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Background Contour delineation, a crucial process in radiation oncology, is time-consuming and inaccurate due to inter-observer variation has been a critical issue in this process. An atlas-based automatic segmentation was developed to improve the delineation efficiency and reduce inter-observer variation. Additionally, automated segmentation using artificial intelligence (AI) has recently become available. In this study, auto-segmentations by atlas- and AI-based models for Organs at Risk (OAR) in patients with prostate and head and neck cancer were performed and delineation accuracies were evaluated. Methods Twenty-one patients with prostate cancer and 30 patients with head and neck cancer were evaluated. MIM Maestro was used to apply the atlas-based segmentation. MIM Contour ProtégéAI was used to apply the AI-based segmentation. Three similarity indices, the Dice similarity coefficient (DSC), Hausdorff distance (HD), and mean distance to agreement (MDA), were evaluated and compared with manual delineations. In addition, radiation oncologists visually evaluated the delineation accuracies. Results Among patients with prostate cancer, the AI-based model demonstrated higher accuracy than the atlas-based on DSC, HD, and MDA for the bladder and rectum. Upon visual evaluation, some errors were observed in the atlas-based delineations when the boundary between the small bowel or the seminal vesicle and the bladder was unclear. For patients with head and neck cancer, no significant differences were observed between the two models for almost all OARs, except small delineations such as the optic chiasm and optic nerve. The DSC tended to be lower when the HD and the MDA were smaller in small volume delineations. Conclusions In terms of efficiency, the processing time for head and neck cancers was much shorter than manual delineation. While quantitative evaluation with AI-based segmentation was significantly more accurate than atlas-based for prostate cancer, there was no significant difference for head and neck cancer. According to the results of visual evaluation, less necessity of manual correction in AI-based segmentation indicates that the segmentation efficiency of AI-based model is higher than that of atlas-based model. The effectiveness of the AI-based model can be expected to improve the segmentation efficiency and to significantly shorten the delineation time.

BeO ceramics (Thermalox® 995, Materion Corp.) can function as thermoluminescent dosimeters (TLDs) with a tissue-equivalent effective atomic number and sufficient high solidity which can be used as postal dosimeters. To evaluate the feasibility of employing BeO ceramic in proton dosimetry, we investigated the dose–response and the linear energy transfer (LET) dependence of a BeO ceramic TLD. As the BeO ceramic TLDs exhibit two glow peaks, the dose–responses of the integral thermoluminescence (TL) signals for the low-temperature ( G L ) and high-temperature ( G H ) glow peaks, as well as those for entire TL signal ( G T ), were all investigated in this study. The irradiation doses were 0.5, 1.0, 2.0, and 5.0 Gy, and the LET dependence of the TL efficiency was investigated between 0.53 and 7.42 keVµm −1 . All experiments were performed using a 160 MeV proton beam at NIRS-HIMAC in Japan. The TL intensities of G L , G H , and G T increased with increasing irradiation dose. The relation between the TL intensity and irradiation dose could be expressed as a function of a quadratic polynomial equation. The TL efficiencies of glow peaks ( G H and G T ) decreased with decreasing LET, while no significant correlation was observed between G L and LET. The shape of the glow curve of the BeO ceramic depends on the irradiation dose and LET.

To investigate the genetic basis of erythromycin resistance in Riemerella anatipestifer, the MIC to erythromycin of 79 R. anatipestifer isolates from China and one typed strain, ATCC11845, were evaluated. The results showed that 43 of 80 (53.8%) of the tested R. anatipestifer strains showed resistance to erythromycin, and 30 of 43 erythromycin-resistant R. anatipestifer strains carried ermF or ermFU with an MIC in the range of 32-2048 μg/ml, while the other 13 strains carrying the ereD gene exhibited an MIC of 4-16 μg/ml. Of 30 ermF + R. anatipestifer strains, 27 (90.0%) carried the ermFU gene which may have been derived from the CTnDOT-like element, while three other strains carried ermF from transposon Tn4351. Moreover, sequence analysis revealed that ermF, ermFU, and ereD were located within the multiresistance region of the R. anatipestifer genome.

