Particle track structure and its correlation with radiobiological endpoint

Abstract

One of the possible ways to classify track structures is application of the conventional partition techniques of analysis of multidimensional data to the track structure. Using these cluster algorithms this paper attempts to find characteristics of radiation reflecting the spatial distribution of ionizations in the primary particle track. Absolute frequency distributions of clusters giving the mean number of clusters produced by radiation per unit of deposited energy have been computed for radiation of different qualities. The results were compared with the published experimental data of cell inactivation. For particular biological objects the critical properties of radiation correlating with the cell inactivation can be found and it seems that the occurrence of a cluster of at least four ionizations formed in a domain of approximately 2-3 nm correlates with the induction of double strand break.

Molecular and cell models of biological effects of heavy ion radiation

“…damage that may be most relevant to biological effects (Brenner and Ward 1992;Goodhead and Brenner 1983;. Goodhead and Nikjoo 1989;Michalik 1991;Nikjoo et al 1994a). Attempts have been made also to evaluate from these simulated tracks the yields of SSB and DSB for various radiation types, either from direct ionizations in the DNA, indirect effects from nearby hydroxyl radicals or combinations of both (Charlton et al 1989;Chatterjee and Holley 1993;Ito 1987;Nikjoo et al 1994b;Terrissol and Pomplun 1994).…”

Track structure simulations of proximity functions in liquid water using the Geant4-DNA toolkit

“…Besides modern approaches to model the relative biological effectiveness (RBE), 61 many theoretical predictions of RBE are still based on microdosimetric concepts, such as the dose-weighted lineal energy in micro-or nano-meter size targets 62,63 or various clustering analysis of ionisations 64,65 or energy deposition 66 at the nanoscale. Proximity functions can be used to calculate the RBE in the context of the TDRA.…”

Cluster analysis of HZE particle tracks as applied to space radiobiology problems

“…The other steps of the algorithm are identical to the ones in [4]. The virtual center of a cluster is calculated asx…”

“…The frequency distribution depends on the cluster size p and the mean free path λ i of a charged particle in the medium. Figure 1 shows the scheme of the improved clustering algorithm compared to the one developed in [4]. An example of the improved algorithm applied to a 1 GeV/nucleon iron ion track in liquid water is shown in Fig.…”

“…One of the widely used techniques for clustering data processing is the K-means method [2,3]. The application of this method for ionization density analysis in clusters comparable to the DNA molecule size is well demonstrated in [4] for low-Z particles. However, the implementation of K-means for HZE atomic nuclei of GCR requires modiˇcation of this algorithm.…”