Kristen Barry Thomas MD, Presenter: Nothing to Disclose

Richard William Rittenhouse DO, Abstract Co-Author: Nothing to Disclose

Lifeng Yu PhD, Abstract Co-Author: Research grant, Xoran Technologies, Inc

Cynthia H. McCollough PhD, Abstract Co-Author: Research grant, Siemens AG Research grant, RTI Electronics AB Research grant, Bayer AG

Alisa Ingrid Walz-Flannigan PhD, Abstract Co-Author: Nothing to Disclose

Jodie A. Christner PhD, Abstract Co-Author: Grant, Siemens AG

Thomas J. Vrieze RT(R), Abstract Co-Author: Nothing to Disclose

Joel Garland Fletcher MD, Abstract Co-Author: Research grant, Siemens AG Grant, E-Z-EM, Inc License agreement, General Electric Company

et al, Abstract Co-Author: Nothing to Disclose

To develop and optimize a weight-based reduced-kV technique chart for pediatric body CT.

A novel noise-insertion method was developed and validated to simulate reduced-dose CT images at four kV levels and a wide range of patient sizes. With this tool, we used a three-step method to develop and optimize a reduced-kV technique chart for pediatric body CT. First, we simulated images with 25%, 50%, 70%, and 90% of the original dose level for 12 pediatric exams scanned using our 120 kV techniques. Two pediatric radiologists evaluated image quality to determine the lowest acceptable dose level for each exam. Second, noise as a function of dose was determined using nine acrylic phantoms (diameter range: 8.7 to 26 cm) at 80, 100, and 120 kV. The lowest acceptable doses at 120 kV (from step 1) were converted to noise-matched dose values at 80 kV and 100 kV for each phantom size. The attenuation of each phantom was translated into a corresponding patient weight for the technique chart. Third, we refined the reduced-kV technique chart clinically in order to take into account the increased iodine contrast enhancement at lower kV settings. Using the technique chart from step 2, 14 pediatric body cases were scanned with reduced-kV techniques (7 with 80 kV, 7 with 100 kV). Then, similar to step 1, we simulated images with 25%, 50%, 70%, 90% of the original dose level for these reduced-kV cases. Two pediatric radiologists evaluated image quality to determine the lowest acceptable dose levels for the 80 kV and 100 kV cases, resulting in the final reduced-kV technique chart.

The described iterative technique for creating a reduced-kV technique chart allowed for determination of the lowest dose settings consistent with clinical acceptance. In preliminary results, the dose reduction and optimal kV setting were, respectively: 36-67% and 80 kV for patients less than 10 kg; 46-66% and 100 kV for patients between 10 kg and 20 kg; 30-50% and 120 kV for patients between 20 kg and 45 kg.

A three-step iterative optimization method was used to develop reduced-kV protocols for pediatric body CT. Dose reductions of 30-67% were achieved while maintaining clinically acceptable image quality.

The development of optimal reduced-kV technique charts requires an iterative approach and can substantially reduce radiation dose for pediatric CT.

Thomas, K, Rittenhouse, R, Yu, L, McCollough, C, Walz-Flannigan, A, Christner, J, Vrieze, T, Fletcher, J, et al, , Creation and Implementation of Reduced-kV Pediatric Body CT Protocols.  Radiological Society of North America 2008 Scientific Assembly and Annual Meeting, February 18 - February 20, 2008 ,Chicago IL. http://archive.rsna.org/2008/6012868.html