1064-nm Wavelength Research Articles

Histologic Evaluation of Effect of Three Wavelengths of Diode Laser on Human Gingival Margins.

Introduction: Available evidence suggests that the response of the intervened tissue is directly linked to the effects generated by the cutting instrument used. To determine the histological findings in gingival tissue margins excised through gingivectomies performed using 450 nm, 940 nm, and 980 nm diode lasers. The present study aimed to determine the histological findings in gingival tissue margins excised through gingivectomies performed using 450 nm, 940 nm, and 980 nm diode lasers. Methods: Gingival tissue samples were collected from 30 patients who had undergone gingivectomy procedures. Each study group comprised 10 patients who willingly provided their samples after providing informed consent. The visualization of histological findings was facilitated through Hematoxylin-Eosin staining. Additionally, variables related to pain and hemostasis were assessed during the intraoperative period. Results: The incision quality was categorized as irregular across all three wavelengths. Histological examination of the epithelial tissue revealed the absence of carbonization and the preservation of cell morphology in over 50% of the resection margin in samples obtained with the 450 nm and 940 nm wavelengths. In the connective tissue, observations included carbonization, collagen coagulation, and basophilia, with the 980 nm wavelength demonstrating the highest percentage of samples displaying collagen coagulation in more than 50% of the resection margin. Conversely, the 450 nm wavelength exhibited the highest degree of preservation of the fibroblast structure. Conclusion: Based on a comprehensive analysis of the study results, it can be inferred that the 450nm and 940nm wavelength lasers tend to produce less thermal damage and better cell preservation when compared to the 980nm wavelength.

High-energy picosecond pulses with a single spatial mode from a passively mode-locked, broad-area semiconductor laser

We present a mode-locked semiconductor laser oscillator that emits few picosecond pulses (5-8ps at a repetition rate of 379MHz and wavelength of 1064nm) with record peak power (112W) and pulse energy (0.5nJ) directly out of the oscillator (with no amplifier). To achieve this high power performance we employ a high-current broad-area, spatially multi-mode diode amplifier (0.3×5mm), placed in an external cavity that enforces oscillation in a single spatial mode. Consequently, the brightness of the beam is near-ideal (M2 = 1.3). Mode locking is achieved by dividing the large diode chip (edge emitter) into two sections with independent electrical control: one large section for gain and another small section for a saturable absorber. Precise tuning of the reverse voltage on the absorber section allows to tune the saturation level and recovery time of the absorber, providing a convenient knob to optimize the mode-locking performance for various cavity conditions.

Trapping and Imaging Single Dysprosium Atoms in Optical Tweezer Arrays.

We report the preparation and observation of single atoms of dysprosium in arrays of optical tweezers with a wavelength of 532nm, imaged on the intercombination line at 626nm. We use the anisotropic light shift specific to lanthanides and in particular a large difference in tensor and vector polarizabilities between the ground and excited states to tune the differential light shift and produce tweezers in near-magic or magic polarization. This allows us to find a regime where single atoms can be trapped and imaged. Using the tweezer array toolbox to manipulate lanthanides will open new research directions for quantum physics studies by taking advantage of their rich spectrum, large spin, and magnetic dipole moment.

A multi-physics simulation study on material optimization for fabrication of 532-nm operating wavelength photonic crystal

A multi-physics simulation study on material optimization for fabrication of 532-nm operating wavelength photonic crystal

Preparation of Copper Nanoparticles Using Different Media by Pulsed Laser Ablation and Study of Their Physical Properties

In this study, copper nanoparticles (CuNPs) were prepared using the pulsed laser ablation method, and the study was conducted under the effect of changing the liquid medium (ethanol, deionized water, distilled water) with a number of pulses (700p/s) and using a (Q-switched Nd-YAG) laser. At a wavelength of 532nm and an energy of 100mJ, the results of the samples prepared in a medium (ethanol, distilled water, deionized water) showed the average radii of CuNPs (58.3, 61.6, 46.1 nm, respectively) with a spherical shape. The spectrum of copper at (3250 to 3550 ) is mainly due to the expansion of (O-H) the clear hydroxyl group and under the conditions of the three solvents (ethanol, deionized water, distilled water). The XRD results showed that the CuO nanoparticles are free of impurities and crystallized High and the crystallite size was calculated at 2theta (20.094, 19.949, 38.045) nm for the samples in (deionized water, distilled water, and ethanol), respectively.

