Development of a fiber optic probe for tumor laser ablation with integrated temperature measurement capabilities

L'abstract è presente nell'allegato / the abstract is in the attachmen

Temperature Distribution Mapping Using an FBG-Equipped Probe for Solid Tumor Laser Ablation

In recent years, laser ablation treatments have become promising therapies for early-stage solid tumors, although the anatomical variability within the irradiated organs (i.e., presence of blood vessels and other inhomogeneities) greatly challenges the control of the tissue temperature throughout the medical procedure and thus the optical therapeutic outcome. To help getting around these limitations, a new fiber optic probe able to both deliver the laser light with optimal irradiation pattern and measure the temperature in the tumor region had been previously developed. This paper, using simulations validated with experimental data, aims at demonstrating how this probe, combined with suitable hyperthermal treatment planning, can be used to overcome the discrepancies between ex-vivo and in-vivo laser ablation procedures

Characterization of fiber optic distributed temperature sensors for tissue laser ablation

Fiber optics is the most promising technology for distributed temperature sensing. The paper investigates the characterization of probes based on single or multiplexed fiber Bragg gratings, specifically conceived to evaluate the temperature distribution in applications that imply large temperature gradients, such as in laser induced thermal treatments of solid tumors. A setup for the characterization of fiber Bragg grating sensors in non uniform temperature conditions is described and examples of applications in case that mimic actual working conditions are reported

Towards inline spatially resolved temperature sensing in thermal ablation with chirped fiber Bragg grating

We investigate the theory and feasibility of an in-line spatially resolved temperature sensor, suitable for thermal ablation monitoring. The sensor is based o a chirped fiber Bragg grating (CFBG). The CFBG is modelled as a chain of Bragg gratings, each sensitive to local temperature variations. By using a combination of iterative and statistical optimization techniques, it is possible to use demodulate the CFBG, in case of a Gaussian-like spatial temperature profile. A feasibility test based on CFBG simulation shows that the CFBG returns error <1 mm on cells damage threshold spatial estimation and good noise resilience

A Fiber Optic Probe for Tumor Laser Ablation with Integrated Temperature Measurement Capability

The paper presents the characterization results of a new all-optical applicator for improved tumor laser ablation treatments that features customized irradiation pattern and builtin temperature sensors. The probe exploits a double cladding optical fiber to integrate some Bragg gratings acting as temperature sensing elements in the core, while guiding the high power beam used for the ablation in the inner cladding. The assessment of the probe behavior has been conducted in two steps: first, with an agar gel phantom to characterize the irradiation pattern and to validate the Bragg grating based measurement setup in comparison with a thermographic camera; then, simulating actual treatments using an ex-vivo animal liver

Pro- and anti-oxidant properties of near-infrared (NIR) light responsive carbon nanoparticles

Elemental carbon nanomaterials (ECNMs) are redox active agents that can be exploited to purposely modify the redox balance of cells. Both pro- or antioxidant properties have been reported. However, to the best of our knowledge, there are not comprehensive studies exploring both properties on the same material in view of a potential application in medicine. At the same time, the effect of the bulk structure on the pro/antioxidant properties is poorly known. Here, carbon nanoparticles (CNPs) derived by glucose with definite size and shape have been prepared, and their redox properties evaluated in cell free systems in the dark or following activation with a Near Infrared (NIR) laser beam (945 nm, 1.3 W/cm2). We found that, when irradiated with NIR, CNPs efficiently generate heat and singlet oxygen (1O2), a property that can be exploited for dual photo-thermal (PT)/photodynamic (PD) therapy in cancer. On the other hand, in the absence of photo-activation, CNPs react with both oxidant (hydroxyl radicals) and antioxidant (glutathione) species. When tested on a murine macrophages cell line (RAW 264.7) CNPs were clearly antioxidant. Furthermore, albeit efficiently internalized, CNPs do not exert cytotoxic effect up to 80 µg/ml and do not exacerbate TNF-α-mediated inflammation. Overall, the results reported herein suggest that CNPs may represent a new class of safe nanomaterials with potential applications in medicine

Linearly chirped fiber Bragg grating response to thermal gradient: from bench tests to the real-time assessment during in vivo laser ablations of biological tissue

The response of a fiber optic sensor [linearly chirped fiber Bragg grating (LCFBG)] to a linear thermal gradient applied on its sensing length (i.e., 1.5 cm) has been investigated. After these bench tests, we assessed their feasibility for temperature monitoring during thermal tumor treatment. In particular, we performed experi- ments during ex vivo laser ablation (LA) in pig liver and in vivo thermal ablation in animal models (pigs). We investigated the following: (i) the relationship between the full width at half maximum of the LCFBG spectrum and the temperature difference among the extremities of the LCFBG and (ii) the relationship between the mean spectrum wavelength and the mean temperature acting on the LCFBG sensing area. These relationships showed a linear trend during both bench tests and LA in animal models. Thermal sensitivity was significant although different values were found with regards to bench tests and animal experiments. The linear trend and significant sensitivity allow hypothesizing a future use of this kind of sensor to monitor both temperature gradient and mean temperature within a tissue undergoing thermal treatment

A compact diode laser based all-fiber delivery system for PDT+PTT with integrated temperature sensing capabilities

The paper first reviews the main laser based cancer therapies and then presents a new 9xx nm high power laser diode system specifically devised to irradiate carbon graphitic nanoparticles that have shown photodynamic and photo-thermal behavior when exposed to near-IR laser light. The peculiarity of the laser system is that its delivery is through a fiber probe that integrates Bragg gratings to allow monitoring the induced temperature increase without introducing artifacts due to the interaction with the laser beam. Experimental validations through EPR spectrum and temperature measurements on hydroxylated fullerene and carbon nanoparticle samples are provided to assess the effectiveness of the developed system

On the customization of the irradiation patterns of probes for laser tumor ablation with integrated temperature sensing capabilities

The paper reports some results on the customization of the irradiation pattern of an all-fiber applicator for laser induced thermal therapies of solid tumors. The probe exploits a double cladding fiber structure to simultaneously guide the high power beam for the ablation and the signals for the interrogation of embedded Bragg gratings that add temperature sensing capabilities. The probe was characterized using phantoms so as to mimic real situations while providing a repeatable environment for comparing the different solutions in terms of irradiation pattern shapes and induced temperature profiles