Colour Engineering. Achieving Device Independent Colour. Wiley: Fill & Download for Free

For those of us who think they know anything about physics. This Question was refering to if you give a theorum to the patent office to get patented. Einstein had access to patents that were unreleased because he was a patent clerk that helped people patent their ideas and make them public. Hence the unpublishing notion.Einstein saw ideas before others did.So getting back to physics.Please allow me to introduceJames Clerk Maxwell: a force for physics01 Dec 2006Born 175 years ago, James Clerk Maxwell carried out the first profound unification of nature’s forces. Francis Everitt examines the immense contributions of the greatest mathematical physicist since NewtonDeserving recognitionUnless one is a poet, a war hero or a rock star, it is a mistake to die young. James Clerk Maxwell – unlike Isaac Newton and Albert Einstein, the two giants of physics with whom he stands – made that mistake, dying in 1879 at the age of just 48. Physicists may be familiar with Maxwell, but most non-scientists, when they switch on their colour TVs or use their mobile phones, are unlikely to realize that he made such technology possible. After all, in 1864 he gave us “Maxwell’s equations” – voted by Physics World readers as their favourite equations of all time – from which radio waves were predicted.Suppose Maxwell had lived one year beyond the biblical three score and ten. He would then have been alive on 12 December 1901, the day when Guglielmo Marconi, in St John’s, Newfoundland, received the first transatlantic radio signal from a transmitter in Cornwall, UK, designed by Maxwell’s former student Ambrose Fleming. Or consider relativity: mention it and everyone thinks of Einstein. Yet it was Maxwell in 1877 who introduced the term into physics, and had noticed well before then how the interpretation of electromagnetic induction was different depending on whether one considers a magnet approaching a wire loop or a loop approaching a magnet. It was from these “asymmetries that do not appear to be inherent in the phenomena” that Einstein began his work on special relativity.Had he not died so young, Maxwell would almost certainly have developed special relativity a decade or more before Einstein. Moreover, it was through reading Maxwell’s article “Ether” in the ninth edition of the Encyclopaedia Britannica that Albert Michelson came to invent the interferometer – a new kind of instrument that he and Edward Morley used in 1887 to discover that the speed of light is the same in all directions.A man for all scienceSo what impression of Maxwell would you have gained if you had met him in his prime, as a young Scottish undergraduate Donald MacAlister did in Cambridge in 1877? You would surely have been charmed, but perhaps also surprised to meet – as MacAlister put it – “a thorough old Scotch laird in ways and speech”. As the proprietor of an 1800 acre Scottish estate, Maxwell had all the qualities of the better kind of Victorian country gentleman: cultivated, considerate of his tenants, active in local affairs, and an expert swimmer and horseman too.Few would have guessed that this “Scotch laird”, so disarmingly old-fashioned even in 1877, was a scientist whose writings remain astonishingly vibrant in 2006 and the greatest mathematical physicist since Newton. In addition to his work on electromagnetism, Maxwell also contributed to eight other scientific spheres: geometrical optics, kinetic theory, thermodynamics, viscoelasticity, bridge structures, control theory, dimensional analysis and the theory of Saturn’s rings. He also worked on colour vision, producing the first ever colour photograph (see box “A colourful tale”).A taste of geniusEven if his achievements are somewhat overshadowed in the public’s eye by those of Einstein, whose successes were marked by a great series of events last year, it is a measure of Maxwell’s standing that 2006 – the 175th anniversary of this birth – has been dubbed Maxwell Year.From Glenlair to EdinburghJames Clerk Maxwell was born on 18 June 1831 to Frances Cay and John Clerk – a lawyer who was the younger son of James Clerk. The Clerks were one of the most distinguished and wealthiest families in Edinburgh and both of Maxwell’s parents were steeped in the city’s culture. Yet Maxwell spent the first 10 years of his life on a country estate, Glenlair in south-west Scotland, which was then a region of extreme isolation, even lawlessness, with no nearby school. How did this happen and why do we refer not to Clerk’s equations but to Maxwell’s equations?The answer lies in a long blood-feud between the Maxwell family and another Scottish family – the Johnstones – that dates back to the 16th century. The feud included the execution in 1613 of the eighth Lord Maxwell for the murder of the chief of the Johnstones in revenge for their killing of his father. Lacking legitimate children, Lord Maxwell bequeathed land to his illegitimate son, John Maxwell, who was himself murdered in 1639. The marriage of two of the latter’s heiresses to members of the Clerk family resulted, following complex legal settlements, in the 7000 acre Clerk estate near Edinburgh being handed down in 1798 to George Clerk (James Clerk Maxwell’s uncle) and the Maxwell name and estate to John Clerk (Maxwell’s father).Mechanical modelAfter Maxwell’s parents got married, they began developing the estate at Glenlair. But with no schools nearby and only one child to look after, his mother doubled as his schoolteacher. Her death when he was eight affected Maxwell deeply and, after two unhappy years with a private tutor, he was sent to Edinburgh Academy, where his weird accent and weirder shoes (hand made by his father) won him the nickname “Dafty”. Maxwell was also involved in a tug-of-war between two aunts over who should bring him up. Despite these setbacks, Maxwell survived and soon began to enjoy Edinburgh’s marvellous culture, especially after his father made time to come from Glenlair.Maxwell’s first scientific paper appeared when he was just 14, which suggests that he was a terrifying mathematical prodigy. In fact, Maxwell was a very clever boy but by no means exclusively scientific. Indeed, a poem of his was published in the Edinburgh Courant six months before his first scientific paper. He wrote the latter after meeting the decorative artist D R Hay, who was searching for a way to draw ovals. The 14-year-old Maxwell generalized the definition of an ellipse and succeeded in producing true ovals identical to those studied in the 17th century be René Descartes. Maxwell’s father showed the method to James David Forbes, an experimental physicist at Edinburgh University, who realized that it was correct. Forbes then presented the paper on Maxwell’s behalf at a meeting of the Royal Society of Edinburgh – a remarkable achievement for someone so young.Student daysMaxwell began his studies at Edinburgh University in 1847 at the age of 16. He moved to Cambridge in 1850 to take the mathematical Tripos, which lasted for three years and a term. This unusually long undergraduate career, which resulted from the different ages at which students in England and Scotland then went to university, proved entirely beneficial for Maxwell. At Edinburgh he gained a broad education centred on philosophy, while Cambridge gave him an excellent training in applied mathematics and the most gruelling examination system the wit of man has devised. At both, he encountered first-class minds.In his honourApart from Forbes, who gave Maxwell the run of his laboratory and encouraged his interest in colour, Edinburgh boasted Sir William Hamilton, professor of logic and metaphysics. (He should not be confused with the Irish mathematician William Rowan Hamilton.) Hamilton was a man of formidable learning, a genius at enlivening young minds, and who was famous for his teachings drawn indirectly from Kant on “the relativity of human