IEC 61331-1:2014

IEC 61331-1 ®
Edition 2.0 2014-05
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Protective devices against diagnostic medical X-radiation –
Part 1: Determination of attenuation properties of materials

Dispositifs de protection radiologique contre les rayonnements X pour
diagnostic médical –
Partie 1: Détermination des propriétés d’atténuation des matériaux

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IEC 61331-1 ®
Edition 2.0 2014-05
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Protective devices against diagnostic medical X-radiation –

Part 1: Determination of attenuation properties of materials

Dispositifs de protection radiologique contre les rayonnements X pour

diagnostic médical –
Partie 1: Détermination des propriétés d’atténuation des matériaux

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CODE PRIX T
ICS 11.040.50 ISBN 978-2-8322-1562-3

– 2 – IEC 61331-1:2014 © IEC 2014
CONTENTS
FOREWORD . 4
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 7
4 Methods to determine the ATTENUATION RATIO . 7
4.1 General . 7
4.2 NARROW BEAM CONDITION . 7
4.2.1 General description . 7
4.2.2 AIR KERMA RATE measurements . 7
4.2.3 RADIATION QUALITIES and RADIATION DETECTOR . 8
4.2.4 Signal to noise condition . 9
4.2.5 ATTENUATION RATIO evaluation. 10
4.3 BROAD BEAM CONDITION . 10
4.3.1 General description . 10
4.3.2 AIR KERMA RATE measurements . 10
4.3.3 RADIATION QUALITIES and RADIATION DETECTOR . 10
4.3.4 Signal to noise condition . 11
4.3.5 ATTENUATION RATIO evaluation . 12
4.4 Inverse BROAD BEAM CONDITION . 12
4.4.1 General description . 12
4.4.2 AIR KERMA RATE measurements . 12
4.4.3 RADIATION QUALITIES and RADIATION DETECTOR . 13
4.4.4 Signal to noise condition . 14
4.4.5 ATTENUATION RATIO evaluation . 14
4.5 Calculation of the ATTENUATION RATIO for photon-emitting radionuclides . 14
4.5.1 Equation . 14
4.5.2 Decay data . 14
4.5.3 Mass ATTENUATION and mass energy-absorption coefficients . 14
4.5.4 Verification of the mass- ATTENUATION COEFFICIENTS of the test
material . 15
5 Determination of ATTENUATION properties . 16
5.1 ATTENUATION RATIO . 16
5.1.1 Determination . 16
5.1.2 Indication . 16
5.2 BUILD-UP FACTOR . 16
5.2.1 Determination . 16
5.2.2 Indication . 16
5.3 ATTENUATION EQUIVALENT . 16
5.3.1 Determination . 16
5.3.2 Indication . 17
5.4 LEAD EQUIVALENT . 17
5.4.1 Determination . 17
5.4.2 Indication . 17
5.5 LEAD EQUIVALENT class for a SPECIFIED range of RADIATION QUALITIES . 17
5.5.1 Materials. 17
5.5.2 Standard thicknesses . 17

5.5.3 Conditions for assignment to a LEAD EQUIVALENT class . 17
5.5.4 Indication . 18
5.6 Homogeneity . 18
5.6.1 Determination . 18
5.6.2 Indication . 18
6 Statement of compliance . 18
Annex A (informative) Tables of ATTENUATION RATIOS, BUILD-UP FACTORS and first HALF-
VALUE LAYERS . 19
Bibliography . 24
Index of defined terms used in this International Standard . 25

Figure 1 – NARROW BEAM CONDITION . 9
Figure 2 – BROAD BEAM CONDITION . 11
Figure 3 – Inverse BROAD BEAM CONDITION . 13

