Abstract
Iodine contrast medium is used in Digital Subtraction Angiography (DSA) examination, in which the contrast medium is injected into a blood vessel, and images are collected in real time. However, when iodine contrast medium is used for a patient having iodine contraindication or an iodine allergy, critical side effects may occur. We compared the DSA image of Gadolinium (Gd) contrast medium and iodine contrast medium in order to investigate DSA examination using Gd contrast medium. As a result, the contrast provided by Gd contrast medium decreased due to the absorption of X-rays. When the gradation processing (linear gray scale transformation) built into DSA equipment is applied to the image in which the contrast has decreased, there is also the possibility that the image will become unusable for diagnosis due to increased noise. The present study devised a nonlinear gray scale transformation process using Gd contrast medium by which noise to the DSA image is not increased. As main techniques, the genetic algorithm which can perform optimization and search was applied to image processing. As a result of calculating the optimal gray scale transformation function using a genetic algorithm, and applying this function to a DSA image using Gd contrast medium, the obtained image contained information required for diagnosis.
