Department of Radiology, Asanogawa General Hospital, 83 Kosaka-naka, Kanazawa 920-8621, Japan.
Med Phys. 2011 Jul;38(7):4141-6. doi: 10.1118/1.3604151.
Breathing control is crucial to ensuring the accuracy of stereotactic irradiation for lung cancer. This study monitored respiration in patients with inoperable nonsmall-cell lung cancer using a respiration-monitoring apparatus, Abches, and investigated the reproducibility of tumor position in these patients.
Subjects comprised 32 patients with nonsmall-cell lung cancer who were administered stereotactic radiotherapy under breath-holding conditions monitored by Abches. Computed tomography (CT) was performed under breath-holding conditions using Abches (Abches scan) for treatment planning. A free-breathing scan was performed to determine the range of tumor motions in a given position. After the free-breathing scan, Abches scan was repeated and the tumor position thus defined was taken as the intrafraction tumor position. Abches scan was also performed just before treatment, and the tumor position thus defined was taken as the interfraction tumor position. To calculate the errors, tumor positions were compared based on Abches scan for the initial treatment plan. The error in tumor position was measured using the BrainSCAN treatment-planning device, then compared for each lung lobe.
Displacements in tumor position were calculated in three dimensions (i.e., superior-inferior (S-I), left-right (L-R), and anterior-posterior (A-P) dimensions) and recorded as absolute values. For the whole lung, average intrafraction tumor displacement was 1.1 mm (L-R), 1.9 mm (A-P), and 2.0 mm (S-I); the average interfraction tumor displacement was 1.1 mm (L-R), 2.1 mm (A-P), and 2.0 mm (S-I); and the average free-breathing tumor displacement was 2.3 mm (L-R), 3.5 mm (A-P), and 7.9 mm (S-I). The difference between using Abches and free breathing could be reduced from approximately 20 mm at the maximum to approximately 3 mm in the S-I direction for both intrafraction and interfraction positions in the lower lobe. In addition, maximum intrafraction tumor displacement with the use of Abches was 4.5 mm (S-I) in the lingular segment. These results suggest that use of the Abches system can reduce deviations in tumor position to levels below those achieved under free breathing, irrespective of the tumor location.
Respiratory control with high accuracy and reproducibility is required for high-precision radiotherapy of inoperable nonsmall-cell lung cancer and was achieved using Abches in this study.
呼吸控制对于确保肺癌立体定向放疗的准确性至关重要。本研究使用呼吸监测仪 Abches 监测无法手术的非小细胞肺癌患者的呼吸，并研究这些患者肿瘤位置的可重复性。
本研究纳入了 32 例接受立体定向放疗的非小细胞肺癌患者，这些患者在 Abches 监测下进行屏气。使用 Abches 进行屏气状态下的计算机断层扫描（CT）（Abches 扫描）进行治疗计划。在自由呼吸状态下进行扫描，以确定给定位置的肿瘤运动范围。在自由呼吸扫描后，重复 Abches 扫描，并将由此确定的肿瘤位置定义为分次内肿瘤位置。Abches 扫描也在治疗前进行，将由此确定的肿瘤位置定义为分次间肿瘤位置。为了计算误差，根据初始治疗计划，使用 BrainSCAN 治疗计划设备对肿瘤位置进行比较。然后，在每个肺叶中比较肿瘤位置误差。
在三个维度（即上下（S-I）、左右（L-R）和前后（A-P）维度）计算肿瘤位置的位移，并记录为绝对值。对于整个肺，分次内肿瘤平均位移为 1.1mm（L-R）、1.9mm（A-P）和 2.0mm（S-I）；分次间肿瘤平均位移为 1.1mm（L-R）、2.1mm（A-P）和 2.0mm（S-I）；自由呼吸肿瘤平均位移为 2.3mm（L-R）、3.5mm（A-P）和 7.9mm（S-I）。使用 Abches 和自由呼吸时的差异可从最大约 20mm 减少到下叶分次内和分次间位置的 S-I 方向约 3mm。此外，使用 Abches 的最大分次内肿瘤位移为 4.5mm（S-I）在舌段。这些结果表明，使用 Abches 系统可以将肿瘤位置的偏差降低到低于自由呼吸时的水平，而与肿瘤位置无关。
对于无法手术的非小细胞肺癌的高精度放疗，需要高精度和可重复性的呼吸控制，本研究中使用 Abches 实现了这一目标。
