The use of cross-polarization OCT in determining the dynamics of the state of pathological and normal tissues during radiation and photodynamic therapy

Abstract

The aim of the investigation was evaluating the possibilities of cross-polarization optical coherence tomography (CP OCT) to monitor the effectiveness of photodynamic therapy (PDT) and radiation therapy (RT) of the oral cancer and of the cervical cancer. Materials and Methods. The CP OCT investigation was performed by an OCT-1300U tomograph (Institute of Applied Physics of the Russian Academy of Sciences, LLC “Biomedtech”, Russia). The monitoring of the two types of treatment was performed after different periods of exposure: for RT of the oral cancer — once for every 2–3 days throughout the whole course of the treatment, starting from the first day of radiation; for the PDT of the cancers of the skin and cervix uteri — before the exposure, immediately after the exposure, and then at 1 day, 7 day and 1 month after the exposure. Fourteen patients were examined in total. Results. The results of the study of the medical pathomorphism of different kinds of tumors performed on the 14 patients showed that visual evaluation of CP OCT images of a tumor does not reveal any visible changes in response to RT, however it does register the reaction of the normal mucosa in the area exposed to the radiation. During the PDT of tumors of the skin and cervix mucosa CP OCT was capable of detecting the key morphological changes (edema, necrosis, and structural recovery). It can be applied most effectively at later stages of the follow-up observation (at 30–35 days after PDT) to evaluate the completeness of the recovery of the stromal component of the tissues. Conclusion. The use of CP OCT contributes to realization of non-invasive monitoring of the responses of tumors and the adjacent normal tissues to PDT and to RT that can be useful for evaluation of the effectiveness of therapy and to help in choosing optimal tactics for the treatment.