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1. E. K. Fishman and R. B. Jeffrey, Spiral CT: Principles, Techniques, and Clinical Applications (Lippincott-Raven, Philadelphia, 1998).
2. M. Prokop and M. Galanski, Spiral and Multislice Computed Tomography of the Body (Thieme, Stuttgart, 2003).
3. W. A. Kalender, Computed Tomography: Fundamentals, System Technology, Image Quality, Applications, 3rd ed. (Publicis Publishing, Erlangen, 2011).
4. K. K. Lindfors, J. M. Boone, T. R. Nelson, K. Yang, A. L. C. Kwan, and D. W. F. Miller, “Dedicated breast CT: Initial clinical experience,” Radiology 246, 725733 (2008).
5. J. M. Boone, T. R. Nelson, K. K. Lindfors, and J. A. Seibert, “Dedicated breast CT: Radiation dose and image quality evaluation,” Radiology 221, 657667 (2001).
6. W. A. Kalender, M. Beister, J. M. Boone, D. Kolditz, S. V. Vollmar, and M. C. Weigel, “High-resolution spiral CT of the breast at very low dose: Concept and feasibility considerations,” Eur. Radiol. 22, 18 (2012).
7. F. Eisa, R. Brauweiler, M. Hupfer, T. Nowak, L. Lotz, I. Hoffmann, D. Wachter, R. Dittrich, M. W. Beckmann, G. Jost, H. Pietsch, and W. A. Kalender, “Dynamic contrast-enhanced micro-CT on mice with mammary carcinoma for the assessment of antiangiogenic therapy response,” Eur. Radiol. 18 (2011).
8. K. Nieman, F. Cademartiri, P. A. Lemos, R. Raaijmakers, P. M. T. Pattynama, and P. J. de Feyter, “Reliable noninvasive coronary angiography with fast submillimeter multislice spiral computed tomography,” Circulation 106, 20512054 (2002).
9. C. S. Chung, M. Karamanoglu, and S. J. Kovács, “Duration of diastole and its phases as a function of heart rate during supine bicycle exercise,” Am. J. Physiol. Heart Circ. Physiol. 287, H2003H2008 (2004).
10. M. J. Budoff, S. Achenbach, R. S. Blumenthal, J. J. Carr, J. G. Goldin, P. Greenland, A. D. Guerci, J. A. C. Lima, D. J. Rader, and G. D. Rubin, “Assessment of coronary artery disease by cardiac computed tomography,” Circulation 114, 17611791 (2006).
11. S. Achenbach, D. Ropers, A. Kuettner, T. Flohr, B. Ohnesorge, H. Bruder, H. Theessen, M. Karakaya, W. G. Daniel, and W. Bautz, “Contrast-enhanced coronary artery visualization by dual-source computed tomography—Initial experience,” Eur. J. Radiol. 57, 331335 (2006).
12. C. R. Becker, M. Reiser, H. Alkadhi, K. Nikolaou, and G. Glazer, Multislice CT (Springer, New York, 2009).
13. A. Oppelt, Imaging Systems for Medical Diagnostics: Fundamentals, Technical Solutions and Applications for Systems Applying Ionizing Radiation, Nuclear Magnetic Resonance and Ultrasound (John Wiley & Sons, New York, 2011).
14. J. Sweedler, J. Shear, H. Fishman, R. N. Zare, and R. Scheller, “Fluorescence detection in capillary zone electrophoresis using a charge-coupled device with time-delayed integration,” Anal. Chem. 63, 496502 (1991).
15. B. Pain, T. J. Cunningham, G. Yang, and M. Ortiz, U.S. patent 7,268,814 (5 October 2000–2007).
16. J. Bogaerts, G. Meynants and G. Lepage, European patent EP2088763 (12 August 2009).
17. G. Lepage, U.S. patent 7,675,561 (28 September 2006 2010).
18. M. Tesic, M. Fisher Piccaro, and B. Munier, “Full field digital mammography scanner,” Eur. J. Radiol. 31, 217 (1999).
19. T. O. Tümer, S. Yin, V. Cajipe, H. Flores, J. Mainprize, G. Mawdsley, J. A. Rowlands, M. J. Yaffe, E. E. Gordon, and W. J. Hamilton, “High-resolution pixel detectors for second generation digital mammography,” Nucl. Instrum. Methods Phys. Res. A 497, 2129 (2003).
20. M. Kachelrieß, M. Knaup, C. Penßel, and W. A. Kalender, “Flying focal spot (FFS) in cone-beam CT,” IEEE Trans. Nucl. Sci. 53, 12381247 (2006).
21. Y. Kyriakou, M. Kachelrieß, M. Knaup, J. U. Krause, and W. A. Kalender, “Impact of the z-flying focal spot on resolution and artifact behavior for a 64-slice spiral CT scanner,” Eur. Radiol. 16, 12061215 (2006).
22. T. Flohr, K. Stierstorfer, S. Ulzheimer, H. Bruder, A. Primak, and C. McCollough, “Image reconstruction and image quality evaluation for a 64-slice CT scanner with z-flying focal spot,” Med. Phys. 32, 2536 (2005).
23. L. Feldkamp, L. Davis, and J. Kress, “Practical cone-beam algorithm,” J. Opt. Soc. Am. A 1, 612619 (1984).
24. L. A. Shepp and B. F. Logan, “The Fourier reconstruction of a head section,” IEEE Trans. Nucl. Sci. 21, 2143 (1974).
25. C. E. Metz and K. Doi, “Transfer function analysis of radiographic imaging systems,” Phys. Med. Biol. 24, 1079 (1979).
26. K. Imamura, N. Ehara, Y. Inada, Y. Kanemaki, J. Okamoto, I. Maeda, K. Miyamoto, H. Ogata, H. Kawamoto, and Y. Nakajima, “Microcalcifications of breast tissue: appearance on synchrotron radiation imaging with 6-μm resolution,” Am. J. Roentgenol. 190, W234W236 (2008).

