A pancreatic tumor ablation system that generates high-power mid-infrared femtosecond pulsed laser.

Abstract

This invention discloses a pancreatic tumor ablation system for generating high-power mid-infrared femtosecond laser pulses, comprising: a high-power pump source, a signal pulse light generation module, a near-infrared optical parametric amplification module, a mid-infrared optical parametric amplification module, and a pancreatic tumor ablation module. This invention is the first to combine an optical parametric amplification system with a tumor ablation system, realizing a technical solution for ablating pancreatic tumors using mid-infrared femtosecond lasers. By constructing a 115W high-power pump source to pump a two-stage optical parametric amplification process and adjusting the phase matching angle of the LGS and its corresponding time delay, high-average-power mid-infrared pulses near a 6µm wavelength can be generated. The ablation efficiency is high and the lateral lesion size is small. Mid-infrared pulse light generation based on optical parametric conversion is easy to integrate and miniaturize, resulting in low maintenance and operating costs.

Description

Technical Field

[0001] This invention relates to the field of solid-state ultrafast laser technology, specifically to a pancreatic tumor ablation system that generates high-power mid-infrared femtosecond pulsed laser. Background Technology

[0002] Thermal ablation, as a minimally invasive treatment, is now widely used in local interventional therapy for tumors. Laser ablation (LA), as a method of thermal ablation, offers unique advantages over radiofrequency ablation (RFA) and microwave ablation (MWA), including precise target ablation and good hemostasis, and has seen widespread success in various tumor ablation treatments in recent years. Femtosecond laser tumor ablation, due to its non-contact nature, high ablation efficiency, and safety, coupled with automated control and imaging monitoring technologies, allows for precise manipulation and has played an important role in surgeries for tumors such as those in the liver, lung, and thyroid. However, its application in the mid-infrared band is not yet widespread. In fact, the resonance frequencies of pancreatic tumors (proteins and phosphates) and water molecules are mostly located in the mid-infrared band (pancreatic tumor tissue has a strong absorption peak around 6 μm). Simultaneously, the ultrashort pulses generated by femtosecond lasers interact with the material for an extremely short time, without causing thermal effects on the surrounding material. Therefore, utilizing the resonance between mid-infrared femtosecond lasers and pancreatic tumor molecules can achieve lateral damage on the order of micrometers and ablation depths on the order of millimeters. Mid-infrared femtosecond laser tumor ablation plays an irreplaceable role in the treatment of tumors in high-risk or special locations due to its unique advantages such as precision and minimal damage. It is also currently recognized as the ablation procedure with the fewest complications among solid tumor ablation techniques. Generating mid-infrared femtosecond lasers is difficult, which greatly limits its research in tumor ablation. Due to the limitations of the transition energy levels in the gain medium, the output wavelength of common lasers is fixed and mostly limited to the near-infrared and visible light range (0.3-2 μm), far from the resonance peak of tumor tissue, resulting in cutting depths on the order of 10 μm. The method of obtaining mid-infrared femtosecond lasers (3-9 μm) through nonlinear parametric conversion in LiGaS2 crystals, which have a large energy bandgap, wide transmission range, and weak two-photon absorption, has many advantages, including high conversion efficiency, flexible phase matching, and large gain bandwidth. It can generate mid-infrared femtosecond lasers with high average power and continuously tunable bandwidth. Pumping with 1030 nm can further enhance the output energy and average power of the mid-infrared pulsed light converted from near-infrared parametric conversion. In summary, with the rapid development of localization and efficacy assessment technologies, mid-infrared femtosecond lasers based on resonant absorption will play an important role in the treatment of various solid tumors, benefiting more cancer patients. The most significant problem with existing technologies is the lack of desktop-scale mid-infrared femtosecond pulse generation devices for broader research. Free-electron lasers can also generate mid-infrared femtosecond laser sources, but their devices are on a kilometer scale and have high operating and maintenance costs. Currently, there is no miniaturized and economical mid-infrared system based on optical parametric amplification for tumor ablation.

[0003] Doping refers to the introduction of foreign ions into a crystal. When dopant ions are introduced into a crystal, they alter the crystal lattice structure and interatomic interactions, thereby causing changes in the crystal's electronic energy levels. For generating mid-infrared radiation, commonly used solid-state activating ions include rare-earth ions (Tm ions). 3+ Ho 3+ Er 3+ (etc.) and transition metal ions (Fe 2+ Cr 2+ (etc.). When external light shines on such a doped ion crystal, the doped ions absorb the light energy and transition to an excited state, and after a period of time, de-excite back to the ground state through a non-radiative transition. During this process, the doped ions release radiant energy in the mid-infrared band. By appropriately selecting doped ions and crystal materials and optimizing the crystal structure, mid-infrared radiation in different wavelength ranges can be generated. However, the output wavelength of lasers that directly emit mid-infrared light from common doped ions is fixed and mostly limited to the near-infrared and visible light (0.3-2μm) ranges, and the temperature effect is relatively severe, resulting in large heat generation and relatively low conversion efficiency.

