A new optical fiber and method of manufacturing the same developed for use with surgical laser systems. The fiber core utilizes an ultra-low expansion (ULE) material. The preferred ULE fiber consists of silicon dioxide core doped with titanium dioxide which is cladded and jacketed for chemical and abrasion resistance. The resulting fiber is stable against degradation due to thermal expansion.
The recent rise of artificial intelligence, especially ma- chine learning and deep learning, has paved the way for a wide range of applications, and cardiac tissue engineer- ing is not an exception. Machine learning (ML) aims to develop algorithms that discover trends and patterns in existing data and use this information to make predic- tions on new data. ML has proven to be of great poten- tial value in a variety of application domains, including biological investigations and healthcare where accurate analysis of biomedical data benefits early prediction and detection of diseases . ML encompasses a diverse set of schemes by which a machine extracts certain features, “learns” the pattern of features associated with a certain group and then predicts the group based on feature pat- terns of new samples. The ML methods are particularly effective in situations where prediction involves large data sets, especially datasets of terabyte or petabyte size . Specifically, ML algorithms can perform efficient data training to identify relationships of inputs and out- puts, although there are not typically intuitive interpreta- tions for how hidden layers in these algorithms operate . However, in this field, it is still in the proof-of- concept phase where structures and algorithms have been focused in order to minimize or eliminate human intervention in these processes. For example, ML has been used for automated drug classification based on contractility of human pluripotent stem cell-derived engineered cardiac tissue , protein-ligand binding af- finity , and histopathological image analysis . Re- garding 3D scaffold constructs, the fabrication could be controlled and optimized with an adaptive neuro fuzzy inference system and a Pareto-based self-learning evolu- tionary algorithm .
Deep learning methods have garnered a lot of interest in the computer vision and image analysis communities in recent years. They have shown superior performance to statistics-based methods and other machine learning techniques in a variety of image analysis tasks. There is a growing set of deep learning- based analysis pipelines in the digital pathology domain. In this paper we presented two novel pipelines for analysis of tissue images. These methods target two core steps in tissue image analysis; segmentation of nuclei/cells and classification of images. The multiscale deep residual aggregation network is designed to segment nuclei in images. The experimental evaluation suggests that (1) the multiscale aggregation aids in improving the segmentation of (relatively) smaller nuclei and (2) advanced and sophisticated touching nuclei separation methods may hold a great potential for improving the segmentation performance in tissue specimens with discernable staining variation and instability as well as densely overlapping nuclei. The second method implements a deep neural network that classifies image patches in whole slide tissue images of non- small cell lung cancer tissue specimens as lung adenocarcinoma, lung squamous cell carcinoma or non-diagnostic regions. The experimental results show that use of a deep learning network and a random forest regression model, which uses statistical and morphological features extracted from images, can achieve good classification accuracy.
Laser scalpels, however, cannot provide haptic feed- back. For this reason, it is necessary to develop alternative methods to detect what type of tissue (e.g. fat, nerve, blood vessels) is being operated on during a surgery. One possible way, applied in this study, is to illuminate the region at and near the scalpel’s current position, and to measure the reflected light spectra. These spectra are given as smooth real-valued functions over a certain wave- length range, and are measured at discrete wavelenghts. Data of this type is called functional data . When these spectra are measured in between pulses of the laser scalpel, one can then classify them and find out what tissue is about to be ablated. Finally, this can then be assembled into an algorithm that detects when the laser is about to damage critical tissue and emits a warning sig- nal to the surgeon or temporarily shuts off the laser as an automatic feedback mechanism.
As discussed, soft tissues have a range of material proper- ties that are highly dependent on age, function, temperature, etc., so any value determined from in vivo or ex vivo experi- ments will involve a degree of uncertainty. Computational modeling has a great advantage over physical modeling in that properties may be easily changed, but these models must still be validated in some way. One proposal is to develop a simplified physical model that adequately simu- lates the human function and properties and then construct a numerical model of that system. If the numerical model is validated by the physical surrogate, then confidence is gained in the computational procedure, which can then be developed for more complex, biologically accurate systems. The 3-D nature of biological systems adds complexity to this research. In this research, we have started with simplified 2-D physical models and demonstrated the potential of dynamic digital photoelasticity. But for 3-D analysis, the integral nature of photoelasticity is a challenge, especially when combined with the dynamic nature of the problems presented and the strain rate dependency of the materials. Scalar medical tomographic techniques currently require the patient to remain still throughout the scanning procedure, so tensor tomography on dynamic systems is a huge engi- neering challenge. One solution would be to utilize the ver- satility of computational methods. In their work on streaming birefringence, Spalton et al. 33 performed a 3-D experiment and recorded integrated photoelastic data. The 3-D simula- tion data were validated by the experiment by manipulating the computational data to simulate the integral effect. The authors believe that a similar use of hybrid experimental- computational methods, using the respective advantages of both approaches with new birefringent materials and modern digital photoelasticity, offers exciting possibilities for analyz- ing highly complex human physiological systems.
