Thermoluminescence solid-state nanodosimetry--the peak 5A/5 dosemeter

Abstract

The shape of composite peak 5 in the glow curve of LiF:Mg,Ti (TLD-100) following 90 Sr/ 90 Y beta irradiation, previously demonstrated to be dependent on the cooling rate used in the 4008 8 8 8 8C pre-irradiation anneal, is shown to be dependent on ionisation density in both naturally cooled and slow-cooled samples. Following heavy-charged particle high-ionisation density (HID) irradiation, the temperature of composite peak 5 decreases by ∼58 8 8 8 8C and the peak becomes broader. This behaviour is attributed to an increase in the relative intensity of peak 5a (a low-temperature satellite of peak 5). The relative intensity of peak 5a is estimated using a computerised glow curve deconvolution code based on first-order kinetics. The analysis uses kinetic parameters for peaks 4 and 5 determined from ancillary measurements resulting in nearly 'single-glow peak' curves for both the peaks. In the slow-cooled samples, owing to the increased relative intensity of peak 5a compared with the naturally cooled samples, the precision of the measurement of the 5a/5 intensity ratio is found to be ∼15 % (1 SD) compared with ∼25 % for the naturally cooled samples. The ratio of peak 5a/5 in the slow-cooled samples is found to increase systematically and gradually through a variety of radiation fields from a minimum value of 0.13+ + + + +0.02 for 90 Sr/ 90 Y low-ionisation density irradiations to a maximum value of ∼0.8 for 20 MeV Cu and I ion HID irradiations. Irradiation by low-energy electrons of energy 0.1-1.5 keV results in values between 1.27 and 0.95, respectively. The increasing values of the ratio of peak 5a/5 with increasing ionisation density demonstrate the viability of the concept of the peak 5a/5 nanodosemeter and its potential in the measurement of average ionisation density in a 'nanoscopic' mass containing the trapping centre/luminescent centre spatially correlated molecule giving rise to composite peak 5.

Calculation of complex DNA damage induced by ions

“…First, it can be compared with Monte Carlo simulations done for the purposes of nanodosimetry [26]. Second, it will be possible to compare this dependence (correspondingly modified) with dosimetric experiments [27,28]. At this point, it is possible to use the dependence shown in Fig.…”

“…6 is shorter than 10 nm. Even though, this size is about 1000 times smaller (for glial cells) than that of the cell's nucleus [7]; it plays a significant role in calculations of the probability of cell death and will be critical for the comparisons with nano-dosimetric data [26][27][28]31].…”

“…Then, we can integrate the radial-dependent probability of the complex damage given by Eq. (1) (for appropriate N (ρ) dependence) with this density distribution: This gives the number of clusters of ν lesions per nm, which can be compared with the nano-dosimetric experiments [26][27][28]31] and can give still another relation for unknown parameters such as Γ and the dependence of lethality of damage on the order of cluster ν.…”

Influence of Ultraviolet and Electron Radiation on Photoelectron Emission Spectra of Lead Sulfide Nanoparticles Embedded in a Matrix of Zirconium Oxide

“…One of the approaches is to measure number of ionizations caused by radiation in gaseous targets of millimetric dimensions and recalculate the result to the biological nanometric sites using scaling procedure [1]. Another approach is to study thermoluminescent recombination between charge carriers trapped in centers of ~2 nm dimensions under influence of ionizing radiation [2].…”

Mysteries of LiF TLD response following high ionisation density irradiation: nanodosimetry and track structure theory, dose response and glow curve shapes

“…Peak 5a, a low-temperature component of composite peak 5, is believed to arise from joint e -h capture in the TC/LC molecular complex and this 'two-energy-transfer' event is preferred at HID compared with the 'single-energy transfer' event giving rise to peak 5 (electron capture only) (3) . It has been suggested that the ratio 5a/5 can provide a nanodosimetric measurement of average ionisation density in the 'nanoscopic' volume comprising the TC/LC molecular complex giving rise to peaks 5a and 5 (4) ; (3) the decrease in the relative efficiency following HID/HCP irradiation, which has been modelled by track structure theory (TST) with some degree of success (5) . However, the TST premise that the radiation action of HCPs is exclusively due to the dose delivered by the secondary electrons liberated by the HCP slowing down has never been subjected to a stringent test.…”