Specific Requirements for Radiographic X-ray Equipment.
24 RCNY § 175.48
in effect§ 175.48 Specific Requirements for Radiographic X-ray Equipment.
The requirements of this section apply to all non-dental registrants using diagnostic x-ray equipment.
(a) Acceptance testing. Each registrant must have acceptance testing conducted on all radiographic x-ray units with the exception of dental, podiatric, and bone densitometer units, prior to clinical patient exams being conducted with the designated x-ray units. The acceptance testing must be conducted by a QMP and the report must be provided to the registrant. All non- compliance issues noted in this report must be corrected prior to clinical use of the unit. The acceptance testing report must verify the stated manufacturer's tolerances for all machine testing. If manufacturer tolerances are absent, the registrant's QMP must develop tolerances that must be used in subsequent QA testing by the registrant and must be so noted in the quality assurance manual.
(b) Control and indication of technique factors.
(1) Timers. Means must 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.
(i) Except during serial radiography, the operator must 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 must cause automatic resetting of the timer to its initial setting or to zero. It must not be possible to make an exposure when the timer is set to a zero or off position if either position is provided.
(ii) During serial radiography, the operator must 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.
(2) Automatic exposure controls. When an automatic exposure control is provided:
(i) indication must be made on the control panel when this mode of operation is selected;
(ii) 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 must be equal to or less than a time interval equivalent to two pulses and the minimum exposure time for all other equipment must be equal to or less than 1/60 second or a time interval required to deliver 5 milliampere-seconds (mAs), whichever is greater;
(iii) either the product of peak x-ray tube potential, current, and exposure time must be limited to not more than 60 kilowatt-seconds (kWs) per exposure or the product of x-ray tube current and exposure time must 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 must be limited to not more than 2,000 mAs per exposure; and
(iv) a visible signal must indicate when an exposure has been terminated at the limits described in subparagraph (iii) of this paragraph, and manual resetting must be required before further automatically timed exposures can be made.
(c) Reproducibility.
(1) Coefficient of variation. For any specific combination of selected technique factors, the estimated coefficient of variation of the air kerma must be no greater than 0.05.
(2) Measuring compliance. Determination of compliance must be based on 10 consecutive measurements taken within a time period of 1 hour. Equipment manufactured after September 5, 1978, must also have all variable controls for technique factors adjusted to alternate settings and reset to the test setting after each measurement. 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.
(3) Alternatively, the reproducibility of any technique value may be determined by taking 5 consecutive measurements and utilizing the formula given below:
Reproducibility = (maximum measured value - minimum measured value)
Average of the measured five values
The calculated reproducibility shall be equal to ± 10 percent for compliance.
(d) 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. In regard to paragraphs (1) through (3) in this subdivision below, measurements can be made in mR instead of mGy.
(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 must not differ by more than 0.10 times their sum. This is: |X1 - X2 ≤ | 0.10(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.
(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 must not differ by more than 0.10 times their sum. This is: |X1 - X2 ≤ | 0.10(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.
(3) Measuring compliance. Determination of compliance will be based on at least 3 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.
(e) 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 must meet the following requirements:
(1) Variable x-ray field limitation. A means for stepless adjustment of the size of the x-ray field must be provided. Each dimension of the minimum field size at an SID of 100 cm must be equal to or less than 5 cm.
(2) Visual definition.
(i) Means for visually defining the perimeter of the x-ray field must 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 must 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.
(ii) When a light localizer is used to define the x-ray field, it must 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.
(iii) The edge of the light field at 100 cm or at the maximum SID, whichever is less, must 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.
(f) 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 must meet the following requirements, in addition to those prescribed in subdivision (e) of this section:
(1) Means must 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;
(2) The beam-limiting device must 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 must be specified in centimeters or inches and must 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
(4) Compliance measurements will be made at each SID in common clinical use (such as SIDs of 100, 150, and 200 cm or 36, 40, 48, 72 inches) and with at least one of the commonly used image receptor dimensions (such as nominal image receptor dimensions of 13, 18, 24, 30, 35, 40, and 43 cm 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.
(g) Field limitation on x-ray equipment other than general purpose radiographic systems.
(1) X-ray systems designed for one image receptor size. Radiographic equipment designed for only one image receptor size at a fixed SID must 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 must 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.
