Dosimetric comparison of 3-dimensional conformal radiotherapy, volumetric modulated arc therapy, and helical tomotherapy for postoperative gastric cancer patients

To compare dosimetric data for the planning target volume (PTV) and organs at risk (OARs) between 3-dimensional conformal radiotherapy (3DCRT), volumetric modulated arc therapy (VMAT), and helical tomotherapy [1]. The dosimetric data for 15 gastric cancer patients treated with 3DCRT, VMAT, or HT techniques were used. Cumulative dosimetric parameters, homogeneity index (HI), and conformal index (CI) were compared for the PTV and OARs. The average maximum doses of PTV were significantly higher in VMAT plans than in 3DCRT (p = 0.04) and HT (p = 0.02) plans, whereas minimum dose values were significantly lower in 3DCRT plans compared with VMAT (p < 0.001) and HT (p = 0.02) plans. Liver mean dose (D (mean)) and D (mean) values for both kidneys were significantly lower in HT plans than in 3DCRT and VMAT plans. The doses in high dose regions (V30-V45) using 3DCRT plans were significantly higher compared to both VMAT and HT plans. The bowel V5-V30 and V45 was significantly less in HT plans compared to VMAT plans. There were no significant differences in dose sparing of the spinal cord. The HT plans reduced the maximum dose applied to the target and improved the conformality and homogeneity of radiation, while providing sufficient PTV coverage.