1. Comprehensive Ultrasound Research Platform Emma Muir Sam Muir Jacob Sandlund David Smith Advisor: Dr. Sánchez Co-advisor: Dr. Irwin

2. 22 Outline Introduction System ◦ Block Diagram / Functional Description ◦ Requirements Progress

3. 33 Outline Introduction System ◦ Block Diagram / Functional Description ◦ Requirements Progress 3

4. 44 Ultrasound Introduction Piezoelectric Transducer ◦ Pulse Excitation Changes in density reflect waves

5. 55 Objective Create an Ultrasound Research Platform ◦ Image Creation ◦ Multi-pin  Beamforming ◦ Sigma Delta Architecture  1-bit ADC ◦ Arbitrary Waveforms  Coded excitation signals  Configurable delays 5

6. 66 Motivation Improve Ultrasound Techniques Medical Applications ◦ Detecting tumors and abnormalities Future Research 6

7. 77 Significance Test codes (arbitrary) for better imaging Multi-pin to allow Beamforming Architecture reduces cost and size ◦ RASMUS  Two 19 inch racks ◦ Sigma Delta vs. 12+ bit DAC 7

8. 88 Outline Introduction System ◦ Block Diagram / Functional Description ◦ Requirements Progress 8

9. 99 Block Diagram

10. 10 PC Data Processing

11. 11 Outline Introduction System ◦ Block Diagram / Functional Description ◦ Requirements Progress 11

12. 12 System Requirements Up to 8 transducer channels Excitations <= 3 μs ◦ Time-bandwidth product of 40 High frequency design ◦ Signal to noise ratio (SNR) > 50 dB

13. 13 Sigma Delta Modulation < 10% MSE 500 M samples/second Trade off ◦ Accuracy vs. Stability ◦ OSR = 16 (must be a power of 2) ◦ Order = 2nd

14. 14 FPGA Requirements Store data on DDR2 ◦ 62.5 MHz ◦ 8 waveforms ◦ 1536 bits per waveform Output Data ◦ 8 Individualized Pins ◦ Delays of up to 5  s ◦ 500 MHz

15. 15 FPGA to PC Communication UART ◦ 115200 baud Send waveform data Assign waveform to pins Assign delay to pins Start transmission

16. 16 Data Processing ◦ Less than 2 minutes Display an image ◦ Depths between 0.25 cm and 30 cm. ◦ Adjust contrast Graphical User Interface (GUI)

17. 17 Outline Introduction System ◦ Block Diagram / Functional Description ◦ Requirements Progress 17

18. 18 Progress 18

19. 19 Progress 19

20. 20 Amplifier Progress Different designs examined ◦ H-Bridge ◦ 2 MOSFETs  Push-pull RF MOSFET ◦ 1 MOSFET  N-channel RF MOSFET  Final Design

21. Amplifier Progress Discuss problems/solutions

22. Amplifier Progress

27. T/R Switch Progress 27

28. T/R Switch Progress 28 1.92V

29. PCB Progress Footprints ◦ TX810  Transmit/Receive Switch ◦ RF MOSFET  Set INTO board

30. 30 Progress 30

31. 31 Progress 31

32. 32 Progress 32

33. 33 FPGA Progress Arbitrary transmission Output verified ◦ 500 MHz Multi-pin ◦ Currently 4 ◦ Adjustable Arbitrary length ◦ Must be 256 bit pieces Adjustable delays of < 33 ms 33

34. 34 FPGA Flowchart Progress 34

35. 35 FPGA Remaining Fix storing waveform data from UART ◦ Inconsistent results Increase delays precision ◦ After data retrieved Make output more exact Change to 8 pins 35

36. 36 Progress 36

37. 37 UART Progress UART ◦ 115200 baud works PC to FPGA Communication ◦ Start transmission signal ◦ Set waveforms to pins ◦ Set delays for pins ◦ Waveform data  Inconsistent 37

38. 38

39. Waveform GUI Features Multiple selection Automatic pin settings removal Save/Load settings Check files exist when loading settings Let “None” represent an array of 0’s 39

40. 40 Progress 40

41. 41 FPGA Results Time (s) Delayed Cross-talk 41

42. 42 FPGA Results Normalized Correlation Sample number Max Corr. = 0.97 42

43. 43 FPGA Results 43

44. 44 FPGA Results 44

45. 45 FPGA Results 45

46. 46 Progress 46

47. 47 Analog Front End Results Source: Analog Devices UG-016 http://www.analog.com/static/imported-files/user_guides/UG-016.pdf 47

48. 48 Alternatives Analog Front End ◦ 12 bit resolution ◦ 80 MSPS Lecroy High Speed Oscilloscope ◦ 725Zi ◦ 8 bit Resolution ◦ 20 GSPS ◦ 4 Channels 48

49. 49 Progress 49

50. 50 Progress 50

51. Beamforming Delay based on distance from point to sensor and distance from sensor to focal point Note: No delay at the Focal Point Sensors Focal Point Point 51

