Radiation protection regulation aspect

Anna Maria Motoc

Ádám Salik National Research Institute for Radiobiology and Radiohygiene

Radiation protection • An improper application of the ionising radiation may

harm the health of humans and of fauna and flora, therefore damaging the environment.

• In order to avoid these unwanted effects, for the control of radiation sources

Radiation protection was created

the protection against exposure to ionising radiation.

• Shortly after the discovery of ionising radiations, their users realised that standards of protection had to be developed.

• Due to this concern, the International Commission on Radiological Protection (ICRP) was established in 1928.

International organizations

Inter-governmental organization: • United Nations (UN)

and its subsidiary organization UNSCEAR

(UN Scientific Commitee on the Effect of Atomic Radiation)

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Specialised organizations

• Word Health Organization (WHO)

• Food and Agriculture Organization (FAO)

• International Labour Organization (ILO)

IAEA - International Atomic Energy Agency Radiation protection recommendations, Publications: Safety Standards, Safety Guides, Safety Recommendations, Safety Requirements.

For the effective operation of radiation protection, it is necessary to have appropriate laws and decrees.

• Complying with these, their revision and development can only be done based on

prescribed constitutional form

Organizations of International radiation protection - the main recommendations and regulations

Basic documents for Hungarian regulation

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• Governmental regulation – Governments have responsibility for the enforcement

of the standard, generally through a system that includes a Regulatory Authority

• National infrastructure includes: – legislation and regulations (law and decrees)

– a Regulatory Authority empowered to authorize and inspect regulated activities

– sufficent resources

– adequate numbers of trained personnel

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Regulatory Authority

The type of regulatory system adopted in a country depends on:

• the size

• complexity

• safety applications of the regulated practices and sources

• the regulatory traditions in the country

Radiation protection in Hungary Present regulation

ICRP Publication 103. (2007)

IAEA/IBSS

EURATOM Directive 2013/59 (2013)

Act No. CXVI of 1996 on Atomic Energy (modified)

Governmental Decree No. 487/2015

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Act CXVI of 1996 on Atomic Energy

Use of the nuclear energy is regulated by law in Hungary; • the peaceful use of atomic energy promotes the living conditions of humanity

in numerous fields of industry, agriculture, health care, and scientific research;

• however, that the improper application of atomic energy may harm the health of humans and of fauna and flora, and damage the natural environment;

• to ensure that the risk caused by the use of atomic energy is no greater than the socially-accepted risks associated with other activities and to ensure adherence to safety requirements by appropriate national regulations which are in agreement with international regulations;

Act CXVI of 1996 on Atomic Energy

• the Act defines the legal responsibilities of the users of nuclear energy and of the authoriti;

what it means, the nuclear energy peaceful uses? For example: Panoramic X-Ray Equipment, industrial application (radiography)

• the Hungarian Atomic Energy Authority (OAH) is charged with the primary responsibility for regulation and supervision of radiation safety.

Structure of the radiation protection framework

Act on Atomic Energy

Executive Decrees Standards for workplaces

Workplace Radiation Protection Rules

Government Decree No. 487/2015 (XII.30)

on the execution of certain provisions

of Act CXVI of 1996 on Atomic Energy associated with radiation protection

Goal of radiation protection

• to prevent the occurrence of serious radiation induced acute and chronic deterministic effects (e.g., cataracts, skin burns, acut radiation syndrom)

and

• to reduce the potential for stochastic effects (e.g., cancers, hereditary effects) in exposed persons to a degree that is acceptable in relation to the benefits to the individual and to society from the activities that generate such exposures.

Radiation protection requirements

3 principles:

• justification of a practice;

• optimization of protection and safety;

• dose limitation.

Justification of a practice

• No practice involving exposures to radiation should be adopted unless it produces sufficient benefit to the exposed individuals or to society to offset the radiation detriment it causes.

• An activity resulting in the release of ionising radiation may only be licensed in the case that it can be justified that the benefit to society counterbalances the potential adverse consequences of the radiation;

Optimization of protection

the protection and the safety shall be optimized:

• the magnitude of individual doses,

• the number of the persons exposed to radiation

• the probability of the exposures should all be kept as low as reasonable achievable (ALARA), economic and social factors being taken into account.

