overview of occupational radiation safety in hospital, dr. avinash u. sonaware

Overview of Occupational Radiation Safety in

Hospital

Dr. Avinash U. Sonawane

Head, Radiological Safety Division

Atomic Energy Regulatory Board

Topics covered in presentation

• Applications of radiation

• Regulatory framework

• Regulatory requirements in respect of occupational workers

• Categories of exposures

• Issues relating to excessive exposures

• Conclusion

18 November 2015 2

Typical Usage of Radiation in Medicine

18 November 2015 3

Treatment of Cancer through Radiotherapy

Medical Diagnosis and Cardiological

Procedures Using X-rays

Nuclear Medicine for diagnosis, PET

examination and treatment

Blood irradiation to

prevent Transfusion- Associated

Disease

An estimated 5.1 million courses of radiotherapy treatment were

administered annually between 1997 and 2007.

UNSCEAR 2008 Report

Every year, 1 million new cancer cases are detected in India of which

40,000 cancer cases occur in children.

TMH,Mumbai Report

Over the last three decades, at least 3000 patients have been

affected by radiotherapy incidents and accidents.

These accidents do not affect patients directly (e.g. harm and

death), but might also undermine the public’s confidence in the

treatment.

Preventable medical errors overall also cost countries billions of

dollars each year.

IAEA

Radiotherapy

An estimated 3.6 billion (3.1 medical and 0.5 dental) x-ray examinations were undertaken annually in the world between 1997 and 2007.

Total annual collective effective dose to the global population (6,446 millions) from diagnostic medical exposures was estimated to be 4000 x103 manSv .

Annual per caput effective dose is 0.62 mSv.

CT scanning accounts 43% of the total collective effective dose due to diagnostic medical radiology.

UNSCEAR 2008 Report

Diagnostic Radiology

Nuclear Medicine

• Nuclear medicine includes all uses of unsealed radioactive sources

for diagnostic and therapeutic purposes.

• An estimated 33 million diagnostic nuclear medicine examinations

performed annually worldwide.

• Annual collective effective dose to the world population due to

diagnostic nuclear medicine examinations is estimated to be 202

x103 manSv.

• For diagnostic nuclear medicine, the main contribution to the

collective effective dose arise from Tc-99m bone scans, Tl-201

cardiovascular studies and iodine thyroid scans.

UNSCEAR 2008 Report

The UN Classes of Dangerous Goods

1. Explosive Substances

2. Gases

3. Flammable liquids

4. Flammable solids

5. Oxidizing substances

6. Toxic substances

7. Radioactive material

8. Corrosive substances

9. Miscellaneous dangerous substances and articles

7

Direct

effects

Indirect

effects

Cell death

Primary

damage

Modified

cell

Damage

to organ Somatic

cells

Germ

cells

Hereditary

effects

Cancer

Leukemia

Death of

organism

Repair

Deterministic

effects

Stochastic

effects

Biological effects of ionizing radiation

Regulatory Framework

18 November 2015

System of Regulatory Control

Issued by Central Government

Act [Atomic Energy Act, 1962]

Rules [Atomic Energy (Radiation Protection) Rules, 2004]

Notifications

Published by AERB

Safety Codes

Safety Standards

Safety Guides

Safety Manuals

• Atomic Energy Regulatory Board

(AERB) – the National Regulatory Authority for radiation protection

• AERB constituted in 1983. • The mission of the Board is to

ensure that the use of ionizing radiation and nuclear energy in India does not cause undue risk to health and the environment.

• Chairman, AERB is the

Competent Authority for radiation protection in India.

10

Atomic Energy Regulatory Board (AERB)

Atomic Energy Regulatory Board

18 November 2015 11

“Licence in accordance with Atomic Energy (Radiation Protection)Rules, 2004 from AERB is mandatory requirement for the procurement and use

of radiation sources in India”.

AERB, Anushaktinagar, Mumbai Radiological Safety Division (RSD) of AERB is responsible for enforcement of

regulations to ensure safe handling of ionizing radiation sources

Principles of Radiation Protection

• Justification- whether benefit of use of radiation outweighs the risk

• Optimisation- If exposure justified, then keep it as low as reasonably achievable (ALARA)

• Dose Limits- exposures should be within the prescribed dose limits

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Principles of Radiological Protection Justification

– Includes risk, cost and radiation detriment

– Depends upon availability of alternate techniques

– Sometimes beyond the scope of radiological protection alone

– In planned situation by controlling the source

– In emergency situation by modifying the pathway to avert further exposure

– Responsibility for justification generally lies with the Government or National authority

– For medical exposure justification often lies with professionals

– Professionals need to be specifically trained in Radiological Protection

Unjustified Practices

– Introducing radiations in consumer products-toys, jewellery, foods etc.

– Radiological examination without clinical indication

– Mass screening

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Optimisation

• Likelihood of incurring exposure

• Number of people exposed

• Magnitude of individual dose

• Socio-economical factors

• ALARA – Time…Distance…..Shielding

Level of benefit should be high maximizing the margin over harm.