Table 1 – Standard RADIATION QUALITIES for X-RAY BEAMS . 15
Table 2 – Standard gamma RADIATION QUALITIES according to ISO 4037-1 . 16
Table A.1 – ATTENUATION RATIOS F of lead thicknesses from 0,125 mm to 2 mm
N
calculated for RADIATION QUALITIES of Table 1 according to the formula given in 4.5.4. 20
Table A.2 – BUILD-UP FACTOR B measured for RADIATION QUALITIES of Table 1 according
to the formula given in 5.2.1 for lead thicknesses 0,25 mm, 0,35 mm and 0,50 mm . 21
Table A.3 – ATTENUATION RATIOS F of lead thicknesses from 0,125 mm to 7 mm
N
calculated for RADIATION QUALITIES of Tables 1 and 2 according to the formula given in
4.5.4 . 21
Table A.4 – First HALF-VALUE LAYERS in mm Al of RADIATION QUALITIES of Table 1 as a
function of additional lead filters of different thicknesses in the range from 0,125 mm
to 2 mm . 22
Table A.5 – First HALF-VALUE LAYERS in mm Cu of RADIATION QUALITIES of Table 1 as a
function of additional lead filters of different thicknesses in the range from 0,125 mm
to 4 mm . 23

– 4 – IEC 61331-1:2014 © IEC 2014
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
PROTECTIVE DEVICES AGAINST
DIAGNOSTIC MEDICAL X-RADIATION –

Part 1: Determination of attenuation properties of materials

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
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4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
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between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
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5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
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services carried out by independent certification bodies.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
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expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 61331-1 has been prepared by subcommittee 62B: Diagnostic
imaging equipment, of IEC technical committee 62: Electrical equipment in medical practice.
This second edition cancels and replaces the first edition of IEC 61331-1, published in 1994.
It constitutes a technical revision. This second edition has been adapted to apply to the
present technology. In particular, this second edition is consistently applicable to lead- and
non-lead-containing materials. The essential changes and extensions are:
– extension of the scope to cover photon-emitting radionuclides;
– improved methods to determine the ATTENUATION RATIO;
– addition of the so-called inverse BROAD BEAM CONDITION;
– addition of a method to calculate the ATTENUATION RATIO of photon-emitting radionuclides;
– definition of new standard X- and gamma RADIATION QUALITIES used for testing;
– addition of the so-called LEAD EQUIVALENT class;

– tables of ATTENUATION RATIOS, BUILD-UP FACTORS and first HALF-VALUE LAYERS for the
standard RADIATION QUALITIES filtered with different thicknesses of lead.
The text of this standard is based on the following documents:
FDIS Report on voting
62B/936/FDIS 62B/942/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
In this standard, the following print types are used:
– requirements and definitions: roman type;.
– informative material appearing outside of tables, such as notes, examples and references: in smaller type.
Normative text of tables is also in a smaller type;
– TERMS DEFINED IN CLAUSE 3 OF THIS STANDARD OR AS NOTED: SMALL CAPS.
The verbal forms used in this standard conform to usage described in Annex H of the ISO/IEC
Directives, Part 2. For the purposes of this standard, the auxiliary verb:
– “shall” means that compliance with a requirement or a test is mandatory for compliance
with this standard;
– “should” means that compliance with a requirement or a test is recommended but is not
mandatory for compliance with this standard;
– “may” is used to describe a permissible way to achieve compliance with a requirement or
test.
A list of all parts of the IEC 61331 series, published under the general title Protective devices
against diagnostic medical X-radiation, can be found on the IEC website.
The committee has decided that the contents of this publication will remain unchanged until
the stability date indicated on the IEC web site under "http://webstore.iec.ch" in the data
related to the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
– 6 – IEC 61331-1:2014 © IEC 2014
PROTECTIVE DEVICES AGAINST
DIAGNOSTIC MEDICAL X-RADIATION –

