16 Del. Admin. Code § 4465-F-6.0

Current through Register Vol. 28, No. 7, January 1, 2025

Section 4465-F-6.0 - Radiographic Equipment

6.1 The following regulations apply to all non-dental registrants using diagnostic x-ray equipment. Requirements specific to using dental intra-oral, hand held, panoramic, and cephalometric equipment are in Part F, Section 7.0.

6.2 Digital radiographic systems shall be evaluated by a QMP (QE) prior to clinical use, and at least annually. The evaluation shall follow nationally recognized standards or procedures. Unless otherwise specified in this Part, dental, podiatric, and veterinary systems are exempt from this requirement.

6.3 Control and indication of technique factors.

6.3.1 Timers. Means shall be provided to terminate the exposure at a preset time interval, a preset product of current and time, a preset number of pulses, or a preset radiation exposure to the image receptor. (21CFR 1020.31(a)(2))

6.3.1.1 Except during serial radiography, the operator shall be able to terminate the exposure at any time during an exposure of greater than one-half second. Except during panoramic dental radiography, termination of exposure shall cause automatic resetting of the timer to its initial setting or to zero. 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. (21CFR 1020.31(a)(2)(i))

6.3.1.2 During serial radiography, the operator 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. (21CFR 1020.31(a)(2)(ii))

6.3.2 Automatic exposure controls. When an automatic exposure control is provided:

6.3.2.1 Indication shall be made on the control panel when this mode of operation is selected; (21CFR 1020.31(a)(3)(i))

6.3.2.2 When the x-ray tube potential is equal to or greater than 51 kilovolts peak (kVp), the minimum exposure time for field emission equipment rated for pulse operation shall be equal to or less than a time interval equivalent to two pulses and the minimum exposure time for all other equipment shall be equal to or less than 1/60 second or a time interval required to deliver 5 milliampere-seconds (mAs), whichever is greater; (21CFR 1020.31(a)(3)(ii))

6.3.2.3 Either the product of peak x-ray tube potential, current, and exposure time shall be limited to not more than 60 kilowatt-seconds (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 51 kVp, in which case the product of x-ray tube current and exposure time shall be limited to not more than 2,000 mAs per exposure; and (21CFR 1020.31(a)(3)(iii))

6.3.2.4 A visible signal shall indicate when an exposure has been terminated at the limits described in Part F, subsection 6.3.2.3, and manual resetting shall be required before further automatically timed exposures can be made. (21CFR 1020.31(a)(3)(iv))

6.3.3 Accuracy. Deviation of technique factors under Part F, subsection 6.3 from indicated values shall not exceed the limits given by the manufacturer. (variation of 21CFR 1020.31(a)(4))

6.4 Reproducibility.

6.4.1 Coefficient of variation. For any specific combination of selected technique factors, the estimated coefficient of variation of the air kerma shall be no greater than 0.05. (21CFR 1020.31(b)(1)

6.4.2 Measuring compliance. Determination of compliance shall be based on 10 consecutive measurements taken within a time period of 1 hour. Equipment manufactured after September 5, 1978, shall be subject to the additional requirement that all variable controls for technique factors shall be adjusted to alternate settings and reset to the test setting after each measurement. The percent line-voltage regulation shall be within ±1 of the mean value for all measurements. For equipment having automatic exposure controls, compliance shall be determined with a sufficient thickness of attenuating material in the useful beam such that the technique factors can be adjusted to provide individual exposures of a minimum of 12 pulses on field emission equipment rated for pulsed operation or no less than one-tenth second per exposure on all other equipment. (21CFR 1020.31(b)(2))

6.5 Linearity. The following requirements apply for any fixed x-ray tube potential within the range of 40 percent to 100 percent of the maximum rated. (variation of 21CFR 1020.31(c))

6.5.1 Equipment having independent selection of x-ray tube current (mA). The average ratios of air kerma to the indicated milliampere-seconds product (mGy/mAs) obtained at any two consecutive tube current settings shall not differ by more than 0.10 times their sum. This is: IX1 - X20.10 >= I(X1 + X2); where X1 and X2 are the average mGy/mAs values obtained at each of two consecutive mAs selector settings or at two settings differing by no more than a factor of 2 where the mAs selector provides continuous selection. (21CFR 1020.31(c)(1))