knowledge”. However, he and Forbes were enemies; only in one place did they meet well – and that was in the mind of the young Maxwell.Cambridge, meanwhile, was home to William Hopkins – a great teacher who became Maxwell’s private tutor – as well as the world’s leading authority on optics, George Gabriel Stokes. There was also William Whewell, the supreme historian and philosopher of science who invented the word “physicist”. As one Cambridge friend recalled, Maxwell was “acquainted with every subject upon which the conversation turned. I never met a man like him. I do believe there is not a single subject on which he cannot talk, and talk well too, displaying always the most curious and out of the way information.”Like many clever undergraduates, Maxwell worked hard while pretending not to. However, in 1854 he just missed the coveted position of “senior wrangler” in the mathematics examination, coming second to E J Routh. Two years later Maxwell was made a fellow of Trinity College, Cambridge, before returning to Scotland in 1856 as professor of natural philosophy at Marischal College, Aberdeen, at the age of just 25. It was here that he married Katherine Mary Dewar, daughter of the principal of the college.In 1860 Aberdeen’s two colleges – Marischal and King’s – merged and Maxwell was one of the professors let go, with a pension of £40 a year. This was not a huge sum in those days, but he did have a private income of about £2000 a year from his estate so it was nothing to worry about. Maxwell moved south to King’s College, London, before “retiring” in 1865 to enlarge Glenlair House, write his Treatise on Electricity and Magnetism and become a Tripos examiner for Cambridge. In 1871, however, he returned to Cambridge full time as the first professor of experimental physics. It was here, with funding from the seventh Duke of Devonshire, that he created the Cavendish Laboratory, which opened in 1874. Under J J Thomson, Ernest Rutherford and their successors, the Cavendish was to become one of the greatest research centres in the world.The first grand unificationOn 5 January 1865, while at King’s, Maxwell ended a letter to his cousin Charles Cay about his latest scientific work with the casual remark, “I have also a paper afloat containing an electromagnetic theory of light, which, till I am convinced to the contrary, I hold to be great guns.” The judgment was correct. More than a new theory, this was a new kind of theory that entailed completely new views of scientific explanation, unifying as it did three different realms of physics – electricity, magnetism and light. This unification of nature’s basic forces is a goal that physicists are still working on today.Before Maxwell there had been huge progress in optics and electromagnetism but troubling questions remained in both fields. The wave theory of light, originated by Thomas Young and Augustin Fresnel, was in one sense a marvellous success, leading to a flood of new discoveries. But in another way it was a worrying failure. At least 11 alternative theories existed, each of which tried to explain Fresnel’s and other formulae in terms of an underlying ether, but, as Stokes proved devastatingly in 1862, every one of them was flawed. Part of the miracle of Maxwell’s theory was that it almost magically swept the troubles with those theories away.A different issue hampered electromagnetism, which had been discovered by the Danish physicist Hans Christian Oersted in 1820. Oersted had found that a compass needle brought near a current-carrying wire pointed at right angles to the direction of the current, which involved a twisting motion that could not be explained by any other force. Two explanations emerged. Ampère sought to reinterpret the twisting as an attraction of a more complex kind, while Faraday, who had shown that magnetism, the electric current and the resultant force on a body act perpendicularly to each other, took Oersted’s finding as an irreducible new fact.Faraday saw the “lines of force”, which are revealed by sprinkling iron filings on a sheet of paper held over a magnet, not only as geometrical lines but also, more daringly, as physical lines rather like stretched elastic bands with an extra sideways repulsion. For him, these physical stresses could be used to explain magnetic force. Maxwell developed both aspects of Faraday’s thinking, devising in his second paper in 1861 an “ether” full of tiny “molecular vortices” aligned with the lines of force. Like tiny spinning Earths, Maxwell reasoned, each vortex shrinks axially and expands sideways, giving just the stress patterns that Faraday had hypothesized (see image “mechanical model”). To explain how the vortices rotate, Maxwell envisioned smaller “gearwheel particles” meshing with the vortices.While emphasizing that this idea, especially the gearwheel particles, was speculative and not a real physical model, he nevertheless saw it as a useful way to understand electromagnetism. In a wire, the particles are free to flow and form an electric current. In space, they serve as counter-rotating idle wheels between vortices to make successive ones turn in the same direction. This machinery gave the right result; Maxwell had “explained” magnetic force in Faraday-like terms.Maxwell addressed the electric force – the crux of his discussion – after submitting two papers on the magnetic force for publication. The key issue was where the energy resides. Previous theories had assumed that the energy was located at or on magnets or electrically charged bodies. In Maxwell’s theory, however, the magnetic energy was in the surrounding space, or “field”, as he called it. The energy was, in other words, the kinetic energy of the vortices.Drawing on insights from William Thomson (the future Lord Kelvin), Maxwell proceeded to make his ether elastic, with the electric force being the result of the potential energy needed to distort the ether. Intrigued by the fact that an elastic ether ought to transmit waves, Maxwell decided to calculate the speed at which they would move in terms of electric and magnetic forces, doing the calculations while at Glenlair.On returning to London, he looked up the ratio for magnetic to electric forces, which had been determined experimentally in 1858 by the German physicist Wilhelm Weber. Weber had measured the ratio because it played an important, but not well understood, part in his own theory of electromagnetism. A velocity appeared in his theory also, but with a different numerical value that had no obvious physical meaning. Maxwell plugged Weber’s force ratio into his equations and discovered to his utter astonishment that the velocity exactly equalled the speed of light, which was then known experimentally to an accuracy of 1%. With excitement manifest in italics, he wrote, “We can scarcely avoid the inference that light consists in the transverse undulations of the same medium which is the cause of electric and magnetic phenomena.”Having made this epoch-making discovery, Maxwell moved from his visionary model to hard fact. In a paper that has a good claim to be the foundation of dimensional analysis, in 1863 he proved that the ratio of the magnetic and electric forces indeed contains a velocity that equals the speed of light, c. The importance of this result to physics is hard to overstate. Before Maxwell, c was just one velocity among many. Now it was privileged, pointing the way forward to Einstein and relativity.Maxwell’s vortex-ether began as an attempt at a mechanical explanation of Faraday’s magnetic stresses. Another person might have been tempted to improve and refine it. Maxwell saw that no such effort was necessary. He had by now assembled a series of equations relating electric and magnetic quantities; he could deduce wave propagation from them. Instead of explaining electromagnetism or light, he had connected these two apparently different classes of phenomena using equations that took two forms. The