Radiation Physics Chapter 2

Front 1

what is matter?

Back 1

anything that occupies space & has mass

Front 2

when does energy result?

Back 2

when matter is altered.

Front 3

what is the fundamental unit of matter?

Back 3

an atom

Front 4

the atom consists of 2 parts, what are they?

Back 4

central nucleus and orbiting electrons

Front 5

how is the identity of an atom determined?

Back 5

by its composition of its nucleus and the arrangement of its orbiting electrons

Front 6

at present, how many different atoms exist?

Back 6

105

Front 7

the dense core of the atom composed of particles is known as what?

Back 7

nucleus

Front 8

nucleus is composed of what?

Back 8

protons and neutrons(also known as nucleons)

Front 9

the nucleus of an atom occupies very little space, most of the atom is empty space. t/f

Back 9

true

Front 10

what determines the mass number or atomic weight?

Back 10

the number of protons and neutrons in the nucleus of an atom.

Front 11

atomic number is determined by what?

Back 11

number of protons inside the nucleus equals the number of electrons outside the nucleus

Front 12

elements are substances made up of only one type of atom. t/f

Back 12

t

Front 13

electrons travel around the nucleus in well defined paths known as what?

Back 13

orbits or shells

Front 14

what is the max number of shells that an atom contains?

Back 14

seven

Front 15

each shell is at at different distances from the nucleus and this represents different energy levels. what letters designate the shell?

Back 15

K-Q.

Front 16

which energy shell is located closest to the nucleus?

Back 16

Kshell

Front 17

which shell has the highest energy level?

Back 17

k shell

Front 18

electrons are maintained in their orbits by what force?

Back 18

electrostatic force

Front 19

the binding energy or binding force of an electron is what?

Back 19

the attraction btwn the positive nucleus and negative electrons

Front 20

what determines the binding energy?

Back 20

the distance btwn the nucleus and the orbiting electron and it's diff for each shell

Front 21

the strongest binding energy is found closest to the nucleus in what shell?

Back 21

k shell

Front 22

electrons located in the outer shells have a stronger or weaker binding energy?

Back 22

weak

Front 23

the binding energies of orbital electrons are measured in what measurements?

Back 23

electron volts (eV) or kil electon volts (keV)

Front 24

one kil elecron volt equals how many eVs?

Back 24

1000

Front 25

the energy required to remove an electron from its orbital shell must exceed what?

Back 25

the binding energy of the electron in that shell

Front 26

atoms are capable of combing with each other to form what?

Back 26

molecules

Front 27

how is a molecule defined?

Back 27

as two or more atoms joined by chemical bonds
OR
the smallest amount of a substance that possesses its characterstic properties

Front 28

molecules are formed in one of two ways. what are the two ways?

Back 28

1. by the transfer of electrons
2. by the sharing of electrons btwn the outermost shells of atoms

Front 29

a neutral atom contains equal numbers of protons and electrons. t/f

Back 29

t

Front 30

an atom that gains or loses an electron and becomes electrically unbalanced is known as what?

Back 30

an ion

Front 31

ionization is what?

Back 31

the production of ions or the process of converting an atom into ions

Front 32

ionization deals only with electrons and protons & requires sufficient energy to overcome the electrostatic force that binds the electron to the nucleus. t/f

Back 32

f: it only deals with electrons

Front 33

when an electron is removed from an atom in the ionization process, what results?

Back 33

an ion pair

Front 34

when an ion pair is formed, which is the positive ion and which is the negative one?

Back 34

the atom is positive ion and the electron that is ejected is the negative ion

Front 35

radiation is what?

Back 35

the emmision and propagation of energy through space or a substance in the form of waves or particles.

Front 36

radiation and radioactivity basically have the same meaning. t/f

Back 36

f. they DO NO have the same meaning.

Front 37

Radioactivity is defined as what?

Back 37

the process by which certain unstable atoms or elements undergo SPONTANEOUS disintegration or decay, in an effort to attain a more balanced nuclear state.

Front 38

if a substance gives off energy in the form of particles or rays as a result of the disintegration of atomic nuclei, it is considered what?

Back 38

radioactive

Front 39

in dentistry, what is used? radiation or radioactivity?

Back 39

radiation, specifically x-radiation

Front 40

ionizing radiation is defined as what?

Back 40

radiation that is capable of producing ions by removing or adding an electron to an atom

Front 41

ionizing radiation is classified into 2 groups: _______ and _______

Back 41

particulate radiation
and
electromagnetic radiation

Front 42

radiation that is capable of producing ions by removing or adding an electron to an atom is known as what?

Back 42

ionizing radiation

Front 43

what's particulate radiations?

