R
racemose resembling a bunch of grapes.
radial associated with the radius. Applied to the nerve, artery and vein.
radiation the process of heat loss from a body in the form of electromagnetic radiation; this is the only heat transfer process that can take place in a vacuum. Emanation of radiant energy in the form of electromagnetic waves, including gamma rays, infrared, ultraviolet rays, X-rays and visible light rays. Subatomic particles, such as neutrons or electrons, may also be radiated. Radiation may be non-ionizing or ionizing and has many diagnostic and therapeutic uses. See also ionizing radiation.
radiation dosimetry the method of measuring the amount of radiation received by an individual. Also called radiation monitoring.
radiation nephritis inflammation of the renal nephrons; acute associated with hypertension and proteinuria occurring 6–13 months after radiotherapy. chronic associated with urinary protein and casts, nocturia and loss of the ability to concentrate and occurs 1.5–4 years after radiotherapy.
radiation oncologist medical specialist in the treatment of disease by X-rays and other forms of radiation.
radiation pneumonitis inflammation of the lungs caused by the radiation dosage received by the patient.
radiation protection equipment and rules to ensure that staff and patient’s experience safe working practices. See also local rules, dosimetry.
radiation protection advisor a suitably qualified and experienced person whose role is to advise staff on the safe use of ionizing radiation.
radiation protection supervisor a person directly involved with ionization who is responsible for ensuring safe working practices in a specific department and is appointed by the radiation protection advisor.
radiation safety committee a local group of radiation users, advisors and management who discuss matters related to radiation safety.
radiation sickness tissue damage from exposure to ionizing radiation leads to diarrhoea, vomiting, anorexia and bone marrow failure.
radiation treatment planning the method required to graphically display the isodose distribution that results when one or more radiation beams converge on the target volume in external beam therapy.
radical associated with the root of a thing.
radical mastectomy rarely performed operation that involves removal of the breast, pectoralis major muscle and clearance of the axillary lymph nodes.
radical surgery usually extensive surgery which aims to be curative, not palliative.
radical treatment aimed at attempting to kill or remove all malignant cells present.
radiculography radiography of the spinal nerve roots after the introduction of a positive contrast agent via a lumbar puncture to locate the site and size of a prolapsed intervertebral disc. Superseded by CT and MRI.
radioactive exhibiting radioactivity. Describes an unstable atomic nucleus which emits charged particles as it disintegrates. See also radioisotope.
radioactive decay the process by which a nucleus of a radioactive atom spontaneously transforms by one or more discrete energy steps until a stable state is reached. See also half-life.
radioactive disintegration when a stable nuclide, the parent, changes to another nuclide, the daughter, which may be either stable or unstable and therefore radioactive.
radioactive equilibrium equilibrium reached, after radioactive disintegration, when the weight of each nuclide in the atom is inversely proportional to the half-life of the nuclide.
radioactive fallout release of radioactive particles into the atmosphere. Results from industrial processes or accidents, and the testing or use of nuclear weapons.
radioactive source a radioactive substance sealed, in a capsule, which, when inserted into the body, delivers a predetermined dose of radiation.
radiobiology the study of the effects of radiation on living organisms. The use of radioactive tracers to study biological processes.
radiocarbon a radioactive form of the element carbon, such as carbon-14 (14C), used for investigations, for example, absorption tests and research.
radiodermatitis skin inflammation caused by exposure to ionizing radiation.
radiograph a photographic image formed by exposure to X-rays; the correct term for an ‘X-ray’.
radiographer there are two distinct professional disciplines within radiography, diagnostic and therapeutic; they are health professionals qualified in the use of ionizing radiation and other techniques, either in diagnostic imaging or radiotherapy.
radiographic contrast the photographic differences between two adjacent areas on a film.
radiography the use of X-radiation (a) to create images of the body from which medical diagnosis can be made (diagnostic radiography); or (b) to treat a person suffering from a (malignant) disease, according to a medically prescribed regimen (therapeutic radiography). See also radiotherapy.
radioimmunoassay the use of radioactive substances to measure the amount of concentration of an antigen, antibody or protein or substances such as hormones and drugs in the blood.
radioiodinated human serum albumin (RIHSA) used for detection and localization of brain lesions, determination of blood and plasma volumes, circulation time and cardiac output.
