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Overview of occupational radiation safety in hospital, Dr. Avinash u. Sonaware

Overview of occupational radiation safety in hospital

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Overview of occupational radiation safety in hospital, Dr. Avinash u. Sonaware

  1. 1. Overview of Occupational Radiation Safety in Hospital Dr. Avinash U. Sonawane Head, Radiological Safety Division Atomic Energy Regulatory Board
  2. 2. 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
  3. 3. 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
  4. 4.  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
  5. 5.  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
  6. 6. 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
  7. 7. 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
  8. 8. 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
  9. 9. 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
  10. 10. • 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)
  11. 11. 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
  12. 12. 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
  13. 13. 13 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
  14. 14. 14 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.
  15. 15. 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.
  16. 16. 16 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
  17. 17. 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
  18. 18. 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)
  19. 19. Categories of Exposure… • Public Exposure: Public exposure encompasses all exposures of the public other than occupational exposures and medical exposures of patients.
  20. 20. 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
  21. 21. 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
  22. 22. Categories of Exposure… • 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.
  23. 23. Categories of Exposure… • Medical Exposure: • Dose limits do not apply to medical exposures. • Diagnostic reference levels • Dose constraints for comforters and carers???
  24. 24. • 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)
  25. 25. Personnel monitoring requirements (Rule 27b) • The workers shall be subjected to personnel monitoring and health surveillance and appropriate records shall be maintained.
  26. 26. 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.
  27. 27. 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.
  28. 28. 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.
  29. 29. 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.
  30. 30. 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.
  31. 31. 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.
  32. 32. 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.
  33. 33. 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.
  34. 34. 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
  35. 35. 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.
  36. 36. 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.
  37. 37. 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
  38. 38. 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)
  39. 39. 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)
  40. 40. Exposure during emergency Reference level • Normally it should not be more than 100 mSv • For life saving activities: 500 mSv
  41. 41. Exposure during emergency • 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).
  42. 42. Exposure during emergency • 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).
  43. 43. 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
  44. 44. 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.
  45. 45. 30th June 2015 46