Les Roger Folio DO, MPH, Presenter: Nothing to Disclose

Peter L. Choyke MD, Abstract Co-Author: Researcher, Koninklijke Philips NV Researcher, General Electric Company Researcher, Siemens AG Researcher, iCAD, Inc Researcher, Aspyrian Therapeutics, Inc Researcher, ImaginAb, Inc Researcher, Aura

To minimize radiation dose on multiphase CT exams while maintaining diagnostic quality by 1) eliminating the pre-contrast pass and 2) reducing mAs and 3. applying iterative reconstruction. We also share a streamlined workflow, processing Virtual Non Contrast (VNC) across vendors.  

We compared radiation exposures of 22 consecutive multiphase chest, abdomen and pelvis CTs in patients with Von Hippel Lindau (VHL), to determine amount of total DLP reduction relative to prior exams. Tube current reduction (from 240mAs to 150 mAs) effects were compensated for noise using iterative reconstruction (SAFIRE, Siemens Medical, Malvern, PA) with an iterative strength of 2 (of 5 strengths available). The reduced exposure exams were performed on Siemens Flash in Dual Energy mode while the VNC was processed on Siemens PACS (Syngo.via) then pushed to our PACS (Carestream Health, Rochester, NY). Radiologists and referring clinicians compared the quality of mAs reduced exams and VNC series to prior actual non-contrast series and overall scan quality.

Eliminating the non-contrast scan and applying iterative reconstruction resulted in an average exposure reduction of more than 50% (avg 59.9%) while maintaining diagnostic quality. VNC was limited in larger patients (FOV of 80 kVp tube is only 33 cm), causing incomplete analysis of a small portion of one kidney in one patient. Workflow was streamlined by co-locating a PACS node next to the CT console. 

Significant dose savings on multiphase CT exams were achieved by replacing the non-contrast phase with a VNC exam, reducing tube current and compensating for noise with iterative reconstruction. This resulted in greater than 50% exposure reduction when compared to previous exams in the same patients, while maintaining image quality. 

Multiphase exams are of clinical importance, however, expose patients to higher doses of radiation. Replacing the non-contrast images with a VNC, while using tube current reductions/iterative reconstruction can provide substantial dose savings; especially in patients that receive frequent surveillance exams.

Folio, L, Choyke, P, Radiation Exposure Reduction on Multiphase Dual Energy CT Exams: How Virtual Non-Contrast Combined with Iterative Reconstruction Cut Doses in Half.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14004171.html