Empirical formula for 30Co axial depth doses

An empirical formula has been developed to approximate the published axial depth doses of 60Co radiation with greater accuracy than available hitherto. With sets of nine constants, varying slightly with SSD, a total of 2100 percentage depth doses are reproduced with root-mean-square deviations ranging from 0.13 to 0.16 for four values of SSD from 50 to 100 cm.