Image synthesis of monoenergetic CT image in dual-energy CT using kilovoltage CT with deep convolutional generative adversarial networks

Purpose: To synthesize a dual-energy computed tomography (DECT) image from an equivalent kilovoltage computed tomography (kV-CT) image using a deep convolutional adversarial network. Methods: A total of 18,084 images of 28 patients are categorized into training and test datasets. Monoenergetic CT images at 40, 70, and 140 keV and equivalent kVCT images at 120 kVp are reconstructed via DECT and are defined as the reference images. An image prediction framework is created to generate monoenergetic computed tomography (CT) images from kV-CT images. The accuracy of the images generated by the CNN model is determined by evaluating the mean absolute error (MAE), mean square error (MSE), relative root mean square error (RMSE), peak signal-to-noise ratio (PSNR), structural similarity index (SSIM), and mutual information between the synthesized and reference monochromatic CT images. Moreover, the pixel values between the synthetic and reference images are measured and compared using a manually drawn region of interest (ROI). Results: The difference in the monoenergetic CT numbers of the ROIs between the synthetic and reference monoenergetic CT images is within the standard deviation values. The MAE, MSE, RMSE, and SSIM are the smallest for the image conversion of 120 kVp to 140 keV. The PSNR is the smallest and the MI is the largest for the synthetic 70 keV image. Conclusions: The proposed model can act as a suitable alternative to the existing methods for the reconstruction of monoenergetic CT images in DECT from single-energy CT images

Shedding light on the base-pair opening dynamics of nucleic acids in living human cells

生細胞中の核酸のダイナミクスに光を当てる --生細胞中における挙動は試験管中とは異なる--. 京都大学プレスリリース. 2022-11-30.Base-pair opening is a fundamental property of nucleic acids that plays important roles in biological functions. However, studying the base-pair opening dynamics inside living cells has remained challenging. Here, to determine the base-pair opening kinetics inside living human cells, the exchange rate constant (kex) of the imino proton with the proton of solvent water involved in hairpin and G-quadruplex (GQ) structures is determined by the in-cell NMR technique. It is deduced on determination of kex values that at least some G-C base pairs of the hairpin structure and all G-G base-pairs of the GQ structure open more frequently in living human cells than in vitro. It is suggested that interactions with endogenous proteins could be responsible for the increase in frequency of base-pair opening. Our studies demonstrate a difference in dynamics of nucleic acids between in-cell and in vitro conditions

Pre-regulation of the planar chirality of pillar[5]arenes for preparing discrete chiral nanotubes

Regulating the chirality of macrocyclic host molecules and supramolecular assemblies is crucial because chirality often plays a role in governing the properties of these systems. Herein, we describe pillar[5]arene-based chiral nanotube formation via pre-regulation of the building blocks' chirality, which is different from frequently used post-regulation strategies. The planar chirality of rim-differentiated pillar[5]arenes is initially regulated by chiral awakening and further induction/inversion through stepwise achiral external stimuli. The pre-regulated chiral information is well stored in discrete nanotubes by interacting with a per-alkylamino-substituted pillar[5]arene. Such pre-regulation is more efficient than post-regulating the chirality of nanotubes

Assessment of biological dosimetric margin for stereotactic body radiation therapy

Purpose: To develop a novel biological dosimetric margin (BDM) and to create a biological conversion factor (BCF) that compensates for the difference between physical dosimetric margin (PDM) and BDM, which provides a novel scheme of a direct estimation of the BDM from the physical dose (PD) distribution. Methods: The offset to isocenter was applied in 1‐mm steps along left‐right (LR), anterior‐posterior (AP), and cranio‐caudal (CC) directions for 10 treatment plans of lung stereotactic body radiation therapy (SBRT) with a prescribed dose of 48 Gy. These plans were recalculated to biological equivalent dose (BED) by the linearquadratic model for the dose per fraction (DPF) of d = 3–20 Gy/fr and α/β= 3 - 10. BDM and PDM were defined so that the region that satisfied that the dose covering 95% (or 98%) of the clinical target volume was greater than or equal to the 90% of the prescribed PD and BED, respectively. An empirical formula of the BCF was created as a function of the DPF. Results: There was no significant difference between LR and AP directions for neither the PDM nor BDM. On the other hand, BDM and PDM in the CC direction were significantly larger than in the other directions. BCFs of D95% and D98% were derived for the transverse (LR and AP) and longitudinal (CC) directions. Conclusions: A novel scheme to directly estimate the BDM using the BCF was developed. This technique is expected to enable the BED‐based SBRT treatment planning using PD‐based treatment planning systems

