Development of an external Faraday cup for beam current measurements

International Nuclear Information System (INIS)

Kim, Kye-Ryung; Jung, Myung-Hwan; Ra, Se-Jin; Lee, Seok-Ki

2010-01-01

In general, beam current measurements are very important for many kinds of experiments using highly energetic particle beams at accelerators, such as cyclotrons, linacs, etc. The Faraday cup is known to be one of the most popular beam current measurement tools. We developed an external Faraday cup to measure the beam current at a dedicated beam line for low-flux experiments installed at the MC-50 cyclotron of Korea Institute of Radiological and Medical Sciences (KIRAMS). It was designed for external beam current measurements and is composed of a vacuum chamber, an entrance window, a collimator, a electrostatic suppressor ring, and a cup. The window is made of 75-um-thick Kapton film, and the diameter of the collimator is 10 mm or 20 mm. The ring and the cup has 5-cm inner diameters, and the thickness of the bottom of the cup is 2 cm, which is enough to absorb the total proton energy up to 45 MeV. Using this external Faraday cup, we measured the beam current from the cyclotron, and we compared measured flux to the results from film dosimetry using GAF films.

Comparison of radioimmunotherapy and external beam radiotherapy in colon cancer xenografts

International Nuclear Information System (INIS)

Buras, R.R.; Wong, J.F.C.; Kuhn, J.A.; Beatty, B.G.; Williams, L.E.; Beatty, J.D.; Wanek, P.M.

1993-01-01

Radioimmunotherapy and external beam radiotherapy were compared in a nude mouse human colon cancer model. Radioimmunotherapy was delivered by intraperitoneal injection of 90 Y-labeled anticarcinoembryonic antigen monoclonal antibody (anti-CEA MAB). Single fraction external beam radiotherapy was delivered using a 60 Co teletherapy unit. Control groups received saline, unlabeled anit-CEA monoclonal antibody and labeled nonspecific monoclonal antibody. Tumor growth suppression was expressed as delay to reach 2g compared to saline controls. Unlabeled anti-CEA monoclonal antibody and labeled nonspecific monoclonal antibody had no effect. External beam radiotherapy of 300, 600, 1000 and 2000 cGy produced growth delays of 3, 12, 17, and 22 days, respectively. Radioimmunotherapy with 120 μCi, 175 μCi, and 225 μCi resulted in growth delays of 20, 34, and 36 days. Estimated absorbed tumor dose was 1750 cGy in the 120 μCi group. Similar comparisons were done with the more radioresistant WiDr human colon carcinoma cell line. External beam radiotherapy doses of 400, 800, 1200, and 1600 cGy resulted in growth delays of 6, 21, 36 and 48 days, respectively. Radioimmunotherapy of 120 μCi and 175 μCi resulted in growth delays of 9 and 19 days, respectively. The 120 μCi dose delivered an estimated absorbed tumor dose of 1080 cGy to WiDr tumors. In summary, for the radiosensitive LS174T line, radioimmunotherapy produced biologic effects that were comparable to a similar dose of single fraction external beam radiotherapy. For the more radioresistant WiDr tumor, radioimmunotherapy produced a biologic effect which was less than a similar dose of single fraction external beam radiotherapy. These studies suggest that a tumor's response to radioimmunotherapy relative to that of external beam radiotherapy is, in part, dependent on tumor radiosensitivity and repair capacity. 23 refs., 5 figs. 4 tabs

Measurement of M2-Curve for Asymmetric Beams by Self-Referencing Interferometer Wavefront Sensor

Directory of Open Access Journals (Sweden)

Yongzhao Du

2016-11-01

Full Text Available For asymmetric laser beams, the values of beam quality factor M x 2 and M y 2 are inconsistent if one selects a different coordinate system or measures beam quality with different experimental conditionals, even when analyzing the same beam. To overcome this non-uniqueness, a new beam quality characterization method named as M2-curve is developed. The M2-curve not only contains the beam quality factor M x 2 and M y 2 in the x-direction and y-direction, respectively; but also introduces a curve of M x α 2 versus rotation angle α of coordinate axis. Moreover, we also present a real-time measurement method to demonstrate beam propagation factor M2-curve with a modified self-referencing Mach-Zehnder interferometer based-wavefront sensor (henceforth SRI-WFS. The feasibility of the proposed method is demonstrated with the theoretical analysis and experiment in multimode beams. The experimental results showed that the proposed measurement method is simple, fast, and a single-shot measurement procedure without movable parts.

Composite beam analysis linear analysis of naturally curved and twisted anisotropic beams

Science.gov (United States)

Borri, Marco; Ghiringhelli, Gian L.; Merlini, Teodoro

1992-05-01

The aim of this report is to present a consistent theory for the deformation of a naturally curved and twisted anisotropic beam. The proposed formulation naturally extends the classical Saint-Venant approach to the case of curved and twisted anisotropic beams. The mathematical model developed under the assumption of span-wise uniform cross-section, curvature and twist, can take into account any kind of elastic coupling due to the material properties and the curved geometry. The consistency of the presented math-model and its generality about the cross-sectional shape, make it a useful tool even in a preliminary design optimization context such as the aeroelastic tailoring of helicopter rotor blades. The advantage of the present procedure is that it only requires a two-dimensional discretization; thus, very detailed analyses can be performed and interlaminar stresses between laminae can be evaluated. Such analyses would be extremely time consuming if performed with standard finite element codes: that prevents their recursive use as for example when optimizing a beam design. Moreover, as a byproduct of the proposed formulation, one obtains the constitutive law of the cross-section in terms of stress resultant and moment and their conjugate strain measures. This constitutive law takes into account any kind of elastic couplings, e.g., torsion-tension, tension-shear, bending-shear, and constitutes a fundamental input in aeroelastic analyses of helicopter blades. Four simple examples are given in order to show the principal features of the method.

The development of a curved beam element model applied to finite elements method

International Nuclear Information System (INIS)

Bento Filho, A.

1980-01-01

A procedure for the evaluation of the stiffness matrix for a thick curved beam element is developed, by means of the minimum potential energy principle, applied to finite elements. The displacement field is prescribed through polynomial expansions, and the interpolation model is determined by comparison of results obtained by the use of a sample of different expansions. As a limiting case of the curved beam, three cases of straight beams, with different dimensional ratios are analised, employing the approach proposed. Finally, an interpolation model is proposed and applied to a curved beam with great curvature. Desplacements and internal stresses are determined and the results are compared with those found in the literature. (Author) [pt

Minimal requirements for quality controls in radiotherapy with external beams

International Nuclear Information System (INIS)

1999-01-01

Physical dosimetric guidelines have been developed by the Italian National Institute of Health study group on quality assurance in radiotherapy to define protocols for quality controls in external beam radiotherapy. While the document does not determine strict rules or firm recommendations, it suggests minimal requirements for quality controls necessary to guarantee an adequate degree of accuracy in external beam radiotherapy [it

External beam radiotherapy for unresectable pancreatic cancer

Energy Technology Data Exchange (ETDEWEB)

Kagami, Yoshikazu; Nishio, Masamichi; Narimatsu, Naoto; Ogawa, Hajime; Betsuyaku, Takashi; Hirata, Kouji; Ikeda, Shigeyuki (Sapporo National Hospital (Japan). Hokkaido Cancer Center)

1992-04-01

Between 1980 to 1989, 24 patients with unresectable pancreatic cancer (10 with localized tumor alone and 14 with distant metastases) have been treated with external beam radiation at Sapporo National Hospital, Hokkaido Cancer Center. Response rate of pancreatic tumor treated with external beam radiation was 33.3% (7/21) with no complete response. Median survival time of the patients with localized tumor was 10 months and that of the patients with distant metastases was 3 months. Relief of pain occurred in 92.9% (12/13) of patients having pain due to pancreatic tumor and in 75% (3/4) of patients having pain due to bone metastases. Major complication was gastric ulcer which developed in 5 patients of 21 patients given stomach irradiation. We concluded that unresectable pancreatic cancer would be frequently indicated for radiotherapy. (author).

Development and Commissioning of an External Beam Facility in the Union College Ion Beam Analysis Laboratory

Science.gov (United States)

Yoskowitz, Joshua; Clark, Morgan; Labrake, Scott; Vineyard, Michael

2015-10-01

We have developed an external beam facility for the 1.1-MV tandem Pelletron accelerator in the Union College Ion Beam Analysis Laboratory. The beam is extracted from an aluminum pipe through a 1 / 4 ' ' diameter window with a 7.5- μm thick Kapton foil. This external beam facility allows us to perform ion beam analysis on samples that cannot be put under vacuum, including wet samples and samples too large to fit into the scattering chamber. We have commissioned the new facility by performing proton induced X-ray emission (PIXE) analysis of several samples of environmental interest. These include samples of artificial turf, running tracks, and a human tooth with an amalgam filling. A 1.7-MeV external proton beam was incident on the samples positioned 2 cm from the window. The resulting X-rays were measured using a silicon drift detector and were analyzed using GUPIX software to determine the concentrations of elements in the samples. The results on the human tooth indicate that while significant concentrations of Hg, Ag, and Sn are present in the amalgam filling, only trace amounts of Hg appear to have leached into the tooth. The artificial turf and running tracks show rather large concentrations of a broad range of elements and trace amounts of Pb in the turf infill.

Historical Cost Curves for Hydrogen Masers and Cesium Beam Frequency and Timing Standards

Science.gov (United States)

Remer, D. S.; Moore, R. C.

1985-01-01

Historical cost curves were developed for hydrogen masers and cesium beam standards used for frequency and timing calibration in the Deep Space Network. These curves may be used to calculate the cost of future hydrogen masers or cesium beam standards in either future or current dollars. The cesium beam standards are decreasing in cost by about 2.3% per year since 1966, and hydrogen masers are decreasing by about 0.8% per year since 1978 relative to the National Aeronautics and Space Administration inflation index.

Isogeometric analysis of free-form Timoshenko curved beams including the nonlinear effects of large deformations

Science.gov (United States)

Hosseini, Seyed Farhad; Hashemian, Ali; Moetakef-Imani, Behnam; Hadidimoud, Saied

2018-03-01

In the present paper, the isogeometric analysis (IGA) of free-form planar curved beams is formulated based on the nonlinear Timoshenko beam theory to investigate the large deformation of beams with variable curvature. Based on the isoparametric concept, the shape functions of the field variables (displacement and rotation) in a finite element analysis are considered to be the same as the non-uniform rational basis spline (NURBS) basis functions defining the geometry. The validity of the presented formulation is tested in five case studies covering a wide range of engineering curved structures including from straight and constant curvature to variable curvature beams. The nonlinear deformation results obtained by the presented method are compared to well-established benchmark examples and also compared to the results of linear and nonlinear finite element analyses. As the nonlinear load-deflection behavior of Timoshenko beams is the main topic of this article, the results strongly show the applicability of the IGA method to the large deformation analysis of free-form curved beams. Finally, it is interesting to notice that, until very recently, the large deformations analysis of free-form Timoshenko curved beams has not been considered in IGA by researchers.

Acoustic energy harvesting by piezoelectric curved beams in the cavity of a sonic crystal

International Nuclear Information System (INIS)

Wang, Wei-Chung; Wu, Liang-Yu; Chen, Lien-Wen; Liu, Chia-Ming

2010-01-01

Acoustic energy harvesting by piezoelectric curved beams in the cavity of a sonic crystal is investigated. A resonant cavity of the sonic crystal is used to localize the acoustic wave as the acoustic waves are incident into the sonic crystal at the resonant frequency. The piezoelectric curved beam is placed in the resonant cavity and vibrated by the acoustic wave. The energy harvesting can be achieved as the acoustic waves are incident at the resonant frequency. A model for energy harvesting of the piezoelectric curved beam is also developed to predict the output voltage and power of the energy harvesting. The experimental results are compared with the theoretical

External-beam PIXE analysis of small sculptures

International Nuclear Information System (INIS)

Gyodi, I.; Demeter, I.; Hollos-Nagy, K.; Kovacs, I.; Szokefalvi-Nagy, Z.

1999-01-01

Non-destructive analysis of precious art objects is an important tool to solve provenance problems or to facilitate restoration. External beam PIXE analysis is one of the most powerful and popular methods used in this respect. The paper summarises the external beam PIXE set-up at the Accelerator Laboratory in Budapest, and two selected applications are described. Different parts of a small Cambodian metal sculpture probably made in the 11th century were analysed. It was observed that the sculpture was composed of an iron core and an outer bronze shell. This sculptural technique was well known in the Middle-East but no indication has been found about its use in the Far-East, yet. Before its restoration paint traces on a wooden relief of St. Jerome made by an unknown artist in about 1600 were analysed. Different white and red paints were distinguished at selected points and the presence of titanium on a certain part of the relief was attributed to a repainting in modern times

Reflection and Transmission of a Focused Finite Amplitude Sound Beam Incident on a Curved Interface

Science.gov (United States)

Makin, Inder Raj Singh

Reflection and transmission of a finite amplitude focused sound beam at a weakly curved interface separating two fluid-like media are investigated. The KZK parabolic wave equation, which accounts for thermoviscous absorption, diffraction, and nonlinearity, is used to describe the high intensity focused beam. The first part of the work deals with the quasilinear analysis of a weakly nonlinear beam after its reflection and transmission from a curved interface. A Green's function approach is used to define the field integrals describing the primary and the nonlinearly generated second harmonic beam. Closed-form solutions are obtained for the primary and second harmonic beams when a Gaussian amplitude distribution at the source is assumed. The second part of the research uses a numerical frequency domain solution of the KZK equation for a fully nonlinear analysis of the reflected and transmitted fields. Both piston and Gaussian sources are considered. Harmonic components generated in the medium due to propagation of the focused beam are evaluated, and formation of shocks in the reflected and transmitted beams is investigated. A finite amplitude focused beam is observed to be modified due to reflection and transmission from a curved interface in a manner distinct from that in the case of a small signal beam. Propagation curves, beam patterns, phase plots and time waveforms for various parameters defining the source and media pairs are presented, highlighting the effect of the interface curvature on the reflected and transmitted beams. Relevance of the current work to biomedical applications of ultrasound is discussed.

Possibilities and conditions of applying PIXE analysis with external proton beam

International Nuclear Information System (INIS)

Potocek, V.

1989-01-01

The technical and methodological prerequisites are summed up for the use of the PIXE method with an external proton beam. The method is suitable for the preliminary analysis of unknown samples prior to the choice of the best suited analytical method, for the nondestructive analysis of rare samples such as unique works of art, of small amounts of materials which are difficult to access, etc., as well as for calibration and comparing analyses. As for the operators the application of the PIXE method with external proton beam assumes the availability of accelerator operating time, minimization of the length of exposure of the targets, optimization of parameters of the exciting beam and automation of the whole process. Attention is also devoted to technical provisions and organization of laboratory work. The design is described of an analytical unit using the PIXE method with external proton beam, and it is stated that the Van de Graaff accelerator at the Institute of Nuclear Physics in Rez near Prague could be used for the purpose. (Z.M.). 6 refs

Two-stream instability for a light ion beam-plasma system with external magnetic field

International Nuclear Information System (INIS)

Okada, T.; Tazawa, H.

1992-12-01

For inertial confinement fusion, a focused light ion beam (LIB) is required to propagate stably through a chamber to a target. We have pointed out that the applied external magnetic field is important for LIB propagation. To investigate the influence of the external magnetic field on the LIB propagation, we analysed the electrostatic dispersion relation of magnetized light ion beam-plasma system. The particle in-cell (PIC) simulation results are presented for a light ion beam-plasma system with external magnetic field. (author)

External proton and Li beams

International Nuclear Information System (INIS)

Schuff, Juan A.; Burlon, Alejandro A.; Debray, Mario E.; Kesque, Jose M.; Kreiner, Andres J.; Stoliar, Pablo A.; Naab, Fabian; Ozafran, Mabel J.; Vazquez, Monica E.; Perez de la Hoz, A.; Somacal, Hector; Valda, Alejandro; Canevas, S.; Ruffolo, M.; Tasat, D.R.; Muhlmann, M. C.

2000-01-01

In the frame of a feasibility study to introduce proton therapy in Argentina in a collaborative agreement between the Physics and Radiobiology Departments of the National Atomic Energy Commission or Argentina and the Centre de Protontherapie de Orsay, France, external proton and Li beams were produced at the TANDAR accelerator in Buenos Aires. The specific aim of this work was to start radiobiology studies on cell cultures and small laboratory animals. In particular we seek to determine here the relative biological effectiveness, RBE, for proton and Li beams as a function of energy for different tumor and normal cell lines. The 24 MeV proton beam was diffused using a 25 μm gold foil and extracted through a Kapton window to obtain a homogeneous field (constant to 95%) of about 7 cm in diameter. Measurements were carried out with quasi-monoenergetic beams (of 20.2 ± 0.07 MeV, 2.9 ± 0.10 MeV y 1.5 ± 0.1 MeV for protons and 21.4 ± 0.4 MeV for Lithium). Proton fluence and Bragg peaks were measured. The dose delivered in each case was monitored on-line with a calibrated transmission ionization chamber. Three cell lines PDV, PDVC 57 and V 79 (as a reference) were irradiated with γ-rays, proton and lithium beams with linear energy transfer (LET) from 2 to 100 keV/μm. RBE values in the range of 1.2-5.9 were obtained. In addition preliminary studies on chromosomal aberrations and viability of alveolar macrophages were carried out. (author)

Derivation of electron and photon energy spectra from electron beam central axis depth dose curves

Energy Technology Data Exchange (ETDEWEB)

Deng Jun [Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA 94305 (United States)]. E-mail: jun@reyes.stanford.edu; Jiang, Steve B.; Pawlicki, Todd; Li Jinsheng; Ma, C.M. [Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA 94305 (United States)

2001-05-01

A method for deriving the electron and photon energy spectra from electron beam central axis percentage depth dose (PDD) curves has been investigated. The PDD curves of 6, 12 and 20 MeV electron beams obtained from the Monte Carlo full phase space simulations of the Varian linear accelerator treatment head have been used to test the method. We have employed a 'random creep' algorithm to determine the energy spectra of electrons and photons in a clinical electron beam. The fitted electron and photon energy spectra have been compared with the corresponding spectra obtained from the Monte Carlo full phase space simulations. Our fitted energy spectra are in good agreement with the Monte Carlo simulated spectra in terms of peak location, peak width, amplitude and smoothness of the spectrum. In addition, the derived depth dose curves of head-generated photons agree well in both shape and amplitude with those calculated using the full phase space data. The central axis depth dose curves and dose profiles at various depths have been compared using an automated electron beam commissioning procedure. The comparison has demonstrated that our method is capable of deriving the energy spectra for the Varian accelerator electron beams investigated. We have implemented this method in the electron beam commissioning procedure for Monte Carlo electron beam dose calculations. (author)

In-Plane Vibrations of Circular Curved Beams with a Transverse Open Crack

OpenAIRE

Öz, H. R.; Daş, M. T.

2006-01-01

In this study, the in plane vibrations of cracked circular curved beams is investigated. The beam is an Euler-Bernoulli beam. Only bending and extension effects are included. The curvature is in a single plane. In plane vibrations is analyzed using FEM. In the analysis, elongation, bending and rotary inertia effects are included. Four degrees of freedom for in-plane vibrations is assumed. Natural frequencies of the beam with a crack in different locations and depths are calculated using FEM. ...

Experimental and simulated beam-foil decay curves for some transitions in Zn II

International Nuclear Information System (INIS)

Hultberg, S.; Liljeby, L.; Mannervik, S.; Veje, E.; Lindgaard, A.

1980-01-01

Experimental beam-foil decay curves for the 4s-4p, 4p-4d, 4d-4f, and the 4p-5s transitions in Zn II are compared to decay curves synthesized from transition probabilities calculated in the numerical Coulomb approximation and either measured initial level populations or population models. Good agreement exists between experimental curves and those based on the measured initial level populations for the 5s, 4d, and 4f levels while certain deviations are noted for the 4p term. None of the applied population models reproduce all experimental curves satisfyingly well. In addition, lifetimes are determined experimentally for 7 terms in Zn II, and good agreement with the numerical Coulomb approximation lifetimes is generally found except for some p terms. Beam-foil excitation-mechanism results for zinc are presented and compared to previous results from light projectiles. (Auth.)

Theoretical and computational analysis of IFR beam transport on curved channels

International Nuclear Information System (INIS)

Rienstra, W.W.