Part 1: Determination of attenuation properties of materials

1 Scope
This part of IEC 61331 applies to materials in sheet form used for the manufacturing of
PROTECTIVE DEVICES against X-RADIATION of RADIATION QUALITIES generated with X-RAY TUBE
VOLTAGES up to 400 kV and gamma radiation emitted by radionuclides with photon energies
up to 1,3 MeV.
This Part 1 is not intended to be applied to PROTECTIVE DEVICES when these are to be checked
for the presence of their ATTENUATION properties before and after periods of use.
This Part 1 specifies the methods of determining and indicating the ATTENUATION properties of
the materials.
The ATTENUATION properties are given in terms of:
– ATTENUATION RATIO;
– BUILD-UP FACTOR;
– ATTENUATION EQUIVALENT;
together with, as appropriate, an indication of homogeneity and mass per unit area.
ATTENUATION properties in compliance with this part of the
Ways of stating values of
International Standard are included.
Excluded from the scope of this International Standard are:
– methods for periodical checks of PROTECTIVE DEVICES, particularly of PROTECTIVE CLOTHING,
– methods of determining ATTENUATION by layers in the RADIATION BEAM, and
– methods of determining ATTENUATION for purposes of protection against IONIZING RADIATION
provided by walls and other parts of an installation.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and
are indispensable for its application. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any
amendments) applies.
IEC 60601-1:2005, Medical electrical equipment – Part 1: General requirements for basic
safety and essential performance
IEC 60601-1:2005/AMD1:2012
IEC 60601-1-3:2008, Medical electrical equipment – Part 1-3: General requirements for basic
safety and essential performance – Collateral Standard: Radiation protection in diagnostic X-
ray equipment
IEC 60601-1-3:2008/AMD1:2013
IEC/TR 60788:2004, Medical electrical equipment – Glossary of defined terms

Monographie BIPM-5:2013, Table of Radionuclides
NISTIR 5632:2004, Tables of X-Ray Mass Attenuation Coefficients and Mass Energy-
Absorption Coefficients (version 1.4) [on-line, cited 2014-01-30] Available at
http://www.nist.gov/pml/data/xraycoef/]
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC/TR 60788:2004,
IEC 60601-1:2005 and IEC 60601-1:2005/AMD 1:2012, IEC 60601-1-3:2008 and IEC 60601-
1-3:2008/AMD1:2013 and the following apply.
3.1
ATTENUATION RATIO
ratio of the value of a SPECIFIED RADIATION QUANTITY in the centre of a SPECIFIED RADIATION
BEAM of SPECIFIED RADIATION QUALITY, with the attenuating material under consideration
outside the beam, to the value at the same position and under the same conditions with this
attenuating material placed in the beam
4 Methods to determine the ATTENUATION RATIO
4.1 General
There are four different conditions described in this standard to determine ATTENUATION
RATIOS, F:
F ATTENUATION RATIO measured with a NARROW BEAM CONDITION  (4.2)
N
F ATTENUATION RATIO measured with a BROAD BEAM CONDITION  (4.3)
B
F ATTENUATION RATIO measured with an inverse BROAD BEAM CONDITION (4.4)
IB
F ATTENUATION RATIO calculated for a photon-emitting radionuclide, R (4.5)
N,R
4.2 NARROW BEAM CONDITION
4.2.1 General description
The ATTENUATION RATIO F for a given test material (or test object) shall be measured
N
according to the arrangement for NARROW BEAM CONDITION as shown in Figure 1. This
arrangement is designed to measure the ATTENUATION of the X-RAY BEAM only due to primary
photons. The probability that secondary photons such as fluorescence photons or Compton
scattered photons from the test object reach the RADIATION DETECTOR is minimized. The
aperture in the DIAPHRAGM shall be just large enough to produce the smallest beam covering
the radiation detector. An additional DIAPHRAGM (number 5 in Figure 1) shall be used to shield
the RADIATION DETECTOR from SCATTERED RADIATION produced in the test object. The distance a
from the test object to the reference point of the RADIATION DETECTOR on the beam axis shall
be at least ten times the diameter d of the detector or ten times the diameter t of the
RADIATION BEAM at the distal surface of the test object , whatever is larger, i.e. a ≥ 10 max(d,t).
The minimal distance of the wall or the floor from the detector (position 6 in the Figure 1) in
the direction of the beam shall be 700 mm.
4.2.2 AIR KERMA RATE measurements
The AIR KERMA RATE shall be measured under three different conditions with the same
RADIATION DETECTOR at the same position, where
______________
Bureau International de Poids et Mesures, Pavillon de Breteeuil, F-92310 Sèvres, ISBN 92-822-2204-7 (set).
National Institute of Standards and Technology (NIST), U.S.Department of Commerce.

