The study in the mobility of lung tumors and impact factors

Objective: To investigate the mobility of the lung tumors in order to guide the margin that CTV is to be expanded to PTV during stereotactic radiotherapy for lung tumors. Methods: Eighty-three lung tumors included, in which 7 invaded the chest wall. 1-2 gold marker (s) was/were implanted into or nearby the tumor. The motion of lung tumors in x (right-left), y (superior-inferior) and : (anterior-posterior) directions were measured via X-ray simulator system. One week later, 1.25 mm thick of 16-slice spiral CT lung scan were taken. Apex, middle, and bottom of the lung were classified according to anatomic borderlines. Results: No significant difference was detected among movements of apex, middle and bottom of the lung lesions in x axis direction ((1.6±0.8), (2.6±1.1), (2.8±1.7)mm, respectively (F=1.76, P=0.179)) and, y axis direction ((2.0±1.3), (4.3±2.8), (4.0±2.0)mm, respectively (F=2.06, P=0.135)) in 76 lesions of 63 patients. Significant differences were detected in Z axis ((2.7±0.8), (7.3±3.6), (12.0±5.3) mm (F=16.33, P=0.000)). The mobilities of the 7 lesions of 7 patients invading the chest wall were very small in all directions (0.9±0.7, 0.7±0.7, and 2.0±0.6 mm, respectively). Motion amplitude did not correlate with the sex, age, height, weight and FEV1/FVC (r=-0.001-0.136, all P>0.05). Conclusions: Motion amplitude of lung tumor due to breathing is associated with tumor location and status of chest wall involvement. Identification of the mobile rules and the influencing factors is important for the internal margin set-up in lung tumor radiotherapy. (authors)