Method and apparatus for measuring distribution of radioactive nuclide in subject

A method of measuring a distribution of a radioactive nuclide in a subject, comprising

• preparing a data table for density measurement which indicates a relationship between the density of a subject sample and an intensity of .beta.-ray radiation emitted from .sup.147 Pm and having passed through said subject sample,
• preparing a data table for compensation of self-absorption which indicates a relationship between the density of said subject sample and a self-absorptivity of said subject sample for radiation from .sup.14 C as a second nuclide present in said subject sample,
• uniformly irradiating said subject sample with ionizing .beta.-ray radiation from .sup.147 Pm, said subject sample containing .sup.14 C distributed therein, and measuring the intensity of the ionizing radiation from .sup.147 Pm having passed through said subject sample for density measurement,
• comparing measured results and data in said data table for density measurement to determine densities of respective parts of said subject sample,
• measuring a distribution of the intensity of ionizing radiation for a subject assay emitted from .sup.14 C in said subject sample, and
• measuring the amounts of .sup.14 C in said subject sample based on the densities of respective parts of said subject sample, said data table for compensation of self-absorption, and the distribution of the intensity of said ionizing radiation for subject assay.

An apparatus for measuring a distribution of a radioactive nuclide in a subject, comprising

• a density-measurement data table memory storing a data table for density measurement which indicates a relationship between a density of a subject sample and an intensity of .beta.-ray emitted from .sup.147 Pm and having passed through said subject sample,
• a self-absorption compensating data table memory storing a data table for compensation of self-absorption which indicates a relationship between the density of said subject sample and a self-absorptivity of said subject sample for radiation from .sup.14 C,
• density-measurement ionizing radiation reading means for uniformly irradiating ionizing radiation from .sup.147 Pm upon said subject sample which contains .sup.14 C distributed therein, and for reading the intensity of the ionizing radiation emitted from .sup.147 Pm after it has passed through said subject sample,
• density measuring means for comparing results read by said density-measurement ionizing radiation reading means and data in said density-measurement data table memory to determine densities of respective parts of said subject sample,
• subject-assay ionizing radiation reading means for reading a distribution of the intensity of ionizing radiation emitted from .sup.14 C said subject sample,
• self-absorptivity reading means for, based on the density of a certain part of said subject sample determined by said density measuring means, reading a self-absorptivity corresponding to the density of said certain part from said self-absorption compensating data table memory, and
• ionizing radiation intensity compensating means for compensating the distribution of the intensity of the ionizing radiation read by said subject-assay ionizing radiation reading means based on the self-absorptivity read by said self-absorptivity reading means.