[Design of X-ray Images Based on Quantitative Analysis: Predictive Model of Image Quality and Physical Quantity Factors by Multiple Regression Equation of Visual Evaluation (Scheffé's) and Physical Quantities (Dose and Noise)].

PURPOSE: The Scheffé's method obtains the difference between pair comparisons with that of the interval scale and can judge the superiority or inferiority of the sample to be compared with no restriction in the observation image by the statistical significant difference. However, the Scheffé's method cannot be judged as a single image quality indicator. Therefore, I examined a method that can evaluate the association of average degree of preference of Scheffé's method and the physical quantities that make up the image. METHODS: This study focuses on the fact that the average degree of preference of the Scheffé's method is quantitative data on the interval scale and that multiple regression analysis is possible. In the multiple regression analysis, the average degree of preference by imaging simulated pulmonary adenocarcinoma with different exposure doses was used as the objective variable and the exposure doses and noise (standard deviation [SD]) were used as the explanatory variables. The Scheffé's method used the Nakaya's modified method. RESULTS: In the multiple regression analysis, SD was P=0.027. By substituting the threshold value of the intersection of the exposure doses and SD into the multiple regression equation (predictive model), the average degree of preference (Y) was calculated. Y(Scheffé;Gy,SD) was -0.147, which was about 1/2 of exposure doses (-0.150). CONCLUSION: The multiple regression analysis of Scheffé's (average degree of preference) and physical quantity factors (exposure doses and noise) has made it possible to design images that can reduce exposure doses while maintaining adequate image quality.

[Evaluation study of abnormal detectability with Thurstone and Scheffé (Nakaya) of paired comparison method using chest phantom].

Monitors are increasingly being used as diagnostic imaging devices. In this study, using an all-purpose liquid-crystal display (LCD), the rate of detection of abnormalities was investigated using Thurstone's and Scheffé's (Nakaya) paired comparison methods. A chest phantom was prepared as a test sample with acryl and aluminum plates and intensities suggesting small adenocarcinomas. For the acquisition conditions for computed radiography, after setting the baseline at a dose at which the film density of the standard screen-film system at the same as those for the lung, costal bone, and mediastinum, 5 steps of 2-fold serial doses were then set: 1/4, 1/2, 1, 2, and 4. The test sample was observed by 10 students. On the Thurstone scale, detectability decreased with a decrease in the dose in the lung, costal bone, and mediastinum. When the significance of differences between the values at adjacent doses was investigated using the yardstick method, using Scheffé's method revealed a significant difference between the 4- and 2-fold doses and between the 1/2 and 1/4 doses in the pulmonary region. A significant difference was also noted between the baseline and 1/2 doses in the mediastinum. Changes in the order of the scale values may not occur in the intervals in which significant differences were noted using Scheffé's methods.

[Comparison of detectability of liquid crystal displays (LCDs) and film using phantoms of small adenocarcinomas as abnormalities].

Following the trend of the digitalization of the modalities used for diagnostic imaging, the devices for such imaging have increasingly included monitors. The present study was undertaken to evaluate the usefulness of soft-copy (liquid crystal display; LCD) images of phantoms of small adenocarcinomas using receiver operating characteristic (ROC) analysis of two different display systems: LCD and hard copy (film). A two-tailed paired t-test and the jackknife method (parametric methods) were performed, and no significant differences were found in the area under the ROC curve (AUC) for the pulmonary fields, lungs, ribs, or mediastinum between the film and LCD display systems, and the detectability did not differ between the film and LCD monitors. A Mann-Whitney U test, which is a non-parametric method that applies to the analysis of a small sample, also showed no significant differences in the AUC. The results of this study suggest that LCDs can replace hard-copy film as a display system if the signals.

Involvement of the tubulin tyrosine ligase-like family member 4 polyglutamylase in PELP1 polyglutamylation and chromatin remodeling in pancreatic cancer cells.

Polyglutamylation is a new class of posttranslational modification in which glutamate side chains are formed in proteins, although its biological significance is not well known. Through our genome-wide gene expression profile analyses of pancreatic ductal adenocarcinoma (PDAC) cells, we identified the overexpression of tubulin tyrosine ligase-like family member 4 (TTLL4) in PDAC cells. Subsequent reverse transcription-PCR and Northern blot analyses confirmed its upregulation in several PDACs. TTLL4 belongs to the TTLL family which was reported to have polyglutamylase activity. Knockdown of TTLL4 by short hairpin RNA in PDAC cells attenuated the growth of PDAC cells and exogenous introduction of TTLL4 enhanced cell growth. We also found that TTLL4 expression was correlated with polyglutamylation levels of a glutamate stretch region of the proline, glutamate, and leucine-rich protein 1 (PELP1) that was shown to interact with various proteins such as histone H3, and was involved in several signaling pathways through its function as a scaffold protein. PELP1 polyglutamylation could influence its interaction with histone H3 and affect histone H3 acetylation. We also identified the interaction of PELP1 with LAS1L and SENP3, components of the MLL1-WDR5 supercomplex involving chromatin remodeling. Our findings imply that TTLL4 could play important roles in pancreatic carcinogenesis through its polyglutamylase activity and subsequent coordination of chromatin remodeling, and might be a good molecular candidate for the development of new therapeutic strategies for pancreatic cancer.

[Estimation of appropriate dose for computed radiography by the threshold value of the image quality figure].

