RADIOLOGY (MEDICAL IMAGING)

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Gerard Wilson
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1 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 Combining form Meaning Radi Radi/o 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. Diagnostic 2. Therapeutic 3. 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 Radiotherapy Page 1 of 5

2 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 x- rays 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. Radiotherapy Page 2 of 5

3 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 Radiogram Radiograph Radiologist Radiographer Radioisotopes the process of making film records the film, x-ray or recording produced by this process. the instrument used in this process is a specialist in the field of radiology. is the technician who takes the film. 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 Radiotherapy Page 3 of 5

4 INVESTIGATIONS Arthrography Bone x-ray Angiogram Cardiac catheterisation Echocardiography (cardiac ultrasound examination) Venography Chest x-ray Barium enema Cholangiography Gastrointestinal series Intravenous pyelogram ivp Retrograde pyelogram Radiography using contrast media to outline soft tissue structures in a joint Radiographic examination of a bone of the body for presence of disease or fractures 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 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 Use of high-frequency sound waves to visualise the heart for assessment of valvular heart disease and overall heart function X-ray procedure using contrast dye to determine the presence of blood clots or other blockages caused by disease such as arteriosclerosis Radiographic examination to check for any abnormality of the lungs or chest cavity Radiographic studies using contrast medium to visualise the colon and rectum Radiographic studies of the gall bladder and its ducts to see if blockages or stones are present Radiographic studies of oesophagus, stomach and small intestine, after swallowing a contrast medium such as barium. Radiographic visualisation of the kidneys and urinary tract after an intravenous injection of a dye or substance 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 Radiotherapy Page 4 of 5

5 Magnetic resonance imaging mri Computerised {axial} Tomography (ct / cat) Lung scan Radioactive iodine uptake Hysterosalpingography 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 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 Involving intravenous injection of radioactive material to diagnose pulmonary emboli and lung structure and function 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. 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. Radiotherapy Page 5 of 5

Arteriogram An X-ray of an artery after the injection of dye.

Arteriogram An X-ray of an artery after the injection of dye. A Abscess A localized collection of pus in any part of the body, usually surrounded by inflamed tissue. Anesthetic An agent that causes loss of sensation with or without the loss of consciousness. Angiography,