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					                                    AS ICT1 – Information Systems – ICT in Health

COMPUTERS IN HOSPITALS

Mr. John Martin arrives at the hospital to see his patients. He will examine the
records of their vital signs of life and decide if anyone is well enough to leave
the Intensive Care Wards and to return to the normal wards. He will then
decide upon his operating list for the day, as all neurosurgery operative
patients need intensive care post operatively. This is in the day to day running
of a busy hospital department.

The hospital being in close proximity to the M4 deals with numerous cases
daily. It now boasts a helipad that allows chronically ill patients to be
transferred quickly to the A&E department.

Mr. Martin will use all the advantages that ICT can give him in the care of his
patients. He will use ICT in numerous different forms as he gather the
information needed to help his patient and to ensure that he cares for them in
to the best of his ability.

ICT is at the heart of the patient care. It is developing in all exciting and
diverse methods in the quest to help care for ill people. Let us look at some of
the ways that this occurs.

There are two main areas of computer use in hospitals:

      Basic ledger system
      Use for patient care

Ledger System

This deals with the day-to-day purchases that the hospital needs to keep going
on a day-to-day basis. It covers everything that is bought by the hospital and
accounts for their purchase and their use by a particular department. All
departments have budgets and these are then managed by the computer
system.

The finance system also manages the payroll needs of the hospital. This is the
basis by which health authority pays the salary of each individual.

Advantages

      Easy to trace the spending of individual areas
      Cheaper sourcing of materials and items when buying bulk
      Budgets are set early on so that they can be adhered to
      Allows overall monetary control to be decentralised

Disadvantages

      Expensive patient care has to be balanced with the budgetary controls
      Epidemics can not be planned for
      New procedures tend to be expensive
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AS ICT1 – Information Systems – ICT in Health

       Drug bills are expensive

For Patient Records

The creation and management of lists.

Patient personal records are not kept on computer. There are many issues as
to why this is and they will be dealt with later on. At present, patient records
are transcribed manually and these records are then held in the Medical
Records Department. A computer is used to manage the list of appointments
for clinics that go on daily at the busy hospital. Waiting lists are produced for
each clinic and the names of the patients on the list are then processed so that
their notes are delivered to the correct clinic ready for the day’s work. The
notes can include a record of previous visits, previous consultations and
diagnoses and include also results from tests.

So large is this delivery that a small truck runs around the hospital continually
all day long being loaded with notes for the clinics and for the return journey
to Medical Records.

A patient is assigned a unique number when they enter a hospital, the keyfield
in a database This unique number is only used in that hospital and is not
transferable to any other, even those within the same health authority or
trust. The computer held patient records does not carry any detail of their
complaint or diagnoses but holds only their doctor’s name, their GP’s name,
the date of their appointments and the consultant’s name that they are under.
(The name of the doctor that is treating them may differ from their
consultant’s name)

The computer system allows for case note tracking and as an administration
tool for the overview of lists and details. When a list appears, the medical
records team prepare the appropriate notes and test results for the individual
and these are then delivered to the designated ward for admission or to the
clinic that they are attending that day

The use of the keyfield allows direct access to the patient record. The patient’s
records are kept up to date manually and the Medical Records teams type
these up. Detailed notes, such as diagrams by the doctor/surgeon are left in
records and all printed work is transcribed.


The different areas of the hospital have different uses of IT. The systems
developed are unique in their specialism so that they perform the task
designated for them.

The systems continue to evolve, becoming more sophisticated as they are
developed and enhanced. They become more sophisticated in what they do,
clever in detecting the tasks prescribed to them. This clearly demonstrates the
continual development of ICT.

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                                    AS ICT1 – Information Systems – ICT in Health

The Haematology Department (Blood)

One computer system is used to administer blood tests and to track blood that
is transfused to patients.

Transfusions.

An ill patient is brought into hospital needing an operation. The patient’s
details are recorded and using this information, a bracelet is produced with the
keyfield number printed on by barcode. The use of the barcode is to make the
input of information as correct as possible. The scanner used reduces the
human involvement and the chance of error there in. The barcode is used to
track the transfusions that may be given to the person.

On the unit of blood, there is another unique barcode, which can trace the
blood from who gave it. This allows the tracking of the blood as it comes into
the system and can trace the individual that gave the blood. This system
relates to problems that have arisen over the last few years, especially the
CJD (Mad Cow disease) and how that could be spread by transfusion.