Synthesized effective atomic numbers for commercially available dual-energy CT

Purpose: The objective of this study was to assess synthesized effective atomic number (Zeff) values with a new developed tissue characteristic phantom and contrast material of varying iodine concentrations using single-source fast kilovoltage switching dual-energy CT (DECT) scanner. Methods: A newly developed multi energy tissue characterisation CT phantom and an acrylic phantom with various iodine concentrations of were scanned using single-source fast kilovoltage switching DECT (GE-DECT) scanner. The difference between the measured and theoretical values of Zeff were evaluated. Additionally, the difference and coefficient of variation (CV) values of the theoretical and measured values were compared with values obtained with the Canon-DECT scanner that was analysed in our previous study. Results: The average Zeff difference in the Multi-energy phantom was within 4.5%. The average difference of the theoretical and measured Zeff values for the acrylic phantom with variation of iodine concentration was within 3.3%. Compared to the results for the single-source Canon-DECT scanner used in our previous study, the average difference and CV of the theoretical and measured Zeff values obtained with the GE-DECT scanner were markedly smaller. Conclusions: The accuracy of the synthesized Zeff values with GE-DECT had a good agreement with the theoretical Zeff values for the Multi-Energy phantom. The GE-DECT could reduce the noise and the accuracy of the Zeff values than that with Canon-DECT for the varying iodine concentrations of contrast medium. Advances in knowledge: The accuracy and precision of the Zeff values of the contrast medium with the GE-DECT could be sufficient with human equivalent materials

Health effects of immediate telework introduction during the COVID-19 era in Japan: A cross-sectional study

[Background] Telework has been widely discussed in several fields; however, there is a lack of research on the health aspects of teleworking. The current study was conducted to determine the health effects of teleworking during an emergency statement as evidence for future policy development. [Method] This was a cross-sectional study in which we administered an online questionnaire to 5, 214 general workers (response rate = 36.4%) from June 2020 to August 2020. Based on working methods during the pandemic, workers were categorized into the office group (n = 86) and telework group (n = 1597), and we characterized their demographics, changes in lifestyle, telework status, physical symptoms, and mental health. [Results] The results showed that the workers’ residence, marital status, management positions, and employee status affected the choice of the work method. During the emergency, teleworkers experienced more changes in their habits than office workers. In terms of exercise habits, 67.0% of the individuals belonging to the office-telework (OT) group exercised less. Approximately half of the teleworkers were satisfied with their telework, and those in the OT group were less satisfied with their telework than those in the telework-telework (TT) group, and they reported an increase in both working hours and meeting hours. Work-family conflict was more pronounced in the TT group than in the two other groups. Only 13.2% of individuals did not experience any stress in the past 30 days, and all three groups showed varying degrees of anxiety and depressive tendencies. In addition, all teleworkers experienced adverse physical symptoms before and after the emergency. [Conclusion] Health issues associated with teleworking should be given adequate attention

Mechanistic Insight on the Formation of GaN:ZnO Solid Solution from Zn–Ga Layered Double Hydroxide Using Urea as the Nitriding Agent

A solid solution of GaN and ZnO (GaN:ZnO) is promising as a photocatalyst for visible light-driven overall water splitting to produce H2. However, several obstacles still exist in the conventional preparation procedure of GaN:ZnO. For example, the atomic distributions of Zn and Ga are non-uniform in GaN:ZnO when a mixture of the metal oxides, i.e., Ga2O3 and ZnO, is used as a precursor. In addition, GaN:ZnO is generally prepared under harmful NH3 flow for long durations at high temperatures. Here, a facile synthesis of GaN:ZnO with homogeneous atomic composition via a simple and safe procedure is reported. A layered double hydroxide (LDH) containing Zn2+ and Ga3+ was used to increase the uniformity of the atomic distributions of Zn and Ga in GaN:ZnO. We employed urea as a nitriding agent instead of gaseous NH3 to increase the safety of the reaction. Through the optimization of reaction conditions such as heattreatment temperature and content of urea, single-phase GaN:ZnO was successfully obtained. In addition, the nitridation mechanism using urea was investigated in detail. NH3 released from the thermal decomposition of urea did not directly nitride the LDH precursor. X-ray absorption and infrared spectroscopies revealed that Zn(CN2)-like intermediate species were generated at the middle temperature range and Ga–N bonds formed at high temperature along with dissociation of CO and CO2.This file includes Supporting Information.This work was supported by JSPS KAKENHI Grant Number JP16H06438, JP16H06441, JP17H05483, JP17H03392. This work was partly supported by the Center for Functional Nano Oxide at Hiroshima University. The synchrotron radiation experiments were performed at the BL01B1 beamline of SPring-8 with the approval of the Japan Synchrotron Radiation Research 32 Institute (JASRI) (Proposal No. 2017B1043 and 2018A1749)

