3. Introduction
Radiography is a process by which images are obtained by projecting x ray beams through a
subject and onto an image detector.
Xray was discovered in 1895 by a professor of physics, Wilhelm Roentgen
The radiographic image produced is a projectional map of the amount of radiation absorbed by
the subject along the course of x ray beam.
When a radiograph is taken, X-rays reach the film and darken it. The more X-rays reach an area
of the film, the darker that area will be on the radiograph. Therefore, if an object is very dense,
less X-rays will reach the film and consequently the image of the object will appear white on the
radiograph e.g. bone.
4. Common Radiographic Terminology
•Erect : standing
•Decubitus : lying down
•Lateral decubitus : lying on one side
Right lateral – right side touches
Prone -: lying face down
Anteroposterior – central rays passes perpendicular to coronal plane from anterior to posterior
Posteroanterior – central rays passes perpendicular to coronal plane from posterior to anterior
Opacity – area on the x-ray that is brighter than normal
Lucency – area on the X ray that is darker than normal
5. Radiological densities
There are 5 principle densities recognised on plain X-rays:
1. Air/ Gas = black (e.g. lung, bowel, stomach)
2. Fat = Dark grey (e.g. subcutaneous tissue layer, retroperitoneal fat)
3. Soft tissues/ Water = light grey (e.g. solid organs, heart ,muscle, bladder)
4. Bone = off white
5. Contrast material / Metal = bright white
6.
7. Before interpreting a radiograph
Patient’s identification
Date
The part of the body
Check the marker – Left or Right
Check if the film was adequately taken- eg. Rule out rotation in chest radiograph
Follow a patten while studying the film- Inspect From outside to inside
8. The skull
Since the advent of computed tomography and magnetic resonance the need for plain X-rays of
the skull has almost disappeared.
Plain films are of limited value in suspected intracranial pathology, especially in the absence of
neurological signs.
STANDARD VIEWS ;
Lateral
AP or PA
Townes view ( half axial view) - is an angled anteroposterior radiograph of the skull and
visualizes the petrous part of the pyramids, the dorsum sellae and the posterior clinoid
processes, which are visible in the shadow of the foramen magnum.
9. Indication for skull radiograph
Evaluation of skeletal dysplasia
Diagnostic survey in abuse
Abnormal head shape
Infections and tumours affecting the skull bone
Metabolic bone disease, leukaemia and multiple myeloma
10. Skull x-ray views
•Lateral view - best displays the ethmoid and sphenoid sinuses
•AP / PA view – usually taken PA . For visualization of skull fractures with medial and lateral
displacement.
•Towne’s view- This is taken with a 30 degree caudal tilt of the tube to project the occipital and
petrous bones free of the overlying facial bones.
•Waters view - a PA radiograph of the skull with the patient’s head tilted back (like someone
drinking water!). This view displays best the orbital rim, the floor of the orbit, the maxillary
sinuses, the zygomatic bones, the nasal septum and nasal bones
•Caldwell’s view- a frontal radiograph of the head taken with the patient's face against the film
(PA). This view best displays the frontal sinuses, the orbital rim and the medial orbital wall
17. Before interpreting a radiograph
Patient’s identification
Date
Xray view- AP , PA , lateral
Breath – inspiratory or expiratory
Penetration
From outside to inside-
-Soft tissue and bones
-Diaphragms - These have a smooth outline and are convex upwards. The right
dome lies 1-2cm higher than the left. Usually at or below the level of the 10th posterior
rib or 6th anterior rib. The costophrenic angle should be acute & clear
-Lungs – opacity/luscency
-Mediastinum – trachea (position), heart (size, border)
18. Views
•Posteroanterior view
Chest X-rays (CXR) are normally taken erect and PA (posterior anterior). The anterior
chest wall is against the film cassette and the X-ray tube behind the patient aimed towards the
film.
•Anteroposterior view- in patients unable to stand
•Lateral view
Further assessment & localisation of abnormalities seen or suspected on the PA film.
Earlier detection of small pleural effusions if ultrasound is not available
19.
20.
21. A GOOD PA CHEST X-RAY?
1. The patient should not be rotated. Look at the anterior ends of the clavicles. They should be
equidistant from the spinous processes. If the patient is rotated one side of the chest will look
paler than the other & the mediastinum will appear abnormal
2. The film should be taken on full inspiration. To check for this count the number of ribs
showing above the diaphragm. The top of the R diaphragm should lie below the anterior end of
the 6th right rib. The left diaphragm is usually lower.
3. The ribs should be sloping and not horizontal. If they lie horizontally, it may be that the
patient was leaning backwards and the diaphragms will obliterate the lung bases.
4. The anterior end of the first rib should lie just below the clavicle.
22. 5. The scapulae should not overlay the lung fields.
6. The spinous processes should be faintly visible through the heart shadow so that lesions
behind or in front of the heart will not be missed. The bony detail should not be visible because
the lungs will then appear too dark.
7. The whole of the lung fields should be fully included on the film. Make sure that part of the
costo-phrenic angles & apices have not been missed.
28. Cardiothoracic ratio is the simple method of estimating cardiac enlargement
Estimation of cardiothoracic ration should always be done on a PA film
The heart size should not measure greater than 14.5/15 cms in diameter in women, or 15.5/16cm
in men.
