Chest Xray Interpretation Flashcards
How does an Xray work
A beam of ionizing radiation diverges from its source and travels in a straight line passing through the anatomical structure and terminating on the detector.
what does the result of an Xray depend on
the DENSITY of the structures
Depending on the density of the anatomical structure the beam will be absorbed in a variation of degree or be scattered (in the case of metal)
describe the density of bone, air, soft tissue, fat and metal
the order of these in least density to most density is shown below. therefore the material with the least density (air) appears black, whereas the most density (metal) appears white
What causes structures to be magnified? why is this important
structures that the beam hits first (the structures closest to the beam) will be magnified since they are farther from the detector.
this is what causes the difference in Posterior-Anterior CXR and Anterior-Posterior CXR
what is the main difference in PA CXR and AP CXR
in AP CXR the heart will be magnified since it is closer to the source of the beam and father from the detector. This makes the heart appear larger
what are common reasons that CXR are ordered
- Persistent cough
- Shortness of breath
- Wheezing
- Chest pain/injury
- Fever (unexplained)
- Monitoring of disease resolution or progression
- Lymphadenopathy (unexplained)
what is the patient preparation for CXR
- remove clothes, undergarments, all metal
- LMP/pregnancy test (females only, usually if its been greater than 3-4 weeks since LMP get pregnancy test)
what are the possible views for a CXR? What is contained in the standard 2 view CXR?
Posterior-Anterior (PA)
Lateral
Lateral Decubitus
Expiratory
Lordotic
Anterior-Posterior (AP)
standard 2 view = PA and lateral
what is the PA view
performed with the chest against the detector
what is the lateral view
performed with the left side of the body against the detector
when is lateral decubitus CXR view indicated
- pleural effusions vs consolidation
- loculated effusions vs free pleural fluid
- evaluate for small pneumothorax
what is the positioning for the lateral decubitus view for a suspected pleural effusion
the side of interest should be down because fluid travels down
what is the positioning for the lateral decubitus view for a suspected pneumothorax
the side of interest should be up because air travels up
A 56-year-old male presents with complaints of chest pain and shortness of breath that was sudden in onset 1 hour ago. Initial PA CXR shows is suspicious for a small right pneumothorax vs artifact.
What would be the most appropriate follow up x-ray you would want to order?
Left lateral decubitus position
when do we order an expiratory CXR view
- air trapping d/t a foreign body (food stuck in lung)
- small pneumothoraces
what is the abnormal side of this expiratory CXR view
the right side because it is bigger. this means the right side is not able to exhale as much air which indicates a foreign body in the bronchus.
what is a lordotic view
using a different angle to further evaluate structures that are superimposed and inhibiting view
when is a lordotic view indicated
to evaluate lung apices that appear obscured on the PA/AP.
(example: when you see something that may be an abnormality but you are unsure if it is a part of the superimpossed bone over the lung, or if it is a problem with the lung itself so you order a lordodic view)
when would you order an AP view CXR
for patients who cannot stand erect. this view is taken supine or sitting.
what is the differences between PA view and AP view
Why does the anatomy appear in the same position despite the way the image was captured in PA vs AP?
they rotate the image so that it always appears as if the patient is looking at you. In every xray image you see, it will be as if the patient is facing you
A 42-year-old female presents with complaints of cough and shortness of breath that was has progressively worsened over the last week. Initial x-ray shows a blunted costophrenic angle on the left. The radiologist is concerned about a pleural effusion.
What would be the most appropriate follow up x-ray you would want to order?
Order a CXR with Left lateral decubitus view.
gravity should pull the fluid down to confirm pleural effusion.
what are the 4 systematic steps to interpreting a CXR
- ensure basic information ( ID the patient and make sure its the right patient!)
- ensure its an adequate quality CXR.
- Interpret the CXR
- Always compare the CXR to past x rays.
what are things to look for to ensure a CXR is of good quality
- penetration
- Artifact
- Inclusion
- Rotation