Section 216-RICR-40-20-4.2 - DefinitionsA. Whenever used in this Part, the following terms shall be construed as follows:1. "Accessible surface" means the external surface of the enclosure or housing of the radiation producing machine as provided by the manufacturer.2. "Act" means R.I. Gen. Laws Chapter 23-1.3, entitled "Radiation Control."3. "Agency" means Rhode Island Radiation Control Agency (RCA), Center for Health Facilities Regulation - Radiation Control Program, Rhode Island Department of Health.4. "Air kerma" means kerma in air (see definition of Kerma).5. "Air kerma rate" or "AKR" means the air kerma per unit time.6. "Alert value" means a dose index (e.g., of CTDIvol(mGy) or DLP(mGy-cm)) that is set by the registrant to trigger an alert to the CT operator prior to scanning within an ongoing examination. The Alert value represents a universal dose index value well above the registrant's established range for the examination that warrants more stringent review and consideration before proceeding. 7. "Aluminum equivalent" means the thickness of type 1100 aluminum alloy affording the same attenuation, under specified conditions, as the material in question. [The nominal chemical composition of type 1100 aluminum is ninety-nine percent (99.00%) minimum aluminum, twelve one hundredths of one percent (0.12%) copper.]8. "Articulated joint" means a joint between two (2) separate sections of a tabletop which joint provides the capacity of one (1) of the sections to pivot on the line segment along which the sections join.9. "Attenuation block" means a block or stack of type 1100 aluminum alloy, or aluminum alloy having equivalent attenuation, with dimensions twenty centimeters (20 cm) or larger by twenty centimeters (20 cm) or larger by three and eight tenths centimeters (3.8 cm), that is large enough to intercept the entire X-ray beam. 10. "Automatic exposure control" or "AEC)" means a device which automatically controls one (1) or more technique factors in order to obtain at a preselected location(s) a required quantity of radiation.11. "Automatic exposure rate control" or "AERC)" means a device which automatically controls one (1) or more technique factors in order to obtain, at a preselected location(s), a required quantity of radiation per unit time.12. "Barrier" (See "Primary protective barrier").13. "Beam axis" means a line from the source through the centers of the X-ray fields.14. "Beam-limiting device" means a device which provides a means to restrict the dimensions of the X-ray field.15. "Bone densitometry" means a noninvasive measurement of certain physical characteristics of bone that reflect bone strength. Test results are typically reported as bone mineral content or density and are used for diagnosing osteoporosis, estimating fracture risk, and monitoring changes in bone mineral content.16. "Bone densitometer" means a device intended for medical purposes to measure bone density and mineral content by X-ray or gamma ray transmission measurements through the bone and adjacent tissues. This generic type of device may include signal analysis and display equipment, patient and equipment supports, component parts, and accessories.17. "C-arm fluoroscope" means a fluoroscopic X-ray system in which the image receptor and the X-ray tube housing assembly are connected or coordinated to maintain a spatial relationship. Such a system allows a change in the direction of the beam axis with respect to the patient without moving the patient.18. "Cantilevered tabletop" means a tabletop designed such that the unsupported portion can be extended at least one hundred centimeters (100 cm) beyond the support.19. "Cassette holder" means a device, other than a spot-film device, that supports and/or fixes the position of the image receptor during a radiographic exposure.20. "Coefficient of variation (C)" means the ratio of the standard deviation to the mean value of a population of observations. It is estimated using the following equation: Image Not Available
21. "Computed radiography" or "CR" (also see "DR") means a digital X-ray imaging method in which a photo-stimulable phosphor is used to capture and store a latent image. The latent image is read out by stimulating the phosphor with a laser. Computed radiography systems may use cassettes to house the phosphor, or it may be integrated into a digital radiography system.22. "Computed tomography" or "CT" means the production of a tomogram by the acquisition and computer processing of X-ray transmission data.23. "Computed tomography dose index" or "CTDI" means the average absorbed dose, along the z-axis, from a series of contiguous irradiations. It is measured from one (1) axial CT scan (one (1) rotation of the X-ray tube) and is calculated by dividing the integrated absorbed dose by the nominal total beam collimation. The scattering media for CTDI consist of two (2) (sixteen (16) and thirty-two (32) centimeters in diameter) polymethylmethacrylate (PMMA, e.g., acrylic or Lucite) cylinders of fourteen centimeters (14 cm) length. The equation is: Image Not Available
where: D(z) = the radiation dose profile along the z-axis,
N = the number of tomographic sections imaged in a single axial scan. This is equal to the number of data channels used in a particular scan. The value of N may be less than or equal to the maximum number of data channels available on the system, and
T = the width of the tomographic section along the z-axis imaged by one (1) data channel. In multiple-detector-row (multislice) CT scanners, several detector elements may be grouped together to form one (1) data channel. In single-detector-row (single-slice) CT, the z-axis collimation (T) is the nominal scan width.
