# Wavelia Breast Imaging: The Optical Breast Contour Detection Subsystem
## 4 Conclusions  
In this paper, a new calibration algorithm for turntable-based 3D scanning systems, a new method for 3D surface reconstruction from point cloud based on a linear stretching function, and a breast volume computation method, which have been designed for and integrated in the OBCD subsystem of the Wavelia prototype breast imaging medical device, have been thoroughly presented. Indicative experimental results with two test breast phantoms and preliminary results from ten patient scans have demonstrated the efficacy of the system in reconstructing with high precision the external envelope of a female patient's breast hanging below the examination table, while the patient is in prone position. This consists in very valuable input information for the second counterpart of the Wavelia medical device, the MBI subsystem, which aims at detecting the presence of breast pathologies, based on the contrast, in terms of dielectric properties, between healthy and malignant breast tissue. The envelope of the breast being scanned with the microwave breast imaging system is essential to be known for any detection in the microwave image to be meaningfully referenced in space. In addition, specifically for microwave breast imaging, as the dielectric properties of the interior of the breast are unknown, while the dielectric properties of the transition medium are known, the breast envelope which is extracted at first also serves as boundary between the two electromagnetic wave propagating media (dielectrically known exterior of the breast versus dielectrically unspecified interior of the breast), which is very important a priori information for any microwave imaging algorithm, further on. The spatial resolution of the OBCD (optical) subsystem is significantly finer than the one of the MBI (microwave) subsystem, but the optical subsystem cannot penetrate the breast skin, while the microwave subsystem can. The interest in fusing the optical and microwave data is exactly to profit from a highly detailed breast envelope, as spatial reference for any abnormalities of the breast tissues being detectable with microwaves. The Wavelia prototype medical device has only recently been installed at the Galway University Hospital, Ireland, for its first-in-human pilot clinical test. To this day, the system has been tested on twenty patients in total (the aim being to test it on thirty patients by the end of this first-in-human clinical investigation). The OBCD subsystem, which has been the main focus of this paper, has been evaluated positively by the users, so far, and generated reliable data which are being efficiently exploited in the ongoing off-line processing of the MBI subsystem datasets. A first encouraging patient result, involving the detection of a palpable Invasive Ductal Carcinoma (IDC) of approximate size 15 mm in the breast of a 44-year old patient, using the Wavelia breast imaging medical device, has been presented in [35]. More complete associated clinical data results will be included in future publications on the Wavelia Microwave Breast Imaging system. The proposed method for new 3D surface reconstruction from point clouds has been designed based on the shape of the breast when the patient is in prone position on the examination table (Wavelia MBI and OBCD subsystems). However, beyond this specific application, the method could be also used to reconstruct objects other than the breast, as long as the object is representable with the shape of a cone or a cylinder (e.g., the breast can be represented by a cone). The proposed calibration method could be used to calibrate any turntable-based 3D scanning system, in general.