Olivia Egan MS, Presenter: Nothing to Disclose

Eugenia Kulama MSc, Abstract Co-Author: Nothing to Disclose

Advanced dose reduction technology allows significant reduction in patient dose without compromising image quality in the Thorax and AbdoPelvis. 

The study investigated the impact of new dose reduction technologies on radiation dose and image noise in the Thorax and AbdoPelvis. A recently introduced software upgrade has been compared to its predecessor on the SOMATOM Definition AS (Siemens Healthcare) scanner. The new software includes number of dose reduction features and related workflow concepts including CARE technology (Combined Applications to Reduce Exposure) and raw-data based iterative reconstruction (IR) called SAFIRE (Sinogram Affirmed Iterative Reconstruction). SAFIRE allows noise reduction and minimises cone-beam artifacts by utilising raw-data information without compromising image sharpness. Both tube current and voltage is adjusted to individual patients with new the software (extension of the CAREDose4D concept).    

Images from 25 Thorax and 25 AbdoPelvis studies were retrospectively evaluated per software version. Patients were of similar size and weight. Identical protocols were used for both versions, however the new software saw both tube voltage adjustment and SAFIRE being used in addition. The effective dose was calculated on individual basis using the ImPACT CT Patient Dosimetry Calculator Excel spreadsheet. Three radiologists blind scored images for image quality. Image noise was measured with standard 200 pixel region of interest in the descending aorta at specific levels in both studies.

By proactively reducing reference mAs and using SAFIRE, radiation doses in AbdoPelvis were reduced from mean effective dose of 9.8mSv to 5.7mSv (˜40%), while image noise and quality was maintained. Radiation doses in Thorax were reduced from mean effective dose 5.7mSv to 3.2mSv (˜45%) but image noise increased by ˜30%. Utilizing tube voltage adjustment saw low tube voltage of 80 or 100 kV being proposed in majority of examinations. Image quality in terms of contrast to noise ratio was maintained however, thus the observed increase in noise was balanced with the increase of contrast within these lower kV exams. No images were deemed non-diagnostic.

Egan, O, Kulama, E, To Investigate the Impact of Dose Reduction Technologies on Radiation Dose and Image Noise in the Thorax and Abdo-Pelvis.  Radiological Society of North America 2011 Scientific Assembly and Annual Meeting, November 26 - December 2, 2011 ,Chicago IL. http://archive.rsna.org/2011/11016658.html