Pennsylvania Code › Title 25 - ENVIRONMENTAL PROTECTION › Part I - Department of Environmental Protection › Subpart D - Environmental Health and Safety › Article V - Radiological Health › Chapter 221 - X-RAYS IN THE HEALING ARTS › GENERAL PROVISIONS › Section 221.2 - Definitions

Current through Register Vol. 54, No. 28, July 13, 2024
The following words and terms, when used in this
						  chapter, have the following meanings, unless the context clearly indicates
						  otherwise:
AAPM
-American Association of
						  Physicists in Medicine.
Air kerma
-Kerma in air.
Air kerma rate
-Air kerma per unit
						  time.
Aluminum equivalent
-The thickness of
						  type 1100 aluminum alloy-the nominal chemical composition of type 1100 aluminum
						  alloy is 99% minimum aluminum, 0.12% copper-affording the same attenuation,
						  under specified conditions, as the material in question.
Automatic exposure control
-A device
						  which automatically controls one or more technique factors to obtain at
						  preselected locations a desired quantity of radiation.
Beam axis
-A line from the source
						  through the centers of the X-ray fields.
Beam-limiting device
-A device
						  providing a means to restrict the dimensions of the X-ray field.
CBCT-Cone beam computed tomography
-A
						  digital volume tomography method used in some imaging applications using
						  two-dimensional digital detector arrays and a cone-shaped X-ray beam, instead
						  of fan-shaped, that rotates around to generate a high-resolution 3D image with
						  high geometric accuracy. Reconstruction algorithms can be used to generate
						  images of any desired plane.
CINE-Cineradiography
-A motion picture
						  record of successive images appearing on a fluoroscopic screen.
CR-Computed radiography
-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. CR systems may use cassettes to house the phosphor or it
						  may be integrated into a DR system.
CT-Computed tomography
-The production
						  of a tomogram by the acquisition and computer processing of X-ray transmission
						  data.
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 which are subject to regulations promulgated under the Radiation
						  Control for Health and Safety Act of 1968 (42 U.S.C.A. §§
													263b-263n).
Certified system
-An X-ray system which
						  has one or more certified components.
Changeable filter
-A filter, exclusive
						  of inherent filtration, which can be added to or removed from the useful beam
						  through an electronic, mechanical or physical process.
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:
Click
						  to view image
Control panel
-The part of the X-ray
						  control upon which are mounted the switches, knobs, pushbuttons and other
						  hardware necessary for manually setting the technique factors.
DDR-Direct digital radiography
-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.
DR-Digital radiography
-
(i) An X-ray imaging method (or radiography)
						which produces a digital rather than film projection image.
(ii) The term includes CR and DDR.
DRL-Diagnostic reference level
-An
						  investigational level, set as a standard by a recognized body (for example, the
						  American College of Radiology, the American Association of Physicists in
						  Medicine, the National Council on Radiation Protection and Measurements or
						  similar), used to identify unusually high radiation doses for common diagnostic
						  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.
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.
Dental panoramic system
-A device
						  intended to produce a radiographic image of both dental arches on one
						  film.
Diagnostic source assembly
-The tube
						  housing assembly with a beam-limiting device attached.
Diagnostic X-ray system
-An X-ray
						  system designed for irradiation of a part of the human body for the purpose of
						  diagnosis or visualization.
Direct supervision
-A licensed
						  practitioner of the healing arts who exercises general supervision and is
						  present in the facility and immediately available to furnish assistance and
						  direction throughout the performance of the procedure. The licensed
						  practitioner does not have to be present in the room when the procedure is
						  being performed.
Dose length product
-The indicator of
						  the integrated radiation dose from a complete CT examination. It addresses the
						  total scan length by the following formula:
DLP (mGy - cm) = CTDIvol (mGy) x
						  scan length (cm)
Electronic brachytherapy
-A modality
						  of radiation therapy where an electrically generated source of ionizing
						  radiation is placed in or near the tumor or target tissue to deliver
						  therapeutic radiation dosage. X-ray devices specifically designed and solely
						  used to treat skin cancer lesions are not considered electronic brachytherapy
						  devices under this definition and must meet the applicable parts of this title
						  pertaining to registration and use.
