Yasir Andrabi MD, MPH, Presenter: Nothing to Disclose

Saajed Ali, Abstract Co-Author: Nothing to Disclose

Sabiha A Wadoo, Abstract Co-Author: Nothing to Disclose

Manuel Patino MD, Abstract Co-Author: Nothing to Disclose

Jorge Mario Fuentes MD, Abstract Co-Author: Nothing to Disclose

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

To investigate the feasibility and accuracy of Size Specific Dose Estimate (SSDE) calculation based on CTDI and body weight (BW) in comparison to conventional effective diameter based SSDE calculation.

In this IRB approved study, 10581 abdomen CT exams performed between June 2013 and February 2014 were retrieved using dose monitoring software (DMS, eXposure, Radimetrics). DMS automates SSDE measures by determining the effective body diameter at mid-axial line. To validate the accuracy and reproducibility of DMS generated SSDE, in 300 consecutive abdomen CT exams, SSDE was manually calculated. The 10,281 remaining exams were divided into 3 groups: Group A=4000, Group B=6000 and Group C=281 exams; in group A, a correlation between SSDE based on CTDI and BW was determined and a formula best fitting the curve was derived. The accuracy of the derived formula was then determined by comparing the formula based SSDE with DMS generated SSDE in Group B and manually calculated SSDE in Group C.

A strong correlation between DMS and manually calculated SSDE was established (R2=0.93, p<0.0001).2) A power curve was estimated between SSDE and CTDI after correcting for BW (Multiple R=0.95, R2=0.9 and p<0.0001). The formula SSDE = 2.3987×CTDI0.7749 – e (where e=0.0549×Weight + 4.5099) was derived. The SSDE values generated using this formula showed a positive correlation with the DMS generated SSDE (Group B) ( N=6000, R=0.87, R2 =0.76) and manually derived SSDE (Group C) (N=281, R=0.94, R2=0.87).

The DMS generated SSDE values are reliable and accurate. By applying a formula based on patient’s body weight and CTDI one can reliably measure SSDE similar to DMS generated value. This formula can be a reliably estimate for SSDE reporting especially for large patient cohorts when automated solutions are not available.

SSDE has been introduced as a reliable dose metric; however, its calculation is not feasible especially while reporting doses in large patient cohorts. In absence of automated solution, this formula which incorporates readily available CTDI and patient’s BW can make SSDE calculation and reporting timely and feasible.

Andrabi, Y, Ali, S, Wadoo, S, Patino, M, Fuentes, J, Sahani, D, Can an Estimation Based on CTDI and Body Weight Replace the Conventional Diameter Based Approach for SSDE Calculation? Can a Simple CTDI and Body Weight Based Estimation Serve as a Reliable Alternative for Body Diameter Based Approach for Size Specific.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14046032.html