test 1, ch 2 radiation types, sources, doses received

concept of effective dose and unit (The equivalent dose (EqD) enables the calculation of effective dose (EfD).) --the best estimate of overall harm that might be produced by a given dose of radiation in human tissue. It takes into account both the type of ionizing radiation and the part of the body irradiated

--The effective dose (Efd) takes in to account that the radiation absorbed dose affects different organs and organ systems, as well as the type of ionizing radiation that caused the dose. ---The organs or organ systems irradiated is another factor that plays a role in determining the degree of biologic damage. Ex: irradiation of internal organs has different and generally more severe consequences than irradiation of extremities. --measured in millisievert (mSv).

Man-Made

1. Consumer Products Containing Radioactive Material: Includes: ØAirport surveillance systems ØElectron microscopes ØIonization-type smoke detector alarms ØIndustrial static eliminators --As a result of strict regulations imposed within the US by the FDA regarding such devices, the radiation exposure of the general public from consumer products may now be considered negligible. 2. Air Travel Normal use of airplane at high elevations bring many humans in closer contact with high energy extraterrestrial radiation and increase their exposure A flight on a typical commercial airliner results in an EqD rate of 0.005 to 0.01 mSv/hr ØSunspots can increase radiation exposure ØDuring "solar flares" can be 10 to 100x higher. ØDuring a 10 hour flight a person receives a radiation EqD equal to the dose received from one CXR examination ØPilots, flight attendants and general public who are "frequent flyers" may be exposed to large dose of radiation Ø3. Nuclear Fuel for Generation of Power: Nuclear Power plants that produce nuclear fuel do not contribute significantly to the annual EqD of the US population. 4. Atmospheric Fallout from Nuclear Weapons Testing: Total annual EqD from fallout cannot be made because actual radiation measurements don't exist --Dose commitment=the dose that may ultimately be delivered from a given intake of a radionuclide --Dose commitment may be estimated using approximations and models. 5. Nuclear Power Plants:

Changes in the blood count can result from nonnegligible( a little amount) exposure to ionizing radiation and is an example of organic damage.

Acute Whole Body Exposures- Radiation exposures are delivered to the entire body over a time period of less than a few hours (this does not happen in xray imaging) --ex) An EqD of .25 Sv (250 mSv) delivered to whole body may cause decrease in the number of lymphocytes (WBCells) within a few days after exposure. (chart shows acute exposures) (.25 x 1000 or move decimal over 3 places)

different forms of particulate radiation (all ionizing but is not equal in terms of biologic damage from xrays) "Particulate radiation refers to particles, originating from radioactive nuclei, with the energy to ionize matter" All particulate radiations are subatomic particles that are ejected from atoms at very high speeds. . At rest, they cannot cause ionization.

Alpha particles Beta particles Neutrons Protons

ØRadiation received by patient may be indicated by: Entrance skin exposure (ESE) which includes skin and glandular dose Bone marrow dose Gonadal dose Fetal dose (estimated in pregnant women)

Because humans are unable to control natural background radiation, exposure from man-made sources that can be controlled must be limited to protect the general population from further biologic damage

the frequency of exposure to manmade radiation in medical applications continues to increase rapidly among all age groups in the US

Main reason medicolegal considerations. medicine must be counterbalanced by controlling the amount of patient exposure in individual imaging procedures

Medical Radiation:

Number of medical procedures involving the use of ionizing radiation has increased dramatically since the 1980s, Because of this , exposure of the US population from medical sources has also increased signifiantly --Medical radiation exposures result from 1. Diagnostic x-rays which includes: -CT scanning -Interventional fluoroscopy -Conventional fluoroscopy 2. Radiopharmaceuticals in nuclear medicine

X-rays and gamma rays:

have characteristics of both waves and particles, but because of their high energy, they exhibit more particulate characteristics than those at the other end of the spectrum. They do exhibit the wave characteristics of transmission.

''''

have very short wavelengths. They are high energy, high-frequency radiation. Their energy is measured in thousands of electron volts (keV) and they are capable of ionization. Ionizing radiation such as x-rays and gamma rays has enough energy to remove an electron from its orbital shell.

Radioactive decay

is the process of a radioactive element giving off excess energy and particles to regain its stability ---A radioactive substance does not suddenly decay all at once ---term used to describe the rate at which a radioactive substance decays is half life

It wasn't until the beginning of the 20th century that the general public had any exposure to man-made sources of radiation (t/f)

true

Both occupational and nonoccupational dose limits are expressed in EfD and EqD and stated in millisieverts

true.

