New Mexico Administrative Code
Title 20 - ENVIRONMENTAL PROTECTION
Chapter 3 - RADIATION PROTECTION
Part 6 - X-RAYS IN HEALING ARTS
Section 20.3.6.604 - FLUOROSCOPIC X-RAY SYSTEMS

Universal Citation: 20 NM Admin Code 20.3.6.604

Current through Register Vol. 35, No. 24, December 23, 2024

All fluoroscopic x-ray systems shall meet the following requirements.

A. Limitation of Useful Beam:

(1) The fluoroscopic tube shall not produce x-rays unless the primary protective barrier is in position to intercept the entire useful beam at all times.

(2) The entire cross-section of the useful beam shall be intercepted by the primary protective barrier of the fluoroscopic image assembly at any SID.

(3) Limitation to the Imaging Surface.
(a) Non-Image-Intensified Fluoroscopy and Spot Filming: The x-ray field produced by non-image-intensified fluoroscopic equipment shall not extend beyond the entire visible area of the image receptor. This requirement applies to field size during both fluoroscopic procedures and spot-filming procedures.

(b) Image-Intensified Fluoroscopy and Spot Filming.
(i) During fluoroscopic or spot-filming procedures, neither the length nor the width of the x-ray field in the plane of the image receptor shall exceed the visible area of the image receptor by more than 3 percent of the SID. The sum of the excess length and the excess width shall be no greater than 4 percent of the SID.

(ii) Compliance shall be determined with the beam axis perpendicular to the image receptor. For rectangular x-ray fields used with circular image reception, the error in alignment shall be determined along the length and width dimensions of the x-ray field which pass through the center of the visible area of the image receptor.

B. Activation of the Fluoroscopic Tube: X-ray production in the fluoroscopic mode shall be controlled by a device which requires continuous pressure by the fluoroscopist for the entire time of any exposure. When recording serial fluoroscopic images, the fluoroscopist shall be able to terminate the x-ray exposure(s) at any time, but means may be provided to permit completion of any single exposure of the series in process.

C. Entrance Exposure Rate Allowable Limits:

(1) The exposure rate measured at the point where the center of the useful beam enters the patient shall not exceed 10 R per minute, (2.58 mC/kg) except during recording of fluoroscopic images or when provided with optional high-level control.

(2) When provided with optional high-level control, the equipment shall not be operable at any combination of tube potential and current which will result in an exposure rate in excess of 5 Rem (1.29 mC/kg) per minute at the point where the center of the useful beam enters the patient unless the high-level control is activated. A continuous signal audible to the fluoroscopist shall indicate that the high-level control is being employed.

(3) Measuring Compliance of Entrance Exposure Rate Limits: Compliance with 604.C [Subsection C., Section 604 of 20.3.6.604 NMAC] shall be determined by:
(a) removing movable grids and compression devices from the useful beam during the measurements;

(b) if the source is below the table, express exposure rate, 1 cm above the tabletop or cradle;

(c) express exposure rate, if the source is above the table, 30 cm above the tabletop with the end of the beam-limiting device or spacer positioned as closely as possible to the point of measurement; and

(d) in a C-arm type of fluoroscope, the exposure rate shall be measured, 30 cm (11.81 inches) from the input surface of the fluoroscopic imaging assembly.

(4) Periodic measurement of entrance exposure rate limits:
(a) periodic measurements of the exposure rate shall be made by a qualified expert. An adequate period for such measurements shall be annually or after any maintenance of the system which might affect the exposure rate.

(b) results of these measurements shall be posted where any fluoroscopist may have ready access to such results while using that fluoroscope and in the record required in 602.A.2.e [Subparagraph (e), Paragraph (2), Subsection A., Section 602 of 20.3.6.602 NMAC]. Results of the measurements shall include the maximum possible Rem/per minute, (1.29 mC/kg) as well as the physical factors used to determine all data; the name of the person performing the measurements; and the date the measurements were performed.

(c) Use of monitoring devices (e.g., commercially available film badges, thermoluminescent dosimeters, or low-energy dosimeters) may be used to perform the test, provided the measurements are made as noted in 604.C.4.d [Subparagraph (d), Paragraph (4), Subsection C. Section 604 of 20.3.6.604 NMAC].