Basis of Dose Limits • Risk based approach:

• For radiation workers: The death rate probability is 1 out of 1000. This death rate probability is equal to the death rate probability of the workers working in high risk areas in a safe industry.

• For the public the risk is considered to be 1/10th of the workers

• The average dose received by a radiation worker is below 1 mSv/annum i.e. below 1/20th of the prescribed limit

Note:

• The risk is estimated on the basis of Linear No Threshold (LNT) Model.

• The deleterious effects of ionising radiation is yet to established at low doses.

• The genetic effects w.r.t. radiation exposure in human beings is yet to be established.

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System of Radiological Protection

• Type of exposure situations – Planned exposures – Emergency exposures – Existing exposure situations

• Categories of exposures – Occupational exposure – Public exposure – Medical exposure

• Identification of exposed individuals – Workers – Members of public – Patients and comforters

Categories of Exposure…

• Occupational Exposure: Rradiation exposure of workers incurred as a result of their work during use of radiation sources (radioactive material and radiation generating equipment).

Dose Limit: As per AERB Directive 01/2011

Adult Occupational Dose Limits

Whole Body (everything except extremities)

30 mSv maximum per year

20 mSv averaged over 5 years

Extremities

500 mSv per year

Skin of the Whole Body

500 mSv per year

Lens 150 mSv

(New limit 20 mSv/y)


• Public Exposure:

Public exposure encompasses all exposures of the public other than occupational exposures and medical exposures of patients.

Public Dose Limits

Whole Body (everything except extremities)

1 mSv per year

Extremities

50 mSv per year

Skin of the Whole Body

50 mSv per year

Lens 15 mSv

Annual average exposures (mSv) for the year 2014 in India

Source/Practice Average annual effective dose (mSv)

Diagnostic X-rays 0.8

Radiation therapy 0.55

Nuclear Medicine 0.9

Industrial Radiography and Radiation processing 1.41

Research 0.37


• Medical Exposure: As per RPR 2004

"medical exposure" means exposure incurred by -

(i) patients as part of their own medical diagnosis or treatment;

(ii) persons, other than occupationally exposed, while knowingly and willingly helping in the support and comfort of patients; and

(iii) volunteers in biomedical research.


• Medical Exposure:

• Dose limits do not apply to medical exposures.

• Diagnostic reference levels

• Dose constraints for comforters and carers???

• Dose constraints for comforters and visitors of patients:

5 mSv for adults and 1 mSv for children.

• Diagnostic Reference levels / Guidance Levels

(Radiography, Fluoroscopy, CT & Cardiology procedures, Nuclear Medicine)

Personnel monitoring requirements (Rule 27b)

• The workers shall be subjected to personnel monitoring and health surveillance and appropriate records shall be maintained.

Records of workers (Rule 24)

(1) Every licensee shall maintain complete and up-to-date records of -

(a) personnel monitoring (b) the health surveillance (2) Such records shall be preserved during the working

life of each worker, and afterwards until the worker attains or would have attained the age of Seventy five years, or not less than thirty years after the termination of the work involving occupational exposure whichever is later.

(3) A worker shall have access to his personnel monitoring and the health surveillance records.

Classified worker (Rule 18)

The employer shall designate as classified workers, those of his employees, who are likely to receive an effective dose in excess of three tenths of the average annual dose limits notified by the competent authority and shall forthwith inform those employees that they have been so designated.

Health surveillance of workers (Rule 25)…

(1) Every employer shall provide the services of a physician with appropriate qualifications to undertake occupational health surveillance of classified workers.

Health surveillance of workers

(2) Every worker, initially on employment, and classified worker, thereafter at least once in three years as long as the individual is employed, shall be subjected to the health surveillance such as -

(a) special tests or medical examinations as specified by order by the competent authority, for workers who have received dose in excess of regulatory constraints; and

(b) counselling of pregnant workers.

Directives in the cases of exposures in excess of regulatory constraints (Rule 28)…

(1) When, in the opinion of the competent authority, any worker has exceeded the dose constraints, the competent authority may, without prejudice to other course of action available, issue appropriate directives for controlling further exposure and the employer shall comply with the directives.

Directives in the cases of exposures in excess of regulatory constraints…

(2) If a worker discontinues radiation work under the directives of the competent authority issued under this rule, the employer shall assign alternative work not involving exposure to radiation, until the competent authority is satisfied about the fitness of the worker to resume radiation work.

(3) The employer shall comply with restrictions, if any, that the competent authority may impose in this regard.

Reporting of suspected excessive exposure (EE)

If in a reporting period, the dose received exceeds 10 mSv, the same needs to be reported and investigation is required.

