Medical Laser Research Articles

Selection of optimal irradiation parameters for a medical laser for nonablative tumor removal in the periorbital area

Selection of optimal irradiation parameters for a medical laser for nonablative tumor removal in the periorbital area

Ultrashort pulse lasers in medicine, current applications and prospects for future advances

Ultrashort pulse lasers in medicine, current applications and prospects for future advances

Investigate the Influence of Glass Temperature on the Absorption Coefficient of Helium-Neon (He-Ne) Laser Radiation

Density of the glass and the speed of their movement at high temperatures. As the temperature increases, the behaviour and movement of photons within the material changes, leading to more significant interactions that affect how the laser is absorbed. Overall, the results highlight the relationship between temperature and optical properties of glass, emphasizing the importance of understanding these effects for applications in materials science and engineering. The results of the study are consistent with previous research on visual materials, which confirms the hypotheses and theoretical equations that were used in the research. It studies the variables that affect optical devices at different thermal conditions, and provides valuable new practical insights for the design of modern optical components. Key findings enhance and confirm understanding of the interactions of the laser beam with materials, especially glass, which is critical for improving performance in practical and medical laser applications.

Energy-Based Medical Devices in Plastic Surgery: A Comparison of FDA-Approved Indications to Advertised Claims.

Lasers and energy-based devices are commonly employed in aesthetic medicine. In the United States, the FDA regulates lasers as medical devices, restricting marketing to approved indications and making off-label claims illegal. Despite this, no comprehensive analysis of off-label marketing prevalence exists. The authors of this study aim to compare the FDA-approved indications for 2 popular aesthetic lasers to their online advertising claims. Additionally, they seek to educate aesthetic providers on the current regulatory restrictions surrounding off-label advertising. FDA-approved indications for 2 lasers-helium plasma dermal resurfacing and 2940 nm fractional erbium-doped yttrium aluminum garnet-were obtained from the publicly available Establishment Registration & Device Listings Database. Online advertisements regarding the capabilities of each laser were collected from practice websites in the United States. Our analysis of 100 online claims for each laser revealed that more than half of the websites advertising helium plasma (n = 59) and 44 websites advertising fractional lasers made at least 1 off-label claim. Both plastic surgeons and nonplastic surgeons made at least 1 off-label claim, with no statistically significant difference between the groups. Despite FDA regulation of medical devices, online advertising regarding the indications and capabilities of popular medical lasers varies widely. Patients who seek information regarding aesthetic laser treatments may encounter inaccurate and differing claims for these treatments, potentially leading to false expectations and poor patient outcomes.

An electromechanical shutter for a medical copper vapor laser system

An electromechanical shutter for a medical copper vapor laser system

Plasmonic nanophotothermal therapy: Destruction of 500 mm3 subcutaneous human basal cell carcinoma with gold nanoparticles and near infrared laser.

Multilesional basal cell carcinoma (BCC) are spread on sun exposed skin areas, including arms, face and back. The first-line treatment remains the surgical resection or Mohs surgery. Despite its high complexity, Mohs surgery is well practiced in USA and Germany and presents very good results both in esthetic and in carcinology point of view. Large lesions more than 2cm remain challenging to remove by topical cream used in photodynamic therapy (PDT). If these larger lesions are not treated in less than 1 month, they could grow deeply in the skin, thus enhancing the risk of reoccurrence and the severity of the disease. Despite this model herein studied, that is non melanoma skin cancer is a good prognostic cancer, the therapy aims to be applied to more aggressive melanoma skin cancers. Total regression of large cutaneous lesions less than 1 month with no reoccurrence. Tumor induction on murine model bearing a 500 mm3 subcutaneous lesion. Increasing dose of gold nanoparticles at fixed initial concentration C0=0.3mg/mL, infused into the tumor then exposition of the region of interest to NIR medical laser to assess the therapy. One or two intratumoral administration(s) were compared to surgery and control, that is no treatment, laser alone or nanoparticles alone. Gold nanoparticles alone or the NIR laser alone did not induce the tumor regression. The combination of laser and nanoparticles called plasmonic nanophotothermal therapy induced apoptosis. Derma and hypoderm do not show any visible gold nanoparticles and demonstrated a good cicatrization process. Plasmonic nanophotothermal therapy using two doses of gold nanoparticles was the only protocol that proved its efficacy on large lesions in 14 days, that is 500 mm3 on a murine model bearing human basal cell carcinoma.