Existing approaches to modeling tissue dynamics may be grouped into either discrete models or continuum models. In discrete models, tissues are treated as aggregates of cells and empirical, physical, mechanical rules (such as the differential adhesion rule [43, 44]) are enforced for both individual cells and cell-cell interactions. Cellular automata models , cellular Potts models [36, 48] and viscoelastic cellular models  are all widely used for various biological problems. It is relatively straightforward to incorporate cellular charac- teristics and extracellular information into discrete models, but such models may produce limited insight for physical reality, and the predictions from such discrete models often do not correspond to physically measurable quantities.
than 5 GPa), measured by microhardness distribution profiles, upon laser processing before metallization increases by two times (from 60 µm to 120 µm). The drawback of metallization without preliminary laser alloying is sharp drop of microhardness, which creates stress gradient at the layer interface and can lead to its pitting during operation. Laser processing provides smoother microhardness distribution profile due to more intensive progress of diffusion.
Laser machining system s have numerous advantages over the conventional methods and are increasingly used in manufacturing. These system s can operate as individual system s or they can form part of a manufacturing cell for machining and heat treatment. Recently, special attention has been devoted to laser heat treatment of cast iron m ostly because of the good combination between the ductile core and the newly formed hard, fine structured surface which significantly increases corrosion and wear resistance of the material. The investigation studies the behaviour of gray iron and ductile iron after laser heat treatment from the point of view of structure, and verifies it by measuring the changes in hardness of the hardened trace. The findings about laser heat treatment of these casts are supplemented by careful selection of optimum lasertreatment conditions.
In an attempt to reduce morbidity and improve recovery time, several minimally invasive techniques have been developed as alternatives to surgery in the last few years. Endovenous lasertreatment (ELT) is one of the most promising of these new techniques [2-4]. In 1999, Boné first reported the delivery of endoluminal laser energy . Numerous studies have since demonstrated that this tech- nique is both safe and efficacious. Several wavelengths have been proposed, respectively 810, 940, 980, 1064 and 1320 nm [6-10] with 810, 940 and 980 the most com- monly used. At these wavelengths, power is usually set between 10 and 15 W. The energy is administered endov- enously, either in a pulsed fashion (pulse duration: 1 to 3 s with fiber pull back in 3 to 5 mm increments every 2 sec- onds) or continuously with a constant pullback of the laser fiber (pullback velocity ranging from 1 to 3 mm). At these parameters, doses applied range from 20 J/cm to 140 J/cm [11,12]. These doses induce an heating of the vein wall which is necessary to cause collagen contraction and destruction of endothelium. This stimulates vein wall thickening leading to luminal contraction, venous throm- bosis and vein fibrosis . Since tumescent anesthesia is always delivered, patients feel no pain during endovenous laser ablation at the suggested or commonly used laser parameters. The pain that patients feel occurs 5–8 days following the procedure and is related to the inflamma- tion resulting from a successful endovenous ablation (i.e. wall thickening). It is not related to the presence or degree of ecchymosis nor is it the result of non-target laser dam- age to perivenous tissue. However, if greater doses of energy are delivered, the treatment is becoming painful.
