Calculation of generalized Hubbell rectangular source integral

A simple formula for computing the generalized Hubbell radiation rectangular source integral $$H[{a,b,p,\lambda \atop \alpha,\beta,\gamma}]=\frac{\sigma a}{4\pi}\int_0^b x^\lambda(x^2+p)^{-\alpha}{}_2F_1(\alpha,\beta;\gamma;-{a^2\over x^2+p})dx,$$ is introduced. Tables are given to compare the numerical values derived from our approximation formula with those given earlier in the literature.