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NORMAL CHEST X RAY

How to obtain a good quality chest radiography (1)

3  aspects are very important for good quality:

• The penetrating power of the x-ray beam

(adjustment of x-ray tube voltage )• The x-ray tube current (milliampere)• The exposure time adjustment

How to obtain a good quality chest radiography (2)

• The adjustment of the x-ray tube voltage controls the contrast: the difference of density levels of the different organs and tissues in the thorax

• The x-ray tube current and the exposure time controls the intensity of x-ray beams

How to obtain a good quality chest radiography (3)

Adjustment of voltage

Exposure time

High voltage: a range of 100 /120 kV: optimal contrast between lungs and bones, and good visualisation of mediastinum and vessels

<0.05 seconds: decrease of motion artefact caused by the beating of the heart or respiratory movement

How to obtain a good quality chest radiography (4)

A long distance between the tube focus and the film improves the image clarityand decreases the geometric blur

How to obtain a good quality chest radiography (5)

Other criteria • Quality of the x-ray grid: the flat metallic plate with very

narrow lead trips close to the film: increase in the image clarity and reduction of the scattered radiation from the patient

• Good quality electrical power supply• Efficient and frequent maintenance of x-ray equipment• Quality of films and good conditions of storage• Good screen-film system• Good techniques for x-ray film processing (developing,

rinsing, fixing, washing and drying procedure). If possible automatic film processor.

What about digital X ray system?(1)(Direct Digitalised System)

composed with:• Electronic flat-panel X ray detector• High resolution grayscale diagnostic display• High performance computer

What about digital X ray system ?(2)

• Avantages:

-feasible imaging quality adjusted by computer processing

-easy and quick image processing

-X-ray film and its processing procedures in dark room no more needed.

-Lower dose radiation

- imaging transmission and intepretation via internet to referent radiologist is easily possible

• Disadvantages:

- Costly initial investment (61000 to 400000 $)

- Significant trainning in digital technology needed for the radiological technicians and costly running maintenance

Possible compromise with computed radiography (CR system)

• digital radiography using a Photo‐stimulable Phosphor plate (PSP, also called Imaging Plate, IP) enclosed in a cassette as a detector, instead of a film‐screen.

• The IP is then introduced into a CR Reader which reads the film and converts the recorded signal into a digital grey scale image

• Same avantages than digitalised system

• Lower cost than DR system, because can be used with the existing X ray equipment. Only a CR reader and CR cassette reader (with Imaging Plates) need to be

purchased..

Basic radiographic views:Postero-anterior view

Lateral view

Additional/supplementary view:

radiography in expiration

radiography in supine and lateral position

Back view (antero-posterior view)

Opacification of the oesaphagus

The thorax is composed of:• Bone (vertebrae, ribs, scapula…). The main component

is calcium, which absorbs the x-ray considerably: the bone image is very opaque (white on the radiography)

• Blood and soft tissue (heart, mediastinum, vessels). The absorption of x-rays is less complete than bones: the image is less opaque (light grey)

• Fat tissue. the absorption of x-rays is lower: the image is dark grey.

• Air (in lungs) which does not absorb the x-ray at all. The image of the lungs is black

calcium water oil Air

Picture of 4 different solutions on a chest x-ray film

calcium

Fluid / soft tissu

Fat

air

Dosage of x-rays type of

investigationEquivalent of chest x-ray

Equivalent of natural radiation

chest x-ray 1 3 days

TDM 10 -100 1 month-1year

NMR: no radiation

Chest x-ray: criteria for quality

• Deep inspiration• Adequate contrast / density• Good position of the patient• X-ray beam in postero-anterior view

(the patient is standing)

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Adequate inspiration if you can count9 posterior or 6 anterior parts of ribs over the diaphragm

Poor inspirationFalse opacity of the inferior lobes

Same patient with deep inspiration

false cardiomegalyclavicles are high and horizontal

The x-ray beam is antero posterior

Same patient with correct postero-anterior x-ray beam

incidence

AP versus PA view

The technician should specify the position of the patient if AP view

PA is the correct view

D1 D2

D1D2

The heart outline is bigger on D2

( bird’s-eye view of the patient)

Correct standing or sitting position for chest radiography

Standing or sitting position not always easy to obtain…

If the patient is in supine position (too ill to stand up), the cardiac outline and mediastinum is enlarged. The scapula may be on the lung field.The chest x-ray has poor quality for analysis

Patient in supine position Standing patient with postero-anterior X ray beam

The technician should specify the patient position if supine

Lighy filmUnder penetrationNo detail visiblein the mediastinum area.

