ANSI/HPS N43.2-2001
Health Physics
Society
An American National Standard
Radiation Safety for X-ray Diffraction
and Fluorescence Analysis
Equipment
ANSI/HPS N43.2-2001
An American National Standard -
Radiation Safety for X-ray Diffraction
and Fluorescence Analysis Equipment
Approved: July 31, 2001
American National Standards Institute, Inc.
Forward
(This forward is not part of ANSI/HPS N43.2-2001, Radiation Safety for X-ray Diffraction and
Fluorescence Analysis Equipment.)
The problem of radiation hazards connected with the operation of x-ray diffraction and fluorescence
analysis equipment has been a continuing one since the advent of such equipment. While many
improvements have been made in safety since the last release of this standard, many pieces of older and
custom-built equipment are still in use today. In addition, new uses have been found in areas like surface
and thin film analysis that were not addressed in the original standard. This revision is meant to
modernize the past recommendations (many of which are still valid, however) and to provide guidance for
x-ray use in new technologies.
Historically, the American Standards Association (ASA), Sectional Committee Z54, in 1946 issued
American War Standard Z54.1 “Safety Code for the Industrial Use of X-rays” which included a section on
x-ray diffraction. In 1967, the ASA was superseded by the USA Standard Institute, and Sectional
Committee Z54 was replaced by Committee N43 under the sponsorship of the National Bureau of
Standards (NBS).
Responsibility for the development of the original standard was assigned to Subcommittee N43-1.
American National Standard N43.2-1971 “Radiation Safety for X-ray Diffraction and Fluorescence
Analysis Equipment” was approved on October 6, 1971, published as NBS Handbook 111, and then
reaffirmed with minor revisions in 1976. In 1985, the Health Physics Society replaced the National Bureau
of Standards as the Secretariat for the N43 Committee.
In 1988 Subcommittee N43.2 reformed to begin updating process and had the standard reaffirmed in
March 1989. Revision work was completed in December 1998 and the draft received N43 Committee
approval April 23, 1999.
Suggestions for improvement gained in the use of this standard will be welcome. They should be sent to
HPS Standards Program Director, Health Physics Society, 1313 Dolley Madison Blvd., Suite 402,
McLean, VA 22101, USA.
iv
Below is the list of Members of Subcommittee N43.2 which had the responsibility for the development of
ANSI/HPS 43.2-2001:
Jeffrey Leavey, Chair
(IBM Corporation)
David Allard
(Pennsylvania Bureau of Radiation Protection)
Mike Byrnes
(Lucent Technologies)
Ted de Castro
(Lawrence Berkeley Laboratory)
Mark Depp
(formerly with Bruker AxS)
Len DeRoche
(formerly with Rigaku USA)
Wes Dunn
(formerly with International Isotopes, Inc.)
Reed Durham
(Lockheed Martin Energy Systems)
William Morris
(Dept. of the Navy)
Robert Westerdale
(EDAX, Inc.)
iii
This standard was consensus balloted and approved by the ANSI-Accredited HPS N43 Committee on
April 23, 1999. At that time, the N43 Standards Committee had the following membership:
Chair
Vice Chair
ABB Industrial Systems Inc.
Alliance of American Insurers
American Automobile Manufacturers Association
American Conference of Governmental Industrial Hygienists
American Crystallographic Association
American Insurance Services Group
American Iron and Steel Institute
American Public Health Assoc., Inc.
American Society for Nondestructive Testing, Inc.
American Society for Testing and Materials
Atomic Energy Control Board
Conference of Radiation Control Program Directors
Health Physics Society
National Institute of Standards and Technology
Underwriters' Laboratories, Inc.
Univ. of California (Los Alamos Nat'l Lab)
U. S. Dept of the Air Force, Office of the Surgeon General
U. S. Dept of the Army, Office of the Surgeon General
U.S. Department of Energy
U. S. Department of the Navy
U. S. Dept of Health and Human Services - Public Health
Individual Members
iv
John C. Taschner
Gordon M. Lodde
John R. Dukes
Thomas F. Bresnahan
Donald A. Greschaw
William Watt (alt.)
David A. Felinski (alt.)
Gordon M. Lodde
Camden Hubbard
Stewart M. Fastman
Anthony LaMastra
Peter A. Hernandez (alt.)
Jesse Lieberman
K. Dieter Markert
Marvin M. Turkanis
R. E. Irwin
Mike Henry
Bart Lago (alt.)
Jack Fix
David Lee (alt.)
Douglas M. Eagleson
James W. Tracy (alt.)
Peter Boden
David Dini (alt.)
John C. Taschner
Don Jordan
Harris Edge
Gregory R. Komp (alt.)
Peter O'Connell
Joel Rabovsky (alt.)
David E. Farrand
William Morris (alt.)
Steven Doremus (alt.)
H. Thompson Heaton
Frank Cerra (alt.)
John H. Weiler
Contents
1. Introduction ............................................................................................................................................... 1
2. Scope ........................................................................................................................................................ 1
3. Definitions ................................................................................................................................................. 1
4. Types of Injuries........................................................................................................................................ 3
5. Dose Limits ............................................................................................................................................... 3
6. Installation and Equipment Requirements ................................................................................................ 3
6.1 Installation requirements .............................................................................................................. 3
6.2 X-ray System Classification and Requirements........................................................................... 5
7. Operating Procedure Requirements ......................................................................................................... 7
7.1 Federal, State and Local regulations and Procedures................................................................. 7
7.2 Radiation Protection Surveys and Inspection .............................................................................. 7
7.3 Normal Opertion ........................................................................................................................... 8
7.4 Repair and Alignment................................................................................................................... 8
7.5 Use of Nonstandard Accessories................................................................................................. 8
7.6 X-ray Use in Vacuum Systems .................................................................................................... 8
8. Personnel Requirements .......................................................................................................................... 9
8.1 Responsibility ............................................................................................................................... 9
8.2 Health Surveillance ...................................................................................................................... 9
8.3 Personnel Monitoring ................................................................................................................... 9
9. References.............................................................................................................................................. 10
Figures
Figure 1. Area Designations ......................................................................................................................... 4
Tables
Table 1. NCRP External Ionizing Radiation Dose Recommendations ....................................................... 13
Table 2. Transmission Through Lead of X-rays Generated at Constant Potential..................................... 13
Table 3. Thickness of lead (mm) required for a primary beam barrier located 5 cm from focal spot......... 13
Appendix
A. Detection and Measurement of Radiation from X-ray Diffraction and Fluorescence Analysis Equipment 14
v
AMERCIAN NATIONAL STANDARD
ANSI/HPS N43.2-2001
Radiation Safety for X-ray Diffraction and Fluorescence Analysis
Equipment
1.
Introduction
This standard reviews the types of injuries
resulting from accidental exposure to ionizing
radiation resulting from the operation of
analytical x-ray diffraction and fluorescence
equipment, establishes equipment design
criteria, sets up requirements for approved
operating procedures, and recommends the
establishment of health surveillance, and
personnel
monitoring
programs.
The
circumstances under which operation of
equipment must be limited to specially
designated areas equipped with radiation
barriers and warning signs are provided. Dose
limits recommended by the National Council on
Radiation Protection and Measurements are
provided for reference. A list of references to
selected articles on various aspects of radiation
safety is given, and notes on the detection and
measurement of radiation from x-ray diffraction
and fluorescence analysis equipment are
included in an appendix.
2.
Scope
This standard provides guidelines specific to the
radiation safety aspects of the design and
operation of x-ray diffraction and fluorescence
analysis equipment. It does not include electrical
safety guidelines or other safety considerations
outside the realm of radiation safety.
3.
Definitions
The definitions and terms contained in this
standard, or in other American National
Standards referred to in this document, are not
intended to embrace all legitimate meanings of
the terms. They are applicable only to the
subject treated in this standard.
