OAR 333-106-0305: Additional Requirements for Radiographic Machines: Radiation Exposure Control Devices

(1) Timers. Means shall be provided to terminate the exposure at a preset time interval, preset product of current and time, a preset number of pulses or a preset radiation exposure to the image receptor. In addition: (a) Termination of exposure shall cause automatic resetting of the timer to its initial setting or to zero; (b) It shall not be possible to make an exposure when the timer is set to a zero or "off" position if either position is provided. (2) X-ray Exposure Control: (a) An X-ray exposure control shall be incorporated into each X-ray system such that an exposure can be terminated by the operator at any time except for: (A) Exposure of 0.5 second or less; or (B) During serial radiography when means shall be provided to permit completion of any single exposure of the series in process. (b) Each X-ray exposure control shall be located in such a way as to meet the following requirements: (A) Stationary X-ray systems shall be required to have the X-ray exposure control permanently mounted in a protected area so that the operator is required to remain in that protected area during the entire exposure; and (B) The operator's protected area shall provide visual indication of the patient during the X-ray procedure; and (C) Mobile and portable X-ray systems which are: (i) Used for greater than one week in the same location, i.e., a room or suite, shall meet the requirements of paragraph (2)(b)(A) of this rule; (ii) Used for greater than one hour and less than one week at the same location, i.e., a room or suite, shall meet the requirement of subparagraph (2)(b)(C)(i) of this rule or be provided with a 6.5 feet (1.98 m) high protective barrier which is placed at least 6 feet (1.83 m) from the tube housing assembly and at least 6 feet (1.83 m) from the patient; or (iii) Used to make an exposure(s) of a patient at the use location shall meet the requirement of subparagraph (2)(b)(C)(i) or (ii) of this rule or be provided with a method of X-ray control which permits the operator to be at least 12 feet (3.66 m) from the tube housing assembly during an exposure. (c) The X-ray control shall provide visual indication observable at or from the operator's protected position whenever X-rays are produced. In addition, a signal audible to the operator shall indicate that the exposure has terminated. (3) Automatic Exposure Controls. When an automatic exposure control is provided: (a) Indication shall be made on the control panel when this mode of operation is selected; (b) If the X-ray tube potential is equal to or greater than 50 kVp, the minimum exposure time for field emission equipment rated for pulsed operation shall be equal to or less than a time interval equivalent to two pulses; (c) The minimum exposure time for all equipment other than that specified in subsection (3)(b) of this rule shall be equal to or less than 1/60 second or a time interval required to deliver 5 mAs, whichever is greater; (d) Either the product of peak X-ray tube potential, current, and exposure time shall be limited to not more than 60 kWs per exposure, or the product of X-ray tube current and exposure time shall be limited to not more than 600 mAs per exposure except that, when the X-ray tube potential is less than 50 kVp, the product of X-ray tube current and exposure time shall be limited to not more than 2000 mAs per exposure; and (e) A visible signal shall indicate when an exposure has been terminated at the limits required by subsection (3)(d) of this rule, and manual resetting shall be required before further automatically timed exposures can be made. (4) Reproducibility. With a timer setting of 0.5 seconds or less, the average exposure period (T) shall be greater than or equal to five times the maximum exposure period (Tmax) minus the minimum exposure period (Tmin) when four timer tests are performed: (T)> 5 (Tmax - Tmin).