– 8 – IEC 61331-1:2014 © IEC 2014

denotes the AIR KERMA RATE without the test object in the RADIATION BEAM;
K

the AIR KERMA RATE with the test object in the RADIATION BEAM;
K

the AIR KERMA RATE with the test object in the beam replaced by a sheet of material of
K
B
the same shape with an ATTENUATION RATIO greater than 10
.
The same constant dose rate of the primary beam shall be used for the three measurements.
If the mean dose rate of the primary beam varies by more than 0,2 % during the
measurements, a monitor shall be used to normalize the three measurements to the same
primary beam dose rate.
4.2.3 RADIATION QUALITIES and RADIATION DETECTOR
The RADIATION QUALITIES used for the measurements shall be selected from Table 1 . The
 
RADIATION DETECTOR shall be calibrated in terms of AIR KERMA. The quotient K divided by K
0 1
shall be known with a relative standard uncertainty not more than 2 %.
NOTE The AIR KERMA RESPONSE of the RADIATION DETECTOR can be measured with e.g. NARROW BEAM qualities
and the RESPONSE can be plotted as a function of Al or Cu HALF-VALUE LAYERS (HVL). Tables A.4 and A.5 of this
standard can be used to look up the approximate Al or Cu HVL of the non-attenuated and attenuated beams. The
AIR KERMA RESPONSE in the actual beam can then be evaluated from the plot.

t
d
IEC  1444/14
1 DIAPHRAGM
2 Beam filtration
3 Beam-limiting DIAPHRAGM
4 Test object
5 DIAPHRAGM
6 Radiation detector
Condition: a ≥ 10 max(d,t)
Figure 1 – NARROW BEAM CONDITION
4.2.4 Signal to noise condition
The following condition shall be fulfilled:
 
K ≥ 10K
1 B
a
– 10 – IEC 61331-1:2014 © IEC 2014
4.2.5 ATTENUATION RATIO evaluation
The ATTENUATION RATIO F shall be evaluated as:
N
 
K −K
0 B
F =
N
 
K −K
1 B
4.3 BROAD BEAM CONDITION
4.3.1 General description
The ATTENUATION RATIO F for a given test material (or test object) shall be measured
B
according to the arrangement for BROAD BEAM CONDITION as shown in Figure 2. This
arrangement is designed to measure the ATTENUATION of the x-ray beam if secondary photons
emitted by the material sample are included in the detection of the attenuated beam. The
probability that secondary photons such as fluorescence photons or Compton scattered
photons from the test object reach the RADIATION DETECTOR is maximized. The distance a,
from the focal spot to the radiation exit plane of the test object shall be at least three times
the diameter d, of the beam limiting aperture, i.e. a ≥ 3d. The aperture diameter d shall be at
least 10 times greater than the distance b, of the reference point of the RADIATION DETECTOR
from the surface of the test object, i.e. d ≥ 10b. b shall be chosen as small as possible in
order to minimize the ATTENUATION of secondary photons by the amount of air between the
reference point of the RADIATION DETECTOR and the point of emission of the secondary photons
from the test object. The distance between the outer wall of the chamber and the surface of
the test object shall not exceed 10 mm. The minimal distance of the wall or the floor from the
detector (position 6 in Figure 2) in the direction of the beam shall be 700 mm.
4.3.2 AIR KERMA RATE measurements
The AIR KERMA RATE shall be measured under three different conditions with the same
RADIATION DETECTOR at the same position, where:

K denotes the AIR KERMA RATE without the test object in the RADIATION BEAM;

K the AIR KERMA RATE with the test object in the RADIATION BEAM;

K the AIR KERMA RATE with the test object in the beam replaced by a sheet of material of
B
the same shape with an ATTENUATION RATIO greater than 10 .
The same constant dose rate of the primary beam shall be used for the three measurements.
If the mean dose rate of the primary beam varies by more than 0,2 % during the
measurements a monitor shall be used to normalize the three measurements to the same
primary beam dose rate. The dose rate of the primary beam at any point in the plane of the
beam-limiting aperture shall not vary by more than 2 %.
4.3.3 RADIATION QUALITIES and RADIATION DETECTOR
The RADIATION QUALITIES given in Table 1 shall be used for the measurements. The RADIATION
 
DETECTOR shall be calibrated in terms of AIR KERMA. The quotient K divided by K shall be
0 1
known with a relative standard uncertainty not more than 2 %. The dependence of the
response of the RADIATION DETECTOR upon the direction of incidence shall be negligibly small
over a hemisphere. It is recommended to use a spherical ionisation chamber.
NOTE The AIR KERMA RESPONSE of the RADIATION DETECTOR can be measured with e.g. NARROW BEAM qualities
and the RESPONSE can be plotted as a function of Al or Cu HALF-VALUE LAYERS (HVL). Tables A.4 and A.5 of this
standard can be used to look up the approximate Al or Cu HVL of the non-attenuated and attenuated beams. The
AIR KERMA RESPONSE in the actual beam can then be evaluated from the plot.

d
IEC  1445/14
1 DIAPHRAGM
2 Beam filtration
3 DIAPHRAGM
4 Test object
5 Beam-limiting DIAPHRAGM
6 Radiation detector
Conditions: a ≥ 3 d, d ≥ 10 b
Figure 2 – BROAD BEAM CONDITION
4.3.4 Signal to noise condition
The following condition shall be fulfilled:
 
K ≥ 10K
1 B
a
b
– 12 – IEC 61331-1:2014 © IEC 2014
4.3.5 ATTENUATION RATIO evaluation
The ATTENUATION RATIO F shall be evaluated as:
B
 
K −K
0 B
F =
B
 
K −K
1 B
4.4 Inverse BROAD BEAM CONDITION
4.4.1 General description
The geometry of the inverse BROAD BEAM shown in Figure 3 is an alternative method to
measure the ATTENUATION RATIO F . In order to distinguish from the conventional method, it is
B
designated as F . In contrast to the conventional method described in 4.2 where a BROAD
IB
BEAM impinges on a large area piece of the test object and a small RADIATION DETECTOR
closely behind the test object is used, the inverse method is characterized by a NARROW BEAM
impinging on a small area piece of the test object and a large area flat RADIATION DETECTOR
immediately behind the test object. A flat ionisation chamber shall be used for this purpose.
This method has some advantages because it is easy to use, has low measuring
uncertainties, need only small field sizes and small sheets of material. It shall be used for the
determination of the ATTENUATION properties of materials used for PROTECTIVE CLOTHING and
PROTECTIVE DEVICES for gonads in medical x-ray diagnostic described in IEC 61331-3. The
method as described here shall not be used for RADIATION QUALITIES with X-RAY TUBE VOLTAGES
above 150 kV. The distance a, from the focal spot to the entrance plane of the measuring
DIAPHRAGM shall not be less than 5 times the diameter of the DIAPHRAGM aperture, d, i.e.
DIAPHRAGM. The
a ≥ 5 d. The test object can be fixed to the exit plane of the measuring
distance b, between the radiation exit plane of the test object and the flat ionisation chamber
shall be chosen to be as close as possible. The following condition shall be fulfilled:
D – d ≥ 10 b. The distance b shall not exceed 5 mm. The minimal distance of the wall or the
floor from the detector (position 6 in the Figure 3) in the direction of the beam shall be
700 mm.
4.4.2 AIR KERMA RATE measurements
The AIR KERMA RATE shall be measured under three different conditions with the same
RADIATION DETECTOR at the same position, where:

