نتایج جستجو برای: megavoltage photons
تعداد نتایج: 47760 فیلتر نتایج به سال:
Currently portal imaging devices are used to obtain information on patient localization during radiation therapy treatments. Such obtained information is two dimensional in nature, limited to the plane of the captured image. It has been proposed that megavoltage computed tomography images be reconstructed to overcome this limitation. This study explores the feasibility of reconstructing tomogra...
Most of the treatment units, both new and old models, are equipped with a megavoltage portal imager but its use for volumetric imaging is limited. This is mainly due to the poor image quality produced by the high-energy treatment beam (> 6MV). A linac at our center is equipped with a prototype 2.5 MV imaging beam. This study evaluates the feasibility of low-dose megavoltage cone-beam imaging wi...
BACKGROUND AND PURPOSE An analysis of the current radiotherapy status in Turkey was conducted to establish a comprehensive baseline. Turkey's future demand analysis in view of international benchmarks was conducted. Moreover, the ministerial plans are shared to present an example for making a comprehensive planning in developing countries. METHODS The data from all radiotherapy centers in Tur...
OBJECTIVE To compare neutron treatment and megavoltage (photon) radiotherapy in locally advanced squamous cell carcinoma of the head and neck. DESIGN Randomised trial of patients stratified by site of primary tumour and presence or absence of lymph node metastases. Follow up of patients after treatment. SETTING Department of clinical oncology, Western General Hospital, Edinburgh. PATIENTS...
Two of the most popular dosimetry systems used for calibration of megavoltage photon and electron beams in radiation therapy are (i) cylindrical Farmer-type chambers in liquid water and (ii) Holt Memorial parallel-plate chambers in clear polystyrene. Since implementation of the AAPM TG-21 calibration protocol, the Radiological Physics Center (which uses the Farmer in-water system) has compared ...
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