Monitoring Focal Laser Ablation with Interstitial Fluence Probes: Monte Carlo Simulation and Phantom Validation

Author(s):  
Rory Geoghegan ◽  
Alan Priester ◽  
Le Zhang ◽  
Holden Wu ◽  
Leonard Marks ◽  
...  
2020 ◽  
Vol 138 (6) ◽  
pp. 819-823
Author(s):  
Shuang Liu ◽  
Zongjun Tian ◽  
Xuesong Gao ◽  
Deqiao Xie

Phlebologie ◽  
2013 ◽  
Vol 42 (03) ◽  
pp. 131-138 ◽  
Author(s):  
M. Hemmerich ◽  
T. Pongratz ◽  
K. Siegrist ◽  
J. Brons ◽  
S. Linden ◽  
...  

SummaryIntroduction: Endovenous laser ablation is becoming a common procedure in clinical routine. Although technical improvements and certain laser parameters are available there is demand to improve the situation by developing feedback-systems, thus getting online information for the clinical outcome and preventing for under- and over-treatment.Methods: By means of Monte Carlo simulation the potential of detecting signals due to heat induced shrinkage of the vessel was investigated. Remission spectra of native and coagulated vein tissue were compared to identify potential parameters for signalling the physiological change of the tissue due to the heating process. A miniaturized temperature sensor was developed for intraluminal measurements during laser energy application.Results: Monte Carlo simulation shows that the detection of remitted light from the vessels wall is possible for small vessel calibres of less than 6 mm in diameter. Remission spectra of native compared to coagulated vein tissue differ. While native tissue relates more to the content of deoxy-hemoglobin, the spectra of coagulated tissue relates more to the oxy-hemoglobin state. Based on the principle of temperature dependent fluorescence emission a miniaturized sensor was developed which can be used in the light field of radial emitting fibres.Conclusion: Several optical changes for online-monitoring of signals during endovenous laser ablation showed potential to serve as feedback mechanism. Up to now, only the measurement of the endoluminal temperature could be realized. Further investigations are needed to find suitable technical realization to prevent for under- or overheating during endovenous laser ablation.


Optik ◽  
2021 ◽  
Vol 227 ◽  
pp. 165569
Author(s):  
Shuang Liu ◽  
Zongjun Tian ◽  
Lida Shen ◽  
Mingbo Qiu ◽  
Xuesong Gao

Author(s):  
Ryuichi Shimizu ◽  
Ze-Jun Ding

Monte Carlo simulation has been becoming most powerful tool to describe the electron scattering in solids, leading to more comprehensive understanding of the complicated mechanism of generation of various types of signals for microbeam analysis.The present paper proposes a practical model for the Monte Carlo simulation of scattering processes of a penetrating electron and the generation of the slow secondaries in solids. The model is based on the combined use of Gryzinski’s inner-shell electron excitation function and the dielectric function for taking into account the valence electron contribution in inelastic scattering processes, while the cross-sections derived by partial wave expansion method are used for describing elastic scattering processes. An improvement of the use of this elastic scattering cross-section can be seen in the success to describe the anisotropy of angular distribution of elastically backscattered electrons from Au in low energy region, shown in Fig.l. Fig.l(a) shows the elastic cross-sections of 600 eV electron for single Au-atom, clearly indicating that the angular distribution is no more smooth as expected from Rutherford scattering formula, but has the socalled lobes appearing at the large scattering angle.


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