1987-01-01

With the successful demonstration at Sandia National Laboratory and at Lawrence Livermore Laboratory of ion focused regime (IFR) electron beam guiding in accelerators there has developed interest in using IFR channels to steer beams along curved paths. The authors report the calculations of the expected emittance growth from such channels and the results of the TRACKER code simulations of IFR steering with the assistance of strong focus sector magnets

External beam radiotherapy in the management of ovarian carcinoma

International Nuclear Information System (INIS)

Reinfuss, Marian; Zbigniew, Kojs; Skolyszewski, Jan

1993-01-01

Between 1970 and 1983, 345 patients with ovarian cancer clinical stage I, II and III were irradiated postoperatively. Five-year NED survival was achieved in 41.7% of patients. The most important prognostic factors were histological grade and clinical stage of cancer. Postoperative external beam radiotherapy appeared to be highly efficient for the patients with microscopic residual disease, giving 70% 5-year survival, and moderately efficient for patients with small, i.e. ≤3 cm in diameter residual disease, giving 40% 5-year survival. The optimal technique of irradiation appeared to be the irradiation given to the entire abdominal cavity with additional irradiation coned down to the pelvis. External beam radiotherapy was ineffective in patients with gross residual disease, i.e. >3 cm in diameter, and useless as palliative treatment given to patients with inoperable cancer of the ovary. (author). tabs., figs

Biochemical failure after radical external beam radiotherapy for prostate cancer

International Nuclear Information System (INIS)

Nomoto, Satoshi; Imada, Hajime; Kato, Fumio; Yahara, Katsuya; Morioka, Tomoaki; Ohguri, Takayuki; Nakano, Keita; Korogi, Yukunori

2005-01-01

The purpose of this study was to evaluate biochemical failures after radical external beam radiotherapy for prostate cancer. A total of 143 patients with prostate cancer (5 cases in stage A2, 95 in stage B and 43 in stage C; 18 in low risk group, 37 in intermediate risk group, 67 in high risk group and 21 in unknown group) were included in this study. Patients of stage A2 and B underwent external irradiation of 46 Gy to the prostate gland and seminal vesicle and additional 20 Gy to the prostate gland, while patients of stage C underwent external irradiation of 66 Gy to the prostate gland and seminal vesicle including 46 Gy to the pelvis. Neoadjuvant hormonal therapy was done in 66 cases, and long-term hormonal therapy in 75 cases; two cases were treated with radiation therapy alone. The 3-year relapse free survival rates by stage A2, B and C were 100%, 96.7% and 88.1%, respectively. The 3-year relapse free survival rates by low, intermediate and high risk groups were 100%, 92.3% and 89.7%, respectively. Biochemical failure was noted in nine cases during the average observation term of 32.2 months; in this group the median of prostate specific antigen (PSA) value was 2.6 ng/ml, the doubling time was 8.6 months, and the term of biochemical failure was 33.2 months. Six of eight cases with biochemical failure were the neoadjuvant hormonal therapy group, but biochemical no evidence of disease (bNED) curve showed no significant difference between neoadjuvant and long-term hormonal groups. It is supposed that unnecessary hormonal therapies were performed based on the nonspecific diagnosis of biochemical failure after radical radiotherapy in our group of patients. A precise criterion of biochemical failure after radical radiotherapy for prostate cancer is necessary. (author)

Vibration Energy Harvester with Bi-stable Curved Beam Spring Offset by Gravitational Acceleration

International Nuclear Information System (INIS)

Yamamoto, Koki; Fujita, Takayuki; Kanda, Kensuke; Maenaka, Kazusuke; Badel, Adrien; Formosa, Fabien

2015-01-01

We developed MEMS bi-stable spring for vibration energy harvester (VEH), which consists of intrinsically curved shape spring and gravitational acceleration. By applying the gravitational acceleration, the curved beam is offset to the gravity direction. It will make more symmetrical bi-stable motion and the symmetry is improved from 3.3 to 65.4%. We proposed that the combination between curved beam and gravity acceleration for decreasing snap- through acceleration. From the analytical result, we investigate the combination can effective to use for decreasing of snap-through force. We also fabricated the prototype device by using MEMS fabrication process. The frequency response for horizontal direction and the acceleration response for vertical direction are measured. The acceleration response shows that the gravitational acceleration improves the symmetry of snap-through force. (paper)

Dose-rate effects in external beam radiotherapy redux

International Nuclear Information System (INIS)

Ling, C. Clifton; Gerweck, Leo E.; Zaider, Marco; Yorke, Ellen

2010-01-01

Recent developments in external beam radiotherapy, both in technical advances and in clinical approaches, have prompted renewed discussions on the potential influence of dose-rate on radio-response in certain treatment scenarios. We consider the multiple factors that influence the dose-rate effect, e.g. radical recombination, the kinetics of sublethal damage repair for tumors and normal tissues, the difference in α/β ratio for early and late reacting tissues, and perform a comprehensive literature review. Based on radiobiological considerations and the linear-quadratic (LQ) model we estimate the influence of overall treatment time on radio-response for specific clinical situations. As the influence of dose-rate applies to both the tumor and normal tissues, in oligo-fractionated treatment using large doses per fraction, the influence of delivery prolongation is likely important, with late reacting normal tissues being generally more sensitive to the dose-rate effect than tumors and early reacting tissues. In conventional fractionated treatment using 1.8-2 Gy per fraction and treatment times of 2-10 min, the influence of dose-rate is relatively small. Lastly, the dose-rate effect in external beam radiotherapy is governed by the overall beam-on-time, not by the average linac dose-rate, nor by the instantaneous dose-rate within individual linac pulses which could be as high as 3 x 10 6 MU/min.

Bilateral Rhegmatogenous Retinal Detachment during External Beam Radiotherapy

Directory of Open Access Journals (Sweden)

Takako Hidaka

2016-06-01

Full Text Available Herein, we report a case of nontraumatic bilateral rhegmatogenous retinal detachment (RRD during external beam radiotherapy for nonocular tumor, presented as an observational case study in conjunction with a review of the relevant literature. A 65-year-old male was referred to our hospital due to bilateral RRD. He underwent a biopsy for a tumor of the left frontal lobe 4 months prior to presentation, and the tumor had been diagnosed as primary central nerve system B-cell type lymphoma. He received chemotherapy and external beam radiotherapy for 1 month. There were no traumatic episodes. Bilateral retinal detachment occurred during a series of radiotherapies. Simultaneous nontraumatic bilateral retinal detachment is rare. The effects of radiotherapy on ocular functionality, particularly in cases involving retinal adhesion and vitreous contraction, may include RRD. Thus, it is necessary to closely monitor the eyes of patients undergoing radiotherapy, particularly those undergoing surgery for retinal detachment and those with a history of photocoagulation for retinal tears, a relevant family history, or risk factors known to be associated with RRD.

External beam radiation for retinoblastoma: Results, patterns of failure, and a proposal for treatment guidelines

International Nuclear Information System (INIS)

Hernandez, J. Carlos; Brady, Luther W.; Shields, Jerry A.; Shields, Carol L.; Potter, Patrick de; Karlsson, Ulf L.; Markoe, Arnold M.; Amendola, Beatriz E.; Singh, Arun

1996-01-01

Purpose: To analyze treatment results and patterns of failure following external beam radiation for retinoblastoma and propose treatment guidelines according to specific clinical variables. Methods and Materials: We analyzed 27 patients (34 eyes) with retinoblastoma who received external beam radiation as initial treatment at Hahnemann University Hospital from October 1980 to December 1991 and have been followed for at least 1 year. Of the 34 eyes, 14 were Groups I-II (Reese-Ellsworth classification), 7 were Group III, and 13 were Groups IV-V. Doses ranged from 34.5-49.5 Gy (mean 44.3 Gy, median 45 Gy) in 1.5-2.0 Gy fractions generally delivered through anterior and lateral wedged pair fields. Results: At a mean follow up of 35.2 months (range 12-93 months), local tumor control was obtained in 44% (15 out of 34) of eyes with external beam radiation alone. Salvage therapy (plaque brachytherapy, cryotherapy, and/or photocoagulation) controlled an additional 10 eyes (29.5%), so that overall ocular survival has been 73.5%. Local tumor control with external beam radiotherapy alone was obtained in 78.5% (11 out of 14) of eyes in Groups I-II, but in only 20% (4 out of 20) of eyes in Groups III-V. A total of 67 existing tumors were identified prior to treatment in the 34 treated eyes and local control with external beam radiation alone was obtained in 87% (46 out of 53) of tumors measuring 15 mm or less and in 50% (7 out of 14) of tumors measuring more than 15 mm. When analyzing patterns of failure in the 19 eyes that relapsed, a total of 28 failure sites were identified and consisted of progression of vitreous seeds in seven instances (25% of failure sites) recurrences from previously existing tumors in 10 instances (36% of failure sites) and development of new tumors in previously uninvolved retina in 11 instances (39% of failure sites). Conclusions: 1) We find that external beam radiation to a dose of 45 Gy in fractions of 1.5 to 2.0 Gy provides adequate tumor control

Displacement sensing based on resonant frequency monitoring of electrostatically actuated curved micro beams

International Nuclear Information System (INIS)

Krakover, Naftaly; Krylov, Slava; Ilic, B Robert

2016-01-01

The ability to control nonlinear interactions of suspended mechanical structures offers a unique opportunity to engineer rich dynamical behavior that extends the dynamic range and ultimate device sensitivity. We demonstrate a displacement sensing technique based on resonant frequency monitoring of curved, doubly clamped, bistable micromechanical beams interacting with a movable electrode. In this configuration, the electrode displacement influences the nonlinear electrostatic interactions, effective stiffness and frequency of the curved beam. Increased sensitivity is made possible by dynamically operating the beam near the snap-through bistability onset. Various in-plane device architectures were fabricated from single crystal silicon and measured under ambient conditions using laser Doppler vibrometry. In agreement with the reduced order Galerkin-based model predictions, our experimental results show a significant resonant frequency reduction near critical snap-through, followed by a frequency increase within the post-buckling configuration. Interactions with a stationary electrode yield a voltage sensitivity up to  ≈560 Hz V −1 and results with a movable electrode allow motion sensitivity up to  ≈1.5 Hz nm −1 . Our theoretical and experimental results collectively reveal the potential of displacement sensing using nonlinear interactions of geometrically curved beams near instabilities, with possible applications ranging from highly sensitive resonant inertial detectors to complex optomechanical platforms providing an interface between the classical and quantum domains. (paper)

Synthesization of the Ar VIII 3s-3p beam-foil decay curve

International Nuclear Information System (INIS)

Lindgaard, A.; Veje, E.

1981-01-01

The beam-foil decay curve for the 3s-3p transition in Ar VIII has been simulated from experimentally determined relative initial level populations and transition probabilities calculated in the numerical Coulomb approximation. Good agreement is observed between simulated and measured decay curves. A discussion of the simulation is given. (Auth.)

External Beam Radiotherapy in Metastatic Bone Pain from Solid ...

African Journals Online (AJOL)

Key Words: Bone, metastasis, radiotherapy, pain, control randomized ... described the efficacy of external beam radiotherapy in pain .... life of patients with multiple myeloma. Eur. J. ... Rades D, Jeremic B, Hoskin PJ: The Role of ... randomised multicenter trial on single fraction ... "The subjective experience of acute pain. An.

The relationship between external beam radiotherapy dose and chronic urinary dysfunction - A methodological critique

International Nuclear Information System (INIS)

Rosewall, Tara; Catton, Charles; Currie, Geoffrey; Bayley, Andrew; Chung, Peter; Wheat, Janelle; Milosevic, Michael

2010-01-01

Purpose: To perform a methodological critique of the literature evaluating the relationship between external beam radiotherapy dose/volume parameters and chronic urinary dysfunction to determine why consistent associations between dose and dysfunction have not been found. Methods and materials: The radiotherapy literature was reviewed using various electronic medical search engines with appropriate keywords and MeSH headings. Inclusion criteria comprised of; English language articles, published between 1999 and June 2009, incorporating megavoltage external beam photons in standard-sized daily fraction. A methodological critique was then performed, evaluating the factors affected in the quantification of radiotherapy dose and chronic urinary dysfunction. Results: Nine of 22 eligible studies successfully identified a clinically and statistically significant relationship between dose and dysfunction. Accurate estimations of external beam radiotherapy dose were compromised by the frequent use of dosimetric variables which are poor surrogates for the dose received by the lower urinary tract tissue and do not incorporate the effect of daily variations in isocentre and bladder position. The precise categorization of chronic urinary dysfunction was obscured by reliance on subjective and aggregated toxicity metrics which vary over time. Conclusions: A high-level evidence-base for the relationship between external beam radiotherapy dose and chronic urinary dysfunction does not currently exist. The quantification of the actual external beam dose delivered to the functionally important tissues using dose accumulation strategies and the use of objective measures of individual manifestations of urinary dysfunction will assist in the identification of robust relationships between dose and urinary dysfunction for application in widespread clinical practice.

External beam pixe programs at the University of California, Davis

International Nuclear Information System (INIS)

Eldred, R.A.

1983-01-01

A PIXE system in which large or delicate samples are excited by a low-current external proton beam is described. This system has been used to analyze historical printed books and manuscripts, as well as a large variety of archeological artifacts. The steps used to protect the sample from unnecessary beam current are examined. A recent thorough study of the first volume of the Gutenberg 42-line Bible is described in some detail

Implementation of a system for external audits beam radiation therapy in terms of reference no

International Nuclear Information System (INIS)

Alonso Samper, Jose Luis; Dominguez, Lourdes; Alert Silva, Jose; Alfonso Laguardia, Rodolfo; Larrinaga Cortina, Eduardo; Garcia Yip, Fernando; Rodriguez Machado, Jorge; Morales Lopez, Jorge Luis; Silvestre Patallo, Ileana

2009-01-01

This paper presents our experience in implementing a external audit system for radiotherapy beam in no reference conditions with the use of CIRS and a summary of the measurements with him made.This paper presents our experience in implementing a external audit system for radiotherapy beam in no reference conditions with the use of CIRS and a summary of the measurements with him made. Centers were audited with external beam high-energy Co-60, 6 MV and 15 MV and were considered 4 treatment planning systems (TPS): AMEPLAN, Theraplan Plus, Precise Plan and MIRS to calculate doses prescribed in each test case. All measurements were acquired by the audit team using the anthropomorphic phantom CIRS, Semiflex chamber PTW 31010 and PTW electrometer STATES. The implementation and development of the external audits of beams radiotherapy in terms of 'no reference' has brought an improvement in both clinical aspects of treatment and the radiation safety and the quality control, has given us greater confidence and for this reason we believe has become essential. (Author)

The effect of material heterogeneity in curved composite beams for use in aircraft structures

Science.gov (United States)

Otoole, Brendan J.; Santare, Michael H.

1992-01-01

A design tool is presented for predicting the effect of material heterogeneity on the performance of curved composite beams for use in aircraft fuselage structures. Material heterogeneity can be induced during processes such as sheet forming and stretch forming of thermoplastic composites. This heterogeneity can be introduced in the form of fiber realignment and spreading during the manufacturing process causing a gradient in material properties in both the radial and tangential directions. The analysis procedure uses a separate two-dimensional elasticity solution for the stresses in the flanges and web sections of the beam. The separate solutions are coupled by requiring the forces and displacements match at the section boundaries. Analysis is performed for curved beams loaded in pure bending and uniform pressure. The beams can be of any general cross-section such as a hat, T-, I-, or J-beam. Preliminary results show that geometry of the beam dictates the effect of heterogeneity on performance. Heterogeneity plays a much larger role in beams with a small average radius to depth ratio, R/t, where R is the average radius of the beam and t is the difference between the inside and outside radius. Results of the analysis are in the form of stresses and displacements, and they are compared to both mechanics of materials and numerical solutions obtained using finite element analysis.

A method to combine three dimensional dose distributions for external beam and brachytherapy radiation treatments for gynecological neoplasms

International Nuclear Information System (INIS)

Narayana, V.; Sahijdak, W.M.; Orton, C.G.

1997-01-01

Purpose: Radiation treatment of gynecological neoplasms, such as cervical carcinoma, usually combines external radiation therapy with one or more intracavitary brachytherapy applications. Although the dose from external beam radiation therapy and brachytherapy can be calculated and displayed in 3D individually, the dose distributions are not combined. At most, combined point doses are calculated for select points using various time-dose models. In this study, we present a methodology to combine external beam and brachytherapy treatments for gynecological neoplasms. Material and Methods: Three dimensional bio-effect treatment planning to obtain complication probability has been outlined. CT scans of the patient's pelvis with the gynecological applicator in place are used to outline normal tissue and tumor volumes. 3D external beam and brachytherapy treatment plans are developed separately and an external beam dose matrix and a brachytherapy dose matrix was calculated. The dose in each voxel was assumed to be homogeneous. The physical dose in each voxel of the dose matrix was then converted into extrapolated response dose (ERD) based on the linear quadratic model that accounts for the dose per fraction, number of fractions, dose rate, and complete or incomplete repair of sublethal damage (time between fractions). The net biological dose delivered was obtained by summing the ERD grids from external beam and brachytherapy since there was complete repair of sublethal damage between external beam and brachytherapy treatments. The normal tissue complication probability and tumor control probability were obtained using the biological dose matrix based on the critical element model. Results: The outlined method of combining external beam and brachytherapy treatments was implemented on gynecological treatments using an applicator for brachytherapy treatments. Conclusion: Implementation of the biological dose calculation that combine different modalities is extremely useful

Prospective survey of erectile dysfunction after external beam radiotherapy for prostate cancer

International Nuclear Information System (INIS)

Kikuchi, Eiji; Ando, Toshiyuki; Nagata, Hirohiko; Miyajima, Akira; Nakagawa, Ken; Oya, Mototsugu; Nakashima, Jun; Marumo, Ken

2011-01-01

We prospectively evaluated the effect of external beam radiotherapy on erectile function in patients with localized or locally advanced prostate cancer using the Japanese version of the International Index of Erectile Function (IIEF) survey. From 2000 to 2007, we identified 55 patients who underwent external beam radiotherapy at our institution for localized or locally advanced prostate cancer and could respond to the IIEF survey. The patients did not receive neo- and/or adjuvant hormone therapy and they were followed-up for at least 12 months after radiotherapy. Mean patient age was 69 years and the mean prostate specific antigen (PSA) level before radiotherapy was 24.9 ng/ml. First we evaluated the change of the erectile function domain score over time before and after radiotherapy. The population of severe erectile dysfunction (ED) increased while those with no or mild ED decreased after radiotherapy. The erectile function and intercourse satisfaction domain score of the IIEF declined significantly after radiotherapy, however, the orgasmic function, sexual desire, and overall satisfaction domain scores did not change after external beam radiation. Of the 34 patients who had erectile function at baseline, 10 patients could maintain erectile function 12 months after radiotherapy. Though there were no significant differences in clinical features between patients who could maintain erectile function and those who had worsening erectile function 12 months after radiotherapy, the sexual desire domain score before radiotherapy was significantly higher in patients who could maintain erectile function than their counterparts. Using the IIEF survey, external beam radiation was found to affect erectile function in patients with localized or locally advanced prostate cancer. (author)

SU-E-T-403: Evaluation of the Beam Performance of a Varian TrueBeam Linear Accelerator Under External Device-Based Gated Delivery Conditions

International Nuclear Information System (INIS)

Kobulnicky, K; Pawlak, D; Purwar, A

2015-01-01

Purpose: To examine the beam performance of a Varian TrueBeam linear accelerator under external device-based gated delivery conditions. Methods: Six gating cycles were used to evaluate the gating performance of a standard production TrueBeam system that was not specially tuned in any way. The system was equipped with a factory installed external gating interface (EXGI). An in-house EXGI tester box was used to simulate the input gating signals. The gating cycles were selected based on long beam-on and short beam-off times, short beam-on and long beam-off times, or equal beam on and off times to check linac performance. The beam latencies were measured as the time difference between the logic high gating signal and the first or last target pulses with an oscilloscope. Tissue-Phantom Ratio, beam flatness, and dose distributions from 5 different plans were measured using the 6 different gating durations and the un-gated irradiation. A PTW 729 2-D array was used to compare 5 plans versus the un-gated delivery with a 1%/1mm gamma index passing criteria. Results: The beam latencies of the linac were based off of 20 samples for beam-on and beam-off, for each gating cycle. The average beam-on delays were measured to be between 57 and 66msec, with a maximum of 88 msec. The beam off latencies averaged between 19 and 26msec, with a maximum of 48 msec. TPR20,10 measurements showed beam energy stability within 0.5% of the un-gated delivery. Beam flatness was better than 2.5% for all gated cycles. All but two deliveries, the open field with 4 seconds on, 1 second off, and a five field IMRT plan with 0.5 seconds on, 2.5 seconds off, had >90% passing rate. Conclusion: TrueBeam demonstrates excellent beam stability with minimal beam latencies under external device-based gated operations. Dosimetric measurements show minimal variation in beam energy, flatness, and plan delivery. Authors are employees of Varian Medical Systems, Inc

SU-E-T-403: Evaluation of the Beam Performance of a Varian TrueBeam Linear Accelerator Under External Device-Based Gated Delivery Conditions

Energy Technology Data Exchange (ETDEWEB)

Kobulnicky, K; Pawlak, D; Purwar, A [Varian Medical Systems, Inc., Palo Alto, CA (United States)

2015-06-15

Purpose: To examine the beam performance of a Varian TrueBeam linear accelerator under external device-based gated delivery conditions. Methods: Six gating cycles were used to evaluate the gating performance of a standard production TrueBeam system that was not specially tuned in any way. The system was equipped with a factory installed external gating interface (EXGI). An in-house EXGI tester box was used to simulate the input gating signals. The gating cycles were selected based on long beam-on and short beam-off times, short beam-on and long beam-off times, or equal beam on and off times to check linac performance. The beam latencies were measured as the time difference between the logic high gating signal and the first or last target pulses with an oscilloscope. Tissue-Phantom Ratio, beam flatness, and dose distributions from 5 different plans were measured using the 6 different gating durations and the un-gated irradiation. A PTW 729 2-D array was used to compare 5 plans versus the un-gated delivery with a 1%/1mm gamma index passing criteria. Results: The beam latencies of the linac were based off of 20 samples for beam-on and beam-off, for each gating cycle. The average beam-on delays were measured to be between 57 and 66msec, with a maximum of 88 msec. The beam off latencies averaged between 19 and 26msec, with a maximum of 48 msec. TPR20,10 measurements showed beam energy stability within 0.5% of the un-gated delivery. Beam flatness was better than 2.5% for all gated cycles. All but two deliveries, the open field with 4 seconds on, 1 second off, and a five field IMRT plan with 0.5 seconds on, 2.5 seconds off, had >90% passing rate. Conclusion: TrueBeam demonstrates excellent beam stability with minimal beam latencies under external device-based gated operations. Dosimetric measurements show minimal variation in beam energy, flatness, and plan delivery. Authors are employees of Varian Medical Systems, Inc.

Generating AN Optimum Treatment Plan for External Beam Radiation Therapy.

Science.gov (United States)

Kabus, Irwin

1990-01-01

The application of linear programming to the generation of an optimum external beam radiation treatment plan is investigated. MPSX, an IBM linear programming software package was used. All data originated from the CAT scan of an actual patient who was treated for a pancreatic malignant tumor before this study began. An examination of several alternatives for representing the cross section of the patient showed that it was sufficient to use a set of strategically placed points in the vital organs and tumor and a grid of points spaced about one half inch apart for the healthy tissue. Optimum treatment plans were generated from objective functions representing various treatment philosophies. The optimum plans were based on allowing for 216 external radiation beams which accounted for wedges of any size. A beam reduction scheme then reduced the number of beams in the optimum plan to a number of beams small enough for implementation. Regardless of the objective function, the linear programming treatment plan preserved about 95% of the patient's right kidney vs. 59% for the plan the hospital actually administered to the patient. The clinician, on the case, found most of the linear programming treatment plans to be superior to the hospital plan. An investigation was made, using parametric linear programming, concerning any possible benefits derived from generating treatment plans based on objective functions made up of convex combinations of two objective functions, however, this proved to have only limited value. This study also found, through dual variable analysis, that there was no benefit gained from relaxing some of the constraints on the healthy regions of the anatomy. This conclusion was supported by the clinician. Finally several schemes were found that, under certain conditions, can further reduce the number of beams in the final linear programming treatment plan.

