The concept of quasi-tissue-equivalent nanodosimeter based on the Glow Peak 5a/5 in LiF:Mg, Ti (TLD-100)

Abstract

We demonstrate the viability of the concept of using existing molecular nanostructures in thermoluminescent solid-state materials as solid-state nanodosimeters. The concept is based on mimicking radiobiology (specifically the ionization density dependence of double strand breaks in DNA) by using the similar ionization density dependence of simultaneous electron-hole capture in spatially correlated trapping and luminescent centres pairs in the thermoluminescence of LiF:Mg,Ti. This simultaneous electron-hole capture has been shown to lead to ionization density dependence in the relative intensity of peak 5a to peak 5 similar to the ratio of double-strand breaks to single-strand breaks for low energy He ions.

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

“…above hypothesis for the TL absorption mechanisms giving rise to composite peak 5 (3) . Due to the 'twoenergy transfer event' nature of peak 5a it is expected on purely statistical grounds that its relative intensity following HID irradiation would be increased relative to the same ratio following LID radiation due to the very high levels of dose (ionisation density) in the HCP track (28) . Model calculations of the ratio of peak 5a/5 following proton and alpha particle irradiation using a track structure approach have been carried out demonstrating enhanced intensity of peak 5a following HCP irradiation due to full population of TCs and LCs and de-activation of CCs at high ionisation density (28) .…”

“…Due to the 'twoenergy transfer event' nature of peak 5a it is expected on purely statistical grounds that its relative intensity following HID irradiation would be increased relative to the same ratio following LID radiation due to the very high levels of dose (ionisation density) in the HCP track (28) . Model calculations of the ratio of peak 5a/5 following proton and alpha particle irradiation using a track structure approach have been carried out demonstrating enhanced intensity of peak 5a following HCP irradiation due to full population of TCs and LCs and de-activation of CCs at high ionisation density (28) . The relative intensity of peak 5a to peak 5 thus represents a measure of ionisation density in a volume of nanometre dimensions (corresponding to the approximate size of the TC/LC complex), which may be correlatable with radiation damage in certain biological systems due to its conceptual similarity to the radiation-induced mechanisms of 'single-strand breaks' and 'double-strand breaks' in DNA (27) .…”

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

“…The TC giving rise to composite peak 5 is associated with a 4 eV optical absorption band and very strong conversion of peak 5a to peak 4 following 4 eV optical excitation and stepped (I m 2T stop ) annealing is the primary experimental evidence supporting the above hypothesis for the TL absorption mechanisms giving rise to composite peak 5 (11) . Owing to the 'two-energy transfer event' nature of peak 5a, it is expected on purely statistical grounds that its relative intensity following HID irradiation would be increased relative to the same ratio following LID radiation because of the very high levels of dose (ionisation density) in the HCP track (12) . Model calculations of the ratio of peak 5a/5 following Figure 1.…”