Download Radiology (Medical Imaging)

RADIOLOGY (MEDICAL IMAGING)
Radiology is the study of the diagnosis of disease by the use of radiant
energy (radiation). In the past this meant the use of X-rays to make an image.
Today many other forms of radiation are used to aid both diagnosis and treatment of disease.
The investigation of disease by methods involving the use of ultrasound, and by methods
which show the infra-red radiation from the body – thermography - also fall within the
scope of diagnostic radiology
It involves the diagnosis and treatment of diseases using radiation. Radiation is the
emission (sending forth) of waves or particles of radiant energy. Examples of radiation are
radio waves, infra-red waves, ultraviolet light, x-rays, alpha particles, beta particles and
gamma rays. A substance that is radioactive has the property of spontaneously emitting
some form of radiant energy e.g. a radioisotope.
Root word
Radi
Combining form
Radi/o
Meaning
Invasive rays produced by an x-ray machine
Roentgen
Roentgen/o
X-rays
Cine
Cine, cinemat/o
Moving film
Tom
Tom/o
Slice or section
Son
Son/o
Sound
Echo
Echo-
Reflection of sound
Therm
Therm/o
Heat
Scint
Scint/i, scintilla/a
Emitting sparks/light
Radiotherapy and radiology:
Radiology is the branch of medicine concerned with radioactive substances; with using
various methods of visualisation to diagnose and treat diseases using various sources of
radiant energy. Three branches of radiology are:
1.
2.
3.
Diagnostic
Therapeutic
Nuclear medicine
Diagnostic radiology:
Diagnostic radiology is imaging using external sources of radiation. Diagnostic radiological
investigations consist, in their simplest form, of taking X-ray pictures or radiographs, and of
visual examination of internal structures on a fluorescent screen. The radiological
demonstration of certain body structures requires that their interior cavities be filled with
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substances which are either more opaque (eg barium), or more translucent (eg air), than
surrounding body tissues
Therapeutic radiology:
Therapeutic radiology is the treatment of disease - principally neoplasms - using radiation.
This involves treatment by ionising radiations produced by superficial and deep X-ray
machines, linear accelerators, betatrons and so on, or ionising radiations produced
spontaneously by radium, radio-cobalt, radio-phosphorus, radio-iodine and other
radioactive isotopes. This type of therapy is commonly used to treat malignant neoplasms,
but can also be used for other diseases such as skin conditions
Nuclear medicine:
Nuclear medicine is imaging using radio-active materials that are placed in body organs,
e.g. bone scan - by injection of radioactive material. The concentration of injected material
in any specific area reveals an abnormal condition of bone, particularly metastatic bone
disease.
X-RAY
The most common use of radiation is x-rays. X-rays pass through the body and expose an
x-ray film, producing a photographic image called a radiogram. A radiogram provides a
two-dimensional shadow image of the interior of the body. Parts of the body block the xrays and these structures are said to be radio-opaque, they appear light or white on x-ray
film, e.g. bones. From these images diagnoses can be made e.g. fractures. Other parts of
the body are not radio-opaque and the x-rays pass through them so they do not show up
on film, e.g. the gastrointestinal tract. In order to x-ray these areas, a contrast medium is
inserted into the body. Barium (Ba) is a radio-opaque substance or contrast medium is
used either orally or rectally to make the GIT more visible on film. Barium studies - can be
a meal or enema. Contrast mediums can also be injected into the body.
X-rays compress body images onto a flat sheet of film, often resulting in an overlap of
organs and tissues that can make diagnosis difficult.
CT Scan
These diagnostic difficulties have been virtually eliminated by the use of an x-ray technique
called CT (computed tomography) scanning. CT scanning combines the principles of x-ray
and advance computer technologies. An x-ray source moves in an arc around the part of
the body being scanned and repeatedly sends out x-ray beams. The beams are then
converted into electronic impulses that produce thousands of readings of the density of the
tissue in a 1cm (or smaller) slice of the body tissue. Next, the computer produces a
graphic, detailed sketch from these readings called a CT scan, which can be viewed on a
TV screen. The CT scan produces very accurate cross-sectional (slices) pictures of any
area of the body. The CT scan permits a significant differentiation of body parts that was
never possible with conventional x-rays. The entire CT scan process takes only seconds,
it is completely painless and the x-ray dose is equal to or less than that of many other
diagnostic procedures.