The Photodynamic Antibacterial Activity Properties of a Series of Indium(III) Porphyrins and their Gold and Silver Nanoparticle Conjugates

AbstractIn(III) tetraarylporphyrin complexes with 4‐thiomethylphenyl (1‐InPor), thien‐3‐yl (2‐InPor), thien‐2‐yl (3‐InPor) and 5‐bromothien‐2‐yl (4‐InPor) meso‐aryl rings have been synthesized and characterized. The complexes have been conjugated to gold and silver nanoparticles (AuNPs and AgNPs). The photodynamic antimicrobial chemotherapy (PACT) activities of 1–4‐InPor and their AuNP and AgNP conjugates have been investigated against both planktonic bacteria and biofilms of Gram‐(+) S. aureus and Gram‐(−) E. coli. 2.5 μg.mL−1 solutions of 1–4‐InPor exhibited favorable PACT activities against planktonic S. aureus with high Log10 reduction values in the 4.28–7.69 range upon 75 min photoirradiation with a Thorlabs M625L3 LED (240 mW.cm−2) mounted onto the illumination chamber of a Modulight 7710 medical laser system to provide a dose at the well‐plate of 86 mJ.cm−2.min−1. In contrast, low values in the 1.4–1.9 range were obtained against E. coli with 10 μg.mL−1 solutions. 1–4‐InPor exhibited relatively low PACT activity against the biofilm cells of S. aureus and E. coli. Conjugation of 1–4‐InPor to AgNPs and AuNPs significantly enhanced the PACT activities. This is demonstrated by the complete eradication of planktonic S. aureus at shorter irradiation times with high Log10 values>7.69 and moderate Log10 values>2 against planktonic E. coli for the meso‐thienylporphyrin conjugates.

Evaluation of a Novel Ablative 1940 nm Pulsed Laser for Skin Rejuvenation.

Skin rejuvenation is a widely sought-after goal, prompting advancements in laser technology for noninvasive and effective treatments. Ablative lasers, in particular, have evolved to address diverse skin concerns, with fractional ablative lasers offering better-tolerated outcomes. The introduction of a novel ablative Thulium pulsed laser, based on Thulium-doped Yttrium aluminum Perovskite (Tm:YAP) crystal, delivers precise and controlled skin rejuvenation by allowing customization of ablative microcolumns. A pilot in vivo study was conducted on the abdominal skin of a live female pig. Using the Laser Team Medical (LTM) prototype laser, treatments were administered with varying coagulation settings (minimal and maximum) and energies (32, 80, 120, and 160 mJ per microcolumn). Biopsies were harvested, fixed, and stained for subsequent analysis. The penetration depth and width of the microcolumns were evaluated. Low coagulation settings produced ablative microcolumns with thermal affected zones of 160 µm width, while high coagulation settings resulted in wider zones of 400-530 µm. The ablation cavities' width was estimated to be less than 100 µm in both settings. The novel 1940 nm pulsed laser demonstrated superior microcolumn properties, offering potential advantages such as shorter downtime and increased efficacy compared to existing fractional ablative lasers. This study presents encouraging preliminary results regarding the efficacy and safety of the first ablative 1940 nm pulsed laser. The results show ablative microcolumns thinner than the counterpart devices, showing the device safety and potential higher efficacy along with short downtime. The LTM novel ablative 1940 nm pulsed laser holds immense potential for enhancing skin rejuvenation treatments due to its superior microcolumns properties. The versatility of this laser can open new treatment procedures and may extend to different areas of dermatology.

Pulsed Optical Vortex Array Generation in a Self-Q-Switched Tm:YALO3 Laser.