6.5.2 Equipment having selection of x-ray tube current-exposure time product (mAs). For equipment manufactured after May 3, 1994, the average ratios of air kerma to the indicated milliampere-seconds product (mGy/mAs) obtained at any two consecutive mAs selector settings shall not differ by more than 0.10 times their sum. This is: IX1 - X20.10 >= I(X1 + X2); where X1 and X2 are the average mGy/mAs values obtained at each of two consecutive mAs selector settings or at two settings differing by no more than a factor of 2 where the mAs selector provides continuous selection. (21CFR 1020.31(c)(2))

6.5.3 Measuring compliance. Determination of compliance will be based on 10 exposures, made within 1 hour, at each of the two settings. These two settings may include any two focal spot sizes except where one is equal to or less than 0.45 mm and the other is greater than 0.45 mm. For purposes of this requirement, focal spot size is the focal spot size specified by the x-ray tube manufacturer. The percent line-voltage regulation shall be determined for each measurement. All values for percent line-voltage regulation at any one combination of technique factors shall be within ±1 of the mean value for all measurements at these technique factors. (21CFR 1020.31(c)(3))

6.6 Field limitation and alignment for mobile, portable, and stationary general purpose x-ray systems. Except when spot-film devices are in service, mobile, portable, and stationary general purpose radiographic x-ray systems shall meet the following requirements: (21CFR 1020.31(d))

6.6.1 Variable x-ray field limitation. A means for stepless adjustment of the size of the x-ray field shall be provided. Each dimension of the minimum field size at an SID of 100 cm shall be equal to or less than 5 cm. (21CFR 1020.31(d)(1))

6.6.2 Visual definition.

6.6.2.1 Means for visually defining the perimeter of the x-ray field shall be provided. The total misalignment of the edges of the visually defined field with the respective 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. (21CFR 1020.31(d)(2)(i))

6.6.2.2 When a light localizer is used to define the x-ray field, it shall provide an average illuminance of not less than 160 lux (15 footcandles) at 100 cm or at the maximum SID, whichever is less. The average illuminance shall be based on measurements made in the approximate center of each quadrant of the light field. Radiation therapy simulation systems are exempt from this requirement. (21CFR 1020.31(d)(2)(ii))

6.6.2.3 The edge of the light field at 100 cm or at the maximum SID, whichever is less, shall have a contrast ratio, corrected for ambient lighting, of not less than 4 in the case of beam-limiting devices designed for use on stationary equipment, and a contrast ratio of not less than 3 in the case of beam-limiting devices designed for use on mobile and portable equipment. The contrast ratio is defined as I1/I2, where I1 is the illuminance 3 mm from the edge of the light field toward the center of the field; and I2 is the illuminance 3 mm from the edge of the light field away from the center of the field. Compliance shall be determined with a measuring aperture of 1 mm. (21CFR 1020.31(d)(2)(iii))

6.7 Field indication and alignment on stationary general purpose x-ray equipment. Except when spot-film devices are in service, stationary general purpose x-ray systems shall meet the following requirements in addition to those prescribed in Part F, subsection 6.6: (21CFR 1020.31(e))

6.7.1 Means shall be provided 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; (21CFR 1020.31(e)(1))

6.7.2 The beam-limiting device shall numerically indicate the field size in the plane of the image receptor to which it is adjusted; (21CFR 1020.31(e)(2))

6.7.3 Indication of field size dimensions and SIDs shall be specified in centimeters and/or inches and shall be such that aperture adjustments result in x-ray field dimensions in the plane of the image receptor which correspond to those indicated by the beam-limiting device to within 2 percent of the SID when the beam axis is indicated to be perpendicular to the plane of the image receptor; and (21CFR 1020.31(e)(3))

6.7.4 Compliance measurements will be made at discrete SIDs and image receptor dimensions in common clinical use (such as SIDs of 100, 150, and 200 cm and/or 36, 40, 48, 72 inches and nominal image receptor dimensions of 13, 18, 24, 30, 35, 40, and 43 cm and/or 5, 7, 8, 9, 10, 11, 12, 14, and 17 inches) or at any other specific dimensions at which the beam-limiting device or its associated diagnostic x-ray system is uniquely designed to operate. (21CFR 1020.31(e)(4))

6.8 Field limitation on x-ray equipment other than general purpose radiographic systems.

6.8.1 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 image receptor to within 2 percent of the SID, or shall be provided with means to both size and align the x-ray field such that the x-ray field at the plane of the image receptor does not extend beyond the edge of the image receptor.

