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EXAM Flashcards

1
Q

is it true or false that xray photons have electrical charge

A

false

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2
Q

what is the correct ring holder to use when taking a paralleling periapical radiograph of tooth 11

A

blue

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3
Q

is it true or false that the xray beam is aimed upwards at approx 8 degrees

A

true

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4
Q

when positioning a patient for a panoramic radiograph which anatomical reference should be horizontal?

A

Frankfort plane

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5
Q

it should be standard practice for the patient to wear a lead apron for which intramural dental radiograph?

A

none of them

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6
Q

list 2 specific anatomical features that can hinder the positioning of the image receptor holder when attempting to take a paralleling periapical radiograph of a first molar tooth in an adult?

A

strong tongue
lack of adjacent teeth
shallow or high hard palate
lack of opposing molar teeth
tight cheeks unable to hold receptor

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7
Q

intra oral dental xray units, with an operating potential of 60-70kv, must include a spacer cone to ensure a minimum “focus to skin distance”. state the minimum distance and explain why the UK guidance depends it?

A

focus to skin distance 200mm
ensures xray beam is parallel as more parallel beam means you have less distortion of the anatomy, maintains high quality and can be replicated

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8
Q

what does the Compton effect cause?

A

scatter which results in a lower quality image very little diagnostic information.

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9
Q

which end of the spectrum has photons which are not useful for image formation?
what material is used to filler these out of the xray beam?

A

low end of spectrum

aluminium

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10
Q

who can be the referee for radiographs?

A

qualified dental professionals
operators
practitioners

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11
Q

what are ghost shadow son a radiograph?

A

earrings
facial peircings
salivary stones
tonsil stones
dental restorations
dentures

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12
Q

what radiographs would you use for a patient with a BPE of 4 in all sextants?

A

Full mouth of periapicals

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13
Q

What is the numbers of the radiograph receptors and what colours are they and what type of radiographs would be take with these and what colour of xray holder would be used?

A

0- Anterior periapical- yellow receptor - blue Xray holder

2- bitewing, posterior periapical- green receptor - red xray holder.

4- occlusal - blue receptor

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14
Q

what are advantages and disadvantages of intraoral radiographs?

A

advantages :
low exposure, detailed image, quick and easy

dis adv:
uncomfortable for the patient, might need to retake, patient positioning

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15
Q

what would you you see on a periapical radiograph?
what are the advantages
and disadvantages?

A

the entire tooth crown root and apex of the tooth
periodontal bone loss
apex of the tooth for any infection
caries
endodontic treatment

dis adv:
just 1 or 2 teeth at a time so limited view
technique sensitive
overlapping

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16
Q

what would you see on a bitewing radiograph? what are the advantages and disadvantages?

A

molars and pre molars of upper and lower arch crown and root of the tooth
periodontal bone loss
interdental caries
advantages:
detect inter dental caries, bone loss, minimal radiation exposure, fast exposure

dis adv:
may be uncomfortable for the patient
if patient has over lapping teeth may need to take 2
doesn’t show other anatomy
the quality of the image may nit be great

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17
Q

what does an OPT show you and what are advantages and disadvantages?

A

opt shows you the entire dentition, and other surrounding anatomy such as TMJ maxillary sinuses and wisdom teeth.

adv
good for patients with gag reflex
can see full dentition
Other anatomy

dis adv
higher radiation exposure 5x more
Longer exposure time

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18
Q

What is the ideal projection geometry?

A

Non divergent xray beam
Tooth immediately next to receptor
Xray beam exactly perpendicular to both the tooth and receptor

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19
Q

How you achieve the best possible projection geometry?

A

Keep patient still
Maintain focus to skin distance
Ensure the receptor is as close to the tooth as possible

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20
Q

The uk guidance recommends at least how much distance for focus to skin distance? For intra oral X-ray units

And what is this distance maintained by using ?

A

200mm

Spacer cone

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21
Q

What is the curve of spee?

A

The occlusal plane rises as you move distally

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22
Q

What is the curve of Wilson?

