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D1 BS1 + II/ FSI + II > radiology > Flashcards

radiology Flashcards

1
Q

name the order of the rays

A

radio, micro, infrared, vl, UV, xrays, gamma (most dangerous)

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2
Q

focal spot

A
  • located on the anode
  • area on target where focusing cup directs electrons from filament. Sharpness of radiograph increases as size of this spot decreases (can be done by dec angulation)
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3
Q

why is tungsten the best

A
  • high atomicc number, high melting point, thermal conductivity, low vapor pressure
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4
Q

bensons line focus principle

A
  • smaller the anode tilt, the smaller the effective focal spot
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5
Q

cathode

A
  • in mA, contains the filament
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6
Q

anode

A
  • positive
  • kV, contains focal spot and tungsten target
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7
Q

mA determines

A

number of e made, increasing this will increase quantity of xray beams

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8
Q

kVp

A

(kVp is for AC, KvC is for DC which is better)
determines energy of the xrays produced
- increases the quality of the xray

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9
Q

filtration

A

reduces intensity, increases the mean energy so less rad to patient

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10
Q

target object distance

A
  • increase it means increased image sharpness!!
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11
Q

photoelectric absorption

A
  • the scatter ray that interacts with matter to form the image
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12
Q

particulate radiation

A

alpha, beta, cathode

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13
Q

compton scatter

A
  • most interaction, cause of scatter
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14
Q

coherent scatter

A

least common scatter

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15
Q

attenuation

A

absorption of individual photons in the beam by atoms in tissues or photons being scattered

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16
Q

beam hardening

A
  • increase mean energy and decrease intensity
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17
Q

cell cycle and radiosensitivity

A
  • less radiosensitive in g1, least in s phase, most in g2 and m phase
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18
Q

chromosome aberration

A

occurs when rad before DNA synth

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19
Q

chromatid abberation

A

after dna synth rad

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20
Q

what cells are rad resistant and which are most

A
  • fully differentiated cells
  • lymph ccells are MOST
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21
Q

where does most radiation come from

A

radon and ct scan

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22
Q

best radiographic practice

A
  • usse E/F speed film
  • rare earth screen for films
  • use CBCT for region of interest
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23
Q

personal protection

A

stand more than 6 ft away, use backscatter shield
- use long cone head
- stand at 90 to 135 degrees from central beam

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24
Q

collimators

A

rectangular is 66% less area than round!

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25
Q

parallelling technique

A
  • sensor is parallel to central axis
  • longer object film distance (16”)
  • pros: teeth are accurate, minimal distortion, less rad
  • disadvL sensor is big, longer distance may mean higher mag and lower sharpness
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26
Q

bisecting angle

A
  • beam is perp to an imaginary bisector of the angle formed by long axis of tooth and long axis of the film
  • pros: easy to place, shorter cone
  • disadv: hard to see film, film can bend, not dimensionally accurate
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27
Q

X ray is

A

invisible beam or photon of energy

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28
Q

Image receptor is

A

material on which the image is created. (COD/CMOSS?)

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29
Q

Intraoral detectors:

A

the thing that take the image (sensor or film)

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30
Q

Radiograph

A

is ANY kind of radiographic image (resultant image)

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31
Q

Visualization of films

A

done by air technique (of films to see them)

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32
Q

machine parts

A

has power supply
Control panel
Tube head (surrounded by oil)

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33
Q

Radiolucent

A

dark image

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34
Q

Lec 1, slide 15

A

parts of X-ray tube head

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35
Q

characteristic radiation

A

X-rays are produced by a certain photon energy called characteristic radiation. This is done by filtration (only takes short wavelength) by aluminum filter (must be 1.5 mm for 70 kVp, and 2.5 for over). This means less radiation to patient

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36
Q

Inherent filtration:

A

done by glass wall of tube, insulating oil, barrier surrounding the oil (done by natural materials)

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37
Q

Factors affecting image quality:

A

decrease kV, filter thickness, ambient light, collimator size, target, detector distance (NOT target object), focal spot size ALL increase radiographic contrast

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38
Q

radioactive decay

A

Radiation is released during radioactive decay (more high rate of decay is more radioactivity)

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39
Q

particulate radiation

A

alpha, beta and cathode rays

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40
Q

Deterministic effects

A

response is proportional to dose (but there are thresholds where no symptoms show). Effect the immediate area of radiation
- not caused by diagnostic

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41
Q

Stochastic effects

A

probability of change is dose dependent. Long term ie cancer
- caused by diagnostic
- no threshold so its all or nothing
- higher dose is more frequent effect

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42
Q

Direct radiation effect:

A

biological molecule is ionized by energy of photon (if done in s phase, it is propagated!)

