RADIATION PROTECTION PRINCIPLES & REGULATORY

INFRASTRUCTURE

H. L. Anil Ranjith

INTERNATIONAL ORGANIZATIONS

International Commission of Radiological Protection (ICRP)

International Commission on Radiological Units and Measurements (ICRU)

International Atomic Energy Agency (IAEA)

International Electro technical Commission(IEC)

• Established in 1928 by the second international congress of radiology as the “International X-ray and Radiation Protection Commission” as its main concern was with the safety aspects of medical radiology.

• Name was changed to the ICRP in 1950 as its activities were expanded to widespread use of radiation outside the sphere of medicine.

• Assumed the basis responsibility for providing guidance in matters of radiation safety.

• Adopted the policy of preparing its recommendations to deal with the basic principles of radiation protection.

ICRP

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ICRP (http://www.icrp.org)In preparing its recommendations, ICRP considers

the fundamental principles and quantitative bases upon which appropriate radiation protection measures can be established, while leaving to the various national protection bodies the responsibility of formulating the specific advice, codes of practice, or regulations that are best suited to the needs of their individual countries.

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ICRP (http://www.icrp.org)

ICRP offers its recommendations to regulatory and advisory agencies and provides advice intended to be of help to management and professional staff with responsibilities for radiation protection. While ICRP has no formal power to impose its proposals on anyone, in fact legislation in most countries adheres closely to ICRP recommendations.

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United Nations Scientific Committee for the Effects of the Atomic Radiation

They elaborate the “UNSCEAR reports” to United Nations General Assembly about use and effects of atomic radiation.

UNSCEAR

ICRU

• Established in 1925

• Closely works with ICRP

• Responsible for development of Internationally acceptable recommendations regarding:

Quantities and units of radiation & radioactivity.

Procedures suitable for the measurements and application of these quantities in clinical

radiology and radiobiology.

Physical data needed in the application of these procedures.

IAEA

Is an UN agency established in 1956.

Responsible for promotion of peaceful uses of nuclear energy.

Assist member states in Radiation Protection and promotion of application of nuclear energy for peaceful uses.

Produces publications in radiation safety and on applications of radiation in all disciplines.

IEC

Responsible for development and recommendations of electrical standards and units.

International system of radiation protection

Radiation Protection Regulations

Radiation protection regulations in Sri Lanka has been developed using ICRP & IAEA recommendations.

Relevant publications are:

• ICRP Anals – 60

• IAEA International Basic Safety

standards 115

1991

(1994) 1996

BASIC TERMS

The activities which ADD radiation exposures or risks are called

PRACTICES

The activities which SUBTRACT radiation exposures are called

INTERVENTIONS

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Detriment

Radiation exposure to different organs and tissues in the body results in different probabilities of harm and different levels of severity.

The combination of probability and severity of harm is called “detriment”.

Effective dose reflects the combined detriment from stochastic effects due to the equivalent doses in all the organs and tissues of the body.

Practices (e.g medical use of radiation in a hospital)

Interventions (e.g. replacement of old Ra-sourced with other types of soures in brachytherapy)

Potential exposure (e.g. the possibility that sources are lost or destroyed)

Individual-related system

Source-related system

Main site of protection

Environment

A. B.

CONCEPTUAL FRAMEWORK

Provide an appropriate standard of protection against ionizing radiations without unduly limiting the beneficial practices giving rise to the exposures.

Prevent deterministic effects by keeping doses below the relevant threshold.

Demand that all reasonable steps are taken to reduce the incidence of stochastic effects to acceptable levels.

PRINCIPLES OF RADIATION PROTECTION

Three components have been identified by the

ICRP as:

1.) Justification of the practice

2.) Optimization of radiation protection

3.) Individual dose limitation

Justification of the Practice

No practice or source within a practice should be authorized unless the practice produces sufficient benefit to the exposed individual or to the society to offset the radiation harm which it might cause.

Justification of the Practice

Consider advantages and disadvantages

Ensure overall net benefit

Ideally, apply a risk-benefit analysis

Individual Dose Limitation

Dose to individuals shall not exceed the limits recommended for the appropriate circumstances.

Individual Dose Limitation

Aim of Dose limitation

Prevention of deterministic effects

Reduction of risk of stochastic

effects to an acceptable limit

Individual Dose Limitation

Categories of exposures :

1.) Occupational Exposure

2.) Public Exposure

3.) Medical Exposure

Individual Dose Limitation

Occupational exposure

Adults exposed to ionizing radiation in the course of their work .

Persons in this category are sometimes referred to as radiation workers.

Two sub-groups :

a) pregnant women

b) all other radiation workers

Individual Dose limitation

Public ExposureExposure incurred by members of the public from radiation sources,Excluding occupational or medical exposure and the normal local natural background radiation.

Summary of dose limits established in the Basic Safety Standards.

