Superiority of conventional intensity-modulated radiotherapy over helical tomotherapy in locally advanced non-small cell lung cancer A comparative plan analysis

To compare helical tomotherapy (HT) and conventional intensity-modulated radiotherapy (IMRT) using a variety of dosimetric and radiobiologic indexes in patients with locally advanced non-small cell lung cancer (LA-NSCLC). A total of 20 patients with LA-NSCLC were enrolled. IMRT plans with 4-6 coplanar beams and HT plans were generated for each patient. Dose distributions and dosimetric indexes for the tumors and critical structures were computed for both plans and compared. Both modalities created highly conformal plans. They did not differ in the volumes of lung exposed to > 20 Gy of radiation. The average mean lung dose, volume receiving a parts per thousand yenaEuro parts per thousand 30 Gy, and volume receiving a parts per thousand yenaEuro parts per thousand 10 Gy in HT planning were 18.3 Gy, 18.5%, and 57.1%, respectively, compared to 19.4 Gy, 25.4%, and 48.9%, respectively, with IMRT (p = 0.004, p < 0.001, and p < 0.001). The differences between HT and IMRT in lung volume receiving a parts per thousand yenaEuro parts per thousand 10-20 Gy increased significantly as the planning target volume (PTV) increased. For 6 patients who had PTV greater than 700 cm(3), IMRT was superior to HT for 5 patients in terms of lung volume receiving a parts per thousand yenaEuro parts per thousand 5-20 Gy. The integral dose to the entire thorax in HT plans was significantly higher than in IMRT plans. HT gave significantly better control of mean lung dose and volume receiving a parts per thousand yenaEuro parts per thousand 30-40 Gy, whereas IMRT provided better control of the lung volume receiving a parts per thousand yenaEuro parts per thousand 5-15 Gy and the integral dose to entire thorax. In most patients with PTV greater than 700 cm(3), IMRT was superior to HT in terms of lung volume receiving a parts per thousand yenaEuro parts per thousand 5-20 Gy. It is therefore advised that caution should be exercised when planning LA-NSCLC using HT.