Ablation of Subsurface Tumors Using 1552 nm Ultra-Short Pulse Laser

Author(s):  
Shreya Raje ◽  
Amir Sajjadi ◽  
Kunal Mitra ◽  
Michael S. Grace

Over last two decades lasers have been used for the treatment of subsurface tumors. Various techniques such as Laser-induced Hyperthermia, Laser Interstitial Thermal Therapy (LITT), and Laser Immunotherapy have been developed for the successful ablation of subsurface tumors by different researchers. All these techniques use photo-thermal mechanism for tumor ablation by delivering thermal energy at the tumor site. In all these existing techniques, either continuous wave (CW) or long pulse laser source has been used, which often produces larger heat affected zone as compared to that produced by short pulse laser. Moreover, the delivery of laser beam at the target site is achieved through fiber optic probes which often require perforation of the skin. These drawbacks can be eliminated if a converging laser beam from a short pulse laser source is directly focused at the subsurface location to ablate the tumor.

Author(s):  
Amir Sajjadi ◽  
Ogugua Onyejekwe ◽  
Kunal Mitra ◽  
Michael S. Grace

For the past few years various photothermal methods such as Laser-induced Hyperthermia [1] and Laser Interstitial Thermal Therapy [2] has been developed for tumor ablation. In all of these existing techniques, either continuous wave (CW) or long pulse laser sources have been used, which often produces heat affected zones that are larger than the boundaries of the tumor, which leads to collateral damage of surrounding healthy tissue. Moreover for these applications, either collimated or diffused laser beams are used, resulting in much of the energy being absorbed by tissues at the skin surface and very little remaining energy penetrating the skin. Such drawbacks can be eliminated if a beam from a short pulse laser source is focused directly at the targeted subsurface location. Tight focusing ensures that sufficient intensity to drive nonlinear optical absorption can be achieved with low pulse energy. This technique has been effectively used in applications such as non-ablative dermal remodeling [3] and treatment of striated muscles [4]. However, the use of focused beam from an ultra-short pulse laser source has never been applied to tumor ablation and is investigated in this paper.


Author(s):  
Amir Yousef Sajjadi ◽  
Gopalendu Pal ◽  
Kunal Mitra ◽  
Michael Grace

The objective of the work is to perform both experimental and numerical analysis of short pulse laser interaction with tissue medium with the goal of tumor / cancer diagnostics. Short pulse laser probing techniques for diagnostics have distinct advantages over very large pulse width or continuous wave lasers primarily due to the additional information conveyed by the temporal distribution of the optical signals. For short pulse laser source, the shape of output signal is a function of the optical properties of the medium and hence the scattered optical signal provides information about the medium characteristics. Two laser systems are used: a mode-locked short pulse laser (wavelength = 514 nm and pulsewidth = 200 ps) and a frequency doubled diode short pulse laser (wavelength = 776 nm and pulsewidth = 1.3 ps). The scattered optical signals are measured with a Hamamatsu streak camera. First in vitro experiments are performed on mouse skin tissue samples injected with India ink in order to simulate presence of inhomogeneities. Finally, in vivo imaging is performed on anaesthetized rats with tumorogenic agents injected inside skin tissues and on anaesthetized mouse with mammary tumors. Both the temporal and the spatial profiles of the scattered reflected optical signals are compared with the numerical modeling results obtained by solving the transient radiative transport equation using the discrete ordinates technique. The goal is to demonstrate the feasibility of the time-resolved technique in detecting tumors in animal model.


Author(s):  
F. Beaudoin ◽  
P. Perdu ◽  
C. DeNardi ◽  
R. Desplats ◽  
J. Lopez ◽  
...  

Abstract Ultra-short pulse laser ablation is applied to IC backside sample preparation. It is contact-less, non-thermal, precise and can ablate the various types of material present in IC packages. This study concerns the optimization of ultra-short pulse laser ablation for silicon thinning. Uncontrolled silicon roughness and poor uniformity of the laser thinned cavity needed to be tackled. Special care is taken to minimize the silicon RMS roughness to less than 1µm. Application to sample preparation of 256Mbit devices is presented.


1994 ◽  
Author(s):  
Ronnie Shepherd ◽  
Rex Booth ◽  
Dwight Price ◽  
Rosemary Walling ◽  
Richard More ◽  
...  

2005 ◽  
Author(s):  
Andreas Hertwig ◽  
Sven Martin ◽  
Wolfgang Kautek ◽  
Jörg Krüger

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