Theoretical assessment of principal factors influencing laser interstitial thermotherapy outcomes on pancreas

Abstract

The influence of some therapy-relevant parameters on Laser Induced Interstitial Thermotherapy (LITT) outcomes on pancreas is assessed. The aim is to execute a sensitivity analysis for an optimal treatment strategy on in vivo pancreas. A numerical model based on Bioheat Equation has been implemented to assess the influence of laser settings (power P and energy E), applicator radius (r(f)) and optical properties (effective attenuation coefficient, μ(eff)) on temperature (T) distribution. Effects on pancreas undergoing LITT have been evaluated with a twofold approach: 1) T rise and maximum T (T(max)) in tissue; 2) injured volumes (vaporized and coagulated ones). We consider parameters range in typical LITT values (P from 1.5 W to 6 W, E from 500 J to 1500 J, r(f) from 150 µm to 600 µm) and optical values reported in literature. Our analysis shows that, among others, P and μ(eff) are the principal influencing factors of thermal effects on pancreas undergoing LITT: P should be carefully chosen by operator to obtain the desired injured volumes, while the accurate measurement of tissue optical properties is crucial to carry out a safe and controlled thermal therapy on pancreas.

Thermal ablation of pancreatic cancer: A systematic literature review of clinical practice and pre-clinical studies

“…Regarding the use of LA in preclinical and ex vivo settings, 12 articles have been included according to the selection criteria [18][19][20][21][22][23][24][25][26][27][28][29]. They present the use of laser light for therapy purpose, also in combination with nanotechnology ( Table 1).…”

“…In collaboration with Di Matteo [19,21,[24][25][26][27][28], our group deeply investigated the thermal response of pancreatic tissue undergoing LA. In these years, the procedure was always performed by guiding the laser light emitted by Nd:YAG system (1064 nm wavelength) though one or multiple bare optical quartz fibers (0.3 mm-diameter).…”

Design of fiber optic applicators for laser interstitial thermotherapy: Theoretical evaluation of thermal outcomes

“…Photons absorption within the tissue entails a temperature increase, that can be estimated by the Bio Heat Equation [6][7][8][9]:…”

“…Simulations are performed at two P (i.e., 3 W and 5 W) and E=1650 J, according to typical settings of clinical LITT procedures [6,7,8].…”

Characterization of fiber optic distributed temperature sensors for tissue laser ablation

“…LA is similar to other minimally invasive alternatives to surgical resection, such as Radio-Frequency Ablation (RFA) or MicroWave Ablation (MWA), but exploits the absorption of laser light from tissue to locally increase the temperature above cytotoxic levels (60 • C). This approach has become one of the elective treatments for small (less than 2 cm) solid tumors [12]; however, despite its increasing adoption, the outcomes could be further improved with the adoption of proper real-time temperature measurement systems, given the difficulty in predicting a priori the size of the area where cytotoxic temperature levels are reached without causing carbonizations [13]. The developed probe could help overcoming these limitations.…”