Spatial resolution of x-ray tomosynthesis in relation to computed tomography for coronal/sagittal images of the knee

We consider in this report, a tomosynthesis (TS) system utilizing a recently developed Selenium flat panel detector (Shimadzu Safire II) capable of acquiring 30 pulsed frames per second (fps) with precise geometric registration to a moving gantry. The reconstructed TS resolution achieved with this system is reported in relation to the resolution obtained with modern volumetric computed tomography (vCT) systems. Computed tomography resolution is assessed using a sphere phantom. To, describe the resolution of coronal/sagittal re-formatted planes, we average the transverse and axial response to express typical vCT performance as 1.00 mm (FWHM PISF) and 0.83 cycles/mm (10% MTF). Tomosynthesis response is assessed using a wire phantom. To describe the resolution of the coronal/sagittal TS images, we use the FWHM of the LSF and the frequency at 20% of the peak spatial frequency response to express typical TS performance as 2.41 mm (FWHM LSF) and 2.62 cycles/mm (20% Peak). Cadaver images confirm that the TS resolution is about 3 times better than that for vCT systems. On the other hand, the TS slice sensitivity of 3. mm is about 3 times larger than vCT resolution (FWHM LSF).