Development of a hydrated electron dosimeter for radiotherapy applications: A proof of concept.
hydrated electron
radiation detector
radiolysis
Journal
Medical physics
ISSN: 2473-4209
Titre abrégé: Med Phys
Pays: United States
ID NLM: 0425746
Informations de publication
Date de publication:
Nov 2023
Nov 2023
Historique:
revised:
04
05
2023
received:
04
01
2023
accepted:
11
05
2023
medline:
6
11
2023
pubmed:
19
6
2023
entrez:
19
6
2023
Statut:
ppublish
Résumé
Hydrated electrons, which are short-lived products of radiolysis in water, increase the optical absorption of water, providing a pathway toward near-tissue-equivalent clinical radiation dosimeters. This has been demonstrated in high-dose-per-pulse radiochemistry research, but, owing to the weak absorption signal, its application in existing low-dose-per-pulse radiotherapy provided by clinical linear accelerators (linacs) has yet to be investigated. The aims of this study were to measure the optical absorption associated with hydrated electrons produced by clinical linacs and to assess the suitability of the technique for radiotherapy (⩽ 1 cGy per pulse) applications. 40 mW of 660-nm laser light was sent five passes through deionized water contained in a 10 Examination of the absorbance profiles showed clear absorption changes in the water when radiation pulses were delivered. Both the amplitude and the decay time of the signal appeared consistent with the absorbed dose and the characteristics of the hydrated electrons. By using literature value for the hydrated electron radiation chemical yield (3.0±0.3), we inferred doses of 2.1±0.2 mGy (10 MV FFF), 1.3±0.1 mGy (6 MV FFF), 0.45±0.06 mGy (6 MV) for photons, and 0.47±0.05 mGy (6 MeV) for electrons, which differed from EBT3 film measurements by 0.6%, 0.8%, 10%, and 15.7%, respectively. The half-life of the hydrated electrons in the solution was ∼ 24 By measuring 660-nm laser light transmitted through a cm-scale, multi-pass water cavity, we observed absorption transients consistent with hydrated electrons generated by clinical linac radiation. The agreement between our inferred dose and EBT3 film measurements suggests this proof-of-concept system represents a viable pathway toward tissue-equivalent dosimeters for clinical radiotherapy applications.
Sections du résumé
BACKGROUND
BACKGROUND
Hydrated electrons, which are short-lived products of radiolysis in water, increase the optical absorption of water, providing a pathway toward near-tissue-equivalent clinical radiation dosimeters. This has been demonstrated in high-dose-per-pulse radiochemistry research, but, owing to the weak absorption signal, its application in existing low-dose-per-pulse radiotherapy provided by clinical linear accelerators (linacs) has yet to be investigated.
PURPOSE
OBJECTIVE
The aims of this study were to measure the optical absorption associated with hydrated electrons produced by clinical linacs and to assess the suitability of the technique for radiotherapy (⩽ 1 cGy per pulse) applications.
METHODS
METHODS
40 mW of 660-nm laser light was sent five passes through deionized water contained in a 10
RESULTS
RESULTS
Examination of the absorbance profiles showed clear absorption changes in the water when radiation pulses were delivered. Both the amplitude and the decay time of the signal appeared consistent with the absorbed dose and the characteristics of the hydrated electrons. By using literature value for the hydrated electron radiation chemical yield (3.0±0.3), we inferred doses of 2.1±0.2 mGy (10 MV FFF), 1.3±0.1 mGy (6 MV FFF), 0.45±0.06 mGy (6 MV) for photons, and 0.47±0.05 mGy (6 MeV) for electrons, which differed from EBT3 film measurements by 0.6%, 0.8%, 10%, and 15.7%, respectively. The half-life of the hydrated electrons in the solution was ∼ 24
CONCLUSIONS
CONCLUSIONS
By measuring 660-nm laser light transmitted through a cm-scale, multi-pass water cavity, we observed absorption transients consistent with hydrated electrons generated by clinical linac radiation. The agreement between our inferred dose and EBT3 film measurements suggests this proof-of-concept system represents a viable pathway toward tissue-equivalent dosimeters for clinical radiotherapy applications.
Substances chimiques
Water
059QF0KO0R
Types de publication
Journal Article
Langues
eng
Sous-ensembles de citation
IM
Pagination
7245-7251Subventions
Organisme : MEDTEQ+
ID : 13-D FLASH dosimetrie
Organisme : Canada Research Chairs
Organisme : Natural Sciences and Engineering Research Council of Canada
Informations de copyright
© 2023 The Authors. Medical Physics published by Wiley Periodicals LLC on behalf of American Association of Physicists in Medicine.
Références
International Atomic Energy Agency. Radiation Oncology Physics. International Atomic Energy Agency; 2005.
Draganic IG, Draganic ZD. The Radiation Chemistry of Water. Vol 26. Elsevier; 1971.
Buxton GV, Greenstock CL, Helman WP, Ross AB. Critical review of rate constants for reactions of hydrated electrons, hydrogen atoms and hydroxyl radicals in aqueous solution. J Phys Chem Ref Data. 1988;17:513-886.
Spinks JWT, Woods RJ. An Introduction to Radiation Chemistry. Wiley; 1990.
Caër SL. Water radiolysis: influence of oxide surfaces on H2 production under ionizing radiation. Water. 2011;3:235-253.
Keene J. Absorption spectra in irradiated water and some solutions. Part II. Optical absorptions in irradiated water, Nature, Medium: X; Size: 1963:47-8.
Hart EJ, Boag JW. Absorption spectrum of the hydrated electron in water and in aqueous solutions. J Am Chem Soc. 1962;84:4090-4095.
Hart EJ, Fielden EM. The hydrated electron dosimeter. Book Section Procedures in Radiation Dosimetry: Liquid Chemical systems, Marcel Dekker, New York; 1970:331-335.
Elliot AJ, Bartels DM. The reaction set, rate constants and g-values for the simulation of the radiolysis of light water over the range 20 deg to 350 deg C based on information available in 2008. Report, 2009.
Baxendale JH, Busi F. The study of fast processes and transient species by electron pulse radiolysis. In: Proceedings of the NATO Advanced Study Institute held ay Capri, Italy, 7-18 September, 1981. Springer; 1982.
Sogandares FM, Fry ES. Absorption spectrum (340-640 nm) of pure water: photothermal measurements. Appl Opt. 1997;36:8699-8709.
Baxendale JH, Fielden EM, Capellos C, et al. Pulse Radiolysis. Nature. 1964;201:468-470.
Ma J. Ultrafast Electron Transfer in Solutions Studied by Picosecond Pulse Radiolysis. Thesis, 2015.
Draganic IG, Draganic ZD. Radiation Sources and Irradiation Techniques. Vol 26. book section 7, Elsevier; 1971:191-210.
Systems VM. TrueBeam Estx system: Specifications. Report, 2015.
Fielden EM, Hart EJ. Hydrated electron and thermoluminescent dosimetry of pulsed x-ray beams. Radiation Chemistry. Vol 81. American Chemical Society; 1968:585-594.
THORLABS, BB05-E02 Broadband Dielectric Mirrors: Specifications, Report Revision E, 2018.
THORLABS, DET10A2 Si Biased Detector: User Guide, Report, 2017.
Keysight, Keysight InfiniiVision 2000 X-Series Oscilloscopes: Programmer's Guide, Report, 2019.
Devic S, Tomic N, Lewis D. Reference radiochromic film dosimetry: review of technical aspects. Physica Med. 2016;32:541-556.