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Teaching Documents by Rajesh Chaurasia

HELIYON , 2023

In the modern developing society, application of radiation has increased extensively. With signif... more In the modern developing society, application of radiation has increased extensively. With significant improvement in the radiation protection practices, exposure to human could be minimized substantially, but cannot be avoided completely. Assessment of exposure is essential for
regulatory decision and medical management as applicable. Until now, cytogenetic changes have
served as surrogate marker of radiation exposure and have been extensively employed for biological dose estimation of various planned and unplanned exposures. Dicentric Chromosomal
Aberration (DCA) is radiation specific and is considered as gold standard, micronucleus is not
very specific to radiation and is considered as an alternative method for biodosimetry. In this
study dose response curves were generated for X-ray induced “dicentric + ring” and micronuclei,
in lymphocytes of three healthy volunteers [2 females (age 22, 23 years) and 1 male (24 year)].
The blood samples were irradiated with X-ray using LINAC (energy 6 MV, dose rate 6 Gy/min), in
the dose range of 0–5Gy. Irradiated blood samples were cultured and processed to harvest
metaphases, as per standard procedures recommended by International Atomic Energy Agency.
Pooled data obtained from all the three volunteers, were in agreement with Poisson distribution
for “dicentric + ring”, however over dispersion was observed for micronuclei. Data (“dicentric +
ring” and micronuclei) were fitted by linear quadratic model of the expression Y– –C + αD + βD2
using Dose Estimate software, version 5.2. The data fit has resulted in linear coefficient α =
0.0006 (±0.0068) “dicentric + ring” cell− 1 Gy− 1 and quadratic coefficient β = 0.0619 (±0.0043)
“dicentric + ring” cell− 1 Gy− 2 for “dicentric + ring” and linear coefficient α = 0.0459 ± (0.0038)
micronuclei cell− 1 Gy− 1 and quadratic coefficient β = 0.0185 ± (0.0010) micronuclei cell− 1 Gy− 2
for micronuclei, respectively. Background frequencies for “dicentric + ring” and micronuclei were
0.0006 ± 0.0004 and 0.0077 ± 0.0012 cell− 1, respectively. Established curves were validated, by
reconstructing the doses of 8 dose blinded samples (4 by DCA and 4 by CBMN) using coefficients generated here. Estimated doses were within the variation of 0.9–16% for “dicentric + ring” and
21.7–31.2% for micronuclei respectively. These established curves have potential to be employed
for biodosimetry of occupational, clinical and accidental exposures, for initial triage and medical
management.

HELIYON , 2023

In the modern developing society, application of radiation has increased extensively. With signif... more In the modern developing society, application of radiation has increased extensively. With significant improvement in the radiation protection practices, exposure to human could be minimized substantially, but cannot be avoided completely. Assessment of exposure is essential for
regulatory decision and medical management as applicable. Until now, cytogenetic changes have
served as surrogate marker of radiation exposure and have been extensively employed for biological dose estimation of various planned and unplanned exposures. Dicentric Chromosomal
Aberration (DCA) is radiation specific and is considered as gold standard, micronucleus is not
very specific to radiation and is considered as an alternative method for biodosimetry. In this
study dose response curves were generated for X-ray induced “dicentric + ring” and micronuclei,
in lymphocytes of three healthy volunteers [2 females (age 22, 23 years) and 1 male (24 year)].
The blood samples were irradiated with X-ray using LINAC (energy 6 MV, dose rate 6 Gy/min), in
the dose range of 0–5Gy. Irradiated blood samples were cultured and processed to harvest
metaphases, as per standard procedures recommended by International Atomic Energy Agency.
Pooled data obtained from all the three volunteers, were in agreement with Poisson distribution
for “dicentric + ring”, however over dispersion was observed for micronuclei. Data (“dicentric +
ring” and micronuclei) were fitted by linear quadratic model of the expression Y– –C + αD + βD2
using Dose Estimate software, version 5.2. The data fit has resulted in linear coefficient α =
0.0006 (±0.0068) “dicentric + ring” cell− 1 Gy− 1 and quadratic coefficient β = 0.0619 (±0.0043)
“dicentric + ring” cell− 1 Gy− 2 for “dicentric + ring” and linear coefficient α = 0.0459 ± (0.0038)
micronuclei cell− 1 Gy− 1 and quadratic coefficient β = 0.0185 ± (0.0010) micronuclei cell− 1 Gy− 2
for micronuclei, respectively. Background frequencies for “dicentric + ring” and micronuclei were
0.0006 ± 0.0004 and 0.0077 ± 0.0012 cell− 1, respectively. Established curves were validated, by
reconstructing the doses of 8 dose blinded samples (4 by DCA and 4 by CBMN) using coefficients generated here. Estimated doses were within the variation of 0.9–16% for “dicentric + ring” and
21.7–31.2% for micronuclei respectively. These established curves have potential to be employed
for biodosimetry of occupational, clinical and accidental exposures, for initial triage and medical
management.