Radiological imaging apparatus and transmission imaging method

Abstract

A radiological imaging apparatus includes an imaging apparatus having an opening for insertion of a bed thereinto, and an attenuation correction data creating device. The imaging has a plurality of radiation detectors disposed around the opening and a plurality of gamma ray generation units residing between the opening and the radiation detectors disposed at a position nearest to the opening and being placed in a longitudinal direction of the bed. Each γ-ray generation unit has γ-ray sources of single photon emission nuclear species and is arranged to externally radiate a γ-ray alternately from either one of the γ-ray generators toward the opening. The data creator prepares attenuation correction data based on a detection signal as output from the radiation detector due to the incoming radiation of γ-rays from the γ-ray generator.

1 . A radiological imaging apparatus comprising:
 an imaging apparatus with an opening being formed for insertion of a bed thereinto; and   an attenuation correction data creation device,   wherein said imaging apparatus includes a plurality of radiation detectors disposed around said opening and a plurality of gamma ray generation means residing between said opening and said radiation detectors as placed at a position nearest to said opening and being disposed in a longitudinal direction of said bed,   wherein said plurality of gamma ray generation means respectively comprises gamma ray sources each being a single photon emission nuclear species and being arranged to alternately radiate a gamma ray from any one of said gamma ray generation means to its outside in propagation for said opening,   wherein said attenuation correction data creation device is operative to create attenuation correction data based on a detection signal as output from said radiation detectors due to incoming radiation of the gamma ray to be emitted from said gamma ray generation means.   
   
   
       2 . The radiological imaging apparatus according to  claim 1 , wherein each said gamma ray generation means has a housing which is a radiation shield surrounding said gamma ray source, and wherein said housing forms a release window for releasing said gamma ray emitted from said gamma ray source toward said opening. 
   
   
       3 . The radiological imaging apparatus according to  claim 2 , wherein said plurality of gamma ray generation means include a first gamma ray generator means having a first said gamma ray source and a second gamma ray generator means having a second said gamma ray source, and wherein said imaging apparatus further comprises:
 a radiation source holding member for installation of respective ones of said gamma ray sources; and   a drive device for causing said radiation source holding member to circulate around said opening and rotate within said housing.   
   
   
       4 . The radiological imaging apparatus according to  claim 3 , wherein said first gamma ray source is disposed at a position different from that of said second gamma ray source in the rotation direction of said radiation source holding member. 
   
   
       5 . The radiological imaging apparatus according to  claim 3 , wherein while letting a length of an installation range of said radiation detectors in said longitudinal direction of said bed be d, said first gamma ray source and said second gamma ray source are disposed at positions of from d/3 to 2d/3 from a one end of said radiation detectors in said longitudinal direction of said bed. 
   
   
       6 . The radiological imaging apparatus according to  claim 2 , wherein said plurality of gamma ray generation means include a first gamma ray generator means having a first said gamma ray source, a second gamma ray generator means having a second said gamma ray source and a third gamma ray generator means having a third said gamma ray source, and wherein said imaging apparatus further comprises:
 a radiation source holding member for installation of respective ones of said gamma ray sources; and   a drive device for causing said radiation source holding member to circulate around said opening and rotate within said housing, wherein   while letting a length of an installation range of said radiation detectors in said longitudinal direction of said bed be d, said first gamma ray source and said second gamma ray source and said third gamma ray source are disposed at positions of from d/6 to 5d/6 from one end of said radiation detectors in said longitudinal direction of said bed.   
   
   
       7 . A radiological imaging apparatus comprising:
 an imaging apparatus with an opening being formed for insertion of a bed thereinto; and   an attenuation correction data creation device,   wherein said imaging apparatus includes a plurality of radiation detectors disposed around said opening and a gamma ray generation means being a single photon emission nuclear species and having a plurality of gamma ray sources disposed between said opening and said radiation detectors disposed nearest to said opening and a plurality of release windows for radiating gamma rays from said gamma ray sources toward said opening;   wherein said gamma ray generation means are arranged to alternately radiate said gamma ray from either one of said release windows;   wherein said attenuation correction data creation device is operable to create attenuation correction data based on a detection signal as output from said radiation detector due to incoming radiation of said gamma ray to be emitted from said gamma ray generation means.   
   
   
       8 . The radiological imaging apparatus according to  claim 7 , wherein said gamma ray generation means comprises a housing surrounding said plurality of gamma ray sources and shielding said gamma ray to be radiated in a region other than said release windows. 
   
   
       9 . The radiological imaging apparatus according to  claim 8 , further comprising a plurality of radiation shields for shielding, when said plurality of point radiation sources are at positions other than said release windows respectively, the gamma rays as emitted from said point radiation sources to thereby prevent said rays from being released out of said release windows and a radiation source holding member with said plurality of gamma ray sources being attached thereto and being rotatable within said housing, wherein
 said plurality of gamma ray sources are disposed so that respective ones are at different positions in the rotation direction of said radiation source holding member.   
   
   
       10 . The radiological imaging apparatus according to  claim 8 , further comprising:
 a support member for supporting said housing;   a rotator with said support member being attached thereto, for rotating to thereby cause said support member to revolute around said opening; and   a drive device for rotation driving of said rotator.   
   
   
       11 . The radiological imaging apparatus according to  claim 9 , further comprising:
 an internal gear with a rack being formed therein; and   a gearwheel provided at said radiation source holding member for being engaged with said rack to rotate.