ALARA. As Low As Reasonably Achievable making every reasonable effort to maintain
exposures to radiation as far below the dose
limits as practical, taking into account the state
of the technology, the economics of the
improvements in relation to the benefits, and
other societal or socioeconomic considerations.
Analytical X-ray Equipment. Laboratory
equipment utilizing x-ray radiation to analyze or
obtain information about material properties
(e.g.
surface
characteristics,
elemental
composition, material structure, etc.) using
diffraction or fluorescence techniques.
Controlled Area. A specified area to which
access is managed in order to protect personnel
from radiation.
Dose, Absorbed. The energy imparted to
matter in a volume element by ionizing radiation
divided by the mass of irradiated material in that
volume element. The unit is the Gray (Gy) and
the special unit of absorbed dose is the rad. One
Gy = 1 J/kg and one rad equals 100 ergs per
gram. (1 Gy = 100 rad.)
Dose Equivalent (H). The product of absorbed
dose, radiation weighting factor, and other
modifying factors necessary to express on a
common scale, for all ionizing radiation, the
dose incurred by exposed persons. The unit is
the Sievert (Sv) and the special unit of dose
equivalent is the rem. (1 Sv = 100 rem.)
Dose Rate, Absorbed. The absorbed dose per
unit time.
Exposure.
A measure of the ionization
produced in air by x- or gamma-radiation. This
unit is considered obsolete. It is the sum of the
electrical charges on all of the ions of one sign
produced in air when all electrons liberated by
photons in a volume element of air are
completely stopped in the air, divided by the
mass of the air in the volume element. The
special unit of exposure is the roentgen (R)
which = 2.58x10-4 Coulomb/kg.
Exposure Rate. The exposure per unit time.
Fail-safe Design. A design in which all
realistically anticipated failures of indicators or
1
ANSI/HPS N43.2-2001
safety components result in a condition in which
personnel are safe from exposure to radiation.
For example: if a light indicating "X-RAY ON"
fails, the production of x-rays shall be prevented,
or if a shutter status indicator fails, the shutter
shall close.
High Radiation Area. Any area accessible to
individuals, in which radiation could result in an
individual receiving a deep dose equivalent in
excess of 1.0 mSv (100 mrem) in any one hour
at 30 cm (1 foot) from the source or from any
surface that the radiation penetrates. Note: other
definitions of high radiation area may exist, see
Section 7.1.
Installation. A room or other space with defined
boundaries where analytical x-ray equipment is
located.
Installation Enclosure. That portion of an
installation which clearly defines the transition
from an uncontrolled to a controlled area, and
provides such shielding as may be required to
limit the dose rate in the uncontrolled area
during normal operation. For example, the walls
of a room containing an x-ray unit may be the
installation enclosure.
Normal Operation. Operation under conditions
suitable for collecting data as recommended by
a manufacturer of the x-ray system.
Recommended shielding and barriers shall be in
place.
Primary Beam. Ionizing radiation from an x-ray
tube anode or secondary target which is allowed
to pass by a direct path through an aperture in
the radiation source housing for use in
conducting x-ray measurements.
Primary Radiation. Ionizing radiation coming
by direct path from the x-ray tube anode and/or
secondary target.
Qualified Expert.
A person having the
knowledge and training necessary to measure
ionizing radiation, analyze the significance of
and evaluate the potential for health effects, and
advise regarding radiation protection as it
pertains to x-ray diffraction and fluorescence
analysis x-ray equipment. (Where guidance is
needed as to the competence of an individual to
discharge the responsibilities of a qualified
expert, it may be obtained from a national
2
certifying board or through local, state, or other
regulatory agencies.)
Qualified Operator. A person involved with the
routine operation of analytical x-ray equipment
who has had adequate instruction and training in
the operation and safety as required by the
relevant regulations, person in charge, or
supervisor of the equipment.
Quality Factor. An energy dependent
dimensionless factor by which absorbed dose is
to be multiplied by to obtain, for radiation
protection purposes, a quantity that expresses
on a common scale for all ionizing radiation, the
magnitude of radiation effects likely to be
incurred by exposed persons. The quality factor
(Q) for x-rays is 1.0. This term has been
superseded by the radiation weighting factor
(WR).
Radiation Area.
Any area accessible to
individuals, in which radiation could result in an
individual receiving a deep dose equivalent in
excess of 0.05 mSv (5 mrem) in any one hour at
30 cm (1 foot) from the source or from any
surface that the radiation penetrates. Note: other
definitions of radiation area may exist, see
Section 7.1.
Radiation Safety (or Protection) Officer. One
who has the knowledge and responsibility to
apply
appropriate
radiation
protection
regulations. He or she may be the owner or the
person in charge of the controlled area, a
qualified expert, or a technically competent
person appointed by the person in charge.
Radiation Source. An apparatus or a material
emitting or capable of emitting ionizing radiation.
Radiation Source (or X-ray Tube) Housing.
That portion of an x-ray system which contains
the x-ray tube and/or secondary target. Often
the housing contains radiation shielding material
or inherently provides shielding.
Radiation Survey.
An evaluation of the
radiation hazard in and around an installation. It
customarily includes a physical survey of the
arrangement and use of the equipment and
measurement of the exposure rates under the
full range of expected and “worst case”
operating conditions.
ANSI/HPS N43.2-2001
Radiation Weighting Factor (WR). A linearenergy-transfer dependent factor by which
absorbed doses are to be multiplied in
computing the dose equivalent. (Note: this term
was formerly known as the Quality Factor Q.)
Shall. Where "shall" is used for a provision
specified herein, that provision is intended to be
a requirement.
In cases of accidental exposure, severe burns
affecting the upper extremities of the body (e.g.
hands and fingers) are the most frequently
reported types of injury [1]. Amputation of one or
more fingers is sometimes required [2].
Exposure of the lens of the eye to large doses
can result in cataracts and other opacities [3].
Sometimes the damage does not become
apparent until years later.
Should, is Recommended. "Should" or "is
recommended" is used to indicate provisions
which are not required but which are here
recommended as good practices for many
facilities.
Section 9 provides extensive
references about health effects.
System Barrier. That portion of an x-ray
installation which clearly defines the transition
from a controlled area to a radiation area and
provides such shielding as may be required to
limit the dose rate in the controlled area during
normal operation. For example, an interlocked
enclosure immediately around the x-ray unit
could be a system barrier.
Recommendations for permissible doses of
ionizing radiation are established by the National
Council
on
Radiation
Protection
and
Measurements (NCRP), and by the International
Commission on Radiological Protection (ICRP).
Regulatory limits are established by the
Environmental Protection Agency (EPA) and
implemented
by
Nuclear
Regulatory
Commission (NRC) (for radioisotope sources),
Occupational Safety and Health Administration
(OSHA) (for machine produced radiation),
Department of Energy (DOE), and/or States.
The current NRCP recommended limits are
summarized in Table 1. Be sure to consult the
regulations governing the x-ray installation
(federal, state, local, and/or others) for dose
limits and other requirements.
Uncontrolled Area. Any area to which access
is not controlled for purposes of radiation
protection (see 6.1.3).
X-ray Accessory Apparatus. Any portion of an
x-ray installation which is external to the
radiation source housing and into which an x-ray
beam is directed making x-ray measurements or
for other uses.
X-ray Generator. That portion of an x-ray
system which provides the accelerating (high)
voltage and current for the x-ray tube.
X-ray Installation. One or more x-ray systems,
the surrounding room or controlled area, and the
installation enclosure.
X-ray System. Apparatus for generating and
using ionizing radiation, including all x-ray
accessory apparatus.
4. Types of Injuries
Analytical x-ray diffraction and fluorescence
analysis equipment have the potential to
generate high intensity ionizing radiation
literature
5. Dose Limits
The problem of correctly evaluating doses due
to intense small-area beams of low energy x-ray
photons is not trivial and results can easily be in
error by an order of magnitude. Appendix A,
Detection and Measurement of Radiation from
x-ray Diffraction and Fluorescence Analysis
Equipment, has been prepared as an aid in
avoiding some of the pitfalls.