When a unit of blood is despatched to a patient, the blood transfusion
department scans it and the appropriate barcode is printed out at the
department and stuck on to the unit of blood. When it reaches the patient, the
scanned barcode on the patient’s bracelet and the scanned barcode on the unit
of blood have to match before the blood can be administered as a part of a
treatment or operation.

Part of the bracelet printed At Morriston Hospital




This system used is called ISBT 128 and is similar to the ISBN system for the
cataloguing of books. The system has the following advantages

Advantages

      Blood can be tracked from donor to patient
      Ensuring that the correct blood is given to the correct patient, cutting
       down the chance of mistake.
      Cutting down the chance of cross contamination

So blood is tacked from the donor to the patient. It can be detected in the
system and its bar coding reduces the human error that may occur in the
system.

Other systems in Haematology are aimed towards the computerisation of the
tests that take place on the blood of patients. In the Pathology laboratory, the

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use of ICT enables the diagnosis of blood disorders and biochemical problems.
This may be the counting of red blood corpuscles, the analysis of the
composition of the blood etc. and all these are carried out automatically. The
machines are regularly calibrated and checked to ensure their accuracy by
outside bodies. (I think that’s a PUN)

Results from these tests are transferred to the ward and the doctor that
ordered them via a computer system. This system uses a LAN to communicate
the information to the doctor and the correct ward as soon as it is available.
This speeds up the return of the appropriate results to the doctor to aid the
diagnosis of the patient’s problems as quickly as is possible.

The automation of the tests reduces the chance of human error by using a
machine to analyse the samples. It reduces the need for highly trained staff as
far as possible. There is an issue here with the over-dependence with a
particular system. If this system goes down, what would happen to the test
that are needed immediately

The only place where this is not possible is in cytology tests where the sample
has to be viewed via a microscope. The trained laboratory technician is looking
of a change in the cell structure or the presence of wrong type of cell. These
may be rogue cells or pointers towards future problems. This has to be done
by a trained pathologist and it only a trained person who can be entrusted with
this work. No computer program is yet in place to do away with the trained
operative in this field.

Hospital Communication – The use of WAN

To communicate information between hospitals for example from Bronglais
Hospital in Aberystwyth to Morriston Hospital in Swansea closed network is
used. This allows x-rays and scans to be sent by a doctor to a specialist for
them to share their opinion. This gives the doctor a second opinion by a
specialist in that field. The closed nature of the network ensures the
confidentiality of the sent material. All hospitals in Wales are linked together
and there is also a gateway to English hospital. It is a system that ensures the
correct and best advice for that patient. The message can be sent quickly to its
destination and the information can be discussed whilst looking at the image.




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Intensive Treatment Unit (ITU)

The area of Intensive Care and Treatment in one with the use of ICT at its
core. Patients can be admitted after trauma (e.g. an accident such as car
crash or industrial incident) or post operatively where they may have
undergone major surgery. Some patients are also referred when an illness or
condition escalates in seriousness.

All patients’ in ITU are in a one to one situation with a nurse to every patient.
Sensors linked to computers and alarms constantly monitor the patient. The
readings of the sensors is recorded by computer but legally at the moment,
the nurse records the maximum and minimum readings manually. These
records are kept for all patients and are shown top the doctor in charge of the
case.

Different sensors can measure a number of different body functions such as

      Temperature
      Pulse
      Blood pressure
      Central venous pressure
      Heart rate
      Blood gases e.g. oxygen in the blood
      Gases as a breakdown of breath
      Brain monitoring measuring brainwave activity
      Continual ECG heart monitoring
      Fluid level testing
      Inter cranial pressure (pressure in the skull)

With dedicated computers and sensors for these aspects mentioned above,
there is the continual monitoring of the patients, 24/7. Alarms are set for
extreme readings allowing nurses and doctors react to each condition as
necessary.

The data can then be turned into information as it is represented as graphs or
when the maximum or minimum readings are read. It allows doctors to spot
trends in patient care and to look at the effect of administration of drugs and
dosage. This is only truly possible with the computer records where certain
times can be examined in greater detail enabling closer examination at definite
times in the patient’s treatment.

Doctors can then act on the input that they are receiving from the equipment.
For example, the central venous pressure gives the anaesthetist the
information to prescribe more or less fluids to ensure the maintenance of fluid
levels.