radioisotope (radionuclide) any isotope that is radioactive. Forms of an element which have the same atomic number but different mass numbers, exhibiting the property of spontaneous nuclear disintegration. When taken orally or by injection, can be traced by a Geiger counter.
radioisotope scan pictorial representation of the amount and distribution of radioactive isotope present in a particular organ.
radiolabel the modification of a substance to make it radioactive so that it can be used to target a particular organ or body part so that it can be detected in radionuclide imaging.
radiologist a medical specialist in diagnosis by using X-rays and other allied imaging techniques.
radiology the study of the diagnosis of disease by using X-rays and other allied imaging techniques.
radiolucent a substance that has minimal effect on an X-ray beam and therefore the beam does not change as it passes through the substance.
radiomimetic exerting effects similar to those of ionizing radiation, for example, nitrogen mustards.
radionecrosis tissue death caused by radiation.
radionuclide (radioisotope) any nuclide that is radioactive. Forms of an element which have the same atomic number but different mass numbers, exhibiting the property of spontaneous nuclear disintegration. When taken orally or by injection, can be traced by a Geiger counter.
radionuclide generator a system containing a long-lived parent radionuclide which decays to a short-lived daughter radionuclide.
radionuclide therapy the introduction of a radionuclide either orally or by injection; this is then taken up by a targeted organ which receives a calculated radiation dose to maximize the dose of radiation to the treatment area in a patient and minimize the dose to normal tissue.
radiopaque having the property of significantly absorbing X-rays, thus becoming visible on a radiograph. Barium and iodine compounds are used, as contrast agents, to produce artificial radiopacity.
radiosensitivity the relative susceptibility of cells, tissues, organs, organisms, or any other substances to the effects of ionizing radiation.
radiosurgery (stereotactic radiotherapy) a radiotherapy treatment based on a 3D coordinate system designed to achieve a high concentration of absorbed dose to an intracranial target.
radiotherapist (oncologist) medical specialist in the treatment of disease by X-rays and other forms of radiation.
radiotherapy a method of treating disease and eradicating tumour cells by aiming to deliver a therapeutic dose of radiation while preserving normal tissue function and structure.
radiotracer the modification of a substance to make it radioactive so that it can be used to target a particular organ or body part so that it can be detected in radionuclide imaging.
radium (Ra) a radioactive element occurring in nature.
radius the lateral bone of the forearm.
radon seeds capsules containing radon – a radioactive gas produced by the disintegration of radium atoms.
raised intracranial pressure (RIP) an elevation in intracranial pressure is a serious situation. Causes include: tumours, intracranial haemorrhage, trauma causing oedema or haematoma and obstruction to the flow of cerebrospinal fluid. The features depend on the cause, but there may be headache, vomiting, papilloedema, fits, bradycardia, arterial hypertension and changes in the level of consciousness. See also benign intracranial hypertension.
RAM (Random Access Memory) the part of the memory of a computer which can be accessed by the user; the amount of RAM available determines how much data can be stored by the user.
randomized controlled trial (RCT) research study using two or more randomly selected groups: experimental and control. It produces high-level evidence for practice.
random sampling in research. The selection process whereby every person in the population has an equal chance of being selected.
random variable background factors such as environmental conditions that may affect any conditions of the independent variables equally. See also independent variable.
range describes the span of values (lowest – highest) observed in a sample.
range of motion (ROM) the movements possible at a joint.
rank in statistics, the method of organizing data.
raphe a seam, suture, ridge or crease.
rare earths metals having two electrons in the outer shell and either 8 or 9 electrons in the penultimate shell; they are used for the phosphors in television monitors, lasers and modern intensifying screens. Examples include lanthanum, europium, gadolinium, terbium, yttrium.
rarefaction less dense, as applied to diseased bone. In ultrasound the opposite of compression.
raster lines the lines formed when a beam of electrons scans a phosphor to form an image. See also phosphor.
rating the rating of an X-ray unit is the combination of exposure settings which can occur without unacceptably damaging the unit.
ratio data measurement data with a numerical score, for example, height, that has a true zero of 0. It is interval data with an absolute zero. See also interval data.
raw data original received information.
raw data matrix in magnetic resonance imaging it is the initial image before analysis. The points at the centre of the matrix represent areas of low spatial frequencies and the frequencies become higher the further away from the centre.
