Dental Radiology - Written Exam 2

Front 1

Wavelength determines what?

Back 1

energy and penetrating power of radiation

Front 2

X-rays with shorter wavelengths have ______ penetrating power as to x-rays with longer wavelengths have _____ penetrating and more likely to be absorbed by matter.

Back 2

1. more

2. less

Front 3

What is radiology?

Back 3

study of radiation used in medicine

Front 4

What is radiography?

Back 4

art and science of making radiographs by exposure of film to x-ray

Front 5

What is radiation?

Back 5

form of energy carried by waves of stream of particles.

Front 6

Protons/Neutrons are located in the ________ of an atom while Electrons _________ the nucleus in an electron cloud.

Back 6

1. nucleus

2. orbit/circle

Front 7

What is particulate radiation?

Back 7

tiny particles of matter that possess mass & travel in lines at high speeds, transmitting kinetic energy... energy is normally absorbed into body which causes detrimental changes to tissue by ionizaton.

Front 8

Cathode rays are?

Back 8

streams of high-speed electrons, originate in x-ray tube.

Front 9

Beta particles are?

Back 9

fast moving electrons emitted from the nucleus of radioactive atoms.

Front 10

Alpha particles are?

Back 10

emitted from nuclei of heavy metals and exist as protons and neutrons.

Front 11

Protons are?

Back 11

hydrogen nuclei, w/ mass of 1 and charge of +1 (positive)

Front 12

Neutrons are?

Back 12

accelerated particles, hydrogen nuclei w/ mass of 1 and no electrical charges.

Front 13

Gamma radiation is a form of?

Back 13

electromagnetic radiation

Front 14

Electromagnetic radiation is?

Back 14

wave-like energy (w/ out mass) through space & matter. Energy is w/ oscillating electric & magnetic fields positioned @ right angles. It can be manmade or occur naturally...including cosmic rays, gamma rays, x-rays, etc.

Front 15

How is the energy for electromagnetic radiation?

Back 15

it is NOT absorbed into body causing ionization/damage.. --> high penetration

Front 16

Within electrons, what has the most binding energy (distance away from nucleus)?

Back 16

closest shell or "K shell"

Front 17

Electrons located on the outer shells have ________ binding energies, therefore can cause _____________.

Back 17

1. weaker

2. ionization

Front 18

What is the required kVp to break the binding energy from the K shell in a tungsten atom?

Back 18

70 kVp

Front 19

Shell strength order?

Back 19

K, L, M, N, O, P and Q (or 1, 2, 3, 4, 5, 6, & 7)

Front 20

What are the subshells?

Back 20

S, P, D, F, & G (Examples: 1s, 2s, 2p, 3s, 2, 3d, etc)

Front 21

Define ionization :

2 examples?

Back 21

1. production of ions or conversion of atom into ion by removing/adding electrons.

2. cation and anion

Front 22

4 common characteristics of electromagnetic radiations :

Back 22

1. no mass/weight

2. no electrical charge

3. all forms of radiation travel @ speed of light (C= 3 X 10*8)

4. travels both as a particulate and as a wave

Front 23

What is wavelength?

Back 23

distance from crest of one wave to the next

Front 24

What is frequency?

Back 24

how many wavelengths in a given amount of time

Front 25

If frequency is high, then wavelength is ____

Back 25

short and vice versa

Front 26

High frequency means a particular energy is _____

Back 26

high

Front 27

Why is it good that higher energy wavelengths have better potential to penetrate/pass through tissue?

Back 27

does NOT cause tissue damage because it is NOT absorbed.

Front 28

Radiotherapy characteristics :

Back 28

- also known as x-ray

- 1/100,000 nm

- small wavelength so energy/frequency is higher

Front 29

Dental radiography's wavelength frequency to common radiations in electromagnetic spectrum -

Back 29

1/10 nm

Front 30

Suns wavelenth freq. to common radiations in electro. spectrum -

Back 30

10 nm

Front 31

Microwaves wavelength freq. to common radiations in electro. spectrum -

Back 31

100,000 nm

Front 32

Televisions wavelength freq. to common radiations in electro. spectrum -

Back 32

1 meter (m)

Front 33

Radio wavelength freq. to common radiations i electro. spectrum -

Back 33

1,000 meters (not very powerful type of wavelength due to long wave & short freq.)

Front 34

Acronyms for Radiotherapy, Dental radiography, sun, microwave, television, radio -

Back 34

R D S M T R

Front 35

Cathode definition -

Back 35

neg electrode that consists of tungsten filament and molybdenum cup for thermionic emission

Front 36

Molybdenum cup -

Back 36

focuses electrons produced by tungsten filament and directs them across the tube towards target

Front 37

Tungsten filament -

Back 37

when heated, it produces electrons that gather at the electron cloud

Front 38

Step down transformer aids by?