Dark filmno detail visiblein the lung area

Correct densityand good contrast:

- Pulmonary vessels visible in the lungs, behind the diaphragmand behind the heart

- Para-aortic line visible

- Vertebra visible behind the mediastinum

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Conditions for adequate contrast / density

• Correct x-ray factor (Kv, Mas, exposure time)

• Good conditions of developing and good quality of processing chemicals

• Correct temperature of developer• correct quality of film

In case of digitalised or computerised system, imaging quality is adjusted by computer processing and the 3 last conditions are no more

needed.

Exact front view : the vertical line connecting the spinous process of thoracic vertebrae is in the middle of

the two sterno-claviculars joints.

exact PA view left anterior oblique position

Front View l a o r a o

D1 D2 D3

D3> D1>D2

Chest x-ray: to ensure top quality

• deep inspiration• adequate contrast / density• correct position of the patient

(exact front view)• x-ray beam in postero anterior

view (the patient is standing)

Process for analysis of the chest radiography: the  check list 

• Verification of name and date• Clinical history and findings• Verification of the factors for good quality• Assess

-thoracic wall and thoracic skeleton

- mediastinum

- each lung field, one after the other

Do not skip any item in the checklist !

Normal chest radiography

and some pitfalls…( trouble-shooting)

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Thoracic wallAnd skeleton

Thoracic wall

Sus and retro clavicular fieldExternal side of

Sternocleidomastoid muscle

thoracic wall

The clavicles are projected on the level

of the 3rd or 4th posterior part of ribs

1

3

4

Cervical ribs: minor malformation

trap picture: opacity of the superior part of right lung due to a hair braid

Be aware of foreign body or artefacts on the chest x-ray

Breast implant

The retro-clavicular fields are always difficult to analyse, because of bone superposition:

- Clavicles

- Anterior part of first rib

- Posterior part of third and fourth rib,

- Sterno-clavicular joint

There are 2 ways to correctly analyse the retro-clavicular fields:

• Always compare right and left• Ask for a chest x-ray with the patient’s

back against the film (AP view, lordotic position)

Always compare left and right

Right TB infiltrate

Patient with fever, cough, AFB sputum positive…

You have no CT scan. So use your eyes and compare right and left!

If any doubt, request AP/ lordotic chest X ray

Normal chest x-ray , front close to the film

Normal AP chest x-ray, back close to the film

Chest x-ray, front close to the filmChest x-ray, back close to the film

And clavicles out of the field by raising hands

Chest x-ray back close to the film

Thoracic wall

physiological blur of the inferior side of the

ribs

Rib view section

You must always « read » a chest x-ray with methodology:Example: for the chest wall, you must look at every rib, one after the other

(6th and 9th ribs missing on this CXR)

Chest wall

Top of the axillar hole

Big pectoral muscle

thoracic wall

Scapula

Congenital clavicles agenesy

What is wrong with this chest x-ray?

Thoracic wall

Breast silhouette

Be careful with false opacities in the inferior lobes, consequences of breast superposition.

Chest x-ray. Before and after right mastectomy

Thoracic wall

Diaphragm

The right side is usually higher than the

left side (3cm )

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Component elements of Mediatinum and hilus

RA RVLV

AO

PA

AO

RV

LA

LV

Front view

SVC

RA

AO

PA

LV

AO

RV LA

LV

Lateral view

RALA

LVRV

PA

SVC: superor vena cavaAO : aortic vesselPA: pulmonary arteryRA:Right ventricleLV left ventricleLA: left auricleRV: right venticle

Right pulmonary artery

Left pulmonary artery

L A

L V

RSPV

RIPV

LPSV

The pulmonary vena are not physiologiccally visible

• X ray beam crossing thorax and mediastinum meets in some places pleural thickness, producing images on the CXR like lines defining mediastinum lines…

Mediastinum lines

1. Sub clavicle arterial line

2. Posterior mediastinum line

3. Brachio cepahalic vena line

4. para-azygos line

5. Anterior mediastinum line

6. Descending aortic line

7. Right and left paravertébral line

8. Inferior veina cava line

9. para-œsophageal line

10. para-trachéal line

Mediastinum lines

6Too complicatedAnd not so usefull…

Three of them are really important.

