We present the Empirical Formula (EF) to calculate the phantom scatter
factor, Sp, of small
radiation fields under charge particle dis-equilibrium conditions. The Empirical Formula (EF) was verified by
examining the calculated data with
experimentally measured data utilizing the anthropomorphic phantom in
twelve different combinations of beam entry and point location, where the value for Sp per tissue composition was within 3% in 8/12 cases, 5% in 1/12 cases, and 10% in 3/12 cases. Our
results showed a good agreement with experimental data to less than 1% when the
ion chamber was surrounded by the
homogeneous tissue, whether lung, soft tissue, or bone. Indicating that the prediction of the equation is valid, and
it can be reliably used for phantom scatter factor calculation for different homogeneous media under charge particle dis-equilibrium
conditions.
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