6.8.2 Other x-ray systems. Radiographic systems not specifically covered in Part F, subsection 6.6, subsection 6.8.2, subsection 6.8.3, and systems covered in Part F, subsection 6.8.1, which are also designed for use with extraoral image receptors and when used with an extraoral image receptor, 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. In addition, means shall be provided to align the center of the x-ray field with the center of the image receptor to within 2 percent of the SID, or means shall be provided to both size and alignment the x-ray field such that the x-ray field at the plane of the image receptor does not extend beyond any edge of the image receptor. These requirements may be met with: (21CFR 1020.31(f)(4))

6.8.2.1 A system which performs in accordance with Part F, subsection 6.6 and Part F, subsection 6.7; or when alignment means are also provided, may be met with either; (21CFR 1020.31(f)(4)(i))

6.8.2.2 An assortment of removable, fixed-aperture, beam-limiting devices sufficient to meet the requirement 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 (21CFR 1020.31(f)(4)(ii))

6.8.2.3 A beam-limiting device having multiple fixed apertures sufficient to meet the requirement 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. (21CFR 1020.31(f)(4)(iii))

6.9 Positive beam limitation (PBL). The requirements of this subsection shall apply to radiographic systems which contain PBL. (21CFR 1020.31(g))

6.9.1 Field size. When a PBL system is provided, it shall prevent x-ray production when: (21CFR 1020.31(g)(1))

6.9.1.1 Either the length or width of the x-ray field in the plane of the image receptor differs from the corresponding image receptor dimension by more than 3 percent of the SID; or (21CFR 1020.31(g)(1)(i))

6.9.1.2 The sum of the length and width differences stated in Part F, subsection 6.9.1.1 without regard to sign exceeds 4 percent of the SID. (21CFR 1020.31(g)(1)(ii))

6.9.1.3 The beam-limiting device is at an SID for which PBL is not designed for sizing. (21CFR 1020.31(g)(1)(iii))

6.9.2 Conditions for Positive Beam Limitation (PBL). When provided, the PBL system shall function as described in Part F, subsection 6.9.1 whenever all the following conditions are met: (21CFR 1020.31(g)(2))

6.9.2.1 The image receptor is inserted into a permanently mounted cassette holder; (21CFR 1020.31(g)(2)(i))

6.9.2.2 The image receptor length and width are less than 50 cm; (21CFR 1020.31(g)(2)(ii))

6.9.2.3 The x-ray beam axis is within ±3 degrees of vertical and the SID is 90 cm to 130 cm inclusive; or the x-ray beam axis is within ±3 degrees of horizontal and the SID is 90 cm to 205 cm inclusive; (21CFR 1020.31(g)(2)(iii))

6.9.2.4 The x-ray beam axis is perpendicular to the plane of the image receptor to within ±3 degrees; and (21CFR 1020.31(g)(2)(iv))

6.9.2.5 Neither tomographic nor stereoscopic radiography is being performed. (21CFR 1020.31(g)(2)(v))

6.9.3 Measuring compliance. Compliance with the requirements of Part F, subsection 6.9.1 shall be determined when the equipment indicates that the beam axis is perpendicular to the plane of the image receptor and the provisions of Part F, subsection 6.9.2 are met. Compliance shall be determined no sooner than 5 second after insertion of the image receptor. (21CFR 1020.31(g)(3))

6.9.4 Operator initiated undersizing. The PBL system shall be capable of operating such that, at the discretion of the operator, the size of the field may be made smaller than the size of the image receptor through stepless adjustment of the field size. Each dimension of the minimum field size at an SID of 100 cm shall be equal to or less than 5 cm. Return to PBL function as described in Part F, subsection 6.9.1 shall occur automatically upon any change of image receptor size or SID. (21CFR 1020.31(g)(4))

6.9.5 Override of PBL. A capability may be provided for overriding PBL in case of system failure and for servicing the system. This override may be for all SIDs and image receptor sizes. A key shall be required for any override capability that is accessible to the operator. It shall not be possible to remove the key while PBL is overridden. Each such key switch or key shall be clearly and durably labeled as follows:

For X-Ray Field Limitation System Failure

The override capability is considered accessible to the operator if it is referenced in the operator's manual or in other material intended for the operator or if its location is such that the operator would consider it part of the operational controls. (21CFR 1020.31(g)(5))

6.9.6 Disabling of PBL. A facility has the option to permanently functionally disable a PBL system. When this option is chosen, the standards for manual collimation apply.

