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
what cardiac structures can you see on a CXR?
- ascending aorta
- aortic arch
- right and left pulmonary artery
- right and left atrium
- aortopulmonary window
- left ventricle
- descending aorta
right ventricle is against the diaphragm inferiorly!
what do you see on a CXR if there’s a problem with the aortopulmonary window?
it’s an opening between the aortic arch and left pulmonary artery and it’s a black hole on a CXR
there’s a lot of lymph nodes in that space so if you have lymphadenopathy the space won’t be black anymore because the lymph nodes are inflamed – it also contains the recurrent laryngeal nerve
so if the lymph nodes are enlarged the aortopulmonary window will become a convex contour
where do pleural effusions usually collect?
the costophrenic angle
it’s the sliver in between the pleural and the diaphragm
what is the gastric bubble?
a black spot on the left hemi-draphgram that is totally normal
it is NOT seen on the right
what is an endotracheal tube supposed to show up on a CXR?
ETT should be midway between the thoracic inlet and the carina
aka draw a horizontal line between the medial clavicles and another horizontal line at the level of the carina; the endotracheal tube should be in the middle of the two of those roughly 4 cm above the carina
what is an NG tube supposed to show up on a CXR?
NG tube tip should be below the diaphragm near the gastric bubble on the left side
it should NOT coil anywhere in the mediastinum; if it curls above the diaphragm it could be a hiatal hernia where the stomach has herniated above the diaphragm
make sure it doesn’t go into the bronchus
where are central lines supposed to be on a CXR?
you want them to terminate in the SVC
so find the carina and the tip of your central line should be no more than 2.5 vertebral bodies below the carina
what should you be worried about when placing a central line?
the lung can be punctured so you have to look for pneumothorax
also be careful about arterial placement! it should be in the superior vena cava, not the aorta!
what do you look for in a CXR of someone who got a pacemaker placed?
- pneumothorax
- look for ventricular lead coiled in atrium
- look for broken wires
- look for a lead outside a cardiac chamber; perforations are usually ventricular
what is a pneumothorax?
a tear of the parietal pleura
high yield CXRs
go rewatch the lecture
