Quality Control of Intensity Modulated Radiation Therapy (IMRT)

The aim of this study is to ensure the MLC positional and leaf speed accuracy. To check the MLC positional and leaf speed accuracy picket fence and synchronized segmented stripes test pattern were performed. The relative and absolute dosimetric verification were analyzed in this study. This project was followed by Quality control for Intensity-Modulated Radiation Therapy, as in the Recommendation No.15 from SGSMP. For relative dosimetric verification test such as different dose in same depth, same dose in different depth, chair test and inhomogeneous test were performed. All the plans were followed by Gamma index. To verify absolute dose 0.3 cc SemiFlex chamber along with a PTW solid water phantom was used. In picket fence and synchronized segmented stripes test, match-lines appear at -10.0, -5.0, 0.0, 5.0, 10.0 and -12.0, -8.0, -4.0, 0.0, 4.0, 8.0, 12.0 cm respectively from the center of the field. The Gamma Index for the different dose in same depth, same dose in different depth, chair test and inhomogeneous test were 99.48% & -0.52%, 99.35% & -0.65%, 99.04% & -1.96% and 98.34% & -1.66% at the pixel range of -1.00 to 1.00 & 1.00 to 2.00 respectively. Calculated and measured absolute dose for three cases were 2.050 &1.970 (% deviation 4.06), 1.728 & 1.730 (% deviation -0.011) and 1.270 & 1.250 (% deviation 1.6).