Static intensity-modulated radiotherapy versus volumetric modulated arc therapy in dosimetric parameters of target area and organs at risk for middle thoracic esophageal cancer

Objective To compare the dosimetric parameters of target area and organs at risk for middle thoracic esophageal cancer between static intensity-modulated radiotherapy(sIMRT)and volumetric modulated arc therapy(VMAT). Methods Totally 22 patients with middle thoracic esophageal cancer were selected. The target area and organs at risk were delineated by Pinnacle 10.0 therapeutic plan system. The sIMRT and VMAT plans were designed and the dosimetric parameters were analyzed. Results In the comparison of PGTV, the dose of 2% volumetric tumor target area for radiation(D₂), the median dose of tumor target area for radiation(D₅₀)and the uniformity index(HI)of tumor target area by treatment of sIMRT were significantly higher than those by VMAT, while conformal index(CI)of tumor target area was significantly lower than VMAT(P<0.05). In the comparison of PTV, the dose of 98% of tumor target area for radiation(D₉₈)and CI by sIMRT were significantly lower than those by VMAT, while HI was significantly higher than that by VMAT(P<0.05). The percentage of volume of whole lung exposed to 5 Gy radiation(V₅), V₁₀, V₁₅, V₂₀, V₃₀, - V₄₀ and average radiation dose(D_mean)by VAMT were lower than those by sIMRT, and except for V₃₀ and V₄₀, there were significant differences in V₅, V₁₀, V₁₅, V₂₀ and D_mean between VAMT and sIMRT(P<0.05). The cardiac V₂₅, V₃₀, V₃₅, V₄₀ and D_mean by VMAT were significantly lower than those by sIMRT(P<0.05). Conclusion Both sIMRT and VMAT can meet the clinical needs, but the CI and HI of VMAT are better, and VMAT has better of effect than sIMRT in protection of lung, heart and spinal cord.