The Evaluation of Optimum Radiation Dose to Prevent Transfusion-Associated Graft-Versus-Host Disease Among the Iranian Population

Transfusion-associated graft-versus-host disease is a complication being mortal in 90% of cases. Today, Co-60 devices are utilized for the suppression of the lymphocytes to prevent this complication. Due to problems such as radioactive source age, problems in source replacement, and protection risks, we sought to replace a linear accelerator for this purpose and carefully determinate the X-ray dose and other settings.
First, the venous blood of the right-handed people with blood group O was exposed to different radiation doses of Linac and diluted. The proliferative responses of the exposed cells were examined by MTT assay and TB in comparison with controls after 48h. The average percentage of cell survival at each delivered dose and the required dose of radiation for the inhibition of lymphocyte proliferation were checked and the optimal dose of radiation was obtained as 25 Gy in a special radiation condition.
The results indicated that the irradiation with 25 Gy at 3.5 Gy/min in the internal mid-plan by compact 6MV for 30*30-field size at an 8 cm-distance of the samples to the source and 1370-monitor unit could completely suppress the lymphocytes. Under the same condition and 1096-monitor unit for total 20 Gy, we did not find optimal results.
In this research, we found that a linear accelerator in a specific exposure condition is a suitable alternative for Cobalt-60 sources and the above-mentioned condition of irradiation can be used to overcome the GVHD concern.