IGCAR : Annual Report - Indira Gandhi Centre for Atomic Research

IGC
Annual Report 2007
hemisphere of radius 13 cm in
100 time slices. 10% Gaussian
noise with mean zero is added
to the computed data to obtain
the b rn matrix. By using the
MUSIC approach described
above locations of all the
dipoles are identified as shown
in Fig.2. with characteristic
rotating dipoles being identified
after plotting the inverse of
trace of the cost function matrix
J as shown in Fig.3. It is seen
from the results presented in
Table -1that the locations of the
dipoles identified by this
inversion algorithm are
accurate to within 2 mm within
the cortex even in the presence
of 10% noise.
VI.14. A Novel Technique to Irradiate Blood Cells
in vitro with Alpha Radiation for Cytogenetic Aanalysis
The need for determining a required for purposes of
reliable Radiobiological radiation protection, human
Effectiveness (RBE) value for blood cells need to be
alpha exposures has become
important as reported literature
values vary widely. Moreover,
increasing nuclear reprocessing
irradiated in vitro. However,
unlike gamma radiation, due to
the low penetrating power of
alpha rays, it has always been a
facilities the world-over calls for challenge for radiation
measures to estimate alpha biologists to handle alpha
radiation doses during a sources. A simple technique to
criticality accident such as the irradiate human blood
one that occurred at lymphocytes in vitro using
Tokaimura, Japan, in 1999. In radon gas emanating from a
order to construct doseresponse
solid radium source has been
curves and calculate
RBE factors for risk estimation
designed and developed. The
difficulties in delivering and
Fig.1 Blood irradiation using the radon source
estimating exact activity
concentrations have been
handled in a unique and safe
way. Such a method was used
to score chromosome
aberrations induced by radon
and progeny.
Radon exposure
The radon source used in the
present study was procured
from Pylon (Canada). The
assembly used for irradiation is
shown in Fig 1. Activity was
determined using a custom
designed Lucas cell (Fig.2).
The radon concentration and
doses were calculated using the
equations:
Activity (Bq/m 3 )= 0.06967 x
(-0.00012584 x DT)
NC/ Eff x 0.14 e x 1
- e (-0.00012584 x CT) Metaphases
prepared by standard culturing
methods were captured using a
Metaphase finder
(Metasystems, Zeiss) available
at RSD. (Fig.3).
170 BASIC RESEARCH