Louisiana Administrative Code › Title 33 - ENVIRONMENTAL QUALITY › Part XV - Radiation Protection › Chapter 6 - X-Rays in the Healing Arts › Section XV-602 - Definitions

Current through Register Vol. 50, No. 6, June 20, 2024
A. As used in this
				Chapter, the following definitions apply. Other definitions applicable to this
				Chapter may be found in LAC 33:XV. Chapters 1 and 2.
Accessible Surface
- the external surface of
				  the enclosure or housing provided by the manufacturer.
Added Filtration
- any filtration that is in
				  addition to the inherent filtration.
Air Kerma (K)
-the kinetic energy released in
				  air by ionizing radiation. Kerma is determined as the quotient of dE by dM,
				  where dE is the sum of the initial kinetic energies of all the charged ionizing
				  particles liberated by uncharged ionizing particles in air of mass dM. The SI
				  unit of air kerma is joule per kilogram and the special name for the unit of
				  kerma is the gray (Gy).
Air Kerma Rate (AKR)
-air kerma per unit
				  time.
Alert Value
-a dose rate 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.
Aluminum Equivalent
-the thickness of type
				  1100 aluminum alloy affording the same attenuation, under specified conditions,
				  as the material in question.
Articulated Joint
-a joint between two
				  separate sections of a tabletop which joint provides the capacity of one of the
				  sections to pivot on the line segment along which the sections join.
Assembler
- any person engaged in the
				  business of assembling, replacing, or installing one or more components into an
				  X-ray system or subsystem. The term includes the owner of an X-ray system or
				  his or her employee or agent who assembles components into an X-ray system that
				  is subsequently used to provide professional or commercial services.
Attenuation Block
- a block or stack, having
				  dimensions 20 centimeters by 20 centimeters by 3.8 centimeters, of type 1100
				  aluminum alloy or other materials having equivalent attenuation.
Automatic Exposure Control
- a device that
				  automatically controls one or more technique factors in order to obtain at a
				  preselected location or locations a required quantity of radiation (see also
Phototimer
).
Attenuation Block
-a block or stack of type
				  1100 aluminum alloy, or aluminum alloy having equivalent attenuation, with
				  dimensions 20 centimeters or larger by 20 centimeters or larger by 3.8
				  centimeters, that is large enough to intercept the entire X-ray beam.
Automatic Exposure Control (AEC)
-a device
				  which automatically controls one or more technique factors in order to obtain
				  at a preselected location(s) a required quantity of radiation (see also
Phototimer
).
Automatic Exposure Rate Control (AERC)
-a
				  device which automatically controls one or more technique factors in order to
				  obtain, at a preselected location(s), a required quantity of radiation per unit
				  time.
Barrier
-(See
Protective
				  Barrier
)
Beam Axis
- a line from the source through
				  the centers of the X-ray fields.
Beam-Limiting Device
- a device that
				  provides a means to restrict the dimensions of the X-ray field.
Beam Monitoring System
- a system designed
				  to detect and measure the radiation present in the useful beam.
Bone Densitometer
-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.
Bone Densitometry
-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.
C Arm X-Ray System
- an X-ray system in
				  which the image receptor and X-ray tube housing assembly are connected by a
				  common mechanical support system in order to maintain a desired spatial
				  relationship. This system is designed to allow a change in the projection of
				  the beam through the patient without a change in the position of the
				  patient.
Cantilevered Tabletop
-a tabletop designed
				  such that the unsupported portion can be extended at least 100 cm beyond the
				  support.
Cassette Holder
-a device, other than a
				  spot-film device, that supports and/or fixes the position of the image receptor
				  during a radiographic exposure.
Cephalometric Device
- a device intended for
				  the radiographic visualization and measurement of the dimensions of the human
				  head.
Certified Components
-components of X-ray
				  systems that are certified by the U.S. Food and Drug Administration
				  (FDA).
Changeable Filters
- any filter, exclusive
				  of inherent filtration, that can be removed from the useful beam through any
				  electronic, mechanical, or physical process.
Coefficient of Variation
or
				  "
C
"-Repealed.
Coefficient of Variation (C)
-the ratio of
				  the standard deviation to the mean value of a population of observations. It is
				  estimated using the following equation:
where:
Click
				  here to view Image
s = estimated standard deviation of the population;
x = mean value of observations in sample;
xi = ith
				  observation in sample; and
n = number of observations sampled.