A photon of x-radiation and a photon of visible light are fundamentally the same, except that

x-radiation has much higher frequency, and hence a shorter wavelength, than visible light. x-ray photons, behave more like particles than waves. which is why they interact at atomic level.

Electromagnetic radiation appears to have a dual nature called wave-particle duality.

-Can travel through space in the form of a wave but can interact with matter as a particle of energy -For this reason x-rays may be described as both waves and particles characteristics. --Higher-energy electromagnetic radiation tends to exhibit more particle characteristics, ------and lower-energy electromagnetic radiation tends to exhibit more wave characteristics.

spectrum

-EM radiations vary in energy, frequency and wavelength -The energy of radiation is measured in eV

Natural environmental radiation equivalent dose annually in humans

3.0 mSv

Photon ENERGY and FREQUENCY are _____PROPORTIONAL

DIRECTLY

electromagnetic radiation

X-rays Gamma rays

define radiation

energy in transit from one location to another.

Ultrasound is a form of

mechanical energy

Diagnostic x-rays and nuclear medicine procedures are the two largest sources of man-made (artificial radiation)

(t/f)

3. Protons: Positively charged components

--Proton therapy is a form of radiation treatment that uses a beam of protons(cyclotron or a synchrotron) to deliver targeted precise doses (steered by magnets) of radiation to pts.

DEFINE Terrestrial radiation:

--Results from the deposits of uranium-238, radium-226 and thorium-232 and other radionuclides that are present in various quantities in the crust of the earth. Contributes to about .3 mSv of average annual radiation EqD from natural radiation for the US. --The largest source of natural environmental radiation is radon. ----Radon is a radioactive gas produced by natural radioactive decay of uranium, which is present in trace quantities in the Earth --Concrete, bricks, and gypsum wallboard, contain radon. --Radon emits alpha particles, which are not penetrating, and therefore contributes a radiation dose only to the lung. --EPA considers radon to be the second leading cause of lung cancer in the US. Radon contributes 2.0 mSv of average annual radiation EqD from natural radiation for the US.

2. Beta Particles --have been used in therapy, mainly for superficial skin lesions or to deliver radiation boost treatments to breast tumors at tissue depths not exceeding 5 to 6 cm.

--an electron that is emitted from an unstable nucleus; it does not originate from an electron shell. -is much lighter and smaller than an alpha particle and can penetrate light materials (tissue penetration is up to 2 cm) -longer range but still. ionize many atoms -negatively charged beta particle differs from an electron only in that it originated in the nucleus of the atom, not an orbital shell. --positively charged beta particle is called a positron. -able to penetrate matter to a greater depth than alpha particles. --1 mm of lead is required to stop beta particles

different forms of electromagnetic

1. Radio waves 2. Microwaves 3. Infrared light 4. Visible light 5. Ultraviolet light 6. X-rays 7. Gamma rays

Man-made radiation annual equivalent (EqD)

3.3 mSv

It is preferable to designate x-rays and gamma rays according to their

PHOTON ENERGY.

Electromagnetic Energy/radiation

Type of energy in x-rays. energy emitted and transferred through space.

shorter wavelength =

higher frequency (inversely proportional)

discuss need for rad protection

--By limiting widespread substitution of unnecessary CT scans and/or repetitive CT scans by using alternative, less costly diagnostic procedures --In interventional radiography radiation doses can be kept lower by using pulsed and not continuous operation, lesser mA, last image hold feature

Electromagnetic Waves

--Electromagnetic radiation consists of vibrations in electric and magnetic fields. --These vibrations have no charge and no mass and travel at the speed of light --Electromagnetic radiation moves in sinusoidal waves. --These waves consist of electric and magnetic fields

7 sources of manmade/artificial ionizing radiation

-Consumer products -Air travel -Nuclear fuel for generation of power -Atmospheric fallout from nuclear weapons testing -Nuclear power plant accidents -Nuclear power plant accidents as a consequence of natural disasters -Medical Radiation (3.2 out of the 3.3)

modalities used that have caused an increase in dose from 1980-present (Since 1987, little change in amount of natural)

-Increase use of CT (and "repeat" CT exams) -Interventional procedures -Cardiac nuclear medicine exams

local/global consequences of rad exposure from accidents in power plants

1. Three Mile Island: 2. Chernobyl 3. Fukushima

3 sources of natural background ionizing radiation

1.terrestrial radiation sources of radiation that are present in variable quantities in the crust of the earth. (radon) 2. cosmic radiation from the sun (solar) and beyond the solar system (galactic) 3. internal deposits of radionuclides which make up a small percentage of the body's tissues.

