A Multi-port Low-Fluence Alpha-Particle Irradiator: Fabrication, Testing and Benchmark Radiobiological Studies

Abstract

A new multi-port irradiator, designed to facilitate the study of the effects of low fluences of alpha particles on monolayer cultures, has been developed. The irradiator consists of four individual planar (241)Am alpha-particle sources that are housed inside a helium-filled Lucite chamber. Three of the radioactive sources consist of 20 MBq of (241)Am dioxide foil. The fourth source, used to produce higher dose rates, has an activity of 500 MBq. The four sources are mounted on rotating turntables parallel to their respective 1.5-microm-thick Mylar exit windows. A stainless steel honeycomb collimator is placed between the four sources and their exit windows by a cantilever attachment to the platform of an orbital shaker that moves its table in an orbit of 2 cm. Each exit window is equipped with a beam delimiter to optimize the uniformity of the beam and with a high-precision electronic shutter. Opening and closing of the shutters is controlled with a high-precision timer. Custom-designed stainless steel Mylar-bottomed culture dishes are placed on an adapter on the shutter. The alpha particles that strike the cells have a mean energy of 2.9 MeV. The corresponding LET distribution of the particles has a mean value of 132 keV/microm. Clonogenic cell survival experiments with AG1522 human fibroblasts indicate that the RBE of the alpha particles compared to (137)Cs gamma rays is about 7.6 for this biological end point.

Modeling radiation-induced cell death: role of different levels of DNA damage clustering

“…The results are shown in Fig. 3, which reports survival curves for V79 cells exposed to alpha particles of 20, 28, 50, 90 and 120 keV/lm (compared with experimental data taken from: Cox et al 1977 for 20 and 50 keV/lm; Thacker et al 1979 for 28 and 90 keV/lm; Phoenix et al 2009 for 120 keV/lm) and for AG1522 cells exposed to 132 keV/lm alpha particles (compared with data from Neti et al 2004). Analogous results, which were not reported in the figure for the sake of clarity, were found for V79 cells exposed to 70 keV/lm alpha particles.…”

“…1 shows survival curves for V79 cells exposed to c-rays, V79 cells exposed to X-rays, AG1522 cells exposed to c-rays and AG01522 cells exposed to X-rays. The lines are simulation results, whereas the points are experimental data taken from the literature: Thacker et al (1979), Belli et al (2008) and Phoenix et al (2009) for V79 cells exposed to c-rays; Folkard et al (1996) for V79 cells exposed to X-rays; Neti et al (2004) for AG1522 cells exposed to c-rays; and Chaudhary et al (2014) for AG01522 cells exposed to X-rays. The curves reported in Fig.…”

Biological Response to Nonuniform Distributions of210Po in Multicellular Clusters

“…Various groups have reported RBE values for α particles that range from 2-20 depending on the reference radiation, biological end point, and cell type (26)(27)(28)(29)(30). Among them are the RBEs at D 37 for 241 Am α particles, compared to acute 137 Cs γ rays, of 7.6 and 12 for AG1522 cells (31) and DU-145 cells (32), respectively. Table 4 indicates that the experimental D 37 depends on the percentage of cells in the cluster that were radiolabeled.…”

Mechanisms of resistance to high and low linear energy transfer radiation in myeloid leukemia cells

“…The mean ␣-particle energy is estimated to be 2.9 MeV incident to the surface with a full-width half-maximum value of ϳ 0.9 MeV, corresponding to a mean LET of 132 keV/m. 13 For spherical cells, this corresponds to a conservative estimated nuclear dose of 1 Gy for every 4 nuclear ␣-particle traversals. 14 Any differences in dose to specific cell clones were accounted for by adjusting the number of ␣-particle traversals for a given exposure time according to measured nuclear area (supplemental Figure 4, available on the Blood Web site; see the Supplemental Materials link at the top of the online article).…”