[0004] Traditional semiconductor lasers generate laser light through the recombination of electrons and holes, producing emitted photons. The advent of quantum cascade technology has further improved quantum efficiency and output power, while simultaneously extending the wavelength range of the output laser. Semiconductor materials possess unique band structures, including a valence band and a conduction band. Mid-infrared lasers typically utilize III-V compound semiconductor materials, such as GaN and InP. Current is injected into the semiconductor material via a battery or other external device, causing electrons to transition from the valence band to the conduction band, forming free charge carriers. Within the semiconductor layer, free charge carriers (electrons and holes) recombine through collisions and scattering. When one free charge carrier encounters another corresponding free charge carrier, they undergo nonradiative recombination, releasing heat, or the carrier may return from an electronic state to the valence band. When free charge carriers recombine in the semiconductor, they may transition to lower energy levels and release photons. These photons, after multiple reflections and amplifications, enhance the light in the laser cavity, ultimately generating laser light. Although these devices are highly efficient and have a wide output wavelength range, they have relatively low output power, limited wavelength tunability, and require operation in low-temperature environments.

[0005] Surgical Trauma: Radiofrequency ablation requires the placement of radiofrequency electrodes within the patient's body for treatment, which can result in puncture trauma. While this trauma is usually minor, it can still cause complications such as pain, infection, and bleeding. Risk of Tumor Recurrence: Radiofrequency ablation can effectively destroy tumor cells, but it may not completely eliminate all tumor tissue. If residual tumor cells are not completely eradicated, it can lead to tumor recurrence or metastasis. Limitation to Specific Tumor Types and Locations: Radiofrequency ablation is suitable for some smaller, localized tumors, such as liver and lung cancer. For larger tumors or those that are not easily accessible, radiofrequency ablation may be less suitable. Summary of the Invention

[0006] To address the above problems, the present invention provides a pancreatic tumor ablation system that generates high-power mid-infrared femtosecond pulsed laser.

[0007] The present invention adopts the following technical solution:

[0008] A pancreatic tumor ablation system for generating high-power mid-infrared femtosecond pulsed lasers is characterized by comprising a high-power pump source, a signal pulsed light generation module, a near-infrared optical parametric amplification module, a mid-infrared optical parametric amplification module, and a pancreatic tumor ablation module.

[0009] The femtosecond pulse light generated by the high-power pump source is split into a first beam and a second beam after passing through a first half-wave plate and a first thin-film polarizer.

[0010] The signal pulse light generation module performs spectral broadening on the first beam of light to obtain signal pulse light, and transmits it to the near-infrared optical parametric amplification module;

[0011] The near-infrared optical parametric amplification module amplifies the signal pulse light after combining the signal pulse light and the second beam light, separates the second beam light to obtain the near-infrared pulse light, and transmits the near-infrared pulse light to the mid-infrared optical parametric amplification module.

[0012] The mid-infrared optical parametric amplification module amplifies the near-infrared pulse light after combining the near-infrared pulse light and the second beam, separates the second beam to obtain the mid-infrared pulse light, and transmits the mid-infrared pulse light to the pancreatic tumor ablation module.

[0013] The pancreatic tumor ablation module uses optical fiber to guide mid-infrared pulsed light into the pancreatic tumor tissue for ablation.

[0014] Furthermore, the signal pulse light generation module includes an aperture, a first plano-convex lens, a YAG crystal, a second plano-convex lens, and a first long-pass filter arranged in sequence; the YAG crystal performs spectral broadening to obtain signal pulse light; the second plano-convex lens is used for collimation.

[0015] Furthermore, the near-infrared optical parametric amplification module includes a signal pulse light propagating along a third plano-convex lens and being combined by a first dichroic mirror; a second beam of light propagating along a time delay device and a fourth plano-convex lens and being combined by the first dichroic mirror; it also includes a first LGS crystal and a fifth plano-convex lens arranged sequentially after the first dichroic mirror; the first LGS crystal amplifies the signal pulse light; and the fifth plano-convex lens is used for collimation.

