OCT/OCTA-guided laser ablation for tumor treatment

Laser ablation has come an alternative solution for tumor treatment, and it can be used to remove or shrink tumor tissue. In the previous reports, the pulsed lasers are the most common laser as the light source of laser treatment due to the controllable thermal damage, but it is difficult to use continuous-wave (CW) lasers for tissue ablation because of unpredictable laser damage and thermal effect. Typically, the CW lasers are cost effective in comparison to the pulsed lasers. Additionally, it is also challenging to accurately identify the tumor region for laser therapy to avoid the extra damage on the surrounding tissue. To overcome the limitation of using CW lasers for tumor therapy and to identify the tumor region for laser therapy, an imaging method to monitor the thermal effect induced by the CW laser in real time and to distinguish the tumor region is required. In this study, we develop an optical coherence tomography (OCT)/optical coherence angiography (OCA)-guided laser treatment system with a CW laser diode which is significantly much cheaper than pulsed lasers. To investigate the laser-induced thermal damage, a method based on the analysis of the OCT backscattered intensity is proposed. Moreover, the thermal effect on the vessels of skin is also quantitatively investigated. However, to accurately identify the tumor region, OCT and OCA results could be effective indicators according to the difference of normal and tumor tissue in the backscattered intensity and the vascular distribution. The automatic and objective identification of tumor region can be achieved based on deep learning, enabling to discriminate the tumor tissue with a high sensitivity of 97 %. Finally, the integrated system and the proposed method are implemented for the treatment of skin tumor on the mouse model. The results illustrate that the OCT/OCA-guided laser ablation system can accurately and effectively remove tumor tissues with controllable photodamage. Moreover, the system cost may be significantly reduced by using the continuous wave laser diode.