A new aluminum filter, 5.8 mm thick at the center, was designed. The effective energy, exposure dose, absorbed dose, and noise were measured by using low-dose technique, very low-dose technique with a conventional filter, and very low-dose technique with a new filter on a chest phantom. Accuracy of very low-dose computed tomography (CT) with a new filter was compared against standard helical CT in 40 patients and against chest radiography in 35 patients. Effective energies were 42.6 keV and 51.6 keV at a conventional filter and the new filter, respectively. Compared against 20mA with a conventional filter, exposure dose was reduced by 17%, and absorbed dose was equivalent, at 30 mA with the new filter. Noise was improved by 9%. Compared with standard helical CT, the sensitivity, specificity, and accuracy of very-low-dose helical CT were 100%, 88%, and 95%, respectively. Very-low-dose helical CT was found to be significantly superior to chest radiography in the detection of lung cancers. Using a smaller tube current and an appropriate filter allows a further reduction in radiation dose in helical CT for lung cancer screening.
Our current study disclosed that RLP-C levels are strongly associated with coronary artery disease, especially in patients with normal total cholesterol levels. Moreover, RLP-C/HDL-C ratio may be even more significantly associated with the presence of coronary artery stenosis in normocholesterolemic patients.
Objective Wedesigned the present study to evaluate the association of various lipid and fibrinolytic components with coronary artery stenosis with respect to the triglyceride (TG) level.Methods Levels of TG, remnant-like particle cholesterol (RLP-C), total cholesterol, high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), lipoprotein-(a), uric acid, blood glucose, tissue plasminogen activator (t-PA), t-PA inhibitor type 1, antithrombin III, and protein C were measured in 208 patients who underwent diagnostic coronary angiograms.Patients Of these 208 patients, 59 were hypertriglyceridemic (150 mg/dl or higher) and 149 were normotriglyceridemic.Results Both LDL-Cand HDL-Cshowed significant differences between patients with and those without coronary artery stenosis in both hypertriglyceridemic and normotriglyceridemic patient subgroups. However, RLP-C showeda significant difference in the normotriglyceridemic patient subgroup (p=0.012) but not in the hypertriglyceridemic patient subgroup (p=0.736). Conclusion Our current retrospective study disclosed that RLP-Clevels are closely associated with coronary artery stenosis in patients with normal TGlevels.
We are investigating three-dimensional converging stereotactic radiotherapy (3DCSRT) with suitable medium-energy x rays as treatment for small lung tumors with better dose homogeneity at the target. A computed tomography (CT) system dedicated for non-coplanar converging radiotherapy was simulated with BEAMnrc (EGS4) Monte-Carlo code for x-ray energy of 147.5, 200, 300, and 500 kilovoltage (kVp). The system was validated by comparing calculated and measured percentage of depth dose in a water phantom for the energy of 120 and 147.5 kVp. A thorax phantom and CT data from lung tumors (<20 cm3) were used to compare dose homogeneities of kVp energies with MV energies of 4, 6, and 10 MV. Three non-coplanar arcs (0 degrees and +/-25 degrees ) around the center of the target were employed. The Monte Carlo dose data format was converted to the XiO RTP format to compare dose homogeneity, differential, and integral dose volume histograms of kVp and MV energies. In terms of dose homogeneity and DVHs, dose distributions at the target of all kVp energies with the thorax phantom were better than MV energies, with mean dose absorption at the ribs (human data) of 100%, 85%, 50%, 30% for 147.5, 200, 300, and 500 kVp, respectively. Considering dose distributions and reduction of the enhanced dose absorption at the ribs, a minimum of 500 kVp is suitable for the lung kVp 3DCSRT system.
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