Stereotactic radiation therapy by medium fraction size for lung tumor

Stereotactic radiation therapy by medium fraction size (SRTm) was applied for lung tumor, we investigated to effectiveness and CT image change by treatment. Thirteen patients with lung tumor were treated with SRTm between September, 2003 and June, 2004. Nine cases were consisted as primary lung cancer, and 4 as metastatic lung cancers. Total 13 lesions were treated in 13 cases. Tumor diameter ranged from 1 cm to 4 cm, and the median was 2 cm. Body Fix was applied for patient's immobilization. The treatment planning was performed with CT simulator, X-ray simulator, and ECLIPSE. Fraction dose was escalated from 4 Gy to 7 Gy, of which contents were as follows 4 Gy/f x 10 f (one) 4 Gy/fx 12 f (one), 4 Gy/fx 15 f (one), 5 Gy/fx 10 f (3) 5 Gy/f x 12 f (3), 6 Gy x 10 f (3), and 7 Gy/f x 10 f (one). Total dose by LQ model were estimated as 56-119 in BEDacute (α/β=10), and 120-315 in BEDlate (α/β=3). V20 ranged from 2.52-10.24% (average 5.84). In the initial response, 8 lesions were achieved as CR, 2 as PR and 3 as SD. Among 13 lesions, no lesion had re-growth. Radiation-induced pulmonary complications greater than National Cancer Institute (NCI)-CTC criteria Grade 2 was noted one only. In change of CT image, slight increase in opacity was noted 3 cases within 3 month after treatment. Pachy consolidation was noted 10 cases between 3 month and 12 month after treatment. Stereotactic radiation therapy by medium fraction size for lung tumor was considered as effective and safety. (author)