Iterative image reconstruction method, iterative image reconstruction program, and tomography apparatus

A non-transitory computer-readable storage medium storing instructions for performing iterative image reconstruction using a computer, the instructions causing one or more computer processors to perform operations according to a method comprising:

• performing first image reconstruction with an iterative method using first state variables to obtain a first reconstructed image;
• storing the first state variables and the first reconstructed image at an end of the first image reconstruction;
• judging whether or not to initialize the first state variables and the first reconstructed image before performing second image reconstruction:
• reading the first state variables and the first reconstructed image when it is judged not to initialize the first state variables and the first reconstructed image;
• and
• performing the second image reconstruction using second state variables and the first reconstructed image to obtain a second reconstructed image,
• wherein the first state variables depend on the number of iterations or a pixel position to determine update conditions for obtaining the first reconstructed image, and
• wherein the second state variables include at least a portion of the first state variables.

A tomography apparatus for performing iterative image reconstruction comprising:

• at least one storage device storing instructions;
• and
• at least one computer processor configured to execute the instructions and to cause the apparatus to perform operations comprising:
• performing first image reconstruction with an iterative method using first state variables to obtain a first reconstructed image;
• storing the first state variables and the first reconstructed image at an end of the first image reconstruction;
• judging whether or not to initialize the first state variables and the first reconstructed image before performing second image reconstruction:
• reading the first state variables and the first reconstructed image when it is judged not to initialize the first state variables and the first reconstructed image;
• and
• performing the second image reconstruction using second state variables and the first reconstructed image to obtain a second reconstructed image,
• wherein the first state variables depend on the number of iterations or a pixel position to determine update conditions for obtaining the first reconstructed image, and
• wherein the second state variables include at least a portion of the first state variables.

An iterative image reconstruction method of reconstructing an image using an iterative method, comprising:

• performing first image reconstruction with the iterative method using first state variables to obtain a first reconstructed image;
• storing the first state variables and the first reconstructed image at an end of the first image reconstruction;
• reading the first state variables and the first reconstructed image;
• and
• performing second image reconstruction using second state variables and the first reconstructed image to obtain a second reconstructed image,
• wherein the first state variables depend on the number of iterations or a pixel position to determine update conditions for obtaining the first reconstructed image,
• wherein the second state variables include at least a portion of the first state variables,
• wherein the second state variables include third state variables different from the first state variables,
• wherein a steepest descent method or a Newton's method is used as an optimization algorithm for the first and second image reconstructions, and
• wherein the first state variables include a data term and a penalty term.