6. Diagnostics Flashcards
What is meant by the ‘quality’ of an X-ray beam
Penetrating power of the beam
What is meant by the ‘intensity’ of an X-ray beam
Amount of radiation in the beam
What of quality and/or intensity does changing kV affect
Quality and intensity
What of quality and/or intensity does changing mA affect
Intensity only
List the radiographic process
Positioning
Centring
Collimation
Exposure factors
Labelling
Artefacts
Give 3 ways scattered radiation and be reduced
Good collimation
Low kV
Using radiographic grid if required
How is an image formed by ultrasound scanner
Reflection of the sounds at tissue boundaries
What is the goal of radiography
Gain a diagnostic image
How do we get around the fact that radiography is taking a 2D image of a 3D structure
We take orthogonal views (90 degrees to each other)
What does good positioning of the animal achieve for radiography
Accurately represents the anatomy
Minimises distortion and magnification
How is good positioning achieved in radiography
Having the area of interest as close to the plate as possible
The area of interest must be central, parallel to the plate and perpendicular to the beam
Why do we collimate a radiographic image
Radiation safety
Reduces scatter and improves image
How to have correct exposure for a radiograph
mAs and kV correct
use an exposure chart
How to label a radiographic image
L/R markers used in the image
Digitally label with the date, patient name etc
Give examples of difficulties when radiographing large animals
Conscious standing animal
Need a machine operator, plate holder and animal handler
Often done at client premises
Use of horizontal beam requires careful attention to safety, planning and good technique
Give a risk of using horizontal radiography beam
Higher exposures as beam has to travel further therefore more scatter
What is the inverse square law when referring to radiography
Strength of X-ray beam is inversely proportional to square of distance from source
Name the oblique views used in large animal radiography
Dorsolateral palmaromedial oblique
Dorsomedial palmerolateral oblique
How do you make large animal radiography as safe as possible
Use of protective clothing
Plate holder so you aren’t in primary beam
Controlled area with minimal people present
Why are X-rays dangerous
They are ionising radiation
Can affect your atoms and DNA - mutations
Penetrating so can pass through objects
4 ways we achieve As low as reasonably practicable (ALARP) - as the radiographer
Working practices
Amount of radiation used
Distance
Shielding
Give examples of working practices used to achieve ALARP
Using sedation or GA to minimise handling of the patient
Having a controlled area with signage and warning lights to prevent entry when active
Local rules set by RPA and monitored by RPS
Give examples of how amounts of radiation is used to achieve ALARP
Collimation centring, positioning, labelling and reducing artefacts so repeat exposures are not required
Using best settings for mAs and kV to give good quality image but the minimum radiation
Give examples of how distances are used to achieve ALARP
Inverse square law
Give examples of shielding used to achieve ALARP
Lead
Gowns gloves, thyroid protectors
Portable shields
Lead lines walls and doors of the xray room
Why is remote anaesthesia required during imaging
MRI and CT require periods of time where the animal is left unsupervised
Need to ensure adequate depth of anaesthesia and the ability to monitor from afar
Give examples of appropriate restraint for animals during an ultrasound
Large animals - standing in stocks/stalls
Small animals can lie in recumbency
Consider need for analgesia, sedation or anaesthesia
How can you prep the animal to make sure the sound can penetrate into the tissue for an ultrasound
Clip hair
Remove dirt and skin oil using alcohol
Apply ultrasound gel
ensure contact between transducer and skin
How to move superficial structures further away from the transducer for an ultrasound
Gel standoff’s
What is the correct frequency to select for different structures - eye vs pregnancy diagnosis
examples
Eye - 10 MHz, high resolution, low penetration
pregnancy diagnosis - 3MHz low resolution but good penetration
What 3 things should you comment on when doing an imaging report
What have you got
What can you see
What does it mean
If taking hip radiographs for BVA hip dysplasia scoring, how should the animal be positioned
Dorsal recumbency, legs pulled out straight, parallel to each other
What 2 views do you need for hip dysplasia scoring
Ventrodorsal view and L or R lateral (affected side close to the plate)
What are the 2 standard views for elbow scoring radiographs
Craniocaudal
Mediolateral
Both in neutral positions
what 2 standard views for radiography of a dogs stifle
Lateral view - typically mediolateral
Caudocranial - dog in ventral recumbency with limb extended caudally
Name the 4 common diseases associated with a dogs stifle
Joint effusion
Cranial cruciate ligament rupture
Chronic stifle arthritis
Oesteochondrosis
What 2 views are commonly taken to look at a dogs shoulder
Lateral - medio lateral mostly
Caudocranial - dorsal recumbancy
Name the 3 common diseases associated with a dogs shoulder
Medial shoulder luxation
Osteochondrosis
Chronic shoulder arthrosis
What are the 2 problems with CT and radiography
radiation dosing
poor soft tissue resolution
What are the 5 issues with MRI
Susceptible to movement
Poor bone detail
Metallic artefacts
Implanted medical devices may be destroyed
Not real time - takes 45min to get results
What are the 2 types of +ve contrast media used in CT and radiography
Iodine
Barium
What -ve contrast media is used in CT and radiography
Air
What +ve contrast media is used in MRI scans
Gadolinium
What -ve contrast media is used in MRI scans
air
Give the main heath and safety issues with MRI and CT
CT - ionising radiation
MRI - strong magnetic fields
what does endoscopy allow you to do
Look inside a body cavity or organ
Can obtain diagnostic samples e.g. fluid sampling, lavage, biopsies
Can enable a therapeutic procedure
Give 3 examples of therapeutic procedures which can be done with an endoscope
Removal of foreign body
Management and oesophageal stricture
Placement of a gastric feeding tube
what are the two types of endoscopes
Rigid
Flexible
Give 3 broad examples of when we may used endoscopy
GI signs
Respiratory signs
Urinary signs
Give 5 examples of when we may use endoscopy in horses
Suspected upper airway/laryngeal obstruction
Investigation of abnormal respiratory noise
Suspected lung disease
Gastric ulceration
Urinary tract disease
What patient prep may be required for endoscopy
Empty GIT or enema if GI endoscopy
What 3 things can go wrong in endoscopy and how to avoid
Aspiration => cuffed endotracheal tube
Damage to scope => mouth gag
GI perforation => never force the scope, always use plenty of lubrication
what are the 2 types of flexible endoscopes
Fibreoptic endoscopes
Video endoscopes
Name 3 limitations of flexible endoscopy
Scope may not be long enough
Small diameter scopes only allow small biopsy instruments
Biopsy channel needs to be approx. 2.8mm to be useful
What are the positives of rigid endoscopes
Cheaper
Less prone to damage
Better image than flexible
allows larger instruments to be used
What are the cons of rigid endoscopes
No flexibility => restricted access to some anatomical sites
Need additional equipment
Risk of damage and mucosal bleeding
Unable to manoeuvre around bends
Cannot inflate areas with air
Give 4 examples of when you use rigid endoscopy
Rhinoscopy
Athroscopy
Cystoscopy in bitches
Laparoscopy
What 4 things are you looking for in pleural ultrasounds
Glide sign
Comet tails or rockets
solid sections of lung
Fluid
What will you see on pleural ultrasound if an animal has pneumothorax
Will see thicker parietal pleura
Line won’t glide
