NAC459.566. Fluoroscopic X-ray systems: Limitation of useful beam; spot filming.

All fluoroscopic X-ray systems must meet the following requirements:

     1. The fluoroscopic tube must 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 must be intercepted by the primary protective barrier of the fluoroscopic image assembly at any source-image receptor distance.

     3. The X-ray field produced by fluoroscopic equipment without image intensification must 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.

     4. During fluoroscopic or spot-filming procedures, neither the length nor the width of the X-ray field in the plane of the image receptor may exceed the visible area of the image receptor by more than 3 percent of the source-image receptor distance. The sum of the excess length and the excess width must be no greater than 4 percent of the source-image receptor distance.

     5. Compliance will 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 will 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.

     6. In addition to other requirements of NAC 459.400 to 459.624, inclusive, for new equipment installed after February 28, 1980:

     (a) A means must be provided between the source and the patient for adjustment of the X-ray field size in the plane of the film to the size of that portion of the film which has been selected on the spot-film selector. Such an adjustment must be automatically accomplished except when the X-ray field size in the plane of the film is smaller than that of the selected portion of the film.

     (b) It must be possible to adjust the X-ray field size in the plane of the film to a size smaller than the selected position of the film. The minimum field size at the greatest source-image receptor distance must be equal to or less than 5 by 5 centimeters.

     (c) The center of the X-ray field in the plane of the film must be aligned with the center of the selected portion of the film to within 2 percent of the source-image receptor distance.

     [Bd. of Health, Radiation Control Reg. §§ 6.5-6.5.1.3.3.3, eff. 2-28-80]