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