Radiography Flashcards
1
Q
What term is used for the following? can produce characteristic x-rays from the movement of electrons in the energy levels around the nucleus
A
characteristic radiation
2
Q
What is the term used for the following;
- heated electron filament
- negative potential (- ive)
A
cathode
3
Q
What is the term used for the following;
- target, high Z material, Tungsten
- positive potential (+ ive)
A
anode
4
Q
From biggest to smallest, list the 7 types of electromagnetic radiation wavelengths
A
- radio waves
- microwaves
- infrared
- visible light
- UV
- X-rays
- gamma rays
5
Q
What is the term used which refers to the potential difference between the anode and the cathode; it refers also to approx the maximum energy of x rays produced?
A
kV
6
Q
What is the term used which refers to the beam current - the number of electrons flowing between anode and cathode?
A
mA
7
Q
What is the term used which refers to the longer the exposure, the more X-rays absorbed by the patient - more image quality but also more dose to the patient?
A
exposure time
8
Q
What is the function of the oil within an X-ray machine?
A
for cooling; power supply and X-ray tube
9
Q
What is the function of the metal housing within an X-ray machine?
A
lead lining for radiation protection to both operator and patient
10
Q
What is the function of the aluminium filter within an X-ray machine?
A
for ‘hardening’ the X-ray beam
11
Q
A?
A
filament and electron cloud
12
Q
B?
A
focal spot on tungsten target
13
Q
C?
A
glass envelope
14
Q
D?
A
vacuum
15
Q
E?
A
copper stem
16
Q
F?
A
electronic focusing cup
17
Q
G?
A
cathode
18
Q
H?
A
tube window
19
Q
I?
A
useful X-ray beam
20
Q
J?
A
anode
21
Q
What is the name of the theory relating to the further away the patient is the less dose and the closer they are, the more dose they will receive?
A
inverse square law
22
Q
A & F?
A
power supply
23
Q
B?
A
aluminium filter
24
Q
C?
A
X-ray beam
25
D?
aiming cylinder
26
E?
collimator
27
G?
oil
28
H?
yoke
29
I?
X-ray tube
30
What does the term Bremsstrahlung mean?
braking radiation
31
What is the term used for the following?
| - the process by which a neutral atom acquires a positive (or negative) charge
ionisation
32
What is the term used for the following?
- the process by which the energy given to an orbital electron is insufficient to eject it from an atom, but simply raise it to a higher energy level
excitation
33
What is the term used for the following?
| - this is when a photon (X-ray) gives up all its energy to the material by transferring it to an electron(s)
absorption
34
What is the term used for the following?
- this is when the photon (X-ray) collides with an electron or atom and changes direction, this can be with or without a change in energy of the photon (X-ray)
scatter
35
What are the 3 main factors that affect radiation dose?
time
distance
shielding
36
What are the 2 current legislations for radiography?
- ionising radiation regulations 2017
| - ionising radiation (medical exposure) regulations 2017
37
What is the name of the person responsible for the following?
- usually a dentist or PCD
- ensures compliance with IRR2017 and particularly supervises arrangements set out in the local rules
radiation protection supervisor (RPS)
38
What is the name of the person responsible for the following?
- usually a physicist
- advises on compliance with IRR2017
radiation protection advisor (RPA)
39
What is the width of the controlled area?
1.5 metres around the patient in any direction
40
What legislation are the following guidelines of?
- duties of referrer, practitioner, operator and employer
- appoint a medical physics expert
- justification of exposures
- optimisation
- establish diagnostic reference levels
- record an evaluation of every radiograph
ionising radiation (medical exposure) regulations 2017 (IR(ME)R 2017)
41
Who is responsible for the following?
- a registered healthcare professional entitled to refer a patient to a practitioner for exposure
- responsible for providing justification
referrer
42
Who is responsible for the following?
- suitably trained PCD or dentist
- must ensure justification is appropriate and that benefit outweighs harm
practitioner
43
Who is responsible for the following?
- suitably trained PCD or dentist
- responsible for exposure to be carried out in accordance with appropriate prescription/justification
operator
44
Who is responsible for the following?
- has legal responsibility for x-ray installation
- provides radiological protection framework and ensures staff and procedures conform with regulations
employer
45
What is this the definition of?
| - the dose which gives an image of sufficient diagnostic quality whilst minimising the radiation to the patient
optimum dose
46
Which radiation document must contain the following?
- name of RPS
- identification and description of controlled area
- summary of working instructions
- significant findings of risk assessment
- contingency arrangements
- dose investigation level
- name of 'legal person' (usually employer)
- name and contact details of RPA
- arrangements for personal dosimetry
- arrangements for pregnant staff
radiation protection file
47
What are the 3 guidance points for radiation for pregnant employees?
