Total marrow (lymph-node) irradiation (TMI/TMLI) is a radiotherapy technique irradiating the whole body of a patient. The limited couch travel range in modern linacs (130-150cm) forces to split the TMI/TMLI delivery into two plans with opposite orientation. A dedicated field junction is necessary to achieve satisfactory target coverage in the overlapping region of the two plans. In a recent study, we implemented an automatic tool (AT) using the Eclipse Scripting API for the creation of a field junction and optimization of TMI/TMLI. In this work, we improved the AT by developing an automatic base-dose planning approach. Ten patients were selected to compare the manual procedure, original automatic planning approach, and new base-dose approach. Treatment plans were evaluated with the D98%, Dmean, and D2% for the planning target volume at the junction (PTV_J), while Dmean and D2% were considered for the PTV without the junction (PTVNoJ) and healthy tissues. Base-dose planning significantly improved the PTV_J coverage compared with the manual approach, with unaltered Dmean, consistently lower D2% (2.24Gy vs. 2.30Gy) and higher D98% (1.98Gy vs. 1.89Gy). Moreover, it significantly reduced the hotspots in healthy tissues (2.02Gy vs. 2.15Gy). No significant differences for PTVNoJ dose statistics were observed among the procedures, demonstrating that the automatic approaches produced a target coverage similar to the one obtained manually. Base-dose planning improved the field junction optimization of TMI/TMLI. Automatic planning tools can incrementally improve procedures that would be challenging or error-prone to achieve manually.
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