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Modern computed tomography(CT)systems are supporting increasingly fast rotation speeds, which are a prerequisite for fast dynamic acquisition, e.g. in perfusion imaging, and for new modalities such as dedicated breast CT, where breathhold scanning is indicated. However, not all detector technologies are supporting the high frame rates that are necessary to retain high resolution for objects far away from the isocenter. Even on systems that would support a sufficiently high frame rate, the necessary bandwidth of the data transfer from the rotating gantry stills remains challenging. The authors evaluated a pixel shifting technique termed time-delayed summation (TDS) as a method of increasing resolution on fast rotating CTsystems without the need to increase the frame rate.


In TDS mode, detector pixel values are shifted along rows during image acquisition to compensate for detector motion. In order to fully exploit TDS, focal spot position control (FSC) was used in combination with TDS. FSC applies a counter movement to the x-ray focal spot during image acquisition such that it is kept fixed in space. As a proof of concept, measurements were performed on a prototype photon counting detector capable of TDS. The detector was mounted on a movable table and a gold wire phantom was imaged with different TDS settings and detector velocities. Additionally, simulations of a broad range of TDS and FSC settings on two different modalities, a clinical CT scanner and a breast CT scanner, and two different detector geometries, flat and cylindrical, were performed to assess the gain in resolution and contrast in cylindrical water phantoms containing a small wire at distances from the phantom center varied from 5% to 90% of the phantom radius. As figures of merit, the modulation transfer function(MTF) at 10% and the maximum contrast were used and compared against the respective values when using step-and-shoot acquisition, which means stopping the rotation when a projection image is acquired.


Measurements showed that detector movement and the resulting blurring of the wire projections were compensated to the expected degree when using the appropriate number of TDS shifts per frame (TDS factor). Using simulations it was found that when using the optimal TDS factor, over 90% of the resolution achieved in step-and-shot mode was reached for all investigated wire positions. TDS showed better performance on a cylindrical detector that on the same system with a flat detector. TDS factors that were deviating from the optimum by more than 1 shift led to a performance below that of standard continuous acquisition.


The findings of this study encourage the combined usage of TDS and FSC in systems that require fast rotation. The integration of TDS in state-of-the-art x-ray detectors is feasible.


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