T2: Radiography Flashcards
What is a radiograph?
photographic image caused by x-rays on sensitive film
What is radiology?
interpretation of radiographs (x-rays)
List some of the radiography licensing requirements
- Compliance w/ code of practice for radiation protection in vet. medicine (2009)
- Info on ventilation, drainage, surfaces
- Assessment of minimum amount of shielding req.
- Name of the personal radiation monitoring device
List the PPE required for radiography
- Lead apron, gloves, sleeves
- mobile shields
- personal radiation monitors
- thyroid shields
- goggles
What is ALARA and what are the 3 major principles it entails?
As Low As Reasonably Achievable
- TIME
- DISTANCE
- SHIELDING
Describe the process of assessing x-ray machine position
-check tube housing parallel to table w/ spirit level -check collimator & tube head are not crooked/
rotated
- Use protractor to measure correct angle of machine if head has angulation indicator
- Machine must be stabled & have means to prevent movement
- Never physically hold x-ray tube housing
What is focal film distance and how much should this distance be?
Distance b/w x-ray tube & x-ray film. 75 - 100cm
Does a digital radiograph require a darkroom?
No.
When should an x-ray grid be used?
for thoraxes deeper than 14cm and other body parts thicker than 10cm
What equipment is required for producing radiographs?
- X-ray machine, cassettes, intensifying screens, film & grids
- Table
- Technique charts & correction factors
- Measures
- PPE
- Positioning equip. & labels
- Contrast media
- ID equip.
- Dark room, viewing box & hot light
- Film processing equip.
- Records & storage/filing
Veterinarians are legally obliged to permanently mark radiograph. What are/are not acceptable ways of marking radiographs?
NOT acceptable to use pen or sticky label Acceptable:
- collimator marks,
- marker (L or R, Fore or Hind, view)
- ID label: name of practice, owner, date record no# -image
Describe the daylight and darkroom systems of ID radiographs
DL: using x-rite tape, or lead letters
DR: light box marker
Describe the chemical process (equipment) of creating radiographs, based on a manual system
Developing fluids: film placed in diff. fluids, kept in 3 chamber tank
- Developer: changes silver bromide & film to black metallic silver & is first solution film placed in
- Fixer: renders film light insensitive, also combined w/ hardener which hardens film emulsion to prevent scratching
- Water heater: developing fluid needs to be kept at 20˚C, use thermometer
- Developing tank: 3 chambers for developer - rinsing water
- fixer
- Stirring rods: stirs developing fluid prior to use. Evens temp & homogenises solution
What does the developer do?
- Affected crystals become black (silver precipitates)
- Unaffected crystals remain clear and wash off
What does the fixer do?
- Makes visible image permanent
- emulsion hardened
When should darkroom chemicals be renewed?
What are some tests that can be done to check this?
Before processing
- Developer pH test. Should be above 10-11.5 pH
- Fixer silver test. should be 3-6g/L
How much developer replenisher should you add if developer becomes exhausted?
Also how much for fixer?
- 400ml developer replenisher /sq m film
- 600ml fixer / sq m
Describe manual V auto processing
- rapid processing solution used in emergencies or surgeries
- film is developed and fixed for 15 - 20 seconds
- Does not have same amount of contrast as normal and will discolour w/ time
- no dark room req
What are contrast media in radiography?
Name two examples
- Used to give more detail of a particular organ or body system by admin. compounds that outline interior lining or body cavity
- Barium
- Iodine
Describe positive contrast media
- Show up as WHITE
- Barium suplahte used in GIT
- Iodine formulated in compounds used IV
Describe negative contrast media
- Show up as BLACK
- Gas used to outline organ
What should be carefully monitoring while a patient is under anaesthesia?
What can happen at deep levels of anaesthesia?
- Monitoring should be continuous; VS every 5 mins
- PR (rhythm and strength)
- HR
- MM colour
- CRT
- RR
- Tidal volume (size of breath; approx 10 -15ml/kg body weight)
- Temp
- At deep levels tissue perfusion and oxygenation can become impaired, leading to cell death
Monitoring equipment:
What is an oesophageal stethoscope?
- Used to continuously monitor heart and respiratory sounds
- signal may be heard through earpieces or speaker
Monitoring equipment:
What is an ap-alert respiratory monitor?
- sounds alarm of patient suffers apnoea (has not taken breath after specified time)
- Beeping sound emitted w/ each breath
- No info given on adequacy of breath
Monitoring equipment:
What is a pulse oximeter?
- Measures PR and degree of oxygen saturation in arterial blood
- Does this by measuring wavelengths of of red and infer-red light
Monitoring equipment:
What is an ECG?
- electrocardiography
- info on electrical activity of heart
- no info on cardiac output (how well heart is pumping)
- Does allow ID of arrythmias and other changes associated w/ physiological abnormalities
An anaesthetic record is an important legal document. What sort of things should be recorded?
