In this work an irradiance and temperature controlled in-vitro system for conducting investigations in PDT and phototherapy is presented.
The development of new light sources has caused a considerable increase in research and application of several photodynamic (PDT) therapeutic methods, as well as other light-based therapeutic techniques. However, further work is needed to fully understand and elucidate the mechanisms as well as to increase the effectiveness of PDT. Nowadays, there are no commercial systems to perform automated light exposure experiments with cultured cells. Also, there are very few reports of similar photoirradiation systems.
The system is composed of 24 independent light-emitting diodes that can be used to irradiate separate wells in a microwell plate. The system includes a module to measure changes in temperature within each irradiated well without contact. The light sources are placed on a plate that can easily be changed in order to irradiate at different wavelengths. The performance of the system is fully controlled with a computer, and all the experimental data are properly recorded.
The design, construction, operation, and a full characterization of the system are presented.
A novel fully automated photoirradiation system has been developed. The system allows the design of the experiments in this area with precise dosimetry, temperature, and irradiation regime controls reducing manipulation of the samples and saving time.
Implantable Self-Powered Low-Level Laser Cure System for Mouse Embryonic Osteoblasts’ Proliferation and Differentiation.
Bone remodeling or orthodontic treatment is usually a long-term process. It is highly desirable to speed up the process for effective medical treatment. In this work, a self-powered low-level laser cure system for osteogenesis is developed using the power generated by the triboelectric nanogenerator. It is found that the system significantly accelerated the mouse embryonic osteoblasts’ proliferation and differentiation, which is essential for bone and tooth healing. The system is further demonstrated to be driven by living creature’s motions, such as human walking, or mouse’s breathing, suggesting its practical use in portable or implantable clinical cure for bone remodeling or orthodontic treatment.
[Diagnostic and therapeutic devices for patients with chronic intractable pain: preface and comments].
New diagnostic and therapeutic devices for patients with chronic intractable pain are used in Japan. The following articles describe topics of new diagnostic and therapeutic devices for patients with chronic intractable pain including thermography, functional MRI, device for the quantitative analysis of perception and pain sensation, epiduroscopy, device for phototherapy, Racz catheter and device for spinal cord stimulation (SCS).
[Light irradiator for various chronic pain].
Effects of light upon human tissue are divided into irreversible effects and reversible effects. Irreversible effects can be called as high level lasertherapy (HLLT), and reversible effects can be called as low level light therapy (LLLT). Light irradiators for chronic pain act under principle of LLLT.Laser diode, halogen lamp and xenon lamp are used as light sources for light irradiator for various chronic pain. These days, light emitting diode (LED) is used as light source for light irradiator for various kinds of pain. Light irradiators are now divided into portable light weight low power machine and heavy weight, high power machine. In the dental area Nd : YAG laser is using as HLLT tool. But, now there are many reports about Nd : YAG laserused as anesthetic machine. In these reports, topical anesthetic effects of Nd : YAG laser are immediate and with fewer side effects compared with topical anesthetic agents. These effects are explained as LLLT. Halogen lamp and xenon lamp type irradiators were also introduced. MEDILASER SOFT PULSE10, an laser diode type irradiator was withdrawn from the market.
Calculation of the dose of low-intensity laser radiation: the need or the harm?.
This study showed that it is highly undesirable to equip the devices for laser therapy with the dose-calculation function. In order to avoid mistakes, the operator should perform a strict sequence of actions as follows: to choose the needed wavelength and operating regime (the laser head block) of the LILR source, to set and measure the radiation power, the time and frequency of treatment, turn on the apparatus, control its operation and switch it off at the scheduled time. Meeting all these requirements eventually ensures obtaining a certain optimal dose density and guarantees that the entire procedure of laser irradiation is performed in a proper way. The equipment of the apparatus with the dose-calculation function is nothing more than a marketing ploy intended to earn extra money that apart from everything else creates additional problems for the customer.
[Usefulness and clinical application of phototherapy: preface and comments].
