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b) The chest X-ray is the commonest diagnostic
X-ray examination
.
Normally a frontal (anteropostetior) view is obtained. The patient
stands facing the photographic plate with the chest pressed to the
plate, with hands on hips and elbows pushed out in front. The
padiographer, the technician who takes the X-ray, asks the patient
not to move, then to breathe in deeply and not to breathe out. This
makes a blurred, unclear X-ray image less likely and improves the
quality of the image, as it is easier to see abnormalities in air-
filled (inflated) lungs than in deflated lungs. During the procedure
the radiographer orders the patient to keep still, or to take a deep
breath, or to hold his (her) breath.
c)
Ultrasound examination
uses high-frequency sound waves to
view organs and structures inside the body. The waves are gener-
ated and received by a hand-held device called a transducer. The
reflected waves are processed by a computer which produces de-
tailed images for display on a monitor. Ultrasound is a safe as it
does not employ ionizing radiation like X-rays. It is a cheap,
quick and non-invasive investigation for a wide range of referrals,
although results can be unsatisfactory in obese patients
d)
CT (Computed Tomography)
uses an X-ray source which rotates
around the body to produce cross-sectional images. The scanner
will be used for:
– diagnosing muscle and bone disorders
– locating tumors, infections and clots
– monitoring the progress of malignant diseases and the re-
sponse to therapy (treatment)
– providing accurate guidance for interventional procedures
such as biopsies, and drainage – removing fluid from the site
of injury or infection.
e)
Magnetic Resonance Imaging (MRI)
is safer than X-rays because
it does not radiation. It provides more information than CT about
some head, neck and spinal disorders because the images are
more detailed and have more contrast, meaning the differences
between dark and light areas are stronger. Unlike CT, images can
be taken on any plane, any surface of the body seen from an an-
gle. MRI is not approved in patients with metallic foreign bodies
in the orbits, patients with pacemakers, and during the first tri-
mester of pregnancy.