An X-ray imaging system is provided. The X-ray imaging system includes an X-ray radiation source. The X-ray imaging system also includes a source controller coupled to the source and configured to command emission of X-rays for image exposures. The X-ray imaging system further includes a digital X-ray detector configured to acquire X-ray image data without communication from the source controller, wherein the digital X-ray detector includes a photovoltaic device, and the digital X-ray detector is configured to determine one or more of a beginning, end, or duration of an image exposure via the photovoltaic device.