Each Dose Point in the Fitted “Dose–Effect Curve by DIC Analysis. (See table 1)
Abbreviation: DIC, dicentric chromosome.
In the following dose ranges, the obtained data were fitted by the method of minimum sum of squares according to the four mathematical models provided by WHO, the significance test of the regression coefficient was carried out, and the correlation index (R2) test of the fitting degree of the equation was carried out. According to the regression coefficient significance test (P), the degree of fit (R2), the difference between a value and the spontaneous aberration rate, the optimal regression equation was selected for each dose range.：0-0.5Gy(Dic+r)，Y=3.99D1.1033;0-0.5Gy(The total distortion),Y=6.5328D1.0196；0.5-5.0Gy(Dic+ r),Y=7.1466D1.8933;0-5.0Gy(Dic+r),Y=8.9846D1.632. 0-6.0Gy (Dic+r),Y=9.23D1.6606.
Biological dose estimation and error analysis were performed on the national assessment samples in 2015 and 2016 by using the dose curves established by different dose rates in different laboratories.
The dose curves with different exposure dose rates established by different laboratories were used to estimate the biological dose of the national assessment samples in 2015 and 2016. The error analysis is shown in table 2，3.
Table 3 shows that the absolute value of the error increases with the increase of the radiation dose rate, which is significant with the increase of the radiation dose. It indicates that the irradiation dose is dominant and the irradiation dose rate is secondary.
Analysis of double + ring (%) and irradiation dose results of chromosome aberrations in peripheral blood irradiated by different dose rates in different laboratories (see table 4)
Table4 shows that the original data of the biological dose estimation curve of chromosome aberration established by different laboratories have certain differences when comparing the dose-effect curve of each laboratory. Although there was an increasing trend of different dose rates at the same dose, there were also cases in which the high dose rate irradiation of “dicentric+ring” (%) of chromosome aberration was lower than that of low dose rate irradiation.
1Gy: Y=5.936+5.074x, p=0.018
2Gy: Y=19.666+15.354x, p=0.024
3Gy: Y=40.604+29.299x, p=0.010
4Gy: Y=74.908+42.752x, p=0.012
5Gy: Y=122.004+62.054x, p=0.019
Y is the increasing of “dicentric+ring” (%) cause by the dose rate;
The unit of x is Gy·min-1
At each dose point, "Dic + r/Cell" is proportional to "dose rate", that is, Y=k X +b, It shown table 5, figure1, 2.
According to the values of k：
Dose rate :Y Dose rate =1.2534×10-2 x 2+6.6164×10-2 x -2.732×10-3（1Gy·min-1；R2=0.999）(1).
According to the values of b，Remove "Dic + r/Cell" due to dose rate increase：
Y Dose1 =5.7213×10-2 x 2+5.5899×10-2 x -6.4592×10-3（0.01Gy·min-1；R2=0.999 (2).
The dose rate caused by the “dicentric+ring” increase in the share of the analysis, it shown table 6, 7 and Figure 3
The fraction of “dicentric+ring” caused by dose rate was calculated, if “Dose rate” is Z Gy·min-1, it corresponds to an increase in linear relationships.
Biological dose estimation curve :Y=3.318×10-3+2.0541×10-2 x +7.1721×10-2x2（1.16Gy·min-1；R2=0.9997）(3).
Dose rate :Y Dose rate =1.2534×10-2 x 2+6.6164×10-2 x -2.732×10-3（0.01Gy·min-1；R2=0.999）(1).
The estimated dose is formula (3) – (1.16-Z)×formula (1).