24. "CTDI100" means the accumulated multiple scan dose at the center of a one hundred millimeter (100 mm) scan and underestimates the accumulated dose for longer scan lengths. It is thus smaller than the equilibrium dose. The CTDI100, requires integration of the radiation dose profile from a single axial scan over specific integration limits. In the case of CTDI100, the integration limits are + fifty millimeters (50 mm), which corresponds to the one hundred millimeters (100 mm) length of the commercially available "pencil" ionization chamber. CTDI100 is acquired using a one hundred millimeter (100 mm) long, three (3) cc active volume CT "pencil" ionization chamber and one (1) of the two (2) standard CTDI acrylic phantoms (sixteen (16) and thirty-two (32) centimeters diameter) and a stationary patient table. The equation is: Image Not Available
25. "Cone beam computed tomography" or "CBCT" means a volumetric imaging modality. Volumetric data are acquired using two-dimensional digital detector arrays, and a cone-shaped X-ray beam (instead of fanshaped) that rotates around the patient. Reconstruction algorithms can be used to generate images of any desired plane.26. "Control panel" means that part of the X-ray control upon which are mounted the switches, knobs, pushbuttons, keypads, touchscreens, and other hardware necessary for manually setting the technique factors.27. "Cradle" means: a. A removable device which supports and may restrain a patient above an X-ray table; orb. A device: (1) Whose patient support structure is interposed between the patient and the image receptor during normal use;(2) Which is equipped with means for patient restraint; and(3) Which is capable of rotation about its long (longitudinal) axis.28. "CT conditions of operation" means all selectable parameters governing the operation of a CT X-ray system including nominal tomographic section thickness, filtration, and the technique factors as defined in § 4.2 of this Part.29. "CT gantry" means tube housing assemblies, beam-limiting devices, detectors, and the supporting structures, frames, and covers which hold and/or enclose these components within a computed tomography system.30. "CT number" means the number used to represent the X-ray attenuation associated with each elemental area of the CT image: Image Not Available
where: k = A constant, a normal value of one thousand (1,000) when the Hounsfield scale of CT number is used;
ux = Linear attenuation coefficient of the material of interest; and
uw = Linear attenuation coefficient of water.
