Program Information
Quantifying Organ Dose and Improving Image Quality in CT Exams of Subjects with Metal Implants Utilizing a Metal-Artifact Reduction Algorithm
I Lipnharski*, C Carranza , A Mench , R Lamoureux , B Cormack , S Bidari , L Rill , M Arreola , University of Florida, Gainesville, FL
Presentations
MO-B-BRD-4 (Monday, March 9, 2015) 10:00 AM - 12:00 PM Room: Ballroom D
Purpose:
To evaluate the effect of metal implants on organ doses and image quality in CT examinations utilizing post-mortem subjects.
Methods:
Three similar sized adult female post-mortem subjects were scanned on a commercial 320-slice scanner using a chest-abdomen-pelvis protocol. One subject presented metal implants, specifically in the sternum, lumbar, and pelvic regions. All subjects had optically stimulated luminescent dosimeters inserted into various organs, and were scanned using a helical 0.5 mm x 80 detector setting, reconstructed with an iterative algorithm (AIDR). CTDIvol, DLP, and organ doses were recorded for each scan. The subject containing implants was additionally scanned using a volumetric 0.5 mm x 320 detector setting, reconstructed with AIDR and an artifact reduction algorithm (SEMAR). Image noise was measured for each image series, and image quality was assessed by means of a blind observer study by experienced radiologists.
Results:
The scans of the two implant-free subjects demonstrated similar doses. Their reported CTDIvols were 6.6 mGy and 6.8 mGy, with a maximum dose difference of 1.9 mGy in the stomach. The scans on the subject containing implants resulted in a higher CTDIvol of 9.7 mGy, and increased dose differences of 3.0 mGy in the stomach, 3.2 mGy in the small intestine, 2.5 mGy in the colon, and 2.3 mGy in the ovaries, relative to an implant-free subject,. All images were graded to be of diagnostic quality, with the exception of the pelvic region of the subject with hip implants, exhibiting streaking artifacts. Image quality was improved significantly without the need for dose increases when SEMAR reconstruction was employed, improving visualization of the soft tissue and bone structures surrounding metallic implants.
Conclusion:
Patients containing metallic implants may locally experience increased organ doses and impaired image quality. Image quality and diagnostic capabilities may be improved by utilizing metal artifact reduction reconstruction algorithms.
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