An imaging detector includes a scintillator array (202), a photosensor array (204) optically coupled to the scintillator array (202), a current-to-frequency (I/F) converter (314), and logic (312). The I/F converter (314) includes an integrator (302) and a comparator (310), and converts, during a current integration period, charge output by the photosensor array (204) into a digital signal having a frequency indicative of the charge. The logic (312) sets a gain of the integrator (302) for a next integration period based on the digital signal for the current integration period. In one instance, the gain is increased for the next integration period, relative to the gain for the current integration period, which allows for reducing an amount of bias current injected at an input of the I/F converter (314) to generate a measurable signal in the absence of radiation, which may reduce noise such as shot noise, flicker noise, and/or other noise.