New Mexico Administrative Code
Title 20 - ENVIRONMENTAL PROTECTION
Chapter 3 - RADIATION PROTECTION
Part 6 - X-RAYS IN HEALING ARTS
Section 20.3.6.605 - RADIOGRAPHIC SYSTEMS OTHER THAN FLUOROSCOPIC, DENTAL, INTRAORAL, OR VETERINARIAN OR COMPUTED TOMOGRAPHY X-RAY SYSTEMS

Universal Citation: 20 NM Admin Code 20.3.6.605

Current through Register Vol. 35, No. 18, September 24, 2024

A. Beam Limitation: The useful beam shall be limited to the area of clinical interest.

(1) General purpose stationary and mobile x-ray systems:
(a) Variable held limitation: There shall be provided a means for stepless adjustment of the size of the x-ray field. The minimum field size at a SID of 100 cm shall be equal to or less than 5 cm (1.96 inches) by 5 cm (1.96 inches).

(b) Visual Definition: Means shall be provided for visually defining the perimeter of the x-ray field. The total misalignment of the edges of the x-ray field along either the length or width of the visually defined field shall not exceed 2 percent of the distance from the source to the center of the visually defined field when the surface upon which it appears is perpendicular to the axis of the x-ray beam.

(2) Additional Requirements for Stationary General Purpose X-ray Systems: In addition to the requirements in 605.A.1 [Paragraph (1), Subsection A., Section 605 of 20.3.6.605 NMAC] above, all stationary x-ray systems shall:
(a) provide means to indicate when the axis of the x-ray beam is perpendicular to the plane of the image receptor, to align the center of the x-ray field with respect to the center of the image receptor to within 2 percent of the SID, and to indicate the SID to within 2 percent;

(b) be equipped with a beam-limiting device that numerically indicates the field size in the plane of the image receptor to which it is adjusted; and

(c) indicate field size dimensions and SID's in inches or cm, and shall be such that aperture adjustments result in x-ray field dimensions in the plane of the image receptor which correspond to those of the image receptor to within 2 percent of the SID when the beam axis is perpendicular to the plane of the image receptor.

(3) X-ray Systems Designed for One Image Receptor Size: Radiographic equipment designed for only one image receptor size at a fixed SID shall be provided with means to limit the field at the plane of the image receptor to dimensions no greater than those of the image receptor, and to align the center of the x-ray field with the center of the image receptor to within 2 percent of the SID.

(4) Special purpose x-ray systems:
(a) Shall be provided with means to limit the x-ray field in the plane of the image receptor so that such field does not exceed each dimension of the image receptor by more than 2 percent of the SID when the axis of the x-ray beam is perpendicular to the plane of the image receptor.

(b) Shall be provided with means to align the center of the x-ray field with the center of the image receptor to within 2 percent of the SID.

(c) The above, 605.A.4.a and 605.A.4.b [Subparagraphs (a) and (b), Paragraph (4), Subsection A., Section 605 of 20.3.6.605 NMAC], may be met with a system that meets the requirements for a general purpose x-ray system as specified in 605.A.1 [Paragraph (1), Subsection A., Section 605 of 20.3.6.605 NMAC] above or, when alignment means are also provided, may be met with either:
(i) an assortment of removable, fixed-aperture, beam-limiting devices sufficient to meet the requirements for each combination of image receptor size and SID for which the unit is designed (each such device shall have clear and permanent markings to indicate the image receptor size and SID for which it is designed); or

(ii) a beam-limiting device having multiple fixed apertures sufficient to meet the requirements for each combination of image receptor size and SID for which the unit is designed. Permanent, clearly legible markings shall indicate the image receptor size and SID for which each aperture is designed and shall indicate which aperture is in position for use.

B. 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; 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) X-ray control (exposure switch):
(a) A control shall be incorporated into each x-ray system such that an exposure can be terminated at any time except for:
(i) exposure of one-half second or less; or

(ii) during serial radiography when means shall be provided to permit completion of any single exposure of the series in process.

(b) Each x-ray control shall:
(i) for stationary x-ray systems be permanently mounted in a protected area so that the operator is required to remain in that protected area during the entire exposure; or

(ii) mobile and portable x-ray systems which are:
1) used for greater than one week in one location (one room or suite) shall meet the requirements of 605.B.2.b.(1) [Item (i), Subparagraph (b), Paragraph (2), Subsection B., Section 605 of 20.3.6.605 NMAC] above;

2) used for more than 1 hour and less than 1 week at one location (one room, or suite) shall meet the requirement of 605.B.2.b.(2)(a) [Item (ii), Subparagraph (b), Paragraph (2), Subsection B., Section 605 of 20.3.6.605 NMAC] or be provided with 1.98 m (6.5 feet) high protective barrier which is placed at least 1.83 m (6 feet) from the tube housing assembly and at least 1.83 m (6 feet) from the patient; or

3) used to make an exposure(s) of only one patient at the use location shall meet the requirement of 605.B.2.b.(2)(a) [Item (ii), Subparagraph (b), Paragraph (2), Subsection B., Section 605 of 20.3.6.605 NMAC]or 605.B.2.b.(2)(b) [Item(ii), Subparagraph (b), Paragraph (2), Subsection B., Section 605 of 20.3.6.605 NMAC] or be provided with a method of control which will permit the operator to be at least 3.66 m (12 feet) from the tube head assembly during an exposure.

(iii) 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 (Phototimer): When an automatic exposure control is provided:
(a) indication shall be made on the control panel when this mode of operation is selected;

(b) when 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 specified in 605.B.3.b [Subparagraph (b), Paragraph (3), Subsection B., Section 605 of 20.3.6.605 NMAC] 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 when the x-ray tube potential is less than 50 kVp in which case 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 described in 605.B.3.d [Subparagraph (d), Paragraph (3), Subsection B., Section 605 of 20.3.6.605 NMAC], and manual resetting shall be required before further automatically timed exposures can be made. [5-3-95 ]

(4) Reproducibility: With a timer setting of 0.5 seconds or less, the average exposure period (T) shall be greater than or equal to 5 times the maximum exposure period (Tmax) minus the minimum exposure period (Tmin) when 4 timer tests are performed: T 5(Tmax Tmin).

C. Source-to-Source or Receptor Distance Limitation: All radiographic systems shall be provided with a durable, securely fastened means to limit the source-to-skin distance to not less than 30 cm (11.81 inches). This can be met when the collimator or cone provides the required limits.

D. Exposure Reproducibility: The exposure produced shall be reproducible to within the following criteria: When all technique factors are held constant, the coefficient of variation shall not exceed 0.10. This shall be deemed to have been met if when four exposures at identical technique factors are made that the value of the average exposure (E) is greater than or equal to five times the maximum exposure (Emax), minus the minimum exposure (Emin). E5 (Emax Emin)

E. Standby Radiation from Capacitor Energy Storage Equipment: Radiation emitted from the x-ray tube when the exposure switch or timer is not activated shall not exceed a rate of 2 mR (20 mSv) per hour at 5 cm (1.96 inches) from any accessible surface of the diagnostic source assembly, with the beam-limiting device fully open.

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