Thomas Henzler MD, Presenter: Nothing to Disclose

Hashim Jafarov MD, Abstract Co-Author: Nothing to Disclose

Mathias Meyer, Abstract Co-Author: Nothing to Disclose

Paul Apfaltrer MD, Abstract Co-Author: Nothing to Disclose

Stefan A Klein, Abstract Co-Author: Nothing to Disclose

Stefan Oswald Schoenberg MD, PhD, Abstract Co-Author: Nothing to Disclose

Christian Fink MD, Abstract Co-Author: Nothing to Disclose

Patients with lymphoma are at higher-risk for secondary malignancies due to radiotherapy and frequent follow-up-staging-CTs (average >200 mSv). Thus, the aim of this study was to prospectively investigate quantitative and subjective image quality of full-dose-standard (FDS), full-dose-iterative (FDI) and half-dose-iterative (HDI) reconstructions in patients with malignant lymphoma.

To acquire full-dose and half-dose-CT simultaneously, contrast-enhanced-whole-body staging-CT was performed with a dual-source (DS) CT, operating both tubes at 120 kV with the total mAs equally distributed on both tubes. CTDI and dose length product of the scan were equal to the standard institutional protocol. For FDS and FDI reconstructions data of both tubes were used whereas HDI reconstructions were calculated by using only data from tube A of the DSCT-system (50% of total mAs). Image quality was quantitatively assessed by measuring image noise in different tissues of the neck, thorax and abdomen. Overall diagnostic image quality was assessed by two radiologists using a 5-point-Likert-scale. In addition, the three different reconstructions of any anatomic area were ranked by two radiologists (1-3, 1 being the best). Differences between reconstruction techniques were compared.

Image noise significantly decreased in all anatomic regions when FDI and HDI (-32%;-21%, respectively) was compared to FDS reconstructions (all p<0.05) (see figure). Image quality of FDI (median 5) and HDI (median 4) was rated significantly higher when compared to FDS (median 3) reconstructions (both p<0.05). FDI was ranked as the best reconstruction in 78%, HDI second best in 75% and FBP as the third best reconstruction technique in 94% (all p<0.05).

Subjective and objective image quality of FDI and HDI appear to be superior to FDS reconstruction, thus enabling dose reduction in whole-body lymphoma staging-CT.

Iterative image reconstruction allows 50% dose reduction for whole-body lymphoma staging CT, thus potentially decreasing the risk for radiation-induced secondary malignancies.

Henzler, T, Jafarov, H, Meyer, M, Apfaltrer, P, Klein, S, Schoenberg, S, Fink, C, Feasibility of 50% Dose Reduction in Whole-Body Lymphoma Staging CT Using Iterative Reconstruction.  Radiological Society of North America 2012 Scientific Assembly and Annual Meeting, November 25 - November 30, 2012 ,Chicago IL. http://archive.rsna.org/2012/12043881.html