Suppression of beam-excited electron waves by an externally applied RF signal

International Nuclear Information System (INIS)

Fukumasa, Osamu; Itatani, Ryohei

1980-11-01

Suppression of the beam-excited electron wave in a bounded system is investigated in connection with the beam distribution function. Wave suppression has two different processes depending on whether injected beams are reflected at the other end or not. In the absence of reflected beam electrons, deformation of the beam distribution function is observed in relation to the suppression of the electron wave. However, when beam electrons are reflected, the external wave suppresses the electron wave but distribution function shows no appreciable change. These experimental results show that nonlinear behaviors of beam electrons, namely behaviors of reflected beams, are quite important for wave suppression. By using the method of partial simulation, interaction between two waves in the bounded system including nonlinear motions of beam electrons is studied numerically. Qualitative agreement between experimental and numerical results is obtained. (author)

An assessment of effective dose to staff in external beam radiotherapy

International Nuclear Information System (INIS)

Rawlings, D.J.; Nicholson, L.

1997-01-01

Radiation safety in external beam radiotherapy is governed by national legislation. Annual doses recorded by radiographers and others associated with external beam radiotherapy are typically much lower than the relevant dose limit. However, it is possible that larger doses might be received as a result of an accidental irradiation. In the event of a significant exposure resulting in a dose at or near a relevant dose limit, an accurate conversion has to be made from the dose meter reading to the limiting quantity. A method was devised to demonstrate ratios of effective dose to personal dose equivalent which might be anticipated in the even of an individual other than the patient being irradiated within a radiotherapy treatment room consisting of a linear accelerator. The variation of ratios obtained under different conditions is discussed. (author)

Biological-effective versus conventional dose volume histograms correlated with late genitourinary and gastrointestinal toxicity after external beam radiotherapy for prostate cancer: a matched pair analysis

Directory of Open Access Journals (Sweden)

Roeske John C

2003-05-01

Full Text Available Abstract Background To determine whether the dose-volume histograms (DVH's for the rectum and bladder constructed using biological-effective dose (BED-DVH's better correlate with late gastrointestinal (GI and genitourinary (GU toxicity after treatment with external beam radiotherapy for prostate cancer than conventional DVH's (C-DVH's. Methods The charts of 190 patients treated with external beam radiotherapy with a minimum follow-up of 2 years were reviewed. Six patients (3.2% were found to have RTOG grade 3 GI toxicity, and similarly 6 patients (3.2% were found to have RTOG grade 3 GU toxicity. Average late C-DVH's and BED-DVH's of the bladder and rectum were computed for these patients as well as for matched-pair control patients. For each matched pair the following measures of normalized difference in the DVH's were computed: (a δAUC = (Area Under Curve [AUC] in grade 3 patient – AUC in grade 0 patient/(AUC in grade 0 patient and (b δV60 = (Percent volume receiving = 60 Gy [V60] in grade 3 patient – V60 in grade 0 patient/(V60 in grade 0 patient. Results As expected, the grade 3 curve is to the right of and above the grade 0 curve for all four sets of average DVH's – suggesting that both the C-DVH and the BED-DVH can be used for predicting late toxicity. δAUC was higher for the BED-DVH's than for the C-DVH's – 0.27 vs 0.23 (p = 0.036 for the rectum and 0.24 vs 0.20 (p = 0.065 for the bladder. δV60 was also higher for the BED-DVH's than for the C-DVH's – 2.73 vs 1.49 for the rectum (p = 0.021 and 1.64 vs 0.71 (p = 0.021 for the bladder. Conclusions When considering well-established dosimetric endpoints used in evaluating treatment plans, BED-DVH's for the rectum and bladder correlate better with late toxicity than C-DVH's and should be considered when attempting to minimize late GI and GU toxicity after external beam radiotherapy for prostate cancer.

Guide for External Beam Radiotherapy. Procedures 2007

International Nuclear Information System (INIS)

Ardiet, Jean-Michel; Bourhis, Jean; Eschwege, Francois; Gerard, Jean-Pierre; Martin, Philippe; Mazeron, Jean-Jacques; Barillot, Isabelle; Bey, Pierre; Cosset, Jean-Marc; Thomas, Olivier; Bolla, Michel; Bourguignon, Michel; Godet, Jean-Luc; Krembel, David; Valero, Marc; Bara, Christine; Beauvais-March, Helene; Derreumaux, Sylvie; Vidal, Jean-Pierre; Drouard, Jean; Sarrazin, Thierry; Lindecker-Cournil, Valerie; Robin, Sun Hee Lee; Thevenet, Nicolas; Depenweiller, Christian; Le Tallec, Philippe; Ortholan, Cecile; Aimone, Nicole; Baldeschi, Carine; Cantelli, Andree; Estivalet, Stephane; Le Prince, Cyrille; QUERO, Laurent; Costa, Andre; Gerard, Jean-Pierre; Ardiet, Jean-Michel; Bensadoun, Rene-Jean; Bourhis, Jean; Calais, Gilles; Lartigau, Eric; Ginot, Aurelie; Girard, Nicolas; Mornex, Francoise; Bolla, Michel; Chauvet, Bruno; Maingon, Philippe; Martin, Etienne; Azria, David; Gerard, Jean-Pierre; Grehange, Gilles; Hennequin, Christophe; Peiffert, Didier; Toledano, Alain; Belkacemi, Yazid; Courdi, Adel; Belliere, Aurelie; Peignaux, Karine; Mahe, Marc; Bondiau, Pierre-Yves; Kantor, Guy; Lepechoux, Cecile; Carrie, Christian; Claude, Line

2007-01-01

In order to optimize quality and security in the delivery of radiation treatment, the French SFRO (Societe francaise de radiotherapie oncologique) is publishing a Guide for Radiotherapy. This guide is realized according to the HAS (Haute Autorite de sante) methodology of 'structured experts consensus'. This document is made of two parts: a general description of external beam radiation therapy and chapters describing the technical procedures of the main tumors to be irradiated (24). For each procedure, a special attention is given to dose constraints in the organs at risk. This guide will be regularly updated

The curvature of sensitometric curves for Kodak XV-2 film irradiated with photon and electron beams.

Science.gov (United States)

van Battum, L J; Huizenga, H

2006-07-01

Sensitometric curves of Kodak XV-2 film, obtained in a time period of ten years with various types of equipment, have been analyzed both for photon and electron beams. The sensitometric slope in the dataset varies more than a factor of 2, which is attributed mainly to variations in developer conditions. In the literature, the single hit equation has been proposed as a model for the sensitometric curve, as with the parameters of the sensitivity and maximum optical density. In this work, the single hit equation has been translated into a polynomial like function as with the parameters of the sensitometric slope and curvature. The model has been applied to fit the sensitometric data. If the dataset is fitted for each single sensitometric curve separately, a large variation is observed for both fit parameters. When sensitometric curves are fitted simultaneously it appears that all curves can be fitted adequately with a sensitometric curvature that is related to the sensitometric slope. When fitting each curve separately, apparently measurement uncertainty hides this relation. This relation appears to be dependent only on the type of densitometer used. No significant differences between beam energies or beam modalities are observed. Using the intrinsic relation between slope and curvature in fitting sensitometric data, e.g., for pretreatment verification of intensity-modulated radiotherapy, will increase the accuracy of the sensitometric curve. A calibration at a single dose point, together with a predetermined densitometer-dependent parameter ODmax will be adequate to find the actual relation between optical density and dose.

The target volume concept at the recording of external beam radiotherapy

International Nuclear Information System (INIS)

Quast, U.; Glaeser, L.

1981-01-01

With the aim of complete, exact and reproducible manual recording and documentation of external beam radiotherapy a concept is proposed providing treatment planning and recording related to space and time for target volumes of different order corresponding to Ist, IInd or IIIrd part of treatment course, regarding all dose limiting organs at risk. The record consists of the dosage plan for medical treatment planning, the treatment plan for physical dose distribution planning and the treatment record of absorbed doses delivered as well as a checklist for patient and machine set-up, and labels for intended actions during treatment development. A clear arrangement of the record form in logical order was found, demanding exact specification of target(s) and beam(s) and their relation in space and time; asking for verbal and graphical description of target volumes, organs at risk, patient positioning, beam portals and dose reference points in terms of patients' anatomy; emphasizing the most important medical data by marked areas and leaving enough empty space for additional data, remarks or comments. During several years of clinical use these record forms proved to be suitable for all cases of external beam therapy, for complex situations of target volumes and treatment-scheduling, for all treatment techniques and radiation qualities and for all ways of physical treatment planning. They can be extended to automatic treatment verification, monitoring and recording as well as to the application of in-vivo-measurements of absorbed doses. (orig.) [de

Elemental analysis with external-beam PIXE

Science.gov (United States)

Lin, E. K.; Wang, C. W.; Teng, P. K.; Huang, Y. M.; Chen, C. Y.

1992-05-01

A beamline system and experimental setup has been established for elemental analysis using PIXE with an external beam. Experiments for the study of the elemental composition of ancient Chinese potsherds (the Min and Ching ages) were performed. Continuum X-ray spectra from the samples bombarded by 3 MeV protons have been measured with a Si(Li) detector. From the analysis of PIXE data, the concentration of the main elements (Al, Si, K, and Ca) and of more than ten trace elements in the matrices and glazed surfaces were determined. Results for two different potsherds are presented, and those obtained from the glaze colorants are compared with the results of measurements on a Ching blue-and-white porcelain vase.

Respiratory gated beam delivery cannot facilitate margin reduction, unless combined with respiratory correlated image guidance

DEFF Research Database (Denmark)

Korreman, S.S.; Boyer, A.L.; Juhler-Nøttrup, Trine

2008-01-01

PURPOSE/OBJECTIVE: In radiotherapy of targets moving with respiration, beam gating is offered as a means of reducing the target motion. The purpose of this study is to evaluate the safe magnitude of margin reduction for respiratory gated beam delivery. MATERIALS/METHODS: The study is based on data...... for 17 lung cancer patients in separate protocols at Rigshospitalet and Stanford Cancer Center. Respiratory curves for external optical markers and implanted fiducials were collected using equipment based on the RPM system (Varian Medical Systems). A total of 861 respiratory curves represented external...... measurements over 30 fraction treatment courses for 10 patients, and synchronous external/internal measurements in single sessions for seven patients. Variations in respiratory amplitude (simulated coaching) and external/internal phase shifts were simulated by perturbation with realistic values. Variations...

MO-A-BRB-03: Integration Issues in Electronic Charting for External Beam Therapy

International Nuclear Information System (INIS)

Sutlief, S.

2015-01-01

The process of converting to an electronic chart for radiation therapy can be daunting. It requires a dedicated committee to first research and choose appropriate software, to review the entire documentation policy and flow of the clinic, to convert this system to electronic form or if necessary, redesign the system to more easily conform to the electronic process. Those making the conversion and those who already use electronic charting would benefit from the shared experience of those who have been through the process in the past. Therefore TG262 was convened to provide guidance on electronic charting for external beam radiation therapy and brachytherapy. This course will present the results of an internal survey of task group members on EMR practices in External Beam Radiation Therapy as well as discuss important issues in EMR development and structure for both EBRT and brachytherapy. Learning Objectives: Be familiarized with common practices and pitfalls in development and maintenance of an electronic chart in Radiation Oncology Be familiarized with important issues related to electronic charting in External Beam Radiation Therapy Be familiarized with important issues related to electronic charting in Brachytherapy

In-vivo dosimetric study of carcinoma of uterine cervix with FBX solution in external beam therapy

International Nuclear Information System (INIS)

Srinivas, Challapalli; Shenoy, K. Kamalaksh; Dinesh, M.; Savitha, K.S.; Kasturi, Dinesh Pai; Supe, S.S.; Nagesha, Y.N.

1999-01-01

To ensure accurate dose delivery to target site in external beam therapy and brachytherapy, various authors have conducted tests to assess the process of manual dose calculations. In vivo dosimetric measurement is one of these methods to verify these calculations. In this study, an attempt has been made to compare the manually calculated dose to dose estimated using a chemical dosimeter (FBX) solution (in-vivo method, using polypropylene vials), on 12 patients of carcinoma of uterine cervix in external beam therapy. Dose measured by FBX vial varies in the range of ± 2 to 6.75%, as compared with manual calculations. These variations seen may be attributed to the location of the vial position in the vagina, with reference to the beam axis (may not be horizontal), off axis position, manual calculation variations and reproducibility of the FBX system etc. FBX dosimetry offers itself as an in-vivo method to estimate the dose delivered to the target site in external beam therapy. (author)

Calculation of Coherent Synchrotron Radiation Impedance for a Beam Moving in a Curved Trajectory

Science.gov (United States)

Zhou, Demin; Ohmi, Kazuhito; Oide, Katsunobu; Zang, Lei; Stupakov, Gennady

2012-01-01

Coherent synchrotron radiation (CSR) fields are generated when a bunched beam moves along a curved trajectory. A new code, named CSRZ, was developed using finite difference method to calculate the longitudinal CSR impedance for a beam moving along a curved chamber. The method adopted in the code was originated by Agoh and Yokoya [Phys. Rev. ST Accel. Beams 7 (2004) 054403]. It solves the parabolic equation in the frequency domain in a curvilinear coordinate system. The chamber considered has uniform rectangular cross-section along the beam trajectory. The code was used to investigate the properties of CSR impedance of a single or a series of bending magnets. The calculation results indicate that the shielding effect due to outer chamber wall can be well explained by a simple optical approximation model at high frequencies. The CSR fields reflected by the outer wall may interfere with each other along a series of bending magnets and lead to sharp narrow peaks in the CSR impedance. In a small storage ring, such interference effect can be significant and may cause microwave instability, according to a simple estimate of instability threshold.

A TCP model for external beam treatment of intermediate-risk prostate cancer.

LENUS (Irish Health Repository)

Walsh, Seán

2013-03-01

Biological models offer the ability to predict clinical outcomes. The authors describe a model to predict the clinical response of intermediate-risk prostate cancer to external beam radiotherapy for a variety of fractionation regimes.

High field superconducting beam transport in a BNL primary proton beam

International Nuclear Information System (INIS)

Allinger, J.; Brown, H.N.; Carroll, A.S.; Danby, G.; DeVito, B.; Glenn, J.W.; Jackson, J.; Keith, W.; Lowenstein, D.; Prodell, A.G.

1979-01-01

Construction of a slow external beam switchyard at the BNL AGS requires a rapid 20.4 0 bend in the upstream end of the beam line. Two curved superconducting window dipole magnets, operating at 6.0 T and about 80% of short sample magnetic field, will be utilized with two small superconducting sextupoles to provide the necessary deflection for a 28.5 GeV/c primary proton beam. Because the magnets will operate in a primary proton beam environment, they are designed to absorb large amounts of radiation heating from the beam without quenching. The field quality of the superconducting magnets is extremely good. Computer field calculations indicate a field error, ΔB/B 0 , equivalent to approx. = 1 x 10 -4 up to 75% of the 8.26 cm full aperture diameter in the magnet

External beam radiotherapy alone in advanced esophageal cancer

Energy Technology Data Exchange (ETDEWEB)

Ahn, Sung Ja; Chung, Woong Ki; Nah, Byung Sik; Nam, Taek Keun [College of Medicine, Chonnam National Univ., Kwangju (Korea, Republic of)

1999-09-01

We performed the retrospective analysis to find the outcome of external beam radiotherapy alone in advanced esophageal cancer patients. One hundred and six patients treated with external beam radiotherapy alone between July 1990 and December 1996 were analyzed retrospectively. We limited the site of the lesions to the thoracic esophagus and cell type to the squamous cell carcinoma. Follow-up was completed in 100 patients (94%) and ranged from 1 month to 92 months (median; 6 months). The median age was 62 years old and male to female ratio was 104:2. Fifty-three percent was the middle thorax lesion and curative radiotherapy was performed in 83%. Mean tumor dose delivered with curative aim was 58.6 Gy (55-70.8 Gy) and median duration of the radiation therapy was days. The median survival of all patients was 6 months and 1-year and 2-year overall survival rate was 27% and 12%, respectively. Improvement of dysphagia was obtained in most patients except for 7 patients who underwent feeding gastrostomy. The complete response rate immediately after radiation therapy was 32% (34/106). The median survival and 2-year survival rate of the complete responder was 14 months and 30% respectively, while those of the nonresponder was 4 months and 0% respectively (p=0.000). The median survival and 2-year survival rate of the patients who could tolerate regular diet was 9 months and 16% while those of the patients who could not tolerate regular diet was 3 months and 0%, respectively (p=0.004). The survival difference between the patients with 5 cm or less tumor length and those with more than 5 cm tumor length was marginally statistically significant (p=0.06). However, the survival difference according to the periesophageal invasion or mediastinal lymphadenopathy in the chest CT imaging study was not statistically significant in this study. In a multivariate analysis, the statistically significant covariates to the survival were complete response to radiotherapy, tumor, length, and

Influence of boost technique (external beam radiotherapy or brachytherapy) on the outcome of patients with carcinoma of the base of the tongue

International Nuclear Information System (INIS)

Regueiro, C.A.; Millan, I.; Torre, A. de la; Valcarcel, F.J.; Magallon, R.; Fernandez, E.; Aragon, G.

1995-01-01

We reviewed 90 patients with squamous cell carcinoma of the base of the tongue. Fifty-three patients were treated with external beam radiotherapy alone (3 T1, 11 T2, 21 T3, and 18 T4 tumors) and thirty-seven patients were treated with external beam radiotherapy plus brachytherapy boost (4 T1, 15 T2, 11 T3, and 7 T4 tumors). For patients with T1, T2 and T3 primaries, the actuarial 3-year local relapse-free survival was 42% following external beam radiotherapy alone and 67% following external beam radiotherapy plus brachytherapy (p<0.05). The actuarial 3-year cause specific survival for these T-stages was 37% for patients treated with external beam radiotherapy alone and 53% for patients treated with external beam radiotherapy plus brachytherapy (p=0.1). In the Cox multivariate analyses restricted patients with T1, T2 and T3 staged tumors, treatment modality was the only predictor for local control but no influence on specific survival was found. The trend towards significant differences in specific survival found in the univariate comparison of both treatment modalities was probably due to the significantly higher number of N-positive patients treated with external beam radiotherapy alone. When all stages were included in the Cox analysis, low hemoglobin level, invasion of deep muscle, number of palpable nodes, and history of weight loss significantly influenced the outcome. Soft tissue necrosis occurred more frequently in patients treated with external beam radiotherapy plus brachytherapy (33% vs. 10%, p=0.52). (orig.)

Target volume delineation in external beam partial breast irradiation: less inter-observer variation with preoperative- compared to postoperative delineation

NARCIS (Netherlands)

Leij, F. van der; Elkhuizen, P.H.M.; Janssen, T.M.; Poortmans, P.M.P.; Sangen, M. van der; Scholten, A.N.; Vliet-Vroegindeweij, C. van; Boersma, L.J.

2014-01-01

The challenge of adequate target volume definition in external beam partial breast irradiation (PBI) could be overcome with preoperative irradiation, due to less inter-observer variation. We compared the target volume delineation for external beam PBI on preoperative versus postoperative CT scans of

Severe dry-eye syndrome following external beam irradiation

International Nuclear Information System (INIS)

Parsons, J.T.; Bova, F.J.; Million, R.R.

1994-01-01

There are limited data in the literature on the probability of dry-eye complications according to radiotherapy dose. This study investigates the risk of radiation-induced severe dry-eye syndrome in patients in whom an entire orbit was exposed to fractionated external beam irradiation. Between October 1964 and May 1989, 33 patients with extracranial head and neck tumors received irradiation of an entire orbit. Most patients were treated with 60 Co. The dose to the lacrimal apparatus was calculated at a depth of 1 cm from the anterior skin surface, the approximate depth of the major lacrimal gland. The end point of the study was severe dry-eye syndrome sufficient to produce visual loss secondary to corneal opacification, ulceration, or vascularization. Twenty patients developed severe dry-eye syndrome. All 17 patients who received dose ≥57Gy developed severe dry-eye syndrome. Three (19%) of 16 patients who received doses ≥45 Gy developed severe dry-eye syndrome; injuries in the latter group were much more slower to develop (4 to 11 years) than in the higher dose group, in whom corneal vascularization and opacification were usually pronounced within 9-10 months. There were no data for the range of doses between 45.01 and 56.99 Gy. The data did not suggest an increased risk of severe dry-eye syndrome with increasing age. Data from the current series and the literature are combined to construct a sigmoid dose response curve. The incidence of injury increases from 0% reported after doses ≥30 Gy to 100% after doses ≥57 Gy. 13 refs., 3 figs., 5 tabs

Flexural Behavior of RC Members Using Externally Bonded Aluminum-Glass Fiber Composite Beams

Directory of Open Access Journals (Sweden)

Ki-Nam Hong

2014-03-01

Full Text Available This study concerns improvement of flexural stiffness/strength of concrete members reinforced with externally bonded, aluminum-glass fiber composite (AGC beams. An experimental program, consisting of seven reinforced concrete slabs and seven reinforced concrete beams strengthened in flexure with AGC beams, was initiated under four-point bending in order to evaluate three parameters: the cross-sectional shape of the AGC beam, the glass fiber fabric array, and the installation of fasteners. The load-deflection response, strain distribution along the longitudinal axis of the beam, and associated failure modes of the tested specimens were recorded. It was observed that the AGC beam led to an increase of the initial cracking load, yielding load of the tension steels and peak load. On the other hand, the ductility of some specimens strengthened was reduced by more than 50%. The A-type AGC beam was more efficient in slab specimens than in beam specimens and the B-type was more suitable for beam specimens than for slabs.

