نتایج جستجو برای: dosimetry protocols
تعداد نتایج: 108295 فیلتر نتایج به سال:
The ultimate check of the actual dose delivered to a patient in radiotherapy can only be achieved by using in vivo dosimetry. This work reports a pilot study to test the applicability of a thermoluminescent dosimetric system for performing in vivo entrance dose measurements in external photon beam radiotherapy. The measurements demonstrated the value of thermoluminescent dosimetry as a treatmen...
UNLABELLED Adult PET/CT acquisition protocols need to be modified for pediatric imaging to minimize the radiation dose while maintaining diagnostic utility. We developed pediatric PET/CT acquisition protocols customized to patient weight and estimated the dosimetry and cancer risk of these low-dose protocols to communicate basic imaging risks. METHODS Protocols were developed for whole-body (...
Background: Since 1984 MRI gel dosimetry has been introduced as a potential technique for 3D dosimetry. Most of the studies have measured R1 (1/T1) or R2 (1/T2) properties of the gel depending on the gel type. We have studied image intensity change in the Fricke gel by different MRI protocols. Materials and Methods: Gel Dosimeters contain 0.4 mM ferrous sulphate, 1 mM NaCl, 50 mM H2SO4 and 1% b...
ارزیابی کیفیت تصویر و دز دریافتی بیماران در ماموگرافی فیلم اسکرین و ماموگرافی کامپیوتریشده در ایران
In this study, a quantitative parameter is introduced that evaluate three important features of a mammography exam ,contrast, spatial resolution and patient dose. Two kinds of regular mammography system used in screening mammography were evaluated in automatic exposure control mode (AEC) by this parameter. To evaluate the contrast and detail of the mammography images, the contrast-detail phanto...
introduction intensity modulated radiation therapy (imrt) has made a significant progress in radiation therapy centers in recent years. in this method, each radiation beam is divided into many subfields that create a field with a modulated intensity. considering the complexity of this method, the quality control for imrt is a topic of interest for researchers. this article is about the various ...
Current dosimetry protocols recommend the use of plane-parallel ionization chambers for the dosimetry of clinical electron beams. The necessary perturbation corrections p(wall) and p(cav) are assumed to be unity, independent of the depth of measurement and the energy of the primary electrons. To verify these assumptions detailed Monte Carlo studies of a Roos chamber in clinical electron beams w...
The preceding DIN 6800-2 (1997) protocol has been revised by a German task group and its latest version was published in March 2008 as the national standard dosimetry protocol DIN 6800-2 (2008 March). Since then, in Germany the determination of absorbed dose to water for high-energy photon and electron beams has to be performed according to this new German dosimetry protocol. The IAEA Code of P...
Dosimetry protocols for external beam radiotherapy currently in use, such as the IAEA TRS-398 and AAPM TG-51, were written for conventional linear accelerators. In these accelerators, a flattening filter is used to produce a beam which is uniform at water depths where the ionization chamber is used to measure the absorbed dose. Recently, clinical linacs have been implemented without the flatten...
The potential health impacts of chronic exposures to uranium, as they occur in occupational settings, are not well characterized. Most epidemiological studies have been limited by small sample sizes, and a lack of harmonization of methods used to quantify radiation doses resulting from uranium exposure. Experimental studies have shown that uranium has biological effects, but their implications ...
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