[Usefulness of Combining Post-processing Scatter Correction and an Anti-scatter Grid in Chest Standing Radiography].

PURPOSE: The aim of this study was to evaluate the usefulness of combining post-processing scatter correction (IG) and an anti-scatter grid (RG) in chest radiography. METHOD: To determine the combination protocol (Hyb) that was closed to RG 12:1 (RG12), we measured the content rate of scattered radiation for each combination (RG12, IG12, RG3-12+IG3-12). Task-based modulation transfer function (MTF_Task) and SDNR were evaluated using RG12, IG12, and Hyb. Additionally, seven radiologists performed visual evaluation by using chest phantom. RESULT: The protocol of Hyb was RG8+IG3. In SDNR, Hyb (RG8+IG3) was equal to or higher than RG12, and MTF_Task was equal in all grid systems. Hyb (RG8+IG3) was significantly superior to RG12 in visual evaluation. CONCLUSION: The combining post-processing scatter correction should be useful for improving inspection throughput and reducing the risk of grid's damage.

[Examination of the Maximum Brightness of the Monitor Suitable for Radiological Technologists' Interpretation Assistance and Image Inspection].

The purpose of this study is to examine the maximum brightness of the monitor, which is suitable for radiological technologists' (hereinafter referred to as technicians) interpretation assistance and image inspection. The signal detection ability was evaluated by receiver operating characteristic (ROC) analysis using a chest X-ray image with a simulated nodule. In order to examine the ease of observation and the effect on the subjective evaluation by changing the maximum brightness, evaluation was performed by the normalized ranking method using chest X-ray images. ROC experiments were performed using images with and without simulated nodules in the chest phantom. There was no significant difference in detectability by changing the maximum brightness (p>0.05), but the average area under the curve (AUC) was higher at 350 cd/m2 than at 100 cd/m2 and 170 cd/m2. A normalized ranking method was performed focusing on simulated nodules on chest X-ray images. In the least significant difference (l.s.d.) method, there was a significant difference between the maximum luminance, and the higher the maximum luminance, the better the evaluation. From these results, the change in the maximum brightness did not significantly affect the signal detection ability of the technician's chest X-ray image, but the higher the maximum brightness, the easier it was to observe and the higher the subjective evaluation. It has been reported that the higher the maximum brightness, the shorter the signal recognition time, and a monitor with a high maximum brightness may lead to more efficient image inspection by a technician. From the results of this study, it is considered appropriate to use a medical liquid crystal display (LCD) monitor with a maximum brightness of 350 cd/m2 for the technician's interpretation assistance and image inspection.

Correction to: A simple method for the automatic classification of body parts and detection of implanted metal using postmortem computed tomography scout view.

In the original publication of the article, the authors affiliations were incorrectly published. The corrected affiliations are given in this correction.

A simple method for the automatic classification of body parts and detection of implanted metal using postmortem computed tomography scout view.

Information on medical devices embedded in the body is important in the identification of an unidentified body. Computed tomography (CT) is a powerful imaging modality; however, metallic artifacts deteriorate the image quality because of the reconstruction method. On the contrary, CT scout view is less affected by metallic artifacts compared to CT. It is a simple method to classify the body into three rough parts for postmortem CT (PMCT) scout view, and an algorithm used to detect the location of the implanted metal has been developed for personal identification in forensic pathology. Of the test images, 97% were correctly classified into the three body parts. The true-positive rate for detection of the implanted metal in the scout view was 96.5%. Therefore, our simple methods are applicable in PMCT scout views and would be particularly useful for forensic pathology.

Helical Assemblies of One-Dimensional Supramolecular Polymers Composed of Helical Macromolecules: Generation of Circularly Polarized Light Using an Infinitesimal Chiral Source.

