ISSN: 1859 - 2872
Evaluating dose distribution to the volume regions of VMAT treatment plans using 6MV, 6FFF, 10MV and 10FFF beams for cervical cancer treatment at Hospital K
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Abstract
Objective: To evaluate the dose distribution of VMAT radiotherapy plans using flattened Filter (FF) and flattened Filter Free (FFF) beam with 6MV and 10MV energy in the radiotherapy treatment of cervical cancer. Subject and method: This descriptive study included 15 patients with cervical cancer who received whole pelvic irradiation with a dose of 45Gy in 25 fractions. VMAT treatment plans were planned using 6FFF, 10MV, and 10FFF beams. Plans with the same energy level used the same optimization costfunctions and dose constraints. Treatment plans were evaluated through dose-volume histogram (DVH), conformity index (CI), homogeneity index (HI), monitor units (MU), beam-on time (BOT), and doses to organs-at-risk (OARs). Result: Our results showed similar coverage of the prescribed dose to the planning target volume (PTV) for all energy levels. The mean dose values of PTV were 4409.81 ± 29.94, 4407.96 ± 25.92, 4409.53 ± 26.24, and 4411.90 ± 26.35 for the 6MV, 6FFF, 10MV, and 10FFF plans, respectively. The homogeneity and conformity index of the plans were also similar, with mean HI and CI values of 0.88 and 0.87, respectively. However, plans using FFF beams had lower doses to low-dose receiving normal tissues and were statistically significant compared to FF plans. The monitor units (MU) of the FFF beam plans (mean 1027.87 ± 128.13 and 1141.22 ± 159.30 for the 6FFF and 10FFF plans, respectively) were higher than the FF beam plans (mean 803.14 ± 103.09 and 737.88 ± 71.34 for the 6MV and 10MV plans, respectively), but the beam-on time was shorter. The mean beam-on time for the 6MV and 10MV plans were 96.38 ± 12.36 and 88.55 ± 8.56 seconds, respectively. The beam-on time for the 6FFF and 10FFF plans were only 51.39 ± 6.41 and 34.24 ± 4.78 seconds, respectively. Conclusion: VMAT treatment plans for cervical cancer using 6MV, 6FFF, 10MV, and 10FFF beams met the criteria for plan evaluation. The dose distribution to the target volume was not significantly different among the plans, but plans using FFF beams have significantly reduced beam-on times.
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References
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