Personnel monitoring by musa. Y dambele.pptx

Radiation science

1. Individual Monitoring Musa Y. Dambele Nuclear Medicine Unit/ Radiation Protection and Dosimetry Unit Dept. of Medical Radiography Bayero University, Kano 1

2. Legal requirements Regulation 47 -(1) Every employer shall ensure that – (a) in respect of each of his employees who is designated as a classified person, an assessment is made of all doses of ionizing radiation received by such employee which are likely to be significant; and 2

3. Regulations 47 (2): For the purposes of paragraph (1) of this regulation, the employer shall make suitable arrangements with one or more authorised dosimetry service providers for - (a) the making of systematic assessments of such doses by the use of suitable individual measurement for appropriate periods or, where individual measurement is inappropriate, by means of other suitable measurements; and (b) the making and maintenance of dose records relating to each classified person. 3 Legal requirements

4. Regulations 47: (3) For the purposes of paragraph (2) (b) of this regulation, the arrangements that the employer shall make with the authorised dosimetry service provider shall include requirements for that service to – (a) keep and submit to the Authority, quarterly records made and maintained pursuant to the arrangements or a copy thereof until the person to whom the records relates has or would have attained the age of 75 years or for at least 50 years from when they were made, whichever is earlier; 4 Legal requirements

5. What is Personnel Monitoring Program A systematic process for monitoring, recording, evaluating, and reporting the radiation doses received by occupationally exposed individuals

6. 6 Purpose of Personnel Monitoring To ensure compliance with established dose limits To keep radiation doses a s l ow a s r easonably a chievable (ALARA)

7. 7 Monitoring Criteria Any occupationally exposed individual who is likely to receive a dose in excess of 10% of any applicable limit Any occupationally exposed individual who is likely to receive an intake of radioactive material in excess of 10% of the annual limit on intake (ALI) Any person entering a high radiation area or very high radiation area

8. 8 Individual monitoring Individual dose monitoring shall be undertaken for workers who are normally exposed to radiation in controlled areas: Radiographers, radiologists, medical physicists, the RSO, and nurses Other frequent users of X Ray systems and those working regularly in supervised areas, or occasionally in controlled areas should have personal doses assessed such as endoscopists, anaesthetists, cardiologists, surgeons etc., as well as ancillary workers who frequently work in controlled areas, shall also be monitored.

9. Individual monitoring Two categories of personal monitoring: External: the measurement of dose due to sources outside the body Internal: the measurement of dose due to sources inside the body 9

10. Personal Dosimeters – (External monitoring) Types of external personal dosimeters Passive dosimeters: Photographic Film Thermoluminescence Optically Stimulated Luminescence Nuclear Track Emulsions etc Active dosimeters: Electronic Dosimeters Pocket Dosimeters 10

11. 11 Personal dosimetry Several personal dosimeters are recommended From: Avoidance of radiation injuries from interventional procedures. ICRP draft 2000

12. whole body extremity 12 Use of personal alarm and TLD

13. Personal Alarms Real time read-out of dose Audible alarm at pre-set levels (dose or dose rate) Used where potential dose rates are high, eg radiography, radiation emergencies, source replacement 13

14. Internal Dosimetry Assess intake Calculate dose Biological dosimetry Whole body monitoring Thyroid monitoring Personal air sampling 14

15. Assessing intake Direct measurement of intake 15

16. Dosimeter placement The dosimeter should be placed in a position representative of the most highly exposed part of the surface of the torso. Normally on the front of the body 16

17. Dosimeter placement Body locations representing skin and whole body are usually not the same. When fields are highly non-uniform, additional dosimeters on other parts of the body may be useful. 17

18. Dosimeter placement In special situations (eg. medical radiology where protective clothing such as lead aprons are used), more than one dosimeter may be used: one under the protective apron, and one on unshielded parts of the body to provide information on the exposure to the unshielded part of the body (skin, eye, etc). 18

19. Dosimeter placement When protective clothing is worn, the dosimeter should be worn at the position where the skin is likely to be most seriously exposed (i.e. either under the clothing or at the unprotected part of the body). If the exposure is inhomogeneous, it may be necessary to use more than one dosimeter. 19

20. Exposure to the lens of the eye H P (3) can be assessed from the indication of H P (10) and H P (0.07). Dosimeters used for this purpose should be worn near the eyes (e.g. on the forehead or on a cap). If H P (10) and H P (0.07) are below the relevant dose limits, the value of H P (3) will nearly always be below the dose limit for the lens of the eye (150 mSv). Dosimeter placement 20

21. 21 Individual monitoring when a lead apron is used The dosimeter should be worn under the apron for estimating the effective dose The other body areas not protected by the apron will receive higher dose One dosimeter worn under the apron will yield a reasonable estimate of effective dose for most instances In case of high workload (interventional radiology) an additional dosimeter outside the apron should be considered by the RSO

22. 22 Individual monitoring when a lead apron is used When expected doses are high , two dosimeters are required: 1 under the apron at waist level 1 over the apron at collar level The effective dose E is given by: E = 0.5 Hw + 0.025 Hn where: Hw : dose at waist level under the apron Hn : dose recorded by a dosimeter worn at neck level over the apron Note : The thyroid shielding allows 50% reduction of the E The dosimeter worn over the apron at collar level gives also an estimation of thyroid and eye lens doses

