scholarly journals Fiber-Optic Temperature and Pressure Sensors Applied to Radiofrequency Thermal Ablation in Liver Phantom: Methodology and Experimental Measurements

2015 ◽  
Vol 2015 ◽  
pp. 1-22 ◽  
Author(s):  
Daniele Tosi ◽  
Edoardo Gino Macchi ◽  
Alfredo Cigada
Keyword(s):  
Thermal Ablation ◽  
Rayleigh Scattering ◽  
Fiber Optic ◽  
Optical Measurement ◽  
Ex Vivo ◽  
Pressure Sensors ◽  
Fiber Optic Sensor ◽  
Tissue Temperature ◽  
Biophysical Parameters ◽  
Radiofrequency Thermal Ablation

Radiofrequency thermal ablation (RFA) is a procedure aimed at interventional cancer care and is applied to the treatment of small- and midsize tumors in lung, kidney, liver, and other tissues. RFA generates a selective high-temperature field in the tissue; temperature values and their persistency are directly related to the mortality rate of tumor cells. Temperature measurement in up to 3–5 points, using electrical thermocouples, belongs to the present clinical practice of RFA and is the foundation of a physical model of the ablation process. Fiber-optic sensors allow extending the detection of biophysical parameters to a vast plurality of sensing points, using miniature and noninvasive technologies that do not alter the RFA pattern. This work addresses the methodology for optical measurement of temperature distribution and pressure using four different fiber-optic technologies: fiber Bragg gratings (FBGs), linearly chirped FBGs (LCFBGs), Rayleigh scattering-based distributed temperature system (DTS), and extrinsic Fabry-Perot interferometry (EFPI). For each instrument, methodology forex vivosensing, as well as experimental results, is reported, leading to the application of fiber-optic technologiesin vivo. The possibility of using a fiber-optic sensor network, in conjunction with a suitable ablation device, can enable smart ablation procedure whereas ablation parameters are dynamically changed.

scholarly journals Fiber-optic combined FPI/FBG sensors for monitoring of radiofrequency thermal ablation of liver tumors: ex vivo experiments

2014 ◽  
Vol 53 (10) ◽  
pp. 2136 ◽  
Author(s):  
Daniele Tosi ◽  
Edoardo Gino Macchi ◽  
Giovanni Braschi ◽  
Alfredo Cigada ◽  
Mario Gallati ◽  
...  
Keyword(s):  
Thermal Ablation ◽  
Fiber Optic ◽  
Liver Tumors ◽  
Ex Vivo ◽  
Radiofrequency Thermal Ablation ◽  
Fbg Sensors

Fiber-Optic EFPI/FBG Dual Sensor for Monitoring of Radiofrequency Thermal Ablation of Liver Tumors

CLEO: 2014 ◽  
2014 ◽  
Author(s):  
D. Tosi ◽  
E. G. Macchi ◽  
M. Gallati ◽  
G. Braschi ◽  
A. Cigada ◽  
...  
Keyword(s):  
Thermal Ablation ◽  
Fiber Optic ◽  
Liver Tumors ◽  
Radiofrequency Thermal Ablation ◽  
Dual Sensor

scholarly journals Ex-Vivo Measurement of the pH in Aqueous Humor Samples by a Tapered Fiber-Optic Sensor

Sensors ◽  
2021 ◽  
Vol 21 (15) ◽  
pp. 5075
Author(s):  
Ondřej Podrazký ◽  
Jan Mrázek ◽  
Jana Proboštová ◽  
Soňa Vytykáčová ◽  
Ivan Kašík ◽  
...  
Keyword(s):  
Cataract Surgery ◽  
Aqueous Humor ◽  
Fiber Optic ◽  
Ex Vivo ◽  
Sol Gel ◽  
Ph Sensor ◽  
Fiber Optic Sensor ◽  
Optic Sensor ◽  
Tapered Optical Fiber ◽  
Practical Demonstration

