Iso 11737 2 Pdf Free Download
Radiation Sterilization Standards, such as ISO 11137 and related Technical Reports and Specifications pertaining to radiation sterilization of medical products were discussed. Standard
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Abhaya Sharma
ISOMED, Bhabha Atomic Research Centre
Trombay, Mumbai, 400 085 India
(Email: abhaya@magnum.barc.ernet.in)
Introduction
Radiation sterilization using
gamma radiation from Cobalt-60 or
Caesium-137 has achieved a
phenomenal success in the last three
decades or so. The method offers
several advantages over the traditional
methods of sterilization viz. ethylene
oxide, dry and moist heat.
The major advantages include
sterilization in the pre-packed
condition, deep penetration of the
gamma radiation and a single
parameter that controls the process i.e.
time of irradiation. Radiation
processing facilities provide a safe,
continuous and efficient method for
sterilization of healthcare products.
Radiation sterilization is an accepted
method for sterilization of a wide
variety of healthcare products more so
in the growing field of disposable
medical products. It is particularly
suitable for a large number of
products that may be either heat
sensitive or where use of ethylene
oxide is prohibited, for the presence
of toxic residual substances and
occupational hazard.
Moreover, being a continuous
process it is applicable to sterilization
of the products on a large scale.
Several developed and developing
countries have adopted gamma
radiation for sterilization of their
healthcare and medical products.
Gamma radiation processing facilities
worldwide mainly use sealed cobalt-
60 sources, which can be easily
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produced in nuclear reactors, Cs-137
can also be used for this purpose.
International Organization for
Standardization (ISO) and American
Society for Testing and Materials
(ASTM) are the major organizations
that provide international standards on
a wide variety of applications of
science and technology. The
availability of standards on radiation
sterilization and related aspects from
these organizations has greatly
influenced and promoted the global
acceptance of the sterilization of
healthcare products using ionizing
radiation. This has substantially
improved the standard and availability
of quality sterilized healthcare
products. The impact of these
standards for the advancement of the
radiation sterilization technology can
not be underestimated.
ISO 11137 is considered as the
primary document for validation and
quality control of the process of
radiation sterilization. Technical
reports and specifications which apply
in particular or specific conditions and
are to be used in conjunction with this
standard are also available.
A radiation dose of 25 kGy for
sterilization of healthcare products is
universally accepted as effective in
rendering the products sterile with a
high degree of sterility assurance
level. This dose was used in the very
first applications of ionizing radiation
by Ethicon for sterilization of surgical
sutures.
The 25 kGy dose is considered
to have a high safety factor and is
believed to be suitable for most of the
materials used in the manufacture of
healthcare products. The accurate and
precise measurement of absorbed
dose is crucial in all radiation
processing applications and
sterilization is no exception.
ISO/ASTM standards on dosimetry
are also described.
For any given sterilization
method, microbiological evaluation of
the products before and after the
sterilization is naturally considered an
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essential act. In fact, for some
traditional methods of sterilization
e.g. heat and ETO, the use of
biological indicators and/or sterility
tests are also to be performed for the
validation.
Microbiological aspects, not
necessarily restricted to radiation
sterilization, are subject of some
international standards. These
standards have also been included for
completeness.
Radiation Sterilization Standard –
ISO 11137
ISO 11137 has served the
radiation processing facilities in
providing the guidelines for
sterilization of healthcare products
since the time of its inception in 1991
and has since been revised in 1995.
The efforts are being made for
harmonization of this standard with
EN 552 a compatible standard on
radiation sterilization of medical
devices from European Committee for
Standardization (CEN). The extensive
revision of these standards is planned
to accommodate and base them on the
recent general sterilization standard
ISO 14937.
ISO standard 11137 describes
the process and quality control
requirements in context of
sterilization using ionizing radiation.
The products sterilized according to
the procedures and guidelines
described in this standard, are likely
to consistently yield good results,
provided, the specified sterilization
dose is imparted to the products, and
they are manufactured using good
manufacturing practices.
