Document Type : Original Paper
Rajiv Gandhi Cancer Institute &amp; Research Center, New Delhi, India
Department of Applied Science & Humanities, Bundelkhand Institute of Engineering & Technology, Jhansi, India
Medical Physics Division, Radiation Oncology Department, Rajiv Gandhi Cancer Institute &amp; Research Centre, Sector-5, Rohini, Delhi-110085
Department of Medical Physics, Rajiv Gandhi Cancer Research Center Delhi
Medical Physics Division & Radiation Oncology Department,Rajiv Gandhi Cancer Institute and Research Center, New Delhi, India
Medical Physics Division & Radiation Oncology Department, Rajiv Gandhi Cancer Institute and Research Center, New Delhi,India
Introduction: To compare the dosimetric outcomes of 6 and 10 MV flattening filter free beam (FFFB) energies in gynaecological malignancies RapidArc (RA) planning.
Material and Methods: The RA plans were generated for a cohort of 20 patients using 6 and 10 MV FFFBs. The plans aimed to deliver a dose of 50.4Gy in 28 fractions to planning target volume (PTV); moreover, planning objectives were kept as low as reasonably achievable for organs at risk (OARs). Dosimetric analysis was performed in terms of PTV coverage, conformity index (CI), homogeneity index (HI), dose to OAR’s, integral dose to normal tissue (NTID), and total number of monitor units (MU’s).
Results: According to the results, volumes of PTV receiving prescription dose and CI values were 95.03±0.10% and 95.02±0.18%, as well as 1.018±0.028 and 1.024±0.027, respectively. Moreover, HI values were estimated at 1.063±0.008 and 1.068±0.010. Additionally, the corresponding values of mean NTID and MUs were 280.3±42.5 and 267.9±39.1 (liter-Gy), as well as 610.3±30.3 and 630.6±39.7 for FFFB using 6 and 10 MV, respectively. The 6 and 10 MV FFFBs were statistically similar in terms of mean dose to bladder, rectum and both femoral heads, while comparison yielded significant difference (p <0.05) in terms of HI, CI, MUs and NTID.
Conclusion: The FFFB of 6MV was found superior, compared to 10MV, for RA planning in case of gynaecological malignancies. Moreover, it offers better HI and CI values, as well as fewer numbers of MUs (3.33%). In addition, it delivers more NTID (4.42%) for similar target coverage and OAR’s sparing.