Ch. 10 - Dose Limits for Exposure to Ionizing Radiation

What is an EfD limiting system?

set of numeric dose limits used as an attempt to control known risks

The concept of radiation exposure and of the associated risk of __________ is the basis of the effective dose limiting system.

radiation-induced malignancy

The ___________ is considered the international authority on the safe use of sources of ionizing radiation and provides clear and consistent radiation protection guidance through its recommendations for occupational dose limits, and public dose limits.

International Commission on Radiological Protection (ICRP)

In the U.S., __________ is a nongovernmental, nonprofit, corporation that determines how to implement ICRP recommendations into U.S. radiation protection criteria.

National Council on Radiation Protection and Measurements (NCRP)

In the U.S., we have the _________, which is a federal agency that has the authority to enforce radiation protection standards but does not regulate or inspect x-ray imaging facilities.

Nuclear Regulatory Commission (NRC)

The __________ conducts on-site inspections of x-ray equipment, especially mammographic units.

Food and Drug Administration (FDA)

What is the goal of OSHA?

Enforces workplace safety for radiation outside the nuclear field

What is the difference in an RSC and RSO?

Radiation safety committee (RSC) facilitates ongoing operation of a radiation safety program, Radiation safety officer (RSO) oversees safety program's daily operation & yearly review

Detail some of the basic functions/responsibilities of an RSO

- Develop an appropriate radiation safety program, Oversee daily operations of safety program, Provide formal review of safety program yearly, Ensure the facility's operational radiation practices are such, Review & maintain radiation monitoring records, Be available to provide counseling for individuals.

ALARA concept

As Low As Reasonably Achievable-for radiation workers

What is an alternate name for ALARA?

optimization (ORP)

What is the purpose of the Consumer-Patient Radiation Health and Safety Act of 1981?

helps ensure medical imaging professionals are qualified and protects the public from unnecessary exposure to radiation

What are the 2 categories of radiation induced responses to radiation?

Tissue reactions, Stochastic effects

Give 2 examples of late tissue reactions.

Cataract formation, Organ atrophy

Give 2 examples of early tissue reactions

Skin erythema, epilation

What is a stochastic effect?

non-threshold, randomly occurring biologic somatic changes

At what time during in-utero is the embryo-fetus most at risk for radiation-induced intellectual disability?

8-15 weeks gestation

What is a tissue weighting factor?

number assigned that quantifies relative radiosensitivity of tissues

How do you calculate your lifetime effective dose (cumulative effective dose)?

10 mSv x age in years

What is an action limit?

early warning system; personnel dosimeter readings should be below 1/10 of annual dose limit

Define radiation hormesis

scientific hypothesis that maybe at low doses of ionizing radiation, there's actually a health benefit

NCRP recommendation for occupational exposure:

Annual effective dose limit

50 mSv

NCRP recommendation for occupational exposure:

Cumulative effective dose limit

10 mSv x age in years

NCRP recommendation for occupational exposure:

Lens of eye

150 mSv

NCRP recommendation for occupational exposure:

Localized areas of the skin, hands, & feet

500 mSv

NCRP recommendation for public exposure:

Continuous/frequent

1 mSv

NCRP recommendation for public exposure:

Infrequent

5 mSv

NCRP recommendation for public exposure:

Lens of eye

15 mSv

NCRP recommendation for public exposure:

Localized areas of the skin, hands, & feet

50 mSv

NCRP recommendation for student exposure:

Effective dose limit

1 mSv

NCRP recommendation for student exposure:

Lens of eye

15 mSv

NCRP recommendation for student exposure:

Localized areas of the skin, hands, & feet

50 mSv

NCRP recommendation for embryo & fetus exposure:

Monthly

0.5 mSv

NCRP recommendation for embryo & fetus exposure:

Entire gestation

5.0 mSv

NCRP recommendation for negligible individual dose (annual)

0.01 mSv

Effective dose limiting systems are an attempt to...

control known risk

Basis of effective dose limiting system

associated risk of radiation-induced malignancy

NCRP report that gives specific dose limits

Report No. 116

Radiation protection standards are based on:

risk

Medical imaging professionals' roles

Shared responsibility for patient safety, Knowledge of previous, existing, & new radiation safety guidelines

Radiation protection standards organization (4)

ICRP, NRCP, UNSCEAR, NAS/NRC-BEIR

The ICRP & NCRP are responsible for...

evaluating dose & biological effects

Key roles of:

International Commission on Radiologic Protection (ICRP)

Develops radiation protection principles, Recommends dose limits for occupational & public exposure, Influences national & international regulation.

