ABSTRACT
OBJECTIVE: Subject contrast of pulmonary tissues was investigated for five X-ray beams (70 kV without filter, 90 kV with 0.15 mm Cu filter, 90 kV with 0.2 mm Cu filter, 120 kV without filter, and 120 kV with 0.2 mm Cu filter) in CsI-FPD chest radiography using two types of model phantoms by Monte Carlo simulation. METHODS: A total of 72 million photons were entered to the model lung phantom (width, 300 mm; length, 300 mm; thickness, 200 mm; air space, 120 mm) and model mediastinum phantom (width, 300 mm; length, 300 mm; thickness, 200 mm; air space, 40 mm). Individual primary and secondary photon's process (absorption, scattering, and penetration) in the phantom and CsI-detector was recorded by Monte Carlo simulation. Subject contrast was calculated by entered and absorbed photon's number in the CsI-detector. RESULTS: Subject contrast pulmonary tissues were high to low energy X-ray beam; however, the ones of soft tissue and soft tissue overlaying bone had few differences for beam quality except 70 kV without filter. Moreover, the subject contrast by absorbed photons was higher compared to the one by entered photons in CsI. CONCLUSION: It was shown that the subject contrast study by Monte Carlo calculation can be replaced by the way of physical chest phantom, and that the subject contrast by absorbed photons and by injected photons in CsI was different. Furthermore, be verified that the subject contrast of soft tissue and soft tissue overlaying bone differs hardly.
Subject(s)
Lung , Photons , Monte Carlo Method , Radiography , Computer Simulation , X-Rays , Lung/diagnostic imaging , Phantoms, ImagingABSTRACT
Objective To investigate the effects of dexamethasone on prevention of apoptosis in pulmonary tissues of rats after simulated weightlessness. Methods Tail suspension was used to simulate weightlessness. Thirty Sprague-Dawley male rats were divided randomly into 3 groups: control group, tail suspension for 7 days group, and dexamethasone treatment after suspension group. TUNEL technique was used to detect cell apoptosis in pulmonary tissues. Results The rate of apoptotic cells in the lung of rats suspended for 7 day was higher than that of control group(P
ABSTRACT
To investigate the changes of cell apoptosis genes in pulmonary tissue of tail suspended rats during simulated weightlessness, 40 Spragno Dawley male rats were divided into 4 groups: suspended for 7d,control of 7d, suspended for 21d, and control of 21d.Tail suspension(-30?) was used as weightlessness simulation.The condition of bcl 2/bax in pulmonary tissues was detected by in situ hybridization. The results showed that the level of bcl 2 mRNA in pulmonary tissue of 7d tail suspended rats decreased significantly( P 0 05). The results also showed that the level of bax mRNA in pulmonary tissue of 7d tail suspended rats increased significantly( P 0 05).It can be concluded that there are certain changes of cell apoptosis genes in pulmonary tissue of 7d tail suspended rats during simulated weightlessness.
ABSTRACT
To investigate the changes of vascular endothelial growth factor mRNA (VEGFmRNA) in pulmonary tissues of tail suspended rats during simulated weightlessness,the experiments were conducted on 40 Spragno Dawley male rats,divided into 4 groups:suspended for 7d,control of 7d and suspended for 21d,control of 21d.Tail suspension(-30?) was used as weightlessness simulation.The condition of VEGFmRNA in pulmonary tissues was examined by hybridization in situ. The results showed that the level of VEGFmRNA in pulmonary tissues of 7d tail suspended rats increased significantly( P