Malondialdehyde Levels in Blood Serum of Wistar Rats After Exposure to Panoramic and Cephalometric Radiation (Experimental Laboratory Research)

Background: Panoramic and cephalometric radiographs are used in dentistry, especially orthodontics, sometimes accompanied by periapical examination. Behind the benefits of using radiography, there are disadvantages for the body, which cause changes in the normal cell arrangement, detected by increased levels of Malondialdehyde (MDA) in blood serum. Purpose: This study was to determine differences in blood serum MDA levels of wistar rats a few days after exposure to panoramic and cephalometric radiation. Materials and Methods: This study used 35 male Wistar strain Rattus norvegicus, weighing 200-250 grams, aged 3-4 months, in good physical health. Animals are divided into five groups. Group K did not do fixation and was not given radiation exposure; groups K1, K2, K3, and K4 underwent fixation were given radiation exposure, MDA levels were measured, groups K1, K2, K3, K4, day 1, 3, 5 and 7 after radiation exposure. MDA levels were measured by the thiobarbituric acid method using a spectrophotometer with a wavelength of 532nm. Results: There was a significant increase MDA levels in K1 (45.2704 + 2.08684). Significant decrease of MDA levels occurred in K2 (34.7747 + 7.90103), K3 (18.1266 + 5.33797), and K4 (12.0494 + 1.91399). Conclusion: There was an increase in MDA levels after radiation exposure, and MDA decreased significantly from the third to the seventh day after radiation exposure. However, MDA levels have not returned to normal.

Erbium-ytterbium containing upconversion mesoporous bioactive glass microspheres for tissue engineering: luminescence monitoring of biomineralization and drug release.

The development of functional biomaterials with real-time monitoring of mineralization processes, drug release and biodistribution has potential applications but remains an unsolved challenge. Herein, erbium- and ytterbium- containing mesoporous bioactive glass microspheres (MBGs:Er/Yb) with blue and red emission at an excitation wavelength of 980nm were synthesized by a sol-gel combined with organic template method. As the concentration of Yb3+ ions gradually increases, the emission intensity of the MBGs:Er/Yb exhibits a clear concentration quenching effect. Combined with in vitro bioactivity tests, the optimal molar ratio of Er3+/Yb3+ was determined to be 4:3. Therefore, MBGs:4Er/3Yb was selected for in vitro biomineralization and drug release monitoring. The results of biomineralization monitoring show that the upconversion luminescence intensity is closely related to the degree of biomineralization. The upconversion luminescence intensity of MBGs:4Er/3Yb is quenched with the increase of the degree of biomineralization. The degree of luminescence quenching during biomineralization can be semiquantized. Drug release monitoring experiments showed that the anticancer drug doxorubicin hydrochloride (DOX) was successfully loaded into MBGs:4Er/3Yb and selectively quenched the green emission. When DOX was released, the green emission recovered stably, and It/I0 increased gradually. Moreover, there was a linear relationship between It/I0 and cumulative drug release, indicating that DOX-MBGs:4Er/3Yb is highly sensitive to DOX release, and monitoring the It/I0 values of DOX-MBGs:4Er/3Yb can achieve real-time tracking of the DOX release process to a certain extent. In conclusion, MBGs:4Er/3Yb has potential application as an upconversion luminescence biomonitoring material in the field of bone tissue engineering. STATEMENT OF SIGNIFICANCE: Mesoporous bioactive glasses have great potential for applications in bone tissue repair due to their excellent biological properties, but the effective information of the repair process cannot be grasped in a timely manner. Therefore, real-time monitoring of mineralization and drug release processes will be beneficial to obtain the degree of healing and optimize the amount and distribution of drugs to improve targeted therapeutic effects. For biomaterials, in vitro biological properties determine their biological properties in vivo, where the environment is more complex and diverse, and thus in vitro biomonitoring is particularly crucial. The organic combination of physical properties and biological properties will also provide a feasible idea for the development of biomaterials.

