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- Ademuyiwa, Adesoji O., et al.
(författare)
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Determinants of morbidity and mortality following emergency abdominal surgery in children in low-income and middle-income countries
- 2016
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Ingår i: BMJ Global Health. - : BMJ Publishing Group Ltd. - 2059-7908. ; 1:4
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Tidskriftsartikel (refereegranskat)abstract
- Background: Child health is a key priority on the global health agenda, yet the provision of essential and emergency surgery in children is patchy in resource-poor regions. This study was aimed to determine the mortality risk for emergency abdominal paediatric surgery in low-income countries globally.Methods: Multicentre, international, prospective, cohort study. Self-selected surgical units performing emergency abdominal surgery submitted prespecified data for consecutive children aged <16 years during a 2-week period between July and December 2014. The United Nation's Human Development Index (HDI) was used to stratify countries. The main outcome measure was 30-day postoperative mortality, analysed by multilevel logistic regression.Results: This study included 1409 patients from 253 centres in 43 countries; 282 children were under 2 years of age. Among them, 265 (18.8%) were from low-HDI, 450 (31.9%) from middle-HDI and 694 (49.3%) from high-HDI countries. The most common operations performed were appendectomy, small bowel resection, pyloromyotomy and correction of intussusception. After adjustment for patient and hospital risk factors, child mortality at 30 days was significantly higher in low-HDI (adjusted OR 7.14 (95% CI 2.52 to 20.23), p<0.001) and middle-HDI (4.42 (1.44 to 13.56), p=0.009) countries compared with high-HDI countries, translating to 40 excess deaths per 1000 procedures performed.Conclusions: Adjusted mortality in children following emergency abdominal surgery may be as high as 7 times greater in low-HDI and middle-HDI countries compared with high-HDI countries. Effective provision of emergency essential surgery should be a key priority for global child health agendas.
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| 2. |
- Mannerberg, Annika, et al.
(författare)
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Surface guided electron FLASH radiotherapy for canine cancer patients
- 2023
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Ingår i: Medical Physics. - 0094-2405. ; 50:7, s. 4047-4054
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundDuring recent years FLASH radiotherapy (FLASH-RT) has shown promising results in radiation oncology, with the potential to spare normal tissue while maintaining the antitumor effects. The high speed of the FLASH-RT delivery increases the need for fast and precise motion monitoring to avoid underdosing the target. Surface guided radiotherapy (SGRT) uses surface imaging (SI) to render a 3D surface of the patient. SI provides real-time motion monitoring and has a large scanning field of view, covering off-isocentric positions. However, SI has so far only been used for human patients with conventional setup and treatment.PurposeThe aim of this study was to investigate the performance of SI as a motion management tool during electron FLASH-RT of canine cancer patients.MethodsTo evaluate the SI system's ability to render surfaces of fur, three fur-like blankets in white, grey, and black were used to imitate the surface of canine patients and the camera settings were optimized for each blanket. Phantom measurements using the fur blankets were carried out, simulating respiratory motion and sudden shift. Respiratory motion was simulated using the QUASAR Respiratory Motion Phantom with the fur blankets placed on the phantom platform, which moved 10 mm vertically with a simulated respiratory period of 4 s. Sudden motion was simulated with an in-house developed phantom, consisting of a platform which was moved vertically in a stepwise motion at a chosen frequency. For sudden measurements, 1, 2, 3, 4, 5, 6, 7, and 10 Hz were measured. All measurements were both carried out at the conventional source-to-surface distance (SSD) of 100 cm, and in the locally used FLASH-RT setup at SSD = 70 cm. The capability of the SI system to reproduce the simulated motion and the sampling time were evaluated. As an initial step towards clinical implementation, the feasibility of SI for surface guided FLASH-RT was evaluated for 11 canine cancer patients.ResultsThe SI camera was capable of rendering surfaces for all blankets. The deviation between simulated and measured mean peak-to-peak breathing amplitude was within 0.6 mm for all blankets. The sampling time was generally higher for the black fur than for the white and grey fur, for the measurement of both respiratory and sudden motion. The SI system could measure sudden motion within 62.5 ms and detect motion with a frequency of 10 Hz. The feasibility study of the canine patients showed that the SI system could be an important tool to ensure patient safety. By using this system we could ensure and document that 10 out of 11 canine patients had a total vector offset from the reference setup position ConclusionsWe have shown that SI can be used for surface guided FLASH-RT of canine patients. The SI system is currently not fast enough to interrupt a FLASH-RT beam while irradiating but with the short sampling time sudden motion can be detected. The beam can therefore be held just prior to irradiation, preventing treatment errors such as underdosing the target.
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| 3. |
- Olsson, Hampus, et al.
(författare)
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Simultaneous 3D T1 and B1+ mapping at 7T using MPRAGE with multiple volumes and driven equilibrium (DE)
- 2021
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Ingår i: Proceedings of the 2021 ISMRM & ISMRT Annual Meeting and Exhibition. - 1545-4428. ; 29
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Konferensbidrag (refereegranskat)abstract
- MP2RAGE has become popular for T1 mapping at 7T. Accuracy is yet improved by using a separately acquired flip angle map when creating the protocol-specific lookup table. Here, two additional volumes acquired at differing flip angles are added to an MP2RAGE sequence to obtain two separate states of driven equilibriums, effectively forming a dual flip angle protocol within the cycle. By estimating the accelerated effective relaxation, T1* from the signals, both T1 and B1+ can be solved for analytically. Thus, a multi-volume MPRAGE sequence is turned into a dedicated high-resolution T1 and flip angle-mapping protocol.
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| 4. |
- Olsson, Hampus, et al.
(författare)
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Simultaneous mapping of T1and B1+ in human brain at 7T
- 2022
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Ingår i: Magnetic Resonance in Medicine. - : Wiley. - 1522-2594 .- 0740-3194. ; 87:6, s. 2637-2649
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Tidskriftsartikel (refereegranskat)abstract
- PurposeTo map T1 and the local flip angle (B1+) in human brain using a single MP3RAGE sequence with 3 rapid acquisitions of gradient echoes (RAGEs).Theory and methodsA third RAGE with a relatively high flip angle was appended to an MP2RAGE sequence. Through curve fitting and a rational approximation for small flip angles and short TR, closed form solutions for T1 and B1+ were derived. The influence of different k-space encoding schemes on precision and whether edge enhancement artifacts could be reduced with a saturation pulse applied prior to the third RAGE were explored. Validation of T1 estimates was performed using single-slice inversion recovery (IR) and a subsequent region-of-interest–based comparison, whereas validation of B1+ was performed using a whole brain pixelwise comparison to a DREAM flip angle mapping protocol. Lastly, MP3RAGE was compared to T1-mapping by MP2RAGE with separate B1+ correction.ResultsWhole brain maps of T1 and B1+ at 1 mm isotropic resolution were obtained with MP3RAGE in 06:37 min. A linear–reverse centric–reverse centric phase-encoding order of the 3 RAGEs improved precision, and artifacts were successfully reduced with the saturation pulse. Estimations of T1 and B1+ deviated +2.5 ± 3.1% and −1.7 ± 8.6% from their respective references.ConclusionT1 and B1+ can be mapped simultaneously using MP3RAGE. The approach can be thought of as combining MP2RAGE with a dual flip angle T1-mapping protocol. Both maps can be solved for analytically and will be inherently co-registered at the high resolution associated with MPRAGE.
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