basics of chest xray

Request form Name, age, date , sex, clinical info
Technical Adequate inspiration
centering , rotation , side markers ,
exposure/penetration , collimation
Trachea Position , outline
Heart and mediastinum Size, shape , displacement
Diaphragms Outline , shape , relative position
Pleural spaces Position of horizontal fissure, costophrenic
and cardiophrenic angles
Lungs Local , generalised abnormality , comparison
of translucency and vascular markings
Hila Density , position , shape
Hidden areas Apices , posterior sulcus , mediastinum , hila
Soft tissues Mastectomy , gas , densities
Bones Destructive lesions etc

INSPIRATION
1. Anterior 6 ribs or posterior 10 ribs
2. Shallow insp : elderly , patients in pain , unconscious and
with bedside radiography .
3. Pitfalls :
1. cardiac diameter appears enlarged due to its
attachment with diaphragm
2. crowding of the vessels at lung bases simulating
basal lung infection or areas of subsegmental collapse
.

ROTATION
1. Vertical line drawn through the centre of the vertebral
bodies (T1-T5) is equidistant from the medial end of each
clavicle .
2. Rotation to right : manubrium and SVC or vessels arising
from the arch of aorta becomes prominent .
3. Rotation of left : aortic arch may appear enlarged.
4. Common cause for one lung appearing blacker than the
opposite side.
1. Seen in drowsy , ill patients or children who do not held still

EXPOSURE
Adequate exposure : vertebral bodies and disc spaces
should be just visible down to the T8/9 level through the
cardiac shadows
UNDERPENETRATION : pulmonary vessels and interstitial
markings appear more prominent, loss of detail at the lung
bases and vertebrae, results in increased density
OVERPENETRATION : results in loss of visibility of low
density lesions such as early consolidation

EXPOSURE FACTORS
Choice of factors depends on density , thickness ,
pathology etc
1. The milliampere seconds (mAs)
2. the kilovoltage (kvp)
3. The film to focus distance(FFD)

MILLIAMPERE SECONDS
1. Indicates intensity or amount of radiation being used.
2. It is the product of xray tube current (mA) and exposure
time (seconds)
3. As a rule , mas should be as high as possible with a short
time to reduce movement unsharpness.
4. Low mAs: underexposed - low density - low contrast
5. high mAs : overexposed – excessive density – lack of
contrast

KILOVOLTAGE (kvp)
MOST IMP FACTOR in control of contrast .
1. Kvp indicates how the xray beam will penetrate the body.
2. As the kvp increases – xray more energy – penetrate more
3. Max contrast : if lowest possible kvp is used .
dense structure ( bones) absorb
less dense ( soft tissues ) not well absorb
leads to contrast
4. Kvp increases – more penetration- less contrast

FILM TO FOCUS DISTANCE (FFD)
Greater FFD- lower radiation reaching the film
So if FFD is increased, mAs should also be increased.
1. Xray tube should not be too close to the patient skin –
radiation damage
2. Short FFD could give unacceptable geometric
unsharpness
3. FFD should not be excessive , otherwise the large
increase in mas would require high tube loading .
4. Most xray = 100cm
Cxray = 180cm

Positioning
• patient is erect facing the upright image receptor, the
superior aspect of the receptor is 5 cm above the shoulder
joints
• the chin is raised as to be out of the image field
• shoulders are rotated anteriorly to allow the scapulae to
move laterally off the lung fields, and this can be achieved
by either:
– hands placed on the posterior aspect of the hips, elbows
partially flexed rolling anterior or
– hands are placed around the image receptor in a hugging
motion with a focus on the lateral movement of the scapulae
• shoulders are depressed to move the clavicles below the
lung apices

Technical factors
posteroanterior projection
suspended inspiration
centring point
the level of the 7th thoracic vertebra, approximately the inferior
angle of the scapulae
collimation
superiorly 5 cm above the shoulder joint
inferior to the inferior border of the 12th rib
lateral to the level of the acromioclavicular joints
Exposure
100-110 kVp
4-8 mAs
FFD : 180 cm

