WO2017055883A1

WO2017055883A1 - 3d spectracoustic system: a modular, tomographic, spectroscopic mapping, non- invasive imaging diagnostic system

Info

Publication number: WO2017055883A1
Application number: PCT/GR2016/000047
Authority: WO
Inventors: Th. Georgios KARAGIANNIS
Original assignee: Karagiannis Th Georgios
Priority date: 2015-09-28
Filing date: 2016-09-27
Publication date: 2017-04-06
Also published as: GR1008824B; DE112016004385T5

Abstract

The current patent is aiming to describe the combined use of high frequency ultrasonic and photonic technologies in the infrared area of the spectrum through the use of a common probe. This common probe can excite the under diagnosis/ study object using both the modalities simultaneously or in serial mode resulting to the acquisition of the tomographic information from the object as well as its spectroscopic reflectance/ absorbance information in the infrared area of the spectrum. The combination of the two technologies can be called as spectracoustic method.

Description

3D Spectracoustic system: A modular, tomographic, spectroscopic mapping, non invasive imaging diagnostic system

1. Background of the invention

The modalities that are combined are described in the following two paragraphs:

1.1 Acoustic Microscopy

In the simplest and most widely employed non-destructive testing (NDT) applications, a single piezoelectric transducer is used to excite an acoustic wave into the object under test. In most cases, the transducer is placed inside water and the wave propagates through the water medium into the object. This technique has the advantage of making the transducer readily movable. Generally, the matching between the transducer and the object investigated, in this case a skin-melanoma, is a very crucial factor in acoustic microscopy resolution and accuracy. This can be significantly enhanced using a thin rubber layer or gel for better contacting between the acoustic source and the object. This technique is very convenient especially in medical diagnostic imaging applications. Supposing that the acoustic source is excited by a short electrical pulse, the wave generated by the transducer will be a short acoustic pulse that will propagate through the object and eventually will be reflected by acoustic impedance discontinuities. These can be caused by flaws or internal structures inside the object (Figure 2). These reflections are caused by the surfaces of different layers' materials in the stratigraphy of the skin melanoma. The reflected signals can be amplified and viewed in an oscilloscope. The time-difference of an echo appearing in the recorder signal can be used to identify the distance of the flaw (from the transducer), while the amplitude of the reflected echo is proportional to the size and shape of the flaws. This technique is known as the amplitude-scan or A-scan. The main disadvantage of A-scan imaging is that this method is very slow and tedious to use. An alternative technique is the brightness-scan or B-scan method, in which the echo signal is used to modulate the intensity of the spot on an oscilloscope, while the time delay is represented by the horizontal position of the spot. The mechanical position along the surface of the object is represented by the vertical position of the spot on the oscilloscope. A third output for acoustic imaging is known as the C-scan, where reflection imaging is used to form an image in a plane that is perpendicular to the direction of propagation of the acoustic beam. The object is mechanically scanned across the beam, while the beam itself is moved transversal, to create a raster scan. The amplitude of the received signal is used to vary the intensity of a light-spot displayed on-screen. The advantage of C-scans is that this method gives high-resolution images of thin-objects. Acoustic microscopy is the term used to describe the ultrasound based techniques and systems with operating frequencies of the order of higher than 50MHz. 1.2 IR Spectroscopy

The IR spectrometer consists of three basic optical elements: a) an IR source, b) an interferometer, which comprises a beam splitter and two mirrors, one fixed and one moving, and c) a detector. The working principle of an IR spectrometer is briefly illustrated in Figure 3. The beam produced by the IR source passes through an aperture. Then it is optically filtered before entering into the interferometer, which constitutes the "heart" of the spectrometer. The motion of the interferometer' s moving mirror modulates the light beam, which then exits the interferometer and it is led to the sample. The light that was transmitted through or reflected by the sample is finally focused on the detector, which measures its intensity, i.e., its power. The signal at the detector, i.e., the interferogram, is amplified, filtered and digitized, before being processed to produce the sample's spectrum. The choice of the technical characteristics of the three optical elements depends on the wanted spectral region, i.e., near IR (nIR), mid IR (mIR) and far IR (fIR), to be measured. Although the main working principles are the same, the design of the interferometer is based on that of the two-beam interferometer originally designed by Michelson in 1891. The theory behind all state of the art two-beam interferometers is similar to the theory behind the Michelson interferometer.

2. Detailed description of the invention

The system is capable of acquiring information about the tomographic/3D structure and the "distribution" of the materials, the chemical composition or in the case of biomedical applications the biochemical "changes" in this 3D structure.

The system is capable of providing the 3D spectroscopic mapping information of a multi-layered structure. Similarly, is capable to provide a 3D spectroscopic mapping image of small tumours structures and serve as a robust tool for "in vivo" early detection of melanoma. This is achieved with the combined use of the described techniques in the previous paragraph and is presented schematically in Figure 1 and lexically accordingly; Using acoustic microscopy, the tomographic information (and not only) of the under study structure is obtained and using nIR and mIR spectroscopic mapping imaging in diffuse reflectance or in reflectance mode, the identification of crucial substances and their concentration that exist in the tomographic structure can be achieved. The crucial and novel concept and part of the system are:

1. The 3D spectroscopic mapping imaging system or as a novel term 3D spectracoustic mapping imaging system (Figure 1).

2. A special fabricated combined acoustic microscopy transducer and infrared iUumination probe permitting the simultaneous acquisition of the spectroscopic and the tomographic information (Figure 4 and Figure 5). This probe provides with the capability of high fidelity and precision registered information from the combined modalities.

