Two dimensional slice section are composed of pixels which are the smallest picture elements.
- The more the pixels in a certain distance the better the resolution.
- Currently the highest resolution available for both CT and MRI is 512×512 pixels per image. In a field that is 30×30 cm, this gives a low resolution.
- The image resolution is stated by the number of pixels in the x any y axis only and the size of the image field will not be actually defined.
- Each pixel in the CT scan has the value ranging from 1000 to 3096. This is often referred to as hounsfield unit (HU)
- CT scan are calibrated such that the value 0 = the density of water.
- High pixel values are displayed white. Lower pixel values – lower the density of tissue → darker.
- Pixel are 2D but it is possible to convert those pictures element into a 3 D block.
- This 3D block is referred to as a voxel or a volumetric picture element. Depending on the inter slice distance, voxel can be:
- a cube
- cuboid
