PROBLEM TO BE SOLVED: To correct a distortion of image due to non-linearity of a gradient field and a distortion of image due to ununiformity in magentostatic field.SOLUTION: Correction terms Cnm and ψnm for correcting a distortion of image due to ununiformity in magnetostatic field are added to constants Cnm and ψnm included in a spherical surface harmonics showing a non-linearity of a gradient field. Since the ununiformity in magnetostatic field is shown by the spherical surface harmonics similarly to the non-linearity of the gradient field, a magnetic field component showing the ununiformity in magnetostatic field and a magnetic field component showing the non-linearity of the gradient magnetic field may be included in the spherical surface harmonics by adding the correction terms Cnm and ψnm for correcting the distortion of image due to ununiformity in magnetostatic field to the constants Cnm and ψnm. Accordingly, not only the distortion of image due to the non-linearity of the gradient field but also the distortion of image due to the ununiformity in magnetostatic field is corrected.COPYRIGHT: (C)2014,JPO&INPIT【課題】勾配磁場の非線形性による画像の歪みと、静磁場不均一による画像の歪みとを補正する。【解決手段】勾配磁場の非線形性を表す球面調和関数に含まれている定数Cnmおよびψnmに、静磁場不均一による画像の歪みを補正するための補正項Cnm′およびψnm′を加える。静磁場不均一は勾配磁場の非線形性と同様に、球面調和関数で表すことができるので、定数Cnmおよびψnmに、静磁場不均一による画像の歪みを補正するための補正項Cnm′およびψnm′を加えることにより、球面調和関数に、静磁場の不均一性を表す磁場成分と、勾配磁場の非線形性を表す磁場成分とを含めることができる。したがって、勾配磁場の非線形性による画像の歪みだけでなく、静磁場不均一による画像の歪みも補正することができる。【選択図】図1
