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. 2022 Jan;23(1):e13479.
doi: 10.1002/acm2.13479. Epub 2021 Nov 29.

Varian ethos online adaptive radiotherapy for prostate cancer: Early results of contouring accuracy, treatment plan quality, and treatment time

Mikel Byrne  1   2 , Ben Archibald-Heeren  1 , Yunfei Hu  3 , Amy Teh  1 , Rhea Beserminji  1 , Emma Cai  1 , Guilin Liu  1 , Angela Yates  1 , James Rijken  4 , Nick Collett  1 , Trent Aland  5
Affiliations

Varian ethos online adaptive radiotherapy for prostate cancer: Early results of contouring accuracy, treatment plan quality, and treatment time

Mikel Byrne et al. J Appl Clin Med Phys. 2022 Jan.

Abstract

The Varian Ethos system allows for online adaptive treatments through the utilization of artificial intelligence (AI) and deformable image registration which automates large parts of the anatomical contouring and plan optimization process. In this study, treatments of intact prostate and prostate bed, with and without nodes, were simulated for 182 online adaptive fractions, and then a further 184 clinical fractions were delivered on the Ethos system. Frequency and magnitude of contour edits were recorded, as well as a range of plan quality metrics. From the fractions analyzed, 11% of AI generated contours, known as influencer contours, required no change, and 81% required minor edits in any given fraction. The frequency of target and noninfluencer organs at risk (OAR) contour editing varied substantially between different targets and noninfluencer OARs, although across all targets 72% of cases required no edits. The adaptive plan was the preference in 95% of fractions. The adaptive plan met more goals than the scheduled plan in 78% of fractions, while in 15% of fractions the number of goals met was the same. The online adaptive recontouring and replanning process was carried out in 19 min on average. Significant improvements in dosimetry are possible with the Ethos online adaptive system in prostate radiotherapy.

Keywords: adaptive therapy; deformable registration; machine learning.

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Conflict of interest statement

Icon group is a member of the Varian Adaptive Intelligence Consortium and has a partnership with Varian to provide radiotherapy equipment. Mikel Byrne, Ben Archibald‐Heeren and Amy Teh have also received honoraria for presenting on behalf of Varian Medical Systems.

Figures

FIGURE 1
FIGURE 1
Frequency of edits required for (a) influencer structures; (b) target structures; (c) noninfluencer OAR structures; and (d) frequency of sigmoid colon editing by treatment site
FIGURE 2
FIGURE 2
Histogram of differences in number of planning clinical goals met per fraction
FIGURE 3
FIGURE 3
Selected plan parameters shown for each fraction for a representative prostate patient. Note the reference plan values (far left) match the values achieved by the adaptive plan more closely than the scheduled plan. CTVp and PTV_60 coverage is generally higher and rectum dose is generally lower for the adaptive plan for each fraction
See this image and copyright information in PMC

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