scholarly journals A Diamond-Based Dose-per-Pulse X-ray Detector for Radiation Therapy

Materials ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5203
Author(s):  
Sara Pettinato ◽  
Marco Girolami ◽  
Riccardo Olivieri ◽  
Antonella Stravato ◽  
Cristina Caruso ◽  
...  
Keyword(s):  
Detection System ◽  
Irradiation Time ◽  
Dose Range ◽  
Single Pulse ◽  
High Dose ◽  
X Ray ◽  
Care Plans ◽  
Integration Period ◽  
Integration Mode ◽  
A Charge

One of the goals of modern dynamic radiotherapy treatments is to deliver high-dose values in the shortest irradiation time possible. In such a context, fast X-ray detectors and reliable front-end readout electronics for beam diagnostics are crucial to meet the necessary quality assurance requirements of care plans. This work describes a diamond-based detection system able to acquire and process the dose delivered by every single pulse sourced by a linear accelerator (LINAC) generating 6-MV X-ray beams. The proposed system is able to measure the intensity of X-ray pulses in a limited integration period around each pulse, thus reducing the inaccuracy induced by unnecessarily long acquisition times. Detector sensitivity under 6-MV X-photons in the 0.1–10 Gy dose range was measured to be 302.2 nC/Gy at a bias voltage of 10 V. Pulse-by-pulse measurements returned a charge-per-pulse value of 84.68 pC, in excellent agreement with the value estimated (but not directly measured) with a commercial electrometer operating in a continuous integration mode. Significantly, by intrinsically holding the acquired signal, the proposed system enables signal processing even in the millisecond period between two consecutive pulses, thus allowing for effective real-time dose-per-pulse monitoring.

Use of a CCD-Based Area Detection System on a Fibre Diffractometer

1994 ◽  
Vol 38 ◽  
pp. 503-510 ◽  
Author(s):  
S. Hanna ◽  
A.H. Windle
Keyword(s):  
Detection System ◽  
Single Point ◽  
Video Camera ◽  
Reciprocal Space ◽  
Charge Coupled Device ◽  
X Ray ◽  
Complete Section ◽  
Ewald Sphere ◽  
Pros And Cons ◽  
A Charge

Abstract We describe a new X-ray fibre diffractometer, consisting of a commercial X-ray sensitive video camera coupled to a conventional 3-circle goniometer in place of a more traditional single-point detector. The active element of the video camera is a charge-coupled device (CCD). Diffraction images, obtained at various goniometer settings, are transformed into reciprocal space, and combined to give a complete section through the origin and parallel to the symmetry axis of cyiindrically averaged reciprocal space. A greater density of measurements is needed in the vicinity of the reciprocal fibre axis in order to avoid information loss due to the curvature of the Ewald sphere. The pros and cons of using CCD's as X-ray detectors are discussed and sample results from polymer fibres are shown.

scholarly journals Radiochromic Films for the Two-Dimensional Dose Distribution Assessment

2021 ◽  
Vol 11 (5) ◽  
pp. 2132
Author(s):  
Pierluigi Casolaro
Keyword(s):  
Detection System ◽  
Dose Range ◽  
Radiation Detection ◽  
Short Review ◽  
Medical Diagnostics ◽  
Radiochromic Film ◽  
High Dose ◽  
Two Dimensional ◽  
Dose Verification ◽  
Radiochromic Films

Radiochromic films are mainly used for two-dimensional dose verification in photon, electron, and proton therapy treatments. Moreover, the radiochromic film types available today allow their use in a wide dose range, corresponding to applications from low-medical diagnostics to high-dose beam profile measurements in charged particle medical accelerators. An in-depth knowledge of the characteristics of radiochromic films, of their operating principles, and of the dose reading techniques is of paramount importance to exploit all the features of this interesting and versatile radiation detection system. This short review focuses on these main aspects by considering the most recent works on the subject.

