IAEAInternational Atomic Energy Agency

Protection Against Public Exposureand

Release of patients after Radiotherapy

Day 9 – Lecture 3

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• To understand essential elements and concepts necessary to assess potential public exposure that may occur during the use of radiation sources ( e.g., in industrial or medical facilities or activities).

• • To understand the need to impose restrictions on the

release of patients after radionuclide therapy and on the activity of sources implanted in patients

• Emergency preparedness and response

Objective

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• Define the responsibilities.• Dose limits and constraints• Design considerations• Controlling visitor access. • Monitoring public exposure..• Procedures for decommissioning and source disposal.• Public protection with reference to Release of patients• Emergency preparedness and response

Contents

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“Exposure incurred by members of the public due to sources in planned exposure situations, emergency exposure situations and existing exposure situations, excluding any occupational exposure or medical exposure”

(GSR Part 3, Definitions)

Public Exposure

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• people who work in or visit facilities where radiation sources are used or stored etc.;

Public Exposure (cont)

The public may include, for example:

• personnel employed by the facilities (other than those authorized to deal with radiation sources);

• persons living near locations where radiation sources are used, calibrated or stored;

• contractors (other than authorized service agents) e.g. electricians, painters, plumbers, etc. who may be required to carry out work in supervised or controlled areas etc.

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The registrant or licensee shall ensure:

• optimization of the protection of members of the public whose exposure is attributable to radiation sources within their control;

• the security and safety of those radiation sources such that the likelihood of public exposure is controlled in accordance with the IAEA Basic Safety Standards;

• that they have suitable and adequate facilities, equipment and services for the protection of the public commensurate with the magnitude and likelihood of the exposure;

Responsibilities of registrant or licensee

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Public Dose Limits

Effective Dose Limits

1 mSv per year

In special circumstances a higher effective dose could be allowed in a single year provided that the average

over 5 years does not exceed 1 mSv per year

Equivalent Dose Limits

Lens of the eye 15 mSv per year

Skin 50 mSv per year

Recommended limits from the IAEA Basic Safety Standards (GSR Part 3)

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The registrant or licensee shall:

• appropriately train the personnel having functions relevant to the protection of the public.

• limit normal exposure of the relevant critical group so that the applicable dose limits are not exceeded;

• use appropriate monitoring equipment and surveillance Programs;• maintain adequate records of the surveillance and monitoring results;

“Registrants and licensees shall, as appropriate: (a) establish and implement monitoring programmes to ensure that public

exposure due to sources under their responsibility is adequately assessed and that the assessment is sufficient to verify and demonstrate compliance with the authorization. (GSR Part 3, 3.137)

General Responsibilities

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• dose contributions from other radiation sources and practices including realistically assessed possible future sources and practices;

• potential changes in any condition that could affect public exposure eg. structural changes to the facilities, etc;

• current good practice in the operation of similar radiation sources;

• any uncertainties in the assessment of exposures.

The registrant or licensee shall take into account:

Responsibilities of registrant or licensee

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• before commencing use of the radiation sources, ensure that all new installations and all significant modifications have been approved by the Regulatory Body;

• establish public dose constraints to the satisfaction of the Regulatory Body;

• ensure that shielding and other protective measures are optimized in accordance with the requirements of the regulations or other standards approved by the Regulatory Body.

The registrant or licensee shall:

Responsibilities of registrant or licensee

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• are accompanied by personnel who are knowledgeable about the protection and safety measures for that area;

Control of Visitors

• are given information and safety instructions before entering the area;

Registrants and licensees shall ensure that visitors to controlled areas:

Adequate control over the entry of visitors to supervised areas shall be maintained and appropriate signs posted in such areas.

Responsibilities of registrant or licensee

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• The design of installations and the adequacy of shielding must be reviewed and approved by the Regulatory Body;

Sources of External Irradiation

• Dose constraints should be used to minimize potential exposure (ALARA).

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• Optimized measures shall be taken for restricting public exposures in areas accessible to the public.

