US 12,292,492 B2
Method and apparatus for homogenizing magnetostatic field generated from superconducting magnet
Hajime Tanabe, Okayama (JP)
Assigned to CANON MEDICAL SYSTEMS CORPORATION, Otawara (JP)
Filed by CANON MEDICAL SYSTEMS CORPORATION, Otawara (JP)
Filed on Feb. 21, 2023, as Appl. No. 18/171,796.
Application 18/171,796 is a continuation of application No. PCT/JP2020/032031, filed on Aug. 25, 2020.
Prior Publication US 2023/0280426 A1, Sep. 7, 2023
Int. Cl. G01R 33/38 (2006.01); G01R 33/3815 (2006.01); G01R 33/3873 (2006.01)
CPC G01R 33/3873 (2013.01) [G01R 33/3815 (2013.01)] 4 Claims
OG exemplary drawing
 
1. A method of homogenizing, in a specific space, a magnetostatic field generated from a superconducting magnet by arranging a plurality of ferromagnetic bodies in the specific space, the specific space being subjected to the magnetostatic field, wherein a plurality of positions in the specific space at which the plurality of ferromagnetic bodies are arranged are predetermined, and each of the plurality of ferromagnetic bodies is selected from a plurality of specific ferromagnetic bodies each having a corresponding predetermined quantity of ferromagnetic material, the method comprising:
setting a first restriction condition including a corresponding first lower limit and a corresponding first upper limit for each of a plurality of error components of a magnetic field distribution in the specific space, and calculating a respective first optimum quantity of ferromagnetic material arranged at each position of the plurality of positions so that each error component, of the plurality of error components, satisfies the first restriction condition corresponding to the error component;
calculating, for each position of the plurality of positions, a first combination of at least one ferromagnetic body selected from the plurality of specific ferromagnetic bodies, the first combination having a first total corresponding ferromagnetic material amount closest to the first respective optimum quantity corresponding to the position among all possible combinations of the at least one ferromagnetic body;
calculating the plurality of error components that result when ferromagnetic material is arranged at each of the plurality of positions in quantities specified by the calculated first combination;
when, for each error component of the plurality of error components, the calculated error component is less than the first lower limit corresponding to the error component, setting a condition including a lower limit that is greater than the first lower limit and an upper limit that is greater than the first upper limit as a second restriction condition, and when the calculated error component is greater than the first upper limit corresponding to the error component, setting a condition including a lower limit that is less than the first lower limit and an upper limit that is less than the first upper limit as the second restriction condition, and calculating a respective second optimum quantity of ferromagnetic arranged at each position of the plurality of positions so that each error component, of the plurality of error components, satisfies the second restriction condition corresponding to the error component; and
calculating, for each position of the plurality of positions, a second combination of at least one ferromagnetic body selected from the plurality of specific ferromagnetic bodies, the second combination having a second total corresponding ferromagnetic material amount closest to the respective second optimum quantity corresponding to the position among all possible combinations of the at least one ferromagnetic body.