Multi-pass Treatment Research Articles

Full-face and neck resurfacing with a novel ablative fractional 2910 nm erbium-doped fluoride glass fiber laser for advanced photoaging.

Ablative fractional lasers have long been considered the gold standard for facial resurfacing for advanced photoaging. These lasers offer an improved safety profile compared to traditional ablative lasers but typically require more treatment sessions given their fractional approach. In this study, we evaluate a new novel 2910 nm erbium-doped fluoride glass fiber laser (2910 nm fiber laser) (UltraClear; Acclaro Medical) for full-face and neck resurfacing for the treatment of advanced photoaging. Twenty-two healthy subjects aged 44-80 years presenting for advanced facial photoaging and rhytides were enrolled in the study. All subjects received three full-face and neck, multipass treatments utilizing the 2910 nm fiber laser spaced 6-8 weeks apart. Subjects were asked to rate the average level of pain during the treatment. At 90 days following subjects' third treatment subjects evaluated their improvement using a Global Aesthetic Improvement Scale (GAIS) and rated their satisfaction with the treatment. Evaluation of pretreatment and posttreatment photos was completed by two blinded physician reviewers. Reviewers were asked to identify the pretreatment and posttreatment photographs and to rate the degree of improvement utilizing a GAIS. Fifteen participants completed the study; six were exited from the study (withdrew or lost to follow-up). The average subject GAIS score for overall appearance was 3.8. The average subject satisfaction level at follow-up was 4.8. The average subject pain score was 4.9. One blinded physician reviewer correctly identified 100% of subjects' posttreatment photographs, while the second blinded reviewer correctly identified 93%. Blinded evaluation of digital photographs revealed an average GAIS score of 3.2. Posttreatment skin responses included pin-point hemorrhage, erythema, edema, and soft tissue crusting lasting 5-7 days. There were no instances of infection, scarring or hypopigmentation. There were two instances of temporary hyperpigmentation. Treatment with the novel 2910 nm fiber laser is safe and effective in treating advanced photoaging and rhytides. Three treatments produced moderate to marked improvement with high patient satisfaction and treatment was associated with less discomfort and downtime compared to conventional fractional ablative lasers.

Aquablation Outcomes in Men With LUTS Due to BPH Following Single Versus Multi-pass Treatments

OBJECTIVETo determine whether existing data support the use of multiple passes in Aquablation for LUTS due to BPH. METHODSData were obtained from 2sources. The WATER trial (NCT02505919) is a prospective, multicenter, double-blind, randomized controlled trial of Aquablation vs TURP in prostate volumes of 30 - 80 ml. The WATER II trial (NCT03123250) is a prospective single-arm multicenter trial of Aquablation in prostate volumes of 80-150ml. The number of passes was determined by the procedural data collected and the video recordings of all study cases. RESULTSIn total, 127 Aquablation subjects underwent a single pass, 90 underwent multiple passes (80 had 2passes and 10 underwent 3passes), and 65 underwent TURP (in WATER only). Men undergoing 2or more passes with Aquablation had larger prostates but few differences in other baseline parameters, including prostate size range. Compared to a single pass, the use of 2or more passes during Aquablation resulted in lower IPSS scores (by ∼4 points, P = .0002) and lower IPSS QoL scores (by ∼0.7 points, P = .0096) at the later timepoints of 24 and 36 months. Similarly, 36-month Qmax values were higher (by ∼5 ml/sec, P = .0220) in those with 2or more passes than in those with 1pass. There was no statistically significant difference in ejaculatory dysfunction between groups. CONCLUSIONIndependent of prostate volume, a multiple treatment pass protocol led to improved voiding outcomes and IPSS improvement.