Emerging technology
-An innovative
						  medical technology that uses an ionizing radiation source.
Entrance exposure rate
-The exposure in
						  air per unit time at the point where the center of the useful beam enters the
						  patient.
FGI-Fluoroscopic-guided interventional
						  procedures
-An interventional diagnostic or therapeutic high-risk
						  procedure performed by means of percutaneous or other access routes, usually
						  with local anesthesia or intravenous sedation, which uses external ionizing
						  radiation in the form of fluoroscopy to do all of the following:
(i) Localize or characterize a lesion,
						diagnostic site or treatment site.
(ii) Monitor the procedure.
(iii) Control and document the procedure.
Field emission equipment
-Equipment
						  using an X-ray tube in which electrons are emitted from the cathode solely by
						  the force between an electric field and the electrons.
Filter
-Material placed in the useful
						  beam to modify the spectral energy distribution and flux of the transmitted
						  radiation and preferentially absorb selected radiation.
Filtration
-The amount of material
						  placed in the useful beam to modify the radiation's characteristics, typically
						  expressed in terms of millimeters of aluminum or copper equivalent.
Fluoroscopic imaging assembly
-A
						  subsystem in which X-ray photons produce a fluoroscopic image. The term
						  includes the image receptors such as the image intensifier and spot-film
						  device, electrical interlocks, if any, and structural material providing
						  linkage between the image receptor and diagnostic source assembly.
Fluoroscopic system
-See fluoroscopic
						  imaging assembly.
Focal spot
-The area projected on the
						  anode of the X-ray tube by the electrons accelerated from the cathode and from
						  which the useful beam originates.
General supervision
-The overall
						  direction and control of a licensed practitioner of the healing arts. The
						  licensed practitioner is not required to be present during the performance of
						  the procedure.
HVL-Half-value layer
-
(i) The thickness of specified material which
						attenuates the exposure rate by 1/2 when introduced into the path of a given
						beam of radiation. 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.
(ii) The term is used to describe the
						penetrating ability of the radiation.
Healing arts screening
-The testing of
						  human beings using X-ray machines for the detection or evaluation of health
						  indications when the tests are not specifically and individually ordered for
						  the purpose of diagnosis or treatment by a licensed practitioner of the healing
						  arts legally authorized to prescribe the X-ray tests.
Health physics
-An application of
						  physics concerned with protection of people and the environment from the
						  biological effects of radiation.
High-risk procedure
-Any radiologic
						  procedure that uses energies of less than 1 million electron volts that could
						  exceed skin doses of 200 rad (2.0 Gy).
IORT-Intraoperative radiation
						  therapy
-A modality of therapy in which therapeutic levels of ionizing
						  radiation are applied to a target area, such as a cancer tumor, while the area
						  is exposed during surgery.
Image intensifier
-An image receptor
						  with electronic amplification, installed in its housing, which instantaneously
						  converts an X-ray pattern into a corresponding light image of higher energy
						  density.
Image receptor
-A device, such as a
						  fluorescent screen or radiographic film, 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.
Intensifying screen
-A fluorescent
						  screen which transforms incident X-ray photons into a visible image.
Intraoral dental radiography
-A
						  modality of dental radiography in which the image receptor is placed inside a
						  patient's oral cavity.
kV
-Kilovolts
kVp
-Peak
						  tube potential (see kilovolts peak).
Kerma
-A measure of energy transferred
						  from radiation to matter and means kinetic energy released per unit mass. It is
						  related to, but not the same as, absorbed dose. Unit of measure is gray.
Kilovolts peak (kVp)
-The maximum value
						  of the potential difference across the X-ray tube during an exposure.
Lead equivalent
-The thickness of lead
						  affording the same attenuation, under specified conditions, as the material in
						  question.
Leakage radiation
-Radiation emanating
						  from the diagnostic or therapeutic source assembly except for the
						  following:
(i) The useful
						beam.
(ii) Radiation produced when
						the exposure switch or timer is not activated.