Optimization of Protection in Dental Radiology

• To be able to apply the principle of radiation protection to dental radiology system including design and Quality Control (QC).

Facts

• Very frequent examination (about 25% of all the radiological

examinations)

• Organs at risk: parathyroid, thyroid, larynx, parotid glands

Optimization of Protection in Dental Radiology

• Technical characteristics of intraoral, panoramic, and cephalometric dental x-ray equipment are summarized, along with operating characteristics

• Although doses are generally low, the high frequency of examinations requires radiation protection and quality control in dental radiology

• Some tests are detailed for quality control of dental equipment. What Tests ?

– Processor QC– most critical – Collimation – Dose – Exposure Time – Half-Value Layer – Kilovoltage (kVp)

How reduce the dose?

Patient dose? PD

Basic radiation protection strategies

• Time (short exposure time)

• Distance (operator)

• Shielding (lead)

Dose limitation

• Is aimed at ensuring that no individual is exposed to radiation risks that are judged to be unacceptable from these practices in any normal circumstances.

• The accumulated radiation doses arising from artificial sources, except the radiation doses arising from medical treatment, shall not exceed the dose limits set forth in the Decree (487/2015).

• Intervention levels relating to emergency radiation doses (urgent protective measures: isolation, evacuation, iodine prophylaxis)

Radiation protection dose limits with respect to workers and public

members

Exposed workers

Students, trainees

(between 16-18 y)

Members of the population

Workers in emergency situation

Effective dose (whole body)

20 mSv/y 6 mSv/y 1 mSv/y 50, 100 and

250 mSv / case

Equivalent dose Eye lenses

20 mSv/ y 15 mSv/y 15 mSv/y

Equivalent dose skins

500 mSv /y 150 mSv/y 50 mSv/y

Pregnant or nursing mother employee can't be employed in radiation jobs.

487/2015 Government Decree

Radiation protection training

Acquisition of radiation protection knowleadge shall be ensured within the framework of training and upgrading training (every five years); subject to examination; depending on the degree of the risk arising from the characteristics of the work: • basic level, • extended level, work in industrial, medical, radiological

areas (handle the radiation source independently, or who supervise such work positions);

• comprehensive level.

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Order of radiation protection training

• Acquisition of radiation protection knowleadge shall be ensured within the framework of training and upgrading training (every five years)

• Subject to written and oral examination

Licensing procedure

What is need license, when we use to x-ray equipment in Hungary?

X-ray equipment for operation only by Hungarian Atomic Energy Authority license

What needs of the Authority?

• Radiation Protection Description

• Workplace Radiation Protection Rules

Radiation Protection Description

include:

• the organizational (dentistry) structure of the workplace

• technological description of the activity,

• optimization criteria,

• Workplace layout (where is the equipment)

• Certification standards,

Radiation Protection Description

• the quality control program,

• operator dose

• number of employees

• the risk of accidents

• type of equipment and the type of Marketing Authorisation (type quality certificate)

Marketing Authorisation (type quality certificate)

• Any equipment used in the field of the application of atomic energy may only be used if it has been licensed as being suitable from radiation protection point of view and has issued a Marketing

Authorisation (HAEA).

– technical specifications

– Hungarian-language user's manual

– how much the patient dose

– declartion of conformity

Workplace Radiation Protection Rules

include:

• a radiation protection officer name, contact information, job title,

• the tasks of the heads of facility, • technical description of the radiologically hazardous

activities, • a description of the hazardous working area, • the classification of the workers, the requirements related to

monitoring of the internal and external radiation doses of the workers,

• the rights and obligations of workers working in radiation hazardous workplaces,

• an emergency prevention and action plan.

Basic requirements of the workplace radiation protection

radiation protection officer tasks of Radiation protection officer and one deputy,

appointed by the employer in writing; • Working with radiation in accordance with

applicable regulations, • Informing the employees, the organization of

education and access to education records, • organizing and keeping the register of medical

examination • equipment out inspections and measurements,

method and frequency of implementation,

Monitoring radiation doses

• Workers of radiation hazardous workplaces shall divided into two categories from the point of view of the monitoring of their radiation doses.

