Treatment Planning Evaluation of Sliding Window and Multiple Static Segments Technique in Intensity Modulated Radiotherapy for Different Beam Directions

Abstract

Objective: The demand of improved dose conformity of the tumor has been increased in Radiation Therapy with the advent of recent imaging facilities and efficient computer technologies. This study was focused to investigate more accurate dose conformity and delivery using intensity modulated radiation therapy (IMRT). Material and Methods: This study was conducted at department of Radiation Oncology Shaukat Khanum Cancer Hospital Lahore during January 2011 to July 2011. Sample Size: Thirteen patients were enrolled. Intensity modulated radiotherapy plans were explored for different beam directions in sliding window and step and shoot technique, using Eclipse Treatment Planning System with Linear Accelerator. Thirteen patients were planned on 15 MV X-ray for 5, 7, 9 and 13 fields making the dose constraints analogous. Results: The rival plans were scrutinized using D_mean, D_max, D_1%, D_95%, dose uniformity index (UI), dose conformity index (CI) and dose homogeneity index (HI). Better coverage for planning target volume was achieved using step and shoot (multiple static segments) technique and reduced the dose to surrounding healthy tissues and organs at-risk (OAR). Conclusion: Step and shoot technique has better results as compared to sliding window technique. Key words, Sliding window (SW), Step and Shoot (SS), IMRT, dose conformity index (CI) and dose homogeneity index (HI), Planning Target Volume (PTV), Dose Volume Histogram (DVH)