Thoracic Radiographs Flashcards
is there more natural contrast in the thorax or abdomen
thorax
more air in thorax than abdomen –> less beam attenuation
is the thorax a high motion area
yes - breathing causes motion
what kVp and mAs settings should you use
HIGH kVp - decreases contrast
LOW mAs - decreases motion/blur
how does overexposure appear on radiographs
black/darker
how does underexposure appear on radiographs
bright
standard views for thoracic radiographs
right lateral
left lateral
DV
how can you tell which side the lateral view is in
diaphragm
right lateral: if R crus is more cranial + caudal vena cava empties into cranial crus
left lateral: if L crus is more cranial + caudal vena cava empties into caudal crus
what is a horizontal beam study
patient is in R or L lateral but the image is shot in DV
gravity pushes on the lung that is down
top lung space becomes more visible, bottom lung space becomes less visible
why DV over VD
DV is a more physiological position for the heart
- narrow thoracic cavity
- diaphragm contacts heart
- more accurate vessels
VD can make the heart appear larger/shifted
- wider thoracic cavity
- better for cranial and caudal lung lobes
at what point during respiration should you take the radiograph
peak inspiration
lungs fill with air –> makes thorax appear larger
what is the appropriate window for thoracic radiographs
thoracic inlet to diaphragm
proper patient positioning for thoracic radiographs
legs forward
neutral neck position
lateral: flat spine, R and L ribs should superimpose on each other, top rib should not be above the spine
DV: spinous processes should superimpose over spine, lung fields should be symmetrical
how do obliqued images affect the radiograph
distorts the heart shape and causes asymmetrical lung fields
what is the systematic approach to viewing thoracic radiographs
- skeletal structures
- abdomen
- heart
- vessels
- lungs
- pleural space
- mediastinum
what are the skeletal structures in the thorax
cervical and thoracic vertebrae
ribs
scapula
proximal humerus
what abdominal structures can you see in the thoracic radiograph
liver
stomach
peritoneal detail
what do you evaluate about the heart
cardiac silhouette
- shape
- size
- margins
can you see individual lung lobes
no
normal appearance of pulmonary vessels
located on either side of the bronchi
lateral: veins are ventral, arteries are dorsal
DV: veins are medial, arteries are lateral
how does a cat thorax vary from a dog thorax
smaller and more oval cardiac silhouette
triangular thoracic field
deep chested vs round chested breeds
deep chested: narrow cavity, elongated heart
round chested: round heart
how does the heart appear in athletic breeds
larger heart
what is unique about Bassett hound thorax rads
curved ribs
age related changes in thoracic radiographs
- calcified tracheal rings/bronchial walls/costal cartilage
- pleural fissure lines
- increased lung density
- aortic ectasia
- “horizontal heart” in cats
what is a visible structure in young animals
thymus
visible in cranial mediastinum
how does obesity affect thoracic radiographs
fat deposits in mediastinum and pericardium
increased lung opacity
skin folds
can increase exposure to avoid underexposing