6. Installation and Equipment
Requirements
6.1 Installation Requirements
Three types of areas within installations are
recognized in this standard: radiation area,
controlled area, and non-controlled area. The
areas, as well as the dose limits and barriers
required, are schematically illustrated in Figure
1.
3
ANSI/HPS N43.2-2001
Installation Enclosure (See 6.1.2.2)
CONTROLLED AREA
Dose equivalent greater than uncontrolled area, but less than a
radiation area.
System Barrier (See 6.1.1.3)
RADIATION AREA
Dose equivalent > 0.05 mSv (5 mrem) in any one
hour at 30 cm, but < 0.05 Sv (5000 mrem) in a year
(see 6.1.1.1)
UNCONTROLLED AREA
Dose equivalent < 0.02 mSv (2 mrem) in any one
hour and < 1 mSv (100 mrem)
in a year (see 6.1.3.1)
Fig. 1. Area Designations
Note that the establishment at all times of three
physically separate areas may not be required.
In other words, it may be possible to set up an
installation utilizing modern X-ray equipment
with enclosures so that the temporary radiation
area within the controlled area can be the same
physical space. Radiation area requirements
would have to be met when such areas
temporarily exist (e.g. enclosures open and
interlocks bypassed), and controlled area
requirements would have to be met other times.
For example, the implementation of a
"temporary radiation area" for a modern,
enclosed diffractometer during alignment might
require only a simple rope boundary with the
appropriate sign within the controlled area, and
continuous operator presence for supervision
during the period of time the radiation area
4
exists outside the confines of the enclosure. The
establishment of controlled areas must therefore
include the provision or plan for the
establishment of radiation areas when and
where they are needed.
6.1.1 Radiation Area
6.1.1.1 Designation of a radiation area. Any
area accessible to personnel in which there
exists radiation at such levels that the individual
could receive in excess of 0.05 mSv (5 mrem) in
any one hour at 30 cm (1 foot) from the source
or any surface that the radiation penetrates, and
less than 0.05 Sv (5000 mrem) in a year.
6.1.1.2 Occupancy. The occupancy in a
radiation area shall be limited so that the
ANSI/HPS N43.2-2001
accumulated dose received does not exceed
applicable regulatory limits.
6.1.1.3 System barrier. Each radiation area
shall be surrounded by a system barrier with
sufficient inherent shielding so that the dose
equivalent received by individuals in the
surrounding controlled area does not exceed
0.05 mSv (5 mrem) in any one hour at 30 cm (1
foot) from the source or any surface that the
radiation penetrates.
6.1.1.4 Caution sign. Each radiation area shall
be conspicuously posted with a sign or signs
bearing the trefoil radiation symbol and the
words:
CAUTION: RADIATION AREA
The standard colors for signs are a magenta
trefoil and wording on a yellow background.
Additional wording may be included such as
“When the Equipment Is Energized”.
6.1.1.5 Supervision. Each radiation area shall
be under the general supervision of a Radiation
Safety Officer and under continuous supervision
by an operator during operation. Note that
continuous supervision may not require
continuous personnel presence, but control over
access to the radiation area is to be maintained.
For example, continuous supervision may
involve personnel presence, door locks, entry
monitors, or other engineered solutions.
6.1.2.3 Identifying sign. Each controlled area
shall be identified by an appropriate and easily
recognizable warning sign posted at each
entrance. For example, a black and yellow sign
with the following words could be used:
Warning: X-rays In Use
Contact ______________ For Access
6.1.2.4 Supervision. Each controlled area shall
be under the general supervision of a Radiation
Safety Officer, an operator, or the person in
charge of the area.
6.1.3 Uncontrolled areas
6.1.3.1 Dose equivalent limit. The dose
equivalent
received
by
individuals
in
uncontrolled areas shall not exceed 1 mSv (100
mrem) in any year and less than 0.02 mSv (2
mrem) in any one hour.
6.2 X-ray System Classification and
Requirements
6.2.1 Classification.
6.2.1.1 General. X-ray systems for certain
specific applications can be designed so all
possible x-ray beam paths are fully enclosed.
However, operational requirements such as:
(a)
6.1.2 Controlled Area
(b)
6.1.2.1 Designation of a controlled area. Any
area in which the dose equivalent received by
individuals may exceed 1 mSv (100 mrem) in
any year, but does not exceed the levels that
would require it to be designated a radiation
area (see 6.1.1.1), shall be designated a
controlled area. Access to controlled areas is
managed in order to protect personnel from
occupational radiation exposure.
(c)
6.1.2.2 Installation enclosure. Each controlled
area shall be visibly separated from adjacent
uncontrolled areas by an installation enclosure
so that the dose equivalent received by
individuals in the uncontrolled areas does not
exceed 1 mSv (100 mrem) in any year. This may
be accomplished by the use of shielding,
distance, or other means.
frequent changes of attachments and
configuration;
a need for making adjustments with the
x-ray beam on; and
motion of specimen and detector over
wide angular limits;
occasionally, but not necessarily, make the use
of a fully enclosed system during normal
operation impractical.
For the purpose of this standard two classes of
x-ray systems are recognized.
They are
designated Enclosed Beam X-ray Systems and
Open Beam X-ray Systems.
6.2.1.2 Enclosed beam x-ray system. An
enclosed beam x-ray system is one in which all
possible x-ray paths are fully enclosed
according to the requirements of section 6.2.2.3.
For example, the use of interlocked beam pipes
or tubes or an interlocked enclosure around the
whole x-ray system may qualify the system as
5
ANSI/HPS N43.2-2001
an enclosed beam system. However, enclosed
beam systems become open beam systems
during the period when interlocks are defeated.
6.2.1.3 Open beam x-ray system. An x-ray
system that does not comply with all of the
requirements of section 6.2.2.3 shall be
classified as an open beam x-ray system.
6.2.2.1.4 Each shutter shall be provided with a
“shutter open” indication (e.g. warning light or
device) of fail-safe design. The indicator shall
activate when the “shutter open” signal is
initiated. (Consideration should be given to the
use of materials other than lead for shutters
(e.g. tantalum, tungsten, etc.) to avoid corrosion
that high radiation levels can produce and may
cause shutter operation to fail.)
6.2.2 Requirements
6.2.2.1 General requirements for all x-ray
systems covered by this standard.
6.2.2.1.1 The dose due to unwanted, stray, or
anticipated accidental scatter and leakage
radiation from components such as high voltage
rectifiers shall not exceed 0.1 mSv (10 mrem) in
a week in any accessible region 5 cm from the
outside surface of the generator cabinet.
Assuming that an individual may be in the
vicinity of the equipment while it is operating for
as long as 40 hours per week, the dose rate
should not exceed 0.0025 mSv/hr (0.25
mrem/hr). (Note: the applicable regulations may
vary, see Section 7.1.)
6.2.2.1.2 The x-ray accessory apparatus shall
include a beam stop, trap or other barrier with
sufficient shielding so that the dose rate due to
the transmitted primary beam does not exceed
0.0025 mSv/hr (0.25 mrem/hr) under normal
operating conditions. Shielding information for
lead is presented in Table 2, which can be used
in determining the amount of shielding required.
Table 3 presents lead shielding information
found in the first edition of this standard
(minimum lead thickness for the tube maximum
rated anode current and potential).
6.2.2.1.3 Warning lights or devices of failsafe
design labeled with the words "X-RAYS ON", or
other words having similar meaning, shall be
located:
6.2.2.1.5 A label bearing the conventional
radiation symbol and the words, CAUTION:
THIS EQUIPMENT PRODUCES X-RAYS
WHEN ENERGIZED, or other words having
similar meaning, shall be attached near any
switch which energizes an x-ray tube. Additional
wording should include: TO BE OPERATED
ONLY BY QUALIFIED PERSONNEL.
