Original Article
Dosimetric comparison of helical tomotherapy and conventional Linac-based X-knife stereotactic body radiation therapy for primary lung cancer or pulmonary metastases
Abstract
Background: To compare helical tomotherapy (HT) with X-knife stereotactic body radiation therapy (HT-SBRT/X-SBRT) for primary or metastatic lung cancer regarding planning target volume (PTV) coverage, such as homogeneity index (HI), conformity index (CI) and dose-volume histogram (DVH) of organs at risk (OARs).
Methods: We retrospectively analyzed 21 patients receiving definitive radiation treatment for non-small cell lung cancer (NSCLC) or pulmonary metastases at our institution between March 2015 and October 2016. Tumors were irradiated with 4–10 Gy per fraction in 5–15 fractions. Plans were compared according to PTV coverage and OARs sparing.
Results: Significant differences between HT and X-knife were observed for both HI (P=0.003) and CI (P<0.001). The V5 (P=0.001), V10 (P=0.009), V20 (P=0.001), the mean lung dose (P=0.005) of total lung and maximum dose of the spinal cord (P=0.010) were significantly lower in the X-SBRT group than the HTSBRT group. There were no significant differences for the V30 (P=0.075) and the mean heart dose (P=0.584) between the two groups.
Conclusions: X-SBRT was dosimetrically superior to HT-SBRT, when applied in these tumors’ maximum diameters <5 cm. As HT resulted in increased low-dose volume, it is essential to optimize the patient selection in order to avoid severe radiation pneumonitis in HT-SBRT.
Methods: We retrospectively analyzed 21 patients receiving definitive radiation treatment for non-small cell lung cancer (NSCLC) or pulmonary metastases at our institution between March 2015 and October 2016. Tumors were irradiated with 4–10 Gy per fraction in 5–15 fractions. Plans were compared according to PTV coverage and OARs sparing.
Results: Significant differences between HT and X-knife were observed for both HI (P=0.003) and CI (P<0.001). The V5 (P=0.001), V10 (P=0.009), V20 (P=0.001), the mean lung dose (P=0.005) of total lung and maximum dose of the spinal cord (P=0.010) were significantly lower in the X-SBRT group than the HTSBRT group. There were no significant differences for the V30 (P=0.075) and the mean heart dose (P=0.584) between the two groups.
Conclusions: X-SBRT was dosimetrically superior to HT-SBRT, when applied in these tumors’ maximum diameters <5 cm. As HT resulted in increased low-dose volume, it is essential to optimize the patient selection in order to avoid severe radiation pneumonitis in HT-SBRT.
