Comparison of low power and high power holmium YAG laser settings in flexible ureteroscopy

High-frequency in laser lithotripsy: do we truly know what it means?

INTRODUCTION AND OBJECTIVE

High frequency (HF) in laser lithotripsy lacks a consistent definition, potentially impacting clinical outcomes and patient safety. This review aims to analyze available evidence on the definition of HF.

MATERIALS AND METHODS

A comprehensive literature search of MEDLINE, Scopus, and Cochrane databases identified English-language studies published up to November 2024. Those mentioning HF focused on Holmium:YAG (Ho:YAG), Thulium Fiber Laser (TFL), and pulsed Thulium:YAG (p-Tm:YAG) in ureteral and renal endoscopic procedures; in vitro experiments and reviews/editorials were also included. User manuals from high-power laser manufacturers, and data from artificial intelligence (AI) platforms were also analyzed.

RESULTS

From 1030 initial records, 857 studies were screened after duplicate removal, and 106 studies were ultimately included. Most articles came from Europe (46), followed by North America (37) and Asia (20). HF was poorly defined in 25 articles, distributed across Europe (11), North America (7), and Asia (7). Most studies evaluated Ho:YAG (N = 80), followed by TFL (N = 13) and p-Tm:YAG (N = 1); the rest evaluated the first two lasers or all three. HF definitions varied, with European studies reporting ranges from 10 to 200 Hz, North American studies from 10 to 120 Hz, and Asian studies from 10 to 200 Hz. On average, HF ranged from 40 to 50 Hz. Among manufacturers, only four out of eight provided HF definitions in pre-setting/starting guidelines. AI platforms defined HF as 15-100 Hz for Ho:YAG, 50-2000 Hz for TFL, and 20-500 Hz for p-Tm:YAG.

CONCLUSIONS

There is no consensus on HF definitions in laser lithotripsy, with limited manufacturer guidelines and overly broad AI-defined ranges. Standardized terminology is essential. We propose defining HF as > 30 Hz for renal and > 15 Hz for ureteral procedures. Based on the available evidence, the use of HF settings does not appear to be necessary for dusting or popcorning techniques with current technologies.

Prospective evaluation of efficacy, safety, cumulative laser energy, and stone-free rates in the post-market SOLTIVE™ SuperPulsed laser system registry: insights from team of worldwide endourological researchers' (T.O.W.E.R.) research consortium

The Thulium fiber laser (TFL) is a relatively new tool for endoscopic laser lithotripsy. The Endourological Society's T.O.W.E.R. registry sought to evaluate the stone-free rate (SFR) at 3 months following URS. A subset of the study sought to determine the association between cumulative TFL energy and SFRs. 423 patients with planned ureteroscopic lithotripsy using TFL (SOLTIVE™, Gyrus ACMI, Inc. d/b/a Olympus Surgical Technologies America) were prospectively enrolled between December 2020 and May 2023 at nine international sites. Baseline clinical characteristics and SFR data for kidney and ureteral stones were separately analyzed according to quartile cumulative TFL energy ranges. Median patient age was 58.0 (IQR: 44-67) years and maximal stone diameters were 9.9 (IQR: 7-12.9) mm and 7.4 (IQR 6.1-9.4) mm for kidney and ureteral stones, respectively. Overall SFR (no fragments) for renal and ureteral stones were 73.0% and 85.7% at 3-months. Cumulative energy levels were divided into quartiles and lower SFRs were observed with the highest quartile for kidney stones (p = 0.001), but not in ureteral stones. This correlated with kidney stone size as larger stones required more energy. The rate of adverse events related to the procedure was 1.9% (8/423). Higher stone burdens had lower stone free rates and required more cumulative laser energy. The TFL is effective in endoscopic lithotripsy. This post-marketing survey demonstrates that TFL is a safe and effective tool for endoscopic laser lithotripsy.