[0016] Furthermore, the mid-infrared optical parametric amplification module includes a near-infrared pulse light propagating along a sixth plano-convex lens and being combined at a third dichroic mirror; a second beam of light propagating along a time delay device and a seventh plano-convex lens and being combined at a third dichroic mirror; and a second LGS crystal and an eighth plano-convex lens arranged sequentially behind the third dichroic mirror; the second LGS crystal amplifies the near-infrared pulse light; and the eighth plano-convex lens is used for collimation.

[0017] Furthermore, the pancreatic tumor ablation module includes a ZnSe plano-convex lens and a mid-infrared optical fiber arranged sequentially.

[0018] Furthermore, the second beam of the femtosecond pulse light generated by the high-power pump source is split sequentially by a second half-wave plate and a second thin-film polarizer. One beam enters the near-infrared optical parametric amplification module, while the other beam is split by a third half-wave plate and a third thin-film polarizer before entering the mid-infrared optical parametric amplification module.

[0019] Furthermore, a second dichroic mirror, a beam collector, and a second long-pass filter are disposed behind the fifth plano-convex lens; the second dichroic mirror is used to separate the second beam of light to obtain near-infrared pulse light; the first beam collector is used to collect the separated second beam of light.

[0020] Furthermore, a fourth dichroic mirror, a second beam collector, a germanium plate, and a metal film reflector are disposed behind the eighth plano-convex lens; the fourth dichroic mirror separates the second beam of light to obtain mid-infrared pulse light, and the germanium plate is used to filter out near-infrared pulse light.

[0021] Furthermore, the high-power pump source has an output power of 115 W, an output pulse width of ~280 fs, and a center wavelength of 1030 nm.

[0022] The beneficial effects of this invention are:

[0023] 1. This invention is the first to combine an optical parametric amplification system with a tumor ablation system, realizing a technical solution for ablation of pancreatic tumors using mid-infrared femtosecond laser.

[0024] 2. This invention generates high average power mid-infrared pulses near the 6 μm wavelength by constructing a 115 W high-power pump source to pump a two-stage optical parametric amplification process and adjusting the phase matching angle of the LGS crystal and its corresponding time delay.

[0025] 3. High ablation efficiency and small lateral lesion size. This invention is based on the characteristic absorption of pancreatic tumor tissue in the mid-infrared spectral region. Ablation of pancreatic tissue shows that the ablation effect in the characteristic absorption region is better than that in the non-characteristic region.

[0026] 4. This invention generates mid-infrared pulse light based on optical parametric conversion, which is easy to integrate and miniaturize, and has low maintenance and usage costs. Attached Figure Description

[0027] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings of the embodiments will be briefly described below. Obviously, the drawings described below only relate to some embodiments of the present invention and are not intended to limit the present invention.

[0028] Figure 1 This is a schematic diagram of the experimental apparatus of the present invention;

[0029] Figure 2 This is the normalized spectrum of the 6.1 μm pulsed light of the present invention;

[0030] Figure 3 This is a schematic diagram of a slice of pancreatic tumor tissue ablated by a 6.1 μm pulsed laser according to the present invention;

[0031] In the picture:

[0032] 1 High-power pump source, 2 First half-wave plate, 3 First thin-film polarizer, 4 Second half-wave plate, 5 Second thin-film polarizer, 6 Third half-wave plate, 7 Third thin-film polarizer, 8 Aperture, 9 First plano-convex lens, 10 YAG crystal, 11 Second plano-convex lens, 12 First long-pass filter, 13 Third plano-convex lens, 14 First dichroic mirror, 15 Fourth plano-convex lens, 16 First high-reflection mirror, 17 Second high-reflection mirror, 18 Third high-reflection mirror, 19 First LGS crystal, 20 Fifth 21 Plano-convex lens, 22 Second dichroic mirror, 23 Beam collector, 24 Second long-pass filter, 25 Sixth plano-convex lens, 26 Third dichroic mirror, 27 Seventh plano-convex lens, 28 Fourth high-reflection mirror, 29 Sixth high-reflection mirror, 30 Second LGS crystal, 31 Eighth plano-convex lens, 32 Fourth dichroic mirror, 33 Second beam collector, 34 Germanium sheet, 35 Metal film mirror, 36 ZnSe plano-convex lens, 37 Mid-infrared optical fiber, 38 Tumor sample. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0034] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0035] like Figure 1 As shown, a pancreatic tumor ablation system for generating high-power mid-infrared femtosecond pulsed lasers includes a high-power pump source 1, a signal pulsed light generation module, a near-infrared optical parametric amplification module, a mid-infrared optical parametric amplification module, and a pancreatic tumor ablation module. The femtosecond pulsed light generated by the high-power pump source 1 is split into a first beam and a second beam after passing through a first half-wave plate 2 and a first thin-film polarizer 3. The high-power pump source has an output power of 115 W, an output pulse width of ~280 fs, and a center wavelength of 1030 nm. The signal pulsed light generation module broadens the spectrum of the first beam to obtain a signal pulsed light, which is then transmitted to the near-infrared optical parametric amplification module. The near-infrared optical parametric amplification module combines the signal pulsed light and the second beam, amplifies the signal pulsed light, separates the second beam to obtain a near-infrared pulsed light, and transmits the near-infrared pulsed light to the mid-infrared optical parametric amplification module. The mid-infrared optical parametric amplification module combines the near-infrared pulsed light and the second beam, amplifies the near-infrared pulsed light, and separates the second beam to obtain a mid-infrared pulsed light. Figure 2 The image shows the spectrum of a mid-infrared pulse, which is then transmitted to a pancreatic tumor ablation module. This module guides the mid-infrared pulse into the pancreatic tumor tissue via an optical fiber for ablation. The module includes a ZnSe plano-convex lens 36 and a mid-infrared optical fiber 37 arranged sequentially. The mid-infrared pulse is guided into the tumor sample 38 via the mid-infrared optical fiber 37 for ablation. Figure 3 A section of tissue cultured for tumor ablation.

