Considerations for Thermal Injury Analysis for RF Ablation Devices~!2009-09-09~!2009-12-19~!2010-02-04~!

Chang, Isaac

doi:10.2174/1874120701004020003

Cited by 29 publications

(20 citation statements)

References 42 publications

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“…In the past study, it was suggested that if damage function exceeds the value of 0.53, then first-degree burns are imminent [43]. Further, the necrosed tissues lead to the transient cessation of localized blood flow [44]. Therefore, the proposed CEM43°C-based Arrhenius model could be used to predict the thermal injury during bone grinding.…”

Section: Tissue Damagementioning

confidence: 99%

Thermogenesis mitigation using ultrasonic actuation during bone grinding: a hybrid approach using CEM43°C and Arrhenius model

Babbar

Jain

Gupta

2019

J Braz. Soc. Mech. Sci. Eng.

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Bone grinding has cemented its applications in the various sorts of the neurosurgeries. Generally, a rotating burr is used to remove a part of the bone to expose the tumors present underneath the bone. The abrasion caused by the grinding wheel causes a rise in temperature owing to the generation of the heat during grinding and would have severe consequences with the initiation of thermogenesis. To bridge this gap, an in-house experimental setup was developed to perform multi-pass rotary ultrasonic neurosurgical bone grinding. Three functional characteristics, namely rotational speed, feed rate, and amplitude, have been investigated using Taguchi L18 orthogonal array design. The regression equations have been obtained and validated with confirmation experiments using a random set of machining parameters. Further, machining parameters are optimized using genetic algorithm and confirmatory trials are performed using optimized conditions. The results of statistical analysis (ANOVA) revealed that the feed rate is the most significant parameter influencing the change in temperature during osteotomy. Nevertheless, the standard deviation was most affected by rotational speed. Furthermore, a comparative analysis has been carried out for conventional and rotary ultrasonic neurosurgical grinding. A hybrid approach using cumulative equivalent minutes (CEM43°C) and Arrhenius model has been used to predict the thermal damage caused to the human body's tissues during bone grinding. The results obtained have been experimentally validated, and outcomes revealed that ultrasonically actuated grinding burr may prevent osteonecrosis and neural damage duly supported with infrared thermograms and graphical plots. Keywords Bone grinding • Ultrasonic • Genetic algorithm • Infrared thermography • CEM43°C • Arrhenius equations List of symbols Ω Tissue damage function A Pre-exponential factor (s −1) E a Arrhenius activation energy (J/mol) τ Time (s) R Universal gas constant (J/mol k) K Rate constant T Actual exposure temperature (°C) T break Breaking point temperature CEM43°C Cumulative number of equivalent minutes at 43 °C F Feed rate (mm/min) A Amplitude (µm) D Depth of cut (mm) ∆T Change in temperature (°C) σ Standard deviation CG Conventional grinding RUNG Rotary ultrasonic neurosurgical grinding

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Section: Tissue Damagementioning

confidence: 99%

Thermogenesis mitigation using ultrasonic actuation during bone grinding: a hybrid approach using CEM43°C and Arrhenius model

Babbar

Jain

Gupta

2019

J Braz. Soc. Mech. Sci. Eng.

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“…where ρ b is density of blood, c b specific heat of blood, T b blood temperature (37°C), ω b blood perfusion coefficient (ω b = 0.0155 s -1 ), 8 and β is a coefficient which took the values of 0 and 1, according to the value of the thermal damage: β = 0 for Ω ≥ 4.6 and β = 1 for Ω < 4.6. The parameter Ω is assessed by the Arrhenius damage model, 9 which associates temperature with exposure time using a first-order kinetics relationship:…”

Section: Governing Equations and Model Characteristicsmentioning

confidence: 99%

“…where R is the universal gas constant, A (7.39 × 10 39 s −1 ) is a frequency factor and ΔE (2.577 × 10 5 J/mol) is the activation energy for the irreversible damage reaction. 9,10 We assessed the thermal damage by the D99 isoline, 11 which corresponds to Ω = 4.6 (99% probability of cell death). The location of the D99 isoline defined the size of the coagulation zone.…”

Section: Governing Equations and Model Characteristicsmentioning

confidence: 99%

How coagulation zone size is underestimated in computer modeling of RF ablation by ignoring the cooling phase just after RF power is switched off

