title: Reduction of thermal damage in photodynamic therapy by laser irradiation techniques.
abstract: General application of continuous-wave (CW) laser irradiation modes in photodynamic therapy can cause thermal damage to normal tissues in addition to tumors. A new photodynamic laser therapy system using a pulse irradiation mode was optimized to reduce nonspecific thermal damage. In in vitro tissue specimens, tissue energy deposition rates were measured in three irradiation modes, CW, pulse, and burst-pulse. In addition, methods were tested for reducing variations in laser output and specific wavelength shifts using a thermoelectric cooler and thermistor. The average temperature elevation per 10 J/cm2 was 0.27°C, 0.09°C, and 0.08°C using the three methods, respectively, in pig muscle tissue. Variations in laser output were controlled within ± 0.2%, and specific wavelength shift was limited to ± 3 nm. Thus, optimization of a photodynamic laser system was achieved using a new pulse irradiation mode and controlled laser output to reduce potential thermal damage during conventional CW-based photodynamic therapy.
authors.affiliation: Chungnam National University, College of Medicine, Department of Biomedical Engineering, Chungnam National University Hospital, Faculty Building 2036, Daesa Dong 640, Jung-Gu, Daejeon, Republic of Korea. hslim@cnu.ac.kr
authors.forename: Hyun Soo
authors.initials: HS
authors.lastname: Lim
mesh_terms: D000818:Animals; D002056:Burns / Q000209:etiology / Q000517:prevention & control*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005246:Feedback; D066298:In Vitro Techniques; D053685:Laser Therapy / Q000009:adverse effects* / Q000295:instrumentation; D018482:Muscle, Skeletal / Q000187:drug effects / Q000293:injuries / Q000528:radiation effects*; D010778:Photochemotherapy / Q000009:adverse effects* / Q000295:instrumentation*; D017319:Photosensitizing Agents / Q000627:therapeutic use; D012815:Signal Processing, Computer-Assisted / Q000295:instrumentation*; D013552:Swine; D013817:Thermography / Q000295:instrumentation*
chemical_list: D017319:Photosensitizing Agents