Radiation Safety

 RADIATION PROTECTION REQUIREMENTS

What is Radiation

The process of emitting energy in the form of particles or waves.

Matter’s is composed of very, very small particles called atoms.

Radiation comes from atoms that are in the process of changing

Radiation Types

Non-Ionizing Radiation

Visible light/heat/radio waves/microwaves

Does not have sufficient energy to cause ionization 

•

Ionizing Radiation

–

Physical change in atoms by making them electrically charged—called ionization

Non-Ionizing Radiation

Has enough energy to move atoms but not enough to alter them chemically.

It is all part of the electromagnetic spectrum, or electromagnetic radiation.

Electromagnetic exists as waves with both an electric field and a magnetic field.

Ultra Violet, Infra Red, Microwave, Laser.

Hazards of Non-Ionizing Radiation

Its energy is transformed into thermal and chemical energy.

Thermal energy generates heat, and chemical energy can cause reactions which may damage the molecule in our tissues.

Some energy can cause burns (IR), and can cause cataracts and can burn the cornea and injure the retina

UV can cause blindness.

Protection

Appropriate engineering controls and safe work practices.

Apparatus are designed to prevent the escape of harmful light – follow the manufacturer’s instructions for replacing bulbs and making repairs.

Make sure all shields and guards are in place whenever the bulb is energized.

Use the proper eye protection.

Ionizing Radiation

Is radiation that has sufficient energy to remove electrons from atoms.

The major types of radiation emitted as a result of spontaneous decay are Alpha and Beta particles, and Gamma rays. X rays, another major type of radiation, arise from processes outside the nucleus. 

Alpha Particles

Alpha particles are energetic, positively charged particles that rapidly lose energy when passing through matter and do not penetrate so far.

They can cause damage over their short path through tissue.(Not a hazard outside the body)

They can be very harmful if they are ingested or inhaled.

Alpha particles can be stopped completely by a sheet of paper.

Alpha Particles

Positively charged

Emitted from uranium and radium

Do not penetrate far

Not a hazard outside the body

Harmful if ingested or inhaled

Beta Particles

Beta particles are fast moving negatively charged particles.

Beta particles are more penetrating than Alpha particles.

Some Beta particles are capable of penetrating the skin and causing radiation damage.

They can be very harmful when they are inhaled or ingested.

Can be stopped by a layer of clothing or by a few millimeters of aluminum.

Beta Particles

Positive or negative electrons

Emitted from tritium, carbon-14, strontium-90

Capable of penetrating skin

More hazardous when inhaled or ingested

Stopped by clothing or aluminum foil

Gamma Rays

Gamma rays are weightless packets of energy called photons.

They have neither a charge nor a mass and are very penetrating.

Gamma rays can easily pass completely through the human body or be absorbed by tissue, thus constituting a radiation hazard for the entire body.

Several feet of concrete or a few inches of lead may be required to stop the more energetic gamma rays.

Gamma Rays

Packets of energy called photons

No charge or mass, very penetrating

Emitted from potassium-40, plutonium-239

Absorbed by tissue

Only stopped by thick concrete or lead

X - Rays

X-rays are high-energy photons produced by the interaction of charged particles with matter.

X-rays and gamma rays have essentially the same properties, but differ in origin.

X-rays are emitted from processes outside the nucleus.

X-rays are lower in energy and less penetrating than gamma rays.

A few millimeter of lead can stop medical x-rays.

Penetrating Powers

Risk from Exposure to Radiation

Radiation is carcinogen, can cause cancer.

It may also cause other adverse health effects, including genetic defects in the children of exposed parents or mental retardation in the children of motors exposed during pregnancy.

Knowledge about risks from radiation is based on studies of over 100,000 survivors of the atomic bombs at Hiroshima and Nagasaki.

Effects of wide range of radiation doses. 

Acute Health Effects

Changes in the blood cells 

Vascular changes 

Skin irritation 

Gastrointestinal effects 

Radiation sickness:

Diarrhea

Nausea

Vomiting

High fever 

Hair loss 

Burns

Radiation Protection Concepts

There are three concepts in basic radiation protection. They are:

1- Time

2- Distance

3- Shielding

Time

If you decrease the amount of time you spent near the source of radiation, you will decrease the amount of radiation exposure you receive.

Distance

The farther away you are from a radiation source, the less the exposure.

The intensity of radiation from a source varies inversely as the square of the distance from the source.

Shielding

If you increase the shielding around a radiation source, it will decrease your exposure.

Radiation Measurement Units

Rad

Roentgen

Curie

Rem

Sievert

Becquerel

Dosimetry Units

Exposure

Ability of photons to ionize air

1 roentgen (R) = 2.58 e-4 Joule/kg in air

Absorbed Dose (RAD)

Energy actually deposited by mass

1 rad = 100 ergs/gram 

1 gray (Gy) = 100 rad -- SI units

Dose Equivalent - REM                                                

Takes into account the relative biological effect for different radiations

1 rem = 1rad x QF

QF = Quality Factor

Beta = 1

Gamma & X-ray = 1

1 seivert (Sv) = 100 rem -- SI units

Radiation Absorbed Dose (RAD)

The unit of absorbed dose, a dose of one rad means the absorption of 100 ergs of radiation energy per gram of absorber or 10 j/kg of absorbing materials.

Reontgen

Is a unit of exposure and represents the amount of x-rays or gamma radiation required to produce ions carrying one electrostatic unit of charge of either in 1 cc or dry air under standard conditions

Curie (Ci)

Unit of radioactivity defined as the quantity of any substance in which the number of disintegration per second equals 3.700 x 1010.

Roentgen Equivalent Man (REM)

The unit of dose equivalent. The dose equivalent in rems is numerically equal to the absorbed dose in rads multiplied by the quality factor, the distribution factor, and other necessary modifying factors.

SIEVERT (Sv)

Special name for the SI unit of dose .

One Sievert = 100 rem

Summary

Permissible Dosage

Rems per calender year
Whole body: head and trunk; active blood-forming organs; lens of eyes or gonads	5 Rem
Hand and forearms, feet and ankles	75 Rem
Skin of whole body	30 Rem