All this gives the best possible care for the ill patient. It gives the patients the
best possible chance for recovery. An area though that cannot be quantified by
sensor or probe is the measurement of pain and that is a value judgement that
cannot be placed on computer record.
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Quantifying Measurements for Input to a Computer

Apache

All patients entering ITU are given an APACHE score. This is a raw diagnosis of
their illness quantified so that it can be measured. The figure is used to see
how a patient improves and gets well. The details of all patients in ITUs are
sent on to ICNARC (Intensive Care national Audit Research Centre). Here the
centre looks for areas of good practice and specialism. If a particular centre is
producing good results then the good practice of the centre may be shared
with others.

There is has to be the quantifying of the measurements of illness so that it can
be put onto a computer database and compared to other centres across the
country. Whilst various factors can be easily measured such as temperature
and heart rate, others become difficult to quantify such as the measurement of
pain.

Diagnostic Tools

The MRI Scanner

The Magnetic Resonance Imaging Scanner is a radiology technique that uses
magnetism, radio waves and a computer to produce images of the body
structure. A huge circular magnet is in the tube that surrounds the patient.
When the magnet is switched on, the detection of change in magnet resonance
is picked up by radio waves and this change can be modelled by a computer to
produce an image. Different tissues change the resonance of the magnetic
waves. The image and resolution of the image produced is quite detailed and
can detect tiny changes in the body. By changing the reading of the magnetic
resonance and by measuring the change, it can focus the image on different
aspects of the patient, producing some quite spectacular results.



                                                The scan is made up of a
                                                number of slices through any
                                                section of the patient. The
                                                distance these slices are apart
                                                can be set by the operative to
                                                the request of the doctor. It
                                                can show up quite clearly any
                                                part of the body.



This enables the doctors to investigate problems that could only be looked at
previously by surgery. For example, the surgeons can now examine the inside
of the heart and how it is functioning. The inner part of the brain can be
examined. By changing the resonance of the scan, different tissues and other
areas such as blood vessels, tissue, bone or ligament can be seen clearly in
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the resulting picture. Then neurosurgeons can investigate the integrity of the
spinal cord after trauma; brain aneurysms and tumours can be seen clearly.
Contrast agents can also be introduced to increase the accuracy of the images.

Accurate pictures can be taken of joints that show up the soft tissue as well as
the bones of the body. The heart and aorta can be clearly seen as well as
glands and organs, all these without surgery.

Sir Peter Mansfield and Paul C. Lauterbur were the two individuals who
developed MRI scanning. The American Lauterbur discovered the possibility of
producing a two-dimensional picture by variations in the magnetic field.
Mansfield, from Nottingham, showed how the emissions of the magnetism
could be mathematically analysed. He also demonstrated how fast imaging
could be achieved though it took more than a decade for his projections to
become reality. For their work in developing this scanner, both were awarded
the Nobel Prize for medicine in 2003.

Parallel processing and distributed computing

In distributed computing, a number of computers would process its own share
of the work independently. This is when the computers that are linked
together are all set onto the same task at the same time. An example was in
Canada where numerous computers were set a task overnight via the Internet
by a university. Their combined computing power allowed them to tackle a
problem too large for an individual computer to take on.

Parallel processing is the use of many processors in a single computer. This
allows the processors communicate with each other much more quickly.
Multiple processors make the writing of programmes much more difficult and
this is why they are not widely used.

Some MRI scanners use two 930-MHz processors linked together and
extremely large hard drives (6 terabytes and larger) to capture the resultant
data. The processing power will be used to put the scans together into images,
which can be understood by the doctor.

The memory of these machines is backed up every other day, the files being
written to optical discs, these then being stored. It allows for a large amount
of data to be backed up and catalogued. When a patient returns for check-up,
a new scan can be done and the two images, one from before the treatment
and one after treatment can be compared. This can also be examined when
the patients return after a few years on a matter not connected or otherwise.
It gives the doctor a much broader picture of the patient’s health and help with
an accurate diagnosis and treatment.

All scans are backup on optical disk every three days. The use of an optical
disk is to future protect the images.




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The Future

The role of Director General of the NHS Programme for ICT is a vital one.
There is a need to take healthcare into the digital generation.

