Medical Instruments and Assistive Technology: Neuro Surgery Monitoring
Blood vessel-related diseases, such as stroke, are the third largest killers in Indonesia after heart and cancer diseases. In fact, referred to a 2004 survey, stroke is the primary causes of death in Indonesian government hospitals. There are about 500,000 new stroke patients every year in Indonesia. One third of those are fully recovered, the other one third have functional disabilities range from minor to medium level, the rest experience heavy functional disabilities which require long term and special medical treatment.
There are at least two mechanisms that cause stroke: a blocked artery and the leaking of a blood vessel (or combination). Both might cause paralysis and even sudden death. The other blood vessel-related disease is cerebral aneurysm, an anomaly of blood vessel that causes weak area of blood vessel enlarge. This phenomenon affects the thickness of the vessel, which gradually causes the vessel thinner and weaker and at one point the vessel spontaneously shatters, which releases the blood into a space in brain called subarachnoid cavity, leading to subarachnoid hemorrhage (SAH). The blood might mix with cerebrospinal fluid or flow to the brain substance, forming intracerebral hemorrhage.
It is important to assess the quality of blood vessel as an early disease detection to prevent physical defect as the main objective. Electroencephalograph (EEG) monitoring is important both for study of brain electricity and for nerve surgery monitoring. The EEG monitoring instrument can suggest how to minimize blooding effect due to surgery and can determine minimally proper location in tumor removal without spoiling the healthy brain tissue.
The research is a collaboration between nerve surgery doctor team and instruments and signal processing team. The research was started from sensor selection to model and algorithm development to get parametric signals satisfying clinical and medical requirements. There was also collaboration with hospitals and industries to perform clinical tests and instrument optimization. The optimization includes quality, cost, and time for production assessment.
Holographic method is a recording method of distribution of interference pattern produced by interaction between two coherent beams. Holographic microscope is a device that utilizes holographic method for observation of microscopic objects. Images from holographic microscope contain intensity and phase information simultaneously so that the images are more easily reconstructed into 3D images. Moreover, transparent objects with low contrast are subject to holographically processing without additional processing to form more contrast images.
The aim of holographic microscope research is to build a device with parallel and homogeneous beam so that it can be used for diagnostic tools in medical and biological purposes.
ITB Biomedical Engineering has conducted researches about holographic microscope since 2010. The works include:
- Developing hardware of digital holographic microscope with off-axis configuration. The hardware was constructed from Mach Zehnder interferometer, light source from 656.81 nm-laser diode, and CMOS sensor image with resolution of 1.3 megapixels. Silica gel was used as a test object. The resolution of the device was 10.1 µm.
- Designing software to reconstruct the holograms. The holograms used in the test were from recording of off-axis configuration holographic microscope.
- Developing software for image reconstruction of digital holographic microscope in C++.
- Developing a digital off-axis configuration holographic microscope with Michelson interferometer. The hardware was constructed from Michelson interferometer, light source from 533 nm-laser diode, and CMOS sensor image with resolution of 1280 × 720 pixels. Silica gel, crystal salt and red blood cells were used as test objects.
The previous studies in ITB Biomedical Engineering holographic microscope research succeed to develop holographic microscope with horizontal beam propagation. This arrangement requires vertical deployment of object observation, i.e. the device cannot be used for fluid object observations. Thus, further research is expected to solve this problem, namely digital holographic microscopy with vertical beam propagation.