Evaluation of Hybrid VMAT Advantages and Robustness Considering Setup Errors Using Surface Guided Dose Accumulation for Internal Lymph Mammary Nodes Irradiation of Postmastectomy Radiotherapy

Abstract

ObjectivesSetup error is a key factor affecting postmastectomy radiotherapy (PMRT) and irradiation of the internal mammary lymph nodes is the most investigated aspect for PMRT patients. In this study, we evaluated the robustness, radiobiological, and dosimetric benefits of the hybrid volumetric modulated arc therapy (H-VMAT) planning technique based on the setup error in dose accumulation using a surface-guided system for radiation therapy.MethodsWe retrospectively selected 32 patients treated by a radiation oncologist and evaluated the clinical target volume (CTV), including internal lymph node irradiation (IMNIs), and considered the planning target volume (PTV) margin to be 5 mm. Three different planning techniques were evaluated: tangential-VMAT (T-VMAT), intensity-modulated radiation therapy (IMRT), and H-VMAT. The interfraction and intrafraction setup errors were analyzed in each field and the accumulated dose was evaluated as the patients underwent daily surface-guided monitoring. These parameters were included while evaluating CTV coverage, the dose required for the left anterior descending artery (LAD) and the left ventricle (LV), the normal tissue complication probability (NTCP) for the heart and lungs, and the second cancer complication probability (SCCP) for contralateral breast (CB).ResultsWhen the setup error was accounted for dose accumulation, T-VMAT (95.51%) and H-VMAT (95.48%) had a higher CTV coverage than IMRT (91.25%). In the NTCP for the heart, H-VMAT (0.04%) was higher than T-VMAT (0.01%) and lower than IMRT (0.2%). However, the SCCP (1.05%) of CB using H-VMAT was lower than that using T-VMAT (2%) as well as delivery efficiency. And T-VMAT (3.72) and IMRT (10.5).had higher plan complexity than H-VMAT (3.71).ConclusionsIn this study, based on the dose accumulation of setup error for patients with left-sided PMRT with IMNI, we found that the H-VMAT technique was superior for achieving an optimum balance between target coverage, OAR dose, complication probability, plan robustness, and complexity.

Hybrid Treatment Planning for Chest Wall Irradiation Utilizing Three-Dimensional Conformal Radiotherapy (3DCRT), Intensity-Modulated Radiation Therapy (IMRT), and Volumetric Modulated Arc Therapy (VMAT): A Systematic Review

“…The nine reviewed articles have various levels of chest wall irradiation with lymph node inclusion. The left side was covered in six reports [19][20][21][22][23][24]. The chest wall on both sides was studied in three investigations [25][26][27].…”

“…The dose distribution map for the mentioned techniques is illustrated in Figure 2. A combination of modalities produced better PTV coverage [19,22,23,27], lower HI [19,27], higher CI [19,22], lower MU [19,22,23], and shorter treatment time [19,22] than relying on a single modality. The hybrid techniques, H-VMAT or H-IMRT, performed better in PTV coverage than single modalities 3DCRT and VMAT.…”

“…H-VMAT and H-IMRT had lower MUs and less treatment time. From two reviewed studies, the MU decreased from 524 and 746 in VMAT to 489 and 742 in H-VMAT [19,23].…”

Comparative Study of Plan Robustness for Breast Radiotherapy: Volumetric Modulated Arc Therapy Plans with Robust Optimization versus Manual Flash Approach

“…This evaluation method could address dose degradation in the worst possible error scenario in line with the definition of robustness. A smaller difference represented greater robustness [24,25].…”

“…This approach requires defining a magnitude of uncertainties and discretizing them into several error scenarios for generating a plan that can minimize objective functions based on the worst case scenarios. In this way, a skin flashing effect could be achieved [24,25].…”