RBE of "Prometeus" Facility Protons for Irradiation of Tumor Cells in vitro with One and Three Fields

The study was aimed to the biological effectiveness of the proton scanning beam of the first Russian medical facility. The clonogenic assay of B-16 tumor cells was used as a test system. Cell irradiation was carried out in a suspension condition in a water phantom. Single and three-field exposures were studied. The dose interval was 2-8 Gy. The energy range from 47.5 to 92.0 MeV was used for the Bragg peak formation. The relative biological effectiveness of protons comparing to gamma-rays was 1.2 for single-field and 1.5 for three-field irradiation. The results obtained agree with literature data related to the used cell culture (B-16) and linear energy transfer range (3÷8 keV/µm)

Development of an approach to assess critical doses and dose rates for cultivated plants

The aim of this work is to develop methods for an assessment of critical doses and dose rates that can result in significant radiation-induced effects in agrocenoses. This is realized on an example of cultivated plants which are one of the main components of agroecosystems. Available information on dose dependences in such umbrella endpoints as reproduction, survival, morbidity, alterations in morphological and biochemical processes, genetic effects in crops, vegetables, fruit trees, etc are gathered from papers issued mainly in Russian scientific press during last 50 years. Data are maintained as database in MS Access that contains about 10000 records at the moment. As critical exposure values, doses are considered producing 50% changes of biological effect at acute impact (ED50), or dose rates resulting in 10% changes at chronic exposure of plants (EDR10). The critical doses and dose rates for agrocenosis estimated from available information on reproduction and survival are presented here. Primary data are assesed for their quality according to several criteria. Three models (linear, logariphmic, logistic) for dose-effect relationship are tested for an applicability to fit a dose-effect dependence taking account of their goodness-of-fit and robustness of ED50 and EDR10 estimates