Method and apparatus for measuring the distribution of radioactivity

Claim 1

A method of measuring three-dimensional distribution of radioactivity, which comprises: measuring with a radiation sensor the intensity of radiation of an object containing radioactive nuclides while external radiation is radiated through said object from outside said object; imparting relative rotational and up and down movement between a source of said external radiation and said radiation sensor, and said object, while measuring said intensity of radiation at a plurality of segments during said up and down movement over the length of said object and at a plurality of regions within each of said segments during said rotational movement; discriminating the intensity of radiation thus measured into first radiation intensity based on said external radiation and second radiation intensity based on a radioactive nuclide in said object; determining a radiation absorption coefficient of said object on the basis of said first radiation intensity; and determining the distribution of radioactivity of said object in three dimensions on the basis of said radiation absorption coefficient and said second radiation intensity.

Claim 2

A method of measuring three-dimensional distribution of radioactivity, which comprises: measuring with a radiation sensor the intensity of radiation of an object containing radioactive nuclides while external radiation is radiated through said object from outside said object; imparting relative rotational and up and down movement between a source of said external radiation and said radiation sensor, and said object, while measuring said intensity of radiation at a plurality of segments during said up and down movement over the length of said object and at a plurality of regions within each of said segments during said rotational movement; discriminating the intensity of radiation thus measured into first radiation intensity based on said external radiation and second radiation intensity based on a radioactive nuclide in said object; determining a radiation absorption coefficient of said object on the basis of said first radiation intensity; and determining the distribution of radioactivity of said object in three dimensions on the basis of said radiation absorption coefficient and said second radiation intensity.

Claim 4

An apparatus for measuring three-dimensional distribution of radioactivity, which comprises: an external radiation source disposed outside an object, which object contains a radioactive nuclide; radiation sensor means disposed outside said object in such a manner as to interpose said object between said radiation sensor means and said external radiation source, for sensing radiation; means for imparting relative up and down movement between said external radiation source and radiation sensor means, and said object, to expose said object to said radiation source at a plurality of segments extending over the length of said object, and for imparting relative rotational movement between said external radiation source and radiation sensor means, and said object, to obtain output signals from said radiation sensor means at a plurality of regions within each of said segments during said rotational movement; means for discriminating the output signal from said radiation sensor means into first radiation intensity emitted from said external radiation source and second radiation intensity emitted from said radioactive nuclide inside said object; means for determining a radiation absorption coefficient of said object from said first radiation intensity; and radioactivity distribution calculation means for determining three-dimensional distribution of radioactivity within said object on the basis of said radiation absorption coefficient and said second radiation intensity.

Claim 5

An apparatus for measuring three-dimensional distribution of radioactivity, which comprises: an external radiation source disposed outside an object, which object contains a radioactive nuclide; radiation sensor means disposed outside said object in such a manner as to interpose said object between said radiation sensor means and said external radiation source, for sensing radiation; means for imparting relative up and down movement between said external radiation source and radiation sensor means, and said object, to expose said object to said radiation source at a plurality of segments extending over the length of said object, and for imparting relative rotational movement between said external radiation source and radiation sensor means, and said object, to obtain output signals from said radiation sensor means at a plurality of regions within each of said segments during said rotational movement; means for discriminating the output signal from said radiation sensor means into first radiation intensity emitted from said external radiation source and second radiation intensity emitted from said radioactive nuclide inside said object; means for determining a radiation absorption coefficient of said object from said first radiation intensity; and radioactivity distribution calculation means for determining three-dimensional distribution of radioactivity within said object on the basis of said radiation absorption coefficient and said second radiation intensity.