banner image
No data available.
Please log in to see this content.
You have no subscription access to this content.
No metrics data to plot.
The attempt to load metrics for this article has failed.
The attempt to plot a graph for these metrics has failed.
The full text of this article is not currently available.
Antiscatter grids in mobile C-arm cone-beam CT: Effect on image quality and dose
Rent this article for
Access full text Article
1. S. Schafer, S. Nithiananthan, D. J. Mirota, A. Uneri, J. W. Stayman, W. Zbijewski, C. Schmidgunst, G. Kleinszig, A. J. Khanna, and J. H. Siewerdsen, “Mobile C-arm cone-beam CT for guidance of spine surgery: Image quality, radiation dose, and integration with interventional guidance,” Med. Phys. 38 (8), 45634574 (2011).
2. J. H. Siewerdsen, D. J. Moseley, S. Burch, S. K. Bisland, A. Bogaards, B. C. Wilson, and D. A. Jaffray, “Volume CT with a flat-panel detector on a mobile, isocentric C-arm: Pre-clinical investigation in guidance of minimally invasive surgery,” Med. Phys. 32 (1), 241254 (2005).
3. J. H. Siewerdsen and D. A. Jaffray, “Cone-beam computed tomography with a flat-panel imager: Magnitude and effects of x-ray scatter,” Med. Phys. 28 (2), 220231 (2001).
4. J. H. Siewerdsen, D. J. Moseley, B. Bakhtiar, S. Richard, and D. A. Jaffray, “The influence of antiscatter grids on soft-tissue detectability in cone-beam computed tomography with flat-panel detectors,” Med. Phys. 31 (12), 35063520 (2004).
5. L. Zhu, Y. Xie, J. Wang, and L. Xing, “Scatter correction for cone-beam CT in radiation therapy,” Med. Phys. 36 (6), 22582268 (2009).
6. W. Zbijewski, P. D. Jean, P. Prakash, Y. Ding, J. W. Stayman, N. Packard, R. Senn, D. Yang, J. Yorkston, A. Machado, J. A. Carrino, and J. H. Siewerdsen, “A dedicated cone-beam CT system for musculoskeletal extremities imaging: Design, optimization, and initial performance characterization,” Med. Phys. 38 (8), 47004713 (2011).
7. C. Schmidgunst, D. Ritter, and E. Lang, “Calibration model of a dual gain flat panel detector for 2D and 3D x-ray imaging,” Med. Phys. 34 (9), 36493664 (2007).
8. M. J. Daly, J. H. Siewerdsen, D. J. Moseley, D. A. Jaffray, and J. C. Irish, “Intraoperative cone-beam CT for guidance of head and neck surgery: Assessment of dose and image quality using a C-arm prototype,” Med. Phys. 33 (10), 37673780 (2006).
9. R. Fahrig, R. Dixon, T. Payne, R. L. Morin, A. Ganguly, and N. Strobel, “Dose and image quality for a cone-beam C-arm CT system,” Med. Phys. 33 (12), 45414550 (2006).
10. S. Kim, S. Yoo, F.-F. Yin, E. Samei, and T. Yoshizumi, “Kilovoltage cone-beam CT: Comparative dose and image quality evaluations in partial and full-angle scan protocols,” Med. Phys. 37 (7), 36483659 (2010).
11. Y. Watanabe, “Derivation of linear attenuation coefficients from CT numbers for low-energy photons,” Phys. Med. Biol. 44 (9), 2201 (1999).
12. J. H. Siewerdsen, A. M. Waese, D. J. Moseley, S. Richard, and D. A. Jaffray, “Spektr: A computational tool for x-ray spectral analysis and imaging system optimization,” Med. Phys. 31 (11), 30573067 (2004).
13. U. Neitzel, “Grids or air gaps for scatter reduction in digital radiography: A model calculation,” Med. Phys. 19 (2), 475481 (1992).
14. J. H. Siewerdsen and D. A. Jaffray, “Optimization of x-ray imaging geometry (with specific application to flat-panel cone-beam computed tomography),” Med. Phys. 27 (8), 19031914 (2000).

Data & Media loading...


Article metrics loading...



Purpose: X-ray scatter is a major detriment to image quality in cone-beam CT(CBCT). Existing geometries exhibit strong differences in scatter susceptibility with more compact geometries, e.g., dental or musculoskeletal, benefiting from antiscatter grids, whereas in more extended geometries, e.g., IGRT, grid use carries tradeoffs in image quality per unit dose. This work assesses the tradeoffs in dose and image quality for grids applied in the context of low-dose CBCT on a mobile C-arm for image-guided surgery.Methods: Studies were performed on a mobile C-arm equipped with a flat-panel detector for high-quality CBCT. Antiscatter grids of grid ratio (GR) 6:1–12:1, 40 lp/cm, were tested in “body” surgery, i.e., spine, using protocols for bone and soft-tissue visibility in the thoracic and abdominal spine. Studies focused on grid orientation, CT number accuracy, imagenoise, and contrast-to-noise ratio(CNR) in quantitative phantoms at constant dose.Results: There was no effect of grid orientation on possible gridline artifacts, given accurate angle-dependent gain calibration. Incorrect calibration was found to result in gridline shadows in the projection data that imparted high-frequency artifacts in 3D reconstructions. Increasing GR reduced errors in CT number from 31%, thorax, and 37%, abdomen, for gridless operation to 2% and 10%, respectively, with a 12:1 grid, while imagenoise increased by up to 70%. The CNR of high-contrast objects was largely unaffected by grids, but low-contrast soft-tissues suffered reduction in CNR, 2%–65%, across the investigated GR at constant dose.Conclusions: While grids improved CT number accuracy, soft-tissue CNR was reduced due to attenuation of primary radiation.CNR could be restored by increasing dose by factors of ∼1.6–2.5 depending on GR, e.g., increase from 4.6 mGy for the thorax and 12.5 mGy for the abdomen without antiscatter grids to approximately 12 mGy and 30 mGy, respectively, with a high-GR grid. However, increasing the dose poses a significant impediment to repeat intraoperative CBCT and can cause the cumulative intraoperative dose to exceed that of a single diagnostic CT scan. This places the mobile C-arm in the category of extended CBCT geometries with sufficient air gap for which the tradeoffs between CNR and dose typically do not favor incorporation of an antiscatter grid.


Full text loading...

This is a required field
Please enter a valid email address

Oops! This section, does not exist...

Use the links on this page to find existing content.

752b84549af89a08dbdd7fdb8b9568b5 journal.articlezxybnytfddd
Scitation: Antiscatter grids in mobile C-arm cone-beam CT: Effect on image quality and dose