Image forming apparatus and image forming method

摘要

An image forming apparatus has acoustic transducers; and an image processing unit which calculates intensity of acoustic waves irradiated from regions inside a subject respectively by processing received signals, which are output from the acoustic transducers, by a Fourier-domain method. The image processing unit includes: a coefficient memory which stores coefficients computed in advance, the coefficient being a value determined only by a position of the acoustic transducer, position of the region and a time of receipt of the acoustic wave; a multiplier unit which multiplies the received signal of the acoustic transducer by the corresponding coefficient; and a voxel memory which accumulates multiplication results of the multiplier unit for each region.

主权项

1. An image forming apparatus for creating image data from information on an interior of a subject based on acoustic waves irradiated from the interior of the subject, comprising:
a plurality of acoustic transducers which receive acoustic waves and convert the acoustic waves into received signals; and an image processing unit which obtains intensity of acoustic waves irradiated from a plurality of regions inside the subject respectively by processing the received signals, which are output from said plurality of acoustic transducers, wherein said image processing unit includes:
a coefficient memory which stores coefficients determined by a position of a corresponding acoustic transducer, a position of a region a time of receipt of the acoustic wave, and variables of a Fourier transform having wave number dimensions;a multiplier unit which obtains a coefficient corresponding to the acoustic transducer from said coefficient memory, and multiplies a received signal which is output from the acoustic transducer by the coefficient, for each acoustic transducer; anda voxel memory which accumulates multiplication results of said multiplier unit for each region,wherein a coefficient A is obtained by a following formula, when (xi,yi) represents a position of the acoustic transducer i, (xj,yj,zj) represents a position of a region j in the subject, and t* represents a time of receipt of the acoustic wave:A⁡(xj,yj,zj⁢:⁢⁢xi,yi,t*)=1(2⁢π)3⁢∫∫∫-∞∞⁢2⁢w⁢⁢sgn⁡(w)u2+v2+w2⁢exp⁢{ⅈ⁡[u⁢(xi-xj)+v⁡(yi-yj)-wzj+sgn⁡(w)⁢u2+v2+w2⁢t*]}⁢ⅆu⁢ⅆv⁢ⅆw[Expression⁢⁢1] where u, v and w are variables of a Fourier transform, and sgn(w) is a function which is 1 when w>0, is 0 when w=0, and is −1 when w<0.