The following articles describe topics of phototherapy including low reactive laser therapy by diode laser device, semiconductor as a medium consisting of aluminum, gallium and arsenic, near infrared light irradiator using halogen lamp, and xenon light by high-intensity electrical stimulation of xenon gas. In addition, the applications of phototherapy in the clinical medicine such as rehabilitation, orthopedics and pain clinic are described. Phototherapy is a useful and safe method for pain relief.
New classification for single-system light treatment.
- Japan Medical Laser Laboratory, Shinanomachi, Tokyo, Japan.
BACKGROUND AND AIMS:
Although the use of the laser in medical applications has increased dramatically during the last three decades, it is significant that during the last few years non-laser light sources have gained prominence in photomedicine and photosurgery, particularly the use of light-emitting diodes (LEDs) and intense pulsed light (IPL). The author therefore believed it was important to devise a new classification of light/tissue interactions, and that the well-accepted acronym LLLT and HLLT should now stand for low level light therapy and for high level light treatment, since the ‘L’ in ‘laser‘, LED and IPL stands for ‘light’.
The author herein presents a classification, which is based on the level of reaction induced by the light incident on tissue, rather than being based on the system used to deliver the light energy. When the level of tissue reactivity to light of very low incident power and energy densities is well below the cells’ damage threshold, so that instead of being damaged the cells are directly activated by the low incident photon density, the changes in the irradiated tissue are photoactivative and reversible: the author hereafter refers to this group of reactions as low level light therapy (LLLT). When the level of tissue reactivity to light of very high incident power and energy densities is over the cells’ damage threshold, so that the cells are directly destroyed, the changes in the irradiated tissue are photodestructive and irreversible: the author hereafter refers to this group of reactions as high level light treatment (HLLT). For levels of tissue reaction intermediate to HLLT and LLLT, the author suggests the new term, mediumlevel light treatment (MLLT), as described in detail herein.
When the new classification system of light treatment (LT) is understood and used, the author feels this offers an accurate and simple method of classifying light/tissue reactions by the therapeutic reaction itself, rather than by the light source, laser, LED, IPL system or other, used to produce the reaction.
HLLT; LLLT; MLLT; light apple; light treatment; low level light therapy; new classification
Rev Bras Fisioter. 2010 Aug;14(4):303-308. Epub 2010 Sep 3.
Calibration of low-level laser therapy equipment.
[Article in Portuguese]
Fukuda TY, Jesus JF, Santos MG, Cazarini Junior C, Tanji MM, Plapler H.
Setor de Fisioterapia, Irmandade Santa Casa de Misericórdia de São Paulo, São Paulo, SP, Brasil.
BACKGROUND: Despite the increase in the use of low-level laser therapy (LLLT), there is still a lack of consensus in the literature regarding how often the equipment must be calibrated.
OBJECTIVE: To evaluate the real average power of LLLT devices in the Greater São Paulo area.
METHODS: For the evaluation, a LaserCheck power meter designed to calibrate continuous equipment was used. The power meter was programmed with data related to the laser’s wavelength to gauge the real average power being emitted. The LLLT devices were evaluated in two ways: first with the device cooled down and then with the device warmed up for 10 minutes. For each condition, three tests were performed. The laser probe was aligned with the power meter, which provided the real average power being emitted by the LLLT device. All of the data and information related to the laser application were collected with the use of a questionnaire filled in by the supervising therapists.
RESULTS: The 60 devices evaluated showed deficit in real average power in the cooled-down and warmed-up condition. The statistical analysis (ANOVA) showed a significant decrease (p<0.05) in the real average power measured in relation to the manufacturer’s average power. On average, the most common dose in the clinics was 4 J/cm², and the most desired effects were healing and anti-inflammatory effects. According to the World Association for Laser Therapy (WALT), 1 to 4 J of final energy are necessary to achieve these effects, however only one device was able to reach the recommended therapeutic window.
