Surgical apparatus for laser ablation of soft tissue

Abstract

A method for photoselective vaporization of prostate tissue includes delivering laser radiation to the treatment area on the tissue, via an optical fiber for example, wherein the laser radiation has a wavelength and irradiance in the treatment area on the surface of the tissue sufficient because vaporization of a substantially greater volume of tissue than a volume of residual coagulated tissue caused by the laser radiation. The laser radiation is generated using a neodymium doped solid-state laser, including optics producing a second or higher harmonic output with greater than 60 watts average output power. The delivered laser radiation has a wavelength for example in a range of about 200 nm to about 650 nm, and has an average irradiance in the treatment area greater than about 10 kilowatts/cm 2 , in a spot size of at least 0.05 mm 2 .

1 . A surgical apparatus for laser ablation of soft tissue, comprising 
 a diode-pumped laser operated at highly multiple modes and producing an output laser beam of 40 W or higher, said diode-pumped laser includes: 
 a resonant cavity formed by three or more reflective optics;  
 a solid-state gain medium deposited in said resonant cavity and having a cross-section dimension of 2 mm or bigger;  
 diode laser radiation delivered from multiple bars of diode lasers and pumping said solid-state gain medium from two or more directions;  
 a Q-switch deposited in said resonant cavity and being operable at a repetition rate within 1 kHz to 100 kHz;  
 a frequency-doubling crystal deposited in said resonant cavity and located around a beam waist of said resonant cavity; and  
 a mode control mechanism implemented in said resonant cavity and ensuring highly multiple modes to operate, wherein a beam spot size at said solid-state gain medium is at least five times as big as a minimum beam spot size associated with TEM00 mode operation;  
   a beam delivery optics positioned at a beam path of said output laser beam and delivering said output laser beam onto said soft tissue; and    a beam divergence controller implemented with said beam delivery optics to obtain a feasibly small beam divergence angle of said output laser beam on said soft tissue;    wherein said diode-pumped laser of said highly multiple modes provides effective laser ablation on said soft tissue.    
   
   
       2 . A surgical apparatus for laser ablation of soft tissue, comprising 
 a diode-pumped laser operated at highly multiple modes and producing an output laser beam of 40 W or higher, said diode-pumped laser includes: 
 a resonant cavity formed by three or more reflective optics;  
 a solid-state gain medium deposited in said resonant cavity and having a cross-section dimension of 2 mm or bigger;  
 diode laser radiation delivered from multiple bars of diode lasers and pumping said solid-state gain medium from two or more directions;  
 a Q-switch deposited in said resonant cavity and being operable at a repetition rate within 1 kHz to 100 kHz;  
 a frequency-doubling crystal deposited in said resonant cavity and located around a beam waist of said resonant cavity; and  
 a mode control mechanism implemented in said resonant cavity and ensuring highly multiple modes to operate, wherein a beam spot size at said solid-state gain medium is at least five times as big as a minimum beam spot size associated with TEM00 mode operation;  
   a beam delivery optics positioned at a beam path of said output laser beam and delivering said output laser beam onto said soft tissue; and    means to optimize power of said output laser power conversion efficiency of 3% or higher from wall-plug electricity;    wherein power consumption of said diode-pumped laser is sufficiently low to enable use of standard electrical wall-plug outlet.    
   
   
       3 . A surgical apparatus for laser ablation of soft tissue, comprising 
 a diode-pumped laser operated at highly multiple modes and producing an output laser beam of 40 W or higher, wherein said diode-pumped laser includes a frequency-doubling crystal to generate second harmonics;    a beam delivery optics positioned at a beam path of said output laser beam and delivering said output laser beam onto said soft tissue; and    a temperature-tuning mechanism applied to said frequency-doubling crystal to optimize phase-matching angle through temperature tuning;    wherein said frequency-doubling crystal is prevented from temperature shock due to otherwise mechanical tuning of phase-matching angle.    
   
   
       4 . A surgical apparatus of  claim 1 , further comprising 
 a first-pulse compressor coupled electronically to said diode-pumped laser and eliminating giant first-pulse from any train of said Q-switched pulses;    wherein said diode-pumped laser is prevented from power damage.    
   
   
       5 . A surgical apparatus of  claim 1  wherein said soft tissue includes prostatic tissue.  
   
   
       6 . A surgical apparatus of  claim 1  wherein said diode-pumped laser operates at a CW Q-switching mode.  
   
   
       7 . A surgical apparatus of  claim 1  wherein said highly multiple modes has 10 or more modes.  
   
   
       8 . A surgical apparatus of  claim 1  wherein said diode-pumped laser delivers 30 W to 150 W laser power on said soft tissue.  
   
   
       9 . A surgical apparatus of  claim 1  wherein said solid-state gain medium includes Nd:YAG, Nd:YLF, or Nd:YVO 4 .  
   
   
       10 . A surgical apparatus of  claim 1  wherein said diode laser radiation is generated with CW current.  
   
   
       11 . A surgical apparatus of  claim 1  wherein said frequency-doubling crystal includes LBO or KTP.  
   
   
       12 . A surgical apparatus of  claim 1  wherein said output laser beam has a beam quality with value M 2  greater than 100.  
   
   
       13 . A surgical apparatus of  claim 1  wherein said mode control mechanism consists of focal optics with predetermined focal length to ensure operation of said highly multiple modes.  
   
   
       14 . A surgical apparatus of  claim 1  wherein said diode-pumped laser delivers laser output from one or more laser heads.  
   
   
       15 . A surgical apparatus of  claim 1  wherein said feasibly small beam divergence angle has a numerical aperture of 0.2 or smaller.  
   
   
       16 . A surgical apparatus of  claim 1 , further comprising a beam-size control element implemented with said beam delivery optics and controlling beam size of said output laser beam on said soft tissue to obtain an improved ablation speed.  
   
   
       17 . A surgical apparatus of  claim 2  wherein said means to optimize power is a Q-switch controller that optimizes said power of said output laser beam via repetition rate and peak power of Q-switched pulses.  
   
   
       18 . A surgical apparatus of  claim 2  wherein said means to optimize power is a frequency-doubling crystal that optimizes said power of said output laser beam via crystal length.  
   
   
       19 . A surgical apparatus of  claim 2  wherein said power consumption of said diode-pumped laser is 3 kilowatt or lower.  
   
   
       20 . A surgical apparatus of  claim 2  wherein said power consumption of said diode-pumped laser is sufficiently low to enable elimination of external water-cooling or secondary cooling loop.  
   
   
       21 . A surgical apparatus of  claim 2  has advantages of enabling use of standard wall-plug outlet; and elimination of external water-cooling or secondary cooling loop; 
 wherein said diode-pumped laser encourages more hospitals and surgeon offices to use more fiber-optic delivery devices.