scholarly journals Development of dose-response calibration curve for dicentric chromosome induced by X-rays

2019 ◽  
Vol 10 (1) ◽  
pp. 2 ◽  
Author(s):  
Yanti Lusiyanti ◽  
Mukh Syaifudin ◽  
Tuti Budiantari ◽  
Sofiati Purnami ◽  
Dwi Ramadhani
Keyword(s):  
Dose Response ◽  
Calibration Curve ◽  
Dicentric Chromosome ◽  
X Rays

scholarly journals Establishing a Reference Dose–Response Calibration Curve for Dicentric Chromosome Aberrations to Assess Accidental Radiation Exposure in Saudi Arabia

2020 ◽  
Vol 8 ◽  
Author(s):  
Ghazi A. Alsbeih ◽  
Khaled S. Al-Hadyan ◽  
Najla M. Al-Harbi ◽  
Sara S. Bin Judia ◽  
Belal A. Moftah
Keyword(s):  
Radiation Exposure ◽  
Dose Response ◽  
Calibration Curve ◽  
Goodness Of Fit ◽  
Dicentric Chromosome ◽  
Homogeneity Test ◽  
X Rays ◽  
Blood Samples ◽  
Reference Dose ◽  
Effect Of Age

In cases of nuclear and radiological accidents, public health and emergency response need to assess the magnitude of radiation exposure regardless of whether they arise from disaster, negligence, or deliberate act. Here we report the establishment of a national reference dose–response calibration curve (DRCC) for dicentric chromosome (DC), prerequisite to assess radiation doses received in accidental exposures. Peripheral blood samples were collected from 10 volunteers (aged 20–40 years, median = 29 years) of both sexes (three females and seven males). Blood samples, cytogenetic preparation, and analysis followed the International Atomic Energy Agency EPR-Biodosimetry 2011 report. Irradiations were performed using 320 kVp X-rays. Metafer system was used for automated and assisted (elimination of false-positives and inclusion of true-positives) metaphases findings and DC scoring. DC yields were fit to a linear–quadratic model. Results of the assisted DRCC showed some variations among individuals that were not statistically significant (homogeneity test, P = 0.66). There was no effect of age or sex (P > 0.05). To obtain representative national DRCC, data of all volunteers were pooled together and analyzed. The fitted parameters of the radiation-induced DC curve were as follows: Y = 0.0020 (±0.0002) + 0.0369 (±0.0019) *D + 0.0689 (±0.0009) *D2. The high significance of the fitted coefficients (z-test, P < 0.0001), along with the close to 1.0 p-value of the Poisson-based goodness of fit (χ2 = 3.51, degrees of freedom = 7, P = 0.83), indicated excellent fitting with no trend toward lack of fit. The curve was in the middle range of DRCCs published in other populations. The automated DRCC over and under estimated DCs at low (<1 Gy) and high (>2 Gy) doses, respectively, with a significant lack of goodness of fit (P < 0.0001). In conclusion, we have established the reference DRCC for DCs induced by 320 kVp X-rays. There was no effect of age or sex in this cohort of 10 young adults. Although the calibration curve obtained by the automated (unsupervised) scoring misrepresented dicentric yields at low and high doses, it can potentially be useful for triage mode to segregate between false-positive and near 2-Gy exposures from seriously irradiated individuals who require hospitalization.

A simulation approach to predict the calibration curve of low LET radiations for biological dosimetry using the Geant4-DNA toolkit

2022 ◽  
Vol 17 (01) ◽  
pp. P01014
Author(s):  
E. Mirrezaei ◽  
S. Setayeshi ◽  
F. Zakeri ◽  
S. Baradaran
Keyword(s):  
Dose Response ◽  
Calibration Curve ◽  
Cellular Response ◽  
Mechanistic Model ◽  
Scaling Factor ◽  
X Rays ◽  
Simulation Approach ◽  
Response Curves ◽  
Biological Dosimetry ◽  
Dicentric Chromosomes

Abstract Ionizing radiation is extensively utilized in various applications; however, it can lead to significant harm to living systems. In this regard, the radiation absorbed dose is usually evaluated by performing biological dosimetry and physical reconstruction of exposure scenarios. But, this is costly, time-consuming, and maybe impractical for a biodosimetry lab to perform biological dosimetry. This study aimed to assess the applicability and reliability of the Geant4-DNA toolkit as a simulation approach to construct a reliable dose-response curve for biodosimetry purposes as an appropriate substitution for experimental measurements. In this matter, the total number of double-strand breaks (DSBs), due to different doses of low LET radiation qualities on DNA molecules, was calculated and converted to the values of dicentric chromosomes using a mechanistic model of cellular response. Then, the number of dicentric chromosomes induced by 200 kVp X-rays were modified by using a semi-empirical scaling factor for compensating the restriction of simulation code to consider what can happen in a real cell. Next, the trend of dicentrics for 137Cs and 60Co were calculated and modified by the above scaling factor. Finally, the dose-response curves for these gamma sources compared to several published experiments. The suggested calibration curves for 137Cs and 60Co followed a linear quadratic equation: Ydic = 0.0054 (± 0.0133) - 0.0089 (± 0.0212) × D + 0.0568 (± 0.0051) × D2 and Ydic = 0.0052 (± 0.0128) - 0.00568 (± 0.0203) × D + 0.0525 (± 0.0049) × D2 respectively. They revealed a satisfactory agreement with the experimental data reported by others. The Geant4 program developed in this work could provide an appropriate tool for predicting the dose-response (calibration) curve for biodosimetry purposes.

