Clinical use of stereotactic 3-D conformal multiple dynamic arc radiotherapy for stage I non-small cell lung cancer using a linear accelerator combined with self-moving ct scanner and patient’s self-breath and beam control technique

Abstract

Purpose/Objective: In the last ASTRO meeting, we presented a new irradiation system for lung cancer: patient’s self-breath-hold and self-turning radiation-beam on and off using a linear accelerator combined with a self-moving CT scanner. The purpose of the current study is to apply this system for the stereotactic 3-D conformal radiotherapy of stage I non-small cell lung cancer and to evaluate its clinical outcomes. Materials/Methods: Twenty-two patients with stage I (11 T1N0, 11 T2N0) primary non-small cell lung cancer who were treated between October 2000 and November 2001 were included in this study. The patients ranged from 68 to 92 years of age with a median of 78 years. The performance status was better than WHO grade-2 in all but two patients of Parkinson’s disease and pulmonary fibrosis. The histology was adenocarcinoma in 15, squamous cell carcinoma in 7 cases. Tumor size ranged from 13 to 48 mm with a median of 30 mm. Planning target volume (PTV) was determined to include the gross tumor volume on CT scan, 3mm for respiratory internal margin and 5mm for the safety margin. The three-dimensional treatment plannings were made using 10 different non-coplanar dynamic arcs of which couch angles were between -20deg. and 25deg. A total dose of 60Gy in 10 fractions (daily 2 fractions) at the minimum dose point in PTV was delivered with 6MV X-ray over 5 to 8 days. In the simulation, every patient was taught sufficiently how to hold the breath at a same inspiration phase, and CT scans under the patient’s self-judged breath-hold were performed 3 times to confirm that the respiratory reproducibility was within 3 mm. After the isocenter of the PTV was adjusted to the planned position by the CT combined with the linear accelerator under the patients’ self-judged breath-hold at inspiration phase, they turned the radiation-beam on and off repeatedly at their own agreeable pace by the handheld switch until they filled up the monitor units. Results: All patients completed the treatment without any complaints. During the follow up of 4-17 (median=10) months, no pulmonary complications greater than NCI-CTC criteria of grade 1 were noted in all patients. None of the patients experienced symptomatic radiation esophagitis. The one-year local control rate was 100%. One-year overall survival was 100%. No patients showed metastasis on resional lymphnodes or distant site. Conclusions: This new irradiation technique, by which patients turned the radiation beam on and off by their hand-held switch under self-judged inspired breath-hold after a precise adjustment of the isocenter to the planned position with the combination of CT scanner and linear accelerator, permitted us to perform the high dose stereotactic irradiation safely with an enough margin around the clinical target volume. Based on the initial clinical results, excellent local control with minimal symptomatic complications can be achieved for stage I non-small cell lung cancer.