scholarly journals Thermoluminescence Properties of Bioglass for Radiation Dosimetry

2021 ◽  
Author(s):  
Huda A. Alazab ◽  
N.Y. Abdou ◽  
H. A. Saudi ◽  
wesam Abd-Allah
Keyword(s):  
Thermal Analysis ◽  
Differential Thermal Analysis ◽  
Radiation Dosimetry ◽  
Dose Range ◽  
Glow Peak ◽  
Gamma Dose ◽  
High Dose ◽  
X Ray Diffraction ◽  
X Ray ◽  
High Gamma

Abstract The thermoluminescence technique was employed to study bioglass matrices prepared using the traditional technique of glass making. The synthesized bioglass matrices were investigated using X-ray diffraction (XRD), and differential thermal analysis (DTA) has been studied. The highest thermoluminescent intensity was found for the bioglass matric of 26.91% CaO, 46.134% SiO2, 2.60% P2O5, 24.34%Na2O (mol%), with only one glow peak at 460 k. The TL response illustrations linearity in high gamma dose range from 25 to 1000 Gy. This new bioglass matric might become useful in high-dose fields for dosimetry.

scholarly journals Clinical results of proton beam therapy for twenty older patients with esophageal cancer

2015 ◽  
Vol 49 (4) ◽  
pp. 371-378 ◽  
Author(s):  
Takashi Ono ◽  
Tatsuya Nakamura ◽  
Yusuke Azami ◽  
Hisashi Yamaguchi ◽  
Yuichiro Hayashi ◽  
...  
Keyword(s):  
Esophageal Cancer ◽  
Proton Beam ◽  
Older Patients ◽  
Dose Range ◽  
Proton Beam Therapy ◽  
Clinical Results ◽  
Local Control Rate ◽  
High Dose ◽  
X Ray ◽  
Node Metastases

Abstract Background. In an aging society, increasing number of older patients are diagnosed with esophageal cancer. The purpose of this study was to assess the clinical efficacy and safety of proton beam therapy for older patients with esophageal cancer. Patients and methods. Older patients (age: ≥ 65 years) newly diagnosed with esophageal cancer between January 2009 and June 2013 were enrolled in this study. All patients underwent either proton beam therapy alone or proton beam therapy with initial X-ray irradiation. Toxicities were evaluated using the Common Terminology Criteria for Adverse Events version 4.0. Results. Twenty patients were eligible for this study and all completed the treatment. The median age was 78 years (range: 65–89 years) and the median follow-up time was 26.5 months (range: 6–62 months). Seven patients had lymph node metastases and 10 had stage II/III cancer. The median dose of proton beam therapy was 72.6 Gy relative biological dose effectiveness (RBE) (range: 66–74.8 Gy [RBE]) for proton beam therapy alone and 33 Gy (RBE) (range: 30.8–39.6 Gy [RBE]; total dose range: 66.8–75.6 Gy [RBE]) for proton beam therapy with initial X-ray irradiation. The 2-year overall survival rate was 81.8% (95% confidence interval [CI]: 62.4%–100%), and the 2-year local control rate was 89.4% (95% CI: 75.5%–100%). Grade 2 or 3 toxicities occurred in some cases; however, no grade 4 or 5 toxicity was observed. Conclusions. High-dose (66–75.6 Gy [RBE]) proton beam therapy without chemotherapy was an efficacious and safe treatment for older patients with esophageal cancer.

