Rounded leaf end effect of multileaf collimator on penumbra width and radiation field offset: an analytical and numerical study

摘要: Background. Penumbra characteristics play a significant role in dose delivery accuracy for radiation therapy. For treatment planning, penumbra width and field offset strongly influence target conformity organ at risk sparing. Methods. In this study, we present an analytical numerical approach evaluation of the rounded leaf end effect on characteristics. Based rule half-value layer, algorithms position calculation correction are developed, which advantageous particularly dealing with large radius end. Computer simulation is performed based Monte Carlo codes EGSnrc/BEAMnrc, groups radii source sizes. Data processing technique curve fitting employed deriving offset. Results. Results show that increases size. curves U-shaped. This observation probably related to fact beams penetrate through proximal distal sides. contrast, size has negligible impact Radiation offsets found be constant both method simulation. However, overall resulting values obtained by slightly smaller compared Conclusion. The proposed could provide insight into investigation calibration should carefully commission multileaf collimator intensity modulated radiotherapy.