Chest X-rays Flashcards
What are the different parts of the chest?
(5)
Skeletal
Cartilaginous structures
Respiratory
Digestive
Circulatory
What makes up the skeletal part of the chest?
(5)
Ribs
Spine
Scapulae
Clavicles
Sternum
Proximal humerus
What makes up the cartilaginous structures of the chest?
(2)
Xiphoid process
Costal cartilage
What makes up the digestive part of the chest?
Oesophagus
What makes up the circulatory part of the chest?
(4)
Heart
Major blood vessels
Arterial
Venous
What makes up the respiratory part of the chest?
(3)
Lungs
Airways
Diaphragm
What is the diaphragm made of?
Muscle
How many lobes does the right lung have?
3
How many lobes does the left lobe have?
2
Why does the left lung only have 2 lobes?
Because the heart is behind it
What side of the body is the heart on?
Left side
Why is a chest x-ray important?
It shows all the anatomy in a 2D image
What do we x-ray the chest for?
(5)
Mainly to demonstrate the lung field
Clinical indications, e.g. lung diseases
Cardiac/heart assessments
Airway assessments
Bony assessments
Why are chest x-rays good for primary treatment?
(3)
Because they’re cheaper than other, e.g. CT
They’re done quickly
They’re easily accessible to do
What does CXR stand for?
Chest x-ray
What are the 2 categories of the projections of CXR?
(2)
Standard
Non-standard
What are the standard projections of CXR?
(2)
PA (main projection)
AP
What are the non-standard projections for CXR?
(2)
Lateral
Oblique
What CXR view is the gold standard?
PA
How do we know if an CXR used a PA view?
There’ll be no annotation on the image- annotations are only used when an alternative projection has been used, e.g. AP, supine, etc
Why is PA used on a CXR?
(4)
The heart is an anterior structure inside the chest cavity, so if AP was used, it’d be close to the detector- so PA reduces the magnification of the heart
It prevents breast tissue compression
Less dose is given to the thyroid gland. The thyroid gland is radio-sensitive, so it protects it
It improves image quality and provides a sharper image
Is the image sharper when it’s closer or further away from the detector?
Closer
How do we position a patient for a CXR?
(9)
Patient stood upright
Chest close to the detector
Median saggital plane at right angles to detector (patient is stood straight up)
Shoulders shrugged forwards
Dorsum of hands on the back of the hips
Elbows partially flexed and forwards
Head and neck straight and forward
Breathe in but leave shoulders relaxed
Exposure patient at deepest breath in- remember to tell them to breathe again!
Why do the shoulders need to be shrugged forwards during a CXR?
To move the scapula out of the way of the lung fields
What is the SID of an adult PA CXR?
Why?
180cm
To help reduce the magnification of the heart
Is a grid/bucky used in an adult PA CXR?
Yes
Which type of projection does an adult PA CXR use?
Why?
Lateral
Because it’s not over the heart
What is the detector size of an adult PA CXR?
Why?
43cm x 35cm
A large detector is needed because the chest is a large body part
What is the centering point for an adult PA CXR?
T7 (the T7 is in line with the bottom of the scapula)
What is the collimation for an adult PA CXR?
From the shoulders to just above the lower costal margins (lower ribs) (shoulders to diaphragm)
Is the focal spot for an adult PA CXR small or large?
Large
What are the exposure factors for an adult PA CXR?
120 kV
1.6 mAs
How does paediatric CXR differ from adult CXR?
Paediatric CXR requires adjustment based on their age and size, using your knowledge and judgement.
How do we know if the exposure of the chest is good?
Can you see the vertebrae all the way through the heart? If you can, the exposure is good
How do we make sure that the patient took a deep enough breath?
(2)
Look at the image
If you can count about 8-10 ribs in the image, then they took a deep enough breath
Does this CXR have good exposure?
Why?
Yes
Because we can see the vertebrae through the heart
How can we assess a CXR for good patient position?
(3)
We can see the medial ends of the clavicles
The scapula is out of the way of the lung fields
The vertebra can be seen behind the heart shadow
Fill this in:
What’s wrong with the centering point of this image?
The centering point isn’t at T7
What is the cardiothoracic ratio?
The ratio of the greatest transverse dimension of the hart to the greatest transverse dimension of the chest cavity (how big the heart is in relation to how big the chest is)
What is the normal cardiothoracic ratio?
0.42-0.50
How do we know is the cardiothoracic ratio is normal?
If the heart is less than half of the chest, it’s normal
Why is the cardiothoracic ratio important?
It detects enlargement of the heart. Further cardiac investigation are normally needed for a higher ratio than 0.42-0.50
What a cardiomegaly?
An enlarged heart
Is this a normal heart?
Why?
Yes
Because the heart is less than half of the chest cavity
Is this a normal heart?
Why?
No
Because the heart is bigger than 1/2 of the chest cavity
How do we position a patient for a AP CXR?
(8)
AP is down when PA is not possible
Patient sat upright or supine (lying on their back- put the detector under their trolley) and as straight as possible
Median saggital plane at right angles to the detector (straight up)
Patient’s back against the detector (put detector behind patient)
Scapula as lateral as possible- shrug forwards
Chin up
Practice a breath in and holding
X-ray beam perpendicular (right angles) to the detector
What’s the SID for an erect AP CXR?
180cm
What’s the SID for a supine AP CXR?
100cm
Fill this in:
How do we locate where the mid sternum is?
It’s at T7 but at the front
How can we assess an AP CXR image?
(2)
Do the 10 point check
Use AP annotation on the image
What is an example of an emergency situation when a CXR has to be done?
Pneumothorax (collapsed lung)- air leaks into the pleural space between the lung and chest wall
What is the pleura?
The lining of the lungs that sits between the ribs and lung field
What happens if air gets into the pleura?
The air pushes the lung downwards (the lung collapses)
What has to happen to get air out of the pleura?
The chest has to be drained to re-inflate the lung
What happens in tension pneumothorax?
(4)
After trauma, e.g. the ribs break, there’s a puncture of the pleural space.
This can displace the heart and airways.
Air enters the pleural cavity with no way to escape, causing the lung to collapse.
The heart, blood vessels and airways are displaced
What pathology is this?
How do you know?
Tension pneumothorax
Because the heart isn’t in the middle of the chest cavity
