الفهرس 
Introduction and Literature ReviewOnly 14 pages are availabe for public view
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Abstract
Radiotherapy treatment aims to deliver the maximum dose to the tumor and the minimum dose elsewhere. During fractionated radiation therapy, setup errors are an inherent part of the radiation treatment process. Image Guided Radiation Therapy (IGRT) can be used to increase the agreement between planned treatment and the actual delivered dose to the patient.
In this work setup errors are detected using (EPID). The specific patient (personalized/ individual) setup errors are applied on Head and Neck (H&N) and prostate Volumetric modulation Arc therapy (VMAT) treatment plans using the Simultaneous Integrated Boost (SIB) technique by varying the plan isocenter to evaluate the extent of the effect of setup errors and to investigate their impact on target volumes with the help of Dose-Volume Histogram (DVH) parameters and dosimetric indices.
Results show that prostate random errors are (3.61), (3.24), and (3.87) mm in vertical, longitudinal, and lateral directions, respectively. H&N random errors are 1.45, 2.33, and 1.41 mm in vertical, longitudinal, and lateral directions, respectively.
For 20 H&N patients, significant differences are reported between original and shifted Planning Target Volumes (PTVs) due to setup errors. After consideration of setup errors for the planning target volumes (PTV-70). The mean, maximum, and minimum doses delivered to the target volume are significantly different. Significant deteriorations in target dose homogeneity for target-70.
For 10 prostate patients, at the individual level, the mean, maximum, and minimum were always different from the original isocenter compared to shifted isocenter for planning target volume -78(PTV-78). Significant reduction in the dose conformity is observed for target-78 as measured using the CI parameter. Significant reduction in the homogeneity of target dose distribution (higher HI values) for shifted targets is also reported compared to original plans.
This work shows that it would be recommended to implement a weekly EPID procedure for H&N and prostate VMAT patients. The dosimetric and biological impacts were evaluated and indicated that setup errors during VMAT treatments can lead to a non-significant change of conformity and homogeneity but can lead to changes in the dose distribution influencing the target volume coverage and altering the delivered dose to the organs at risk (OAR).