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.