The standard covers terms and
definitions, requirements for
validation and procedures for
qualification of the irradiation facility,
process and products. The
significance of certification, routine
process control, and documentation as
applied to the radiation sterilization
has been dealt explicitly. Four
informative annexure are included in
this standard to enhance support to
the radiation sterilization application.
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Annexure A discusses the device and
packaging material qualification.
Annexure B deals with the dose
setting methods – two methods have
been described for determination of
sterilization dose. Dosimeters,
dosimetry and associated equipment
have been mentioned in the annexure
C, where as bibliography and
reference material is provided in the
last annexure. The important radiation
sterilization standards, guidelines,
technical reports and specifications
are presented in the table-1.
Table – 1 Radiation Sterilization Standards, Technical Reports and
Specifications
Standard Description/Title Year
ISO 11137 Sterilization of Healthcare Products- Requirements for
Validation and Routine Control - Radiation
Sterilization
1991,
1995
ISO/TR
13409
Sterilization of Healthcare Products - Substantiation of
25 kGy for Radiation Sterilization of Small or
Infrequent Production Batches
1996
ISO/TR
15844
Sterilization of health care products- Radiation
Sterilization - Selection of Sterilization dose for a
single production batch
1998
ISO/TS
15843
Sterilization of Healthcare Products- Radiation
Sterilization- Product Families and Sampling Plans for
Verification Dose Experiments and Sterilization Dose
Audits, and Frequency of Sterilization Dose Audits
2000
EN 552 Validation and routine control of sterilization by
irradiation
(1994)
ANSI/AAMI
ST- 32
Guidelines for gamma radiation sterilization 1991
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Technical Reports and Specification
used in conjunction with ISO 11137
A technical report ISO/TR
13409 addresses the substantiation of
the dose of 25 kGy for sterilization of
small or infrequent production
batches. ISO/TS 15843 describes the
issues related to product families,
sampling plans and dose verification
experiments for sterilization dose
audits and frequencies of such audits.
ISO/TR 15844 provides the methods
for selection of sterilization dose for a
single production batch.
Dosimetry – The General
Standards
Dosimetry is the science of the
measurement of absorbed dose when
matter is exposed to ionizing
radiation. The absorbed dose, defined
as the amount of energy imparted per
unit mass of the product on exposure
to ionizing radiation, is measured in
gray (Gy), 1 Gy is equivalent to 1
Joule/Kg. Often the accurate
measurement of the absorbed dose is
the only quality control parameter
employed for certifying the products
to be sterile, when using radiation
sterilization methods. Three
standards on the general aspects of
dosimetry are available jointly from
ISO and ASTM.
The standard ISO/ASTM
51261 describes the general criteria
for selection of a dosimetry system
and the calibration aspects.
ISO/ASTM 51400 describes the
characterization and performance
requirements of such a laboratory.
The standard ISO/ASTM 51707
addresses the concept of uncertainties
and their applications to radiation
dosimetry, this last standard assumes
further significance since the dose
from different laboratories is found to
be quite different due to uncertainties
introduced during measurement.
Table-2 lists these and
standards on terminology related
radiation measurement and dosimetry
and Practice for calculation of
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absorbed dose from gamma or X-rays. .
Table-2 Standards on Guidelines and Practice of Dosimetry
Standard Description/Title Year
ASTM E170 Terminology relating to radiation measurement
and dosimetry
1999
ASTM E 666 Standard practice for calculating absorbed dose
from gamma or X-radiation
1997
ISO/ASTM
51261
Guide for Selection and Calibration of Dosimetry
Systems for Radiation Processing
2002
ISO/ASTM
51400
Practice for Characterization and Performance of a
High Dose Gamma Radiation Dosimetry
Calibration Laboratory
2002
ISO/ASTM
51707
Guide for Estimating Uncertainties in Dosimetry
for Radiation Processing
2002
Specific Dosimetry Systems
The measurement of absorbed
dose is carried out using a specific
dosimetry system. Some of the
dosimetry systems that can be used
for radiation sterilization, i.e. suitable
for the measurement of absorbed dose
of 25 kGy are listed Table-3.