first, which appeared in his 1865 paper and again in his Treatise, consisted of eight groups of equations. The second, in 1868, contains the four equations that we now know as “Maxwell’s equations”. The differences are somewhat technical: the eight equations include the concept of a “vector potential” and the incorrectly named “Lorentz force law”. (Devotees of Ockham’s razor should notice a remark by Maxwell in his Treatise that “to eliminate a quantity which expresses a useful idea would be a loss rather than a gain in this stage of our inquiry”.)Maxwell’s theory predicted many new phenomena, such as radiation pressure. But its most remarkable consequence – as Maxwell at once realized – was that it pointed to the existence of an electromagnetic spectrum. This “great storehouse of nature” might contain other radiation of higher and lower frequencies, a thought that was vindicated over the next 30 years with the discovery of radio waves, X-rays and gamma radiation. As for relativity, Maxwell introduced Hamilton’s word, in the way that physicists now understand it, in his small book Matter and Motion of 1877. Poincaré read the work; Einstein learned of it from Poincaré; and the rest is history.From Saturn to glaciers and gasesMaxwell’s unification of electricity and magnetism was his greatest contribution to physics. But his longest ever paper concerned a different topic altogether: the nature of Saturn’s rings. In this paper, which Maxwell spent four years working on between 1856 and 1860, he showed that the rings of Saturn are not solid, liquid or gaseous but instead consist of vast numbers of independent particles. But why did he devote so much time to this particular topic?The answer is that while Maxwell was a gentleman, he did not lack competitive drive. Coming second to Routh in the Tripos examination of 1854 was a blow, so Maxwell immediately turned his attention to another prestigious award called the Smith’s prize, which several other second wranglers, including Kelvin, had won. However, for the first time in its 84-year history, the prize that year was divided, with Routh and Maxwell bracketed equal. Maxwell therefore decided to enter the recently established Adams’ prize, awarded once every three years and open only to Cambridge graduates.The topic for the 1856 award was the structure and stability of Saturn’s rings. It took Maxwell four years to solve the problem, but his dedication succeeded. He won the Adams’ prize with an essay that caused a stir and was a strong factor in his becoming a Tripos examiner himself six years later. Moreover, Maxwell became fascinated by the problem of dynamical stability in general. Indeed, in 1868 he decided to investigate the stability of a “speed governor” – a device that controls a motor’s rate of rotation – his paper on which was the first in the now vast field of control theory.Then came delicious irony. Maxwell was appointed examiner of the 1877 Adams’ prize, the topic was dynamical stability and the winner was Routh, who derived, amid much else, a fundamental stability condition now known as the Routh–Hurwitz criterion.Maxwell, together with Ludwig Boltzmann and Willard Gibbs, also created the science of statistical mechanics. His work in this area began in 1859, when he read a highly original paper by Rudolf Clausius on colliding gas molecules. However, Maxwell went much further, first obtaining a statistical law governing the distribution of velocities in the gas and then determining many properties of gases that previously were impossible to calculate. One was viscosity, which he found should remain constant over a wide range of pressures. This unexpected result was confirmed by Oskar Meyer and by Maxwell and his wife, she doing nearly all of the experimental work. In particular, she discovered that viscosity increases almost linearly with temperature, rather than as the square root of temperature as the original theory predicted.In attempting to understand this puzzle, Maxwell made one of the most spectacular intellectual leaps in physics, which took him from gases to glaciers and back. Rudolf Clausius, picturing molecules as billiard balls, had assumed that they travel a certain average distance, known as the “mean free path”, between collisions. But that picture turned out to be too simple. In practice, longer-range forces act between molecules, accounting for the different temperature dependences. A new approach was needed. Maxwell recalled that Forbes, while climbing in the Alps, had made extensive measurements of glaciers that showed that they move like liquids over long periods of time.Maxwell seized on this idea and introduced into physics, engineering and glaciology a far-reaching new concept known as the “relaxation time”: a glacier behaves like a solid at times shorter than the relaxation time, but like a liquid at longer times.Maxwell then showed mathematically that molecules in a rarefied gas bouncing from wall to wall also act like a solid. In other words, as pressure increases, a gas begins to behave like a fluid and has a relaxation time that increases with pressure. Clausius’ characteristic distance could therefore be replaced by a characteristic time, and Maxwell was able to develop the theory on a firm mathematical footing, which was later extended by Boltzmann.Present throughout, alas, was a problem. In his first paper on this subject, Maxwell had proved a neat theorem that stated that the average rotational and translational energies of molecules are equal. When used to predict the specific heats of gases, however, the theorem gave results that flatly disagreed with experiment. Deeply alarmed, Maxwell said in a lecture at Oxford in 1860 that this finding “overturns the whole theory”. Although this was not true, he had discovered the first breakdown of classical mechanics.Worse was to follow. When Boltzmann extended the theory, he established a much wider principle, equipartition, that applied to all modes of motion, internal and external, of molecules. A student at Cambridge in the 1870s vividly recalled Maxwell saying that “Boltzmann has proved too much”, explaining his remark with the observation that equipartition would apply to solids and liquids as well as gases. Only with the arrival of quantum mechanics was that anxiety transformed from difficulty to triumph.The issue of equipartition steadily worsened. In a review written in 1877 Maxwell examined and demolished every evasion advanced up to that time, concluding that nothing remained but to admit “the thoroughly conscious ignorance that is the prelude to every real advance in knowledge”. The answer – and new questions – came in 1900 with Planck’s quantum of action. Some 40 years after Maxwell’s alarming discovery of 1860, the prediction of the specific heat of gases and much else was explained by the fact that the energy is quantized. At the atomic and subatomic levels, equipartition does not hold.Maxwell’s legacyWhen Einstein visited Cambridge in the 1920s, someone remarked, “You have done great things but you stand on Newton’s shoulders.” His reply was, “No, I stand on Maxwell’s shoulders.”He was correct, but much else in modern physics also rests on Maxwell. It was after all Maxwell who introduced the methods that underlie not only Maxwell–Boltzmann statistics but the quantum-mechanical Fermi–Dirac and Bose–Einstein statistics governing photons and electrons. It was even he, in two innocent-seeming discussions in the 1870s, who first emphasized what we now call the “butterfly effect” – the fact that tiny differences in initial conditions can produce huge final effects, the starting point of chaos theory. In a similar vein, Maxwell’s scientific contributions have had dramatic effects on the future course of physics, notably the quest to unify nature’s fundamental forces. Sadly Maxwell died of cancer on 5 November 1879 and never lived to see the applications of radio or the demystifying of equipartition. But the power