Table 2 shows the number of cells scored, the frequency of dicentrics, their distribution, the dispersion index ([[sigma].sup.2]/y), and the u index.
As expected, the yield of dicentrics increased with radiation dose, showing increments that were clearly dose-dependent (r = 0.9680).
The yield of dicentrics for gamma and X-rays, which are both low with LET radiation, and where the ionizing events are sparsely distributed among cells, followed a Poisson distribution.
Establishment of in-vitro [sup.60]Co dose calibration curve for dicentrics in National biodosimetry laboratory of Malaysia.
Dose (Gy) Cells scored Dicentrics Centric rings Acentric rings 0.0 3000 3 0 0 0.25 1504 9 1 0 0.5 1039 27 2 2 1.0 768 51 2 0 1.5 500 64 5 1 2.0 560 163 7 5 3.0 500 258 14 1 Dose (Gy) Minutes Excess acentrics 0.0 0 9 0.25 0 20 0.5 6 29 1.0 2 47 1.5 5 40 2.0 3 93 3.0 7 173 Table 2.
Among several proposed biological endpoints and cellular biomarkers, the assay of dicentric chromosomes in peripheral blood lymphocytes is the most frequently used and is considered as the gold standard (1).
A dicentric chromosome is a radiation-induced aberrant chromosome formed as a result of misrepair by nonhomologous end joining whereby two damaged chromosomes undergo an exchange of material.
The purpose of this paper was to construct an in vitro dose calibration curve for a 6 MV electron linear accelerator using the dicentric assay and to fit the data to both the CABAS and the Dose Estimate programs in order to compare the output of each method.
In order to correlate the dose delivered and dicentric frequency, Pearson's correlation was determined at the 5% or P [less than or equal to] 0.05 level of significance.
Figure 1 shows the dose-response calibration curves generated by the CABAS (A) and Dose Estimate (B) programs and calculated using the dicentric yields induced by incremental doses of X-irradiation generated by the linear accelerator.
In the present study, the goodness-of-fit test for the dicentric calibration curves indicated that the data were well represented by the linear-quadratic model ([chi square] = 7.19, degrees of freedom = 4, P = 9.487).
As previously emphasized, the radiation-induced dicentric yield is also determined by the energy, so that it is interesting to compare the curves obtained for different types of radiation (4,5).