A

Teeth don’t sit on the jaws completely perfectly they tilt vertically maxillary teeth tilt buccal labial mandibular molars tilt lingully

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23
Q

What is the bisecting angle technique?

A

When the subject and receptor are tilted at equal but opposite angles the two effects counteract one another

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24
Q

When is the bisecting angle used and who would we use it on?

A

Used when unable to position the receptor parallel to the tooth

Edentulous patient
Bad gag reflex
Child can’t tolerate receptor in mouth
Shallow palate

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25
What is the match band effect?
Optical illusion created by the retina can make areas look brighter and areas look darker
26
How would you assess image quality?
Over exposure or underexposed If the receptor is the wrong way around
27
What is caries seen as on a radiography and where can it be seen?
Radiolucent Pits and fissures, smooth surfaces, interdental, root surface, secondary caries under restorations
28
What are the requirements of a controlled area for standard dental radiography?
Within 1.5m of the xray tube head and patient
29
Who is in charge of radiographs and who governs radiography?
FGDP
30
Why do we need safety regulations put in place?
To keep patients and staff safe There is risk associated with X-rays Exposure levels were higher in the past
31
What are local rules?
Rules put in place to ensure there is safe working in the xray area
32
What is a radiation protection adviser ?What matters should the employer consult a radiation protection advisor on?
A Radiation protection adviser is a specialist who advises employers to comply with IRR17 regulations. Investigations Radiation risk assessments Regular equipment checks
33
The basic principles of the ICRP system are that all radiation exposures should be ?
Justified Optimised Limited
34
Who does IIR17 regulate And what are some examples of what they regulate?
Radiation safety to members of the public and staff Controlled areas Local rules Risk assessments
35
Who does IRMER17 govern?
medical exposures of patients and others Exposures must be justified And staff must be trained
36
What is the xray beam made up of?
Millions of xray photons directed in the same direction
37
what are radiographs?
Images created by X-rays which have been through an object then interacted with receptor
38
what is the xray production?
Electrons go towards atoms at a very high speed as they collide kinetic entry from the electrons is converted to heat and electromagnetic radiation
39
Xray units have generations which modify the alternating current so that it mimics a constant direct current what is this process known as?
Rectification
40
What are the electricity fundamentals?
Current - flow of electric charge Voltage - different electrical potential between 2 points in electric field Transformers - alter voltage from one circuit to another
41
what is electromagnetic radiation?
X-rays are a form of electromagnetic radiation The flow of energy represented as a sine wave
42
What are properties of electromagnetic radiation?
No mass No charge Can travel in vcuum Travels at speed of light
43
EM radiation involves the movement of energy as “packets of energy” known as what? Wat are they usually measured in ?
Photons Electron volts
44
What are properties of X-rays
Form of electromagnetic radiation No mass No charge Travel in vaccum Man made
45
What is an electron shell ?
When electrons spin around the nucleus in discrete shells
46
What is the dental xray unit made up of?
Tube head Collimator Spacer cone Positioning arm Control panel Circuitry
47
Xray units have generators which modify the alternating current so that it mimics constant direct current what is this process known as?
Rectification
48
The dental Xray unit requires what type of current? And what type of voltages?
Requires a direct current Requires 2 voltages One as high as 10s of thousands One as low as 10 volts
49
What way to photons travel?
Photons effectively travel in straight lines but diverge from the xray source Not parallel
50
What are xray photons aimed at?
A subject
51
What removes the lower energy (non diagnostic X-rays) from the beam?
Aluminium absorbs the photons
52
What is the precise area on target where electrons collide and X-rays are produced?
Focal spot
53
What is the penumbra effect?
Blurring of radiograph image due to the focal spot not being a single point
54
What are the main components of a tube head ?
Xray tube Metal shielding Aluminium filtration Oil Spacer cone
55
How much Focus to skin distance should the tubehead be from the patient How is this effective?
