Glossary - medical imaging

A small medical viewing scope which is inserted into the anus to allow for a visualisation of the anus and the lower portion of the rectum. Commonly used to identify abnormalities such as inflammation, hemorrhoids, or tumours.

A C-Arm is a type of radiologic equipment, so named because of its C-shaped arc surrounding its table. A C-Arm is an x-ray image intensifier, normally used for either plain fluoroscopy or digital subtraction angiography (DSA). It allows for lower x-ray doses to be used on patients by magnifying the intensity produced in the output image, enabling the viewer to easily see the structure of the object being imaged.

A C-Arm table is for examination in conjunction with an x-ray image intensifier, also known as a C-Arm. The table is constructed to allow for the placement of the C-shaped arc of the x-ray image intensifier, which arcs over both the top and bottom of the table.

A thin, lighted tube-like medical device which is used to examine the inside of the entire colon and rectum. A colonoscope has a light and a lens for viewing, and may include a tool used for tissue removal. The device is inserted through the rectum into the colon to enable to doctor to view the entire lining of the colon.

An endoscopic instrument used in the examination of the cervix, vagina, or vulva. The instrument includes a magnifying lens, which is used for the direct observation and study of the tissues of the cervix and vagina.

A visual examination of the cervix and vagina using a lighted optical magnifying instrument (known as a colposcope, which is a type of endoscope) to check for abnormalities. This procedure is primarily performed to identify areas of cervical dysplasia in women with abnormal Pap smears.

A Computerised Axial Tomography machine creates images of the internal structures of the body and are used for diagnosis. The procedure was developed by the British scientist Godfrey Hounsfield who constructed the first scanner in the early 1970’s. The patient lies between an X-Ray source and an array of detectors, which receive different amounts of radiation according to the density of the tissue scanned. The source and detector array are rotated around the patient and the data is analysed by a computer and presented as a graphic image of the ‘slice’. These slices can the be compiled by the computer to produce stunning 3D images of the soft tissue structures. Tomography is a sectional X-Ray. As the radiation is of a lower power the patient doesn't receive large doses of X-rays.

Also known as a crash trolley or code cart. Consists of a set of trays on a wheeled cart that is used in hospital wards and emergency rooms. The cart contains all the basic equipment needed to follow ACLS (Advanced Cardiac Life Support) / ALS (Advanced Life Support) protocols and potentially save a person's life. A crash cart typically includes a defibrillator, intravenous medications (such as epinephrine and atropine), and a variety of medical supplies, such as latex gloves and alcohol swabs.

A procedure in which the doctor inserts a lighted instrument called a cystoscope into the urethra in order to look inside the urethra and bladder. The cystoscope has lenses like a telescope or microscope which lets the doctor focus on the inner surfaces of the urinary tract. The cystoscope is as thin as a pencil and has a light at the tip. Many cystoscopes have extra tubes to guide other instruments for procedures to treat urinary problems.

An apparatus used for measuring the optical density of a material.

A medical test in which sound waves are used to produce an image of the heart through a non-invasive procedure.

A class of medical equipment that uses electrons rather than visible light to produce magnified images, especially of objects having dimensions smaller than the wavelengths of visible light, with linear magnification approaching or exceeding one million.

A device consisting of a tube with a light and a lens on the end which may be inserted into a body opening or incision. An endoscope can be flexible or rigid. Typically used to examine hollow organs inside the body, including the esophagus, stomach, duodenum, colon, or rectum, but also used to take tissue from the body for testing. Optionally, an endoscope can be attached to a camera to take colour photographs of the inside of the body or for viewing on a video screen.

A scope that can be used to visualise the inside of the body, either through insertion into a tiny incision or by passing the scope through a body opening (such as the mouth or anus). Endoscopy is used to examine, biopsy, or surgically treat a variety of conditions. Types of endoscopy include arthroscopy (joints); bronchoscopy (bronchial tubes, lungs); colonoscopy/sigmoidoscopy (large intestine); colposcopy (vagina, cervix); gastroscopy (stomach, small intestine); laparoscopy (abdomen); and others.

The fetal heart can be monitored using ultrasound probes attached to the mother's abdomen whilst in labour. Pulsation's of the fetal heart are heard through a loudspeaker and the fetal heart rate is displayed digitally. Also, the heart rate is printed on a graph over time to show any variations. Additionally, these devices incorporate transducers that measure the contractions with the use of a strain gauge also attached to the abdomen. The result of this is plotted along side the fetal heart rate, thus enabling the midwife to observe the increasing intensity of the contractions. Hand-held fetal heart detectors are used in ante natal clinics and by midwives who use the instruments to check for the fetal heart.

An x-ray machine capable of producing both still images and 'real-time' motion of the joints or vertebrae. Often used to visualise intervertebral joint motion through flexion and extension of the neck or back or to place a syringe needle at a targeted site.

A surgical tool that uses ultrasound waves to cut tissue and seal bleeding vessels at the same time.

