Section 120.312 - Locking of Sources of Radiation, Storage Containers and Source Changers(A) The control panel of each radiation machine shall be equipped with a locking device which will prevent the unauthorized use of an x-ray system or the accidental production of radiation. The radiation machine shall be kept locked and the key removed at all times except when under the direct visual surveillance of a radiographer or radiographer trainee, or an individual specifically authorized by the Agency.(B) Each radiographic exposure device must have a lock or outer lockable container designed to prevent unauthorized or accidental removal of the sealed source from its shielded position. The exposure device and/or its container must be kept locked and, if a keyed lock, the key removed at all times when not under the direct surveillance of a radiographer or radiographer trainee, or an individual specifically authorized by the Agency except at permanent radiograhic installations as stated in 105 CMR 120.319. In addition, during radiographic operations the sealed source assembly must be secured in the shielded position each time the source is returned to that position.(C) Each sealed storage container and source changer must have a lock or outer lockable container designed to prevent unauthorized or accidental removal of the sealed source from its shielded position. Storage containers and source changers must be kept locked, and if a keyed lock the key removed when containing sealed sources except when under the direct surveillance of a radiographer or a radiographer trainee.(D) The sealed source shall be secured in its shielded position by locking the exposure device or securing the remote control each time the sealed source is returned to its shielded position. Then a survey shall be performed to determine that the sealed source is in the shielded position pursuant to 105 CMR 120.333(B).Amended by Mass Register Issue 1307, eff. 2/26/2016.