External beam monitoring of the Cyclone 30 cyclotron of IPEN-CNEN-SP

International Nuclear Information System (INIS)

Matsuda, Hylton

2002-01-01

Due to the increasing demand for cyclotron radioisotopes and the high cost of equipment and materials involved in the process, it becomes evident the importance of external beam monitoring of the cyclotron. In this way, the beam of the Cyclone 30 cyclotron of IPEN-CNEN/S P was characterized throughout the evaluation of its current intensity, profile (position, focus and geometry), alignment and homogeneity, by measuring currents, temperatures and pressures of irradiation systems. For this purpose, techniques and conventional devices, thermocouples and pressure sensors associated to electronic of instrumentation, and technology and flexibility of micro controllers allowed observing the beam behavior during irradiations in real time. The ion beam energy was also evaluated using activation analysis technique of monitor reactions in nat Cu. The beam monitoring systems have been contributing to prevent material damages and they have already been used in routine irradiations, bringing important advantages in the process of beam optimization of the Cyclone 30. (author)

A comparative study for different shielding material composition and beam geometry applied to PET facilities: simulated transmission curves

Energy Technology Data Exchange (ETDEWEB)

Hoff, Gabriela [Pontificia Univ. Catolica do Rio Grande do Sul (PUCRS), Porto Alegre, RS (Brazil). Grupo de Experimentacao e Simulacao Computacional em Fisica Medica; Costa, Paulo Roberto, E-mail: pcosta@if.usp.br [Universidade de Sao Paulo (IF/USP), SP (Brazil). Dept. de Fisica Nuclear. Lab. de Dosimetria das Radiacoes e Fisica Medica

2013-03-15

The aim of this work is to simulate transmission data for different beam geometry and material composition in order to evaluate the effect of these parameters on transmission curves. The simulations are focused on outgoing spectra for shielding barriers used in PET facilities. The behavior of the transmission was evaluated as a function of the shielding material composition and thickness using Geant4 Monte Carlo code, version 9.2 p 03.The application was benchmarked for barited mortar and compared to The American Association of Physicists in Medicine (AAPM) data for lead. Their influence on the transmission curves as well the study of the influence of the shielding material composition and beam geometry on the outgoing spectra were performed. Characteristics of transmitted spectra, such as shape, average energy and Half-Value Layer (HVL), were also evaluated. The Geant4 toolkit benchmark for the energy resulting from the positron annihilation phenomena and its application in transmission curves description shown good agreement between data published by American Association on Physicists in Medicine task group 108 and experimental data published by Brazil. The transmission properties for different material compositions were also studied and have shown low dependency with the considered thicknesses. The broad and narrow beams configuration presented significant differences on the result. The fitting parameter for determining the transmission curves equations, according to Archer model is presented for different material. As conclusion were defined that beam geometry has significant influence and the composition has low influence on transmission curves for shielding design for the range of energy applied to PET. (author)

A comparative study for different shielding material composition and beam geometry applied to PET facilities: simulated transmission curves

International Nuclear Information System (INIS)

Hoff, Gabriela; Costa, Paulo Roberto

2013-01-01

The aim of this work is to simulate transmission data for different beam geometry and material composition in order to evaluate the effect of these parameters on transmission curves. The simulations are focused on outgoing spectra for shielding barriers used in PET facilities. The behavior of the transmission was evaluated as a function of the shielding material composition and thickness using Geant4 Monte Carlo code, version 9.2 p 03.The application was benchmarked for barited mortar and compared to The American Association of Physicists in Medicine (AAPM) data for lead. Their influence on the transmission curves as well the study of the influence of the shielding material composition and beam geometry on the outgoing spectra were performed. Characteristics of transmitted spectra, such as shape, average energy and Half-Value Layer (HVL), were also evaluated. The Geant4 toolkit benchmark for the energy resulting from the positron annihilation phenomena and its application in transmission curves description shown good agreement between data published by American Association on Physicists in Medicine task group 108 and experimental data published by Brazil. The transmission properties for different material compositions were also studied and have shown low dependency with the considered thicknesses. The broad and narrow beams configuration presented significant differences on the result. The fitting parameter for determining the transmission curves equations, according to Archer model is presented for different material. As conclusion were defined that beam geometry has significant influence and the composition has low influence on transmission curves for shielding design for the range of energy applied to PET. (author)

Elemental analysis of artefacts - establishing external beam PIXE

International Nuclear Information System (INIS)

Alves, A.; Johnston, P.; Short, R.; Bubb, I.

1999-01-01

The development of an external PIXE facility on the 1 MV Tandetron accelerator at RMIT has led to a wide range of research possibilities. A proton beam, generated inside a vacuum is brought into air via an Au coated Kapton foil exit window (thickness 8μm, diameter 0.35mm). Monitoring of the beam intensity is achieved by detecting backscattered protons from the inside Au coating on the window. Artefacts, which may be too large to be placed inside the vacuum, are positioned in the beamline opposite the exit window. An optical system consisting of a CCD camera, alignment laser and two mirrors allows viewing of a region of the target 10mm x 10mm. This technique provides quantitative analysis of elements in the pigments used in paintings and on ceramics, which is a valuable tool in art conservation and authentication. Application of the technique to a ceramic sample from the historic house 'Viewbank' is described

Radiotherapy in poor risk patients with stage I cancer of the endometrium: results of not giving external beam radiotherapy.

Science.gov (United States)

DeCruze, B; Guthrie, D

1999-01-01

Poor prognosis (poorly differentiated and/or deep myometrial invasion) Stage I endometrial cancer can have a relapse rate as high as 50%. Traditionally, most clinical oncologists treat these patients with external beam radiotherapy after surgery but there is no evidence to show that this improves survival. The retrospective study looks at the results of not giving external beam radiotherapy in 25 consecutive patients and compares the results with a group of 13 consecutive patients who did have such treatment. The two groups were comparable with regard to age, degree of differentiation and degree of invasion. Survival was comparable in the two groups. There is no evidence of any obvious decrease in survival from withholding external beam radiotherapy, but this was not a prospective randomized controlled trial. This study illustrates that it is essential that the Medical Research Council ASTEC trial should be supported because this will determine the true place of external beam radiotherapy in such patients.

Development of an external beam nuclear microprobe on the Aglae facility of the Louvre museum

Energy Technology Data Exchange (ETDEWEB)

Calligaro, T.; Dran, J.-C. E-mail: dran@culture.fr; Ioannidou, E.; Moignard, B.; Pichon, L.; Salomon, J

2000-03-01

The external beam line of our facility has been recently equipped with the focusing system previously mounted on a classical nuclear microprobe. When using a 0.1 {mu}m thick Si{sub 3}N{sub 4} foil for the exit window and flowing helium on the sample under analysis, a beam spot as small as 10 {mu}m is attainable at a distance of 3 mm from the window. Elemental micromapping is performed by mechanical scanning. An electronic device has been designed which allows XY scanning by moving the sample under the beam by steps down to 0.1 {mu}m. Beam monitoring is carried out by means of the weak X-ray signal emitted by the exit foil and detected by a specially designed Si(Li) detector cooled by Peltier effect. The characteristics of external beams of protons and alpha particles are evaluated by means of resonance scanning and elemental mapping of a grid. An example of application is presented, dealing with elemental micro-mapping of inclusions in gemstones.

Rigid body displacement fields of an in-plane-deformable curved beam based on conventional strain definition

International Nuclear Information System (INIS)

Moon, Won Joo; Min, Oak Key; Kim, Yong Woo

1998-01-01

To improve the convergence and the accuracy of a finite element, the finite element has to describe not only displacement and stress distributions in a static analysis but also rigid body displacements. In this paper, we consider the in-plane-deformable curved beam element to understand the descriptive capability of rigid body displacements of a finite element. We derive the rigid body displacement fields of a single finite element under various essential boundary conditions when the nodal displacements are caused by the rigid body displacement. We also examine the rigid body displacement fields of a quadratic curved beam element by employing the reduced minimization theory

Target volume delineation in external beam partial breast irradiation: Less inter-observer variation with preoperative- compared to postoperative delineation

International Nuclear Information System (INIS)

Leij, Femke van der; Elkhuizen, Paula H.M.; Janssen, Tomas M.; Poortmans, Philip; Sangen, Maurice van der; Scholten, Astrid N.; Vliet-Vroegindeweij, Corine van; Boersma, Liesbeth J.

2014-01-01

The challenge of adequate target volume definition in external beam partial breast irradiation (PBI) could be overcome with preoperative irradiation, due to less inter-observer variation. We compared the target volume delineation for external beam PBI on preoperative versus postoperative CT scans of twenty-four breast cancer patients

Dose-effect curves for electron-beam irradiation of some collection microbial strains

International Nuclear Information System (INIS)

Ferdes, O.; Dumitru, E.; Catargiu, L.; Ferdes, M.; Minea, R.; Oproiu, C.; Niculescu, A.

1994-01-01

There were electron-beam irradiated some microbial strains of B.subtilis ICA I-60 both in germination and in sporulated forms. The irradiation were performed at the IPTRD's electron accelerator at 6 MeV, and in the dose range between 0.1-5.0 kGy, at different dose-rate varying from 50 Gy/minute to 100 Gy/minute. The dosimetry was carried out by a PTW medical dosemeter. There were established the dose-effect relationships and curves, the inactivation dose (factor) and the optimum domain for electron-beam mutagenesis. There were obtained some mutant strains with 2-3.5 higher biosynthesis potential, which are in the IFC's collection. (Author)

Distortion of optical feedback signals in microchip Nd:YAG lasers subjected to external multi-beam interference feedback

International Nuclear Information System (INIS)

Yi-Dong, Tan; Shu-Lian, Zhang; Zhou, Ren; Cheng, Ren; Yi-Nan, Zhang

2010-01-01

This paper proposes a theoretical analysis for the characteristics of an external cavity Nd:YAG laser with feedback of multiple-beam interference, which is induced by the multi-reentrance of the light from the external Fabry–Perot cavity. The theoretical model considers the multiple beam interference of the external Fabry–Perot cavity. It is found that the optical feedback signals are distorted to pulse waveforms instead of the sinusoidal ones in conventional feedback. The experimental results are in good agreement with the theoretical analysis. The obtained theoretical and experimental results can advance the development of a laser feedback interferometer

External Beam Radiotherapy for Carcinoma of the Extrahepatic Biliary System

International Nuclear Information System (INIS)

Chun, Ha Chung; Lee, Myung Za

1996-01-01

Purpose : To evaluate the effectiveness and tolerance of patients of external beam radiotherapy of carcinoma of the extrahepatic biliary system (EHBS) including gall bladder (GB) and extrahepatic bile ducts (EHBD) and to define the role of radiotherapy for these tumors. Methods and Materials : We retrospectively analyzed the records of 43 patients with carcinoma of the EHBS treated with external beam radiotherapy at our institution between April, 1986 and July, 1994. Twenty three patients had GB cancers and remaining 20 patients did EHBD cancers. Of those 23 GB cancers, 2 had Stage II, 12 did Stage III and 9 did Stage IV disease, respectively. Male to female ratio was 11 to 12. Fifteen patients underwent radical surgery with curative intent and 8 patients did biopsy and bypass surgery alone. Postoperatively 16 patients were irradiated with 4500 cGy or higher doses and 4 patients with 3180 to 4140 cGy. Follow up periods ranged from 8 to 34 months. Results : overall median survival time of patients with GB cancer was 11 months. Median survival time for patients with Stage III and IV disease were 14 months and 5 months, respectively. Corresponding two year survival rates were 36%(4/11) and 13%(1/8), respectively. Those who underwent surgery with curative intent showed significantly better survival at 12 months than those who underwent bypass surgery alone(67% vs 13%). None of the patients died of treatment related complications. Median survival time for entire group of 20 EHBD patients was 10 months. Median survivals of 10 Stage III and 7 Stage IV disease were 10 and 8 months, respectively. Two patients who underwent Whipple's procedure had 11 and 14 month survival and those treated with resection and drainage showed median survival of 10 month. Conclusion : Postoperative external beam radiotherapy for carcinoma of the extrahepatic billary system is well tolerated and might improve survival of patients. especially those with respectable lesions with microscopic or

Flexural behaviour of RCC beams with externally bonded FRP

Science.gov (United States)

Vignesh, S. Arun; Sumathi, A.; Saravana Raja Mohan, K.

2017-07-01

The increasing use of carbon and glass fibre reinforced polymer (FRP) sheets for strengthening existing reinforced concrete beams has generated considerable interest in understanding the behavior of the FRP sheets when subjected to bending. The study on flexure includes various parameters like percentage of increase in strength of the member due to the externally bonded Fiber reinforced polymer, examining the crack patterns, reasons of debonding of the fibre from the structure, scaling, convenience of using the fibres, cost effectiveness etc. The present work aims to study experimentally about the reasons behind the failure due to flexure of an EB-FRP concrete beam by studying the various parameters. Deflection control may become as important as flexural strength for the design of FRPreinforced concrete structures. A numerical model is created using FEM software and the results are compared with that of the experiment.

Effect of external magnetic field on critical current for the onset of virtual cathode oscillations in relativistic electron beams

International Nuclear Information System (INIS)

Hramov, Alexander; Koronovskii, Alexey; Morozov, Mikhail; Mushtakov, Alexander

2008-01-01

In this Letter we research the space charge limiting current value at which the oscillating virtual cathode is formed in the relativistic electron beam as a function of the external magnetic field guiding the beam electrons. It is shown that the space charge limiting (critical) current decreases with growth of the external magnetic field, and that there is an optimal induction value of the magnetic field at which the critical current for the onset of virtual cathode oscillations in the electron beam is minimum. For the strong external magnetic field the space charge limiting current corresponds to the analytical relation derived under the assumption that the motion of the electron beam is one-dimensional [D.J. Sullivan, J.E. Walsh, E. Coutsias, in: V.L. Granatstein, I. Alexeff (Eds.), Virtual Cathode Oscillator (Vircator) Theory, in: High Power Microwave Sources, vol. 13, Artech House Microwave Library, 1987, Chapter 13]. Such behavior is explained by the characteristic features of the dynamics of electron space charge in the longitudinal and radial directions in the drift space at the different external magnetic fields

Unified model to predict flexural shear behavior of externally bonded RC beams

International Nuclear Information System (INIS)

Colotti, V.; Spadea, G.; Swamy, R.N.

2006-01-01

Structural strengthening with externally bonded reinforcement is now recognized as a cost-effective, structurally sound and practically efficient method of rehabilitating deteriorating and damaged reinforced concrete beams. There is now an urgent need to develop a sound engineering basis which can predict the failure loads of all such strengthened beams in a reliable and consistent manner. Existing models to predict the behavior at ultimate of strengthened beams suffer from many limitations and weaknesses. This paper presents a unified global model, based on the Strut-and-Tie approach, to predict the failure loads of reinforced concrete beams strengthened for flexure and/or shear. This structural model is based on rational engineering principles, considers all the possible failure modes, and incorporates the load transfer mechanism bond to reflect the debonding phenomena which has a dominant influence on the failure process of plated beams. The model is validated against about 200 strengthened beam test reported in the literature and failing in flexure and/or shear, involving a large number of structural variables and steel, carbon and glass fiber reinforced polymer laminates as reinforcing medium. (author)

External post-operational checks for the LHC beam dumping system

International Nuclear Information System (INIS)

Magnin, N.; Baggiolini, V.; Carlier, E.; Goddard, B.; Gorbonosov, R.; Khasbulatov, D.; Uythoven, J.; Zerlauth, M.

2012-01-01

The LHC Beam Dumping System (LBDS) is a critical part of the LHC machine protection system. After every LHC beam dump action the various signals and transient data recordings of the beam dumping control systems and beam instrumentation measurements are automatically analysed by the external Post-Operational Checks (XPOC) system to verify the correct execution of the dump action and the integrity of the related equipment. This software system complements the LHC machine protection hardware, and has to ascertain that the beam dumping system is 'as good as new' before the start of the next operational cycle. This is the only way by which the stringent reliability requirements can be met. The XPOC system has been developed within the framework of the LHC 'Post-Mortem' system, allowing highly dependable data acquisition, data archiving, live analysis of acquired data and replay of previously recorded events. It is composed of various analysis modules, each one dedicated to the analysis of measurements coming from specific equipment. This paper describes the global architecture of the XPOC system and gives examples of the analyses performed by some of the most important analysis modules. It explains the integration of the XPOC into the LHC control infrastructure along with its integration into the decision chain to allow proceeding with beam operation. Finally, it discusses the operational experience with the XPOC system acquired during the first years of LHC operation, and illustrates examples of internal system faults or abnormal beam dump executions which it has detected. (authors)

T2-weighted endorectal magnetic resonance imaging of prostate cancer after external beam radiation therapy

International Nuclear Information System (INIS)

Westphalen, Antonio C.; Kurhanewicz, John; Cunha, Rui M.G.; Hsu, I-Chow; Kornak, John; Zhao, Shoujun; Coakley, Fergus V.

2009-01-01

Purpose: To retrospectively determine the accuracy of T2-weighted endorectal MR imaging in the detection of prostate cancer after external beam radiation therapy and to investigate the relationship between imaging accuracy and time since therapy. Materials and Methods: Institutional review board approval was obtained and the study was HIPPA compliant. We identified 59 patients who underwent 1.5 Tesla endorectal MR imaging of the prostate between 1999 and 2006 after definitive external beam radiation therapy for biopsy-proven prostate cancer. Two readers recorded the presence or absence of tumor on T2-weighted images. Logistic regression and Fisher's exact tests for 2x2 tables were used to determine the accuracy of imaging and investigate if accuracy differed between those imaged within 3 years of therapy (n = 25) and those imaged more than 3 years after therapy (n = 34). Transrectal biopsy was used as the standard of reference for the presence or absence of recurrent cancer. Results: Thirty-four of 59 patients (58%) had recurrent prostate cancer detected on biopsy. The overall accuracy of T2-weighted MR imaging in the detection cancer after external beam radiation therapy was 63% (37/59) for reader 1 and 71% for reader 2 (42/59). For both readers, logistic regression showed no difference in accuracy between those imaged within 3 years of therapy and those imaged more than 3 years after therapy (p = 0.86 for reader 1 and 0.44 for reader 2). Conclusion: T2-weighted endorectal MR imaging has low accuracy in the detection of prostate cancer after external beam radiation therapy, irrespective of the time since therapy. (author)

Shear Strengthening of RC Deep Beam Using Externally Bonded GFRP Fabrics

Science.gov (United States)

Kumari, A.; Patel, S. S.; Nayak, A. N.

2018-06-01

This work presents the experimental investigation of RC deep beams wrapped with externally bonded Glass Fibre Reinforced Polymer (GFRP) fabrics in order to study the Load versus deflection behavior, cracking pattern, failure modes and ultimate shear strength. A total number of five deep beams have been casted, which is designed with conventional steel reinforcement as per IS: 456 (Indian standard plain and reinforced concrete—code for practice, Bureau of Indian Standards, New Delhi, 2000). The spans to depth ratio for all RC deep beams have been kept less than 2 as per the above specification. Out of five RC deep beams, one without retrofitting serves as a reference beam and the rest four have been wrapped with GFRP fabrics in multiple layers and tested with two point loading condition. The first cracking load, ultimate load and the shear contribution of GFRP to the deep beams have been observed. A critical discussion is made with respect to the enhancement of the strength, behaviour and performance of retrofitted deep beams in comparison to the deep beam without GFRP in order to explore the potential use of GFRP for strengthening the RC deep beams. Test results have demonstrated that the deep beams retrofitted with GFRP shows a slower development of the diagonal cracks and improves shear carrying capacity of the RC deep beam. A comparative study of the experimental results with the theoretical ones predicted by various researchers available in the literatures has also been presented. It is observed that the ultimate load of the beams retrofitted with GFRP fabrics increases with increase of number of GFRP layers up to a specific number of layers, i.e. 3 layers, beyond which it decreases.

Propagation characteristics of a focused laser beam in a strontium barium niobate photorefractive crystal under reverse external electric field.

Science.gov (United States)

Guo, Q L; Liang, B L; Wang, Y; Deng, G Y; Jiang, Y H; Zhang, S H; Fu, G S; Simmonds, P J

2014-10-01

The propagation characteristics of a focused laser beam in a SBN:75 photorefractive crystal strongly depend on the signal-to-background intensity ratio (R=Is/Ib) under reverse external electric field. In the range 20>R>0.05, the laser beam shows enhanced self-defocusing behavior with increasing external electric field, while it shows self-focusing in the range 0.03>R>0.01. Spatial solitons are observed under a suitable reverse external electric field for R=0.025. A theoretical model is proposed to explain the experimental observations, which suggest a new type of soliton formation due to "enhancement" not "screening" of the external electrical field.

Strengthening of Reinforced Concrete Beam in Shear Zone by Compensation the Stirrups with Equivalent External Steel Plates

Directory of Open Access Journals (Sweden)

Khamail Abdul-Mahdi Mosheer

2016-09-01

Full Text Available An experimental study on reinforced concrete beams strengthened with external steel plates instead of shear stirrups has been held in this paper. Eight samples of the same dimensions and properties were used. Two of them were tested up to failure and specified as references beams; one with shear reinforcement and the other without shear reinforcement. Another samples without shear reinforcement were tested until the first shear crack occurs, then the samples strengthened on both sides with external steel plates as equivalent area of removed stirrups. The strengthened beams were divided into three groups according to the thickness of plates (1, 1.5, 2 mm, each group involved two beams; one bonded using epoxy and the other bonded using epoxy with anchored bolts. Finally, the strengthened beams tested when using anchored bolts with epoxy glue to bond plates. Where the increasing in maximum load is higher than that in reference beam with no internal stirrups reach to (75.46 –106.13% and has a good agreement with the control beam with shear reinforcement reach to (76.06 – 89.36% of ultimate load.

Measure of the attenuation curve of a beam of X-rays with TLD-100 dosimeters of LiF

International Nuclear Information System (INIS)

Bonzi, E. V.; Mainardi, R. T.; Germanier, A.; Delgado, V.

2011-10-01

The attenuation curve of a beam of X-rays represents the beam intensity in function of the attenuator thickness interposed between the source and the detector. To know with the major possible precision the attenuation curve is indispensable in procedures of spectral reconstruction. Their periodic measuring also offers valuable information on the correct operation of a tube of X-rays, diagnostic or therapy, when not have a specific detector for that activity. In this work was measured the attenuation curve of a tube of X-rays operated to 50 kV and 0.5 ma, using existent elements in any diagnostic or therapy laboratory with radiations. In the measures commercial aluminum foil was used, bent until 24 times and thermoluminescent dosimeters TLD 100 - LiF. Also, for comparison, was measured this attenuation curve with an ionization chamber brand Capintec model 192. Was determined by X-rays fluorescence the composition of the aluminium foil, since the present elements in the alloy can to affect the form of the attenuation curve. It is interesting to observe that these elements are in very low proportion (ppm) that they do not alter the attenuation capacity of the pure aluminium. Finally in a precision balance we weigh a big piece (30 cm x 100 cm) of aluminium foil and we obtained the thickness in g/c m2. It is possible to obtain attenuation curves of a beam of X-rays, with a high precision procedure and reproducibility. The use of TLD-100 dosimeters of LiF or similar makes that this activity was also quick and simple. (Author)

PIXE/PIGE characterisation of emeralds using an external micro-beam

International Nuclear Information System (INIS)

Calligaro, T.; Dran, J.-C.; Poirot, J.-P.; Querre, G.; Salomon, J.; Zwaan, J.C.