There are many avenues that are being investigated and acted upon. One is
Electronic Patient Records (EPR). This is the venture to put all patients’ records
online so that all hospitals have access to them, If you were taken into any
hospital anywhere in Britain they could call up your notes and see if you are
for example on any medication at the moment. This can only lead to better
diagnosis of patient’s problems and improve the chances of survival,

This would allow the sharing of information between hospitals, between trusts
and health authority, something that does not go on now. It would greatly
improve the care a patient receives at an A & E department.

Problems associated with the introduction of such a system would be the
compatibility to all. Large projects such as this are notorious for running over-
budget and time and the need for the system to be robust, user friendly and
future proofed create an immense task. Security of Information is also a
major concern as well as the updating of all patient records. Many issues have
to be dealt with.

These plans would also make it possible to book appointments with the doctor
over the Internet and would be able to look at their own notes also. Patients
would also be able to choose where they went for an appointment and to
select the practise they attend for a consultation. Your personal notes are
locked in a filing cabinet somewhere and at present there are something like
660 million pieces of paper in the NHS system and a vast majority have been
typed 2 or 3 times. Streamlining this would cut down on a lot of waste and
repetitive work.

The computerising of the patient records would also create a huge database of
all the people in Britain. This could also allow an epidemiological investigation
to take place. People’s records could be compared to see what treatment
worked and what other factors there may have been for some complex illness.
Trends could be spotted at their early stage and remedial action taken to stop
them quickly. This information would be available no matter where the hospital
was or what the condition of it is.

A database such as this can also be seen as a step towards a national identity
programme where to get treatment one would have to proof of nationality and
proof of residence in this country. You would have to exist on the database
before one can be dealt with. Immigrants, legal or otherwise would have to
prove their adherence to these rules.

There are many problems and a lot of work has to go into their development
before they can be achieved. Numerous issues need clarification and many
avenues have to be explored before completion. There is though a great
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improvement that can be made and a huge streamlining of the bureaucracy of
the NHS letting managers target the money spent in other directions.

EXPERTS

Artificial Intelligence

Software is now being developed which will enable computers to learn and
reason. e.g. Some chess game programs get better the more they are played
- the computer remembers 'when I made that move, I lost...therefore find an
alternative'.

AI is difficult to define. Alan Turing (a prominent mathematician) developed a
simple test (1950) to determine if a computer possessed intelligence:

          Suppose there are two identical terminals in a room, one
          connected to a computer, and the other operated by a
          person. If someone using the two terminals is unable to tell
          which is connected to the computer and which is operated
          by the person, then the computer can be credited with
          intelligence.

AI research includes –

     language processing - understanding and speaking languages as well
      as humans.
     computer vision - recognising and analysing objects.

Neural networks.

The current technology for this is only in its infancy. Nothing to do with
computer networks, neural networks try to mimic the way that the human
brain works (neurons, synapses etc).

Work on neural networks is being carried out in the field of image analysis,
pattern analysis, financial trends etc.

Aspirin is a language used in neural networks (Using a MIGRAINES
interface!).

Requirements

HARDWARE
Parallel processors with powerful capabilities to handle numbers very quickly

SOFTWARE
Languages such as OCCAM

How does a parallel processor handle an instruction?

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Instruction is split up and each processor does part of it


e.g. 4 processors adding up 8 numbers

P1           P2          P3          P4
1+2          3+4         5+6         7+8
P1+ P2       P3 +P4

Result of above

Expert Systems

An expert system is a computer system that emulates the decision-making
ability of a human expert.

A knowledge-based system that attempts to replace a human 'expert' in a
particular field.

It diagnoses problems and gives advice on the cause of those problems. They
can also give advice on solutions.

Components of a rule-based expert system

A typical rule-based expert system integrates

     1. A problem-domain-specific knowledge base that stores the encoded
        knowledge to support one problem domain such as diagnosing why a car
        won't start. In a rule-based expert system, the knowledge base includes
        the if-then rules and additional specifications that control the course of
        the interview.

     2. An inference engine a set of rules for making deductions from the data
        and that implements the reasoning mechanism and controls the
        interview process. The inference engine might be generalized so that the
        same software is able to process many different knowledge bases.




     3. The user interface requests information from the user and outputs
        intermediate and final results. In some expert systems, input is acquired
        from additional sources such as databases and sensors.



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                                   AS ICT1 – Information Systems – ICT in Health

An expert system shell consists of a generalized inference engine and user
interface designed to work with a knowledge base provided in a specified
format. A shell often includes tools that help with the design, development and
testing of the knowledge base. With the shell approach, expert systems
representing many different problem domains may be developed and delivered
with the same software environment.

