Refine
Has Fulltext
- yes (5)
Is part of the Bibliography
- yes (5)
Document Type
- Journal article (5) (remove)
Language
- English (5)
Keywords
- prostate cancer (2)
- Applied physics (1)
- Biomedical engineering (1)
- Halcyon (1)
- Imaging techniques (1)
- Synergy (1)
- acute toxicity (1)
- adaptive radiotherapy (1)
- anaemia walk‐in clinic (1)
- bee community (1)
- blood transfusion (1)
- deformable image registration (1)
- dominant intraprostatic lesion (1)
- dose accumulation (1)
- dose evaluation (1)
- geographic biases (1)
- global dataset (1)
- hypofractionation (1)
- intensification (1)
- iron deficiency (1)
- land-use change (1)
- orthopaedic patients (1)
- patient blood management (1)
- prostate Imaging Reporting and Data System (1)
- reticulocyte haemoglobin (1)
- taxonomic biases (1)
Predicting bee community responses to land-use changes: Effects of geographic and taxonomic biases
(2016)
Land-use change and intensification threaten bee populations worldwide, imperilling pollination services. Global models are needed to better characterise, project, and mitigate bees' responses to these human impacts. The available data are, however, geographically and taxonomically unrepresentative; most data are from North America and Western Europe, overrepresenting bumblebees and raising concerns that model results may not be generalizable to other regions and taxa. To assess whether the geographic and taxonomic biases of data could undermine effectiveness of models for conservation policy, we have collated from the published literature a global dataset of bee diversity at sites facing land-use change and intensification, and assess whether bee responses to these pressures vary across 11 regions (Western, Northern, Eastern and Southern Europe; North, Central and South America; Australia and New Zealand; South East Asia; Middle and Southern Africa) and between bumblebees and other bees. Our analyses highlight strong regionally-based responses of total abundance, species richness and Simpson's diversity to land use, caused by variation in the sensitivity of species and potentially in the nature of threats. These results suggest that global extrapolation of models based on geographically and taxonomically restricted data may underestimate the true uncertainty, increasing the risk of ecological surprises.
Purpose
To compare radiotherapy plans between an O-ring and a conventional C-arm linac for hypofractionated high-dose prostate radiotherapy in terms of plan quality, dose distribution, and quality assurance in a multi-vendor environment.
Methods
Twenty prostate cancer treatment plans were irradiated on the O-ring Varian Halcyon linac and were re-optimized for the C-arm Elekta Synergy Agility linac. Dose-volume histogram metrics for target coverage and organ at risk dose, quality assurance, and monitor units were retrospectively compared. Patient-specific quality assurance with ion chamber measurements, gamma index analysis, and portal dosimetry was performed using the Varian Portal Dosimetry system and the ArcCHECK® phantom (Sun Nuclear Corporation). Prostate-only radiotherapy was delivered with simultaneous integrated boost (SIB) volumetric modulated arc therapy (VMAT) in 20 fractions of 2.5/3.0 Gy each.
Results
For both linacs, target coverage was excellent and plan quality comparable. Homogeneity in PTVBoost was high for Synergy as well as Halcyon with a mean homogeneity index of 0.07 ± 0.01 and 0.05 ± 0.01, respectively. Mean dose for the organs at risk rectum and bladder differed not significantly between the linacs but were higher for the femoral heads and penile bulb for Halcyon. Quality assurance showed no significant differences in terms of ArcCHECK gamma pass rates. Median pass rate for 3%/2 mm was 99.3% (96.7 to 99.8%) for Synergy and 99.8% (95.6 to 100%) for Halcyon. Agreement between calculated and measured dose was high with a median deviation of −0.6% (−1.7 to 0.8%) for Synergy and 0.2% (−0.6 to 2.3%) for Halcyon. Monitor units were higher for the Halcyon by approximately 20% (p < 0.001).
Conclusion
Hypofractionated high-dose prostate cancer SIB VMAT on the Halcyon system is feasible with comparable plan quality in reference to a standard C-arm Elekta Synergy linac.
