216-40-20 R.I. Code R. § 4.6

Current through June 20, 2024

Section 216-RICR-40-20-4.6 - Radiographic Equipment

4.6.1Applicability

The provisions of § 4.6 of this Part apply to all non-dental registrants using diagnostic X-ray equipment. X-ray systems subject to § 4.6 of this Part shall also meet the requirements of § 4.4 of this Part. Requirements specific to using dental intra-oral, hand held, panoramic, and cephalometric equipment are in §§ 4.13 and 4.14 of this Part. The useful beam shall be limited to the area of clinical interest.

4.6.2Radiation Exposure Control

A. 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.

B. 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.

C. Operator Protection, Except Veterinary Systems

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.

2. Mobile and Portable Systems. Mobile and portable X-ray systems which are:

a. Used continuously for greater than one (1) week in the same location (i.e., a room or suite) shall meet the requirements of §4.6.2(C)(1) of this Part;

b. Used for less than one (1) week at the same location shall be provided with either a protective barrier at least two meters (2 m) (six and one half feet (6.5')) high for operator protection during exposures or means shall be provided to allow the operator to be at least two and seven tenths meters (2.7 m) (nine feet (9')) from the tube housing assembly during the exposure.

3. Podiatry Systems. Podiatry facilities shall meet the protection requirements in §4.6.2(C)(2)(b) of this Part.

D. Operator and Ancillary Personnel Protection for Veterinary Systems

1. All stationary, mobile or portable X-ray systems used for veterinary work shall be provided with either a two meter (2 m) (six and one half feet (6.5')) high protective barrier for operator protection during exposures or shall be provided with means to allow the operator to be at least two and seven tenths meters (2.7 m) (nine feet (9')) 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 twenty-five one hundredths millimeter (0.25 mm) lead equivalent from scatter radiation and one half millimeter (0.5 mm) from the useful beam. Refer to § 4.13 of this Part for hand-held intraoral dental radiographic units used in veterinary practice.

4.6.3Control and Indication of Technique Factors

A. 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.

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 (0.5) second. Except during panoramic dental radiography, termination of exposure shall cause automatic resetting of the timer to its initial setting or to zero (0). It shall not be possible to make an exposure when the timer is set to a zero (0) or off position if either position is provided.

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.

B. Automatic Exposure Controls. When an automatic exposure control is provided:

1. Indication shall be made on the control panel when this mode of operation is selected;

2. When the X-ray tube potential is equal to or greater than fifty-one kilovolts peak (51 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 one sixtieth of one (1/60) second or a time interval required to deliver five milliampere-seconds (5 mAs), whichever is greater;

3. Either the product of peak X-ray tube potential, current, and exposure time shall be limited to not more than sixty kilowatt-seconds (60 kWs) per exposure or the product of X-ray tube current and exposure time shall be limited to not more than six hundred (600) mAs per exposure, except when the X-ray tube potential is less than fifty-one (51) kVp, in which case the product of X-ray tube current and exposure time shall be limited to not more than two thousand (2,000) mAs per exposure; and

4. A visible signal shall indicate when an exposure has been terminated at the limits described in §4.6.3(B)(3) of this Part, and manual resetting shall be required before further automatically timed exposures can be made.

C. Accuracy. Deviation of technique factors under §4.6.3 of this Part from indicated values shall not exceed the limits given by the manufacturer.

4.6.4Positive Beam Limitation (PBL)

A. The requirements of §4.6.4 of this Part shall apply to radiographic systems which contain PBL.

B. Field Size. When a PBL system is provided, it shall prevent X-ray production when:

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 three percent (3%) of the SID; or

2. The sum of the length and width differences stated in §4.6.4(B)(1) of this Part without regard to sign exceeds four percent (4%) of the SID.

3. The beam-limiting device is at a SID for which PBL is not designed for sizing.

C. Conditions For PBL. When provided, the PBL system shall function as described in §4.6.4(B) of this Part whenever all the following conditions are met:

1. The image receptor is inserted into a permanently mounted cassette holder;

2. The image receptor length and width are less than fifty centimeters (50 cm);

3. The X-ray beam axis is within ± three degrees (± 3°) of vertical and the SID is ninety centimeters (90 cm) to one hundred thirty centimeters (130 cm) inclusive; or the X-ray beam axis is within ± three degrees (± 3°) of horizontal and the SID is ninety centimeters (90 cm) to two hundred five centimeters (205 cm) inclusive;

4. The X-ray beam axis is perpendicular to the plane of the image receptor to within ± three degrees (± 3°); and

5. Neither tomographic nor stereoscopic radiography is being performed.

D. Measuring Compliance. Compliance with the requirements of §4.6.4(B) of this Part shall be determined when the equipment indicates that the beam axis is perpendicular to the plane of the image receptor and the provisions of §4.6.4(B) of this Part are met. Compliance shall be determined no sooner than five (5) seconds after insertion of the image receptor.

