Apr. 4: Fluoroscopy, Computerized Tomography, and Small Animal Special Procedures

What is the primary function of fluoroscopy?

provides dynamic real time imaging of anatomical structures using a continuous beam of x-rays

What is an image intensifier?

an electronic device on fluoroscopy unit used for image detection by receiving remnant radiation exiting the patient and converting it into a visible light image of high intensity

What are the layers of the input screen?

support layer, input phosphor, photocathode

What is the support layers purpose?

focus electrons toward opposite end of the intensifier

What is the input phosphor’s purpose?

allows light to exit

What is the photocathode’s purpose?

absorb light and emit electrons

What is the electrostatic focusing lens purpose?

help focus the electrons toward the anode

What is the output phosphor’s purpose?

convert phosphor back into light photons

What is the output window’s purpose?

final viewing

What is “dark adaption” regarding fluoroscopy?

letting eyes adapt to dim light of screen prior to procedure

What does CAT stand for?

computerized axial tomography

What does CTAT stand for?

computerized trans-axial tomography

(T/F) CT uses radiation

true

How is CT slice thickness determined?

operator of the CT scanner

What’s the smallest possible slice that a CT scan can take?

smaller than a millimeter

(T/F) CT scanners utilize kVp and mAs that are much lower than conventional x-ray units

false (much higher than conventional)

How does contrast work?

changes the density or atomic number of an organ to make the tissue/organ visible

What color would positive-contrast agents appear on radiographs?

white/radiopaque

What color would negative-contrast agents appear on radiographs?

black/radiolucent

What must be evaluated prior to attempting study?

patient ability to withstand risks

What is a morphological study?

contrast study observing form and structure of an organ or organ system

What is a functional study?

contrast study evaluating activity or way an organ or organ system works

What positive contrast medium should not be used if bowel perforation is suspected?

barium sulfate

What are the positive contrast mediums?

barium sulfate, water soluble organic iodides

What happens to molecules with ionic iodides?

molecules dissociate and cause changes to osmolality (higher osmolality causes greater risk of anaphylactic reaction)

What happens to molecules with nonionic iodides?

molecules remain whole in solution (lower osmolality has less risk of anaphylactic reaction)

What are effects of osmolality?

crenation of RBCs and reactions

What is an important patient preparation step for GI studies?

noting any anesthetic agents and their effect on transit time

What is esophagography?

contrast radiography of the esophagus

What are precautions of an esophagram?

aspiration of the contrast agent