6.2.2.1.6 Systems that contain an x-ray tube
shall be equipped with an interlock that shuts off
the high voltage to the tube if the tube is
removed from the radiation source housing or if
the housing is disassembled.
6.2.2.1.7 Normal operating and alignment
procedures shall be documented by the
manufacturer of the x-ray system. If the radiation
source housing and/or x-ray accessory
apparatus are not compatible (i.e. nonstandard)
components
supplied
by
the
same
manufacturer, procedures shall be documented
by the person in charge of the use of the system
and reviewed by the Radiation Safety Officer.
6.2.2.1.8 Normal operating procedures shall be
such that a qualified operator following
instructions will not receive in any one hour a
dose equivalent in excess of 0.25 mSv (25
mrem) to the extremities or 0.025 mSv (2.5
mrem) to the whole body.
near any switch which activates the high
voltage to energize an x-ray tube;
in a conspicuous location near the
radiation source housing and radiation
beam(s) and visible from all instrument
access areas.
6.2.2.1.9 Alignment procedures should be such
that a qualified worker aware of the radiation
hazards will not receive in any one hour a dose
equivalent in excess of 0.25 mSv (25 mrem) to
the extremities or 0.025 mSv (2.5 mrem) to the
whole body while following these instructions. If
either of these dose rates is likely to be
exceeded, a warning shall be included in the
alignment instructions.
Such lights or devices shall activate when the xray tube is energized.
6.2.2.1.10 The use of an area radiation monitor
is discussed in Section 7.2.2.
(a)
(b)
6
ANSI/HPS N43.2-2001
6.2.2.2 Requirements for an open beam x-ray
system in addition to general requirements
in 6.2.2.1.
6.2.2.2.1 Radiation levels external to the x-ray
tube housing with all shutters closed shall not
exceed 0.025 mSv/hr (2.5 mrem/hr) as
measured at 5 cm from the surface of the
housing within which an x-ray tube is operating
at full rated power at maximum rated
accelerating potential.
6.2.2.2.2 Each port of the radiation source
housing shall be provided with a beam shutter
interlocked with the x-ray accessory apparatus
coupling, or collimator, in such a way that the
port will be open only when the collimator or
coupling is in place. Shutters at unused ports
shall be secured to prevent casual opening.
6.2.2.2.3 It is strongly recommended that a
guard (e.g. beam tubes) or interlock which
prevents entry of any part of the body into the
primary beam path should be utilized when
practical.
6.2.2.2.4 Radiation dose levels in the vicinity of
controls and adjustments of the x-ray accessory
apparatus used during normal operation shall
not exceed 0.25 mSv/hr (25 mrem/hr) to the
extremities or 0.025 mSv/hr (2.5 mrem/hr) to the
whole body.
6.2.2.2.5 A system barrier shall be provided to
meet the requirements of 6.1.1.3.
6.2.2.3 Requirements for an enclosed beam
x-ray system in addition to general
requirements in 6.2.2.1.
6.2.2.3.1 The radiation source, beam paths,
sample, detector and/or other devices (e.g.
analyzing crystal, filters, etc.) shall be enclosed
in a chamber, coupled chambers, beam pipes,
whole system enclosure, etc. that cannot be
entered by any part of the body during normal
operation.
6.2.2.3.2 The inherent shielding of the
chamber/enclosure walls shall be sufficient to
limit the dose rate in all regions 5 cm from its
outer surface to 0.0025 mSv/hr (0.25 mrem/hr)
during normal operation.
6.2.2.3.3 The system enclosure, sample
chamber, etc. closure shall be interlocked with
the x-ray tube high voltage supply and/or a
shutter in the primary beam so that no x-ray
beam can enter the sample chamber while it is
open unless the interlock has been consciously
and deliberately defeated.
6.2.2.3.4 The interlock required by section
6.2.2.3.3 shall be of fail-safe design.
6.2.2.3.5 If there is more than one port in the
radiation source housing or more than one
radiation source, all requirements under 6.2.2.3
must satisfied for each port in every source
housing associated with the system.
7. Operating Procedure
Requirements
7.1
Federal, State, and Local Regulations
and Procedures
7.1.1 Installations may be subject to federal,
state and local regulations that are different than
those provided here, and may involve
registration, licensing, and compliance with
specific rules. Some other topics of regulatory
interest may include: licensing or registration,
operator training, radiation area definition,
posting and labeling requirements, reporting,
etc. In addition, the institution, installation
supervisor
or
operator
may
impose
administrative requirements. The Radiation
Safety Officer, person in charge of the
installation, and all equipment operators shall be
familiar with applicable operating procedures
and regulations governing the x-ray installation.
7.2 Radiation Protection Surveys and
Inspection
7.2.1 A radiation survey and inspection and test
of protective devices shall be made before a
new installation is placed in routine operation,
and whenever changes are made that could
adversely affect radiation protection (e.g.
maintenance, relocation of equipment, radiation
shielding modifications, etc.) In addition, periodic
surveys should be performed at least once
every 12 months. Guidance for performing
surveys can be found in: American National
Standard for General Radiation Safety Installations Using Non-Medical X-ray and
7
ANSI/HPS N43.2-2001
Sealed Gamma-Ray Sources, Energies up to 10
MeV (ANSI N43.3-1993)[4].
7.2.2 The need for active or passive fail-safe
radiation area monitors should be evaluated on
a case by case basis. The proper placement of
detectors and integration into the equipment
interlock circuitry can provide enhanced safety.
When appropriate, the use of these devices is
highly
recommended
and
should
be
implemented.
7.4.6 If an alignment procedure results in
increasing the dose rate in any area so that the
usual designation of that area no longer applies,
the person in charge shall erect temporary
barriers and warning signs as required to create
a new controlled area and shall keep the area
under surveillance until normal operation has
been restored.
7.3 Normal Operation
7.4.7 Repairs should be carried out on an
uncluttered surface so that any pieces left out
during reassembly will be conspicuous.
7.3.1 Only those procedures specified by the
manufacturer of the x-ray system should be
used, unless an alternate procedure has been
documented by the person in charge and
approved by the Radiation Safety Officer.
Variations from approved radiation safety and
operating procedures shall be reviewed and
approved by the person in charge and the
Radiation Safety Officer.
7.4.8 After reassembly, the x-ray system shall
be checked by the Radiation Safety Officer or
other person in charge. Particular attention
should be given to the alignment of shielding,
shutters and collimators. Lead parts should be
inspected for damage, distortion, or corrosion
which could result in radiation leakage and
should be mounted in such a way that they will
not cold-flow because of their own weight.
7.4 Repair and Alignment
7.5 Use of Nonstandard Accessories
7.4.1 Most severe injuries have occurred during
non-routine operations such as repair and
alignment [5]. It is recommended that the
Radiation Safety Officer, or other person in
charge of an x-ray installation be advised when
these operations are to be undertaken.
7.5.1 Any device for use with an x-ray tube shall
be regarded as a nonstandard accessory unless
it is a compatible component manufactured
specifically to fit the radiation source housing
used. It is recommended that no new accessory
be aligned or operated until the manufacturer’s
procedures have been reviewed by the
operator(s) and the person in charge (e.g.
supervisor), and a radiation survey has been
carried out.
7.4.2 No operation involving removal of cover
shielding materials or tube housings or
modifications to shutters, collimators or beam
stops shall be performed without ascertaining
that the tube is off and will remain off until safe
conditions have be restored. The x-ray source
power switch, rather than safety interlocks, shall
be used for routine shutdown in preparation for
repairs.
7.4.3 No x-ray tube shall be operated without a
suitably shielded housing to restrict the primary
or secondary radiation to a well defined beam.
7.5.2 Nonstandard accessories shall not be
aligned or operated by the equipment users until
procedures have been approved and a radiation
survey carried out. Manufacturer's personnel
performing work on nonstandard accessories
(e.g. installation, maintenance, etc.) shall follow
safety procedures specific to this type of
operation.
