Ionizing radiation effects are investigated in N-channel metal-oxide-semiconductor triple-gate field-effect transistors with Ω-shaped gate fin field-effect transistor (FinFET) architecture. The total dose response is shown to be dependent on device geometry. A wide FinFET structure behaves like a single-gate fully depleted silicon-on-insulator transistor, showing a noticeable degradation induced by ionizing radiation. By contrast, an optimized narrow FinFET shows a drastically reduced influence of ionizing radiation thanks to the efficient electrostatic control of the potential in the device provided by the Ω gate. A narrow FinFET is shown to be naturally tolerant to a significant total dose exposure.