| 1. |
- Bäck, Sven, et al.
(författare)
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Ferrous sulphate gel dosimetry and MRI for proton beam dose measurements
- 1999
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Ingår i: Physics in Medicine and Biology. - : IOP Publishing. - 1361-6560 .- 0031-9155. ; 44:8, s. 1983-1996
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Tidskriftsartikel (refereegranskat)abstract
- Ferrous sulphate gel dosimetry has the potential for measurement of absorbed dose distributions in proton therapy. The chemical properties of the gel are altered according to the radiation dose and these changes can be evaluated in three dimensions using MRI. The purpose of this work was to investigate the properties of a ferrous gel used with clinical proton beams. The gel was irradiated with both monoenergetic and range-modulated proton beams. It was then evaluated using MRI. The depth dose by means of the 1/T1 distribution was studied and compared with data from a plane-parallel plate ionization chamber. 1/T1 was shown to be proportional to the dose at a mean proton energy of approximately 90 MeV. The dose response was no different from that obtained using photon beams. However, on normalization at the entrance, the relative 1/T1 at the Bragg peak was 15-20% lower than the corresponding ionization chamber data for the monoenergetic proton beam. Better agreement was found for the modulated beam, but with significant differences close to the distal edge of the 1/T1 distribution. The change in sensitivity with depth was explained by means of a linear energy transfer dependence. This property was further studied using Monte Carlo methods.
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| 9. |
- Andersen, C. E., et al.
(författare)
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Medical proton dosimetry using radioluminescence from aluminium oxide crystals attached to optical-fiber cables
- 2007
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576 .- 0167-5087. ; 580:1, s. 466-468
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Tidskriftsartikel (refereegranskat)abstract
- The prime objective of this study is to investigate if radioluminescence (RL) from carbon-doped aluminum oxide (Al2O3:C) crystals potentially can be used for absorbed dose-rate measurements during proton radiotherapy. The RL from two separate (2 mg) Al2O3:C crystals attached to optical-fiber cables were recorded during irradiations in water in a 175 MeV clinical proton beam. The RL response for low-LET protons in the plateau region of the Bragg curve was found to closely resemble that observed for a clinical 6 MV X-ray beam. An identical response was found in the Bragg peak (where the dose-averaged LET is about 4 keV/mu m) for absorbed doses less than 0.3 Gy. For doses in the range of 0.3-3Gy, we observed a significant decrease in luminescence efficiency with LET. At 3 Gy, the luminescence efficiency was about 60% in the Bragg-peak region. The study implies that the RL-signal from Al2O3:C could potentially be suitable for medical proton dosimetry in the 0-0.3 Gy range even without any LET-dependent correction factors.
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| 21. |
- Larsson, Helen, 1982, et al.
(författare)
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Grade of eosinophilia versus symptoms in patients with dysphagia and esophageal eosinophilia.
- 2016
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Ingår i: Diseases of the esophagus. - : Oxford University Press (OUP). - 1120-8694. ; 29:8, s. 971-976
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to assess whether the symptom severity and health-related quality of life (HRQL) of patients with dysphagia and esophageal eosinophilia correlate with disease activity as expressed by the number of eosinophils in the esophageal mucosa. This study included newly diagnosed (n = 58) or relapsed patients (n = 7), where 40% were diagnosed in connection with esophageal bolus impaction. The mean age was 45 years (19-88), and 74% were men. Symptoms and HRQL were recorded using the Watson Dysphagia Scale (WDS), the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire - Oesophageal Module 18 and the Short Form-36 Questionnaire. Histological samples gathered from the proximal and distal esophageal mucosa were stained using both hematoxylin and eosin (HE) and an immunohistochemical (IHC) technique against 'Eosinophil Major Basic Protein,' and the peak number of eosinophils per high-power field was assessed. More eosinophils were detected after IHC staining than HE staining (P < 0.001). No correlation was found between symptoms or the HRQL and the number of eosinophils. However, higher numbers of eosinophils at the proximal esophagus were found in patients with concomitant bolus impaction (IHC P < 0.05 and HE P < 0.05) and could serve as a risk marker.
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| 23. |
- Lennernäs, Bo, 1963, et al.
(författare)
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Silicon diodes as detectors for backscatter radiation in photon fields.
- 2001
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Ingår i: Oncology reports. - : Spandidos Publications. - 1021-335X .- 1791-2431. ; 8:1, s. 181-3
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Tidskriftsartikel (refereegranskat)abstract
- We investigated the use of unencapsulated silicon semiconductor detectors for backscatter radiation detection. The results were compared with Monte Carlo (MC) calculations modelling the experimental set-up. A special diode was manufactured, which was designed so that it allowed the positioning of different materials in close contact with the detector surface. Polymethylmethacrylate (PMMA), Pb, Ti and Fe (stainless steel) were used as backscatter materials. The diode signal was measured by integrating the current when irradiating the diode with an equal photon fluence obtained from a medical Co-60 source. When compared to the signal with PMMA as backscatter material the increase in signal was 21%, 27% and 73% for Ti, Fe and Pb, respectively. This is in reasonable agreement with the MC calculations, when taking the effective measurement depth in the Si diode detector into account.