We propose a two-step method to converse human tissue materials from patient computed tomography (CT) images, which is required in dose reconstructions for a retrospective study of carbon-ion radiotherapy (CIRT) using Monte Carlo (MC) simulation. The first step was to assign the standard tissues of the International Commission on Radiological Protection reference phantoms according to the CT-number. The second step was to determine the mass density of each material based on the relationship between CT-number and stopping power ratio (Hounsfield unit [HU]-SPR) registered in treatment planning system (TPS). Direct implementation of the well-calibrated HU-SPR curve allows the reproduction of previous clinical treatments recorded in TPS without uncertainty due to a mismatch of the CT scanner or scanning conditions, whereas MC simulation with realistic human tissue materials can fulfill the out-of-field dose, which was missing in the record. To validate our proposed method, depth-dose distributions in the homogenous and heterogeneous phantoms irradiated by a 400 MeV/u carbon beam with an 8 cm spread-out Bragg peak (SOBP) were computed by the MC simulation in combination with the proposed methods and compared with those of TPS. Good agreement of the depth-dose distributions between the TPS and MC simulation (within a 1% discrepancy in range) was obtained for different materials. In contrast, fluence distributions of secondary particles revealed the necessity of MC simulation using realistic human tissue. The proposed material assignment method will be used for a retrospective study using previous clinical data of CIRT at the National Institute of Radiological Sciences (NIRS).

A realistic X‐ray energy spectrum is essential for accurate dose calculation using the Monte Carlo (MC) algorithm. An energy spectrum for dose calculation in the radiation treatment planning system is modeled using the MC algorithm and adjusted to obtain acceptable agreement with the measured percent depth dose (PDD) and off‐axis ratio. The simulated energy spectrum may not consistently reproduce a realistic energy spectrum. Therefore, direct measurement of the X‐ray energy spectrum from a linac is necessary to obtain a realistic spectrum. Previous studies have measured low photon fluence directly, but the measurement was performed with a nonclinical linac with a thick target and a long target‐to‐detector distance. In this study, an X‐ray energy spectrum from a clinical linac was directly measured using a NaI(Tl) scintillator at an ultralow dose rate achieved by adjusting the gun grid voltage. The measured energy spectrum was unfolded by the Gold algorithm and compared with a simulated spectrum using statistical tests. Furthermore, the PDD was calculated using an unfolded energy spectrum and a simulated energy spectrum was compared with the measured PDD to evaluate the validity of the unfolded energy spectrum. Consequently, there was no significant difference between the unfolded and simulated energy spectra by nonparametric, Wilcoxon's rank‐sum, chi‐square, and two‐sample Kolmogorov–Smirnov tests with a significance level of 0.05. However, the PDD calculated from the unfolded energy spectrum better agreed with the measured compared to the calculated PDD results from the simulated energy spectrum. The adjustment of the incident electron parameters using MC simulation is sensitive and takes time. Therefore, it is desirable to obtain the energy spectrum by direct measurement. Thus, a method to obtain the realistic energy spectrum by direct measurement was proposed in this study.

The production of extended-spectrum beta-lactamase (ESBL) is one of the major antimicrobial resistance mechanisms in Enterobacteriaceae , and the increasing number of ESBL-producing Enterobacteriaceae isolated from water environments has posed a serious threat to the public health. The study aimed to analyze prevalence and characterization of ESBL-producing Enterobacteriaceae from rural well waters in Taian, China. A total of 10 isolates expressing an ESBL phenotype, including 9 Escherichia coli ( E. coli ) and 1 Klebsiella pneumoniae ( K. pneumoniae ) was obtained from 4 (4 %) out of the 100 sampled wells. ESBL genotype revealed that 9 expressed CTX-M-15 and 1 produced CTX-M-27. Five out of 8 ESBL-producing E. coli expressing CTX-M-15 belonged to ST10, which are mostly detected from human feces in China. Importantly, the only strain of CTX-M-27-producing E. coli belonged to multi-locus sequence type B2:131 (ST131), which may be related with severe infection in humans and animals.