of his scientific insights lives on.A colourful taleFew people will be aware that James Clerk Maxwell produced the first ever colour photograph (left, of a tartan ribbon). But Maxwell had a life-long interest in optics and colour vision, beginning in 1849 when the Edinburgh University physicist David James Forbes spun a top with three adjustable coloured sectors. Both men knew that red, blue and yellow are primary colours. However, no combination of those colours produced grey. (Thomas Young knew this years earlier but that fact had been forgotten.)What was needed were red, blue and green. Improving Forbes’ top, Maxwell determined “colour equations”, which give quantitative measurements of the ability of the eye to match real colours. But since light conditions vary for different observers, Maxwell realized that a more sophisticated instrument than a top was needed, which led to him inventing an ingenious “colour box”. With it, he and his wife carried out detailed measurements of the variations of colour register across the retina for hundreds of observers – an achievement unmatched until the 1920s. On 17 May 1861 Maxwell gave a lecture on colour at the Royal Institution in London, during which he projected through red, green and blue coloured filters three photographs of a tartan ribbon taken through the same filters. This first-ever colour photograph was a surprisingly faithful reproduction of the original.At a Glance: James Clerk Maxwell• James Clerk Maxwell was born 175 years ago, in recognition of which 2006 has been dubbed Maxwell Year• A child prodigy, he studied at Edinburgh and Cambridge universities and was appointed professor at Marischal College, Aberdeen, 150 years ago, aged just 25• In 1865 Maxwell wrote down his famous equations, which related – or “unified” – electricity, magnetism and light for the first time• He played a key role in the development of statistical mechanics, paving the way for the development of quantum mechanics• Maxwell was a cultivated man who could speak on almost any intellectual topic, yet he also took a keen interest in the local affairs of his Scottish estateMore about: James Clerk MaxwellS G Brush, C W F Everitt and E Garber (ed) 1983 Maxwell on Saturn’s Rings (MIT Press)S G Brush, C W F Everitt and E Garber (ed) 1986 Maxwell on Molecules and Gases (MIT Press)C W F Everitt 1975 James Clerk Maxwell: Physicist and Natural Philosopher (Scribner)E Garber, S G Brush and C W F Everitt (ed) 1995 Maxwell on Heat and Statistical Mechanics (Lehigh University Press)P M Harman (ed) 1990–2002 The Scientific Letters and Papers of James Clerk Maxwell (three vols) (Cambridge University Press)B Mahon 2004 The Man Who Changed Everything: The Life of James Clerk Maxwell (Wiley)Francis Everitt is in the Hansen Experimental Physics Laboratory, Stanford University, US, e-mail [email protected]

Real-time locating systems (RTLS, also known as real-time location systems) have become an important component of many existing ubiquitous location aware systems. While GPS (global positioning system) has been quite successful as an outdoor real-time locating solution, it fails to repeat this success indoors. A number of RTLS technologies have been used to solve indoor tracking problems. The ability to accurately track the location of assets and individuals indoors has many applications in healthcare. This paper provides a condensed primer of RTLS in healthcare, briefly covering the many options and technologies that are involved, as well as the various possible applications of RTLS in healthcare facilities and their potential benefits, including capital expenditure reduction and workflow and patient throughput improvements. The key to a successful RTLS deployment lies in picking the right RTLS option(s) and solution(s) for the application(s) or problem(s) at hand. Where this application-technology match has not been carefully thought of, any technology will be doomed to failure or to achieving less than optimal results.State-of-the-art reviewReal-time locating systems (RTLS, also known as real-time location systems) are local systems for the identification and tracking of the location of assets and/or persons in real or near-real-time. An RTLS consists of specialised fixed receivers or readers (location sensors) receiving wireless signals from small ID badges or tags attached to objects of interest and/or persons, to determine where the tagged entities are located within a building or some other confined indoor or outdoor space (Figure 1). Each tag transmits its own unique ID. The tag ID is logged against the asset or person to which/whom it is attached. The tags periodically transmit their ID, and depending on the technology chosen, the system locates the tags (and therefore the tagged entities) within a few rooms on one of several floors or to a specific room or part of a room on a specific floor. When staff members require portable assets, they log onto the system at a workstation (or using a mobile device), identify where the closest available item is located, and go and get it.Figure 1figure1Basic components of an RTLS (modified from[1]).Full size imageRTLS location information typically does not include complete or continuous navigation details such as speed, direction, or spatial orientation of tracked assets and persons. Standards governing RTLS include ISO/IEC 24730 standards series, which describes a form of RTLS used by a subset of vendors, but does not cover the full range of RTLS technologies [2].Emergency first response, healthcare and hospitals [3–6], care homes [7] and even everyday home life (as an assistive technology, where applicable) can all potentially benefit by using an appropriate RTLS solution.RTLS components and technologiesIn an RTLS, the location engine software communicates with tags and location sensors to determine the location of tagged entities. The location engine relays this information to specialised middleware and applications. The middleware in an RTLS acts as the “plumbing” between the core RTLS components (tags, location sensors and location engine software) and a range of software applications capable of displaying and exploiting the real-time location and status information of tracked entities [1]. These latter applications vary from simple RTLS end-user interfaces for querying and displaying location information of tagged entities to more comprehensive integration into (or interoperability with) existing business/enterprise systems such as hospital ADT (admission, discharge and transfer) systems and HIS (hospital information systems and subsystems such as RIS (radiology information systems), operating room (OR) systems, bed management systems, etc.) via standards-based, open APIs (application programming interfaces) to enrich these systems with location information necessary for the completion of a variety tasks and process flow management operations [4, 8].The location engine, middleware and application software may run on the same computer or on different machines. These applications also often offer some kind of client interface such as a Web-browser-based or mobile interface [1].Tags can also be equipped with push buttons (or call buttons). These can be used as panic buttons for summoning emergency response. Whenever the person carrying the tag presses the panic button, the location engine raises an alert and provides the location of the individual who pressed the button. Another use of tags with push buttons is when they are attached to assets, staff can use the button to indicate or toggle asset status, such as ‘bed occupied by patient’ (hospital bed status) or ‘device in need of repair’, as appropriate [1].If a tag has voice-to-voice capability, it can be used to communicate with the individual carrying the tag based on his/her location. Buzzers (emitting sounds, recorded voice messages, or live messages), LEDs (light emitting diodes of different colours and blinking patterns), or