2000-01-01

A large collection of emeralds of various occurrences has been analysed by PIXE/PIGE in view to establish a compositional database. Major elements (Be, Si, Al) and trace elements (Li, F, Na, Mg, Ca, Rb, Cs and transition metals) are determined using an external 3 MeV proton micro-beam. Elemental micro-mapping permits to select the useful provenance tracers. This database was applied to infer the origin of several ancient emeralds set on historical jewels

SU-E-J-181: Effect of Prostate Motion On Combined Brachytherapy and External Beam Dose Based On Daily Motion of the Prostate

Energy Technology Data Exchange (ETDEWEB)

Narayana, V; McLaughlin, P [Providence Cancer Center, Southfield, MI (United States); University of Michigan, Ann Arbor, MI (United States); Ealbaj, J [University of Michigan, Ann Arbor, MI (United States)

2015-06-15

Purpose: In this study, the adequacy of target expansions on the combined external beam and implant dose was examined based on the measured daily motion of the prostate. Methods: Thirty patients received an I–125 prostate implant prescribed to dose of 90Gy. This was followed by external beam to deliver a dose of 90Gyeq (external beam equivalent) to the prostate over 25 to 30 fractions. An ideal IMRT plan was developed by optimizing the external beam dose based on the delivered implant dose. The implant dose was converted to an equivalent external beam dose using the linear quadratic model. Patients were set up on the treatment table by daily orthogonal imaging and aligning the marker seeds in the prostate. Orthogonal images were obtained at the end of treatment to assess prostate intrafraction motion. Based on the observed motion of the markers between the initial and final images, 5 individual plans showing the actual dose delivered to the patient were calculated. A final true dose distribution was established based on summing the implant dose and the 5 external beam plans. Dose to the prostate, seminal vesicles, lymphnodes and normal tissues, rectal wall, urethra and lower sphincter were calculated and compared to ideal. On 18 patients who were sexually active, dose to the corpus cavernosum and internal pudendal artery was also calculated. Results: The average prostate motion in 3 orthogonal directions was less than 1 mm with a standard deviation of less than +2 mm. Dose and volume parameters showed that there was no decrease in dose to the targets and a marginal decrease in dose to in normal tissues. Conclusion: Dose delivered by seed implant moves with the prostate, decreasing the impact of intrafractions dose movement on actual dose delivered. Combined brachytherapy and external beam dose delivered to the prostate was not sensitive to prostate motion.

The effect of combined external beam and high-dose intracavitary brachytherapy on dysphagia and survival in patients with advanced esophageal cancer

International Nuclear Information System (INIS)

Yorozu, Atsunori; Dokiya, Takushi; Ogita, Mikio; Kutsuki, Shoji

1996-01-01

During an 11-year period, a group of 130 patients with esophageal cancer of stages 2 to 4 were treated with external beam irradiation (40 to 60 Gy) followed by boost dose of 10 to 20 Gy of high-dose intracavitary brachytherapy. The overall 2-year survival rate was 15.4%. The significant prognostic factors were tumor size, response to external beam irradiation, pretreatment dysphagia score, and presence of distant metastases. The palliative effect was excellent; the dysphagia scores of 122 of 130 patients (93.8%) improved. The significant palliative factors were response to external beam irradiation and pretreatment dysphagia score. Tracheoesophageal fistulas developed after treatment in 13 of 130 patients (10%); 3 of the fistulas were probably related to radiotherapy. We conclude that intracavitary brachytherapy is useful in the treatment of cases of advanced cancer which show a good response to external beam irradiation and may be curative in patients with mild dysphagia. (author)

Accuracy of digital peripical radiography and cone-beam computed tomography in detecting external root resorption

Energy Technology Data Exchange (ETDEWEB)

Creanga, Adriana Gabriela [Division of Dental Diagnostic Science, Rutgers School of Dental Medicine, Newark (United States); Geha, Hassem; Sankar, Vidya; Mcmahan, Clyde Alex; Noujeim, Marcel [University of Texas Health Science Center San Antonio, San Antonio (United States); Teixeira, Fabrico B. [Dept. of Endodontics, University of Iowa, Iowa City (United States)

2015-09-15

The purpose of this study was to evaluate and compare the efficacy of cone-beam computed tomography (CBCT) and digital intraoral radiography in diagnosing simulated small external root resorption cavities. Cavities were drilled in 159 roots using a small spherical bur at different root levels and on all surfaces. The teeth were imaged both with intraoral digital radiography using image plates and with CBCT. Two sets of intraoral images were acquired per tooth: orthogonal (PA) which was the conventional periapical radiograph and mesioangulated (SET). Four readers were asked to rate their confidence level in detecting and locating the lesions. Receiver operating characteristic (ROC) analysis was performed to assess the accuracy of each modality in detecting the presence of lesions, the affected surface, and the affected level. Analysis of variation was used to compare the results and kappa analysis was used to evaluate interobserver agreement. A significant difference in the area under the ROC curves was found among the three modalities (P=0.0002), with CBCT (0.81) having a significantly higher value than PA (0.71) or SET (0.71). PA was slightly more accurate than SET, but the difference was not statistically significant. CBCT was also superior in locating the affected surface and level. CBCT has already proven its superiority in detecting multiple dental conditions, and this study shows it to likewise be superior in detecting and locating incipient external root resorption.

Interfacial stresses in damaged RC beams strengthened with externally bonded CFRP plate

International Nuclear Information System (INIS)

Benrahou, K.H.; Adda bedia, E.A.; Benyoucef, S.; Tounsi, A.; Benguediab, M.

2006-01-01

A theoretical method to predict the interfacial stresses in the adhesive layer of damaged reinforced concrete beams strengthened with externally bonded carbon fiber-reinforced polymer (CFRP) plate is presented. The adopted model is developed including the adherend shear deformations by assuming a linear shear stress through the depth of the RC beam [A. Tounsi, Int. J. Solids Struct., in press], while all existing solutions neglect this effect [e.g. S. Benyoucef, A. Tounsi, S.A. Meftah, E.A. Adda Bedia, Compos. Interfaces, in press; S.T. Smith, J.G. Teng, Eng. Struct. 23 (7) (2001) 857-871; T.M. Roberts, Struct. Eng. 67 (12) (1989) 229-233; A. Tounsi, S. Benyoucef, Int. J. Adhes. Adhes., in press; T. Stratford, J. Cadei, Construct. Building Mater. 20 (2006) 34-35]. In addition, in the present study the anisotropic damage model is adopted to describe the damage of the RC beams. It is shown that the damage has a significant effect on the interfacial stresses in FRP-damaged RC beam

Stability of aerosol droplets in Bessel beam optical traps under constant and pulsed external forces

International Nuclear Information System (INIS)

David, Grégory; Esat, Kıvanç; Hartweg, Sebastian; Cremer, Johannes; Chasovskikh, Egor; Signorell, Ruth

2015-01-01

We report on the dynamics of aerosol droplets in optical traps under the influence of additional constant and pulsed external forces. Experimental results are compared with simulations of the three-dimensional droplet dynamics for two types of optical traps, the counter-propagating Bessel beam (CPBB) trap and the quadruple Bessel beam (QBB) trap. Under the influence of a constant gas flow (constant external force), the QBB trap is found to be more stable compared with the CPBB trap. By contrast, under pulsed laser excitation with laser pulse durations of nanoseconds (pulsed external force), the type of trap is of minor importance for the droplet stability. It typically needs pulsed laser forces that are several orders of magnitude higher than the optical forces to induce escape of the droplet from the trap. If the droplet strongly absorbs the pulsed laser light, these escape forces can be strongly reduced. The lower stability of absorbing droplets is a result of secondary thermal processes that cause droplet escape

Stability of aerosol droplets in Bessel beam optical traps under constant and pulsed external forces

Energy Technology Data Exchange (ETDEWEB)

David, Grégory; Esat, Kıvanç; Hartweg, Sebastian; Cremer, Johannes; Chasovskikh, Egor; Signorell, Ruth, E-mail: rsignorell@ethz.ch [Laboratory of Physical Chemistry, ETH Zürich, Vladimir-Prelog-Weg 2, CH-8093 Zürich (Switzerland)

2015-04-21

We report on the dynamics of aerosol droplets in optical traps under the influence of additional constant and pulsed external forces. Experimental results are compared with simulations of the three-dimensional droplet dynamics for two types of optical traps, the counter-propagating Bessel beam (CPBB) trap and the quadruple Bessel beam (QBB) trap. Under the influence of a constant gas flow (constant external force), the QBB trap is found to be more stable compared with the CPBB trap. By contrast, under pulsed laser excitation with laser pulse durations of nanoseconds (pulsed external force), the type of trap is of minor importance for the droplet stability. It typically needs pulsed laser forces that are several orders of magnitude higher than the optical forces to induce escape of the droplet from the trap. If the droplet strongly absorbs the pulsed laser light, these escape forces can be strongly reduced. The lower stability of absorbing droplets is a result of secondary thermal processes that cause droplet escape.

Stability of aerosol droplets in Bessel beam optical traps under constant and pulsed external forces.

Science.gov (United States)

David, Grégory; Esat, Kıvanç; Hartweg, Sebastian; Cremer, Johannes; Chasovskikh, Egor; Signorell, Ruth

2015-04-21

We report on the dynamics of aerosol droplets in optical traps under the influence of additional constant and pulsed external forces. Experimental results are compared with simulations of the three-dimensional droplet dynamics for two types of optical traps, the counter-propagating Bessel beam (CPBB) trap and the quadruple Bessel beam (QBB) trap. Under the influence of a constant gas flow (constant external force), the QBB trap is found to be more stable compared with the CPBB trap. By contrast, under pulsed laser excitation with laser pulse durations of nanoseconds (pulsed external force), the type of trap is of minor importance for the droplet stability. It typically needs pulsed laser forces that are several orders of magnitude higher than the optical forces to induce escape of the droplet from the trap. If the droplet strongly absorbs the pulsed laser light, these escape forces can be strongly reduced. The lower stability of absorbing droplets is a result of secondary thermal processes that cause droplet escape.

Stability of aerosol droplets in Bessel beam optical traps under constant and pulsed external forces

Science.gov (United States)

David, Grégory; Esat, Kıvanç; Hartweg, Sebastian; Cremer, Johannes; Chasovskikh, Egor; Signorell, Ruth

2015-04-01

We report on the dynamics of aerosol droplets in optical traps under the influence of additional constant and pulsed external forces. Experimental results are compared with simulations of the three-dimensional droplet dynamics for two types of optical traps, the counter-propagating Bessel beam (CPBB) trap and the quadruple Bessel beam (QBB) trap. Under the influence of a constant gas flow (constant external force), the QBB trap is found to be more stable compared with the CPBB trap. By contrast, under pulsed laser excitation with laser pulse durations of nanoseconds (pulsed external force), the type of trap is of minor importance for the droplet stability. It typically needs pulsed laser forces that are several orders of magnitude higher than the optical forces to induce escape of the droplet from the trap. If the droplet strongly absorbs the pulsed laser light, these escape forces can be strongly reduced. The lower stability of absorbing droplets is a result of secondary thermal processes that cause droplet escape.

Nonlinear Analysis of External Prestressed Reinforced Concrete Beams with BFRP and CFRP

Directory of Open Access Journals (Sweden)

Haleem K. Hussain

2017-05-01

Full Text Available The traditional strengthening methods for concrete structure (girders, beams, columns…. consuming time and could be an economical, a new modern repair methods using the Carbon Fiber Reinforced Polymers (CFRP and Basalt Fiber Reinforced Polymer (BFRP as a laminate strips or bars,and considered a competitive solution that will increase the life-cycle of repaired structures. This study investigated the strengthen reinforced concrete girder. Nonlinear analysis have been adopted to the models using FEM analysis (ANSYS to simulate the theoretical results compared with experimental results.Using finite element packages, more efficient and better analyses can be made to fully understand the response of individual structural components and their contribution to a structure as a whole.Three type of material are used in this study as an external prestressed wire (steel, CFRP and BFRP. The prestressed beam is modeled as simply supported beam with two concentrated point load. The results showed that all tested strengthening beam increased the load carryingcapacity of the beams depend on prestressing force. Obtained Result was compared for different type of beam.This study also was enlarged to include using CFRP and BFRPbarwhich are light weight and moredurable, lead to ease of handling and maintenance. The research conducted analytical work to evaluate the effectiveness of concrete beams reinforced normally by the use of CFRP and BFRP bars. The results showed a significant gain in the beam’s ultimate capacities using CFRP bars comparing with beam reinforced with BFRP bar and reference beam

Wavelength beam combining of a 980-nm tapered diode laser bar in an external cavity

DEFF Research Database (Denmark)

Vijayakumar, Deepak; Jensen, Ole Bjarlin; Thestrup Nielsen, Birgitte

2010-01-01

solution for preserving the beam quality of the bar in the range of that of a single emitter and at the same time, enabling the power scaling. We report spectral beam combining applied to a 12 emitter tapered laser bar at 980 nm. The external cavity has been designed for a wavelength separation of 4.0 nm......High power diode lasers are used in a large number of applications. A limiting factor for more widespread use of broad area lasers is the poor beam quality. Gain guided tapered diode lasers are ideal candidates for industrial applications that demands watt level output power with good beam quality...

Charge collection in an external proton beam

International Nuclear Information System (INIS)

Wookey, C.W.; Somswasdi, B.; Rouse, J.L.

1982-01-01

Results from the measurement of the stability of charge collected from the target and exit foil, or as alternatives, the γ-ray or backscattered proton counts from the exit foil and the Ar X-ray counts from the air path in an external proton beam are presented. These results show that comparative analysis of material mounted in air is reliable, using either the collected charge or the γ-ray counts as the normalizing factor, if there are no earthed objects in close geometry. The backscattered proton counts can also be used, but not the Ar X-ray counts, unless the current is stabilized. The electrical or thermal conductivity of the target and the target to exit foil separation do not affect the proportionality of the collected charge and the γ-ray counts to the charge incident on the target

A curved beam test specimen for determining the interlaminar tensile strength of a laminated composite

Science.gov (United States)

Hiel, Clement C.; Sumich, Mark; Chappell, David P.

1991-01-01

A curved beam type of test specimen is evaluated for use in determining the through-the-thickness strength of laminated composites. Two variations of a curved beam specimen configuration (semicircular and elliptical) were tested to failure using static and fatigue loads. The static failure load for the semicircular specimens was found to be highly sensitive to flaw content, with the specimens falling into two distinct groups. This result supports the use of proof testing for structural validation. Static design allowables are derived based on the Weibull distribution. Fatigue data indicates no measured increase in specimen compliance prior to final fracture. All static and fatigue failures at room temperature dry conditions occurred catastrophically. The elliptical specimens demonstrated unusually high failure strengths indicating the presence of phenomena requiring further study. Results are also included for specimens exposed to a wet environment showing a matrix strength degradation due to moisture content. Further testing is underway to evaluate a fatigue methodology for matrix dominated failures based on residual static strength (wearout).

A phase I/II study of external beam radiation, brachytherapy and concurrent chemotherapy in localized cancer of the esophagus (RTOG 9207)

International Nuclear Information System (INIS)

Gaspar, L.E.; Qian, C.; Kocha, W.I.; Coia, L.R.; Herskovic, A.; Graham, M.

1996-01-01

Introduction: A multi-institutional, prospective study was designed to determine the feasibility and toxicity of chemotherapy, external beam irradiation and esophageal brachytherapy (EB) in a potentially curable group of patients with adenocarcinoma or squamous cell carcinoma of the esophagus. Methods: Planned treatment was 50 Gy external beam radiation (25 fractions/5 wks) followed 2 weeks later by EB (either HDR 5 Gy wks 8,9 and 10 for a total of 15 Gy or LDR 20 Gy wk 8). The protocol was later revised to delete the LDR alternative due to poor accrual and decrease the HDR dose to 10 Gy, ie 5 Gy wks 8 and 9. Chemotherapy was given wks 1,5,8 and 11 with DDP 75 mg/m2 and 5-FU 1000 mg/m2/24 hrs, 96 hour infusion. Data is available on 50 patients (46 squamous, 3 adenocarcinoma) treated on the HDR alternative (EB dose 15 Gy and 10 Gy in 40 and 10 patients, respectively. Results: Thirty-five patients (70%) were able to complete external beam, EB and at least 2 courses of chemotherapy. Estimated survival rate at 12 months is 48%. Life-threatening toxicity or death occurred in 13 (26%) and 4 (8%) patients, respectively. Treatment-related esophageal fistulas occurred in 6 patients (12%) at 0.5 to 6.2 months from the first day of brachytherapy, leading to death in 3. So far all treatment-related fistulas occurred in the 15 Gy EB group. Conclusions: Survival following this combination of chemotherapy, external beam radiation and EB does not appear to be different from survival seen following chemotherapy and external beam radiation only. Based on the high incidence of fistulas, we urge extreme caution in employing EB as a boost following concurrent chemotherapy and external beam radiation with the schema utilized in this prospective study

Evaluation of the learning curve for external cephalic version using cumulative sum analysis.

Science.gov (United States)

Kim, So Yun; Han, Jung Yeol; Chang, Eun Hye; Kwak, Dong Wook; Ahn, Hyun Kyung; Ryu, Hyun Mi; Kim, Moon Young

2017-07-01

We evaluated the learning curve for external cephalic version (ECV) using learning curve-cumulative sum (LC-CUSUM) analysis. This was a retrospective study involving 290 consecutive cases between October 2013 and March 2017. We evaluated the learning curve for ECV on nulli and over para 1 group using LC-CUSUM analysis on the assumption that 50% and 70% of ECV procedures succeeded by description a trend-line of quadratic function with reliable R 2 values. The overall success rate for ECV was 64.8% (188/290), while the success rate for nullipara and over para 1 groups was 56.2% (100/178) and 78.6% (88/112), respectively. 'H' value, that the actual failure rate does not differ from the acceptable failure rate, was -3.27 and -1.635 when considering ECV success rates of 50% and 70%, respectively. Consequently, in order to obtain a consistent 50% success rate, we would require 57 nullipara cases, and in order to obtain a consistent 70% success rate, we would require 130 nullipara cases. In contrast, 8 to 10 over para 1 cases would be required for an expected success rate of 50% and 70% on over para 1 group. Even a relatively inexperienced physician can experience success with multipara and after accumulating experience, they will manage nullipara cases. Further research is required for LC-CUSUM involving several practitioners instead of a single practitioner. This will lead to the gradual implementation of standard learning curve guidelines for ECV.

Influence of external beam technique and brachytherapy quality assurance on the side effects in the combined external beam- and brachytherapy treatment of local advanced prostate cancer

International Nuclear Information System (INIS)

Kovacs, G.; Galalae, R.; Wirth, B.; Bertermann, H.; Wilhelm, R.; Kohr, P.; Kimmig, B.

1996-01-01

Transrectal ultrasound(TRUS) guided HDR implantation of the prostate has been established at the Kiel University by Bertermann and Brix in 1986 and there are to date 179 (T1b-T3 No Mo) patients treated in a combined modality. The dose for the implant was 2x 15 Gy on the capsule of the prostate in 14-20 days. For local and regional lymph nodes 20 Gy external beam therapy (AP-PA pelvic portals), 20 Gy with an individual transmission block (100% for subclinical disease, 70% and 50% according to the implant dosimetry for the prostate) and 10 Gy small volume irradiation for the prostate was applied, conventional fractioned. Total dose after the therapy 70 Gy for the prostate and 50 Gy for the subclinical disease in 6-7 weeks. As a quality control method we use since 1991 in vivo dosimetry on the medial rectum wall as well as in the prostatic part of the urethra. Regular follow-up 3-118 months after therapy (median 55) with PSA, digital rectal examination, control TRUS with volumetry (after one year with biopsy) and bone scan. There were no major early side effects within the first three months. Proctitis till 1991 with a duration up to 12 months 49%, prolonging more than one year in 23 %, (total proctitis 72.6%). Dysuria in up to 12 months 30 %, long lasting 30% (total number of dysuria 60 %). Erectile dysfunction in 56 %. Because of the number of the side effects 1991 we changed the external beam technique: instead of the biaxial arch therapy the AP-PA portals, and reduced irradiated volume (from 6480 cm 3 to 5040 cm 3 ). We introduced instead of the small volume arch therapy for 10 Gy external boost the box-technique with shielding the back part of the rectum and the upper part of the bladder resulting additional volume reduction. Through the 15 Gy HDR brachytherapy dose on the prostate capsule there are up to 8 Gy on the medial rectal wall, measured by in vivo dosimetry. This dose could not be responsible for the high number of side effects (see gynecological

External beam radiotherapy for rectal adenocarcinoma

International Nuclear Information System (INIS)

Taylor, R.E.; Kerr, G.R.; Arnott, S.J.

1987-01-01

A series of 243 patients with adenocarcinoma of the rectum treated with radiotherapy is presented. Radiotherapy was combined with 5-fluorouracil, or given alone. Seventy-four patients were treated with radical external beam radiotherapy for recurrent or inoperable rectal adenocarcinoma. One hundred and forty-five patients with advanced pelvic tumours or metastases were treated with palliative pelvic radiotherapy. Twenty-four patients with small-volume residual pelvic tumour or who were felt to be at high risk of pelvic recurrence following radical resection received postoperative radiotherapy. Complete tumour regression was seen in 38% of radically treated patients, and 24% of palliatively treated patients. Partial regression was observed in 56% of radically treated patients, and 58% of palliatively treated patients. Long-term local tumour control was more commonly observed for small tumours (< 5 cm diameter). Fifty-eight % of patients treated with postoperative radiotherapy remained free of local recurrence. Survival was significantly better with small tumours. The addition of 5FU did not appear to improve survival or tumour control. (author)

Improving external beam radiotherapy by combination with internal irradiation.

Science.gov (United States)

Dietrich, A; Koi, L; Zöphel, K; Sihver, W; Kotzerke, J; Baumann, M; Krause, M

2015-07-01

The efficacy of external beam radiotherapy (EBRT) is dose dependent, but the dose that can be applied to solid tumour lesions is limited by the sensitivity of the surrounding tissue. The combination of EBRT with systemically applied radioimmunotherapy (RIT) is a promising approach to increase efficacy of radiotherapy. Toxicities of both treatment modalities of this combination of internal and external radiotherapy (CIERT) are not additive, as different organs at risk are in target. However, advantages of both single treatments are combined, for example, precise high dose delivery to the bulk tumour via standard EBRT, which can be increased by addition of RIT, and potential targeting of micrometastases by RIT. Eventually, theragnostic radionuclide pairs can be used to predict uptake of the radiotherapeutic drug prior to and during therapy and find individual patients who may benefit from this treatment. This review aims to highlight the outcome of pre-clinical studies on CIERT and resultant questions for translation into the clinic. Few clinical data are available until now and reasons as well as challenges for clinical implementation are discussed.

