GAMMA DOSE DISTRIBUTION EVALUATION OF XiO TREATMENT PLANNING SYSTEM FOR STATIC FIELD IMRT, USING AAPM TG-119

The purpose of this work was to perform a comprehensive comparison of static field intensity modulated radiation therapy (IMRT) for patient specific quality assurance (QA) in order to investigate commissioning of a XiO treatment planning system (TPS). QA measurements were evaluated for three of four test geometries provided in American Association of Physicists in Medicine (AAPM) Task Group Report 119 (TG-119) on multitarget, prostate, head and neck. Using the XiO TPS, fixed-beam IMRT treatment plans were constructed based on the structure sets copied to a parallelepipedic phantom which consists of solid water slabs and the 2D array.The plans were delivered to the phantom using an Elekta Synergy Platform-MLCi2 and the resulting dose distributions were measured in the coronal plane. Measured planar dose distributions were analyzed using gamma index with criteria of 2 %/2 mm and 3 %/3 mm. Also, point measurements were taken five times each using a Farmer type ion chamber situated in the centre of a rectangular water phantom. Measured point doses were analyzed using percentage difference. This study evaluates the response of the XiO TPS for static fields IMRT (step and shoot) using the 2D-array 729, TG-119 geometry sets and gamma analysis. The results showed an adequate level of accuracy for all the analysed specific treatment plans, thus confirming the robustness of this radiotherapy treatment system as a whole.