| Summary: | <p><strong>Purpose: </strong>To evaluate the low contrast detectability sensitivity among 4-slice, 8-slice and 16-slice CT units using various mAs settings. Findings of the study may elucidate the most optimal imaging parameter for stereotactic radiosurgery (SRS) patients who are not MRI compatible.</p><p><strong>Methods and Materials</strong>: Low contrast targets in the CATPHAN phantom (model: CTP 504, The Phantom Laboratory) were imaged on a 4-slice LightSpeed Advantage™ GE CT scanner (GE Healthcare, WI) and a 16- slice LightSpeed Advantage™ GE CT scanner (GE Healthcare, WI) in 8-slice and 16-slice mode. The CATPHAN CTP515 low contrast targets of size 15, 9, 8, 7, 6, 5, 4, 3 and 2 mm for each contrast difference of 1%, 0.5% and 0.3% from the water-equivalent background was imaged using a SRS protocol. Two image sets per setting were acquired for mAs parameters of 300, 350 and 440. Images were evaluated in a blind study by three independent reviewers.</p><p><strong>Results: </strong>Using 300,350 and 440mAs settings on the 4-slice scanner, the average smallest diameters recorded at 1% contrast were 5 ± 1 mm, 5 ± 1 mm and 5 ± 0 mm and at 0.5% were 7 ± 2 mm, 7 ± 1 mm and 6 ± 1 mm. For the 8 - slice scanner, the average smallest diameters recorded at 1% contrast were 7 ± 0 mm, 6 ± 0 mm and 5 ± 0 mm, and at 0.5% were 12 ± 3 mm, 9 ± 1 mm and 6 ± 1 mm. For the 16 - slice scanner, the average smallest diameters recorded at 1% contrast were 7 ± 1 mm, 7 ± 1 mm and 6 ± 1 mm, and at 0.5% were 11 ± 3 mm, 8 ± 1 mm and 8 ± 1 mm. A difference was observed between the 4 and 8 - slice scanners at 300mAs (p < 0.01) for each contrast level as well as the 4 and 16 slice at 440 (p < 0.01) and 350 (p < 0.01) mAs. Additionally, a difference was observed between each mAs for the 8 slice at 1% (p < 0.01) and 0.5% (p < 0.01) contrast.</p><p><strong>Conclusion</strong>: Results demonstrate consistently improved low contrast detectability as mAs was increased. CT simulation imaging parameters can be optimized to improve low contrast sensitivity for non MRI compatible SRS patients.</p><p>----------------</p><p><strong>Cite this article as</strong>: Stanley D, Narayanasamy G, Breton C, Papanikolaou N, Gutierrez AN. Comparison of low contrast sensitivity among multi-slice CT units using various mAs setting for the potential benefit of non-MRI compatible, stereotactic radiosurgery (SRS) patients. Int J Cancer Ther Oncol 2014; 2(2):020237. <strong>DOI: 10.14319/ijcto.0202.37</strong><br /><br /><br /></p>
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