Optical hollow fibers with inner dielectric and metal thin layers can deliver efficiently IR laser light which conventional silica fibers cannot be used for. A new novel endoscopic system using CO2 laser is being developed, in which such hollow fibers are considered as key devices. Compared to many other kinds of solid-core IR fibers, the hollow fibers have some advantages from the viewpoint of physical and chemical features as well as optical properties. CO2 laser light and visible aiming light transmitted through the hollow fiber are irradiated to tissues with a noncontact condition, in which the irradiating point can be grasped precisely. Unlike Nd:YAG lasers for endoscopic therapy as laser scalpels which were once widely evaluated, the light of CO2 laser does not penetrate deeply into the normal tissue and has an outstanding effect for cutting out appropriately a treatment area. The laser endoscopic system composed of the CO2 laser source and the hollow fiber is promising for a safer new method, especially a minimally invasive treatment for early stage of gastrointestinal cancers.
We demonstrate full-field optical coherence microscopy (FF-OCM) using an ultrathin forward-imaging short multimode fiber (SMMF) probe with a core diameter of 50 μm, outer diameter of 125 μm, and length of 7.4 mm, which is a typical graded-index multimode fiber used for optical communications. The axial and lateral resolutions were measured to be 2.14 μm and 2.3 μm, respectively. Inserting the SMMF 4 mm into the cortex of an in vivo rat brain, depths were scanned from a SMMF facet to 147 μm with a field of view of 47 μm. Three-dimensional (3D) OCM images were obtained at depths from about 20 μm to 90 μm. From morphological information of the resliced 3D images and the dependence of the integration of the OCM image signal on the inserted distance, the 3D information of nerve fibers have been demonstrated.
A composite-type optical fiberscope was developed for maintenance research and development of nuclear facilities by National Institutes for Quantum and Radiological Science and Technology (QST). It can coaxially deliver both a high-energy laser beam for micro processing and an image from processing targets. At present, we are developing a minimally invasive laser treatment device based on this technology and are expanding into the medical field. This paper introduces these medical applications.
We are developing a diffused light irradiation probe using a small diameter flexible plastic optical fiber and aiming at a photodynamic therapy in a narrow area by uniform light irradiation. In a narrow area, a direct transmission light irradiation probe could not manipulate the irradiation area, and a diffused light irradiation probe is required. The conventional diffused light irradiation probe made of quartz, has a hard tip, and could not be inserted into a curved path. We developed a light diffuser made by a small diameter plastic optical fiber and completed a small diameter and flexible diffused light irradiation probe.
In the result of discussions between industry, academia and government, yakuseikishinhatsu 0629 No. 4 ‘Management of medical laser application for approval’ was notified. The new notification shows not the range of specification without clinical trial but the guideline for development of medical laser including laser scalpel, which is mainly composed of non-clinical evaluation items and basic concepts of indication for use and necessity of clinical trial. The consultation with pharmaceuticals and medical devices agency is recommended for the decision that it is possible to evaluate the differences between devices with only non-clinical testing. Additionally, it is important for medical devices to take safety measures for the post marketing, which is not subjected to the notification but one of the review points for approval. Especially, it should be noted that safety manager selection and safety management area setting are essential for medical laser use. It is significant for resolving the clinical problems relative to medical laser to keep discussing continuously and cooperating closely with industry, academia and government.
This paper discusses perspective directions of evaluation of medical laser devices from an engineering side in response to the notification “Handling of application for approval of laser medical devices.” To accelerate the application approval of novel laser devices by safety and efficient use of this notification, we propose computer-aided regulatory science and introduce photothermal damage evaluation in laser medicine by simulation.
There is a significant proportion of unapproved laser and energy-based devices being used by dermatologists and plastic surgeons in Japan. The government’s approval process in very slow, which is problematic. Also, lasers and energy-based devices are used without clinical research. More research on these devices in needed as well as more academic conferences to help establish treatment guidelines monitor the incidence of complications.
This report summarizes the result of the questionnaire asked to the member institutions of Japan Medical Laser Association (JMLA) about how the MHLW, PSEHB/ELD Notification No. 0629-4—“The Procedural guideline for the approval of the applications for laser medical devices” issued on June 29, 2016—affected manufacturers’ activities. Also introduced here is my observation, reflecting the opinions submitted by the industry through the above questionnaire, that a new holistic approach of cooperation among “industry-academia-government-clinicians” that can stimulate the medical laser industry is needed under the current circumstances.
The activities of Social Insurance Committee of the Japan Society for Laser Surgery and Medicine for medical fee revision in 2020 and the results were described. In addition, the summary of the laser equipment that have been approved by government and the present insurance coverage for laser treatment were described in detail.