Radiology Flashcards
What is radiography?
X-Ray; photons interact with tissue; attenuated photons don’t make it to detector; photons not attenuated will pass through to be recorded by detector
Define Radiopaque
No penetration; appears white
Bone, metal
Define radiolucent
complete penetration; appears black
Define shades of grey in context of radiography
Partial penetration
What does degree of penetration in radiography depend on?
Atomic number and thickness; more absorption = higher atomic number/more thick
What appears the same on radiography?
water and soft tissue; although all is relative
What is used for radiographic contrast? How do they appear on radiograph?
Iodine or barium; highly attenuated
What are the two radiographic views?
Frontal (AP or PA) and lateral
Put these radio densities in order from highest density to lowest: contrast, acute blood, fat, metal, gas, bone, water/soft tissue
[high] metal/bone, contrast, acute blood, water/soft tissue, fat, gas [low]
How does computed tomography (CT) work?
Ionizing radiation creates cross-sectional images of the body
What plan is a CT taken?
Images are acquired in axial (transverse) plane then used to create images in any plane (commonly sagittal or coronal) and is composed of voxels
What does a CT highlight?
Tissues of interest for CT are soft tissue, lung window, and bones
What contrast is used for CT?
Enteric (oral or rectal): barium or iodine
Intravenous: iodine (barium CANNOT be given IV)
What is the correct verbiage to describe CT?
Attenuation
Describe hypo attenuation
Darker than background organ
Describe iso attenuation
equal in attenuation with background organ
Describe hyper attenuation
Brighter than background organ
Ultrasound is based on the detection and display of what?
It is based on the detection and display of acoustic energy (sound waves) reflected from interfaces in the body
What is a pro of using ultrasound imaging?
No ionizing radiation (pediatrics, pregnant women, etc.)
Describe amplitude of ultrasound imaging
Amplitude of returned signal indicates strength of reflection; high amplitude appears white and low amplitude appears dark
What does timing indicate in ultrasound?
The depth at which the echo originated
Describe the ultrasound planes used
Transverse: oriented like axial in CT scan
Longitudinal: imaging an organ along its axis (either sagittal or coronal)
What terminology is used to describe ultrasound?
Echogenicity
What can be used in CT to better visualize something?
enhancement
Describe what hypoechoic looks like
Darker than background organ
Describe what anechoic/echolucent appears like
black coloring
Describe how hyperechoic appears on an ultrasound
Brighter than background or organ; sound does not pass through bone or gas resulting in hyperechoic appearance on screen
Describe how objects in movement appear on an ultrasound
Stationary objects: no change in frequency of sound wave as it bounces off of target (FR=FT)
Moving objects: target moving towards transducer (FR>FT) and target moving away from transducer (FR<FT)
FR= frequency received
FT= frequency transferred
How are magnetic resonance imaging (MRI) images created?
By strong magnetic fields and radio frequency waves: imaging protons (hydrogen atoms in fat and water)
Benefit: no ionizing radiation
Disadvantage: takes a long time
Describe a T2 weighted MRI
Static fluid appears bright (look for CSF); highlights pathology (edema)
Describe T1 weighted MRI
static fluid appears dark (look for CSF) and highlights anatomy
Describe fat sat for T1 and T2 MRIs
Results in low signal intensity in the appearance of fat
How can you tell the difference between MRI and CT?
Look for bones; bones appear more clearly on CT (i.e., look for ribs)
What is the correct terminology for MRI scans?
Intensity
Describe hypointense
Area appears darker than background organ
Describe isointense
area appears equal in color to background of the organ
Describe hyper intense
Area appears brighter than background organ
What is used for MRI contrast?
Gadolinium based - makes tissue appear brighter on T1 weighted MRI (IV); usually use enhancement after to see even better