6.10 Source-skin distance. The minimum source-skin distance shall not be less than 30 cm, except intraoral dental equipment covered under Part F, subsection 7.17.2 and veterinary equipment.

6.11 Radiation from capacitor energy storage equipment. Radiation emitted from the x-ray tube shall not exceed: (21CFR 1020.31(l))

6.11.1 An air kerma of 0.26 microGy (vice 0.03 mR exposure) in 1 minute at 5 cm from any accessible surface of the diagnostic source assembly, with the beam-limiting device fully open, the system fully charged, and the exposure switch, timer, or any discharge mechanism not activated. Compliance shall be determined by measurements averaged over an area of 100 square cm, with no linear dimensions greater than 20 cm; and(21CFR 1020.31(l)(1))

6.11.2 An air kerma of 0.88 mGy (vice 100 mR exposure) in one hour at 100 cm from the x-ray source, with beam-limiting device fully open, when the system is discharged through the x-ray tube either manually or automatically by use of a discharge switch or deactivation of the input power. Compliance shall be determined by measurements of the maximum air kerma per discharge multiplied by the total number of discharges in 1 hour (duty cycle). The measurements shall be averaged over an area of 100 square cm with no linear dimension greater than 20 cm. (21CFR 1020.31(l)(2))

6.12 Radiation Exposure Control.

6.12.1 Exposure Initiation. Means shall be provided to initiate the radiation exposure by a deliberate action on the part of the operator, such as the depression of a switch. Radiation exposure shall not be initiated without such an action. In addition, it shall not be possible to initiate an exposure when the timer is set to a "zero" or "off" position if either position is provided.

6.12.2 Exposure Indication. Means shall be provided for 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.

6.12.3 Operator Protection, Except Veterinary Systems.

6.12.3.1 Stationary Radiographic Systems. Stationary radiographic systems shall be required to have the x-ray control, including the exposure switch, permanently mounted in a protected area so that the operator is required to remain in that protected area during the entire exposure.

6.12.3.2 Mobile and Portable Systems. Mobile and portable x-ray systems which are:

6.12.3.2.1 Used continuously for greater than one week in the same location, i.e., a room or suite, shall meet the requirements of Part F, subsection 6.12.3.1;

6.12.3.2.2 Used for less than one week at the same location shall be provided with either a protective barrier at least 2 meters (6.5 feet) high for operator protection during exposures, or means shall be provided to allow the operator to be at least 2.7 meters (9 feet) from the tube housing assembly during the exposure.

6.12.3.2.3 Podiatry Systems. Podiatry facilities shall meet the protection requirements in Part F, subsection 6.12.3.2.2.

6.12.4 Operator and Ancillary Personnel Protection for Veterinary Systems. All stationary, mobile or portable x-ray systems used for veterinary work shall be provided with either a 2 meter (6.5 feet) high protective barrier for operator protection during exposures, or shall be provided with means to allow the operator to be at least 2 meters (6.5 feet) from the tube housing assembly during exposures. Otherwise, in cases where animals are held, the operator and ancillary personnel shall be protected by a minimum of 0.25 mm lead equivalent from scatter radiation and 0.5 mm from the useful beam. Refer to Part F, Section 7.0 for hand-held intraoral dental x-ray units used in veterinary practice.

6.13 Tube Stands for Portable X-Ray Systems. Except during veterinary field operations where it is impractical to do so, a tube stand or other mechanical support shall be used for portable x-ray systems, so that the x-ray tube housing assembly need not be hand-held during an exposure.

6.14 Systems designed for mammography. All systems designed for mammography shall comply with Mammography Quality Standards Act of 1998.

6.15 Prohibitions. Capacity energy storage equipment shall not be used to image humans 2 years after the effective date of this Part.

16 Del. Admin. Code § 4465-F-6.0

16 DE Reg. 1274(6/1/2013)
22 DE Reg. 401( 11/1/2018) (Final)