Comparing Thulium Fiber Versus High-Power Holmium Laser Lithotripsy Combined with the Flexible and Navigable Suction Access Sheath in Flexible Ureteroscopy for Kidney Stone Disease: A Propensity Score Matched Analysis by the Global FANS Collaborative Group

Objective: We aim to evaluate stone-free rate (SFR) and complications after flexible ureteroscopy (F-URS) for kidney stones, using a flexible and navigable suction ureteral access sheath (FANS), comparing thulium fiber laser (TFL) and high-power holmium:yttrium-aluminum-garnet laser (HPHL). Methods: Data from adults who underwent F-URS in 15 centers were prospectively analyzed (August 2023-January 2024). Exclusion criteria were ureteral stones, concomitant bilateral procedures, and renal abnormalities. One-to-one propensity score matching for age, gender, stone location, stone volume, and Hounsfield unit was performed. SFR was assessed using computed tomography scan within 30 days and defined as zero fragments. Data are presented as median (25th-75th quartiles). Multivariable logistic regression was performed to evaluate predictors of SFR. Results: Of included patients, HPHL was used in 114 patients and TFL in 181 patients. After matching, 96 patients from each group with similar baseline characteristics were included. There was no difference between the groups regarding the use of disposable scopes, lithotripsy mode, and ureteroscopy, lasing and total surgical time. There was no case of sepsis, and blood transfusion was necessary for only one patient in the HPHL group. The incidence of transient fever was similar (3.4% in HPHL vs 3.8% in TFL group). Postoperative day 1 loin pain did not differ significantly. Postoperative stay did not differ significantly [1 [0, 2] in HPHL vs 1 [0, 1] days in TFL group, p = 0.12]. Thirty-day SFR was similar (52.1% for HL vs 64.6% for TFL group, p = 0.11). At multivariable analysis, the use of TFL (odds ratio 1.95, 95% confidence interval 1.01-3.82) was significantly associated with higher odds of being stone-free. Conclusions: Both lasers are safe and efficacious and can be suitably used for F-URS with FANS with high SFR and minimal complications.

High-power versus low-power laser settings during endoscopic stone disease management: a systematic review from the EAU endourology section

PURPOSE

Optimal laser settings during endoscopic stone disease management still represents a debatable issue. The aim of this systematic review is to summarize all existing evidence regarding the comparison of high-power (HP) versus low-power (LP) laser settings during different endoscopic lithotripsy procedures.

METHODS

PubMed, Scopus and Cochrane databases were systematically screened, based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) Guidelines. All endoscopic laser lithotripsy surgical approaches were included, including ureteroscopy (URS), retrograde intrarenal surgery (RIRS), percutaneous nephrolithotomy (PCNL) and transurethral lithotripsy for bladder stones. Pediatric patients were also included.

RESULTS

In total, 10 studies met the inclusion criteria and were included in final qualitative synthesis. In most studies total operative time (OT) was shorter for the HP group. Mean fragmentation time was homogenously significantly shorter in the HP group. Stone-free rates (SFR) ranged from 59.0% to 100% for the LP group and from 78.9% to 100% for the HP group. Total complication rates were higher for the LP group in six studies, equivalent between the two groups in one study and higher in the HP group in one study.

CONCLUSION

HP laser lithotripsy is a safe and efficient approach for URS, RIRS, PCNL and cystolithotripsy. HP laser settings were associated with significantly shorter total operative time, while some studies reported also better SFR in the HP groups. The implementation of more Randomized Controlled Trials comparing HP and LP laser lithotripsy in different stone settings is of outmost importance, so that better conclusions can be drawn.

Laser Ablation Efficiency, Laser Ablation Speed, and Laser Energy Consumption During Lithotripsy: What Are They and How Are They Defined? A Systematic Review and Proposal for a Standardized Terminology

CONTEXT

Laser performance for lithotripsy is currently reported using units of measurement such as J/mm3, mm3/J, mm3/s, s/mm3, and mm3/min. However, there are no current standardized definitions or terminology for these metrics. This may lead to confusion when assessing and comparing different laser systems.

OBJECTIVE

The primary objective was to summarize outcome values and corresponding terminology from studies on laser lithotripsy performance using stone volume in relation to time or energy. The secondary objective was to propose a standardized terminology for reporting laser performance metrics.

EVIDENCE ACQUISITION

A systematic review of the literature was conducted using the search string ("j*/mm3" OR "mm3/j*" OR "mm3/s*" OR "s*/mm3" OR "mm3/min*" OR "min*/mm3" AND "lithotripsy") on Scopus, Web of Science, Embase, and PubMed databases. Study selection, data extraction, and quality assessment were performed independently by two authors.