Computed Radiography (CR; also see DR)
-a
				  digital X-ray imaging method in which a photostimulable 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.
Computed Tomography
(
CT
)-the production of a tomogram by the acquisition and
				  computer processing of X-ray transmission data.
Computed Tomography Dose Index (CTDI)
-the
				  average absorbed dose, along the z-axis, from a series of contiguous
				  irradiations. It is measured from one axial CT scan (one 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
				  (16 and 32 cm in diameter) polymethylmethacrylate (PMMA, e.g., acrylic or
				  Lucite) cylinders. The equation is:
Click
				  here to view Image
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 data channel. In multiple-detector-row (multislice) CT scanners,
				  several detector elements may be grouped together to form one data channel. In
				  single-detectorrow (single-slice) CT, the z-axis collimation (T) is the nominal
				  scan width.
CTDI100
-the
				  accumulated multiple scan dose at the center of a 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 +50 mm, which corresponds to the
				  100-mm length of the commercially available "pencil" ionization chamber.
				  CTDI100 is acquired using a 100-mm long, 3-cc active volume CT "pencil"
				  ionization chamber and one of the two standard CTDI acrylic phantoms (16 and 32
				  cm diameter) and a stationary patient table. The equation is:
Click
				  here to view Image
CTDI
vol-see volume
				  Computed Tomography Dose Index (CTDIvol)/
CTDI
w-see Weighted
				  Computed Tomography Dose Index (CTDIw).
Cone Beam Computed Tomography (CBCT)
-a
				  volumetric imaging modality. volumetric data are acquired using two dimensional
				  digital detector arrays, and a coneshaped (instead of fan-shaped) X-ray beam
				  that rotates around the patient. Reconstruction algorithms can be used to
				  generate images of any desired plane.
Contact Therapy System
- an X-ray system
				  used for therapy with the X-ray tube port placed in contact with or within 5
				  centimeters of the surface being treated.
Click
				  here to view Image
where:
[MICRO] x = linear attenuation
				  coefficient of the material of interest;
[MICRO] w = linear attenuation
				  coefficient of water;
(CTN)
x
= CTN of the
				  material of interest; and
(CTN)
w
= CTN of
				  water.
Control Panel
-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.
Cooling Curve
- the graphical relationship
				  between heat units stored and cooling time.
Cradle
-a removable device which supports and
				  may restrain a patient above an X-ray table; or a device:
a. where patient support structure is
				interposed between the patient and the image receptor during normal
				use;
b. which is equipped with
				means for patient restraint; and
c.
				which is capable of rotation about its long (longitudinal) axis.
CS
-see
Contrast
				  Scale
.
CT
-see Computed Tomography.
CT Conditions of Operation
-all selectable
				  parameters governing the operation of a CT X-ray system including, but not
				  limited to, nominal tomographic section thickness, filtration, and the
				  technique factors as defined in LAC 33:XV.602.
CT Gantry
-the tube housing assemblies,
				  beam-limiting devices, detectors, and the supporting structures and frames that
				  hold these components.
CTN
-see
CT Number
.
CT Number
-the number used to represent the
				  X-ray attenuation associated with each elemental area of the CT image. The
				  equation is:
Click
				  here to view Image
where:
k = a constant. The constant has a normal value of 1,000 when
				  the Hounsfield unit of CTN is used;
[MICRO] x = linear attenuation
				  coefficient of the material of interest; and
[MICRO] w = linear attenuation
				  coefficient of water.
Cumulative Air Kerma
-the total air kerma
				  accrued from the beginning of an examination or procedure and includes all
				  contributions from fluoroscopic and radiographic irradiation.
Dead-Man Switch
- a switch so constructed
				  that a circuit closing contact can be maintained only by continuous pressure on
				  the switch by the operator.
Detector
-(See
Radiation
				  Detector
)
Diagnostic Reference Level (DRL)
-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.
Diagnostic Source Assembly
- the tube
				  housing assembly with a beam-limiting device attached.
Diagnostic-Type Tube Housing
- a tube
				  housing so constructed that the leakage radiation measured at a distance of 1
				  meter from the source does not exceed 100 mR in one hour when the tube is
				  operated at its leakage technique factors.
