Chest Radiography
Image Evaluation
⬧ Distance between image receptor and
tube focus & X-ray beam alignment
⬧ X-ray tube voltage
⬧ X-ray tube current and exposure time
⬧ Effective focal size
⬧ X-ray grid
⬧ Electrical power supply for x-ray
equipment
⬧ X-ray film viewer
⬧ Mobile x-ray unit
- CR must be perpendicular to IR & RP.
The effect of SID on resolution.
As SID increases, penumbra is reduced & resolution increases.
The effect of SID on image
size magnification.
Magnification is minimized
by increasing SID.
- 100-120kVp is recommended
- Low contrast (wide latitude/long scale)
Low kVp
High kVp
- suitable mAs depends on the unit used
- exposure time is less than 0.05s
- more than 100mA
- impedance of mains electricity – less than 0.3
minimize motion
- smaller than 1.2mm
Resolution increases
as focal spot decreases.
- minimum of 34 lead strip line/cm
- 8:1 grid ratio
X-ray Film Viewer
- minimum of two (2) vertically mounted
15W fluorescent bulbs
Mobile X-ray Unit
- not recommended for chest radiography
- used only for restricted applications
- screen type : green light emission is
recommended
- screen sensitivity: medium speed is recommended
e.g. HG-M, XG-S, Lanex Medium etc…
- film suitable for color light emitted by screen
- film-type: regular type recommended
Select
chest
“Gold
Standard”
Name of Health Facility
Name of Patient
Age
Date of Examination
Outside the
lung field
Checked in terms of the seven (7) items:
⬧ defective lungs
⬧ poor inspiration
⬧ oblique positioning
⬧ position of clavicles
⬧ position of scapulae
⬧ asymmetric density of the lungs
⬧ foreign substances
Positioning of patient for chest radiography
Standing
Seated
PA Projection
- avoid magnification
of the heart
Ideal position of lungs.
Defective lung fields.
Defective lung field
due to light having
leaked into the
processing room.
Insufficient Inspiration
Good Respiration
Checking Point
The posterior part of 10th rib bone is painted as
black in this figure
Checking Point
Full inhalation
Exhalation
Female patient w/ large breast
Breasts superimposed
over lower lungs
Correct placement of breasts
Ideal Positioning
Poor Positioning
SCJ symmetric
SCJ asymmetric
Clavicles visualized apart from the 4th posterior rib
Improper positioning of clavicles
Good position
symmetrical
Asymmetric
density of lungs
Poor Positioning
Human eye can not determine the
density but densitometer can provide
the numeric value.
⬧ lung field (1)
⬧ lung periphery (2)
⬧ mediastinum (3)
⬧ cardiac shadow (4)
3&4
2
1) Lung field: 1.86
2) Lung periphery: 0.68
3) Mediastinum structure: 0.51
4) Cardiac shadow: 0.53
1
High Contrast
Proper Contrast
Improper Contrast
Good Contrast
Pulmonary vessels
visualized behind
the bones
Assessment of lung field
Pulmonary
vessels can be
easily traced at
the lung fields
Assessment of lung periphery
Pulmonary vessels
can be easily
visualized at lung
periphery, and
the border line
between the
chest wall and
the lung field
Assessment of mediastinum structure
Trachea &
both main
tracheal
branches are
clearly
visualized
Assessment of cardiac shadow
:Pulmonary
vessels can be
easily visualized
behind the
cardiac shadow
Poor definition
Excellent definition
Sharpness of the pulmonary vessels
Poor
Good
Poor sharpness
(blurring)
due to heart
stroke motion