EVIDENCE SYNTHESIS

A total of 28 studies were included, covering holmium:yttrium-aluminum-garnet (Ho:YAG), MOSES, and thulium fiber laser (TFL) technologies. Laser energy consumption values reported for the studies ranged from 2.0 - 43.5 J/mm3in vitro and from 2.7 - 47.8 J/mm3in vivo, translating to laser ablation efficiency of 0.023 - 0.500 mm3/J and 0.021 - 0.370 mm3/J, respectively. Laser ablation speeds ranged from 0.3 - 8.5 mm3/s in vivo, translating to lasing time consumption of 0.12 - 3.33 s/mm3. Laser efficacy ranged from 4.35 - 51.7 mm3/min in vivo. There was high heterogeneity for the terminology used to describe laser performance for the same metrics.

CONCLUSIONS

The range of laser performance metric values relating stone volume to energy or time is wide, with corresponding differing terminology. We propose a standardized terminology for future studies on laser lithotripsy, including laser ablation efficiency (mm3/J), laser ablation speed (mm3/s), and laser energy consumption (J/mm3). Laser efficacy (mm3/min) is proposed as a broader term that is based on the total operative time, encompassing the whole technique using the laser.

PATIENT SUMMARY

We reviewed studies to identify the units and terms used for laser performance when treating urinary stones. The review revealed a wide range of differing units, outcomes, and terms. Therefore, we propose a standardized terminology for future studies on laser stone treatment.

Comparison of conventional (basketing + dusting) and Moses (pop-dusting) holmium lasers during flexible ureteroscopy in the treatment of renal stones between 2 and 3 cm: a randomized clinical trial

To investigate the feasibility of conventional (basketing + dusting) and Moses (pop-dusting) holmium lasers during flexible ureteroscopy (FURS) in the treatment of 2-3 cm renal calculi and to compare the efficiency and safety of the two methods, a total of 230 patients with 2-3 cm kidney stones who underwent FURS were randomly divided into the conventional group and the Moses group. The mode of lithotripsy in the conventional group was fragmentation and dusting. The mode of lithotripsy in the Moses group was dusting and pop-dusting. Clinical and perioperative variables and complications were compared between the two cohorts. Multivariate analyses of factors contributing to the stone-free rate (SFR) and operation time were performed. No statistically significant differences were found in the demographics, renal stone-related data, SFR, or complications between the cohorts. The laser energy was higher in the Moses cohort than in the conventional cohort (119.3 ± 15.2 vs. 92.8 ± 15.1 kJ; P < 0.001), and the operation time was shorter in the Moses cohort than in the conventional cohort (99.5 ± 18.9 vs. 105.3 ± 13.7 min; P = 0.009). When there was isolated stone, the operation time was shorter in the Moses cohort than in the conventional cohort (99.6 ± 17.5 vs. 111.4 ± 10.7 min; P < 0.001), while there was no significant difference between the two cohorts when there were multiple stones (99.5 ± 20 vs. 101.2 ± 14 min; P = 0.415). Multivariate analyses found that an increase in stone volume can decrease the SFR and prolong the operation time, and use of a Moses laser can shorten the operation time. Both holmium laser modes during FURS can effectively treat 2-3 cm renal calculi. The Moses mode is recommended as the first choice for the treatment of isolated 2-3 cm renal stones. When treating multiple stones, the efficiency of these two laser modalities is the same. TRIAL REGISTRATION: ChiCTR2200056091.

The Effect of High- and Low-power Holmium Laser Settings for Transurethral Lithotripsy in the Management of Adults with Ureteral Stone

Since there is insufficient evidence to determine the best treatment of transurethral laser lithotripsy (TLL) in ureteral stones, this study compared the effectiveness and safety of TLL using high-power (HP) (100 W) and low-power (LP) (20 W) laser settings. All patients with maximally sized ureteral stones who were planned for transurethral holmium laser lithotripsy were enrolled in this open study. One of the two laser setting groups-LP or HP-was allocated to each alternate patient. Using IBM SPSS Statistics 24, the treatment groups were compared for operating time, intraoperative and postoperative problems (up to 1 year), and rates of stone-free recovery. Welch tests were employed to compare continuous data, whereas Fisher's exact or Chi-square tests were used to assess categorical variables. At P < 0.05, statistical significance was established. A total of 207 individuals were included and preoperative data were comparable between the two groups. The HP group had a considerably greater ablation rate and a significantly shorter procedure duration (42.61 ± 11.74 min) than the LP group (78.56 ± 25.91 min) ( P = 0.025). The Overactive Bladder Symptom Score and International Prostate Symptom Score were considerably higher in the HP group than in the LP group. Treatment effectiveness was considerably impacted by the location of the ureteral stone, according to univariate and multivariate logistic regression models. A HP laser setting of up to 100 W greatly shortens the duration of the process for treating ureteral stones without raising the risk of problems.