The chemical or physical
changes imparted in the dosimeters
have well defined radiation yield that
can be correlated to the actual dose
absorbed in the products. Several
dosimetry systems have been
identified over the years and many of
them are suitable for the measurement
of absorbed dose during radiation
sterilization.
For example, Ceric-cerous
sulphate dosimeters (ISO/ASTM
51205) are widely employed in
radiation processing facilities to
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calculate the absorbed dose. The
other systems which have received
much attention are alanine-EPR,
dichromate, ethanol-chlorobenzene,
radiochromic film and liquid
solutions, cellulose acetate, and
polymethylmethacrylate systems. The
selection of a particular dosimetry
system is governed by the availability
of the particular dosimeter system,
cost, availability of the necessary
apparatus/equipment.
Table-3 Standards related to Specific Dosimetry Systems
Standard Description/Title Year *
ISO/ASTM
51205
Practice for Use of a Ceric-Cerous Sulfate
Dosimetry System
2002
ISO/ASTM
51275
Practice for Use of a Radiochromic Film
Dosimetry System
2002
ISO/ASTM
51276
Practice for Use of a Polymethylmethacrylate
Dosimetry System
2002
ISO/ASTM
51401
Practice for Use of a Dichromate Dosimetry
System
2002
ISO/ASTM
51538
Practice for Use of an Ethanol-Chlorobenzene
Dosimetry System
2002
ISO/ASTM
51540
Practice for Use of a Radiochromic Liquid
Solution Dosimetry System
2002
ISO/ASTM
51607
Standard Practice for Use of the Alanine -EPR
Dosimetry System
2002
ISO/ASTM
51650
Practice for Use of a Cellulose Acetate Dosimetry
System
2002
* Existed earlier but jointly issued by ISO/ASTM in 2002
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Dosimetry systems which can be
transported from one place to another
without having any effect on the
amount of absorbed dose over a
period of time are known as transfer
dosimetry systems. These are
particularly useful for national or
international validation of the
dosimetry systems. The absorbed
dose calculated using a specific
dosimetry system is compared with
the value obtained using transfer
dosimetry systems. Alanine-EPR
dosimetry system (ISO/ASTM 51607)
is used by IAEA and several other
which undertake the international
dose assurance services.
Microbiology Related Standards
Various microbiological
methods are required for
determination of the verification and
validation of sterilization dose as
mentioned in ISO 11137. The two
part ISO standard ISO 11737 is
particularly useful in this regard. The
first part of this standard can be used
for determination of bioburden on the
products. Whereas, second part is
particularly useful for conducting
sterility tests for validation of the
sterilization process. These standards
include informative annexures which
outline the various requirements for
materials, equipments, sampling
techniques, experimental methods and
presentation of results for the
microbiological evaluations.
Though use of Biological
indicators is not mandatory for use as
a quality control method in radiation
sterilization, BIs based on Bacillus
pumilus are in use for this purpose for
radiation sterilization. They provide
supplementary information and are
considered an actual proof of
microbial inactivation. Part I of ISO
11138 describes the general
requirements for the use of biological
indicators used in context of
sterilization of healthcare products.
Microbiology related standards are
grouped in Table 4.