Rayleigh scattering see coherent scattering.
reactance the opposition to current flow and is produced by capacitors and inductors but not by resistors.
reactionary haemorrhage bleeding that occurs a few hours after an injury but within 24 hours; shock and/or drugs can inhibit the blood flow.
reactive arthritis (Reiter’s syndrome) arthritis that develops in response to infection, usually urogenital, gastrointestinal or throat infection. See also sexually acquired reactive arthritis.
real time a computer controlling, or recording, events as they are actually happening.
real time scanning a method of producing a moving image on a screen.
real-time ultrasonography an ultrasound imaging technique involving rapid pulsing to enable continuous viewing of movement to be obtained, rather than stationary images.
reasonable doubt to secure a conviction in criminal proceedings, the prosecution must establish beyond reasonable doubt the guilt of the accused.
receiver the part of the ultrasonic transducer that detects returning sound waves and converts them to electrical signals.
receiver bandwidth the measure of a range of frequencies within which a magnetic resonance system is tuned to receive the signal. Alteration affects the signal-to-noise ratio, by narrowing the bandwidth the ratio is increased and by broadening it the ratio is decreased.
receiver operating characteristics a method of measuring the ability of an observer to make a diagnosis.
receptaculum receptacle, often forms a reservoir.
receptor sensory afferent nerve ending capable of receiving and transmitting stimuli. A protein situated on or inside a cell membrane which reacts with various molecules, drugs, hormones or cell mediators.
recipient the individual who receives something from a donor such as blood, an organ such as a kidney or bone marrow.
reciprocity the ability to produce an accurate range of densities over a film which reflect the structure being imaged.
reciprocity failure seen with either very short exposures at high intensity or very long exposures at low intensity which do not produce the expected density on the film.
reciprocity law the amount of density produced on a film is dependent only on the total amount of light energy available.
recognition acuity the ability of an individual to recognize standard shapes.
reconstruction technique a method of forming an image from a set of measurements; in CT imaging this includes automatic corrections. See also iterative reconstruction algorithm.
recovery position a first aid measure in which a patient with an altered level of consciousness is positioned so that their airway is maintained and to prevent the inhalation of secretions or vomit.
rectified made unidirectional, when alternating current is modified so that current only flows in a positive direction. half-wave rectification the negative half of the cycle is suppressed. full-wave rectification the negative half of the cycle is made positive by the use of rectifiers.
rectifier a piece of equipment that allows current to flow in only one direction.
rectosigmoid associated with the rectum and sigmoid colon.
rectouterine associated with the rectum and uterus, as the rectouterine pouch.
rectovaginal associated with the rectum and vagina.
rectovesical associated with the rectum and bladder.
rectum the lower part of the large intestine between the sigmoid flexure and anal canal.
rectus abdominis abdominal muscle.
recumbent position lying on the back with the head supported on a pillow: the knees can be flexed and parted to facilitate inspection of the perineum.
recurrent (habitual) miscarriage when miscarriage occurs in three successive pregnancies.
recurring costs regular and ongoing costs, such as planned maintenance and staff salaries.
red muscle describes muscle consisting mainly of slow-twitch fibres. The red colour is derived from the plentiful blood supply and myoglobin.
redistribution during fractionated radiotherapy those cells that are not killed become more resistant to radiation, they try to change to the mitotic stage of the cell cycle so that they can repopulate.
reductase an enzyme that starts the reduction of an organic compound.
Reed–Sternberg cell a large, abnormal multinucleated cell found in the lymphatic system in Hodgkin’s disease.
referred pain pain occurring at a distance from its source, for example, pain felt in the upper limbs from angina pectoris; that from the gallbladder felt in the scapular region.
reflection to throw back light or radiation, X and γ radiation cannot be reflected.
reflective layer the layer between the base and the phosphor layer in an intensifying screen whose function is to reflect light towards the film.
reflex literally, reflected or thrown back; involuntary, not controlled by will.
reflex action an involuntary motor or secretory response by tissue to a sensory stimulus, for example, tendon stretch, sneezing, blinking, coughing. Reflexes may be postural or protective. Testing reflexes provides valuable information in the localization and diagnosis of neurological diseases. See also accommodation reflex, conditioned reflex, corneal reflex.
reflux backward flow. See also vesicoureteric reflux.
refraction the bending of light rays as they pass through media of different densities. In normal vision, this occurs so that the image is focused on the retina.
refresh rate the rate at which an electron beam scans the whole of a computer screen.
regional ileitis see Crohn’s disease.
regression techniques various analytical methods used in multivariate statistics. Used to predict dependent variable(s) from independent variable(s).
regulation in a transformer is caused by resistance in the windings, if the electric load from the secondary winding is increased a higher current flows in the secondary winding but the potential difference across the secondary winding is decreased. percentage regulation a calculation to determine the efficiency of a transformer, the lower the percentage the more efficient is the transformer.
regurgitation backward flow, for example, of stomach contents into, or through, the mouth, or blood through an incompetent (regurgitant) heart valve.
rehabilitation to restore normal function.