Normal:
For adult – 50%
For neonates - 60%
32. THINGS TO LOOK OUT FOR
Patient’s name
Date
Position of film/view
Any bowel preparation
Preperitoneal fat line
Size , position / location of visualised organs
Any opacity or calcification
Artefacts
34. Views
Supine
Erect –This is taken to look for fluid levels and free gas.
bowel obstruction, KUB, pneumoperitoneum
Lateral decubitus-
This may be useful instead of an erect film if the patient is unfit to stand.
A left lateral decubitus view is taken with the patient lying on the left side.
This shows fluid levels and small amounts of free air will be seen between the liver and the
diaphragm.
Lateral abdomen- This is seldom necessary but may occasionally be useful for suspected aortic
aneurysm (if ultrasound is not immediately available).
35.
36. The large bowel lies peripherally.
There may be longer fluid levels and the
maximum diameter is variable.
The large bowel often contains faeces & has a
speckled appearance due to gas trapped in the
faeces.
The haustra can be recognised by the fact that
they do not cross the full width of the bowel
and they are not regular.
37. The small bowel lies centrally.
There should be no more than 3 short fluid
levels on an erect film.
There should only be small amounts of gas in
the small bowel.
The jejunum is recognised by valvulae
conniventes, folds which traverse the full
width of the bowel.
39. Calcifications that may be seen that are not significant.
- Phleboliths in the pelvis – these may mimic lower ureteric stones but are more rounded in appearance.
Often multiple.
- Prostate. Calcification is often seen in the prostate and is a normal finding. It should not be confused with
a bladder calculus. It lies below the bladder, centrally.
- Seminal Vesicles. These occasionally calcify. They are serpiginous in appearance, lying behind the
bladder.
42. Indication
Arthritis of the hip
Pelvic fractures
Hip dislocation
Stiffness of spine or sacroiliac joint (ankylosing spondylitis)
43. Projections
AP- standard projection
INLET VIEW – demonstrates pelvic ring. Best for evaluating posterior displacement of pelvic ring
and fracture of pubic symphysis
OUTLET VIEW – assess for superior displacement of hemipelvis in fracture
FLAMINGO VIEW- evaluation of suspected pubic symphysis instability
JUDET (Oblique) VIEW- patient is place in 45 degree oblique position. Evaluation of superior,
medial, lateral and posterior surfaces of acetabulum
49. Things to look out for
Soft tissue abnormality
Discontinuity of the bone
Displacement/ dislocation of joint
Density of the bone
Narrowing of joint space
56. Indication for X-ray of the Spine
Trauma
Fracture
Dislocation
Pain
Ankylosing spondylitis,
Spondylosis
Suspected neurofibromatosis
TB spine
Tumour
57. Cervical spine
Lateral
Antero-posterior(AP)
AP odontoid view if there is a history of trauma. This is taken through the open mouth.
Oblique views- are not routine but are sometimes needed in trauma. They are also indicated in suspected
neurofibromatosis ( to show the intervertebral foramina) and are helpful in spondylosis if there are
neurological signs. They show posterior osteophytes better than the lateral view.
61. Following trauma it is important that the spine is not moved until fracture has been excluded.
All the films should be taken with the patient supine.
The lateral film should be inspected and obvious fracture excluded before moving the
patient.
All the vertebral bodies should be included on the film from C1 –T1.
62. Thoracic and Lumbar Spine
The standard projections are Lateral and AP
AP
Usually the vertebrae are counted with reference to the 12th rib or the sacrum.
The 3rd lumbar vertebra usually has the longest transverse process & this is sometimes a useful guide.
The spinous processes lie in the centre of the bodies and should lie in a straight line.
The pedicles are round oval structures on each side of the body and should be symmetrical. A pedicle is often
destroyed in metastatic disease and the pedicles should always be checked.
The vertebral bodies increase a little in size lower down the spine but the lateral vertebral lines should be un-
interrupted. The outlines should be clear.
The disc spaces should be equal in the thoracic region. In the lumbar spine they increase in size from L1 down to
the L5/S1 disc space.
The interpedicular distance increases slightly in the lumbar spine from L2 to L5.
63. LATERAL:
The vertebral bodies in each region of the spine should be roughly the same size and shape.
A lines drawn along the anterior and posterior bodies should be smooth and uninterrupted.
The bodies should be roughly square shaped with well- defined outlines.
The disc spaces increase in size from L1 to L5.
The densities of the bodies should be equal and the trabeculae should be seen.
67. Conclusion
Radiographs play a role in the diagnosis of diseases and treatment
follow–up.
A good knowledge of the human anatomy is needed for proper
interpretation of a radiograph
68. References
Ouellette H. Tetreault P. Clinical Radiology made ridiculously simple. MedMaster, 2000
Tersoo’s Radiology. 2008. Revised edition.
Bell D. Shetty A. Radiographic Positioning Terminology,
http://radiopeadia.org/articles/radiographic-positioning-terminology/ accessed 25th May, 2021
Tarek M. Evaluation of plain skull X-ray Skull: A systemic approach
Dr Arushi G. Abdominal Xray. https://www.slideshare.net/ArushiGupta119/abdominal-xray-
imaging-and-interpretation-173049384. accessed 23rd May, 2021.
