Notes of Medical images

Pagina 1

MEDICAL IMAGES A medical image is defined in space. It is defined by two coordinates: 𝑥 and 𝑦. The pixel are the smallest squares that compose the image and the smallest dimension that can be captured. This is why a good resolution of the image is given by a high number of pixel as it is possible to see a lot of details in the image. This definition of the object is done in the space domain (two dimension). Different techniques for image acquisition X-rays: 𝑋-rays have a start intensity and an arrival intensity. The 𝑥 rays pass through the volume of the body and arrive on the detector. The final intensity is attenuated in the volume and produces the image. This is the first way through which the images were created. The attenuation coefficient is indicated by 𝜇. This coefficient is specific for each tissue that characterises our body districts. Through this physical property of the tissues is possible to obtain the image of the district we want to analyse. Magnetic Resonance Image (MRI): it is a complicated method that uses tomographic reconstruction. MRI uses a big magnet producing a magnetic field that interacts with protons inside the human body. This is particularly useful to represent soft tissue in human body. Echography images (ECHO): mechanical waves change their direction and the return intensity of the mechanical waves associated to the different tissues. 𝛾-camera: is the simplest nucleus medicine technique. The images obtained have a lower resolution when compared to other images. These images contain information about the evolving metabolism of the patient. The structure visible in the image can be associated to a tumour region, for example, that was not visible in other ways. Generation and processing of a Biomedical Image The generation and processing of…