Reiter’s syndrome sexually acquired reactive arthritis.
reject analysis the examining of images that have been judged to be unacceptable to try to find out why the films have been rejected and whether it is due to equipment or operator problems.
related in statistics the data are matched – each sample has a matched sample with one or more than one variable in common.
relaxant a drug or technique that reduces tension. See also muscle relaxant.
relaxin polypeptide hormone secreted by the placenta and ovaries to soften the cervix and loosen the ligaments in preparation for birth.
relay an electrical switch in which one circuit is controlled by another ciruit.
reliability in research, a term meaning consistency of results. The likelihood of achieving the same findings using the same research conditions over a period of time or with different researchers.
remark instruction ignored by the computer, but enables the user to add comments in plain English.
remission the period of abatement of a fever or other disease.
renal arteriography the demonstration of the renal arteries following the injection of a contrast agent into the femoral artery.
renal calculus stone in the kidney.
renal erythropoietic factor (REF) a substance released by the kidneys in response to renal (and therefore systemic) hypoxia. Once secreted into the blood, it reacts with a plasma protein to produce erythropoietin.
renal failure can be described as acute or chronic. acute renal failure (ARF) occurs when previously healthy kidneys suddenly fail because of a variety of problems affecting the kidney and its perfusion with blood. This condition is potentially reversible. ARF is treated by haemofiltration or haemodiafiltration until kidney function improves. chronic renal failure (CRF) occurs when irreversible and progressive pathological destruction of the kidney leads to end-stage renal disease (ESRD). This process usually takes several years but once ESRD is reached, death will follow unless the patient is treated with some type of renal replacement therapy such as dialysis, or renal transplant. See also acute tubular necrosis, uraemia.
renal function tests kidney function tests.
renal glycosuria occurs in patients with a normal blood sugar and a lowered renal threshold for glucose.
renal transplant kidney transplant.
renal tubule part of a nephron.
renin an enzyme released by the kidney (juxtaglomerular apparatus) in response to low serum sodium or low blood pressure. Renin starts the angiotensin-aldosterone response. A plasma protein (angiotensinogen) is activated to produce angiotensin I, which in turn is converted into angiotensin II.
rennin milk curdling enzyme found in the gastric juice of human infants and ruminants. It converts caseinogen into casein.
renogram radioisotope study of the kidney.
renography a method of assessing the output and function of the kidneys in radionuclide imaging by producing time–activity curves.
reoxygenation the process when tumour cells gain access to oxygen which is released when cells are killed with low-energy transfer radiations – for example, between radiotherapy fractions. If the cells receive oxygen they are more likely to be killed during the next dose of treatment.
repair cells injured during radiotherapy attempt to repair themselves; healthy tissue is quicker than tumour cells in achieving the repair.
repetition time in magnetic resonance imaging, the time between the beginning of one radio frequency pulse sequence to the start of the next.
repetitive strain injury (RSI) a misleading term used to describe diffuse pain and inflammation randomly occurring in the hand and forearm arising from repetitive activities in the workplace, aggravated by static posture.
replenishment the addition of an amount of developer and fixer to the processing tank every time a film is processed to maintain the activity of the solutions.
repolarization the process whereby the membrane potential returns from the depolarized state to its polarized resting (negative) state.
repopulation the re-growth of tissue cells, during fractionated radiotherapy normal tissue cells can regenerate at a faster rate than the tumour cells therefore reducing the side effects of the treatment.
reproductive system the structures necessary for reproduction. In the male it includes the testes, deferent ducts (vas deferens), prostate gland, seminal vesicles, urethra and penis. In the female it includes the ovaries, uterine tubes, uterus, vagina and vulva.
