In this paper, we have explored the electrical and material properties of TIPS-Pentacene for low doses of gamma irradiation. Interface trap/defect generation was studied post gamma irradiation of TIPS-Pentacene transistors. This paper demonstrates that the traps/defects at the bulk/surface of TIPS-Pentacene and SiO2/Si interface states significantly influence the sensing behavior. It is demonstrated that the interface trap charges introduced by the gamma radiation are significant in the TIPS-Pentacene thin-film instead of the SiO2/Si. The detector exhibits a record high sensitivity of ~3 V/Gy at 1 Gy in ambient air. A theoretical model was developed to understand the change in ON-current and channel doping. The change in surface potential of film was studied by Kelvin probe force microscopy (KPFM). Developed model was in good agreement with the KPFM results. These promising results indicate that our device can be used as a dosimeter for medical applications with high sensitivity.