5 – Intro to Thoracic Radiography

Question 1

kVp for thorax

Answer 1

• Increased for larger areas and body parts (Ex. THORAX)
  o Higher penetration power (higher QUALITY)

Question 2

mA for thorax

Answer 2

• Decreased for adequate contrast of thoracic structures and to decrease radiation exposure
  o Lower number of X-rays being produced (QUANTITY of the beam)

Question 3

Exposure time for thorax

Answer 3

• How long X-rays are produced for
  o DECREASED to reduce motion blur (respiration)

Question 4

mAs for thorax

Answer 4

• Low

Question 5

Thorax standard radiographic views

Answer 5

• At least 2 orthogonal views (**R. lateral, DV)
• 4 is strongly recommended for a more ACCURATE evaluation and to avoid missing subtle lesions
• *want it on max INSPIRATION (“end of inspiration”)

Question 6

Right/left lateral view

Answer 6

• Right/left lateral recumbency
• Thoracic limbs pulled cranially
• Field of view
  o Just cranial to thoracic inlet (don’t want it to superimpose)
  o Few cm caudal to the last rib (b/c lungs extend caudally, ‘around’ the curved diaphragm)

Question 7

**How do you distinguish if it is R vs. L lateral view?

Answer 7

• Right
  o **Dorsal crura of diaphragm are PARALLEL
  o Heart slightly more elongated, not elevated from the sternum
• Left
  o **Dorsal crura of diaphragm DEVIATE from each other (“Y-shape”)
  o Heart slightly more round and elevated from the sternum

Question 8

Ventrodorsal view (VD)

Answer 8

• Dorsal recumbency
• Thoracic limbs pulled cranially
• Field of view (FOV)
  o Just cranial to thoracic inlet
  o Few cm caudal to last rib
• *symmetry is important: use collimation as a guide
• Markers: right side of patient should be on our left side (when we look at it)

Question 9

How do you distinguish VD from DV view?

Answer 9

• DV view
  o Diaphragm cranially displaced
  o Cardiac apex shifted to the left
  o Cardiac silhouette more rounded (often misinterpreted as cardiomegaly)
  o Caudal lobar vessels are more conspicuous (due to being in sternal recumbency and caudal dorsal lungs being more aerated)

Question 10

Lung lobes

Answer 10

• Left
  o Cranial
   Cranial and caudal segments
  o Caudal
• Right
  o Cranial
  o Middle
  o Caudal
  o Accessory

Question 11

Dog heart size and vertebral heart score (VHS): lateral view

Answer 11

• <2.5-3.5 intercostal spaces
• VHS: 9.7 +/- 0.5v (range 8.7-10.7)

Question 12

Cat heart size and vertebral heart score (VHS): lateral view

Answer 12

• <2-2.5 intercostal spaces
• VHS: 7.8v (7-8)

Question 13

Cardiac width in orthogonal view

Answer 13

• <2/3 of the chest wall (dogs and cats
• Not used too often

Question 14

*Location of cardiac chambers: lateral view

Answer 14

• Left side: caudal
• Right side: cranial
  o Most contact with sternum

Question 15

*location of cardiac chambers: DV view (“clock”)

Answer 15

• 12-1: aortic arch
• 1-2: MPA
• 2-3 L. auricle
• 3-6: L. ventricle
• 6-9: R ventricle
• 9-11: R. atrium

Question 16

Caudal vena cava normal diameter

Answer 16

• <1.5x aorta
• <length of T5 or T6

Question 17

Pulmonary vessels: lateral view

Answer 17

• LEFT lateral is better than right
• Normal diameter
  o Arteries should be approximately the same diameter as veins
  o BOTH <diameter of the 4th proximal rib

Question 18

Pulmonary vessels: DV or VD view

Answer 18

• DV view is better than VD
• Normal diameter
  o Arteries should be approximately the same diameter as veins
  o BOTH=diameter of the 9th rib (if form a perfect square)