A NOVEL SIGNAL PROCESSING METHOD BASED ON THE FREQUENCY MODALITY FOR INTRA-BODY MEDICAL INSTRUMENT TRACKING Dr. DIMITRIS A. FOTIADIS TECHNOLOGICAL EDUCATIONAL INSTITUTE OF WESTERN MAEDONIA (TEIWM) SCHOOL OF APPLIED SCIENCES DEPARTMENT OF INFORMATICS ENGINEERING KASTORIA CAMPUS GREECE

1 Presentation Outline Medical instrument position tracking method Measurement waveform processing methods Locally Weighted Scatter-Plot Smoothing (LOWESS) Locally Weighted Scatter-Plot Smoothing (LOWESS) Lomb-Scargle periodogram Lomb-Scargle periodogramConclusion Dr. DIMITRIS A. FOTIADIS Dr. DIMITRIS A. FOTIADIS A NOVEL SIGNAL PROCESSING METHOD BASED ON THE FREQUENCY MODALITY FOR INTRA-BODY MEDICAL INSTRUMENT TRACKING A NOVEL SIGNAL PROCESSING METHOD BASED ON THE FREQUENCY MODALITY FOR INTRA-BODY MEDICAL INSTRUMENT TRACKING

2 Novel medical instrument position tracking method Dr. DIMITRIS A. FOTIADIS Dr. DIMITRIS A. FOTIADIS A NOVEL SIGNAL PROCESSING METHOD BASED ON THE FREQUENCY MODALITY FOR INTRA-BODY MEDICAL INSTRUMENT TRACKING A NOVEL SIGNAL PROCESSING METHOD BASED ON THE FREQUENCY MODALITY FOR INTRA-BODY MEDICAL INSTRUMENT TRACKING

3 System implementation The system is implemented using modified Doppler radar units PLL with open loop design when transmitter displaced A constant transmitter displacement velocity results into a sinusoidal ZIF receiver voltage Dr. DIMITRIS A. FOTIADIS Dr. DIMITRIS A. FOTIADIS A NOVEL SIGNAL PROCESSING METHOD BASED ON THE FREQUENCY MODALITY FOR INTRA-BODY MEDICAL INSTRUMENT TRACKING A NOVEL SIGNAL PROCESSING METHOD BASED ON THE FREQUENCY MODALITY FOR INTRA-BODY MEDICAL INSTRUMENT TRACKING

4 Typical oscilloscope captured plot – Transmitter constant velocity 4cm/s Dr. DIMITRIS A. FOTIADIS Dr. DIMITRIS A. FOTIADIS A NOVEL SIGNAL PROCESSING METHOD BASED ON THE FREQUENCY MODALITY FOR INTRA-BODY MEDICAL INSTRUMENT TRACKING A NOVEL SIGNAL PROCESSING METHOD BASED ON THE FREQUENCY MODALITY FOR INTRA-BODY MEDICAL INSTRUMENT TRACKING

5 Noise filtering methods System precision is measured at zero crossing points The ZIF signal needs to be filtered, in order to perform precise distance measurements Two methods were used in time and frequency domain: LOWESS ( Locally Weighted Scatter-Plot Smoothing) LOWESS ( Locally Weighted Scatter-Plot Smoothing) Lomb-Scargle periodogram Lomb-Scargle periodogram Dr. DIMITRIS A. FOTIADIS Dr. DIMITRIS A. FOTIADIS A NOVEL SIGNAL PROCESSING METHOD BASED ON THE FREQUENCY MODALITY FOR INTRA-BODY MEDICAL INSTRUMENT TRACKING A NOVEL SIGNAL PROCESSING METHOD BASED ON THE FREQUENCY MODALITY FOR INTRA-BODY MEDICAL INSTRUMENT TRACKING

6 LOWESS LOWESS is a curve fitting or non-parametric regression analysis method This method is based on data analysis aiming at the creation of a set of points along a curve This method is based on data analysis aiming at the creation of a set of points along a curve Initially the regression weights are computed, for each sampled data point Dr. DIMITRIS A. FOTIADIS Dr. DIMITRIS A. FOTIADIS A NOVEL SIGNAL PROCESSING METHOD BASED ON THE FREQUENCY MODALITY FOR INTRA-BODY MEDICAL INSTRUMENT TRACKING A NOVEL SIGNAL PROCESSING METHOD BASED ON THE FREQUENCY MODALITY FOR INTRA-BODY MEDICAL INSTRUMENT TRACKING