An Apparatus For Student Projects Using External-Beam PIXE And PIGE

International Nuclear Information System (INIS)

Correll, Francis D.; Edsall, Douglas W.; DePooter, Katherine A.; Maskell, Nicholas D.; Vanhoy, Jeffrey R.

2011-01-01

We recently installed a simple endstation at the Naval Academy Tandem Accelerator Laboratory to support student projects using external-beam PIXE and PIGE. It consists of a short, graphite-lined beamline extension with a thin window, an interlocked box that surrounds the target, detectors for x- and gamma rays, provision for flooding the target with helium gas, easily changed x-ray absorbers, and a compact video camera for monitoring the position of the beam spot. We used this system to measure the elemental composition of colonial-era architectural materials, principally bricks and mortar, from James Madison's Montpelier, the reconstructed Virginia estate of the fourth President of the United States. We describe the design and construction of the system, relate some of our experiences using it, and present some preliminary data from our investigations.

Cervix Regression and Motion During the Course of External Beam Chemoradiation for Cervical Cancer

International Nuclear Information System (INIS)

Beadle, Beth M.; Jhingran, Anuja; Salehpour, Mohammad; Sam, Marianne; Iyer, Revathy B.; Eifel, Patricia J.

2009-01-01

Purpose: To evaluate the magnitude of cervix regression and motion during external beam chemoradiation for cervical cancer. Methods and Materials: Sixteen patients with cervical cancer underwent computed tomography scanning before, weekly during, and after conventional chemoradiation. Cervix volumes were calculated to determine the extent of cervix regression. Changes in the center of mass and perimeter of the cervix between scans were used to determine the magnitude of cervix motion. Maximum cervix position changes were calculated for each patient, and mean maximum changes were calculated for the group. Results: Mean cervical volumes before and after 45 Gy of external beam irradiation were 97.0 and 31.9 cc, respectively; mean volume reduction was 62.3%. Mean maximum changes in the center of mass of the cervix were 2.1, 1.6, and 0.82 cm in the superior-inferior, anterior-posterior, and right-left lateral dimensions, respectively. Mean maximum changes in the perimeter of the cervix were 2.3 and 1.3 cm in the superior and inferior, 1.7 and 1.8 cm in the anterior and posterior, and 0.76 and 0.94 cm in the right and left lateral directions, respectively. Conclusions: Cervix regression and internal organ motion contribute to marked interfraction variations in the intrapelvic position of the cervical target in patients receiving chemoradiation for cervical cancer. Failure to take these variations into account during the application of highly conformal external beam radiation techniques poses a theoretical risk of underdosing the target or overdosing adjacent critical structures

Development of isodose curves for A 6 mv x-ray beam

International Nuclear Information System (INIS)

Hidaytalla, Lamya Abbas

1994-08-01

In this thesis radiation distribution of 6 Mv x-ray beam in a water phantom is developed. The method is based on a simple empirical equation and the assumption that the x-ray source is a point source. This leads to a simple equation for the calculation and plotting of the isodose curves. the charts obtained for two fields, 6*6 and 12*12 cm 2 show good agreement with the previous data used in the isotope and radiation centre, Khartoum hospital. It is suggested that further development should be carried out by writing a computer program for all the fields. (Author)

ERDA with an external helium ion micro-beam: Advantages and potential applications

International Nuclear Information System (INIS)

Calligaro, T.; Castaing, J.; Dran, J.-C.; Moignard, B.; Pivin, J.-C.; Prasad, G.V.R.; Salomon, J.; Walter, P.

2001-01-01

Preliminary ERDA experiments at atmospheric pressure have been performed with our external microprobe set-up currently used for the analysis of museum objects by PIXE, RBS and NRA. The objective was to check the feasibility of hydrogen (and deuterium) profiling with an external beam of 3-MeV helium ions. The standard scattering geometry (incident beam at 15 deg. with respect to sample surface and emerging protons or deuterons at 15 deg. in the forward direction) was kept, but the thin foil absorber was replaced by helium gas filling the space between the beam spot and the detector over a distance of about 84 mm. Several standards prepared by ion implantation, with well known H or D depth profiles, were first analysed, which indicated that the analytical capability was as good as under vacuum. A striking feature is the much lower surface peak than under vacuum, a fact that enhances the sensitivity for H analysis near the surface. The same type of measurement was then performed on different materials to show the usefulness of the technique. As a first example, we have checked that the incorporation of H or D into sapphire crystals during mechanical polishing is below the detection limit. Another example is the measurement of the H content in emeralds which can be used as an additional compositional criterion for determining the provenance of emeralds set in museum jewels. The advantages and limitations of our set-up are discussed and several possible applications in the field of cultural heritage are described

Controversies in external beam and high dose rate brachytherapy of oesophageal cancer

International Nuclear Information System (INIS)

Sur, R.K.; Levin, V.C.; Malas, Simon; Donde, Bernard

1994-01-01

Various controversies in the treatment of oesophageal carcinoma with external beam radiotherapy and high dose rate intracavitary irradiation have been reviewed. Conflicting results from different parts of the world has made it difficult to optimize the radiation dose that may give the best results. More studies and longer follow-up are needed before a definite conclusion can be made on the optimization of dose. (author). 18 refs., 2 tabs

Numerical simulation on the energy spectrum of the electron beam generated by low-impedance diode and the influence of external magnetic field on diode impedance

International Nuclear Information System (INIS)

Liu Guozhi

2003-01-01

The energy spectrum of the electron beam generated by low-impedance diode and the influence of external magnetic field on the impedance of diode are studied numerically in this paper. The results show that the beam generated by the diode has an energy spread, even with constant applied voltage. Additionally, external magnetic field has great but reverse influence on the impedance of low-impedance diode, which is, according to the author's analysis, the result of the change of the electron's track due to external magnetic field. If the beam current is less than the critical one for self-pinch, the impedance will be constant with the variation of external magnetic field

Evaluation of surface and shallow depth dose reductions using a Superflab bolus during conventional and advanced external beam radiotherapy.

Science.gov (United States)

Yoon, Jihyung; Xie, Yibo; Zhang, Rui

2018-03-01

The purpose of this study was to evaluate a methodology to reduce scatter and leakage radiations to patients' surface and shallow depths during conventional and advanced external beam radiotherapy. Superflab boluses of different thicknesses were placed on top of a stack of solid water phantoms, and the bolus effect on surface and shallow depth doses for both open and intensity-modulated radiotherapy (IMRT) beams was evaluated using thermoluminescent dosimeters and ion chamber measurements. Contralateral breast dose reduction caused by the bolus was evaluated by delivering clinical postmastectomy radiotherapy (PMRT) plans to an anthropomorphic phantom. For the solid water phantom measurements, surface dose reduction caused by the Superflab bolus was achieved only in out-of-field area and on the incident side of the beam, and the dose reduction increased with bolus thickness. The dose reduction caused by the bolus was more significant at closer distances from the beam. Most of the dose reductions occurred in the first 2-cm depth and stopped at 4-cm depth. For clinical PMRT treatment plans, surface dose reductions using a 1-cm Superflab bolus were up to 31% and 62% for volumetric-modulated arc therapy and 4-field IMRT, respectively, but there was no dose reduction for Tomotherapy. A Superflab bolus can be used to reduce surface and shallow depth doses during external beam radiotherapy when it is placed out of the beam and on the incident side of the beam. Although we only validated this dose reduction strategy for PMRT treatments, it is applicable to any external beam radiotherapy and can potentially reduce patients' risk of developing radiation-induced side effects. © 2018 The Authors. Journal of Applied Clinical Medical Physics published by Wiley Periodicals, Inc. on behalf of American Association of Physicists in Medicine.

External beam PIXE analysis of painting

International Nuclear Information System (INIS)

Pascholati, Paulo R.; Rizzutto, Marcia A.; Barbosa, Marcel D.L.; Albuquerque, Cindy

2005-01-01

The preservation and conservation of mankind cultural heritage has become an important issue worldwide. Non-destructive analytical techniques are suitable, for example, to analyze precious and unique objects of art and archaeology. Among those techniques Particle Induced X-Ray Emission (PIXE) has good advantage to identify elemental composition present in these kinds of objects. The Laboratorio de Analise de Materiais por Feixes Ionicos-LAMFI of the Institute of Physics of the University of Sao Paulo has been installed an external beam facility for PIXE analysis. This new setup is being used for the analysis of archaeological pottery artifacts, paintings and biological tissues (teeth and bones), which are not compatible with the high vacuum of the regular PIXE target chamber. In addition most art and archaeological objects are too large for the evacuated analysis chamber. Applications of this facility will be presented in the analysis of one painting of the beginning of the last century. The chemical elements identified in the painting were Ca, Ti, Cr, Cu, Fe, Zn, Pb and Ba. The PIXE measurements were done non-destructively and no visible damage was observed on the irradiated object. (author)

Trace element fingerprinting of jewellery rubies by external beam PIXE

International Nuclear Information System (INIS)

Calligaro, T.; Poirot, J.-P.; Querre, G.

1999-01-01

External beam PIXE analysis allows the non-destructive in situ characterisation of gemstones mounted on jewellery pieces. This technique was used for the determination of the geographical origin of 64 rubies set on a high-valued necklace. The trace element content of these gemstones was measured and compared to that of a set of rubies of known sources. Multivariate statistical processing of the results allowed us to infer the provenance of rubies: one comes from Thailand/Cambodia deposit while the remaining are attributed to Burma. This highlights the complementary capabilities of PIXE and conventional geological observations

Trace element fingerprinting of jewellery rubies by external beam PIXE

Energy Technology Data Exchange (ETDEWEB)

Calligaro, T. E-mail: calli@culture.nl; Poirot, J.-P.; Querre, G

1999-04-02

External beam PIXE analysis allows the non-destructive in situ characterisation of gemstones mounted on jewellery pieces. This technique was used for the determination of the geographical origin of 64 rubies set on a high-valued necklace. The trace element content of these gemstones was measured and compared to that of a set of rubies of known sources. Multivariate statistical processing of the results allowed us to infer the provenance of rubies: one comes from Thailand/Cambodia deposit while the remaining are attributed to Burma. This highlights the complementary capabilities of PIXE and conventional geological observations.

MO-A-BRB-01: Review of TG-262 Internal Survey of Practices in EMR for External Beam Therapy

International Nuclear Information System (INIS)

Mechalakos, J.

2015-01-01

The process of converting to an electronic chart for radiation therapy can be daunting. It requires a dedicated committee to first research and choose appropriate software, to review the entire documentation policy and flow of the clinic, to convert this system to electronic form or if necessary, redesign the system to more easily conform to the electronic process. Those making the conversion and those who already use electronic charting would benefit from the shared experience of those who have been through the process in the past. Therefore TG262 was convened to provide guidance on electronic charting for external beam radiation therapy and brachytherapy. This course will present the results of an internal survey of task group members on EMR practices in External Beam Radiation Therapy as well as discuss important issues in EMR development and structure for both EBRT and brachytherapy. Learning Objectives: Be familiarized with common practices and pitfalls in development and maintenance of an electronic chart in Radiation Oncology Be familiarized with important issues related to electronic charting in External Beam Radiation Therapy Be familiarized with important issues related to electronic charting in Brachytherapy

External proton and Li beams; Haces externos de protones y litios

Energy Technology Data Exchange (ETDEWEB)

Schuff, Juan A; Burlon, Alejandro A; Debray, Mario E; Kesque, Jose M; Kreiner, Andres J; Stoliar, Pablo A; Naab, Fabian; Ozafran, Mabel J; Vazquez, Monica E [Comision Nacional de Energia Atomica, General San Martin (Argentina). Dept. de Fisica; Policastro, Lucia L; Duran, Hebe; Molinari, Beatriz L; O' Connor, Silvia E; Saint-Martin, Maria L.G.; Palmieri, Monica; Bernaola, Omar A; Opezzo, Oscar J [Comision Nacional de Energia Atomica, General San Martin (Argentina). Dept. de Radiobiologia; Mazal, A; Favaudon, F; Henry, Y [Institut Curie, 75 - Paris (France); Perez de la Hoz, A.; Somacal, Hector; Valda, Alejandro; Canevas, S; Ruffolo, M; Tasat, D R [Universidad Nacional de General San Martin, Villa Ballester (Argentina). Escuela de Ciencia y Tecnologia; Davidson, Miguel; Davidson, Jorge [Buenos Aires Univ. (Argentina). Dept. de Fisica; Delacroix, S; Nauraye, C; Brune, E; Gautier, C; Habrand, J L [Centre de Protontherapie, 91 - Orsay (France); Muhlmann, M C [Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET), Buenos Aires (Argentina)

2000-07-01

In the frame of a feasibility study to introduce proton therapy in Argentina in a collaborative agreement between the Physics and Radiobiology Departments of the National Atomic Energy Commission or Argentina and the Centre de Protontherapie de Orsay, France, external proton and Li beams were produced at the TANDAR accelerator in Buenos Aires. The specific aim of this work was to start radiobiology studies on cell cultures and small laboratory animals. In particular we seek to determine here the relative biological effectiveness, RBE, for proton and Li beams as a function of energy for different tumor and normal cell lines. The 24 MeV proton beam was diffused using a 25 {mu}m gold foil and extracted through a Kapton window to obtain a homogeneous field (constant to 95%) of about 7 cm in diameter. Measurements were carried out with quasi-monoenergetic beams (of 20.2 {+-} 0.07 MeV, 2.9 {+-} 0.10 MeV y 1.5 {+-} 0.1 MeV for protons and 21.4 {+-} 0.4 MeV for Lithium). Proton fluence and Bragg peaks were measured. The dose delivered in each case was monitored on-line with a calibrated transmission ionization chamber. Three cell lines PDV, PDVC 57 and V 79 (as a reference) were irradiated with {gamma}-rays, proton and lithium beams with linear energy transfer (LET) from 2 to 100 keV/{mu}m. RBE values in the range of 1.2-5.9 were obtained. In addition preliminary studies on chromosomal aberrations and viability of alveolar macrophages were carried out. (author)

External Beam Boost for Cancer of the Cervix Uteri When Intracavitary Therapy Cannot Be Performed

International Nuclear Information System (INIS)

Barraclough, Lisa Helen; Swindell, Ric; Livsey, Jacqueline E.; Hunter, Robin D.; Davidson, Susan E.

2008-01-01

Purpose: To assess the outcome of patients treated with radical radiotherapy for cervical cancer who received an external beam boost, in place of intracavitary brachytherapy (ICT), after irradiation to the whole pelvis. Methods and Materials: Case notes were reviewed for all patients treated in this way in a single center between 1996 and 2004. Patient and tumor details, the reasons why ICT was not possible, and treatment outcome were documented. Results: Forty-four patients were identified. The mean age was 56.4 years (range, 26-88 years). Clinical International Federation of Gynecology and Obstetrics or radiologic stage for Stages I, II, III, and IV, respectively, was 16%, 48%, 27%, and 7%. A total radiation dose of 54-70 Gy was given (75% received ≥60 Gy). Reasons for ICT not being performed were technical limitations in 73%, comorbidity or isolation limitations in 23%, and patient choice in 4%. The median follow-up was 2.3 years. Recurrent disease was seen in 48%, with a median time to recurrence of 2.3 years. Central recurrence was seen in 16 of the 21 patients with recurrent disease. The 5-year overall survival rate was 49.3%. The 3-year cancer-specific survival rate by stage was 100%, 70%, and 42% for Stages I, II, and III, respectively. Late Grades 1 and 2 bowel, bladder, and vaginal toxicity were seen in 41%. Late Grade 3 toxicity was seen in 2%. Conclusion: An external beam boost is a reasonable option after external beam radiotherapy to the pelvis when it is not possible to perform ICT

Monitoring external beam radiotherapy using real-time beam visualization

Energy Technology Data Exchange (ETDEWEB)

Jenkins, Cesare H. [Department of Mechanical Engineering and Department of Radiation Oncology, Stanford University, Stanford, California 94305 (United States); Naczynski, Dominik J.; Yu, Shu-Jung S.; Xing, Lei, E-mail: lei@stanford.edu [Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California 94305 (United States)

2015-01-15

Purpose: To characterize the performance of a novel radiation therapy monitoring technique that utilizes a flexible scintillating film, common optical detectors, and image processing algorithms for real-time beam visualization (RT-BV). Methods: Scintillating films were formed by mixing Gd{sub 2}O{sub 2}S:Tb (GOS) with silicone and casting the mixture at room temperature. The films were placed in the path of therapeutic beams generated by medical linear accelerators (LINAC). The emitted light was subsequently captured using a CMOS digital camera. Image processing algorithms were used to extract the intensity, shape, and location of the radiation field at various beam energies, dose rates, and collimator locations. The measurement results were compared with known collimator settings to validate the performance of the imaging system. Results: The RT-BV system achieved a sufficient contrast-to-noise ratio to enable real-time monitoring of the LINAC beam at 20 fps with normal ambient lighting in the LINAC room. The RT-BV system successfully identified collimator movements with sub-millimeter resolution. Conclusions: The RT-BV system is capable of localizing radiation therapy beams with sub-millimeter precision and tracking beam movement at video-rate exposure.

Olfactory neural tumours - the role of external beam radiotherapy

International Nuclear Information System (INIS)

Slevin, N.J.; Irwin, C.J.R.; Banerjee, S.S.; Path, F.R.C.; Gupta, N.K.; Farrington, W.T.

1996-01-01

Olfactory neuroblastoma is an uncommon tumour arising in the nasal cavity or paranasal sinuses. We report the management of nine cases treated with external beam radiotherapy subsequent to surgery, either attempted definitive removal or biopsy only. Recent refinements in pathological evaluation of these tumours are discussed. Seven cases were deemed classical olfactory neuroblastoma whilst two were classified as neuroendocrine carcinoma. The clinical features, radiotherapy technique and variable natural history are presented. Seven of eight patients treated radically were controlled locally, with a minimum follow-up of two years. Three patients developed cervical lymph node disease and three patients died of systemic metastatic disease. Suggestions are made as to which patients should have en-bloc resection rather than definitive radiotherapy. (author)

Simulations of Gamma-Ray Burst Jets in a Stratified External Medium: Dynamics, Afterglow Light Curves, Jet Breaks, and Radio Calorimetry

Science.gov (United States)

De Colle, Fabio; Ramirez-Ruiz, Enrico; Granot, Jonathan; Lopez-Camara, Diego

2012-05-01

The dynamics of gamma-ray burst (GRB) jets during the afterglow phase is most reliably and accurately modeled using hydrodynamic simulations. All published simulations so far, however, have considered only a uniform external medium, while a stratified external medium is expected around long duration GRB progenitors. Here, we present simulations of the dynamics of GRB jets and the resulting afterglow emission for both uniform and stratified external media with ρextvpropr -k for k = 0, 1, 2. The simulations are performed in two dimensions using the special relativistic version of the Mezcal code. Common to all calculations is the initiation of the GRB jet as a conical wedge of half-opening angle θ0 = 0.2 whose radial profile is taken from the self-similar Blandford-McKee solution. The dynamics for stratified external media (k = 1, 2) are broadly similar to those derived for expansion into a uniform external medium (k = 0). The jet half-opening angle is observed to start increasing logarithmically with time (or radius) once the Lorentz factor Γ drops below θ-1 0. For larger k values, however, the lateral expansion is faster at early times (when Γ > θ-1 0) and slower at late times with the jet expansion becoming Newtonian and slowly approaching spherical symmetry over progressively longer timescales. We find that, contrary to analytic expectations, there is a reasonably sharp jet break in the light curve for k = 2 (a wind-like external medium), although the shape of the break is affected more by the viewing angle (for θobs <= θ0) than by the slope of the external density profile (for 0 <= k <= 2). Steeper density profiles (i.e., increasing k values) are found to produce more gradual jet breaks while larger viewing angles cause smoother and later appearing jet breaks. The counterjet becomes visible as it becomes sub-relativistic, and for k = 0 this results in a clear bump-like feature in the light curve. However, for larger k values the jet decelerates more

Pain flare following external beam radiotherapy and meaningful change in pain scores in the treatment of bone metastases

International Nuclear Information System (INIS)

Chow, Edward; Ling, Alison; Davis, Lori; Panzarella, Tony; Danjoux, Cyril

2005-01-01

Background and purpose: To examine the incidence of pain flare following external beam radiotherapy and to determine what constitutes a meaningful change in pain scores in the treatment of bone metastases. Patients and methods: Patients with bone metastases treated with external beam radiotherapy were asked to score their pain on a scale of 0-10 before the treatment (baseline), daily during the treatment and for 10 days after completion of external beam radiation. Pain flare was defined as a two-point increase from baseline pain in the pain scale of 0-10 with no decrease in analgesic intake or a 25% increase in analgesic intake employing daily oral morphine equivalent with no decrease in pain score. To distinguish pain flare from progression of pain, we required the pain score and analgesic intake to return back to baseline levels after the increase/flare. They were also asked to indicate if their pain changed during that time compared to pre-treatment level. The change in pain score was compared with patient perception. Results: Eighty-eight patients were evaluated in this study. There were 49 male and 39 female patients with the median age of 70 years. Twelve of 88 patients (14%) had pain flare on day 1. The overall incidence of pain flare during the study period ranged from 2 to 16%. A total of 797 pain scorings were obtained. Patients perceived an improvement in pain when their self-reported pain score decreased by at least two points. Conclusions: Our study confirms the occurrence of pain flare following the external beam radiotherapy in the treatment of bone metastases. Further studies are required to predict who are at risk for flare. Appropriate measures can be taken to alleviate the pain flare. The finding in the meaningful change in pain scores supports the investigator-defined partial response used in some clinical trials

Combined external beam and intraluminal radiotherapy for irresectable Klatskin tumors

Energy Technology Data Exchange (ETDEWEB)

