Radiation Safety Radiation Safety TrainingTraining

Understanding and Working Understanding and Working Safely with RadiationSafely with Radiation

ICN Dosimetry Service

Revision 0, April 2000

Tosh Ushino, CHPRadiation Safety Officer

What is radiation and what What is radiation and what does it mean to me?does it mean to me?

Did it exist before the bomb?

Will I get cancer from it?

How can I ensure my safety?

[Or, are bananas radioactive and is that why King Kong got to be that big?]

There is so much There is so much misinformation about radiationmisinformation about radiationWe learned about radiation and its effects watching Sci Fi movies and TV shows

– Incredible Hulk, mutation caused by radiation– Spiderman, bitten by a radioactive spider– Godzilla, mutated from a weapon test– Teenage Mutant Ninja Turtles, from radioactive waste– and many others……

Unfortunately, lots of people think this is all true…. – and of course, Mr. Spock of Star Trek, after all his exciting

adventures across the universe, died of radiation exposure

Where does Radiation come from?Where does Radiation come from?

Atoms are composed of particles

Nucleus: – protons with positive (+) charge– neutrons with no charge

Outer shell:– electrons with negative (-) charge

Where does Radiation come Where does Radiation come from? (cont’d)from? (cont’d)

Neutrons act like to glue to hold nucleus together

– Protons don’t want to stay together

– There are about equal numbers of protons and neutrons in nucleus

– If the numbers are out of balance, then the nucleus is unstable

Where does Radiation come Where does Radiation come from? (cont’d)from? (cont’d)

Number of protons in nucleus determines what kind of element the atom is Number of neutrons in the nucleus determines the isotope of that element

Where does Radiation come Where does Radiation come from? (cont’d)from? (cont’d)

Example:

Stable Hydrogen– Nucleus composed of one proton (normal

hydrogen)– Nucleus composed of one proton and one

neutron (deuterium)

Unstable Hydrogen (radioactive)– Nucleus composed of one proton and two

neutrons (tritium)

Where does Radiation come Where does Radiation come from? (cont’d)from? (cont’d)

Example: (cont’d)

In a process called “radioactive decay,” unstable nucleus eventually becomes stable by ejecting– excess particles– excess energy

Radiation is the ejected excess energy or Radiation is the ejected excess energy or particleparticle

““ActivityActivity” is the measure how much ” is the measure how much isotopes are undergoing decayisotopes are undergoing decay

What is Ionizing Radiation?What is Ionizing Radiation?

There are 2 types of radiation: sub-atomic particles electromagnetic waves

Typically, particles are parts of atoms alpha (helium nucleus) beta (electron) positron (positive anti-electron) neutron (component of nucleus)

You can find exotic particles in cosmic ray and at high energy accelerators

What is Ionizing Radiation? What is Ionizing Radiation? (cont’d)(cont’d)

Electromagnetic waves are: Like light or radio-waves you cannot

see Emitted in packets of energy called

“photons”– X-Ray

– Gamma Ray

What is Ionizing Radiation? What is Ionizing Radiation? (cont’d)(cont’d)

Gamma Rays – from nucleus of atom– from annihilation of electron and positron

X-Rays – from orbital electrons– from high energy electrons (and positrons)

slowing down (call “Bremsstrahlung”)

Ionizing radiation has enough energy to strip electrons off of atom or molecule

Where do isotopes come from?Where do isotopes come from?

Primordial isotopes• Uranium series

• Thorium series

• Radium series

• Potassium-40 (K-40)

Continually produced by natural process– H-3, C-14

Generated through man’s activity– Tc-99m, Cs-137, Pu-239

Where do we get most of our Where do we get most of our radiation exposure?radiation exposure?

We live in an ocean of radiation

Radiation comes from earth, space, and food we eat

Life on earth evolved and flourished in higher level of natural radiation than today

Natural Sources of RadiationNatural Sources of Radiation

Terrestrial RadiationRadiation emitted from natural radioactivity in soil, minerals and rocks

Nuclide DepositionRadiation from natural radioactivity

in our bodies, from food and air

Cosmic RayHigh energy radiation from

the sun and deep space

Space WeatherSpace Weather

ENERGETIC PARTICLES

ELECTROMAGNETIC RADIATION

SOLAR WIND

POLAR CUSP

The sun emits both electromagnetic radiation and electrically charged particle streams which can interact with the near-earth environment. These radiations vary in intensity over time

Man-made Sources of RadiationMan-made Sources of Radiation

Nuclear Medicine• Radioactive tracers for diagnostic therapy• Analytical procedures• Pacemakers

Medical X-Rays (produced by x-ray tubes)

• Fluoroscopy• Chest X-Ray• Dental X-ray

Man-made Sources of Radiation Man-made Sources of Radiation (cont’d)(cont’d)

Consumer products– Television sets

– Smoke detectors

– Fossil fuel: coal, gas

Air travel Luminous compounds Building materials Nuclear fuel cycle Above-ground bomb tests

Can you become radioactive if Can you become radioactive if you get exposed to radiation?you get exposed to radiation?

You are already radioactiveYou are already radioactive Radioactivity is a nuclear process Radiation we encounter day-to-day only affects

electrons around the nucleus– If you come into a dark room from sunlight, can others

see you glow in the dark?– If you heat your food in microwave oven, does the food

emit microwave as you are eating it?

Radioactivity can be induced only if exposed to neutron or beam from an accelerator

How much radiation exposure is How much radiation exposure is allowed per year?allowed per year?