31. "Cumulative air kerma" means the total air kerma accrued from the beginning of an examination or procedure and includes all contributions from fluoroscopic and radiographic irradiation.32. "Detector" (See "Radiation detector").33. "Diagnostic reference level" or "DRL" means an investigational level used to identify unusually high radiation doses or dose rates for common medical X-ray imaging procedures. DRLs are suggested action levels above which a facility should review its methods and determine if acceptable image quality can be achieved at lower doses. DRLs should not be applied to an individual patient.34. "Diagnostic source assembly" means the tube housing assembly with a beam-limiting device attached.35. "Diagnostic X-ray system" means an X-ray system designed for irradiation of any part of the human [or animal] body for the purpose of diagnosis or visualization.36. "Digital radiography" or "DR" means an X-ray imaging method (or radiography) which produces a digital rather than analog image. DR includes both computed radiography and direct digital radiography.37. "Direct digital radiography" or "DDR" (also see "CR" and "DR") means an X-ray imaging method in which a digital sensor, usually incorporating a thin-film transistor, is used to capture an X-ray image. Some DDR systems use a scintillator to convert X-rays to light and a photodiode array to convert light to charge, while others use a photoconductor to convert X-rays directly to charge, which is stored on the thin-film transistor.38. "Direct scattered radiation" means that scattered radiation which has been deviated in direction only by materials irradiated by the useful beam (See "Scattered radiation").39. "Direct supervision" means a qualified licensed practitioner must exercise general supervision and be present in the facility and immediately available to furnish assistance and direction throughout the performance of the procedure. It does not mean that the licensed practitioner must be present in the room when the procedure is being performed.40. "Dose" means the absorbed dose as defined by the International Commission on Radiation Units and Measurements. The absorbed dose, D, is the quotient of de by dm, where de is the mean energy imparted to matter of mass dm; thus D=de/dm, in units of J/kg, where the special name of the unit of absorbed dose is gray (Gy).41. "Dose area product," "DAP," a/k/a "kerma-area product," or "KAP" means the product of the air kerma and the area of the irradiated field and is typically expressed in Gy-cm2, so it does not change with distance from the X-ray tube.42. "Dose length product" or "DLP" means the indicator of the integrated radiation dose from a complete CT examination. It addresses the total scan length by the formula: DLP (mGy-cm) = CTDIvol (mGy) x scan length (cm).43. "Dose profile" means the dose as a function of position along a line.44. "Effective dose" or "E" means the sum of the tissue-weighted equivalent doses for the radiosensitive tissues and organs of the body. It is given by the expression E = [SIGMA]T (wT HT), in which HT is the equivalent dose in tissue or organ T and w t is the tissue weighting factor for tissue or organ T. The unit of E and H t is joule per kilogram (J·kg-1), with the special name sievert (Sv).45. "Equipment" (See "X-ray equipment") means X-ray equipment.46. "Exposure" or "X" means the quotient of dQ by dm where dQ is the absolute value of the total charge of the ions of one sign produced in air when all the electrons and positrons liberated or created by photons in air of mass dm are completely stopped in air; thus X=dQ/dm, in units of C/kg. A second meaning of exposure is the process or condition during which the X-ray tube produces X-ray radiation.47. "Field emission equipment" means equipment which uses an X-ray tube in which electron emission from the cathode is due solely to the action of an electric field.48. "Filter" means material placed in the useful beam to preferentially absorb selected radiations.49. "Fluoroscopic imaging assembly" means a subsystem in which X-ray photons produce a set of fluoroscopic images or radiographic images recorded from the fluoroscopic image receptor. It includes the image receptor(s), electrical interlocks, if any, and structural material providing linkage between the image receptor and diagnostic source assembly.50. "Fluoroscopic irradiation time" means the cumulative duration during an examination or procedure of operator-applied continuous pressure to the device, enabling X-ray tube activation in any fluoroscopic mode of operation.51. "Fluoroscopically-guided interventional procedures" or "FGI procedures" means an interventional diagnostic or therapeutic procedure performed via percutaneous or other access routes, usually with local anesthesia or intravenous sedation, which uses external ionizing radiation in the form of fluoroscopy to localize or characterize a lesion, diagnostic site, or treatment site, to monitor the procedure, and to control and document therapy.52. "Fluoroscopy" means a technique for generating X-ray images and presenting them simultaneously and continuously as visible images. This term has the same meaning as the term "radioscopy" in the standards of the International Electrotechnical Commission.53. "Focal spot (actual)" means the area projected on the anode of the X-ray tube bombarded by the electrons accelerated from the cathode and from which the useful beam originates.54. "General purpose radiographic X-ray system" means any radiographic X-ray system which, by design, is not limited to radiographic examination of specific anatomical regions.55. "General supervision" means the procedure is performed under the overall direction and control of the qualified licensed practitioner but who is not required to be physically present during the performance of the procedure.56. "Half-value layer" or "HVL" means the thickness of specified material which attenuates the beam of radiation to an extent such that the AKR is reduced by one half (1/2) of its original value. In this definition, the