Right paratracheal line

Para-aortic line

Aorto pulmonary line

Mediastinum enlargment due to fat tissu

Be aware of false enlargment of mediastinumif obesity, poor inspiration, oblique view or supine

position

Trap: false mediastinum enlargment in the case of this older woman with cyphoscoliosis,

in supine position

Component elements of lungs

On a normal chest x-ray, bronchi are not visible(opacification with iodin hydrosoluble solution)

…but pulmonary arteries are visible.

Right view

Small fissura

Big fissura

Left view

Left fissura

Right superior lobe pneumonia

minor fissura

Large oblique fissura posterior

part

minor fissura

Right inferior pneumonia

Large oblique fissura

Middle lobe pneumonia

Large fissura

minor fissura

Small pleural effusion

External segment of middle lobe pneumonia

External segment of middle lobe pneumonia

Left superior lobe pneumonia

Left inferior pneumonia

Left scissura

Normal lateral view

Lateral view

AO

PA

RV

LA

LV

Front view

SVC

RA

AO

PA

LV

AO

RV LA

LV

Lateral view

RALA

LVRV

PA

Heart and Mediastinum

vessels

AscendingAorta

Superior vena cava

Pulmonary arteria

Right ventricle

Descendingaorta

Heart and Mediastinumvessels

Left ventricle

Inferiorvena cava

Mediastinum

vessels

Aortic arch

mediastinum vessels

Descending aorta

Mediastinum vessels

Right pulmonary artery

Left pulmonary artery

Lateral view is very useful for diagnosis of mediastinal adenopathies

normal CXR

trachea

20 mm

Right superior lobe bronchus

Left superior lobe bronchus

Retro sternal clear space

Retro cardiac clear space

The «clear spaces»

The «clear spaces»

Retro tracheal space

enlargment of the clear spaces: Emphysema

Emphysema Normal lateral view

The retro sternal space is filled: thymoma

The retro sternal space is filled: thymoma. Normal view on the right

Diaphragm

Right diaphragm

Leftdiaphragm

Summary normal CXR

Normal frontal chest view

Aortic arch (AA)Descending aorta (DA)Proximal left pulmonary artery (PLPA)Left interlobar pulmonary artery (LPA)Aortopulmonary window (AW)Left main bronchus (LB)Left atrial appendage (LAA)Left ventricle (LV)Superior vena cava (SVC)Right paratracheal stripe (RPS)Azygos vein (AV)Aortic arch (AA)Right interlobar pulmonary artery (RIPA)Right atrium (RA)Trachea (T)Right diaphragm (RD)Left diaphragm (LD)

DA

LPA

RIPA

A W

LB

LV

SVC

RPTS

AV

RA

T

RD

LD

A A

SVCT

Normal lateral chest viewPosteriorly: vertebral bodies (V) and intervertebral disc spaces (*)Anteriorly: retrosternal clear space (RSCS)Trachea (T) Orifice of Right Upper Lobe bronchus (RUL) appears as circular lucency projecting over the continuation of the tracheal air column

Left pulmonary artery (LPA)Right pulmonary artery (RPA)Left auricle (LA)Left ventricle (LV)Right ventricle (RV)Aortic arch (AA)Postero costo phrenic angle (PCPA)Right diphragm (RD)Left diaphragm (LD)Inferior vena cava (IVC)Scapula (Sc)Retro cardiac clear space (RCCS)

T

V

*

RSCS

RUL

LPA

Sc

RPA

LA

LV

RV

AA

PCPARD

LD

IVC

RCCS