Reference Plan

This plan was generated using the Ethos Treatment Management system for daily online adaptive treatments. Planning directives were used to guide the intelligent optimization engine (IOE) for the most optimal balance of target coverage, dose conformity, and OAR sparing. For this case, the clinical directives ranked with high importance were used for CTV/PTV coverage and for minimizing hotspots. Rank of most importance was also assigned to the maximum dose in the rectum and femoral heads. Goals deemed as very important were placed in descending order as PTV50.4 and PTV70 rings, rectum, bladder, bowel, skin, and sigmoid. Additional important and less important Dmean goals were placed on these OAR’s to help reduce lower-level doses.​

​Ethos can automatically derive PTV, PRV, and optimization structures based on templates with saved Boolean operations. These structures can help guide the dose distribution for both initial and adaptive treatment plans. For this case, the 20mm ring structures were cropped 3mm from the PTV’s to help reduce hot spots outside of the targets. An inner ring structure with an expansion of 5mm was also utilized to push dose away from the body surface. A “PTV50.4_Eval” structure was utilized to help guide the gradient between the PTV50.4 and PTV70 dose levels. This structure was derived by cropping PTV50.4 by 7mm from PTV70.​

​A plan from Eclipse was imported utilizing a 19-field beam geometry. Starting from the PA field, each beam angle is spaced every 19 degrees so that no one beam directly opposes each other. The collimator is equally rotated every 9.5 degrees to allow for a unique path of MLC travel for each field. This geometry helps open the solution space for the IOE to find an optimal plan.​

_{Any reference to a "plan study" are simply what the organizers call each case and may not be a "study" in the FDA sense as they may not have been published in a peer reviewed journal.
Varian does not provide medical advice and these are illustrative examples only.
Leading plans by expert planner. Your results may vary.}