contribution of all scattered radiation, other than any which might be present initially in the beam concerned, is deemed to be excluded.57. "Healing arts screening" means the testing of human beings using X-ray machines for the detection or evaluation of health indications when such tests are not specifically and individually ordered by a licensed practitioner of the healing arts legally authorized to prescribe such X-ray tests for the purpose of diagnosis or treatment.58. "Heat unit" means a unit of energy equal to the product of the peak kilovoltage, milliamperes, and seconds, i.e., kVp x mA x second.59. "Image intensifier" means a device, installed in its housing, which instantaneously converts an X-ray pattern into a corresponding light image of higher intensity.60. "Image receptor" means any device, such as a fluorescent screen, radiographic film, X-ray image intensifier tube, solid-state detector, or gaseous detector which transforms incident X-ray photons either into a visible image or into another form which can be made into a visible image by further transformations. In those cases where means are provided to preselect a portion of the image receptor, the term "image receptor" shall mean the preselected portion of the device.61. "Irradiation" means the exposure of matter to ionizing radiation.62. "Isocenter" means the center of the smallest sphere through which the beam axis passes when the equipment moves through a full range of rotations about its common center.63. "Kerma" means the quantity defined by the International Commission on Radiation Units and Measurements. The kerma, K, is the quotient of dEtr by dm, where dEtr is the sum of the initial kinetic energies of all the charged particles liberated by uncharged particles in a mass dm of material; thus K=dEtr/dm, in units of J/kg, where the special name for the unit of kerma is gray (Gy). When the material is air, the quantity is referred to as "air kerma."64. "Kerma-area product" or "KAP" (See "dose area product").65. "Kilovolts peak" (See "Peak tube potential").66. "kV" means kilovolts.67. "kWs" means kilowatt second.68. "Last-image hold radiograph" or "LIH radiograph" means an image obtained either by retaining one (1) or more fluoroscopic images, which may be temporarily integrated, at the end of a fluoroscopic exposure or by initiating a separate and distinct radiographic exposure automatically and immediately in conjunction with termination of the fluoroscopic exposure.69. "Lead equivalent" means the thickness of lead affording the same attenuation, under specified conditions, as the material in question.70. "Leakage radiation" means radiation emanating from the diagnostic source assembly except for: b. Radiation produced when the exposure switch or timer is not activated.71. "Leakage technique factors" means the technique factors associated with the diagnostic source assembly which are used in measuring leakage radiation. They are defined as follows: a. For diagnostic source assemblies intended for capacitor energy storage equipment, the maximum-rated peak tube potential and the maximum-rated number of exposures in an hour for operation at the maximum-rated peak tube potential with the quantity of charge per exposure being ten (10) millicoulombs (or ten (10) mAs) or the minimum obtainable from the unit, whichever is larger;b. For diagnostic source assemblies intended for field emission equipment rated for pulsed operation, the maximum-rated peak tube potential and the maximum-rated number of X-ray pulses in an hour for operation at the maximum-rated peak tube potential; andc. For all other diagnostic source assemblies, the maximum-rated peak tube potential and the maximum-rated continuous tube current for the maximum-rated peak tube potential.72. "Light field" means that area of the intersection of the light beam from the beam-limiting device and one (1) of the set of planes parallel to and including the plane of the image receptor, whose perimeter is the locus of points at which the illumination is one fourth (1/4) of the maximum in the intersection.73. "Line-voltage regulation" means the difference between the no-load and the load line potentials expressed as a percent of the load line potential; that is, Percent line-voltage regulation = 100 (Vn-Vl)/Vl, where: Vn = Noload line potential; and Vl = Load line potential.74. "mA" means milliampere.75. "mAs" means milliampere second.76. "Mode of operation" means, for fluoroscopic systems, a distinct method of fluoroscopy or radiography provided by the manufacturer and selected with a set of several technique factors or other control settings uniquely associated with the mode. The set of distinct technique factors and control settings for the mode may be selected by the operation of a single control. Examples of distinct modes of operation include normal fluoroscopy (analog or digital), high-level control fluoroscopy, cineradiography (analog and digital), digital subtraction angiography, electronic radiography using the fluoroscopic image receptor, and photospot recording. In a specific mode of operation, certain system variables affecting kerma, AKR, or image quality, such as image magnification, X-ray field size, pulse rate, pulse duration, number of pulses, source-image receptor distance (SID), or optical aperture, may be adjustable or may vary; their variation per se does not comprise a mode of operation different from the one that has been selected.77. "Multiple tomogram system" means a computed tomography X-ray system which obtains X-ray transmission data simultaneously during a single scan to produce more than one tomogram.78. "Noise" means the standard deviation of the fluctuations in CTN expressed as a percentage of the attenuation coefficient of water. Its estimate (Sn) is calculated using the following expression: Image Not Available
where µx = Linear attenuation coefficient of the material of interest, µw = Linear attenuation coefficient of water, and s = Estimated standard deviation of the CTN of picture elements in a specified area of the CT image.
