Head Motion Detection In a MRI Simulator

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Head Motion Detection In a MRI Simulator

• Yuk-Ki Lam
• Brent Geiger
• BME 200/300
• 10-18-02

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Outline

• Design Parameters
• Summary of Proposed Solutions
• Selection of Design and Decision Matrix
• Final Proposed Design
• Conclusion and Future Goals

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Design Parameters

• Safety- children, exposed wires, knobs
• Comfort- noninvasive
• Simplicity- simple to construct and operate
• Accuracy- 1-2mm, 3-axes
• Cost- construction and operation
• Adaptability- accommodate different patients

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Proposed Feedback System

• Feedback system for all designs
• Signal sent to Operator outside tube
• Operator has control
• Operator then notifies patient
• More comfortable for patient
• Based on Advice from Michael Anderle

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1. Stretch Sensor Device
-Stretch sensors connected to face and head
coil -Resistance proportional to change in
length -Interpreted and analyzed by
computer -Feedback response
Stretch sensor from Merlin Systems
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Advantages Disadvantages

• Cost
• -Stretch sensors are relatively cheap- 15 per
  sensor
• Simplicity
• -simple design

• Accuracy
• -Skin stretch
• Adaptability
• -Must be set to each patient
• -Training of Operator
• Comfort
• -Sensors attached to skin/face

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2. Integrated Camera Image

• Install digital camera in tube
• Image sent to computer
• Software integrates images
• Detect motion outside specified range
• Feedback response

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2.Integrated Camera Image

• Advantage
• Comfort
• No direct contact
• Adaptability
• For all patient population

• Disadvantage
• Cost
• High cost
• Simplicity
• Hard to install
• Darkness
• Accuracy
• Time Delay

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3. Electromyogram (EMG)

• Head is moved by muscle contraction
• EMG
• Use electrode to detection voltage change
• Signal send to computer and analysis
• Software determine motion
• Feedback system

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3. Electromyogram (EMG)

• Advantage
• Accuracy
• Quantitative measurement
• Adaptability
• For all patient population

• Disadvantage
• Simplicity
• VERY complicated
• Hard to obtain electrical impulse of single
  muscle
• Cost
• High cost on labor

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4. Headband Photosensor
Photo Sensor
Feedback System
On/off Switch
Light Beam
Embedded inside the headband
Light source
Battery (Power Supply)
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4. Headband Photosensor

• Advantage
• Safe
• Embedded all wire
• Simplicity
• Easy to install
• Cost
• Low cost

• Disadvantage
• Accuracy
• Lose information on median plane
• Only on/off signal information

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Decision Matrix
(Scale -5 to 5)
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Final Solution-Modifications

• Light source
• NOT laser
• Infrared/LED
• Focal Length

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Modification
Amplifier
Zone A Zone B Zone C Zone D
Amplifier
Processor (with input in different port)
Feedback response
Amplifier
Amplifier

• Photosensor
• Use multi-sensors
• Increase information value
• Analysis

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Conclusion and Future Goals

• Our Best Solution
• Headband Photosensor
• Future Goals
• Light source
• Focal length
• Photosensor arrangement
• Prototype

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Thanks To

• Andrew Alexander Ph.D.
• Michael Anderle
• Mitchell Tyler
• Professor Willis Tompkins