Rad 111 lect 3 Radiation Protection/ ALARA Rad lecture

What does ALARA stand for?

As Low As Reasonably Achievable.

What is the main goal of ALARA?

To keep radiation exposure as low as possible while still getting a useful image.

What is ionizing radiation?

Radiation that has enough energy to remove an electron from an atom.

What is nonionizing radiation?

Radiation that does not have enough energy to remove an electron from an atom.

Is ultrasound ionizing or nonionizing?

Nonionizing.

Are x-rays ionizing or nonionizing?

Ionizing.

Does ultrasound need a medium to travel?

Yes, ultrasound needs a medium.

Do electromagnetic waves need a medium to travel?

No, electromagnetic waves do not need a medium.

What type of wave is ultrasound?

A sound wave.

Is ultrasound part of the electromagnetic spectrum?

No.

What does ultrasound cause tissue molecules to do?

Vibrate.

What are two possible biological effects of ultrasound?

Heating tissues and cavitation.

What is cavitation?

The formation and collapse of tiny bubbles in liquid or tissue.

What does a higher Mechanical Index mean?

A greater chance of microbubble disturbance and cavitation effects.

What is the unit used to measure ultrasound frequency?

Hertz.

What does Hertz measure?

Cycles per second, or frequency.

What is the unit of ultrasound power?

Watt.

Why should ultrasound power be kept low?

Because power affects dose.

What is the unit of ultrasound intensity?

W/m² or mW/cm².

What type of radiation are x-rays?

Ionizing radiation.

What are x-rays made of?

Photons.

Why are x-rays ionizing?

They have enough energy to remove electrons from atoms.

What type of radiation is gamma radiation?

Ionizing radiation made of photons.

What type of radiation is beta radiation?

Ionizing radiation made of particles.

What type of radiation is alpha radiation?

Ionizing radiation made of particles.

Are alpha and beta particles part of the electromagnetic spectrum?

No.

Are x-rays and gamma rays photons?

Yes.

What is radioactivity?

The release of radiation from unstable atoms.

What is the standard unit of radioactivity?

Curie.

What is the SI unit of radioactivity?

Becquerel.

What is the SI unit of absorbed dose?

Gray.

What does Gray measure?

Absorbed dose.

What does Sievert measure?

Effective dose or equivalent dose.

What does Becquerel measure?

Radioactivity or activity.

What is air kerma measured in?

Gray.

What does Gy equal?

1 joule per kilogram.

What is the quality factor for alpha particles?

20.

What is the quality factor for x-rays, beta, and gamma rays?

1.

When are rad and rem equal?

When the quality factor is 1 and the whole body dose is being compared.

What is radiation therapy used for?

Treatment.

Does radiation therapy use ionizing radiation?

Yes.

What are the two main biological effects of ultrasound?

Thermal and nonthermal effects.

What is a thermal effect of ultrasound?

Localized heating of tissue.

What is a nonthermal effect of ultrasound?

Cavitation.

What is the safest approach when using ultrasound?

Use the highest frequency possible, lowest power possible, and shortest scan time.

Why should scan time be reduced during ultrasound?

To reduce the chance of tissue heating.

What ultrasound mode is usually lower risk?

B-mode.

When should ultrasound imaging be performed?

Only when medically necessary.

What law explains cell sensitivity to radiation?

Law of Bergonie and Tribondeau.

What four cell characteristics increase radiation sensitivity?

Young age, low differentiation, high metabolic rate, and high cell division.

Are young tissues more sensitive to radiation?

Yes.

Are undifferentiated cells more radiosensitive?

Yes.

Are mature cells more radioresistant?

Yes.

Which cells are very sensitive to radiation?

Basal skin cells, small intestine crypt cells, and germ cells.

Which cells are less sensitive to radiation?

Nerve, muscle, and brain cells.

What are early stages of radiation effects?

Prodromal, latent, and manifest stages.

What happens during the prodromal stage?

Nausea, vomiting, and diarrhea may occur.

What happens during the latent period?

The person may feel okay, but biological changes are occurring.

What happens during the manifest stage?

Recovery or death may occur.

Are early radiation effects usually from normal diagnostic doses?

No, they require much higher doses.

What are short-term somatic effects?

Effects seen within about 3 months.

Give examples of short-term somatic effects.

Erythema, hair loss, and skin ulceration.

What are late effects of radiation?

Effects that develop long after exposure.

What are the two types of late effects?

Somatic and genetic.

What are somatic effects?

Effects that happen in the exposed person.

What are common somatic late effects?

Cataracts and cancer.

What is the most important late effect of radiation?

Cancer.

What are genetic effects?

Effects caused by mutations that may affect future generations.

Are genetic radiation effects common?

No, they are very rare.

What are prenatal effects?

Radiation effects on a fetus during pregnancy.

What organization sets standards for radiation-producing equipment?

Center for Devices and Radiological Health under the FDA.

What does the FDA regulate?

Radiation-producing equipment.

What does the NRC stand for?

Nuclear Regulatory Commission.

What does the NRC help regulate?

Radiation and radioactivity safety and dose limits.

What state agency helps regulate radiation dose limits in Ohio?

Ohio Department of Health.

What is the annual occupational dose limit for radiation workers?

50 mSv per year.

What is the annual dose limit for the general public for frequent exposure?

1 mSv per year.

What is the annual dose limit for infrequent general public exposure?

5 mSv per year.

What is the dose limit for minors?

1 mSv per year or 10% of adult limits.

What is the cumulative dose limit for radiation workers?

10 mSv times the worker’s age.

What is the monthly dose limit for pregnant radiation workers?

0.5 mSv per month.

What is the dose limit for the entire gestation of a pregnant radiation worker?

5 mSv.

Where should a pregnant worker wear a second monitor?

Under the lead apron at waist level.

Who is responsible for radiation safety in a hospital or clinic?

The radiation safety officer or radiation physicist.

Who does the radiation safety officer protect?

Personnel and patients.

What is a film badge used for?

Monitoring personnel radiation exposure.

How does a film badge work?

The film darkens based on radiation exposure.

What does TLD stand for?

Thermoluminescent dosimeter.

What does OSL stand for?

Optically Stimulated Luminescence dosimeter.

What is the most common personnel monitoring device?

OSL dosimeter.

What material is commonly used in a TLD?

Lithium fluoride or calcium fluoride crystals.

How does a TLD work?

Crystals absorb radiation and release light when heated.

Can a TLD be reanalyzed?

No.

What is the lowest exposure a TLD can measure?

About 50 μGya.

What material does an OSL use?

Aluminum oxide.

How is an OSL processed?

With a laser.

Can an OSL be reanalyzed?

Yes.

What is the lowest exposure an OSL can measure?

About 10 μGya.

Which is more sensitive at low doses, TLD or OSL?

OSL.

Which monitor is commonly used as a ring badge in nuclear medicine?

TLD.