International Commission on Radiologic Protection (ICRP)

Non-government independent organization that looks at GLOBAL radiation protection- Key source of evidence-based guidance; take data & applies to real world safety practices

National Council on Radiation Protection and Measurements (NCRP)

Nonprofit independent organization that makes radiation protection recommendations for the USA- Bridges gap between science & policy

Key roles of:

National Council on Radiation Protection and Measurements (NCRP)

Advise govt agencies & the public, Interprets & applies ICRP guidance, Develops radiation protection standards, Publishes technical reports & recommendations, Promotes education & public understanding.

United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR)

Looks at effects & levels of ionizing radiation worldwide- One of the most trusted sources of global scientific data; ensures policies are based on science

Key roles of:

United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR)

Collects global radiation exposure data, Assesses radiation health effects, Provides authoritative scientific reports, Informs international standards.

National Academy of Sciences/National Research Council Committee on the Biological Effect of Ionizing Radiation (NAS/NRC-BEIR)

Advisory group that makes recommendations on policies- connects biological research to public health policy

Key roles of:

National Academy of Sciences/National Research Council Committee on the Biological Effect of Ionizing Radiation (NAS/NRC-BEIR)

Review scientific evidence on health effects of radiation, Publish authoritative BEIR reports, Provide scientific basis for U.S. radiation protection policy. Supports the LNT model.

What do ICRP, NCRP, UNSCEAR, & BEIR have in common?

all provide science-based recommendations on radiation protection, but do not make/enforce laws

U.S. regulatory agencies (5)

NRC, Agreement States, EPA, FDA, OSHA

what does the Nuclear Regulatory Commission (NRC) focus on

nuclear energy safety & byproduct materials

What does the NRC do

Issues licenses, conducts inspections, recommends occupational dose limits

What does the NRC regulate

Nuclear materials and facilities

Agreement state's focus

radiation use within the state

What do agreement states regulate

radioactive materials locally

Environmental Protection Agency (EPA) focus:

Focuses on protecting public health & ecosystems

What does the EPA regulate

radon, water, air, and waste contaminations

What does the EPA set

Environmental exposure limits

what does the U.S. Food and Drug Administration (FDA) regulate

Radiation emitting devices

What does the FDA oversee

food irradiation, device labeling standards

What is the FDA's focus?

Patient and consumer safety

what does the Occupational Safety and Health Administration (OSHA) enforce?

workplace safety for radiation outside nuclear fields

What does OSHA cover

Training, protective equipment, exposure limits

What is OSHA's focus

worker safety in healthcare, industry, and research

Facilities providing imaging services must have what?

an effective & detailed radiation safety program

Implementation of an effective radiation safety program

begins with administration of facility, Administration provides necessary resources

RSO job authority

- Identify radiation safety problems, Initiate, recommend, or provide corrective action, stop unsafe operations, Verify implementation of corrective actions.

Radiation control for health and safety act of 1968 is strictly an equipment performance standard. It does not...

regulate the diagnostic x-ray user

Key points:

Code of standards for diagnostic x-ray equipment

- Automatic beam limitation, Filtration Reproducibility & exposure linearity, Beam on indications, Backup times

Code of standards for diagnostic x-ray equipment: why it matters

sets minimum safety standards for all new x-ray equipment

(enforced by FDA)

FDA White Paper purpose

radiation dose management awareness; initiative to reduce unnecessary radiation exposure from medical imaging

Effective dose limiting system looks at (3):

Partial body, Whole body, Individual organs

True / False: The Consumer-Patient Radiation Health and Safety Act of 1981 is not enforceable by federal policies.

True

Current radiation protection guidance is based on...

Genetic & somatic responses, Linear nonthreshold model

Radiography occupational risk of fatality

2.5%

EfD limiting system underlying concept

any organ is vulnerable to damage from ionizing radiation

In 1971, EfD limiting systems only looked at vital organs such as:

the gonads, blood-forming organs, & lung tissue

What is covered in the NCRP Report No. 116?

effective dose limits for occupational workers & the public

How does the NCRP recommend that we calculate cumulative occupational effective dose?

age in years x 10 mSv

What are the 2 explicit objectives of radiation protection?

Decrease late stochastic effects, Decrease genetic effects

True/False: Public Law 90-602 regulates the diagnostic x-ray user.

False- regulates equipment performance standards