T3: Imaging Modalities Flashcards
What is Digital Radiography and what does it involve?
- Uses no films, chemistry or processor
- A single unit which incorporates both camera and processor into one machine
- Consists of a monitor attached to a computer with a special DR plate in same room
- Coversion to DCIM on computer
How do you use DR?
- Warm machine up
- Wait for signal it is ready (green light)
- Patient details are entered into the computer
What are the selections to be entered into the computer when using DR?
- Anatomy
- Projection
- Choose either full or high res field
- Measurements (use callipers first)
What are some benefits of DR?
- Less takes are needed because you can manipulate the image
- Can manipulate contrast and view
What is Computed Radiography and what does it involve?
CR Imaging is done using the original Xray head/generator but using a CR reader and a CR casette and bucky.
The screen stores the energy in proportion to the intensity and when placed in the CR reader, the energy is converted to visible light when scanned by a laser. This is then converted from a raw image into a digital image file.
How do you use CR?
- Place the casette under the buck tray
- Once image is acquired, remove the casette and place into CR reader
What must you NOT do in CR?
DONT DROP THE PLATES
What is fluroscopy and what does it involve?
Fluroscopes perform dynamic studies, helping visualise the motion of fluids and the bodies internal structures in a real time image.
It takes a continuing stream of xray images at a rate of approx 25-30 images per sec. They are then viewed on a monitor with the images being played together.
What can Fluroscopy be used for?
Diagnosing:
- swallowing disorders eg strictures
- collapsing trachea
- motility problems of the stomach and intestines
- flow of blood through abnormal vessells
Orthopedic procedures such as fracture repairs
Contrast studies such as the path of the oesophogous and GIT, contractions of the stomach and intestines and urinary contrast studies.
What is Computed Tomography and what does it involve?
A thin Xray beam rotates around an area of the body, generating a 3D image of the internal structures.
Images are taken in slices.
What is the standard slice scanner used in practices?
16 slices
What are the benefits of an increased slice count?
Offers higher resolution which is useful in cancer diagnosis. Makes it easier to assess the progression of the disease.
What are CTs used for?
Detecting
- tumours
- haemorrhage
- complex fractures
- abdominal disease
- coronary arteries
- spinal lesions
Bone scans
Brain scans
Imaging of the lungs - can detect lung parenchyma
What is Scintigraphy and what does it involve?
A radioactive tracer is injected into animal which distributes around the body and is taken up by areas with increased blood supply and metabolic ativity.
These areas emit Gamma rays detected by a gamma camera, which produces an image of the funcation, shape, size and position ofthe target organ.
Areas of increased bone turn over are shown as hot spots on the images.
What is Scintigraphy used for?
Bone, thyroid and kidney scans
Comonly used in horses to detect injuries such as mulitple limb or shifting limb lameness
What is the most common radioactive tracer injected into the animal when using Scintigraphy?
Technetium-phosphonates
What should you do with the animal after scintigraphy?
Isolate it for 24-36 hrs to allow body to clear the radioactive tracer.
Dispose of waste correctly as this contains radiation as well.
What is Megnetic Resonance Imaging and what does it involve?
When a patient enters the MRI tube, the protons in the patients body react by lining up like magnets do with the needle of a compass.
When the radio waves are sent out in short bursts, they knock these protons out of alignment.
When the radiowaves are turned off, the protons then realign and send out radio signals with info about the protons, which are picked up by receivers.
This is then converted into an image.
Is radioation used in MRIs?
No
How much does an MRI machine weigh?
Around 3-4 tonne
What is the magnetic field like on an MRI machine?
Very strong, even when machine is switched off.
Anything containing metal such as collars, drip stands etc must be removed before entering the area housing the MRI room
What are MRIs good for looking at?
Soft tissue
Bone
Ligaments
Tendons
Organs
What are some cons of MRIs?
Noisy
Lengthy
Patient needs to be anaethesised
Horses can only fit head in
Expensive