Optical vortex arrays are characterized by specific orbital angular momentums, and they have important applications in optical trapping and manipulation, optical communications, secure communications, and high-security information processing. Despite widespread research on optical vortex arrays, the 2 μm wavelength range remains underexplored. Pulsed lasers at 2 μm are vital in laser medicine, sensing, communications, and nonlinear optic applications. The need for 2 μm-pulsed structured optical vortices, combining the advantages of this wavelength range and optical vortex arrays, is evident. Therefore, using just three elements in the cavity, we demonstrate a compact self-Q-switched Tm:YALO3 vortex laser by utilizing the self-modulation effect of a laser crystal and a defect spot mirror. By tuning the position of the defect spot and the output coupler, the resonator delivers optical vortex arrays with phase singularities ranging from 1 to 4. The narrowest pulse widths of the TEM00 LG0,-1, two-, three-, and four-vortex arrays are 543, 1266, 1281, 2379, and 1615 ns, respectively. All the vortex arrays in our study have relatively high-power outputs, slope efficiencies, and single-pulse energies. This work paves the way for a 2 μm-pulsed structured light source that has potential applications in optical trapping and manipulation, free-space optical communications, and laser medicine.

REVIEW OF THE PHYTOTHERAPY FOR NEPHROLITHIASIS

Nephrolithiasis (kidney stone) cases have a prevalence ranging from 1% to 13%. The disease not only hampers kidney function but also elevates the risk of chronic kidney diseases. The pathophysiology of nephrolithiasis is closely linked to elevated concentrations of calcium, oxalate, and/or uric acid in the urine. Pharmacotherapy to manage nephrolithiasis includes thiazide diuretics, allopurinol, citrate supplements, and alpha-blockers that have been prescribed to relieve symptoms. In addition, there is growing interest in exploring the potential of phytotherapy. This review aims to identify suitable phytotherapy approaches by examining relevant articles on nephrolithiasis. The research methodology involved searching PubMed articles using the keywords of (("Plant Extracts") AND ("Nephrolithiasis")) OR ("Ureterolithiasis"). The articles obtained from the initial search were n =123. 2 authors screened articles for their eligibility. The inclusion criteria were limited to articles written in English, topics related to nephrolithiasis and not other kidney diseases, the botanical names of the plants and the method of extraction are clearly described, complete studies with clear descriptions regarding the methods and results, not synthetic drugs, and not involving medical instruments or laser to remove the stones. Articles included in the review were n = 17. Water and hydro-alcohol were the solvents used to extract the plants. Twenty-two plants have confirmed their anti-nephrolithiasis activity, and nine articles described the assay by in vivo study, two by in vitro study, three by both in vitro and in vivo study, and only one article mentioned a study in humans by a randomized-control trial on a mixture of herbs. It is concluded that Rhizoma alismatis, Poria cocos, Polyporus umbellatus, Atractylodis macrocephalae, and Cinnamomi Cassiae prepared as a mixture in the Wu-Ling-San formula have a potential therapeutic effect on nephrolithiasis, as this formula has been studied in humans.

Therapeutic efficacy and safety of home-based portable laser irradiation on patients with wrist pain: a single-blinded randomized controlled trial

The purpose of this study is to confirm the effect of small, portable low-level laser therapy (light sources in square configuration: 830 nm GaAs diode 3.2 mW at the center, 4 × 650 nm InGaAIP diodes over the corners) treatment in reducing and enhancing hand function in patients with wrist pain. This study was a prospective, randomized, sham-controlled, and home-based self-therapy trial. A total of thirty subjects with wrist pain were enrolled. All participants received low-level laser therapy on painful area at the wrist. The experimental group (n = 15) received laser stimulation, while the control group (n = 15) received sham stimulation using identical equipment that generated only a red light without the laser output. Both groups self-treated for 30 min a day, 5 days per week for 3 weeks, total of 15 sessions. The primary outcome was assessed using a visual analogue scale (VAS) for wrist pain from 0 (painless) to 10 (extreme pain). The secondary outcomes were measured with patient-rated wrist evaluation (PRWE), grip strength, lateral, palmar, and tip pinch strength. Measures were taken before and after treatment. A total of thirty participants provided outcome data. After the intervention, both groups showed a significant decrease in VAS score, from 4.93 to 3.67 in experimental group, from 5.53 to 4.00 in control group (the experiment group: p = 0.020, the control group: p = 0.003). The experimental group showed a significant improvement in function scale score (p = 0.012), the control group did not. Lateral and pinch strength was significantly improved in the experimental group (p = 0.017) and in the control group (p = 0.034) respectively. There were no side effects in the patients. Medical laser irradiation is a portable and easy-to-use laser irradiator without side effects. Clinical Trial Registration number: KCT0006604.

