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Detection of low- and high-LET radiation with alanine
Radiat. Phys. Chem. Voi.28, No.5/6, p.535, 1986
0146-5724/86 $3.00 + 0.00
Int. J. Radiat. Appl.lnstrum. Part C Printed in Great Britain.
Copyright(~)1986. PergamonJournals Ltd
All rights reserved
Detection of Low- and High-LET Radiation with Alanine
Johnny W. Hansen and Kjeld J. Olsen Accelerator Department, Ris~ National Laboratory, DK 4000 Roskilde, Denmark Department of Radiophysics, University Hospital of Copenhagen, DK 2730 Herlev, Denmark
SUMMARY Production and accumulation of free radicals in some crystalline biomolecules are relatively stable products of a sequence of events i n i t i a t e d by the absorption of radiation energy. Free radicals can qualitatively and quantitatively be analyzed by means of electron spin resonance, ESR, spectroscopy, and the measure of radical concentration may thus be used for dosimetry purposes. For practical application in radiation dosimetry the crystalline amino acid L-u-alanine is pressed into pellets, 4.5 mm in diameter by 2 mmin thickness, with 5% by weight polyvinylpyrro]idinone (C4HBNO-CH=CH2)n added as a binding material. The dose meter is robust and easy to handle, and the read-out technique is non-destructive with respect to the measuredsignal. The useful dose range is from 0.5 to lO5 Gy with ± 0.4% reproducibility of measurement. Hence, the dose meter can be used in radiation processing of food, for s t e r i l i z a t i o n , as a postal dose meter for intercalibration of radiation f a c i l i t i e s , for control and documentationof radiation therapy doses, and as a personal accident dose meter for radiation workers. Alanine is also suitable for use in high-LET dosimetry as the relative effectiveness, RE, has been found to decrease by only a factor of 4 over a LET-range of four orders of magnitude, and because the dose-responsemaintains linearity also for the very densely ionizing particles.
RE
is the response to high-LET radiation relative to that of low-LET radiation, e.g. 60Co y-rays and fast electrons, for the sameabsorbedenergy per unit mass. The dose-responseof alanine to ionizing radiation closely f i t s the conditions for the theory of track structure for heavy charged particles, which'makes the RE and thus the dose-response for high-LET radiations predictable. For binding the microcrystalline alanine powder into mechanically stable pellets, a few materials have been investigated in respect to mechanical strength and background ESR signal.
Dose-response
to low- and high-LET radiation is shown, as well as dose rate sensitivity and fading properties. RE measuredwith various high-LET radiations is comparedto theoretical data.
535
0146-5724/86 $3.00 + 0.00
Int. J. Radiat. Appl.lnstrum. Part C Printed in Great Britain.
Copyright(~)1986. PergamonJournals Ltd
All rights reserved
Detection of Low- and High-LET Radiation with Alanine
Johnny W. Hansen and Kjeld J. Olsen Accelerator Department, Ris~ National Laboratory, DK 4000 Roskilde, Denmark Department of Radiophysics, University Hospital of Copenhagen, DK 2730 Herlev, Denmark
SUMMARY Production and accumulation of free radicals in some crystalline biomolecules are relatively stable products of a sequence of events i n i t i a t e d by the absorption of radiation energy. Free radicals can qualitatively and quantitatively be analyzed by means of electron spin resonance, ESR, spectroscopy, and the measure of radical concentration may thus be used for dosimetry purposes. For practical application in radiation dosimetry the crystalline amino acid L-u-alanine is pressed into pellets, 4.5 mm in diameter by 2 mmin thickness, with 5% by weight polyvinylpyrro]idinone (C4HBNO-CH=CH2)n added as a binding material. The dose meter is robust and easy to handle, and the read-out technique is non-destructive with respect to the measuredsignal. The useful dose range is from 0.5 to lO5 Gy with ± 0.4% reproducibility of measurement. Hence, the dose meter can be used in radiation processing of food, for s t e r i l i z a t i o n , as a postal dose meter for intercalibration of radiation f a c i l i t i e s , for control and documentationof radiation therapy doses, and as a personal accident dose meter for radiation workers. Alanine is also suitable for use in high-LET dosimetry as the relative effectiveness, RE, has been found to decrease by only a factor of 4 over a LET-range of four orders of magnitude, and because the dose-responsemaintains linearity also for the very densely ionizing particles.
RE
is the response to high-LET radiation relative to that of low-LET radiation, e.g. 60Co y-rays and fast electrons, for the sameabsorbedenergy per unit mass. The dose-responseof alanine to ionizing radiation closely f i t s the conditions for the theory of track structure for heavy charged particles, which'makes the RE and thus the dose-response for high-LET radiations predictable. For binding the microcrystalline alanine powder into mechanically stable pellets, a few materials have been investigated in respect to mechanical strength and background ESR signal.
Dose-response
to low- and high-LET radiation is shown, as well as dose rate sensitivity and fading properties. RE measuredwith various high-LET radiations is comparedto theoretical data.
535