CONCLUSION: The LLLT devices showed a deficit in real average power that emphasized a lack of order in the application of this tool. The present study also showed the need for periodical calibration of LLLT equipment and a better technical knowledge of the therapists involved.
[Phototherapy for chronic pain treatment].
- Department of Anesthesia, Toho University Sakura Medical Center Sakura 285-8741.
Three types of machines are used in the field of phototherapy for chronic pain. One type is an instrument for low reactive level laser therapy (LLLT), one is an instrument for linear polarized infrared light irradiation (SUPER LIZER), and the last one is an instrument for Xenon light irradiation (beta EXCEL Xe10). The available machines for LLLT all project laser by semiconductor. The newest machine (MEDILASER SOFT PULSE10) has peak power of 10 W and mean power of 1 W. This machine is as safe as 1 W machine and is effective twice as deep as the 1 W machine. The irradiation by low reactive level laser induces hyperpolarization, decreased resistance of neuronal membrane, and increased intra-cellular ATP concentrations. The effects of low reactive level laser might be induced by the activation of ATP-dependent K channel. The significant analgesic effects of 1 W and 10 W LLLT were reported with double blind test. The significant analgesic effects of linear polarized near infrared light irradiation with double blind test were also reported. The effects of low reactive level laser upon the sympathetic nerve system were thought to result from its normalization of the overloaded sympathetic nerve system.
Photomed Laser Surg. 2009 Aug;27(4):633-9.
Radiant power determination of low-level laser therapy equipment and characterization of its clinical use procedures.
Guirro RR, Weis LC.
Department of Biomechanics, Medicine and Rehabilitation of the Locomotor System, School of Medicine of Ribeirão Preto, University São Paulo, Ribeirão Preto, SP, Brazil. email@example.com
OBJECTIVE: The main objectives of this study were to characterize low-level laser therapy (LLLT) and the physical therapy clinical procedures for its use. BACKGROUND DATA: There are few scientific studies that characterize the calibration of LLLT equipment. MATERIALS AND METHODS: Forty lasers at 36 physical therapy clinics were selected. The equipment was characterized through data collected from the owner manuals, direct consultation with the manufacturers, and a questionnaire answered by the users. A digital potency analyzer was used to calibrate released mean potency. Qualitative data were presented throughout the descriptive statistics and quantitative data were analyzed by the Wilcoxon/Kruskal-Wallis and Fisher tests (significance, p < 0.05). RESULTS: The laser equipment was either AsGa (70.5%) or HeNe (23.5%), and 60% was analog and acquired over 5 years ago. The majority of the equipment was used 10-15 times per week and the most frequent density level used was 2 to 4 J/cm(2). Protective goggles were available in only 19.4% of the clinics evaluated. The association between the analyzed categories demonstrated that a lower mean potency was correlated both with equipment acquired over 5 years ago and analog technology. The determined mean potency was lower than the one claimed by the manufacturer (p < 0.05). In 30 cases, the analyzed equipment presented a potency between 3 microW and 5.6 mW; in three cases, the potency was >25 mW; and in seven cases, potency was nonexistent. CONCLUSION: The analyzed equipment was out-dated and periodical maintenance was not conducted, which was reflected in the low irradiated potency.
Masui. 2006 Sep;55(9):1104-11.
[Equipment for low reactive level laser therapy including that for light therapy]
[Article in Japanese]
Department of Anesthesiology, Nihon University School of Medicine (Surugadai Nihon University Hospital), Tokyo.
Equipments used for light therapy include machinery used for irradiation by low reactive level laser, xenon light and linear polarized infra-red ray. Low reactive level laser is divided into two types of laser according to the medium by which laser is obtained ; semiconductor laser and helium-neon laser. Low reactive level laser has only one wave length and produces analgesia by action of light itself. On the other hands, Xenon light and linear polarized infra-red ray produce analgesia by warming effect induced by light in addition to the action of light itself. There are four methods of irradiation by these light sources; irradiation of acupuncture points, of trigger points, along nerves causing pain and of stellate ganglion area. Indication for light therapy includes various kinds of diseases such as herpes zoster, post herpetic neuralgia, cervical pain, lumbago due to muscle contracture, complex regional pain syndrome, arthralgia etc. However, we have to know that light therapy does not exert analgesic effects equally to all patients. But light therapy does not accompany pain and rarely shows any side effects. Therefore it is thought to be an alternative for patients who reject injection or patients who are not indicated for nerve block because of patients’ conditions such as bleeding tendency.
