RT 202 RAD PRODUCTION MIDTERMS

radiation

the emission of energy as electromagnetic waves or as moving subatomic particles (especially high-energy particles) which causes ionization

radiation

the emission or transmission of energy in the form of waves or particles through space or material medium

electromagnetic radiation

type of ionizing radiation that has both electrical and magnetic properties

x-ray

kind of electromagnetic radiation that comes from the electron cloud

gamma ray

kind of electromagnetic radiation that comes from the nucleus

particulate radiation

type of ionizing radiation that is made up of any subatomic particles (such as protons, neutrons, and high-speed electrons) capable of causing ionization

alpha and beta particles

2 common types of particle radiation

radioactive decay

source of radioactive atom

wavelength

the distance between 2 successive crest or throughs

lambda (λ)

symbol of wavelength

frequency

represents the number of waves passing a given point per given unit of time

amplitude

distance between the highest and lowest point; height of the wave

crest

highest point of a wave

through

lowest point of a wave

inverse

relationship of wavelength and frequency

photons

atom of light; quanta; small bundle of energy; smallest quantity of any type of electromagnetic energy

speed of light (3 × 10⁸ m/s)

x-rays travel at the _________ in a vacuum

neutral

x-rays are electrically ____________ due to the attraction of anode and cathode particles

optically focused

x-rays cannot be _____________; it is only absorbed and filtered

poly-energetic or heterogenous

x-rays form _________ beams; can be produced in different energies

straight

x-rays travel in _______ lines

penetrate

x-rays can ________ human bodies; this also explains how x-rays can reach the image receptor

fluoresce

x-rays can cause substances to ________ (can cause materials to light up)

chemical changes

x-rays can cause __________ to occur in radiographic and photographic films

no mass

what is the mass of x-rays?

absorbed or scatteresd

x-rays can be ____________ by tissues in the human bodies

chemical and biological

x-rays can cause _________ damage to living tissues

gurney mott theory

theory of latent image production

x-ray tube

where x-ray is usually produced

inverse square law

the intensity of electromagnetic radiation is inversely related to the square of the distance from the source

exposure dose

amount of radiation traveling through the air

roentgen

conventional unit for exposure dose

coulomb/kg

SI unit for exposure dose

air kerma

the kinetic energy transferred from photons to electrons during ionization and excitation; exposure dose

radiation absorbed dose

describes the amount of radiation absorbed by an object or person; radiation energy absorbed per unit mass

rad

conventional unit for radiation absorbed dose

gray (Gy_t)

SI unit for radiation absorbed dose

equivalent dose

combines the amount of radiation absorbed and the medical effects of that type of radiation; measurement of the biological effects of the radiation on a specific tissue or organ exposed to specific type of radiation

rem (radiation equivalent man)

conventional unit of equivalent dose

sievert (Sv)

SI unit of equivalent dose

effective dose

whole body radiation dose; used to estimate the tissue and organ radiobiological detriment from imaging

sievert (Sv)

SI unit of effective dose

radioactivity

refers to the amount of ionizing radiation released by a material

curie (Ci)

conventional unit of radioactivity

becquerel (Bq)

SI unit of radioactivity

support structure, protective housing, glass or metal enclosure

external components of x-ray tube

support structure

ceiling, floor-to-ceiling, c-arm support system

ceiling support system

most frequently used; consists of 2 perpendicular sets of ceiling mounted rails that allows for both longitudinal and transverse travel of the x-ray tube

floor-to-ceiling support system

has a single column at each end (one attached to a ceiling mounted rail and the other attached to a floor mounted rail)

c-arm support system

these systems are ceiling mounted and provide for very flexible x-ray tube positioning; usually used in interventional radiology

dynamic images

images that are moving

protective housing

provides mechanical support for the x-ray tube and protects the tube from damage caused by rough handling

protective housing

guards against excessive radiation exposure and electric shock

leakage radiation

x-rays that escape through the protective housing

useful beam

the x-rays emitted through the window section of the protective housing

heat dissipation

the ability of the material to withstand heat

diala oil

oil in x-ray tubes that serves as both insulator against electric shock and as a thermal cushion to dissipate heat

pyrex

type of glass used in x-ray tubes as it has the ability to withstand tremendous heat

vacuum

allows for more efficient x-ray production and a longer tube life; located in glass/metal enclosure

cathode

negative side of the x-ray

primary parts of cathode

filament and focusing cup

filament

coil of wire; emits electron when it is heated

thoriated tungsten

makes up the filament

3410 degree celsius

melting point of thoriated tungsten

thermionic emission

when the outer-shell electrons of the filament atoms are boiled off and ejected from the atom

focusing cup

a negatively charged metal that electrostatically confines the electron beam to a small area of the anode

anode

positive side of the x-ray tube

anode

conducts electricity and radiates heat and x-rays from the target

types of anode

stationary and rotating

stationary anode

high tube current and power are not required

stationary anode

used in dental and portable x-ray imaging systems

rotating anode

capable of producing high intensity x-ray beam in a short period of time

rotating anode

used in general x-ray

3 functions of anode in x-ray tube

electrical conductor, mechanical support for the target, thermal dissipater

electrical conductor

anode acts as _______ as it receives electrons emitted by the cathode and conducts them through the tube to the connecting cables back to the high voltage generator

the anode stem

it serves mechanical support for the target; connects anode disc to the remainder of the anode assembly

target

the area of anode struck by the electrons from the cathode

tungsten alloy

in stationary anode, the target consists of ________ embedded in copper anode

3400 degree celsius

melting point of tungsten alloy

rotating disc

in rotating anode tubes, the ______ is the target

copper, molybdenum, graphite

most common anode materials

molybdenum or graphite

high-capacity x-ray tubes have _______________ layered under the tungsten target as it has lower mass density , making the anode lighter and easier to rotate

tungsten target

target material of choice for general radiography

atomic number (74)

results in high-efficiency x-ray production and in high-energy x-rays (tungsten)

thermal conductivity

tungsten has a _________ nearly equal to that of a copper; efficient metal for dissipating the heat produced

high melting point (3400 degree celsius)

tungsten has a ____________ and therefore can stand up under high tube current without pitting of bubbling

1100 degree celsius

melting point of copper

boiling off of electrons

other term for thermionic emission; production of electrons

electron space charge

cloud of electrons

space charge effect

process of creating electrons space charge

99%

approximately ______ of the kinetic energy of electrons from the cathode is converted into heat

1%

approximately ____ of electron kinetic energy is used for production of x-radiation

acceleration

occurs when the electrons created from the cathode will be attracted to the anode target; high voltage helps electrons stream toward the anode

deceleration

occurs once the electrons hit the target