K denotes the AIR KERMA RATE without the test object in the RADIATION BEAM;

the AIR KERMA RATE with the test object in the RADIATION BEAM;
K

the AIR KERMA RATE with the test object in the beam replaced by a sheet of material of
K
B
the same shape with an ATTENUATION RATIO greater than 10 .

The same constant dose rate of the primary beam shall be used for the three measurements.
If the mean dose rate of the primary beam varies by more than 0,2 % during the
measurements, a monitor shall be used to normalize the three measurements to the same
primary beam dose rate.
d
D
IEC  1446/14
1 DIAPHRAGM
2 Beam filtration
3 DIAPHRAGM
4 Measuring DIAPHRAGM
5 Test object
6 Flat measuring chamber
Conditions: a ≥ 5 d, D – d ≥ 10 b, b ≤ 5 mm
Figure 3 – Inverse BROAD BEAM CONDITION
4.4.3 RADIATION QUALITIES and RADIATION DETECTOR
The RADIATION QUALITIES given in Table 1 shall be used for the measurements. The flat
ionisation chamber shall be calibrated in terms of AIR KERMA under the same irradiation
 
conditions as used in the measurements. The quotient K divided by K shall be known with
0 1
a relative standard uncertainty not more than 2%.
NOTE The AIR KERMA RESPONSE of the RADIATION DETECTOR can be measured with e.g. NARROW BEAM qualities
and the RESPONSE can be plotted as a function of Al HALF-VALUE LAYERS (HVL). Table A.4 of this standard can be
a
b
– 14 – IEC 61331-1:2014 © IEC 2014
used to look up the approximate Al HVL of the non-attenuated and attenuated beams. The AIR KERMA RESPONSE in
the actual beam can then be evaluated from the plot.
4.4.4 Signal to noise condition
The following condition shall be fulfilled:
 
K ≥ 10K
1 B
4.4.5 ATTENUATION RATIO evaluation
The ATTENUATION RATIO F shall be evaluated as:
IB
 
K −K
0 B
F =
IB
 
K −K
1 B
4.5 Calculation of the ATTENUATION RATIO for photon-emitting radionuclides
4.5.1 Equation
The ATTENUATION RATIO F for a given test material to protect against the photon-emitting
N,R
radionuclide R shall be calculated according to the following equation:
 µ (E ) 
en i
  p(E )E
∑ i i
 
ρ
 
i
air
F = , E ≥ 20 keV
N,R i
 µ(E ) 
i
−  dρ
 
 µ (E ) 
ρ
en i
 
m
 
p(E )E e
∑ i i
 
ρ
 
i air
where
E is the energy of the i-th photon emitted per decay
i
p(E ) is the photon emission probability per decay event for photons with energy E
i i
µ (E )
 
en i
  is the mass energy-absorption coefficient of air for photons with energy E
i
 
ρ
 
air
 µ(E ) 
i
  is the mass ATTENUATION COEFFICIENT of the test material for photons with
 
ρ
 
m
energy E
i
d is the thickness of the test material
ρ is the density of the test material
4.5.2 Decay data
Photon energies E and photon emission probabilities p(E ) shall be taken from the
i i
Monographie BIPM-5: Table of Radionuclides.
4.5.3 Mass ATTENUATION and mass energy-absorption coefficients
ATTENUATION and mass energy-absorption coefficients shall be taken from NISTIR 5632:
Mass
Tables of X-Ray Mass Attenuation Coefficients and Mass Energy-Absorption Coefficients.

