New Mexico Administrative Code › Title 20 - ENVIRONMENTAL PROTECTION › Chapter 3 - RADIATION PROTECTION › Part 6 - X-RAYS IN HEALING ARTS › Section 20.3.6.7 - DEFINITIONS

Current through Register Vol. 35, No. 13, July 16, 2024
As used in this Subpart [Part]:
A. "Accessible surface" means the external
				surface of the enclosure or housing provided by the manufacturer.
B. "Added filter" means the filter added to
				the inherent filtration.
C.
				"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.)
D. "Attenuation block" means a block or stack
				3.8 cm thick of type 1100 aluminum alloy or other material having equivalent
				attenuation.
E. "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").
F. "Barrier" (see "Protective
				barrier").
G. "Beam axis" means a
				line from the source through the center of the x-ray field.
H. "Beam-limiting device" means a device
				which provides a means to restrict the dimensions of the x-ray field.
I. "Changeable filter" means any filter,
				exclusive of inherent filtration, which can be removed from the useful beam
				through any electronic, mechanical or physical process.
J. "Coefficient of variation (SA)" means the
				ratio of the standard deviation to the mean value of a population of
				observations. It is estimated using the following equation:
where:
x = mean value of observations in sample
xi = ith observation in sample
N = number of observations in sample
K. "Collimator" means a device or mechanism
				by which the x-ray beam is restricted in size.
L. "Contact therapy system" means that the
				x-ray tube port is put in contact with, or within 5 centimeters of, the surface
				being treated.
M. "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.
N. "Cooling
				curve" means the graphical relationship between heat units stored and cooling
				time.
O. "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.
P. "Density (D)" (as used in conjunction with
				image receptors) means the logarithm to the base 10 of the ratio of the
				incident to the transmitted luminous flux, where I is luminous flux.
D=LOG SUB 10 [{I~Incident} over {I~Transmitted}]
Q. "Diagnostic source assembly"
				means the tube housing assembly with a beam-limiting device attached.
R. "Diagnostic x-ray system" means an x-ray
				system designed for irradiation of any part of the human body for the purpose
				of diagnosis or visualization.
S.
				"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").
T.
				"Entrance exposure rate" means the roentgens per unit time at the point where
				the center of the useful beam enters the patient.
U. "Equipment" (see "X-ray
				equipment").
V. "Exposure" 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 (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, 1R =
				2.58 x 10-4 C/Kg)
W. "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.
X. "Filter" means material
				placed in the useful beam to absorb preferentially the less penetrating
				components.
Y. "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.
Z. "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.
AA. "Gonad shield" means a
				protective barrier for the testes or ovaries.
AB. "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.
AC. "Image
				intensifier" means a device which produces an image of greater contrast than
				would be produced without the device present.
AD. "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.
AE. "Inherent filtration" means filtration
				permanently in the useful beam; it includes the window of the x-ray tube and
				any permanent tube or source enclosure.
AF. "Interlock" means a device for precluding
				access to a radiation area by automatically terminating exposure upon entry by
				personnel.
AG. "Kilovolts peak
				(kVp)" (see "Peak tube potential").
AH. "kWs" means kilowatt second which is
				equal to the product of peak kilovolts, amperes, and seconds or 103 kVmA
				sec.
AI. "Lead equivalent" means
				the thickness of material in question affording the same attenuation, under
				specified conditions, as the lead in question.
AJ. "Leakage radiation" means 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.