Microstereolithography is a well known method for three dimensional microfabrication. Despite wide needs for microdevices from biotechnological and medical industries, microstereolithography cannot be applied to those fields because photocurable resins used in conventional stereolithography system are not cytocompatibile. To overcome this problem, we have been working on new post-bake process to provide cytocompatibility to conventional photocurable resin. In this report, stereolithographic objects with transparency and cytocompatibility were realized by a high temperature post-bake process in nitrogen atmosphere. By using MTT assay, precise post-bake conditions both in air and nitrogen were investigated. Transparency of post-baked photocurable resin was increased by processing in nitrogen atmosphere. In addition, the aqueous solution of the generated gas during post-bake process and the eluted substance from non-treated Photocurable resin had the same spectrum peak at around 245 nm. This result indicated that cytotoxicity of photocurable resin was reduced due to sublimation and diffusion of cytotoxicic substances from cured photocurable resin. The new post-bake process developed herein should be a fundamental fabrication technology for future development of medical micromachines, portable health care devices and tissue engineering devices.
Medical errors are critical issues in medical practice. Serious accidents are deeply investigated, but most slight cases are ignored as careless mistakes by clinical staff. Identification of potential risks in surgery and treatment of risks are important to decrease errors. Video recording and analyzing system was developed to record intraoperative information and to find risk factors, but visual mining by medical doctors requires much time and effort and the results will be subjective. Thus we adopted quantity of motion in the recorded video as a quantitative index to indicate “candidates” of incidents. This system was evaluated in a clinical case (brain tumor removal) to compare detecting ability of incidents between human observation and computer processing. While human observation took 8.7 hours (equivalent to operative time) and found 4 incidents, computer processing took only 2.7 hours and extracted 81 candidates under tentative extraction threshold. Two events were common to both methods, but results of computation contained many false positive cases and does not detect rest two cases which human observation succeeded. Computer detection reduced the time to find risk factors, but it contained false detection and could not detect motionless incidents. We will integrate other featuring quantity and machine learning methods.
The advancement of measurement technology inside operation room including medical imaging and diagnosis and the combination between these technologies and computer technology leads the progress of navigation surgery, which is safer and more precise surgery; this type of a surgical procedure is mainly applicable to neurosurgery, orthopedic surgery, and otolaryngologic surgery. For example, fetal endoscopy can be safely performed through a surgical procedure based on the navigation technology; this procedure enhances the surgeon's field of view. However, a real-time and high-quality imagining and visualization technology is required to perform surgeries involving the treatment of soft tissue, such as fetal surgery. In our work, we developed a real-time updated navigation system for performing abdominal endoscopy including fetal surgery, using a high-speed transfer interface of a real-time 3D ultrasound imaging system and by carrying out high-speed computing using a multi-core processor system. The evaluation results of our system showed that our system was able to detect a position error of up to approximately 2.78 mm, and it was able to visualize and process data after every 200-500 ms. Further, we developed a new method for sensing the distance between the organs and surgical instruments. The evaluation results of our navigation system show that our system is able to avoid collision between the organs and surgical instruments during endoscopic procedures.