Evaluation of fundamental properties of DSA system by a simplified test phantom

Physical properties of digital subtraction angiography (DSA) system were evaluated using a simplified test phantom by comparing their contrast range, resolution, low-contrast (iodine) detectability and linearity, and subtraction effectiveness. The phantom consists of five clear-acrylic building blocks of step wedge, bone block, resolution block, artery block and slot block. Hitachi DFA-2 DSA system was employed as a DSA system. All phantom images were radiographed with serial imaging additive (SIA) mode on matrix sizes of 512 x 512 and 1024 x 1024 with 7 and 9 inch I.I. mode. Contrast curve was dependent on the matrix size and shape of the curve varied with the scatter fraction. Resolution limitting of matrix size of 1024 x 1024 was better than that of 512 x 512 matrix in both 7 and 9 inch I.I. mode. Detectability of low contrast phantom simulating stenoses and aneurysms was influenced by sizes of the lesions, concentrations of iodine and presence of materials behind the simulated arteries. (author)