US2017189117A1PendingUtilityA1
Flash vaporization surgical systems
Est. expiryApr 22, 2030(~3.8 yrs left)· nominal 20-yr term from priority
A61B 2018/00577A61B 2018/2222A61B 2017/00199A61B 2018/00982A61B 2018/00714A61B 2018/00607A61B 34/25A61B 2017/00172A61B 2018/2244A61B 2018/00696A61B 2018/00601A61B 18/22
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Claims
Abstract
A laser can produce pulses of light energy to eject a volume of the tissue, and the energy can be delivered to a treatment site through a waveguide, such as a fiber optic waveguide. The incident laser energy can be absorbed within a volume of the target tissue with a tissue penetration depth and pulse direction such that the propagation of the energy from the tissue volume is inhibited and such that the target tissue within the volume reaches the spinodal threshold of decomposition and ejects the volume, for example without substantial damage to tissue adjacent the ejected volume.
Claims
exact text as granted — not AI-modified1 . A method for tissue removal, comprising:
directing laser pulses, the laser pulses having a wavelength with an associated optical penetration depth D in the target tissue, an energy per pulse, a fluence φ, a spot area and a pulse duration t p toward an interaction volume of a target tissue around a nerve; and using the laser pulses to generate pressure within the interaction volume of the target tissue which causes ejection of the target tissue within the interaction volume and heating the interaction volume above a spinodal decomposition threshold at the optical penetration depth using the laser pulses, without collateral damage to the nerve.
2 . The method of claim 1 , wherein the wavelength is between 1400 and 1520 nm or between 1860 and 2500 nm.
3 . The method of claim 1 , wherein the interaction volume is a function of the optical penetration depth D and the spot area of the laser pulses incident on the target tissue, where the spot area has a minimum width W, and wherein the optical penetration depth D is a function of an absorption coefficient μ a of the target tissue that is determined by tissue properties and the wavelength, and wherein the optical penetration depth and minimum spot width satisfy a condition that D is within a range of ⅙ W to 2 W, the pulse duration t p meets stress confinement conditions for the interaction volume including:
t p <1/μ a ν s and
t p <W/2ν s , where ν s speed of sound in the target tissue, and further that the pulse duration t p is less than 200 nsec;
wherein the energy per pulse of the laser pulses in the heating of the interaction volume heats water within the interaction volume to induce a phase transition by spinodal decomposition within the interaction volume creating said pressure, and the fluence φ, satisfies
φ
=
t
L
1
-
e
t
L
P
Γμ
a
where:
P=pressure to eject the target tissue
t L =t ρ μ a ν s
Γ=dimensionless strength parameter of the target tissue.
4 . The method of claim 1 , wherein the energy per pulse between 0.5 milliJoules and 40 milliJoules.
5 . The method of claim 1 , including delivering the laser pulses to the target tissue using a silica optical fiber, with energy and pulse duration combinations that are below a damage threshold for the silica optical fiber.
6 . The method of claim 1 , wherein the tissue within the interaction volume is ejected without stress propagation of mechanical energy into tissue adjacent to the interaction volume and without thermal diffusion of thermal energy into the tissue adjacent to the interaction volume.
7 . The method of claim 1 , including delivering the laser pulses through an optical fiber.
8 . The method of claim 1 , wherein the target tissue comprises connective tissue.
9 . The method of claim 1 , wherein the target tissue comprises diseased tissue.
10 . The method of claim 1 , wherein the tissue removal rate comprises at least 10 −7 cm 3 /pulse.
11 . A method for tissue removal, comprising:
directing laser pulses, the laser pulses having a wavelength with an associated optical penetration depth D in the target tissue, and pulse parameters including an energy per pulse, a fluence φ, a spot area and a pulse duration t p toward an interaction volume of a target tissue having mechanical properties different than adjacent tissue; using the laser pulses to generate pressure within the interaction volume of the target tissue which causes ejection of the target tissue within the interaction volume and heating the interaction volume above a spinodal decomposition threshold at the optical penetration depth using the laser pulses; and before said using the laser pulses, adjusting the pulse parameters for the target tissue to so that the pressure generated in the target tissue exceeds a threshold pressure for ejection of the target tissue, where the threshold pressure is different for different types of target tissues.
12 . The method of claim 1 , wherein the wavelength is between 1400 and 1520 nm or between 1860 and 2500 nm.
13 . The method of claim 1 , wherein the interaction volume is a function of the optical penetration depth D and the spot area of the laser pulses incident on the target tissue, where the spot area has a minimum width W, and wherein the optical penetration depth D is a function of an absorption coefficient μ a of the target tissue that is determined by tissue properties and the wavelength, and wherein the optical penetration depth and minimum spot width satisfy a condition that D is within a range of ⅙ W to 2 W, the pulse duration t p meets stress confinement conditions for the interaction volume including:
t p <1/μ a ν s and
t p <W/2ν s , where ν s speed of sound in the target tissue, and further that the pulse duration t p is less than 200 nsec;
wherein the energy per pulse of the laser pulses in the heating of the interaction volume heats water within the interaction volume to induce a phase transition by spinodal decomposition within the interaction volume creating said pressure, and the fluence φ, satisfies
φ
=
t
L
1
-
e
t
L
P
Γμ
a
where:
P=pressure to eject the target tissue
t L =t ρ μ a ν s
Γ=dimensionless strength parameter of the target tissue.
14 . The method of claim 11 , wherein the energy per pulse between 0.5 milliJoules and 40 milliJoules.
15 . The method of claim 11 , including delivering the laser pulses to the target tissue using a silica optical fiber, with energy and pulse duration combinations that are below a damage threshold for the silica optical fiber.
16 . The method of claim 11 , wherein the tissue within the interaction volume is ejected without stress propagation of mechanical energy into tissue adjacent to the interaction volume and without thermal diffusion of thermal energy into the tissue adjacent to the interaction volume.
17 . The method of claim 11 , including delivering the laser pulses through an optical fiber.
18 . The method of claim 11 , wherein the target tissue comprises connective tissue.
19 . The method of claim 11 , wherein the target tissue comprises diseased tissue.
20 . The method of claim 11 , wherein the tissue removal rate comprises at least 10 −7 cm 3 /pulse.Cited by (0)
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