(Saturday, 4/4/2020) [Mountain Time (GMT-6)]
Purpose: The objective of this study is to compare 3D-CRT versus Rapid Arc radiotherapy planning in brain gliomas, using linear accelerator (LINAC) using 6 MV & 15 MV energies, in terms of dosimetric outcomes of dose volume histogram (DVH), PTV in terms of Dmean, Dmax and Dmin covered 95% of the target and the doses of organ at risk OARs.
Methods: Plans were created for 15 patients and the prescribed dose was 54Gy in 30 fractions, who had received radical RapidArc treatment from 2018 to 2019 at SKMCH (Shaukat Khanum Memorial Cancer Hospital and Research Centre). After simulation, the CT images were transferred to the External Beam planning system of Eclipse using 6 MV and 15 MV photon beam data. The Photon optimizer (PO) was used for the RapidArc plans. The Anisotropic Analytical Algorithm (AAA) was used for photon dose calculation for all cases
Results: According to statistical data, the mean dose to the PTV was 54.43 in RapidArc and 56.03 in 3D-CRT. The average maximum dose to the PTV was 54.33 in Rapidarc and 59.67 in 3D-CT. The average minimum dose to the PTV was 44.31 in RapidArc and 38.63 in 3D-CRT. The dose to 95% of the PTV was 52.51 in RapidArc to 52.43 in 3D-CRT). Conformity index (CI) was with an average value of 1.099 in RapidArc compared to 1.450 in 3D-CRT.The average homogeneity index (HI) in VMAT was 1.066 and 1.115 in 3D-CRT,all OARs doses were within tolerance in both RapidArc and 3D-CRT plans.
Conclusion: The results of this study show that RapidArc plan achieved lower mean and maximum doses to the PTV. RapidArc (VMAT) is superior to 3D-CRT in terms of PTV, conformity and homogeneity over 3D-CRT, Volumetric modulated arc therapy provides better conformity to the tumor, sparing healthy structures and better low-dose OAR.
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