外文翻译---激光的组织接合：激光束光斑尺寸和研究概况.docx

附录A 英文原文Laser Tissue Welding: Laser Spot Size and Beam Prole StudiesAbstract：This paper evaluates the effect of laser spot diameter and beam prole on the shape of the thermal denaturation zone produced during laser tissue welding. 2-cm-long full-thickness incisions were made on the epilated backs of guinea pigs in vivo. India ink was used as an absorber and clamps were used to appose the incision edges. Welding was performed using continuous-wave 1.06-m, Nd:YAG laser radiation scanned over the incisions to produce 100-ms pulses. Laser spot diameters of 1, 2, 4, and 6 mm were studied, with powers of 1, 4, 16, and 36 W, respectively. The irradiance remained constant at 127 Monte Carlo simulations were also conducted to examine .the effect of laser spot size and beam prole on the distribution of photons absorbed in the tissue. The laser spot diameter was varied from 1 to 6 mm. Gaussian, at-top, dual Gaussian, and dual at-top beam proles were studied. The experimental results showed that 1-, 2-, 4-, and 6-mm-diameter spots produced thermal denaturation to an average depth of 570, 970, 1470, and 1900 m, respectively. Monte Carlo simulations demonstrated that the most uniform distribution of photon absorption is achieved using large diameter dual at-top beams. Index Terms Denaturation, laser biomedical applications, laser materials-processing applications, laser welding, Monte Carlo methods, optical propagation.MATERIALS AND METHODSA. ExperimentsIn vivo welding of skin incisions was performed at constant irradiance to investigate the effect of various laser spot sizes (1-, 2-, 4-, and 6-mm-diameter FWHM) on the extent of thermal denaturation at the weld site. Adult female albino guinea pigs (Hartley, age 78 weeks, weight 400500 grams) were shaved then epilated with a chemical depilator (Nair,Carter-Wallace, Inc., New York, NY). Each guinea pig was anesthetized with atropine (0.05 mg/kg), ketamine (30 mg/kg), and xylazine (2 mg/kg) administered by intraperitoneal injection. 1% lidocaine with 1:100000 epinephrine was used as a local anesthetic at each incision site. 2-cm-long, fullthickness incisions were made parallel to the spine with a no.15 scalpel. Four incisions were made on the back of each guinea pig. Approximately 25 l of India ink (black India Rapidograph ink, 3080-F, 100-nm particle diameter, Koh-INoor, Bloomsbury, NJ) were applied to the wound edges with a micropipette. The animal was then placed prone on a translation stage, in preparation for surgery. Clamps were used to temporarily appose the incision edges during welding.Welding was performed with a continuous-wave (CW), Nd:YAG laser (Lee Laser, Model 703T) emitting 1.06 radiation that was coupled into a 600 -core diameter optical ber (Thor Labs, Newton, NJ). A stepper-motor-driven translation stage (Newport, Irvine, CA) scanned the laser beam along the axis of the weld site at speeds that effectively produced 100-ms-long pulses. Seventy scans were made along each weld; the beam stopped at the end of the weld site for 10 s after each scan. To minimize thermal damage to the skin beyond the weld area, high-reecting metal plates placed on each end of the incision blocked the beam. Experiments were performed at constant irradiance (127) comparing laser spot diameters of 1, 2, 4, and 6 mm full-width at full-maximum(FWHM), with laser output powers of 1, 4, 16, and 36 W, respectively. The beam prole, as measured by scanning a 200- m-diameter pin hole across the beam, was approximately Gaussian for all spot diameters. The power delivered to the tissue was measured before each weld with a power meter (Molectron PowerMax 5100, Portland, OR). It shows the experimental conguration used for dye-assisted laser skin welding and summarizes the laser parameters for this study.After welding, the anesthetized guinea pig was euthanized with an intracardiac overdose of sodium pentobarbitol (Nembutal, Abbott Laboratories, North Chicago, IL). The dorsal skin, including epidermis and dermis, was excised with a scalpel and then sectioned. Samples were processed using standard histological techniques, including storage in 10% formalin, processing with graded alcohols and xylenes, paran embedding, sectioning, and hemotoxylin and eosin staining. A minimum of seven samples was processed for each laser spot diameter and beam prole. The 6-mm-diameter spot study was discontinued after grossly obvious burns developed at the wound site.Thermal denaturation measurements were made using a transmission light microscope (Nikon, Japan) t with crossed linear polarizers (Prinz, Japan). Thermal denaturation was measured laterally from the center of the weld site at three different depths: the papillary dermis, mid-dermis, and base of the dermis. The depth to which one observed denaturation was recorded and divided by the skin thickness to obtain the fraction of a full-thickness weld that was achieved. Measurements were made consistently to the point at which complete thermal denaturation of the tissue was observed.Statistical analyzes were conducted on the histological data. ANOVA was used to determine statistical signicance of thermal denaturation measurements between laser spot size groups.B. Monte Carlo SimulationMonte Carlo simulations were run to investigate the effect of various spot sizes (16-mm diameters) and beam proles (Gaussian versus at-top and single versus dual beam) on the distribution of absorbed radiation. All simulations were run using code available over the public domain . Several changes were made in the Monte Carlo code to adapt it for use with the geometry of this application. First, because the vertical ink layer in the tissue disrupted the cylindrical symmetry assumed in the Original program, the data were stored in Cartesian rather than cylindrical coordinates and a convolution program was not used to generate the laser beam prole. The beam prole was, instead, created using a random number generator ; a large number of photons was used to create the desired beam prole. Second, the vertical ink layer was modeled as an innite absorber extending from the skin surface to the base of the dermis with a uniform thickness of 100 m. The experimentally measured absorption coefcient for the ink, was 3500 cm. Even though histologic analysis of the welds showed variable staining of the tissue with a lateral thickness varying from 40 to 100 m, since the ink layer thickness was much greater than the probability that a photon could cross the ink layer was negligible, and the assumption that was innite is reasonable. Third, the skin was modeled as a single dermal tissue layer with the assumption that the epidermis and subcutaneous tissue have optical properties similar to that of the dermis. Finally, even though the optical properties of tissue are known to be temperature-dependent, with the dermal scattering coefcient initially increasing with temperature for temperatures less than 60 C then decreasing sharply at higher temperatures and the dermal absorption coefcient decreasing with increasing temperature , the optical properties in this model were assumed to be static. This assumption, which avoided a complete optical-thermal model, will result in a slight underestimation of the penetration depth of the photons in the dermis. The optical properties of guinea pig skin at a wavelength of 1.06 have not been well characterized. The optical properties for human, pig, and rat dermis were therefore. compiled from several sources. The optical properties used in the Monte Carlo simulations are listed in Table II. Note that in the experimental irradiations, the irradiance was held constant at 127 . For the simulated irradiations, the mean irradiance over the full-width, halfmaximum of each beam was constant (10 photons per 1-mm-diameter area). The grid element size in the tissue was xed at 100 m, and the dimensions of the tissue (length width depth) were 1.0 cm 1.0 cm 0.5 cm, respectively. The tissue thickness was, in part, chosen based on the knowledge that human skin may be thicker than guinea pig skin, ranging in thickness from 1 to 4 mm. Simulations were run on a Pentium 133 MHz PC computer (Micron, Nampa, ID)running Microsoft Windows 95 (Microsoft, Redmond, WA)III. RESULTSA. ExperimentsHistologic analysis showed that only shallow welds were achieved using a 1-mm-diameter laser irradiation area. Thermal denaturation was observed only to a depth of 570100 (meanS.D.,n=7) or 30% of the average dermal thickness of 1900200 , see Table III. Thermal denaturation lateral to the incision was limited to near the tissue surface. An image of a weld created with a 1-mm-diameter spot is shown in.When the laser spot diameter was increased to 2 mm, thermal denaturation was observed down to the middle layers of the dermis, as show. The thermal denaturation extended to an average depth of (n=7)(p0.001) or 50% of the dermal thickness. This depth was signicantly greater than achieved with a 1-mm-diameter spot Signicantly more lateral thermal denaturation was also measured at the surface of the skin, m, than for the 1-mm-diameter spot.Increasing the spot diameter to 4 mm resulted in welds with an average depth of (n=7) , or 80% of the dermal thickness。