title: Theoretical analysis and experimental evaluation of laser-induced interstitial thermotherapy in ex vivo porcine pancreas.
abstract: Laser-induced interstitial thermotherapy (LITT) has been recently applied to pancreas in animal models for ablation purpose. Assessment of thermal effects due to the laser-pancreatic tissue interaction is a critical factor in validating the procedure feasibility and safety. A mathematical model based on bioheat equation and its experimental assessment was developed. The LITT procedure was performed on 40 ex vivo porcine pancreases, with an Nd:YAG (1064 nm) energy of 1000 J and power from 1.5 up to 10 W conveyed by a quartz optical fiber with 300 μm diameter. Six fiber Bragg grating sensors have been utilized to measure temperature distribution as a function of time at fixed distances from the applicator tip within pancreas undergoing LITT. Simulations and experiments show temperature variations Δ T steeply decreasing with distance from the applicator at higher power values: at 6 W, ∆T > 40 °C at 5 mm and Δ T is approximately equal to 5 °C at 10 mm. Δ T nonlinearly increases with power close to the applicator. Ablated and coagulated tissue volumes have also been measured and experimental results agree with theoretical ones. Despite the absence of data in the current literature on pancreas optical parameters, the model allowed a quite good prediction of thermal effects. The prediction of LITT effects on pancreas is necessary to assess laser dosimetry.
authors.affiliation: Center for Integrated Research, Università Campus Bio-Medico di Roma, Rome, Italy. p.saccomandi@unicampus.it
authors.forename: Paola
authors.initials: P
authors.lastname: Saccomandi
authors.forename: Emiliano
authors.initials: E
authors.lastname: Schena
authors.forename: Michele Arturo
authors.initials: MA
authors.lastname: Caponero
authors.forename: Francesco Maria
authors.initials: FM
authors.lastname: Di Matteo
authors.forename: Margareth
authors.initials: M
authors.lastname: Martino
authors.forename: Monica
authors.initials: M
authors.lastname: Pandolfi
authors.forename: Sergio
authors.initials: S
authors.lastname: Silvestri
mesh_terms: D000818:Animals; D003198:Computer Simulation; D006651:Histocytochemistry; D006979:Hyperthermia, Induced / Q000009:adverse effects / Q000295:instrumentation / Q000379:methods*; D053844:Lasers, Solid-State; D008954:Models, Biological; D010179:Pancreas / Q000473:pathology* / Q000528:radiation effects*; D013552:Swine; D013696:Temperature; D062125:Thermometry / Q000295:instrumentation