research systematic investigation of data, reports and observations to establish facts or principles, in order to produce organized scientific knowledge.
research design how a research study is to be undertaken such as data collection method, statistical analysis, etc.
residual air the air remaining in the lung after forced expiration.
residual thiosulphate test a method of assessing the archival permanence of a film by dropping a drop of solution on the film and comparing it with a colour chart.
residual urine the volume of urine remaining in the bladder after micturition.
resistance the impedance to the flow of electrons; it is measured in ohms.
resistivity index the ultrasonic method of numerically determining the resistance of blood flowing through a vessel by using the equation systolic – diastolic/mean.
resistor an object which opposes the flow of electrons; resistors in series are placed end to end, resistors in parallel are connected parallel to each other.
resolution indicates the size of the smallest object that a system will record and the smallest distance that must exist between two objects before they are seen as two separate objects. It is expressed as line pair per millimetre. In ultrasound the ability to distinguish between two adjacent structures, the higher the frequency of the probe the better the resolution.
resonate mechanically deform, vibrate.
resorption the act of absorbing again, for example, absorption of (a) callus following bone fracture, (b) roots of the deciduous teeth, (c) blood from a haematoma.
respiration the gaseous exchange between a cell and its environment. See also abdominal breathing, Cheyne–Stokes respiration, paradoxical respiration.
respirator equipment to qualify the air breathed through it. A device for giving artificial respiration or to assist pulmonary ventilation.
respiratory failure failure of the lungs to oxygenate the blood adequately.
respiratory quotient the ratio between inspired oxygen and expired carbon dioxide during a specified time.
respiratory rate number of breaths per minute, normally 20 in an adult.
respiratory system deals with gaseous exchange. Comprises the nose, nasopharynx, larynx, trachea, bronchi and lungs.
restrainer a chemical to improve the selectivity of a solution; in the developer solution either benzotriazole or potassium bromide is used to ensure low fog and high image contrast.
resuscitation restoration to life of one who is collapsed or apparently dead. See also cardiopulmonary resuscitation.
retching straining at vomiting.
retention of urine inability to pass urine.
reticule a thin plastic tray holding lead markers which are positioned to delineate the geometry of the radiotherapy treatment field and a set treatment distance.
reticulocyte an immature circulating red blood cell which still contains traces of the nucleus. Accounts for up to 2% of circulating red cells.
reticulocytosis an increase in the number of reticulocytes in the blood indicating active red blood cell formation in the marrow. See also reticulocyte.
reticuloendothelial system (RES) see monocyte–macrophage system.
retina layer of tissue in the eye that converts light into electrical signals. Consists of a multiple-layer complex of neurosensory retina containing nerve cells including photoreceptors (rods and cones), and a layer of pigmented cells beyond the neurosensory retina.
retinoblastoma a rapidly growing, congenital, hereditary, malignant tumour arising from the retinal germ cells in the eye, occurs exclusively in children.
retinol also known as retinene. A light-absorbing molecule formed from vitamin A. It combines with a protein (opsin) to form rhodopsin (visual pigment).
retractile capable of being drawn back, i.e. retracted.
retraction a backward movement. See also protraction.
retrocaecal behind the caecum.
retroflexion the state of being bent backwards. See also anteflexion.
retrograde going backward. retrograde urography/pyelography. See also urography.
retrograde ejaculation a situation where semen is discharged backwards into the bladder. It may follow prostate surgery or be associated with diabetic neuropathy.
retrograde pyleograph the radiographic investigation of the renal tract when excretion urography has failed. A catheter is introduced into the renal pelvis via the urethra to enable the introduction of a contrast agent.
retroperitoneal behind the peritoneum.
retropharyngeal behind the pharynx.
retrospective study research that deals with past data, moving backwards in time. See also prospective study.
retrosternal behind the sternum.
retrotracheal behind the trachea.
retroversion turning backward. See also anteversion.
retroversion of the uterus tilting of the whole of the uterus backward with the cervix pointing forward.
revenue budget the budget allocation for day to day running costs, for example, salaries, telephone, electricity and drugs, etc. See also capital budget.
reverberation in ultrasound when multiple repeat echoes which are produced when two strong reflectors lie parallel to each other.
reverse barrier nursing (protective isolation) involves separating patients who are immunocompromised and susceptible to infection, either by disease or treatment. The type of patients needing protection from infection include those with leukaemia, those having immunosuppressant treatment for organ transplantation, chemotherapy or radiation or neutropenic patients. See also containment isolation, source isolation.
reverse bias is when a battery is connected across a PN junction, the potential barrier is raised as current flow is stopped until the barrier breaks down. Opposite forward bias.
