Evaluation of Median Root Prior for Robust In-Beam PET Reconstruction

Defne Us, Karol Brzezinski, Tom Buitenhuis, Peter Dendooven, Ulla Ruotsalainen

    Research output: Contribution to journalArticleScientificpeer-review


    Dose delivery verification in proton beam radiotherapy is used to ensure the delivery of the dose to the correct location. A positron emission tomography (PET) scanner can be used to detect the secondary radiation during the treatment, so-called in-beam PET. This is a challenging application for PET due to the low counts and limited angular coverage. We propose a maximum a posteriori (MAP) reconstruction with median root prior (MRP) for the reconstruction of in-beam PET data. The proposed method was compared against MAP with total variation (TV) prior and maximum likelihood expectation maximization (MLEM), which have previously been used for this application. The effects of different ring configurations and time-of-flight information were tested with simulations of a geometrical phantom and a realistic patient treatment plan. The results indicate that both MAP methods produced sharper edges than MLEM, allowing more accurate edge localization in the reconstructed images. Even for the partial ring configurations, no elongation was observed with MAP methods. MAP-MRP successfully reduced the noise, whereas MAP-TV resulted in checkerboard artifacts. MAP-MRP was also more stable against the selection of the reconstruction parameters. In conclusion, MAP-MRP offers a simple and robust alternative for the reconstruction of in-beam PET data.
    Original languageEnglish
    Pages (from-to)490-498
    Number of pages8
    JournalIEEE Transactions on Radiation and Plasma Medical Sciences
    Issue number5
    Publication statusPublished - 5 Sept 2018
    Publication typeA1 Journal article-refereed

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