the projection data of the second energy spectrum according to a predetermined synthetic condition, and generating a synthetic image, and a display device displays the generated synthetic image.

Abstract: There are provided an X-ray CT scan simulator and an X-ray CT apparatus in which a lesion postulated by an operator can be displayed on a simulation image and a high-precision simulation containing a postulation of occurrence of a new lesion can be performed. They comprise an image storing device for storing a reference image, a target noise value setting device for setting a target noise value of a desired image, a simulated lesion setting device for setting a condition for a simulated lesion postulated by the operator, a simulation image generating device for generating a simulation image containing a simulated lesion by using the reference image on the basis of the set target noise value and the condition for the simulated lesion, and an image display device for displaying the simulation image containing the simulated lesion.

Abstract: An X-ray CT apparatus is provided, having a function for deciding an X-ray imaging condition prior to scanning, the X-ray imaging condition allowing an acquisition of contrast to noise ratio appropriate for identifying a diagnostic object. Prior to the real scan, a three-dimensional model of an object is estimated from scanogram projection data of the object, a contrast to noise ratio enabling identification of the diagnostic object is calculated, based on the diagnostic object size set by an operator via an operating device when planning the scan, the three-dimensional model, and a standard imaging condition that is stored in a storage device. Then, an optimum irradiated X-ray condition (tube current and tube voltage) is calculated for achieving the contrast to noise ratio enabling identification. The X-ray condition being calculated is displayed in the form of information such as image SD value and exposure dose, under the calculated X-ray condition and under other condition.

Abstract: 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 modifi

Abstract: Provided is an X-ray CT apparatus which can perform CT scan of multi-energy scanning at a high speed and can obtain an image having an excellent substance distinguishing ability. The X-ray CT apparatus includes: means to continuously perform a first CT scanning using a first X-ray energy and a second CT scanning using a second X-ray energy without interrupting CT scan; means to transit the X-ray energy emitted from the X-ray during a transition period TR including an end of the first CT scanning and a beginning of the second CT scanning from the first X-ray energy to the second X-ray energy; and means to compensate the scan data in the transition period by the opposing data in the residual scan period so as to reconstruct an image.

Abstract: In the X-ray CT apparatus of the present invention, the setting device sets X-ray irradiation condition candidate by at least one combination of a tube current and tube voltage for power to be supplied to the X-ray source by the use of an X-ray absorption coefficient of said scanning subject site of the object, and the control device makes the display device selectably display each of the set X-ray irradiation condition candidates which is provided for a diagnosis of a requested tissue of the object, to take control such that a tomographic image of the object is taken according to the selected X-ray irradiation condition candidate. According to the X-ray CT apparatus of the present invention, it is possible to set a scanning condition in view of absorption or transmission of X-rays specific to and different among each tissue of an object.

Abstract: An X-ray CT apparatus inputs information with respect to a target tissue of the object to be discriminated in the tomographic image and inputs an index with respect to correctness of the discrimination, and determines scanning conditions for discriminating the target tissue based on the index.

Abstract: An X-ray CT apparatus is configured capable of properly calculating a radiation dosed amount more approximating to an actually exposed radiation dose that includes scattering rays of an examined object from data measured at the scanning time. A function or table showing a relationship between data obtained on the basis of the measured data of the object detected by an X-ray detector at the scanning time and the radiation dosed amount is stored in advance; and the X-ray CT apparatus calculates the radiation dosed amount of the object in accordance with the data obtained on the function or table showing the relationship between the data obtained on the basis of the measured data of the object stored in advance and the radiation dosed amount.