7.6 X-ray Use in Vacuum Systems
7.4.4 Alignment procedures recommended by
manufacturer of the x-ray system shall be used
when available.
7.4.5 Special alignment procedures shall not be
used unless approved by the Radiation Safety
Officer and the person in charge of the analytical
x-ray installation.
8
7.6.1 Certain types of x-ray surface analysis
(e.g. XPS or x-ray photospectrometry) must be
performed in a vacuum. Typically an x-ray tube
is installed into one or more penetrations of the
vacuum system and can be adjusted for sourceto-sample distance. The vacuum system also
typically contains multiple view ports with high
vacuum windows for observing the sample
visually.
ANSI/HPS N43.2-2001
7.6.2 The location of x-ray tubes in relation to
windows shall be considered carefully. Any
window within the radiation emission cone of the
source may create a local radiation or high
radiation area. If the x-ray source is adjustable,
efforts shall be taken to ensure safe operation
over the full range of adjustment.
7.6.3 If windows cannot be positioned to prevent
radiation emission because of technical or
operational reasons, lead glass covers or similar
material may be used to reduce radiation levels.
Covers shall be affixed so they cannot be
accidentally knocked aside. A survey shall be
performed to verify the effectiveness of the
covers
under
all
anticipated
operating
conditions.
7.6.4 If the entire system, including x-ray tube, is
under one contiguous vacuum, and radiation
leakage is less than 0.0025 mSv/hr (0.25
mrem/hr) at 5 cm, and a change in any part of
the system will not increase the radiation level,
then the system shall be considered to be an
enclosed beam system.
control. They shall also be responsible for
carrying out all specified instructions and
maintaining prescribed operating conditions.
Lastly, they should ensure that adequate
medical surveillance and radiation monitoring of
personnel are carried out.
8.1.2 Each worker shall, upon the instruction of
a qualified expert or responsible supervisor,
follow the recommendations and instructions
that have been drawn up in the interest of
radiation protection.
8.1.3 Each worker shall use the protective
devices and radiation dosimetry provided.
8.1.4 Each worker shall bring to the attention of
those in charge any defect or deficiency in
radiation protection devices and procedures.
8.1.5 Female radiation workers who become
pregnant should refer to the applicable
regulations
concerning
declaration
of
pregnancy.
8.2 Health Surveillance
8. Personnel Requirements
It should be stressed that recommendations and
radiation safety procedures with respect to the
installation and operation of the equipment are
not in themselves sufficient to guarantee
adequate protection. Such protection depends
largely on the expert knowledge of the staff and
on their cooperation in carrying out the
instructions prepared by their supervisor in the
interests of radiation protection. All personnel
involved with operation of equipment shall have
adequate instruction and safety training as
required by the regulations, person in charge, or
supervisor of the installation.
Two videotapes that may assist in radiation
safety training are cited in Section 9.2.
8.1 Responsibility
8.1.1 The owner or the person in charge of a
controlled area shall be responsible for the
evaluation of needs and the formation of policy
with respect to radiation protection. They shall
be responsible for the working conditions and for
the instruction of all persons working in the area
regarding radiation hazards and methods of
8.2.1 The need for periodic medical examination
shall be determined by the equipment operator's
management, the Radiation Safety Officer and
the operator's medical personnel. If performed,
the exam should pay particular attention to the
eyes and to the skin of the hands and the face.
8.3 Personnel Monitoring
8.3.1 Doses to personnel received as a result of
occupational
exposures
should
be
systematically evaluated with appropriate
radiation measuring instruments (see Appendix
A) to ensure that regulatory limits are not
exceeded.
8.3.2 The deficiencies of personnel monitoring
devices at low x-ray energy and their use are
well known. However, according to a report [6]
on seventeen cases of accidental exposure, the
personnel dosimeter gave the first indication that
an accident had occurred in five of the cases.
The use of suitable personnel monitoring
devices is recommended provided the response
of the personnel dosimeter to low energy x-rays
is known and documented. Whole body and
extremity dosimetry should be used by any
operator who uses open beam systems,
performs alignments with x-ray beam on, or
9
ANSI/HPS N43.2-2001
otherwise bypasses an interlock with the x-ray
tube energized. The operator's management
and Radiation Safety Officer shall determine the
need for personnel radiation monitoring based
on regulatory requirements and exposure
potential.
9. References
9.1 The following publications are referred to in
this standard and the appendix. Although some
may be hard to locate, they are included here as
sources of information from the original
standard. Additional references are listed in
Section 9.2.
1. Howley, J.R. and Robbins, C., Radiation
hazards from x-ray diffraction equipment.
Radiological Health Data and Reports vol. 8,
no. 5, (May 1967), pp. 245-249.
2. A Summary of Industrial Accidents in
USAEC Facilities, 1965-1966. United States
Atomic Energy Commission, Division of
Technical Information, Oak Ridge, TN
37830, (TID-5360-Supplement 6), pp. 4 and
6.
3. Merriam, G.R. and Focht, E.F., Clinical
study of radiation cataracts and relationship
to dose. The American Journal of
Roentgenology, Radium Therapy and
Nuclear Medicine, vol. 77, May 1957, pp.
759-785.
4. American National Standard for General
Radiation Safety - Installations Using NonMedical X-ray and Sealed Gamma-Ray
Sources, Energies Up To 10 MeV, American
National Standard N43.3-1993.
5. Kaelble, E.F. (Editor), Handbook of X-rays.
New York: McGraw-Hill Book Co., (1967).
6. Conference
on
Detection
and
Measurements of X-Radiation from Color
Television
Receivers.
United
States
Department of Health, Education and
Welfare;
and
Electronic
Industries
Association; Bureau of Radiological Health,
Washington, D.C. 20850, March 28-29,
1968 (Technical Papers).
7. Clark, G.L. (Editor), The Encyclopedia of Xrays and Gamma Rays. New York: Reinhold
Publishing Corporation, 1963.
9.2 The following publications are not cited in
this standard, but are included as additional
sources of information.
10
1. Video: Double Edged Sword, National
Audiovisual Center (GSA), Washington,
D.C.
2. Video:
The
Invisible
Partner,
International Center for Diffraction Data,
12 Campus Blvd., Newton Square, PA,
19073-3273, (610) 325-9814, Catalog
Number ALCOA-VHS.
3. Computer-based training: Working
Safely with X-rays, International Center
for Diffraction Data, 12 Campus Blvd.,
Newton Square, PA, 19073-3273, (610)
325-9814, Catalog Number ALCOACBT. A printed workbook version of the
computer course is also available as
Catalog Number ALCOA-SWB.
4. Basic Radiation Protection Criteria.
National Council on Radiation Protection
and Measurements. P.O. Box 30175,
Washington, D.C. 20014, 1971 (NCRP
Report 39).
5. Lindell, B. Occupational hazards in x-ray
analytical work. Health Physics, vol. 15,
no. 6, December 1968, pp. 481-486.
6. Lubenau, J.O., Davis, J.S., McDonald,
D.J., and Gerusky, T.M., Analytical x-ray
hazards: a continuing problem. Health
Physics, vol. 16, June 1969, pp. 739746.
7. Attix, F.H. and Roesch, W.C. (Editors).
Radiation Dosimetry, vol. 1 - 1968
(Fundamentals),
vol.
2
- 1966
(Instrumentation) and vol. 3 - 1969
(Sources, Fields, Measurements and
Applications). New York: Academic
Press.
8. Accident
Prevention
Manual
for
Industrial Operations. Chicago: National
Safety Council, 1964, (5th Edition), Ch.
42, pp. 33-35.
9. Beu,
K.E.
(Chairman).
Safety
Considerations in the Design of X-ray
Tube and Collimator Couplings on X-ray
Diffraction
Equipment.
