Primary application of active breathing control system in conformal radiotherapy for patients with non-small cell lung cancer / 中华放射肿瘤学杂志

ABSTRACT

Objective To evaluate the feasibility of active breathing control (ABC) in conformal radiotherapy (CRT) for patients with non-small cell lung cancer (NSCLC). Methods From Feb 2005 to Mar 2008, 29 patients with inoperable NSCLC (stage Ⅱ-Ⅳ) were evaluated. For each patient, two series of CT scans were obtained with free breathing (FB) and ABC system during simulation, respectively. Then two confonnal radiotherapy (CRT) plans were finished based on the two sets of reconstructed images. The pattern of post-inspiratory breath-hold was triggered at 80% of the peak of inspiration curve. The margin of clinical target volume (CTV) to planning target volume (PTV) was 0. 6 cm for lesions of the superior lobe, and 1.0 cm for the lesions of middle and inferior lobes. Three to five coplanar fields were performed in conformal radiotherapy. The gross tumor volume (GTV), CTV, PTV, volume of the bilateral lungs (Volume_(lung)), V_(20) and mean lung dose (MLD) of two plans were evaluated by dose-volume histogram (DVH). The World Health Organization criteria and National Cancer Institute Common Toxicity Criteria 3.0 (NCI-CTC3.0) scale were used to assess the immediate response and acute side-effect, respectively. Results Significant differences of GTV, CTV, FIN, Volum_(lung), V_(20) and MDL were observed between the two plans (36. 35 cm~3 vs. 31.40 cm~3, t = 9. 70, P <0. 001 ;82. 33 cm~3 vs. 70. 83 cm~3, t = 8. 19, P < 0. 001 ; 230. 73 cm~3 vs. 197.59 cm~3 ,t=5.72,P <0. 001 ;21.66% vs. 18. 76% ,t = 11.16,P <0. 001 ;1329. 07 Gy vs. 1143. 14 Gy, t = 13. 24, P < 0. 001). With ABC, all patients completed their treatment successfully except one patient for financial problems. The median radiation dose to the GTV was 64 Gy (60 -64 Gy). The overall immediate response rate was 64% (18/28). According to the NCI-CTC 3.0, grade 1 and 2 acute radiation-related toxicities occurred in 68% (19/28) and 18% (5/28) of patients for esophagitis, 82% (23/28) and 7% (2/28) for pneumonitis, respectively. Grade 1, 2 and 3 bone marrow suppression occurred in 57% (16/28), 25% (7/28) and 14% (4/28) of patients, respectively. Grade 1 and 2 acute cardiac injuries occurred in 86% (24/28) and 14% (4/28) of patients. Conclusions During CRT for patients with NSCLC, the use of ABC can decrease the radiation dose and acute complications of normal tissues.