AP ERECT VIEW
1. Done in ill patients.
2. To see rib fractures
3. Considered inferior to PA :
• mediastinum is magnified

Patient position
1.patient is upright as possible with their back against
the image receptor
2.the chin is raised as to be out of the image field
if possible, the hands are placed by the patient's side
3.shoulders are depressed to move the clavicles
below the lung apices

Technical factors
anteroposterior projection
centring point
the level of the 7th thoracic vertebra, approximately 7 cm below
the jugular notch of the sternum
collimation
exposure
100-110 kVp
4-8 mAs
SID
180 cm

PA VIEW AP VIEW
Scapula donot overlap the lung
fields.
Seen in the periphery
Scapula overlapping the lung fields
Clavicle project on the lung field Clavicles are above the apices of the
lung
Posterior ribs distinct anterior ribs distinct

SUPINE
PREFERED:
1. Very ill or young child
2. Useful in distinguishing
between free and
encapsulated fluid
3. between elevation of
diaphragm and the free
fluid trapped below the
inferior surface of the
lung

Patient position
1.patient is supine
an image receptor is placed
under the patient's chest
2.the chin is raised (if possible)
as to be out of the image field
if possible
3. the hands are placed by the
patient's side
4.any leads or lines that can be
moved should be transferred
out of the image area to
improve image quality

Technical factors
centring point
the level of the 7th thoracic vertebra, approximately 7 cm below
the jugular notch of the sternum
collimation
superiorly 5 cm above the shoulder
exposure
100-110 kVp
4-8 mAs
SID
180 cm

LATERAL
The lateral chest view may be performed as an adjunct.
Lateral radiographs can be particularly useful in assessing
1.the retrosternal and retrocardiac airspaces.
2.Enlargement/collapse of a diseased lobe/segment
3. Encapsulated fluid prior to tapping
Practical points
The left lateral is the preferred lateral position as it demonstrates
better anatomical detail of the heart.

POSITION
1.standing upright
2.left side of the
thorax adjacent to
the image
receptor
3.left shoulder
placed firmly
against the image
receptor
4.both arms
raised above the
head, preventing
superimposition
over the chest
5.chin raised out
of the image field

Technical factors
lateral projection
centring point
the midcoronal plane of the level of the 7th thoracic
vertebra, approximately the inferior angle of the
scapulae
collimation
anteroposterior to the level of the acromioclavicular
joints
exposure
100-110 kVp
8-12 mAs
SID
180 cm

LATERAL DECUBITUS
VIEW
Used for :
1. Pleural effusion (side
of interest should be
down)
2. Pneumothorax
(should be up )
3. Foreign bodies
(bilateral views)

POSITION
the patient is laying
either left lateral or right
lateral
the detector is placed
posterior to the patient
patient's hands should
be raised
rotation of shoulders
should be minimized
x-ray is taken in full
inspiration

Technical factors
lateral decubitus
centring point
midsagittal place (xiphisternum)
at the level of T7
collimation
laterally to include both lungs
superior to the apex
inferior to the
costodiaphragmatic recess
exposure
100 - 125 kVp
3 - 10 mAs
SID
100 cm
grid
yes

LORDOTIC
1.Gives relatively bone free view of
the upper lung fields.
2. Confirming the presence of middle
lobe and lingular disease
3. Mediastinal herniation

POSITION
the patient is standing with
feet approximately 30cm
away from the image
receptor, with back arched
until upper back, shoulders
and head are against the
image receptor
the shoulders and elbows are
rolled anteriorly
the angle formed between
the midcoronal body plane
and image receptor should be
approximately 45 degrees

Technical factors
centring point
midsagittal plane, halfway between the manubrium and the xiphoid process
collimation
exposure
100-110 kVp
4-8 mAs
SID
180 cm
grid
yes (this may be departmentally dependent)

