Jennifer LC Cullmann, Presenter: Nothing to Disclose

Khoschy Schawkat MD, Abstract Co-Author: Nothing to Disclose

Daniel Ott MD, Abstract Co-Author: Nothing to Disclose

Stefan Puig MD, MSc, Abstract Co-Author: Nothing to Disclose

To evaluate the potential reduction of radiation dose in pediatric body CTs after implementation of a new fully-integrated-digital detector (Stellar®, Siemens Healthcare, Germany) compared with a conventional “Ultra-Fast-Ceramic” (UFC) solid-state-detector.

152 routine CT examinations (112 thoracal, 8 abdominal and 32 thoracoabdominal) of 114 children (58 male, 56 female) between 1 day and 16 years of age were included in the analysis. The following parameters were recorded: age, scan length, maximum body diameter, and CTDIvol, dose-length-product (DLP). The effective radiation dose (ED) was estimated from the DLP and an organ weighting factor (k): ED[mSv] ≈ k × DLP[mGy×cm]. All examinations were performed on a single dual source multi-detector CT (Somatom Definition Flash; Siemens Healthcare, Erlangen, Germany), 93 examinations before the exchange of the detector unit, with a UFC solid-state-detector, and 59 with the new digital Stellar®-detector. The scanning protocols were kept the same before and after replacement of the detector unit. Independent two-sample t-tests were used to assess statistical differences, the level of significance was defined as p ≤ .05.

Age and body diameter did not show significant differences in both groups. The mean CTDIvol was about 16% lower after detector change (1.77 vs. 1.52 mSv). However, this difference was statistically not significant (p=.30). The mean ED was significantly lower with the digital Stellar detector (0.74 mSv ± .6) compared with the previous UFC solid-state-detector (1.09 mSv ± 1,3) (p=0.02). This was obviously mainly achieved due to a significantly lower mean scan-length of 270 mm ± 123.6 vs. 231mm ± 89.5 (p=.3) resulting in a significantly lower DLP: 70.2 mGy×cm ± 88.4 vs. 45.2 mGy×cm ± 41.6 (p=.02).

Fully digital Stellar® detector may achieve a mild reduction of radiation in pediatric patients. However, the main difference of the DLP was due to differences of the scan length before and after exchange of the detector unit.

There may be some radiation dose reduction due to fully digital detectors. However, other factors such as scan length still have a major influence on radiation dose.

Cullmann, J, Schawkat, K, Ott, D, Puig, S, Dose Reduction in Pediatric Body-CT due to Fully-integrated-Digital "Stellar®" Detector.  Radiological Society of North America 2013 Scientific Assembly and Annual Meeting, December 1 - December 6, 2013 ,Chicago IL. http://archive.rsna.org/2013/13026344.html