- must inform legal person once pregnancy is confirmed
- they must not receive more than 1000 sieverts to abdomen during declared term of pregnancy
- must consult RPA if taking more than 150 radiographs a week
48
What are 3 reasons why the number of radiographs being taken has increased?
- increase in prevention
- more caries prevalence
- paper trail of treatment decisions
49
What is the name of the guidelines listed;
- no practice shall be adopted unless its introduction produces a net positive benefit
- all exposures to be kept As Low As Reasonably Practicable, taking social and economic factors into account
- the equivalent dose to individuals shall not exceed the limits recommended by the commission
ICRP general principles
50
What are 3 benefits of radiographs?
- early diagnosis
- prevention
- informed treatment
51
What are 3 risks of radiographs?
- genetic mutations
- cancer
- premature ageing
52
What are 5 tissues that are more susceptible to tissue damage due to radiation exposure?
- bone marrow
- breast
- colon
- lung
- stomach
53
How often should bitewings be taken for a high caries risk?
every 6 months
54
How often should bitewings be taken for a medium caries risk?
every 12 months
55
How often should bitewings be taken for a low caries risk?
every 2 years
56
How often should bitewings be taken for a low caries risk and primary dentition?
12-18 months
57
Which type of radiograph should be taken for the following?
| - heavily restored dentition/history of multi quadrant endodontic treatment
OPG or periapicals
58
Which type of radiograph should be taken for the following?
| - grossly neglected dentition with multiple grossly carious teeth and/or roots in many quadrants
OPG
59
Which type of radiograph should be taken for the following?
| - < 5mm pocketing
bitewings (horizontal)
60
Which type of radiograph should be taken for the following?
| - > 5mm and < 8mm pocketing
bitewings (vertical) or periapicals
61
Which type of radiograph should be taken for the following?
| - > 8mm pocketing (localised)
periapicals
62
Which type of radiography should be taken for the following?
| - > 8mm generalised
periapicals or panoramic (if not embarking on treatment)
63
What are 4 ways optimisation be achieved?
''optimisation is the process of balancing the diagnostic quality of a radiograph against the dose received by the patient''
- equipment optimisation
- good technique
- lead protection
- quality assurance
64
What is the kV for modern dental x-ray machines?
70kV
65
What does increasing the kV of the x-ray machine do?
- increases the potential difference between the cathode and the anode
66
Older machines were too under powered to tolerate a long cone, modern machines use a relatively long cone of what length? (focus to skin distance)
20cm
67
Which type of x-ray points at the thyroid and a lead thyroid collar held high would need to be used for protection?
upper standard occlusal
68
Which type of wet film is being described?
- image formed by action of x-ray photons
- renders fine detail (greater resolution)
- higher radiation dose
- single use
- small
- intra oral use
direct
69
Which type of wet film is being described?
- image formed by light photons emitted by screens
- less detail (lower resolution)
- lower radiation dose
- screens need to be re-used (maintenance, infection control)
- bulky
- extra oral use
indirect (cassette)
70
Which size is the following film/sensor measurements?
| - 40.5mm x 30.5mm
size 2
71
Which size is the following film/sensor measurements?
| - 40mm x 24mm
size 1
72
Which size is the following film/sensor measurements?
| - 35mm x 22mm
size 0
73
Which size is the following film/sensor measurements?
| - 76mm x 57mm
size 4
74
What are the 4 contents of a film packet?
- film
- black card - is on both sides and has a flap to reduce light leaks. protects film from light, fingerprints, saliva
- lead foil - reduces residual radiation, reduces secondary scattered radiation
- packet - stops saliva getting in
75
What is film emulsion made up of?
silver halide
when x-ray photon hits emulsion an electron from an AgBr ion gets enough energy to escape, thus, the exposed film compromises a pattern of more or less sensitised areas of silver halide. when film is developed, the more sensitised silver halide crystals are converted to black silver - areas which have received less radiation will appear paler
76
What are the 5 stages of developing wet film?
1. development
2. intermediate washing
3. fixing
4. final washing
5. drying
77
What are 3 factors that affect the quality of a radiograph?
- quality of technique
- image receptors used
- exposure or processing faults
78
What are 3 reasons why image is too dark?
- overexposed
- overdeveloped
- fogging (faulty dark room etc.)
79
What are 3 images why image may be too pale?
- under exposed (faulty equipment etc.)