High-resolution 3D nanoprinting based on two-step absorption via an integrated fiber-coupled laser diode.

Three-dimensional (3D) laser nanoprinting with high resolution and low cost is highly desirable for fabricating arbitrary 3D structures with fine feature size. In this work, we use a 405-nm integrated fiber-coupled continuous wave (cw) laser diode to establish an easy-to-build 3D nanoprinting system based on two-step absorption. Two-dimensional (2D) gratings with a sub-150-nm period and 3D woodpile nanostructures with a lateral period of 350 nm have been printed at a low speed. At a faster scan velocity of 1000 µm/s, 2D gratings with sub-200-nm resolution and sub-50-nm linewidth can still be fabricated with laser power less than 1 mW. The two-step absorption of the used benzil initiator enables us to use a second cw laser with 532-nm wavelength to enhance the polymerization with sub-100-nm feature size when starting with insufficient 405-nm laser power, which possess the potential to find applications in high-speed high-resolution parallel-writing and in situ manipulation.

Hyper Rayleigh scattering from DNA nucleotides in aqueous solution.

Nucleotides are organic compounds consisting of a phosphate group, a nitrogenous base, namely adenine (A), thymine (T), cytosine (C), or guanine (G), and a sugar, here deoxyribose. The magnitude of the first hyperpolarizability β of these four DNA nucleotides was determined in aqueous solution with the nonlinear optical technique of hyper rayleigh scattering under non resonant conditions at a fundamental wavelength of 800nm. The smallest value is found to be 1.67 ± 0.15 × 10-30 esu for thymidine-5'-monophosphate and the highest is 1.76 ± 0.16 × 10-30 esu for 2'-guanosine-5'-monophosphate. Polarization resolved studies were also performed to question the symmetry of the first hyperpolarizability tensor and access the ratio of some elements of the first hyperpolarizability tensor. These experimental results were then compared to the theoretical values of these first hyperpolarizabilities obtained with the density functional theory at the level of the PCM-B3LYP/6-31G+(d) basis and taking into account the solvent.

Metal-Free Hybrid Energetic Composites Based on Donor-Acceptor π-Conjugated Organic Energetic Catalysts with Enlightening the Laser Ignition Performance of Multi-Scale Ammonium Perchlorate.

Photosensitive materials, such as energetic complexes, usually have high sensitivity and cause heavy-metal pollution, whereas others, like carbon black and dye, do not contain energy, which affects energy output and mechanical properties. In this work, donor-acceptor π-conjugated energetic catalysts, denoted as D-n, are designed and synthesized. Nonmetallic hybrid energetic composites are prepared by assembling the as-synthesized catalysts into multiscale ammonium perchlorate (AP). Composites containing catalysts and APs can be successfully ignited without the involvement of metals. The new ignition mechanism is further analyzed using experimental and theoretical analyses such as UV-vis-near-infrared (NIR) spectra, electron-spin resonance spectroscopy, and energy-gap analysis. The shortest ignition delay time is 56ms under the experimental condition of a NIR wavelength of 1064nm and a laser power of 10W. At the voltage of 1kV and the electric field of 500V mm-1 , the laser-ignition delay time of D-2/AP hybrid composite decreases from 56 to 35ms because D-2 also exhibits organic semiconductor-like properties. D-2/AP and D-12/AP can also be used to successfully laser ignite other common energetic materials. This study can guide the development of advanced metal-free laser-ignitable energetic composites to address challenges in the field of aerospace engineering.

