A new method was developed based on calculating the absorption coefficients,
self-absorption coefficients and transmission coefficients of the gamma-photons
emitted by different radioisotopes for evaluating gamma dose equivalent rates,
at 1 meter from various cylindrical radioactive solution sources utilized in medicine,
in a biological tissue. Results obtained were compared with data given in literature.
The influence of the radioisotope half-life and gamma-photon energy and number of
photons per disintegration on the gamma dose equivalent rate, effective dose and threshold
initial activity of the considered solution sources was studied.