講演抄録/キーワード |
講演名 |
2010-07-09 14:30
An IIR Ramp Filter for Filtered Backprojection Reconstruction of X-ray CT ○Kazuhisa Hayashi(Hitachizosen Corp.)・Hiroshi Tsutsu・Hiroaki Morimoto(Okayama Univ.)・Junichi Murakami(Kagawa college)・Yoshitaka Morikawa(Okayama Univ.) MI2010-44 |
抄録 |
(和) |
(まだ登録されていません) |
(英) |
It will be soon possible to be able to observe the moving 3D heart by X-ray CT in real time. Helical CT (HCT) is said to be the shortcut to such a 4D CT. In HCT, 2D reconstructed images are stacked to form a volume. Thus acceleration of 2D filtered backprojection algorithm (FBA) is valuable for 4D CT realization. The authors recently have developed order-N2log2N algorithm for backprojection. Therefore in FBA the cost of backprojection becomes comparable to that of filtering. The existing method for filtering converts the convolution with a ramp filter to the product in the FFT domain. In contrast, the new method decomposes a ramp filter into a cascade of differentiator and discrete Hilbert transformer (DHT), and directly applies them. Since allpass design of DHT yields very efficient realization, 4 to 5 times speed up for ramp filtering is possible comparing to the FFT method. We also propose a method to compromise ultralow frequency artifacts (dishing artifact) and ripple artifacts, using 1st order covariance model. Moreover, we expand the point spread function (PSF) from projection to backprojection with respect to the transition bandwidth. Since the lowest second order PSF implies the contribution to DC-shift, this paper proposes a compensation of DC-shift. Computer simulations showed the proposed method with DC-shift compensation is comparable to the existing method. |
キーワード |
(和) |
/ / / / / / / |
(英) |
CT / IIR Filter / Allpass Filter / Hilbert transformer / / / / |
文献情報 |
信学技報, vol. 110, no. 121, MI2010-44, pp. 39-44, 2010年7月. |
資料番号 |
MI2010-44 |
発行日 |
2010-07-02 (MI) |
ISSN |
Print edition: ISSN 0913-5685 Online edition: ISSN 2432-6380 |
著作権に ついて |
技術研究報告に掲載された論文の著作権は電子情報通信学会に帰属します.(許諾番号:10GA0019/12GB0052/13GB0056/17GB0034/18GB0034) |
PDFダウンロード |
MI2010-44 |