- under developed
- film back to front (pattern from lead foil will be seen)
80
When would brown film occur?
inadequate final wash
81
When would blurred film occur?
the receptor moved
or
the patient moved
82
What are the 2 types of digital radiography?
direct or indirect
83
Which type of digital radiography is being described?
- involved a phosphor plate (PSP)
- needs to be scanned - not instantaneous
- sensors deterioriate over time
- all different sizes available, but then need to have appropriate scanner
indirect
84
What are 3 potential issues with digital radiography?
- exposure problems
- image manipulation problems
- wear and tear
85
What are 3 aims of quality assurance programmes?
- reduce repeats
- reduce dose
- reduce costs
86
What are 6 things that need to be monitored as part of the quality assurance?
1. x ray equipment
* initial testing, critical exam and report by equipment installer, written log and local rues, daily and weekly checks
2. procedures
* local rules (IRR99), procedures log
3. darkroom/processing
* all checks, instructions, logs, safelights, fogging checks, film speed, expiry date and storage conditions, intensifying screens require regular cleaning
4. digital processing
* check plates/sensors for scratches, fogging etc, check monitors
5. image quality
* investigate any significant deterioration in quality and take corrective action
6. staff training
* CPD
87
What are the quality targets for digital systems?
acceptable - no less than 95%
| not acceptable - no more than 5%
88
What are the quality targets for wet films?
acceptable - no less than 90%
| not acceptable - no more than 10%
89
OPGs
| The arch shaped area of focus is known as the...?
focal trough
90
What are 4 things to do to prepare a patient for an OPG?
1. explain about the machine movement to the patient, especially children
2. ask patient to remove glasses, necklaces, earrings and dentures
3. ensure that the patient places their tongue against the palate during the exposure
4. position the patient upright not slumped
91
OPGs
The teeth/jaws must be positioned so that they lie within the U shaped focal trough, structures positioned inside this trough will be distorted, out of focus and ...?
enlarged
92
OPGs
The teeth/jaws must be positioned so that they lie within the U shaped focal trough, structures positioned outside this trough will be distorted, out of focus and ...?
diminished
93
What would the following indicate when taking an OPG?
- anterior teeth will be blurred and narrow in appearance
- the premolars will be overlapped
- the cervical spine may be superimposed on the rami
- rami are 'curled in' and there's a lot of spine visible on each side
the canine light is further back than the canine/nasolabial fold indicating that the patient is too far forward
''too far in, teeth are thin''
94
What would the following indicate when taking an OPG?
- the anterior teeth will be blurred and wide in appearance
- the cervical spine may be superimposed on the central teeth
- rami are curled out and condyles are splayed - may even be off the view
the canine light is further forward than the canine/nasolabial fold
''too far out, teeth are stout''
95
What would the following indicate when taking an OPG?
- the roots of the upper incisors being blurred
- condyles may be lost off the sides
- hard palate may be projected over upper roots
- frowny face
- base of skull superimposed
the line passes above the tragus of the ear or below the alar process of the nose
96
What would the following indicate when taking an OPG?
- the roots of the lower incisors will be blurred
- hyoid may be projected over the mandible
- smiley face
the line passes below the tragus of the ear or above the alar process of the nose
97
What would the following indicate when taking an OPG?
- the teeth on one side will be magnified and have overlapping contacts compared to the other side
- the width of the rami will also be different
the patient is biting on the block, but the head isn't lined up straight
so one side will be inside the focal trough whilst the other side falls outside of it
98
What would the following indicate when taking an OPG?
| - cervical spine being superimposed over the midline of the image
patient may stoop to the bite guard or be slumped
99
An OPG radiation dose is the equivalent to how many intra orals?
4-8
100
What should a bitewing show?
distal of 3s to 7s
| coronal third of root
101
What will a bitewing x ray not show?
bone loss more than 5mm
| anything apical
102
What should vertical bitewings show?
same as normal bitewings but with 2/3 of the roots
| show up to 8mm bone loss
103
What should PA x-rays show?
complete crown and root of selected tooth and adjacent tooth
104
What are 4 PA indications?
- trauma
- perio assessment
- show periapical radiolucency
- assess root morphology for endo
105
What are 3 advantages of the paralleling technique?
- correct centering with minimal distortion
- image can be reproduced
- patient dose reduced
106
What are 3 disadvantages of the paralleling technique?
- instruments costly and need sterilisation
- patients may find instruments difficult to tolerate
- technique not always possible
107
What are 2 advantages of the bisecting angle technique?
- no additional equipment required
| - relatively easy for patients to tolerate
108
What are 2 disadvantages of the bisecting angle technique?