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43
Q

Indirect radiation effect

A

ionization of water occurs, producing free radicals that create change (radiolysis 2/3 of effects: SEE SLIDES 23-25 of lec 2)

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44
Q

MOST radiosensitive

A

sperm, erythroblast, lymph organs, bone marrow, intestine, mucous membrane

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45
Q

Intermediate radiosensitivity

A

growing bone, salivary glands, kidney, liver

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46
Q

low radiosensitivity

A

optic lens, muscle and neurons

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47
Q

exposure

A

quantity of radiation incident on something expressed in Roentgen
- 1 c/Kg is 3870 R

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48
Q

dose absorbed

A

There is dose absorbed (what u give patient) in rad

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49
Q

dose equiv

A

biological damage produced by the radiation in rem

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50
Q

Sievert

A

1 Sv = 100 rems)

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51
Q

Kerma

A

kinetic energy released in matter

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52
Q

Effective dose

A

can’t be calculated easily! (Ht is sum of organ dose and Wt is weighting factors, eon is E = Ht x Wt)

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53
Q

Natural background radiation

A

3600 mSv per year. (10 per day)

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54
Q

Stochastic exposure limit

A

50 mSv. Deterministic is shown to cause cancer so 150 for the eye, and 500 for the skin (occupation)

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55
Q

Public exposure limit:

A

5 mSv but NOW it is 1 per year. 15 for eye and 50 for skin

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56
Q

How to reduce exposure (kvc, ma and distance limits)

A

nly take radiograph when needed, use fast image rreceptors, source to image receptor distance WILL not be less than 20 cm and SHOULD not be less than 40 cm, rectangular collimation, filtration with 1.5 mm aliuminum for 70 kVp, lead apron and thyroid collar (always visible in clinic), kVc should be 60-65 and mA should be 3.7-3.8, clinic should have shielding by walls

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57
Q

collimation for posterior pa and bitewing

A

horizontal

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58
Q

anterior pa and verticcal bitewing collimation

A

vertical

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59
Q

peri apical

A

apex of tooth and 2 mm beyond apex

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60
Q

bitewing

A

maxilla, mandible with crown, alveolar crest, 1/3 roots of each jaw, inter proximal contacts

61
Q

occlusal

A

not used too often. Get more area in mouth. Shows the top part

62
Q

unexposed receptor

A

image looks white and clear

63
Q

overexposed

A

image is dark or highly dense

64
Q

underexposed

A

image is light or low in density

65
Q

how to find where a lesion is

A

SLOB
- if you move the same direction as the shift of the PID, the object is LINGUAL
If it moves opposite, it is buccal

66
Q

Crooks tube

A

filament heats up, electrons release (thermionic emission)
Form electron cloud at cathode (- charge, 10v so lower power)
Voltage to anode creates a high potential difference (65-80 kvolts) and electrons bombard the anode (+)
Electrons interact with tungsten
Electrons get converted to x-ray photons as they decelerate
Angulation directs rays to filter and stream out (only short ones)

67
Q

coolidge tube

A
  • the “cool” new one
  • rotating anode to stop burnout
    Copper ring with oil chamber
    Two circuits with step up and step down transformer
    Evacuated glass
    **power is used to heat filament and create voltage potential difference
68
Q

cathode

A

filament made of tungsten

69
Q

Focusing cup

A
  • charge concave reflector (charge repels electrons) - cathode? Made of molybdenum
70
Q

Anode

A

tungsten in copper stem (dissipates heat from tungsten). Converts kinetic energy of electrons into x rays. Only 1% works!