Structure and Electrical Properties of Yttria Stabilized Zirconia by Iron Ion Implantation

1993 ◽  
Vol 316 ◽  
Author(s):  
Wang Guomei ◽  
Qu Zuyuan
Keyword(s):  
Electrical Properties ◽  
Photoelectron Spectroscopy ◽  
Yttria Stabilized Zirconia ◽  
High Dose ◽  
X Ray Diffraction ◽  
Stabilized Zirconia ◽  
X Ray ◽  
A Charge ◽  
Fe Ions ◽  
Post Implantation

ABSTRACTFe ions were implanted into yttria stabilized zirconia with doses of 5×1015 -2×1017 ions/cm2 at an energy of 140 KeV. The effects of Fe-implanted zirconia and post-implantation thermal annealing on electrical properties and structure of an implanted layer were studies by electric measurement, X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). It was found that the resistivity for the as-implanted sample decreased greatly with increasing ion dose, and at high dose the resistivity decreasing gradually. After annealing at 1200°C in N2 environment, the resistivity relative to that for the as-implanted sample had clearly marked decreases. Results of the XRD and XPS measurements showed that the implanted Fe ion was mainly in a charge state of Fe2+ and the sections of Fe2+ were incorporated into the ZrO2 lattice, forming a FeZrO3 compound. Finally, the conductivity mechanisms were discussed briefly.

Studies of metaphase chromosomes in the scanning transmission x-ray microscope: Image fidelity, radiation damage and specimen preparation

1992 ◽  
Vol 50 (2) ◽  
pp. 1038-1039
Author(s):  
Shawn Williams ◽  
Xiaodong Zhang ◽  
Susan Lamm ◽  
Jack Van’t Hof
Keyword(s):  
Visible Light ◽  
Radiation Damage ◽  
Cross Section ◽  
Imaging Techniques ◽  
Dose Range ◽  
Specimen Preparation ◽  
X Rays ◽  
Metaphase Chromosomes ◽  
X Ray ◽  
Scanning Transmission

The Scanning Transmission X-ray Microscope (STXM) is well suited for investigating metaphase chromosome structure. The absorption cross-section of soft x-rays having energies between the carbon and oxygen K edges (284 - 531 eV) is 6 - 9.5 times greater for organic specimens than for water, which permits one to examine unstained, wet biological specimens with resolution superior to that attainable using visible light. The attenuation length of the x-rays is suitable for imaging micron thick specimens without sectioning. This large difference in cross-section yields good specimen contrast, so that fewer soft x-rays than electrons are required to image wet biological specimens at a given resolution. But most imaging techniques delivering better resolution than visible light produce radiation damage. Soft x-rays are known to be very effective in damaging biological specimens. The STXM is constructed to minimize specimen dose, but it is important to measure the actual damage induced as a function of dose in order to determine the dose range within which radiation damage does not compromise image quality.

Reconstruction of Chitin-Protein Complexes Using Correlation Averaging Methods: Ovipositor of the Ichneumon Fly Megarhyssa

1980 ◽  
Vol 38 ◽  
pp. 38-39
Author(s):  
L. T. Germinario ◽  
J. Blackwell ◽  
J. Frank
Keyword(s):  
Protein Complexes ◽  
Hexagonal Lattice ◽  
Uranyl Acetate ◽  
Optical Diffraction ◽  
Insect Cuticle ◽  
High Dose ◽  
Wide Angle ◽  
X Ray ◽  
Averaging Methods ◽  
Digital Correlation

This report describes the use of digital correlation and averaging methods 1,2 for the reconstruction of high dose electron micrographs of the chitin-protein complex from Megarhyssa ovipositor. Electron microscopy of uranyl acetate stained insect cuticle has demonstrated a hexagonal array of unstained chitin monofibrils, 2.4−3.0 nm in diameter, in a stained protein matrix3,4. Optical diffraction Indicated a hexagonal lattice with a = 5.1-8.3 nm3 A particularly well ordered complex is found in the ovipositor of the ichneumon fly Megarhyssa: the small angle x-ray data gives a = 7.25 nm, and the wide angle pattern shows that the protein consists of subunits arranged in a 61 helix, with an axial repeat of 3.06 nm5.