Radioactive contamination in enclosed spaces

• Specific containment provisions shall be established for the construction and operation of a source that could cause spread of contamination in areas accessible to the public.

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• establish a monitoring Program to ensure compliance with the dose limits;

• maintain adequate records of the monitoring Program;

• report a summary of monitoring results to the Regulatory Body at prescribed intervals;

• promptly report any abnormal events that are causing an increase in public exposures.

Monitoring of Public Exposures

Registrants and licensees shall, if appropriate:

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Products capable of causing exposure to the public shall not be supplied unless subject to exclusion, exemption or are otherwise authorized by the Regulatory Body.

Consumer Products

• Labels should be firmly affixed to each product stating that: the product contains radioactive material; the sale has been authorized by the Regulatory Body.

• Information is to be provided with the product stating any precautions for use and disposal of the product.

Smoke Detector

Uranium glazed dish Luminous watch Luminous Key Rings

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• the industrial facility and remaining equipment is free of contamination;

When an industrial facility is to be decommissioned, the licensee shall ensure:

Decommissioning and source disposal

• that all radiation sources are returned to the supplier or otherwise disposed of in compliance with the law and the requirements of the Regulatory Body;

Inadequate control of disused radioactive sources can pose a significant risk to occupationally exposed personnel and the public.

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• redundant radiation warning signs are removed;

Decommissioning and source disposal (cont)

• disused radiation sources are disposed of in compliance with local regulations and with full knowledge of the Regulatory Body.

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Protection of the Public

Release of patients

after Radionuclide Therapy

and with Radioactive Implants

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“The government shall ensure that, as a result of consultation between the health authority, relevant professional bodies and the regulatory body, the following are established:

• dose constraints, for carers and comforters • criteria and guidelines for the release of patients who have undergone

therapeutic procedures using unsealed sources or patients who still retain implanted sealed sources…”

(GSR Part 3, 3.148)

“Registrants and licensees shall ensure that relevant dose constraints are used in the optimization of protection and safety in any procedure in which an individual acts as a carer or comforter…”

(GSR Part 3, 3.172)

Values should be establish at national (or regional) level.

Dose Constraints

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Layout of Nuclear Medicine Department should take into account the potential exposure of the general public

From high to low activity

Layout of Nuclear Medicine Department

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• Separation of radioactive patients and other patients waiting is an example of good practice, especially in a busy department.

Patient Areas

• A separate toilet for the exclusive use of injected patients should always be considered. This patient washroom should not be used by general public or hospital staff as it is likely that the floor, toilet seat and sink taps will be contaminated frequently.

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The need for structural shielding or movable shields must be considered during radionuclide therapy.

Patient treated with 131 I or implanted

Ordinary patient

Shielding

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Storage of Sources

• to be locked to prevent unauthorized use and theft;

Storage location:

• display a warning sign;• to be shielded as appropriate;• audited to maintain the

accuracy of the source inventory.

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• properly classifying areas;

Reducing the Risk of Uncontrolled Contamination

The risk of contamination can be reduced by:

• engaging well trained staff and promoting a safety culture;

• documenting safe procedures in the handling of radiopharmaceuticals (receipt, preparation, administration, waste disposal);

• routine workplace monitoring.

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“The radiological medical practitioner shall ensure that no patient who has undergone a therapeutic procedure with sealed sources or unsealed sources is discharged until it has been established by either a medical physicist or the facility’s radiation protection officer that:• the activity of radionuclides in the patient is such that doses that

could be received by members of the public and family members would be in compliance with the requirements set by the relevant authorities;

• the patient is provided with: written instructions for keeping doses to persons in contact with or in the vicinity of the patient ALARA and for avoiding the spread of contamination; and information on the radiation risks…” (GSR Part 3, 3.177)

Release of patients

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YES!(after leaving the hospital)

The Radioactive Patient

Are there uncontrolled radioactive sources that may cause external exposure and contamination of the general public?

