Performance assessment of four 64-slice computed tomographic devices for a typical clinical protocol

To compare the performances of four 64-slice CT devices, as regards radiation dose and image quality. Effective dose was measured with thermoluminescent dosimeters in an Alderson Rando phantom (Alderson Research Laboratories, New York, NY). Quantitative image quality was evaluated in a Catphan 600 phantom (The Phantom Laboratory, New York, NY) using 3 parameters (modulation transfer function, contrast-to-noise ratio, and figure of merit). Effective and main organ doses were measured in 40 patients (10 for each CT device), who underwent an abdominal study with the same standard protocol; moreover, in these patients, clinical image quality, using a 5-grade quality score, was assessed. In-phantom measured doses and quantitative image quality showed some differences among the 4 devices. On the contrary, effective and organ doses provided to the patients were similar; no statistically significant differences were found also for clinical image quality. Some differences were found among the 4 devices from a physical point of view; on the other hand, the patient data were similar.