Chest X ray Flashcards
definition and background
they have been used for over a century, they are electromagnetic waves, a CXR is a procedure by the electromagnetic beams passing through the thorax and exposing photographic plate. usually taken whilst on deep breath in
what is the X ray image based on
it is based on the anatomy of the patient blocking the transmission by varying degrees, which results in an image caused by the degree of exposure of the plate, the plate turns black (from grey_ as the X-ray strikes it, each body tissue has a different radio-density
radio density
less dense tissue such as air or air filled structures are referred to as radiolucent (black- lets ray through), more dense structures are referred to as radiopaque- white
4 basic radio-density- gas=black-lungs, fat- grey-lipid tissue, soft tissue- grey- heart, bone ormetal- white- ribs or sternum
types- AP, PA
PA- most common- x ray passes posterior to anterior with the plate anterior to the patients chest. patient is upright and the scapula are rotated away from the lung field
AP= commonly used for portable CXR’s. X=ray passes A to P. heart size is magnified done when patient isn’t well- cant move
types- lateral, lordotic and oblique
lateral- allows visualization of lung bases and lung tissue behind heart- taken laterally
lordotic- provides better view of the lung apex, lingula and right middle lobes
oblique- is used to project abnormalities away from overlying structures
types- expiratory, lateral decubitus
expiratory- is used to demonstrate a small pneumothorax or unilateral airway obstruction, lateral decubitus- is used to identify presence of free pleural fluid or to common an air-fluid level- lay on bed and on side
quality- over-exposed
the number of rays (frequency) is too high- higher effect on plate-black, or the length of time the rays have passed through somebody is too long- more time to hit plate- black
quality- under-exposed
not enough intensity, not exposed patient long enough- plate doesn’t change colour
why don’t you want rotation whilst the X-ray is being taken
more likely to occur with AP- more mobile, as structures don’t appear as they should be, to see this look at the clavicle- look to see if the ends of the clavicle are qual distances from SP
what things can you see on X Ray
trachea, the hila, lungs, diaphragm, heaty, aortic notch, ribs scapula, breast tissue, stomach
invisible structures on X-Ray
sternum, oesophagus, aorta, pleura, fissure, detail of spine- lot of dense structures all in one place- similar in radiodensity
interpretations
who- is the patient, check the hospital number/DOB, what- has been X-ray ahs been taken, when- when was it taken, was it post op? and how has it changed, why- was the film taken? was it routine or change in clinical state?
how- position patient in? ward or critical care? AP or PA? how well?- over/under exposed
a systematic approach- A, B, and C
Alignment- is it straight film? look at the proximal end of clavicle and SP?
B- bones- are they all there, intact and normal?
C-Cardiac/mediastinum- is there a clear heart border? is it a normal size (1/3), anything to note in the mediastinum> is there evidence of shifting structures?
a systematic approach- D and E
D- diaphragm- are both hemidiaphragms clearly visible? what about angels, cardiophrenic, costophrenic? right should be higher
E- expansion- how well expanded is the chest? the 10th rib posteriorly should bisect the right hemidiaphragms at mid clavicular line and its 6th rib anteriorly
a systematic approach- F and G
fields- are lung fields clear? are there any areas where the density either increases or decreases? can you see lung edge? fluid level?
G-gadgets- drips, drains, tubes, lines, and other gadgets are visible? are they in, on or around the patient?
common abnormalities
consolidations, atelectasis/collapse, pleural effusion, pneumothorax, pulmonary oedema, fracture
what is an consolidation
a condition in which the lung tissues becomes firm and solid rather than elastic and air-filled because it has accumulated fluids and tissue debris, main causes- pneumonia, chest infection, lung contusion following trauma. Space filled with inflammatory exudate
clinical features on CXR and auscultation- consolidation
CXR- white/grey shadow, no loss loss of volume
auscultation- increased breathing sound/ bronchial breathing, or decreased breath sounds, with or without crackles or wheezes (dependant on stage of consolidation)
atelectasis/ collapse
an airless state of the lung tissue which may involve part of the lung or whole lung. main causes- shallow breathing obstruction, absorption of trapped gas, surfactant depletion, compression from external pressure such as pleura disorder, abdominal or cardiothoracic surgery
clinical features on CXR and auscultation- atelectasis/ collapse
CXR- white/grey shadow, with loss of volume and shifting of structures (only visible on CXR if significant collapse) a total collapse may displace the mediastinum towards the affected side and other structures
auscultation- quite breath sounds,if occluded bronchus or bronchial breath sound if patient bronchus, fine end inspiratory crackles with smaller atelectasis
pleural effusion
excess fluid in pleural cavity (usually less than 20ml of fluid present in normal lung), main causes- disturbed osmotic/hydrostatic pressure in the plasma, changes in membrane permeability, malignancy, heart/ kidney or liver failure, abdominal or cardiothoracic surgery, pneumonia, T.B.
