Fractal analysis of an Advanced Modeled Iterative Reconstruction Algorithm for the evaluation of complex structure

摘要

Iterative reconstruction (IR) technique can allow a radiation dose reduction without unfavorable objective effects on image quality. Non-linear processing applied to IR may sometimes cause unwanted image appearance by increasing its strength. We examined whether it is possible to subjective evaluation of the IR image using fractal analysis. A bundle of five acryl rods inserted in the center of a circular phantom filled with various concentration of diluted contrast medium was scanned at a various radiation dose (CTDI_(vol) of 1.8 to 14.4 mGy) with different reconstruction algorithms such as FBP and IR with strength 1 to 5 at 120 kV. Images were analyzed to calculate fractal dimension (FD) of the phantom using a box-counting methods for binary images. The FD decreased with increasing radiation dose, IR strength and contrast differences. The FD of FBP images at 100% radiation dose was almost same as that of IR strength 3 at a half radiation dose. FD that represents complexity of contour would be applied as a potential indicator for the quantitative assessment of iterative reconstruction.