LCD (liquid crystal display) screens (displaying text messages) can also be fitted on tags to communicate information or alerts to the person carrying the tag, to identify or locate an asset, and to communicate with the person who has the asset or is expected to check the asset [1].Location sensors too can be fitted with buzzers. Patient ID badges sometimes become buried in bed linen (when patients are discharged) and cannot survive the bed linen wash cycle. In this case, installing location sensors that can sound an alarm whenever badges are detected in laundry chutes could prove helpful [6].Various sensors can be incorporated in tags to gain information about the environment, the status of the person carrying the tag, or the tagged asset. For example, motion sensors in the tag can indicate whether the individual carrying it is moving, while a temperature sensor attached to a device can indicate whether that device is in optimum thermal operating conditions [1].Tags can also have connectors that connect to assets in order to communicate specific details about the asset or its operational state. For example, the tag can indicate not only where the tagged device is, but also whether it is powered on. Finally, tags can have writeable memory, e.g., to log and store some user and other data about the tagged asset [1].When tracking the physical location of an asset or an individual, depending on the needs of the application(s) at hand, we may want to know the absolute position (absolute coordinates, such as latitude, longitude and altitude), relative position (distance in three dimensions with reference to a fixed point, e.g., the nurse is standing at 10 metres north of the main entrance of the ward), or symbolic position (presence in a specific area, e.g., the surgeon is in operating theatre A, or presence near something or someone, e.g., the nurse is near patient B) [1].To meet the requirements of different applications, whether they need precise location or room-level location, various RTLS solutions are available that can report tag location at different resolutions [1]:Presence-based locating: RTLS returns tag location as to whether it is present in a given (relatively wide) area;Locating at room level: RTLS returns tag location as present in a specific room, e.g., if a nurse presses the panic button to summon security assistance in the event of a physical attack on her, the location engine reports the nurse’s exact room in the hospital to the security personnel;Locating at sub-room level: RTLS locates tag to a specific part of the room, e.g., in hospital rooms accommodating multiple patients, such as dual-bed rooms and larger wards, if a nurse is carrying a tag, the location engine can report how much time the nurse has spent by each patient’s bedside or cubicle;Locating at choke points: tag location is returned by a specific choke point (an entry or exit point, such as a ward entrance; it is assumed that individuals or assets move from one area to another through these points). By monitoring the time a tag was detected at specific points, one can also determine the direction the tag is moving;Locating by associating: tag location is returned as proximity with respect to another tag, e.g., if each patient in a hospital wears a tag and each IVF (intravenous fluid) pump has a tag, the location of a given IVF pump can be returned as present next to a specific patient (and for how long); andLocating precisely: the exact tag location is pinpointed precisely on a map of the world and/or a detailed indoor map/in a given building and reported as absolute or relative position as described above.It is worth noting here that business cases for true real-time systems are very rare. For most common RTLS applications, the requirement is to know where someone or something is located, when he/she or it is required. In this respect, the system needs to provide real-time location information simply when the information is needed and not continuously; it does not need to update the information every few milliseconds. In terms of cost, it may be cost effective to rationalise this issue when scoping a project. The question is why identify where assets are located each second when they only move once every 1–2 hours or days, in which case identifying where they are each minute would be more than adequate; the technology would also be less stressed and system costs are likely to be reduced.An RTLS can be realised using various technologies, including light, camera vision, infrared (IR), sound, ultrasound, Bluetooth, Wi-Fi, RFID (radio frequency identification; RFID tags can be either active, with a small power supply to send out a signal covering a range of up to 100 metres, or passive, with no power supply and activated by a scanning signal, which limits their range of detection to less than a metre), ZigBee [9], ultra-wideband (UWB), GPS (global positioning system) and Cellular, among other technologies [1, 10, 11]. Different technologies use different approaches, and each method supports different applications or solves a slightly different problem while introducing its own limitations, e.g., IR requires a clear line of sight for the tags and sensors to communicate, so if a badge worn by a patient is covered by a blanket or flipped around, the system might momentarily lose track of the patient [6].These technologies also vary in many aspects, such as the physical phenomena used for location detection, the tag’s form factor and that of the associated location sensors, power requirements/battery life, range, indoor versus outdoor applicability, installation and maintenance/scalability considerations (which also affect cost—[3, 8]), and cost vs. time and space resolution (or precision; for example, the physics of Wi-Fi radio frequency, which passes through walls, limit accuracy to floor level at best and certainly not room-level precision [3], but one should note here that not all applications will require the same or the highest levels of accuracy). Some technologies require additional location sensors, and some leverage existing infrastructures, such as electricity or Wi-Fi in the building [1, 3, 11]. Some tag properties might also be essential for certain applications, e.g., waterproofness/water resistance and whether tags could be autoclaved [8].In some systems, the tag being located actually computes its own position (tag self-positioning), while in other RTLS, the software that locates the tag is external to the tag (remote-positioning), or tag position is determined by recognising the location of a nearby tag (tag indirect-positioning) [1].In the end, all RTLS technologies share the common objective of determining the location of assets and individuals as precisely as is needed by the target application(s). Each technology will succeed in its own way, provided it has been carefully matched to suitable applications. However, where this application-technology match has not been carefully thought of, any technology will be doomed to failure or to achieving less than optimal results [12]. For certain applications, the use of ‘best of breed’ or blended RTLS solutions that incorporate complementary technologies such as IR and RFID can deliver levels of precision and flexibility that are unachievable by any single competing technology [3].RTLS applications in healthcareRTLS can be used to quickly locate healthcare staff in large facilities when a patient or other member of staff summons assistance during a medical emergency. RTLS can also be deployed to track the physical movement of patients to help ensure their safety, particularly in the case of Alzheimer’s and dementia patients. An RTLS can alert staff and pinpoint the location of a resident who wanders away from a pre-defined area or tries to leave the building, e.g., when a patient passes too close to an entrance or an exit. Automatic door locking may also be triggered in such cases, as appropriate [1]. (A