- not possible to reproduce same views
| - crowns of teeth may looks distorted
109
What is an advantage of an occlusal X-ray?
useful for providing a second view in alternative plane so can locate teeth
110
What are the 3 types of maxillary occlusal x rays?
1. upper true occlusal
2. upper standard occlusal
3. upper oblique occlusal
111
What are the 3 types of mandibular occlusal X-rays?
- lower 45 degree occlusal (anterior)
- lower 90 degree occlusal
- lower oblique occlusal
112
What are 2 reasons why occlusal radiographs aren't frequently used?
- sensor/scanning issues
| - better visualisation available with CBCT
113
How does increasing the voltage of the x ray machine affect the beam?
higher energy photons are produced
114
A?
leaded glass tube
115
B?
metal housing
116
C?
cathode
117
D?
cathode
118
E?
filament
119
F?
electrons
120
G?
lead diaphragm
121
H?
aluminium filter
122
I?
tube aiming device
123
What does the concave surface of an X-ray machine do?
focuses beam
124
What does the copper block of an X-ray machine do?
dissipates heat
125
What does the unleaded glass window of an X-ray machine do?
lets photons out
126
What does the aluminium filter of an X-ray machine do?
attenuate (reduce the force/effect) the low-energy (soft) x-ray photons from the spectrum
127
What does the lead tube (collimator) of an X-ray machine do?
constrains beam
128
What does the oil of an X-ray machine do?
dissipates heat
129
What does the metal housing of an X-ray machine do?
absorbs all radiation that is not directed towards the patient
130
What are 3 factors that affect the quality of a radiograph?
- how image was taken
- image receptors used
- exposure or processing faults
131
What are 3 factors that will make an image appear too dark?
- over exposed
- overdeveloped
- fogging
132
What are 3 factors that will make an image appear too pale?
- under exposed
- underdeveloped
- film back to front
133
What is a factor that will make an image appear brown?
inadequate final wash
134
What is a factor that will make an image appear blurred?
patient or equipment moved
135
What are 7 factors that can produce marks on the film?
- bending by operator
- finger marks
- static discharge
- chemical
- roller marks
- dirty screens
- patient biting too hard on packet
136
When an X-ray beam hits a person, what 4 things can happen?
- the photon misses everything and passes through the tissue unchanged
- the photon is deflected with no loss of energy
- the photon is deflected after some loss of energy
- the photon is completely absorbed
137
When the beam hits a person, the photon can be deflected after some loss of energy, this causes some tissue damage, but gives us our image. Higher energy photons are more likely to scatter forward - giving poorer contrast at higher voltages. This is known as the?
Compton effect
138
When the beam hits a person, the photon can be completely absorbed, this causes more tissue damage, but also contributes to good contrast on the image. This is known as the?
photoelectric effect
139
When interacting with tissues, photons may be?
- absorbed (photoelectric effect)
- attenuated (Compton effect; part absorbed, part scattered)
- transmitted (pass through unchanged)
- scattered (deflected)
140
What are 5 points of how to take a bite wing?
- place film centrally in holder
- make sure it is seated down properly
- sensor should be parallel to the arch
- bite platform should be placed over the 6s (unless you really need it to show a different area)
- ring should be slid up to nearly touching patients face
141
What are 4 positioning requirements of taking an X-ray?
- tooth and film packet in contact or as close as possible
- tooth and film packet parallel to each other (use full vault of palate to ensure parallel to long axis of tooth)
- incident ray at perpendicular to tooth and film
- film long axis vertical for incisors and horizontally for premolars and molars
142
Which biological effects is the following?
- probability is dependent upon the dose of radiation received
- damage may occur with ANY level if radiation dose; no threshold dose
- cancer induction, genetic mutations, acute/long term effects
stochastic effects
143
Which biological effects is the following?
- severity is dependent upon the dose of radiation received
- in most cases, there is a threshold before the effect is apparent eg. erythema (skin reddening)
- acute/long term effects
deterministic effects
144
What 9 things should be included in the local rules?
- name of RPS
- ID and description of controlled areas
- summary of key work instructions for equipment and names of staff appropriately qualified/trained
- contingency arrangements re. equipment fault or accidental exposure
- name of legal person with legal responsibility of compliance
- key findings of risk assessment
- dose investigation level
- name of RPA
- arrangements for personal dosimetry and pregnant staff
145
How is dose defined?
energy absorbed per unit mass
146
What are the 10 IRR essential requirements?
- authorisation
- notification
- prior risk assessment
- restriction of exposure
- maintenance
- contingency plans
- appoint a RPA
- appropriate training
- designate controlled area
- appoint a RPS