- Animal and procedure deets
- baseline vital signs (b4 procedure)
- drugs given, before, during, in recovery period
- anaesthetic regime or equipment used
- vital signs
- any relevant comments
Once an animals temp falls to ………… cardiac arrest is likely to occur (from hypothermia).
These animals are prone to developing hypoxia.
- 28 - 30˚C
How should you remove an endotracheal tube post anaesthesia in:
dogs?
cats?
- dogs:
- remove tube once swallow reflex is regained
- cats:
- as soon as show signs of wakening
- Make sure cuff is deflated before removal
What does film density mean?
- blackening of the film
What does film contrast mean?
- difference b/w shades or densities on the RDG
Radiographic faults may occur due to?
(broad over view; 3 major points)
- Inappropriate restraint or movement of patient
- Failure to adequately maintain machine or equipment
- Problems w/ exposure settings or development process
What are the many possible reasons as to why a film may be TOO DARK/INCREASED DENISTY?
This includes manual errors, technical errors and automatic processing errors.
- mAs too high
- kV too high
- focal-film distance too short
- surge in incoming line voltage
- double exposure
- forgot to use grid
- overdeveloped
- developer temp too high
- over replenishing
- light leak in dark room/processor cover
- speed too slow/malfunctioning rollers
What is the kV(p) in relation to x-ray settings?
- KiloVolt Peak
- high = stronger x-ray
- controls quality (grey)
What is the mA in relation to x-ray settings?
- MilliAmps (x seconds)
- Controls quantity (black)
What are the many possible reasons as to why a film may be TOO LIGHT/DECREASED DENISTY?
This includes manual errors, technical errors and automatic processing errors.
- mAs too low
- kV too low
- focal-film distance too long
- drop in incoming line voltage
- no exposure
- thickness wrong (technique chart incorrect)
- underdeveloped
- too cold
- developer exhausted, too dilute, not mixed or contaminated
- developer temp too low
- under replenishing
- exhausted developer
What are the many possible reasons as to why a film may be GREY/FOGGED?
This includes manual errors, technical errors and automatic processing errors.
- accidental exposure to radiation (scatter, direct, secondary)
- no grid used w/ thick objects
- old film
- incorrect storage
- light leaking in
- wrong safelight intensity
- overdeveloping
- contaminated developer
- accidental x-ray exposure
- light leaking
- developer hot, contaminated, exhausted
- incomplete fixing
What are the many possible reasons as to why a film may have BLACK MARKS/SPOTS?
This includes manual errors, technical errors and automatic processing errors.
- scratches on film
- rough handling
- cassette not closed properly
- film exposed to light
- developer on unprocessed film
- films stuck together in fixer
What are the many possible reasons as to why a film may have WHITE MARKS/SPOTS?
This includes manual errors, technical errors and automatic processing errors.
- dirt/hair b/w film and screen
- crack or defect in screen
- damaged screens
- grit/dust on film surface
- air bubbles on film
- film touching sides of tank
What are the many possible reasons as to why a film may have LINES?
This includes manual errors, technical errors and automatic processing errors.
- grid out of focal range, upside-down, damaged
- primary beam not centred
What are the many possible reasons as to why a film may be BLURRED?
This includes manual errors, technical errors and automatic processing errors.
- grid out of focal range, upside-down, damaged
- primary beam not centred
- dirty rollers, wash water, air tubes
- jammed films
Poor image quality:
What may cause low contrast?
- Too high kV
- Slow speed screen/film
- No grid
- Under filtration
- Double exposure
Poor image quality:
Why may the image have poor detail?
- blurring due to motion
- machine focal spot too large or damaged
- unsharpness: double exposure, object too thick, FF distance too short
- Distortion/magnification: area of interest not close enough to film, primary beam not centred
How to improve image quality:
What shoulds you do if film intensity too dark?
- decrease mAs by 30 – 50%
- decrease kV by 10 – 15%
How to improve image quality:
What shoulds you do if film intensity too light?
- Increase mAs by 30 – 50%
- Increase kV by 10 – 15%
How to improve image quality:
When should you increase the factors?
- object has increased fluid
- obesity
- plaster cast
- positive contrast rdg (barium, iodine)
Evaluating the improperly exposed radiograph
(view pic in answer)
What details should you put in the radiographic record?
- date
- patient name/ID number
- client name
- type of animal
- area viewed
- positioning
- tissue depth
- exposure factors used
- use of grid
- developing time
- comment on film quality
How should you clean and maintain equipment?
(simple, brief, not step by step).
- Follow manufacturers instructions.
- Do not bump tube
- Keep tube free from dust, dirt and safely retracted out of the way
- Never hold x-ray machines or tubes during exposure
- Avoid prolonged use of ready modes and lighting of collimator
- Clean surfaces w/ metho