related outdoor tracking application for Alzheimer’s patients using GPS is described in [13].)Because locating by associating can provide detailed data on who is near whom, it can be used to detect how long a nurse has attended to a patient. A similar low-cost system for care homes can record each time care assistants attend to residents in their rooms [1, 7]. Moreover, in older care homes, RTLS can provide information about residents’ mobility around the home (e.g., by computing the daily distance walked by each resident based on the distance between each sensor he/she passed by; the latter (distances between sensors) are stored in the computer system), which can be used as an indicator of residents’ overall well-being and in detecting problems, such as when an older resident has not left his/her room or visited a toilet within a pre-set period of time [7].Tracking patient flows for throughput management can help diagnose bottlenecks and tailor (and monitor the implementation of) appropriate solutions for problems such as extended waiting times, overcrowding and boarding in outpatient clinics, emergency departments/rooms (ED/ER) and post-anaesthesia care units (PACUs); bumped and late surgeries; and the lack of available routine inpatient and intensive care unit (ICU) beds [1, 5, 14, 15].Monitoring patient flow or movement (handoffs) between departments, e.g., transfer from ED to radiology department, is accomplished by giving each patient a unique tag to always carry with him/her. The time spent by patients in each location is logged by an analytic application. By monitoring the time patients spend in various rooms and departments around the hospital, the hospital management can decide whether they need to allocate more staff or equipment at different departments and stages of the patient’s journey [1].Moreover, an RTLS can directly decrease patient waiting and transfer times by reducing the time needed to find staff or to locate a wheelchair, for example, to transport the patient. Using an RTLS also allows quickly locating equipment that is due for maintenance, testing or inspection, as well as a closer synchronisation of housekeeping (bed cleaning) with patient discharge, enabling faster bed turnaround rates as part of a hospital bed management system. The latter can track real-time notifications of patient or bed status (such as occupied, available, assigned, discharge ordered, cleaning, or not in service, etc.), enabling faster transport of patients and faster housekeeping [1, 16].Laskowski-Jones [6] and Whalen in [15] report impressive RTLS-enabled workflow efficiencies, including quantifiable significant cuttings in ED wait times, length of stay (LOS) and ‘left without being seen’ (LWBS) rates (actual figures for wait times, LOS and LWBS rate reductions can be found in [6, 15]). The value of the intelligence gleaned from RTLS patient flow data can be maximised by combining it with ‘lean production system principles’ (pioneered by Toyota Motor Corporation) to optimise patient flows [6, 17–19]. Other benefits of patient flow tracking and optimisation include fewer ambulance diversions and higher patient satisfaction ratings [5], which can translate into improving the care facility’s perception and reputation.Tracking expensive or shared equipment, such as ICU ventilators and intravenous (IV) pumps [20], can save time and money, and reduce equipment theft and accidental loss [1]. Hospitals are often large institutions, and personnel often find it difficult to locate portable equipment when it is required (Table 1 lists some examples of portable hospital equipment). Because personnel find it difficult to locate portable equipment when they need it, they sometimes “hide” (or “hoard”) it, so that they may find it when required; this practice exacerbates the problem.Table 1 Examples of acute care hospital mobile assetsFull size tableEstimates indicate that hospitals will purchase 10% to 20% more portable equipment than actually required for operational needs, so that staff may find it when needed. Let us assume the example of a hospital originally planning to procure 600 IV pumps at GBP £3,250.00 each (total: GBP £1,950,000.00). With the deployment of a suitable RTLS, these figures can be reduced to 530 IV pumps for a total cost of GBP £1,722,500.00. This is a saving of GBP £227,500.00. Now, if the investment in the RTLS has cost GBP £97,000.00, the final savings after investment will be GBP £130,500.00, a 134.5% ROI (return on investment) with immediate payback time. For more expensive equipment such as ICU ventilators, the ROI can be much greater, even when assuming a 50% depreciation value of purchased equipment (which cuts RTLS savings to half).Lower capital expenditure will also result in a reduction in the cost of depreciation (where applicable), and fewer assets (530 instead of 600 IV pumps in the above example) will translate into a proportionate reduction in storage and maintenance needs and costs. Furthermore, with an RTLS, medical personnel spend less time looking for equipment, thus increasing efficiency and productivity, as well as staff (and patients’) satisfaction.By deploying RTLS to locate IVF pumps, one can also track whether members of staff are complying with regulations regarding proper disinfection between uses by different patients. To quantify the benefits of deploying such an application, one can consider the industry average costs spent and negative effects on reputation in case a violation citation is received [1].Compliance with hand hygiene protocol in hospitals can significantly minimise the risk of nosocomial infections. RTLS can be used as a low cost method for recording when members of staff use hand sanitation stations before and after they enter and leave rooms and wards. When a member of staff uses a hand washing station, a nearby electromagnetic field emitter (exciter) triggers the personal badge tag (active RFID) worn by the caregiver to transmit a ‘hand washing event’ message that identifies the caregiver and the time that the specific dispenser was used. The system is not used to micromanage individual members of staff, but is rather used as a hospital infection control measure to identify individuals and groups who may need additional training or education.RTLS has the potential of improving the productivity of nurses and caregivers and hence their job satisfaction levels by reducing many mundane and repetitive tasks that staff encounters on a daily basis. For example, a nurse or a caregiver typically has to manually cancel a call (register that it has been answered), but an RTLS can perform the same task automatically by recognising the nurse’s presence in the room. RTLS can also cut the time staff has to spend to check the status of rooms and beds and also improve a patient’s family/visitors’ satisfaction by increasing their awareness of patient location [1].An RTLS can be deployed as an important component of a comprehensive hospital security solution. Instances of physical and verbal abuses of nurses and other members of staff (by abusive patients, visitors and other staff) in healthcare facilities, especially psychiatric hospitals, are not uncommon. RTLS can improve the safety of staff and nurses by giving them a means to request emergency assistance during crisis situations. Moreover, tracking personnel also alleviates security concerns by monitoring unauthorised access in restricted areas [1]. However, RTLS can be perceived as ‘big brother’. It is therefore important to promote its operational benefits to stakeholders prior to implementation and include appropriate checks to ensure their privacy is not infringed.In 2001, the second author was involved in an RTLS deployment at a major London hospital which failed. The project was to install a nurse call/nurse tracking system within a new wing in the hospital. The scope of the project in the beginning was to improve safety procedures for nurses within