Diagnostic X-Ray Imaging System
- an
				  assemblage of components for the generation, emission, and reception of X-rays
				  and the transformation, storage, and visual display of the resultant X-ray
				  image.
Diagnostic X-Ray System
- an X-ray system
				  designed for irradiation of any part of the human or animal body for the
				  purpose of diagnosis or visualization.
Digital Radiography (DR)
-an X-ray imaging
				  method (or radiography) which produces a digital rather than analog image. DR
				  includes both computed radiography and direct digital radiography.
Direct Digital Radiography (DDR
; also see
CR
and
DR)
-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.
Direct Scattered Radiation
-that scattered
				  radiation which has been deviated in direction only by materials irradiated by
				  the useful beam. (See
Scattered Radiation
)
Direct Supervision
-general supervision by a
				  qualified practitioner 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 shall be present in the room
				  when the procedure is being performed.
Dose
-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).
Dose Area Product (DAP)
(aka
Kerma-Area Product (KAP)
)-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.
Dose Length Product (DLP)
-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)
Dose Profile
-the dose as a function of
				  position along a line.
Effective Dose (E)
-the sum of the
				  tissue-weighted equivalent doses for the radiosensitive tissues and organs of
				  the body. It is given by the expression E = ÎT (wT HT), in which HT is
				  the equivalent dose in tissue or organ T and wT is the tissue weighting factor
				  for tissue or organ T. The unit of E and HT is joule per kilogram (J/kg), with
				  the special name sievert (Sv).
Elemental Area
-the smallest area within a
				  tomogram for which the X-ray attenuation properties of a body are depicted.
				  (See also
Picture Element
)
Entrance Exposure Rate
- the exposure free
				  in air per unit time at the point where the center of the useful beam enters
				  the patient.
Equipment
-(See
X-Ray
				  Equipment
)
Exposure (X)
-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.
				  Exposure is also the process or condition during which the X-ray tube produces
				  X-ray radiation.
Field Emission Equipment
- equipment that
				  uses an X-ray tube in which electron emission from the cathode is due solely to
				  the action of an electric field.
Filter
- material placed in the useful beam
				  to absorb preferentially selected radiations.
Fluoroscopic Imaging Assembly
-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.
Fluoroscopic Irradiation Time
-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.
Fluoroscopically-Guided Interventional (FGI)
				  Procedures
-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.
Fluoroscopy
-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.
Focal Spot
(actual)-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.
General Purpose Radiographic X-Ray System
-
				  any radiographic X-ray system that, by design, is not limited to radiographic
				  examination of specific anatomical regions.
General Supervision
-supervision of a
				  procedure under the overall direction and control of the qualified practitioner
				  but who is not required to be physically present during the performance of the
				  procedure.
Gonad Shield
-Repealed.
Half-Value Layer
-the thickness of specified
				  material that attenuates the beam of radiation to an extent that the exposure
				  rate is reduced by one half. In this definition, the contribution of all
				  scattered radiation, other than any that might be present initially in the beam
				  concerned, is deemed to be excluded.
Hand-Held X-Ray Equipment
-X-ray equipment
				  that is designed to be hand-held during operation.
Healing Arts Screening
- 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.
Heat Unit
-a unit of energy equal to the
				  product of the peak kilovoltage, milliamperes, and seconds, i.e., kVp x mA x
				  second.
HVL
-(See
Half-Value
				  Layer
)
Image Intensifier
-a device, installed in its
				  housing, that instantaneously converts an X-ray pattern into a corresponding
				  light image of higher intensity.
Image Receptor
-any device, such as a
				  fluorescent screen, radiographic film, X-ray image intensifier tube,
				  solid-state detector, or gaseous detector, that transforms incident X-ray
				  photons either into a visible image or into another form that 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.
Image Receptor Support
- for mammographic
				  systems, that part of the system designed to support the image receptor during
				  mammography.
Inherent Filtration
- the filtration of the
				  useful beam provided by the permanently installed components of the tube
				  housing assembly.
Irradiation
- the exposure of matter to
				  ionizing radiation.
Isocenter
-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.
Kerma
-a measurement 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."
Kerma-Area Product
(KAP)-see
Dose
				  Area Product
.
