A comparison of three CT voltage optimization strategies

Kent M. Ogden; Walter Huda; Mohammad R. Khorasani; Ernest M. Scalzetti

doi:10.1117/12.773305

25 March 2008 A comparison of three CT voltage optimization strategies

Kent M. Ogden, Walter Huda, Mohammad R. Khorasani, Ernest M. Scalzetti

Proceedings Volume 6913, Medical Imaging 2008: Physics of Medical Imaging; 691351 (2008) https://doi.org/10.1117/12.773305
Event: Medical Imaging, 2008, San Diego, California, United States

Abstract

We evaluated three strategies for optimizing the x-ray tube voltage in chest CT examinations: (1) keeping patient dose constant and maximizing contrast to noise ratios (CNR); (2) keeping CNR constant and minimizing patient effective dose (E); (3) maximizing CNR²/E. Lung and soft tissue Hounsfield unit values, together with the corresponding image noise, were measured in a Rando phantom at x-ray tube voltages between 80 and 140 kV. A CT dosimetry software package (ImPACT) was used to compute effective doses as a function of CT x-ray tube voltage for adult patients undergoing chest CT examinations. CNR and patient dose in chest CT examinations both increase with increasing x-ray tube voltage at a fixed mAs. All optimization strategies provided similar qualitative results, which showed the best imaging performance was achieved at the lowest x-ray tube voltage (80 kV). Optimization using constant CNR or effective dose is preferred since these methods provide explicit choices of optimal kV/mAs combinations, as well as quantitative data on how changing kV would modify CNR and/or patient dose. The CNR²/Dose figure of merit does not offer explicit choices of kV/mAs for performing CT examinations, and changes in FOM value are more difficult to relate to changes in imaging performance or patient dose.

Citation Download Citation

Kent M. Ogden, Walter Huda, Mohammad R. Khorasani, and Ernest M. Scalzetti "A comparison of three CT voltage optimization strategies", Proc. SPIE 6913, Medical Imaging 2008: Physics of Medical Imaging, 691351 (25 March 2008); https://doi.org/10.1117/12.773305

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