23. 23 Special aspects of individual monitoring In case of loss of a dosimeter, the dose estimation may be carried out from: recent dose history, co-workers dose or, workplace dosimetry Individual monitoring devices should be calibrated Laboratory performing personnel dosimetry should be approved by the regulatory authority

24. Individual monitoring Objectives control of radiation exposure assesses ALARA identifies high doses assessment of working practices Fulfilling legal requirements 24

25. Demonstration of good working practices, including adequacy of: supervision training engineering standards 25 Individual monitoring Objectives

26. Estimation of the actual radiation exposure of workers, to demonstrate compliance with legal requirements. Evaluation and development of operating procedures. Provision of information that may help motivate workers to reduce exposure. 26 Individual monitoring Objectives

27. Provision of information for evaluation of dose following an accident. Data for medical purposes. Provision of data for use in epidemiological studies. Risk-Benefit analyses. 27 Individual monitoring Objectives

28. Health surveillance Objectives to assess fitness of workers for radiation work to provide baseline of information to support management of overexposed workers Periodic medical reviews Health Records 28

29. Personal monitoring period Depends on the exposure situation. A week to a month is often convenient. More than 1 month may be undesirable, since it is more difficult to determine the reason for an exposure with time. 29

30. Personal monitoring period For people who usually do not receive a measurable dose, a 3 month monitoring period may be suitable. Direct reading dosimeters should be worn in addition to the official dosimeter, if daily monitoring is required. 30

31. Record keeping Records of dose received to be kept Records to include: Personnel data (gender, age, ...) Nature of work Dose information and means of assessment Dates and relevant employer Doses received during emergencies to be identified Must exchange information when employee exposed to source under another employer’s control) 31

32. Dose records Must be available to Worker Supervisor of health surveillance programme Regulatory authority New employer After the employee’s working life Records to be kept to 75 th Birthday, or to 30 years from cessation of radiation work. 32

33. 33 Dose Assessment Evaluation of dose is an important aspect of radiation protection It is important that workers return dosimeters on time for processing Delays in the evaluation of a dosimeter can result in the loss of the stored information Licensees should make every effort to recover any missing dosimeters

34. Reference levels Reference level - predetermined value for: any of the quantities, which requires a certain course of action if, the value of the level for a quantity is exceeded. Reference levels often refer to effective dose , but may apply to other quantities These are called derived reference levels A reference level is not a limit in itself. The reference level action may range from just recording the value to intervention. 34

35. Reference levels Recording level Investigation level Action level 35

36. Recording level Value of dose equivalent, detected activity above which a result should be retained The recording level should be based on: 1/10 of the fraction of the annual limit, corresponding to the period of time of which the individual monitoring measurement refers about 0.17 mSv for monthly monitoring periods A result smaller than the recording level may be discarded and treated as zero in assessing the dose 36

37. Investigation levels Investigation level - a value of dose equivalent or intake, usually for a single measurement, above which the result justifies further investigation. It is often appropriate to set the investigation level at 3/10 of the fraction of the relevant annual limit corresponding to the individual monitoring period. 37

38. Investigation levels For monthly monitoring or exchange periods, IL= 20 mSv x 0.3 / 12 = 0.54 mSv Below the investigation level, further review is not needed. It may be necessary to change investigation levels, for example as conditions in a workplace change. 38

39. Action level Level that for remedial or protective action. Applies to chronic exposure or emergency exposure situations. Action levels often serve to protect the public. Have occupational exposure relevance in chronic exposure situations. Particularly relevant to workplace radon exposure. 39

40. Employer The employer should: Provide workers access to information in their own exposure records; Provide access to the exposure records by the supervisor of the health surveillance programme, the Regulatory Authority and the relevant employer; and Facilitate the provision of copies of workers' exposure records to new employers 40

41. Worker Usually through his employer A simplified version of the full dose record is appropriate. Partly because the transcript may contain unrecognizable computer terminology On termination of employment, a summary of the dose record may be given to the worker Covers the period of last employment and dose information transferred from previous employment 41

42. Organizations Dose reporting may be required to: Employer (radiation safety officer/management) Radiation worker Local safety inspector Medical officer National legal authorities/inspectorates. 42

43. Summary Controlled areas Supervised areas Local Rules Supervision of the work (RSO) Use of radiation monitors dose rate, contamination Testing, record keeping Individual monitoring – external exposure Individual monitoring – intakes Individual monitoring objectives Record keeping & Dose assessment Reference levels Health Surveillance 43

44. Conclusion Personal Monitoring ensures: control over individual dose to be exercised abnormally high doses to be identified changes in working conditions to be identified poor working practices to be identified legal evidence to be provided security and confidence 44

45. Conclusion Personal monitoring is an essential Technical Service: to authorized radiation users to the Regulatory Authority Accredited Dosimetry Service provider should be engaged Dosimeter should be worn Properly Dose Record Analysed properly 45