ACRF Image X Institute, The University of Sydney Central Clinical School, Australia.
ACRF Image X Institute, The University of Sydney Central Clinical School, Australia.
Radiother Oncol. 2019 Jun;135:65-73. doi: 10.1016/j.radonc.2019.02.019. Epub 2019 Mar 14.
To test the hypothesis that 4DCT and 4DCBCT-measured target motion ranges predict target motion ranges during lung cancer SABR.
Ten lung SABR patients were implanted with Calypso beacons. 4DCBCT was reconstructed for 29 fractions (1-4fx/patient) from a 1 min CBCT scan. The beacon centroid motion segmented for all 4DCT and 4DCBCT bins was compared with the real-time imaging and treatment beacon centroid ("target") motion range (4SDs) for each fraction. We tested the hypotheses that (1) 4DCT and 4CBCT predict treatment motion range and (2) there is no difference between 4DCT and 4DCBCT for predicting treatment motion range. Phase-wise root-mean-square errors (RMSEs) between imaging and treatment motion and reconstructed motion (4DCT, 4DCBCT) were calculated. Relationships between motion ranges in 4DCT and 4DCBCT and imaging and treatment motion ranges were investigated for the superior-inferior (SI), left-right (LR) and anterior-posterior (AP) directions. Baseline drifts and amplitude variability were investigated as potential factors leading to motion misrepresentation.
SI 4DCT, 4DCBCT, imaging and treatment motion ranges were 6.3 ± 3.6 mm, 7.1 ± 4.5 mm, 11.1 ± 7.5 mm and 10.9 ± 6.9 mm, respectively. Similar 4DCT and 4DCBCT under-predictions were observed in the LR and AP directions. Hypothesis (1) was rejected (p < 0.0001). Treatment target motion range was under-predicted in 4DCT by factors of 1.7, 1.9 and 1.7 and in 4DCBCT by factors of 1.5, 1.6 and 1.6 in the SI, LR, and AP directions, respectively. RMSEs were generally lower for end-exhale than inhale. 4DCBCT showed higher correlations with the imaging and treatment target motion than 4DCT and testing hypothesis (2) a statistically significant difference between 4DCT and 4DCBCT was shown in the SI direction (p = 0.03).
For lung SABR patients both 4DCT and 4DCBCT significantly under-predict treatment target motion ranges.
本研究旨在验证以下假设，即 4DCT 和 4D-CBCT 测量的靶区运动范围可预测肺癌 SABR 中的靶区运动范围。
10 例肺癌 SABR 患者接受了 Calypso 信标植入。从 1 分钟 CBCT 扫描中重建了 29 个分次（1-4fx/例）的 4D-CBCT。对所有 4DCT 和 4D-CBCT bins 的信标质心运动进行了分段，并与实时成像和治疗信标质心（“靶区”）运动范围（4SD）进行了比较。我们检验了以下两个假设：（1）4DCT 和 4D-CBCT 可预测治疗运动范围；（2）4DCT 和 4D-CBCT 预测治疗运动范围无差异。计算了成像和治疗运动与重建运动（4DCT、4D-CBCT）之间的各相位均方根误差（RMSE）。研究了 4DCT 和 4D-CBCT 中的运动范围与成像和治疗运动范围在上下（SI）、左右（LR）和前后（AP）方向上的关系。研究了基线漂移和幅度变化作为导致运动表示不准确的潜在因素。
SI 4DCT、4D-CBCT、成像和治疗运动范围分别为 6.3±3.6mm、7.1±4.5mm、11.1±7.5mm和 10.9±6.9mm。在 LR 和 AP 方向也观察到类似的 4DCT 和 4D-CBCT 低估。假设 1 被拒绝（p＜0.0001）。4DCT 和 4D-CBCT 在 SI、LR 和 AP 方向上对治疗靶区运动范围的预测值分别为 1.7、1.9 和 1.7 倍和 1.5、1.6 和 1.6 倍。在呼气末的 RMSE 通常低于吸气末。4D-CBCT 与成像和治疗靶区运动的相关性高于 4DCT，且在 SI 方向上，检验假设 2（4DCT 和 4D-CBCT 之间存在统计学显著差异）具有统计学意义（p=0.03）。
对于接受肺癌 SABR 的患者，4DCT 和 4D-CBCT 均显著低估了治疗靶区运动范围。
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