Special Requirements for Medical Fluoroscopic Installations

PURPOSE: This rule establishes special requirements for medical fluoroscopic installations. (1) All fluoroscopes shall be so constructed that the entire cross-section of the useful beam is attenuated by a primary barrier. Collimators and adjustable diaphragms or shutters shall be provided to restrict the size of the useful beam to less than the area of the barrier. For conventional fluoroscopes, this requirement is met if, when the adjustable diaphragm is open to its fullest extent, an unilluminated two centimeter (2 cm) margin is left on the fluorescent screen with the screen centered in the beam at a distance of thirty-five centimeters (35 cm) (fourteen inches (14")) from the panel or table top. The margin requirement does not apply to installations where image amplifiers are used but a protective shield shall be provided in these installations so that the useful beam does not produce a radiation hazard. (2) Accessory shielding devices (such as cones, curtains, bucky slot covers, shielding between patient and fluoroscopist) shall be used as required to reduce the exposure dose rate to not more than fifty (50) milliroentgens per hour in the area adjacent to the machine normally occupied by the fluoroscopist and his/her assistants during fluoroscopy. (3) The target to panel distance shall not be less than eighteen inches (18"). (4) A manually reset cumulative timing device shall be used which will either indicate elapsed time by an audible signal or turn off the apparatus when the total exposure exceeds a predetermined limit given in one (1) or a series of exposures. The device shall have a maximum range of five (5) minutes. (5) The primary beam barrier should have a lead equivalent of at least 2.0 millimeters (mm) and shall not be less than 1.5 mm for one hundred (100) kvp, should be at least 2.4 mm and shall be not less than 1.8 mm for one hundred twenty-five (125) kvp, and should be at least 2.7 mm and shall be not less than 2.0 mm for one hundred fifty (150) kvp. For conventional fluoroscopes, this requirement may be assumed to have been met if the exposuredose rate measured at the viewing surface of the fluorescent screen does not exceed fifty (50) milliroentgens per hour with the screen in the primary beam of the fluoroscope without a patient, under normal operating conditions. (6) Collimators and adjustable diaphragms or shutters to restrict the size of the useful beam shall provide a minimum of 2.0 mm lead equivalent protection for one hundred (100) kvp, 2.4 mm for one hundred twenty-five (125) kvp and 2.7 mm for one hundred fifty (150) kvp. (7) For routine fluoroscopy, the dose rate measured at the panel or table top shall not exceed six (6) roentgens per minute. (8) Mobile fluoroscopic equipment shall meet the requirements of sections (1)–(7) of this rule except that— (A) In the absence of panel or table top, a cone or spacer frame hall limit the target-toskin distance to not less than twelve inches (12"); (B) It shall be impossible to operate the machine when the collimating cone or diaphragm is not in place; and (C) The maximum permissible exposuredose rate of six (6) roentgens per minute shall be measured at the minimum target-to-skin distance. AUTHORITY: section 192.420, RSMo 1986.* This rule was previously filed as 13 CSR 5090.130. Original rule filed Nov. 9, 1964, effective Dec. 9, 1964. *Original authority: 192.420, RSMo 1963.