CONSTRUCTION AND VALIDATION OF IN VITRO DOSE–RESPONSE CALIBRATION CURVE USING DICENTRIC CHROMOSOME ABERRATION

2020 ◽  
Vol 189 (2) ◽  
pp. 198-204
Author(s):  
Ehsan Mirrezaei ◽  
Saeed Setayeshi ◽  
Farideh Zakeri ◽  
Samaneh Baradaran
Keyword(s):  
Dose Response ◽  
Calibration Curve ◽  
Radiation Effects ◽  
Standard Dose ◽  
Absorbed Dose ◽  
Dicentric Chromosome ◽  
Blood Samples ◽  
Radiation Induced ◽  
Occupational Radiation

Abstract Cytogenetic biodosimetry is a well-known method for quantifying the absorbed dose based on measuring biological radiation effects. To correlate the induced chromosomal abberrations with the absorbed dose of the individuals, a reliable dose–response calibration curve should be established. This study aimed to use frequencies and distributions of radiation-induced dicentric chromosome aberrations to develop a standard dose–response calibration curve. Peripheral blood samples taken from six male donors irradiated by an X-ray generator up to 4 Gy were studied. Three different blood samples were irradiated by known doses, then scored blindly for verification of the proposed calibration curve. Dose estimation was also carried out for three real overexposed cases. The results showed good accordance with the other published curves. The constructed dose–response curve provides a reliable tool for biological dosimetry in accidental or occupational radiation exposures.

scholarly journals Über die Rezeptorsubstanz für den Phagen T5 V. Das rezeptoraktive Areal

1960 ◽  
Vol 15 (1) ◽  
pp. 34-37 ◽  
Author(s):  
Wolfhard Weidel ◽  
Jürgen Homann
Keyword(s):  
Cross Section ◽  
Dose Response ◽  
Active Site ◽  
X Rays ◽  
Binding Reaction ◽  
Phage Tail ◽  
Rapid Inactivation ◽  
The Cross

Highly purified T 5-receptor substance was irradiated with X-rays, and a one-hit dose response was obtained. By comparing quantitatively the results of two independent tests, both of which measure “survival“ of receptor after irradiation, it was possible to conclude that the receptor-active site of one receptor particle must be larger than the cross-section of a T 5-phage tail. However, since receptor particles were never definitely observed to have combined with more than one T 5-particle, secondary processes must be involved in the binding reaction, leading to a rapid inactivation of any surplus receptor-active areas on the receptor particle undergoing the reaction.

scholarly journals X-RAY STAGE SENSITIVITY OF MOUSE OOCYTES AND ITS BEARING ON DOSE-RESPONSE CURVES

Genetics ◽  
1979 ◽  
Vol 91 (1) ◽  
pp. 149-161
Author(s):  
J G Brewen ◽  
H S Payne
Keyword(s):  
Dose Response ◽  
Cytogenetic Study ◽  
Mutation Induction ◽  
Time Interval ◽  
X Rays ◽  
Response Curves ◽  
Time Intervals ◽  
Pooled Data ◽  
Chromatid Aberration ◽  
Dose Response Curves

ABSTRACT A detailed cytogenetic study of maturing mouse oocyte radiosensitivity was performed. Oocytes were collected at various intervals ranging from 1.5 days to 28.5 days after irradiation with 50, 100, 200, and 300R of acute X-rays. The observed sensitivity to chromatid aberration induction varied greatly over this time span. Sensitivity was lowest at the shortest time interval before ovulation and gradually increased up to 9.5 days; it then remained constant until insufficient numbers of oocytes could be collected. The data were analyzed in three ways. First, the data from all time intervals at each dose were pooled; second the data from the least sensitive time intervals, at each dose, were pooled, and third, the data from the period of uniform sensitivity, at each dose, were pooled. Dose-response regression analyses were done on these pooled data and the best fits obtained were to the models Y= a + bD  + cD2 and Y= a + cD2 for both deletions and interchanges. This result is interpreted as indicating that the aberrations result from a predominantly two-track process. The cytogenetic data were compared to specific-locus mutation induction data in comparable oocyte stages, and qualitative similarity in dosei esponse characteristics were observed. This similarity is interpreted to mean that both events result from the same mechanism, and that the large dose-rate effect, observed for both events, is a reflection of the two-track component in the dose-response curves.

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