Abstract: An X-ray source interlock kit includes a probe-based portion integral with an X-ray source in communication with a peripheral-based portion, the interlock kit serving as an interface between an X-ray treatment system and a given class of peripheral devices. Peripheral devices are classified based on their shielding characteristics and whether or not radiation is permitted with the device, and include, for example, a stereotactic frame, a probe adjuster, and a photodiode array. The probe-based portion includes a probe side bushing having two optical source-detector pairs housed therein and interlock electronics, which accomplish signal processing as required. The peripheral-based portion is the form of a peripheral side bushing which is coded with the shielding and radiation information for a given class of peripheral devices.