Ohio Administrative Code
Title 3701:1 - Radiation Control
Chapter 3701:1-67 - External Beam Radiation Therapy Equipment
Section 3701:1-67-01 - Definitions
Universal Citation: OH Admin Code 3701:1-67-01
Current through all regulations passed and filed through March 18, 2024
(A) Terms defined in rule 3701:1-38-01 of the Administrative Code shall have the same meaning when used in Chapter 3701:1-67 of the Administrative Code except for:
(1)
Terms redefined within this rule which shall be used within Chapter 3701:1-67
of the Administrative Code; and
(2)
Terms redefined in specific rules in Chapter 3701:1-67 of the Administrative
Code, are for use within that specific rule only.
(B) As used in this chapter:
(1) "Absorbed dose " means the mean energy imparted by ionizing
radiation to matter. Absorbed dose is determined as the quotient of dE by dM,
where dE is the mean energy imparted by ionizing radiation to matter of mass
dM. The SI unit of absorbed dose is joule per kilogram and the special name of
the unit of absorbed dose is the gray (Gy). The previously used special unit of
absorbed dose (rad) is being replaced by the gray.
(2) "Absorbed dose rate" means absorbed dose
per unit time, for machines with timers, or dose monitor unit per unit time for
linear accelerators.
(3) "Air
kerma" means the sum of the initial kinetic energy of all charged ionizing
particles liberated by uncharged ionizing radiation in a given mass of air. The
unit for air kerma is joules per kilogram which is given the special name of
gray (Gy). To determine air kerma in Gy from exposure in units of roentgens (R)
multiply exposure by the conversion factor 0.00876 Gy/R.
(4) "Authorized user"
means an individual qualified in accordance with paragraph (C) of rule
3701:1-67-02
of the Administrative Code.
(5) "Beam axis" means
the axis of rotation of the beam limiting device.
(6) "Beam-limiting
device" means a field defining collimator, integral to the therapy equipment,
which provides a means to restrict the dimensions of the useful beam.
(7)
"Beam monitoring system" means a system installed in the radiation head to
detect and measure the radiation present in the useful beam.
(8)
"Beam scattering foil" means a thin piece of material, usually metallic, placed
in the beam to scatter a beam of electrons in order to provide a more uniform
electron distribution in the useful beam.
(9) "Computed
tomography" or " (CT)" means an imaging procedure
that uses multiple x-ray transmission measurements and a computer program to
generate tomographic images of a patient or material.
(10)
"Contact therapy system" means a therapeutic radiation machine that is a type
of electronic brachytherapy device.
(11) "Control panel"
means that part of the radiation-generating equipment control system used to
initiate and terminate the beam.
(12) "Control system"
means the collective hardware and software components used for determining and
selecting the treatment parameters and monitor the course of
treatment.
(13) "Conventional
simulator" means any x-ray system designed to reproduce the geometric
conditions of the radiation therapy equipment.
(14) "Daily" means
each treatment day before the evaluated equipment component is used
clinically.
(15) "Direct
supervision" means to be physically present at the same address and available
to respond to the needs of something or someone.
(16) "Dose monitoring
system" means
(a) "Primary dose monitoring
system" means a system which will monitor the useful beam during irradiation
and which will terminate irradiation when a pre-selected number of dose monitor
units have been delivered.
(b)
"Secondary dose monitoring system" means a system which will terminate
irradiation in the event of failure of the primary dose monitoring
system.
(17) "Dose rate" means
absorbed dose per unit time, for machines with timers, or monitor unit per unit
time for linear accelerators.
(18) "Electronic
brachytherapy" means a method 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.
(19) "Electronic
brachytherapy device" means the system used to deliver electronic brachytherapy
including the x-ray tube, the control mechanism, the cooling system, and the
power source.
(20) "Electronic
brachytherapy source" means the x-ray tube component used in an electronic
brachytherapy device.
(21) "External beam
radiation therapy" means therapeutic irradiation in which the source of
radiation is at a distance from the body.
(22) "Field-flattening
filter" means a filter used to homogenize the absorbed dose rate over the
radiation field.
(23) "Filter" means
material placed in the useful beam to preferentially attenuate selected
radiations.
(24) "Gantry" means
that part of a radiation therapy system supporting and allowing movements of
the radiation head about a center of rotation.
(25) "Individual
responsible for radiation protection (IRRP)" means an individual designated by
the registrant who has the knowledge and responsibility for overall radiation
safety and the quality assurance program at the facility, to include daily
radiation safety operations and compliance with the rules.
(26)
"Intensity Modulated Radiation Therapy (IMRT)" means radiation therapy that
uses non-uniform radiation beam intensities which have been determined by
various computer-based optimization techniques.
(27) "Interlock" means
a device preventing the start or continued operation of equipment unless
certain predetermined conditions prevail.
(28) "Interruption of
irradiation" means the stopping of irradiation with the possibility of
continuing irradiation without resetting of operating conditions via the
control system.
(29) "Irradiation"
means the exposure of a living being or matter to ionizing radiation.
(30)
"Isocenter" means the center of the sphere through which the useful beam axis
passes while the gantry moves through its full range of motions.
(31)
"Leakage radiation" means radiation emanating from the radiation therapy system
except for the useful beam.
(32) "Light field"
means the area illuminated by light, simulating the radiation field.
(33)
"Medical Event"
means an event that meets the criteria in paragraph (B) or (C) of rule
3701:1-67-12
of the Administrative Code.
