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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