Fifty-seventh annual meeting of the American association of physicists in medicine
MO-F-CAMPUS-I-05: The Total Internal Reflection Based Elastography Method for Tissue Elasticity Quantification and Characterization
Diagnosing early formation of tumors or lumps, particularly those caused by cancer, has been a problem. Our goal is to develop a simple and easy to use system that can document the properties of palpable lumps in soft tissue using noninvasive technique.
The tactile sensor we propose comprises of an elastic optical waveguide unit, a high resolution CCD camera unit, a LED light source unit, and a laptop computer. The sensing element is formed on poly dimethylsiloxane (PDMS) and is illuminated along its four edges by LED light sources. The tactile sensor operates on the principle of total internal reflection (TIR) within an optical waveguide. The light directed into the waveguide remains within it due to the TIR generated, since the waveguide is surrounded by air having a lower refractive index than the waveguide. When an object adheres to the waveguide and compresses, the contact area of the waveguide deforms and causes the light to scatter.
To validate the proposed method, three patients presented with a lesion that was initially detected by another modality (mammography, ultrasound, or manual palpation). When performing the sensor scans, the doctor already knew where the lesions were located. For each lesion, 10 tactile images were obtained and the estimated parameters were averaged. Regarding the hardness estimation of the lesions, malignant breast lesion of the patient 1 had increased Young's modulus (146 kPa), compared to benign lesions (97 kPa and 103 kPa, patient 2 and 3). The elasticity information was correlated with the malignancy data from the pathology reports. The minimum and maximum relative errors are 1.1% and 11.72%. The mean error is 5.07% with 3.39% standard deviation.
In this paper, a tactile elasticity imaging sensor using the total internal reflection principle is designed and experimentally evaluated.