Kilovolts Peak
-(See
Peak
Tube Potential
)
kVp
-see
Peak Tube
				  Potential
.
Kw*s
- kilowatt second.
Last-Image Hold (LIH) Radiograph
-an image
				  obtained either by retaining one 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.
Lead Equivalent
-the thickness of the
				  material in question affording the same attenuation, under specified
				  conditions, as lead.
Leakage Radiation
- radiation emanating from
				  the diagnostic or therapeutic source assembly except for:
1. the useful beam; and
2. radiation produced when the exposure
				switch or timer is not activated.
Leakage Technique Factors
- the technique
				  factors associated with the diagnostic or therapeutic source assembly that are
				  used in measuring leakage radiation. They are defined as follows:
1. 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 10 millicoulombs, i.e., 10 milliampere seconds, or the minimum obtainable
				from the unit, whichever is larger;
2. 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; and
3. for all other diagnostic or therapeutic
				source assemblies, the maximum rated peak tube potential and the maximum rated
				continuous tube current for the maximum rated peak tube potential.
Licensed Practitioner
-a person licensed or
				  otherwise authorized by law to practice medicine, dentistry, chiropractic,
				  osteopathy or podiatry, or a licensed nurse practitioner, or physician
				  assistant.
Light Field
- that area of the intersection
				  of the light beam from the beam-limiting device and one of the sets of planes
				  parallel to and including the plane of the image receptor, whose perimeter is
				  the locus of points at which the illumination is 1/4 of the maximum in the
				  intersection.
Line-voltage Regulation
- the difference
				  between the no-load and the load line potentials expressed as a percentage of
				  the load line potential. It is calculated using the following equation.
Click Here To View
				  Image
where:
Vn = no-load line potential;
				  and
V1 = load line potential.
mA
-milliampere.
mAs
-milliampere second.
Mammography Physicist
- an individual who
				  has submitted credentials to the department and who satisfies one or more of
				  the following criteria:
1.
				is certified in radiological physics by the American Board of Radiology or the
				American Board of Medical Physics and who continues to meet the Mammography
				Quality Standards Act (MQSA) requirement of 15 hours of continuing mammography
				education every three years;
2. has
				a master's or doctoral degree from an accredited college or university in
				physics, engineering, chemistry, or environmental science, has at least one
				year of radiation survey experience that includes performing instrument surveys
				on at least 20 mammography units, and continues to meet the MQSA requirement of
				15 hours of continuing mammography education every three years;
3. has a bachelor's degree from an accredited
				college or university in physics, engineering, chemistry, environmental
				science, or any biological science that included at least 10 semester hours of
				college-level physics, has had at least five years of experience with making
				radiation measurements that includes performing instrument surveys on at least
				20 mammography units, and continues to meet the MQSA requirement of 15 hours of
				continuing mammography education every three years; and
4. has been approved by the department.
Maximum Line Current
- the root-mean-square
				  current in the supply line of an X-ray machine operating at its maximum
				  rating.
Medical Event
-one or more of the criteria
				  that are listed in LAC 33:XV.613 have occurred.
Mobile X-Ray Equipment
-(See
X-Ray
				  Equipment
)
Mode of Operation
-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. 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.
Multiple Tomogram System
-a computed
				  tomography X-ray system that obtains X-ray transmission data simultaneously
				  during a single scan to produce more than one tomogram.
Noise
-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:
Click
				  here to view Image
where:
CS = contrast scale;
[MICRO] w = linear attenuation coefficient of water;
				  and
s = estimated standard deviation of the CTN of picture
				  elements in a specified area of the CT image.
Nominal Tomographic Section Thickness
-the
				  full width at half-maximum of the sensitivity profile taken at the center of
				  the cross-sectional volume over which X-ray transmission data are
				  collected.
Operator
- an individual who, under the
				  supervision of a practitioner of the healing arts, physically positions
				  patients or animals, determines exposure parameters, and applies the radiation
				  for the diagnostic or therapeutic purposes intended. See the definition of
				  supervision in LAC 33:XV.110.E.
Patient
- an individual or animal subjected
				  to healing arts examination, diagnosis, or treatment.
PBL
-see
Positive Beam
				  Limitation
.
Peak Tube Potential
(kVp)-the maximum value
				  of the potential difference across the X-ray tube during an exposure.