A 2 µm Gallium Antimonide Semiconductor Laser Based on Slanted, Wedge-Shaped Microlens Fiber Coupling

Semiconductor lasers with a wavelength of 2 µm, composed of antimonide materials, find important applications in trace gas detection, laser medicine, and free-space optical communication, among others. In this paper, a more suitable microlens shape for 2 µm gallium antimonide semiconductor lasers is designed. Based on the fiber coupling efficiency model, the parameters of the designed slanting wedge-shaped microlens fiber are optimized to improve laser beam quality. The large tangent angle on both sides of the slanted, wedge-shaped microlens fiber is calculated using Snell’s law, and the fiber core diameter and small wedge angle are determined through space fiber coupling experiments. After packaging the fiber coupling module with the chip, the laser output beam exhibits good overall symmetry in the spot with a uniform intensity distribution. The maximum output power is approximately 210 mW, demonstrating good power stability.

Application of laser interstitial thermal therapy in the treatment of patients with euthyroid nodular goiter: aingle-center prospective study

Background. Laser interstitial thermal therapy (LITT) is one of the most effective and economically justified methods, which is recommended as the first-line treatment for patients with compression syndrome, a significant cosmetic defect, and those who categorically refuse surgery or have contraindications to it. The purpose of the study was to analyze the short-term outcomes of LITT in patients with euthyroid nodular goiter. Materials and methods. The results of LITT were analyzed in 20 patients with euthyroid nodular goiter, Bethesda category II, and solid echostructure for 2021–2023. The average volume of nodules was 0.67 (0.16; 1.39) cm3. Medical GaAlAs diode laser VELAS II-30F was used. The response of the nodules was classified as positive effect if volume reduction rate (VRR) was above 70 %, absent with VRR 69–0 %, negative effect with VRR < 0 %. The total follow-up ranged from 1 to 24 months. Results. A linear regression analysis revealed that shrinkage of the final nodule volume after the first session (0.37 (0.06; 0.9) cm3) statistically significantly depended on the initial volume (0.67 (0.16; 1.39) cm3), R2 = 0.955, p < 0.001. A positive effect was observed only in nodules up to 1.0 cm3 (average of 0.16 (0.085; 0.31) cm3). Statistically significant correlation was not found after the first session between the effect and the initial nodule volume (r = –0.163, p = 0.49). A linear regression analysis showed the absence of statistically significant correlation between the final nodule volume, final VRR, and laser characteristics (p > 0.05). The final nodule volume after the second session decreased statistically significantly vs. initial one (p = 0.007) and vs. the final volume after the first session (p = 0.028). There was no statistically significant difference between the frequency of effect in patients after single LITT and in those with two sessions (χ2 = 2.14, p = 0.34). A linear regression analysis did not show statistically significant causal relationship between these indicators (R2 = 0.27, p = 0.12). Conclusions. Laser interstitial thermal therapy is a safe method of organ-preserving treatment in patients with the euthyroid nodular goiter, which can be performed on an outpatient basis and does not lead to thyroid dysfunction. LITT is the most effective with a volume nodule of up to 1.0 cm3. The use of LITT in nodules larger than 1.0 cm3 does not meet the criteria of technical “success” but this does not necessarily indicate the overall ineffectiveness since the sample volume was insufficient. For greater validity, a study should be conducted on a larger sample of patients, which will allow reliably assessing the effectiveness of the method and determining clear criteria of selecting patients for this intervention. The study is still in progress.

All-fiberized amorphous carbon nitride (a-CNx) based passive Q-switcher

This research presents the first-ever demonstration of a passively Q-switched fiber laser in the 1.5 μm wavelength region using amorphous carbon nitride (a-CNx) as a saturable absorber (SA) in an all-fiber configuration. The a-CNx thin film was prepared using plasma-enhanced chemical vapor deposition. The laser operation showed remarkable stability, achieving a repetition rate of 57.99 kHz and a pulse duration of 1.36 μs at maximum input pump power. The peak power and pulse energy reached 100.56 mW and 136.77 nJ, respectively. The utilization of a-CNx as an SA offers potential benefits such as a simpler and more flexible cavity design, making it an attractive candidate for various applications, including material processing and medical laser equipment. This work contributes to the advancement of fiber lasers and expands the possibilities for utilizing carbon nitride-based SAs in practical laser systems.