The device is designed in order to achieve the aforementioned concept and efficiently use of the designed probe. A standard pulser system excites transducer which is located to the center of the combined probe with pulses of 2ns width with a bandwidth of 500MHz. The electrical pulses are transmitted to mechanical waves through the use of the transducer and the power of the acoustic wave is inserted in the under study object. Parallel to the path used for the excitation of the piezoelectric transducer a fiber optic bundle path is also designed in order to guide the iUurnination using the output infrared beam form the device displayed in Figure 3 and Figure 4 and consequently, guide the reflected infrared power from the under study object into the sensor of the device (Figure 3). The curve of the face of the probe is designed in order the focal point of the ultrasonic (acoustic microscopy) transducer to be the same with the focal point of the illumination of the infrared beam achieving the receiving of the reflection from both the modalities form exactly the same point. The excitation of the spectroscopic modality is displayed in Figure 4 and Figure 5; the beam produced by the IR source passes through the fiber optic bundle for the iUurnination of the area of examination. The fiber optic bundle located nearer the axial center of the probe is guiding the illumination beam marked with yellow colour in Figure 4 and Figure 5. The resulting reflected spectra from the illurninated area are transmitted back through the receiving fiber optic bundle which also presented in Figure 5 marked with orange colour.

Then by scanning a region of interest the acquisition of the tomographic information and the spectroscopic one from the exactly the same array points of the scanned area is achieved. The case of a small melanoma tumour is presented in Figure 6 and Figure 7. BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 : General concept of the proposed system

Figure 2: Acoustic microscopy principle

Figure 3: Infrared (IR) spectroscopic mapping imaging principle

Figure 4: Block diagram of the spectracoustic mapping imaging system

Figure 5: Two designs of the spectracoustic probe

Figure 6: The acoustic microscopy tomographic information form a melanoma

Figure 7: The spectroscopic mapping information fused with the acoustic microscopy tomographic information from a melanoma using the spectracoustic probe REFERENCES

[1] G. Karagiannis, "Development of a non-invasive system for the early detection of melanoma with the combined use of acoustic microscopy from 50 up to 175MHz, IR reflectance from 0.4μπι up to ΙΟμπι., Raman spectroscopy, 9th International Conference on Ultrasonic Biomedical Micro scanning, University of Edinburg, 28th September 2014 - 1st October 2014.

[2] G. Karagiannis, G. Apostolidis, K. Vavliakis, G. Grivas, A. Tsingotjidou, I. Dori, P. Georgoulias, Use of signal processing techniques applied to acoustic microscopy echo graphs in order to support the detection of melanoma infiltration using time frequency representation techniques, 6o Πανελλήνιο Συνέδριο Βιοϊατρικής Τεχνολογίας 6-8 Μαΐου 2015, Αθήνα, Ελλάδα. Georgios T. Karagiannis; Ioannis Grivas; Anastasia Tsingotjidou; Georgios K. Apostolidis; Ifigeneia Grigoriadou, I. Don, Kyriaki-Nefeli Poulatsidou, Argyrios Doumas, Stefan Wesarg, Panagiotis Georgoulias,," Early detection of melanoma with the combined use of acoustic microscopy, infrared reflectance and Raman spectroscopy ", Proc. SPIE 9323, Photons Plus Ultrasound: Imaging and Sensing 2015, 93232T (March 11, 2015); doi:10.1117/12.2079690; http://dx.doi.org/10.1117/12.2079690

G. Karagiannis, A. Tsingotjidou, I. Grivas, I. Grigoriadou, S. Wesarg, P. Georgoulias, "Development of a non-invasive system for the early detection of melanoma with the combined use of acoustic microscopy from 50 up to 175MHz, IR reflectance from 0.4μπι up to ΙΟμπι., Raman spectroscopy, 9th International Conference on Ultrasonic Biomedical Micro scanning, University of Edinburg, 28th September 2014 - 1st October 2014.

I. Grivas, G. Karagiannis, A. S. Tsingotjidou, I. Dori, I. Grigoriadou, S. Wesarg, P. Georgoulias, Experimental model for the study of melanoma Diagnostic approach with the combined use of acoustic microscopy and infrared spectroscopy, evaluated by histological analysis, Biomedical and Laboratory Animal Science for transnational research annual scientific meeting, Athens, on September 22-23, 2014 (1st price award).

Claims

1. A combined spectroscopic mapping imaging and acoustic microscopy system providing tomographic and material or biomaterial information from the under study 3D structure (Figure 1)·

2. A combined acoustic microscopy transducer and infrared illumination probe specifically designed to permit simultaneous acquisition of the tomographic and the 3D spectroscopic information (Figure 4 and Figure 5).

3. The introduction and claim of the technique term spectracoustic in the field of non-invasive diagnosis.

4. The introduction and claim of the technique and term of 3D spectroscopic mapping imaging and 3D spectracoustic mapping imaging.