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Industrial Radiography Occupational exposures and protection

Industrial Radiography Occupational exposures and protection. A. H. Mehrparvar, MD Occupational Medicine department Yazd University of Medical Sciences. History. 500 BC : Democritus postulates that all matter is made of indivisible units they call " atomos ."

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Industrial Radiography Occupational exposures and protection

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  1. Industrial RadiographyOccupational exposures and protection A. H. Mehrparvar, MD Occupational Medicine department Yazd University of Medical Sciences

  2. History • 500 BC:Democritus postulates that all matter is made of indivisible units they call "atomos." • 1895 (Nov 8):Roentgen discovers X-rays. • 1896: First diagnostic X-ray in US (E. Frost) • 1896:Thomas Edison reports eye injuries from X-rays • 1896: First therapeutic applications of X-rays Many nobble prizes in this issue

  3. Types of radiation • Ionizing • Electromagnetic energy • X-ray • Gamma ray • Subatomic particles • Electron • Proton • Neutron • Non-ionizing • infrared, visible, microwaves, radar, radio waves, lasers

  4. Radiation wavelength in angstrom units 8 6 4 2 -2 -4 -6 10 10 10 10 1 10 10 10 Radio Infrared V Ultra-Violet X-Rays Cosmic Rays i Light s i b l e Gamma Rays 4 - 10 -8 -6 -4 -2 2 2 2 10 10 10 10 10 1 10 10 Photon energy in million electron volts (MeV) Radiation spectrum

  5. Definitions • Radioactivity (Bq, Ci) • LET (linear energy transfer) (kev/μm) • Absorbed dose (Gy, Rad) • Equivalent dose (Sv, Rem) • Effective dose (Sv, Rem)

  6. Radiation Units:

  7. Total exposure Man-made sources Medical X-Rays Radon 55.0% 11 Other 1% Internal 11% Consumer Products 3% Man-Made 18% Nuclear Medicine 4% Cosmic 8% Terrestrial 6%

  8. Aircrew Dental worker Radiologist Radiology technicians Reactor worker Electron microscopist Industrial radiographer Plasma torch operators High-voltage TV repairman Underground Uranium miner Atomic power plant worker Occupational exposure

  9. Organ excposures

  10. Radiation Sources x-ray generators gamma ray sources

  11. Imaging Modalities Several different imaging methods are available to display the final image in industrial radiography: • Film Radiography • Digital radiography • Real Time Radiography • Computed Tomography (CT) • Computed Radiography (CR)

  12. Industrial Radiography • Application: use of radiography for the non-destructive testing (NDT) of items • a means of checking the physical integrity of equipment and structures such as vessels, pipes, welded joints, castings and other devices

  13. Industrial radiography (cont.) • Sensitive to changes in thickness, corrosion, cracks, and material density changes • Technique is not limited by material type or density • Can inspect assembled components • Detects both surface and subsurface defects • Provides a permanent record of the inspection • often carried out under difficult working conditions, such as in confined spaces, extreme cold or high temperatures.

  14. Radiographic Images

  15. Radiographic Images

  16. Radiographic Images

  17. Radiation Bioeffects • Deterministic (non-stochastic) • Severity increases with radiation dose • Threshold: 50-100 rem • Dose and dose rate dependent • Examples • Cataract induction • Epilation (hair loss) • Erythema (skin reddening) • Blood changes

  18. Radiation Bioeffects • Stochastic (probabilistic) • Probability of occurrence increases with radiation dose • Threshold: 10 rem, but regulatory models assume no threshold (ALARA!) • Examples • Cancer induction • Genetic mutations • Developmental abnormalities

  19. Deterministic Radiation Effect Thresholds HEALTH EFFECT ORGAN DOSE (rem) Temporary sterility Testis 15 Nausea GI 35 Blood cell depression Bone marrow 50 Reversible skin effects Skin 200 Permanent sterility Ovaries 250 - 600 Vomiting GI 300 Temporary hair loss Skin 300 - 500 Permanent sterility Testis 350 Skin erythema Skin 500 - 600

  20. Stochastic Radiation Effects • Cancer • incidence begins to increase in populations acutely exposed to more than 10 rem • continues to increase with increasing dose • Genetic Effects • more than 100 rem of low-dose rate, low LET radiation needed to double the incidence of genetic defects in humans • no human hereditary effects seen at gonadal doses less than 50 rem • In Utero Irradiation • developmental and other effects begin to increase at 10 rem

