Comparison of combinations of irradiation techniques and jaw conditions in intensity-modulated radiotherapy for lung cancer.

Purpose To assist in the selection of a suitable combination of an irradiation technique and jaw condition in intensity-modulated radiotherapy (IMRT) and volumetric-modulated arc radiotherapy (VMAT) for lung cancer treatment plans. Materials and methods Thirty patients with lung cancer who underwent radiotherapy were enrolled retrospectively. They were categorized as having central lung cancer, peripheral lung cancer with mediastinal lymph node metastasis (peripheral E lung cancer), and peripheral lung cancer without mediastinal lymph node metastasis (peripheral N lung cancer). Four treatment plans were designed for each patient: fixed jaw and adaptive jaw IMRT technique (FJ-IMRT and JA-IMRT), and fixed jaw and jaw tracking VMAT technique (FJ-VMAT and JT-VMAT). The dose parameters of the four group plans were compared and analyzed. Results Compared to FJ-IMRT, JA-IMRT significantly reduced the mean dose (Dmean ) and volume percentage of 5 Gy (V5Gy ) of the total lung in central and peripheral N lung cancer. Similarly, compared to FJ-VMAT, JT-VMAT provided better protection to most organs at risk (OARs), particularly for total lung and heart. In comparison with IMRT, VMAT significantly improved the conformity index (CI) of the planning target volume for the three lung cancer classifications, and it reduced the dose of almost all OARs except V5Gy and Dmean of the total lung. Moreover, the mean monitor units of the VMAT groups were far lower than the IMRT groups. Conclusion Based on the dosimetric findings and considering clinical data published on lung and heart side effects, we propose recommendations on the preferred treatment technique based on tumor location and pulmonary function. For central lung cancer with normal pulmonary function, we advise JT-VMAT techniques. Conversely, for central lung cancer with poor pulmonary function, we recommend JA-IMRT techniques. We advocate JA-IMRT for peripheral E lung cancer. For peripheral N lung cancer, JT-VMAT techniques are strongly recommended.