Photothermal Signature Characterization of Breast Microcalcifications Ex-Vivo by Photoacoustic Method

Abstract

Photothermal signatures of microcalcifications (MC) represented an important marker, that possibly later using the pulsed photoacoustic technique, this anomaly could be detected in early stages. Currently, MC are diagnosed by radiological images, however, their resolution is an impediment to detect smaller MC (<1 μm). For these reasons, this work presents pulsed photoacoustic technique as a possible method for microcalcifications early detection of and is also a non-invasive method. This method consists of irradiating the sample with near infrared light, and part of this light is absorbed by the microcalcifications, where these are heated causing a thermoelastic effect which generates mechanical waves that propagate at the sound speed and are detected by ultrasound sensors. The mechanical waves transmit information of the MC optical properties and when analyzing the amplitude, the delay time of the PA signal, and the vibrational modes of the frequency spectrum (FFT), it was possible to obtain the photothermal signature characteristic of microcalcifications and its depth in the breast tissue.