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RADIATION PROTECTION

Chapter 9

ORGANIZATIONS, STANDARDS, AND PHILOSOPHY

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Objectives

Identify key organizations that recommend dose limits

Identify organizations that set standards

Define the philosophy of radiation protection

Know the occupational and public radiation protection limits

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Key Scientific Organizations

International Commission on Radiological Protection (ICRP)

International Atomic Energy Agency (IAEA)

International Commission on Radiological Units and Measurements (ICRU)

National Council on Radiation Protection and Measurements (NCRP)

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Other International Organizations United Nations:

International Labor Organization

World Health Organization

Food and Agriculture Organization

Issue recommended “safe practices” guidelines. They do not have authority to require adoption of their recommendations.

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Environmental Protection Agency Radiation protection

guidelines Environmental radiation

standards and regulations Federal radiation council Surveillance of air, food

and water

Organizations that Establish and Implement Radiation Protection Standards

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Organizations That Establish and Implement Radiation Protection Standards Nuclear Regulatory Commission

regulates nuclear energy industry (commercial sector)

power reactors fuel manufacturers spent-fuel processing waste management production and use of

radioisotopes in research, medicine, industry

issues regulations to comply with EPA standards.

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U.S. Department of Energy Standards for Department of

Energy Facilities 10 CFR 834, 835 Regulatory Authority Being

Challenged Military

?

Organizations that Establish and Implement Radiation Protection Standards

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Food and Drug Administration Center for Devices and

Radiological Health (CDRH) responsibility for developing safety

standards for sources not controlled by NRC (e.g., naturally occurring or accelerator produced radionuclides)

X-ray generators regulations apply to manufacturers do not have the force of law, but

may be adopted by states

Organizations that Establish and Implement Radiation Protection Standards

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The States NRC can delegate certain health

and safety responsibilities to states

~ 1/2 of states are “agreement” Municipalities

large cities (e.g., New York) may have authority to regulate radiation sources

Organizations that Establish and Implement Radiation Protection Standards

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Department of Transportation regulations governing

shipment of radioactive materials.

NRC enforces

Organizations that Establish and Implement Radiation Protection Standards

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The Philosophy of Radiation Protection

Justification

Optimization

Dose limitation

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Categories of Exposure

Occupational Exposure pregnant workers all other radiation

workers Members of the General

Public Medical Exposure

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Dose Calculation Method

How do you compare doses delivered to different parts of the body?

Uniform whole body irradiation (Most likely) external source Gamma emitter

Non uniform irradiation (Most likely) internal source , , , N, x-ray or other

source

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External Dose

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Dose Equivalent (H)

Biological response varies by radiations

Radiation weighting factors used to provide a common scale:

DT,R is absorbed dose

T is tissue (organ) R is radiation type R WR is radiation

weighting factor

R

RTRT DwH ,

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Effective Dose Equivalent (HE)

Different tissues respond differently to same radiation dose

Tissue weighting factors used to provide a common scale:

HE is the effective dose equivalent

WT is the tissue weighting factor

T

TTE HwH

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Effective Dose Equivalent, continued

Take dose equivalent for each organ

Multiply by radiation risk factor, WT

Sum to get “effective dose equivalent” for the entire body:

Where HT is the tissue (organ) dose equivalent

TT

TE HWH

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Tissue Weighting Factors WT

*

Tissue or Organ

Tissue Weighting Factor, WT

Gonads 0.25

Bone Marrow (red)

0.12

Lung 0.12

Breast 0.15

Thyroid 0.03

Bone Surface 0.03

Remainder 0.30

*From ICRP 20, ICRP-60 values and tissues are different

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So… Biological Dose Today

Measure Exposure (X or roentgen) or Absorbed dose (rad, Gy)

Calculate Dose equivalent for each effected

organ (Gy*WR) Result expressed in rem, Sv

Multiply Each organ dose by organ-specific

radiation risk factor (Sv*WT) Sum “risk” weighted organ doses

Result listed as “effective dose equivalent” (rem, Sv)

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Occupational Exposure Limits

To prevent nonstochastic effects: 0.15 Sv (15 rem) lens of the eye 0.5 Sv (50 rems) all other

tissues To limit stochastic effects:

Dose-equivalent limit from uniform whole body irradiation is 50 mSv (5 rem) in 1 year

Effective dose-equivalent from nonuniform irradiation 50 mSv (5 rem) in 1 year

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Exposure of General Public

For routine releases from sites: 1 mSv (100 mrem) per year Occasional 5 mSv (500 mrem)

per year if average < 1 mSv Remediated sites:

0.15 mSv (15 mrem) per year e.g., Decommissioned reactors,

waste sites etc. Air emissions:

0.1msv (10 mrem)

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Medical Exposure Limits

None Exposures must be justifiable

on the basis of benefits to the patient