The primary objective of this study is to create a novel mathematical model that accounts for the combined effects of heat radiation and the Sutterby nanofluid convection flow caused by a stretched Riga cylindrical tube that contains planktonic microorganisms utilizing the non-Darcy flow (Forchheimer model). Mathematically, the issue is modulated by a nonlinear partial differential equations system (PDEs), which are then converted into an ordinary differential equations system (ODEs) with the use of appropriate similarity transformations. Using MATHEMATICA software’s built-in command (Parametric ND Solve), the generated ODEs system is resolved numerically. A series of figures are used to demonstrate numerically and graphically the influence of the physical parameters on the fluid behaviour. The performed numerical simulation indicated that thermal radiation is a property of temperature that decreases with the increase of thermal radiation parameter. Furthermore, as the temperature decreases, the diameter of the nanoparticles grows, resulting in an increase in the volume and concentration of the nanoparticle and making it more effective near to tumor tissues. Since it specifically targets tumour cells for localized destruction, it can be employed as a radiotherapy agent to cause localized increases in doses of radiation (Radiotherapy of oncology).