1. 2010 Student Practice in JINR Fields of Research
Established calibration curve for unstable chromosomal aberrations induced by therapeutic protons beam for retrospective dose estimation
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

2. The yield of chromosome aberrations
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.

3. How are aberrations formed?
ionising radiation
Primary lesions
acentric
fragments
translocation
dicentric

4. What it is calibration curves?
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

5. SCHEME OF THE EXPERIMENT
for the standard metaphase analysis (dicentric assay)
PHA
Culture of Irradiated blood
BrdU
colcemid
46h
Fixation
0-24 h
48-50h
Staining with Fluorescence Plus Giemsa (FPG)
Reference: Cytogenetic analysis for radiation dose assessment.
A manual. (2001) International Atomic Energy Agency. Vienna.
light microscope

6. Image visible under light microscope
An example of metaphase stained with Giemsa. Cell carried unstable aberrations: dicentrics, acentric fragments and centric and acentric rings.
Dic
Centric ring
Acentric ring
deletion
ace
Image visible under light microscope

7. 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: , 2007.

8. Our results: Y=A+αD+βD^2 Y- aberration yield; A – control frequency
D – dose [Gy]
α- linear coefficient
β- dose squared coefficient
Y=0, *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.

9. 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.

10. Acknowledgements Special thanks to:
Marta Deperas-Kaminska and Polina Kutsalo.
Ewa and Władysław Chmielowscy
Roman Zawodny
Stanislav Zdislavovich Pakuliak

11. X-ray photo
Thanks for your attention