Flash-Effect in Radiotherapy of Tumors and the Problems of its Radiobiological Substantiation

Abstract

The published data regarding radiation therapy of tumors treatment with ultrahigh dose rate radiation has been analyzed. In 2014, the authors, among whom the most mentioned are Vincent Favaudon and MarieCatherine Vozenin, named it the flash effect. Note, however, that a member of our laboratory, S.V. Kozin in the collaboration with ITEP researchers, back in 1984, having studied the reaction of a graft tumors and the mice skin after the proton irradiation with the ultrahigh and ordinary dose rates, concluded that: ‘... an increase in the radiation dose rate to ultrahigh, without significantly changing radiation reactions of tumors, leads to the protection of the mice skin, which is associated with the manifestation of the effect of radiation-chemical absorption of oxygen. Thus, under certain conditions of radiotherapy, one can expect to receive a therapeutic gain due to use the radiation with a high dose rate’. Consideration of the expediency and possibility of using a single irradiation with a dose rate of tens of Gy/s in radiation therapy of tumors is now given a special attention. It can be considered as established that less damage to the skin, lungs, intestines, and some other tissues occurs in this case in comparison with the usual dose rates used for the radiation therapy. Moreover, a number of studies indicate an increase in radiation damage to the tumors, or at least a much smaller decrease in the degree of their damage. The radiobiological mechanisms remain unclear. The effect itself is of undoubted clinical and experimental interest and justifies the conduct of experimental and clinical studies, as well as the need to take it into account when developing new equipment for radiation therapy and dosimetry accompanying the treatment process.