Planning evaluation of a novel volume-based algorithm for personalized optimization of lung dose in VMAT for esophageal cancer

Chen-Xiong Hsu,Tung-Hsin Wu,Wei-Ta Tsai,Hui-Ju Tien,Chiu-Han Chang,Kuan-Heng Lin,Shan-Ying Wang,Greta S P Mok,Pei-Wei Shueng

doi:10.1038/s41598-021-04571-3

Chen-Xiong Hsu, Tung-Hsin Wu + Show 7 more

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https://doi.org/10.1038/s41598-021-04571-3

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Radiotherapy treatment planning (RTP) is time-consuming and labor-intensive since medical physicists must devise treatment plans carefully to reduce damage to tissues and organs for patients. Previously, we proposed the volume-based algorithm (VBA) method, providing optimal partial arcs (OPA) angle to achieve the low-dose volume of lungs in dynamic arc radiotherapy. This study aimed to implement the VBA for esophageal cancer (EC) patients and compare the lung dose and delivery time between full arcs (FA) without using VBA and OPA angle using VBA in volumetric modulated arc therapy (VMAT) plans. We retrospectively included 30 patients diagnosed with EC. RTP of each patient was replanned to 4 VMAT plans, including FA plans without (FA-C) and with (FA + C) dose constraints of OARs and OPA plans without (OPA-C) and with (OPA + C) dose constraints of OARs. The prescribed dose was 45 Gy. The OARs included the lungs, heart, and spinal cord. The dose distribution, dose-volume histogram, monitor units (MUs), delivery time, and gamma passing rates were analyzed. The results showed that the lung V5 and V10 in OPA + C plans were significantly lower than in FA + C plans (p < 0.05). No significant differences were noted in planning target volume (PTV) coverage, lung V15, lung V20, mean lung dose, heart V30, heart V40, mean heart dose, and maximal spinal cord dose between FA + C and OPA + C plans. The delivery time was significantly longer in FA + C plans than in OPA + C plans (237 vs. 192 s, p < 0.05). There were no significant differences between FA + C and OPA + C plans in gamma passing rates. We successfully applied the OPA angle based on the VBA to clinical EC patients and simplified the arc angle selection in RTP. The VBA could provide a personalized OPA angle for each patient and effectively reduce lung V5, V10, and delivery time in VMAT.

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With the rapid development of dynamic arc radiotherapy, volumetric modulated arc therapy (VMAT) and tomotherapy could have better tumor coverage of the treatment plans for esophageal cancer (EC)
The purpose of this study was to implement the optimal partial arcs (OPA) angle based on the volume-based algorithm (VBA) for clinical EC patients and to compare the lung dose and delivery time between full arcs (FA) without using VBA and OPA angle using VBA in VMAT plans
The results showed that the PVT could achieve good target coverage and the organs at risk (OARs) could decline to the acceptable dose

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Introduction

With the rapid development of dynamic arc radiotherapy, volumetric modulated arc therapy (VMAT) and tomotherapy could have better tumor coverage of the treatment plans for esophageal cancer (EC). Many methods for reducing the lung dose have been reported in dynamic arc radiotherapy[9, 10]. The selection of gantry arc angle and dose constraints are the key factors in radiotherapy treatment planning (RTP). Parameters, which is complex and time-consuming in inverse treatment planning. A high-quality treatment plan could provide high tumor coverage, low normal tissue dose, and a shorter delivery time in VMAT, e.g., an average of 6.1–6.6 min to deliver the total monitor unit (MUs)[10, 14]. The purpose of this study was to implement the OPA angle based on the VBA for clinical EC patients and to compare the lung dose and delivery time between full arcs (FA) without using VBA and OPA angle using VBA in VMAT plans

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