Kavita Gulati MD, Presenter: Nothing to Disclose

Mannudeep Karanvir Singh Kalra MD, Abstract Co-Author: Research grant, General Electric Company

Michael Austin Blake MBBCh, Abstract Co-Author: Nothing to Disclose

Michael Stanley Gee MD, PhD, Abstract Co-Author: Nothing to Disclose

Mark Walters, Abstract Co-Author: Nothing to Disclose

Thomas Louis Toth, Abstract Co-Author: Employee, General Electric Company

Dushyant V. Sahani MD, Abstract Co-Author: Researcher, General Electric Company

Keith J. Dreyer DO, PhD, Abstract Co-Author: Employee, Perceptics, LLC Medical Advisor, Perceptics, LLC Medical Advisor, Agfa-Gevaert Group Medical Advisor, FUJIFILM Holdings Corporation Medical Advisor, General Electric Company Medical Advisor, McKesson Corporation Medical Advisor, AuntMinnie.com Medical Advisor, AMICAS, Inc Medical Advisor, Dynamic Imaging, LLC Medical Advisor, Ascom Holding AG Medical Advisor, Bracco Group Medical Advisor, Merge Healthcare Medical Advisor, Emageon, Inc Medical Advisor, RCG HealthCare Consulting Medical Advisor, Valley Radiology Medical Associates, Inc Medical Advisor, The Elizabeth Wende Breast Clinic Medical Advisor, ISCI Medical Advisor, Siemens AG Medical Advisor, Barco nv Medical Advisor, Hue AS Medical Advisor, Planar Systems, Inc Medical Advisor, Vital Images, Inc Medical Advisor, Commissure, Inc Medical Advisor, TeraRecon, Inc Medical Advisor, Mercury Computer Systems, Inc Medical Advisor, IBM Corporation Medical Advisor, Hewlett-Packard Company Medical Advisor, EMC Corp Medical Advisor, Phase Forward Incorporated Medical Advisor, Winchester Systems, Inc Medical Advisor, Dell Inc Medical Advisor, Eastman Kodak Company Medical Advisor, Amirsys, Inc Medical Advisor, Reed Elsevier Committee member, Diagnostic Imaging Committee member, AuntMinnie.com Committee member, Imaging Economics Author, Springer Science+Business Media Deutschland GmbH Shareholder, Microsoft Corporation Shareholder, Intel Corporation Shareholder, IBM Corporation Shareholder, Hewlett-Packard Company Shareholder, Dell Inc Shareholder, General Electric Company Shareholder, Siemens AG Shareholder, Google Inc

et al, Abstract Co-Author: Nothing to Disclose

The purpose of our study was to assess the diagnostically acceptable level of radiation dose reduction for detection of subtle lesions on abdominal CT with the help of noise projection software and dose trainer application.

This IRB approved ongoing study included 40 patients (mean age:53.3, 22M: 18 F) with an abdominal CT study from (Jan’07-Feb’08), having subtle (<1 cm or isoattenuating with organ of origin) lesions. Set of routine DICOM images (kV 140, mA 50-500, slice thickness 5mm) showing pathology were extracted and were processed with the noise projection software to create five series of simulated 15% (mA 66-466, mean 259.9), 30% (mA 55-384, mean 211.9), 45% (mA 43-301, mean 167.3), 60% (mA 31-219, mean 121.8), 75% (mA 20-137, mean 76.8) dose reduction per case. All image series were viewed on the dose trainer (Win32 CSharp) application. Two abdominal radiologists, blinded to dose levels, independently reviewed the randomized standard and simulated low radiation dose images. Readers graded the image noise, diagnostic acceptability and lesion conspicuity. Objective noise and CT number were measured in each series with the same region of interest (ROI). Statistical analysis was performed using student’s t-test and Wilcoxon Signed rank test. Level of dose-reduction acceptable to both readers was assessed.

Average objective noise with 30% (20), 45% (21), 60% (24), 75% (30) reduced dose was significantly higher than standard dose series (16.7) (p<0.03). Total 45 lesions were identified on standard dose series with average lesion size of 1 cm. Both readers found that 45% reduced dose series was diagnostically acceptable but had more than usual noise in 25 of 45 lesions (p<0.0001), whereas diagnostic acceptability and image noise at 60%, 75% reduced dose series were suboptimal for 39 of 45 lesions (p<0.0001).

Use of noise projection software and dose trainer application suggests that CT radiation dose can be reduced by upto 45% without compromising the image quality and diagnostic acceptability.

The radiation dose, even if reduced to 45% of current protocols in abdominal CT studies, can be diagnostically acceptable for subtle lesions.

Gulati, K, Kalra, M, Blake, M, Gee, M, Walters, M, Toth, T, Sahani, D, Dreyer, K, et al, , Evaluation of Diagnostic Acceptability of Low Dose Abdominal CT Exams: An Alternative Approach.  Radiological Society of North America 2008 Scientific Assembly and Annual Meeting, February 18 - February 20, 2008 ,Chicago IL. http://archive.rsna.org/2008/6012725.html