Back 38

lowering the voltage of the current for thermionic emission to happen

Front 39

Anode?

Back 39

positive electrode that consists of the tungsten target and the copper stem

Front 40

What is the function of the copper stem?

Back 40

to dissipate heat away from the tungsten target during x-rays

Front 41

What do Aluminum disks do?

Back 41

absorb low energy x-rays produced at the tungsten target (low energy = potentially dangerous)

Front 42

Leaded glass housing -

Back 42

leaded vacuum tube that prevents x-rays from scattering or escaping in all directions

Front 43

Window -

Back 43

ONLY location on leaded housing that is NOT made of lead / lets out x-rays to leave the tube and enter the PID

Front 44

Lead collimator (round or rectangular) -

Back 44

lead plate that restricts the size of the x-ray for lesser radiation exposure.

Front 45

Transformer -

Back 45

device that alters the voltage of incoming electricity.

Front 46

Thermionic emission -

Back 46

release of electrons from tungsten filament when electric current passes through it and heats up

Front 47

How many volts does the filament circuit use to heat up the tungsten filament in the cathode portion of the tube?

Back 47

3-5 volts

Front 48

The electrons for thermionic emission stay in an electron cloud until the -

Back 48

high-voltage circuit is activated

Front 49

What has to happen FIRST in order for the thermionic emission to occur?

Back 49

step-down transformer has to decrease the voltage coming from the wall

Front 50

step-down transformer contains how many volts?

Back 50

(110 volts) ; 3-5 volts

Front 51

Which transformer has MORE wire coils in the primary (input side) than the secondary coil (output side)?

Back 51

step-down transformer

Front 52

Step-up transformer is used to -

Back 52

increase voltage from incoming 110 voltage line to the needed 65,000 - 100,000 volts required for exposure.

Front 53

Which transformer has MORE secondary coils than primary coils?

Back 53

step- up transformer

Front 54

Autotransformer -

Back 54

serves as a voltage compensator that corrects minor fluctuations so a steady voltage remains for a steady x-ray

Front 55

Braking (bremsstrahlung) radiation -

Back 55

sudden stopping of high-speed electrons when they hit the tungsten target in the anode.

Front 56

What percentage of x-rays are produced by braking radiation?

Back 56

70%

Front 57

The electrons that hit the nucleus directly become completely converted into a -

Back 57

x-ray photon

Front 58

Braking radiation consists of x-rays of many different _____________ & ______________.

Back 58

energies and wavelengths

Front 59

What is the amount of energy (kvp) required to dislodge an inner shell tungsten atom?

Back 59

70 kvp

Front 60

Ampere (amount of electrons) -

Back 60

intensity of an electrical current produced by 1 volt acting through a resistance of 1ohm.

Front 61

Volt (speed of electrons) -

Back 61

unit of electromotive force that drives an electrical current through a circuit

Front 62

Resistance -

Back 62

opposing of 1 force or thing to another

Front 63

Alternating current -

Back 63

current that comes out of the wall and flow into 2 different directions --> meaning negative side (cathode) and positive side (anode) swap back and forth.

Front 64

Direct current -

Back 64

current flows in one direction through the conductor

Front 65

Rectification -

Back 65

process in which the AC is converted into DC to produce x-rays --> ensures electrons are always flowing in a certain direction

Front 66

Half-wave rectification -

Back 66

process in which negative side is removed from the wave so that the charges never swap. --> this is INEFFICIENT because electrons will slow during phases when the negative portions were taken out.

Front 67

Full-wave rectification -

Back 67

process in which wave is completely positive... ensures wave works at max energy and speed helps electrons flow,

Front 68

Full-wave rectification reduces pt exposure by _____ %

Back 68

20

Front 69

Ionization is also known as -

Back 69

photoelectric effect

Front 70

Kilovoltage increases intensity in __________ and _________

Back 70

quantity and quality

Front 71

Inverse square law -

Back 71

intensity of radiation is inversely proportional to the square of distance from the source of radiation (therefore, the further away the x-ray beams are from the person - the less intense the x-ray beam is)

Front 72

Density -

Back 72

overall darkness/blackness of film

Front 73

Contrast -

Back 73

how sharply dark / light segments are on an x-ray

Front 74

Low kvp = ______ contrast

High kvp = ______ contrast

Back 74

low = high

high = low

Front 75

If mA is increased, it will make density _______ so the image will then turn ________.

Back 75

density higher - make image turn darker

Front 76

Photoelectric effect -

Back 76

ionization takes place --> photon collides with tightly bounded inner shell electron ejecting inner electron called "photoelectron"

Front 77

Photoelectric effect accounts for ____ % of all x-ray interactions w/ matter.

Back 77

30%

Front 78

Compton scatter -

Back 78

occurs when x-ray photon is deflected from its path during its passage through matter

Front 79

What takes place during compton scatter?