Back 43

tiny particles of matter that possess mass and travel in straight lines and at high speeds

Front 44

what type of radiation transmits kinetic energy by means of their extremely fast moving, small masses?

Back 44

particulate radiations

Front 45

four types of particulate radiation are recognized. what are they?

Back 45

1. electrons (beta particles = fast moving electrons from the nucleus of radioactive atoms. cathode rays = streams of high speed electrons originating from xray tube)
2. alpha particles
3. protons
4. neutrons

Front 46

electrons can be classified into 2 categories. what are they & their origins?

Back 46

1. beta particles = fast moving electrons emited from NUCLEUS of radioactive atoms
2. cathode rays = streams of high speed electrons that originate in an xray tube

Front 47

alpha particles are emitted from where? and how do they exist?

Back 47

alpha particles are emitted from the nuclei of heavy metals and exist as TWO protons and neutrons, without electrons

Front 48

alpha particles: do they have electrons, protons or neutrons? or all 3?

Back 48

only protons and neutrons. NO electrons

Front 49

protons are accelerated particles, specifically what type of nuclei? what mass and what charge?

Back 49

hydrogen nuclei.
mass of 1.
charge of +1.

Front 50

neutrons are accelerated particles with mass of what and charge of what?

Back 50

mass of 1.
no charge.

Front 51

define electromagnetic radiation

Back 51

propagation of wavelike energy (without mass) through space or matter.

Front 52

why the term electromagnetic?

Back 52

bc energy propagated is accompained by oscillating electric & magnetic fields positioned at right angles to one another

Front 53

oscillating electric and magnetic fields are characterstics of what type of radiations?

Back 53

electromagnetic

Front 54

which type of radiations have:
no mass
no weight
no electrical charge
travel at the speed of light (3x10^8m/s)
travel both as a particle and a wave
?

Back 54

electromagnetic radiations

Front 55

which radiation:
-propagates as an electric field at RIGHT angles to path of travel
-propagate a magntetic field at right angles to the electric field
-has different measurable energies (frequencies and wavelengths)

Back 55

electromagnetic radiations

Front 56

what are examples of electromagnetic radiations?

Back 56

cosmic rays, gamma rays, xrays, UV rays, visible light, IR, radar waves, microwaves and radio waves

Front 57

electromagnetic radiations are arranged according to their energies into what?

Back 57

the electromagnetic spectrum

Front 58

electromagnetic radiations can be classified as:

Back 58

ionizing
or non-ionizing

Front 59

only high energy radiations are capable of ionization in the electromagnetic spectrum. t/f

Back 59

t

Front 60

what are examples of high energy radiations

Back 60

cosmic rays
gamma rays
xrays

Front 61

what are the 2 concepts when dealing wtih electromagnetic radiations?

Back 61

particle concept
and
wave concept
bc it can travel through space as both a particle and a wave

Front 62

the particle concept characterizes electromagnetic radiations as descrete bundles of energy called?

Back 62

quanta or photons

Front 63

do photons or quanta contain weight or mass? how much

Back 63

no. none!

Front 64

wavelength is the distance btwn what?

Back 64

the crest/peak of one wave and the crest of the next

Front 65

the wave concept characterizes electromagnetic radiations deals with what 3 concepts?

Back 65

velocity
wavelength
frequency

Front 66

velocity = speed of the wave. how fast do electromagenetic radiations travel?

Back 66

speed of light
3 x 10^8 m/s or 186,000 miles per second

Front 67

wavelength determines the energy and what?

Back 67

penetrating power of hte radiation

Front 68

the shorter the distance btwn crests, the shorter the wavelength and the ______ the energy and ability to penetrate matter

Back 68

HIGHER

Front 69

what unit is wavelength measured in?

Back 69

nanometers for short waves, and meters for longer waves

Front 70

frequency is the number of _______ that pass a given point in a certain amount of _____.

Back 70

wavelengths
time

Front 71

the shorter the wavelength, the higher the frequency. t/f

Back 71

t

Front 72

low frequency = longer waves = _____ energy.

Back 72

less.

Front 73

the 3 components parts of dental xray machine are what?

Back 73

1. control panel
2. extension arm
3. tube head

Front 74

dental xray machine can be divided into 3 study areas =

Back 74

1. component parts
2. xray tube
3. xray generating apparatus

Front 75

what am i? i am the metal body of hte tubehead that surrounds the xray tube and transforms and is filled with oil. i protect the xray tube and ground the high voltage components

Back 75

metal housing

Front 76

what am i? i'm the oil that surrounds the xray tube and transforms insdet he tubehead, i prevent overheating by absorbing the heat created by the production of xrays

Back 76

insulating oil

Front 77

what am i? i am the aluminum or leaded glass covering of the tubehead that permits the exit of xrays from the tubehead. i seal the oil int he tubehead and act as a filter to the xray beam.

