[The Relation between the Height of Radiographic Table and Workloads of Radiologic Technologist in General X-ray Examinations].

Workloads of radiological technologists under different conditions of heights of radiographic table and/or X-ray tube assembly were calculated using a software for preventing musculoskeletal complaint to investigate optimal working environment for general X-ray examinations. In the patient positioning, compressive force of lumbar disc decreased at higher radiographic table within the range of 45-90 cm. On the other hand, workload of the shoulder joint increased with increase in the height of radiographic table. Load of the shoulder joint similarly increased as the height of the X-ray tube assembly increased. Compressive force of lumbar disc reduced by approximately 10-30% as the height ratio of the radiographic table to body height increased by approximately 40%, compared to the lowest table of 45 cm. Muscle load of a 50-years-old woman was approximately double compared to a 30-year-old man, even in the same workload. It is important to keep suitable height of radiographic table for reduction of the workloads of lumbar rather than shoulder joint, because floating-type radiographic table is generally used.

Impact of hybrid iterative reconstruction on unenhanced liver CT.

OBJECTIVE: To clarify the impact of hybrid iterative reconstruction (HIR) and filtered back projection (FBP) on unenhanced liver CT. METHODS: 30 patients with hepatocellular carcinoma (HCC) underwent unenhanced CT. The images were reconstructed with FBP and weak (Level 1), mild (Level 4) and strong (Level 7) levels of HIR (iDose4; Philips Medical Systems, Cleveland, OH). Quantitatively, attenuations of the HCC (with the largest lesion in each case), hepatic parenchyma (the average of four segments) and image noise (standard deviation of the attenuations in hepatic parenchyma) were compared between the four kinds of reconstruction using the two-tailed paired t-test. Qualitatively, liver lesion conspicuity and characterization were also compared using the Wilcoxon signed-rank test. RESULTS: Attenuation of the liver lesion with the strong level of HIR was significantly higher than that with FBP (p = 0.0005). Attenuations of hepatic parenchyma with all three HIR levels were significantly lower than that with FBP (p ≤ 0.0002 in all comparisons). Image noise with each of the three HIR levels was significantly smaller than that with FBP (p < 0.0001 in any comparison). There was no significant difference in lesion conspicuity and characterization between FBP and each HIR level (p ≥ 0.0819 in all comparisons). CONCLUSION: Although attenuations of the liver lesion and hepatic parenchyma were significantly different between HIR and FBP, HIR had no significant effect on lesion conspicuity and characterization. Advances in knowledge: Attenuations of liver lesions and hepatic parenchyma differ significantly between HIR and FBP images.

Histogram analysis with automated extraction of brain-tissue region from whole-brain CT images.

To determine whether an automated extraction of the brain-tissue region from CT images is useful for the histogram analysis of the brain-tissue region was studied. We used the CT images of 11 patients. We developed an automatic brain-tissue extraction algorithm. We evaluated the similarity index of this automated extraction method relative to manual extraction, and we compared the mean CT number of all extracted pixels and the kurtosis and skewness of the distribution of CT numbers of all extracted pixels from the automated and manual extractions. The similarity index was 0.93. The mean CT number and the kurtosis and skewness from the automated extraction were 35.0 Hounsfield units, 0.63, and 0.51, respectively, and were equivalent to those from the manual extraction (35.4 Hounsfield units, 0.59, and 0.46, respectively). The automated extraction of the brain-tissue region from whole-brain CT images was useful for histogram analysis of the brain-tissue region.

[Optimization of the chest exposure condition with a contrast-detail phantom: evaluation of the flat-panel versus computed radiography systems].

In this study, we evaluated the performance of a digital chest imaging system using a contrast-detail (C-D) phantom. In the initial step, 76 sample images of the C-D phantom were produced by changing the doses from 0.5, 0.75, 1.0, 1.25, 1.5, to 2.0 times the dose for a screen-film (S/F) system. The sample images were analyzed by five radiological technologists and two medical physicists, and the image quality figure (IQF) was determined. The quality of each image was examined, and appropriate doses were determined from the calculated IQF to obtain the same image quality for other digital chest imaging systems. The method of determining IQF from C-D phantom analysis was very useful for comparing image quality and determining radiographic techniques.