7 LOWESS The weights for each data point are given by: where x is the predictor value associated with the response value to be smoothed, x i are the neighbors that are nearest at x as defined by the span and d(x) is the distance along the abscissa from x to the most distant predictor value within the span Dr. DIMITRIS A. FOTIADIS Dr. DIMITRIS A. FOTIADIS A NOVEL SIGNAL PROCESSING METHOD BASED ON THE FREQUENCY MODALITY FOR INTRA-BODY MEDICAL INSTRUMENT TRACKING A NOVEL SIGNAL PROCESSING METHOD BASED ON THE FREQUENCY MODALITY FOR INTRA-BODY MEDICAL INSTRUMENT TRACKING

8 LOWESS Next, a weighted linear least squares regression is performed into the data set. The regression employs a first degree polynomial Next, a weighted linear least squares regression is performed into the data set. The regression employs a first degree polynomial The smoothed value is given by the weighted regression at the predictor value of interest The smoothed value is given by the weighted regression at the predictor value of interest The LOWESS method is superior for unevenly sampled data, whereas the least squares smoothing method is not The LOWESS method is superior for unevenly sampled data, whereas the least squares smoothing method is not Dr. DIMITRIS A. FOTIADIS Dr. DIMITRIS A. FOTIADIS A NOVEL SIGNAL PROCESSING METHOD BASED ON THE FREQUENCY MODALITY FOR INTRA-BODY MEDICAL INSTRUMENT TRACKING A NOVEL SIGNAL PROCESSING METHOD BASED ON THE FREQUENCY MODALITY FOR INTRA-BODY MEDICAL INSTRUMENT TRACKING

9 LOWESS smoothed waveform Dr. DIMITRIS A. FOTIADIS Dr. DIMITRIS A. FOTIADIS A NOVEL SIGNAL PROCESSING METHOD BASED ON THE FREQUENCY MODALITY FOR INTRA-BODY MEDICAL INSTRUMENT TRACKING A NOVEL SIGNAL PROCESSING METHOD BASED ON THE FREQUENCY MODALITY FOR INTRA-BODY MEDICAL INSTRUMENT TRACKING

10 Lomb-Scargle periodogram Lomb-Scargle periodogram the most common signal spectrum analysis method for small amplitude signals with periodicity Lomb-Scargle periodogram the most common signal spectrum analysis method for small amplitude signals with periodicity It is often called LSSA: Least-Squares Spectral Analysis It is often called LSSA: Least-Squares Spectral Analysis It is a method which does not require interpolation and resampling It is a method which does not require interpolation and resampling Dr. DIMITRIS A. FOTIADIS Dr. DIMITRIS A. FOTIADIS A NOVEL SIGNAL PROCESSING METHOD BASED ON THE FREQUENCY MODALITY FOR INTRA-BODY MEDICAL INSTRUMENT TRACKING A NOVEL SIGNAL PROCESSING METHOD BASED ON THE FREQUENCY MODALITY FOR INTRA-BODY MEDICAL INSTRUMENT TRACKING

11 Lomb-Scargle periodogram A periodogram is actually a graph showing frequency power for a specific spectrum of frequencies A periodogram is actually a graph showing frequency power for a specific spectrum of frequencies A peak in a periodogram indicates a frequency with significant periodicity A peak in a periodogram indicates a frequency with significant periodicity The sinusoidal ZIF captured waveform is a periodical signal The sinusoidal ZIF captured waveform is a periodical signal Dr. DIMITRIS A. FOTIADIS Dr. DIMITRIS A. FOTIADIS A NOVEL SIGNAL PROCESSING METHOD BASED ON THE FREQUENCY MODALITY FOR INTRA-BODY MEDICAL INSTRUMENT TRACKING A NOVEL SIGNAL PROCESSING METHOD BASED ON THE FREQUENCY MODALITY FOR INTRA-BODY MEDICAL INSTRUMENT TRACKING