Irastorza

Trujillo

Berjano

2017

Numer Methods Biomed Eng

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All the numerical models developed for radiofrequency ablation so far have ignored the possible effect of the cooling phase (just after radiofrequency power is switched off) on the dimensions of the coagulation zone. Our objective was thus to quantify the differences in the minor radius of the coagulation zone computed by including and ignoring the cooling phase. We built models of RF tumor ablation with 2 needle-like electrodes: a dry electrode (5 mm long and 17G in diameter) with a constant temperature protocol (70°C) and a cooled electrode (30 mm long and 17G in diameter) with a protocol of impedance control. We observed that the computed coagulation zone dimensions were always underestimated when the cooling phase was ignored. The mean values of the differences computed along the electrode axis were always lower than 0.15 mm for the dry electrode and 1.5 mm for the cooled electrode, which implied a value lower than 5% of the minor radius of the coagulation zone (which was 3 mm for the dry electrode and 30 mm for the cooled electrode). The underestimation was found to be dependent on the tissue characteristics: being more marked for higher values of specific heat and blood perfusion and less marked for higher values of thermal conductivity.

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“…Mathematical modeling has been an efficient and low cost modality in both design and treatment planning [ 22 ]. Models have been developed to simulate the temperature distributions of tissue during the treatment [ 4 , 23 - 26 ]. The complexity of the tumor composition, the influence of heterogeneous electrical conductivity, thermal conductivity, blood perfusion rate, and the specific distribution of blood vessels on the results have been studied [ 27 - 35 ].…”

Section: Introductionmentioning

confidence: 99%

“…The RF frequency used is 460 kHz. As the wavelength of the electromagnetic field is much longer than the electrode, the quasi-static approximation of the electrical field in the tissue is applied [ 26 , 42 ],…”

Section: Introductionmentioning

confidence: 99%

Numerical study of the influence of water evaporation on radiofrequency ablation

et al. 2013

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BackgroundRadiofrequency ablation is a promising minimal invasive treatment for tumor. However, water loss due to evaporation has been a major issue blocking further RF energy transmission and correspondently eliminating the therapeutic outcome of the treatment.MethodA 2D symmetric cylindrical mathematical model coupling the transport of the electrical current, heat, and the evaporation process in the tissue, has been developed to simulate the treatment process and investigate the influence of the excessive evaporation of the water on the treatment.ResultsOur results show that the largest specific absorption rate (Q SAR ) occurs at the edge of the circular surface of the electrode. When excessive evaporation takes place, the water dehydration rate in this region is the highest, and after a certain time, the dehydrated tissue blocks the electrical energy transmission in the radial direction. It is found that there is an interval as long as 65 s between the beginning of the evaporation and the increase of the tissue impedance. The model is further used to investigate whether purposely terminating the treatment for a while allowing diffusion of the liquid water into the evaporated region would help. Results show it has no obvious improvement enlarging the treatment volume. Treatment with the cooled-tip electrode is also studied. It is found that the cooling conditions of the inside agent greatly affect the water loss pattern. When the convection coefficient of the cooling agent increases, excessive evaporation will start from near the central axis of the tissue cylinder instead of the edge of the electrode, and the coagulation volume obviously enlarges before a sudden increase of the impedance. It is also found that a higher convection coefficient will extend the treatment time. Though the sudden increase of the tissue impedance could be delayed by a larger convection coefficient; the rate of the impedance increase is also more dramatic compared to the case with smaller convection coefficient.ConclusionThe mathematical model simulates the water evaporation and diffusion during radiofrequency ablation and may be used for better clinical design of radiofrequency equipment and treatment protocol planning.

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Considerations for Thermal Injury Analysis for RF Ablation Devices~!2009-09-09~!2009-12-19~!2010-02-04~!

Cited by 29 publications

References 42 publications

Thermogenesis mitigation using ultrasonic actuation during bone grinding: a hybrid approach using CEM43°C and Arrhenius model

Thermogenesis mitigation using ultrasonic actuation during bone grinding: a hybrid approach using CEM43°C and Arrhenius model

How coagulation zone size is underestimated in computer modeling of RF ablation by ignoring the cooling phase just after RF power is switched off

Numerical study of the influence of water evaporation on radiofrequency ablation

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