Fabrication of PEEK Ag/AgI mid-infrared hollow fiber and transmission reliability study for CO2 laser radiation

Hollow fiber is a crucial means for delivery of mid-infrared laser radiation and has a wide range of applications in laser surgery and other fields. At present, there is still a lack of low-cost, highly flexible plastic hollow fiber that can reliably transmit mid-infrared laser with low loss. In this study, flexible Poly ether ether ketone (PEEK) tubing material was selected as the structural tube for establishing a robust plastic Ag/AgI mid-infrared hollow fiber. Fiber samples with inner diameters of 1.0, 1.5 and 2.0 mm were prepared using plasma treatment and dynamic chemical liquid deposition processes. The transmission losses for CO2 laser of the 1.0-, 1.5- and 2.0-mm-bore PEEK Ag/AgI hollow fibers increased from 0.40, 0.18 and 0.10 dB/m to 2.35, 1.60 and 1.05 dB/m, respectively, as they were bent at an angle from 0° to 180° with a radius of 15 cm. The hollow fibers could stably transmit CO2 laser in high (120 °C) and low (-78.5 °C) temperature environments. After undergoing 100 h of accelerated humidity-heat aging (85 °C, 85 % RH) and 10 cycles of high-low (-40 ∼ 85 °C) temperature cycling treatment, the transmission loss remained almost unchanged. The PEEK Ag/AgI hollow fiber exhibited high energy damage threshold and it could stably deliver a 10 ∼ 20 W CO2 laser beam for 20 min to 5 h when bent at a 25 cm radius and a 90° angle. The current research provides a possible approach for developing low-cost, highly flexible, low-loss and highly reliable mid-infrared hollow fibers. It is helpful to promote the applications of CO2 laser in laser medicine, intelligent manufacturing and sensing.

Classic techniques used in laser microsurgery of chronic diseases of the larynx: a literature review

The topicality of the issue of treating chronic diseases of the larynx is beyond dispute. Given the increased load on the vocal apparatus, no downward trend in disease incidence is observed. The percentage of patient visits to an otorhinolaryngologist with complaints of prolonged changes in voice timbre, vocal fatigue, and difficulties with voice control is 7–12%. Chronic productive formations of the larynx account for up to 55–70% of pathologies in the proliferative upper respiratory disease pattern. If not treated promptly, chronic diseases of the larynx can significantly affect a person’s ability to speak, swallow and breathe normally. Today, various methods for surgical treatment of chronic diseases of the larynx are used: both classical cold instruments and high-energy laser systems. The history of laser medicine dates from the late 1960s and is associated with the introduction of a high-intensity device emitting a photon stream in the infrared range into medical practice. The first carbon dioxide lasers were difficult to use (they were large in size and had complex technical settings), but at the same time they showed high resection and coagulation qualities, and it earned them their popularity. Over 3 thousand new laser devices representing a practical interest for laryngeal surgery have appeared on the medical market for more than 60-year period. Despite the fact that fundamental research demonstrates the positive results of phonosurgery with high-power devices, many otolaryngologists continue be in awe of lasers. The article presents the results of the use of traditional devices in phonosurgery for chronic diseases of the larynx and draws conclusions about the effectiveness and safety of high-power devices.

Growth and spectral properties of a novel praseodymium-doped alpha-barium borate laser crystal

A novel Praseodymium-doped borate (Pr:α-BBO) laser crystal was grown successfully by using the Czochralski method. The phase structure, absorption and fluorescence lifetime, as well as blue laser diode (LD) pump performances of Pr:α-BBO were totally studied. The segregation coefficient and valence state of Pr ions in the crystals were investigated using inductively coupled plasma atomic emission spectroscopy and X-ray photoelectron spectroscopy. A 450 nm blue LD was employed to carry out a pump experiment on the Pr:α-BBO slab crystal with a doping concentration of 0.22 at.%. The main emission peaks of Pr3+ ions in the orange-red light band were found to be at 611.5 nm, 634.7 nm, and 638.3 nm. The experimental results show that the Pr:α-BBO crystal exhibits higher orange light fluorescence emission performance, with an emission peak intensity at 611 nm that is 2.1 times stronger than that at 635 nm due to the splitting of the 3P0→3F2 transition (635 nm). By optimizing the Pr:α-BBO laser crystal growth process and further solid-state laser experiments, it can be expected to have broad applications in laser medicine, spectral detection, and nonlinear optical frequency conversion fields.