71
Q

dose

A

effect is proprtional to dose

72
Q

dose rate

A

exposure at high dose rate kills more cells per unit dose since less time to repair lethal damage

73
Q

Oxygen enhancement ratio:

A

how much oxygen is needed to kill same amount of cells( usually less time). See the whole radical thing

74
Q

LET

A

linear energy transfer where low let is for X-rays and high let is for slower, more damaging stuff. Impart more energy

75
Q

Radiation caries:

A

type 1 is widespread superficial, type 2 is in cementum and dentin (most common - where teeth meet), type 3 is whole crown is dark

76
Q

Xerostomia

A

since salivary glands are in path of radiation

77
Q

Gamma ray therapy

A

they put a mouthguard inside

78
Q

Osteoradionecrosis

A

soft tissue dies, then infection spreads to bone
**wait 20 days after removing tooth to irradiate. Treated with hyperbaric oxygen therapy

79
Q

pano advantages

A

ADV: broad coverage, low radiation, easy, comfy, quick, good for patient education

80
Q

pano disadv

A

magnification is unequal so measurement not good, lower res, image errors ()ghost, real, double), needs good patient pos, must be read well,

81
Q

positioning for pano

A

the light must be at half of face, and one must be at the canine. Patient needs to bite on block, rest chin, Tongue must be on hard palate
- frankfort plane parallel to ground
- jaw in focal trough where image is most clear

82
Q

too far in front of bite block

A

image is wide

83
Q

bite block is too into the mouth

A

vertical stretch

84
Q

poor light alignment pano

A

magnification of one side of mouth

85
Q

xray face turned down

A

shows teeth smile going up

86
Q

xray face turned up

A

smile goes down

87
Q

double image

A

what you want, but shown twice. This is because there is a diamond shape in middle of mouth (tongue area) that is exposed twice, so centre structures (hard palate, cervical spine, hyoid bone and airway)

88
Q

ghost image

A

the image is always on the side that the structure is on (so left jaw bone will be on left side of paper or “right” side of image) this is for mandible, cervical spine ALWAYS superior to real image and blurry!
- hard palate and hyoid bone are REAL double images that also produce ghost images

89
Q

calcified lymph node

A

bottom of jaw wayyy under

90
Q

Tonsilloliths

A

when the corners have this radiopacity underneath

91
Q

Carotid artery calcification

A

(can see stent on R and L side)

92
Q

other pathology

A

Impacted third molars or teeth
- trauma fracture

93
Q

Pathoses

A

a bunch of white stuff and bone pattern has changed

94
Q

digital image and pixels

A

image is pixels, and each one has a unique location. More pixels is more image. Smaller size pixel, smaller details can be shown. Pixels form the matrix

95
Q

1 byte

A

8 bits

96
Q

Digital vs film:

A

digital requires less exposure, sensor is more sensitive, 50-90% less exposure time than film!
Film is familiar, less expensive initially but slowly adds up, needs chem processing, film needs to be stored so security issue too
Digital is 80% less rad, expensive, but quicker, used in patient education, no chemicals, easy to read, can email it, very secure

97
Q

analog to digital conversion (ADC)

A
  • conversion from voltage to digital numbers. each detector corresponds to a pixel in the image
98
Q

Cmos receptor:

A

rigid device with layers. The X-ray scintillator is most important since it creates visible light image to be captured by CMOS
- the chip is less expensive than CCD

99
Q

ccd vs cmos

A

CMOS each component generates its own charge that is added up, while CCD move it from pixel to pixel and convert to voltage at the end

100
Q

Direct digital (CMOS and CCD):adv/disadv

A
  • sensor is exposed and transmits to computer

ADV: good resolution, less exposure, fast since image comes out instant, lower cost, efficient
DISADV: set up is expensive, quality is less, sensor is thick, infection control since can’t clean sensor, legal issues because of security
- intra and extraoral

101
Q

Images are stored by

A

Digital Imaging and Communication in Medicine (DICOM) standards, for all imaging (can see them all over the world)

102
Q

Indirect digital

A

expose receptor than must process it to see image
Storage phosphor: reusable imaging plate, scanner, less rapid than digital. Coated with phosphor instead of sensor (PSP plate). The laser is red, then the photodiode that is read is blue light
- can also be taking a picture of a film