clinical features on CXR and auscultation- pleural effusion
CXR- fluid is white on CXR a small amount of fluid (at least 500ml) will result in loss of costophrenic angle. as the amount increases a fluid line may be visible with tracking up the pleura laterally. large amounts of fluid will distance (push) the mediastinum towards the non affected side
auscultation- quite breath sounds over the pleural effusion with bronchial breathing just above the top of fluid level
pneumothorax
air in pleural space secondary to a rupture in either pleural layer. lung squashed towards the hilum in proportion to the amount of pleural air. main cause- fast growth particularly in young males, blebs- smokers, trauma such as- rib fractures/surgery/ insertion of a line, barotrauma with higher pressure positive pressure devices, bullae in emphysema. Can tear within or can tear under tension and stab (entry and exit point)
clinical features on CXR and auscultation- pneumothorax
CXR- air in pleural space is very black as there are no lung markings. with significant pneumothorax the lung is squashed and appears as a white density towards the hilum, the mediastinum may be displaced (pushed) to the non-affected side
auscultation- quit over the area of pneumothorax
pulmonary oedema
extravascular water in the lungs- interstitial and alveoli, main cause- fluid overload, back pressure from failing left heart, osmotic or hydrostatic pressure changes, increased capillary permeability. Happens when capillaries have higher permeability, pink frothy sputum=sign of pulmonary oedema
clinical features on CXR and auscultation- pulmonary oedema
CXR- bilateral fleecy opacities spreading from the hila known as batwing or butterfly shaddows, depending on the cause there may be enlarged heart
auscultation- crackles that are more evident in dependent regions, sometimes fine/ bubbly noises
CT
computed enhancement of a large series of 2D x ray images, taken around a single axis of rotation, produces cross sectional views, supplements Xray, typically used for= bone fractures, cancer monitoring, identifying internal bleeding, differentiates between lung and pleural tissue
CT risks
harm to unborn babies, very small dose of radiation, potential reaction to dyes
MRI
MRI uses the magnetic properties of the hydrogen atom to produce clear images of tissues, a constant magnetic field and radio frequencies bounce off the fate and water molecules in your body and the radio waves are transmitted to a receiver in the machine which is translated to image
typical use of MRI
joints, brain, wrists and ankles, breast, heart, blood vessels
risks include
possible reaction to metals due to magnets, loud noises may cause hearing damage, increase in body temp, claustrophobia
prior to MRI you need to know if patient has
artificial joints, eye implants, IUD, pacemaker, cochlear, heart valve, sternal wires, brain aneurysm clips, pregnant, obese
benefits of scanning
both CT and MRI give internal view, CT is quicker, CT is cheaper, CT is better at providing general images of tissues, organs and skeletal system, MRI is thought to be more superior in regards to detail of image
Ultrasound
a chest US is non-ivasive diagnostic procedure that produces images used to assess the organs and the structures within the chest, such as lungs/mediastinum and pleural space
a gel is placed on the transducer head and skin to allow smooth movement and eliminate air between the skin and transducer,
benefits and use of US
it allows a quick visualisation of the chest organs and structures, may also be used to assess blood flow to chest organ, it is used to assess for any excess fluid in the pleural space or other areas of the chest and can determine which type of fluid is present
CTPA
it is a diagnostic test that uses CT to obtain an image of the PA, used to diagnose pulmonary embolism, it uses a specialist contrast dye injected into the body’s blood vessels via the groin or arm, the dye shows up on scan, shows narrowing or obstructions in the blood vessels