Personal Supervision
-general supervision by
				  a qualified practitioner present in the room or adjacent control area during
				  the performance of the procedure.
Phantom
- 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.
Photostimulable Storage Phosphor (PSP)
-a
				  material used to capture and store radiographic images in computed radiography
				  systems.
Phototimer
- a method for controlling
				  radiation exposures to image receptors by measuring the amount of radiation
				  that reaches a radiation monitoring device or devices. The radiation monitoring
				  device or devices are part of an electronic circuit that controls the duration
				  of time the tube is activated (see
Automatic Exposure
				  Control
).
PID
-see
Position Indicating
				  Device
.
Picture Element
-an elemental area of a
				  tomogram.
Pitch
-the table incrementation, in CT, per
				  X-ray tube rotation, divided by the nominal X-ray beam width at
				  isocenter.
Portable X-Ray Equipment
-(See
X-Ray
				  Equipment
)
Position Indicating Device
(PID)-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.
Positive Beam Limitation
(PBL)-the
				  automatic or semiautomatic adjustment of an X-ray beam to the selected image
				  receptor size, whereby exposures cannot be made without such adjustment.
Protected Area
-an area shielded with primary
				  or secondary protective barriers or an area removed from the radiation source
				  such that the exposure rate within the area due to normal operating procedures
				  and workload does not exceed any of the following
				  limits:
a. 2
				milliroentgens (20 micro Gray) in any one hour;
b. 100 milliroentgens (1 milli Gray) in any
				seven consecutive days; or
c. 500
				milliroentgens (5 milli Gray) in any one year.
Protective Apron
-an apron made of radiation
				  absorbing or lead equivalent materials used to reduce radiation
				  exposure.
Protective Barrier
(
Primary
				  Protective Barrier
)-a barrier of radiation absorbing material(s) used
				  to reduce radiation exposure. The types of protective barriers are as
				  follows:
1.
Primary Protective
				Barrier
- the material, excluding filters, placed in the useful beam,
				to protect anyone other than the patient from radiation exposure.
2.
Secondary Protective
				Barrier
- a barrier sufficient to absorb the stray radiation to the
				required degree.
Protocol
-a collection of settings and
				  parameters that fully describe an examination.
Protective Glove
- a glove made of radiation
				  absorbing materials used to reduce radiation exposure.
Pulsed Mode
-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 second.
Qualified Expert
-an individual who meets one
				  of the following criteria:
a. a qualified medical physicist;
b. not board certified in the required
				subspecialty but with a graduate degree in medical physics, radiologic physics,
				physics, or other relevant physical science or engineering discipline from an
				accredited institution, and formal coursework in the biological sciences with
				at least one course in biology or radiation biology and one course in anatomy,
				physiology, or similar topics related to the practice of medical physics and
				three years of documented experience in a clinical CT environment (for purposes
				of CT evaluations), three years of documented experience in fluoroscopic
				environment (for purposes of fluoroscopic evaluations), or three years of
				documented experience in general radiographic environment (for purposes of
				general radiographic evaluations);
c. grandfathered by having conducted surveys
				of at least three CT units between January 1, 2007, and January 1, 2010;
				or
d. an individual approved by the
				department.
Qualified Medical Physicist (QMP)
-an
				  individual who meets each of the following credentials:
a. has earned a master's and/or doctoral
				degree in physics, medical physics, biophysics, radiological physics, medical
				health physics, or equivalent disciplines from an accredited college or
				university; and
b. has been granted
				certification in the specific subfield(s) of medical physics with its
				associated medical health physics aspects by an appropriate national certifying
				body and abides by the certifying body's requirements for continuing education.
Qualified Practitioner
-an individual who is
				  qualified by education, training, licensure/regulation (when applicable), and
				  facility privileging (when applicable) who performs a professional service
				  within his/her scope of practice and independently reports that professional
				  service.
Quality Assurance (QA)
-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.
Quality Control (QC)
-the routine measurement
				  of image quality and the performance of the diagnostic X-ray imaging system,
				  from X-ray beam output to the viewing of radiographs, and the continual
				  adjustment of that performance to an optimal and consistent level.
Qualified Expert
- an individual who has
				  demonstrated to the satisfaction of the department that such individual
				  possesses the knowledge, training, and experience to measure ionizing
				  radiation, to evaluate safety techniques, and to advise regarding radiation
				  protection needs.