A practical demonstration of pH measurement in real biological samples with an in-house developed fiber-optic pH sensor system is presented. The sensor uses 8-hydroxypyrene-1,3,6-trisulfonate (HPTS) fluorescent dye as the opto-chemical transducer. The dye is immobilized in a hybrid sol-gel matrix at the tip of a tapered optical fiber. We used 405 nm and 450 nm laser diodes for the dye excitation and a photomultiplier tube as a detector. The sensor was used for the measurement of pH in human aqueous humor samples during cataract surgery. Two groups of patients were tested, one underwent conventional phacoemulsification removal of the lens while the other was subjected to femtosecond laser assisted cataract surgery (FLACS). The precision of the measurement was ±0.04 pH units. The average pH of the aqueous humor of patients subjected to FLACS and those subjected to phacoemulsification were 7.24 ± 0.17 and 7.31 ± 0.20 respectively.

Radiofrequency thermal ablation on ex-vivo swine thyroids: Morphometrical analysis of tissue changes

2019 ◽  
Vol 166 ◽  
pp. 121
Author(s):  
P. Pregel ◽  
E. Scala ◽  
M. Bullone ◽  
L. Nozza ◽  
R. Garberoglio ◽  
...  
Keyword(s):  
Thermal Ablation ◽  
Ex Vivo ◽  
Radiofrequency Thermal Ablation ◽  
Morphometrical Analysis ◽  
Tissue Changes

scholarly journals Miniature Fiber Optic Acoustic Pressure Sensors With Air-Backed Graphene Diaphragms

2019 ◽  
Vol 141 (4) ◽  
Author(s):  
Qian Dong ◽  
Hyungdae Bae ◽  
Zhijian Zhang ◽  
Yongyao Chen ◽  
Zhongshan Wen ◽  
...  
Keyword(s):  
Acoustic Pressure ◽  
Fiber Optic ◽  
Capillary Tube ◽  
Graphene Film ◽  
Pressure Sensors ◽  
Experimental Results ◽  
Fiber Optic Sensor ◽  
Mechanical Sensitivity ◽  
Sensor Performance ◽  
Silver Composite

Graphene has been known to possess exceptional mechanical properties, including its extremely high Young’s modulus and atomic layer thickness. Although there are several reported fiber optic pressure sensors using graphene film, a key question that is not well understood is how the suspended graphene film interacts with the backing air cavity and affects the sensor performance. Based on our previous analytical model, we will show that the sensor performance suffers due to the significantly reduced mechanical sensitivity by the backing cavity. To remedy this limitation, we will, through experimental and numerical methods, investigate two approaches to enhance the sensitivity of fiber optic acoustic pressure sensors using graphene film. First, a graphene–silver composite diaphragm is used to enhance the optical sensitivity by increasing the reflectivity. Compared with a sensor with pure graphene diaphragm, graphene–silver composite can enhance the sensitivity by threefold, while the mechanical sensitivity is largely unchanged. Second, a fiber optic sensor is developed with enlarged backing air volume through the gap between an optical fiber and a silica capillary tube. Experimental results show that the mechanical sensitivity is increased by 10× from the case where the gap side space is filled. For both approaches, signal-to-noise ratio (SNR) is improved due to the enhanced sensitivity, and comsol Thermoviscous acoustics simulation compares well with the experimental results. This study is expected to not only enhance the understanding of fluid–structural interaction in sensor design but also benefit various applications requiring high-performance miniature acoustic sensors.

scholarly journals Cystic echinococcosis of the liver and lung treated by radiofrequency thermal ablation: An ex-vivo pilot experimental study in animal models

2009 ◽  
Vol 15 (26) ◽  
pp. 3232 ◽  
Author(s):  
Vincenzo Lamonaca ◽  
Antonino Virga ◽  
Marta Ida Minervini ◽  
Roberta Di Stefano ◽  
Alessio Provenzani ◽  
...  
Keyword(s):  
Experimental Study ◽  
Animal Models ◽  
Cystic Echinococcosis ◽  
Thermal Ablation ◽  
Ex Vivo ◽  
Radiofrequency Thermal Ablation

Performance Comparison of Different Electrodes for Radiofrequency Thermal Ablation on Ex-Vivo Bovine and Porcine Livers

