Various methods and systems are provided for multi-material decomposition for computed tomography. In one embodiment, a method comprises acquiring, via an imaging system, projection data for a plurality of x-ray spectra, estimating path lengths for a plurality of materials based on the projection data and calibration data for the imaging system, iteratively refining the estimated path lengths based on a linearized model derived from the calibration data, and reconstructing material-density images for each material of the plurality of materials from the iteratively-refined estimated path lengths. By determining path-length estimates in this way without modeling the physics of the imaging system, accurate material decomposition may be performed more quickly and with less sensitivity to changes in physics of the system, and furthermore may be extended to more than two materials.

A computer-implemented method of an embodiment is for automatically estimating and/or correcting an error due to artifacts in a multi-energy computed tomography result dataset relating to at least one target material. In an embodiment, the method includes determining at least one first subregion of the imaging region, which is free from the target material and contains at least one, in particular exactly one, second material with known material-specific energy dependence of x-ray attenuation; for each first subregion, comparing the image values of the energy dataset for each voxel, taking into account the known energy dependence, to determine deviation values indicative of artifacts; and for at least a part of the at least one remaining second subregion of the imaging region, calculating estimated deviation values by interpolating and/or extrapolating from the determined deviation values in the first subregion, the estimated deviation values being used as estimated error due to artifacts.

Various methods and systems are provided for spectral computed tomography (CT) imaging. In one embodiment, a method comprises performing a scan of a subject to acquire, with a detector array comprising a plurality of detector elements, projection data of the subject, generating corrected path-length estimates based on the projection data and one or more selected correction functions, and reconstructing at least one material density image based on the corrected path-length estimates. In this way, the fidelity of spectral information is improved, thereby increasing image quality for spectral computed tomography (CT) imaging systems, especially those configured with photon-counting detectors.

An X-ray CT system includes an X-ray tube, an X-ray detector and processing circuitry. The processing circuitry is configured to cyclically change energy of the X-rays during one rotation of the X-ray tube around a subject. The processing circuitry is configured to perform a process including a correcting process addressing a difference in a transmission amount between X-rays having first energy and X-rays having second energy, on at least one selected from between: a plurality of first projection data sets acquired when the X-rays having the first energy were radiated; and a plurality of second projection data sets acquired when the X-rays having the second energy were radiated. The processing circuitry is configured to reconstruct an image on the basis of a combined data set generated on the basis of a plurality of projection data sets including the projection data sets resulting from the process.

A method and system is disclosed for acquiring image data of a subject. The image data can be collected using an imaging system with a selected filtering characteristic. The image data can be reconstructed using reconstruction techniques.

A calibration method for an x-ray computerized tomography system and a method of tomographic reconstruction are provided. The calibration method includes steps of measuring at least one point spread function (PSF) at each of a plurality of points, compressing each PSF, and in one or more storing operations, storing the compressed PSFs in a computer-accessible storage medium. The PSF measurements are made in a grid of calibration points in a field of view (FOV) of the system. In the measuring step, an absorber is positioned at each of the calibration points, and an x-ray projection is taken at least once at each of those absorber positions. In the method of tomographic image reconstruction, projection data from an x-ray tomographic projection system are input to an iterative image reconstruction algorithm. The algorithm retrieves and utilizes a priori system information (APSI) The APSI comprises comprising point spread functions (PSFs) of all voxels in a voxelization of the field of view that are compressed in the form of vectors of parameters. For utilization, each retrieved vector of parameters is decompressed so as to generate a discretized PSF.

Dual-energy absorptiometry is used to estimate intramuscular adipose tissue metrics and display results, preferably as related to normative data. The process involves deriving x-ray measurements for respective pixel positions related to a two-dimensional projection image of a body slice containing intramuscular adipose tissue as well as subcutaneous adipose tissue, at least some of the measurements being dual-energy x-ray measurements, processing the measurements to derive estimates of metrics related to the intramuscular adipose tissue in the slice, and using the resulting estimates. Processing the measurements includes an algorithm which places boundaries of regions, e.g., a large region and a smaller region. The regions are combined in an equation that is highly correlated with intramuscular adipose tissue measured by quantitative computed tomography in order to estimate intramuscular adipose tissue.

A processor acquires at least one radiographic image of a subject including a plurality of compositions and acquires a composition ratio of the subject. The processor sets an attenuation coefficient of radiation used in a case in which the radiographic image is acquired for each pixel of the radiographic image according to the composition ratio. The processor performs image processing on the radiographic image using the set attenuation coefficient.

Systems and methods for medical imaging. The method may include acquiring a tube voltage switching waveform for a radiation source of a medical device. The method may include determining a tube current switching period based on the tube voltage switching waveform. The method may include determining a sampling period correlated with the tube current switching period. The method may include acquiring projection data according to the sampling period. The method may further include reconstructing an image based on the acquired projection data.

An X-ray CT data processing device is provided which when multi-energy photography is performed with an energy-separation type detector, and a subject is separated into a plurality of standard materials to create an image, estimates the appropriateness of posited standard materials, and in order to determine appropriate standard materials with satisfactory accuracy, processes CT data respectively acquired in a plurality of detection energy ranges to create a reconstructed image separated into predetermined standard materials. The X-ray CT data processing device is equipped with a standard material data calculating part which calculates energy-independent physical quantities for a plurality of standard materials respectively using different combinations of a plurality of the CT data, and creates a plurality of standard material data for the same standard material, and an appropriateness determination index creating part which creates an index for determining the appropriateness of the standard material, based on the plurality of standard material data calculated by the standard material data calculating part.