[0036] Specifically, the signal pulse light generation module includes an aperture 8, a first plano-convex lens 9, a YAG crystal 10, a second plano-convex lens 11, and a first long-pass filter 12 arranged sequentially; the aperture 8 controls the flux of the first beam of light, the first plano-convex lens 9 is used to focus the pulse light, the YAG crystal 10 performs spectral broadening to obtain the signal pulse light; and the second plano-convex lens 11 is used for collimation.

[0037] Specifically, the near-infrared optical parametric amplification module includes a signal pulse light propagating along a third plano-convex lens 13 and being combined by a first dichroic mirror 14; a second beam of light propagating along a time delay device and a fourth plano-convex lens 15 and being combined by the first dichroic mirror 14; it also includes a first LGS crystal 19 and a fifth plano-convex lens 20 sequentially arranged after the first dichroic mirror 14; a second dichroic mirror 21, a beam collector 22, and a second long-pass filter 23 are arranged after the fifth plano-convex lens 20; the second dichroic mirror 21 is used to separate the second beam of light to obtain near-infrared pulse light; the first beam collector 22 is used to collect the separated second beam of light. The first LGS crystal 19 amplifies the signal pulse light; the fifth plano-convex lens 20 is used for collimation; the time delay device includes a first high-reflection mirror 16, a second high-reflection mirror 17, and a third high-reflection mirror 18 sequentially arranged.

[0038] Specifically, the mid-infrared optical parametric amplification module includes a near-infrared pulse beam propagating along a sixth plano-convex lens 24 and being combined at a third dichroic mirror 25; a second beam propagating along a time delay device and a seventh plano-convex lens 26 and being combined at the third dichroic mirror 25; and a second LGS crystal 30 and an eighth plano-convex lens 31 sequentially arranged after the third dichroic mirror 25; a fourth dichroic mirror 32, a second beam collector 33, a germanium plate 34, and a metal film reflector 35 are arranged after the eighth plano-convex lens 31; the fourth dichroic mirror 32 separates the second beam to obtain mid-infrared pulse beam, and the germanium plate 34 is used to filter out the near-infrared pulse beam. The second LGS crystal 30 amplifies the near-infrared pulse beam; the eighth plano-convex lens 31 is used for collimation; and the time delay device includes a fourth high-reflectivity mirror 27, a fifth high-reflectivity mirror 28, and a sixth high-reflectivity mirror 29 sequentially arranged.

[0039] Specifically, the second beam of the femtosecond pulse light generated by the high-power pump source 1 is split sequentially by the second half-wave plate 4 and the second thin-film polarizer 5. One beam enters the near-infrared optical parametric amplification module, and the other beam enters the mid-infrared optical parametric amplification module after being split by the third half-wave plate 6 and the third thin-film polarizer 7.

[0040] This invention generates high-average-power mid-infrared pulses near a 6µm wavelength by constructing a 115W high-power pump source to pump a two-stage optical parametric amplification process and adjusting the phase-matching angle of the LGS crystal and its corresponding time delay. The adjustment method involves placing the crystal on a biaxial optical adjustment frame and adjusting the angle between the crystal and the beam by rotating a threaded knob. A translation stage is mounted at the bottom of the time delay system, which consists of mirrors; moving the translation stage adjusts the time delay between the two beams.