Magnetic Particle Imaging (MPI) is a promising new tomographic modality for fast as well as three-dimensional visualization of magnetic material. For anatomical or structural information an additional imaging modality such as computed tomography (CT) is required. In this paper, the first hybrid MPI-CT scanner for multimodal imaging providing simultaneous data acquisition is presented.
Background
Evaluation of delivered dose to the dominant intraprostatic lesion (DIL) for moderately hypofractionated radiotherapy of prostate cancer by cone beam computed tomography (CBCT)-based dose accumulation and target coverage analysis.
Methods
Twenty-three patients with localized prostate cancer treated with moderately hypofractionated prostate radiotherapy with simultaneous integrated boost (SIB) between December 2016 and February 2020 were retrospectively analyzed. Included patients were required to have an identifiable DIL on bi-parametric planning magnetic resonance imaging (MRI). After import into the RayStation treatment planning system and application of a step-wise density override, the fractional doses were computed on each CBCT and were consecutively mapped onto the planning CT via a deformation vector field derived from deformable image registration. Fractional doses were accumulated for all CBCTs and interpolated for missing CBCTs, resulting in the delivered dose for PTV\(_{DIL}\), PTV\(_{Boost}\), PTV, and the organs at risk. The location of the index lesions was recorded according to the sector map of the Prostate Imaging Reporting and Data System (PIRADS) Version 2.1. Target coverage of the index lesions was evaluated and stratified for location.
Results
In total, 338 CBCTs were available for analysis. Dose accumulation target coverage of PTV\(_{DIL}\), PTV\(_{Boost}\), and PTV was excellent and no cases of underdosage in D\(_{Mean}\), D_95%, D_02%, and D_98% could be detected. Delivered rectum D\(_{Mean}\) did not significantly differ from the planned dose. Bladder mean DMean was higher than planned with 19.4 ± 7.4 Gy versus 18.8 ± 7.5 Gy, p < 0.001. The penile bulb showed a decreased delivered mean DMean with 29.1 ± 14.0 Gy versus 29.8 ± 14.4 Gy, p < 0.001. Dorsal DILs, defined as DILs in the posterior medial peripheral zone of the prostate, showed a significantly lower delivered dose with a mean DMean difference of 2.2 Gy (95% CI 1.3–3.1 Gy, p < 0.001) compared to ventral lesions.
Conclusions
CBCT-based dose accumulation showed an adequate delivered dose to the dominant intraprostatic lesion and organs at risk within planning limits. Cautious evaluation of the target coverage for index lesions adjacent to the rectum is warranted to avoid underdosage.
Background
Approximately one in three patients suffers from preoperative anaemia. Even though haemoglobin is measured before surgery, anaemia management is not implemented in every hospital.
Objective
Here, we demonstrate the implementation of an anaemia walk‐in clinic at an Orthopedic University Hospital. To improve the diagnosis of iron deficiency (ID), we examined whether reticulocyte haemoglobin (Ret‐He) could be a useful additional parameter.
Material and Methods
In August 2019, an anaemia walk‐in clinic was established. Between September and December 2019, major orthopaedic surgical patients were screened for preoperative anaemia. The primary endpoint was the incidence of preoperative anaemia. Secondary endpoints included Ret‐He level, red blood cell (RBC) transfusion rate, in‐hospital length of stay and anaemia at hospital discharge.
Results
A total of 104 patients were screened for anaemia. Preoperative anaemia rate was 20.6%. Intravenous iron was supplemented in 23 patients. Transfusion of RBC units per patient (1.7 ± 1.2 vs. 0.2 ± 0.9; p = 0.004) and hospital length of stay (13.1 ± 4.8 days vs. 10.6 ± 5.1 days; p = 0.068) was increased in anaemic patients compared to non‐anaemic patients. Ret‐He values were significantly lower in patients with ID anaemia (33.3 pg [28.6–40.2 pg]) compared to patients with ID (35.3 pg [28.9–38.6 pg]; p = 0.015) or patients without anaemia (35.4 pg [30.2–39.4 pg]; p = 0.001).
Conclusion
Preoperative anaemia is common in orthopaedic patients. Our results proved the feasibility of an anaemia walk‐in clinic to manage preoperative anaemia. Furthermore, our analysis supports the use of Ret‐He as an additional parameter for the diagnosis of ID in surgical patients.