rad 211 - radiation physics - wordpress.com · 2019. 10. 6. · ionizing radiation ionizing...

RAD 211 - RADIATION PHYSICS

DR. MOHAMMED MOSTAFA EMAM

College of Applied Medical Sciences

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IONIZING RADIATION

Ionizing radiation has sufficient energy to ionize anatom or molecule.

Ionization is a process in which a charged portionof a molecule (usually electron) is given enoughenergy to break away from the atom.

Ionization results in the formation of chargedparticles or ions; the molecule with net positivecharge and the free electron with a net negativecharge.

All ionizing radiation is capable, directly andindirectly of removing electrons from most of themolecules.

Ionizing radiation has enough energy to damageDNA in cells which in turn may lead to cancer.

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ALPHA RADIATION

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Characteristics of alpha radiation:

Alpha radiation is not able to penetrate skin.

Alpha emitting materials can be harmful to

humans if the materials are inhaled, swallowed

or absorbed through open wounds.

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Alpha radiation is not able to penetrate skin.

Alpha radiation is the least penetrating.

It can be stopped (or absorbed) by a sheet of paper.

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When alpha particles are emitted outside our bodies, virtually all of their ionizing radiation is harmlessly absorbed by the nonliving outer layer of our skin.

This means that alpha radiation doesn’t have much effect on our health unless radioactive isotopes get inside our bodies and emit radiation internally .

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Alpha radiation travels a very short distance

through air.

A variety of instruments have been

designed to measure alpha radiation.

Instruments can not detect alpha radiation

even a thin layer of water, blood, dust, paper

or other material, because alpha radiation is

not penetrating

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USES OF ALPHA RADIATIONS

Alpha particles are most commonly used in

smoke alarms (smoke detectors). The alpha

particles ionize air between a

small gap. A small current is

pass through the ionized air.

Smoke particles from fire that

enter the air gap reduces the current flow,

sounding the alarm.

Alpha decay can produce safe power sources

for radioisotope thermoelectric generators

used for space probes and artificial heart

pacemakers.

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BETA RADIATION

Beta radiation is a stream of electrons called beta

particles. When a beta particle is ejected, a neutron

in the nucleus is converted to a proton, so the mass

number of nucleus is unchanged, but the atomic

number increases by one unit.

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Thorium undergoes radioactive decay to form Protactinium and beta particle.

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Beta radiation is more hazardous because it can

also cause ionization of living cells. If the particles

hits a molecule of DNA it can cause spontaneous

mutation and cancer.

Characteristics of beta radiation:

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Beta emitting contaminants may be harmful if deposited

internally.

Beta radiation may travel meters in air and is moderately

penetrating, so It can penetrate human skin to “germinal

layer” where new cells are produced.


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Beta radiation cannot be detected with an ionization

chamber such as a CD V-715.

Clothing and turnout gear provide some protection

against most beta radiation. Turnout gear and dry

clothing can keep beta emitters off of the skin.

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USES OF BETA RADIATIONS

Beta radiation are widely used in medicine. In

brachytherapy, beta radioisotopes can be used to

irradiate areas inside a patient to prevent the growth

of certain tissues.

Beta particles are also used in some forms of

therapy to kill cancer cells.

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• Brachytherapy is a procedure that involves placing radioactive material inside your body.

• Brachytherapy is one type of radiation therapy that's used to treat cancer.

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• Brachytherapy is sometimes called internalradiation.

• Brachytherapy allows doctors to deliverhigher doses of radiation to more-specificareas of the body, compared with theconventional form of radiation therapy(external beam radiation) that projectsradiation from a machine outside of yourbody.

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• Brachytherapy may cause fewer side effectsthan does external beam radiation, and theoverall treatment time is usually shorter withbrachytherapy.

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Beta radiation is used in leak detection

in the pipeline. This is achieved by

adding small amount of beta radiation

to the fluid.

The area above the ground where high

intensity of beta radiation is detected

will pin point the leak sources in the

pipeline.

