Technical Note: Rod phantom analysis for comparison of PET detector sampling and reconstruction methods

Scott D. Wollenweber, Brad J. Kemp

Research output: Contribution to journalArticle

2 Scopus citations

Abstract

Purpose: This investigation aimed to develop a scanner quantification performance methodology and compare multiple metrics between two scanners under different imaging conditions. Most PET scanners are designed to work over a wide dynamic range of patient imaging conditions. Clinical constraints, however, often impact the realization of the entitlement performance for a particular scanner design. Using less injected dose and imaging for a shorter time are often key considerations, all while maintaining "acceptable" image quality and quantitative capability. Methods: A dual phantom measurement including resolution inserts was used to measure the effects of in-plane (x, y) and axial (z) system resolution between two PET/CT systems with different block detector crystal dimensions. One of the scanners had significantly thinner slices. Several quantitative measures, including feature contrast recovery, max/min value, and feature profile accuracy were derived from the resulting data and compared between the two scanners and multiple phantoms and alignments. Results: At the clinically relevant count levels used, the scanner with thinner slices had improved performance of approximately 2%, averaged over phantom alignments, measures, and reconstruction methods, for the head-sized phantom, mainly demonstrated with the rods aligned perpendicular to the scanner axis. That same scanner had a slightly decreased performance of -1% for the larger body-size phantom, mostly due to an apparent noise increase in the images. Most of the differences in the metrics between the two scanners were less than 10%. Conclusions: Using the proposed scanner performance methodology, it was shown that smaller detector elements and a larger number of image voxels require higher count density in order to demonstrate improved image quality and quantitation. In a body imaging scenario under typical clinical conditions, the potential advantages of the design must overcome increases in noise due to lower count density.

Original languageEnglish (US)
Pages (from-to)6175-6185
Number of pages11
JournalMedical Physics
Volume43
Issue number11
DOIs
StatePublished - Nov 1 2016

Keywords

  • image quality
  • positron emission tomography (PET)
  • quantification

ASJC Scopus subject areas

  • Biophysics
  • Radiology Nuclear Medicine and imaging

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