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Diffuse Optical Tomography Optimization and Miniaturization ECE 4902-Spring 2014

Diffuse Optical Tomography Optimization and Miniaturization ECE 4902-Spring 2014. Thomas Capuano (EE&BME), Donald McMenemy (EE), David Miller (EE), Dhinakaran Dhanaraj (EE) Faculty Advisor Dr. Quing Zhu. Overview. DOT Procedure Present System Project Goals Proposed System Budget

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Diffuse Optical Tomography Optimization and Miniaturization ECE 4902-Spring 2014

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  1. Diffuse Optical TomographyOptimization and MiniaturizationECE 4902-Spring 2014 Thomas Capuano (EE&BME), Donald McMenemy (EE), David Miller (EE), DhinakaranDhanaraj (EE) Faculty Advisor Dr. Quing Zhu

  2. Overview • DOT Procedure • Present System • Project Goals • Proposed System • Budget • Timeline

  3. DOT Procedure • DOT – Diffuse Optical Tomography • Used in conjunction with Ultrasound • Procedure • 1) Shine infrared light (140MHz) on tissue • 2) Infrared light is scattered and absorbed by tissue • 3)DOT System captures propagated light • 4) Calculate the scattering and absorption coefficients • 5) Coefficients are used determined tissue type

  4. DOT System High Level • Source Box: • Houses laser diodes and drivers • Two Optical switches • Allows for laser wavelength selection • Allows for source position selection • Connects laser to probe • Detection Box: • Connects probe to photomultiplier tube (PMT) • Comprised of analog signal processing circuitry and digital acquisition

  5. DOT System High Level • PC: • NI PCI-1411 (~$1000) • Extracts Ultrasound Images • Two NI PCI-6251 with Shielding Cable ($2000) • Records the Input Waveforms • Sends Optical Switch Control Signals • Position Selection • Laser Wavelength Selection • LabView • Synchronizes the Control of the System • GUI • Data Output for MATLAB Post-Processing

  6. Proposed System • Goals • Reduce Cost • Reduce Size • Improve User Friendly Operation • Methods • Digitize all system controls • Redesign analog to digital conversion • Control and communication over USB • Generate GUI for control and processing

  7. Control Function • FPGA • DE0-Nano • Allows for Pin Function Customization • Allows for Hardware Algorithms • Easy Connectivity Between FPGA and Designed PCB • NIOS II Softcore Processor • Interfaces with Altera IP Cores • Interfaces with AD7609 Avalon Slave Module • Tools • Quartus II – Programming Hardware (HDL) • Qsys – System Level and IP Cores • ModelSim – Testbench • NIOS IDE – Programming Software (C)

  8. Data Bus • Avalon Memory Mapped Interconnect • Function • Allows Data communication between multiple devices over the same data lines • Primary Signals: Read Data, Write Data, Memory Address, Read Enable, Write Enable, Wait For Response • Advantage • Less Connections • More Control and Flexibility in Data • Interface with Current Altera IP

  9. Control Signals • FPGA Output Voltage : 3.3V • Optical Switch Voltage : 5V • Level-Shifter • 3.3V to 5V Bidirectional Voltage Translator • Number of Bits = 4 • TXB0104

  10. Analog-to-Digital Converter • Required Signals to AD7609 • RESET • Done Prior to Conversion • CONVST X • Triggers ADC • CSRD • Triggered 8*Times • * when only collecting bits [17:2]

  11. AD7609 Control Code • VHDL State Machine component in Qsys system • Ignoring LSBs 0 and 1 of [17-0] to increase sampling frequency • Collects 256 samples, stores in embedded (M9K) RAM blocks

  12. AD7609 Control Code • Simulated sampling frequency 284KHz • 14 samples per period

  13. AD7609 State Flow

  14. Digital-to-Analog Converter • Function • Set the Gains of the Photomultiplier Tubes • DC Voltages Between 0.2V and 1.2V • Part • AD5391 • DAC • ADR431 • Voltage Reference • Control • SPI Interface

  15. Miscellaneous • Expansion Ports • 8 GPIO Pins • 8 GND Pins • 4 5V Pins • 4 3.3V Pins • Power • 5V • LM2937 • 3.3V • LM2937-3.3 • System Voltage • +/- 15V 6A DC

  16. Communication • UART (PC to FPGA) • FTDI -FT232R • USB-to-Serial • USB Port Treated as Virtual COM Port • Uses • Set Voltages for DAC • Trigger Data Acquisition • Record Data from ADC

  17. Frame Acquisition • DVI to USB video recorder • Ultrasound image storage before and after DOT • Provides consistent data for position • Epiphan Systems Inc. - DVI2USB 3.0 • 24-bit Color • Up to 30 Frames Per Second • 1920x1200 Resolution • Controllable through DirectShow API

  18. Budget • ADCs: $280 (Provided) • DACs: $60 • PCBA: $230 • FPGA: $100 • Video Acquisition: $700 • Total: $1090

  19. Timeline

  20. Questions?

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