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. 2022 Apr;23(4):e13539.
doi: 10.1002/acm2.13539. Epub 2022 Jan 27.

Assessment of efficacy in automated plan generation for Varian Ethos intelligent optimization engine

Shyam Pokharel  1   2 , Abilio Pacheco  1 , Suzanne Tanner  1
Affiliations

Assessment of efficacy in automated plan generation for Varian Ethos intelligent optimization engine

Shyam Pokharel et al. J Appl Clin Med Phys. 2022 Apr.

Abstract

Varian Ethos, a new treatment platform, is capable of automatically generating treatment plans for initial planning and for online, adaptive planning, using an intelligent optimization engine (IOE). The primary purpose of this study is to assess the efficacy of Varian Ethos IOE for auto-planning and intercompare different treatment modalities within the Ethos treatment planning system (TPS). A total of 36 retrospective prostate and proximal seminal vesicles cases were selected for this study. The prescription dose was 50.4 Gy in 28 fractions to the proximal seminal vesicles, with a simultaneous integrated boost of 70 Gy to the prostate gland. Based on RT intent, three treatment plans were auto-generated in the Ethos TPS and were exported to the Eclipse TPS for intercomparison with the Eclipse treatment plan. When normalized for the same planning target volume (PTV) coverage, Ethos plans Dmax% were 108.1 ± 1.2%, 108.4 ± 1.6%, and 109.6 ± 2.0%, for the 9-field IMRT, 12-field IMRT, and 2-full arc VMAT plans, respectively. This compared well with Eclipse plan Dmax% values, which was 108.8 ± 1.4%. OAR indices were also evaluated for Ethos plans using Radiation Therapy Oncology Group report 0415 as a guide and were found to be comparable to each other and the Eclipse plans. While all Ethos plans were comparable, we found that, in general, the Ethos 12-field IMRT plans met most of the dosimetric goals for treatment. Also, Ethos IOE consistently generated dosimetrically hotter VMAT plans versus IMRT plans. On average, Ethos TPS took 13 min to generate 2-full arc VMAT plans, compared to 5 min for 12-field IMRT plans. Varian Ethos TPS can generate multiple treatment plans in an efficient time frame and the quality of the plans could be deemed clinically acceptable when compared to manually generated treatment plans.

Keywords: Varian Ethos; adaptive radiotherapy; auto planning; intelligent optimization engine; prostate cancer.

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Conflict of interest statement

The authors claim no conflicts of interest.

Figures

FIGURE 1
FIGURE 1
Plan selection interface of Ethos treatment planning system (TPS), displaying all available plans for plan approval with a summary of PTV and organs at risk (OAR) dose metrics and a visual queue if the metrics were met. IM101 = 9‐field IMRT, IM102 = 12‐field IMRT, VA103 = 2‐field VMAT, VA104 = 2‐field VMAT Eclipse plan import, VA105 = 2‐field VMAT Eclipse plan import and re‐optimized
FIGURE 2
FIGURE 2
DVH comparison of Eclipse with un‐normalized (a) and normalized (b) Ethos plans for PTV, bladder, rectum, and bowel. PTV = red, Rectum = cyan, Bladder = magenta, Penile Bulb = yellow. Eclipse plan (‐ ■ ‐), Ethos 9‐field IMRT plan (‐ ▲ ‐), Ethos 12‐field IMRT plan (‐ ● ‐), and Ethos 2‐full arc VMAT (formula image)
FIGURE 3
FIGURE 3
Graphical display of various plans: (a) Eclipse 2‐field VMAT plan, (b) Ethos 9‐field IMRT plan, (c) Ethos 12‐field IMRT plan, (d) Ethos 2‐field VMAT plan. Rx isoline = 100% (bold yellow isoline)
FIGURE 4
FIGURE 4
Box and whiskers plot of D max% (a), bladder V64Gy (b), rectum V59Gy (c), and penile bulb mean dose (d)
See this image and copyright information in PMC

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