Relocking and Locking Range Extension of Partially Locked AMLL Cavity Modes with Two Detuned RF Sinusoids

Actively mode-locked fiber ring lasers (AMLLs) with loss modulators are used to generate approximately 100ps pulses with 100MHz repetition. RF detuning around the fundamental frequency, f0, causes a loss in phase lock (unlocking) of cavity modes and partial mode locking. Multiple RF inputs are shown, theoretically, to relock and extend the locking range of cavity modes in a detuned partially mode-locked AMLL. A custom-built Yb3+-doped AMLL with f0=26MHz, and operating wavelength of 1064nm, was used to experimentally verify the theoretical predictions. Two RF sinusoidal signals with constant phase and equal amplitude resulted in an extension of the range by Xn=6.4kHz in addition to the range Rn=14.34kHz with single input for the mode n=10. An increase in locking range was also observed for higher modes. Pulsewidth reduction to approximately 205ps from about 2ns was also observed in the AMLL.

Trends in outcomes associated with the use of Auryon atherectomy system in a real-world setting

BackgroundWhile endovascular approaches are considered first line treatment for stenosis or occlusion of the lower limb arteries, major dissections and embolic events remain procedural risks. Newer technologies are needed which limit these complications while achieving desired clinical outcomes. MethodsThe Auryon atherectomy system (AngioDynamics) consists of a 355-nm wavelength solid-state Nd:YAG short pulse laser combined with dedicated optical catheters. This single-center, retrospective chart review assessed the safety and efficacy of this device in patients with PAD treated at our center between March and December 2020. ResultsA total of 55 patients were included. Mean age was 73.7 ± 9.3 years with 63.6 % of patients being males. Lesions were above the knee only for 16.4 % of patients, below the knee only for 3.6 %, and both above and below the knee for 80.0 % of patients. One patient had in-stent restenosis. Chronic total occlusions and critical limb ischemia were present for 43.6 % of patients respectively. Procedural success, defined as <30 % residual stenosis without any complications, was achieved in 85.5 % of patients. Stenosis/re-occlusion occurred in 25.5 % of patients at a mean of 168.9 ± 73.4 days with resultant target lesion revascularization (TLR) at 218.3 ± 92.4 days. Four patients underwent minor amputations. No patients experienced procedure-related complications. One patient died unrelated to the procedure. ConclusionThe Auryon laser system was shown to be safe and effective in this real-world patient population with no procedural adverse events or deaths and improvements in patient outcomes.

