Infrared Camera from Wii System to Track Ultrasound

Infrared Camera from Wii System to Track Ultrasound Probe and Create 3 -D Image Vanderbilt University Department of Biomedical Engineering Van Gambrell Laura Owen Steven Walston Jonathan Whitfield Advisor Dr. Christopher Lee - Department of Neurology

Amyotrophic Lateral Sclerosis a. ALS is a progressive neurodegenerative disease that causes atrophy of voluntary muscles through degradation of motor neurons • The size, shape, and structural makeup of muscles like the bicep can be good indicators of the severity of the disease

ALS in the United States Stephen Hawking a. 20 -30 thousand people in the US have ALS b. Doctors diagnose approximately 5, 000 new cases every year. c. Once diagnosed, a person with ALS is only expected to live 3 -5 years. d. Understanding the effects of the disease should help increase the life expectancy and in time hopefully cure it

Dr. Christopher Lee a. Vanderbilt University Medical Center, Neurology Department • Dr. Lee specializes in evaluating muscle ultrasound in ALS patients • He uses this information to determine early clinical and electrodiagnostic features of critical illness polyneuropathy and myopathy

Imaging Muscles MRI a. Great images b. But expensive, time consuming, and immobile c. Current standard Ultrasound a. Images comparable to MRI • Cheaper • Short imaging time • 2 D linear images acquired by free hand o Difficult to make a reproducible 3 D image Ultrasound

Imaging Machinery Ultrasound Cost: a. Sonosite Titan: $16, 500 Size: a. Small laptop • 8" LCD Mobile: • Portable docking station • 4 hour battery life MRI Cost: a. Typical MRI Machine: $3 Million Size: a. 490 Square Feet Mobile: • Not Mobile

Could 3 -D Ultrasound be a good alternative to MRI a. Can the location and position of the ultrasound probe be monitored? b. Can a three dimensional image of muscle be generated using the signal from the probe and correlating it with the data of the orientation of the US probe? c. Will an imaging system that fulfills these two questions be effective, portable, and cost efficient? d. Will the monitoring of muscle volume be effective in researching treatments for ALS?

Solution Design a. Objective is to use 2 Wii-mote CCD's to track infrared LEDs a. x and y position from each wii mote to calculate position in 3 D b. Using a triangulation algorithm to determine the position of the LED in 3 dimensional space using the 2 Wii-motes • Wii-mote can track up to four infrared emitters at one time o Placement of the LEDs will allow the tracking of the probe in 3 -D space • Using the gyroscope from the Wii Motion Plus we will be able obtain the yaw, pitch, and roll information of the US probe

Status and Results a. Wiimote simultaneously tracks 4 infrared LEDs in 2 D space b. Wrote a triangulation algorithm that computes 3 D location from the 2 sets of data c. Determined the camera calibration information, including focal length and other matrix information d. Calculated a centroid to return one data set for 4 IR light sources e. Successfully connect arduino to computer using serial connection and can read yaw, pitch and roll data through MATLAB f. Can report real-time infrared and accelerometer data through MATLAB interface g. Determined sampling rate to be 60 Hz h. Begun trying to interface our data with Strad. X open source 3 -D US software

Data Transfer Schematic

Wii-Motion Plus and Arduino Wii-Motion Plus has much more sensitive accelerometers than the wii mote that can provide 6 degrees of freedom to correctly establish the U. S. probe's orientation. Arduino is an open source prototyping platform that can interface with the Wii-Motion Plus and the computer to provide angular data from the U. S. probe

Physical Schematic

Estimated Final Cost of Design a. Wii Motes: $39. 99 a. X 2 = $79. 98 b. Wii Motion Plus: $17. 96 c. Adruino: $30. 00 d. Adruino + Wii Motion Plus Adapter: $4. 00 e. Circuit Electronics: $15 a. LEDs, Resistors, Battery, Wires f. System Mount: ~$20. 00 g. Arm Stabilizer: ~$18. 00 h. Unforeseen Additions: ~$40. 00 Final Cost: ~$225. 00

Known Problems a. Infrared signals from external sources can interfere with LED signals b. The IR LEDs emit signal in a conical area (limited view) c. Potential accuracy problems d. Incorrect centroid calculations due to blocked IR LED

Wiimote Sensitivity a. 2 infrared LEDs 30. 48 cm apart • Error = -2. 46 mm ± 2. 23 (mean ± std)

Current Work Plans a. Determine scaling of Wii-motion plus accelerometer data a. Sync wiimote and ultrasound acquisition rates • Interface the system with the 3 -D reconstruction software Strad. X

Future Work Plans March 30 a. Physically attach the Wii. Motion+ device to US probe b. Create a mounting system for the IR cameras c. Use the position data to tag Ultrasound images and create a 3 dimensional image d. Begin taking samples for data analysis April� a. Have completed data acquisition • Quality assessment