Introduction: Nasopharyngeal carcinoma is one of the most common malignancies in the head and neck region and radiotherapy is its treatment of choice. In spite of the fact that it is widely used, due to the presence of many sensitive organs or tissues in this region, patients may suffer from a wide range of side effects. One such sensitive tissue is the spinal cord. If the absorbed dose to spin...

A correction method for inhomogeneity of magnetic resonance (MR) images was developed based on renormalization transformation. It is a post-processing algorithm on images. Unlike previous post-processing methods, which need to determine either a filter size or a free adjustable parameter for different applications, this presented method is fully automated. Tests on physical phantom data, patien...

The purpose of this study was to investigate the impact of different CBCT imaging monitor units (MUs), reconstruction slice thicknesses, and planning CT slice thicknesses on the positioning accuracy of a megavoltage cone-beam computed tomography (MV-CBCT) system in image-guided radiation therapy (IGRT) in head-and-neck patients. The MV-CBCT system was a Siemens MVision, a commercial system inte...

introduction: in patients with thyroid carcinoma, radiation absorbed doses of the thyroid and surrounding tissues is important to weigh risk and benefit considerations. in nuclear medicine, the accuracy of absorbed dose of internally distributed radionuclides is estimated by different methods such as mird and direct method using tld. the aim of this study is using tld and a phantom to determine...

The rise in popularity of ultrasound imaging has seen a corresponding increase in demand for effective training tools such as phantom models. They are especially useful for teaching and practice of invasive procedures, such as fine-needle aspiration of lesions of the head and neck. We have created 2 gelatin models out of inexpensive, commonly available materials that can be used in sequence to ...

The aim of this study was to develop and apply an evaluation method for assessing the accuracy a novel 3D EPID back-projection algorithm in vivo dosimetry. Dosimetry Check (DC) 5.8 evaluated. A slab phantom homogeneously filled, or with air bone inserts, used fluence reconstruction different squared fields. VMAT plans anatomical sites were delivered on anthropomorphic phantom. Dose distribution...

Introduction: Critical organs and structures may receive significant amounts of irradiation even if they are not the target of radiotherapy or located outside the treatment field. Although the sensitive thyroid gland and lens are not directly the targets of treatment, they can be affected by irradiation during the treatment of tumours in head and neck region. The purpose of thi...

background: radiotherapy plays an important role in the management of most malignant and many benign primary central nervous system (cns) tumors. radiotherapy affects both tumor cells and uninvolved normal cells; so, it is important to estimate absorbed dose to organs at risk in this kind of treatment. the aim of this study was to determine the absorbed dose to chiasma, lens, optic nerve, retin...

We have segmented CT torso+head and MRI head slices of two living human males. The manually segmented 129 x-ray CT transverse slices were used to create a computerized 3dimensional volume array modeling all major internal structures of the body. The original xray CT images were reconstructed in a 512x512 matrix with a resolution of 1 millimeter in the x,y plane. The z-axis resolution is 1 centi...