MP79-07 EFFECT OF NEAR-INFRARED LASER TREATMENT ON IMPROVING ERECTILE FUNCTION IN RATS WITH DIABETES MELLITUS

You have accessJournal of UrologyCME1 Apr 2023MP79-07 EFFECT OF NEAR-INFRARED LASER TREATMENT ON IMPROVING ERECTILE FUNCTION IN RATS WITH DIABETES MELLITUS Lin Yang, Guoxiong Liu, Dali Jiang, Guiting Lin, Hengtong Fan, Zejun Ren, Bing Yang, Liyue Mu, Tom F Lue, and Dalin He Lin YangLin Yang More articles by this author , Guoxiong LiuGuoxiong Liu More articles by this author , Dali JiangDali Jiang More articles by this author , Guiting LinGuiting Lin More articles by this author , Hengtong FanHengtong Fan More articles by this author , Zejun RenZejun Ren More articles by this author , Bing YangBing Yang More articles by this author , Liyue MuLiyue Mu More articles by this author , Tom F LueTom F Lue More articles by this author , and Dalin HeDalin He More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000003356.07AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Diabetes mellitus induced erectile dysfunction (DMED) is difficult to treat. The oxidative stress (OS) created by DM is a major cause of injuries to the corpus cavernosum (CC), thereby resulting in ED. Near-infrared (NIR) laser has already been shown to be effective in treating multiple brain disorders due to its anti-OS effect. In this study we want to investigate whether an NIR laser improves the erectile function of DMED rats through its anti-OS effect. METHODS: Knowing its advantage of reasonable deep tissue penetration and good photo activation on mitochondria, a NIR laser with wavelength of 808nm was used in the experiment. Since the internal and external CC was covered by different tissue layers, the laser penetration rates of the internal and external CC were measured separately. Different radiant exposure settings were applied: in the initial experiment, 40 male SD rats were randomly assigned to five groups, normal controls (NC), and STZ-induced DM rats that 10 weeks later received various radiant exposures (J/cm2) from the NIR laser (DM0J, DM1J, DM2J, and DM4J) in the subsequent 2 weeks. Erectile function was then assessed 1 week after NIR treatment. It was found the initial radiant-exposure setting was not optimal according to the Arndt–Schulz rule. We followed with a second experiment using a different radiant exposure setting. Forty male rats were randomly divided into five groups (NC, DM0J, DM4J, DM8J, and DM16J), and the NIR laser was again applied according the new setting and erectile function was assessed as in the first experiment. Histologic, biochemical analyses and proteomic were then conducted. RESULTS: Recovery of erectile function of varying degrees was observed in the NIR treatment groups, and radiant exposure of 4 J/cm2 achieved optimal results. The NIR4J group showed improvement in mitochondrial function and in morphology in DM rats, and it was found that OS levels were significantly reduced by NIR exposure. The tissue structure of the CC was also improved by NIR exposure. The proteomics analysis confirming multiple biologic processes had been changed by DM and NIR. CONCLUSIONS: NIR laser activated mitochondria, improved OS, repaired the damage to penile CC tissue structures caused by DM, and improved erectile function in DM rats. These results thus raise the possibility that human patients with DMED may respond to NIR therapy in a manner that parallels the responses we observed in animal study. Source of Funding: Key R&D Plan of Shaanxi Province (2022SF-531) © 2023 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 209Issue Supplement 4April 2023Page: e1143 Advertisement Copyright & Permissions© 2023 by American Urological Association Education and Research, Inc.MetricsAuthor Information Lin Yang More articles by this author Guoxiong Liu More articles by this author Dali Jiang More articles by this author Guiting Lin More articles by this author Hengtong Fan More articles by this author Zejun Ren More articles by this author Bing Yang More articles by this author Liyue Mu More articles by this author Tom F Lue More articles by this author Dalin He More articles by this author Expand All Advertisement PDF downloadLoading ...

Excision of a Chronic Inflammatory Mass Using Diode Lasers: A Case Report

Photobiomodulation (PBM), also known as low level laser therapy (LLLT) or cold laser therapy uses light energy to elicit biological responses from the cell and help regulate cell function. From a clinical point of view PBM offers dental practitioners a non-invasive treatment modality that can be used as an adjunct to the traditional therapies or as a therapeutic tool on its own. This is a case of surgical excision of a fluctuant mass using a scalpel and diode laser 980nm wavelength.

Effect of near-infrared laser treatment on improving erectile function in rats with diabetes mellitus.