E. 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 a SID of one hundred centimeters (100 cm) shall be equal to or less than five centimeters (5 cm). Return to PBL function as described in §4.6.4(B) of this Part shall occur automatically upon any change of image receptor size or SID.

F. 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

1. 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.

G. 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.

4.6.5Source-to-Skin Distance

The minimum source-skin distance shall not be less than thirty centimeters (30 cm), except intraoral dental equipment covered under § 4.14 of this Part and veterinary equipment.

4.6.6Air Kerma Reproducibility

A. 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 five one hundredths (0.05).

1. Measuring compliance. Determination of compliance shall be based on five (5) consecutive measurements taken within a time period of one (1) hour. An additional five (5) consecutive measurements may be taken (ten (10) consecutive measurements total) to determine compliance if the results of the initial five (5) measurements are not compliant. 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 one (± 1) of the mean value for all measurements.

2. 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 twelve (12) pulses on field emission equipment rated for pulsed operation or no less than one tenth of one (0.1) second per exposure on all other equipment.

4.6.7Radiation from Capacitor Energy Storage Equipment

A. Radiation emitted from the X-ray tube shall not exceed:

1. An air kerma of twenty-six one hundredths (0.26) µGy (three one hundredths (0.03) mR exposure) in one (1) minute at five centimeters (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 one hundred square centimeters (100 cm²), with no linear dimensions greater than twenty centimeters (20 cm); and

2. An air kerma of eighty-eight one hundredths (0.88) mGy (one hundred (100) mR exposure) in one (1) hour at one hundred centimeters (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 projected number of discharges in one (1) hour (duty cycle). The measurements shall be averaged over an area of one hundred square centimeters (100 cm²) with no linear dimension greater than twenty centimeters (20 cm).

4.6.8Hand-Holding Restrictions for Portable X-ray Systems

A. 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 exposures.

B. Neither the X-ray tube housing nor the collimating device shall be held during an exposure. Exceptions are allowed for Agency-approved devices specifically designed to be hand-held.

4.6.9[RESERVED]

4.6.10Beam-on Indicators

The X-ray control shall provide visual indication whenever X-rays are produced. In addition, a signal audible to the operator shall indicate that the exposure has terminated.

4.6.11[RESERVED]

4.6.12Field Limitation and Alignment for Mobile, Portable and Stationary General Purpose X-ray Systems

A. Except when spot-film devices are in service, mobile, portable and stationary general purpose radiographic X-ray systems shall meet the following requirements:

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 a SID of one hundred centimeters (100 cm) shall be equal to or less than five centimeters (5 cm).

2. Visual Definition

a. 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 two percent (2%) 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.

b. When a light localizer is used to define the X-ray field, it shall provide an average illuminance of not less than one hundred sixty (160) lux (fifteen (15) footcandles) at one hundred centimeters (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.

c. The edge of the light field at one hundred centimeters (100 cm) or at the maximum SID, whichever is less, shall have a contrast ratio, corrected for ambient lighting, of not less than four (4) in the case of beam-limiting devices designed for use on stationary equipment, and a contrast ratio of not less than three (3) in the case of beamlimiting devices designed for use on mobile and portable equipment. The contrast ratio is defined as I1/I2, where I1 is the illuminance three millimeters (3 mm) from the edge of the light field toward the center of the field; and I2 is the illuminance three millimeters (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 one millimeters (1 mm).

4.6.13Field Indication and Alignment on Stationary General Purpose X-ray Equipment

A. 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 §4.6.12 of this Part:

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 two percent (2%) of the SID, and to indicate the SID to within two percent (2%);

2. The beam-limiting device shall numerically indicate the field size in the plane of the image receptor to which it is adjusted;

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 two percent (2%) of the SID when the beam axis is indicated to be perpendicular to the plane of the image receptor; and

4. Compliance measurements will be made at discrete SIDs and image receptor dimensions in common clinical use (such as SIDs of one hundred (100), one hundred fifty (150), and two hundred (200) centimeters and/or thirty-six (36"), forty (40"), forty-eight (48"), seventy-two (72") inches and nominal image receptor dimensions of thirteen (13), eighteen (18), twenty-four (24), thirty (30), thirty-five (35), forty (40), and forty-three (43) centimeters and/or five (5"), seven (7"), eight (8"), nine (9"), ten (10"), eleven (11"), twelve (12"), fourteen (14"), and seventeen (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.