DOSE LIMIT (1)

APPLICATION Occupational PublicEffective dose 20 mSv per year averaged

over defined periods of 5years (2)

1 mSv per year (3)

Effective dose tothe embryo orfoetus

1 mSv The embryo or foetus is afforded thesame broad level of protection asrequired for members of the public.

Annual equivalentdose in the lens of the eye the skin (4) the hands and feet

150 mSv500 mSv500 mSv

15 mSv50 mSv

1.

2.

3.

4.

The limits apply to the sum of the relevant doses from external exposure in the specified periodand the 50-year committed dose (to age 70 years for children) from intakes of radioactive nuclidesin the same period

With the further provision that the effective dose should not exceed 50 mSv in any single year.

In special circumstances a higher value of effective dose could be allowed in a single year,provided that the average over 5 years does not exceed 1 mSv per year.

The limitation on the effective dose provides sufficient protection for the skin against stochasticeffects. An additional limit is needed for localised exposures to prevent deterministic effects.

Individual dose limitationMedical Exposure

Refers to :

International exposure of patients for diagnostic and therapeutic purposes.

Applies to :

Exposures administered by medical and paramedical personnel.

It does not apply to :

Irradiation of the staff involved in the administration of medical exposure.

Mutual irradiation of patients

Individual dose limitationMedical Exposure

Dose limit does not apply

Optimization of patient protection is done through Guidance levels

0.01

0.1

1

10

100

Effective dose mSv

201Tl- 85 Myocardium (20)

111In-Octreotide 150Tumour (8.1)

131I- 0.5 Thyroidfunction (35% uptake) (12)99mTc-MIBI 1200Myocardium (10)

99mTc-MDP 600 Bone (3.5)

51Cr-EDTA 4 Kidney clearance (0.008)

75Se-HCAT 0.3 Bile acid metabolism (0.2)

57Co-vitamin B12 0.5 “Schilling test” (1.0)

99mTc-aerosol 20Lung ventilation (0.2)

THO 4Body water (0.06)

99mTc-MAA 100Lung perfusion (1.1)

99mTc-MAG3 90 Kidney scintigraphy (0.66)

123I-MIBG 130Phaeochromocytoma (1.8)

99mTcO4- 200 Thyroid (2.4)99mTc-leucocytes 200Inflammation (2.2)

131I-MIBG 50Phaeochromocytoma (7.0)

99mTc-HMPAO 900Cerebral blood flow (8.4)

Angiocardiography

CT

Chest

Lumbar spine

Dental, single exp.

Hand, foot

Dental, fullmouthexamination

Pelvis

UrographyColon

Kidney, bladder

Nuclear medicineX-ray investigations

131I- 3 Thyroid function (35% uptake) (72)

Radionuclide-Tracer-Activity, MBq)-Investig.-(Eff.dose, mSv)

Mammography

Examination Radio-pharmaceu

tical

Administered activityMBq

mean¤

(range ofmean)

max¤ IAEAguidance

leveladults(11)

ARSACadults12)

“optimised”adults

Bone planar scintigraphy

99Tcm-MDP 450(158-600)

826 600 600 200-400(7)

SPECT 800 800Heart blood pool 99Tcm-RBC 687

(12-925)1 000 800 800

myocardium 99Tcm-MIBI 829(423-1300)

1 650 300400(SPECT)

201Tl-ion 81(63-133)

180 100 80

Kidney scintigraphy 99Tcm-DMSA 49

(10-200)200 160 80

renography 99Tcm-DTPA 125(3-300)

1 000 350 300 50(8)

99Tcm-MAG3 90(28-200)

1 000 100 100 45(8)

Brain99Tcm-HMPAO 930

(600-1038)1 100 500 500

¤) for all hospitals and all ages, Sweden, 1995

Optimization of radiation protection

All exposures should be kept As Low As Reasonably Achievable , economic and social factors being taken into account

Optimization of radiation protection

As Low as Reasonably Achievable

A L A R AAll levels of protection provided should result in dose below the relevant dose limits

Optimization is necessary to balance the resources put into protection and the level of protection obtained against background of other factors and constraints

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Dose constraints (I)A prospective and source related

restriction on the individual dose delivered by the source, which serves as a bound in the optimization of protection and safety of the source.

For occupational exposures, dose constraint is a source related value of individual dose used to limit the range of options considered in the process of optimization.

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For medical exposure the dose constraint levels should be interpreted as guidance levels, except when used in optimizing the protection of persons exposed for medical research purposes or of persons, other than workers, who assist in the care, support or comfort of exposed patients.

Dose constraints (II)

Except…

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Dose constraints are not dose limits.

Dose constraints do not apply to patients

In general, dose constraints should be established on the basis of the results of optimization

Dose constraints (III)

Except…

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Dose limitation for comforters and visitors of patients (I)

The dose limits should not apply to comforters of patients, i.e., to individuals exposed while voluntarily helping (other than in their employment or occupation) in the care, support and comfort of patients undergoing medical diagnosis or treatment, or to visitors of such patients.

