Hoffmann Lone, Alber Markus, Jensen Maria Fuglsang, Holt Marianne Ingerslev, Møller Ditte Sloth
Department of Medical Physics, Aarhus University Hospital, Denmark.
Department of Radiation Oncology, Heidelberg University Hospital, Germany.
Radiother Oncol. 2017 Mar;122(3):400-405. doi: 10.1016/j.radonc.2016.12.018. Epub 2016 Dec 31.
Large anatomical changes during radiotherapy are seen for a large proportion of lung cancer patients. We investigate the applicability of a decision support protocol for photon therapy in a proton therapy setting.
Twenty-three consecutive NSCLC patients treated with adaptive photon therapy were retrospectively planned using IMPT. The adaptive protocol was based on geometrical measures of target positioning and large anatomical changes as shown on daily CBCT scans. Two surveillance CT-scans were acquired during the treatment course. The consequences of anatomical changes were evaluated by recalculating the proton plans on the surveillance scans. The CTV receiving 95% of the prescribed dose was analysed.
Fourteen (61%) patients needed adaptations when treated with protons, given that 95% of the CTV must be covered by 95% of the dose. In comparison, no patients needed adaptation when treated with photons using this criterion. The adaptive protocol was found to identify patients with large target under-dosage for proton therapy (six patients). Additionally, target under-dosage was observed for eight patients with non-rigid changes up to 15mm in the positioning of the bones.
Proton therapy for loco-regional lung cancer demands daily imaging and therapy adaptation for a high proportion of patients.
大部分肺癌患者在放疗期间会出现较大的解剖结构变化。我们研究了一种光子治疗决策支持方案在质子治疗环境中的适用性。
对连续23例接受自适应光子治疗的非小细胞肺癌患者进行回顾性计划，采用调强质子治疗（IMPT）。自适应方案基于靶区定位的几何测量以及每日锥形束CT（CBCT）扫描显示的较大解剖结构变化。在治疗过程中获取了两次监测CT扫描。通过在监测扫描上重新计算质子计划来评估解剖结构变化的后果。分析接受规定剂量95%的临床靶区（CTV）。
当使用质子治疗时，14例（61%）患者需要调整，前提是CTV的95%必须被95%的剂量覆盖。相比之下，使用该标准进行光子治疗时，没有患者需要调整。发现自适应方案能够识别出质子治疗中靶区剂量不足较大的患者（6例）。此外，在8例骨骼定位非刚性变化达15毫米的患者中也观察到了靶区剂量不足。
局部区域性肺癌的质子治疗需要对大部分患者进行每日成像和治疗调整。
