10-144-220 Me. Code R. § F-8

Current through 2024-51, December 18, 2024

Section 144-220-F-8 - Intraoral dental radiographic systems and podiatric systems

In addition to the provisions of F.3, F.4, and F.5, the requirements of F.8 apply to x-ray equipment and associated facilities used for dental radiography. Requirements for extraoral dental radiographic systems are covered in F.7.

A. Source-to-skin distance. X-ray systems designed for use with an intraoral image receptor shall be provided with means to limit source-to-skin distance, i.e., SSD, to not less than:

(1) 18 centimeters if operable above 50 kVp, or

(2) 10 centimeters if operable at 50 kVp.

B. Field Limitation. Radiographic systems designed for use with an intraoral image receptor shall be provided with means to limit the x-ray beam such that:

(1) If the minimum SSD is 18 centimeters or more, the x-ray field at the minimum SSD shall be containable in a circle having a diameter of no more than 7 centimeters; and

(2) If the minimum SSD is less than 18 centimeters, the x-ray field at the minimum SSD shall be containable in a circle having a diameter of no more than 6 centimeters.

C. Radiation exposure control for certified and non-certified systems.

(1) Exposure Initiation

(a) Means shall be provided to initiate the radiation exposure by a deliberate action on the part of the operator, such as the depression of a switch. Radiation exposure shall not be initiated without such an action; and

(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) Exposure termination

(a) 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.

(b) 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 exposures of one-half second or less.

(c) Termination of an exposure shall cause automatic resetting of the timer to its initial setting or to zero

(3) Exposure indication. Means shall be provided for 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.

(4) Exposure duration (timer) reproducibility. With a timer setting of 0.5 seconds or less, the difference between the maximum exposure time (Tmax) and the minimum exposure time (Tmin) shall be less than or equal to 10 percent of the average exposure time (T), when four timing tests are performed:

(Tmax - Tmin) < 0.10T

D. X-Ray control.

(1) Each x-ray 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 control permanently mounted in a protected area, and the operator is required to remain in that protected area, or six feet away and out of the useful beam during the entire exposure; and

(b) 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 F.8.D(1)(a);

(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 requirements of F.8.D(1)(b)(i) or be provided with a 6.5 (1.98m) foot high protective barrier which is placed at least 6 feet (1.98m) from the tube housing assembly and at least 6 feet (1.98m) from the patient; or

(iii) Used to make an exposure(s) of a patient at the use location shall meet the requirement of F.8.D(2)(b)(i) or (ii) or be provided with a method of x-ray control which will permit the operator to be at least 6 feet (3.66m) from the tube housing assembly and out of the useful beam during an exposure.

(2) 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, if available to the unit, shall indicate that the exposure has terminated.

E. Exposure reproducibility. The coefficient of variation shall not exceed 0.10 when all technique factors are held constant. This requirement shall be deemed to have been met if, when 4 exposures are made at identical technique factors, that the value of the average exposure (E) is greater than or equal to 5 times the maximum exposure (Emax), minus the minimum exposure (Emin): i.e., E > 5(Emax- Emin).

F. Administrative controls.

(1) Patient and film holding devices shall be used when the techniques permit.

(2) The tube housing and the PID shall not be hand-held during an exposure.

(3) The x-ray system shall be operated in such a manner that the useful beam at the patient's skin does not exceed the requirements of F.8.B.(1).

(4) Dental fluoroscopy without image intensification shall not be used.

G. Additional requirements Applicable to certified systems only. Only diagnostic x-ray systems incorporating one or more certified component(s) shall be required to comply with the following additional requirements(s) which relate to that certified component(s).

(1) Reproducibility. When the equipment is operated on an adequate power supply as specified by the manufacturer, the estimated coefficient of variation of radiation exposures shall be no greater than 0.05, for any specific combination of selected technique factors.

(2) Linearity. When the equipment allows a choice of x-ray tube current settings and is operated on a power supply as specified by the manufacturer in accordance with the requirements of applicable Federal standards, for any fixed x-ray tube potential within the range of 40 percent to 100 percent of the maximum rating, the average ratios of exposure to the indicated milliampere-seconds product, obtained at any two consecutive tube current settings shall not differ by more than 0.10 times their sum,

i.e., X1-X2 < 0.10 (X1 + X2),

where X1 and X2 are the average mR/mAs values obtained at each of two consecutive tube current settings.

(3) Accuracy. Deviation of technique factors from indicated values shall not exceed the limits specified for that system by its manufacturer. In the absence of the manufacturer's specifications the deviation shall not exceed 10 percent of the indicated value.

(4) Timers. Termination of exposure shall cause automatic resetting of the timer to its initial setting or to zero.

(5) Beam quality. All certified dental x-ray systems manufactured on or after December 1, 1980, shall have a minimum half-value layer not less than 1.5 millimeters aluminum equivalent. Systems operating above 70 kVp are subject to the filtration requirements of F.5.E.(1).

10-144 C.M.R. ch. 220, § F-8