Comparison of high and low pulse energy dusting protocols using holmium: YAG laser in flexible ureteroscopy for treatment of renal stones

Objectives

The management of renal stones, particularly those less than 2 cm in diameter, has changed with the development of endourological techniques, among which flexible ureteroscopy (FURS) using laser for lithotripsy has become a cornerstone. This study aims to compare the effectiveness of high pulse energy versus low pulse energy laser settings in renal stone dusting by Holmium YAG laser.

Patients and Methods

This prospective randomized study was conducted between September 2021 and November 2023 to compare the efficacy and safety of high energy versus low-energy pulse settings using a Holmium: YAG laser dusting of renal stones less than 2 cm in diameter. A total of 174 adult patients were included, divided equally into high- and low-pulse energy groups, based on the energy settings of the laser high energy (ranged from 1.2-2.5 Joules and frequency of 8 hz) and low energy (less than 0.5 Joules and frequency ≥ 15 hz) using the dusting ‎technique with non-touch non-stop approach. The study sought to evaluate the impact of these settings on stone fragmentation efficiency, operative time, laser energy consumption, and postoperative outcomes, including stone-free rates and complications.

Results

The study involved 174 patients who underwent renal stone lithotripsy and showed that using high pulse energy laser dusting settings significantly reduced operative times and more rapid dusting compared to low pulse energy settings, without affecting the stone-free rate. The study observed no significant differences in stone size or location between both groups. Minor postoperative complications were similar between both groups, indicating high pulse energy settings for lithotripsy dusting.

Conclusion

The efficacy of high pulse energy dusting in enhancing stone removal during surgery, potentially reducing operative time. Further validation through larger-scale studies is needed to solidify these findings. This technique presents a promising solution, particularly in regions with limited resources where acquiring expensive laser equipment is challenging.

Flexible ureteroscopic treatment of kidney stones: How do the new laser systems change our concepts?

Objective

Flexible ureteroscopy (fURS) has become a widely accepted and effective technique for treating kidney stones. With the development of new laser systems, the fURS approach has evolved significantly. This literature review aims to examine the current state of knowledge on fURS treatment of kidney stones, with a particular focus on the impact of the latest laser technologies on clinical outcomes and patient safety.

Methods

We conducted a search of the PubMed/PMC, Web of Science Core Collection, Scopus, Embase (Ovid), and Cochrane Databases for all randomized controlled trial articles on laser lithotripsy in September 2023 without time restriction.

Results

We found a total of 22 relevant pieces of literature. Holmium laser has been used for intracavitary laser lithotripsy for nearly 30 years and has become the golden standard for the treatment of urinary stones. However, the existing holmium laser cannot completely powder the stone, and the retropulsion of the stone after the laser emission and the thermal damage to the tissue have caused many problems for clinicians. The introduction of thulium fiber laser and Moses technology brings highly efficient dusting lithotripsy effect through laser innovation, limiting pulse energy and broadening pulse frequency.

Conclusion

While the holmium:yttrium-aluminum-garnet laser remains the primary choice for endoscopic laser lithotripsy, recent technological advancements hint at a potential new gold standard. Parameter range, retropulsion effect, laser fiber adaptability, and overall system performance demand comprehensive attention. The ablation efficacy of high-pulse-frequency devices relies on precise targeting, which may pose practical challenges.

Ho:YAG laser and dusting-high power vs low power: there is no difference

The introduction of the Ho:YAG laser 3 decades ago revolutionized the endoscopic treatment of urolithiasis. Since then, a variety of innovations have continued to evolve these devices, including the development of high-power lasers capable of high-frequency lithotripsy. The clinical utility of high-frequency lithotripsy, however, has not necessarily lived up to the potential suggested by in vitro studies. A review of the relevant literature, confirming strong similarities between the outcomes associated with high and lower power laser lithotripsy, follows.

