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Established calibration curve for unstable Established calibration curve for unstable chromosomal aberrations induced by chromosomal aberrations induced by
therapeutic protons beam for retrospective therapeutic protons beam for retrospective dose estimationdose estimation
2010 Student Practice in JINR Fields of Research
1) Agnieszka Frącka; 2) Ilona Głowacka; 2) Wojciech Wróblewski
1) University of Wrocław; 2) University of Łódź
Supervisors: Marta Deperas- Kaminska and Polina Kutsalo
Laboratory of Radiation Biology, Joint Institute for Nuclear Research
Biological dosimetry – allows to assess an accidental dose of ionising radiation by analysis of changes induced in chromosomes of human
peripheral blood lymphocytes
The yield of chromosome aberrations in peripheral blood lymphocytes is the most sensitive indicator for
past irradiation exposure, therefore it is used in biological dosimetry for retrospective dose estimation.
References:• Biological dosimetry: chromosome aberrations analysis for dose assessment. (1986)
International Atomic Energy Agency Technical Report No 260.Vienna.• Cytogenetic analysis for radiation dose assessment. A manual. (2001) International Atomic
Energy Agency. Vienna.
dicentric
translocation
How are aberrations formed?
ionising radiation
Primary lesions
acentric fragments
Purpose:
The purpose of our investigation were to establish calibration curve for unstable aberrations induced by
proton beam routinely use to cancer therapy at Laboratory of Nuclear Problems at JINR.
What it is calibration curves?Calibration curves are performed for chromosomal aberrations yields scored in lymphocytes of several voluntaries exposed in vitro
to the known radiation doses
SCHEME OF THE EXPERSCHEME OF THE EXPERIIMENTMENT
for the standard metaphase analysis (dicentric assay)
colcemid
46h
Fixation
Staining with Fluorescence
Plus Giemsa (FPG)
48-50h
light microscope
Culture of Irradiated
blood BrdU
0-24 h
PHA
Reference: Cytogenetic analysis for radiation dose assessment. A manual. (2001) International Atomic Energy Agency. Vienna.
An example of metaphase stained with Giemsa. Cell carried unstable An example of metaphase stained with Giemsa. Cell carried unstable aberrations: aberrations: dicentrics, acentric fragments and centric and acentric rings.
Dic
Centric ring
Acentric ring
deletion
ace
Image visible under light microscope
CABAS is intended for fitting dose-response curves. The software is intended for fitting a linear-quadratic dose-response relationship by the
maximum-likelihood method. It was designed for the purpose of biological dosimetry based on the analysis of chromosomal aberrations - dicentrics and rings, scored on Giemsa
stained slides.
Reference: Deperas J. et. al. (2007) CABAS - a freely available PC program for fitting calibration curves in chromosome aberration dosimeter. Radiat Prot Dosimetry 124:115-123, 2007.
Our results:
Dose [Gy}
0.0 0.5 1.0 1.5 2.0 2.5 3.0
Num
ber
of d
ic+
R p
er 1
00 c
ells
0
20
40
60
80
100
120
140
Mean values of aberration frequencies Fitted curves
Y=A+αD+βD^2
Y- aberration yield; A – control frequencyD – dose [Gy]α- linear coefficientβ- dose squared coefficient
Y=0,0030+0.0980*D+0,0798*D^2
Figure 1. Fitted dose response curves for sum of dicentrics and centric rings induced by protons in chromosomes of 4 donors. Error bars represent the 95% confidence intervals calculated for
the mean values.
Conclusion:
We established dose calibration curve for unstable chromosomal aberrations
induced by therapeutic proton beam in the dose range from 0 to 3 Gy.
The calibration curve may be useful to retrospective dose estimation in case of
accidental exposure to protons.
Acknowledgements
Special thanks to:
• Marta Deperas-Kaminska and Polina Kutsalo.
• Ewa and Władysław Chmielowscy
• Roman Zawodny
• Stanislav Zdislavovich Pakuliak
X-ray photo - 1896
Thanks for your attention