63 - X-ray Imaging of the Thorax

Question 1

Films used to image X-rays

Answer 1

Silver halide films. X-rays catalyse conversion of silver halide to silver (white colour)

Question 2

What is an X-ray measuring?

Answer 2

Electron densities of whatever X-rays are being sent through

Question 3

Which tissues can’t be separated on an X-ray?

Answer 3

Tissues with the same electron density that are abutting one another

Question 4

How is a normal chest X-ray taken? 1) 2) 3) 4)

Answer 4

1) X-rays shone from posterior to anterior. 2) Patient at full inspiration 3) Scapulae are moved away from chest wall (hug X-ray cassette) 4) Patient must be erect

Question 5

In a normal chest x-ray, why do the x-rays pass posterior to anterior?

Answer 5

So that the heart is closer to the film. X-rays emitted in a conical shape, so closer structures are magnified

Question 6

Why does a patient need to be in an erect position for a chest x-ray?

Answer 6

Open up lungs. If normal, most blood should be in lower lobes (low pressure, gravity). If more blood is in upper lobes, indicates elevated pressure, possible heart failure

Question 7

How can you tell if an X-ray was taken on an erect patient at full inspiration?

Answer 7

Count ribs. Should be 7 anterior ribs visible above hemidiaphragm on one side.

Question 8

How can you tell if a patient was sitting straight on an X-ray?

Answer 8

See if sternal notch aligns with spinous processes of vertebra.

Question 9

*Position of a normal heart on an x-ray

Answer 9

Question 10

How is the thorax divided on an x-ray?

Answer 10

Divide into upper, middle and lower zones. Divide upper zone into halves. Upper half = apex. Divide lower zone into halves. Lower half = base.

Question 11

How can you find parts of the heart on an x-ray?

Answer 11

Use angle of Louis (Manubriosternal junction-T4/T5) to find level where R, L bronchi join.

Question 12

Structures in superior mediastinum 1) 2) 3) 4) 5) 6)

Answer 12

1) Aortic arch 2) SVC (and branches of great vessels) 3) Upper oesophagus 4) Trachea 5) Vagus nerves 6) Lymph nodes

Question 13

Structures in the anterior mediastinum 1) 2) 3)

Answer 13

1) Thymus 2) Fat 3) Lymph nodes

Question 14

Structures in middle mediastinum 1) 2) 3) 4)

Answer 14

1) Heart 2) Great vessels 3) Phrenic nerves 4) Lymph nodes

Question 15

Structures in posterior mediastinum 1) 2) 3) 4) 5)

Answer 15

1) Oesophagus 2) Descending aorta 3) Azygous vein 4) Thoracic duct 5) Lymph nodes

Question 16

Difference in appearance of fluid and air in pleural spaces

Answer 16

Fluid sinks to bases, air rises to apices (only when patient is erect)

Question 17

*How to distinguish between hydrothorax and hydropneumothorax

Answer 17

Hydrothorax liquid will have a meniscus. Hydropneumothorax will have no meniscus.

Question 18

Why is there a meniscus in hydrothorax, but not hydropneumothorax?

Answer 18

Lung pressure is normally below that of atmospheric pressure. When fluid enters, this leads to meniscus. In hydropneumothorax, air pressure in lung is atmospheric, as air is entering pleura. This prevents meniscus formation

Question 19

Long checklist of things to consider when viewing a chest x-ray 1) 2) 3) 4) 5) 6) 7) 8) 9) 10)

Answer 19

1) Patient age, sex 2) Posterior/anterior, erect, inspiratory, exposure time 3) Medical devices, foreign bodies 4) Heart size, valves (if calcified) 5) Mediastinal size, contours and divisions 6) Normal lungs - look for airspace, airways, interstitium, lobes/zones 7) Abnormal lungs - nodules, masses, scars, cavities 8) Pleura - effusion, pneumothorax 9) Diaphragm, upper abdomen, lower neck 10) Soft tissues (EG: breasts),bones, joints

Question 20

Answer 20

Pneumonia. Clearly-defined path of debris, bounded by horizontal fissure.

Question 21

Answer 21

Septicaemia. Circular mass in right upper zone of lung. Could be an abscess, pulmonary embolus (need a CT to confirm)

Question 22

Answer 22

Lung cancer. Only one lung affected, rapid onset, so not COPD. Left lung is full, loss of volume (lung collapse), as air can’t enter lung, perhaps because occluded by cancer.

Question 23

Answer 23

Cancer. Not within lung, below angle of Louis. Anterior mediastinal mass (structures here are thymus, fat, lymph nodes). Fat cancers are rare, thymus still possible in a young person, lymphoma most likely.

Question 24

*roadtraum

Answer 24

Ruptured aorta Aorta is very enlarged (if rupture is at the level of the aortic ring, death. If at level of ligamentum arteriosum, then patient can survive)

Question 25

Answer 25

Congestive heart failure He has a pacemaker (evidence of previous heart problems) Very enlarged heart. Fluid at the base of lungs

Question 26

Answer 26

Pneumothorax Very-sudden onset. Air visible in left lung (superior part). Appears darker here.