Document Detail

Spatial resolution and radiation dose of a 64-MDCT scanner compared with published CT urography protocols.
MedLine Citation:
PMID:  19304698     Owner:  NLM     Status:  MEDLINE    
OBJECTIVE: The objective of our study was to compare the spatial resolution and effective dose from 64-MDCT with several published CT urography protocols. MATERIALS AND METHODS: A phantom containing 1-, 2-, or 4-mm cylindric channels to simulate ureters with 0.25- to 3-mm plugs to simulate ureteral filling defects or ureteral diverticula was imaged using eight helical CT urography protocols. Computed radiography (CR) was also performed. Coronal maximum-intensity-projection images were created and, with the CR image, were evaluated independently by two genitourinary radiologists. Spatial resolution was evaluated by scoring each abnormality as present, visible; or as absent, not visible. Effective dose estimates for 11 CT urography protocols, including the radiographs obtained in the CT urography protocol, were calculated using published Monte Carlo organ dose coefficients. RESULTS: All ureteral abnormalities detected on CR were detected on the highest-spatial-resolution reconstruction using the evaluated 64-MDCT system. The smallest filling defect identified by both was 0.25 mm. Three 0.25-mm filling defects were not detected using the evaluated 16-MDCT system. The 4-MDCT system protocols showed the poorest performance. The range of effective doses for the evaluated CT urography protocols was 20.1-66.3 mSv. The number of phases, anatomic coverage per phase, and scanning parameters all contributed to this variation in dose. CONCLUSION: The evaluated 64-MDCT system showed detection accuracy identical to that of CR. Limiting anatomic coverage for specific phases and combining phases can reduce dose for multiphase protocols by up to a factor of 2 relative to early (circa 2000) 4-MDCT.
Terri J Vrtiska; Robert P Hartman; James M Kofler; Michael R Bruesewitz; Bernard F King; Cynthia H McCollough
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Publication Detail:
Type:  Comparative Study; Journal Article    
Journal Detail:
Title:  AJR. American journal of roentgenology     Volume:  192     ISSN:  1546-3141     ISO Abbreviation:  AJR Am J Roentgenol     Publication Date:  2009 Apr 
Date Detail:
Created Date:  2009-03-23     Completed Date:  2009-04-16     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  7708173     Medline TA:  AJR Am J Roentgenol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  941-8     Citation Subset:  AIM; IM    
Department of Radiology, Mayo Clinic, 200 First St., SW, Rochester, MN 55905, USA.
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MeSH Terms
Phantoms, Imaging
Radiation Dosage
Tomography, Spiral Computed / methods*
Ureter / radiography*
Urography / methods*

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