79. "Nominal tomographic section thickness" means the full width at halfmaximum of the sensitivity profile taken at the center of the crosssectional volume over which X-ray transmission data are collected.80. "Notification value" means a protocol-specific dose index (e.g., CTDIvol(mGy) or of DLP(mGy-cm)) that is set by the registrant to trigger a notification to the CT operator prior to scanning when the dose index exceeds the established range for the examination.81. "Patient" means an individual or animal subjected to healing arts examination, diagnosis or treatment.82. "Picture element" means an elemental area of a tomogram.83. "PBL" (See "Positive beam limitation").84. "Peak tube potential" means the maximum value of the potential difference across the X-ray tube during an exposure.85. "Personal supervision" means a qualified practitioner must exercise General Supervision and be present in the room or adjacent control area during the performance of the procedure.86. "Phantom" means a volume of material behaving in a manner similar to tissue with respect to the attenuation and scattering of radiation. This requires that both the atomic number (Z) and the density of the material be similar to that of tissue.87. "Photostimulable storage phosphor" or "PSP" means a material used to capture and store radiographic images in computed radiography systems.88. "Pitch" means the table incrementation, in CT, per X-ray tube rotation, divided by the nominal X-ray beam width at isocenter.89. "Position indicating device" or "PID" means a device on dental X-ray equipment used to indicate the beam position and to establish a definite source-surface (skin) distance. It may or may not incorporate or serve as a beam-limiting device.90. "Positive beam limitation" means the automatic or semi-automatic adjustment of an X-ray beam to the size of the selected image receptor, whereby exposures cannot be made without such adjustment.91. "Primary protective barrier" means the material, excluding filters, placed in the useful beam to reduce the radiation exposure (beyond the patient and cassette holder) for protection purposes.92. "Protective garment" means a garment made of radiation absorbing materials used to reduce radiation exposure.93. "Protocol" means a collection of settings and parameters that fully describe an examination.94. "Pulsed mode" means operation of the X-ray system such that the X-ray tube current is pulsed by the X-ray control to produce one or more exposure intervals of duration less than one half (1/2) second.95. "Quality assurance" means a program providing for verification by written procedures such as testing, auditing, and inspection to ensure that deficiencies, deviations, defective equipment, or unsafe practices, or a combination thereof, relating to the use, disposal, management, or manufacture of radiation devices are identified, promptly corrected, and reported to the appropriate regulatory authorities as required.96. "Qualified medical physicist" or "QMP" (for activities authorized pursuant to this Part) means an individual registered to provide Radiation Physics Services (Diagnostic X-ray Physics Services) in accordance with § 3.6 of this Subchapter.97. "Radiation detector" means a device which in the presence of radiation provides a signal or other indication suitable for use in measuring one (1) or more quantities of incident radiation.98. "Radiation medical event" means an event that meets the criteria in §4.4.14(A) of this Part.99. "Radiation protocol committee" or "RPC" means the representative group of qualified individuals in a CT or FGI facility responsible for the ongoing review and management of CT or FGI protocols to ensure that exams being performed achieve the desired diagnostic image quality at the lowest radiation dose possible while properly exploiting the capabilities of the equipment being used.100. "Radiation therapy simulation system" means a radiographic or fluoroscopic X-ray system intended for localizing the volume to be exposed during radiation therapy and confirming the position and size of the therapeutic irradiation field.101. "Radiograph" means an image receptor on which the image is created directly or indirectly by an X-ray pattern and results in a permanent record.102. "Radiography" means a technique for generating and recording an X-ray pattern for the purpose of providing the user with an image(s) after termination of the exposure.103. "Recording" means producing a retrievable form of an image resulting