(d) Conditions of measurement:
(i) the measurement shall be made under the conditions that satisfy the requirements of 604.C.3 [Paragraph (3), Subsection C., Section 604 of 20.3.6.604 NMAC];

(ii) the kVp shall be the peak Kv that the x-ray system is capable of producing;

(iii) the high-level control, if present, shall not be activated;

(iv) the x-ray systems that do not incorporate automatic exposure control (automatic brightness control, etc.) shall have sufficient material (e.g., lead or lead equivalence) placed in the useful beam to produce the maximum milliamperage of the x-ray system; and

(v) x-ray systems that incorporate automatic exposure control shall utilize the maximum milliamperage of the x-ray system. Materials (e.g. an attenuation block) may be placed in the useful beam to protect the imaging system.

D. Barrier Transmitted Radiation Rate Limits:

(1) The exposure rate due to transmission through the primary protective barrier with the attenuation block in the useful beam combined with radiation from the image intensifier, if provided, shall not exceed 2 mR (0.516 mC/kg) per hour at 10 cm (3.93 inches) from any surface of the fluoroscopic imaging assembly beyond the plane of the image receptor for each roentgen per minute of entrance exposure rate.

(2) Measuring compliance of barrier transmission:
(a) The exposure rate due to transmission through the primary protective barrier combined with radiation from the image intensifier shall be determined by measurements averaged over an area of 100 sq cm with no linear dimension greater than 20 cm (7.87 inches).

(b) If the source is below the tabletop, the measurement shall be made with the input surface of the fluoroscopic imaging assembly, positioned 30 cm (11.81 inches) above the tabletop.

(c) If the source is above the tabletop and the SID is variable, the measurement shall be made with the end of the beam-limiting device or spacer as close to the tabletop as it can be placed, provided that it shall not be closer than 30 cm (11.81 inches).

(d) Movable grids and compression devices shall be removed from the useful beam during the measurement.

(e) The attenuation block shall be positioned in the useful beam 10 cm (3.93 inches) from the point of measurement of entrance exposure rate and between this point and the input surface of the fluoroscopic imaging assembly.

E. Indication of Potential and Current: During fluoroscopy and cinefluorography, x-ray tube potential and current shall be continuously indicated.

F. Source-Skin Distance: The source to skin distance shall not be less than:

(1) 38 cm (14.96 inches) on stationary fluoroscopes installed after March 10, 1989;

(2) 35.5 cm (13.98 inches) on stationary fluoroscopes which are in operation prior to March 10, 1989;

(3) 30 cm (11.81 inches) on all mobile fluoroscopes; and

(4) 20 cm (7.87 inches) for image intensified fluoroscopes used for specific surgical application. The users operating manual must provide precautionary measures to be adhered to during the use of this device.

G. Fluoroscopic Timer:

(1) Means shall be provided to preset the cumulative on-time of the fluoroscopic tube. The maximum cumulative time of the timing device shall not exceed 5 minutes without resetting.

(2) A signal audible to the fluoroscopist shall indicate the completion of any preset cumulative on-time. Such signal shall continue to sound while x-rays are produced until the timing device is reset.

H. Mobile Fluoroscopes: In addition to the other requirements of 604 [Section 604 of 20.3.6.604 NMAC], mobile fluoroscopes shall provide intensified imaging.

I. Control of Scattered Radiation:

(1) Fluoroscopic table designs when combined with procedures utilized shall be such that no unprotected part of any staff or ancillary person's body shall be exposed to unattenuated scattered radiation which originates from under the table. The attenuation required shall be not less than 0.25 mm lead equivalent.

(2) Equipment configuration when combined with procedures shall be such that no portion of any staff or ancillary person's body, except the extremities, shall be exposed to the unattenuated scattered radiation emanating from above the tabletop unless that individual:
(a) is at least 120 cm (47.24 inches) from the center of the useful beam; or

(b) the radiation has passed through not less than 0.25 mm lead equivalent material (e.g., drapes, Bucky-slot cover, sliding or folding panel, or self supporting curtains) in addition to any lead equivalency provided by the protective apron referred to in 602 A.1.e.(2)[Item (ii), Subparagraph (e), Paragraph (1), Subsection A., Section 602 of 20.3.6.602 NMAC]; and

(c) Exceptions to 604.I.2 [Paragrph (2), Subsection I., Section 604 of 20.3.6.604 NMAC] may be made in some special procedures where a sterile field will not permit the use of the normal protective barriers. Where the use of the prefitted sterilized cover for the barriers is practical, the Department shall not permit such exception.

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