ICL 3.4: Normal Pulmonary Radiology Flashcards
what are the indications to get a CXR?
SUBJECTIVE
1. cough
- SOB / dyspnea
- pleuritic chest pain
- hemptoptysis (bloody cough)
OBJECTIVE
1. rales
- ronchi
- wheezing
- dullness to percussion (hyperresonance)
- focal chest wall tenderness
- dilated neck veins, neck swelling
what are the 2 positions you can take a CXR in?
PA = posterior-anterior –> back to front x-rays
AP = anterior-posterior –> front to back x-rays
how do x-rays work on the chemistry level?
x-rays strike and electrode and positive and negative charges are separated
positive charges move towards the capacitor that stores them and they get read by a computer
what position is used to image the heart? why?
AP view
heart is anteriorly located and when you take an AP view, the heart is magnified
the farther away your x-ray source is from the patient the greater the magnification of structures; you often have to place the x-ray source farther from a patient for an AP view
in general, it’s less accurate to call cardiomegaly on an AP view because it’s being magnified; however if the heart is normal on the AP view then it’s definitely normal
how can you tell if it’s an AP view or PA?
if the edge of the scapula is lateral near the lateral ribs it’s PA view
if the scapula is projecting more medially, it’s probably an AP view
what are the 3 qualities of a good CXR?
- position = you don’t want any rotation or else it’ll change the anatomy; it need to be a pure AP or PA view
- inspiration = will allow you look at an air filled lung that isn’t compacted
- penetration = need the perfect number of x-rays going through the patient; not too many or too little
why does rotation of the patients body matter when taking an CXR?
- it changes the size and shape of the mediastinal structures
- some areas of the lung become harder to see if it’s rotated
how can you tell if a CXR is not rotated?
look at the medial ends of the clavicle and make sure the spinous processes of the vertebrae are equal distance from each one; aka they’re centered
when someone’s rotated, the long part of the ribs will also look longer
why does inspiration matter when taking an CXR?
good inspiration is important because with poor inspiration the lower lobes are hard to see and pulmonary vessels are crowded together and mimic the appearance of atelectasis or pneumonia
how can you tell if someone is adequately inspiriting in a CXR?
count the posterior ribs and the diaphragm should be between the 9th and 11th rib
what factors influence the penetration of the x-ray beam?
- energy of the x-ray beam = how many photons are you putting through the patient
- exposure time = how long are you letting the energy go through the patient
- source to detector distance
- patient size = the bigger the patient, the more likely there aren’t enough x-rays going through them
if the CXR is under-penetrated, the CXR will be very white and if it’s over-penetrated CXR it will look really black where there isn’t a lot of tissue
what are the different colors of a CXR each correspond to?
black = air
darker grey = fat
lighter grey = soft tissue
off white = bone
bright white = metal
what is the systematic approach to review a CXR?
- airway = trachea
- bones and soft tissue
- cardiac and mediastinal contours
- diaphragm
- pleural contours
- lung parenchyma
- lines, tubes, devices, surgery
what part of the airway can you see on a CXR?
- trachea
- left and right main bronchus
if you can see any further down into the respiratory system you’ve got a problem…
what bones and soft tissue can you see on a CXR?
- clavicle
- ribs
- vertebral body
- sternum