from X-ray photons.104. "Reference plane" means a plane which is parallel to and which can be offset (as specified in manufacturer information provided to users) from the location of the tomographic plane(s).105. "Registrant" means any person who is registered with the Agency and is legally obligated to register with the Agency pursuant to this Subchapter and the Act.106. "Registration" means registration with the Agency pursuant to this Subchapter and the Act. 107. "Scan" means the complete process of collecting X-ray transmission data for the production of a tomogram. Data may be collected simultaneously during a single scan for the production of one (1) or more tomograms.108. "Scan increment" means the amount of relative displacement of the patient with respect to the CT X-ray system between successive scans measured along the direction of such displacement.109. "Scan sequence" means a pre-selected set of two (2) or more scans performed consecutively under pre-selected CT conditions of operation.110. "Scan time" means the time elapsed during the accumulation of X-ray transmission data for a single scan.111. "Scattered radiation" means radiation that, during passage through matter, has been deviated in direction (See "Direct scattered radiation").112. "Sensitivity profile" means the relative response of the CT X-ray system as a function of position along a line perpendicular to the tomographic plane.113. "Single tomogram system" means a CT X-ray system which obtains X-ray transmission data during a scan to produce a single tomogram.114. "Shutter" means a device attached to the tube housing assembly which can intercept the entire cross-sectional area of the useful beam and which has a lead equivalency not less than that of the tube housing assembly.115. "Size-specific dose estimate" or "SSDE" means a patient dose estimate which takes into consideration corrections based on the size of the patient, using linear dimensions measured on the patient or patient images.116. "Source" means the focal spot of the X-ray tube.117. "Source-image receptor distance" or "SID" means the distance from the source to the center of the input surface of the image receptor.118. "Source-skin distance" or "SSD" means the distance from the source to the center of the entrant X-ray field in the plane tangent to the patient skin surface.119. "Spot-film" means a radiograph which is made during a fluoroscopic examination to permanently record conditions which exist during that fluoroscopic procedure. Digital image receptors used in place of film with spot-film devices should be considered "spot-film."120. "Spot-film device" means a device intended to transport and/or position a radiographic image receptor between the X-ray source and fluoroscopic image receptor. It includes a device intended to hold a cassette over the input end of the fluoroscopic image receptor for the purpose of producing a radiograph.121. "Stray radiation" means the sum of leakage and scattered radiation.122. "Substantial radiation dose level" or "SRDL" means an appropriately-selected dose used to trigger additional dose-management actions during a procedure and medical follow-up for a radiation level that might produce a clinically-relevant injury in an average patient. 123. "Technique factors" means the following conditions of operation: a. For capacitor energy storage equipment, peak tube potential in kilovolts (kV) and quantity of charge in milliampere-seconds (mAs);b. For field emission equipment rated for pulsed operation, peak tube potential in kV, and number of X-ray pulses;c. For CT X-ray systems designed for pulsed operation, peak tube potential in kV, scan time in seconds, and either tube current in mA, X-ray pulse width in seconds, and the number of X-ray pulses per scan, or the product of tube current, X-ray pulse width, and the number of X-ray pulses in mAs;d. For CT X-ray systems not designed for pulsed operation, peak tube potential in kV, and either tube current in mA and scan time in seconds, or the product of tube current and exposure time in mAs and the scan time when the scan time and exposure time are equivalent; ande. For all other equipment, peak tube potential in kV, and either tube current in mA and exposure time in seconds, or the product of tube current and exposure time in mAs.124. "Tomogram" means the depiction of the X-ray attenuation properties of a section through the body.125. "Tomographic plane" means that geometric plane which the manufacturer identified as