Felsons (CXR)

Question 1

PA - patient should be ____ ft from beam and patient should be close/far from cassette

Answer 1

6ft / close to cassette - this minimizes magnification and maximizes detail and patient inspiration

Question 2

Heart is larger on PA / AP chest

Answer 2

AP chest - heart is further from cassette so increases magnification

Question 3

Left lateral - which side is by cassette / shows which region / which sided nodules will look bigger?

Answer 3

Left side against cassette / shows between heart and mediastinum / right sided nodules look bigger

Question 4

L / R anterior oblique - helps localize what? how?

Answer 4

helps localize lesion to ant vs. post / L or R chest is obliquely against the cassette

• when anterior structures rotate, they move laterally
• when posterior structures rotate, they move medially

Question 5

Lateral decubitus - helps with what?

Answer 5

• can help find pleural effusion (fluid sinks)

- can help find small PTX (air rises)

Question 6

Expiratory films and AP supine films make heart/vessels look _______ and lungs look ______

Answer 6

• larger

- whiter (less aeration)

Question 7

How do Expiratory films help see asymmetrical empysema? small PTX?

Answer 7

• air is trapped and therefore during expiration the affected lung looks blacker
• deflated lung is darker

Question 8

For best image

• ____ ft from beam
• ____ to cassette
• ____

Answer 8

• 6ft
• close
• grid - minimizes scattered photons, maximizes direct photons

Question 9

Reading sequence

Answer 9

Abdomen
Thorax (soft tissue and bone)
Mediastinum
Lungs (unilateral)
Lungs (bilateral)

Question 10

Normal gas containing structures of the abdomen on CXR

Answer 10

• stomach
• hepatic flexure
• splenic flexure

Question 11

Which diseases in lower lungs can mimic upper abd disease?

Answer 11

• PNA, pleurisy

Question 12

Which diseases in Abdomen can mimic lower lung disease?

Answer 12

• subphrenic abscess
• perforated abscess
• pancreatitis
• cholelithiasis

Question 13

Interstitial disease appearance

Answer 13

• thickens interstitium (around small vessels / interlobular septa) at periphery of lung (where interstitium normally disappears)
• makes interstitium appear more white
• alveoli remain normally aerated (black)
• increased contrast between interstitium and alveoli

Question 14

Alveolar disease appearance

Answer 14

• fluid or tissue in alveoli (makes white)

- therefore less distinction between alveoli and interstitium

Question 15

Hounsfield units

• water
• lung
• fat
• muscle
• bone
• heart/vessels/mediastinum

Answer 15

• water = 0 HU
• lung = -800 HU
• fat = 80-120 HU
• muscle = +40 HU
• bone = +350
• heart/vessels/mediastinum = -40/0/+40

Question 16

Lobar Anatomy

• Left lung
• Right lung

Answer 16

Left lung

• major oblique fissure (btw LUL and LLL)
• fissure only visible on lateral (parallel to beam)

Right lung

• major fissure (btw RUL/RLL) -
• minor horizontal fissure (btw RUL/RML) - visible in both PA and lateral in some patient’s unless sloping downward

Question 17

• if a lobe is consolidated, the fissure appears more like ____
• if pleural fluid enters a fissure, it _______

Answer 17

• an edge

- thickens