Clinical application of the mirror irradiation technique in photodynamic therapy for malignant glioma

• Published in: Photodiagnosis and photodynamic therapy 2020-09, Vol.31, p.101956-101956, Article 101956
• Main Authors: Fukami, Shinjiro, Akimoto, Jiro, Nagai, Kenta, Ichikawa, Megumi, Ogawa, Emiyu, Arai, Tsunenori, Kohno, Michihiro
• Format: Article
• Language: English
• Subjects: Glioma - drug therapy; Glioma - radiotherapy; Humans; Lasers; Malignant glioma; Mirror irradiation; Neoplasm Recurrence, Local - drug therapy; Photochemotherapy - methods; Photodynamic therapy; Photosensitizing Agents - therapeutic use; Talaporfin sodium
• ISSN: 1572-1000; 1873-1597
• DOI: 10.1016/j.pdpdt.2020.101956

•We developed a mirror reflecting system against blinds spots in PDT for malignant glioma.•The energy efficiency was approximately 70 %, and 9 patients were treated without complication.•Recurrence did not occur in the site where mirror irradiation was performed. Intraoperative photodynamic therapy (PDT) using talaporfin sodium for malignant glioma is effective both in the experimental and in the clinical setting. Because the irradiation unit is fixed to the objective lens of the operating microscope, blind spots for irradiation exist. To overcome this problem, we developed a mirror reflecting system using a modified dental mirror. The developed mirror is made of stainless steel, has a mirror-polished surface, and is rhodium coated on 1 side, which is the reflecting surface. The reflection rate was measured using He-Ne laser irradiation. The reflection intensity was measured using a laser power meter when the incident angle to the mirror was changed to 60°, 45°, and 30°, and the reflectance was calculated by the direct received light intensity from the laser. After confirming the safety of the fundamental experiment, PDT was performed with this developed mirror on 9 patients with malignant glioma (4 with recurrence and 5 newly diagnosed). The energy efficiency of the mirror was approximately 70 %, and apparent irregular reflection was not observed. Even during clinical use, apparent complications, such as irregular reflection, did not occur upon using the mirror in any of the patients. In all patients, recurrence did not occur in the site where mirror irradiation was performed, but in a deep site or a distant site to which sufficient laser irradiation did not reach. PDT using our newly developed mirror involves few instrumental changes compared with the conventional irradiation method, and is effective, safe, and inexpensive.