Multicentric evaluation of high and low power lasers on RIRS success using propensity score analysis

In this study, we aimed to evaluate the effect of HPL on different parameters by different centers and urologists. While doing this, we evaluated different parameters by comparing HPL(High Power laser) and LPL(Low-power laser). This is an observational, retrospective, comparative, multicentric study of prospectively organised database. A total of 217 patients who underwent RIRS for kidney stones smaller than 2 cm in three different centers were included in the study. The patients were divided into two groups; LPL used (Group1, n:121 patients) and HPL used (Group2, n:96). Propensity score matching was done in the data analysis part. After matching, a total of 192 patients, 96 patients in both groups, were evaluated. There was no difference between the groups regarding age, gender, stone side, and stone location. The stone-free rate on the first day was 80.3% in Group 1, it was 78.1% in Group 2 (p = 0.9). In the third month, it was 90.7% in Group 1 and 87.5% in Group 2 (p:0.7).Hospitalization duration was significantly higher in Group 1. (2.35 ± 2.27 days vs. 1.42 ± 1.10 days; p < 0.001).The operation duration was 88.70 ± 29.72 min in Group1 and 66.17 ± 41.02 min in Group2 (p < 0.001). The fluoroscopy time (FT) was 90.73 ± 4.79 s in Group 1 and 50.78 ± 5.64 s in Group 2 (p < 0.001). Complications according to Clavien Classification, were similar between the groups(p > 0.05). According to our study similar SFR and complication rates were found with HPL and LPL. In addition, patients who used HPL had lower operation time, hospital stay, and fluoroscopy time than the LPL group. Although high-power lasers are expensive in terms of cost, they affect many parameters and strengthen the hand of urologists thanks to the wide energy and frequency range they offer.

Laser safety, warnings, and limits in retrograde intrarenal surgery

OBJECTIVE

To analyze the current information about laser safety in retrograde intrarenal surgery (RIRS), focusing on the two main laser technologies that we use in urology, the holmium:yttrium-aluminum-garnet (Ho:YAG) laser, and the thulium fiber laser (TFL).

METHODS

Narrative overview of the most relevant articles published in MEDLINE and Scopus databases about this subject.

RESULTS

TFL and Ho:YAG laser at similar settings (0.2 J/40 Hz) have similar volume-averaged temperature increase and the average heating rate increase proportionally to laser power, especially when high frequencies are used. Recent preclinical data, comparing both laser technologies at different laser settings, agreed that when the delivered energy increases in expenses of higher frequencies, the thermal damage increases too. Higher frequencies, despite of the rise of temperature in the irrigation medium, can cause accidental thermal lasering lesions.

CONCLUSION

The use of low frequency settings and a proper irrigation is critical to avoid thermal injury in endoscopic laser lithotripsy. In addition, the use of laser safety eyeglasses is recommended in Ho:YAG and TFL ELL.

Pulsed Thulium:YAG laser - What is the lithotripsy ablation efficiency for stone dust from human urinary stones? Results from an in vitro PEARLS study

BACKGROUND

The novel pulsed thulium:yttrium-aluminum-garnet (p-Tm:YAG) laser was recently introduced. Current studies present promising p-Tm:YAG ablation efficiency, although all are based on non-human stone models or with unknown stone composition. The present study aimed to evaluate p-Tm:YAG ablation efficiency for stone dust from human urinary stones of known compositions.

METHODS

Calcium oxalate monohydrate (COM) and uric acid (UA) stones were subjected to lithotripsy in vitro using a p-Tm:YAG laser generator (Thulio®, Dornier MedTech GmbH, Germany). 200 J was applied at 0.1 J × 100 Hz, 0.4 J × 25 Hz or 2.0 J × 5 Hz (average 10W). Ablated stone dust mass was calculated from weight difference between pre-lithotripsy stone and post-lithotripsy fragments > 250 µm. Estimated ablated volume was calculated using prior known stone densities (COM: 2.04 mg/mm3, UA: 1.55 mg/mm3).