Passively Q-switched Erbium-Doped Fibre Laser Based on Graphene-Chitin Saturable Absorber

Graphene is a carbon allotrope composed of densely packed sp2-assembled carbon atoms in a honeycomb-like crystal lattice. It is widely used in various fields of materials science to develop sensors, optoelectronic devices, nanocomposites, and others due to its excellent electronic, mechanical, optical, and thermal properties. Graphene offers several advantages, including ease of fabrication, ultrafast recovery times, low fabrication cost, and low saturation intensities. Its unique zero bandgap property makes it the only material with wavelength-independent absorption, which is advantageous in generating pulsed lasers using saturable absorbers. This study investigates the performance of graphene with a chitin bio-host polymer as a saturable absorber in a 1.5 µm erbium-doped fibre laser. Graphene embedded in chitin was fabricated and utilized in a pulsed laser cavity operating in the wavelength region of 1.5 µm to enable Q-switched pulsed laser operation. The study achieved a pulse energy of approximately 19.83 nJ and a peak power of 10.72 mW. Increasing the pump power from 30.67 mW to 174.28 mW resulted in the highest repetition rate of 63.40 kHz, corresponding to the shortest pulse width of 1.74 µs. These findings have significant implications for applications requiring ultrafast precision and accuracy, such as medical laser equipment and flexible sensors.

Hypertonie cortisonique tardive sous implants de dexaméthasone : à propos de 20 cas

Steroid-induced ocular hypertension (OHT) occurs in approximately one third of cases after dexamethasone implant (DEXi) injection. Among these, more than one fifth occur after the third DEXi intravitreal injection (IVI). Our goal was to analyze the clinical profiles of these late responders. A real-life, retrospective, observational study was conducted to assess demographic characteristics and intraocular pressure (IOP) responses in late responders (IOP ≥ 21mmHg, n DEXi ≥ 4). The following parameters were analyzed: IOP 2months after IVI and number of glaucoma medications needed. The IOP response compared to baseline was defined as low (< +6mmHg), moderate (≤ +15mmHg) or high (> 15mmHg). Late steroid-induced OHT occurred in 20.8% of cases. Twenty eyes (18patients) were included. The mean duration of follow-up was 3.8±1.9years. They received a mean number of 9.5±4.2IVI. The first OHT peak, measured at 25.3±3.2mmHg (21-31), occurred after 6.8±2.3IVI. Approximately 65% of OHT spikes occurred between the fourth and sixth IVI; 35% occurred later. At maximum, 1.7±1.0glaucoma medications and 0.75±0.79SLT procedures were required to control the OHT, with no filtering surgery required. The ratio of "low," "moderate," and "high" responders was 5%, 85% and 10% respectively. Late steroid-induced OHT occurs after at least 3DEXi in one fifth of multi-injected patients, requiring long-term IOP monitoring. This case series identifies mostly moderate responder profiles, whose IOP rise often remains well-controlled with medical management or laser treatment (SLT).

Focusing property of autofocusing Bessel beams.

We introduce what we believe to be a new family of abruptly autofocusing waves named autofocusing Bessel beams (ABBs). Since the beams only strongly influence the area near the focus, it holds promise for medical laser treatment and optical tweezers. By the angular spectrum method, ABBs are proved to be a class solution for the Helmholtz equation. The focal length is well-defined and easily tuned in our mathematical description. Under the finite energy limitation, the abruptly autofocusing and vortex characteristics of Gaussian-modulated ABBs are studied. Interestingly, we found a kind of abruptly autofocusing waves focusing twice on the propagation axis, which is formed by an ABB passing through a focusing lens. Dual-focus ABBs make it possible for a single laser to manipulate two particles on the propagation axis simultaneously. In the experiment, the autofocusing of ABBs and the dual focus of ABBs passing through a focusing lens are observed. This article provides a theoretical model and experimental protocol for studying abruptly autofocusing waves.