Radiation Worker: Whole body: 5,000 mrem Lens of the eye: 15,000 mrem Skin: 50,000 mrem Extremity: 50,000 mrem Pregnant radiation worker 500 mrem

for the entire gestation period– Fetus is radiation sensitive due to rapidly dividing cells

General Public: Whole body: 100 mrem*

[*up to 500 mrem w/prior authorization]

How much radiation dose do we How much radiation dose do we receive from Mother Nature?receive from Mother Nature?

300 mrem/year (national average)300 mrem/year (national average) It increases with:

– elevation– latitude

It varies with:– geology of the area where you live– type of food you eat– type of homes you live in– your lifestyle (smoking, air travel, etc.)

If you live in Denver, you’ll receive more radiation from cosmic ray and granite

Radiation EffectsRadiation Effects

Radiation Effect depends on

– How much radiation dose you receive

– How quickly you receive the dose

– What part of the body receives it, and

– whether you receive any medical treatment

Radiation sensitivity depends on how

rapidly cells divide

Acute Radiation SyndromeAcute Radiation SyndromeWhole Body ExposureWhole Body Exposure

Hemopoietic syndrome (>200,000 mrads)– Depression or ablation of bone marrow– Malaise and fatigue, epilation– Potential death due to infection if no medical treatment given

Gastrointestinal syndrome (>1,000,000 mrads)– Desquamation of intestinal epithelium– Severe nausea, vomiting, diarrhea

Central nervous system syndrome (>2,000,000 mrads)– Damage to central nervous system & other body organs– Unconsciousness within few minutes

How does ionizing radiation cause cell How does ionizing radiation cause cell and tissue damage?and tissue damage?

Direct damage to DNA

– DNA damage is expressed only when damaged cells divide

– Most of the damaged DNA are repaired. If not, the cell may die; or a tiny fraction may persist

How does ionizing radiation cause cell How does ionizing radiation cause cell and tissue damage? (cont’d)and tissue damage? (cont’d)

Indirect damage through formation of hydroxide “free” radicals (hydrogen peroxide)

– Free radicals may damage DNA

– At extremely high dose, cells are killed by damage to cell membrane from high levels of radicals

How much DNA damage will I get?How much DNA damage will I get?

Recent study shows 10,000 mrem of radiation (2x the annual limit for workers) causes ~200 single strand and ~4 double strand breaks per cell

This study also shows chemical and thermal effects (from day-to-day living) cause ~150,000 single strand and ~200 double strand breaks per cell per year

How much DNA damage will I get? How much DNA damage will I get? (cont’d)(cont’d)

Typical American receives ~300 mrem of natural radiation per year

So, ~0.004% of DNA damage may be from natural radiation, and

If radiation worker receives 5,000 mrem,

<0.07% of DNA damage may be from occupational radiation exposure

How effective is radiation in causing How effective is radiation in causing DNA damage?DNA damage?

In the study of cancer, researchers induce malignant transformation in cells

Chemical carcinogens like benzopyrene is much more effective than radiation in producing cancer cells

It may take 10,000’s, if not 100,000’s of mrads to produce the same effect as the amount of benzopyrene in a single cigarette*

[* Dr. Ann Kennedy, University of Pennsylvania]

So, how come we are not all So, how come we are not all dropping dead of cancer?dropping dead of cancer?

On the average, about 1/3 of all people get cancer from all causes

Currently, about 17% of people die from cancer

Population of U.S. is about 300 million

Eventually all those people would die

~ 100 million would get cancer

~ 50 million of those would die from cancer

So, how come we are not all So, how come we are not all dropping dead of cancer? dropping dead of cancer?

(cont’d)(cont’d)

Natural repair mechanism in our bodies

eliminate most of the damaged cells Damaged cells that are not eliminated by the

repair mechanism may become cancerous

Cancer incidence rate rises with age

So, if you live long enough, you will get

cancer

What is the likelihood that you’ll die from What is the likelihood that you’ll die from cancer due to occupational exposure?cancer due to occupational exposure?

Highly unlikely!

Cancer Deaths Attributed to Cancer Deaths Attributed to Various SourcesVarious Sources

Source Cancer Deaths (%)Diet 35 Range: 10 - 70Tobacco 30 Range: 25 - 40Infection 10Sexual lifestyle 7 Range: 1 - 13Occupation 4Alcohol 3Natural Environment 3Pollution 2Medical Care 1Food Additives 1Industrial Products 1Unknown -

So why is there so much scare So why is there so much scare about radiation?about radiation?

We can’t see it, smell it, or feel it– It is not part of our daily experience– Because of that, we do not have a proper

perspective of the relative risks

We read scaryscary headlines– Written by people who probably don’t know

any more than you do

On the other hand, several dozen people die each day due to traffic accidents, but people continue to ride cars, trains and airplanes because we are used to it

Radiation is a toolRadiation is a tool

Radiation has many wonderful uses– Diagnose disease

– Cure cancer

– Analytical tools for industry and medicine

– Sterilize medical equipment and food, etc

Like anything, it can be misused, and

Like anything, too much is not good for you

What Safety Precautions What Safety Precautions should I take?should I take?

Use Common Sense– Not so common after all

Time, Distance and Shielding– Minimize Time– Maximize Distance– Maximize Shielding

(heavier the better)

Follow safety procedures

History of Radiation AccidentsHistory of Radiation AccidentsNearly all, if not all, radiation accidents were

caused by workers– not paying attention to what they were doing– deliberately violating procedures– deliberately circumventing safety devices

Devices do fail occasionally, but good procedures and training would account for that possibility

You can make the devices and procedures as “Idiot-Proof” as possible

– but those “idiots” can be very clever