Internal Radiation: ØInternal radiation is also called endogeneous radiation

Internally deposited radionuclides include: Potassium-40 Carbon-14 Hydrogen-3 Strontium-90 --Average US inhabitant receives an EqD of about or 0.4 mSv (40 mrem) per year from internal radiation

The only difference between x-rays and gamma rays is their origin.*

X-rays are produced in diagnostic imaging systems and come from interactions with orbital electrons. X-rays - are produced when fast-moving electrons within the x-ray tube strike the atoms of the metal in its target.Gamma rays come from inside the nucleus of a radioactive atom. Gamma rays- originate in the nuclei of atoms and represent the excess energy the atom is giving off to reach a stable state.

Radioactivity

a general term for the process by which an atom with excess energy in its nucleus emits particles and energy to regain stability.

Protons, neutrons, and other subatomic particles

are produced in laboratory settings using particle accelerators or in nuclear reactors."

Alpha particles and beta particles are emitted by

by radioactive nuclei

The mSv is the unit of ____ and is used to express radiation exposure of populations and radiation risk in those populations

effective dose (Efd)

Kinetic energy

energy of motion. Includes radiant energy, etc. Ex: a moving automobile, a turning windmill wheel, a falling guillotine blade

The blade of a guillotine offers an example

of both potetial and kinetic energy. When the blade is pulled to its maximum height and is locked into place, it has potential energy. When the blade is allowed to fall, the potential energy is released as kinetic energy.

Infrared radiation,

or heat : has shorter wavelengths and higher energy than radar and microwaves. The high-energy end of the infrared region is visible and can be seen in the red heating elements of your toaster. The signal sent from the TV remote is infrared light.

a _________ is the smallest quantity of any type of electromagnetic energy (just as atom is the smallest quantity of an element)

photon

Photon is pictured as a small bundle of energy, sometimes called a

quantum, that travels through space at the speed of light (c). 3×10^8 m/s.

Elements that are composed of atoms with unstable nuclei are said to be

radioactive. (Technetium is produced for nuclear medicine studies)

An adult emits about 100 gamma rays per second. Sleeping with an adult adds another 0.02 mGy/yr. You may receive more if persons close to you smoke or have recently been given radionuclides for medical purposes. Endogeneous radiation begins at conception, is continuous through death, and becomes more intense with cremation; radionuclides in the ashes are about ten times more concentrated than in the body"

random fact

Visible light:

selectively activates cells in the eye. It represents the colors visible to the human eye. Visible light has higher energy and shorter wavelengths than infrared radiation.

Potential energy-

stored energy of position, several forms. /The ability to do work by virtue of position Ex: Roller coaster on top of incline and stretched spring of open screen door

"Endogenous radionuclides makes each person a significant radiation source. People, pets, and other animals provide interorganismic radiation." (t/f)

true

The highest-energy members of the electromagnetic spectrum that have the ability to ionize matter which can cause biologic changes and harm to human tissues are?

x-rays and gamma rays

which forms of radiation are ionizing (can transfer sufficient energy to some orbital electrons to remove them from the atoms to which they were attached)

xrays and gamma AND High-energy ultraviolet radiation (energy higher than 10 eV)

Cosmic Radiation: ØExtraterrestrial radiation

-Cosmic and EM radiation from the sun (solar) and beyond the solar system (galactic) -Are particulate and electromagnetic radiation emitted by the sun and the stars -On Earth intensity of cosmic radiation increases with altitude and latitude People living in New York City receive about half the exposure to cosmic radiation that people living in a high altitude city such as Denver, Colorado. -Average US inhabitant receives an EqD of about 0.3 mSv per year from extraterrestrial radiation

define matter and define energy

-Matter - anything that occupies space and has mass. Atoms and molecules are the fundamental building blocks of matter. The scientific unit of mass is the kilogram. -Energy - the ability to do work (Measured in an International System (SI) unit called joule (J)—In radiology , the unit electron volt (eV) is often used (traditional unit)

4. Neutrons Electrically neutral

-Neutron beam therapy uses neutrons to destroy very dense tumors -Entails the use of a particle accelerator; protons from the accelerator are deflected by a magnet to a target which creates the neutron beam

The total EqD from natural and manmade dose per year is about

6 mSv (6.3mSv on chart)

. Nonionizing radiation: These radiations do not have sufficient kinetic energy to eject electrons from the atom and are considered nonionizing:

Ultraviolet radiation with energy less than 10 eV Visible light Infrared rays Microwaves radiowaves

All EM waves have the same constant speed—they differ in wavelength and frequency. --an INCREASE in frequency must always be accompanied by a DECREASE in wavelength

Wavelength - distance between 2 successive crests or troughs in a wave Frequency - the number of wavelengths passing a point per second

Breakdown of annual doses to the average member of the population from natural sources of radiation:

Cosmic - 0.3 mSv Internal- 0.4 mSv Terrestrial - 0.3 mSv Radon - 2.0 mSv TOTAL - 3.0 mSv (Bushong states Natural environmental radiation consists of 4 components)

biologic damage in body tissue (primarily by ejecting electrons from the atoms comprising the tissue.)

