1- radiology of thorax

Question 1

what are the different colours that different materials are on x-ray?

Answer 1

air = black (as photons travel through and unlikely to hit anything)

fat = grey

soft tissue/muscle = grey/white

bone = white

metal = bright white (very good at stopping x-rays)

Question 2

what are the relative CT densities?

Answer 2

air = -1000
lungs = -500
fat = -100
water = 0
muscle = +50
bone = +200
contrast = +500
metal = +1000

Question 3

what does fluid, soft tissue, air and bone look like on ultrasound?

Answer 3

Fluid allows passage of sound waves … black

Soft tissue allows passage of sound waves … bright

Air blocks passage of sound waves … shadow

Bone blocks passage of sound waves … shadow

Question 4

how is a standard chest xray done?

Answer 4

standard PA = xray goes from posterior anterior

• patient stands 2 metres from x-ray against x-ray plate
• patient stand with shoulders forward (to get shoulders out pic)
• they have to breathe in and hold breath
• further from source = more magnification

Question 5

how do you do chest x-ray on someone who can’t stand? and why is that not as good?

Answer 5

• get AP view = anterior to posterior
• less easy to assess size of heart and shoulders usually in view so not as good

Question 6

how to analyse chest xray?

Answer 6

• make sure looking at right patient on right day
• is side marker on chest x-ray - shows if correct way around? usually like right or left

Is it technically adequate? Consider the ‘ations’

• Inspir-ation
• Rot-ation
• Penetr-ation (which means ‘is there enough radi-ation?’)

Question 7

what is bad about poorly inspired or poorly rotated chest x-ray?

Answer 7

can simulate pathology when none is there
(like if from wrong angle)

Question 8

how can you check if adequately inspired chest xray?

Answer 8

the anterior ends of at least 5 ribs should be visible

Question 9

how can you check that the chest x-ray is correctly centred?

Answer 9

the medial ends of the clavicles should be equidistant from the spinous processes of the upper thoracic vertebrae

Question 10

what structures should you expect to see to check mediastinal structures?

Answer 10

1. Aorta
2. Pulmonary artery
3. Left auricle
4. Left ventricle
5. Right atrium
6. Trachea
7. Hemidiaphragm (right)
8. Stomach bubble
9. Horizontal fissure

Question 11

what is a difference between right & left bronchi and what does this suggest?

Answer 11

right main bronchus slightly straighter than left (due to heart) so if you drop something down trachea then tends to go down right instead of left so if aspiration pneumonia tend to get problems in right lung over left

Question 12

what are areas that should be checked on lateral radiograph of lung?

Answer 12

1. Oblique fissure = from T4 at back
2. Horizontal fissure
3. Posterior costophrenic recess
4. Retrosternal space

Question 13

why is it important to know which bit of lung infected i.e. which lobe?

Answer 13

to help focused treatment

Question 14

what is consolidation in lungs?

Answer 14

when the air in the small airways of the lungs is replaced with a fluid, solid, or other material such as pus, blood, water, stomach contents, or cells