Back 77

tubehead seal

Front 78

what am i? i am the heart of hte xray generating system

Back 78

x ray tube

Front 79

what am i? i'm a device that alters the voltage of incoming electricity

Back 79

transformer

Front 80

what am i? sheets of 0.5 mm thick aluminum placed in the path of hte xray beam, i filter out hte non penetrating, longer wavelength xrays.

Back 80

aluminum disks

Front 81

what am i? i am the lead plate with a central hole that fits directly over the opening of the metal housing where the xrays exit, i restrict the size of the xray beam

Back 81

lead collimator

Front 82

what is the collimator made out of?

Back 82

lead

Front 83

what am i? i am the open ended lead lined cylinder that extends from the opening of the metal housing of the tubehead and i aim and shape the xray beam

Back 83

PID = position indicating device

Front 84

what does the leaded glass housing do?

Back 84

prevents xrays from escaping in all directions

Front 85

the cathode consists of what 2 things?

Back 85

tungsten filament producing electrons when heated
and
molybdenum cup which focuses the electrons into a narrow beam, directing the beam across the tube toward the tungsten target of hte anode

Front 86

what's the purpose of hte anode?

Back 86

to convert electrons into xray photons

Front 87

what is the anode composed of?

Back 87

tungsten target (serves as a focal spot, convering bombarding electrons into xrays)
and
copper stem (dissipates the heat away from the tungsten target)

Front 88

copper stem does what?

Back 88

dissipates the heat away from the tungsten target

Front 89

tungsten target does what?

Back 89

serves as a focal spot, convering bombarding electrons into xrays

Front 90

tungsten filament does what?

Back 90

produces electrons when heated

Front 91

what does the molybdenum cup do?

Back 91

focuses electrons into a narrow beam, directing it across the tube towards the anode target

Front 92

electricity is defined as?

Back 92

the energy used to make xrays

Front 93

the flow of electrons is known as the?

Back 93

electric current

Front 94

direct current occurs when electrons flow in ___ direction through the conductor.

Back 94

one

Front 95

alternating current (AC) describes what?

Back 95

electrical current where electrons flow in two opposite directions

Front 96

rectification is what?

Back 96

conversion of AC into DC

Front 97

conversion of AC into DC is known as what?

Back 97

rectification

Front 98

the dental xray is a self-rectifier and changes ____ into _____ while producing xrays, ensuring current is flowing from cathode to anode.

Back 98

AC into DC

Front 99

constant-potential machines reduce patietn exposure to radiation by ___%

Back 99

20%

Front 100

what is the measurement of hte number of electrons moving through a conductor?

Back 100

amperage

Front 101

current is measured in what?

Back 101

A = amperes
or
mA = miliaperes

Front 102

voltages is measured in?

Back 102

volts or kilvolts

Front 103

voltage is?

Back 103

the measurement of electrical force that causes electrons to move from a negative pole to a positive one

Front 104

amperage = number of electrons passing through the ___ filament and can be increased or decreased by what adjustment?

Back 104

cathode filament
miliamperage adjustment

Front 105

the voltage of the xray tube current, or the current passing from the cathode to the anode is controlled by what?

Back 105

kilovoltage peak kVp

Front 106

kilovoltage peak controls what?

Back 106

the voltage of the xray tube current, or the current passing from the cathode to the anode

Front 107

circuits are paths of electrical current. the low voltage circuit is also known as?

Back 107

filament circuit

Front 108

filament circuit (low voltage) uses how many volts?

Back 108

65,000 to 100,000 volts.

Front 109

transformers are devices that do what?

Back 109

increase or decrease the voltage in an electrical circuit

Front 110

in the production of dental xrays, 3 transformers are used to adjust the electrical circuits. what are they?

Back 110

1. step down transformer
2. step up transformer
3. autotransformer

Front 111

the step-down transfoerm decreases the voltage from the INCOMING 110 or 220 line voltage to what?

Back 111

3 - 5 volts used by the filament circuit

Front 112

what side has the more coils in a step down transformer?

Back 112

the primary coil(the voil receiving the alternating electrical current, or input coil)

Front 113

the secondary coil is the output coil, while the primary coil is the input coil. t/f

Back 113

t

Front 114

the step up transformer increases the voltage from the incoming 110 or 220 line voltage to what?

Back 114

65,000 to 100,000 volts used by the high voltage circuit.

Front 115

the step up transformer has more coils on which coil?

Back 115

secondary coil

Front 116

general radiation is known as different names such as?