Diabetes mellitus-induced erectile dysfunction is difficult to treat. The oxidative stress created by diabetes mellitus is a major cause of injuries to the corpus cavernosum, thereby resulting in erectile dysfunction. Near-infrared laser has already been shown to be effective in treating multiple brain disorders because of its antioxidative stress effect. To investigate whether a near-infrared laser improves the erectile function of diabetes mellitus-induced erectile dysfunction rats through its antioxidative stress effect. Knowing its advantage of reasonable deep tissue penetration and good photoactivation on mitochondria, a near-infrared laser with wavelength of 808nm was used in the experiment. Since the internal and external corpus cavernosum were covered by different tissue layers, the laser penetration rates of the internal and external corpus cavernosum were measured separately. Different radiant exposure settings were applied: in the initial experiment, 40 male Sprague-Dawley rats were randomly assigned to five groups, normal controls, and streptozotocin-induced diabetes mellitus rats that 10weeks later received various radiant exposures (J/cm2 ) from the near-infrared laser (DM0J(DM+NIR 0 J/cm2 ), DM1J, DM2J, and DM4J) in the subsequent 2weeks. Erectile function was then assessed 1week after near-infrared treatment. It was found that the initial radiant exposure setting was not optimal according to the Arndt-Schulz rule. We performed a second experiment using a different radiant exposure setting. Forty male rats were randomly divided into five groups (normal controls, DM0J, DM4J, DM8J, and DM16J), and the near-infrared laser was again applied according to the new setting, and erectile function was assessed as in the first experiment. Histologic, biochemical, and proteomic analyses were then conducted. Recovery of erectile function of varying degrees was observed in the near-infrared treatment groups, and radiant exposure of 4 J/cm2 achieved optimal results. The DM4J group showed improvement in mitochondrial function and morphology in diabetes mellitus rats, and it was found that oxidative stress levels were significantly reduced by near-infrared exposure. The tissue structure of the corpus cavernosum was also improved by near-infrared exposure. The proteomics analysis confirming multiple biologic processes were changed by diabetes mellitus and near-infrared. Near-infrared laser activated mitochondria, improved oxidative stress, repaired the damage to penile corpus cavernosum tissue structures caused by diabetes mellitus, and improved erectile function in diabetes mellitus rats. These results thus raise the possibility that human patients with diabetes mellitus-induced erectile dysfunction may respond to near-infrared therapy in a manner that parallels the responses we observed in animal study.

Design and calibration of a Mueller matrix microscope based on liquid crystal variable retarders

Polarization imaging techniques have achieved broad applications in areas such as material characterization, nano-scale measurement, and biomedical diagnosis. The Mueller matrix microscopy, as one of the polarization imaging techniques, can provide the most comprehensive polarization information of a sample, such as anisotropy and depolarization. However, the instrumentation of Mueller matrix microscopy is typically complex and the associated calibration process is usually difficult due to the presence of many polarization and imaging components. In this work, we present an easy-to-follow approach for the instrumentation of Mueller matrix microscopy, not from scratch, but by easily modifying a commercial microscope into a Mueller matrix microscope (MMM) based on liquid crystal variable retarders (LCVR). Optimal configurations have been generated by the genetic algorithm at wavelengths of 400-800 nm. An extended eigenvalue calibration method is proposed to accurately calibrate the polarization and imaging components of the modified instruments in a model-free approach. Experiments performed on standard samples at the wavelength of 532nm, such as a polarizer and a waveplate, have indicated the performances of the developed MMM with a measurement error of less than 0.01 and a mean standard deviation of around 0.0042.

Optimization for Ion Detection and Recognition From Laser-Generated Plasma Using SiC Detectors Connected in Time-of-Flight Acquisition

A silicon carbide (SiC) Schottky diode detector is employed to monitor the ion streams emitted from laser-generated plasmas and to obtain information on their kinetic energy using time-of-flight (TOF) measurements. The laser operates with nanosecond (ns) pulses, in the IR region at 1064-nm wavelength, uses single pulses with 200-mJ energy, and an intensity of about 10 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{10}$</tex-math> </inline-formula> W/cm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{2}$</tex-math> </inline-formula> . Plasmas are produced in a high vacuum by irradiation different targets as polymers, ceramics, and metals. The non equilibrium plasma, back emitted orthogonally to the target surface, accelerates ions at about 110 eV per charge state and has a temperature within 70 and 100 eV growing with the atomic number of the laser irradiated target. In this article, an optimization of ion detection is checked for SiC detectors through the TOF spectra, permitting the ion recognition and angular emission. A comparison with classical ion collectors (ICs) is also presented and discussed.