Issues while dealing with EEs

→ Delays in receipt of TLD badges from user institutions (especially Oct-Dec quarter)

→ time required in processing of TLDs

→ time required in reporting excessive exposures to Excessive Exposure Investigation Committee (EEIC)

→ time required in establishing dose, owing to information collection (CA Test, explanation from individual etc;)

→ time required for information to be updated into National Occupational

Dose Registry Section (NODRS),

RP&AD, BARC

→ Reporting to AERB.

Steps initiated for a speedier mechanism

A) Faster Information gathering from NODRS

B) Graded approach in dealing with excessive

exposures.

– 10-20mSv

– 20-30mSv

– 30-100mSv

– >100mSv

Graded approach adopted

• 10-20mSv: – Issue letter by AERB cautioning the institution.

– Await explanation for lead correction ( 15 days)

– Check for TLD pattern (genuine/non-genuine)

– Assign the dose as per AERB Guidelines

• 20-30mSv: – Review by RSD internal committee

– Issue a warning letter.

– Await explanation ( 1 month) before assigning dose.

• 30-100mSv: Review by RSD, AERB committee

• >100mSv: – Priority review by present >50mSv committee

– Inspection of the facility on priority or in the annual schedule by RSD members

– Requirement of CA test can be decided based on Committee review and/or inspection.

Actions of AERB for expeditious investigation and to avoid recurrences of EE

• Constitution of regional committees at two RRCs of AERB • Advised RP&AD to take up CA examination on fast track • Circular issued by AERB to each institution where EE has

occurred in regard to prevent misuse of TLDs • Guidelines issued to all Radiation facilities for proper use of

TLDs to avoid non-genuine OEs • Inspection/Investigations carried out at many facilities by

making visit to the radiation facility • A working group being constituted within RSD to investigate

all EE cases and consolidated report to be submitted for review.

• Emails sent to more than 14000 individuals in diagnostic radiology practice guiding for proper use of TLD badges till date.

Genuine radiation exposures expected to be received in

diagnostic procedures

• Fluoroscopy ( Cath-lab/ C-arm/R&F): – 0.05mSv/cardiac procedure translates to 15mSv/ 3 months. Highly likely to exceed the

annual dose limit.

– Cardiac procedures has the highest radiation generation as compared to other

procedures.

– This is assuming lead apron has been worn at all times, which is normally the case.

• Radiography: Without protection and working at 1 m distance, operator

could receive nearly 80-100mSv/ year, for a busy centre.

• CT: Similar situations as a patient facilitator/ employee for CT. This

might specifically occur in Operation Theatres.

• Dental: Design fault possible, leading to high leakage radiation levels

owing to extensive manufacturing of tube housing for shielding in local

industries.

• Manufacturer: Not having proper work culture

Reasons for non-genuine exposures in diagnostic radiology

-Improper use of TLD

- Instances of TLD placed on equipment

- Use of TLD without filter

- Leaving the TLD near x-ray primary beam.

-Positive on CA test could mean

• Exposures for individual’s medical exam

• High level of uncertainty involved near 100mSv ( as

per discussions with bio-dosimetry group, BARC)

Issues under review….

• e-LORA module presently limited applicability - few

registered institutes -Hence, both paper and electronic

processing will have to be present.

• Very difficult to lay-off medical practitioners

>100mSv/qtr.

• Institutions where there was an excessive exposure to

be included as part of inspection schedule of AERB.

• Rationale in issuance of TLD badges in medical

practice to be firmed up . ( practice already followed in

Industry)

Exposure during emergency

Reference level

• Normally it should not be more than 100 mSv

• For life saving activities: 500 mSv


• Response organizations and employers shall ensure that emergency workers who undertake actions in which the doses received might exceed 50 mSv do so voluntarily (BSS).


• Workers who receive doses in an emergency exposure situation shall not normally be precluded from incurring further occupational exposure. However, qualified medical advice shall be obtained before any further occupational exposure if such a worker has received a dose exceeding 200 mSv or at the request of the worker (BSS).

Training programme for RSOs

44

Name of the

course

Conducted by No. of

courses

No.

Candidates

per course

duration

No. of

Person

Trained per

year

RSO Certification

* for Radiotherapy

Applications

RP&AD, BARC 16 5-30 1-2 years ~70

RSO Certification

# for Nuclear

Medicine

Applications

RP&AD, BARC 16 2-12 1-3 ~80

RSO

Certification in

Diagnostic

Radiology (Only

for Service

Engineers)

RP&AD, BARC 5 15-30 Two wks 45-100

Conclusion

• Overall occupational doses in medical applications of radiation are found to be much below the prescribed annual effective dose limits.

• However, the concern is that number of excessive exposure incidents to workers in the monitoring period are being reported in medical practices such as diagnostic radiology and nuclear medicine.

• The Safety Culture need to be established in the institution and further maintained all the times to ensure that dose constraints are not exceeded and importantly PMS badges are properly used.

• The Licensee is solely responsible for ensuring enforcement of safe procedures for handling of radiation sources and their secure storage when not in use.

30th June 2015 46

overview of occupational radiation safety in hospital, dr. avinash u. sonaware

Health & Medicine