Imagine a robot is operating on you! Now let's learn the technology behind this! Welcome to the robotic surgery, a real revolutionary !
Da vinci 3D endoscope developed by Intuitive Surgical.
The world of imaging has so expanded into healthcare. From diagnosis to surgical intervention, imaging plays an important role to see the internal human system without major surgical cuts. There are different imaging modalities that include but are not limited to MRI(Magnetic Resonance Imaging), X-Ray, CT(Computer tomography),endoscopy. The material elaborates on the optical system of the endoscopy and its applications in the robotic surgery. The endoscopy is an imaging instrument that has a camera attached on its tips and is introduced into the body to view the internal human system. The optic setup is precise enough in such a way that it extends the surgeon's eye virtually. The endoscopes are used for diagnosis and for imaging guidance during robotic surgery. The major component that determines the quality of the images for the endoscopes is sensor. The real challenge is to reduce the chip size while there are more pixels to represent the details of the image. The optical system and the electronic image processing algorithm allows the surgeons to diagnose, plan treatment and perform surgery. Most of the cases, the 3D endoscopes are considered for robotic surgery as they give tissue depth information. On the whole, the purpose of robotic surgical visual systems along with other control systems is to emulate the normal endoscopic surgery that is done manually. In addition to the endoscopic images, the visual system also provides convenience to switch to IR fluorescence mode to display the veins. The knowledge about sensors would give ideas to create effective image processing algorithms.
Da-vinci robot visual system:
Da-vinici is a robotic surgeon system developed by Intuitive surgical and it is the first surgical robot approved by FDA. The interesting fact about 3DHD endoscopic used in da vinci is that the images can be visualized by the surgeon and also viewed in a monitor for other supporting surgeons. The 3D visualization system along with haptic surgical tools are the specialized features that enable the surgeon to operate on a patient while sitting on a console.
Da vinci 3D endoscope image used in robotic surgery
In the visual system, the camera parameters are well adjusted for detailed visualization without interruption. The diameter of the endoscope is adjusted to be small enough to enter the body but also large enough for better resolution and magnification. The diameter of the da- vinci endoscope usually varies from 8mm to 12mm which is large enough to fit into two cameras of the 3D endoscope. The Focal length of the camera lens affects features like the magnification, the depth perception, and the image focus. The focal length of the lens of the da vinci endoscopic camera is about 2.0 mm.
The baseline is the distance between the two cameras. The baseline along with the distance to the target affects the ability to focus. But in the case of da Vinci system, only the distance to the target can be changed as the baseline is fixed (ranges from 10mm to 12 mm). The baseline also affects the depth perception. More the baseline, more the depth. This can be proved using the formula for calculating the Z coordinates of the point cloud(see equation (1)). Also magnification of 10 - 15 X power is added to the visual system. It is the product of optical magnification and digital monitor magnification. The optical magnification is based on the optical laws of the lens and the digital magnification depends on image sensor size and width of the monitor screen.
This magnification feature allows the surgeons to zoom the image of the target without cropping and with good resolution. The resolution of the surgeon console in the da vinci system is about 1080 pixels. The aspect ratio of the images starts from 4:3 and can zoom upto 5 levels without mosaic effect. The ultimate challenge in a 3D endoscope sensor is to reduce the sensor size while increasing the number of pixel occupancy. So pixel size is chosen considering the sensitivity and the resolution. The spatial resolution for da vinci is usually 1280 X 800 which depends on the pixel size.
Sensitivity is the amount of light the sensor is able to detect and it depends on the size of each pixel. The sensitivity also depends on the wavelength of the illumination. In davinci, the illumination is usually the white light of the visible range and it is provided by the 300 W xenon light through an optic fiber. One of the challenges in visualizing surgical processes is the fogging effect on the endoscope lens. This is caused due to the smoke accumulation, blood spills and debris during surgery. There are many anti fogging methods and one of which is using part of the illuminating light to heat up the endoscope.
Considering depth perception, there are many camera parameters to consider that include camera baseline, camera to target distance, viewer to display distance, camera convergence angle, field of view, display screen width and the similarity measure between the two images. The correspondence of the images from the two cameras is done by scope alignment and should be adjusted before surgery. The other parameter that affects the scope alignment is the baseline which is fixed in case of the da Vinci visual system . Irregular scope alignment can lead to larger image disparity values, yielding lower quality images lacking depth.
Apart from the high image quality, there is a freedom for the endoscope to peek through the nook and the corner of the body system. In da vinci system, there are two kinds of endoscopes with respect to angle. The usual 0 degree endoscope which is straight and rigid. This is commonly used for normal endoscopic surgery. The 30 degree endoscope has freedom to move in 30 degrees both upwards and downwards, covering a wider angle of view. The field of view for the da vinci camera would range from 60 to 80 degrees for the da Vinci system. Along with optical setup, the visual system also provides pre operative image data taken from other imaging modalities. These images are superimposed using augmented reality to view the hidden tissues underneath.
A typical da vinci surgical system
The 3DHD sensor gives optimal visualization for the surgeons to identify the critical anatomy and operate on patients precisely. The state of the art technology in the field of robotic surgery is advancing the whole system for teleoperation. Currently, the robotic surgery helps the surgeon to operate on a patient from the same room without contact. But the teleoperation is done when the doctor and the patient are in different locations. This requires advancement in communication system(5G), visual system, haptic system and the overall control system. Considering the visual system, the major challenge would be better hardware obtained by reducing the chip size while allowing maximum pixel occupancy; image processing and reconstruction algorithm for resolution at the surgeon's console. In addition to this, another challenge is that robotic surgery is used for a few cases like lungs, heart, digestive. There are still many untouched areas of robotic surgery like the brain, neural system. This is because these surgeries involve operating on small structures. Hence the challenge is to reduce the endoscope size to fit through the small hollow structures like nerves and with good resolution to capture minute details. Thus a balanced advancement of optic technology and image processing algorithms is very much needed in this case. A highly recommended way for such an advancement would be to know about the tissue light interactions, further study on the working of the human brain in visualization and then advancing technology from here.
Comentários