Improved iterative reconstruction method for Compton imaging using median filter

PloS One
Makoto SakaiTakashi Nakano

Abstract

A Compton camera is a device for imaging a radio-source distribution without using a mechanical collimator. Ordered-subset expectation-maximization (OS-EM) is widely used to reconstruct Compton images. However, the OS-EM algorithm tends to over-concentrate and amplify noise in the reconstructed image. It is, thus, necessary to optimize the number of iterations to develop high-quality images, but this has not yet been achieved. In this paper, we apply a median filter to an OS-EM algorithm and introduce a median root prior expectation-maximization (MRP-EM) algorithm to overcome this problem. In MRP-EM, the median filter is used to update the image in each iteration. We evaluated the quality of images reconstructed by our proposed method and compared them with those reconstructed by conventional algorithms using mathematical phantoms. The spatial resolution was estimated using the images of two point sources. Reproducibility was evaluated on an ellipsoidal phantom by calculating the residual sum of squares, zero-mean normalized cross-correlation, and mutual information. In addition, we evaluated the semi-quantitative performance and uniformity on the ellipsoidal phantom. MRP-EM reduces the generated noise and is robust with respec...Continue Reading

References

Jul 18, 2002·Physics in Medicine and Biology·T Tomitani, M Hirasawa
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Aug 5, 2016·Medical Physics·A AndreyevA Sitek
Oct 11, 2017·Physics in Medicine and Biology·M FontanaÉ Testa
Sep 18, 2018·Physics in Medicine and Biology·Makoto SakaiTakashi Nakano
Dec 12, 2018·Physica Medica : PM : an International Journal Devoted to the Applications of Physics to Medicine and Biology : Official Journal of the Italian Association of Biomedical Physics (AIFB)·Makoto SakaiTakashi Nakano
Jan 23, 2019·Physics in Medicine and Biology·Raj Kumar ParajuliTakashi Nakano

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Citations

Dec 29, 2020·Journal of Nuclear Medicine Technology·Mitsuha FukamiTomoaki Yamamoto
Nov 6, 2021·Scientific Reports·Raj Kumar ParajuliMutsumi Tashiro

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Methods Mentioned

BETA
gamma-ray

Software Mentioned

MRP
Geant4
EM
OS

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