RT Journal Article
SR Electronic
T1 Implementation of Automated Tube Current Modulation in PET/CT: Prospective Selection of a Noise Index and Retrospective Patient Analysis to Ensure Image Quality
JF Journal of Nuclear Medicine Technology
JO J. Nucl. Med. Technol.
FD Society of Nuclear Medicine
SP 83
OP 90
DO 10.2967/jnmt.110.075283
VO 39
IS 2
A1 James Jackson
A1 Tinsu Pan
A1 Elena Tonkopi
A1 Nancy Swanston
A1 Homer A. Macapinlac
A1 Eric M. Rohren
YR 2011
UL http://tech.snmjournals.org/content/39/2/83.abstract
AB Automated tube current modulation (ATCM) has been shown to be a useful tool for reducing CT dose. However, its implementation can be complicated, because the correlation between noise index (NI) settings and noise production can change as parameters are manipulated. The goal was to create a methodology to prospectively select ATCM parameters and retrospectively ensure consistent image quality. Methods: An anthropomorphic phantom was scanned at various NIs to determine a baseline NI versus image noise. The noise was measured in SDs of the CT number reported in Hounsfield units. A physician then reviewed 45 studies performed with the same fixed-tube-current protocol to obtain a preferred noise level. The noise level was compared with our phantom baseline scans to find a suitable NI value. This value was implemented in clinical operation. Then, the next 50 patient examinations were retrospectively reviewed to ensure that image quality was maintained to our physician's cutoff noise levels. Radiation dose reductions through tube current reduction were measured for all CT slices of each patient study. Results: In the phantom study, tube current modulation was observed at an NI of 15. The preferred noise level established in the physician's review correlated with an NI of 20. In our postimplementation analysis, we found that our noise level was 10.75 SDs in Hounsfield units. CT dose reductions of up to 52% were seen. Conclusion: We were able to prospectively select an NI for ATCM CT by correlating phantom scans to a physician's preferred noise level while maintaining consistent image quality.