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Keep the patient in the hospital

Release the patient without any restrictions

Release the patient with restrictions

Risk of exposure to the general public

The Patient as a Contamination Source (cont)

Risk

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• Patients wrongly discharged with temporary radioactive implants in place - a very significant incident that would require immediate remedial action and immediate advice to the Regulatory Body.

Major radiation safety issues

• Patients properly discharged with permanent radioactive implants in place - the patient, family and other persons need to be informed of the hazards, risks and protective measures (where applicable).

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Patients with temporary implants• The responsible medical practitioner must ensure

that all radioactive sources are removed from the patient before discharge.

• This is applicable to all radioisotopes and all types of implants including HDR and LDR remote after loading sources.

• All brachytherapy patients must be monitored before discharge to confirm that all sources have been recovered and have been returned to safe and secure storage.

Major radiation safety issues

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Potential for severe accidents

• Radioactive sources were dislodged from the drive mechanism of an HDR remote afterloading machine and remained in the patient who subsequently died from the radiation exposure.

Example of an accident due to equipment design:

Contributing factors included:

• equipment design not tested adequately;

However, regardless of equipment faults, the accident could have been prevented by proper patient monitoring.

• conflicting signals given by the source position indicator;

• a history of malfunction of a separate radiation detector;

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The Regulatory Body should check that the licensee:

• has appropriate written working rules and safety procedures;

• ensures that an appropriately trained medical physicist is involved in treatments;

• has a monitor at the door of brachytherapy treatment rooms; • ensures that a working and appropriately calibrated portable

radiation survey meter is available to monitor patients immediately the treatment ceases and before they are discharged.

Potential for severe accidents (cont)

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Emergency Preparedness and Response

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Emergency Response

• primary responsibility for emergency response lies with the licensees;

• Regulatory Body, together with other appropriate organizations, shall plan, co-ordinate and implement support for protective actions;

• Regulatory Body have a specific role in ‘off-site’ emergency situations where a licensee is not directly involved.

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Emergency Situations

The following situations may give rise to an emergency response or an intervention:• fire in a facility;• lost, stolen or abandoned sources of significant risk;• radioactive sources brought illegally into the State;• radioactive contamination from sources or from releases

generated in accidents;• a discarded container with a radiation warning symbol and

unknown contents;• malicious or criminal activity involving radiation sources.

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Emergency Preparedness

To ensure the effective discharge of its responsibilities and performance of its functions, the legislation should empower the Regulatory Body: • to require the user (usually the licensee) to develop specific

arrangements for preparedness and response for any practice or source that could necessitate an emergency intervention.

• to coordinate arrangements for emergency preparedness and response through national and local plans; and

• to fulfil its related international agreements and obligations;• to participate in the development and implementation of

generic emergency response planning for those aspects concerning radiation safety.

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Emergencies and Intervention

The role of the Regulatory Body in an intervention in the case of an emergency involving radiation sources will vary, depending on national circumstances, and will need to be determined in advance at the stage of emergency planning.

The regulations should specify this role, which can range from one in which it has responsibility for participating directly in emergency response actions to one in which it acts mainly as an advisor to the user (the licensee) or to a government agency responsible for responding to all types of emergencies.

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Emergency Situations – International Conventions

International conventions contain similar requirements to those in the IAEA Safety Standards and make them binding on contracting parties. These include:

• Convention on Nuclear Safety

• Joint Convention on the Safety of Spent Fuel Management and on the Safety of Radioactive Waste Management.

• Convention on Early Notification of a Nuclear Accident

• Convention on Assistance in the Case of a Nuclear Accident or Radiological Emergency.

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Emergency Situations – IAEA Response Centre

Member States of the IAEA, through contact points established pursuant to international agreements, are expected to notify the IAEA’s Incident and Emergency Centre (IEC) of any events or circumstances that seem to have consequences or implications for safety at the national or international level.

The Incident and Emergency Centre (IEC) was established in 1986 and designated by the Director General of the IAEA as the IAEA’s physical location for response to nuclear accidents or radiological emergencies anywhere in the world.