4.5.4 Verification of the mass- ATTENUATION COEFFICIENTS of the test material
The test material’s mass ATTENUATION COEFFICIENTS used in 4.5.1 shall be verified by
comparison of measured values of F according to 4.2 with calculated values F according
N N,C
to the procedure described in the following. A set of standard RADIATION QUALITIES of Tables 1
and 2 shall be used which covers approximately the energy range of the photons emitted by
the radionuclide. Measurements for the standard gamma RADIATION QUALITIES listed in Table 2
shall be done with a NARROW BEAM CONDITION similar to that shown in Figure 1. The
distribution of the photon fluence with respect to the photon energies of the standard
RADIATION QUALITIES shall be known for this purpose. The value of F of the photon fluence
N
spectra shall be evaluated according to the following formula:
 µ (E ) 
en i
 
φ(E )E
∑ i i
 
ρ
 
i air
F =
N,C
 
µ(E )
i
−  dρ
 
 µ (E ) 
ρ
en i  
m
  φ(E )E e
∑ i i
 
ρ
 
i air
where
E is the energy attributed to the channel i containing all photons with energies between
i
∆ ∆
E − and E +
i i
2 2
φ(E ) is the number of photons contained in channel i
i
and the other symbols have the same meaning as in the equation of 4.5.1.
The condition |1 – F / F | ≤ 0,2 shall be fulfilled for the chosen set of qualities.
N N,C
Table 1 – Standard RADIATION QUALITIES for X-RAY BEAMS
Tube voltage TOTAL FILTRATION 1st HVL AIR KERMA RATE 1 m,
(nominal) (nominal) (nominal) 10 mA
(approximately)
kV
mm Al mm Cu mm Al
mm Cu mGy/s
30 2,5 0,99 0,1
40 2,5 1,44 0,2
50 2,5 1,81 0,3
60 2,5 2,14 0,4
70 2,5 2,44 0,5
80 2,5 2,77 0,6
90 2,5 3,10 0,8
100 2,5 3,44 0,9
110 2,5 3,79 1,0
120 2,5 4,13 1,2
130 2,5 4,48 1,4
140 2,5 4,82 1,6
150 2,5 5,17 2
200 1,2 14,6 1,63 1
250 1,8 16,8 2,53 1,5
300 2,5 18,6 3,37 2
400 3,5 20,8 4,51 3
– 16 – IEC 61331-1:2014 © IEC 2014
The X-RAY TUBE VOLTAGE shall not differ from the nominal values by more than 2 % or 2 kV,
whatever is less. The aluminium filter shall be of 99,9 % purity or higher and density
–3 –3
2,70 g cm . The copper filter shall be of 99,9 % purity or higher and density 8,90 g cm The
thickness of the aluminium and copper filters shall not differ from the nominal values by more
than 0,1 mm. The first Al and Cu HALF-VALUE LAYERS and the approximate AIR KERMA RATES are
given for information only.
Table 2 – Standard gamma RADIATION QUALITIES according to ISO 4037-1
Gamma Code RADIATION ENERGY Half life AIR KERMA RATE constant of
sources the pure source
ISO 4037 keV days
-1 2 -1
µGy h m MBq
Cs-137 S-Cs 661,6 11 050 0,079
Co-60 S-Co 1 173,3; 1 332,5 1 925,5 0,31

