Since manual detection of brain metastases (BMs) is time consuming, studies have been conducted to automate this process using deep learning. The purpose of this study was to conduct a systematic ...review and meta-analysis of the performance of deep learning models that use magnetic resonance imaging (MRI) to detect BMs in cancer patients. A systematic search of MEDLINE, EMBASE, and Web of Science was conducted until 30 September 2022. Inclusion criteria were: patients with BMs; deep learning using MRI images was applied to detect the BMs; sufficient data were present in terms of detective performance; original research articles. Exclusion criteria were: reviews, letters, guidelines, editorials, or errata; case reports or series with less than 20 patients; studies with overlapping cohorts; insufficient data in terms of detective performance; machine learning was used to detect BMs; articles not written in English. Quality Assessment of Diagnostic Accuracy Studies-2 and Checklist for Artificial Intelligence in Medical Imaging was used to assess the quality. Finally, 24 eligible studies were identified for the quantitative analysis. The pooled proportion of patient-wise and lesion-wise detectability was 89%. Articles should adhere to the checklists more strictly. Deep learning algorithms effectively detect BMs. Pooled analysis of false positive rates could not be estimated due to reporting differences.
In the present study, we have presented and validated a plastic scintillation detector (PSD) system designed for real-time multiprobe in vivo measurements.
The PSDs were built with a dose-sensitive ...volume of 0.4 mm(3). The PSDs were assembled into modular detector patches, each containing five closely packed PSDs. Continuous dose readings were performed every 150 ms, with a gap between consecutive readings of <0.3 ms. We first studied the effect of electron multiplication. We then assessed system performance in acrylic and anthropomorphic pelvic phantoms.
The PSDs were compatible with clinical rectal balloons and were easily inserted into the anthropomorphic phantom. With an electron multiplication average gain factor of 40, a twofold increase in the signal/noise ratio was observed, making near real-time dosimetry feasible. Under calibration conditions, the PSDs agreed with the ion chamber measurements to 0.08%. Precision, evaluated as a function of the total dose delivered, ranged from 2.3% at 2 cGy to 0.4% at 200 cGy.
Real-time PSD measurements are highly accurate and precise. These PSDs can be mounted onto rectal balloons, transforming these clinical devices into in vivo dose detectors without modifying current clinical practice. Real-time monitoring of the dose delivered near the rectum during prostate radiotherapy should help radiation oncologists protect this sensitive normal structure.
•We investigate the relation between DB pension funds regulation and asset allocation.•Identification is enabled by regulatory revisions across three countries.•We detail the investment, valuation ...and funding standards’ evolution over 1992–2011.•Risk-based capital and market valuation are linked to 6–7% lower investment risk.•Fund risk-taking under solvency constraints depend on the financial market condition.
We investigate the extent to which regulations governing investment, valuation and funding affect the riskiness of defined benefit pension funds' asset allocation. We compare the regulatory frameworks of public, corporate and industry pension funds in the United States, Canada and the Netherlands over 1992–2011. Derived from panel data analysis of a unique set of asset allocation details for close to 600 funds, our results highlight that regulatory factors are more economically significant than pension funds' characteristics in shaping asset allocation. In particular, risk-based capital requirements and mark-to-market valuation are both associated with a 7% lower risky asset exposure, especially equities, regardless of market conditions. By contrast, the exposure of a pension fund subject to a 100% funding requirement does not differ significantly from that of an unconstrained pension fund during normal times, but the constrained pension fund invests 4% less in risky assets during a financial crisis. In line with theoretical predictions, we find that risk-based capital requirements and minimum funding limits have different consequences for pension funds’ risk-taking.
Anaemia is frequently seen in patients with diabetes and the main cause is renal failure. At all stages of renal failure, however, the prevalence of anaemia is higher in diabetes patients than ...expected for their glomerular filtration rate, suggesting that causes of anaemia other than renal failure are at work. The present cross-sectional study was conducted to investigate the possible iatrogenic causes of anaemia in patients with diabetes.
This was a hospital-based cross-sectional study of all patients who had biological and clinical data covering a 2-year period. All had been in contact with the diabetes department either as outpatients or as inpatients mostly for educational purposes. Clinical factors, including type of diabetes, known diabetes complications, treatments received and biological data, were reviewed for their possible involvement in anaemia.
A total of 4145 consecutive patients were included. Anaemia was observed in 1065 (25.7%) of them. Patients with anaemia were more frequently women and those with longer durations of diabetes. Haemoglobin concentrations were decreased, and prevalence of anaemia was increased at all stages of renal failure, already at stage 2, KDIGO classification. Anaemia patients were more frequently taking insulin, antiplatelet agents and renin–angiotensin system blockers (RASBs). After exclusion of patients with specific causes of anaemia, logistic regression analysis of all parameters correlated with anaemia on univariate analysis revealed that anaemia was associated with gender, antiplatelet agents and RASBs.
