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Session: Therapy General ePoster Viewing [Return to Session]

Evaluation of the Dosimetric Difference Between Eclipse 16.1 and Eclipse 15.6

L Zhuang1*, Y Qin2, (1) Northwestern Medicine Mchenry Hospital, Mchenry, IL, (2) Northwestern Medicine Delnor hospital, Warrenville, IL


PO-GePV-T-298 (Sunday, 7/10/2022)   [Eastern Time (GMT-4)]

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Purpose: To evaluate the dosimetric difference of Eclipse V16.1 from Eclipse V15.6 for both AAA and EMC algorithms.

Methods: Eclipse’s most updated version 16.1 was evaluated in a community hospital clinically implemented Eclipse 15.6. Photon energies including 6X, 10X, 15X, 6FFF and 10FFF along with Electron energies including 6E, 9E, 12E, 16E & 18E were evaluated. Symmetric/Asymmetric/Oblique fields Photon and symmetric field Electron plans were conducted on solid water phantom (30x30x30cm3) and calculated with 1mm dose grid for V15.6 and V16.1 comparison. Coronal and transverse dose planes from photon plans was exported for comparison in SNC patient with Gamma passing rate (GPR) of 1%/1mm/0% threshold. Point dose comparison was used for electron plan comparison. Ten patients’ clinical plans were recalculated in version 16.1 using the same MUs and coronal and transverse dose planes were compared in SNC machine with GPR of 1%/1mm/0% threshold.

Results: Electron point dose matched 0.7±1.0% (mean ± std) with a max of 2.3% or 5MU. The GPR of Photon dose plane comparison was 99.9±0.2% (mean ± std) and large difference was presented within 2mm under surface. Patient plan comparison agreed with phantom plan comparison with GPR of 99.9±0.1% (mean ± std). Before and post upgrade PDDs were extracted from the water phantom to evaluate the impact of surface dose difference. It was noticed the PDD dose difference reduced to below 2% difference beyond depth of 2mm and 1% difference beyond depth of 3mm for all photon energies, and the major surface dose difference (2%) lies within a dose grid of 2mm. Per Varian, the difference was due to a modification of AAA algorithm involving a half voxel shift in calculation and the strategy to minimize memory consumption.

Conclusion: Eclipse 16.1 is comparable to 15.6 although the calculated surface dose maybe slightly different but not clinical significant.


Not Applicable / None Entered.


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