Radiation Detector
- a device that in the
				  presence of radiation provides a signal or other indication suitable for use in
				  measuring one or more quantities of incident radiation.
Radiation Protocol Committee (RPC)
-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.
Radiation Therapy Simulation System
- 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.
Radiography
-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.
Radiographic Imaging System
- any system
				  whereby a permanent or temporary image is recorded on an image receptor by the
				  action of ionizing radiation.
Rating
- the operating limits as specified
				  by the component manufacturer.
Recording
-producing a permanent or
				  retrievable form of an image resulting from X-ray photons.
Reference Plane
-a plane that is displaced
				  from and parallel to the tomographic plane.
Registrant
- as used in this Chapter, any
				  person who owns or possesses and administratively controls an X-ray system that
				  is used to deliberately expose humans or animals to the useful beam of the
				  system and is required by the provisions contained in LAC 33:XV.Chapters 1
				  and/or 2 to register with the administrative authority.
Scan
-the complete process of collecting
				  X-ray transmission data for the production of a tomogram. Data can be collected
				  simultaneously during a single scan for the production of one or more
				  tomograms.
Scan Increment
-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.
Scan Sequence
-a preselected set of two or
				  more scans performed consecutively under preselected CT conditions of
				  operation.
Scan Time
-the period of time between the
				  beginning and end of X-ray transmission data accumulation for a single
				  scan.
Scattered Radiation
- radiation that, during
				  passage through matter, has deviated in direction (see
Direct Scattered
				  Radiation
).
Sensitivity Profile
-the relative response of
				  the CT X-ray system as a function of position along a line perpendicular to the
				  tomographic plane.
Secondary Dose Monitoring System
- a system
				  that will terminate irradiation in the event of failure of the primary
				  system.
Secondary Protective Barrier
-(See
Protective Barrier
)
SID
-see
Source-Image Receptor
				  Distance
.
Single Tomogram System
-a CT X-ray system
				  that obtains X-ray transmission data during a scan to produce a single
				  tomogram.
Size-Specific Dose Estimate (SSDE)
-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.
Shutter
- a device attached to the tube
				  housing assembly that can intercept the entire cross sectional area of the
				  useful beam and that has a lead equivalency not less than that of the tube
				  housing assembly.
Source
-the focal spot of the X-ray tube or
				  the region and/or material from which the radiation emanates.
Source-Image Receptor Distance (SID)
- the
				  distance from the source to the center of the input surface of the image
				  receptor.
Spot Check
- a procedure performed to assure
				  that a previous calibration continues to be valid.
Spot Film
- a radiograph made during a
				  fluoroscopic examination to permanently record conditions that exist during
				  that fluoroscopic procedure.
Spot Film Device
- a device intended to
				  transport and/or position a radiographic image receptor between the X-ray
				  source and fluoroscopic image receptor. The term includes a device intended to
				  hold a cassette over the input end of an image intensifier for the purpose of
				  making a radiograph.
Source-Skin Distance (SSD)
-the distance from
				  the source to the center of the entrant X-ray field in the plane tangent to the
				  patient skin surface.
Spot Film Device
-a device intended to
				  transport and/or position a radiographic image receptor between the X-ray
				  source and fluoroscopic image receptor. The term includes a device intended to
				  hold a cassette over the input end of the fluoroscopic image receptor for the
				  purpose of producing a radiograph.
Stationary X-Ray Equipment
-(See
X-Ray Equipment
)
Stray Radiation
- the sum of leakage and
				  scattered radiation.
Substantial Radiation Dose Level (SRDL)
-an
				  appropriately-selected dose used to trigger additional dosemanagement actions
				  during a procedure and medical follow up for a radiation level that might
				  produce a clinically-relevant injury in an average patient.
Technique Factors
- the following conditions
				  of operation:
1. for capacitor energy
				storage equipment, peak tube potential in kV and quantity of charge in
				mAs;
2. for field emission
				equipment rated for pulsed operation, peak tube potential in kV, and number of
				X-ray pulses;
3. 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;
4. 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;
				and
5. 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.
Termination of Irradiation
- the stopping of
				  irradiation in a fashion that will not permit continuance of irradiation
				  without the resetting of operating conditions at the control panel.
