19 March 2013 Intensity Modulated CT implemented with a dynamic bowtie filter
Author Affiliations +
Proceedings Volume 8668, Medical Imaging 2013: Physics of Medical Imaging; 866818 (2013) https://doi.org/10.1117/12.2005923
Event: SPIE Medical Imaging, 2013, Lake Buena Vista (Orlando Area), Florida, United States
Current advances in CT dose reduction and image quality improvement mechanisms rely on moving towards a more patient / image specific approach. For example, statistical reconstruction algorithms tailor reconstruction weights to patient attenuation values and CT protocols make use of different kVp and mAs settings for different body regions and sizes. In this paper, for the first time to our knowledge, experimental results are presented in which a dynamic bowtie filter was used to tailor the imaging dose during a CT acquisition. The device used to implement a dynamic bowtie is referred to as a digitial beam attenuator (DBA). A non-DBA (non-modulated) CT scan was also performed for comparison. At half of the imaging dose, the noise uniformity of the DBA CT images was 37% better than the non-DBA scan. The use of a dynamic bowtie filter may also prove useful in photon counting CT (PCCT) where high fluence rates and large differences in fluence across projections and from view to view make implementing PCCT difficult. Results are presented in this paper showing dynamic range requirements of 7.9 and 13.8 for DBA and non-DBA scans respectively. The results also show that when using the DBA, the dose delivered can be reduced by 1.9 times for the small phantom used in this study. The differences in dynamic range and dose are somewhat small compared to what would be seen clinically due to the small size of the phantom used in the study. Using a more clinically relevant phantom, dynamic range differences of 22 times and dose reductions on the order of 4 times can be observed in which the effects of the DBA will be more dramatic.
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Timothy P. Szczykutowicz, Timothy P. Szczykutowicz, Charles Mistretta, Charles Mistretta, "Intensity Modulated CT implemented with a dynamic bowtie filter", Proc. SPIE 8668, Medical Imaging 2013: Physics of Medical Imaging, 866818 (19 March 2013); doi: 10.1117/12.2005923; https://doi.org/10.1117/12.2005923

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