Towards personalized and versatile monitoring of temperature fields within heterogeneous tissues during laser therapies

Tailored cancer therapy by magnetic nanoparticle hyperthermia: A virtual scenario simulation method

BACKGROUND AND OBJECTIVE

Hyperthermia is a cancer treatment aiming to induce cell death by directly warming cancerous tissues above 40 °C. This technique can be applied both individually and together with other cancer therapies. The main challenge for researchers and medics is to heat only tumoral cells avoiding global or localized heating of sane tissues. The objective in this study is to provide a realistic virtual scenario to develop an optimized multi-site injection plan for tailored magnetic nanoparticle-mediated hyperthermia applications.

METHODS

A three-dimensional model of a cat's back was tested in three different simulation scenarios, showing the impact of magnetic nanoparticles in each specific environment configuration.

RESULTS

As a result of this study. This simulation method can, minimising the affection to healthy tissue.

CONCLUSIONS

This virtual method will help real and personalized therapy planning and tailor the dose and distribution of magnetic nanoparticles for an enhanced hyperthermia cancer treatment.

Multiphysical numerical study of photothermal therapy of glioblastoma with photoacoustic temperature monitoring in a mouse head

This paper presents a multiphysical numerical study of a photothermal therapy performed on a numerical phantom of a mouse head containing a glioblastoma. The study has been designed to be as realistic as possible. Heat diffusion simulations were performed on the phantom to understand the temperature evolution in the mouse head and therefore in the glioblastoma. The thermal dose has been calculated and lesions caused by heat are shown. The thermal damage on the tumor has also been quantified. To improve the effectiveness of the therapy, the photoabsorber's concentration was increased locally, at the tumor site, to mimic the effect of using absorbing contrast agents such as nanoparticles. Photoacoustic simulations were performed in order to monitor temperature in the phantom: as the Grüneisen parameter changes with the temperature, the photoacoustic signal undergoes changes that can be linked to temperature evolution. These photoacoustic simulations were performed at different instants during the therapy and the evolution of the photoacoustic signal as a function of the spatio-temporal distribution of the temperature in the phantom was observed and quantified. We have developed in this paper a numerical tool that can be used to help defining key parameters of a photothermal therapy.

Interferometric imaging of thermal expansion for temperature control in retinal laser therapy

Precise control of the temperature rise is a prerequisite for proper photothermal therapy. In retinal laser therapy, the heat deposition is primarily governed by the melanin concentration, which can significantly vary across the retina and from patient to patient. In this work, we present a method for determining the optical and thermal properties of layered materials, directly applicable to the retina, using low-energy laser heating and phase-resolved optical coherence tomography (pOCT). The method is demonstrated on a polymer-based tissue phantom heated with a laser pulse focused onto an absorbing layer buried below the phantom's surface. Using a line-scan spectral-domain pOCT, optical path length changes induced by the thermal expansion were extracted from sequential B-scans. The material properties were then determined by matching the optical path length changes to a thermo-mechanical model developed for fast computation. This method determined the absorption coefficient with a precision of 2.5% and the temperature rise with a precision of about 0.2°C from a single laser exposure, while the peak did not exceed 8°C during 1 ms pulse, which is well within the tissue safety range and significantly more precise than other methods.