Washington Administrative Code › Title 246 - Health, Department of › RADIATION › Chapter 246-225 - Radiation protection - X rays in the healing arts › Section 246-225-010 - Definitions

Current through Register Vol. 24-14, July 15, 2024
As used in this chapter, the following definitions
				  apply:
(1) "Accessible surface" means
				the external surface of the enclosure or housing provided by the
				manufacturer.
(2) "Accidental
				radiation exposure incident" means an exposure to a patient, an operator, or a
				member of the public that was unintentional.
(3) "Added filter" means the filter added to
				the inherent filtration.
(4)
				"Aluminum equivalent" means the thickness of aluminum (type 1100 alloy)
				affording the same attenuation, under specified conditions, as the material in
				question. (The nominal chemical composition of type 1100 aluminum alloy is
				99.00 percent minimum aluminum, 0.12 percent copper.)
(5) "Assembler" means any person engaged in
				the business of assembling, replacing, or installing one or more components
				into an X-ray system or subsystem. An assembler may be the practitioner,
				his/her employee, an outside contractor, or an employee of an outside
				firm.
(6) "Attenuation block" means
				a block or stack, having dimensions 20 cm by 20 cm by 3.8 cm, of type 1100
				aluminum alloy or other aluminum alloys having equivalent
				attenuation.
(7) "Automatic
exposure
control" means 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").
(8) "Barrier" (see "protective
				barrier").
(9) "Beam axis" means a
				line from the source through the centers of the X-ray fields.
(10) "Beam-limiting device" means a device
				which provides a means to restrict the dimensions of the X-ray field.
(11) "Beam monitoring system" means a system
				designed to detect and measure the radiation present in the useful
				beam.
(12) "C-arm X-ray system"
				means 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.
(13)
				"Cephalometric device" means a device intended for the radiographic
				visualization and measurement of the dimensions of the human head.
(14) "Certified components" means components
				of X-ray systems which have been certified by the manufacturer as meeting the
				requirements of the federal performance standard for X-ray equipment.
(15) "Certified system" means any X-ray
				system which has one or more certified component(s).
(16) "Changeable filters" means any filter,
				exclusive of inherent filtration, which can be removed from the useful beam
				through any electronic, mechanical or physical process.
(17) "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:
Click to view
								image
where
s = Estimated standard deviation of the
								population.
X = Mean value of observations in sample.
X(i) = ith observation
								sampled.
n = Number of observations in sample.
(18)
				"Contact therapy system" means an X-ray system wherein the X-ray tube port is
				put in contact with or within 5 centimeters of, the surface being
				treated.
(19) "Control panel" means
				that part of the X-ray control upon which are mounted the switches, knobs,
				pushbuttons, and other hardware necessary for manually setting the technique
				factors.
(20) "Cooling curve" means
				the graphical relationship between heat units stored and cooling
				time.
(21) "Date of transfer." See
				installation date.
(22) "Dead-man
				switch" means a switch so constructed that a circuit closing contact can be
				maintained only by continuous pressure on the switch by the operator.
(23) "Department" means the department of
				health which has been designated as the state radiation control
				agency.
(24) "Detector" (see
				"radiation detector").
(25)
				"Diagnostic source assembly" means the tube housing assembly with a
				beam-limiting device attached.
(26)
				"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 recording or visualization
				for diagnostic purposes.
(27)
				"Direct scattered radiation" means that scattered radiation which has been
				deviated in direction only by materials irradiated by the useful beam (see also
				"scattered radiation").
(28)
				"Electronic product defect" means an error in design, manufacture, or
				performance of an X-ray system such that unintentional radiation exposure to a
				patient, an operator, or a member of the public has occurred.
(29) "Entrance
exposure
rate" means the exposure measured free-in-air
				per unit time where the useful beam enters the patient.
(30) "Equipment" (see "X-ray
				equipment").
(31)*"
Exposure
"
				means the quotient of dQ divided 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
				(negatrons and positrons) liberated by photons in a volume element of air
				having mass dm are completely stopped in air. (The special unit of
exposure
is the roentgen.)
Note:
*When the word, exposure, is used in this part to
								mean one or more irradiations of a person for a healing arts purpose, or in a
								more general sense, it will not be underlined.
(32)
				"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.
(33) "Filter" means material
				placed in the useful beam to absorb preferentially selected
				radiations.
(34) "Fluoroscopic
				imaging assembly" means a component which comprises a reception system in which
				X-ray photons produce a fluoroscopic image. It includes equipment housings,
				electrical interlocks if any, the primary protective barrier, and structural
				material providing linkage between the image receptor and the diagnostic source
				assembly.
(35) "Focal spot" means
				the area on the anode of the X-ray tube bombarded by the electrons accelerated
				from the cathode, and from which the useful beam originates.
(36) "Full beam detector" means a radiation
				detector of such size that the total cross section of the maximum size useful
				beam is intercepted.
(37) "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.
(38) "Gonad shield" means
				a protective barrier for the testes or ovaries.
(39) "Half-value layer (HVL)" means the
				thickness of specified material which attenuates the beam of radiation to an
				extent such that the
exposure
rate is reduced to
				one-half 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.
(40) "Healing arts screening" means the
				testing of an asymptomatic population 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.
(41) "Heat unit" means a
				unit of energy equal to the product of the peak kilovoltage, miliamperes, and
				seconds, i.e., kVp x mA x second.
(42) "Image intensifier" means a device
				consisting of an image intensifier tube installed in its housing which
				instantaneously converts an X-ray pattern into a light image of higher energy
				density.
(43) "Image receptor"
				means any 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.
(44) "Image
				receptor support" means that part of a mammographic system designed to support
				the image receptor in a plane perpendicular to the X-ray beam during
				mammography.
(45) "Inherent
				filtration" means the filtration of the useful beam provided by the permanently
				installed components of the tube housing assembly.
(46) "Installation date" means the earliest
				date that a machine, accessory, or component is able to be used by a registrant
				or transferee but no later than the date of the first human exposure made using
				the machine, accessory, or component that has been installed.
(47) "Interlock" means a device arranged or
				connected such that the occurrence of an event or condition is required before
				a second event or condition can occur or continue to occur.
(48) "Irradiation" means the exposure of
				matter to ionizing radiation.
(49)
				"Kilovolts peak (kVp)" (see "peak tube potential").
(50) "kV" means kilovolts.
(51) "kWs" means kilowatt second which is
				equal to the product of peak kilovolts, amperes, and seconds or
				10-3 X kV X mA X sec.
(52) "Lead equivalent" means the thickness of
				lead affording the same attenuation, under specified conditions, as the
				material in question.
(53) "Leakage
				radiation" means radiation emanating from the diagnostic or therapeutic source
				assembly except for:
(a) The useful beam
				and
(b) Radiation produced when the
				exposure switch or timer is not activated.