نتایج جستجو برای: variation in lung density

تعداد نتایج: 17112898  

Background: The purpose of this study is to fabricate inexpensive in-house low cost homogeneous and heterogeneous human equivalent thorax phantom and assess the dose accuracy of the Treatment Planning Systems (TPS) calculated values for different lung treatment dosimetery. It is compared with Thermoluminescent Dosimeter (TLD) measurement. Materials and Methods: Homogeneous and heterogeneous tho...

Journal: :Chest 1992
H Guenard M H Diallo F Laurent J Vergeret

Mean lung density (dm) and radiologic (VLx) lung volume can be calculated using CT scan data. As many emphysematous patients are overdistended, the analysis of dm alone could be meaningless. However, lung mass (m) can be calculated as the product of dm and VLx. Twenty-four patients suspected of mild or severe emphysema as judged by roentgenographic and physiologic examinations as well as 16 hea...

ژورنال: فیزیک زمین و فضا 2018

The time lapse gravity method is a widely used technique to monitor the subsurface density changes in time and space. In hydrocarbon reservoirs, the density variations are due to different factors, such as: substitution of fluids with high density contrast, water influx, gas injection, and the variation in reservoir geomechanical behavior. Considering the monitoring of saturation changes in the...

Introduction: In radiotherapy treatment planning system (TPS), basic input is the data from computed tomography (CT) scan, which takes into account the effect of inhomogeneities in dose calculations. Measurement of CT numbers may be affected by scanner-specific parameters. Therefore, it is important to verify the effect of different CT scanning protocols on Hounsfield unit (HU) and its impact o...

Journal: :Journal of radiation research 2009
Shinichiro Mori Hsiao-Ming Lu John A Wolfgang Noah C Choi George T Y Chen

Intrafractional motion and interfractional changes affect the accuracy of the delivered dose in radiotherapy, particularly in charged-particle radiotherapy. Most recent studies are focused on intrafractional motion (respiratory motion). Here, we report a quantitative simulation analysis of the effects of interfractional changes on water-equivalent pathlength (WEL) in charged-particle lung thera...

2016
J. B. Borges L. Porra M. Pellegrini A. Tannoia S. Derosa A. Larsson S. Bayat G. Perchiazzi G. Hedenstierna

BACKGROUND It is not well known what is the main mechanism causing lung heterogeneity in healthy lungs under mechanical ventilation. We aimed to investigate the mechanisms causing heterogeneity of regional ventilation and parenchymal densities in healthy lungs under anesthesia and mechanical ventilation. METHODS In a small animal model, synchrotron imaging was used to measure lung aeration an...

2017
Qingle Wang Zhiyong Zhang Fei Shan Yuxin Shi Wei Xing Liangrong Shi Xingwei Zhang

BACKGROUND This study was conducted to assess intra-observer and inter-observer agreements for the measurement of dual-input whole tumor computed tomography perfusion (DCTP) in patients with lung cancer. METHODS A total of 88 patients who had undergone DCTP, which had proved a diagnosis of primary lung cancer, were divided into two groups: (i) nodules (diameter ≤3 cm) and masses (diameter >3 ...

NAD(P)H: quinone oxidoreductase 1 (NQO1) is an endogenous cellular defence mechanism against several carcinogenic quinones derived from cigarette smoke. NQO1 C609T polymorphism is a strong determinant of NQO1 structure and function. The people with mutant allele for this polymorphism has significantly reduced NQO1 activity. In this study, we tried to evaluate the risk of lung cancer as...

Journal: :مهندسی زراعی 0

in order to study the effects of sugar cane harvest machinery traffic on bulk density and cone index variation, a survey was conducted in 10 farms of deabel khozaiee sugarcane agro-industrial company, ahvaz, in 2006. in this experiment, two types of harvesters including wheel half track and tire wheels with 14 tons of weight, versus two types of tractor and basket transporters, with 10 and 18 t...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه رازی - دانشکده علوم 1391

1. to determine whether difference in birth body mass influenced growth performance in pipistrellus kuhlii we studied a total of 12 captive-born neonates. bats were assigned to two body mass groups: light birth body mass (lbw: 0.89 ± 0.05, n=8) and heavy birth body mass (hbw: 1.35 ± 0.08, n=4). heavier body mass at birth was associated with rapid postnatal growth (body mass and forearm length) ...

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