  21. Short Term ARS Hemopoietic (bone marrow syndrome) 100-1000 rad 25 rad can depress blood count Gastointestinal (600-1000 rad) CNS (5000 rad) Locally Erythema 300-1000 rad Epilation Delay/suppress menstruation 10 rad LONG TERM Cataract Reduced fertility Fibrosis Organ atrophy Sterility Cancer Embryologic effects Somatic effects

  22. Biologic effects of radiation on pregnant women • Spontaneous abortions during first 2 weeks of pregnancy-- 25 RAD or higher • 2nd week to 10th week – major organogenesis –IF radiation is high enough can cause congenital abnormalities • Principle response after that may be malignant disease in childhood

  23. Tissue sensitivity

  24. Radiation workers • Any person working with radioactive substances • two groups of radiation workers: • Group A: worker can receive more than 30% of the annual dose equivalent limit, must undergo routine medical examinations and have personal monitoring devices. • Group B: radiation worker will not receive more than 30% of the annual dose equivalent limit, do not undergo medical examinations or have to carry monitoring devices.

  25. Occupational exposure limits

  26. Occupational exposure limits (cont.)

  27. Action Level of 1.0 mSv/y • provide and ensure the proper use by workers of an acceptable dosimeter or radiation badge • perform radiation surveys to measure radiation levels in work areas • provide written instructions on safe and proper procedures and practices related to the use of the radiation-emitting device

  28. Radiation Safety Technicians who work with radiation must wear monitoring devices that keep track of their total absorption, and alert them when they are in a high radiation area Radiation Alarm Radiation Badge Survey Meter Pocket Dosimeter

  29. Ring badge

  30. How to Correctly Wear Your Badge • Whole body badges should be worn between the neck and the waist • Ring badges can be worn on any finger  • The badge should be on the inside of your palm, facing the radioactive work

  31. Protection Two principles: Justification (no exposure) Optimization (ALARA)

  32. ALARA Principle • keep all radiation doses well below the regulatory limits and As Low As Reasonable Achievable (ALARA) • ALARA (as low as reasonable achievable) limits are 10% of these:  • 500 mrem deep • 1500 mrem eye • 5000 mrem shallow extremity

  33. Types of Radiation Exposure • External - from gamma photons, x-rays or high-energy beta particles emitted from a source outside the body • Internal - from sources inside the body, which presumably came to be there following ingestion or inhalation of contamination

  34. Protection Against Internal Exposure • Pathways of contamination: • Inhalation, ingestion, wound, through skin • Minimization • awareness of the hazard • good laboratory technique • use of personal protective equipment (ppe) such as gloves, lab coats and fume hoods • proper and timely performance of surveys for radioactive contamination

  35. Personal Protective Equipment Fume Hood Protective Gloves Lab Coat

  36. Protection Against External Exposure • The three important factors in protecting against external exposure are: • time • distance and • shielding • Judicious use of a combination of these factors can minimize radiation exposure

  37. Radiation Safety There are three means of protection to help reduce exposure to radiation:

  38. Personal protective devices

  39. Shielding • Shields that reduce gamma ray intensity by 50% (1/2) include: • 9cm (3.6 inches) of packedsoil • 6cm (2.4 inches) ofconcrete • 1cm (0.4 inches) oflead • 150 m (500 ft) ofair

  40. Guidelines for protection • There must be at least one person designated as the responsible user or radiation protection officer (RPO) to undertakeresponsibility for: • Proper function and miantanance of equipment • Equipment used and maintained only by competentpersonnel • Correct use of equipment • establishing safe operating procedures • Increasing awareness of staff about radiation rules • investigating any high x-ray exposures received by personnel • ensuring that radiation levels outside controlled areas are belowthemaximum permissible limits

  41. Radiographers should: • Follow the local rules and any other relevant procedures • Properly use radiation monitors • Wear their individual dosimeters, at the correct location at all times during radiography and source handling • Co-operate with the RPO and qualified expert on all radiation safety issues • Participate in any training concerning radiation safety

  42. General requirements • Warning Signs

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