Design Case Studies

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Design Case Studies
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Multidetector Brain Scanning System Development

• Problem given point source response, how can one
  improve net spatial sensitivity of a device?
• Pre-CAT scanning and other current technologies

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Detector Point source response
Lead collimator cross section detector are on
the left on this diagram, iso-response profiles
are to the right
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Problem Statement

• "Given one or more focusing collimators (and
  related electronics), develop a brain scanning
  system that shows increased sensitivity compared
  to a rectilinear scan using a single detector,
  and which gives a cross sectional image of the
  brain more suited for surgical planning than
  rectilinear scans."

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Solution 1 Multicrystal Tomographic Scanner
Schematic of early tomographic scanner, U.S.
Patent Number 3,591,806, eight detectors arranged
in a circle with a common intercept point.
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Solution 2 Mutually Orthogonal Multicrystal
Tomographic Scanner
Mutually orthogonal schematic arrangement one
quadrant of a 12-detector system with 4 sets of
three mutually orthogonal detectors
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TRIZ principle 5

• "combining in space homogenous objects destined
  for contiguous operations "
• Both systems worked, one was patented, both
  formed the basis for other technologies (see
  reference patents.)

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Testing of Anesthetists Hypotheses

• A challenging protocol may be developed using a
  simulator that tests anesthetists' skills at
  maintaining patient homeostasis within limits,
  and
• An analytical technique may be demonstrated that
  will suggest that "skill level" may be inferred
  from the data collected from the simulator.

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Simulation Method

• Inform examinee who the patient is (Stan, normal
  young male)
• Operation type low anterior bowel resection
• SOP please
• Inform re stage of surgery
• Start!

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And we are off
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The protocol (Stable Anesthesia)

• Induction ? Intubation (epi) ? Maintenance
• ? Incision (epi) ? Fluid loss ( 3L) ?
• ? Maintenance ? Ischemia Desaturation (? lung
  changes)
• ? Maintenance ? Emergence
• ? Extubation (? adequacy)

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Trained Physician Results
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Novice Results
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Conclusion

• The human patient simulator may be used as a
  testing device to do inter-individual comparison
  of anesthetist response to simulated stresses
  during anesthetic procedures.
• A simple measure of competency of intervention
  may be derived by a time out of range measure
  
• King, P.H., Pierce, D., Higgins, M., Beattie, C.,
  Waitman, L. C. A Proposed Method for the
  Measurement of Anesthetist Care Variability,
  Journal of Clinical Monitoring and Computing, 16
  (2) 121-125, 2000.

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Apnea Detection System

• A means of monitoring patients for potential
  respiratory depression needs to be found, such
  that the patient in a step-down unit may be
  better monitored than just with simple periodic
  visits by hospital personnel.

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A partial solution included the following items

• CO2 monitoring -too low a CO2 level, or no
  waveform (apnea) as detected by a commercial unit
  Sampling was achieved with a single capillary
  tube placed near the patient's nostrils. The
  units used had an alarm level that could be set
  manually the alarm signal could be accessed for
  use in other devices.
• An autodialing motion detection alarm system was
  modified and connected to the capnometer. The
  system would then dial the charge a nurses'
  beeper when the system alarmed. The beeper was
  unique to the patient being monitored.
• The basic system had to be modified with an
  on/off switch that could be activated when the
  patient was talking (seen as a high respiration
  rate) or eating.
• A special cannula had to be obtained to sample
  air from both nostrils and from near the mouth.
  This was necessary for patients who mouth
  breathed due to snoring and/or stuffy noses.

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Cancer Clinic Charting

• While charting the pathway of patients through a
  screening clinic (breast cancer screening) a
  means had to be found to display not only the
  process but also the patient perception of the
  process.

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Cancer clinic diagnosis/discharge/follow-up
section
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EKG Analysis Techniques

• 2 -3 hours of ekg sampled at 1000 samples/sec
  analyze report on 10-20 averaged ekgs at
  multiple points in time (mouse, implanted
  transmitter)
• Desire r-r interval analysis also
• Desire arrhythmia analysis

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Alternatives considered

• Access Excel Visual Basic
• IDL and Visual C
• PV-Wave C
• MATLAB Visual C Excel Visual Basic
• Others approaches, ease of use?

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Current solution

• Initial developmental work done in Excel with
  visual basic (debug test)
• Migration to MATLAB as soon as feasible
• Currently in use

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EKG Analysis Module

• Given the mandate to do so, design an
  introductory freshman module (1 credit hour) to
  allow students potentially interested in your
  department to sample what they might experience
  in their remaining three years should they elect
  your department's major.

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Electrocardiogram Capture and Analysis

• data analysis techniques in electrocardiography,
• medical and engineering nomenclature,
• engineering and engineering applied to medicine,
• technologies involved in cardiology and
  electrocardiography,
• and societal ramifications of heart-related
  research

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Basics

• EKG lectures, basic ekg recognition
• Student ekg sampled, analyzed with Excel (for R-
  wave analysis HR determination)
• Same ekg analyzed with MATLAB
• http//vubme.vuse.vanderbilt.edu/King/ekg2000.htm
  for layout, etc.

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Choosing the Correct Plastic Material

• The purpose of the test is to provide rough
  insight into whether plastic materials subjected
  to stress are compatible with common cleaning
  substances. The materials being considered are
  Valox, Zytel, Cycoloy, and Thermocomp.

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Test dogbones of material

• Kleen-Aseptic
• Sporicidin
• Cidex
• Aldiced
• Virex 256
• Wescodyn
• Acetone
• Bleach
• Isopropyl alcohol.

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Testing -

• Tensile tests
• Flex tests
• Time/exposure tests
• Inspect visually
• Test to failure

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Similar tests procedures

• Materials tests for autoclaving
• Choosing the right cleaning material