Mississippi Administrative Code
Title 15 - Mississippi Department of Health
Part 21 - Division of Radiological Health
Subpart 78 - Radiological Health
Chapter 1 - REGULATIONS FOR CONTROL OF RADIATION IN MISSISSIPPI
Subchapter 6 - X-Rays In The Healing Arts
Rule 15-21-78-1.6.2 - Definitions
As used in this section, the following definitions apply:
1. "Accessible surface" means the external surface of the enclosure or housing provided by the manufacturer.
2. "Added filtration" means any filtration which is in addition to the inherent filtration.
3. "Aluminum equivalent" means the thickness of type 1100 aluminum alloy29 affording the same attenuation, under specified conditions, as the material in question.
4. "Assembler" means 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.
5. "Attenuation block" means 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.
6. "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").
7. "Barrier" (See "Protective barrier").
8. "Beam axis" means a line from the source through the centers of the x-ray fie 1ds.
9. "Beam-limiting device" means a device which provides a means to restrict the dimensions of the x-ray field.
10. "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.
11. "Cephalometric device" means a device intended for the radiographic visualization and measurement of the dimensions of the human head.
12. "Certified components" means components of x-ray systems which are subject to regulations promulgated under Public Law 90-602, the Radiation Control for Health and Safety Act of 1968.
13. "Certified system" means any x-ray system comprised totally of certified components.
14. "Changeable filters" means any filter, exclusive of inherent filtration, which can be removed from the useful beam through any electronic, mechanical, or physical process.
15. "Coefficient of variation" or "C" means the ratio of the standard deviation to the mean value of a sample population of observations. It is estimated using the following equation:
where
s = Estimated standard deviation of the population.
X= Mean Value of observations in sample.
Xi = ith observation in sample.
n = Number of observations in sample.
16. "Computed tomography" means the production of a tomogram by the acquisition and computer processing of x-ray transmission data.
17. "Control panel" means that part of the x-ray control upon which are mounted the switches, knobs, pushbuttons, and other hardware necessary for setting the technique factors.
18. "Cooling curve" means the graphical relationship between heat units stored and cooling time.
19. "CT" (See "Computed tomography").
20. "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.
21. "Detector" (See "Radiation detector").
22. "Diagnostic source assembly" means the tube housing assembly with a beam-limiting device attached.
23. "Diagnostic x-ray imaging system" means 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.
24. "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.
25. "Direct scattered radiation" means that scattered radiation which has been deviated in direction only by materials irradiated by the useful beam (See "Scattered radiation").
26. "Entrance exposure rate" means the exposure free in air per unit time at the point where the center of the useful beam enters the patient.
27. "Equipment" (See "X-ray equipment").
28. "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."
29. "Filter" means material placed in the useful beam to absorb preferentially selected radiations.
30. "Fluoroscopic imaging assembly" means a subsystem in which x-ray photons produce a fluoroscopic image. It includes the image receptor(s) 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.
31. "Focal spot" means 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.
32. "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.
33. "Gonad shield" means a protective barrier for the testes or ovaries.
34. "Half-value layer" 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.
35. "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.
36. "HVL" (See "Half-value layer").
37. "Image intensifier" means a device, installed in its housing, which instantaneously converts an x-ray pattern into a corresponding light image of higher energy density.
38. "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.
39. "Image receptor support" means, for mammographic systems, that part of the system designed to support the image receptor during mammography.
40. "Inherent filtration" means the filtration of the useful beam provided by the permanently installed components of the tube housing assembly.
41. "Irradiation" means the exposure of a living being or matter to ionizing radiation.
42. "Kilovolt (kV) [kilo electron volt (keV)]" means the energy equal to that acquired by a particle with one electron charge in passing through a potential difference of one thousand volts in a vacuum. [Note: current convention is to use kV for photons and keV for electrons].
43. "Kilovolts peak" (See "Peak tube potential").
44. "kVp" (See "Peak tube potential").
45. "kWs" means kilowatt second.
46. "Lead equivalent" means the thickness of the material in question affording the same attenuation, under specified conditions as lead.
47. "Leakage radiation" means radiation emanating from the diagnostic source assembly except for:
a. the useful beam; and
b. radiation produced when the exposure switch or timer is not activated.
48. "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 10 millicoulombs, i.e., 10 milliampere seconds, 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.
c. 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.
49. "Light field" means the area illuminated by light, being the locus of points at which the illumination exceeds a specific or specified level, simulating the radiation field.
50. "Line-voltage regulation" means the difference between the no-load and the load line potentials expressed as a percent of the load line potential. It is calculated using the following equation:
Percent line-voltage regulation = 100 (Vn-V1)/V1
where
Vn = No-load line potential and
V1 = Load line potential.
51. "mA" means milliampere.
52. "mAs" means milliampere second.
53. "Maximum line current" means the root-mean-square current in the supply line of an x-ray machine operating at its maximum rating.