corresponding to the output tomogram.126. "Tomographic section" means the volume of an object whose X-ray attenuation properties are imaged in a tomogram.127. "Tube" means an X-ray tube, unless otherwise specified.128. "Tube housing assembly" means the tube housing with tube installed. It includes high-voltage and/or filament transformers and other appropriate elements when such are contained within the tube housing.129. "Unintended" (radiation dose in diagnostic or interventional X-ray) means a patient radiation dose resulting from a human error or equipment malfunction during the procedure.130. "Useful beam" means the radiation which passes through the tube housing port and the aperture of the beam limiting device when the exposure switch or timer is activated.131. "Visible area" means that portion of the input surface of the image receptor over which incident X-ray photons are producing a visible image.132. "Volume computed tomography dose index" or "CTDIvol" means a radiation dose parameter derived from the CTDIw (weighted or average CTDI given across the field of view). The formula is: CTDIvol = (N)(T)(CTDIw)/I, where N = number of simultaneous axial scans per X-ray source rotation, T = thickness of one axial scan (mm), and I = table increment per axial scan (mm). Thus, CTDIvol = CTDIw/pitch.133. "Weighted computed tomography dose index" or "CTDIwa" means the estimated average CTDI100 across the field of view (FOV). The equation is: CTDIw = 1/3 CTDI100,center + 2/3 CTDI100,edge Where one third (1/3) and two thirds (2/3) approximate the relative areas represented by the center and edge values derived using the sixteen (16) or thirty-two (32) centimeters acrylic phantom. CTDIw uses CTDI100 and an f-factor for air (0.87 rad/R or 1.0 mGy/mGy).134. "X-ray control" means a device which controls input power to the X-ray high-voltage generator and/or the X-ray tube. It includes equipment such as timers, phototimers, automatic brightness stabilizers, and similar devices, which control the technique factors of an X-ray exposure.135. "X-ray exposure control" means a device, switch, button or other similar means by which an operator initiates and/or terminates the radiation exposure. The X-ray exposure control may include such associated equipment as timers and back-up timers.136. "X-ray equipment" means an X-ray system, subsystem, or component thereof. Types of X-ray equipment are as follows: a. "Mobile X-ray equipment" means X-ray equipment mounted on a permanent base with wheels and/or casters for moving while completely assembled;b. "Portable X-ray equipment" means X-ray equipment designed to be hand-carried; andc. "Stationary X-ray equipment" means X-ray equipment which is installed in a fixed location.d. "Hand-held X-ray equipment" means X-ray equipment that is designed to be hand-held during operation.137. "X-ray field" means that area of the intersection of the useful beam and any one of a set of planes parallel to and including the plane of the image receptor, whose perimeter is the locus of points at which the AKR is one fourth (1/4) of the maximum in the intersection.138. "X-ray high-voltage generator" means a device which transforms electrical energy from the potential supplied by the X-ray control to the tube operating potential. The device may also include means for transforming alternating current to direct current, filament transformers for the X-ray tube(s), high-voltage switches, electrical protective devices, and other appropriate elements.139. "X-ray system" means an assemblage of components for the controlled production of X-rays. It includes minimally an X-ray high-voltage generator, an X-ray control, a tube housing assembly, a beam-limiting device, and the necessary supporting structures. Additional components which function with the system are considered integral parts of the system.140. "X-ray table" means a patient support device with its patient support structure (tabletop) interposed between the patient and the image receptor during radiography and/or fluoroscopy. This includes, but is not limited to, any stretcher equipped with a radiolucent panel and any table equipped with a cassette tray (or bucky), cassette tunnel, fluoroscopic image receptor, or spot-film device beneath the tabletop.141. "X-ray tube" means any electron tube which is designed for the conversion of electrical energy into X-ray energy.216 R.I. Code R. § 216-RICR-40-20-4.2
Adopted effective 1/1/2019
Amended effective 5/25/2022
Amended effective 11/28/2023