Schleicher, U.M. [Klinik fuer Strahlentherapie, Technische Hochschule Aachen (Germany); Staatz, G. [Klinik fuer Radiologische Diagnostik, Technische Hochschule Aachen (Germany); Alzen, G. [Klinik fuer Radiologische Diagnostik, Technische Hochschule Aachen (Germany); Abt. Kinderradiologie, Giessen Univ. (Germany); Andreopoulos, D. [Klinik fuer Strahlentherapie, Technische Hochschule Aachen (Germany); BOC Oncology Centre, Nikosia (Cyprus)

2002-12-01

Background: In most cases of proximal cholangiocarcinoma, curative surgery is not possible. Radiotherapy can be used for palliative treatment. We report our experience with combined external beam and intraluminal radiotherapy of advanced Klatskin's tumors. Patients and Methods: 30 patients were treated for extrahepatic proximal bile duct cancer. Our schedule consisted for external beam radiotherapy (median dose 30 Gy) and a high-dose-rate brachytherapy boost (median dose 40 Gy) delivered in four or five fractions, which could be applied completely in twelve of our patients. 15 patients in the brachytherapy and nine patients in the non-brachytherapy group received additional low-dose chemotherapy with 5-fluorouracil. Results: The brachytherapy boost dose improved the effect of external beam radiotherapy by increasing survival from a median of 3.9 months in the non-brachytherapy group to 9.1 months in the brachytherapy group. The effect was obvious in patients receiving a brachytherapy dose above 30 Gy, and in those without jaundice at the beginning of radiotherapy (p<0.05). Conclusions: The poor prognosis in patients with advanced Klatskin's tumors may be improved by combination therapy, with the role of brachytherapy and chemotherapy still to be defined. Our results suggest that patients without jaundice should be offered brachytherapy, and that a full dose of more than 30 Gy should be applied. (orig.) [German] Hintergrund: Bei den meisten Patienten mit proximalen Cholangiokarzinomen ist eine kurative Operation nicht mehr moeglich. Im Rahmen der Palliativbehandlung kann die Strahlentherapie eingesetzt werden. Wir berichten ueber unsere Erfahrungen mit der Kombination aus perkutaner und intraluminaler Strahlentherapie fortgeschrittener Klatskin-Tumoren. Patienten und Methode: 30 Patienten wurden wegen extrahepatischer proximaler Gallengangskarzinome behandelt. Unser Therapieschema umfasste eine perkutane Strahlentherapie (mediane Dosis: 30 Gy) sowie einen

Neural Stem Cell-Preserving External-Beam Radiotherapy of Central Nervous System Malignancies

International Nuclear Information System (INIS)

Barani, Igor J.; Cuttino, Laurie W.; Benedict, Stanley H.; Todor, Dorin; Bump, Edward A.; Wu Yan; Chung, Theodore D.; Broaddus, William C.; Lin, Peck-Sun

2007-01-01

Purpose: Recent discoveries have implicated neural stem cells (NSC) as the source of plasticity and repair in the mature mammalian brain. Treatment-induced NSC dysfunction may lead to observed toxicity. This study evaluates the feasibility of NSC-preserving external beam radiotherapy. Methods and Materials: A single computed tomography (CT) dataset depicting a right periventricular lesion was used in this study as this location reflects the most problematic geometric arrangement with respect to NSC preservation. Conventional and NSC preserving radiotherapy (RT) plans were generated for the same lesion using two clinical scenarios: cerebral metastatic disease and primary high-grade glioma. Disease-specific target volumes were used. Metastatic disease was conventionally treated with whole-brain radiotherapy (WBRT) to 3,750 cGy (15 fractions) followed by a single stereotactic radiosurgery (SRS) boost of 1,800 cGy to gross disease only. High-grade glioma was treated with conventional opposed lateral and anterior superior oblique beams to 4,600 cGy (23 fractions) followed by a 1,400 cGy (7 fractions) boost. NSC preservation was achieved in both scenarios with inverse-planned intensity modulated radiotherapy (IMRT). Results: Cumulative dose reductions of 65% (metastatic disease) and 25% (high-grade glioma) to the total volume of the intracranial NSC compartments were achieved with NSC-preserving IMRT plans. The reduction of entry and exit dose to NSC niches located contralateral to the target contributed most to NSC preservation. Conclusions: Neural stem cells preservation with current external beam radiotherapy techniques is achievable in context of both metastatic brain disease and high-grade glioma, even when the target is located adjacent to a stem cell compartment. Further investigation with clinical trials is warranted to evaluate whether NSC preservation will result in reduced toxicity

Energization of electrons in a plasma beam entering a curved magnetic field

International Nuclear Information System (INIS)

Brenning, N.; Lindberg, L.; Eriksson, A.

1980-09-01

Earlier experiments have indicated that suprathermal electrons appear when a collisionless plasma flowing along a magnetic field enters a region where the magnetic field is curved. In the present investigation newly developed methods of He-spectroscopy based on the absolute intensities of the He I 3889 A and He II 4686 A lines are utilized to study the electron temperature and to estimate the population of non-thermal electrons. The density of helium added for the diagnostic purpose is so low that the flow is not disturbed. It is found that the intrusion of the plasma into a curved or transverse field gives rise to a slight increase (15-20%) in the electron temperature and a remarkable increase in the fraction of non-thermal (>100 eV) electrons from below 1% to as much as 20-25% of the total electron population. There are also indications that the energization of electrons is particularly efficient on that side of the plasma beam which becomes polarized to a positive potential when entering the curved field. The experiments are confined to the case of weak magnetic field, i.e. only the electrons are magnetically confined. New details of the electric field and potential structure are presented and discussed. Electric field components parallel to the magnetic field are likely to energize the electrons, probably through the run-away phenomenon. (Auth.)

Natural frequencies of the frames having curved member

International Nuclear Information System (INIS)

Tekelioglu, M.; Ozyigit, H.A.; Ridvan, H.

2001-01-01

In-plane and out-of-plane vibrations of a frame having a curved member are studied. Although the analysis is carried out on a frame having a straight and a curve beam, it can be applicable for all the frame type structures. Different end conditions are considered for the system. Rotary inertia and extensional effects are included for the curved member. Finite element method is used as analysis tool. Natural frequencies of the curved beams for different end conditions are calculated first, and then the frequencies of the frames are investigated. The transformation from local coordinates to global coordinates for curved beams needs special attention in the analysis. The results are compared with other methods. (author)

Radiobiological comparison of external beam irradiation and radioimmunotherapy in renal cell carcinoma xenografts

International Nuclear Information System (INIS)

Wessels, B.W.; Vessella, R.L.; Palme, D.F. II; Berkopec, J.M.; Smith, G.K.; Bradley, E.W.

1989-01-01

Growth delay was measured in TK-82 renal cell carcinoma (RCC) xenografts implanted in nude mice receiving single fraction external beam irradiation (SF-XRT), multifraction external beam irradiation (MF-XRT), or radioimmunotherapy (RIT). Thermoluminescent dosimeter(s) (TLD) and autoradiography were used to ascertain the average absorbed dose delivered and the degree of heterogeneous uptake of radiolabeled antibody for the RIT irradiations. For intravenous administered activities of 100, 200, 400, and 600 microCi of I-131 labeled A6H antibody, volume doubling times (VDT) and TLD absorbed dose measurements for each administered activity were 7 days (341 cGy), 38 days (383 cGy), 85 days (886 cGy) and no regrowth (1034 cGy), respectively. For SF-XRT irradiations of 500, 1000, and 1500 cGy, VDT times were 11, 62, and 103 days, respectively. MF-XRT of 4 X 250 cGy over a 2-week period yielded a VDT of 25 days. Marked peripheral activity deposition was noted on most autoradiographs from multiple tumor samples. These data suggest that an equivalent to superior tumor growth delay is obtained for absorbed doses delivered by exponentially decaying low dose rate radioimmunotherapy RIT compared to similar doses of acute dose rate XRT as quantitated by the TLD method

Elemental analysis of ancient Chinese bronze artifacts with external-beam PIXE

International Nuclear Information System (INIS)

Lin, E.K.; Yu, Y.C.; Wang, C.W.; Shen, C.T.; Huang, Y.M.; Wu, S.C.; Hsieh, C.H.

1992-01-01

External-beam PIXE has been applied for the determination of the elemental composition of ancient Chinese bronze artifacts. Characteristic x-ray spectra from the samples bombarded with protons of 3 MeV have been measured with a HPGe detector. At each sample three spots were irradiated per run. Results of measurements on three fragments of bronze drinking vessels and helmet of Chinese ancient Chou and Shang dynasties (17th-8th century B.C.) are presented. To check the analytical method, we have also made measurements on the elemental composition of some modern coins. The results are discussed. (author)

Elemental analysis of ancient Chinese bronze artifacts with external-beam PIXE

Energy Technology Data Exchange (ETDEWEB)

Lin, E.K.; Yu, Y.C.; Wang, C.W.; Shen, C.T.; Huang, Y.M.; Wu, S.C.; Hsieh, C.H. [Academia Sinica, Taipei, TW (China). Inst. of Physics

1992-12-31

External-beam PIXE has been applied for the determination of the elemental composition of ancient Chinese bronze artifacts. Characteristic x-ray spectra from the samples bombarded with protons of 3 MeV have been measured with a HPGe detector. At each sample three spots were irradiated per run. Results of measurements on three fragments of bronze drinking vessels and helmet of Chinese ancient Chou and Shang dynasties (17th-8th century B.C.) are presented. To check the analytical method, we have also made measurements on the elemental composition of some modern coins. The results are discussed. (author).

Parallel processing of dose calculation for external photon beam therapy

International Nuclear Information System (INIS)

Kunieda, Etsuo; Ando, Yutaka; Tsukamoto, Nobuhiro; Ito, Hisao; Kubo, Atsushi

1994-01-01

We implemented external photon beam dose calculation programs into a parallel processor system consisting of Transputers, 32-bit processors especially suitable for multi-processor configuration. Two network conformations, binary-tree and pipeline, were evaluated for rectangular and irregular field dose calculation algorithms. Although computation speed increased in proportion to the number of CPU, substantial overhead caused by inter-processor communication occurred when a smaller computation load was delivered to each processor. On the other hand, for irregular field calculation, which requires more computation capability for each calculation point, the communication overhead was still less even when more than 50 processors were involved. Real-time responses could be expected for more complex algorithms by increasing the number of processors. (author)

Tests of a 3 meter curved superconducting beam transport dipole magnet

International Nuclear Information System (INIS)

Allinger, J.E.; Carroll, A.S.; Danby, G.T.; DeVito, B.; Jackson, J.W.; Leonhardt, W.J.; Prodell, A.G.; Weisenbloom, J.

1981-01-01

Initial tests of one of the curved 3 m long superconducting dipole magnets intended to generate 6.0 T and produce a 20.4 0 bend in the primary proton beam to a new D-target station at the Brookhaven National Laboratory AGS have been completed. Although this magnet, whose window frame design generally follows that of the successful 8 0 and Model T superconducting dipoles, demonstrates many of the desirable characteristics of these earlier magnets such as excellent quench propagation and good ramping properties, it has only reached a disappointingly low magnetic field of 3.5 to 4.0 T. Because of the great interest in superconducting magnet technology, this report will describe the diagnostic tests performed and plans for future modifications

Development of isodose curves for A 6 mv x-ray beam

Energy Technology Data Exchange (ETDEWEB)

Hidaytalla, Lamya Abbas [Department of Physics, Faculty of Science, University of Khartoum, Khartoum (Sudan)

1994-08-01

In this thesis radiation distribution of 6 Mv x-ray beam in a water phantom is developed. The method is based on a simple empirical equation and the assumption that the x-ray source is a point source. This leads to a simple equation for the calculation and plotting of the isodose curves. the charts obtained for two fields, 6*6 and 12*12 cm{sup 2} show good agreement with the previous data used in the isotope and radiation centre, Khartoum hospital. It is suggested that further development should be carried out by writing a computer program for all the fields. (Author) 14 refs. , 9 tabs. , 34 figs. Also available from the Department of Physics, Faculty of Science, University of Khartoum, Khartoum (SD)

In-vivo (entrance) dose measurements in external beam radiotherapy with aqueous FBX dosimetry system

International Nuclear Information System (INIS)

Semwal, M.K.; Thakur, P.K.; Bansal, A.K.; Vidyasagar, P.B.

2005-01-01

FBX aqueous chemical dosimetry system has been found useful in radiotherapy owing to its low dose measuring capability. In the present work, entrance dose measurements in external beam radiotherapy on a telecobalt machine were carried out with the system on 100 patients. Treatments involving simple beam arrangement of open parallel-opposed beams in cranial and pelvic irradiations were selected for this study. In place of a spectrophotometer, a simple and inexpensive colorimeter was used for absorbance measurements. The purpose was to assess the efficacy of the FBX system for in-vivo dose measurements. The results obtained show that the average discrepancy between the measured and expected dose for both categories of patients was 0.2% (standard deviation 3.2%) with a maximum of +1 0.3%. There were 5.5% cases showing more than ± 5% discrepancy. Comparison of the results obtained with published work on entrance dose measurements, with diode detectors, shows that the inexpensive FBX system can be used for in-vivo (entrance) dose measurements for simple beam arrangements in radiotherapy and can thus serve as a useful QA tool. (author)

Numerical Derivation of Iso-Damaged Curve for a Reinforced Concrete Beam Subjected to Blast Loading

Directory of Open Access Journals (Sweden)

Temsah Yehya

2018-01-01

Full Text Available Many engineering facilities are severely damaged by blast loading. Therefore, many manufacturers of sensitive, breakable, and deformed structures (such as facades of glass buildings carry out studies and set standards for these installations to withstand shock waves caused by explosions. Structural engineers also use these standards in their designs for various structural elements by following the ISO Damage Carve, which links pressure and Impulse. As all the points below this curve means that the structure is safe and will not exceed the degree of damage based on the various assumptions made. This research aims to derive the Iso-Damage curve of a reinforced concrete beam exposed to blast wave. An advanced volumetric finite element program (ABAQUS will be used to perform the derivation.

SIMULATIONS OF GAMMA-RAY BURST JETS IN A STRATIFIED EXTERNAL MEDIUM: DYNAMICS, AFTERGLOW LIGHT CURVES, JET BREAKS, AND RADIO CALORIMETRY

International Nuclear Information System (INIS)

De Colle, Fabio; Ramirez-Ruiz, Enrico; Granot, Jonathan; Lopez-Camara, Diego

2012-01-01

The dynamics of gamma-ray burst (GRB) jets during the afterglow phase is most reliably and accurately modeled using hydrodynamic simulations. All published simulations so far, however, have considered only a uniform external medium, while a stratified external medium is expected around long duration GRB progenitors. Here, we present simulations of the dynamics of GRB jets and the resulting afterglow emission for both uniform and stratified external media with ρ ext ∝r –k for k = 0, 1, 2. The simulations are performed in two dimensions using the special relativistic version of the Mezcal code. Common to all calculations is the initiation of the GRB jet as a conical wedge of half-opening angle θ 0 = 0.2 whose radial profile is taken from the self-similar Blandford-McKee solution. The dynamics for stratified external media (k = 1, 2) are broadly similar to those derived for expansion into a uniform external medium (k = 0). The jet half-opening angle is observed to start increasing logarithmically with time (or radius) once the Lorentz factor Γ drops below θ –1 0 . For larger k values, however, the lateral expansion is faster at early times (when Γ > θ –1 0 ) and slower at late times with the jet expansion becoming Newtonian and slowly approaching spherical symmetry over progressively longer timescales. We find that, contrary to analytic expectations, there is a reasonably sharp jet break in the light curve for k = 2 (a wind-like external medium), although the shape of the break is affected more by the viewing angle (for θ obs ≤ θ 0 ) than by the slope of the external density profile (for 0 ≤ k ≤ 2). Steeper density profiles (i.e., increasing k values) are found to produce more gradual jet breaks while larger viewing angles cause smoother and later appearing jet breaks. The counterjet becomes visible as it becomes sub-relativistic, and for k = 0 this results in a clear bump-like feature in the light curve. However, for larger k values the jet

SIMULATIONS OF GAMMA-RAY BURST JETS IN A STRATIFIED EXTERNAL MEDIUM: DYNAMICS, AFTERGLOW LIGHT CURVES, JET BREAKS, AND RADIO CALORIMETRY

Energy Technology Data Exchange (ETDEWEB)

De Colle, Fabio; Ramirez-Ruiz, Enrico [TASC, Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States); Granot, Jonathan [Racah Institute of Physics, The Hebrew University, Jerusalem 91904 (Israel); Lopez-Camara, Diego [Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico, Ap. 70-543, 04510 D.F. (Mexico)

2012-05-20

The dynamics of gamma-ray burst (GRB) jets during the afterglow phase is most reliably and accurately modeled using hydrodynamic simulations. All published simulations so far, however, have considered only a uniform external medium, while a stratified external medium is expected around long duration GRB progenitors. Here, we present simulations of the dynamics of GRB jets and the resulting afterglow emission for both uniform and stratified external media with {rho}{sub ext}{proportional_to}r{sup -k} for k = 0, 1, 2. The simulations are performed in two dimensions using the special relativistic version of the Mezcal code. Common to all calculations is the initiation of the GRB jet as a conical wedge of half-opening angle {theta}{sub 0} = 0.2 whose radial profile is taken from the self-similar Blandford-McKee solution. The dynamics for stratified external media (k = 1, 2) are broadly similar to those derived for expansion into a uniform external medium (k = 0). The jet half-opening angle is observed to start increasing logarithmically with time (or radius) once the Lorentz factor {Gamma} drops below {theta}{sup -1}{sub 0}. For larger k values, however, the lateral expansion is faster at early times (when {Gamma} > {theta}{sup -1}{sub 0}) and slower at late times with the jet expansion becoming Newtonian and slowly approaching spherical symmetry over progressively longer timescales. We find that, contrary to analytic expectations, there is a reasonably sharp jet break in the light curve for k = 2 (a wind-like external medium), although the shape of the break is affected more by the viewing angle (for {theta}{sub obs} {<=} {theta}{sub 0}) than by the slope of the external density profile (for 0 {<=} k {<=} 2). Steeper density profiles (i.e., increasing k values) are found to produce more gradual jet breaks while larger viewing angles cause smoother and later appearing jet breaks. The counterjet becomes visible as it becomes sub-relativistic, and for k = 0 this results

A comparison of protocols for external beam radiotherapy beam calibrations

International Nuclear Information System (INIS)

Saeed Al-Ahbabi, Salma; Bradley, D.A.; Beyomi, M.; Alkatib, Z.; Adhaheri, S.; Darmaki, M.; Nisbet, A.

2012-01-01

A number of codes of practice (CoP) for electron and photon radiotherapy beam dosimetry are currently in use. Comparison is made of the more widely used of these, specifically those of the International Atomic Energy Agency (IAEA TRS-398), the American Association of Physicists in Medicine (AAPM TG-51) and the Institute of Physics and Engineering in Medicine (IPEM 2003). All are based on calibration of ionization chambers in terms of absorbed dose to water, each seeking to reduce uncertainty in delivered dose, providing an even stronger system of primary standards than previous air-kerma based approaches. They also provide a firm, traceable and straight-forward formalism. Included in making dose assessments for the three CoP are calibration coefficients for a range of beam quality indices. Measurements have been performed using clinical photon and electron beams, the absorbed dose to water being obtained following the recommendations given by each code. Electron beam comparisons have been carried out using measurements for electron beams of nominal energies 6, 9, 12, 16 and 20 MeV. Comparisons were also carried out for photon beams of nominal energies 6 and 18 MV. For photon beams use was made of NE2571 cylindrical graphite walled ionization chambers, cross-calibrated against an NE2611 Secondary Standard; for electron beams, PTW Markus and NACP-02 plane-parallel chambers were used. Irradiations were made using Varian 600C/2100C linacs, supported by water tanks and Virtual Water™ phantoms. The absorbed doses for photon and electron beams obtained following these CoP are all in good agreement, with deviations of less than 2%. A number of studies have been carried out by different groups in different countries to examine the consistency of dosimetry codes of practice or protocols. The aim of these studies is to confirm that the goal of those codes is met, namely uniformity in establishment of dosimetry of all radiation beam types used in cancer therapy in the world

Radiation retinopathy after external-beam irradiation: Analysis of time-dose factors

International Nuclear Information System (INIS)

Parsons, J.T.; Bova, F.J.; Mendenhall, W.M.

1994-01-01

To investigate the risk of radiation-induced retinopathy according to total radiation dose and fraction size, based on both retorspective and prospectively collected data. Between October 1964 and May 1989, 68 retinae in 64 patients received fractionated external-beam irradiation during the treatment of primary extracranial head and neck tumors. All patients had a minimum of 3 years of ophthalmologic follow-up (range, 3 to 26 years; mean, 9 years; median, 8 years). Twenty-seven eyes in 26 patients developed radiation retinopathy resulting in visual acuity of 20/200 or worse. The mean and median times to the onset of symptoms attributable to retinal ischemia were 2.8 and 2.5 years, respectively. Fourteen of the injured eyes developed rubeosis iridis and/or neovascular glaucoma. Radiation retinopathy was not observed at doses below 45 Gy, but increased steadily in incidence at doses ≥45Gy. In the range of doses between 45 and 55 Gy, there was an increased risk of injury among patients who received doses per fraction of ≥1.9Gy (p - .09). There was also a trend toward increased risk of injury among patients who received chemotherapy (two of two vs. four of ten in the 45-51 Gy range; p - .23). The lowest dose associated with retinopathy was 45 Gy delivered to a diabetic patient by twice-a-day fractionation. The data did not suggest an increased risk of radiation retinopathy with increasing age. The current study suggests the importance of total dose as well as dose per fraction, and adds support to a small body of literature suggesting that patients with diabetes mellitus or who receive chemotherapy are at increased risk of injury. A sigmoid dose-response curve is constructed from our current data and data from the literature. 36 refs., 5 figs., 4 tabs

Prostate biopsy after definitive treatment by interstitial iodine 125 implant or external beam radiation therapy

International Nuclear Information System (INIS)

Schellhammer, P.F.; el-Mahdi, A.M.; Higgins, E.M.; Schultheiss, T.E.; Ladaga, L.E.; Babb, T.J.