We report the synthesis of one-dimensional supramolecular polymers composed of one-handed helical macromolecules bearing fluorescent pendant groups and the generation of circularly polarized light on the basis of hierarchical chiral amplification starting from a tiny amount of chiral substituent. Copolymerization of benzo[1,2-b:4,5-b']dithiophene-appended achiral/chiral isocyanides (99:1, mol/mol) with a solid-state photoluminescence feature afforded submicrometer supramolecular fibers, in which almost perfect single-handed helical polyisocyanides were noncovalently connected end to end. The resulting helical supramolecular polymers were further helically assembled to form a cholesteric liquid crystal film with an intense circularly polarized luminescence (CPL) signal. Surprisingly, the supramolecular system containing only 0.01 mol % of the chiral monomer unit also emitted the observable circularly polarized light owing to multiple chiral amplification from an infinitesimal point chirality to helical chirality and then to supramolecular chirality. Furthermore, chiral information was efficiently transferred from the helically assembled supramolecular system containing 1 mol % of the chiral unit to achiral dye molecules blended in the film, allowing full-color tunable induced CPL with luminescence dissymmetry factors greater than 1.0 × 10-2. This unprecedentedly strong chiral amplification enables the creation of helical supramolecular polymers and chirally assembled systems with various chiral functions based solely on an infinitesimal chiral source.

Optically active triptycenes containing hexa-peri-hexabenzocoronene units.

A pair of novel optically active triptycene-based molecules ((R,R)-1 and (S,S)-1) containing two hexabenzocoronene moieties were synthesized and their optical and chiroptical properties were investigated. Optically active 1 emitted preferred-handed circularly polarized light upon UV irradiation, with the luminescence dissymmetry factors found to be approximately 1.0 × 10-3. Based on a comparative study using the analogous triptycene derivative with two hexaphenylbenzene units (2), which was the key precursor of 1, the ladder-type rigid structure with an asymmetrically bent geometry was important for optically active 1 to exhibit circularly polarized luminescence (CPL). We also showed that rac-1 undergoes conglomerate crystallization, which allowed CPL to be produced by a random selection of crystals prepared from rac-1.

One-Step Synthesis of One-Dimensional Supramolecular Assemblies Composed of Helical Macromolecular Building Blocks.

Living systems achieve sophisticated functions using supramolecular protein assemblies, in which the protein building blocks possess a specific secondary structure and are noncovalently arranged in a preprogrammed manner. Herein, we demonstrate the one-step synthesis of one-dimensional macromolecular assemblies by simply mixing a glycine-based isocyanide with a nickel catalyst, in which helical constituent polymers are linked end-to-end through multiple hydrogen bonds. The applicable scope of this approach is not confined to a particular monomer bearing a specially designed pendant, but covers a wide range of glycine-based isocyanides with or without aromatic and other functional groups. Surprisingly, copolymerization with an analogous chiral isocyanide (1 mol %) afforded an almost perfect one-handed helical supramolecular fiber owing to intramolecular/intermolecular dual chiral amplifications. The simplicity and broad applicability of this approach, which can also afford exquisite chiral amplification, enable the creation of a wide variety of functional supramolecular assemblies and provide access to new supramolecular materials.

Synthesis of a one-handed helical polythiophene: a new approach using an axially chiral bithiophene with a fixed syn-conformation.

We report an optically active polythiophene capable of forming a one-handed helically folded conformation without needing aggregate formation, poor solvent conditions, hydrogen-bonded ion-pair formation or guest addition. The target polythiophene (poly-TR) with a static axial chirality in the main chain was synthesized via Stille coupling copolymerization of a glucose-linked chiral 5,5'-dibromobithiophene with 2,5-bis(stannyl)thiophene. Poly-TR showed a characteristic circular dichroism and circularly polarized luminescence, which were completely different to those observed for an analogous polymer (poly-PhR) and the corresponding unimer/dimer model compounds. This chiroptical study, combined with the results of all-atom molecular dynamics simulations, revealed that poly-TR can fold into a left-handed helical conformation under good solvent conditions. Partial conformational regulation derived from the fixed syn-conformation of the chiral bithiophene unit was considered a key factor in producing the one-handed helical polythiophene.

Triptycene-Based Ladder Polymers with One-Handed Helical Geometry.