Conf Proc IEEE Eng Med Biol Soc. 2006;1:4107-10.
Design of the laser acupuncture therapeutic instrument.
Li C, Zhen H.
Sch. of Electr. Eng. & Autom., Harbin Inst. of Technol., China. firstname.lastname@example.org
Laser acupuncture is defined as the stimulation of traditional acupuncture points with low-intensity, non-thermal laser irradiation. It has been well applied in clinic since the 1970s; however, some traditional acupuncture manipulating methods still cannot be implemented in the design of this kind of instruments, such as lifting and thrusting manipulating method, and twisting and twirling manipulating method, which are the essential acupuncture method in traditional acupuncture. The objective of this work was to design and build a low cost portable laser acupuncture therapeutic instrument, which can implement the two essential acupuncture manipulating methods. Digital PID control theory is used to control the power of laser diode (LD), and to implement the lifting and thrusting manipulating method. Special optical system is designed to implement twisting and twirling manipulating method. M5P430 microcontroller system is used as the control centre of the instrument. The realization of lifting and thrusting manipulating method and twisting and twirling manipulating method are technological innovations in traditional acupuncture coming true in engineering.
Biomed Eng Online. 2005 Jan 13;4(1):5.
Design and testing of low intensity laser biostimulator.
Valchinov ES, Pallikarakis NE.
Department of Medical Physics, University of Patras, Patras 26500, Greece. email@example.com
BACKGROUND: The non-invasive nature of laser biostimulation has made lasers an attractive alternative in Medical Acupuncture at the last 25 years. However, there is still an uncertainty as to whether they work or their effect is just placebo. Although a plethora of scientific papers published about the topic showing positive clinical results, there is still a lack of objective scientific proofs about the biostimulation effect of lasers in Medical Acupuncture. The objective of this work was to design and build a low cost portable laser device for stimulation of acupuncture points, considered here as small localized biosources (SLB), without stimulating any sensory nerves via shock or heat and to find out a suitable method for objectively evaluating its stimulating effect. The design is aimed for studying SLB potentials provoked by laser stimulus, in search for objective proofs of the biostimulation effect of lasers used in Medical Acupuncture. METHODS: The proposed biostimulator features two operational modes: program mode and stimulation mode and two output polarization modes: linearly and circularly polarized laser emission. In program mode, different user-defined stimulation protocols can be created and memorized. The laser output can be either continuous or pulse modulated. Each stimulation session consists of a pre-defined number of successive continuous or square pulse modulated sequences of laser emission. The variable parameters of the laser output are: average output power, pulse width, pulse period, and continuous or pulsed sequence duration and repetition period. In stimulation mode the stimulus is automatically applied according to the pre-programmed protocol. The laser source is 30 mW AlGaInP laser diode with an emission wavelength of 685 nm, driven by a highly integrated driver. The optical system designed for beam collimation and polarization change uses single collimating lens with large numerical aperture, linear polarizer and a quarter-wave retardation plate. The proposed method for testing the device efficiency employs a biofeedback from the subject by recording the biopotentials evoked by the laser stimulus at related distant SLB sites. Therefore measuring of SLB biopotentials caused by the stimulus would indicate that a biopotential has been evoked at the irradiated site and has propagated to the measurement sites, rather than being caused by local changes of the electrical skin conductivity. RESULTS: A prototype device was built according to the proposed design using relatively inexpensive and commercially available components. The laser output can be pulse modulated from 0.1 to 1000 Hz with a duty factor from 10 to 90%. The average output power density can be adjusted in the range 24-480 mW/cm2, where the total irradiation is limited to 2 Joule per stimulation session. The device is controlled by an 8-bit RISC Flash microcontroller with internal RAM and EEPROM memory, which allows for a wide range of different stimulation protocols to be implemented