RGB (Red, Green and Blue) input to a computer colour monitor.
rhabdomyosarcoma a highly malignant tumour derived from striated muscle cells.
rheumatic associated with rheumatism, a non-specific term.
rheumatic diseases a diverse group of diseases affecting connective tissue, joints and bones. They include: inflammatory joint disease, for example, rheumatoid arthritis, septic arthritis and gout; connective tissue disease, for example, systemic lupus erythematosus; osteoarthritis; non-articular/soft tissue rheumatism, for example, fibromyalgia. rheumatic heart disease (RHD) chronic cardiac disease with valve damage resulting from rheumatic fever.
rheumatic fever an inflammatory disease which may be due to an inadequately treated infection, can affect the joints and can lead to long-term heart problems.
rheumatism a non-specific term embracing a diverse group of diseases and syndromes which have in common disorder or diseases of connective tissue and hence usually present with pain, or stiffness, or swelling of muscles and joints. Used colloquially to describe ill-defined aches and pains. See also rheumatic diseases.
rheumatoid arthritis a disease of unknown aetiology, characterized by polyarthritis usually affecting firstly the smaller peripheral joints, before extending to involve larger joints accompanied by general ill health and resulting eventually in varying degrees of joint destruction and deformity with associated muscle wasting. It is not just a disease of joints; and most body systems can be affected, for example, lung, peripheral nerves. Many rheumatologists therefore prefer the term ‘rheumatoid disease’. There is some question of it being an autoimmune process.
rheumatoid factors autoantibodies found in most people with rheumatoid arthritis. It is not yet known whether they are the cause of, or the result of, arthritis.
rheumatoid pneumoconiosis fibrosing alveolitis occurring in patients suffering from rheumatoid arthritis. See also anthracosis, asbestosis, byssinosis, siderosis silicosis.
rheumatology the science or the study of the rheumatic diseases.
rhinosinusitis inflammation of the nose and paranasal sinuses.
rhodopsin the visual purple (pigment) found in the rods. Required for vision in low-intensity light. Its colour is maintained in darkness; bleached by daylight. Vitamin A is needed for its formation.
ribonuclease an enzyme that breaks down ribonucleic acid.
ribs the twelve pairs of bones which articulate with the twelve dorsal vertebrae posteriorly and form the walls of the thorax. The upper seven pairs are true ribs and are attached to the sternum anteriorly by costal cartilage. The remaining five pairs are the false ribs; the first three pairs of these do not have an attachment to the sternum but are bound to each other by costal cartilage. The lower two pairs are the floating ribs which have no anterior articulation. cervical ribs are an extension of the transverse process of the seventh cervical vertebra in the form of bone or fibrous tissue; this causes an upward displacement of the subclavian artery.
rickets bone disease caused by vitamin D deficiency during infancy and childhood (prior to ossification of the epiphyses) which results from poor dietary intake or insufficient exposure to sunlight. There is abnormal metabolism of calcium and phosphate with poor ossification and bone growth. There is muscle weakness, anaemia, respiratory infections, bone tenderness and pain and hypocalcaemia. Delays occur in motor development such as walking, eruption of teeth and closure of the fontanelles. Later there may be bony deformities, for example, bow legs. Rickets may be secondary to vitamin D malabsorption, or impaired metabolism, such as with chronic renal failure. The same condition in adults is known as osteomalacia.
rickety rosary a series of protuberances (bossing) at junction of ribs and costal cartilages in children suffering from rickets.
rider’s bone a bony mass in the origin of the adductor muscles of the thigh, from repeated minor trauma in horse riding.
right anterior oblique a radiographic projection with the patient either erect or semi prone at 45° to the film with the right side of the body closest to the film and the left side away from the film (see figure on p. 332).
right colic (hepatic) flexure the bend between the ascending and transverse colon, beneath the liver.
right posterior oblique a radiographic projection with the patient either erect or semi supine at 45° to the film with the right side of the body closest to the film and the left side away from the film (see figure on p. 332).
rights the recognition in law that certain inalienable rights, such as the right to life, should be respected, for example, Human Rights Act 1998.
