In one embodiment, a quantum dot based radiation source includes a housing having a wall defining a cavity therein, a plurality of quantum dots disposed on an inner surface of the wall of the housing, and a radiation excitation source in optical communication with the housing and configured to output radiation to excite the plurality of quantum dots to emit radiation in a desired wavelength range. The quantum dot based radiation source can be used in a calibration system or calibrator, for example to calibrate a detector.