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However, the dose of any such comforter or visitor of patients should be constrained so that it is unlikely that his or her dose will exceed 5 mSv during the period of a patient's diagnostic examination or treatment. The dose to children visiting patients who have ingested radioactive materials should be similarly constrained to less than 1 mSv.

Dose limitation for comforters and visitors of patients (II)

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Not considered for dose limitsSome cases are not considered for dose limits, although they may increase the effective dose:

Natural background radiation Origin: cosmic radiation and natural radioactive

elements in the environment (2-3 mSv/year)Radiation received as consequence of medical

exposureIt may represent an increment of dose > than natural

radiation, but it is not taken into consideration for dose limits.

Structure of Legal System

Level of Legislation

Act - Provide the legal basis for establishment of infrastructure for ensuring radiation safety.

Regulations - Establish general rules, principles and requirements for controlling exposures.

Code of - Provide instructions, Practices guidance and procedures for

safe handling & uses of varioussources of ionizing radiation.

LAWS & REGULATIONS

Atomic Energy Authority Act No. 19 of 1969

Sections : 18, 19, 20, 23, 30, 40 and 41 of the Act are important for regulatory control over uses of radiation

sources.

LAWS & REGULATIONS(CONTD)

Atomic Energy Safety Regulations No. 1 of 1999 (Gazetted in July 2000)

Regulations on Waste Management * (draft to be amended)

Regulations on Safe Transport of Radioactive Material *(final draft is ready for legal advice )

* Atomic Energy Safety Regulations No. 1 of 1999 has also given provision for control of disposal, store and transport of radioactive materials.

Atomic Energy Safety Regulations No. 1 of 1999

WAS GAZATED IN JULY 2000 AND SUPERSEDED PREVIOUS REGULATION MADE IN 1975.

Parties responsible for Enforcement

Regulatory Authority and, in the case of intervention, the intervening organization.

Parties responsible for application

Principle Parties: Registrant, Licensees and Employers.

Other parties which have subsidiary responsibilities : Suppliers Workers Radiation Protection Officers Medical Practitioners Health Professional Qualified Expert Ethical review committee; and any other party to

whom a principal party has delegated specific responsibilities.

National Complement Authority

Atomic Energy Authority : Established in 1970

Atomic Energy Regulations : Promulgated in 1975

(Superseded by new regulations of 1999)

Atomic Energy Safety

Regulation No. 1 of 1999: Promulgated in July

2000

Duties & Responsibilities of Atomic Energy Authority

Licensing & inspection of :

Sources of Ionizing Radiation.

Facilities & Installations

Operators & Users

Issue rules, Codes of Practices, Guides & Manuals etc.

Advice on Radiation Protection Matters

Keep records of sources

Keep records of doses

Duties & Responsibilities of Atomic Energy Authority

Authorization for disposal of radioactiveWastesAuthorization for transport of radioactiveMaterials

Organization of training courses on radiation protectionCarrying out personnel monitoring service

Prepare plans and procedures for dealing with emergencies.

Provisions of the regulations3.Prohibition of Unauthorised Practices.

 

No person shall be engaged in any practice specified in Sections 18,19 and 20 of the Act, involving exposure to, or the likelihood of exposure to ionising radiation or to radioactive substances or to irradiating apparatus, without an authorization issued by the Atomic Energy Authority (hereinafter referred to as the Authority) in respect of such practice, obtained prior to involvement in any such practice.

Provisions of the regulations

4.Applications

4.(1)For the purposes of these Regulations, such practices specified in Sections 18,19 and 20 of Act, for which prior authorization by the Authority is required, shall include the following:  

(a) The production of sources, mining and milling of radioactive ores; and the use of radiation from sources or radioactive substances, whether such use is for medical, industrial, veterinary or agricultural purposes, or for education and training or research, or otherwise; and these provisions shall be applicable to any activity that is related to such use, which may involve exposure to radiation or radiation sources such as, mining milling, processing, design, manufacturing, construction, assembling, acquiring, import, export, distribution, sell, loan, hiring, receiving, sitting, locating, commissioning, possession, use, operation, maintenance, repair, transfer, decommissioning, disassembling, transport, storage, disposal of sources; and these provisions shall also be applicable to any such practice which involves the presence or use of irradiating apparatus.

Responsibilities of Radiation Workers :

Each radiation worker shall ensure that he : works strictly in accordance with the

local radiation safety working rules given by the Radiation Protection Officer.

uses personnel monitoring devices issued to him in the manner in which it is required to be used and return them to the Radiation Protection Officer when called for;

immediately informs the Radiation Protection Officer of any suspected unsafe practice, hazardous situation, accident or incident; and the “Authority” on major incidents.

is aware of all precautions to be taken in the event of a hazardous situations, accident or incident