van der Weide Lineke, van Sörnsen de Koste John R, Lagerwaard Frank J, Vincent Andrew, van Triest Baukelien, Slotman Ben J, Senan Suresh
Department of Radiation Oncology, VU University Medical Center, Amsterdam, The Netherlands.
Int J Radiat Oncol Biol Phys. 2008 Jul 15;71(4):1111-7. doi: 10.1016/j.ijrobp.2007.11.027. Epub 2008 Feb 6.
Respiratory gating can mitigate the effect of tumor mobility in radiotherapy (RT) for lung cancer. Because the tumor is generally not visualized, external surrogates of tumor position are used to trigger respiration-gated RT. We evaluated the suitability of the carina position as a surrogate in respiration-gated RT.
A total of 30 four-dimensional (4D) computed tomography (CT) scans from 14 patients with lung cancer were retrospectively analyzed. Both uncoached (free breathing) and audio-coached 4D-CT scans were acquired from 9 patients, and 12 uncoached 4D-CT scans were acquired from 5 other patients during a 2-4-week period of stereotactic RT. The repeat scans were co-registered. The carina position was identified on the coronal cut planes in all 4D-CT phases. The correlation between the carina position and the total lung volume for each phase was determined, and the reproducibility of the carina position was studied in the 5 patients with repeat uncoached 4D-CT scans.
The mean extent of carina motion in 21 uncoached scans was 5.3 +/- 1.6 mm in the craniocaudal (CC), 2.3 +/- 1.4 mm in the anteroposterior, and 1.5 +/- 0.7 mm in the mediolateral direction. Audio coaching resulted in a twofold increase in carina mobility in all directions. The CC carina position correlated with changes in the total lung volume (R = 0.89 +/- 0.14), but the correlation was better for the audio-coached than for the uncoached 4D-CT scans (R = 0.93 +/- 0.08 vs. R = 0.85 +/- 0.17; paired t test, p = 0.034). Preliminary data from the 5 patients indicated that the CC carina motion correlated better with tumor motion than did the motion of the diaphragm.
The CC position of the carina correlated well with the total lung volume, indicating that the carina is a good surrogate for verifying the total lung volume during respiration-gated RT.
呼吸门控可减轻肺癌放射治疗（RT）中肿瘤运动的影响。由于肿瘤通常不可见，因此使用肿瘤位置的外部替代物来触发呼吸门控RT。我们评估了隆突位置作为呼吸门控RT替代物的适用性。
回顾性分析了14例肺癌患者的30次四维（4D）计算机断层扫描（CT）。在立体定向RT的2-4周期间，从9例患者中获取了非指导（自由呼吸）和音频指导的4D-CT扫描，从另外5例患者中获取了12次非指导的4D-CT扫描。重复扫描进行了配准。在所有4D-CT阶段的冠状切面上确定隆突位置。确定每个阶段隆突位置与全肺体积之间的相关性，并在5例进行重复非指导4D-CT扫描的患者中研究隆突位置的可重复性。
在21次非指导扫描中，隆突在颅尾（CC）方向的平均移动范围为5.3±1.6mm，前后方向为2.3±1.4mm，内外侧方向为1.5±0.7mm。音频指导导致隆突在各个方向上的移动增加了两倍。CC隆突位置与全肺体积的变化相关（R = 0.89±0.14），但音频指导的4D-CT扫描的相关性优于非指导的4D-CT扫描（R = 0.93±0.08 vs. R = 0.85±0.17；配对t检验，p = 0.034）。5例患者的初步数据表明，CC隆突运动与肿瘤运动的相关性优于膈肌运动。
隆突的CC位置与全肺体积密切相关，表明隆突是呼吸门控RT期间验证全肺体积的良好替代物。
