(Thursday, 7/16/2020) 10:30 AM - 12:30 PM [Eastern Time (GMT-4)]
Room: Track 4
Purpose: fully automated online re-planning tool for adaptive radiotherapy (ART) was recently integrated into a commercial treatment planning system uRT-TPS. This study validated the tool by evaluating the quality of auto-generated adaptive plans and planning efficiency for cervical cancer radiotherapy.
Methods: cervical cancer cases were involved. For each case: 1) a clinical acceptable initial static IMRT plan was manually optimized on the planning CT using a 3 mm PTV margin; 2) the initial plan was copied to a treatment CT acquired with a CT-LINAC on a treatment day through rigid registration, and re-calculated to represent image-guided radiotherapy (IGRT) practice; 3) targets and organs at risk (OARs) were auto-segmented on the treatment CT and revised by a physician. Subsequently, an adaptive plan was generated using the online re-planning tool. Time required for each ART step was recorded. IGRT and adaptive plans were evaluated for clinical acceptance and compared to initial plans.
Results: time required for auto-segmentation, revision, and plan generation were 0.5±0.1 min, 12.1±4.9 min and 1.2±0.2 min. All IGRT plans failed to maintain the target coverage, with D95 generally lower than the prescription, ranging from -4.5% to -26.7%. All adaptive plans were clinically acceptable with adequate target coverage. Compared to initial plans, ART plans achieved comparable target conformity index and lower homogeneity index. Differences in OAR sparing were not significant, evaluating with mean dose of bladder/rectum/femoral heads and V30 of bladder/rectum.
Conclusion: fully automated online re-planning tool was able to generate adaptive plans for cervical cancer in less than 2 minutes with clinical acceptable plan quality. The whole ART workflow can be completed in 15~20 minutes. Clinical application of online ART has the potential to eliminate the risk of target underdose when IGRT fails with a small margin.
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