and memorized. The integrated laser diode driver with its onboard light power control loop provides safe and consistent laser modulation. The prototype was tested on the right Tri-Heater (TH) acupuncture meridian according to the proposed method. Laser evoked potentials were recorded from most of the easily accessible SLB along the meridian under study. They appear like periodical spikes with a repetition rate from 0.05 to 10 Hz and amplitude range 0.1-1 mV. CONCLUSION: The prototype’s specifications were found to be better or comparable to those of other existing devices. It features low component count, small size and low power consumption. Because of the low power levels used the possibility of sensory nerve stimulation via the phenomenon of shock or heat is excluded. Thus senseless optical stimulation is achieved. The optical system presented offers simple and cost effective way for beam collimation and polarization change. The novel method proposed for testing the device efficiency allows for objectively recording of SLB potentials evoked by laser stimulus. Based on the biopotential records obtained with this method, a scientifically based conclusion can be drawn about the effectiveness of the commercially available devices for low-level laser therapy used in Medical Acupuncture. The prototype tests showed that with the biostimulator presented, SLB could be effectively stimulated at low power levels. However more studies are needed to derive a general conclusion about the SLB biostimulation mechanism of lasers and their most effective power and optical settings.
Opt Express. 2009 Jun 8;17(12):9873-8.
Design of vertically-stacked polychromatic light-emitting diodes.
Hui KN, Wang XH, Li ZL, Lai PT, Choi HW.
Department of Electrical and Electronic Engineering, Semiconductor Display and Lighting Laboratory, The University of Hong Kong, Hong Kong.
A new design for a polychromatic light-emitting diode (LED) is proposed and demonstrated. LED chips of the primary colors are physically stacked on top of each other. Light emitted from each layer of the stack passes through each other, and thus is mixed naturally without additional optics. As a color-tunable device, a wide range of colors can be generated, making it suitable for display purposes. As a phosphor-free white light LED, luminous efficacy of 30 lm/watt was achieved.
Semin Cutan Med Surg. 2008 Dec;27(4):292-300
Current and future trends in home laser devices.
Department of Cutaneous Laser Surgery, Brooke Army and Wilford Hall Air Force Medical Centers, San Antonio, TX, USA. firstname.lastname@example.org
Laser and intense pulse light procedures, once limited to physician offices and operating rooms, have become increasingly available at a variety of nonmedical sites such as spas. State regulations as to whom can perform these treatments varies greatly across the United States and, thus, in some states, the operators of these devices do not have any significant additional medical or laser knowledge more so than the patients who receive treatment. Although serious complications of laser treatments occur, they are rare when the procedure is performed correctly. Currently, there are 2 light devices approved by the Food and Drug Administration for home hair removal on the U.S. market, and several other companies are expected to release products in the near future. There are two home laser devices marketed for hair loss. As these light-based devices become smaller, safer, easier to use, as well as cheaper to manufacture, direct use by patients will increase. Results from home use devices are impressive but still inferior to office-based lasers and light devices. It is likely that home lasers and intense pulsed light devices will eventually receive other indications because many of these devices use wavelengths similar to currently available office based equipment.
Aerosp Am. 2000 Apr;38(4):24-5.
From growing plants to killing tumors.
NASA: A technique called photodynamic therapy, originally developed for commercial plant growth research on the Space Shuttle, has been used by surgeons in two successful operations for brain tumors. The device uses pin-head-size light emitting diodes (LEDs) that release long, cool, wavelengths of light which activate photosensitive antineoplastic drugs. The device is being adapted to non-space uses through a Small Business Innovation Research grant. The LEDs also are used to treat skin cancer, psoriasis, and rheumatoid arthritis. Research is being conducted regarding LED use in wound healing, tissue growth, and prevention of muscle and bone atrophy in astronauts.