Adaptive carbon ion radiotherapy for locally advanced non‐small cell lung cancer: Organ‐sparing potential and target coverage

Abstract

Background The dose distribution of carbon ion radiotherapy (CIRT) for locally advanced non‐small cell lung cancer (LANSCLC) is highly sensitive to anatomical changes. Purpose To demonstrate the dosimetric benefits of adaptive CIRT for LANSCLC and compare the differences between patients with and without adaptive plans based on dosimetry and clinical effect factors. Materials and methods Of the 98 patients with LANSCLC receiving CIRT, 31 patients underwent replanning following re‐evaluations that revealed changes that would have compromised the dose coverage of the target volume or violated dose constraints. Dosimetric parameters and clinical factors were compared between patients with and without adaptive plans. Multivariate analysis identified factors influencing the adaptive planning. Results The median number of fractions delivered using adaptive plans was eight (range: 2‐18). Adaptive plans ensured target coverage, and the maximum spinal cord dose was significantly decreased (p = 0.02). The median reduction in the maximum spinal cord dose was 10.4 Gy (relative biological effectiveness). Patients with adaptive plans had larger tumor volumes (p < 0.001); the median initial internal gross tumor volumes (iGTVs) of patients with adaptive and nonadaptive plans were 125.9 and 49.79 cm3, respectively. Tumor volumes of patients with adaptive plans were altered to a greater extent (p < 0.001); the median absolute percentage of volume changes in patients in the adaptive and in nonadaptive groups were 20.76% and 3.63%, respectively, while the median movements of iGTV centers were 5.75 and 2.44 mm, respectively. Binary logistic regression analysis revealed that the iGTV volume change and iGTV center movements were significantly different between the groups. Conclusions An adaptive plan can effectively ensure target area coverage and protect normal tissues, especially in patients with large tumor volumes and substantial changes. iGTV volume changes and iGTV center movements are the main factors influencing adaptive planning. Weekly simulation computed tomography scans are necessary for treatment evaluation in patients with LANSCLC treated with CIRT.

Robust Beam Selection Based on Water Equivalent Thickness Analysis in Passive Scattering Carbon-Ion Radiotherapy for Pancreatic Cancer

“…We also found a highly robust dose distribution of BC_gantry with TM, and the dose degradation in CTV V95% was very limited (mean value: 3.8%), which was close to that of the adaptive method (mean value: 2.1%) reported in a previous study [28]. Adaptive therapy has been verified as the most effective method for improving the robustness of CIRT plans [28][29][30]. However, rapid online dose verification and quality assurance systems are still challenging.…”

Deep learning-based voxel sampling for particle therapy treatment planning

“…Furthermore, it will aid in enabling fast online treatment adaptation for carbon ion therapy. Weekly or possibly even daily treatment adaptation is often needed to ensure the best therapy, but workflow efficiency is still a major bottleneck (Jia et al 2022). Moreover, the efficiency increase achieved with deep learning voxel sampling would enable to run many planning processes in parallel, providing an improved platform for developing machine learning methods.…”

Beam range uncertainty and its clinical management in particle therapy

“…By recalculating the treatment plan on the verification CT and performing a robustness evaluation, appropriate measures are taken to ensure treatment quality. Adaptive therapy for particle treatment is also an active research subject aiming at more frequent and active intervention by utilizing the daily setup imaging data (CBCT or in-room CT) [51][52][53][54][55][56].…”