Calculation of the effective UV dose absorbed by a flow of blood

Usually radiation damages in biological tissues are evaluated by the expose dose D0D0 which is electromagnetic energy per unit area measured at the surface of a sample. We demonstrate that the appropriate measure of radiation damage is the effective dose DaDa which accounts for attenuation of electromagnetic field in the tissue. We treat a whole blood as strongly absorbing and viscous liquid and evaluate the ratio Da/D0Da/D0 in the process of UV irradiation of human blood perfused through a quartz cuvette. It is shown that because of absorption and parabolic profile of velocities of the blood flow in a rectangular cuvette, this ratio is small. An exponential decay of the intensity of the radiation means strong decrease of the probability of the damage a UV photon may produce on its mean free path. Numerical estimates done for the parameters of the procedure of blood retransfusion in ISOLDA device shows the decrease of the effective dose by up to 50 times as compared to the exposure dose.