A new approach to solve the radiative transport equation for time-resolved spectroscopy is presented. A new phase function that shows much better agreement with Mie theory than Henyey-Greenstein's phase function is introduced. Initial laser beams are properly modeled. For every small time increment, precise and analytical solutions are found to satisfy the radiative transport equation for the uniform field, wide beam, and narrow beam. Computer simulations give promising results. Different conditions of initial beams, media, and medium abnormalities are discussed. A strategy for using the semianalytical solutions to reconstruct the regional distribution of the scattering attenuation coefficient and future work are described.