the hospital. It had been noted that physical attacks and verbal abuse of nurses was occurring almost daily. In order to address this, hospital management decided to implement a system that enabled the nurses to raise an alarm and alert security personnel to nurse’s precise location when an incident occurred. The hardware was installed in the new wing and the nurses were issued each with an ID badge; the badges were fitted with a distress button and transmitted the ID and therefore the nurses’ locations as they moved around the wards. In addition to the nurse tracking system, a nurse call system was also required for the new wards, and it was decided that the nurse call system and the RTLS systems should be integrated. This function would allow management to identify where nurses were located when a nurse call event was activated, what type of event they were dealing with at the time, and how long they took to respond to nurse calls. But the nurses refused to comply with the system (they did not wear the ID badges) and therefore could not be tracked. As a result of this, the system was never used, hence the importance of educating users and addressing any privacy or other concerns they might have.Discussion, practical recommendations and conclusionsIn healthcare facilities, RTLS can be used to locate portable assets and equipment, locate staff quickly and efficiently, and improve workflow. Hospital throughput of patients can be improved by ensuring the correct medical staff and equipment are in the correct place at the right time.It is important to keep in mind that when vendors are more knowledgeable than the people procuring anything complex, the potential for dissatisfaction is likely to be present. Healthcare procurement teams should not simply take vendors’ marketing information and glossy brochures at face value. Moreover, the impact of the lack financial stability of many of the RTLS players within the industry in today’s (2012) gloomy global economic climate (particularly among the smaller vendors/system integrators) means that vendors are often desperate for revenue; under the circumstances, they may be compelled to offer and sell their products or “solutions” for any healthcare-related project, even when they do not have the correct solution for the client. This could be summarised as ‘to a hammer, every problem looks like a nail’.Many of the companies providing products are several years from profitability, they are investing in building a sales and customer support infrastructure, and it is unlikely that all of them will survive to maturity. The problem for the clients of such companies will be how to support legacy (closed, proprietary) systems if the vendors are no longer trading. To reduce such risks, clients should insist on procuring standards-based technologies that support open APIs [8].Prospective clients should also ask vendors bidding for an RTLS installation to provide references from existing customers covering previously delivered work, particularly work of similar nature and requirements as the current job. They should then carefully check all references received (the second author knows of at least one company who has no installations, but nevertheless advertises several “references”).Many IT (information technology) projects fail, particularly large ones; they are either abandoned prior to implementation (due to cost overruns), or they do not achieve the required functional or business benefits. There have been several well documented IT project failures (either partial or complete) in the healthcare sector, including the well-known case of the NHS (National Health Service) National Programme for IT in England. RTLS installations bring in additional factors that may lead to project failure.The IT sector has an inbuilt expertise in protecting themselves from the consequences of project failure. Indeed, the techniques are taught in many universities; they are called ‘functional specifications’. The deliverables and system functionality of a proposed system are detailed in its functional specifications. This is the case for all major IT deployments, including RTLS installations. The outcome is defined in such a way that allows the project to be declared a success if it can be shown to have met its functional specifications, regardless of whether or not it has also met the requirements as sold and anticipated by the client. One problem here is that vendors are experts in the sciences of the hardware and marketing; they hard promote their hardware because they consider that to be their differentiator in the marketplace. Clients, on the other hand, are usually purchasing a solution to an operational problem (rather than a mere hardware installation), and misunderstandings can arise in the (fine, but often critical) details.RTLS systems are high involvement products, and typically the evaluation, selection and procurement team will consist of a of a stakeholder panel drawn from only the procuring organisation. The panel will examine and evaluate the offers received in detail; often they quickly adopt the domain and terminology of the vendors. Vendors usually provide information about radio type and frequency of transmission, received signal strength (RSSI), triangulation, multiple paths, etc. Depending on the makeup of the selection panel, this may or may not be relevant information, because they may not be cognisant of the differences in the capabilities of products offered, due to minutiae. Unfortunately, although the product details supplied by the vendors may be accurate, buyers responsible for the procurement of RTLS for the first time may not be aware of the consequences of decisions based on minutiae provided by vendors.The choice of RTLS technology must be very carefully made. A given technology or hardware may not work well despite all its merits, if not properly matched to the intended application or the care facility’s (physical) environment, budget and future expansion plans (the latter will require an adequately scalable RTLS solution). For example, radio signals are susceptible to interference via signal propagation, metals, water, people, and radio signal collisions. Not every environment is suited for RF (radio frequency) systems.Procurement teams should ideally include as many stakeholder groups as is possible in the whole process, from its beginning till final delivery. This is also needed to avoid cultural and organisational resistance to new procedures and working practices introduced by a new system and to successfully manage the associated organisational change and stakeholders’ adaptation to the new workflows. It should not just be assumed that everyone will willingly agree to all changes, because they seem like a good idea to senior management.It is also advised (whenever possible) to invite a member of the vendor’s team to serve on the project panel from an early stage (once a suitable vendor has been picked). This enables the vendor to give advice on on-going system changes and enhancements at the ideas stage, rather than the vendor being presented with evolving requirements that are proposed by the client and then either attempting to “shoe horn” them into the system or negotiate changes after the fact.Healthcare institutions should aim at improvements which are well within the capabilities of the technology and require modest procedural changes on behalf of users. They should make incremental changes and keep them simple [8].Finally, selection and procurement teams should focus on achievable and demonstrable real-world benefits such as cost savings, improved efficiency, improved staff and patients’ satisfaction, etc. rather than on mere system specifications, making sure that any chosen vendor is committed to achieving these benefits. Bandi [8] also suggests partnership with vendors in a shared risk acquisition model. Vendor selection should always include a ‘Plan B’: what happens if the vendor fails; is there a contingency to source replacement hardware and obtain software support in this event?References1.Malik A: RTLS For Dummies. 