Destructive radiation interaction at the atomic level results in molecular change which can then cause cellular damage.. If excessive cellular damage occurs, then organism have a significant possibility of demonstrating genetic or somatic changes: Examples include: Mutations Cataracts Leukemia

Radar and Microwaves

Have shorter wavelengths and higher energy than radio waves and are used in ovens, in navigation, and in traffic control, where law enforcement officers monitor the speed of cars.

Ultraviolet:

Is the part of the EM spectrum just beyond the visible light region. It has energies approaching those of X-rays and gamma rays. Ultraviolet light-emitting bulbs are used in tanning beds, because it is that part of sunlight that causes darkening of the skin (or burning if exposure is excessive). UV light stimulates melanin production of skin cells, causing the darkening of or damage to the melanocytes, resulting in cancer, but it does not ionize atoms.

Radio Waves

The low end of the energy spectrum. long wavelength, low energy. One common use of radiowaves aside from transmitting our favorite music to our radios is in MRI

Absorbed dose-

amount of kinetic energy per unit mass that has been absorbed in a material due to interaction with ionizing radiation.

define

Chemical energy -Energy released by a chemical reaction Ex: Type of energy provided to our bodies through chemical reactions involving the food we eat. Electrical energy -The work that can be done when an electron or an electronic charge moves through an electric potential Ex: household electricity Thermal Energy (Heat) -The energy of molecular motion and is closely related to temperature. ,,,The faster a molecule of a substance vibrates the more thermal energy it has and the higher its temperature. ØNuclear Energy Energy contained in the nucleus of an atom Ex: We control the release and use of this type of energy in electric nuclear power plants ØMechanical Energy - Ultrasound is a form of mechanical energy that is transmitted by pressure waves through a medium ØElectromagnetic Energy Type of energy in x-rays. radio waves, microwaves, infrared light, visible light , ultraviolet light, gamma rays and x-rays are all types of electromagnetic energy

Equivalent dose / radiation dose

describes a quantity of radiation and applies only to ionizing radiation. (x-rays Exposure to radioactive materials from nuclear reactors - other types of radiation - protons, neutrons, electrons) --attempts to numerically specify the differences in potential biologic harm that are produced by different types of radiation. --provides an overall dose value that includes the different degrees of tissue interaction that could be cause by the different types of radiation. -product of the average absorbed dose in a tissue or organ in the human body and its associated weighting factor chosen for the type of radiation in question. --The most common unit of measure of equivalent dose is the millisievert (mSv)

1. Alpha Particles This gives them the atomic number of 2 and the mass number of 4. Upon accepting two electrons, an alpha particle becomes a neutral helium atom

helium nuclei consisting of two protons & two neutrons. --Alpha particles having a large mass and two positive charges, strongly ionize the atoms of matter through which they pass. --particles leave the nucleus at high speeds, but do not penetrate matter for any appreciable depth because of their strong ionizing ability; in fact they are absorbed by an ordinary piece of paper. --If emitted from a radioisotope that was deposited in the body(internal) (ex.lungs) alpha particles will be absorbed in the epithelial tissue and be extremely damaging. -Average alpha particle possesses 4 to 7 MeV of kinetic energy and ionizes about 40,000 atoms for every centimeter of travel through air.(densely ionizing) -has a very short range in matter

Ionization

process by which a neutral atom gains or loses an electron. foundation of the interactions of x-rays with human tissues. This ionizing potential makes x-rays valuable for creating images but has the undesirable result of potentially producing some damage in the biologic material through which it passes.

Photons interact with matter most easily when the matter is approximately the same size as the photon wavelength. (t/f)

true.

Main reason for increase is the enormously expanded use of CT (t/f)

true. 1980 - collective dose of 3700 person-sieverts 2006 - collective dose of 440,000 person-sieverts. CT offers tremendous medical benefit and risk-to-benefit ratio is still very small when CT exams are ordered for appropriate reasons.

unit that absorbed dose is commonly specified

units of milligray (mGy)