CXR Flashcards
Four basic radiodensities
- Gas = Black e.g. air filled lungs
- Fat = Grey e.g. lipid tissue around muscle
- Soft tissue = Grey e.g. heart, blood vessels & muscle
- Bone or metal = White e.g. ribs & sternum
Types of CXR
Posteroanterior (PA) Most common. X-ray passes posterior to anterior with the plate anterior to the patient’s chest. Patient is upright & the scapula are rotated away from the lung fields
Anteroposterior (AP)
Commonly used for portable CXR’s. X-ray passes anterior to posterior. Heart size is magnified
Lateral
Allows visualization of lung bases & lung tissue behind heart
Normally left lung base as this is obscured by the heart
Oblique
Lordotic
Expiratory
Lateral Decubitus
Visible structures on CXR
Trachea Hila Lungs Diaphragm Heart Aortic Knuckle Ribs Scapulae Breasts Bowel gas
Important obscured/invisible structures on CXR
Sternum Oesophagus Spine Pleura Fissures Aorta
Preliminary checks
Who - have you got the right patient, check the hospital number and DoB
What – exactly was taken? Is it a CXR as a chest film will demonstrate aspects of the abdomen and MSK system (discuss abdominal x-ray),
When - how old is it? want less than 24 hours to be reflective, are there previous ones to compare to? In emergency less than an hour
Why – was the film taken? was it routine or emergency, was it post treatment or a line insertion
How – was the film taken? What position was the patient in? was it taken on the ward or in the department and then whether it is an AP or PA
Quality of CXR
- Overexposed - frequency of X-rays is too high or length of time the rays have been allowed to pass is too long = too black 2. Underexposed - frequency/intensity too low or not exposed for long enough time = too light
Systematic Approach
A – Alignment – rotated using the end of the clavicle to assess
B – Bones – Not just ribs; Are they all there, intact & in a normal position?
C – Cardiac/mediastinum – clear heart boarder? About 1/3 total chest diameter with 1/3 on the right and 2/3 on the left, evidence of shifting?
D – Diaphragms – Are they both visible? Cardiophrenic (relation to heart = rounded) and costophrenic (relation to lungs) angles clear?
E – Expansion – 10th rib posteriorly should bisect the R hemidiaphragm at mid-clavicular line, 8th rib anteriorly; R hemidiaphragm slightly higher
F – lung Fields – clear lung markings (black with white fluffyness)? Densities, lung edge, shifting of structure’s?, fluid level? With collapse & consolidation you will see increased opacity but with collapse you can see shifting of structures or crowding of lung markings
G – Gadgets (drips, drains & tubes) are they in, on or around the patient; obscuring aspects of CXR
Other imaging
CT (Computed Tomography)
MRI (Magnetic Resonance Imaging)
US of thorax
CTPA (Computed tomography pulmonary angiogram)
What is CT scan used for
Typically used for –
• Bone fractures - Shows bony/thoracic wall lesions v. clearly
• Cancer monitoring
• Identifying internal bleeding
• Differentiates between lung and pleural tissues
• V. useful to visualise mediastinum
Supplements CXR rather than replacing
Risks of CT scan
- Harm to unborn babies
- Very small dose of radiation
- Potential reaction to dyes
What is MRI used for
Typically used for – • Joints • Brain • Wrists & ankles • Breast • Heart • Blood vessels
Particularly good for:
- Mediastinal vascular problems such as aneurysms
- Pancoast tumour of lung
Risks of MRI
- Possible reactions to metals due to magnets
- Loud noises may cause hearing damage
- Increase in body temperature during long scans
- Claustrophobia
Preliminary checks prior to MRI
- Artificial joints, or implanted metal work
- Eye implants
- IUD
- Pacemaker/internal defibrillators
- Cochlear
- Heart valve
- Sternal wires
- Brain aneurysm clips
- Pregnant
- Obese
What is US of thorax used for
look for pleural effusions, abnormalities of the heart structure and function
What is CTPA used for
To help diagnose pulmonary embolism (PE)
