31. Impact of DVH sharing and experience level in a multicenter SBRT prostate planning study

Purpose To preliminary evaluate the role of a re-planning phase and Experience Level (EL) in a multi-institutional study for achieving similar plan quality results and for further benchmarking. Methods Each center was provided with 5 anonymized CTs with pre-delineated volumes and was asked to create SBRT plans according to pre-set dose constraints. Dose prescription to PTV was 7 Gy × 5 fr. Dosimetric parameters, modulation index (MItotal) and dynamic parameters for 45 SBRT IMRT/VMAT plans from 9 centers were analyzed. EL was ranked as 1 for “not-experienced SBRT planner” (never planned prostate SBRT) and 2 for “experienced SBRT planner”. After DVH sharing, planners were asked to re-plan the 5th patient, based on the median DVHs from all participants, for improving target homogeneity and further OAR sparing. Results Each center was provided with 5 anonymized CTs with pre-delineated volumes and was asked to create SBRT plans according to pre-set dose constraints. Dose prescription to PTV was 7Gy × 5fr. Dosimetric parameters, modulation index (MItotal) and dynamic parameters for 45 SBRT IMRT/VMAT plans from 9 centers were analyzed. EL was ranked as 1 for “not-experienced SBRT planner” (never planned prostate SBRT) and 2 for “experienced SBRT planner”. After DVH sharing, planners were asked to re-plan the 5th patient, based on the median DVHs from all participants, for improving target homogeneity and further OAR sparing. Conclusions Both OAR dosimetric parameters and the MItotal correlated with planner’s experience. Plan complexity metrics and dose distributions depended on specific dosimetric planning requests and replanning improved results in terms of homogeneity between centers whilst keeping the same level of plan complexity. This indicates that SBRT planning skills could benefit from a replanning phase after DVH sharing among participant, improving plan quality and homogeneity among centers. These results highlight the importance of training as well as the usefulness of feedback strategies from multi-institutional comparisons.