Lower eyelid blepharoplasty combined with ultrasound-guided percutaneous diode laser lipolysis: evaluating effectiveness with long-term outcome.

Laser lipolysis may be considered for selective removal of excess orbital fat via minimally invasive lower blepharoplasty. To control the energy delivery to a precise anatomic location while avoiding complications, ultrasound guidance can be utilized. Under local anesthesia, a diode laser probe (Belody, Minslab, Korea) was introduced percutaneously to the lower eyelid. The tip of the laser device and changes in orbital fat volume were carefully controlled with ultrasound imaging. A 1470-nm wavelength was used for orbital fat reduction (maximal energy 300J), and a 1064-nm wavelength was used to tighten the lower eyelid skin (maximal energy 200J). From March 2015 to December 2019, a total of 261 patients underwent ultrasound-guided diode laser lower blepharoplasty. The procedure took 17min on average. Total energy of 49J-510J (average = 228.31J) was delivered in 1470-nm wavelengths or 45-297J (average = 127.68J) was delivered in 1064-nm wavelengths. Most patients were very satisfied with their results. Fourteen patients experienced complications, including nine cases of transient hypesthesia (3.45%), and three skin thermal burns (1.15%). However, these complications were not observed after strict control of the energy delivery below 500J for each lower lid. Improvement in lower eyelid bags can be achieved using a minimally invasive approach in selected patients with ultrasound-guided laser lipolysis. It is a fast and safe procedure that can be performed in the outpatient setting.

Photoacoustic imaging of hidden dental caries using visible-light diode laser.

Hidden caries is a type of tooth decay that is difficult to identify through visual diagnosis because teeth with hidden caries appear normal on the tooth surface but are damaged underneath. A photoacoustic imaging system based on visible light using a diode laser with a wavelength of 532nm was developed to detect hidden caries in teeth. The results indicate that the average of acoustic intensity level for healthy teeth is -74.2±0.1dB, and the average of acoustic intensity range for teeth with hidden caries is -81.2±0.5dB. The intensity level for the caries area varies depending on the severity of caries. Based on the acoustic intensity level measured by the interaction of teeth with laser light, the photoacoustic imaging system in the study can accurately detect the presence of hidden caries and recognizethe difference between caries teeth and healthy teeth. This research can be developed into a prototype of a simple device that makes it easy to operate in dental practice.

Barium sulfate and pigment admixture for photoacoustic and x-ray contrast imaging of the gut.

X-ray imaging is frequently used for gastrointestinal imaging. Photoacoustic imaging (PAI) of the gastrointestinal tract is an emerging approach that has been demonstrated for preclinical imaging of small animals. A contrast agent active in both modalities could be useful for imaging applications. We aimed to develop a dual-modality contrast agent comprising an admixture of barium sulfate with pigments that absorb light in the second near-infrared region (NIR-II), for preclinical imaging with both x-ray and PAI modalities. Eleven different NIR-II dyes were evaluated after admixture with a 40% w/v barium sulfate mixture. The resulting NIR-II absorption in the soluble fraction and in the total mixture was characterized. Proof-of-principle imaging studies in mice were carried out. Pigments that produced more uniform suspensions were assessed further for photoacoustic contrast signal at a wavelength of 1064nm that corresponds to the output of the Nd:YAG laser used. Phantom imaging studies demonstrated that the pigment-barium sulfate mixture generated imaging contrast in both x-ray and PAI modalities. The optimal pigment selected for further study was a cyanine tetrafluoroborate salt. Ex-vivo and whole-body mouse imaging demonstrated that photoacoustic and x-ray contrast signals co-localized in the intestines for both imaging modalities. These data demonstrate that commercially-available NIR-II pigments can simply be admixed with barium sulfate to generate a dual-modality contrast agent appropriate for small animal gastrointestinal imaging.