Enocson Hedda, Haraldsson André, Engström Per, Ceberg Sofie, Gebre-Medhin Maria, Adrian Gabriel, Af Rosenschöld Per Munck
Medical Radiation Physics, Department of Clinical Sciences Lund, Lund University, Lund, Sweden.
Radiation Physics, Department of Hematology, Oncology, and Radiation Physics, Skåne University Hospital, Sweden.
Phys Imaging Radiat Oncol. 2025 Jan 11;33:100696. doi: 10.1016/j.phro.2025.100696. eCollection 2025 Jan.
Adaptive radiotherapy (ART) involves treatment re-planning based on anatomical changes, which may improve target coverage and sparing of organs-at-risk (OARs). This study retrospectively assessed the technical feasibility and potential benefits of daily ART in combination with reduced planning target volume (PTV) margins for head and neck squamous cell carcinoma (HNSCC).
Thirty-one patients, encompassing 902 treatment fractions, treated with radiotherapy to 60.0-68.0 Gy in 2 Gy/fraction were studied. Synthetic CTs (sCT) from daily kVCT images were created and contours propagated using deformable image registration (DIR). Target contours were reviewed and corrected. On the sCT, non-adapted delivered doses and ART-plans with 5 mm (clinical standard) and 2 mm PTV-margin were evaluated. All daily dose distributions were then accumulated.
Target contours required correction in 48 % of the fractions. Daily non-adapted D was > 95 % in 890 (5 mm) and 825 (2 mm) out of 902 fractions. All adapted plans achieved D > 95 %. Significant reductions in mean doses to OARs were observed for PTV = 2 mm ART-plans: 4.1 Gy for parotid, 2.6 Gy for submandibular, 3.3 Gy for oral cavity, 4.0 Gy for esophagus, and 3.8 Gy for larynx.
ART-planning on sCT and DIR propagated contours was feasible and promising for further clinical testing. To obtain a potential clinical benefit of ART, a synchronous reduction of the PTV-margin was warranted. Daily ART can be used to maintain adequate target dosimetry for every fraction, though for the accumulated treatment, insufficient target coverage without ART is unlikely to occur.
自适应放疗（ART）涉及基于解剖结构变化进行治疗重新计划，这可能会改善靶区覆盖并减少危及器官（OARs）的受照剂量。本研究回顾性评估了每日ART联合缩小计划靶体积（PTV）边界用于头颈部鳞状细胞癌（HNSCC）治疗时的技术可行性和潜在益处。
研究了31例接受放疗的患者，共902个治疗分次，每次分割剂量为2 Gy，总剂量60.0 - 68.0 Gy。利用每日千伏级CT（kVCT）图像生成合成CT（sCT），并使用可变形图像配准（DIR）传播轮廓。对靶区轮廓进行复查和校正。在sCT上，评估了未适应的已交付剂量以及PTV边界为5 mm（临床标准）和2 mm的ART计划。然后累积所有每日剂量分布。
48%的分次需要校正靶区轮廓。在902个分次中，890个（5 mm）和825个（2 mm）分次的每日未适应剂量D>95%。所有适应计划的D均>95%。对于PTV = 2 mm的ART计划，观察到OARs的平均剂量显著降低：腮腺降低4.1 Gy，下颌下腺降低2.6 Gy，口腔降低3.3 Gy，食管降低4.0 Gy，喉降低3.8 Gy。
在sCT和DIR传播的轮廓上进行ART计划是可行的，有望进一步进行临床试验。为了获得ART的潜在临床益处，有必要同步缩小PTV边界。每日ART可用于维持每个分次的靶区剂量测定足够准确，尽管对于累积治疗而言，没有ART时靶区覆盖不足的情况不太可能发生。
