Storage volume of computer tomography images can be reduced by a factor of five

The object of this study is the data compression of CT scans of the brain. A circle is first established which contains all pixels inside the head while minimizing the insignificant area, after which the portion outside the circle so obtained is eliminated. The data are then truncated at CT values of +/- 127 and the differences of two consecutive pixel values are converted into variable length codes. The coding algorithms employed are the well-known Huffman code and our packet coding, both of which achieved a data compression ratio of 20%.