This study has confirmed that anaemia is frequently seen in diabetes patients and strongly associated with renal failure (already at stage 2). Our observations highlight the adjuvant role of drugs, particularly RASBs, in the risk of anaemia in patients with diabetes.
A strong dose-volume relationship exists between the amount of small bowel receiving low- to intermediate-doses of radiation and the rates of acute, severe gastrointestinal toxicity, principally ...diarrhea. There is considerable interest in the application of highly conformal treatment approaches, such as intensity-modulated radiation therapy (IMRT), to reduce dose to adjacent organs-at-risk in the treatment of carcinoma of the rectum. Therefore, we performed a comprehensive dosimetric evaluation of IMRT compared to 3-dimensional conformal radiation therapy (3DCRT) in standard, preoperative treatment for rectal cancer.
Using RTOG consensus anorectal contouring guidelines, treatment volumes were generated for ten patients treated preoperatively at our institution for rectal carcinoma, with IMRT plans compared to plans derived from classic anatomic landmarks, as well as 3DCRT plans treating the RTOG consensus volume. The patients were all T3, were node-negative (N = 1) or node-positive (N = 9), and were planned to a total dose of 45-Gy. Pairwise comparisons were made between IMRT and 3DCRT plans with respect to dose-volume histogram parameters.
IMRT plans had superior PTV coverage, dose homogeneity, and conformality in treatment of the gross disease and at-risk nodal volume, in comparison to 3DCRT. Additionally, in comparison to the 3DCRT plans, IMRT achieved a concomitant reduction in doses to the bowel (small bowel mean dose: 18.6-Gy IMRT versus 25.2-Gy 3DCRT; p = 0.005), bladder (V40Gy: 56.8% IMRT versus 75.4% 3DCRT; p = 0.005), pelvic bones (V40Gy: 47.0% IMRT versus 56.9% 3DCRT; p = 0.005), and femoral heads (V40Gy: 3.4% IMRT versus 9.1% 3DCRT; p = 0.005), with an improvement in absolute volumes of small bowel receiving dose levels known to induce clinically-relevant acute toxicity (small bowel V15Gy: 138-cc IMRT versus 157-cc 3DCRT; p = 0.005). We found that the IMRT treatment volumes were typically larger than that covered by classic bony landmark-derived fields, without incurring penalty with respect to adjacent organs-at-risk.
For rectal carcinoma, IMRT, compared to 3DCRT, yielded plans superior with respect to target coverage, homogeneity, and conformality, while lowering dose to adjacent organs-at-risk. This is achieved despite treating larger volumes, raising the possibility of a clinically-relevant improvement in the therapeutic ratio through the use of IMRT with a belly-board apparatus.
To determine whether there exists any significant difference in normal tissue toxicity between intensity modulated radiation therapy (IMRT) or proton therapy for the treatment of non-small cell lung ...cancer.
A total of 134 study patients (n=49 treated with proton therapy, n=85 with IMRT) treated in a randomized trial had a previously validated esophageal toxicity imaging biomarker, esophageal expansion, quantified during radiation therapy, as well as esophagitis grade (Common Terminology Criteria for Adverse Events version 3.0), on a weekly basis during treatment. Differences between the 2 modalities were statically analyzed using the imaging biomarker metric value (Kruskal-Wallis analysis of variance), as well as the incidence and severity of esophagitis grade (χ
and Fisher exact tests, respectively). The dose-response of the imaging biomarker was also compared between modalities using esophageal equivalent uniform dose, as well as delivered dose to an isotropic esophageal subvolume.
No statistically significant difference in the distribution of esophagitis grade, the incidence of grade ≥3 esophagitis (15 and 11 patients treated with IMRT and proton therapy, respectively), or the esophageal expansion imaging biomarker between cohorts (P>.05) was found. The distribution of imaging biomarker metric values had similar distributions between treatment arms, despite a slightly higher dose volume in the proton arm (P>.05). Imaging biomarker dose-response was similar between modalities for dose quantified as esophageal equivalent uniform dose and delivered esophageal subvolume dose. Regardless of treatment modality, there was high variability in imaging biomarker response, as well as esophagitis grade, for similar esophageal doses between patients.
There was no significant difference in esophageal toxicity from either proton- or photon-based radiation therapy as quantified by esophagitis grade or the esophageal expansion imaging biomarker.
Using first-principles density functional calculations, we show that hexagonal metallic silicon nanotubes can be stabilized by doping with 3d transition metal atoms. Finite nanotubes doped with Fe ...and Mn have high local magnetic moments, whereas Co-doped nanotubes have low values and Ni-doped nanotubes are mostly nonmagnetic. The infinite Si24Fe4 nanotube is found to be ferromagnetic with nearly the same local magnetic moment on each Fe atom as in bulk iron. Mn-doped nanotubes are antiferromagnetic, but a ferrromagnetic state lies only 0.03 eV higher in energy with a gap in the majority spin bands near the Fermi energy. These materials are interesting for silicon-based spintronic devices and other nanoscale magnetic applications.
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