• Workers classified in group "A" are those in the

case of which the possibility exists that their annual effective dose might exceed the value of 6 mSv, or 3/10 of any of the organ dose limits.

• All other workers shall be classified in group "B".

Dosimetry of workers

• The personnel dosimetry monitoring of the radiation doses originating from external sources is compulsory in the case of workers classified in group “A”.

• A National Personal Dosimetry Service and Registry is operated at the NRIRR.

• The external doses were evaluated by TLD is used. • Dosimeters are distributed to about 16413 people working at about 1300 institutions (about 58% of them in healthcare, 27% in the nuclear energy production). • All data are recorded and preserved when the dose at a single reading exceeds 0.1 mSv.

Working areas classification and monitoring

• Controlled area shall be defined as the working area where the year due to the activities of individual exposure may exceed 1 mSv effective dose. – need to mark the entrance of the radiation hazard

symbol and inscription,

• Supervised area

Special radiation protection and safety rules don't need regular conditions.

-although doses incurred during

dental examinations are in general

relatively low,

-dental radiology accounts for nearly

one third of the total number of

radiological examinations in the EU

- and therefore merits specific

attention with regard to radiation

protection.

Safe Use of X-Ray Equipment

The aim of the study

to provide a practical guide to radiation protection for

professional groups of dentists and their assistants, based

upon the two relevant Council Directives of the European

Union:

– Directive 96/29/Euratom, of 13 May 1996, laying down the

basic safety standards for the protection of the health of

workers and the general public against the dangers

arising from ionising radiation;

– Directive 97/43/Euratom of 30 June 1997, on health

protection of individuals against the dangers of ionising

radiation in relation to medical exposure (Medical

Exposures Directive).

to avoid unnecessary or excessive

exposure to radiation and to improve the

quality and effectiveness of medical uses of

radiation

no exposure to X-rays can be considered

completely free of risk, so the use of

radiation by dentists and their assistants

implies a responsibility to ensure

appropriate protection.

Issues

Dental X-ray equipment

X-rays are an important tool that help dentists to

diagnose, plan treatments and monitor both

treatments and lesion development.

Types of dental radiological procedure:

– intraoral bitewing or periapical radiography

– panoramic examinations

– cephalometric examinations

Intraoral dental X-ray equipment

typical x-ray paramters

U: 65-70 kV

I: 6-7 mA

t: 0,5 sec

skin-source distance

SiD: 20 cm

patient dose (PD)

Effecitve dose

4-5 µSv/exposure

natural background:

~3000 µSv/y (0,1µSv/h

Panoramic X-ray equipment

typical x-ray paramters

U: 70-80 kV

I: 8-10 mA

t: 11-15 sec

skin-source distance

SiD: 25 cm

patient dose (PD)

Effecitve dose

20-30 µSv/exposure Dose limits(employee):

20.000 µSv/y

Protection of the patient

thyroid protection

lead apron

Front??

Behind??

Cephalometric X-ray equipment

typical x-ray paramters

U: 75-90 kV

I: 12 -14 mA

t: 20-40 sec

skin-source distance

SiD: 25 cm

patient dose (PD)

Effecitve dose

200-500 µSv/exposure natural background:

~3000 µSv/y (0,1µSv/h)

Combined technology

Panoramic operation CT operation

Cone Beam CT (CBCT)

Standing

position Seating

position

typical x-ray paramters

U: 75-90 kV

I: 12 -14 mA

t: 20-40 sec

skin-source distance

SiD: 25 cm

patient dose (PD)

Effecitve dose

200-500 µSv/exposure

NOMAD (Aseptico, USA)

EZX-60 (Genoray, Korea)

Mobile intraoral X-ray equipment

Dose received by the operator

due to scattered radiation

(µSv/exp)

Nomad EZX-60

Hand 0.18 2.88

Head 0.01 0.12

Gonad 0.00 0.05

Distance=70-80 cm texp=0.35 s

Acquisition of the licenses

Establishment of the facility

Installation of the equipment

Operation of the equipment

Ceasing of activity

Licensing procedure

Grant conditions of the licenses

First step

radiation protection and safety plan (design) form

radiation protection expert

Establishment, Installation and operation license at the

same time

Workplace Radiation Protection Rules

Setting up of the RP Service, assignment of the RP

officer(s)

Conditions for employees

Age (>18 years)

Pregnant women

Health eligibility (suitability) for the position

Professional aptitude

Acquisition of an appropriate radiation protection training

Radiation protection for medical and veterinary work places

Hungarian Standard: MSZ 824:2017.