5 Determination of ATTENUATION properties
5.1 ATTENUATION RATIO
5.1.1 Determination
The ATTENUATION RATIOS F , F , F and F shall be determined according to 4.2, 4.3, 4.4
N B IB N,R
and 4.5, respectively.
5.1.2 Indication
The ATTENUATION RATIOS F , F , F and F shall be indicated by its numerical value
N B IB N,R
NARROW BEAM, BROAD BEAM, inverse BROAD BEAM,
together with the method of determination (
or calculated) and the RADIATION QUALITY in terms of the beam code, the X-RAY TUBE VOLTAGE
and HALF-VALUE LAYER or the code of the radionuclide (see Clause 6).
5.2 BUILD-UP FACTOR
5.2.1 Determination
The BUILD-UP FACTOR B shall be determined according to the equations
F F
N N
B = or B =
F F
B IB
depending on the method used for the BROAD BEAM measurement, where F , F and F refer
N B IB
to the numbers obtained by measurements according to 4.2, 4.3 and 4.4, respectively. F and
N
F or F and F , respectively, shall be done in the beam of the same x-ray facility.
B N IB
5.2.2 Indication
The BUILD-UP FACTOR shall be indicated by its numerical value together with the RADIATION
QUALITY in terms of the beam code, the X-RAY TUBE VOLTAGE and HALF-VALUE LAYER (see
Clause 6).
5.3 ATTENUATION EQUIVALENT
5.3.1 Determination
The ATTENUATION EQUIVALENTS δ , δ , δ and , δ shall be determined by measurements of
N B IB N,R
F , F and F according to 4.2, 4.3 and 4.4, or calculations of F according to 4.5,
N B IB N,R
respectively, for the material under test and by comparison with the thickness of a layer of the
reference material resulting within given tolerances in the same values of F , F , F and
N B IB
F , respectively. The measurements for the material and the reference material shall be
N,R
done in the same beam of the same x-ray facility.
5.3.2 Indication
The ATTENUATION EQUIVALENT shall be indicated in thickness of the reference material in mm
together with the method used for the determination (NARROW BEAM, BROAD BEAM, inverse
BROAD BEAM or calculated), the chemical symbol or other identification of the reference
material and the RADIATION QUALITY in terms of the beam code, the X-RAY TUBE VOLTAGE and
HALF-VALUE LAYER or the code of the radionuclide (see Clause 6).
5.4 LEAD EQUIVALENT
5.4.1 Determination
The LEAD EQUIVALENT shall be determined as ATTENUATION EQUIVALENT, but with (a) layer(s) of
lead as reference material.
NOTE LEAD EQUIVALENT values of a test material can be obtained by interpolation from measured ATTENUATION
RATIOS of lead sheets of different thicknesses covering the range of interest.
5.4.2 Indication
The LEAD EQUIVALENT shall be indicated in thickness of lead in mm together with the chemical
symbol for lead and the method used for the determination (NARROW BEAM, BROAD BEAM,
inverse BROAD BEAM, calculated) and the RADIATION QUALITY in terms of the X-RAY TUBE
VOLTAGE and HALF-VALUE LAYER or the code of the radionuclide (see Clause 6).
5.5 LEAD EQUIVALENT class for a SPECIFIED range of RADIATION QUALITIES
5.5.1 Materials
Some materials used for PROTECTIVE CLOTHING and protective patient shields in medical x-ray
diagnostic as described in IEC 61331-3 need the definition of the LEAD EQUIVALENT value for a
SPECIFIED range of RADIATION QUALITIES. The conditions for the assignment of such a value are
described in the following subclauses.
5.5.2 Standard thicknesses
The LEAD EQUIVALENT value shall be assigned to a material for one of the following classes of
lead thickness: 0,25 mm, 0,35 mm, 0,5 mm and 1 mm.
5.5.3 Conditions for assignment to a LEAD EQUIVALENT class
The LEAD EQUIVALENT class shall be assigned to a material if at least one of the following two
conditions is fulfilled for a SPECIFIED range of RADIATION QUALITIES selected from the full range
30 kV – 150 kV, see Table 1:
1) The ATTENUATION RATIO F of a material for a special RADIATION QUALITY is greater than
IB
250.
2) The LEAD EQUIVALENT δ , by definition determined with the inverse BROAD BEAM method
IB
according to 4.4, is equal or greater than a standard thickness of lead SPECIFIED in 5.5.2.
A relative standard uncertainty of 7 % in the determination of the LEAD EQUIVALENT shall be
taken into account in the decision of conformity, thus, if t is the standard lead thickness
Pb
...