Clinical imaging of thorax part I (AS lecture) Flashcards
Wilhelm Roentgen
When were X-rays discovered and by who
- 1895
- wilhelm conrad roentgen
what appears black on x ray
air
what appears gray but darker than soft tissue on x ray?
fat
what 2 things appear white-ish gray and have the same density on radiographs?
- fluid
- soft tissue
what is the most dense naturalling occuring material in the body that absorbs more x-rays in the body and where is most of it found?
- calcium
- mostly found in the bones
what material usually absorbs all x-rays and appears the whitest on conventional radiographs?
metal
what are 5 advantages of plain radiographs
- quick
- cheap
- low dose radiation
- can be portable
- can detect range of pathologies
X-ray techniques
what are 4 disadvantages of plain radiographs
- lacks detail
- ionising radiation (even though low amounts)
- limited range on densities
- difficult to perform on some patients
X-ray projections
outline 2 reasons why PA view is preferred over AP view in X ray imaging
PA views are:
- higher quality
- heart size is nearer to real size as heart is nearer to the detecter
outline 4 x-ray projection techniques
- posterior anterior/anterior posterior view
- left lateral/right lateral
- AP recumbant ( AKA AP supine)
- right oblique/left oblique view
why is heart magnification minimised in PA view vs AP view?
heart magnification is minimised due to the use of a narrower beam, produced by the increased distance between the source and the patient.
what 2 reasons explain why heart size is exaggerated in AP view compared to PA view?
heart size is exaggerated in AP view because:
- heart is farther away from detector
- X-ray beam is more divergent as source is nearer the patient
what are the 4 main things to observe when conducting an X-ray?
- Rotation
- inspiration/expiration
- penetration
- heart (cardiac shadow)
what 3 questions are asked when checking for rotation in an X-ray?
3 questions asked when checking for rotation in X-rays are:
- do the thoracic vertebral spines align in the centre of the sternum and between the clavicles?
- are the clavicles in the same level
- is the trachea in the midline?
how many anterior and posterior parts of the ribs should be visible in full inspiratory chest radiograph films?
posterior: 9-10
anterior:5-7
where do the anterior parts of the ribs intersect the diaphragm?
- intersect the diaphragm at the mid-clavicular line
what increases in likelihood if a chest X-ray is underexposed and why does this increase in likelihood?
This increases the likelihood of missing an abnormality in overlying structures as the thoracic vertebrae will not clearly be visible
what is a characteristic of over-penetrated chest x-rays, what does this decrease/make absent on x-ray and what 3 things can be missed on an x-ray because of this?
characteristic:
- diffusely dark
this decreases the visibility of pulmonary markings or makes them absent on chest x-ray
3 things that can be missed on an x-ray because of this are:
- pneumothorax
- consolidation
- emphysema
state what ABCDE is in other things to observe in X-ray radiographs
A: Airways Trachea, endotracheal tube, etc.
B: Bones (Clavicles, ribs, sternum, thoracic vertebrae, etc.)
Cardiac shadow
Diaphragm: Remember the right hemidiaphragm is slightly higher.
Everything else: Any wire, tubes, pacemaker, effusions, etc.
what level is the aortic knuckle visualised on chest x-ray?
- around the level of T4/T5 or lateral to the carina
what is the characteristic of the costophrenic and costo-cardiac angles?
characteristic:
- should be sharp and well-defined
what does it mean if the costo-cardiac and costophrenic angles are blunted/lost?
this means there is a chance fluids in the pleural cavity (known as pleural effusion)
where is the gastric bubble normally seen?
under the left hemidiaphragm
what does free air under the right hemidiaphragm suggest?
suggests bowel perforation
what does deviation of the trachea from the midline suggest?
suggests presence of a **mediastinal mass **or tension pneumothorax
