Yunzhe Zhao, Presenter: Research funded, TomoSoft Technologies, LLC

Emmanuel Brun, Abstract Co-Author: Nothing to Disclose

Alberto Bravin, Abstract Co-Author: Nothing to Disclose

Benjamin Pooya Fahimian BS, Abstract Co-Author: Research funded, TomoSoft Technologies, LLC

Anikó Sztrókay MD, Abstract Co-Author: Nothing to Disclose

Paola Coan, Abstract Co-Author: Nothing to Disclose

Jianwei Miao, Abstract Co-Author: Nothing to Disclose

Mammography requires multiple projections to achieve high image quality and since the breast is a highly radiosensitive organ, it is important to keep the delivered dose to as low as possible while maintaining the image quality. We newly developed and implemented an exact Fourier-based iterative reconstruction technique termed Equally-Sloped Tomography(EST) on Monochromatic phase contrast mammography and conducted a series of comparative experiments on human breast samples to explore the possibility of radiation dose reduction.

Experiment took place at the biomedical beamline at ESRF(ID17). Full samples of human breasts were fixed in 4% formalin solution. Planar imaging and Computed Tomography(CT) modalities were combined to PCI techniques at 60KeV and using a 2kx2k taper optics CCD detector(45 micron pixel). The number of projections scanned was 2000 and digitally removed to 512 for reconstructions. For reconstruction, EST method iterates back and forth between real and Fourier space. Constraints were applied in real domain while measured projections were updated in Fourier domain during each iteration. Comparison reconstructions were produced by Filtered-Back Projection(FBP) with a standard uncropped-ramp filter.

When quarter dose FBP reconstruction shows obvious degradation in contrast and resolution, both quantitative and visual comparisons indicate that full dose FBP reconstruction(2000 projections) and quarter dose EST reconstruction(512 projections) have comparable contrast performance between tumor and normal glandular tissue and the collagen exhibit similar visibility. Furthermore, by reducing number of projections, it makes the acquisition time 2~4 times faster, which is important in in-vivo imaging.

Our results indicate that in the monochromatic phase contrast mammography, EST technique can reduce the dose up to 50%~75% while maintaining comparable image as the full dose FBP reconstruction. The main reason for this is that EST is an exact Fourier-based iterative algorithm that compromise between the enforced constraints and the measured data. It is always guided towards a lowest-possible noisy state while keeping strictly consistent with measurements.

50%~75% reduction of radiation dose and data acquisition time in monochromatic phase contrast mammography can be achieved by reducing projection number and implementing EST reconstruction technique.

Zhao, Y, Brun, E, Bravin, A, Fahimian, B, Sztrókay, A, Coan, P, Miao, J, Radiation Dose Reduction in Monochromatic Phase Contrast X-ray Mammography Using Equally-sloped Tomography Reconstruction Technique.  Radiological Society of North America 2011 Scientific Assembly and Annual Meeting, November 26 - December 2, 2011 ,Chicago IL. http://archive.rsna.org/2011/11003991.html