4.6.14Linearity

A. The following requirements apply for any fixed X-ray tube potential within the range of forty percent (40%) to one hundred percent (100%) of the maximum rated:

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 (2) consecutive tube current settings shall not differ by more than one tenth (0.10) times their sum: X1-X2 [LESS THAN AND EQUAL TO] 0.10 (X1+X2), where X1 and X2 are the average mGy/mAs values obtained at each of two (2) consecutive tube current settings, or at two (2) settings differing by no more than a factor of two (2) where the mA selector provides continuous selection.

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 (2) consecutive mAs selector settings shall not differ by more than one tenth (0.10) times their sum: X1-X2 [LESS THAN AND EQUAL TO] 0.10 (X1 +X2), where X1 and X2 are the average mGy/mAs values obtained at any two (2) consecutive mAs selector settings, or at two (2) settings differing by no more than a factor of two (2) where the mAs selector provides continuous selection.

3. Measuring Compliance. Determination of compliance will be based on ten (10) exposures, made within one (1) hour. These two (2) settings may include any two (2) focal spot sizes except where one (1) is equal to or less than forty-five one hundredths of one millimeter (0.45 mm) and the other is greater than forty-five one hundredths of one millimeter (0.45 mm). For purposes of this requirement, focal spot size is the focal spot size specified by the X-ray tube manufacturer. All values for percent linevoltage regulation at any one (1) combination of technique factors shall be within one (± 1) of the mean value for all measurements at these technique factors.

4.6.15Field Limitation on Radiographic X-ray Equipment Other Than General Purpose Radiographic Systems

A. X-ray Systems Designed for One Image Receptor Size. Radiographic equipment designed for only one (1) 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 two percent (2%) 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.

B. Other X-ray Systems. Radiographic systems not specifically covered in §§4.6.12, 4.6.13, or 4.6.15(A), of this Part 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 two percent (2%) 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 two percent (2%) 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:

1. A system which performs in accordance with §§4.6.12 and 4.6.13 of this Part; or when alignment means are also provided, may be met with either;

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

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.

4.6.16Field Limitation and Alignment for Spot-Film Devices

A. The following requirements shall apply to spot-film devices, except when the spot-film device is provided for use with a radiation therapy simulation system:

1. Means shall be provided between the source and the patient for adjustment of the X-ray field size in the plane of the image receptor to the size of that portion of the image receptor which has been selected on the spot-film selector. Such adjustment shall be accomplished automatically when the X-ray field size in the plane of the image receptor is greater than the selected portion of the image receptor. If the X-ray field size is less than the size of the selected portion of the image receptor, the field size shall not open automatically to the size of the selected portion of the image receptor unless the operator has selected that mode of operation.

2. Neither the length nor width of the X-ray field in the plane of the image receptor shall differ from the corresponding dimensions of the selected portion of the image receptor by more than three percent (3%) of the SID when adjusted for full coverage of the selected portion of the image receptor. The sum, without regard to sign, of the length and width differences shall not exceed four percent (4%) of the SID. On spot film devices manufactured after February 25, 1978, if the angle between the plane of the image receptor and beam axis is variable, means shall be provided to indicate when the axis of the X-ray beam is perpendicular to the plane of the image receptor, and compliance shall be determined with the beam axis indicated to be perpendicular to the plane of the image receptor.

3. The center of the X-ray field in the plane of the image receptor shall be aligned with the center of the selected portion of the image receptor to within two percent (2%) of the SID.

4. Means shall be provided to reduce the X-ray field size in the plane of the image receptor to a size smaller than the selected portion of the image receptor such that:

a. For spot-film devices used on fixed-SID fluoroscopic systems which are not required to, and do not provide stepless adjustment of the X-ray field, the minimum field size, at the greatest SID, does not exceed one hundred twenty-five square centimeters (125 cm²); or

b. For spot-film devices used on fluoroscopic systems that have a variable SID and/or stepless adjustment of the field size, the minimum field size, at the greatest SID, shall be containable in a square of five centimeters (5 cm) by five centimeters (5 cm).

5. A capability may be provided for overriding the automatic X-ray field size adjustment in case of system failure. If it is so provided, a signal visible at the operator's position shall indicate whenever the automatic X-ray field size adjustment override is engaged. Each such system failure override switch shall be clearly labeled as follows: FOR X-RAY FIELD LIMITATION SYSTEM FAILURE.

216 R.I. Code R. § 216-RICR-40-20-4.6

Adopted effective 1/1/2019
Amended effective 5/25/2022
Amended effective 11/28/2023