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• Carbon-14 is used as tracers in

chemical and biological research.

• The age of the ancient organic

materials can also be found by

measuring the amount of Carbon-14that is left.

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GAMMA RADIATION

Gamma radiation is electromagnetic radiation of

high frequency and therefore high photons with a

very short wavelength.

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GAMMA RADIATION

The emission of gamma radiation results from an

energy change within the atomic nucleus.

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GAMMA RADIATION

• It should be noted that the emission of gamma rays does not change the mass number or atomic number of the nucleus.

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GAMMA RADIATION

• Alpha and beta emission are often accompanied by

gamma emission, as an excited nucleus drops to a

lower and more stable energy change.

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X-RAYS

X-ray photons carry enough energy to ionize atoms

and disrupt molecular bond.

This makes it a type of ionizing radiation and

thereby harmful to living tissues.

X-ray machine sends individual x-ray particles

through the body. The image is recorded on a

computer or film.

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Characteristics of gamma radiation and x-rays:

Gamma radiation and X-rays are electromagnetic

radiation like visible light, radio waves, and

ultraviolet light. These electromagnetic radiations

differ only in the amount of energy they have.

Gamma rays and X-rays are the most energetic of

these.

X-rays are like gamma rays. They, too, are

penetrating radiation.

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Gamma radiation is able to travel many meters in air

and many centimeters in human tissue.

Radioactive materials that emit gamma radiation and

X-rays constitute both an external and internal hazard to

humans

Gamma radiation or X-rays frequently accompany the

emission of alpha and beta radiation

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Gamma radiation is detected with survey

instruments, including civil defense instruments.

Low levels can be measured with a standard Geiger

counter, such as the CD V-700. High levels can be

measured with an ionization chamber, such as a CD

V-715.

Instruments designed solely for alpha detection will

not detect gamma radiation

Pocket chamber (pencil) dosimeters, film badges,

thermo luminescent, and other types of dosimeters

can be used to measure accumulated exposure to

gamma radiation.

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USES OF GAMMA RADIATIONS

Even after it has been packaged, gamma rays can

be used to kill bacteria, mould and insects in food.

This process prolongs the shelf-life of the food, but

sometimes changes the taste.

Gamma rays are also used to sterilise hospital

equipment, especially plastic syringes that would be

damaged if heated.

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The most common tracer is called Technetium-99 and is

very safe because it only emits gamma rays and doesn't

cause much ionization.

• Radioisotopes can be used for medical purposes, such

as checking for a blocked kidney.

To do this a small amount of Iodine-123 is injected into

the patient, after 5 minutes 2 Geiger counters are placed

over the kidneys.

• Also radioisotopes are used in industry, to detect leaking

pipes. To do this, a small amount is injected into the pipe.

It is then detected with a GM counter above ground.

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Checking welds. If a gamma source is placed on

one side of the welded metal, and a photographic

film on the other side, weak points or air bubbles will

show up on the film, like an X-ray.

Because Gamma rays can kill living cells, they are

used to kill cancer cells without having to resort to

difficult surgery. This is called "Radiotherapy", and

works because cancer cells can't repair themselves

when damaged by gamma rays, as healthy cells can

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USES OF X-RAYS

X-rays are used in medicine for medical analysis.

Dentists use them to find complications, cavities and

impacted teeth. Soft body tissue are transparent to

the waves. Bones also block the rays.

X-rays are used in industry to inspect

products made by various kinds of

materials. X-ray machines are used

in airports to check luggage etc.

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In Science x-rays are used to analyze the

arrangement of atoms in many kinds of substances,

particularly crystals. Archaeologists used X-rays to

examine ancient objects covered by a crust of dirt.

X-rays are also used in consumer goods the

manufactures treat certain kinds of plastic to check

the quality of many mass produced products.

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rad 211 - radiation physics - wordpress.com · 2019. 10. 6. · ionizing radiation ionizing...

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