American
Crystallographic Association, Polycrystal
Book Service, P.O. Box 11567,
Pittsburgh, PA, 15238, 1962, (Apparatus
and Standards Committee Report No.
1).
10. Report of Committee III on Protection
Against X-rays Up to Energies of 3 MeV
and Beta- and Gamma-Rays from
Sealed Sources. London: Pergamon
Press (for the International Commission
on Radiological Protection), 1960,
(ICRP Publication 3), pp. 12-13.
ANSI/HPS N43.2-2001
11. Cook, J.E. and Oosterkamp, W.J.
Protection against radiation injury.
International
Tables
for
X-ray
Crystallography, Birmingham, England:
The Kenosha Press, 1962, (vol. III,
section 6), pp. 333-338.
12. Radiation hazards associated with x-ray
diffraction
techniques.
Acta
Crystallographica, vol. 16, 1963, pp.
324-328.
13. Klug, H.P. and Alexander, L.E., X-ray
Diffraction
Procedures
for
Polycrystalline
and
Amorphous
Materials. New York: John Wiley &
Sons, 1974, 2nd edition, pp. 58-60, 861862.
14. Rudman, R. X-ray diffraction analysis,
part one - safety and generators.
Journal of Chemical Education, vol. 44,
January 1967, (pp. A7-A43).
15. Radiation Safety in X-ray Diffraction and
Spectroscopy.
Proceedings
of
a
conference held January 6-7, 1970 at
the
University
of
Pennsylvania,
Philadelphia,
PA.
United
States
Department of Health, Education and
Welfare, Bureau of Radiological Health,
Rockville,
MD
20852
(DHEW
Publication No. FDA 72-8009 BRH/DEP
72-3.
16. Radiological Protection in the Use of Xray Crystallographic and Spectrometric
Equipment. Department of Employment
and
Productivity,
Advisory
and
Information Unit, Baynards House, 1
Chepstow Place, London, W.2.,1969.
17. Radiation Protection in Educational
Institutions.
National
Council
on
Radiation
Protection
and
Measurements, 7910 Woodmont Ave.,
Suite 1016, Washington, D.C., 20014,
1966, (NCRP Report 32).
18. Jenkins, R. and Haas, D.J., Hazards in
the
Use
of
X-ray
Analytical
Instrumentation. X-ray Spectrometry,
vol. 2, 1973, pp. 135-141.
19. Jenkins, R. and Haas, D.J., Incidence
Detection and Monitoring of Radiation
from X-ray Analytical Instrumentation. Xray Spectrometry, vol. 4, 1975, pp. 3-42.
20. A Guide to Radiation Protection in the
Use of X-ray Optics Equipment,
Monograph No. 15, Science Reviews
Ltd., ISSN 0141-7568, ISBN 0-90692752-4.
21. Martin, E.B.M, A Guide to the Safe Use
of X-ray Diffraction and Spectrometry
Equipment,
Monograph
No.
8,
Occupational Hygiene, 1983, ISSN
0141-7568;8, ISBN 0-905927-11-7.
22. Zhao, S., Kramer, M., and Hohlfeld, K.
The yield from x-ray tubes in terms of
ambient dose equivalent. Radiation
Protection Dosimetry, vol. 51, no. 4,
1994, pp. 297-300.
23. Hughes, W., An installation to avoid
direct radiation hazards in x-ray
analysis.
Journal
of
Scientific
Instruments, vol. 39, 1962, pp. 564-565.
24. Hughes, W., Simple shutter-closing
device for x-ray tubes. Journal of
Scientific Instruments, vol. 39, 1962.
25. Hughes, W. and Taylor, C.A., Safe
universal mounting and alignment
system for x-ray goniometers. Journal of
Scientific Instruments, vol. 38, 1961.
26. Hallewell, V.A., Murphy, R.J., Pauling,
P.J.
and
Robertson,
G.B.,
A
comprehensive safety shutter and
collimator coupling for the Philips x-ray
tube shield PW 1016. Journal of
Scientific Instruments, vol. 42, 1965.
27. Kennard, O., Martin, A.J.P., and
Woodget, L., Labyrinth radiation trap for
use with standard x-ray diffraction
equipment.
Journal
of
Scientific
Instruments, vol. 36, 1959.
28. Lee, J.D. and Oldham, G., Safety device
for x-ray tubes and goniometers. Journal
of Scientific Instruments, vol. 43, 1966.
29. Sutherland, H.H., Design of a safety
system for x-ray generators, Journal of
Scientific Instruments, vol. 44, 1967.
30. Abrahams, S.C. and Blackmore, W.R.,
A shielding device for x-ray diffraction
cameras.
Review
of
Scientific
Instruments, vol. 24, 1953, p. 885.
31. Trout, E.D., A suggestion for radiation
safety in the use of x-ray diffraction
equipment. Health Physics, vol. 22,
1972, p. 94.
32. Krizek, T.J. and Ariyan, S., Severe
acute radiation injuries of the hands.
Plastic and Reconstructive Surgery, vol.
51, 1973, pp. 14-21.
33. Weigensburg, I.J., Asbury, C.W., and
Feldman, A., Injury due to accidental
exposure to x-rays from an x-ray
fluorescence
spectrometer.
Health
Physics, vol. 39, 1980, p. 237-241.
11
ANSI/HPS N43.2-2001
34. Weeks, J.L., Radiation exposure in the
laboratory. Journal of the Society of
Occupational Medicine, vol. 26, 1976,
pp. 9-12.
35. McLaughlin, J.E. and Blatz, H., Potential
radiation hazards in the use of x-ray
diffraction
equipment.
American
Industrial
Hygiene
Association
Quarterly, vol. 16, 1955, pp. 108-112.
36. Burdick,
K.G.
and
Miraldi,
F.,
Radiodermatitis due to exposure in
industry. Journal of the American
Medical Association, vol. 188, no. 6,
1964, pp. 235-236.
37. Berger, M.E., Hurtado, R., Dunlap, J.,
Mutchinick, O., Velasco, M.G., Tostado,
R.A., Valenzuela, J., and Ricks, R.C.,
Accidental radiation injury to the hand:
anatomical
and
physiological
considerations. Health Physics, vol. 72,
no. 3, 1997, pp. 343-347.
38. Leenhouts, H.P., Another failure of a
commercial x-ray shutter system. Health
Physics, vol. 22, 1972, pp. 413-414.
39. LaMastra, A. and McDonald, D.J.,
Report of a failure of a commercial x-ray
diffraction shutter status system. Health
Physics, vol. 20, 1971, pp. 639-640.
40. Watrous, R.M., Hodges, H.W., and
McAndrew, M.J., Radiation burns from
diffraction
apparatus
simulating
infections. Journal of the American
Medical Association, vol. 152, no. 6,
1953, pp. 513-514.
41. Steidley, K.D., Stabile, R.J., and
Sanfilippo, L.J., A case history of severe
radiation burns from 50 kVC x-rays.
Health Physics, vol. 40, 1981, pp. 399405.
42. Robertson, J.K., Radiation hazards from
x-ray diffraction equipment. New
Zealand Journal of Science, vol. 11,
1968, pp. 433-439.
43. Bain, J.T.B., MacCabe, J.E., X-ray
burns in industry. British Medical
Journal, vol. 1, 1962, pp. 1476-1477.
44. Acute accidental superficial x-ray burns.
British Journal of Dermatology, vol. 74,
1962, pp. 392-402.
45. Day, F.H., Thimble chamber calibration
on soft x-rays. U.S. Department of
Commerce,
National
Bureau
of
Standards, research paper RP1926, vol.
41, October 1948.
46. Taylor, L.S. and Stoneburner, C.F., The
measurement of low-voltage x-ray
12
47.
48.
49.
50.
51.
52.
53.
54.
55.
56.
intensities. Bureau of Standards Journal
of Research, vol. 9, no. 1, 1932, pp.
769-780.
