الفهرس 
chapter 1Only 14 pages are availabe for public view
 |  | from | 108 |  |  |
| | | from | 108 | | |
Abstract
Breast cancer is one of the most common cancers after skin cancer. This type of cancer can occur in both women and men, but it’s most famous in women. In this study, we will study the radiotherapy of breast cancer. Radiation therapy is common effective ways in cancer treatment. It is usually used as an adjuvant therapy to other ways of treatment. Radiotherapy uses the radiation for damaging cancer cells. There are two types of radiation treatment which are curative or palliative treatment. Radiation destroys cancer cells by breaking up its molecules and affects the ability of the cell dividing. There are many sources of radiation such as x-rays, gamma-rays and other many types. Radiation treatment has two types. First, the external radiation therapy in which we used directly from a remote source. Second, the internal radiation therapy is called brachytherapy .In the internal radiation therapy is used the radioactive source inside the patient’s body and destroyed cancer cells. In Our study is interested in left breast cancer treatment using external radiation therapy. linear accelerator (linac) represents that remote source which directs the radiation to the tumor from outside the patient’s body. This study shows evaluation of factors effect in cumulative radiotherapy dose volume histogram: heterogeneity correction, interpolation, matrix size (number of points on DVH). Our study shows a statistic comparison between two plans in case of heterogeneity correction, two plans in case of interpolation and six plans in case of matrix size. Our study includes the effect of heterogeneity correction, interpolation and matrix size on conformity index (CI), homogeneity index (HI), planning target volume (PTV), and organs at risk (OARs) dose using the dose volume histogram (DVH) analysis. The first aim of this study is to conclude which plans are more better. from the results we found that all the two plans allow good dose coverage to the PTV where 95% of the target volume is covered with 95% of the prescribed dose for left breast cancer. When there are lost contouring in one cut or more of the patient imaging data, using interpolation makes automatic contouring where the result is good. We recommend using interpolation for left-sided breast cancer because of the results are approximately equal. In case of heterogeneity correction, we study the effect of it on dose volume histogram (DVH) and dose distribution uniformity. In case of matrix size, we study the effect of increasing of it on dose volume histogram (DVH) and dose distribution uniformity.