How to read Chest X-Rays with complete Atlas

by admin on May 30, 2009



General pattern of seeing a X-Ray is described below

Pneumonic to remember headings while describing x-ray to teacher or learning yourself.

PED In O Sonia BA-Tra Hi DiL

Part , exposure and development, inspiratory or expiratory film, orientation, soft tissue shadows, bony cage, trachea and mediastinum, hilar shadow, diaphragm and costophrenic angle, lung fields.

1.First of all describe the part of body in x-ray e.g (chest) look its view i.e A.P or P. A view. P.A view is taken to see lungs and heart while AP view is taken to see posterior lung cage, scapula. PA or AP means the direction from which X-Rays are made to project upon body.

2. See the exposure of film whether overexposed or underexposed.

3. Now describe whether film is taken in expiration or inspiration.

4. Find out the orientation of patient on x-ray : check out orientation of patient on x ray by measuring distances between lateral end of manubrium and medial end of clavicle in case of centrally oriented patient this distance will be equal, to take an x ray in centralized form ask patient to fold both of hands and both of shoulders must touch the plate.

if any of distance is less or shadow is overlapped, patient will have that orientation, that means if patient has removed his left shoulder than right side clavicle will be overlapped with sternum.

5. see soft tissue shadows- like lymphnodes, etc

6. see bony cage- see ribs, cartilages, extra ribs, fracture

7. look for trachea and mediastinum: heart will be explained seperately later in this section.

8. look for hilar shadows

9. Look for diaphragm: look whether diaphragm is flat or curved, its postion, normally lies at 5th -6th ribs

10. look for costophrenic angles, cardiophrenic angle: look whether these angles are obliterated or not, obliterated in case of pleural effusion. But in case of consolidation of lung these angles are not obliterated still you see radio opaque areas, however these consolidation are accompanied by small circular gas filled spot, indicating bronchovascular markings.

11. look for lung fields : looks for homogenous or heterogenous opacity, hypertranslucency, cavity, fibrosis, calcifications, millets etc.

Now look for these heading in details below

  1. Part and View: part i.e chest, view i.e A.P or P.A view, P.A view is taken to see the lung and heart, while AP view is taken to see posterior lung cage, scapula.

Inspiration is done to expand the lung fields, as diaphragm descends down, the principle behind that is that which ever part is closed to X- ray plate is clearly viewed.

PA view is done to minimize bony markings like spine, bony cage, posterior end of ribs are hard so clearly visible in chest x-ray, however anterior part of ribs is fiague, so its shadow becomes light.

  1. Exposure and Development:

Normal Exposure: shadow of vertebral column is faintly visible, intervertebral spaces not clearly visible, and shadow of trachea is normally visible upto the level of clavicle as a translucent shadow.

Over Exposure: vertebral column along with intervertebral spaces will be clearly visible, posterior part that is spine will be clearly visible.

Translucency of trachea is lowered down the level of clavicle may be upto the bifurcation of trachea.

Translucency of the lung field will increase and density and opacity of heart will reduce and heart becomes more central and narrow.

Under Exposed: faint shadow of vertebral column will not be visible at all, translucency of trachea will not be clearly visible, opacity of heart will increase.

  1. Orientation Of the Patient:

What is centrally oriented x – ray?

If the x ray is taken when patient is having hand folded and both of shoulders are touching the plate.

In this case distance between medial end of clavicle and lateral border of vertebrae column will be almost equal in x ray.

Right anterior orientation: only right shoulder touching the plate and left is away, in both left and right orientation there will be overlapping of medial end of clavicle and lateral border of vertebrae.

What is importance of orientation?

In right orientation, trachea will be shifted to left, in x ray, heart will appear to be shifted left or it will show cardiomegaly.

In left orientation heart will appear central, and aortic knuckle, pulmonary conus not visible, tubular appearance of heart in left orientation.

4. Soft tissue shadows:

Abnormalities : abnormality of lymph nodes, calcified (appear dense-more dense than bone) and matted.

Subcutaneous emphysema- vertical linear multiple translucent band like shadow.

5. Bony Cage: cartilages donot have any shadow, from the age of 25 years, cartilages start ossifying, so densly visible.

How to detect cardiomegaly in X ray?

First divide heart shadow in 2 parts from centre by vertical line, now from that line see greatest curves on both left and right side, means there will be to parallel line touching that vertical line, say them (a, b), and say x= a+b

Now measure the transverse diameter of thorax by joining the 2 costophrenic angles and say it to be (y).

If x> y/2 than it is cardiomegaly.

6. Hilar shadows: centre of hilum is place from where vessels originate, it is formed by arteries and viens with small contribution from the walls of the major airways.

The most important vessel in hilum is Basal artery or descending branch of pulmonary artery. On right side it is clearly visible (basal art) width is about 7-19mm when visible on left side it is about 1-2 mm less than right side, generally not visible on left side due to overlapping by heart.

The centre of right hilum is at the level of 3 rd rib anteriorly and 6th rib in the axilla- in a normal inspiratory film.

Ring like shadows around hilum is end of bronchus and solid shadows are blood vessels.

7. Diaphragm and CostophernicAngles: centre of right dome of diaphragm is 5 to 6.5 ant rib in normal insp. Film. Centre of left dome of a diameter is .5 to 2.5 lower than the right.

The curvature of the dome of diaphragm : drop a perpendicular from centre to line coming from angles it is around 1 to 1.5 cm

8. Lung Fields: any lesion should not be defined in reference to lobes but as ZONES.

Upper zone– from 2nd costal cartilage to axilla

Middle zone– between 2nd and 4th costal cartilage.

Lower zone- below 4th costal cartilage.

Horizontal fissure is normally visible in 70% of individual .

Transverse fissure in PA view.

Oblique fissure is not visible in PA view

The level of horizontal fissure in normal inspiratory film is at the level of right hilum, 10 degree inclination or depression is accepted as normal.

Upper zone vessels are less prominent but lower zone vessels are more prominent due to gravitational effects.

In order to look sample X-ray of points described above you need to see x-rays which you can see below in complete atlas…

Complete Atlas of Chest X-Rays by Dr. A. J Chandrasekhar

Some of our readers asked us to tell how to count ribs on chest x ray so your answer is

Ribs counting is done from backward to forward just see the picture which is being attatched red colour indicates the rib which is being counted just compare with other half side of x ray you will see light shadows which are being counted, arrow indicates the direction of ribs counting.

just see the picture below



Also visit self-tutorial for residents and medical students to learn to interpret chest radiographs with confidence at

increase your knowledge with this video presentation of X-Rays

Good videos collection from youtube on understanding and reading chest x-rays

For Further Reading :


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