Objective: Laser ablation of all placental vascular anastomoses is the optimal treatment for twin–twin transfusion syndrome (TTTS). However, two important controversies are apparent in the literature: (a) a gap between concept and performance, and (b) controversy regarding whether all the anastomoses can be identified endoscopically and whether blind lasering of healthy placenta is justified. The purpose of this article is: (a) to address the potential source of the gap between concept and performance by analyzing the fundamental steps needed to successfully accomplish the surgery, and (b) to discuss the resulting competency benchmarks reported with the different surgical techniques. Materials and Methods: Laser surgery for TTTS can be broken down into two fundamental steps: (1) endoscopic identification of the placental vascular anastomoses, (2) laser ablation of the anastomoses. The two steps are not synonymous: (a) regarding the endoscopic identification of the anastomoses, the non-selective technique is based upon lasering all vessels crossing the dividing membrane, whether anastomotic or not. The selective technique identifies and lasers only placental vascular anastomoses. The Solomon technique is based on the theory that not all anastomoses are endoscopically visible and thus involves lasering healthy areas of the placenta between lasered anastomoses, (b) regarding the actual laser ablation of the anastomoses, successful completion of the surgery (i.e., lasering all the anastomoses) can be measured by the rate of persistent or reverse TTTS (PRTTTS) and how often a selective technique can be achieved. Articles representing the different techniques are discussed. Results: The non-selective technique is associated with the lowest double survival rate (35%), compared with 60–75% of the Solomon or the Quintero selective techniques. The Solomon technique is associated with a 20% rate of residual patent placental vascular anastomoses, compared to 3.5–5% for the selective technique (p < .05). Both the Solomon and the selective technique are associated with a 1% risk of PRTTTS. Adequate placental assessment is highest with the selective technique (99%) compared with the Solomon (80%) or the ‘standard’ (60%) techniques (p < .05). A surgical performance index is proposed. Conclusion: The Quintero selective technique was associated with the highest rate of successful ablation and lowest rate of PRTTTS. The Solomon technique represents a historical backward movement in the identification of placental vascular anastomoses and is associated with higher rate of residual patent vascular communications. The reported outcomes of the Quintero selective technique do not lend support to the existence of invisible anastomoses or justify lasering healthy placental tissue.
photocoagulation is a potentially better method of treatment than chemical and electrocoagulation because it avoids the risk of large areas of scar tissue and nasal structure or vascular damage. Popular devices include the KTP laser (532 nm), the pulse dye laser (585 nm), and various diode lasers at the near infrared range (780-1064 nm) (16) .
Modern laser treatments, at wavelengths and settings matched well to individual patient and lesional characteristics, are able to produce significant diminution of CMs. Improvements of 80%–90% are frequently seen with early and optimal treatment. Adjuvant and novel treatments have been briefly explored in the literature and are likely to expand in com- ing years. The use of antiangiogenic drugs, photodynamic therapy, and other methods of targeting dilated capillaries and of limiting revascularization after lasertreatment are likely to produce further improvements. Enhancements in laser technology and epidermal protection methods will also allow more complete results to be obtained while reducing risks of pigmentary changes or scarring. Importantly, an improved understanding of the molecular, genetic, and cellular changes causing this localized capillary and venular dilatation may provide a permanent cure or preventive solution.
To determine whether there were any differences in the baseline demographic profiles of the study groups, we compared each demographic characteristic using either a t-test or chi-square test, as appropriate. Differences were considered significant at p-values < 0 .05. To determine whether the treatment was effective, we compared the study’s outcomes (Tables 2, 3, 4 and 5) in a randomized pre-test-post-test design, using a two-factor ANOVA, followed by individual t-test comparisons of outcome metric means within groups. A significant difference in the pre-test-post-test means of an outcome metric within a group was taken to indicate that the group’s intervention – lasertreatment or sham treatment – affected the out- come. A significant ANOVA interaction in the pre-test- post-test change between groups, i.e., change favouring DTLT, was taken as evidence of treatment efficacy. For measures for which the interaction was significant, un- paired t-tests were used to further explore the differences in change between the groups. Differences were consid- ered significant at p-values < 0.05.
