الفهرس 
Chapter 1 Introduction and Literature ReviewOnly 14 pages are availabe for public view
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Abstract
Brain tumors are the leading cause of death in females aged 20 and under and males aged 40 and under. According to the World Health Organization (WHO), brain cancers are exceedingly heterogeneous, which poses a fundamental challenge for brain tumor categorization and segmentation, and thus diagnosis and prognosis. A brain tumor is an uncontrolled, growing clump of tissue that is stifling surrounding healthy tissue. Malignant and benign brain tumors are two different types of tumors that can develop in the brain. The symptoms that manifest depend on the location, growth rate, and impact of the tumor mass on the brain tissue. Radiation therapy (RT) plays a critical role in the management of cancer patients. The goal of radiotherapy is to achieve tumor control without causing complications. The modern linear accelerator has evolved into a highly precise tool capable of depositing a specific dose into a specific volume of tissue. Each patient who undergoes curative radiotherapy has an individualized treatment plan. Often, an ideal plan cannot be created, and the chosen clinical approach represents a trade-off between ensuring that the dose to the tumor is acceptable while minimizing the risk of complications to normal tissue. Physical parameters such as homogeneity index (HI), target coverage index (TCI), prescription isodose to target volume (PITV) ratio, conformity index (CI), conformity number (CN), gradient index (GI), gradient measure (GM), critical organ scoring index (COSI), modified critical organ scoring index (MCOSI), and quality factor (QF) shall be used to evaluate the treatment planning, but this is insufficient because there are different factors affecting the treatment outcome. These factors are : number of fractions and fraction size (dose fractionation), overall treatment time, type of tumor (its radiosensitivity), dose, and volume of healthy tissue. These factors are considered biological parameters, including tumor control probability (TCP), normal tissue complication probability (NTCP), and free complication tumor control (P+). Biologic indices are an alternative method for evaluating treatment plans that take biological parameters into account. Criteria for an optimal plan include both the biological and physical aspects of radiation oncology. The purpose of this study is to report on the planning experience while taking into account the performance and clinical outcomes of patients with Glioblastoma (GBM). Choosing the best plan for conventional or hypo-fractionation is a highly subjective process. We used identified CT data sets from 20 patients with GBM cancer who had been treated at the Department of Oncology, Radiotherapy, and Nuclear Medicine, Faculty of Medicine, Ain Shams University, Cairo, Egypt, with VMAT using a conventional schedule of 60 Gy in 30 fractions at 2 Gy per fraction. The VMAT treatment plans of those patients have been recalculated using a hypo-fractionated schedule with 40 Gy in 15 fractions, or 2.68 Gy per fraction. In all applied plans, the anisotropic analytical algorithm (AAA) was used for dose calculation in the eclipse treatment planning system version v13.5. The results have led to the safe use of hypo-fractionated RT for different tumors which benefits the waiting lists of patients in many hospitals, especially in cases of pandemics. Chapter 1 contains an introduction to the brain’s anatomy, functions, and disorders. A brain tumor, for example, is one of the leading causes of death. The role of radiotherapy has been discussed since then. The relevant literature survey has been explored to indicate the importance of our study and to show the progress of the radiotherapy fractionation schedule for treatment of different tumors. Chapter 2 explores the basics and the different types of radiation. In addition, the effects of radiation on tissues and organs and the treatment of radiation therapy and its different types. In chapter 3, the basic aspects of radiotherapy planning are outlined. We have illustrated the procedure for treatment planning evaluation using different physical and radiobiological metrics. The different physical and radiobiological metrics are calculated in chapter 4, to evaluate the RT planning fractionation (conventional and hypo) for the 20 patients under study with GBM brain tumors. The conventional fractionation method gives better dose conformity to the target, but the given doses to the critical organs are relatively high in some cases. However, hypo-fractionation provides better conformity to the tumor, with safer parameters and a lower dose for organs at risk (OAR), in addition to saving time. Statistically, the calculated metrics showed good significance between conventional and hypo-fractionated radiotherapy (RT).