200mm Reduces magnification of image
56
How much can rectangular collimation potentially reduce surface area irradiated and reduce effective dose to the patient by approximately?
50%
57
How would you assess image quality ?
Over exposure Under exposure Elongation Cone cutting Receptor placed back to front
58
Who is IRMER17 Enfored by?
Health Improvement Scotland
59
IRMER17 defines particular roles during medical exposures called duty holders what are these ?
Referrer Practitioner Operator Employer
60
What is distortion and what are common causes of it?
a false size or shape of structures being imaged Incorrect distances Angulation of xray beam Patient movement
61
What are double shadows and ghost shadows on OPT?
Double shadows are structures which are captured twice on the image due to the way in which the radiograph was taken Such as 2 soft palates Ghost shadows are faint blurry parts of an image that shouldn’t be there can happen due to patient movement Double exposure by accident Jewelery such as lip pearcing, earrings
62
When would you take an OPT?
you wouldn’t routinely take these Only for generalised gross caries Periodontal bone assessment Assessment of 3rd molars Assessment of anatomy such as TMJ & maxillary sinus
63
When would you take an OPT?
you wouldn’t routinely take these Only for generalised gross caries Periodontal bone assessment Assessment of 3rd molars Assessment of anatomy such as TMJ & maxillary sinus
64
Why are radiographs useful?
Can show anatomy Help diagnosis Help monitor Help treatment plan
65
What is rectification?
Xray units have generators which modify the alternating current so that it mimics a constant direct current
66
How many volts is the electrical supply to xray unit ?
220-240 volts
67
What results in the xray beam intensity ?
The quality of photon energy passing through a cross section area of the beam
68
What causes divergence of the xray beam?
When the dose decreases with the distance from xray source
69
What does electron volts measure?
Kenetic energy gained by electrons
70
How are the xray photons emitted from the focal spot?
lead shielding Attenuated by aluminium filtration Exit tubehead to form xray beam
71
What ways does xray photons interact with matter ?
Transmission Absorption Scatter
72
What does attenuation lead to?
The radiographic image
73
What are specific attenuation interactions?
Photoelectric effect is when an xray photon and gets completely absorbed leads to a high contrast image Compton effect is when the xray photon hits an outer body electron and leads to less absorption and scatter creating a bur or fog in the image
74
The majority of scatter from an xray beam produced by an xray tube operating at what KV and what scatter ?
70kv Forward scatter
75
The controlled area should extend at least how far from the Xray tube and patient?
1.5m
76
What digital receptor checks would you carry out?
Check receptor Image Image quality
77
What does the step wedge test check ?
To check image quality and contrast
78
What teeth would you aim to see on a bitewing radiograph ?
Distal of the canine and medial aspect of the last tooth
79
What are potential faults you may see on a radiograph
Receptor damage Bad contrast Too dark too pale
80
What are the receptor sizes and colours and what radiograph are they for ?
Size 0 anterior perapical yellow receptor Size 2 Bitewing green receptor Size 4 occlusal blue receptor
81
what are occlusal images good for compared to other images?
larger image different angle alternative to periapical if patient cannot tolerate
82
what is cerviacal burn out?
triangular shaped radiolucency at neck of the tooth just below the CEJ along the radiograph
83
what is the Y of Ennis?
the start of the nasal cavity and border of the maxillary sinus
84
what are diagnostic radiation levels?
guideline dose levels for radiographs to ensure the exposure is kept AS LOW AS RESONABLY PRACTABLE while achieving a good quality image
85
what are the main components o a panoramic machine?
tubehead receptor control panel positioning apparatus
86
advantages and disadvantages of intra oral radiographs?
advantages high diagnostic detail low exposure to radiation its quick cheap disadvantages are discomfort for the patient may need to retake image technique sensitive limited field of view
87
what is the procedure of an opt radiograph?
prepare the patient remove any dentures, anything inside the mouth any chains or earrings position the patient make sure chin rests on the chin rest the bite block is used to stabilise the head head is aligned to the positioning lights for the Frankfort plane advise patient to keep lips closed tongue to the roof of the mouth and stay still

Radiography (12 decks)

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