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MRI
Nuclear magnetic resonance or more commonly magnetic resonance imaging (MRI) is a
technique that does not expose the patient to ionizing radiation and its associated hazards.
MRI has a greater sensitivity to detecting malignancies, ischaemic regions and other
functional changes in the tissue of an organ before they have progressed so far that gross
anatomical changes have been produced. The contrast between grey and white matter in
the brain is much more distinct with MRI, while the image is almost unaffected by bone.
Computer technology can then be combined with the detailed imaging data to produce a
cross-sectional image in almost any plane, or sequence of these to give a ‘slice’ effect.
Ultrasonography
Another type of image is created by high frequency sound waves - an ultrasound. An
ultrasound is a record of sound waves as they are reflected from internal structures.
Internal organs and masses reflect sound to a different extent, giving different echo
textures. These internal echoes are detected and converted into an image.
Treatment
Radiation is also used to treat diseases, usually cancer. This is called radiotherapy or
radio oncology. Radiation is used to shrink or kill tumours.
Radiography
the process of making film records
Radiogram
the film, x-ray or recording produced by this process.
Radiograph
the instrument used in this process
Radiologist
is a specialist in the field of radiology.
Radiographer
is the technician who takes the film.
Radioisotopes
behave like transmitters passing radiation from inside to the outside of
the body. Used as diagnostic labels to trace the route and uptake of
chemicals administered into the body.
Activity 1
Write the meaning of:
1.
tomogram __________________________________________________________
2.
radiotherapy _________________________________________________________
3.
radiotherapist ________________________________________________________
4.
echocardiogram ______________________________________________________
5.
echoencephalogram ___________________________________________________
6.
fluoroscope __________________________________________________________
7.
echogenic __________________________________________________________
8.
echogram __________________________________________________________
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INVESTIGATIONS
Arthrography
Radiography using contrast media to outline soft tissue structures
in a joint
Bone x-ray
Radiographic examination of a bone of the body for presence of
disease or fractures
Angiogram
A contrast medium is injected into the blood vessels and an x-ray
is taken to study particular vessels, for example, the coronary
arteries or carotid arteries for coronary artery disease
Cardiac
catheterisation
Passage of a small catheter into the heart via a vein in the neck,
arm, groin, or leg to inject dye for x-ray purposes, to record
pressure and to discover anomalies of the heart; a coronary
angiogram is the test then carried out to show abnormalities of
the heart
Echocardiography
(cardiac ultrasound
examination)
Use of high-frequency sound waves to visualise the heart for
assessment of valvular heart disease and overall heart function
Venography
X-ray procedure using contrast dye to determine the presence of
blood clots or other blockages caused by disease such as
arteriosclerosis
Chest x-ray
Radiographic examination to check for any abnormality of the
lungs or chest cavity
Barium enema
Radiographic studies using contrast medium to visualise the
colon and rectum
Cholangiography
Radiographic studies of the gall bladder and its ducts to see if
blockages or stones are present
Gastrointestinal series
Radiographic studies of oesophagus, stomach and small
intestine, after swallowing a contrast medium such as barium.
Intravenous
pyelogram ivp
Radiographic visualisation of the kidneys and urinary tract after
an intravenous injection of a dye or substance
Retrograde pyelogram
Radiographic visualisation of the kidney and urinary tract, using
injection of a contrast medium directly into the bladder
Ultrasound
The imaging of internal organs deep in the body by recording the
reflection of pulsed or continuous high frequency sound waves; it
is important in the diagnosis of foetal abnormalities, cholecystitis,
heart defects and tumours
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Magnetic resonance
imaging mri
Non-invasive method of scanning the body by use of an
electromagnetic field and radio waves, which provides visual
images on a computer screen and x-ray films: it is used
particularly to visualise the brain and spinal cord
Computerised {axial}
Tomography (ct / cat)
Imaging device using x-rays at multiple angles through specific
sections of the body, analysed by computer to provide a total
picture of the part being examined
Lung scan
Involving intravenous injection of radioactive material to diagnose
pulmonary emboli and lung structure and function
Radioactive iodine
uptake
Thyroid function is evaluated by introducing radioactive iodine
orally or by intravenous injection during a selected time period,
and measuring its absorption by the thyroid with a gamma ray
detector.
Hysterosalpingography
X-ray of the uterus and fallopian tubes, using contrast medium to
show blockages and the cause of infertility
The following website has heaps of information about anything connected with radiology. It
is well worth a visit. http://www.radiologyinfo.org/
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