Functional Image-Guided Radiotherapy Planning in Respiratory- Gated Intensity-Modulated Radiation Therapy (IMRT) for Lung Cancer Patients with chronic obstructive pulmonary disease (COPD)

(Purpose) To investigate the incorporation of functional lung image-derived low attenuation area (LAA) based on four-dimensional computed tomography (4D-CT) into respiratory-gated intensity-modulated radiation therapy (IMRT) or volumetric modulated arc therapy (VMAT) in treatment planning for lung cancer patients with chronic obstructive pulmonary disease (COPD). (Materials and Methods) Eight lung cancer patients with COPD were the subjects of this study. LAA was generated from 4D-CT data sets according to CT values lower than -860 Hounsfield units (HU) as a threshold. The functional lung image was defined as the area where LAA was excluded from the image of the total lung. Two respiratory-gated radiotherapy plans (70 Gy/35 fr) were designed and compared in each patient as follows: 1) Plan A: anatomical IMRTor VMAT plan based on the total lung 2) Plan F: functional IMRT or VMAT plan based on the functional lung. Dosimetric parameters (V20: the percentage of total lung volume irradiated with ≥ 20 Gy,MLD:mean dose of total lung) of the two plans were compared. (Results) V20 was lower in Plan F than in Plan A (mean 1.5 %, p= 0.025 in IMRT, mean 1.6 %, p= 0.044 in VMAT) achieved by a reduction in MLD (mean 0.23 Gy, p= 0.083 in IMRT, mean 0.5 Gy, p= 0.042 in VMAT). No differences were noted in target volume coverage and organ-at-risk doses. (Conclusions) Functional image-guided radiotherapy planning based on LAAin respiratory-guided IMRT or VMAT appears to be effective in preserving a functional lung in lung cancer patients with COPD.This work was supported in part by a Grant-in-Aid for Scientific Research from the Ministry of Education, Culture, Sports, Science and Technology of Japan (Grant no. 22591385), and a Grant-in-Aid for Scientific Research from the Association for Nuclear Technology in Medicine. This work was partly presented at the 52nd Annual Meeting of the American Society of Radiation Oncology, San Diego, CA, Oct 31 - Nov 4, 2010

Outcomes of binocular treatment using a Bangerter occlusion film and computer games in patients with intractable unilateral amblyopia

　To report outcomes following binocular treatment using a Bangerter occlusion filter (BF) and computer games in patients with intractable amblyopia.METHODS: Eight patients (4 boys, mean ± SD age: 8.0 ± 0.8 years) with unilateral amblyopia that did not respond to conventional treatments were studied. They were instructed to play action games for one hour a day while wearing spectacles with an adequate level of BF in front of the non-amblyopic eye so that the visual input became the same between the two eyes. They continued this exercise for eight weeks, and we assessed their visual acuity and spatial sensitivity at baseline, and at 4- and 8-week visits. To confirm the maintenance of efficacy after the treatment, we assessed them again at a 12-week visit.　RESULTS: The mean log MAR at distance improved from 0.32 to 0.24 at the 4-week visit (p < 0.05), and appeared to continue up to eight weeks, but returned to the baseline level at the 12-week visit (four weeks after terminating the treatment). There was no significant improvement in the mean log MAR at near. Contrast sensitivity significantly improved only at three cycles/ degree (p < 0.05), and this effect persisted until the 12-week visit. The distance log MAR at the 12-week visit had a significant correlation with the strength of suppression for the amblyopic eye at baseline (r = 0.71, p < 0.05).　CONCLUSIONS: Binocular treatment improved visual function only in terms of contrast sensitivity at low spatial frequency. Patients who have weak suppression may gain some benefit from this treatment