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Table-4 Microbiological Standards
Standard Description/Title Year
ISO 11737-1 Sterilization of Medical Devices- Microbiological
Methods - part 1: Estimation of population of
microorganisms on products
1995
ISO 11737-2 Sterilization of Medical Devices - Microbiological
Methods- Part 2: Tests of Sterility Performed in the
Validation of a Sterilization Process
1998
ISO 11138-1 Sterilization of Health Care Products - Biological
Indicators - Part 1: General
1994
ISO 14937 Sterilization of health care products - General
requirements for characterization of a sterilizing agent
and the development, validation and routine control of
a sterilization process for medical devices
2000
ISO 14937, which is a general
standard issued for sterilization of
health care products, describes the
requirements for characterization of
sterilizing agent and the development,
validation and routine control of a
sterilization process for medical
devices. It is expected that the
standards on sterilization using
radiation, ETO and moist steam are
also going to be developed on these
lines. The standard may well become
the major standard encompassing all
sterilization technologies.
There are specific standards for
quality control of medical devices
which are listed in ISO 14937 and
may be found useful in meeting the
requirements for medical devices.
References
1. Lambert, B.J. and Hansen,
J.M. (1998) ISO Radiation
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Sterilization Standards.
Radiation Physics and
Chemistry Vol. 52(1-6) 11-14.
2. Morrissey, R.F. and Herring,
C.M. (2002) Radiation
sterilization: Past, Present and
Future. Radiation Physics and
Chemistry Vol. 63(3-6) 217-
221.
3. Miller, A. and Hansen, J.
(2002) Revision of the ISO
and EN Radiation Sterilization
Standards. Radiation Physics
and Chemistry Vol. 63(3-6)
665-667.
4. Note: Some of the major
organizations that have been
involved with the preparation
of standards, guidelines,
technical reports and
specifications pertaining to
radiation sterilizations and
various related aspects.
a. ISO – International
Organization for
Standardization - Case
Postale 56, CH-1211,
Geneve 20 Switzerland.
(website: www.iso.org)
b. ASTM – American
Society for Testing and
Materials – 100 Barr
Harbor Drive, West
Conshohocken, PA
19428 USA.
c. CEN – European
Committee for
Standardization – Rue de
Strassart 36, B-1050
Bruxelles, Belgium.
d. AAMI – Association for
the Advancement of
Medical Instruments,
1110 N Glebe Road,
Suite 220, Arlington, VA
22201-4795 USA.
e. ICRU – International
Commission on
Radiation Units and
Measurements, 7910
Woodmount Ave. Suite
800, Bethesda, MD
20814 USA.
ResearchGate has not been able to resolve any citations for this publication.
- A. Miller
- Joyce Hansen
The radiation sterilization standards, ISO 11137 and EN 552, are now being revised under "ISO lead", with the aim of producing only one international standard, although in four parts: (1) requirements, (2) dose-setting methods, (3) dose-substantiation methods and (4) dosimetry. Several aspects of the old standards that have caused problems, when they were used in practice, are addressed in the revision. Input from users of the standards is necessary in order that the standards be developed as useful tools in the documentation of radiation sterilization.
- Byron J. Lambert
- Joyce M. Hansen
This presentation provides an overview of the current status of the ISO radiation sterilization standards. The ISO standards are voluntary standards which detail both the validation and routine control of the sterilization process. ISO 11137 was approved in 1994 and published in 1995. When reviewing the standard you will note that less than 20% of the standard is devoted to requirements and the remainder is guidance on how to comply with the requirements.Future standards developments in radiation sterilization are being focused on providing additional guidance. The guidance that is currently provided in informative annexes of ISO 11137 includes: device/packaging materials, dose setting methods, and dosimeters and dose measurement, currently, there are four Technical Reports being developed to provide additional guidance: 1.1. AAMI Draft TIR, "Radiation Sterilization Material Qualification"2.2. ISO TR 13409-1996, "Sterilization of health care products — Radiation sterilization — Substantiation of 25 kGy as a sterilization dose for small or infrequent production batches"3.3. ISO Draft TR, "Sterilization of health care products — Radiation sterilization Selection of a sterilization dose for a single production batch" li]4. ISO Draft TR, "Sterilization of health care products — Radiation sterilization-Product Families, Plans for Sampling and Frequency of Dose Audits."
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