Chapter 2: Radiation- Types, Sources, and Doses Received

has different types and sources, some types produce damage, others do not, both contribute to total amount that humans recieve

radiation

type of radiation that is always present in the environment

natural

type of radiation that is created by humans for specific purposes

human-made

radiation travels in the form of ___

electromagnetic waves

travels through air and other substances (ex: sound waves & ultrasound)

mechanical vibrations of material

these waves can be detected by our ear

sound waves

these waves have a higher frequency that is too high to hear

ultrasound waves

examples are radio waves, microwaves, infrared, visible light, ultrasound, x-rays, gamma rays

the electromagnetic spectrum

number of cycles per second (Hz)

frequency

distance between 2 crests

wavelength

longer wavelength = ___ crests

farther

shorter wavelength = ___ crests

closer

the higher the frequency, the ___ the wavelength, and the ___ the energy

shorter, higher

Electric and magnetic fields fluctuate as they travel through ___

space

Electromagnetic waves are characterized by their ___ & ___

frequency and wavelength

radiation can travel as a wave or particle of energy (photon)

Dual nature of electromagnetic radiation (wave-particle duality)

what is the speed of light?

300 million meters per second

the ___ the energy levels the more likely to ionize atoms and cause biological damage

higher

what is the lowest energy electromagnetic wave?

AM radio

what is the highest energy electromagnetic wave?

gamma rays

Electromagnetic spectrum can be divided into two types of radiation ___ and ___

1. ionizing radiation (radiation dose)

2. non-ionizing radiation

examples of this are x-rays, gamma rays, high energy UV (above 10 EV)

ionizing radiation

radiation that is absorbed

radiation dose

examples of this are visible light, microwaves, infrared light

non-ionizing radiation

form of ionizing radiation that doesn’t meet the characteristics of electromagnetic spectrum, travels in straight lines (bolts), result of radioactive decay, try to stabilize themselves, not in diagnostic range

particulate radiation

examples of this are alpha particles, beta particles, neutrons, & protons (all have potential to cause ionization)

particulate radiation

low penetration power (paper can stop them), heavy elements, large, positively charged, move slowly, can’t travel far, harmful if INSIDE body

alpha particles (alpha rays)

much less penetrating, internal source of radiation = BAD, can be inhaled, swallowed, through an open wound & does bad things to biological tissues, if radon inhaled you may receive this

alpha particles

smaller and lighter, negatively or positively charged, travel farther, can penetrate skin, less damaging, medical imaging applications

beta particles (beta rays)

higher energy than alpha particles, less chance of interacting b/c smaller, plastic/aluminum can stop them, less damaging than alpha, seen in radiation therapy (created in linear accelerator)

beta particles

positively charged, relatively heavy, found in nucleus of atom, determine atomic number, used in radiation therapy and more precise than x-rays, expensive and limited availability

protons

electrically neutral, have approximately the same mass as a proton, medical imaging applications, used in radiation therapy for radio resistant tumors

neutrons

radiation quantity, amount of energy absorbed in a material (human tissue), helps us determine extent of biological harm, measured in milligray (mGy) or gray (Gy)

absorbed dose

considers the type/how much of ionizing radiation that was absorbed and deposited in tissues, includes the different degrees of tissue interactions, measured in units of the millisievert (MSV)

equivalent dose/dose equivalent (EqD)

considers the dose for all types of ionizing radiation to various irradiated organs or tissues in the human body, best estimate of overall harm from any given dose of radiation, shows types of organs and types of tissue radiated, unit = millisievert (MSV)

effective dose (EfD)

Primarily causes biologic damage, produced by ejecting electrons from atoms composing the tissues, result of destructive radiation interaction at the atomic level

• Molecular change

• Cellular damage

• Organic damage

(all 3 levels cause damage, begins at molecular level)

biologic damage potential

changes begin at molecular/atomic level, different than mechanical & thermal

biologic damage

if any of these sources of natural ionizing radiation increases (intentional or not)

enhance natural sources

natural background radiation can also be called ___

natural radiation

what are the 3 categories of natural radiation?

1. Terrestrial radiation

2. Cosmic radiation

3. Internal radiation from radioactive atoms

type of natural radiation, radioactive materials in the crust of the Earth (radon & thoron), the EPA says ___ is the 2nd leading cause of lung cancer and the #1 leading cause of lung cancer in people who don’t smoke

terrestrial radiation (radon)

type of natural radiation, nuclear interactions within the sun and solar system (most intense at high altitudes)

cosmic radiation

type of natural radiation, small percent of radioactive atoms that make up tissues (water, food, air)

Internal radiation from radioactive atoms

source of ionizing artificial radiation

manmade radiation (artificial radiation)

examples of this are:

1. Consumer products that contain radioactive material

2. Air travel (closer to sun/cosmic radiation)

3. Nuclear fuel for generation of power (nuclear power plants)

4. Atmospheric fallout from nuclear weapons testing

5. Nuclear power plant accidents (TMI-2 and Chernobyl)

manmade radiation (artificial radiation)

___ cancer continues to be the main effect from Chernobyl

thyroid

water reactor had a loss of coolant and lead to a radioactive gas leak

3 mile island

what are the 2 largest sources of artificial radiation?

1. Diagnostic medical x-ray

2. Nuclear medicine procedures

patient ___ for each exam varies

dose

The amount of radiation received by a patient from diagnostic x-ray procedures may be indicated in terms of 3-4 things?

1. entrance skin exposure (ESE)

2. bone marrow dose

3. gonadal dose (fetal dose in pregnant women)

Entrance skin exposure (ESE) includes ___ and ___ dose

skin, glandular

bone marrow dose is one of the most ___ parts of the body

sensitive

which dose can be passed to future generations?

gonadal dose