There are special high-level languages used to program expert systems
e.g. PROLOG

The user interacts with the system through a user interface that may use
menus, natural language or any other style of interaction). Then an inference
engine is used to reason with both the expert knowledge (extracted from our
friendly expert) and data specific to the particular problem being solved.

The expert knowledge will typically be in the form of a set of IF-THEN rules.
The case specific data includes both data provided by the user and partial
conclusions (along with certainty measures) based on this data. In a simple
forward chaining rule-based system the case specific data will be the elements
in working memory.

How an expert system works

Car engine diagnosis

  1. IF                                           engine_getting_petrol
     AND                                             engine_turns_over
     THEN                                    problem_with_spark_plugs

  2. IF                            NOT                engine_turns_over
     AND                           NOT                   lights_come_on
     THEN                                          problem_with_battery

  3. IF                            NOT                 engine_turns_over
     AND                                                  lights_come_on
     THEN                                           problem_with_starter

  4.   IF                                            petrol_in_fuel_tank
       THEN                                        engine_getting_petrol
There are three possible problems with the car:

          problem_with_spark_plugs,
          problem_with_battery,
          problem_with_starter.


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The system will ask the user:

     Is it true that there's petrol in the fuel tank?
Let's say that the answer is yes. This answer would be recorded, so that the
user doesn't get asked the same question again. Anyway, the system now has
proved that the engine is getting petrol, so now wants to find out if the engine
turns over. As the system doesn't yet know whether this is the case, and as
there are no rules that conclude this, the user will be asked:
     Is it true that the engine turns over?
Lets say this time the answer is no. There are no other rules which can be
used to prove ''problem_with_spark_plugs'' so the system will conclude that
this is not the solution to the problem, and will consider the next hypothesis:
problem_with_battery. It is true that the engine does not turn over (the user
has just said that), so all it has to prove is that the lights don't come one. It
will ask the user
     Is it true that the lights come on?
Suppose the answer is no. It has now proved that the problem is with the
battery. Some systems might stop there, but usually there might be more
than one solution, (e.g., more than one fault with the car), or it will be
uncertain which of various solutions is the right one. So usually all hypotheses
are considered. It will try to prove ''problem_with_starter'' but given the
existing data (the lights come on) the proof will fail, so the system will
conclude that the problem is with the battery. A complete interaction with our
very simple system might be:

     System:         Is it true that there's petrol in the fuel tank?

     User:           Yes.

     System:         Is it true that the engine turns over?

     User:           No.

     System:         Is it true that the lights come on?

     User:           No.

     System:         I conclude that there is a problem with battery.

Note that in general, solving problems using backward chaining involves
searching through all the possible ways of proving the hypothesis,
systematically checking each of them.

Questions

     1. ''Briefly describe the basic architecture of a typical expert system,
        mentioning the function of each of the main components.''


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                                  AS ICT1 – Information Systems – ICT in Health

  2. ''A travel agent asks you to design an expert system to help people
     choose where to go on holiday. Design a set of decisions to help you give
     advice on which holiday to take.''

Expert System Use

Expert systems are used in a variety of areas, and are still the most popular
developmental approach in the artificial intelligence world. The table below
depicts the percentage of expert systems being developed in particular areas:

              Area                               Percentage
              Production/Operations Mgmt            48%
              Finance                               17%
              Information Systems                   12%
              Marketing/Transactions                10%
              Accounting/Auditing                    5%
              International Business                 3%
              Human Resources                        2%
              Others                                 2%

     Medical screening for cancer and brain tumours
     Matching people to jobs
     Training on oil rigs
     Diagnosing faults in car engines
     Legal advisory systems
     Mineral prospecting

Medical diagnosis

The computer does not take the place of the doctor but can be used to help
the doctor make decisions.
An expert system would have information about diseases and their symptoms,
the drugs used in treatments etc.

A patient is asked by a doctor about symptoms and the replies are input to the
expert system. The computer searches its database, uses its rules and makes
suggestions about the disease and its treatments. Sometimes probabilities are
assigned to diagnoses.

Mycin was one of the earliest expert systems, and its design has strongly
influenced the design of commercial expert systems and expert system shells.