Here we report an efficient synthesis of optically active ladder-type molecules and polymers through intramolecular cyclization of chiral triptycenes containing bis[2-(4-alkoxyphenyl)ethynyl]phenylene units. The electrophile-induced cyclization reactions are directed away from the bridgehead carbon atoms of triptycene by steric factors, thereby producing one-handed twisted ladder units without any detectable byproducts. Moreover, the quantitative and regioselective nature of this intramolecular cyclization allowed us to synthesize optically active ladder polymers with a well-defined one-handed helical geometry in which homoconjugated dibenzo[ a, h]anthracene units are helically arranged along the main chain. This synthesis route enables the construction of a variety of nanoscale helical ladder architectures and provides an entry into new chiroptical materials.

Direct Detection of Hardly Detectable Hidden Chirality of Hydrocarbons and Deuterated Isotopomers by a Helical Polyacetylene through Chiral Amplification and Memory.

We report the first direct chirality sensing of a series of chiral hydrocarbons and isotopically chiral compounds (deuterated isotopomers), which are almost impossible to detect by conventional optical spectroscopic methods, by a stereoregular polyacetylene bearing 2,2'-biphenol-derived pendants. The polyacetylene showed a circular dichroism due to a preferred-handed helix formation in response to the hardly detectable hidden chirality of saturated tertiary or chiroptical quaternary hydrocarbons, and deuterated isotopomers. In sharp contrast to the previously reported sensory systems, the chirality detection by the polyacetylene relies on an excess one-handed helix formation induced by the chiral hydrocarbons and deuterated isotopomers via significant amplification of the chirality followed by its static memory, through which chiral information on the minute and hidden chirality can be stored as an excess of a single-handed helix memory for a long time.

Optically active distorted cyclic triptycenes: chiral stationary phases for HPLC.

A pair of optically active triptycene derivatives ((R,R)- and (S,S)-8) with a distorted cyclic structure were synthesized via an intramolecular etherification and evaluated as a novel chiral selector for high-performance liquid chromatography. The (R,R)- and (S,S)-8-based chiral stationary phases (CSPs) were found to be particularly effective in the resolution of axially chiral biaryl compounds. The importance of the distorted cyclic structure present in 8 for chiral recognition was demonstrated by comparisons with the corresponding non-cyclic model compound ((R,R)-9), which did not display enantioselectivity in the separation of the test racemates.

Circularly Polarized Luminescent Triptycene-Based Polymers.

A series of chiral fluorescent polymers containing optically active triptycene units in the main chain were synthesized via Sonogashira-Hagihara coupling copolymerizations of (R,R)- or (S,S)-2,6-diethynyltriptycene with a range of diiodoaryls. Their optical and chiroptical properties were investigated under various solution conditions. We observe that these polymers emitted circularly polarized light owing to the chiral triptycene framework with a handed twisted rigid structure, and the fluorescence colors could be tuned in the whole visible range from blue to red by replacing the achiral comonomer units. They possessed luminescence dissymmetry factors of approximately 1.0 × 10-3, regardless of the incorporated comonomer units.

Chiral triptycene-pyrene π-conjugated chromophores with circularly polarized luminescence.

A pair of optically pure triptycene derivatives ((R,R)- and (S,S)-3) containing fluorescent pyrene-based π-conjugated pendant groups attached through amide spacers were prepared via a resolution step using chiral high-performance liquid chromatography. Their absorption, circular dichroism, photoluminescence and circularly polarized luminescence (CPL) properties were investigated under various solution conditions. (R,R)- and (S,S)-3 exhibited clear solvent- and concentration-dependences of the optical and chiroptical properties as a result of the interconversion between molecularly dispersed and aggregate states. We also observed that (R,R)- and (S,S)-3 emitted left- and right-handed circularly polarized light, respectively, upon UV irradiation under aggregation conditions, and their dissymmetry factors were found to be greater than 1.0 × 10-3. Based on the contrasting result that almost no CPL signal appeared in the monomeric solution state, the resulting CPL was considered to arise from the supramolecular chirality induced in the hydrogen-bonded aggregate, wherein the pyrenyl pendants of 3 were most likely arranged in a preferred-handed twisting structure.