(2) Other x-ray systems. Radiographic systems not specifically covered in subdivisions (e) and (f) of this section, and paragraph (1) of this subdivision, which are also designed for use with extraoral image receptors and when used with an extraoral image receptor, must 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 must 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 must be provided 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 any edge of the image receptor. These requirements may be met with:
(i) A system which performs in accordance with subdivisions (e) and (f) of this section or when alignment means are also provided, may be met with either;
(ii) 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 must have clear and permanent markings to indicate the image receptor size and SID for which it is designed; or
(iii) 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 must indicate the image receptor size and SID for which each aperture is designed and must indicate which aperture is in position for use.
(h) Positive beam limitation (PBL). The requirements of this subdivision apply to radiographic systems which contain PBL and which the registrant has not disabled.
(1) Field size. When a PBL system is provided, it must prevent x-ray production when:
(i) 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
(ii) The sum of the length and width differences stated in subparagraph (i) of this paragraph without regard to sign exceeds 4 percent of the SID.
(iii) The beam-limiting device is at an SID for which PBL is not designed for sizing.
(2) Conditions for PBL. When provided and if the registrant has not disabled it, the PBL system must function as described in subparagraph (i) of paragraph (1) of this subdivision. whenever all the following conditions are met:
(i) The image receptor is inserted into a permanently mounted cassette holder;
(ii) The image receptor length and width are less than 50 cm;
(iii) 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;
(iv) The x-ray beam axis is perpendicular to the plane of the image receptor to within ±3 degrees; and
(v) Neither tomographic nor stereoscopic radiography is being performed.
(3) Measuring compliance. Compliance with the requirements of subparagraph (i) of paragraph (1) of this subdivision shall be determined when the equipment indicates that the beam axis is perpendicular to the plane of the image receptor and the provisions of paragraph (2) of this subdivision are met. Compliance shall be determined no sooner than 5 seconds after insertion of the image receptor.
(4) Operator initiated undersizing. The PBL system must 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 must be equal to or less than 5 cm. Return to PBL function as described in paragraph (1) of this subdivision must occur automatically upon any change of image receptor size or SID.
(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 must be required for any override capability that is accessible to the operator. It must not be possible to remove the key while PBL is overridden. Each such key switch or key must 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.
(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.
(i) Source-skin distance. The minimum source-skin distance must not be less than 30 cm, except intraoral dental equipment regardless of clinical or veterinary use.
(j) Radiation from capacitor energy storage equipment. Radiation emitted from the x-ray tube must not exceed:
(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; and
(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).
(k) 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 must be used for portable x-ray systems, so that the x-ray tube housing assembly need not be hand-held during an exposure.
(l) Conditions of use.
(1) The x-ray image receptor used as recording medium during the x-ray examination must show visual evidence of cut-off (beam delineation) on all four sides of the x- ray image. This applies to all x-ray units using manual collimation and where no positive means are used to contain the x-ray field to the size of the image receptor. The x-ray image receptor can be film or digital image receptors.
(2) Personnel monitoring must be required for all persons operating mobile or portable x-ray equipment, except hand-held dental x-ray units.
(3) No person shall be regularly employed to hold patients during exposures nor shall such duty be performed by an individual occupationally exposed to radiation in the course of that individual's other duties. When it is necessary to immobilize the patient, mechanical supporting or immobilizing devices should be used. Written safety procedures must provide the selection criteria for the holder and protocol to be followed during the patient holding procedure.
(4) If patients must be held by an individual, that individual must be instructed in personal radiation safety and must be protected with appropriate shielding devices such as protective gloves and a protective garment of at least 0.25 mm lead equivalent. No part of the holding individual's body shall be in the useful beam. The exposure of any individual used for holding patients must be monitored.
(5) For patients who have not passed the reproductive age, gonadal shielding of not less than 0.5 mm lead equivalent must be used during radiographic procedures in which the gonads are in the useful beam, except for cases in which this would interfere with the diagnostic procedure.
(6) Pregnant women and individuals under 18 years of age must not hold patients under any conditions.
(Added City Record 4/24/2019, eff. 5/24/2019)
Source: City of New York, Charter, Administrative Code and Rules (American Legal Publishing XML export, codelibrary.amlegal.com)URL: https://codelibrary.amlegal.com/codes/newyorkcity/latest/NYCrules/0-0-0-117358Fetched: 10/24/2026