A urethroscope was designed and built by Segalas of France in 1826. He used an introductory cannula and mirrors for light. Kalk of Germany has been dubbed ‘the father of laparoscopy’. He wrote papers on the subject from 1929 to 1959 and he devised a foroblique viewing system for use on his work with liver and gallbladder disease. It is his methods that have widely been adopted and are in use today. Laparoscopes are long narrow tubes that contain lenses and mirrors that a surgeon uses to look inside the body. This method is minimally invasive because only a small incision is made through which the laparoscope is passed. Used with an insufflator, and a light source, the laparoscope is inserted into a small incision and can be moved easily around the organs. The recovery of the patient is easier than that of general surgery because of the minimal invasion.

A small, hand-held medical device which consists of a handle, curved tongue depressor, light source, and a magnification source. This device is typically made from surgical metal, allowing it to be sterilised as needed. A larynogoscope is normally used to move aside the patient's tongue and open the throat and expose the larynx. This process allows the doctor to intubate (insert a breathing tube) or perform other procedures.

A Laser is an instrument that amplifies light waves by stimulation to produce a powerful coherent beam of monochromatic light. This intense beam of light can be used to cut or coagulate tissue. The precise accurate aiming of the beam results in the laser being used for extremely fine surgical procedures, for example, on the eye with very little scar damage and fast healing. Laser surgery is less invasive than normal surgery, it destroys diseased tissue gently and allows quicker, more natural healing. Laser treatment can also be directed down flexible endoscopes into the body allowing even less surgery than would otherwise be required.

Bruck, a Dentist from Breslau, made a platinum wire loop which he heated with electric current in 1867, but before the light source was readily available, mirrors were used to reflect the light onto the subject. It is essential for the clinician or surgeon to have a clear view and see clearly at what they are working. The fibre light source is used during surgery to give the surgeon a clear view through an endoscope or laparoscope.

A minimally invasive procedure which untilises sound waves to break up a kidney or other stone into smaller pieces. This allows the smaller pieces to pass out of the urinary system, and it does not require any type of surgical incision.

Magnetic Resonance Scanning (sometimes called Magnetic Resonance Imaging 'MRI' or nuclear magnetic resonance imaging 'NMR') is a relatively new technique used to investigate the body for diagnostic purposes and has the advantage that it does not use ionising radiation (X-Ray). It comprises a large circular magnet that determines the magnetic bearings of a number of atom nuclei in the body. As the magnet is switched on, some atoms in the body are excited by radio waves. The atoms move into a high energy state and give off a weak radio signal that is picked up and sent to the computer that displays the information as an image. Different radio wave frequencies represent different elements of tissue. The procedure is totally painless, but sometimes an injection is needed (radio opaque die) to enhance the scan.

Intricate surgery can be performed using microscopes and precision surgical instruments during brain, ear and eye surgery, and severed limbs. This has only become possible in recent years. Microsurgery relies on the highly trained surgeon who can connect together the ends of nerves, arteries, veins or muscles to enable the nutrition required to preserve tissue.

A surgical procedure that uses small surgical incisions or no cuts at all. These procedures greatly reduce the amount of bleeding. Examples of minimally invasive procedures include lithotripsy, in which sound waves are used to break up a kidney stone or other stone without any incision required, and endoscopy, which uses small scopes inserted into small cuts or body openings.

Acronym for Magnetic Resonance Imaging. A diagnostic technique using powerful electromagnets, radiofrequency waves, and a computer to produce well-defined images of the body’s internal structures, especially the brain and spinal cord.

Also known as an auriscope, an otoscope is a hand-held instrument whch includes a magnification lens and light which is used to examine the ear canal and eardrum. An ear speculum (a funnel shaped attachment) is attached to the otoscope to allow the physcian to direct the light at a particular point.

Phototherapy, or light therapy, consists of exposure to daylight or to specific wavelengths of light using lasers, LEDs, fluorescent lamps, or very bright, full-spectrum light, for a prescribed amount of time and, in some cases, at a specific time of day or week.

Positron Emission Tomography was developed in the 1970’s with the advent of the computer that produces the final image. PET is a technique of nuclear medicine and now with smaller particle accelerators the technique may become more widespread. PET is used to monitor biochemical and physiological changes within the body using a ‘labelled’ radioactive isotope that has a short half life. It is known that different parts of the body absorb or metabolise certain substances in definite ways. For example : fluroro-deoxyglucose that is ‘labelled’ can make glucose metabolism in the brain 'visible'. The substance is administered and traced. It is possible to provide information on cerebal palsy and the metabolism of brain tumours.

Radiology is the application of radiation for diagnostic or therapeutic purposes. X-ray is used to detect broken bones and chest infections, but techniques have been developed where a non-toxic radio opaque substance (e.g. barium meal) are administered to show the internal organs that do not show up on normal X-ray. An image intensifier displays the X-ray image on a monitor and can convert the image to a digital format for easy storage. The image can be enhanced digitally thus the dosage of radiation can be reduced to the patient.

