Program Information
Similarity Analysis of the Linear Accelerator Machines Based On Clinical Simulation
K Li1,2*, (1) Associates In Medical Physics, Lanham, MD, (2) John R Marsh Cancer Center
Presentations
SU-F-P-51 (Sunday, July 31, 2016) 3:00 PM - 6:00 PM Room: Exhibit Hall
Purpose: To evaluate the clinical rationale for Truebeam and Trilogy Linac machines from Varian Medical System as exchangeable treatment modalities in the same radiation oncology department.
Methods: Intensity Modulated Radiotherapy (IMRT) plans for different diseases were selected for this study. These disease sites included brain, head and neck, breast, lung, and prostate. The parameters selected for this study were the energy amount, Monitor Unit (MU); dose coverage of target reflected by prescription isodose volume(PIV); dose spillage described by the volume of 50% isodoseline of the prescription; and dose homogeneities represented by the maximum dose (MaxD) and the minimum dose (MinD) of target volume (TV) and critical structure (CS). Each percentage difference between the values of these parameters formed an element of a matrix, which was called Similarity Comparison Matrix(SCM). The elements of the SCM were then simplified by dimensional conversion algorithm, which was used to determine clinical similarity between two machines through a single value.
Results: For the selected clinical cases in this study, the average percentage differences between Trilogy and Truebeam in MU was 0.28% with standard deviation(SD) 0.66%, PIV was 0.23% with SD 0.20%, Volume at 50% prescription dose was 0.31% with SD at 0.78%, MaxD at TV is 0.26% with SD 0.35%, MinD at TV is -0.04% with SD 0.51%, MaxD in CS is -0.53% with SD 0.92%, and MinD in CS 3.31%, with SD at 2.89%. The sum, product, geometric and harmonic mean for the matrix elements were 19.0%, 0.00%, 0.19%, and 0.00%.
Conclusion: A method to compare two machines in clinical level was developed and some reference values were calculated for decision-making in clinical practice, and this strategy could be expanded to different clinical applications.
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