Back 79

ionization of tissue

Front 80

For compton scatter, the photon collides w/ a _______ bound outer shell electron and gives up part of its energy in order to eject that electron.

Back 80

loosley

Front 81

Ejected electron is called a -

Back 81

compton electron

Front 82

Compton scatter accounts for ____ % of all x-ray reactions.

Back 82

62%

Front 83

Image definition refers to the -

Back 83

sharpness

Front 84

Smaller the focal spot = _________ the image.

Back 84

sharper

Front 85

mA controls the # of?

Back 85

electrons

Front 86

Increasing the mA __________ the # of electrons so that it will hit the tungsten target.

Back 86

increases

Front 87

Kvp affects both ________ & ________

Back 87

density and contrast

Front 88

kvp increased means _______ is then increased

Back 88

density

Front 89

Short scale (high contrast) -

Back 89

contains many black and white areas, but only a few shades of gray. (low kvp)

Front 90

Long-scale (low contrast) -

Back 90

contains many shades of gray, but only a few shades of black and white (high kvp)

Front 91

Penumbra -

Back 91

refers to unsharpness or shadow (blurriness) that surrounds edges of x-ray

Front 92

4 factors that the penumbra is affected by -

Back 92

1. focal spot size (small spot = clear image)

2. focal spot (tungsten) to object distance

3. object to film distance

4. movement

Front 93

Elongation -

Back 93

film is too flat causing teeth to look long

Front 94

Foreshortening -

Back 94

film is too steep causing teeth to look dwarfed

Front 95

Absorbed dose -

Back 95

measure of energy ionizing radiation absorbed by per unit of mass of matter

Front 96

Traditional unit: rad (radiation absorbed dose) = ?

Back 96

100 ergs/g of absorber

Front 97

S.I. unit: Gy (gray) = ?

Back 97

Joule/Kg

Front 98

Conversion: 1 rad = ?

1 Gy = ?

Back 98

1 rad = 0.01 Gy

1 Gy = 100 rad

Front 99

Equivalent dose is used to compare -

Back 99

biological effects of different types of radiation

Front 100

Radiation weighing factor depends on -

Back 100

type and energy of radiation involved

Front 101

Rem (roentgen equivalent in man) = ?

Back 101

rad (absorbed dose) x Wr (radiation weighing factor)

Front 102

Equivalent dose (III) for S.I. unit = ?

Back 102

Sv (sievert)

Front 103

Conversion for Equivalent dose (III):

1 rem = ?

1 Sv = ?

Back 103

1 rem = 0.01 Sv

1 Sv = 100 rem

Front 104

Acute radiation syndrome -

Back 104

large dose of radiation absorbed in short period of time (like atomic bomb)

Front 105

4 periods/syndromes w/ in acute radiation syndrome -

Back 105

1. prodromal period

2. hematopietic syndrome

3. gastrointestinal syndrome

4. CNS syndrome

Front 106

Prodromal syndrome -

Back 106

shortly after exposure person could develop nausea, diarrhea, vomiting, etc

Front 107

Hemopoietic syndrome -

Back 107

irreversible injury to spleen/bone marrow w/ loss of circulating peripheral blood cells

Front 108

4 characteristics of Hemopoietic syndrome -

Back 108

1. infection from lymphopenia & granulocytopenia

2. hemorrhage from thrombocytopenia

3. anemia from erythrocytopenia

4. death w/ in 10-30 days

Front 109

5 characteristics of GI syndrome -

Back 109

1. loss of plasma/electrolytes

2. hemorrhage/ulceration

3. diarrhea, dehydration, weight loss

4. infection

5. death in 3-5 days

Front 110

Death for CNS syndrome is -

Back 110

few minutes to 48 hours

Front 111

Radiation effects on oral cavity:

1. Mucosa = ?

2. Salivary glands = ?

3. Taste buds = ?

4. Teeth = ?

5. Bone = ?

Back 111

1. mucositis

2. xerostomia

3. loss of taste

4. caries

5. osteoradionecrosis

Front 112

Secondary infection that is a common complication with mucositis?

Back 112

candida albicans

Front 113

Is mucositis painful?

Back 113

VERY

Front 114

Mucositis healing occurs in about ___-___ months

Back 114

1-2 months

Front 115

Another word for loss of taste buds?

Back 115

hypogeusia

Front 116

Epithelial atrophy, xerostomia and mucositis all results in hypogeusia by the ___ to ___ week of treatment

Back 116

2nd to 3rd week

Front 117

Recovery of taste sensitivity will occur in ____-___ months

Back 117

2-4

Front 118

Residual saliva has a lowered pH from 6.5 to? (which is acidic enough to initiate decalcification of enamel)

Back 118

5.5

Front 119

Buffering capacity of saliva is reduced ____-___%

Back 119

40-45%

Front 120

Dryness of mouth subsides in ___ months to ___ year.

Back 120

6 months to 1 year