Choonsik Lee PhD, Presenter: Nothing to Disclose

Jiamin Liu PhD, Abstract Co-Author: Nothing to Disclose

Jianhua Yao PhD, Abstract Co-Author: Royalties, iCAD, Inc

Les Roger Folio DO, MPH, Abstract Co-Author: Nothing to Disclose

Ronald M. Summers MD, PhD, Abstract Co-Author: Royalties, iCAD, Inc Research funded, iCAD, Inc Stockholder, Johnson & Johnson Grant, Viatronix, Inc

To establish the feasibility of individualized organ dose calculations in body computed tomography (CT) patients by using semi-automatic segmentation of major organs, scan parameters abstracted from DICOM header, CT scanner simulation model, and Monte Carlo transport in high-speed parallel computing system.

We used the abdominal CT images (four male and five female) of patients, ranging in age from 19 to 46 years, sampled from our clinical PACS. First, we contoured 6 organs and tissues using threshold (body contour and skeleton) and Multi-Atlas Label Fusion (left and right kidneys, pancreas, spleen, and liver) techniques. Second, scan parameters (scanner model, average mAs, and tube potential) were automatically abstracted from DICOM headers by using an in-house script. Parameters and patient contours were coupled with a CT scanner simulation model within a Monte Carlo transport code, MCNPX2.7. Organ doses for kidneys, pancreas, spleen, and liver were estimated using a hi-speed 32-processor computing server.

The automatic segmentation, data abstraction, and Monte Carlo calculation took about an hour for each patient. All organs were completely included within the scan coverage. The coefficient of variations in organ volumes across the 9 patients were 20, 13, 34, and 26 % for liver, kidneys, spleen, and pancreas, respectively. When organ dose was normalized to mAs, the maximum dose (mGy/mAs) to each organ was from 1.2- (liver) up to 2.5-fold (spleen) greater than the minimum dose among the 9 patients. The dose discrepancy may be attributed to different locations/shapes of organs and body size. When patient-specific mAs was multiplied, the maximum dose to spleen was up to 3.5-fold greater than the minimum dose.

Our pilot study presented the feasibility to calculate patient-specific organ dose from segmented patient anatomy coupled with fast Monte Carlo calculation. The comparison of organ dose (normalized to mAs) revealed significant variation (over 2.5-fold) in all patients even though they were all adults and the organs were completely included into the scan coverage.

We presented an important step towards estimating true patient dose. We are currently working to apply our method to help validate computational phantom-based organ dose in patient dose monitoring.

Lee, C, Liu, J, Yao, J, Folio, L, Summers, R, Individualized Organ Dose Calculations for Body CT Patients from Automatically Segmented Anatomy Coupled with Fast Monte Carlo Transport.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14011326.html