DHS 157.76(2)(e)1.1. When any linear dimension of the visible area of the image receptor measured through the center of the visible area is less than or equal to 34 cm in any direction, at least 80% of the area of the x-ray field overlaps the visible area of the image receptor. DHS 157.76(2)(e)2.2. When any linear dimension of the visible area of the image receptor measured through the center of the visible area is greater than 34 cm in any direction, the x-ray field measured along the direction of greatest misalignment with the visible area of the image receptor does not extend beyond the edge of the visible area of the image receptor by more than 2 cm. DHS 157.76(2)(f)(f) For x-ray systems with inherently rectangular image receptors manufactured on or after June 10, 2006, all the following applies: DHS 157.76(2)(f)1.1. Neither the length nor the width of the x-ray field in the plane of the image receptor shall exceed that of the visible area of the image receptor by more than 3% of the source to image distance. The sum of the excess length and the excess width shall be no greater than 4% of the source to image distance. DHS 157.76(2)(f)2.2. 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. DHS 157.76(2)(g)(g) If the fluoroscopic x-ray field size is adjusted automatically as the source to image distance or image receptor size is changed, a capability may be provided for overriding the automatic adjustment in case of system failure. If it is so provided, a signal visible at the fluoroscopist’s position shall indicate whenever the automatic field adjustment is overridden. Each such system failure override switch shall be clearly labeled as follows: For X-ray Field Limitation System Failure
DHS 157.76(3)(3) Activation of tube. X-ray production in the fluoroscopic mode shall be controlled by a device which requires continuous pressure by the operator for the entire time of any exposure. When recording serial radiographic images from the fluoroscopic image receptor, the operator shall be able to terminate the x-ray exposure at any time, but means may be provided to permit completion of any single exposure of the series in process. DHS 157.76(4)(a)(a) Fluoroscopic equipment manufactured before May 19, 1995 shall meet all the following requirements: DHS 157.76(4)(a)1.1. Equipment provided with automatic exposure rate control shall not be operable at any combination of tube potential and current that will result in an air kerma rate in excess of 88 mGy per minute (10 R/min) at the measurement point specified in par. (e), except as specified in par. (e) 6. DHS 157.76(4)(a)2.2. Equipment provided without automatic exposure rate control shall not be operable at any combination of tube potential and current that will result in an air kerma rate in excess of 44 mGy per minute (5 R/min) at the measurement point specified in par. (e), except as specified in par. (e) 6. DHS 157.76(4)(a)3.3. Equipment provided with both an automatic exposure rate control mode and a manual mode shall not be operable at any combination of tube potential and current that will result in an air kerma rate in excess of 88 mGy per minute (10 R/min) in either mode at the measurement point specified in par. (e), except as specified in par. (e) 6. DHS 157.76(4)(a)4.4. Equipment may be modified in accordance with 21 CFR 1020.30(q) to comply with par. (a). When the equipment is modified, it shall bear a label indicating the date of the modification and the statement: DHS 157.76(4)(b)2.2. When a mode of operation has an optional high-level control, in which case that mode shall not be operable at any combination of tube potential and current that will result in an air kerma rate in excess of the rates specified in this subsection at the measurement point specified in par. (e), unless the high-level control is activated. Special means of activation of high-level controls shall be required. The high-level control shall be operable only when continuous manual activation is provided by the operator. A continuous signal audible to the fluoroscopist shall indicate that the high-level control is being employed. DHS 157.76(4)(c)(c) Fluoroscopic equipment manufactured on or after May 19, 1995 shall meet all the following requirements: DHS 157.76(4)(c)1.1. Equipped with automatic exposure rate control if operable at any combination of tube potential and current that results in an air kerma rate greater than 44 mGy per minute (5 R/min) at the measurement point specified in this subsection. Provision for manual selection of technique factors may be provided. DHS 157.76(4)(c)2.2. Not be operable at any combination of tube potential and current that will result in an air kerma rate in excess of 88 mGy per minute (10 R/min) at the measurement point specified in par. (e) DHS 157.76(4)(d)1.1. For equipment manufactured prior to June 10, 2006, during the recording of images from a fluoroscopic image receptor using photographic film or a video camera when the x-ray source is operated in a pulsed mode. DHS 157.76(4)(d)2.2. For equipment manufactured on or after June 10, 2006, during the recording of images from the fluoroscopic image receptor for the purpose of providing the user with a recorded image after termination of exposure. Such recording does not include images resulting from a last image-hold feature that are not recorded. DHS 157.76(4)(d)3.3. When a mode of operation has an optional high-level control and the control is activated, in which case the equipment shall not be operable at any combination of tube potential and current that will result in an air kerma rate in excess of 176 mGy per minute (20 R/min) at the measurement point specified par. (e). Special means of activation of high-level controls shall be required. The high-level control shall be operable only when continuous manual activation is provided by the operator. A continuous signal audible to the fluoroscopist shall indicate that the high-level control is being employed. DHS 157.76(4)(e)1.1. If the source is below the x-ray table, the air kerma rate shall be measured at 1 cm above the tabletop or cradle. DHS 157.76(4)(e)2.2. If the source is above the x-ray table, the air kerma rate shall be measured at 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. DHS 157.76(4)(e)3.3. In a C-arm type of fluoroscope, the air kerma rate shall be measured at 30 cm from the input surface of the fluoroscopic imaging assembly, with the source positioned at any available source to image distance, provided that the end of the beam limiting device or spacer is no closer than 30 cm from the input surface of the fluoroscopic imaging assembly.