2016 ◽  
Vol 154 (1) ◽  
pp. 84
Author(s):  
E. Bollo ◽  
P. Pregel ◽  
F. Riganti ◽  
N. Bonelli ◽  
E. Manuali ◽  
...  
Keyword(s):  
Thermal Ablation ◽  
Ex Vivo ◽  
Performance Comparison ◽  
Radiofrequency Thermal Ablation

scholarly journals Fiber Optic Sensor for Real-time Monitoring of Freezing–Thawing Cycle in Cryosurgery

2020 ◽  
Vol 10 (3) ◽  
pp. 1053
Author(s):  
Dimosthenis Spasopoulos ◽  
George Rattas ◽  
Archontis Kaisas ◽  
Thomas Dalagiannis ◽  
Ioannis D. Bassukas ◽  
...  
Keyword(s):  
Real Time ◽  
Optical Transmission ◽  
Fiber Optic ◽  
Expert Knowledge ◽  
Ex Vivo ◽  
Fiber Optic Sensor ◽  
Real Time Monitoring ◽  
Fiber Array ◽  
Optic Sensor ◽  
Optical Fiber Array

Cryosurgery/cryotherapy is a widely used, freezing–thawing technique for the renewal or destruction of pathological tissues by applying localized rapid cooling; however, it still relies on the subjective “expert knowledge” of the physicians without, up to now, real-time monitoring of the treatment. This work focused on assessing the depth of freezing using optical transmission and backscattering measurements from frozen/unfrozen porcine ex-vivo skin samples. An optical fiber-array sensor was subsequently developed to determine the depth of freezing and the associated kill zone during freeze–thawing cycles with sub-millimeter accuracy within the skin tissue.

scholarly journals Optical Signature Analysis of Liver Ablation Stages Exploiting Spatio-Spectral Imaging

2021 ◽  
Vol 7 (2) ◽  
pp. 020306
Author(s):  
Mohamed Aref ◽  
Ramy Abdlaty ◽  
Mohamed Abbass ◽  
Ibrahim Aboughaleb ◽  
Ayman Nassar ◽  
...  
Keyword(s):  
Spatial Data ◽  
Thermal Ablation ◽  
Ex Vivo ◽  
Spectral Band ◽  
Region Of Interest ◽  
Tissue Temperature ◽  
Optical Parameters ◽  
Liver Sample ◽  
Noninvasive Technique ◽  
The Impact

Background and Objective: Thermal ablation modalities such as Radiofrequency ablation (RFA) / Microwave ablation (MWA) are deliberately used for marginally invasive tumor removal by escalating tissue temperature. For precise tumor extinguish, thermal ablation outcomes need routine monitoring for tissue necrosis in a challenging research task. The study aims to exploit hyperspectral imaging (HSI) to evaluate the impact of the liver tissue ablation. Materials and Methods: RFA with temperature range (≥80 °C) was accomplished on the ex vivo animal liver and evaluated using a spectral camera (400~1000 nm). The spectral signatures were extracted from the HSI data after the following processing steps: capturing three spectral data cubes for each liver sample with total 7-samples (before ablation, after ablation, and after ablation with sample slicing) using an HSI optical configuration. The custom HSI processing comprises “Top-hat and Bottom-hat transform” combined with “watershed transform” image segmentation to increase the intensity for a region of interest (ROI) of the investigated tissue, linking spectral and spatial data. Additionally, statistical analysis for HSI data was performed to exclusively select the best spectral band that discriminates between the normal, thermally-damaged, and ablated liver regions. Results: The variation of the optical parameters for the investigated liver samples provides variable interaction with the light diffuse reflection (Ŗd) over the spectrum range (400~1000 nm). Where, the extracting spectral information of the various tissue zones from the induced RFA linked to the hemoglobin, methemoglobin, and water permits variations. The generated spectral image after image enhancement utilizing “Top-hat and Bottom-hat transform” followed by “watershed segmentation”, showed high contrast between normal and thermal regions at a wavelength (600 nm). However, the wavelength (900 nm) shows a high variance between the normal and ablated regions. Finally, delineation of the thermal and ablated regions on the complemented enhanced image. Conclusion: HSI is considered a promising optical noninvasive technique for monitoring the RFA toward enhancing the ablation-based treatment for liver tumor outcomes.

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