Four simple methods of scatter correction for gamma camera images: Compton window (CW), split window (SW), a reduced width window (15% photopeak window), and a Triple energy window (TEW) were assessed and compared. Point source images of 99mTc were assessed by the FWTM and FWHM of the image profiles. A Williams phantom was also imaged, for which ROIs were used to calculate contrast and signal to noise ratio (S/N) values. Two observers evaluated the visibility of lesions in randomized images of the phantom. All techniques reduced the FWTM value apart from the 15% photopeak method. Contrast improvements were observed for the SW method and less so for the TEW method, particularly at low counts. Both suffered from a decreased S/N. No improvement in lesion detection was observed for any scatter correction technique due to the reduced S/N. Applying a 9-point smooth to the scatter image before subtraction from the primary image marginally improved the visualization of the lesions over the unsmoothed method. These methods of scatter correction were not found to improve lesion detection but the SW method is believed to be the most promising. Further work to investigate ways of reducing the noise would be justified.
Wright DA, Chandler ST. Simple scatter correction methods for gamma camera images: do they work? British Nuclear Medicine Society Annual Meeting, Manchester 2006. Nuclear Medicine Communications, 27(3):285, (2006).
Mr. Steve Chandler, Darlington Unit, Darlington. Tel: +44 (0)1325-743-347.
Regional Medical Physics Department, Freeman Hospital, Newcastle upon Tyne, NE7 7DN, UK.
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