Asian Journal of Nuclear Medicine
亞洲核醫學雜志

Volume 2 Number 1, March 2002
Abstract

SPECT圖像的重建算法及噪聲抑制

宋惠寧,張智勇,張放林,徐曉紅,張貴鋒,禹暉
蘭州軍區總醫院核醫學科,蘭州 730050,中國

目的 通過選用科學的重建算法和合理的控制噪聲來提高圖像處理的質量。 方法 重建算法可以採用最大期望值(Expectation Maximization,EM)的方法來提高重建圖像的精確度,能夠通過預先分組(Ordered Subsets,OS)的方法來提高圖像重建的速度,即在滑環技術的基礎上對符合電路圖像進行高精度快速的重建(COSEM)。噪聲抑制,首先要選擇一個合適的濾波器來得到分辨率和引入噪聲偽像的最好的折中,然後通過衰減校正和散射校正來提高對深部小病灶的探測能力。結果 1.採用COSEM重建算法能夠消除濾波反投影技術(FBP)圖像重建方法固有的星狀偽影,也解決了採用代數迭代重建(ALR)方法存在的多少迭代次數重建能夠得到最佳圖像及計算時間太長以致臨床無法接受的問題。2.對不同的臟器選用不同的濾波函數和濾波參數及衰減係數,能有效的減少噪聲,提高圖像處理的質量。結論 要想獲得最佳的圖像效果,必須綜合多方面的因素來進行處理。既要有科學的重建算法,又要有效的抑制噪聲,保證良好的圖像分辨率。不同的臟器應採用不同的濾波器及濾波參數,另外還要考慮到衰減及散射對圖像的影響。

【關鍵詞】SPECT

Reconstruction method and noise control in SPECT imaging

Song Huining, Zhang Zhiyong, Zhang Fanglin, Xu Xiaohong, Zhang Guifeng, Yu Hui
Department of Nuclear Medicine, Lanzhou Genreal Hospital, Lanzhou, 730050, China.

Objective To improve SPECT image quality through applications of scientific reconstruction method and logical noise control. Methods Both Expectation Maximization (EM) and Ordered Subsets (OS) can be applied to improve image definition and reconstruction speed respectively. This method attempts to perform precise and high speed reconstruction base on slip-ring technology. For noise control, firstly, an appropriate filter is chosen to achieve the best balance between image resolution and image noise, then attenuation correction and scatter correction are applied to improve the detection power for small deep lesions. Results 1.Adopting COSEM method not only can eliminate "star"-shaped artifacts from filtered back projection (FBP), but also can solve some problems arising from adopting the ALR method such as long processing time. 2.Noise can be minimized through the choice of different filter parameters and attenuation coefficients for different organs. Conclusion We must bring together extensive factors in order to produce the best reconstructed image. To ensure better image resolution, both scientific reconstruction method and effective noise control are needed. Different organs require different filters and filter parameters. Furthermore, the effect of attenuation correction and scatter correction on image quality should be considered.

Key words: SPECT ; Image Reconstruction ; Filtering ; Correction



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