EXPIRATORY VIEW
1.An expiratory chest
radiograph can be taken in either
a PA or AP projection.
2.They are used to help detect
small pneumothoraces and to
assess for inhaled foreign
bodies or gas trapping in COPD
3.The cardiac
silhouette appearing enlarged,
and spurious basal opacities
being the most common false
positive findings

Helpful in localising a lesion , in visualising
its borders and projecting it free of overlying
structures.
Prefered to lateral views in bilateral diseases
bcz the superimposition of the images on
two sides is reduced
Pulmonary vasculature is well shown in
oblique
Degree of obliquity :
1. Lung lesion – 25 deg
2. Cardiac lesion – 60 deg
LEFT OBLIQUE : left anterior and right
posterior oblique views
OBLIQUE VIEW

Opacities obscured in the apical region by
overlapping ribs or clavicular shadows
may be demonstrated by modification of
the PA or AP projections
APICAL VIEW

1. With the patient
in the position
for the PA
projection , the
central ray is
angled 30
degrees
caudally
towards the c7
spinous process
Exposure
100 kVp
4 mAs
FFD / SID 180 cm

2. With the pt in the
position for the AP
projection , the ray is
angled 30 degrees
cephalad towards
the sternal angle.

PAEDIATRIC C XRAY
The chest
radiograph is one of
the most commonly
requested
radiographic
examinations in the
assessment of
the pediatric patient

Indications
respiratory disease (e.g. respiratory
distress syndrome)
cardiac disease
bronchiolitis
pneumonia
pulmonary tuberculosis
pneumothorax
trauma
foreign bodies
septic screen
confirming the location of line
placement (e.g. PICC, ETT, NGT etc.)

STANDARD PROJECTIONS :
suit the patient's needs and age:
PA erect
performed on older patients (teenage
years)
AP erect
ideal for cooperative younger children
(i.e. between 3-7 years old) due to the
ease of positioning and
immobilization
AP supine
performed when imaging unconscious
or uncooperative children
exposure 3
73-90 kVp
1-2 mAs
SID
110 cm

TRACHEA
1. For narrowing , displacement and intraluminal lesions
2. Midline in upper then deviates to right .
3. On expiration :
1. deviation towards right becomes more prominent .
2. shortening – if ET tube just abv carina on
inspiration may block the main bronchus on expiration .

MEDIASTINUM AND HEART
1. Dense cardiac shadow : mediastinum , heart , sternum and spine .
2. Good centering : 2/3rd to left and 1/3rd to right
3. Transverse cardiac diameter :
females: <14.5cm
males : <15.5 cm
4. CT ratio <50% on a PA film
<60% on a AP film
5. Increase in excess of 1.5 cm is significant
6. Pitfall : enlarged with short FFD , on expiration , in supine and AP projections
and when diaphragms are elevated .

DIAPHRAGM
1. Right is higher due to heart depressing the left side.
2. In 3% right is lower than left due to stomach or splenic flexure distension with
gas .
3. Difference greater than 3cm in height – significant .
4. In supine , diaphragms are higher
5. Costophrenic angles
6. Cardiophrenic angles : epicardial fat

HILUM
COMPONENTS :
1. 99 % of each hilar shadow is due to vessels- pulmonary arteries and veins
2. Very minor contribution from fat , LN, bronchial walls.
SIZE :
1. wide variation
2. unusual prominence due to technical factor (rotation) or a skeletal abnormality
(scoliosis)
SHAPE :
1. no lumpy , bumpy elements
2. vessels margins smooth and have branches
POSITION :
1. superior margin of left hilum is higher than right (reason)
2. at same level in 5% ( felson)
3. left never lower than right hilum

BONES
1. Sternum
2. Clavicles
3. Scapulae
4. Ribs
5. Spine
SOFT TISSUES
1. Breast shadows : mastectomy ?
2. Nipple shadows : well defined
laterally and may have a lucent
halo . Repeat films with nipple
markers ae necessary.
3. Skin folds : can be confused
with pneumothorax ( extends
outside the lung field )

basics of chest xray

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