1. (a) General requirements.

   1. (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, 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. (2) Reproducibility. With a timer setting of 0.3 second or less, the average exposure period (T) shall be greater than or equal to 5 times the maximum exposure period (T_max) minus the minimum exposure period (T_min) when 4 timer tests are performed: T> 5(T_max - T_min )

   3. (3) X-Ray control.

      1. (A) An x-ray control shall be incorporated into each dental x-ray system such that an exposure can be terminated by the operator at any time, except for exposures of 0.5 second or less.
      2. (B) The exposure switch shall be of the dead-man type.
      3. (C) Each x-ray control shall be located in such a way as to permit the operator to remain in an area of less than 2 millirems in any 1 hour during the entire exposure.
   4. (4) Exposure reproducibility. The coefficient of variation shall not exceed 0.10 when all technique factors are held constant. This requirement is met when 4 exposures are made at identical technique factors, the value of the average exposure (E) is greater than or equal to 5 times the maximum exposure (E_max) minus the minimum exposure (E_min): E > 5(E_max - E_min )

2. (b) Additional requirements for dental intraoral systems.

   1. (1) Source-to-Skin distance (SSD). Dental x-ray systems designed for use with an intraoral image receptor shall be provided with means to limit SSD to not less than:

      1. (A) 18 centimeters if operable above 50 kVp; or
      2. (B) 10 centimeters if not operable above 50 kVp.

   2. (2) Field limitation.

      1. (A) Dental x-ray systems designed for use with an intraoral image receptor shall be provided with means to limit the x-ray beam such that the x-ray field, at the minimum SSD, is containable in a circle having a diameter of no more than 7 centimeters or a rectangle with a longer side of no more than 5cm.
      2. (B) An open-ended, shielded, beam-indicating device shall be used.

3. (c) Additional requirements for dental extraoral system field limitation.

   1. (1) Dental rotational panoramic systems shall be provided with means to limit the x-ray beam to the imaging slit in the transverse axis and shall not exceed a total of 0.5 inch larger than the imaging slit in the vertical axis.
   2. (2) All other dental extraoral x-ray systems (e.g., cephalometric) shall be provided with means to both size and align the x-ray field so that it does not extend beyond any edge of the image receptor by more than 2 percent of the SID.

Added at 8 Ok Reg 3503, eff 8-15-91 (emergency)

Added at 9 Ok Reg 1643, eff 5-29-92

Amended at 21 Ok Reg 1037, eff 5-13-04

Amended at 38 Ok Reg 1954, eff 9-11-21