103
Q

Fluoresce

A

glows in light

104
Q

phospho

A

glows even after light

105
Q

standard film

A

blue light emitting

106
Q

rare earth film

A

green

107
Q

films must be

A

used in pairs with screen since double sided

108
Q

canthomeatal plane

A

ear to eye

109
Q

ala-tragus plane

A

Ear to nose

110
Q

Frankfort horizontal plane

A

Top ear to eye

111
Q

sagittal plane

A

Half face

112
Q

axial plane

A

Top and bottom half face

113
Q

posterior anterior ceph:

A

canthomeatal line at 10 degrees with film (nose on film)

114
Q

Occipitomental

A

(waters): chin on receptor (Canthomeatal line at 37 degrees to film). Good for sinus pathology!

115
Q

Reverse Townes

A

canthomeatal line at negative 30 to film (forehead to film, jaw open)

116
Q

Townes:

A

jaw open, back of head on receptor (the image right is patient right!)

117
Q

SMV or submentovertex:

A

chin up and back of head on receptor (canthomeatal plane is parallel to film

118
Q

Lateral ceph

A

side head on receptor. This is uneven mag of left and right sides

119
Q

Double space arthrogram

A

for jaw disk thinng??

120
Q

Ct scan has 3 views,

A

coronal (front), sagittal (patient right), axial (looking up from toes to nose)

121
Q

MRI

A

where bone is black and tissue is white

122
Q

why do a pano

A
  • evaluation of dentition and TMJ
  • examine lesions
    0 pos of impacted teeth
  • trauma
  • check up of permanent dentition
  • can’t do intraoral
123
Q

how much dose for a bitewing with PSP or F speed film

A

5 microSV, 0.6 day

124
Q

full mouth using PSP for F speed film

A

5 days 40 micro SV

125
Q

full mouth with CCD sensor

A

20 micro SV, 2.5 days

126
Q

pano dosage

A

20 micro Sv, 2.5 days

127
Q

where to stand when xray if you must

A

90 to 135 degrees of beam (by patient ears)

128
Q

object film distance

A
  • stay small so image is not magnified
129
Q

source film distance

A

long so less magnification

130
Q

CCD stands for

A

charged coupled device
- most common

131
Q

CMOS stands for

A

complementary metal oxide semiconductor

132
Q

PSP stands for

A

photostimulable phosphor plate

133
Q

make sure to also review kendra’s study guide for FMS pictures

A

GO DO IT

134
Q

1 gray = how many rad

A

100

135
Q

1 sV = how many rems

A

100

136
Q

diagnostic radiation

A
  • low dose and long term
137
Q

therapeutic radiation

A

high dose, short and long term

138
Q

radiolysis

A
  • usually forms water or h2 with free radical
  • OR can use water to generate h20+ (if photon takes e)
    or h20- if electron gets added to water
139
Q

h20+ and water make

A

h20+ and OH- (hydroxyl free radical)

140
Q

h- and oxygen make

A

h02- superoxide radical

141
Q

2 h20- make

A

hydrogen peroxide, h202

142
Q

worst and best film to use

A

worst is D film with round collimator
- best is F speed with rectangular collimator

143
Q

receptors used for paralleling technique

A
  • size 1 for anterior, vertial direction
  • size 2 for posterior, horizontal direction
144
Q

bitewings indications

A
  • proximal margins of restorations
  • perio disease
  • when teeth are in contact, history of smooth surface caries
145
Q

angulation erros

A

forshortening (teeth look short) from excessive vertical angulation
- elongation from insufficient vert angulation
- pan beam has negative vertical angulation so lingual objects are higher and buccal are lower

146
Q

multistep image capture process

A

each detector corresponds to a pixel
- x rays are absorbed in scintillator (captures the x ray and turns it to light)
- light is transmitted to CMOS that produce electrical charge within each pixel
- voltage is proportional to number of photons which is converted to a digitized value and processed by computer

147
Q

full mouth PSP or F speed with round collimator

A

400 mSv, 48 days

148
Q

full mouth with CCD sensor round collimator

A

100 mSv, 12 days

D1 BS1 + II/ FSI + II (12 decks)

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