Scatter correction method and apparatus for computed tomography imaging
AssigneeToshiba Medical Systems Corporation
InventorMichael D. Silver
Life of this patent
Estimating the term…
Abstract
A method and apparatus to correct for scatter in projection data by successive approximations of a primary-beam estimate and a scatter estimate. The scatter estimate is calculated by convolving a scattering function, which is a function of the primary-beam estimate, with a smoothing function that includes Rayleigh scattering and Compton scattering terms. The scattering function is greater than zero in the limit that the primary-beam estimate goes to zero. The projection data can be X-ray computed tomography projection data, and the choice of scattering function has the benefit of reducing dark-band artefacts in reconstructed computed tomography images.
Claims18
An apparatus for scatter correction of projection data, the apparatus comprising:
- processing circuitry configured to
- calculate a primary-beam estimate Pn, and
- calculate a scatter estimate Sn using a convolution between a scattering function, SF(Pn), and a smoothing function G,
- wherein Pn is a current primary-beam estimate, Sn is a current scatter estimate, and SF(Pn) is a predetermined scatter function that is a function of the current the primary-beam estimate and is greater than zero over the range 0≦Pn<1.
A method of correcting for scatter in projection data using processing circuitry, the method comprising:
- calculating, by the processing circuitry, a primary-beam estimate Pn;
- calculating a scatter estimate Sn using a convolution between a scattering function of the primary-beam estimate, SF(Pn), and a smoothing function G,
- wherein Pn is a current value of the primary-beam estimate, Sn is a current value of the scatter estimate, and SF(Pn) is a predetermined scatter function that is a function of the current primary-beam estimate and is greater than zero over the range 0≦Pn<1.
An imaging apparatus for computed tomography, comprising:
- a radiation source configured to emit radiation toward an image object;
- a radiation detector configured to detect the radiation transmitted from the radiation source and through the image object to generate projection data representing an intensity of the radiation at the radiation detector;
- and
- scatter-correction processing circuitry configured to
- calculate a primary-beam estimate Pn using the projection data, wherein Pn is a current value of the primary-beam estimate, and
- calculate a scatter estimate Sn using a convolution between a scattering function of the primary-beam estimate SF(Pn) and a smoothing function G, wherein Sn is a current value of the scatter estimate, and SF(Pn) is a predetermined scatter function that is a function of the current primary-beam estimate and is greater than zero over the range 0≦Pn<1;
- and
- image-reconstruction processing circuitry configured to reconstruct a tomographic image from the primary-beam estimate.
Dependencies are inferred from the claim text.