Therapeutic-Type Protective Tube Housing
-
				  the tube housing with tube installed. It includes high voltage and/or filament
				  transformers and other appropriate elements when they are contained within the
				  tube housing.
Tomographic Plane
-that geometric plane
				  identified as corresponding to the output tomogram.
Tomographic Section
-the volume of an object
				  whose X-ray attenuation properties are imaged in a tomogram.
Traceable to a National Standard
- refers to
				  a quantity or a measurement that has been compared to a national standard
				  directly or indirectly through one or more intermediate steps, and all
				  comparisons have been documented.
Tube
- an X-ray tube, unless otherwise
				  specified.
Tube Housing Assembly
- 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.
Tube Rating Chart
- the set of curves that
				  specify the rated limits of operation of the tube in terms of the technique
				  factors.
Unintended
-a radiation dose received by a
				  patient in diagnostic or interventional X-ray resulting from human error or
				  equipment malfunction during a procedure.
Unprotected Area
- any area in which the
				  exposure rate, due to the use of the radiation machine under normal operating
				  procedures and workloads, exceeds any of the following limits:
1. 2 milliroentgens in any one
				hour;
2. 100 milliroentgens in any
				seven consecutive days; or
3. 500
				milliroentgens in any one year.
Useful Beam
-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.
Variable-Aperture Beam-Limiting Device
- a
				  beam-limiting device that has the capacity for stepless adjustment of the X-ray
				  field size at a given SID.
Visible Area
- that portion of the input
				  surface of the image receptor over which incident X-ray photons are producing a
				  visible image.
volume Computed Tomography Dose Index (CTDI
				  vol)
-a radiation dose parameter derived from
				  the CTDIw (weighted or average CTDI given across the field of view). The
				  equation 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).
Or, for helical scans,
CTDIvol = CTDIw
				  / pitch
Wedge Filter
-an added filter effecting
				  continuous progressive attenuation on all or part of the useful beam.
Weighted Computed Tomography Dose Index
				  (CTDIw)
-the estimated average CTDI100 across
				  the field of view (FOV). The equation is:
CTDIw = 1/3CTDI100, center + 2/3CTDI100, edge.
Where 1/3 and 2/3 approximate the relative areas represented
				  by the center and edge values derived using the 16 or 32 cm acrylic phantom.
				  CTDIw uses CTDI100 and an f-factor for air (0.87 rad/R or 1.0 mGy/mGy).
X-Ray Control
- a device that 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.
X-Ray Equipment
-an X-ray system, subsystem,
				  or component thereof. Types of X-ray equipment are as follows:
a.
Mobile X-Ray
				Equipment
-X-ray equipment mounted on a permanent base with wheels
				and/or casters for moving while completely assembled.
b.
Portable X-Ray
				Equipment
-X-ray equipment designed to be hand-carried.
c.
Stationary X-Ray
				Equipment
-X-ray equipment that is installed in a fixed
				location.
d.
Transportable
				X-Ray Equipment
-X-ray equipment installed in a vehicle or
				trailer.
e.
Hand-Held X-Ray
				Equipment
-X-ray equipment that is designed to be hand-held during
				operation.
X-Ray Exposure Control
-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.
X-Ray Equipment
- an X-ray system,
				  subsystem, or component thereof. Types of X-ray equipment are as
				  follows:
1.
Mobile X-Ray
				Equipment
- X-ray equipment mounted on a permanent base with wheels
				and/or casters for moving while completely assembled.
2.
Portable X-Ray Equipment
-
				X-ray equipment designed to be hand-carried.
3.
Stationary X-Ray
				Equipment
- X-ray equipment that is installed in a fixed
				location.
4.
Transportable
				X-Ray Equipment
- X-ray equipment installed in a vehicle or trailer.
X-Ray Field
-that area of the intersection of
				  the useful beam and any one 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 AKR is one-fourth of the maximum in the intersection.
X-Ray High-voltage Generator
- a device that
				  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.
X-Ray Subsystem
- any combination of two or
				  more components of an X-ray system.
X-Ray System
- 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 that function with the system are considered integral parts of the
				  system.
X-Ray Table
-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.
X-Ray Tube
-any electron tube which is
				  designed for the conversion of electrical energy into X-ray energy.