American Journal of Medicine and Medical Sciences 2015, 5(5): 208-219 DOI: 10.5923/j.ajmms.20150505.04 Dosimetric Comparison of 3DCRT Versus RapidArc in Terms of Iso-dose Distribution, Dose Volume Histogram (DVH) and Dosimetric Results for the PTV and Critical Organs for Glioblastoma (GBM) H. A. Sharyan 1 , S. H. Allehyani 1,* , A. R. Tolba 1,2 1 Medical Physics Group, Physics Dept, College of Applied Science, Umm ALQura University, Makkah, Saudi Arabia 2 Radiotherapy and Nuclear Medicine Department, National Cancer Institute, Cairo University, Cairo, Egypt Abstract Purpose: The aim of the present study is to compare (3D-CRT) to RapidArc planning using (LNAC of 6 MV, 15 MV and 18 MV) in terms of dosimetric outcomes of iso-dose distribution, dose volume histogram (DVH), PTV and at risk organs in 11 patients with glioblastoma (GBM). Methods: Plans were created for 11 patients with GBM who had received radical RapidArc treatment from 2012 to 2014 at KAMC (King Abdullah Medical City). Dosimetric evaluation metrics were used to compare the two plans in terms of mean, maximum and minimum doses to PTV, Homogeneity Index (HI), Conformity Index (CI), Target Coverage Index (TCI) and mean and maximum doses to critical organs and normal tissue. Dose to 95% of the PTV (D95%) was used to quantify PTV coverage. Results: RapidArc plan achieved lower mean and maximum doses to the PTV. PTV dose coverage, as measured by the minimum dose and the dose to 95% of the volume, was higher in the RapidArc plan. RapidArc plan also showed a more homogeneous dose distribution in PTV, achieving an HI of 1.0559 compared with 1.0853 in the 3D-CRT plan. However, RapidArc and 3D-CRT achieved similar CI values and improvement in TCI value. Additionally, regarding OARs, the mean and maximum dose in right optic nerve (RON) was lower in RapidArc with a low percentage of the volume receiving low doses. Optic chiasms were within tolerance in RapidArc and 3D-CRT. Although the mean dose was better in 3D-CRT, critical structure was better in the RapidArc plan. RON was lower in RapidArc, while LON was lower in 3D-CRT, and the optic chiasm was approximately equal for both techniques. For brain stem, the maximum dose was within tolerance criteria in RapidArc but exceeded the criteria in 3D-CRT at 60.97 Gy. For the spinal cord, the maximum dose was notably low and did not exceed 1.91 Gy in RapidArc, while it exceeded the acceptable limit in 3D-CRT. Conclusions: (VMAT) is superior to 3D-CRT in term of PTV, conformity and homogeneity and accepting the VMAT class solution over 3D-CRT treatment was preferred to be determined on a case by case basis. Keywords Planning Tumor Volume, Organs at Risk, Conformity Index, Heterogeneity Index, Head cancer 1. Introduction 1.1. Management of Patients with Cancer The optimal care of patients with malignant tumors is a multidisciplinary effort that combines classic modalities, surgery, radiation therapy, and chemotherapy. The role of the radiation oncologist is to assess all conditions relative to the patient and tumor, to systematically review the need for diagnostic and staging procedures, and, in consultation with other oncologists, determine the best therapeutic strategy. * Corresponding author: saud8882001@yahoo.com (S. H. Allehyani) Published online at http://journal.sapub.org/ajmms Copyright © 2015 Scientific & Academic Publishing. All Rights Reserved Radiation oncology includes the clinical and scientific discipline devoted to management of patients with cancer (and other diseases) with ionizing radiation (alone or combined with other modalities), investigation of the biologic and physical basis of radiation therapy, and training of professionals in the field. The aim of radiation therapy is to deliver a precisely measured dose of irradiation to a defined tumor volume with minimal damage to surrounding healthy tissue. This results in eradication of the tumor, increased quality of life, and prolongation of survival at a competitive cost, and allows for effective palliation or prevention of symptoms of cancer, including pain, restoring luminal patency, skeletal integrity, and organ function, with minimal morbidity [1, 2].