In this paper, we present a novel analytical approach to optimize radial synthetic aperture focusing framework for high-definite and high-sensitive volumetric transrectal ultrasound imaging (TRUS-rSAF). A closed-form analytical description of beam profile defines spatial resolution and grating lobe positions in the TRUS-rSAF imaging of radial plane and validated by a heuristic testing of the critical parameters. Given the theoretical foundation, we optimize the TRUS-rSAF system configuration to balance the spatial and temporal resolution, grating lobe artifacts, and signal-to-noise ratio (SNR) in radial plane with a design criterion to outperform a clinical volumetric TRUS (TRUS-REF) imaging. The results showed that the proposed analytical optimization provides significant improvements of imaging quality in radial plane even over an in-plane microconvex TRUS imaging. Therefore, our analytical approach provides a optimal framework for effective TRUS-rSAF imaging in clinics.