RESULTS

Mean ablation mass efficiency was 0.04, 0.06, 0.07 mg/J (COM) and 0.04, 0.05, 0.06 mg/J (UA) for each laser setting, respectively. This translated to 0.021, 0.029, 0.034 mm3/J (COM) and 0.026, 0.030, 0.039 mm3/J (UA). Mean energy consumption was 26, 18, 17 J/mg (COM) and 32, 23, 17 J/mg (UA). This translated to 53, 37, 34 J/mm3 (COM) and 50, 36, 26 J/mm3 (UA). There were no statistically significant differences for laser settings or stone types (all p > 0.05).

CONCLUSION

To our knowledge, this is the first study showing ablation efficiency of the p-Tm:YAG laser for stone dust from human urinary stones of known compositions. The p-Tm:YAG seems to ablate COM and UA equally well, with no statistically significant differences between differing laser settings.

New Technologies in Endourology and Laser Lithotripsy: The Need for Evidence in Comprehensive Clinical Settings

Flexible ureteroscopy (fURS) with laser lithotripsy is currently the gold standard surgical treatment for ureteral and kidney stones with a maximum diameter of 2 cm [...].

Ureteroscopy and lasertripsy with pop dusting using high power holmium laser for large urinary stones > 15 mm: 6.5-year prospective outcomes from a high-volume stone center

INTRODUCTION

Ureteroscopy and stone lasertripsy (URSL) is a recognized technique for treatment of urinary tract stones. Holmium:Yag laser has been successfully used for this purpose for the last two decades. More lately, pulse modulation with Moses technology and high power lasers have been introduced with the result of faster and more efficient stone lasertripsy. Pop dusting is a two-stage combined treatment using a long pulse Ho:YAG laser, initially in contact mode with the stone 'dusting' (0.2-0.5 J/40-50 Hz) followed by non-contact mode 'pop-dusting' (0.5-0.7 J/20-50 Hz). We wanted to look at the outcomes of lasertripsy for renal and ureteric stones using a high-power laser machine.

METHODS

Over a period of 6.5 years (January 2016-May 2022), we prospectively collected data for patients undergoing URSL for stones larger than 15 mm treated using high power Ho:YAG laser (60W Moses or 100W laser). Patient parameters, stone demographics and outcomes of URSL were analyzed.

RESULTS

A total of 201 patients, underwent URSL for large urinary stones. In 136 patients (61.6%) stones were multiple and the mean single and cumulative stone size was 18 mm and 22.4 mm respectively. A pre- and post-operative stent was placed in 92 (41.4%) and 169 (76%) respectively. The initial and final stone free rate (SFR) were 84.5% and 94% respectively and 10% patients underwent additional procedure to achieve stone free status. 7 (3.9%) complications were recorded, all related to UTI/sepsis, with 6 Clavien II and 1 Clavien IVa complication.

CONCLUSION

Dusting and pop-dusting has shown to be successful and safe with the ability to treat large, bilateral or multiple stones with low retreatment and complication rates.

Moses and Moses 2.0 for Laser Lithotripsy: Expectations vs. Reality

Moses technology was born with the aim of controlling the Moses effect present in every single Ho:YAG laser lithotripsy. The capacity to divide the energy pulse into two sub-pulses gained popularity due to the fact that most of the energy would be delivered in the second pulse. However, is this pulse modulation technique really better for endocorporeal laser lithoripsy? A review of the literature was performed and all relevant clinical trials of Moses 1.0 and 2.0, as well as the lab studies of Moses 2.0 carried out up to June 2022 were selected. The search came back with 11 clinical experiences (10 full-text clinical trials and one peer-reviewed abstract) with Moses 1.0 and Moses 2.0, and three laboratory studies (peer-reviewed abstracts) with Moses 2.0 only. The clinical experiences confirmed that the MT (1.0) has a shorter lasing time but lower laser efficacy, because it consumes more J/mm³ when compared with the LP Ho:YAG laser (35 W). This gain in lasing time did not provide enough savings for the medical center. Additionally, in most comparative studies of MT (1.0) vs. the regular mode of the HP Ho:YAG laser, the MT did not have a significant different lasing time, operative time or stone-free rate. Clinical trials with Moses 2.0 are lacking. From what has been published until now, the use of higher frequencies (up to 120 Hz) consumes more total energy and J/mm³ than Moses 1.0 for similar stone-free rates. Given the current evidence that we have, there are no high-quality studies that support the use of HP Ho:YAG lasers with MT over other lasers, such as LP Ho:YAG lasers or TFL lasers.