Terminology in Chest XRays

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Terminology in Chest XRays

• PA view- chest close to xray plate
• xray tube 6 feet from patient
• Pt erect
• AP view- back close to plate
• xray tube 3 feet from pt
• pt supine
• PA sharper
• less magnified
• Both generally taken in full inspiration
• Oblique- taken with pt standing obliquely. Right
  oblique is with right chest against the plate
• Lateral decubitus side of supine pt on the
  plate with xray tube horizontal
• Apical Lordotic- xray tube angled at 45
• Sternal rib views

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HOW TO READ A CHEST X-RAY

• Switch off all unnecessary lights.
• 1.Identify patient name,age,sex,hosp . Date of
  xray and side marker (R or L)?
• 2.. Check the adequacy and tech quality of film
• Exposure- mid thoracic intervertebral disc should
  be clearly visible or a finger held behind the
  black part of the film should be just visible.
  Underexposed film is pale- lung appears
  consolidated/pulm edema. Overexposed film is
  black suggest emphysema
• Position Supine or erect. PA,APor lat
• Rotation (centered)- Spinous process of upper
  thoracic vertebrae should be central Medial
  ends of clavicles must be equidistant from the
  central spinous process
• Lung volume (Degree of inspiration)- Right
  hemidiaphragm should reach the anterior end of
  6th / 7th rib or the 9th / 10th rib posteriorly
  on full inspiration
• gt 6th rib in expiration indicates
  hyperinflation( emphysema)?
• lt 5th rib indicates underinflation (
  crying infant)?
• Film taken in expiration may simulate
  disease cardiomegaly, pulmonary congestion
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(CONTD.)?

• 3. Check the extrathoracic soft tissue-
• Start at the top with the supraclavicular areas,
  neck, shoulder,- look for subcutaneous
  emphysema., calcified glands Continue down each
  side of the chest Assess breast shadows. Finally
  check under the diaphragm for air
• 4.. Check the bony cage Ribs,clavicles,
  scapulae,shoulder jts,thoracic spine
• 5..Check for medical equipment
• like ET tube, CVP line -Tip of ET tube should be
  about 2 cm from carina
• 6. F. Check the superior mediastinum for widening
  or abnormal masses and identify the trachea
• thymus causes widening upto 2yrs
• 7. Check the heart- its positioned with 1/3 of
  its diameter to the right and 2/3 to the left of
  the spinous process. A low diaphragm will cause a
  right shift and a high d a left shift. The
  hearts full dia should be less than ½ of the
  internal thoracic dia at its widest point (
  cardiothoracic ratio)?
• 8.Check the diaphragms, Cp Cp angles.
• R dia 3 cm higher than left. Outline should
  be smooth with highest point medial to the
  midline of the hemithorax
• Gastric bubble seen under L diaphragm
• 9.. Hilum
• Hilar shadows- made up of pulm art and large
  veins. Left hilum normally 2 cm higher than right
• 10.Lungs
• Lung pattern- all the markings in a normal lung
  are vascular. They disappear 2 cm or less from
  the lung margin
• Lung zones- Upper apex to 2nd costal
  cartilage,
• Middle -2-4 cartilage
• lower below 4th cartilage

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Features of Anatomy seen on PA VIEW
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LATERAL VIEW
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Normal PA view
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PA VIEW

• Each lobe is covered by visceral pleura.The
  visceral pleura bordering adjacent surfaces of 2
  lobes form the septa,which separates the lobes.
• The space between 2 adjacent septae is called the
  interlobar fissure- a fissure is a narrow space
  a septa is a divider. The 2 terms are used
  interchangeably
• Right lung has 3 lobe-RUL,RML,RLL separated by
  septa or fissures
• R major fissure runs obliquely downwards from 5th
  thoracic vertebra to the diapraghm to a point
  just behind the ant cp angle.
• Not normally seen in PA view as it is not
  parallel to the x-ray beam
• The Right minor fissure intersects the lateral
  chest wall at the level of anterior portion of
  4th rib(/_2)?
• RUL made up of apical ,anterior posterior
  bronchopulmonary segments
• RML made up of lateral and medial segments
• RLL made of superior, medial basal, ant basal,
  lateral basal and post basal

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PA view

• Left lung is made of
• LUL LLL
• The LUL is made up of apicoposterior and anterior
  segments
• The lower or lingular division of the LUL is made
  up of sup inf seg
• The LLL is made up of the sup, medial basal, ant
  basal, lat basal and postbasal

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NORMAL CXR

• Trachea is central
• Dome of R diapraghm is at the level of 6th rib
• L hemidiapraghm is 3cm lower than the R
• Heart size is lt 50 of the thoracic diameter. 2/3
  of the heart lies to the L and 1/3 to the R of
  the spine
• Cardiac apex gastric bubble are to the left
• Horizontal fissure lies at the level of the 4th
  costal cartilage.
• Mediastinum is lt 25 of the chest width

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HEART BORDERS
1.Aortic knuckle 2.Pulm. Artery 3.L.atrial
appendage 4.L ventricle 5.R atrium 6.trachea
7.R dome of diaphragm 8.gas bubble in stomach
9.horizontal fissure
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CT ratio

• MRDmaximum R
  diameter
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  MLD maximum L diameter.
• 
  ID internal diameter

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USEFUL RULES SIGNS

• The Silhouette Sign
• Contiguous objects of the same density are not
  seen separately
• The 4 basic densities are air, fat, water and
  metal
• The silhouette sign is seen when a border of the
  heart, aorta, or diaphragm is obliterated
• The heart and ascending aorta are anterior
  structure

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Causes of confluent opacification of a hemithorax

• There are four main causes of confluent
  opacification of a hemithorax -
• consolidation (that is, material within the
  air-spaces and
• pleural effusion - that is, material within the
  pleural space, which could be serous fluid,
  blood, or pus.
• Complete collapse of one lung with the
  mediastinum shifting over the the abnormal side
  can also cause a "white out" on the abnormal
  side.
• Finally, after a pneumonectomy the mediastinum
  shifts to the empty hemithorax and the residual
  pleural space fills with fluid and fibrotic
  material leaving the patient with a complete
  "white out" on the side that has been operated
  on. Consolidation and pleural effusion are the
  two most common, and it can be difficult to
  distinguish between them - of course, they can
  coexist.

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Collapse-RML

• Silhouette sign

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RML COLLAPSE-LATERAL
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RML collapse..graphic
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Collapse

• Collapse of a lobe is caused by proximal
  obstruction
• for example, by a neoplasm, mucus plug, such as
  in a postoperative patient, or foreign body, such
  as in a child.

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AIR BRONCHOGRAM

• The bronchi are not normally seen on the xray as
  they are thin walled, contain air and are
  surrounded by air in the alveoli
• Visualisation of air in the bronchi is known as
  an air bronchogram
• Air- filled bronchi can be seen if surrounded by
  diseased lung which contains no air (eg
  pneumonia, hyaline membrane disease,RDS)?

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RDS
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SAIL SIGN

• The normal thymus lies in the sup, ant
  mediastinum. In the infant , it may appear to
  widen the mediastinum in a PA view, being largest
  at about 2 years of age
• The inferior border of the R thymic lobe is a
  straight line. When it rests on the R horizontal
  fissure it produces an appearance referred to as
  the sail sign

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sail sign
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RUL collapse..graphic
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LLL COLLAPSE
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LLL COLLAPSE
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Medial segment of R middle lobe CONSOLIDATION
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RMLL PNEUMONIA
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TB HILAR ADENOPATHY
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APICAL TB
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MILIARY TB
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Pl. effusion R
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