2009, Wiley Publishing, Inc, Indianapolis, Indiana,RTLS For DummiesGoogle Scholar2.International Organization for Standardization: Information technology -- Real-time locating systems (RTLS) -- Part 1: Application program interface (API). ISO/IEC 24730–1:2006. 2006, Geneva, Switzerland,ISO/IEC 24730-1:2006Google Scholar3.Krohn R: The optimal RTLS solution for hospitals. Breaking through a complex environment. J Healthc Inf Manag. 2008, 22 (4): http://14-15.http://www.himss.org/content/files/5_Krohn.pdfPubMedGoogle Scholar4.Dimond D: The optimal RTLS solution for hospitals. J Healthc Inf Manag. 2009, 23 (2): http://4-5.http://www.himss.org/content/files/jhim/23-2/JHIM_Spring_2LetterEditor.pdfPubMedGoogle Scholar5.Drazen E, Rhoads J: Using tracking tools to improve patient flow in hospitals. Issue brief. 2011, California HealthCare Foundation, ,http://www.chcf.org/~/media/MEDIA%20LIBRARY%20Files/PDF/U/PDF%20UsingPatientTrackingToolsInHospitals.pdfGoogle Scholar6.Laskowski-Jones L: RTLS solves patient-tracking emergency. Health Manag Technol. 2012, 33 (3): http://24-25.http://www.healthmgttech.com/index.php/solutions/hospitals/rtls-solves-patient-tracking-emergency.htmlPubMedGoogle Scholar7.Graham E: My Amego relationship centred telecare: using location-based technology to build relationships and manage risk in care homes. Online Proceedings of ‘Location-Based Technologies in Health & Care Services’: 8 February 2012; Reading, UK (an event organised by South East Health Technologies Alliance (SEHTA) and the ICT Knowledge Transfer Network of the UK Technology Strategy Board). 2012,Sign in - Innovation Funding Service, February ; Reading, UK (an event organised by South East Health Technologies Alliance (SEHTA) and the ICT Knowledge Transfer Network of the UK Technology Strategy Board)Google Scholar8.Bandi B: RTLS - To be or not to be. A HIMSS Corporate Member White Paper. 2011, HIMSS,http://www.himss.org/content/files/MEPI/EDI_RTLS_ToBeNotToBe.pdfGoogle Scholar9.Redondi A, Tagliasacchi M, Cesana M, Borsani L, Tarrio P, Salice F: LAURA — LocAlization and Ubiquitous monitoRing of pAtients for health care support. Proceedings of 2010 IEEE 21st International Symposium on Personal, Indoor and Mobile Radio Communications Workshops (PIMRC Workshops): 26–30 September 2010, Istanbul, Turkey. 2010, http://218-222.http://dx.doi.org/10.1109/PIMRCW.2010.5670365Google Scholar10.Liu H, Darabi H, Banerjee P, Liu J: Survey of wireless indoor positioning techniques and systems. IEEE Trans Syst Man Cybern Part C Appl Rev. 2007, 37 (6): http://1067-1080.http://dx.doi.org/10.1109/TSMCC.2007.905750ArticleGoogle Scholar11.Curran K, Furey E, Lunney T, Santos J, Woods D, Mc Caughey A: An evaluation of indoor location determination technologies. J Location Based Serv. 2011, 5 (2): 61-78. 10.1080/17489725.2011.562927.http://dx.doi.org/10.1080/17489725.2011.562927ArticleGoogle Scholar12.Okoniewska B, Graham A, Gavrilova M, Wah D, Gilgen J, Coke J, Burden J, Nayyar S, Kaunda J, Yergens D, Baylis B, Ghali WA, on behalf of the Ward of the 21st Century team: Multidimensional evaluation of a radio frequency identification wi-fi location tracking system in an acute-care hospital setting. J Am Med Inform Assoc. 2012, [Epub ahead of print]. Multidimensional evaluation of a radio frequency identification wi-fi location tracking system in an acute-care hospital settingGoogle Scholar13.Kamel Boulos MN, Anastasiou A, Bekiaris E, Panou M: Geo-enabled technologies for independent living: examples from four European projects. Technol Disabil. 2011, 23 (1): http://7-17.http://dx.doi.org/10.3233/TAD-2011-0300Google Scholar14.Stahl JE, Drew MA, Leone D, Crowley RS: Measuring process change in primary care using real-time location systems: feasibility and the results of a natural experiment. Technol Health Care. 2011, 19 (6): http://415-421.http://dx.doi.org/10.3233/THC-2011-0638PubMedGoogle Scholar15.[No authors listed]: Real-time tracking data drive process improvements, even while ED volumes continue to climb. ED Manag. 2012, 24 (6): http://67-70.http://www.ncbi.nlm.nih.gov/pubmed/22645845Google Scholar16.Cobbley B: Easing patient flow. How an RTLS solution can help ES efficiency. Health Facil Manage. 2011, 24 (12): 43-44. 47, quiz 46. http://www.hfmmagazine.com/hfmmagazine_app/jsp/articledisplay.jsp?dcrpath=HFMMAGAZINE/Article/data/12DEC2011/1211HFM_FEA_ESdomain=HFMMAGAZINEPubMedGoogle Scholar17.Melanson SE, Goonan EM, Lobo MM, Baum JM, Paredes JD, Santos KS, Gustafson ML, Tanasijevic MJ: Applying Lean/Toyota production system principles to improve phlebotomy patient satisfaction and workflow. Am J Clin Pathol. 2009, 132 (6): 914-919. 10.1309/AJCP7FIKZVVTFTXQ.http://dx.doi.org/10.1309/AJCP7FIKZVVTFTXQArticlePubMedGoogle Scholar18.Ng D, Vail G, Thomas S, Schmidt N: Applying the Lean principles of the Toyota Production System to reduce wait times in the emergency department. CJEM. 2010, 12 (1): http://50-57.http://www.cjem-online.ca/v12/n1/p50PubMedGoogle Scholar19.Johnson JE, Smith AL, Mastro KA: From Toyota to the bedside: nurses can lead the lean way in health care reform. Nurs Adm Q. 2012, 36 (3): http://234-242.http://journals.lww.com/naqjournal/Abstract/2012/07000/From_Toyota_to_the_Bedside__Nurses_Can_Lead_the.10.aspxArticlePubMedGoogle Scholar20.Kehoe B: Tracking IV pumps in real time. Mater Manag Health Care. 2007,http://www.matmanmag.com/matmanmag_app/jsp/articledisplay.jsp?dcrpath=MATMANMAG/Article/data/07JUL2007/0707MMH_FEA_CoverStorydomain=MATMANMAGGoogle ScholarDownload referencesAuthor informationAffiliationsFaculty of Health, University of Plymouth, Drake Circus, Plymouth, Devon, PL4 8AA, UKMaged N Kamel BoulosInternational Society for Photogrammetry and Remote Sensing, Commission IV - Geodatabases and Digital Mapping,WG IV/4 - Virtual Globes and Context-Aware Visualisation/Analysis, ISPRS Headquarters (2008–2012), National Geomatics Centre of China, Beijing, 100048, People's Republic of ChinaMaged N Kamel BoulosReal Time Location Technologies Ltd, S60 1FG, Rotherham, UKGeoff BerryCorresponding authorCorrespondence to Maged N Kamel Boulos.Additional informationCompeting interestsMNKB has no competing interests. GB is the founder and CEO (Chief Executive Officer) of a private company offering RTLS solutions.Authors’ contributionsMNKB conducted the literature review, identified and reflected on the main trends in the field, and conceived and drafted the manuscript. GB contributed expert vendor insight to the paper. Both authors read and approved the final manuscript.Authors’ original submitted files for imagesBelow are the links to the authors’ original submitted files for images.Authors’ original file for figure 1Rights and permissionsThis article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (Creative Commons - Attribution 2.0 Generic - CC BY 2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.Reprints and PermissionsAbout this articleCite this articleKamel Boulos, M.N., Berry, G. Real-time locating systems (RTLS) in healthcare: a condensed primer. Int J Health Geogr 11, 25 (2012). Real-time locating systems (RTLS) in healthcare: a condensed primerDownload citationReceived13 June 2012Accepted28 June 2012Published28 June 2012http://DOIhttps://doi.org/10.1186/1476-072X-11-25Share this articleAnyone you share the following link with will be able to read this content:Provided by the Springer Nature SharedIt content-sharing initiativeKeywordsReal-time locating systemsIndoor trackingAssets and individuals trackingHealthcare optimisationDownload PDFDownload ePubAbstractState-of-the-art reviewRTLS components and technologiesRTLS applications in healthcareDiscussion, practical recommendations and conclusionsReferencesAuthor informationAdditional informationAuthors’ original submitted files for imagesRights and permissionsAbout this article