Room: AAPM ePoster Library
Treatment planning for craniospinal irradiation (CSI) remains technically challenging and extremely labor-intensive. The purpose of this work is to develop an innovative approach for CSI via fixed-jaw based multiple-isocentric automatic planning technique (MultiIsoAP).
Fifteen medulloblastoma patients selected from our institution were retrospectively replanned with MultiIsoAP (36 Gy in 20 fractions) and compared to manually planned intensity-modulated radiotherapy (mpIMRT) and volumetric modulated arc therapy (mpVMAT) which consisted of multiple isocenters and overlapping arcs. Specially, the previous beam-setup and preparation procedures of MultiIsoAP were identical with mpVMAT based CSI technique except for automatically chosen-jaw. The longitudinal-jaws for MultiIsoAP from cranial-spinal junction and spinal-spinal junction were manually fixed and suitably adjusted to acquire the optimal overlaps. Subsequently, the progressive optimization based Pinnacle auto-planning engine was induced to automatically adapt objectives, constraints, and auxiliary structures during optimization. Quantitative evaluations of dose-volume histogram parameters for PTV and OARs were computed and compared.
The target coverage presented with V95% for mpIMRT, mpVMAT and MultiIsoAP were 95.41% ± 1.36%, 95.68% ± 2.61%, and 96.45% ± 0.65%, respectively. Homogeneity and conformity of MultiIsoAP were significantly improved among the three treatment modalities especially for the adjacent field areas. The average active operation-time reduced from (86.1±15.2) for mpIMRT and (67.8 ± 11.3) for mpVMAT to (22.3 ± 5.4) for MultiIsoAP. mpVMAT spared better on Lenses-D1, optic nerves, optic chiasm, Lung-V20, and kidneys-Dmean compared with mpIMRT, while it was significantly increased compared to MultiIsoAP. MultiIsoAP and mpVMAT resulted in appreciable reduction for total MUs by 42.6% and 34.7% compare to mpIMRT. No statistic difference was observed with respect to other OARs
Conclusion: proposed MultiIsoAP efficiently generate acceptable treatment plans for CSI without dose escalation and overall superior to manual planning, which could potentially be applied for other multi-metastatic cancers
Funding Support, Disclosures, and Conflict of Interest: science and technology research project of Jiang Xi provincial department of education (GJJ190136)