Mycin was an expert system developed at Stanford in the 1970s. Its job was
to diagnose and recommend treatment for certain blood infections. To do the
diagnosis ``properly'' involves growing cultures of the infecting organism.
Unfortunately this takes around 48 hours, and if doctors waited until this was
complete their patient might be dead! So, doctors have to come up with quick
guesses about likely problems from the available data, and use these guesses
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to provide a ``covering'' treatment where drugs are given which should deal
with any possible problem.

Mycin was developed partly in order to explore how human experts make
these rough (but important) guesses based on partial information. However,
the problem is also a potentially important one in practical terms - there are
lots of junior or non-specialised doctors who sometimes have to make such a
rough diagnosis, and if there is an expert tool available to help them then this
might allow more effective treatment to be given. In fact, Mycin was never
actually used in practice. This wasn't because of any weakness in its
performance - in tests it outperformed members of the Stanford medical
school. It was as much because of ethical and legal issues related to the use of
computers in medicine - if it gives the wrong diagnosis, who do you sue?

Anyway Mycin represented its knowledge as a set of IF-THEN rules with
certainty factors. The following is an English version of one of Mycin's rules:

     IF     the infection is pimary-bacteremia

     AND    the site of the culture is one of the sterile sites

     AND    the suspected portal of entry is the gastrointestinal tract

     THEN   there is suggestive evidence (0.7) that infection is bacteroid

The 0.7 is roughly the certainty that the conclusion will be true given the
evidence. If the evidence is uncertain the certainties of the bits of evidence will
be combined with the certainty of the rule to give the certainty of the
conclusion.

Mycin was written in Lisp, and its rules are formally represented as Lisp
expressions. The action part of the rule could just be a conclusion about the
problem being solved, or it could be an arbitrary lisp expression. This allowed
great flexibility, but removed some of the modularity and clarity of rule-based
systems, so using the facility had to be used with care.

Anyway, Mycin is a (primarily) goal-directed system, using the basic backward
chaining reasoning strategy that we described above. However, Mycin used
various heuristics to control the search for a solution (or proof of some
hypothesis). These were needed both to make the reasoning efficient and to
prevent the user being asked too many unnecessary questions.

One strategy is to first ask the user a number of more or less preset questions
that are always required and which allow the system to rule out totally unlikely
diagnoses. Once these questions have been asked the system can then focus
on particular, more specific possible blood disorders, and go into full backward
chaining mode to try and prove each one. This rules out a lot of unnecessary
search, and also follows the pattern of human patient-doctor interviews.



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The other strategies relate to the way in which rules are invoked. The first one
is simple: given a possible rule to use, Mycin first checks all the premises of
the rule to see if any are known to be false. If so there's not much point using
the rule. The other strategies relate more to the certainty factors. Mycin will
first look at rules that have more certain conclusions, and will abandon a
search once the certainties involved get below 0.2.

There are three main stages to the dialogue with Mycin:

          In the first stage, initial data about the case is gathered so the
           system can come up with a very broad diagnosis.
          In the second more directed questions are asked to test specific
           hypotheses. At the end of this section a diagnosis is proposed.
          In the third section questions are asked to determine an appropriate
           treatment, given the diagnosis and facts about the patient. This
           obviously concludes with a treatment recommendation.

At any stage the user can ask why a question was asked or how a conclusion
was reached, and when treatment is recommended the user can ask for
alternative treatments if the first is not viewed as satisfactory.

A new expert system called PUFF was developed using EMYCIN in the new
domain of heart disorders.

A later version called NEOMYCIN had an explicit disease classification to
represent facts about different kinds of diseases and a system called
NEOMYCIN was developed for training doctors, which would take them through
various example cases, checking their conclusions and explaining where they
went wrong.

Advantages

      The computer can store far more information than a human. It can
       draw on a wide variety of sources such as stored knowledge from books
       case studies to help in diagnosis and advice.
      The computer does not 'forget' or make mistakes.
      Data can be kept up-to-date.
      The expert system is always available 24 hours a day and will never
       'retire'.
      The system can be used at a distance over a network. So rural areas or
       even poorer third world countries have access to experts.
      Provides accurate predictions with probabilities of all possible problems
       with more accurate advice.
      Some people prefer the privacy of talking to a computer.

