Abstract: An X-ray tube exposure monitor for recording the emissions from a diagnostic X-ray tube. A photo diode is mounted inside the X-ray tube bulkhead and detects radiation from the X-ray tube. The photo diode is connected to a high gain amplifier and, in response to radiation being detected, the output of the amplifier sends an electronic signal to a microprocessor. The microprocessor records the emission duration and the temperature of oil around the X-ray tube and increments an exposure count. The recording and exposure count is stored in non-volatile memory which is read later by a service technician.