12 Lomb-Scargle periodogram experimental signal analysis Dr. DIMITRIS A. FOTIADIS Dr. DIMITRIS A. FOTIADIS A NOVEL SIGNAL PROCESSING METHOD BASED ON THE FREQUENCY MODALITY FOR INTRA-BODY MEDICAL INSTRUMENT TRACKING A NOVEL SIGNAL PROCESSING METHOD BASED ON THE FREQUENCY MODALITY FOR INTRA-BODY MEDICAL INSTRUMENT TRACKING

13 Differences between FFT and Lomb- Scargle periodogram Lomb-Scargle periodogram method weights data points, while the FFT method weights frequency intervals Lomb-Scargle periodogram method weights data points, while the FFT method weights frequency intervals Lomb Scargle periodogram can be efficiently used with unevenly sampled data, while the FFT cannot Dr. DIMITRIS A. FOTIADIS Dr. DIMITRIS A. FOTIADIS A NOVEL SIGNAL PROCESSING METHOD BASED ON THE FREQUENCY MODALITY FOR INTRA-BODY MEDICAL INSTRUMENT TRACKING A NOVEL SIGNAL PROCESSING METHOD BASED ON THE FREQUENCY MODALITY FOR INTRA-BODY MEDICAL INSTRUMENT TRACKING

14 Differences between FFT and Lomb- Scargle periodogram Lomb-Scargle periodogram method does not require any data imputation, while FFT does Lomb-Scargle periodogram method does not require any data imputation, while FFT does Any number of data points can be used in a Lomb Scargle periodogram, while the data points in FFT are 2 N and any missing points are zero- padded Any number of data points can be used in a Lomb Scargle periodogram, while the data points in FFT are 2 N and any missing points are zero- padded Dr. DIMITRIS A. FOTIADIS Dr. DIMITRIS A. FOTIADIS A NOVEL SIGNAL PROCESSING METHOD BASED ON THE FREQUENCY MODALITY FOR INTRA-BODY MEDICAL INSTRUMENT TRACKING A NOVEL SIGNAL PROCESSING METHOD BASED ON THE FREQUENCY MODALITY FOR INTRA-BODY MEDICAL INSTRUMENT TRACKING

15 LOWESS and Lomb-Scargle periodogram filtered waveforms Dr. DIMITRIS A. FOTIADIS Dr. DIMITRIS A. FOTIADIS A NOVEL SIGNAL PROCESSING METHOD BASED ON THE FREQUENCY MODALITY FOR INTRA-BODY MEDICAL INSTRUMENT TRACKING A NOVEL SIGNAL PROCESSING METHOD BASED ON THE FREQUENCY MODALITY FOR INTRA-BODY MEDICAL INSTRUMENT TRACKING

16 LOWESS and Lomb-Scargle periodogram medical instrument displacement measurement precision comparison Dr. DIMITRIS A. FOTIADIS Dr. DIMITRIS A. FOTIADIS A NOVEL SIGNAL PROCESSING METHOD BASED ON THE FREQUENCY MODALITY FOR INTRA-BODY MEDICAL INSTRUMENT TRACKING A NOVEL SIGNAL PROCESSING METHOD BASED ON THE FREQUENCY MODALITY FOR INTRA-BODY MEDICAL INSTRUMENT TRACKING

17 Conclusion LOWESS method can be used in cases where a medical instrument displaces into the human body without constant velocity LOWESS method can be used in cases where a medical instrument displaces into the human body without constant velocity Lomb-Scargle periodogram is ideal in cases where a medical instrument displaces into the human body with constant velocity Lomb-Scargle periodogram is ideal in cases where a medical instrument displaces into the human body with constant velocity A combination of both methods can provide optimum precision measurement results A combination of both methods can provide optimum precision measurement results Dr. DIMITRIS A. FOTIADIS Dr. DIMITRIS A. FOTIADIS A NOVEL SIGNAL PROCESSING METHOD BASED ON THE FREQUENCY MODALITY FOR INTRA-BODY MEDICAL INSTRUMENT TRACKING A NOVEL SIGNAL PROCESSING METHOD BASED ON THE FREQUENCY MODALITY FOR INTRA-BODY MEDICAL INSTRUMENT TRACKING

THANK YOU VERY MUCH QUESTIONS? Contact info.: Dimitris Α. Fotiadis