52. Without BeamformingWith Beamforming 52

53. Attenuation Average frequency attenuation in tissue ◦ 0.5 dB/cm/MHz ◦ 5e-5 dB/m/Hz Doubled for ultrasound imaging Frequency = 8MHz Maximum depth = 30cm Maximum attenuation = 240dB Image dB range = 0dB to -50dB 53

54. Time Gain Compensation Based on depth of point in image Att = 1dB/cm/MHz TGC = Att*Depth*8MHz Add to compensate Note that this increases white noise for larger depths 54

55. 55 Progress 55

56. Sigma Delta Representation 56

57. Without Pre-Enhanced Magnitude Correlation = 0.9763 57

58. Pre-Enhanced Magnitude 58

59. With Pre-Enhanced Magnitude Correlation = 0.9916 59

60. Sigma Delta Features Easy to modify ◦ Frequency ◦ Period ◦ Waveform equation ◦ Number of samples Pre-Enhanced Magnitude Checks/displays correlation Writes output to a file as 0’s and 1’s 60

61. Sigma Delta Additions GUI interface for entering ◦ Frequency ◦ Period ◦ Waveform equation Select location to save file Interface with Waveform GUI 61

62. 62 REC Results MATLAB simulation 150% of original bandwidth Linear chirp frequencies ◦ 1.14 times the bandwidth ◦ Reduce side-lobes during pulse compression Apply to finished system

63. 63 h 1 (n) * c 1 (n) = h 2 (n) * c 2 (n)

64. 64

65. 65 Pulse Compression Results MATLAB simulation Wiener filter SNR of 60 dB Input is REC pre-enhanced chirp Varied Smoothing Factor (SF) ◦ Operating Point

66. 66

67. 67 Field II Simulations REC Excitation and Pulse Compression SF = 0.1 Impulse Excitation 67

68. 68 Progress 68

69. MATLAB GUI Features Depth from 2mm to 231mm Max dB range from 10dB to 60dB Update chart settings automatically Update data in 54s 69

70. MATLAB GUI 70

71. MATLAB GUI 71

72. MATLAB GUI Additions Depth from 2mm to 300mm Restrict max dB to 40dB to 60dB Allow user to type value or scroll Minimize update time Convert to C 72

73. 73 Progress 73

74. 74 Progress 74

75. 75 Progress 75

76. Additional Information Visit http://cegt201.bradley.edu/projects/http://cegt201.bradley.edu/projects/ proj2011/ultra/index.html 76

77. 77 Acknowledgments The authors would like to thank Analog Devices and Texas instruments for their donation of parts. This work is partially supported by a grant from Bradley University (13 26 154 REC) Dr. Irwin Dr. Lu Mr. Mattus Mr. Schmitt Andy Fouts

78. 78 References [1] J. A. Zagzebski, Essentials of Ultrasound Physics, St. Louis, MO: Mosby, 1996. [2] R. Schreier and G. C. Temes. Understanding Delta-Sigma Data Converters, John Wiley & Sons, Inc., 2005. [3] R. Schreier, The Delta-Sigma Toolbox Version 7.3. Analog Devices, Inc, 2009. [4] T. Misaridis and J. A. Jensen. “Use of Modulated Excitation Signals in Medical Ultrasound,” IEEE Trans. Ultrason., Ferroelectr. Freq. Contr., vol. 52, no. 2, pp. 177-191, Feb. 2005. [5] M. Oelze. “Bandwidth and Resolution Enhancement Through Pulse Compression,” IEEE Trans. Ultrason., Ferroelectr. Freq. Contr., vol. 54, no. 4, pp. 768-781, Apr. 2007. [6] Mitzner, Kraig. Complete PCB Design Using OrCad Capture and PCB Editor, Newnes, 2009.

79. 79 References Cont. [7] Montrose, Mark I. Printed Circuit Board Design Techniques For EMC Compliance: A Handbook for Designers, Wiley-IEEE Press, 2000. [8] J.A. Jensen. Field: A Program for Simulating Ultrasound Systems, Paper presented at the 10th Nordic-Baltic Conference on Biomedical Imaging Published in Medical & Biological Engineering & Computing, pp. 351-353, Volume 34, Supplement 1, Part 1, 1996. [9] Kai E. Thomenius. Evolution of Ultrasound Beamformers, IEEE Trans. Ultrason., Ferroelectr. Freq. Contr., pp. 1615-1622, 1996. [10] J.A. Jensen and N. B. Svendsen. Calculation of pressure fields from arbitrarily shaped, apodized, and excited ultrasound transducers, IEEE Trans. Ultrason., Ferroelec., Freq. Contr., 39, pp. 262-267, 1992. [11] Kjærgaard, Nina. "RASMUS." Center for Fast Ultrasound Imaging. Technical University of Denmark, 28 Sept. 2010. Web. 25 Feb. 2011..

80. 80 Questions?

81. Without TGCWith TGC 81

82. Using Delta as the Excitation SignalUsing REC (chirp) 82