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Variations of Dose Volume Histogram Calculated Using MiM and Eclipse Software

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H Geng

H Geng1*, H Zhong1 , M Huang1 , F O'Grady1 , C Cheng1 , S Ryu2 , F Yin3 , Y Xiao1 , (1) University of Pennsylvania, PA,(2) Stony Brook University Hospital, Stony Brook, NY, (3) Duke University Medical Center, Durham, NC


SU-I-GPD-T-391 (Sunday, July 30, 2017) 3:00 PM - 6:00 PM Room: Exhibit Hall

Purpose: MiM software has been used for NCI Clinical Trials Network (NCTN) radiotherapy plan evaluation and reporting. However, the uncertainties about dose calculation between the on-site planning and reporting systems is not well documented. This study is to evaluate dose volume histogram (DVH) calculation discrepancies from MiM software and Eclipse using both published DICOM files based on phantoms and real patient data submitted to RTOG 0631.

Methods: A set of published DICOM files of CTs with different spatial resolutions, simple geometrical RT structures together with dose grids of varying spatial resolutions were used for analytical study. Dose volume points of Dmin, Dmax, Dmean, D99%, D95%, D5%, D1% and D0.03cc of all the structures were calculated in MiM, Eclipse and compared with published data (gold standard). 31 RTOG 0631patient plans submitted to NCTN were also used for the study.

Results: Analytical study results show that there was no Mean[Gy] discrepancy larger than 3% for all the evaluations between Eclipse and MiM report. 81% of calculation points for Min[Gy] presented larger than 3% discrepancy between MiM and Eclipse systems. 56% calculation points from both systems reported larger than 3% error compared with gold standard.Patient data analysis reported that 126 calculation points out of total 728 dosimetric points had relative discrepancy between MiM and Eclipse (as normalized to MiM results) larger than 3%. When the absolute dose discrepancy larger than 3% of the prescription dose was considered as the criterion, 33 points out of 698 points met. These 33 points were either for structures with small volume (<30cc) or irregular shapes.

Conclusion: Although the patient data only reported comparison between MiM and Eclipse. Evaluation of plans based on DVH calculation should be performed with caution, especially for structures with small volumes and irregular shapes. Min[Gy] parameter should be avoided when possible.

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