(34) "Megavolt" or " (MV)" or "mega electron volt (MeV)" means the
energy equal to that acquired by a particle with one electron charge in passing
through a potential difference of one million volts in a vacuum. Current
convention is to use MV for photons and MeV for electrons.
(35) "Mobile
Electronic Brachytherapy Service" means transportation of an electronic
brachytherapy device to provide electronic brachytherapy at an address that is
not the address of record.
(36) "Monitor unit" or " (MU)" means a unit response from the beam
monitoring system from which the absorbed dose can be calculated.
(37)
"Monthly" means at least once each calendar month, not to exceed forty-five
days from previous event.
(38) "Moving beam
radiation therapy" means radiation therapy with any planned displacement of
radiation field or patient relative to each other, or with any planned change
of absorbed dose distribution. It includes arc, skip, conformal, intensity
modulation and rotational therapy.
(39) "Nominal
treatment distance" means:
(a) For electron
irradiation, the distance from the scattering foil, virtual source, or exit
window of the electron beam to the entrance surface of the irradiated object
along the central axis of the useful beam.
(b) For x-ray irradiation, the virtual source
or target to isocenter distance along the central axis of the useful beam. For
non-isocentric equipment, this distance shall be that specified by the
manufacturer.
(40) "Patient" means
an individual or animal subjected to radiation from therapy equipment for the
purposes of medical therapy.
(41) "Peak tube
potential" means the maximum value of the potential difference across the x-ray
tube during an exposure.
(42) "Phantom" means
an object behaving in essentially the same manner as tissue, with respect to
absorption or scattering of the ionizing radiation in question.
(43)
"Prescribed dose" means the total dose and dose per fraction as documented in
the written directive. The prescribed dose is a estimation from measured data
from a piece of therapy equipment using assumptions that are clinically
acceptable for that treatment technique and historically consistent with the
clinical calculations previously used for patients treated with the same
clinical technique.
(44) "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.
(b) "Secondary protective barrier" means the
material which attenuates stray radiation.
(45) "Qualified
Medical Physicist" means an individual qualified in accordance with paragraph
(D) of rule
3701:1-67-02
of the Administrative Code.
(46) "Radiation
detector or detector" means a device which, in the presence of radiation
provides, by either direct or indirect means, a signal or other indication
suitable for use in measuring one or more quantities of incident
radiation.
(47) "Radiation head"
means the structure from which the useful beam emerges.
(48)
"Redundant beam monitoring system" means a combination of two independent dose
monitoring systems in which each system is designed to terminate irradiation in
accordance with a pre-selected number of dose monitor units.
(49)
"Shutter" means a device attached to the tube housing assembly which can
intercept the useful beam and which has a lead equivalency not less than that
of the tube housing assembly.
(50) "Signature" or
"sign" means an identifier that authenticates the person who made it.
(51)
"Simulator" or "radiation therapy simulation system" means any x-ray system
intended for localizing the volume to be exposed during radiation therapy and
establishing the position and size of the therapeutic irradiation
field.
(52) "Source" means
the point of origin of the useful radiation beam.
(53) "Stationary beam
radiation therapy" means radiation therapy without displacement of one or more
mechanical axes relative to the patient during irradiation.
(54)
"Stray radiation" means the sum of leakage and scattered radiation.
(55)
"Target" means that part of an x-ray tube or accelerator onto which a beam of
accelerated particles is directed to produce ionizing radiation or other
particles.
(56) "Target-skin
distance" or " (TSD)" means the distance measured
along the beam axis from the center of the front surface of the x-ray target
and/or electron virtual source to the surface of the irradiated object or
patient.
(57) "Technique
factors" means any combination of the following which determines the exposure
rate: kVp, mA, time, x-ray pulses, or the product of tube current and exposure
time in mAs.
(58) "Tenth-value
layer" or " (TVL)" means the thickness of a
specified material which attenuates X-radiation or gamma radiation to an extent
such that the air kerma rate, exposure rate, or absorbed dose rate is reduced
to one-tenth of the value measured without the material at the same
point.
(59) "Termination of
irradiation" means the stopping of irradiation in a fashion which will not
permit continuance of irradiation without the resetting of operating conditions
via the control system.
(60) "Therapy
equipment" means x-ray or electron-producing equipment designed and used for
external beam radiation therapy. For the purpose of these regulations, devices
used to administer electronic brachytherapy or contact therapy shall also be
considered therapy equipment.
(61) "Treatment site"
means the description of the specific tissue volume intended to receive a
radiation dose, as described in the written directive and treatment
plan.
(62) "Tube" means an
x-ray tube, unless otherwise specified.
(63) "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.
(64) "Useful beam" or
"radiation field" 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 therapy equipment to
produce radiation.
(65) "Virtual
Simulator" means a computed tomography (CT) unit used in conjunction with
relevant software which recreates the treatment machine; and that allows
import, manipulation, display, and storage of images from CT and/ or other
imaging modalities.
(66) "Virtual source"
means a point from which radiation appears to originate.
(67)
"Wedge" means a device which effects continuous change in transmission over all
or a part of the useful beam.
(68) "Weekly" means
once per calendar week in which the evaluated equipment component has or will
be used clinically, unless the equipment component was not evaluated during the
prior week. If the equipment component was not evaluated during the prior week,
"weekly" means once per calendar week before the evaluated equipment component
is used clinically.
(69) "Written
directive" means a documented order for the administration of radiation to a
specific patient or human research subject, as specified in paragraph (B) of
rule
3701:1-67-04
of the Administrative Code.
(70) "X-ray tube"
means any electron tube which is designed to be used primarily for the
production of x-rays.
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