ALARA in Radiography...Isotope Use Isotope Half Life Gamma Energy Range Approximate Steel Working...
Transcript of ALARA in Radiography...Isotope Use Isotope Half Life Gamma Energy Range Approximate Steel Working...
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ALARA in RadiographyALARA in Radiography
Michael Fulleron behalf of the
International Source Suppliers and Producers Association (ISSPA)
Michael Fulleron behalf of the
International Source Suppliers and Producers Association (ISSPA)
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In the Beginning
Ra‐226
“Fish Pole” Technique
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Time – Distance – Shielding
COLLIMATOR
FILM
ShieldingDepleted Uranium (DU)
Tungsten, LeadUse of bunkers
Distance10 meters (user to projector)
7 meters (projector to exposure point)
TimeHigh Activity Sealed Source (HASS)
Film optimization
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Many Flavors
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Source Styles
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Isotope Use
Isotope Half Life Gamma Energy RangeApproximate Steel Working Thickness
Gamma Constant R/h (mSv/h) per Ci@ 1 meter
Half Value Layer of Lead cm (in)
Co‐60 5.27y 1.17 and 1.33 MeV 50 ‐ 150 mm 1.368 (13.68) 1.27 (0.5)
Ir‐192 74d 206 ‐ 612 keV 12 ‐ 63 mm 0.591 (5.91) 0.51 (0.2)
Se‐75 120d 97 ‐ 401 keV 3 ‐ 29 mm 0.826 (8.26) 0.1 (0.039)
Yb‐169 32d 63 ‐ 308 keV 2 ‐ 20 mm 0.327 (3.27) 0.08 (0.032)
Cs‐137 30y 662 keV 12 ‐ 63 mm 0.376 (3.76) 0.64 (0.25)Tm‐170 129d 52 ‐ 84 keV 2 ‐ 15 mm 0.006 (0.06) 0.61 (0.24)
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Isotope Use – Example: 60Cobalt
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Isotope Use
Isotope Half Life Gamma Energy RangeApproximate Steel Working Thickness
Gamma Constant R/h (mSv/h) per Ci@ 1 meter
Half Value Layer of Lead cm (in)
Co‐60 5.27y 1.17 and 1.33 MeV 50 ‐ 150 mm 1.368 (13.68) 1.27 (0.5)
Ir‐192 74d 206 ‐ 612 keV 12 ‐ 63 mm 0.591 (5.91) 0.51 (0.2)
Se‐75 120d 97 ‐ 401 keV 3 ‐ 29 mm 0.826 (8.26) 0.1 (0.039)
Yb‐169 32d 63 ‐ 308 keV 2 ‐ 20 mm 0.327 (3.27) 0.08 (0.032)
Cs‐137 30y 662 keV 12 ‐ 63 mm 0.376 (3.76) 0.64 (0.25)Tm‐170 129d 52 ‐ 84 keV 2 ‐ 15 mm 0.006 (0.06) 0.61 (0.24)
Isotope Half Life Gamma Energy RangeApproximate Steel Working Thickness
Gamma Constant R/h (mSv/h) per Ci@ 1 meter
Half Value Layer of Lead cm (in)
Co‐60 5.27y 1.17 and 1.33 MeV 50 ‐ 150 mm 1.368 (13.68) 1.27 (0.5)
Ir‐192 74d 206 ‐ 612 keV 12 ‐ 63 mm 0.591 (5.91) 0.51 (0.2)
Se‐75 120d 97 ‐ 401 keV 3 ‐ 29 mm 0.826 (8.26) 0.1 (0.039)
Yb‐169 32d 63 ‐ 308 keV 2 ‐ 20 mm 0.327 (3.27) 0.08 (0.032)
Cs‐137 30y 662 keV 12 ‐ 63 mm 0.376 (3.76) 0.64 (0.25)Tm‐170 129d 52 ‐ 84 keV 2 ‐ 15 mm 0.006 (0.06) 0.61 (0.24)
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Selenium 75 Benefits / Drawbacks
Benefits• Lower energy – easier to shield
• Softer gamma spectrum – better image quality
• Lower gamma constant – reduced exclusion zone size
• Longer half‐life than Ir‐192
Drawbacks• Lower energy – less penetration
• Elemental selenium highly volatile
• More expensive than Ir‐192
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SCAR Technology
SCAR = Small Controlled Area Radiography
also marketed as
SAFER (Small Area for Exposure Radiography)
or
Close Proximity Radiography
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Close Proximity / SCAR Not New
Removable Shutter Rotating Shutter
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Close Proximity / SCAR Benefits
20 mSv/h boundary for 100 Ci Ir‐192 source ≈ 150 meters
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Design Inputs
Regulatory National / International Standards
Customer InputIndustry EventsAvailable TechnologyManufacturing Costs
Operational Safety Transportation Safety
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Conflicting Desires
User RegulatorDevice needs to be as light
as a featherLoaded device should have
zero radiation leakage≠
Regulator ManufacturerNo Depleted Uranium DU offers best shielding≠
User RegulatorSimple to operate Foolproof≠
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Conflicting Desires
U.S. User Some non‐U.S. UsersHigher activity sources mean
shorter exposure timesCannot use sources above XX
curies≠
User PhysicsSource and/or device needs
to last foreverEverything has a finite
operational life≠
User ManufacturerFree How much money do you have?≠
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Product Adoption
• Can the product be priced to recover development costs, manufacturing costs, and at the same time be enticing to buyers?
• Will the customers require a new license or change to existing license?• Will the new product require significant training for the customer?• Will the new product change traditional radiography methods or results?• Will the new product obsolete existing accessories?• Will the new product a provide a marked improvement (operational, compliance)?
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ALARA Implementation
Exposure ALARA is primarily dictated through regulatory requirements.
Designs developed with many inputs, including regulatory.
SCAR technology seeing some adoption.
Selenium‐75 use is on the rise.
Training and incorporation of a safety culture