Rad2 Flashcards
Nuclear Scintigraphy (NS)
- Use of radioactive material to create images that are indicative of physiologic activity in internal organs
- NS images are not intended to provide anatomic detail
- A radioactive isotope is administered intravenously, transcolonically, or by insufflation
- The radioactive isotope (i.e. radionucleide, radiopharmaceutical) is preferentially absorbed by the target tissue
Settings for Exotic animals
- Exposure factor settings will be generally lower than those used on dogs or cats
- Use highest mA with shortest exposure time. Instead of bumping KVP
- Exotic animals are usually not measured with caliper exposure factors settings based on species and general size
Restraint of exotics for radiographs
• Manual • Physical using positioning devices o Plexiglas sheets and tubes o Radiolucent adhesive tape o Sandbags and ropes • Chemical o Inhalant or injectable anesthesia
Computed Tomography
(CT or CAT scan)
• Use of X-rays and a computer to produce images of the internal anatomy of an animal in cross-section
• Allows visualization of structures in different planes without tissue superimposition
• CT unit consist of movable cradle, gantry, and computer for generating the image
Gantry and Cradle
- Gantry contains X-ray tubes and X-ray detectors
- Cradle moves patient through portal in gantry a few millimeters at a time when scanning
- X-ray tube and detectors can move 360° around patient
Magnetic Resonance Imaging
(MRI)
• Use of a magnetic field and radio waves to produce images of the internal anatomy of an animal in cross-section
o Animal is placed within magnetic field
o Radio wave pulse is directed at tissue to be imaged
o Chemical composition of tissue determines the degree of absorption and rate of release of radio waves
NS scans are most often performed on…
- horses to help diagnose the cause of lameness; NS
- hyperthyroid cats to determine if surgical excision of the thyroid gland is a viable treatment option
. NS image consists of…
block dots on a piece of X-ray film, each dot is representative of a gamma ray emission from tissue
Animals receiving a radiopharmaceutical
• will emit radiation until the radioactive isotope is eliminated from their body
o Animals are typically hospitalized for 24-72 hrs.
o Contact time with the hospitalized animal should be limited
o Radioactive isotope is excreted in animal’s urine and feces
o Wear protective gear and keep a fair distance between you and the animal during the scanning procedure
The radioactive isotope emits….
low levels of radiation (as gamma rays) which can be detected by specialized equipment held in close proximity to the animal’s body
there increased metabolic activity if…
• More of the radioactive isotope is absorbed by the target tissue
More activity in the darker areas of the image
Radiographic Contrast Studies
• Contrast media attenuates the X-ray beam and helps differentiate tissues from each other
Positive contrast agents
increase the subject density of organs and cause them to appear radiopaque on a radiograph
Negative contrast agents
decrease the subject density of organs and cause them to appear radiolucent on a radiograph
Positive contrast agents include:
o Barium sulfate– oral/rectal administration- coats and settles
o Water-soluble organic iodide compounds– IV administration, injection into other body cavities
o Diatrizoate, meglumine (Renografin, Hypaque)
o Iohexal (Omnipaque)