COMPARATIVE ASSESSMENT OF TATTOO REMOVAL WITH SINGLE SESSION OF R20 TECHNIQUE AND CONVENTIONAL TECHNIQUE

Background: Most suitable devices for tattoo removal at present are Q-switched ruby, Nd:YAG and Alexandrite lasers. 1 These are the current gold standard for laser tattoo removal . But there are few limitations, such as long duration of treatment, large interval between sessions; side effects such as blistering, scarring and dyschromia. The current methods attempted to reduce the total number of sessions and total duration to achieve clearing of tattoos. R20 method of tattoo removal is based on principle of repeated exposure of laser light in a single session. Aim: 1) to compare lightning of tattoos with a single pass Q-switched laser treatment with 4 treatment passes separated by 20 minutes 2) To compare the Adverse effects between two methods Methods and Material: It included 50 patients and were divided in half and randomized. Half of them received single pass treatment with Q-switched Nd:YAG laser 1064 nm used at energy of 360 mJ. Other half received multipass treatment (each pass at 20 minutes interval with maximum of 4 pass). Tattoo lightening and adverse effects compared 1month later i.e. after single session. Results: 1 month later, treatment with the R20 method was much more effective than conventional single-pass laser treatment. With R20 method, 100% patients experienced immediate erythema and edema, 16% patient experienced blistering, crusting. No obvious Scarring/permanent pigmentary changes in any patient. >75% fading experienced by 18 patients after single session, 50-75% fading in 4 patients, 40% experienced transient hypopigmentation. With single pass technique, all patients experienced <50% fading. Conclusion: With R20 method the number of sessions required for tattoo removal is greatly reduced thus decreasing the number of visits. It is more effective but also safe in most of the patients. The disadvantages are one single session can take 3½ to 4 hours.

Multi-pass deposition of organosilicon-based superhydrophobic coatings in atmospheric pressure plasma jets

Atmospheric-pressure plasma polymerization of organosilicon precursors such as hexamethyldisiloxane is a well-known process used in the development of SixOyCz thin films on various substrates in different plasma configurations. Typically, long treatments or multi-pass treatments are used to achieve a sufficient thickness. However, the effects of multiple deposition passes on surface properties are rarely considered. In this paper, the development of a superhydrophobic organosilicon-based coating on pre-treated micro-roughened Al-6061 substrates through multiple deposition passes with an atmospheric-pressure plasma jet is reported. It is shown that besides the expected effect on coating's thickness, multiple passes of plasma deposition can also alter surface morphology and surface chemistry through a mechanism similar to the activation of organosilicon substrates with oxygen-containing plasmas. While the increase in coating thickness enhances coating stability in aggressive conditions, the rise of oxygen content reduces the hydrophobic behaviour of the coating.

Simulation of an energy self-sufficient electrodialysis desalination stack for salt removal efficiency and fresh water recovery

Electrodialysis is a commonly used desalination method. In this study, we investigate its hybridization with its reverse process, where reverse electrodialysis (RED) harvests the salinity gradient power to provide the driving force for electrodialysis. In particular, the desalination performance (rejection and recovery) and their tradeoff relationship are simulated for the first time for an energy self-sufficient RED-ED desalination stack (REDD). The simulation results show that these two parameters can be simultaneously optimized by tailoring ion exchange membranes in the stack, i.e., using more selective membranes in the ED sub-cell (EDcell) and less selective membranes in the RED sub-cell (REDcell). Our analysis shows that a considerable driving force (e.g., a salinity ratio of high salinity stream to low salinity stream over 30 and a volumetric ratio over 0.5) is required to fully unleash the desalination performance of REDD, leading to a favorable shift of the rejection-recovery tradeoff line. In addition, multi-pass treatment is demonstrated to further enhance rejection at the expense of lower recovery. Similarly, a multi-stage configuration can be applied for higher recovery. This study reveals the operational constraints of a novel desalination REDD technique and provides insights into performance enhancement.