Quimby, E.H. and Focht, E.F., Dosage
measurements in contact roentgen
therapy.
American
Journal
of
Roentgenology and Radium Therapy,
vol. 50, no. 5, 1943, pp. 653-668.
Desjardins, A.U., Action of roentgen
rays and radium on the gastrointestinal
tract.
American
Journal
of
Roentgenology and Radium Therapy,
vol. XXVI, 1931, pp. 151-190.
Victoreen, J.A., Atlee, Z.J., and Trout,
E.D., The behavior of thimble chambers
when used for the measurement of very
soft radiation. American Journal of
Roentgenology and Radium Therapy,
vol. 53, no. 4, 1945, pp. 391-394.
McBride, W.W. and Lieben, J.,
Radiodermatitis
from
diffraction
apparatus. Archives of Environmental
Health, vol. 4, 1962, pp. 73-77.
Burgess, P.H., The development and
testing of a new technique for the
measurement of dose rates in the main
beam
of
crystallographic
x-ray
equipment.
Radiation
Protection
Dosimetry, vol. 16, no. 3, 1986, pp. 247251.
Conference
of Radiation Control
Program
Directors
(CRCPD),
Suggested State Regulations for Control
of Radiation - Part H - Radiation Safety
Requirements for Analytical X-ray
Equipment. CRCPD, Inc., 205 Capital
Ave.,
Frankfort,
KY
40601.
(http://www.crcpd.org/)
Dax,
M.,
X-ray
film
thickness
measurements.
Semiconductor
International, August 1996, pp. 91-100.
Benzel, W. and Wallace, P. (editors), Xray safety workshop, 43rd Annual
Denver X-ray Conference, August 1-5,
1994,
Steamboat
Springs,
CO.,
University of Denver Department of
Engineering and International Center for
Diffraction Data.
Zhao, Y., Che, R., Tang, E., and Xian,
D., High pressure x-ray diffraction
station at the Beijing synchrotron
radiation
facility.
High
Pressure
Research, vol. 8, 1992, pp. 711-713.
Maharaj, H.P., Safety considerations
and recommendations for analytical xray devices from a review of survey
ANSI/HPS N43.2-2001
57.
58.
59.
60.
61.
62.
63.
data. Health Physics, vol. 66, no. 4,
1994, pp. 463-471.
Olsher, R., The Los Alamos Scientific
Laboratory X-ray Survey Manual, Doc.
No. LA-8246-M, 1983.
Angilello, J. and Linnartz, H., X-ray
diffraction safety improvements at IBM
Research Lab, Report RC-5505, IBM
Thomas J. Watson Research Center,
Yorktown Heights, NY, 10598, 1975.
Masse, F.X., Coutu-Reilly, J., Galanek,
M., and Ducatman, A., The need for
additional warning in x-ray diffraction
equipment: a shutter failure incident.
Health Physics, vol. 58, no. 2, 1990, p.
219.
Blatz, H., Laboratory support for an xray inspection program. Health Physics,
vol. 10, 1964, pp. 643-649.
Moore, M.J. and Sorensen, D.B.,
Radiation alarm system for scattered
radiation. Health Physics, vol. 15, 1968,
pp. 362-363.
Murphy, E.G. and Stewart, H.F.,
Warning chimes for experimental x-ray
machine. Health Physics, vol. 14, 1968,
pp. 517-518.
Pipes, E.W., A voltage-sensing device
for monitoring x-rays. Health Physics,
vol. 13, 1967, pp. 1351-1352.
13
ANSI/HPS N43.2-2001
Table 1.
NCRP External Ionizing Radiation Dose Recommendations
Whole body (head, trunk of body, gonads)
0.05 Sv/yr (5 rem/yr)
Lens of the eye
0.15 Sv/yr (15 rem/yr)
Extremities (hands / forearms, feet / ankles)
0.5 Sv/yr (50 rem/yr)
Skin of whole body
0.5 Sv/yr (50 rem/yr)
Embryo / fetus of “declared” pregnant worker
0.005 Sv (0.5 rem) for the entire gestation period;
0.0005 Sv (0.05 rem) per month
Non-occupational*
0.001 Sv/yr (0.1 rem/yr)
*Dose received by members of the public. Consult the applicable regulations for a more complete
definition.
Table 2.
Transmission Through Lead of X-rays Generated at Constant Potential*
Thickness
Transmission at:
(mm)
20 kV
30 kV
40 kV
50 kV
75 kV
100 kV
0.0635
5.18E-05
3.88E-04
2.74E-03
0.127
1.78E-07
6.05E-06
2.64E-04
0.1905
4.52E-07
4.52E-05
0.25
2.70E-03
3.20E-02
7.60E-02
0.254
3.17E-07
1.06E-05
0.5
9.00E-05
5.30E-03
2.40E-02
1
~ 1 E-6
3.30E-04
4.10E-03
2
~ 1 E-11
5.70E-06
2.30E-04
3
1.70E-05
4
1.40E-06
*Source: Martin, E.B.M., A Guide to the Safe Use of X-ray Diffraction and Spectrometry Equipment,
Monograph No. 8, Occupational Hygiene, 1983, ISSN 0141-7568;8, ISBN 0-905927-11-7, pg.57.
Table 3.
Thickness of lead (mm) required for a primary beam barrier located 5 cm from focal spot*
Anode Current
High Voltage
mA
50 kVp
70 kVp
100 kVp
20
1.5
5.6
7.7
40
1.6
5.8
7.9
80
1.6
5.9
---160
1.7
------*Source: ANSI N43.2-1977.
14
ANSI/HPS N43.2-2001
Appendix A
Detection and Measurement of Radiation from X-ray Diffraction and Fluorescence
Analysis Equipment
(This Appendix is not a part of this standard, but is included for information purposes only.)
A.l Nature of the Radiation
A.1.1 Typical acceleration potentials are 25 to 50 kVp for diffraction tubes and 25 to 100 kVp for those
used in fluorescent analysis ([7], p. 1096). The upper limit for the energy of x-ray photons is, therefore,
50 or 100 keV. There is no theoretical lower limit to the energy of the photons in the radiation spectrum,
but the intensity below about 5 keV is low and the x-rays are readily attenuated. The spectrum can be
assumed to extend from 5 to 100 keV with an intensity maximum in the range 20 to 30 keV depending on
the accelerating potential.
A.1.2 Superimposed on this spectrum are the lines of the characteristic x-ray photons of the anode.
These constitute less than half of the output in the case of tubes used for diffraction but may be the bulk
of the fluorescence x-rays when secondary targets are employed. The energies involved are generally in
the range 5.4 to 17.5 keV for diffraction.
A.1.3 In order to measure the dose from both the bremsstrahlung spectrum and the characteristic
spectrum, a radiation survey device with known energy absorption characteristics throughout the 5 to 100
keV energy range should be used.
A.2 Sources of Radiation
A.2.1 Hazardous radiation may come from the following sources ([6], p. 6-2):
1.
2.
3.
4.
5.
6.
The primary beam.
Leakage or scatter of the primary beam through cracks in ill fitting or defective equipment.
Penetration of the primary beam through the tube housing, shutters or diffraction apparatus.
Secondary scatter emission from the sample or other material exposed to the primary beam.
Diffracted or fluorescence x-rays.
Radiation generated by vacuum tube rectifiers in the high voltage power supply.
A.2.2 The primary beam is most hazardous because of the extremely high dose rates. Exposure rates of
4x103 Gy/min (4x105 rad/min) at the port have been reported for ordinary diffraction tubes [1].
A.2.3 The leakage or scatter of the primary beam through apertures in ill fitting or defective equipment
can produce very high intensity beams of possibly small and irregular cross section.
A.2.4 Diffracted beams also tend to be small and irregular in shape. They may be directed at almost any
angle with respect to the main beam, and occasionally involve dose rates of the order of 0.8 Gy/hr (80
rad/hr).