Laser surgery has emerged as an established method in advanced medicine. Laser-induced remote tissue treat- ment provides a number of advantages: controllable co- agulation and cutting of surgical tissues with wavelength and tissue-specific cutting efficiencies [1,2]. Further- more, laser surgery allows for a high level of sterility and precision when ablating superficial tissue [3-5]. However, the facial area in particular inherits a wealth of critically important structures and organs like nerves, salivary glands and a high number of blood vessels and laser ab- lation is still mainly controlled by visual feedback and therefore subjectively dependent on the surgeon. During a pulse range, it is virtually impossible for the surgeon to estimate the depth of the laser cut and identify which structure is currently being ablated. Thus, the risk of iat- rogenic damage to sensitive structures like blood vessels or adjacent nerves increases dramatically [6-9]. For that reason, the application of surgical lasers is mainly lim- ited to superficial tissue ablation. Thus, when consider- ing profound tissue-ablation, the surgeon has to resort to a specific feedback mechanism that provides informa- tion about which structures are being affected by the laser light at the subsurface. To precisely ablate subsur- face tissue and minimize the risk of iatrogenic injury, a tissue-specific feedback system based on optical tissue differentiation could provide an essential prospect. To date, various approaches have been employed for tissue differentiation by optical methods [10-13]. Optical spec- troscopic techniques provide noninvasive and real-time information about the bio-morphological tissue para- meters by measuring light scattering and absorption properties. In this context, diffuse reflectance spectros- copy (DRS) has proven to be a straightforward, easy-to- use and effective method for optical tissue differentiation regarding premalignant and malignant tissue differenti- ation [14-16]. Recently, our workgroup was able to dem- onstrate the prospects of diffuse reflectance spectroscopy for optical differentiation of several soft and hard tissue types [17,18].
The source term comes into play because of laser-tissue optical interactions like reflection, absorption, and scattering. Many authors have developed mathematical models using different methods like Beer-Lambert‟s law, seven-flux model, Kubelka-Munk theory, photon diffusion approximation, multiple scattering, and Monte Carlo model . The selection of model relies on the laser parameters like wavelength and the precision required as well as the optical and thermal properties of the tissue. The laser light experiences scattering when impinged on the biological tissue. There have been studies on animal skin in vivo , canine and human myocardium  to confirm the scattering of wavelengths in the range of IR and visible spectrum. The beam broadening model proposed by Yoon et al.  considered the scattering phenomenon along with the absorption of light, and beam broadening occurred due to multiple scatterings. The intensity (I) at the point (r,z) can be determined by the relation:
several promising new groups of drugs being developed, especially the metallophthalocyanines (tetra-azoporphyrins) which have similar biological properties to the porphyrins, but are easier to handle chemically and assay in tissue and have much more suitable light absorption spectra (Ben-Hur and Rosenthal, 1985a; Bown et al. y 1986). However despite extensive ex perimentation with these compounds, especially the aluminium sulphonated phthalocyanine used in this work, they are not yet ready for clinical trials. Other photosensitising drugs that show promise include the chlorins which appear effective both in tumour localisation and absorption of red light (Beems et al., 1987). Synthetic porphyrins called purpurins have been synthesized by several groups (Morgan et al., 1987). These can be made with greater purity than HpD/DHE and also absorb further into the red, e.g. benzoporphyrin derivative absorbs at 690 nm. Other experimental drugs such as naphthalocyanines and bacteriochlorophylls absorb at even longer wavelengths, above 750 nm, which should make them suitable to use with the new generation of cheap semi-conductor lasers. Although there are some dyes that absorb light in the near infrared region (around 1 pm) where tissue is most transparent, their triplet state energies are too low to generate sufficient singlet oxygen for effective photodynamic action.
Wavelength: Lasers are single-wavelength light sources. There needs to be sufficient tissue penetration to adequately treat nail fungus. The near-infrared spectrum tends to be used because this is the part of the spectrum that has maximum tissue penetrance in the dermis and epidermis and the nail plate is similar to the epidermis. To date, most laser systems for treating onychomycosis have been Neodymium yttrium aluminum garnet (Nd:YAG) lasers that are typically operated at 1064 nm; 940 to 1320 nm and 1440 nm wavelengths are also options. Pulse duration: Pulses need to be short to avoid damage to the tissue surrounding the target area. For example, short-pulse systems have microsecond pulse durations and Q-switched lasers have nanosecond pulse durations.
We note that the notch grew out at the same rate on the treated as on the untreated toe. This means that there is neither an obvious biostimulatory effect of laser light on nail plate growth, nor is there an inhibitory effect. There were no visible effects of treatment (discoloration, surface texture changes, etc.) seen in any of the photographs or reported by the investigator. In this sample of 17 patients treatment of the toenail with the FootLaser did not damage the nail plate, the underlying nail bed, the matrix, or the surrounding tissue. On the contrary, in a few of the subjects (for example Figure 1 and Figure 4, Subject 0014) an irregular contoured nail grew out looking smooth and natural.