[0041] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A pancreatic tumor ablation system that generates high-power mid-infrared femtosecond pulsed laser, characterized in that, It includes a high-power pump source (1), a signal pulse light generation module, a near-infrared optical parametric amplification module, a mid-infrared optical parametric amplification module, and a pancreatic tumor ablation module; The femtosecond pulse light generated by the high-power pump source (1) is split into a first beam and a second beam after passing through the first half-wave plate (2) and the first thin-film polarizer (3); The signal pulse light generation module performs spectral broadening on the first beam of light to obtain signal pulse light, and transmits it to the near-infrared optical parametric amplification module; The near-infrared optical parametric amplification module amplifies the signal pulse light after combining the signal pulse light and the second beam light, separates the second beam light to obtain the near-infrared pulse light, and transmits the near-infrared pulse light to the mid-infrared optical parametric amplification module. The mid-infrared optical parametric amplification module amplifies the near-infrared pulse light after combining the near-infrared pulse light and the second beam, separates the second beam to obtain the mid-infrared pulse light, and transmits the mid-infrared pulse light to the pancreatic tumor ablation module. The pancreatic tumor ablation module uses an optical fiber to introduce mid-infrared pulsed light into the pancreatic tumor tissue for ablation. The signal pulse light generation module includes an aperture (8), a first plano-convex lens (9), a YAG crystal (10), a second plano-convex lens (11), and a first long-pass filter (12) arranged sequentially; the YAG crystal (10) performs spectral broadening to obtain signal pulse light; the second plano-convex lens (11) is used for collimation; The near-infrared optical parametric amplification module includes a third plano-convex lens (13), a first dichroic mirror (14), a fourth plano-convex lens (15), a time delay device, a first LGS crystal (19), and a fifth plano-convex lens (20). The signal pulse light propagates along the third plano-convex lens (13) and is combined in the first dichroic mirror (14); the second beam of light propagates along the time delay device and the fourth plano-convex lens (15) and is combined in the first dichroic mirror (14); the first LGS crystal (19) amplifies the signal pulse light; and the fifth plano-convex lens (20) is used for collimation. The mid-infrared optical parametric amplification module includes a sixth plano-convex lens (24), a third dichroic mirror (25), a seventh plano-convex lens (26), a time delay device, a second LGS crystal (30), and an eighth plano-convex lens (31). Near-infrared pulse light propagates along the sixth plano-convex lens (24) and is combined at the third dichroic mirror (25); a second beam of light propagates along the time delay device and the seventh plano-convex lens (26) and is combined at the third dichroic mirror (25); the second LGS crystal (30) amplifies the near-infrared pulse light; and the eighth plano-convex lens (31) is used for collimation. The pancreatic tumor ablation module includes a ZnSe plano-convex lens (36) and a mid-infrared fiber (37) arranged in sequence. The high-power pump source has an output power of 115W, an output pulse width of ~280fs, and a center wavelength of 1030nm. By constructing a 115W high-power pump source to pump a two-stage optical parametric amplification process, and adjusting the phase matching angle of the LGS crystal and its corresponding time delay, a mid-infrared pulse with high average power near a wavelength of 6µm is generated.

2. The pancreatic tumor ablation system for generating high-power mid-infrared femtosecond pulsed laser according to claim 1, characterized in that, The second beam of the femtosecond pulse light generated by the high-power pump source (1) is split sequentially by the second half-wave plate (4) and the second thin-film polarizer (5). One beam enters the near-infrared optical parametric amplification module, and the other beam enters the mid-infrared optical parametric amplification module after being split by the third half-wave plate (6) and the third thin-film polarizer (7).

3. The pancreatic tumor ablation system for generating high-power mid-infrared femtosecond pulsed laser according to claim 1, characterized in that, The fifth plano-convex lens (20) is followed by a second dichroic mirror (21), a first beam collector (22), and a second long-pass filter (23); the second dichroic mirror (21) is used to separate the second beam of light to obtain near-infrared pulse light; the first beam collector (22) is used to collect the separated second beam of light.

4. The pancreatic tumor ablation system for generating high-power mid-infrared femtosecond pulsed laser according to claim 1, characterized in that, The eighth plano-convex lens (31) is provided with a fourth dichroic mirror (32), a second beam collector (33), a germanium plate (34), and a metal film reflector (35); the fourth dichroic mirror (32) separates the second beam of light to obtain mid-infrared pulse light, and the germanium plate (34) is used to filter out near-infrared pulse light.

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