نتایج جستجو برای: Phantom scatter factor

تعداد نتایج: 870740  

Ahmad Mostaar, Ghazaleh Sadrieh Khajoo Mahdi Salehi Barough Mohammad Ali Ostadrahimi

Introduction: In the last few decades, a lot of monte carlo codes have been introduced for medical applications. this is important because through simulation, we are fully independent of the spectral scattering factor that we are not able measure in real terms. The effect of the radiation energy, the dimension of the radiation field, the sensitive volume of the ion chamber on t...

Journal: :iranian journal of nuclear medicine 0
mohsen hajizadeh saffar medical physics research center, school of medicine, mashhad university of medical sciences, mashhad, iran shabnam oloomi medical physics department, mashhad university of medical science, mashhad, iran peter knoll department of nuclear medicine, wilhelminenspital, vienna, austria hadi taleshi department of medical physics, faculty of medical sciences, tarbiat modares university, tehran, iran

introduction: scattered photon is one of the main defects that degrade the quality and quantitative accuracy of nuclear medicine images. accurate estimation of scatter in projection data of spect is computationally extremely demanding for activity distribution in uniform and non-uniform dense media. methods: the objective of this paper is to develop and validate a scatter correction technique t...

2017
Mohammad Javad Tahmasebi Birgani Nahid Chegeni Mohammad Ali Behrooz Marziyeh Bagheri Amir Danyaei Azin Shamsi

INTRODUCTION One of the important input factors in the commissioning of the radiotherapy treatment planning systems is the phantom scatter factor (Sp) which requires the same collimator opening for all radiation fields. In this study, we have proposed an analytical method to overcome this issue. METHODS The measurements were performed using Siemens Primus Plus with photon energy 6 MV for fiel...

Journal: :iranian journal of nuclear medicine 2013
mohsen hajizadeh saffar shabnam oloomi peter knoll hadi taleshi

introduction: scattered photon is one of the main defects that degrade the quality and quantitative accuracy of nuclear medicine images. accurate estimation of scatter in projection data of spect is computationally extremely demanding for activity distribution in uniform and non-uniform dense media. methods: the objective of this paper is to develop and validate a scatter correction technique ...

Hadi Taleshi Mohsen Saffar Peter Knoll, Shabnam Oloomi

Introduction: Scattered photon is one of the main defects that degrade the quality and quantitative accuracy of nuclear medicine images. Accurate estimation of scatter in projection data of SPECT is computationally extremely demanding for activity distribution in uniform and non-uniform dense media. Methods: The objective of this paper is to develop and validate a scatter correction technique ...

Journal: :Medical physics 1997
S A Johnsson C P Ceberg

The characterization of the incident photon beam is usually divided into its dependence on collimator setting (head-scatter factor) and off-axis position (primary off-axis ratio). These parameters are normally measured "in air" with a build-up cap thick enough to generate full dose build-up at the depth of dose maximum. In order to prevent any influence from contaminating electrons, it has been...

Journal: :Japanese Journal of Radiological Technology 2012

2011
Angelica Svalkvist Gustaf Ullman Markus Håkansson David Dance Michael Sandborg Gudrun Alm Carlsson Magnus Båth

The primary aim of the present work was to analyze the effects of varying scatter-to-primary ratios on the appearance of simulated nodules in chest tomosynthesis section images. Monte Carlo simulations of the chest tomosynthesis system GE Definium 8000 VolumeRAD (GE Healthcare, Chalfont St. Giles, UK) were used to investigate the variation of scatter-to-primary ratios between different angular ...

Journal: :iranian journal of medical physics 0
afshin akbarzadeh ph.d. student, department of medical physics and biomedical engineering and research center for science and technology in medicine, tehran university of medical sciences, tehran, iran mohammad rreza ay assistant professor in biomedical engineering, biomedical systems & medical physics dept., tehran university of medical sciences & research center for science and technology in medicine, tehran, iran. hossein ghadiri ph.d. student, department of medical physics and biomedical engineering and research center for science and technology in medicine, tehran university of medical sciences, tehran, iran saied sarkar associate professor in biomedical engineering, biomedical systems & medical physics dept., tehran university of medical sciences & research center for science and technology in medicine, tehran, iran.

introduction: one of the most important parameters in x-ray ct imaging is the noise induced by detected scattered radiation. the detected scattered radiation is completely dependent on the scanner geometry as well as size, shape and material of the scanned object. the magnitude and spatial distribution of the scattered radiation in x-ray ct should be quantified for development of robust scatter...

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