نتایج جستجو برای: ionization radiation

تعداد نتایج: 273398  

Journal: :iranian journal of radiation research 0
j. zhu key laboratory of heavy ion radiation biology and medicine of chinese academy of sciences & gansu key laboratory of space radiobiology, institute of modern physics, chinese academy of sciences, lanzhou, 730000, p. r. of china z. ren key laboratory of heavy ion radiation biology and medicine of chinese academy of sciences & gansu key laboratory of space radiobiology, institute of modern physics, chinese academy of sciences, lanzhou, 730000, p. r. of china y. chen key laboratory of heavy ion radiation biology and medicine of chinese academy of sciences & gansu key laboratory of space radiobiology, institute of modern physics, chinese academy of sciences, lanzhou, 730000, p. r. of china h. ojha department of radiation genetics and epigenetics, institute of nuclear medicine and allied sciences, delhi 110054, india

the radiobiological effects of high atomic number and energy (hze particles) ion beams are of interest for radioprotection in space and tumor radiotherapy. space radiation mainly consists of heavy charged particles from protons to iron ions, which is distinct from common terrestrial forms of radiation. hze particles pose a significant cancer risk to astronauts on prolonged space missions. with ...

Journal: :iranian journal of medical physics 0
mohammad-hossein zare department of medical physics, faculty of medicine, mashhad university of medical sciences, mashhad, iran hamid-reza sadoughi department of medical physics, faculty of medicine, mashhad university of medical sciences, mashhad, iran

introduction using ionization radiation for diagnostic and treatment fields has increased worldwide dramatically. this issue causes an increase in the absorbed and collective doses in society noticeably. with regard to two main principles in radiation protection, i.e., justification and optimization, it is necessary to have imaging process with minimum dose to patients and personnel. for achiev...

Journal: :Physics in medicine and biology 2009
James L Bedford Young K Lee Philip Wai Christopher P South Alan P Warrington

The Delta(4) diode array phantom (Scandidos, Uppsala, Sweden) was evaluated for verification of segmental intensity-modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT) on an Elekta linear accelerator (Crawley UK). The device was tested for angular sensitivity by irradiating it from 36 different gantry angles, and the responses of the device to various step-and-shoot s...

J. Wang, M. Nie, N. Yuan, S. Zhang, Y. Fang, Z. Wang,

Background: Protection of hematopoietic system has become a primary goal in the development of novel medical countermeasures against ionization radiation and radiotherapy. This study was to explore the role of rapamycin in normal tissues against radiation. Materials and Methods: Mice were pretreated with rapamycin by i.p. every other day for five times before 5 Gy or 8.5 Gy γ-ray whole bo...

2011
H. I. Al-Mohammed

The aim of this study was to evaluate the significance of performing patient specification quality assurance for patients diagnosed with glioblastoma multiforme treated with intensity modulated radiation therapy. The study evaluated ten intensity modulated radiation therapy treatment plans using 10 MV beams, a total dose of 60 Gy (2 Gy/fraction, five fractions a week for a total of six weeks tr...

2001
R. Moshammer H. Kollmus S. Hagmann M. Schulz B. Feuerstein R. Mann A. Dorn D. Fischer A. N. Perumal C. Höhr C. D. Schröter J. R. Crespo Lopez-Urrutia H. Rottke W. Sandner R. E. Olson J. Ullrich

The interaction of both, highly charged ions and intense lasers fields, with matter or atoms attract increasing interest because of fundamental questions to be addressed and because of the long term perspectives of potential applications. Such applications cover a wide range from inertial fusion driven by heavy ion or intense laser beams to new techniques in material science and medical treatme...

Journal: :Medical physics 2012
Jonas Andersson Erik Johansson Heikki Tölli

PURPOSE The performance of liquid ionization chambers, which may prove to be useful tools in the field of radiation dosimetry, is based on several chamber and liquid specific characteristics. The present work investigates the performance of the PTW microLion liquid ionization chamber with respect to recombination losses and perturbations from ambient electric fields at various dose rates in con...

Journal: :Molecules 2011
Changhyun Roh Dong-Kyung Yu Insub Kim Sung Kee Jo

Globally, there are concerns over the risks associated with radiation exposure, so it is important to understand the biological effects of radiation exposure. Driven by the need to detect the presence of radiation exposure, biomarkers to monitor potential exposure after radiological accidents can be developed and would be extremely valuable for biological response. In this study, the behavior o...

Journal: :Medical physics 2004
Hugo Bouchard Jan Seuntjens

The present paper addresses reference dose measurements using thimble ionization chambers for quality assurance in IMRT fields. In these radiation fields, detector fluence perturbation effects invalidate the application of open-field dosimetry protocol data for the derivation of absorbed dose to water from ionization chamber measurements. We define a correction factor C(Q)IMRT to correct the ab...

2007
J. E. Dyson R. J. R. Williams T. W. Hartquist

We give an overview of the literature on ionization front structure and propagation and comment on recombination front structures. We discuss the formation of cometary tails by photoionization of globules and note the importance of including the diffuse component of the ionizing radiation field. We finally briefly comment on the formation of small scale structures in H II regions.

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