Adaptive radiotherapy for head and neck cancer reduces the requirement for rescans during treatment due to spinal cord dose
Adaptive radiotherapy for head and neck cancer reduces the requirement for rescans during treatment due to spinal cord dose
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DOI：
10.1186/s13014-019-1400-3
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发表时间：
2019-11-01
影响因子：
3.6
通讯作者：
McGarry, Conor K.
中科院分区：
文献类型：
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作者：
Belshaw, Louise;Agnew, Christina E.;McGarry, Conor K.
背景头颈部(H&N)癌放射治疗的患者往往会经历解剖结构的改变。计划目标体积(PTV)覆盖或危险器官(OAR)保留的潜在妥协促使这些患者使用适应性放射治疗(ART)。然而，ART的实施是时间和资源密集型的。这项研究试图通过使用千伏锥束计算机断层扫描(CBCT)验证成像来定义基于脊髓安全性的H&N重新计划的临床触发因素，以便最佳地平衡临床收益和额外的工作量。方法31例H&N患者接受容量调节弧形疗法(VMAT)治疗，治疗过程中均行CT扫描(RCT)。确定计划CT(PCT)和RCT之间的等高线体积变化。最初的治疗计划是在PCT、RCT之前的CBCT、变形后的CBCT(DCT)和RCT(被认为是金标准)上计算的。从剂量体积直方图(DVHs)评估0.1cc(D0.1cc)脊髓的剂量。结果PCT与RCT之间D0.1cc的中位剂量增加为0.7Gy四分位数范围为0.2~1.9Gyp<；0.05)。等高线体积变化与脊髓剂量增加之间无相关性。3名患者表现出7.0-7.2GyD0.1cc的增加，导致重新计划；通过CBCT/DCT的计算，这些患者被正确识别。结论根据CBCT/DCT计算的脊髓剂量可触发自适应重新计划。实施这一触发机制可以通过消除高达90%的额外不必要的CT扫描来减少患者预约时间和辐射剂量，从而减少放射技师、物理学家、剂量师和临床医生的工作量。
Background Patients treated with radiotherapy for head and neck (H&N) cancer often experience anatomical changes. The potential compromises to Planning Target Volume (PTV) coverage or Organ at Risk (OAR) sparing has prompted the use of adaptive radiotherapy (ART) for these patients. However, implementation of ART is time and resource intensive. This study seeks to define a clinical trigger for H&N re-plans based on spinal cord safety using kV Cone-Beam Computed Tomography (CBCT) verification imaging, in order to best balance clinical benefit with additional workload. Methods Thirty-one H&N patients treated with Volumetric Modulated Arc Therapy (VMAT) who had a rescan CT (rCT) during treatment were included in this study. Contour volume changes between the planning CT (pCT) and rCT were determined. The original treatment plan was calculated on the pCT, CBCT prior to the rCT, pCT deformed to the anatomy of the CBCT (dCT), and rCT (considered the gold standard). The dose to 0.1 cc (D0.1cc) spinal cord was evaluated from the Dose Volume Histograms (DVHs). Results The median dose increase to D0.1cc between the pCT and rCT was 0.7 Gy (inter-quartile range 0.2-1.9 Gy, p < 0.05). No correlation was found between contour volume changes and the spinal cord dose increase. Three patients exhibited an increase of 7.0-7.2 Gy to D0.1cc, resulting in a re-plan; these patients were correctly identified using calculations on the CBCT/dCT. Conclusions An adaptive re-plan can be triggered using spinal cord doses calculated on the CBCT/dCT. Implementing this trigger can reduce patient appointments and radiation dose by eliminating up to 90% of additional un-necessary CT scans, reducing the workload for radiographers, physicists, dosimetrists, and clinicians.