We estimated the optimum dose for imaging with a computed radiography (CR) system at two different pixel sizes based on the area under curve (AUC) in receiver operating characteristic (ROC) analysis and image quality figure (IQF). Samples for ROC analysis were prepared as follows. Acryl beads, 2.0 mm in diameter, were placed on a 50.0 mm tough water phantom that was fitted with a 20.0 mm Al filter (SID 200 cm, tube voltage 80 kV). The dose level at which the film density of the screen-film system (SRO250/SRG) was 1.0+/-0.05 served as the reference dose (0.69microC/kg). Five samples were prepared by multiplying the reference dose by 1/4, 1/2, 1, 2, and 4. The samples for image quality evaluation on the basis of IQF were prepared under identical conditions. A contrast-detail (C-D) phantom was placed on a 50.0 mm tough water phantom and images were taken. The contrast threshold of these samples was determined by 10 film readers, the same as those for the ROC analysis. When the significance of differences in the AUC was tested by the paired t-test (two-sided) and the Jackknife method, significant differences were noted between the reference dose and the 1/4 or 4-times dose at the standard pixel size (0.175 mm) and smaller pixel size (0.0875 mm) size, while no significant difference was noted between the reference dose and the 1/2 or 2-times dose. In terms of IQF, no significant difference was noted between standard and smaller pixel sizes (paired t-test). The IQF data indicate that the dose level for imaging with CR can be reduced by about 30% from the reference dose.

Cell cycle phenotype-based optimization of G2-abrogating peptides yields CBP501 with a unique mechanism of action at the G2 checkpoint.

Cell cycle G(2) checkpoint abrogation is an attractive strategy for sensitizing cancer cells to DNA-damaging anticancer agent without increasing adverse effects on normal cells. However, there is no single proven molecular target for this therapeutic approach. High-throughput screening for molecules inhibiting CHK1, a kinase that is essential for the G(2) checkpoint, has not yet yielded therapeutic G(2) checkpoint inhibitors, and the tumor suppressor phenotypes of ATM and CHK2 suggest they may not be ideal targets. Here, we optimized two G(2) checkpoint-abrogating peptides, TAT-S216 and TAT-S216A, based on their ability to reduce G(2) phase accumulation of DNA-damaged cells without affecting M phase accumulation of cells treated with a microtubule-disrupting compound. This approach yielded a peptide CBP501, which has a unique, focused activity against molecules that phosphorylate Ser(216) of CDC25C, including MAPKAP-K2, C-Tak1, and CHK1. CBP501 is >100-fold more potent than TAT-S216A and retains its selectivity for cancer cells. CBP501 is unusually stable, enters cells rapidly, and increases the cytotoxicity of DNA-damaging anticancer drugs against cancer cells without increasing adverse effects. These findings highlight the potency of CBP501 as a G(2)-abrogating drug candidate. This report also shows the usefulness of the cell cycle phenotype-based protocol for identifying G(2) checkpoint-abrogating compounds as well as the potential of peptide-based compounds as focused multitarget inhibitors.

[Sensitometry of Mammographic Screen-film System Using Bootstrap Aluminum Step-Wedge.].

Recently, a few types of step-wedges for bootstrap sensitometry with a mammographic screen-film system have been proposed. In this study, the bootstrap sensitometry with the mammographic screen-film system was studied for two types of aluminum step-wedges. Characteristic X-ray energy curves were determined using mammographic and general radiographic aluminum step-wedges devised to prevent scattered X-rays generated from one step penetrating into the region of another one, and dependence of the characteristic curves on the wedges was also discussed. No difference was found in the characteristic curves due to the difference in the step-wedges for mammography and general radiography although there was a slight difference in shape at the shoulder portion for the two types of step-wedges. Therefore, it was concluded that aluminum step-wedges for mammography and general radiography could be employed in bootstrap sensitometry with the mammographic screen-film system.

[Fundamental study on stability of dry-processing imager system DRYPRO 722/SD-P].

Dry-processing leaser imager systems have become popular due to the advantages such as the elimination of the cost and labor associated with the wet chemical processing. In this paper, the stability of a dry-processing imager system Drypro 722/SD-P was studied using SMPTE pattern films processed by a dry-processing imager Drypro 722 and a wet-processing imager Li-8/SRX-502 at three different times of the day over a period of five consecutive working days. The dry system is inferior to the wet system on the stability and the spatial uniformity, so that the problems assess the necessity of QC for Drypro 722 Laser Imagers. The instability of the post-processing dry and wet films is also studied. The dry film is very instable compared with the wet film. Accordingly the wet film must be handled with the care.

Nonlinear Effect on Noise Power Spectrum for Quantum Mottle in Radiographs.

Rossmann's formula on the power spectrum of quantum noise in a radiograph is based on an assumption that the relation between the spatial fluctuations of optical density and the relative spatial fluctuations of light energy irradiated from the intensifying screen due to absorbed x-ray quanta is linear. The reasonability of the assumption is not theoretically obvious because the relative spatial fluctuation of light energy increases as the number of absorbed x-ray quanta decreases. Based on the shot-noise theory, the power spectrum of quantum noise is calculated taking account of the second order of the spatial fluctuation of light energy and the spectrum is expressed as a function of the gradient, the modulation transfer function of the screen-film system, and the average number of absorbed x-ray quanta. The term caused by the nonlinearity between the spatial fluctuations of optical density and light energy per unit area for the noise power spectrum is also estimated using the m-hits model for the emulsion and it is found that the effect due to the nonlinearity is little in practice.