Leakage technique factors
-The
						  technique factors associated with the tube housing assembly which are used in
						  measuring leakage radiation defined as follows:
(i) 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
						charge per exposure being 10 millicoulombs-10 milliampere seconds-or the
						minimum charge obtainable from the unit, whichever is larger.
(ii) 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.
(iii) For other
						equipment, the maximum-rated peak tube potential and the maximum-rated
						continuous tube current for the maximum-rated peak tube potential.
Licensed practitioner of the healing
						  arts
-An individual licensed by the Commonwealth to practice the
						  healing arts, which for the purposes of this article shall be limited to
						  medicine, surgery, dentistry, osteopathy, podiatry and chiropractic.
Light field
-The area defined by the
						  intersection of the light beam with a plane parallel with the plane of the
						  image receptor. The edge of the field is defined by the points at which the
						  light intensity is 25% of the maximum light intensity in the plane.
Line-voltage regulation
-The difference
						  between the no-load and the load line potentials expressed as a percent of the
						  load line potential calculated using the following equation:
Percent line-voltage regulation = 100
						  (Vn -
						  V1)/V1
where
Vn = No-load line potential
						  and
V1 = Load line potential.
Low-risk procedure
-Any radiologic
						  procedure that is not a high-risk procedure.
mA
-Milliampere.
mAs
-Milliampere second.
mR
-Milliroentgen.
Maximum line current
-The
						  root-mean-square current in the supply line of an X-ray machine operating at
						  its maximum rating.
Medical physics
-An application of
						  physics that addresses the needs of medicine or health care. Subfields of
						  medical physics include the following:
(i) Therapeutic medical physics.
(ii) Diagnostic medical physics or
						imaging.
(iii) Nuclear medical
						diagnostic or molecular imaging and therapy.
(iv) Medical health physics or radiation
						protection.
Mobile X-ray system
-See X-ray
						  equipment.
Patient
-An individual subjected to
						  healing arts examination, diagnosis or treatment.
Peak tube potential
-The maximum value
						  of the potential difference across the X-ray tube during an exposure.
Performance phantom
-A device
						  specifically approved by the QMP or QE for evaluation of operational
						  conformance with tolerances established by the QMP, QE or manufacturer.
Personal supervision
-A licensed
						  practitioner of the healing arts who exercises general supervision and is
						  present in the room or adjacent control area during the performance of the
						  procedure.
Phototimer
-A method for controlling
						  the radiation exposures to an image receptor by measuring the radiation which
						  reaches a radiation monitoring device. The radiation monitoring device is part
						  of an electronic circuit which controls the duration of time the tube is
						  activated.
Portable radiation system
-See X-ray
						  equipment.
Portable X-ray system
-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.
Positive beam limitation
-The automatic
						  or semiautomatic adjustment of an X-ray beam to the size of the selected image
						  receptor, whereby an X-ray exposure cannot be made without an adjustment.
Protective apron
-An apron
						  incorporating radiation absorbing materials.
Protective barrier
-A barrier of
						  radiation absorbing material used to reduce radiation exposure. The term
						  includes the following types:
(i)
Primary protective barrier
-Material used to reduce radiation
						exposure from the useful beam.
(ii)
Secondary protective barrier
-Material used to reduce exposure
						from stray, leakage or scattered radiation.
QE-Qualified expert
-The term as
						  defined in §
												215.2 (relating to
						  definitions).
QMP-Qualified medical physicist
-An
						  individual who is competent to independently provide clinical professional
						  services and practices only in health or radiological physics, or in the
						  subfields of medical physics.
(i) A QMP
						meets all of the following credentials:
(A)
						Certified in the field of medical physics, radiological physics, medical health
						physics or health physics by an appropriate national certifying body recognized
						by the Department.
(B) Complies
						with the certifying body's requirements for continuing education and
						recertification.
(C) Provides
						clinical professional services and practices only in health/radiological
						physics or in one or more of the subfields of medical physics, consistent with
						the individual's training and experience, and in accordance with the
						individual's respective certifying body's code of ethics.