A New Method to Measure Directional Modulation Transfer Function Using Sphere Phantoms in a Cone Beam Computed Tomography System

作者：Lee Changwoo; Baek Jongduk^*

来源：IEEE Transactions on Medical Imaging, 2015, 34(4): 902-910.

DOI：10.1109/TMI.2014.2369524

• Cone beam computed tomography (CBCT)
• directional modulation transfer MTF)
• FDK
• Richardson-Lucy (RL) deconvolution
• sphere phantoms

We propose a new method to measure directional modulation transfer MTF) using sphere phantoms in a cone beam computed tomography (CBCT) system. To measure spatially varying 3-D MTFs, we model FDK reconstruction in local regions and calculate the plane integrals of an ideal sphere phantom and reconstructed sphere phantoms. Then, we modify the Richardson-Lucy (RL) deconvolution method to relax the non-negativity constraint in RL deconvolution and apply it to estimate the directional plane spread functions (PlSFs). Directional MTFs are calculated by taking the modulus of the Fourier transform of the estimated directional PlSFs. To validate the proposed method, we simulate ideal 3-D MTFs and compare them with directional MTFs measured by simulation and experimental data along three major axes. For quantitative evaluation, we compare full-width at half-maximum (FWHM) and full-width at tenth-maximum (FWTM) of measured and ideal directional MTFs. The measured directional MTFs from simulation and experimental data show excellent agreement with the ideal directional MTFs, demonstrating the effectiveness of the proposed method to estimate directional MTFs in a CBCT system.

• 出版日期2015-4