A.2.5 The hazard resulting from penetration of the useful beam through shutters or the x-ray tube housing
is slight in well designed equipment. Adequate shielding is easily attained at the energies commonly
used for diffraction and fluorescence analysis.
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ANSI/HPS N43.2-2001
A.2.6 Adventitious (i.e. incidental) radiation from the high voltage power supply may result from
malfunctioning vacuum tube rectifiers. The effective potential is twice the potential applied to the x-ray
tube, and the radiation is very penetrating. This condition can arise at any time and the only effective
countermeasure is to shield the assembly that contains the rectifiers and check at least twice a year for
radiation leakage.
A.2.7 In addition to the six sources of radiation listed above, large quantities of primary radiation may be
accidentally released as the result of removal of parts of the system or the improper installation of
accessories. Immediate detection of the condition is the only effective way to reduce the exposure of
personnel. In installations where disassembly of shielding components and changes of accessories occur
frequently, consideration should be given to the use of an area monitor having audible and visible
indicators that are actuated when a preselected radiation level has been exceeded.
A.3 Choosing a Radiation Survey Method
A.3.1 One of the major problems in carrying out a radiation survey program is to obtain a detector with
good energy independence at very low photon energies ([7], p. 105-127). The type of instrument
generally recommended for accurate measurements of dose rates at low x-ray energies is an ionization
chamber with a thin window (e.g. ~1.0 mg/cm2 plastic or low atomic number material). Special calibration
corrections may be required at low x-ray photon energies (< 20 keV), and these energies are an
important part of the spectrum when iron, chromium, or copper anodes, targets, or filters are used.
A.3.2 In general, for the accuracy required in radiation protection surveys, calibration corrections may not
be necessary so long as the whole sensitive area of the detector is uniformly irradiated. In this
connection, the relatively large size of many ionization chambers (3.5 inch diameter for a typical survey
instrument) must be listed as a disadvantage of this type of instrument because of the resulting low
sensitivity when used in searching for beams of small cross section.
A.3.3 Instruments which detect x-ray photons (e.g. thin window Geiger-Muller (GM) detectors, thin NaI
scintillation detectors, Si(Li), plastic scintillators with thin windows, and other solid-state detectors like
TLDs, etc.) offer high sensitivity in a small cross section, and are generally superior to ionization
chambers for detecting beams of small cross section. However, the response is generally very energy
dependent and the readings must be interpreted with care. Readings obtained with a GM counter in the
low energy x-ray range are particularly unreliable without knowing the detector’s energy response or
having actual calibration data. On the other hand, thin window GM detectors are very useful in locating
small beams so they may be mechanically eliminated by adding shields or correcting unsatisfactory
assemblies. The use of these simpler counters for this purpose is acceptable. Modern plastic scintillators,
TLDs, and other detectors can also offer high sensitivity, small diameters, and good response linearity.
However, special consideration is needed with regard to proper calibration and detector placement.
A.4 Evaluating the Dose Rate Due to Small Beams
A.4.1 Generally, knowledge of the dose rate from a direct X-ray beam (e.g. primary, diffracted, or
fluorescence beam) is not needed. One case where such information is needed is in accident
investigations. The techniques described here should not be construed as part of any normal operating or
survey procedure.
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ANSI/HPS N43.2-2001
A.4.2 Instrumental methods. An instrument which is calibrated for radiation that uniformly exposes the
entire active detector volume will give an erroneously low reading when exposed to a beam having
dimensions smaller than the detector ([7], p. 155-162), and the reading must be multiplied by a scaling
factor (f):
f=
Detector Cross Section Area
Beam Cross Section Area
Beams as small as 0.01 cm2 are commonly encountered around single crystal diffraction apparatus and
correction factors of 6000 or more may be required for a 3.5-inch diameter ionization chamber. In such
cases, it becomes difficult to detect beams in which the dose rate may be hundreds of times greater than
permissible.
A.4.3 To resolve this difficulty in connection with the detection and measurement of X-rays from color
television receivers, the NCRP has allowed for the fact that the smaller the beam the less is the likelihood
that the same area of an individual will be repeatedly or continuously exposed. The standard for some
television receivers permits the dose rate to be averaged over an area of 10 cm2. The same practice is
acceptable for surveys around x-ray generator cabinets and system barriers, but in the vicinity of x-ray
tube housings, beam ports, collimators, and specimen chambers where small, intense beams are likely to
be encountered, it is recommended that the area over which the dose rate is averaged be limited to 1
cm2.
A.4.4 On this basis it may be assumed that the largest correction factor that will need to be applied will be
numerically equal to the sensitive area of the detector in square centimeters. In general,
.
.
X = X scale
for A beam > A detector
.
.
A
X = detector x X scale
A beam
f or 1 cm 2 < A beam < A detector
.
.
A
X = detect2or x X scale
1 cm
f o r A b e a m < 1 cm 2
.
.
X
X
A is
is the corrected exposure (or dose) rate, scale is the survey meter face reading, and
where
the area of the beam or detector as appropriate.
A.4.5 Film methods. X-ray film in a low absorption optically opaque envelope is a useful adjunct to the
survey meter in searching for radiation leaks. This method often gives recognizable shadows of features
of the x-ray equipment that may effectively locate the leak. An estimate of the cross section of the beam
can be obtained for use in correcting readings of a survey meter, or the film method itself can be made to
give a semi-quantitative estimate of the dose if calibration data are available ([7], pp. 185-212). An
additional advantage of the film is its suitability for integrating over a long period in order to detect very
weak beams and to give an indication of the dose averaged over a period of time that includes all the
steps of a given procedure. The latter sometimes leads to the detection of a possibly hazardous transient
situation.
A.4.6 Of special interest to those checking equipment in the field where darkroom facilities may not be
available, is the use of instant film packs of the type used to take photomicrographs from microscopes.
These have the developer built into the film pack and the photograph can be viewed generally in less
than a minute.
A.4.7 Fluorescent screen method. Fluorescent screens are occasionally useful, but their low sensitivity
generally limits their effectiveness to cases involving a direct beam. This being the case, the screen
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ANSI/HPS N43.2-2001
should be mounted on a long handle to minimize any risk of exposing the hands. It should be viewed
through a lead-glass shield. The sensitivity can be improved by darkening the room completely and
allowing 20 minutes or longer for the eyes to become dark adapted; however, the hazard of working in a
darkened environment must also be assessed.
A.5 Calibration
A.5.1 The accuracy of any radiation detector is only as good as its calibration. All radiation survey meters
shall be calibrated as required by regulations or in accordance with ANSI standard 323A-1997 Radiation
Protection Instrumentation Test and Calibration, Portable Survey Instruments. A recommended
calibration interval is at least annually.
A.6 The Use of a Check Source
A.6.1 As a means of detecting abrupt changes in calibration resulting from component deterioration or
hidden damage, a check source should be provided. Iron-55, which decays by electron capture directly
to the stable isotope manganese-55 is suggested for this application. It emits the 5.9 keV x-ray
characteristic of manganese-55. This radiation represents the extreme low energy range of the spectrum
encountered in survey work and provides an excellent test of an instrument's capabilities in this most
difficult range. A 1.85 MBq (50 µCi) source is sufficient to provide a dose of approximately 0.1 mSv/hr (10
mrem/hr), and its half-life (2.7 years) is long enough to insure a reasonably long useful life. The source
should be mounted in a jig that will insure fixed geometry and used on a regular basis. If possible, the
source dose rate should be established when the survey instrument has been recently calibrated.
Thereafter it is only necessary to correct the source dose rate for radioactive decay and, possibly,
variations in air absorption due to changes in barometric pressure and relative humidity. The simplicity of
the spectrum facilitates making such corrections.
A.6.2 Another function of the check source is in determining the stability of survey instruments over time.
A source of higher energy photons (or beta particles) and longer half-life might be preferred for this
application to avoid complications from air absorption and decay corrections.
18