Radiodensity is the property of relative transparency to the passage of X-rays through a material. Radiolucent indicates greater transparency to X-ray photons. For example, a radiolucent table permits the passage of x-rays without leaving a shadow on the film. Soft tissues are radiolucent; bones are not.

The measurement of radiation by photography, as in x-ray film and film badge, by Geiger-Mueller tube, and by scintillation counting.

Radiotherapy is the use of ionising electromagnetic radiation (X-ray and Gamma ray) for the treatment of diseases such as cancer. Before the 1930’s radium was physically inserted into tumours through hollow needles. Now teletherapy is used in which controlled irradiation is administered from a distance of 1 metre or more. X-ray was superseded by radioactive isotopes radium and cobalt 60 and then by particle accelerators. A critical factor of radiotherapy is dosage and the treatment tends to be used on localised forms of cancer as normal tissue is sensitive to radiation. Radiotherapy is often used in conjunction with surgery and cytotoxic drugs. Tumours are accurately identified with computerised axial tomography (CAT) and modern radiotherapy machine deliver an accurate, precise dose of radiation. Side effects are reduced because of lower intensity dosages given over a period of time.

Instruments for retinoscopy that determines the refractive state of the eye. In principle, a retinoscope provides a light source to illuminate the retina, and then locates the aerial image of the retina in space to obtain an index of the refractive quality of the patient's lens system.

A thin, lighted tube-like instrument used to examine the inside of a colon. Sigmoidoscopes are available as either flexible or rigid tubes that contain a light and a lens for viewing. The device may also have a tool for removing tissue. Similar to a colonoscope (which is used to examine the entire large bowel), A sigmoidoscope is used to examine only up to the sigmoid, the most distal part of the colon.

A minimally invasive medical examination of the large intestine from the rectum through the last part of the colon.

The graphic registration of the frequency and intensity of sounds, such as speech, infant crying, and animal vocalisations.

An apparatus attached to the head, used to localise precisely an area in the brain by means of co-ordinates related to intracerebral structures.

The electronic transmission of radiological images from one location to another for the purposes of interpretation and/or consultation.

In 1956, Satomura used ultrasound for the first measure of blood flow in the heart. Ultrasound is used in many applications in the medical field. For example, echocardiography in cardiovascular, fetal heart monitoring in maternity, vascular blood flow in theatre, and physiotherapy as heat treatment. Piezo crystals can be exited with an electric current. As current passes through the crystal it emits a wave of sound directly proportional to the frequency of electric current. A piezo can also be used to detect sound (Doppler). As the wave hits the surface of the piezo, a voltage is generated across it. In the case of ultrasound scanners, the piezo is pulsed with electric current and then used to hear for the echo. The strength of the echo depends upon the density of the material being analysed and the results are displayed as a grey or colour scale.

This is a small rigid telescope which may be passed up the urethra to view the state of the urethral wall and prostate gland. It differs from a cystoscope because it has an end rather than a side view. This type of Endoscope, sometimes called a panendoscope, does not normally have extra channels for the passage of surgical instruments, although it must be possible to infuse fluids to create a small viewing space at the end.

The advent of smaller video cameras has enabled this branch of optical medicine to be at the forefront of surgical techniques. Video systems are used in theatres with laparoscopes or endoscopes enabling the surgeon to view on the video monitor internal structures, problems or diseases. The ability to record exactly what the surgeon sees during a procedure gives the opportunity to view the operation, or investigation, later for analysis or training. Endoscope, long fibre optic bundles inserted into natural orifice to view internal structures. Microscope, used in laboratory for looking at clinical samples, in theatres during surgery, and clinics for ENT. Theatre Microscopes are very solid mounted structures slung from the theatre ceilings so that the surgeon can swing powerful microscopes directly over the patient. This invention has allowed the progression of microsurgery on both eyes, nerves and other microscopic structures. Slit lamp, used for looking into the eye. Ophthalmoscope, used by clinicians for looking into eyes, nose, or throat. Otoscopes, used to look into the ears.

Discovered in Germany in 1895 by Wilheim Rontgen X-ray is now used in a wide variety of fields. X-Ray is a form of Electromagnetic Radiation that has a greater energy than light because it has a shorter wavelength. An x-ray beam is produced by allowing a beam of high energy electrons to strike a tungsten target. The target is attached to a water cooled copper anode with an evacuated glass envelope. The x-ray has differing extents of penetration and has the ability to affect photographic material. This is used to produce an x-ray photograph which would show fractures, infection and foreign bodies. Also substances opaque to x-rays such as barium sulphate are used to visualise body organs. For example gastro-intestinal disorders. High energy x-rays are used in radiotherapy to destroy tumour cells in Cancer treatment. See RADIOLOGY

High-energy X-rays are used to treat cancer, since some cancer cells are more susceptible to damage from electromagnetic radiation than ordinary cells. The energy of the X-rays (usually expressed in kilovoltage) determines the depth of penetration. Thus for superficial X-rays (suitable for skin treatment) 50 - 150 kV may be used.