Thoracic Radiographs

Question 1

is there more natural contrast in the thorax or abdomen

Answer 1

thorax

more air in thorax than abdomen –> less beam attenuation

Question 2

is the thorax a high motion area

Answer 2

yes - breathing causes motion

Question 3

what kVp and mAs settings should you use

Answer 3

HIGH kVp - decreases contrast

LOW mAs - decreases motion/blur

Question 4

how does overexposure appear on radiographs

Answer 4

black/darker

Question 5

how does underexposure appear on radiographs

Answer 5

bright

Question 6

standard views for thoracic radiographs

Answer 6

right lateral
left lateral
DV

Question 7

how can you tell which side the lateral view is in

Answer 7

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

Question 8

what is a horizontal beam study

Answer 8

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

Question 9

why DV over VD

Answer 9

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

Question 10

at what point during respiration should you take the radiograph

Answer 10

peak inspiration

lungs fill with air –> makes thorax appear larger

Question 11

what is the appropriate window for thoracic radiographs

Answer 11

thoracic inlet to diaphragm

Question 12

proper patient positioning for thoracic radiographs

Answer 12

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

Question 13

how do obliqued images affect the radiograph

Answer 13

distorts the heart shape and causes asymmetrical lung fields

Question 14

what is the systematic approach to viewing thoracic radiographs

Answer 14

1. skeletal structures
2. abdomen
3. heart
4. vessels
5. lungs
6. pleural space
7. mediastinum

Question 15

what are the skeletal structures in the thorax

Answer 15

cervical and thoracic vertebrae
ribs
scapula
proximal humerus

Question 16

what abdominal structures can you see in the thoracic radiograph

Answer 16

liver
stomach
peritoneal detail

Question 17

what do you evaluate about the heart

Answer 17

cardiac silhouette
- shape
- size
- margins

Question 18

can you see individual lung lobes

Answer 18

no

Question 19

normal appearance of pulmonary vessels

Answer 19

located on either side of the bronchi

lateral: veins are ventral, arteries are dorsal

DV: veins are medial, arteries are lateral

Question 20

how does a cat thorax vary from a dog thorax

Answer 20

smaller and more oval cardiac silhouette

triangular thoracic field

Question 21

deep chested vs round chested breeds

Answer 21

deep chested: narrow cavity, elongated heart
round chested: round heart

Question 22

how does the heart appear in athletic breeds

Answer 22

larger heart

Question 23

what is unique about Bassett hound thorax rads

Answer 23

curved ribs

Question 24

age related changes in thoracic radiographs

Answer 24

• calcified tracheal rings/bronchial walls/costal cartilage
• pleural fissure lines
• increased lung density
• aortic ectasia
• “horizontal heart” in cats

Question 25

what is a visible structure in young animals

Answer 25

thymus

visible in cranial mediastinum

Question 26

how does obesity affect thoracic radiographs

Answer 26

fat deposits in mediastinum and pericardium
increased lung opacity
skin folds

can increase exposure to avoid underexposing