CABAS is a freeware program devoted to fitting of linear-quadratic dose-response curves for dicentric and ring-type chromosomal aberrations as used in biological dosimetry. The procedure of fitting chromosomal data to a linear-quadratic equation should be performed by the method of maximum likelihood. This method is difficult to apply because it is not implemented in the widely used, low cost statistical software packages.  A further difficulty is the correct calculation of the 95% confidence interval of dose on the calibration curve. Although a number of papers have been published were the problem of proper curve-fitting is discussed and different solutions are proposed, these are difficult to implement for people who have no support of a statistician. Therefore, we decided to develop a freely available tool with the help of which the user can:

• fit chromosomal aberration data to a linear-quadratic equation by maximum likelihood and test the goodness of fit

• calculate the dose and the uncertainty based on the scored frequency of aberrations

• check if the aberration distribution is Poissonian and, in case it is not, calculate the dose received by the exposed part of the body

• estimate the number of cells necessary to detect a given dose of radiation

• calculate the dose in the case of fractionated or protracted exposure to radiation

• calculate the odds ratio of zero dose versus a suspected dose

A full description of CABAs can be found in: Deperas, J., M. Szłuińska, M. Deperas-Kaminska, A. Edwards, D. Lloyd, C. Lindholm, H. Romm, L. Roy, R. Moss, J. Morand, A Wojcik. CABAS - a freely available PC program for fitting calibration curves in chromosome aberration dosimetry. Radiation Protection Dosimetry 124:115-123, 2007.

Description of CABAS

Application of CABAS

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last updated: 14.12.2007 by Andrzej Wojcik

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Download HPA paper on statistical methods in biological dosimetry