Laser tattoo removal: A clinical update

Techniques for tattoo removal have evolved significantly over the years. The commonly used Quality-switched (QS) ruby, alexandrite, and Nd:YAG lasers are the traditional workhorses for tattoo removal. Newer strategies using combination laser treatments, multi-pass treatments, and picosecond lasers offer promising results. The tattoo color and skin type of the patient are important considerations when choosing the appropriate laser. Standard protocols can be developed for the effective and safe treatment of tattoos.

New Tattoo Approaches in Dermatology

Tattoos have fascinated mankind for centuries. Although these body marks were once considered to be permanent, technical and scientific progress in recent years has made it possible to remove tattoos by various treatment modalities. Contemporary technology involves the use of nonablative quality-switched lasers, which are considered to be the gold-standard treatment option for the removal of unwanted tattoo ink. Current research in the field of tattoo removal is focused on faster lasers and more effective targeting of tattoo pigment particles including picosecond laser devices, multi-pass treatments, dermal scatter reduction, application of imiquimod, and the use of microencapsulated tattoo ink.

Inflammatory Effect of Monopolar Radiofrequency Treatment on Collagen Fibrils in Rabbit Skins

This study quantitatively examined the effects of monopolar radiofrequency (RF) treatment on the progressive nanostructural changes in the inflammatory effect of in vivo rabbit dermal collagen fibrils during postoperative 7 days. Conventional histologic analysis and atomic force microscopy (AFM) were employed to assess the nanostructural dermal response in 6 RF groups that underwent 2 passes of RF treatments (10 and 20 W), and 1 untreated control rabbit. After monopolar RF treatment, the rabbit skin clearly showed changes in the collagen network structure. The RF-treated group showed regular parallel arrangement of collagen fibrils whereas normal group showed tangled nanostructures. This phenomenon was remarkable at postoperative 7 days. Therefore, monopolar RF treatment leads to underlying collagen contracture and promotes new collagen formation. A multi-pass treatment of low-energy RF led to the highest contraction of collagen fibrils at the nanostructural level, compared to a single pass of high-energy RF.

An investigation on pulsed electric fields technology using new treatment chamber design

A pulsed electric field (PEF) system was designed and constructed using modern IGBT technology. The main focus of this work was to design a new PEF treatment chamber that operate at high electric field intensities with limited increase in liquid temperature and limited fouling of electrodes. Four multi-pass treatment chambers were designed consisting of two stainless steel mesh electrodes in each chamber, with the treated fluid flowing through the openings of the mesh electrodes. The two electrodes are electrically isolated from each other by an insulator element designed to form a small orifice where most of the electric field is concentrated. Dielectric breakdown inside the chambers was prevented by removing the electrodes far from the narrow gap. The effect of PEF treatment on the inactivation of gram-negative Escherichia coli ATCC 25922 suspended in simulated milk ultra-filtrate (SMUF) of 100%, 66.67% and 50% w/w was investigated. Treatments with the same electrical input power but with higher electric field strengths provided larger degree of killing. The effect of PEF treatment using suspensions at different flow rates and different pulse frequencies was also investigated. In general, the inactivation rate of E. coli increased with increasing electric field strength, treatment time and processing temperature. More than 6 log reductions in E. coli suspended in SMUF was achieved using electric field intensity in the range of (37.2–49.6 kV/cm) with a treatment temperature not exceeding 38 °C.

The effects of pulse dye laser double‐pass treatment intervals on depth of vessel coagulation

