Stereotactic body radiotherapy (SBRT) with simultaneous integrated boost (SIB) delivers high doses in few fractions to subvolumes within a target, aiming to improve tumor control without increasing toxicity to organs at risk (OARs). This study evaluated the anatomical, functional, and molecular information from PET/MR with F18-PSMA to identify intraprostatic lesions suitable for boost delineation in SBRT treatments, following the hypo-FLAME protocol. Twelve patients with suspected prostate cancer were studied, incorporating an experimental pseudo-diffusion MR sequence with 16 b-values to extract IVIM and DKI biomarkers, providing perfusion-like information without contrast. Acquisition protocols were optimized for mpMRI and PET/MR, and a Python program was developed to process the pseudo-diffusion images. Quantitative DCE biomarkers (Ktrans, kep, ve) were semi-automatically generated using the manufacturer’s workstation. Functional and molecular data from F18-PSMA were registered with tomographic images to simulate SBRT plans with and without SIB using the Halcyon v2.0 system. The pseudo-diffusion sequence enabled extraction of perfusion biomarkers, offering an alternative for patients with renal impairment. PET/MR showed greater sensitivity and specificity than MRI alone, identifying lesions through PSMA overexpression. In SBRT-SIB simulations, high doses were delivered to the tumor with optimal prostate coverage, without exceeding dose constraints for most OARs. However, low-dose exposure increased in the GTV’s anterior/posterior regions, with larger irradiated volumes of bladder, rectum, and urethra due to its proximity to the GTV. Additionally, SIB plans also required more monitor units. This study showed the feasibility of PET/MR combined with pseudo-diffusion biomarkers in SBRT-SIB, highlighting its potential for new treatment standards.