Back 116

braking radiation
or
bremsstrahlung radiation

Front 117

why is it called braking radiation?

Back 117

sudden stopping of high speed electrons when they hit the tungsten target int he anode

Front 118

70% of hte xray energy produced at the anode can be classified as which type of radiation?

Back 118

general radiation

Front 119

when an electron that passes close to the nucleus of a tungsten atom is slowed down, an xray photon of lower energy known as __________ results.

Back 119

general (braking) radiation

Front 120

general radiation consists of xrays of few, moderate, or many different energies and wavelengths?

Back 120

MANY

Front 121

characteristic radiation is produced when?

Back 121

when a high speed electron dislodges an inner shell electron from the tungsten atom and causes ionization of that atom. rearrangement occurs and prodces a loss of energy resulting in xray photon production

Front 122

characterstic radiation accounts for a very small part of xrays in the dental field. t/f

Back 122

t

Front 123

characteristic radiation occurs only at ________ kVp bc why?

Back 123

70 kVp and above.
bc the binding energy of hte K shell electron is approx 70 keV

Front 124

primary radiation refers to what?

Back 124

the penetrating xray beam produced at the target of the anode and that exits the tube head

Front 125

primary radiation is often referred to what 2 other terms?

Back 125

primary beam
or
useful beam

Front 126

secondary radiation is what?

Back 126

refers to xradiation that is created when primary beam interacts with matter (skull)

Front 127

a form of secondary radiation that results when an xray is deflected is called what?

Back 127

scatter radiation

Front 128

when xray exits tubehead 3 things can happen. what are they?

Back 128

1. xrays can pass through the patient without any interaction
2. xray photons can be completely absorbed by the patient
3. xray photons can be scattered

Front 129

four possibilities can occur (at the atomic level) when an xray photon interacts with matter. what are they?

Back 129

1. no interaction
2. absorption or photoelectric effect
3. compton scatter
4. coherent scatter

Front 130

is it possible for an xray photon to pass through matter or the tissue of a patient without any interaction?

Back 130

yes

Front 131

the xray photons that pass through a patient without interaction are responsible for producing ______ on the film

Back 131

densities

Front 132

absorption =

Back 132

total transfer of energy from xray photon to the atoms of matter through which the xray beam passes.

Front 133

at the atomic level, absorption occurs as a result of the ______ effect.

Back 133

photoelectric effect

Front 134

in the photoelectric effect, ionization occurs. t/f

Back 134

t

Front 135

the ejected electron (during hte photoelectric effect) is termed what? and what charge is it?

Back 135

photoelectron and has a negative charge

Front 136

when an xray photon collides with an inner shell electrion, a ________ effect occurs: the photon is absorbed and ceases to exist and a ________ with a negative charge is produced

Back 136

photoeletric effect
photoelectron

Front 137

compton scatter occurs when an xray photon is deflected from its path during its passage through matter. t/f

Back 137

t

Front 138

most of the scatter radiation is due to what effect?

Back 138

the compton effect

Front 139

ionization takes place in compton scatter as well as the photoelectric effect.t/f

Back 139

t

Front 140

when an xray photon collides with a loosely bound outer shell electron and gives up part of its energy to eject the electron from its orbit, what type of scatter occurs?

Back 140

compton

Front 141

in compton a newer xray photon is produces. does it have lower or higher energy?

Back 141

it's weaker with lower energy

Front 142

the ejected electron in compton scatter is refered to as what? and what charge does it have?

Back 142

comtpon electron
or
recoil electron.
negative charge

Front 143

compton scatter accounts for ______ % of the scatter that occurs in diagnostic radiography.

Back 143

62%

Front 144

coherent scatter occurs when?

Back 144

xrays interact with matter

Front 145

another name of coherent scatter is what?

Back 145

unmodified scatter

Front 146

when an xray photon is scattered and NO loss of energy occurs, what scatter is this?

Back 146

coherent scatter

Front 147

when a low energy xray photon interacts with an outer shell electron this is known as what type of scatter? no chnage in the atom occurs

Back 147

coherent

Front 148

no loss of energy, no ionization occur in what scatter?

Back 148

coherent

Front 149

which types of scatter have ionization? which don't?

Back 149

ionization: compton, photoelectric
no ionization: coherent

Front 150

it's called "unmodified" scatter why?

Back 150

bc it simply undergoes a CHANGE IN DIRECTION without a change in energy!

Front 151

coherent scatter accounts for ___% of interactions of matter with the dental xray beam.

Back 151

8%

Front 152

list the % for photoelectric, compton, and coherent scatters

Back 152

photoelectric: 30%
compton scatter: 62%
coherent scatter: 8%