The depth of these welds was signicantly greater than that produced in both the 1-mm- and 2-mm-diameter spot studies(p0.001).The lateral zone of thermal denaturation near the epidermis measured similar to that measured for the 2-mm-diameter spot study Signicantly more thermal denaturation was measured in the middle layers of the dermis for the 4-mm-diameter spot(,n=7), than for the 2-mm-diameter spot (,n=7)(p0.001) The thermal denaturation gradient was less, however, when moving from the upper to middle layers of the dermis for the 4-mm-diameter spot than for the 2-mm-diameter spot. The use of a larger spot diameter therefore resulted in not only deeper, but also more uniform welds.Experiments performed with a 6-mm-diameter spot resulted in full-thickness welds of in depth. During surgery, however, the tissue surrounding the weld site began to redden,blanch, and eventually burn. Due to concerns over the welfare of the animals, these experiments were terminated before statistically signicant quantitative data could be obtained.It should be noted that in some places where there were signicant tinctoral and textural changes to the collagen bers that made the tissue appeared completely denatured, signicant collagen birefringence was often still present. In such cases,we measured to the edge of the region of tinctoral and textural change. This observation suggests that one should be careful when using birefringence as a tool for quantifying the extent of thermal denaturation in tissue.B. Monte Carlo SimulationsIt shows the effect of laser spot diameter on the absorption prole. absorption is plotted as a function of the depth into the tissue along the ink layer for an incident beam with a Gaussian beam prole. The absorption at the surface(d=0.0mm) is due to direct absorption of the incident radiation by the ink layer as well as absorption of backscattered radiation. The absorption immediately beneath the surface increases with increasing laser spot diameter because a larger number of photons are backscattered into the ink layer as the spot diameter increases. The distribution of photon absorption along the ink layer with depth in the tissue becomes more uniform at larger spot diameters. The use of a large diameter laser spot results in less scattering of radiation out of the initially collimated laser beam, resulting in a higher effective penetration depth. The depth at which the absorption drops to of the absorption at m is 1.0, 1.2, 1.6, and 2.0 mm for the 1.0-, 2.0-, 4.0-, and 6.0-mm-diameter spots,respectively. These results compare well with the thermal denaturation depths achieved in the experimental studies.附录B 中文译文激光的组织接合：激光束光斑尺寸和研究概况摘要：本文主要研究在激光缝合肌肉组织时激光光斑的热变性对缝合效果的评估。将实验白鼠背部去毛切开2cm长的全层切口，用夹子在切口边缘附近固定。进行缝合的是采用连续波1.06 Nd：YAG激光器扫描辐射对切口产生100ms脉冲。1，2，4和6mm激光光斑直径进行了研究，其能量分别为1，4，16，36W。辐照度维持为127。本文对蒙特卡洛模拟也不断进行研究。激光光斑的大小以及光束中光子的分布在内部被吸收。激光光斑直径是不同的，从1到6mm。高斯，平顶，双高斯，双平顶光束剖面进行了研究。实验结果表明，1，2，4和6mm直径的斑点产生的热变性的平均深度分别为570，970，1470和1900m。蒙特卡罗模拟表明，光子吸收最均匀分布是通过使用大口径双平顶光束。关键词：激光生物医学应用，激光材料加工应用，激光缝合，蒙特卡罗方法，光的传播。材料和方法A实验在表面切口内部缝合是在不断进行辐照，调查在缝合时各种激光光斑尺寸效应的热变性程度（1，2，4，6mm直径的半高宽）。把成年白鼠（哈特利，年龄7-8周，体重400-500g）用化学脱毛剂脱毛（奈尔，卡特-华莱士公司，纽约，NY）。每个豚鼠被麻醉用阿托品（0.05 mg/kg），氯胺酮（30 mg/kg），甲苯噻嗪（2 mg/kg）腹腔注射给药。把1利多卡因与1:10万肾上腺素作为局部麻醉用在每个切口部位。用15号手术刀在平行的脊柱进行了2cm长的全层切口。拿微吸管将大约2-5升墨汁（印度Rapidograph黑色油墨，3080- F，100纳米颗粒的直径，酸值INoor，Bloomsbury区，新泽西州）分别适用于伤口边缘。将试验品俯卧放置在实验台，为手术准备。夹子被用来在缝合时放在附近的切口边缘固定。缝合的进行是用连续波（CW），Nd：YAG激光（李激光，型号703T）发光1.06辐射成600芯径光纤（托尔实验室，牛顿，新泽西州）。用电机驱动（新港，尔湾，加利福尼亚州）沿伤口控制缝合速度，有效地生产的100ms长的脉冲激光束的轴。扫描每个缝合点，光束在缝合点每次扫描10s停止一次。为了尽量减少缝合面积以外的皮肤收到热损伤，每个切口结束位置都防止金属板来阻挡。实验是在恒定光照下（127的）比较激光光斑直径1，2，4，6ms，激光输出功率分别为1，4，16，36W 在全最大（FWHM）全宽。通过让光束通过200直径的针孔来衡量光束剖面，所有光斑直径约为高斯分布。传递到每块肌肉组织的能量与功率计（MolectronPOWERMAX5100，波特兰，OR）连接。给出了实验配置染料辅助激光焊接皮肤使用。总结了这项研究的激光参数。接合后，实验白鼠是安乐死于过量的钠pentobarbitol（戊巴比妥，雅培公司，北芝加哥，IL）。背侧皮肤，包括表皮和真皮，是用手术刀切除，然后切片。样品处理采用标准组织学技术，包括10的福尔马林存储，与分级醇，二甲苯，石蜡包埋，切片，HE染色和hemotoxylin和处理。每个激光光斑直径和光束最少进行七次实验。6mm直径的光斑用于实验，发现伤口部位有非常明显的烧伤，因而停止实验。热变性测量是用透射光显微镜（Nikon，日本）配合（普林茨，日本）线性偏光片。热变性是指从缝合中心在三个不同深度的方向延伸：乳突状真皮，中真皮，以及真皮基地。深度观察每一个变化的记录和皮肤的厚度为获得一个完全缝合后接合处最小的部分。测量研究组织的热变性，观察点。统计分析是进行实验的数据。用方差来确定激光光斑大小群体之间的热变性测量统计学意义。B.蒙特卡罗模拟蒙特卡罗模拟是调查各种斑的大小（1 6mm直径）和光束剖面（高斯与平顶，单与双光束）对吸收的辐射分布的影响。所有模拟均可以运行使用公共领域的代码。一些变化的蒙特卡洛代码，用来适应与此应用程序使用它的几何形状。首先，因为在组织垂直油墨层打乱了圆柱形对称假设在原程序，数据存储在直角坐标，而不是圆柱和卷积程序，不用于产生激光光束。光束剖面，而是创建使用一个随机数发生器，大量的光子被用来创建所需的光束。第二，垂直油墨层建模为一个无限延伸，从皮肤表面下100m厚度的真皮作为吸收基础。为实验测量油墨的吸收系数，被3500c