Background The interaction between breathing motion and scanning beams causes interplay effects in spot-scanning proton therapy for lung cancer, resulting in compromised treatment quality. This study investigated the effects and clinical robustness of two types of spot-scanning proton therapy with motion-mitigation techniques for locally advanced non-small cell lung cancer (NSCLC) using a new simulation tool (4DCT-based dose reconstruction). Methods Three-field single-field uniform dose (SFUD) and robustly optimized intensity-modulated proton therapy (IMPT) plans combined with gating and re-scanning techniques were created using a VQA treatment planning system for 15 patients with locally advanced NSCLC (70 GyRBE/35 fractions). In addition, gating windows of three or five phases around the end-of-expiration phase and two internal gross tumor volumes (iGTVs) were created, and a re-scanning number of four was used. First, the static dose (SD) was calculated using the end-of-expiration computed tomography (CT) images. The four-dimensional dynamic dose (4DDD) was then calculated using the SD plans, 4D-CT images, and the deformable image registration technique on end-of-expiration CT. The target coverage (V 98%, V 100% ), homogeneity index (HI), and conformation number (CN) for the iGTVs and organ-at-risk (OAR) doses were calculated for the SD and 4DDD groups and statistically compared between the SD, 4DDD, SFUD, and IMPT treatment plans using paired t-test. Results In the 3- and 5-phase SFUD, statistically significant differences between the SD and 4DDD groups were observed for V 100% , HI, and CN. In addition, statistically significant differences were observed for V 98% , V 100% , and HI in phases 3 and 5 of IMPT. The mean V 98% and V 100% in both 3-phase plans were within clinical limits (> 95%) when interplay effects were considered; however, V 100% decreased to 89.3% and 94.0% for the 5-phase SFUD and IMPT, respectively. Regarding the significant differences in the deterioration rates of the dose volume histogram (DVH) indices, the 3-phase SFUD plans had lower V 98% and CN values and higher V 100% values than the IMPT plans. In the 5-phase plans, SFUD had higher deterioration rates for V 100% and HI than IMPT. Conclusions Interplay effects minimally impacted target coverage and OAR doses in SFUD and robustly optimized IMPT with 3-phase gating and re-scanning for locally advanced NSCLC. However, target coverage significantly declined with an increased gating window. Robustly optimized IMPT showed superior resilience to interplay effects, ensuring better target coverage, prescription dose adherence, and homogeneity than SFUD. Trial registration : None.

The glow curve components and thermoluminescence (TL) parameters of BeO ceramics plates with high bioequivalence were analyzed using extremely slow heating rates. Thermalox 995 was used as the BeO ceramic plates, which is a material with a BeO content of 99.5% or higher. The size of the plates was 10 × 10 × 0.7 mm 3 with a density of 2.85 g/cm 3 , and an effective atomic number of 7.13. A linear accelerator was used for irradiation of the BeO plates at 5 Gy of 6 MV X-rays. After irradiation, the TL glow curve was measured using an in-house developed measurement instrument; the TL intensity was recorded from 50 to 400 °C with heating rates of 0.133, 0.05, and 0.005 °C/s used in three patterns. General-order kinetics were used for the theoretical analysis, which takes recapture into account. After irradiation, post-annealing was performed in the range of 50 to 350 °C at 50 °C intervals, and component analysis of the glow curves was also performed. The TL parameters were calculated from glow curves measured up to a heating rate that was three orders of magnitude slower than that previously measured. The activation energy and frequency factor for the main glow component at low temperatures were 1.15 eV and 1.11 × 10 11 /s, respectively, while those for the main glow component at high temperatures were 1.74 eV and 8.65 × 10 13 /s. The glow peak for the BeO ceramic plates were also determined have a low TL intensity component in close proximity to these two glow components. Furthermore, an increase in TL efficiency was observed when the glow curve was measured using an extremely slow heating rate. This may be due to a change of the carriers from TL-inactive when the glow curve is measured with a fast heating rate to TL-active with a longer thermal excitation time.

Background Low levels of mcr‐1 were detected in Escherichia coli from wastewater samples across the world; hence, further monitoring and management of accumulation of mcr‐1‐positive bacteria in wastewater are urgently recommended. Objectives In this study, we have reported the detection of E. coli strains carrying the colistin resistance gene mcr‐1 in slaughterhouse wastewater discharged into Dawen river. Methods Twenty samples were collected aseptically and subjected to polymerase chain reaction (PCR) analysis, multilocus sequence typing and antibiotic resistance tests. Conjugation tests were also performed. Results The screening results showed a positive rate of 20% (4/20), which suggested that the mcr‐1 gene had polluted the environment of the river. The mcr‐1 gene had successfully transferred from the donor to recipient cells, which showed the possibility of horizontal transfer of mcr‐1 and subsequently, the formation of multidrug resistant bacteria in the river. Conclusions Our findings demonstrated a high occurrence of colistin‐resistant E. coli carrying the mcr‐1 gene on transferrable plasmids in slaughterhouses and indicated their dissemination into river. Large‐scale cross‐border cooperation would be required for the effective control of the spread of antibiotic‐resistant bacteria. Large‐scale cross‐border cooperation would be required for the effective control of the spread of antibiotic‐resistant bacteria. Our findings demonstrated the high occurrence of colistin‐resistant E. coli carrying mcr‐1 on transferrable plasmids in slaughterhouses and indicated their dissemination into river.