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Abstract
n this study a dosimetric measurements are done for IMRT in the buildup region with different measurement tools (Gafchromic films, parallel plate ion chamber and TPS) at different gantry angle to assess the discrepancies in this region figure (3-1) and table (3-1).The study provide also the most accurate collimation method in the small fields either MLC only or MLC+Jaws to assess which of them can help the treatment planning system tabulated dosimetric functions to introduce a precise dose calculation. In the same way assessments of the output factor and leaf transmission are measured. Technical and dosimetric parameters related to the use of small shaped MLC field size are investigated in terms of the evaluation of MONACO version 3.3.0 versus XIO version 5.0.0, biological and physical optimization and dynamic and static MLC, using the chair, penumbral and different doses tests. This study revealed that the beam data measurements that will be used in the modeling of small shaped MLC field sizes have to be measured by MLC only without jaws to mimic the real condition of using MLC in shaping small irregular fields. Also, the results indicate that MONACO biological optimization is better than XIO physical optimization. Dynamic plan delivery is time saving more than static plans with no side effect on the plan quality