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- Norder Grusell, E., et al.
(författare)
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Bacterial flora of the human oral cavity, and the upper and lower esophagus.
- 2013
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Ingår i: Diseases of the esophagus. - : Oxford University Press (OUP). - 1120-8694. ; 26:1, s. 84-90
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Tidskriftsartikel (refereegranskat)abstract
- This reference study aims to survey the bacterial flora of the healthy lower human esophagus and to compare it with that of the upper esophagus and oral mucosa. The use of biopsies, in addition to brush samples, allows inclusion of not only transient bacteria present on the surface but also bacteria residing in the epithelia, and the yield of the two methods can be compared. Forty patients scheduled for surgery for reasons with no known influence on esophageal flora and with no symptoms or endoscopic signs of esophageal disease were included. Samples were collected from the oral, upper esophageal, and lower esophageal mucosa using sealed brushes and biopsy forceps. Colonies cultivated on agar plates were classified and semiquantified. Twenty-three different bacterial species were identified, with similar strains present at the three sites. The most common group of bacteria was viridans streptococci, with an occurrence rate in brush samples and biopsies of 98% and 95%, respectively. The median number of species occurring in the oral cavity, upper esophagus, and lower esophagus was between 3 and 4 (range 0-7). The total number of species in the oral cavity was significantly higher when compared with either level in the esophagus, while the yields obtained by brush and biopsy sampling were highly correlated. Hence, the normal human esophagus is colonized with a resident bacterial flora of its own, which has similarities to that of the oral mucosa. There are diverse species that make up this flora, although in relatively low amounts. The most frequent inhabitants of the esophagus are streptococci, with an occurrence rate in brush samples and biopsies of 95-98%. Comparative studies of patients with eosinophilic esophagitis and gastroesophageal reflux disease are warranted.
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- Norder Grusell, E., et al.
(författare)
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The cultivable bacterial flora of the esophagus in subjects with esophagitis
- 2018
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Ingår i: Scandinavian Journal of Gastroenterology. - : Informa UK Limited. - 0036-5521 .- 1502-7708. ; 53:6, s. 650-656
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Tidskriftsartikel (refereegranskat)abstract
- Background: The healthy human esophagus is colonized by bacteria similar to that of the oral mucosa. However, little is known about the microbiome of the esophagus in esophagitis or the possible role of bacteria in the inflammatory response.Aim: To survey bacterial diversity and compare the microbiome of the esophagus in subjects with gastro-esophageal reflux disease (GERD) and eosinophilic esophagitis (EoE).Material and methods: Seventeen subjects diagnosed with GERD and 10 with EoE underwent endoscopic examination with brush sampling and biopsies from the oral cavity, upper and lower esophagus. The samples were cultivated on agar plates, and bacterial growth was identified to the genus or species level and semi-quantified.Results: Significantly higher numbers of bacterial groups or species were found in specimens from the lower esophagus in subjects with EoE compared to subjects with GERD (median 4 (range 1-7) vs. 2 (range 0-6), p<.0014). Sixteen vs. 14 different bacterial groups or species were found in subjects with GERD and EoE, respectively, mostly in sparse or very sparse amounts. Alfa-streptococci (viridans streptococci) were the most common bacteria in both groups. Streptococci were present in all of the EoE-subjects but only in approximately 75% in lower esophagus of the GERD-subjects, regardless of the sampling method.Conclusion: Subjects with GERD had significantly less bacterial diversity in both oral and esophageal samples than EoE-subjects. Whether this discrepancy might be explained by an effect on the protective mucosal biofilm by the acidic content of the reflux in subjects with GERD remains unclear.
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| 29. |
- Plate, John, 1993, et al.
(författare)
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Expression of inducible nitric oxide synthase, nitrotyrosine, eosinophilic peroxidase, eotaxin-3, and galectin-3 in patients with gastroesophageal reflux disease, eosinophilic esophagitis, and in healthy controls: a semiquantitative image analysis of 3,3′-diaminobenzidine-stained esophageal biopsies
- 2024
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Ingår i: DISEASES OF THE ESOPHAGUS. - 1120-8694 .- 1442-2050.
