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Optimization Gap: Iterative Reconstruction Does Not Deliver Actual CT Dose Reduction in a Large, Diverse Fleet of Clinical CT Scanners

J Bell1*, C Smitherman2, T Petrone2, W Moloney3, D Jordan1, (1) University Hospitals, Cleveland, OH, (2) Petrone Associates, LLC, Staten Island, NY, (3) Bio-Med Associates, Inc, Yardley, PA


(Sunday, 7/12/2020) 1:00 PM - 2:00 PM [Eastern Time (GMT-4)]

Room: Track 1

Purpose: to compare actual CT dose reduction using iterative reconstruction (IR) versus filtered backprojection (FBP) based on protocols in use in a large fleet of scanners across multiple institutions. IR potentially reduces patient dose, with evidence and marketing claiming reductions of 25% to 80%. This study investigated whether protocols are being properly set up to take advantage of these potential reductions.

Methods: Acquisition protocol parameters and measured CTDIvol from over 100 scanners were collected from annual medical physicist equipment performance evaluations for adult head and abdomen and pediatric head and abdomen protocols. Protocols are mature, having been previously developed and used routinely for several years at the time of data collection. Therefore they were presumed to produce typical acceptable clinical image quality at the indicated dose levels. Scanners are in service at multiple institutions across Ohio and New York including a mix of academic and non-academic healthcare facilities. The CTDIvol from scanners using IR was compared to CTDIvol from scanners using FBP for each protocol.

Results: Measured CTDIvol for IR was found to be 10 to 25 percent lower than CTDIvol for FBP protocols. Adult head scans had CTDIvol reductions of approximately 10 percent. Adult abdomen, pediatric abdomen, and pediatric head were 26, 24, and 27 percent lower with IR, respectively. None of the differences was statistically significant, however.

Conclusions: Dose reductions with IR in real clinical CT protocols were smaller than claimed potential decreases and not significantly different from FBP protocol doses in the same geographic region. User implementation of IR in CT imaging requires further work to achieve the dose reduction benefits claimed in product marketing and individual feasibility studies.


Reconstruction, Dose, CT


IM- CT: General (Most aspects)

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