Multi-pass treatments with pulse dye lasers (PDLs) are avoided due to perceived side effects. Proper multi-pass techniques allow for deeper vascular injury. New extended PDLs allow use of multi-pass procedures. This study evaluates how the time between pulses, inter-pulse interval [IPI] affect extent of vascular treatment. Sixteen subjects were exposed to a series of exposures on normal skin to determine depth of injury for various IPI. Subjects were exposed to single pass, and 4 double-pass intervals. Tests included exposures at 0.5 milliseconds, 2-7 j/cm(2). Exposures included one and two passes, IPI of 1, 10, 30, and 60 seconds; 5 and 30 minutes. Treatments were done with PhotoGenica V-Star (595-nm), SmartCool air cooling. Biopsies were taken: single pass and double pass purpuric thresholds; and at 7 j/cm(2) to determine depth of vascular coagulation. Histology revealed increased vascular coagulation depth at purpura threshold for intervals of 1, 10, 30, and 60 seconds between passes compared to single pass treatment, and a significant monotonic increase in depth of vascular injury at 7 j/cm(2) with increasing IPI. The use of multiple passes increases depth of vascular injury, which may increase the efficacy of treatment without significant increase in purpura or risk of scarring for treatments at purpura threshold. At purpura threshold, the depth of vascular injury increases with increasing IPI up to 60 seconds. Above purpura threshold, there is a monotonic increase in depth of vascular injury for IPI up to 30 minutes. These observations suggest multi-pass treatment methods may be beneficial when employed with PDLs.

Multipass treatment of photodamage using the pulse dye laser.

Pulse dye lasers (PDLs) alter structural proteins in scars and photodamaged skin, in addition to their effects on dermal vasculature. The PDL has become an option in the treatment of photodamage. Although improvements to skin texture are generally modest when compared with ablative resurfacing, PDL offers a treatment with few side effects. A number of methods have been proposed in an effort to improve treatment outcomes. These range from single, low-fluence treatment with no purpura to multiple passes and treatment sessions as well as purpuric doses. To evaluate several of the PDL treatment methods to improve photorejuvenation outcomes while limiting the risk of side effects. Twenty patients with photodamage were separated into two groups. Each group received a series of four single-pass treatments or four double-pass treatments at 2-week intervals. Treatments were done using a 595-nm PDL (PhotoGenica V-Star) and a 585-nm PDL (PhotoGenica V) at a pulse duration of 0.5 ms and a 10-mm handpiece. Treatment fluences were maintained below the individual's purpuric threshold, ranging from 3 to 4 J/cm2. Photos were taken before treatment and during follow-up. Efficacy of treatment was based on subjective grading of photos and by patient self-reporting. Multiple treatments resulted in improvements to skin tone and texture, including a reduction in the appearance of rhytids and, in particular, improved pigmentary evenness. There was no significant difference between laser or treatment methods. No side effects were noted. PDL treatments provide effective photorejuvenation with minimal risk of side effects.

Multipass Treatment of Photodamage Using the Pulse Dye Laser

BACKGROUND Pulse dye lasers (PDLs) alter structural proteins in scars and photodamaged skin, in addition to their effects on dermal vasculature. The PDL has become an option in the treatment of photodamage. Although improvements to skin texture are generally modest when compared with ablative resurfacing, PDL offers a treatment with few side effects. A number of methods have been proposed in an effort to improve treatment outcomes. These range from single, low-fluence treatment with no purpura to multiple passes and treatment sessions as well as purpuric doses. OBJECTIVE To evaluate several of the PDL treatment methods to improve photorejuvenation outcomes while limiting the risk of side effects. METHODS Twenty patients with photodamage were separated into two groups. Each group received a series of four single-pass treatments or four double-pass treatments at 2-week intervals. Treatments were done using a 595-nm PDL (PhotoGenica V-Star) and a 585-nm PDL (PhotoGenica V) at a pulse duration of 0.5 ms and a 10-mm handpiece. Treatment fluences were maintained below the individual's purpuric threshold, ranging from 3 to 4 J/cm2. Photos were taken before treatment and during follow-up. Efficacy of treatment was based on subjective grading of photos and by patient self-reporting. RESULTS Multiple treatments resulted in improvements to skin tone and texture, including a reduction in the appearance of rhytids and, in particular, improved pigmentary evenness. There was no significant difference between laser or treatment methods. No side effects were noted. CONCLUSION PDL treatments provide effective photorejuvenation with minimal risk of side effects.