RP of the workers and the public

Occupational exposure – not exceed 3/10 of the dose limit ((Goverment Decree 487/2015)

Surroundings (vicinity: dwellings, maternity ward, nursery, school) < 100 μSv

Room design (made by a qualified expert)

Size planning requirements:

size of the basic area in m2, length of side in m (intraoral dental X-ray, inside switchgear 9 m2 / 2.5 m, outside switchgear 4 m2 /1.8 m), room height (2.65 m))

Installation of the dental radiography equipment

Room design Positioning of the examination equipment (focus - wall

distance; in case of two equipments a reciprocal bolt prevents simultaneous activation)

These instructions should detail the responsibility for exposure, positioning of staff, use of protective devices, any restriction on primary beam direction

Adequate auxiliary rooms (waiting rooms, corridors, restrooms)

In case of two equipments a reciprocal bolt prevents simultaneous activation

Design of the facility

Protection of adjacent areas In deciding where to install dental X-ray equipment, it is

essential to consider the likely consequences in terms of radiation dose to staff and members of the public in adjacent areas.

This is particularly important if equipment is located close to a partition wall (i.e. within 1.5m for low workload situations), for any walls or floor in the direction of the primary beam (intraoral and cephalometry) and for high workload use.

Ideally, the advice of a qualified expert should be sought to establish the required wall and floor structural attenuation.

Room layout

It is essential that equipment operators can

position themselves so that they have a view of:

patient, controlled area and ‘X-rays on’ indicator

light.

If the room size is limited, it might be necessary for

staff to position themselves outside the room, in

which case a mirror/camera might be required to

ensure a clear view of the room.

The exposure switch should be located so that the

operator can either remain outside of the

controlled area or be behind a protective screen.

Principles of protection

- X-rays travel in a straight line unless they

interact with matter when their direction of travel

can change.

- The main beam of X-rays emitted by the X-ray

tube is known as the primary beam. When this

primary beam interacts with the patient’s head,

radiation will be scattered in all directions.

Primary and scattered

radiation

Staff protection

Dose limits

– In normal dental practice, effective dose should never exceed the annual dose limit for the workers (and would normally be expected to be lower).

– Likewise, dose to the skin of the hands should be well below the dose limit.

Applying ALARA principle:

“as low as reasonably achievable”

Use of time

Absorbed dose rate:

10 µGy/h

X time = absorbed dose

1 hour = 10 µGy

2 hours = 20 µGy

Use of distance

For a point source of

radiation:

the dose rate falls off as

the inverse of the square

of the distance from the

source

Use of shielding

Protective equipment (walls, leaded doors,

leaded partition wall, leaded apron)

thick 12 cm brick equal 0,5 mm lead

-for intraoral film radiography, the radiation dose in

the primary beam is typically a few mGy at the end

of the cone

-the dose at 1 m – due to scattered radiation – is at

least 1000 times less (a few µGy)

-standing at a distance of 2 m from the patient’s

head will lead to a dose of roughly a quarter of that

received standing only 1 m away

-for scattered radiation, the use of distance alone is

often adequate protection in the dental situation

Results

Patient exposure in dental practices

Individual doses in basic dental radiography (intra-

oral, panoramic and cephalometric) are low, being

equivalent to those associated with a few days of

background radiation.

Individual doses from more complex imaging (CT

scans and multiple slice cross-sectional

tomography) can be substantially higher.

Individual risks in dental radiography are small but

are greater in the younger age groups (below 30) in

which (in many EC member states) dental

radiography is most frequently performed.

Patient exposure in dental practices 2

All X-ray examinations must be justified on an

individual basis by demonstrating that the benefits to

the patient outweigh the potential detriment.

The anticipated benefits are that the X-ray examination

would add new information to aid the patient’s

treatment.

No radiographs should be selected unless history and

clinical examinations have been performed.

‘Routine’ radiography is an unacceptable practice.

Thank you for your attention!

Question? Thank you for your attention!