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Tidskriftsartikel (refereegranskat)abstract
- Eosinophilic esophagitis (EoE) and gastroesophageal reflux disease (GERD) share many histopathological features; therefore, markers for differentiation are of diagnostic interest and may add to the understanding of the underlying mechanisms. The nitrergic system is upregulated in GERD and probably also in EoE. Esophageal biopsies of patients with EoE (n = 20), GERD (n = 20), and healthy volunteers (HVs) (n = 15) were exposed to antibodies against inducible nitric oxide synthase (iNOS), nitrotyrosine, eosinophilic peroxidase, eotaxin-3, and galectin-3. The stained object glasses were randomized, digitized, and blindly analyzed regarding the expression of DAB (3,3 '-diaminobenzidine) by a protocol developed in QuPath software. A statistically significant overexpression of iNOS was observed in patients with any of the two inflammatory diseases compared with that in HVs. Eotaxin-3 could differentiate HVs versus inflammatory states. Gastroesophageal reflux patients displayed the highest levels of nitrotyrosine. Neither iNOS nor nitrotyrosine alone were able to differentiate between the two diseases. For that purpose, eosinophil peroxidase was a better candidate, as the mean levels increased stepwise from HVs via GERD to EoE. iNOS and nitrotyrosine are significantly overexpressed in patients with EoE and GERD compared with healthy controls, but only eosinophil peroxidase could differentiate the two types of esophagitis. The implications of the finding of the highest levels of nitrotyrosine among gastroesophageal reflux patients are discussed.
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| 31. |
- Sanchez-Crespo, A., et al.
(författare)
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Proton therapy beam dosimetry with silicon CMOS image sensors
- 2004
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 525:02-jan, s. 289-293
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Tidskriftsartikel (refereegranskat)abstract
- A 16 mm(2) CMOS Image Sensor with more than 100 000 pixels and with a standard video output was irradiated with 48, 95 and 180 MeV protons. Proton-induced nuclear reactions in silicon were detected as bright spots or tracks in the images. The angular and energy-dependent response of the detector were studied. The application to proton dosimetry is discussed.
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| 32. |
- Sipos, A., et al.
(författare)
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Visualization of neutron and proton induced particle production in a CMOS image sensor
- 2003
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - 0168-9002 .- 1872-9576. ; 509:03-jan, s. 328-332
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Tidskriftsartikel (refereegranskat)abstract
- A commercially available off the shelf CMOS Image Sensor was irradiated with neutron and proton beams. The Image Sensor is equipped with standard video output. The data were collected on VHS videotapes and analyzed off-line after digitization. The camera chip with 110 000 pixels each having 12 x 12 mum(2) size, shows the nuclear reactions occurring in the sensitive layer as bright spots or tracks. Several applications are suggested based on the inexpensive CMOS Image Sensor.
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| 33. |
- Vatnitsky, S, et al.
(författare)
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Proton dosimetry intercomparison based on the ICRU report 59 protocol
- 1999
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Ingår i: Radiotherapy and Oncology. - 0167-8140 .- 1879-0887. ; 51:3, s. 273-279
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND AND PURPOSE:A new protocol for calibration of proton beams was established by the ICRU in report 59 on proton dosimetry. In this paper we report the results of an international proton dosimetry intercomparison, which was held at Loma Linda University Medical Center. The goals of the intercomparison were, first, to estimate the level of consistency in absorbed dose delivered to patients if proton beams at various clinics were calibrated with the new ICRU protocol, and second, to evaluate the differences in absorbed dose determination due to differences in 60Co-based ionization chamber calibration factors.MATERIALS AND METHODS:Eleven institutions participated in the intercomparison. Measurements were performed in a polystyrene phantom at a depth of 10.27 cm water equivalent thickness in a 6-cm modulated proton beam with an accelerator energy of 155 MeV and an incident energy of approximately 135 MeV. Most participants used ionization chambers calibrated in terms of exposure or air kerma. Four ionization chambers had 60Co-based calibration in terms of absorbed dose-to-water. Two chambers were calibrated in a 60Co beam at the NIST both in terms of air kerma and absorbed dose-to-water to provide a comparison of ionization chambers with different calibrations.RESULTS:The intercomparison showed that use of the ICRU report 59 protocol would result in absorbed doses being delivered to patients at their participating institutions to within +/-0.9% (one standard deviation). The maximum difference between doses determined by the participants was found to be 2.9%. Differences between proton doses derived from the measurements with ionization chambers with N(K)-, or N(W) - calibration type depended on chamber type.CONCLUSIONS:Using ionization chambers with 60Co calibration factors traceable to standard laboratories and the ICRU report 59 protocol, a distribution of stated proton absorbed dose is achieved with a difference less than 3%. The ICRU protocol should be adopted for clinical proton beam calibration. A comparison of proton doses derived from measurements with different chambers indicates that the difference in results cannot be explained only by differences in 60Co calibration factors.
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