Treatment of telangiectasia using the multi-pass technique with the extended pulse width, pulsed dye laser (Cynosure V-Star)

The pulsed dye laser (PDL) has been used for the treatment of facial and leg telangiectasia, where it provides safe and effective treatment. Often, a single treatment with the PDL can provide acceptable vessel clearance. Unfortunately, the hallmark of PDL treatment is transient purpura, which can be cosmetically unacceptable to patients. A new class of PDL has been developed in an effort to reduce this transient side effect while maintaining both safety and efficacy. To evaluate the ability of multi-pass treatment for telangiectasia with extended pulse width (40 ms) PDL to provide effective, single-treatment vessel treatment without inducing purpura. A total of 40 patients presenting with facial or leg telangiectasia were treated with the extended pulse width PDL (595 nm), used in conjunction with refrigerated air-cooling (SmartCool; Cynosure). Treatment was given using a pulse width of 40 ms and fluences at or below the purpuric threshold (less than 16 J/cm(2)) and with high-flow air cooling at -4 degrees C. Up to three passes were given until vessel disappearance or intravascular coagulation was observed. A second treatment was done, where needed, 4-8 weeks following the initial treatment. Patients were evaluated 4, 8, and 12 weeks after the final treatment. Following a single treatment, 70% of facial and 80% of leg vessels exhibited at least 75% clearance. After two treatments, 14/20 leg vessels cleared at 75-100%. In all cases, vessel clearance was associated with transient purpura lasting less than 7 days. Hyperpigmentation occurred in 5% of facial vessels and 55% of leg veins. Sub-purpuric doses did not provide acceptable single-treatment clearance. Extended pulse width dye lasers significantly increase the threshold for purpura, allowing higher fluences to be employed. For the goal of single treatment vessel clearance, the extended pulse duration provided acceptable, single-treatment improvement but only in the presence of purpura. While additional, non-purpuric treatments may provide acceptable outcomes, additional improvements will be necessary to provide consistent, effective, single-treatment clearance of telangiectasia without generalized purpura.

Laser perforation of holes in panels of titanium alloys

on the geometrical distribution of the holes: the distance between them is 0.7 mm, the distance between numbers of holes is 0.6 mm, and the distribution of rows along the length and width of the panels is kO.5 mm. Taking these requirements into account and the need to produce a very large number of holes on each panel, it was necessary to develop a standard perforation technology including the method of positioning and securing the panel, determination of the start of operation of the programs, movement ofthelaser along the co-ordinates x and y along the panel and stabilisation of the co-ordinate throughout the entire perforation time of each panel. For perforation of large panels it was necessary to develop and produce special equipment moving the laser radiation source along and across the working table. The equipment has the form of a gantry moving in the longitudinal direction above a stationary sheet to be perforated (panel). A track with an LTN-101 laser and an optical system fixed to it moves along the gantry (across the sheet). The movement of the gantry and the track is realised using a gear transmission consisting of racks and pinions. The play in the transmission is removed by pressing the teeth of the gears with springs to the teeth of the racks. The longitudinal drive includes two racks for preventing misalignment of the gantry during its movement. The position sensors are in the form of rotating transformers and the travel speed is stabilised using tachogenerators. Consequently, the accuracy of positioning is around 0.01 mm. When producing single holes of the given form, it is possible to use multipass and single-pulse treatment. In the first, each hole forms during several pulses. Multipass treatment requires usually arresting the movement of the laser in relation to the panel and greatly extends the perforation cycle. Taking into account the large volume of perforations, single-pulse perforation technology was used. In perforation of the holes in the single-pulse regime, each hole forms as a result of the effect of a short laser beam pulse during several microseconds. In this highspeed process, each hole must be produced without arresting the movement ofthe laser in relation to the panel during the treatment time, because the travel speed is considerably lower than the speed of formation of each hole. This method is more suitable for the perforations of largeareas ofplating panels with a small allowance for the