Download or read book Patient Dose Verification for Image-guided Radiation Therapy Using a Deformable Registration Tool written by Amanda Dyess and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "Patient geometry often changes during the course of radiation therapy due to factors such as weight loss, tumor and normal tissue growth or shrinkage, and intra-treatment position variations. It has been shown that these changes can cause the dose delivered to differ from the originally planned dose distribution. Often this will result in the need to create a modified treatment plan, a process known as adaptive radiation therapy. The aim of this thesis is to evaluate the dosimetric effects due to anatomical changes and positioning variations during intensity-modulated radiation therapy through two retrospective studies. MIM Software (Cleveland, OH), a commercially available deformable registration tool, is used for this work. In the first study, the daily dose for four breast cancer patients undergoing a volumetric modulated arc boost treatment to the tumor bed is calculated on pretreatment cone beam computed tomography images. Two treatment isocenters, corresponding to the initial patient set up position, and the shifted position based on pretreatment imaging, are used for dose verification. The results indicate that a planning target volume consisting of the tumor bed and a uniform margin expansion of 1 cm is adequate to account for positioning errors. In the second study, the daily dose is calculated on the pretreatment megavoltage computed tomography images for craniospinal irradiation and head and neck cancer patients undergoing helical tomotherapy. The dose for each treatment fraction is deformed and accumulated to the planning computed tomography image for comparison with the original plan. This study assesses the effects of anatomical changes on treatment delivery. The results indicate a slight decrease in target coverage and no significant increase in dose to critical structures. " --