54. "Mobile x-ray equipment" (See "X-ray equipment").
55. "Patient" means an individual or animal subjected to healing arts examination, diagnosis, or treatment.
56. "PBL" See "Positive beam limitation."
57. "Peak tube potential" means the maximum value of the potential difference across the x-ray tube during an exposure.
58. "Phantom" means a volume of material behaving in a manner similar to tissue with respect to the attenuation and scattering of radiation.
59. "Phototimer" means a method for controlling radiation exposures to image receptors by measuring the amount of radiation which reaches a radiation monitoring device(s). The radiation monitoring device(s) is part of an electronic circuit which controls the duration of time the tube is activated (See "Automatic exposure control").
60. "PID" (See "Position indicating device").
61. "Portable x-ray equipment" (See "X-ray equipment").
62. "Position indicating device" 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.
63. "Positive beam limitation" means the automatic or semiautomatic adjustment of an x-ray beam to the selected image receptor size, whereby exposures cannot be made without such adjustment.
64. "Primary protective barrier" (See "Protective barrier").
65. "Protective apron" means an apron made of radiation absorbing materials used to reduce radiation exposure.
66. "Protective barrier" means a barrier of radiation absorbing material(s) used to reduce radiation exposure. The types of protective barriers are as follows:
a. "Primary protective barrier" means the material, excluding filters, placed in the useful beam, to protect anyone other than the patient from radiation exposure.
b. "Secondary protective barrier" means a barrier sufficient to attenuate the stray radiation to the required degree.
c. "Protective glove" means a glove made of radiation absorbing materials used to reduce radiation exposure.
67. "Qualified expert" means an individual who has demonstrated to the satisfaction of the Agency that such individual possesses the knowledge, training, and experience to measure ionizing radiation, to evaluate safety techniques, and to advise regarding radiation protection needs.
68. "Radiation detector" means a device which in the presence of radiation provides a signal or other indication suitable for use in measuring one or more quantities of incident radiation.
69. "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.
70. "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.
71. "Radiographic imaging system" means any system whereby a permanent or temporary image is recorded on an image receptor by the action of ionizing radiation.
72. "Rating" means the operating limits as specified by the component manufacturer.
73. "Recording" means producing a permanent form of an image resulting from x-ray photons.
74. "Scattered radiation" means radiation that, during passage through matter, has been deviated in direction (See "Direct scattered radiation").
75. "Secondary protective barrier" (See "Protective barrier").
76. "Shutter" means a device attached to the tube housing assembly which can totally intercept the entire cross section area of the useful beam and which has a lead equivalency not less than that of the tube housing assembly.
77. "SID" (See "Source-image receptor distance").
78. "Source" means the focal spot of the x-ray tube.
79. "Source-image receptor distance" means the distance from the source to the center of the input surface of the image receptor.
80. "Spot film" means a radiograph which is made during a fluoroscopic examination to permanently record conditions which exist during that fluoroscopic procedure.
81. "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 an image intensifier for the purpose of making a radiograph.
82. "SSD" means the distance between the source and the skin entrance plane of the patient.
83. " Stationary x-ray equipment" (See "X-ray equipment").
84. " Stray radiation" means the sum of leakage and scattered radiation.
85. "Technique factors" means the following conditions of operation:
a. for capacitor energy storage equipment, peak tube potential in kV and quantity of charge in 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; and
e. 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.
86. "Termination of irradiation" means the stopping of irradiation in a fashion which will not permit continuance of irradiation without the resetting of operating conditions at the control panel.
87. "Tomogram" means the depiction of the x-ray attenuation properties of a section through a body.
88. "Tube" means an x-ray tube, unless otherwise specified.
89. "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.
90. "Tube rating chart" means the set of curves which specify the rated limits of operation of the tube in terms of the technique factors.
91. "Useful beam" means the radiation emanating from the tube housing port or the radiation head and passing through the aperture of the beam-limiting device when the exposure controls are in a mode to cause the system to produce radiation.
92. "Variable-aperture beam-limiting device" means a beam-limiting device which has capacity for stepless adjustment of the x-ray field size at a given SID.
93. "Visible area" means that portion of the input surface of the image receptor over which incident x-ray photons are producing a visible image.
94. "X-ray exposure control" means a device, switch, button, or other similar means by which an operator initiates and/or terminates the radiation exposure.
95. "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.
c. "Stationary x-ray equipment" means x-ray equipment which is installed in a fixed location.
96. "X-ray field" means 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 exposure rate is one-fourth of the maximum in the intersection.
97. "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.
98. "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.
99. "X-ray subsystem" means any combination of two or more components of an x-ray system.
100. "X-ray tube" means any electron tube which is designed to be used primarily for the production of x-rays.
29 The nominal chemical composition of type 1100 aluminum alloy is 99.00 percent minimum aluminum, 0.12 percent copper.
Miss. Code Ann. § 45-14-11