Limitations / Disadvantages of expert systems

          Over reliance upon computers
          Some ‘experts’ could lose their jobs or not be given training if
           computers are available to do the job.
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            Lacks the 'human touch'! – lack of personal contact
            Dependent upon the correct information being given. If data or rules
             wrong the wrong advice could be given.
            Expert systems have no "common sense". They have no
             understanding of what they are for or of what the limits of their
             applicability are, or of how their recommendations fit into a larger
             context. If MYCIN were told that a patient who has received a
             gunshot wound is bleeding to death, the program would attempt to
             diagnose a bacterial cause for the patient's symptoms.
            Expert systems can make absurd errors, such as prescribing an
             obviously incorrect dosage of a drug for a patient whose weight and
             age are accidentally swapped by the clerk.




The knowledge base of an expert system is small and therefore manageable--a
few thousand rules at most. Programmers are able to employ simple methods
of searching and updating the KB, which would not work if the KB were large.
Furthermore, micro-world programming involves extensive use of what are
called "domain-specific tricks"--dodges and shortcuts that work only because
of the circumscribed nature of the program's "world". More general
simplifications are also possible.

One example concerns the representation of time. Some expert systems get
by without acknowledging time at all. In their micro-worlds everything
happens in an eternal present. If reference to time is unavoidable, the micro-
world programmer includes only such aspects of temporal structure as are
essential to the task--for example, that:

        if a is before b
        and b is before c
        then a is before c.

This rule enables the expert system to merge suitable pairs of before-
statements and so extract their implication (e.g. that the patient's rash
occurred before the application of penicillin). The system may have no other
information at all concerning the relationship "before"--not even that it orders
events in time rather than space.

The problem of how to design a computer program that performs at human
levels of competence in the full complexity of the real world remains open.

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                                       AS ICT1 – Information Systems – ICT in Health




http://www.aaai.org/AITopics/html/expert.html

Delivering expertise without the expert's physical presence

The scenario we just examined used a telephone to provide remote access to
an expert mechanic. Books and manuals provide other examples of packaged
expertise. Methods for delivering advice without the expert's presence that
include a stronger goal orientation include checklists, flowcharts and decision
tables:


AUTO DIAGNOSTIC CHECKLIST
                                         A checklist for diagnosing why a car
SECTION 1                                won't start might begin like this. The
1. Does the starter operate?             branching nature of the problem could
A. Yes (GO TO SECTION 2)                 result in a complex questionnaire.
B. No (GO TO SECTION 3)



                                         Graphical representations of diagnostic
                                         procedures like this flowchart provide
                                         an alternative to complex checklists.



Rule              1    2    3      4

Starter runs?     Y    Y    N            Decision tables can provide procedural
                                         guidance      for    complex    problems.
                                         Attributes of the problem are listed in
Smell gas?        Y    N       .
                                         the    condition stub       (green) and
                                         recommendations or intermediate results
Dead battery      .    .    X
                                         in the action stub (yellow). Rules (read
                                         vertically) specify the action to take for
Out of gas        .    X       .         any combination of conditions.

Flooded           X    .       .


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AS ICT1 – Information Systems – ICT in Health



Representing knowledge in rule-based systems


RULE 1:                                  RULE 2:

If the result of switching on the        If the result of trying the starter is the
headlights is that nothing happens,      car cranks normally and a gas smell is
or the result of trying the starter is   not present when trying the starter
that nothing happens.
                                         Then the gas tank is empty with 90%
Then the recommended action is           confidence
recharge or replace the battery

RULE 3:                                  RULE 4:

If the gas tank is empty                 If the result of trying the starter is the
                                         car cranks normally and a gas smell is
Then the recommended action is           present when trying the starter
refuel the car
                                         Then the recommended action is wait
                                         10 minutes, then restart flooded car

Each rule consists of an IF part called the premise or antecedent and a THEN
part called the consequent or conclusion. When the IF part is true, the rule
is said to fire and the THEN part is asserted - it is considered to be a fact.

Rule results are often combined to reach a conclusion. The goal of the auto
diagnosis is to find a recommended action: what to do to get the car started.
Rule 3 tells what to do if the gas tank is empty and rule 2 could prove that the
gas tank is empty. If rule 2 fires, rule 3 will also fire and provide a
recommended course of action.

The consequent in rule 2 is asserted with 90% confidence. This means that if
the rule's premise is true, we are only 90% certain that the car is out of gas.
Our computer-based expert might be willing to accept this level of confidence
to fire rule 3 and recommend an action.




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