Right posterior oblique (RPO).
From Pocketbook of radiographic positioning, 2nd edn, Ruth Sutherland, 2003, Churchill Livingstone, Edinburgh, with permission.
rigid pes planus in adults, abnormality of the foot may be a progression from flexible to semi-rigid to rigid as part of the ageing process. Structural changes due to the existing abnormal position become fixed, as soft and osseous tissues adapt. Rigidity is increased where there are significant osteoarthritic changes or inflammatory arthritic destruction.
ripple bed a mattress where alternate sections fill and then empty automatically to prevent decubitus ulcers.
RIS (Radiology Information System) a computer system specifically for imaging departments which enables the booking and planning of work for inpatients and outpatients, the identification of suitable tests, the management and reporting of images and the transmission of information back to the ward or individual requesting the services.
risk assessment a structured and methodical assessment of risk carried out for a particular area or activity. For example moving and handling patients in the operating theatre.
risk factors factors associated with an increase in the likelihood of ill health, disease, handicap or disability. Demonstration of the association has to fulfil Sir Austin Bradford Hill’s eight criteria (for example, smoking and lung cancer): (a) biological plausibility—tobacco tar contains known carcinogens, the stages of tumour development following exposure are clearly demonstrated, (b) reversibility—smoking cessation reduces subsequent increase in risk of lung cancer by half in the first year, to nil after 10 years, (c) animal demonstration—model of beagles in laboratory experiments, (d) dose response—risk of lung cancer in smokers shown to increase progressively with the number of cigarettes smoked per day, (e) follows exposure—temporal relationship demonstrated, lung cancer always follows exposure to cigarettes with a time lag of 20 to 30 years, (f) over time and overseas—relationship consistent between different case series and different places (in the world), (g) experimental design—must be reliable. Randomized controlled trials most convincing, but may be unethical. Observational studies (case control, cohort) useful if correctly carried out. (h) strength of the effect—the larger the increase in risk, the more likely the causal relationship.
risk management managing risk in healthcare settings involves: identification of the risk, analysis of the risk and controlling the risk.
ROA (right occipitoanterior) used to describe the position of the fetus in the uterus.
rodent ulcer a basal cell carcinoma often seen on the face which, although locally invasive, does not give rise to metastases.
rods photoreceptors in the retina for appreciation of coarse detail vision in low light conditions. They contain the visual pigment rhodopsin.
Rolando’s fracture a fracture of the base of the first metacarpal.
ROM (Read Only Memory) the pre-programmed part of the computer which enables it to run programs.
root the part of a tooth that lies below the gum.
root filling the removal of the root of a tooth which is then filled and forms the base for an artificial crown.
rooting reflex a primitive reflex present in newborns. The infant will turn his or her head to that side when the cheek is touched.
ROP (right occipitoposterior) used to describe the position of the fetus in the uterus.
rotating anode part of an X-ray tube that is made of a molybdenum disc with a tungsten/rhenium focal tract embedded in it; the positive anode rotates during exposure to enable higher intensities of X-rays than a stationary anode tube due to the larger surface allowing more heat to be deposited and then dissipated.
rotating jig in radiotherapy, a method of determining the contour of a shell. The shell is supported on 4 pins and the 5th pin rotates around an axis at right angles to the plane and scaled in degrees of rotation and centimetres. The contour can then be plotted on polar graph paper.
rotation a limb movement around the axis down the centre of a long bone.
rotation therapy a technique when the source of the radiation is moved through an angle of 360° during treatment.
rotator a muscle that acts to turn a part.
rotator cuff four muscles; subscapularis, supraspinatus, infraspinatus and teres minor. Their tendons converge to form a cuff over the shoulder joint. Controls and produces rotation of the shoulder.
round ligaments uterine supports that run from the uterus, through the inguinal canal, to the labia majora.
router computer equipment that connects computer networks together; it is more powerful than a hub, for example, used to allow access to a single internet connection (phoneline).
RS 232 a type of standard interface between computer and peripheral, defining the plug and socket sizes and how the data are transmitted between the computer and peripheral.
rubor redness: one of the five classic local signs and symptoms of inflammation, the others being dolor, loss of function, calor and tumor.
ruthenium-90 an isotope contained in a silver applicator with a window thickness of 0.1 mm, attached to the sclera for 7–10 days and used to treat the eye.
