Cluster pattern analysis of energy deposition sites for the brachytherapy sources¹⁰³Pd,¹²⁵I,¹⁹²Ir,¹³⁷Cs, and⁶⁰Co

Abstract

Analysing the pattern of energy depositions may help elucidate differences in the severity of radiation-induced DNA strand breakage for different radiation qualities. It is often claimed that energy deposition (ED) sites from photon radiation form a uniform random pattern, but there is indication of differences in RBE values among different photon sources used in brachytherapy. The aim of this work is to analyse the spatial patterns of EDs from 103Pd, 125I, 192Ir, 137Cs sources commonly used in brachytherapy and a 60Co source as a reference radiation. The results suggest that there is both a non-uniform and a uniform random component to the frequency distribution of distances to the nearest neighbour ED. The closest neighbouring EDs show high spatial correlation for all investigated radiation qualities, whilst the uniform random component dominates for neighbours with longer distances for the three higher mean photon energy sources (192Ir, 137Cs, and 60Co). The two lower energy photon emitters (103Pd and 125I) present a very small uniform random component. The ratio of frequencies of clusters with respect to 60Co differs up to 15% for the lower energy sources and less than 2% for the higher energy sources when the maximum distance between each pair of EDs is 2 nm. At distances relevant to DNA damage, cluster patterns can be differentiated between the lower and higher energy sources. This may be part of the explanation to the reported difference in RBE values with initial DSB yields as an endpoint for these brachytherapy sources.

Trastuzumab-Modified Gold Nanoparticles Labeled with 211At as a Prospective Tool for Local Treatment of HER2-Positive Breast Cancer

“…This method is effective and commonly used for curing of solid tumors, such as those involving the prostate, breast, liver, and skin [1]. Brachytherapy usually utilizes sources of 50–100 μm in size, such as 125 I [2], 106 Ru [3], 192 Ir [4], 131 Cs [5,6], 137 Cs [7,8], or 103 Pd [9,10] radioactive seeds, and 90 Y immobilized in resin or glass microspheres [11,12,13]. In the case of breast cancer, brachytherapy has found application as part of a post-surgery partial irradiation strategy for patients undergoing lumpectomy [14].…”

Energy deposition clustering as a functional radiation quality descriptor for modeling relative biological effectiveness

“…22 The update included the correction of an erroneous overestimation of the mean free path for electrons and an erroneous ejection angle from ion interactions, respectively. All data in this paper are based on the corrected code which has been already applied in microdosimetric analysis 23,24 and energy deposition cluster pattern analysis 25,26 of brachytherapy sources.…”

“…Derivation of the photon spectra and the transport simulation for these sources has been described elsewhere. 25 The 60 Co photon source was also the same as that used in Ref. 25 where monoenergetic 1.25 MeV photon beam was used to calculate the Compton electron spectrum which in turn became the electron track generator.…”

“…25 The 60 Co photon source was also the same as that used in Ref. 25 where monoenergetic 1.25 MeV photon beam was used to calculate the Compton electron spectrum which in turn became the electron track generator. It is worth noting that only the methodology from the referred publication is kept but all track data were recalculated with the updated version of LIonTrack for this work.…”

Corrigendum: Cluster pattern analysis of energy deposition sites for the brachytherapy sources103Pd,125I,192Ir,137Cs and60Co (2014Phys. Med. Biol.595531–43)

“…Our aim in Villegas et al (2014) was to analyse the spatial distribution of energy deposition (ED) sites for several common radiation qualities used in brachytherapy. Track structure data were obtained through simulations with a modified version of the Monte Carlo (MC) code PENELOPE v.2008(Fernández-Varea et al 2012.…”