A Modular X-Ray Detection System

2019 ◽  
Author(s):  
Robert Viola ◽  
Keyword(s):  
Detection System ◽  
X Ray

scholarly journals Skin regeneration is accelerated by a lower dose of multipotent mesenchymal stromal/stem cells—a paradigm change

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Gertraud Eylert ◽  
Reinhard Dolp ◽  
Alexandra Parousis ◽  
Richard Cheng ◽  
Christopher Auger ◽  
...  
Keyword(s):  
Stem Cells ◽  
Wound Healing ◽  
Low Dose ◽  
Dose Range ◽  
High Dose ◽  
Full Thickness ◽  
Burn Wound ◽  
Dermal Regeneration Template ◽  
Yorkshire Pigs ◽  
Stromal Stem Cells

Abstract Background Multipotent mesenchymal stromal/stem cell (MSC) therapy is under investigation in promising (pre-)clinical trials for wound healing, which is crucial for survival; however, the optimal cell dosage remains unknown. The aim was to investigate the efficacy of different low-to-high MSC dosages incorporated in a biodegradable collagen-based dermal regeneration template (DRT) Integra®. Methods We conducted a porcine study (N = 8 Yorkshire pigs) and seeded between 200 and 2,000,000 cells/cm2 of umbilical cord mesenchymal stromal/stem cells on the DRT and grafted it onto full-thickness burn excised wounds. On day 28, comparisons were made between the different low-to-high cell dose groups, the acellular control, a burn wound, and healthy skin. Result We found that the low dose range between 200 and 40,000 cells/cm2 regenerates the full-thickness burn excised wounds most efficaciously, followed by the middle dose range of 200,000–400,000 cells/cm2 and a high dose of 2,000,000 cells/cm2. The low dose of 40,000 cells/cm2 accelerated reepithelialization, reduced scarring, regenerated epidermal thickness superiorly, enhanced neovascularization, reduced fibrosis, and reduced type 1 and type 2 macrophages compared to other cell dosages and the acellular control. Conclusion This regenerative cell therapy study using MSCs shows efficacy toward a low dose, which changes the paradigm that more cells lead to better wound healing outcome.

scholarly journals 4-Methylumbelliferone administration enhances radiosensitivity of human fibrosarcoma by intercellular communication

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ryo Saga ◽  
Yusuke Matsuya ◽  
Rei Takahashi ◽  
Kazuki Hasegawa ◽  
Hiroyuki Date ◽  
...  
Keyword(s):  
Intercellular Communication ◽  
Dose Range ◽  
Synthesis Inhibitor ◽  
X Ray ◽  
Tumour Control ◽  
Synergetic Effects ◽  
Fibrosarcoma Cells ◽  
Oxidative Stress Level ◽  
Human Fibrosarcoma Cells

AbstractHyaluronan synthesis inhibitor 4-methylumbelliferone (4-MU) is a candidate of radiosensitizers which enables both anti-tumour and anti-metastasis effects in X-ray therapy. The curative effects under such 4-MU administration have been investigated in vitro; however, the radiosensitizing mechanisms remain unclear. Here, we investigated the radiosensitizing effects under 4-MU treatment from cell experiments and model estimations. We generated experimental surviving fractions of human fibrosarcoma cells (HT1080) after 4-MU treatment combined with X-ray irradiation. Meanwhilst, we also modelled the pharmacological effects of 4-MU treatment and theoretically analyzed the synergetic effects between 4-MU treatment and X-ray irradiation. The results show that the enhancement of cell killing by 4-MU treatment is the greatest in the intermediate dose range of around 4 Gy, which can be reproduced by considering intercellular communication (so called non-targeted effects) through the model analysis. As supposed to be the involvement of intercellular communication in radiosensitization, the oxidative stress level associated with reactive oxygen species (ROS), which leads to DNA damage induction, is significantly higher by the combination of 4-MU treatment and irradiation than only by X-ray irradiation, and the radiosensitization by 4-MU can be suppressed by the ROS inhibitors. These findings suggest that the synergetic effects between 4-MU treatment and irradiation are predominantly attributed to intercellular communication and provide more efficient tumour control than conventional X-ray therapy.

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