1987-01-01

The response to definitive radiation therapy of localized carcinoma of the prostate by iodine 125 implantation or external beam radiotherapy was monitored by examining specimens from biopsies performed after treatment. We analyzed 126 biopsy specimens obtained 18 months or more after treatment: 71 were obtained from 109 patients treated by iodine 125 and 55 from 197 patients treated by external beam radiotherapy. Thereafter, the disease status of these patients was examined at minimum 3-year intervals. No significant statistical difference was found between the negative specimen rates of the 2 treatment modalities: 46 of 71 (65 per cent) after iodine 125 implantation and 39 of 55 (71 per cent) after external beam radiotherapy were negative. To analyze the predictive value of biopsy results 103 patients whose prostatic examination results were normal at biopsy or who showed regression of tumor size and tumor induration after radiation were evaluated. The biopsy results from all patients were combined for analysis. Of 77 patients with negative biopsy specimens 16 (21 per cent) have had recurrent disease, compared to 17 of 26 (65 per cent) with positive biopsy specimens (p equals 0.00005). Of the 77 patients with negative biopsy specimens 7 (9 per cent) had local disease recurrence, compared to 12 of 26 (46 per cent) with a positive biopsy specimen (p equals 0.0001). The value of a positive specimen to predict failure remained significant with patients stratified by pre-treatment clinical stage and grade of the disease. Our results show that patients with positive specimens from the prostate who had been judged clinically by rectal examination to have responded to radiation therapy had a significantly increased incidence of local and distant failure compared to patients who had negative biopsy specimens

Evaluation of the Induced Activity in Air by the External Proton Beam in the Target Room of the Proton Accelerator Facility of Proton Engineering Frontier Project

International Nuclear Information System (INIS)

Lee, Cheol Woo; Lee, Young Ouk; Cho, Young Sik; Ahn, So Hyun

2007-01-01

One of the radiological concerns is the worker's exposure level and the concentration of the radionuclides in the air after shutdown, for the safety analysis on the proton accelerator facility. Although, the primary radiation source is the protons accelerated up to design value, all of the radio-nuclide is produced from the secondary neutron and photon induced reaction in air. Because, the protons don't penetrate the acceleration equipment like the DTL tank wall or BTL wall, secondary neutrons or photons are only in the air in the accelerator tunnel building because of the short range of the proton in the materials. But, for the case of the target rooms, external proton beams are occasionally used in the various experiments. When these external proton beams travel through air from the end of the beam transport line to the target, they interact directly with air and produce activation products from the proton induced reaction. The external proton beam will be used in the target rooms in the accelerator facility of the Proton Accelerator Frontier Project (PEFP). In this study, interaction characteristics of the external proton beam with air and induced activity in air from the direct interaction of the proton beam were evaluated

SU-D-209-02: Percent Depth Dose Curves for Fluoroscopic X-Ray Beam Qualities Incorporating Copper Filtration

Energy Technology Data Exchange (ETDEWEB)

Wunderle, K [Cleveland Clinic Foundation, Cleveland, OH (United States); Wayne State University School of Medicine, Detroit, MI (United States); Godley, A; Shen, Z; Dong, F [Cleveland Clinic Foundation, Cleveland, OH (United States); Rakowski, J [Wayne State University School of Medicine, Detroit, MI (United States)

2016-06-15

Purpose: The purpose of this investigation was to quantify percent depth dose (PDD) curves for fluoroscopic x-ray beam qualities incorporating added copper filtration. Methods: A PTW (Freiburg, Germany) MP3 water tank was used with a Standard Imaging (Middleton, WI) Exradin Model 11 Spokas Chamber to measure PDD curves for 60, 80, 100 and 120 kVp x-ray beams with copper filtration ranging from 0.0–0.9 mm at 22cm and 42cm fields of view from 0 to 150 mm of water. A free-in-air monitor chamber was used to normalize the water tank data to fluctuations in output from the fluoroscope. The measurements were acquired on a Siemens (Erlangen, Germany) Artis ZeeGo fluoroscope. The fluoroscope was inverted from the typical orientation providing an x-ray beam originating from above the water tank. The water tank was positioned so that the water level was located at 60cm from the focal spot; which also represents the focal spot to interventional reference plane distance for that fluoroscope. Results: PDDs for 60, 80, 100, and 120 kVp with 0 mm of copper filtration compared well to previously published data by Fetterly et al. [Med Phys, 28, 205 (2001)] for those beam qualities given differences in fluoroscopes, geometric orientation, type of ionization chamber, and the water tank used for data collection. PDDs for 60, 80, 100, and 120 kVp with copper filtration were obtained and are presented, which have not been previously investigated and published. Conclusion: The equipment and processes used to acquire the reported data were sound and compared well with previously published data for PDDs without copper filtration. PDD data for the fluoroscopic x-ray beams incorporating copper filtration can be used as reference data for estimating organ or soft tissue dose at depth involving similar beam qualities or for comparison with mathematical models.

Radiation optic neuropathy after external beam radiation therapy for acromegaly: report of two cases

International Nuclear Information System (INIS)

Bergh, Alfons C.M. van den; Hoving, Marjanke A.; Links, Thera P.; Dullaart, Robin P.F.; Ranchor, Adelita V.; Weeme, Cees A. ter; Canrinus, Alof A.; Szabo, Ben G.; Pott, Jan-Willem R.

2003-01-01

For diagnosing radiation optic neuropathy (RON) ophthalmological and imaging data were evaluated from 63 acromegalic patients, irradiated between 1967 and 1998. Two patients developed RON: one patient in one optic nerve 10 years and another patient in both optic nerves 5 months after radiation therapy. RON is a rare complication after external beam radiation therapy for acromegaly, which can occur after a considerable latency period

External cervical resorption: an analysis using cone beam and microfocus computed tomography and scanning electron microscopy.

Science.gov (United States)

Gunst, V; Mavridou, A; Huybrechts, B; Van Gorp, G; Bergmans, L; Lambrechts, P

2013-09-01

To provide a three-dimensional representation of external cervical resorption (ECR) with microscopy, stereo microscopy, cone beam computed tomography (CT), microfocus CT and scanning electron microscopy (SEM). External cervical resorption is an aggressive form of root resorption, leading to a loss of dental hard tissues. This is due to clastic action, activated by a damage of the covering cementum and stimulated probably by infection. Clinically, it is a challenging situation as it is characterized by a late symptomatology. This is due to the pericanalar protection from a resorption-resistant sheet, composed of pre-dentine and surrounding dentine. The clastic activity is often associated with an attempt to repair, seen by the formation of osteoid tissue. Cone beam CT is extremely useful in the diagnoses and treatment planning of ECR. SEM analyses provide a better insight into the activity of osteoclasts. The root canal is surrounded by a layer of dentine that is resistant to resorption. © 2013 International Endodontic Journal. Published by John Wiley & Sons Ltd.

Muscle invasive bladder cancer treated by transurethral resection, followed by external beam radiation and interstitial iridium-192

NARCIS (Netherlands)

A. Wijnmaalen (Arendjan); P.A. Helle (Peter); P.C.M. Koper (Peter); P.P. Jansen (Peter); P. Hanssens (Patrick); C.G.G. Boeken Kruger (Cornelis); W.L.J. van Putten (Wim)

1997-01-01

textabstractPurpose: To evaluate the results of transurethral resection (TUR), external beam radiotherapy (EBRT), and interstitial radiation (IRT) with iridium-192, using the afterloading technique in patients with muscle invasive bladder cancer. Methods and Materials: From May 1989 until September

Optimising measles virus-guided radiovirotherapy with external beam radiotherapy and specific checkpoint kinase 1 inhibition

International Nuclear Information System (INIS)

Touchefeu, Yann; Khan, Aadil A.; Borst, Gerben; Zaidi, Shane H.; McLaughlin, Martin; Roulstone, Victoria; Mansfield, David; Kyula, Joan; Pencavel, Tim; Karapanagiotou, Eleni M.; Clayton, Jamie; Federspiel, Mark J.; Russell, Steve J.; Garrett, Michelle; Collins, Ian; Harrington, Kevin J.

2013-01-01

Background and purpose: We previously reported a therapeutic strategy comprising replication-defective NIS-expressing adenovirus combined with radioiodide, external beam radiotherapy (EBRT) and DNA repair inhibition. We have now evaluated NIS-expressing oncolytic measles virus (MV-NIS) combined with NIS-guided radioiodide, EBRT and specific checkpoint kinase 1 (Chk1) inhibition in head and neck and colorectal models. Materials and methods: Anti-proliferative/cytotoxic effects of individual agents and their combinations were measured by MTS, clonogenic and Western analysis. Viral gene expression was measured by radioisotope uptake and replication by one-step growth curves. Potential synergistic interactions were tested in vitro by Bliss independence analysis and in in vivo therapeutic studies. Results: EBRT and MV-NIS were synergistic in vitro. Furthermore, EBRT increased NIS expression in infected cells. SAR-020106 was synergistic with EBRT, but also with MV-NIS in HN5 cells. MV-NIS mediated 131 I-induced cytotoxicity in HN5 and HCT116 cells and, in the latter, this was enhanced by SAR-020106. In vivo studies confirmed that MV-NIS, EBRT and Chk1 inhibition were effective in HCT116 xenografts. The quadruplet regimen of MV-NIS, virally-directed 131 I, EBRT and SAR-020106 had significant anti-tumour activity in HCT116 xenografts. Conclusion: This study strongly supports translational and clinical research on MV-NIS combined with radiation therapy and radiosensitising agents

Nonlinear dynamic analysis of cantilevered piezoelectric energy harvesters under simultaneous parametric and external excitations

Science.gov (United States)

Fang, Fei; Xia, Guanghui; Wang, Jianguo

2018-02-01

The nonlinear dynamics of cantilevered piezoelectric beams is investigated under simultaneous parametric and external excitations. The beam is composed of a substrate and two piezoelectric layers and assumed as an Euler-Bernoulli model with inextensible deformation. A nonlinear distributed parameter model of cantilevered piezoelectric energy harvesters is proposed using the generalized Hamilton's principle. The proposed model includes geometric and inertia nonlinearity, but neglects the material nonlinearity. Using the Galerkin decomposition method and harmonic balance method, analytical expressions of the frequency-response curves are presented when the first bending mode of the beam plays a dominant role. Using these expressions, we investigate the effects of the damping, load resistance, electromechanical coupling, and excitation amplitude on the frequency-response curves. We also study the difference between the nonlinear lumped-parameter and distributed-parameter model for predicting the performance of the energy harvesting system. Only in the case of parametric excitation, we demonstrate that the energy harvesting system has an initiation excitation threshold below which no energy can be harvested. We also illustrate that the damping and load resistance affect the initiation excitation threshold.

Experimental assessment of out-of-field dose components in high energy electron beams used in external beam radiotherapy.

Science.gov (United States)

Alabdoaburas, Mohamad M; Mege, Jean-Pierre; Chavaudra, Jean; Bezin, Jérémi Vũ; Veres, Atilla; de Vathaire, Florent; Lefkopoulos, Dimitri; Diallo, Ibrahima

2015-11-08

The purpose of this work was to experimentally investigate the out-of-field dose in a water phantom, with several high energy electron beams used in external beam radiotherapy (RT). The study was carried out for 6, 9, 12, and 18 MeV electron beams, on three different linear accelerators, each equipped with a specific applicator. Measurements were performed in a water phantom, at different depths, for different applicator sizes, and off-axis distances up to 70 cm from beam central axis (CAX). Thermoluminescent powder dosimeters (TLD-700) were used. For given cases, TLD measurements were compared to EBT3 films and parallel-plane ionization chamber measurements. Also, out-of-field doses at 10 cm depth, with and without applicator, were evaluated. With the Siemens applicators, a peak dose appears at about 12-15 cm out of the field edge, at 1 cm depth, for all field sizes and energies. For the Siemens Primus, with a 10 × 10 cm(²) applicator, this peak reaches 2.3%, 1%, 0.9% and 1.3% of the maximum central axis dose (Dmax) for 6, 9, 12 and 18 MeV electron beams, respectively. For the Siemens Oncor, with a 10 × 10 cm(²) applicator, this peak dose reaches 0.8%, 1%, 1.4%, and 1.6% of Dmax for 6, 9, 12, and 14 MeV, respectively, and these values increase with applicator size. For the Varian 2300C/D, the doses at 12.5 cm out of the field edge are 0.3%, 0.6%, 0.5%, and 1.1% of Dmax for 6, 9, 12, and 18 MeV, respectively, and increase with applicator size. No peak dose is evidenced for the Varian applicator for these energies. In summary, the out-of-field dose from electron beams increases with the beam energy and the applicator size, and decreases with the distance from the beam central axis and the depth in water. It also considerably depends on the applicator types. Our results can be of interest for the dose estimations delivered in healthy tissues outside the treatment field for the RT patient, as well as in studies exploring RT long-term effects.

High dose rate interstitial brachytherapy with external beam irradiation for localized prostate cancer. Preliminary results

Energy Technology Data Exchange (ETDEWEB)

Hiratsuka, Junichi; Jo, Yoshimasa; Yoden, Eisaku; Tanaka, Hiroyoshi; Imajo, Yoshinari [Kawasaki Medical School, Kurashiki, Okayama (Japan); Nagase, Naomi; Narihiro, Naomasa; Kubota, Juichi

2000-12-01

This study was undertaken to assess the biochemical and pathological results of combined external beam radiotherapy and high dose rate Ir-192 brachytherapy (HDR-Ir192) for clinically localized prostate cancer. Between October 1997 and August 1999, 39 evaluable patients with adenocarcinoma of prostate diagnosed by biopsy were treated with interstitial and external beam irradiation. Patients ranged in age from 58-82 years, with a mean of 69.7 years. T1c, T2 and T3 tumors, according to the UICC classification system (1997), were found in 7, 21 and 11 cases respectively. The mean initial pre-treatment PSA was 35.9 ng/ml (median 13.2), with 77% of the patients having had a pre-treatment PSA greater than 10 ng/ml. Of all patients, 17 had received pre-treatment hormonal therapy. Hormonal pretreatment was stopped at the beginning of radiotherapy in all cases. External beam four-field box irradiation was given to the small pelvis to a dose of 45 Gy/25 fractions. Three HDR-Ir192 treatments were given over a 30-h period, with 5.5 Gy per fraction at the circumference of the prostate gland over the course of this study. Biochemical failure was defined as a PSA level >1.5 ng/ml and rising on three consecutive values. If serial post-treatment PSA levels showed a continuous downward trend, failure was not scored. The patient with clinical evidence of progression was classified as a clinical failure. The median follow-up at the time of evaluation was 19.6 months. A post-treatment PSA level {<=}1.0 ng/ml was seen in 26 (67%) patients, and values from >1.0 to {<=}2.0 ng/ml were seen in 10 (26%) patients. Biochemical failure was not seen in 38 patients except for one patient who developed a distant bone metastasis with negative prostatic biopsy 15 months after treatment. Biochemical control rate was 100% (38/38) except for the patient with bone metastasis classified as clinical failure. Negative biopsies 18 months after treatment were found in 93% (14/15) of patients. Only one patient

Tumor bed delineation for external beam accelerated partial breast irradiation: A systematic review

International Nuclear Information System (INIS)

Yang, T. Jonathan; Tao, Randa; Elkhuizen, Paula H.M.; Vliet-Vroegindeweij, Corine van; Li, Guang; Powell, Simon N.

2013-01-01

In recent years, accelerated partial breast irradiation (APBI) has been considered an alternative to whole breast irradiation for patients undergoing breast-conserving therapy. APBI delivers higher doses of radiation in fewer fractions to the post-lumpectomy tumor bed with a 1–2 cm margin, targeting the area at the highest risk of local recurrence while sparing normal breast tissue. However, there are inherent challenges in defining accurate target volumes for APBI. Studies have shown that significant interobserver variation exists among radiation oncologists defining the lumpectomy cavity, which raises the question of how to improve the accuracy and consistency in the delineation of tumor bed volumes. The combination of standardized guidelines and surgical clips significantly improves an observer’s ability in delineation, and it is the standard in multiple ongoing external-beam APBI trials. However, questions about the accuracy of the clips to mark the lumpectomy cavity remain, as clips only define a few points at the margin of the cavity. This paper reviews the techniques that have been developed so far to improve target delineation in APBI delivered by conformal external beam radiation therapy, including the use of standardized guidelines, surgical clips or fiducial markers, pre-operative computed tomography imaging, and additional imaging modalities, including magnetic resonance imaging, ultrasound imaging, and positron emission tomography/computed tomography. Alternatives to post-operative APBI, future directions, and clinical recommendations were also discussed

Imperfection Sensitivity of Nonlinear Vibration of Curved Single-Walled Carbon Nanotubes Based on Nonlocal Timoshenko Beam Theory

Directory of Open Access Journals (Sweden)

Iman Eshraghi

2016-09-01

Full Text Available Imperfection sensitivity of large amplitude vibration of curved single-walled carbon nanotubes (SWCNTs is considered in this study. The SWCNT is modeled as a Timoshenko nano-beam and its curved shape is included as an initial geometric imperfection term in the displacement field. Geometric nonlinearities of von Kármán type and nonlocal elasticity theory of Eringen are employed to derive governing equations of motion. Spatial discretization of governing equations and associated boundary conditions is performed using differential quadrature (DQ method and the corresponding nonlinear eigenvalue problem is iteratively solved. Effects of amplitude and location of the geometric imperfection, and the nonlocal small-scale parameter on the nonlinear frequency for various boundary conditions are investigated. The results show that the geometric imperfection and non-locality play a significant role in the nonlinear vibration characteristics of curved SWCNTs.

Comparison of treatment using teletherapy (external beam radiation) alone versus teletherapy combined with brachytherapy for advanced squamous cell carcinoma of the esophagus

International Nuclear Information System (INIS)

Samea, Renato; Lourenco, Laercio Gomes

2011-01-01

Background - Squamous cell carcinoma of the esophagus is still a difficult tumor to treat with very poor prognosis. Aim - To compare the response to teletherapy treatment (external beam radiotherapy) alone versus teletherapy combined with brachytherapy for patients with advanced squamous cell carcinoma of the esophagus. Methods - Were studied 49 patients with advanced squamous cell carcinoma of the esophagus on clinical stage III (TNM-1999). They were separated into two groups. The first, underwent radiation therapy alone with linear accelerator of particles, average dose of 6000 cGy and the second to external beam radiation therapy at a dose of 5040 cGy combined with brachytherapy with Iridium 192 at a dose of 1500 cGy. Brachytherapy started one to two weeks after the end of teletherapy, and it was divided into three weekly applications of 500 cGy. Age, gender, race, habits (smoking and drinking), body mass index (BMI), complications with treatment benefits (pain relief and food satisfaction) and survival were analyzed. Results - The quality of life (food satisfaction, and pain palliation of dysphagia) were better in the group treated with external beam radiation therapy combined with brachytherapy. Survival was higher in the brachytherapy combined with external beam radiation therapy alone. Conclusion - Although the cure rate of squamous cell cancer of the esophagus is almost nil when treated with irradiation alone, this therapy is a form of palliative treatment for most patients in whom surgical contraindication exists. (author)

Comparison of treatment using teletherapy (external beam radiation) alone versus teletherapy combined with brachytherapy for advanced squamous cell carcinoma of the esophagus

Energy Technology Data Exchange (ETDEWEB)

Samea, Renato; Lourenco, Laercio Gomes, E-mail: renatosamea@globo.com [Department of Surgical Oncology of Dr. Arnaldo Vieira de Carvalho Hospital, Sao Paulo, SP (Brazil)

2011-10-15

Background - Squamous cell carcinoma of the esophagus is still a difficult tumor to treat with very poor prognosis. Aim - To compare the response to teletherapy treatment (external beam radiotherapy) alone versus teletherapy combined with brachytherapy for patients with advanced squamous cell carcinoma of the esophagus. Methods - Were studied 49 patients with advanced squamous cell carcinoma of the esophagus on clinical stage III (TNM-1999). They were separated into two groups. The first, underwent radiation therapy alone with linear accelerator of particles, average dose of 6000 cGy and the second to external beam radiation therapy at a dose of 5040 cGy combined with brachytherapy with Iridium 192 at a dose of 1500 cGy. Brachytherapy started one to two weeks after the end of teletherapy, and it was divided into three weekly applications of 500 cGy. Age, gender, race, habits (smoking and drinking), body mass index (BMI), complications with treatment benefits (pain relief and food satisfaction) and survival were analyzed. Results - The quality of life (food satisfaction, and pain palliation of dysphagia) were better in the group treated with external beam radiation therapy combined with brachytherapy. Survival was higher in the brachytherapy combined with external beam radiation therapy alone. Conclusion - Although the cure rate of squamous cell cancer of the esophagus is almost nil when treated with irradiation alone, this therapy is a form of palliative treatment for most patients in whom surgical contraindication exists. (author)

Parametric oesophageal multiple swallow scintigraphy for validation of dysphageal symptoms during external beam irradiation of mediastinal tumours

Energy Technology Data Exchange (ETDEWEB)

Brandt-Mainz, K.; Eising, E.G.; Bockisch, A. [Essen Univ. (Gesamthochschule) (Germany). Klinik und Poliklinik fuer Nuklearmedizin; Mallek, D. von; Poettgen, C.; Stuschke, M.; Sack, H. [Klinik und Poliklinik fuer Strahlentherapie, Universitaetsklinikum Essen (Germany)

2001-03-01

The aim of the study was to evaluate dysphageal symptoms and to measure the effect of local analgesic treatment using parametric oesophageal multiple swallow scintigraphy (PES) during external beam irradiation of the mediastinal region. Fifteen patients (most with lung cancer) with dysphagia grade II underwent PES during external beam radiotherapy of the mediastinum before and after application of local analgesics. Dynamic parametric condensed images were recorded. The intensity of clinical symptoms was correlated with the emptying rate at 10 s (ER-10 s) and the mean transit time (MTT). Visual analysis of the images was performed and the results were correlated with the fields of irradiation portals. Of the 15 patients, 12 showed a correlation between irradiation portals and the region of oesophageal motility disorder. Concordant results of clinical symptoms and PES data were found. In nine patients with a decrease in dysphagia following local analgesia, an increase in mean ER-10 s and a decrease in MTT were observed. In three patients with deterioration in clinical symptoms after analgesic treatment, a similar decrease in mean ER-10 s was found, though MTT remained constant. In three patients with normal values, motility disorders were detected in the dynamic study. In conclusion, PES was found to be a sensitive tool for the validation of dysphageal symptoms in patients during external beam irradiation of mediastinal tumours and for the evaluation and quantification of the efficacy of local analgesic treatment. Additional visual analysis of the dynamic study is helpful in diagnosing minimal disorders. (orig.)

Parametric oesophageal multiple swallow scintigraphy for validation of dysphageal symptoms during external beam irradiation of mediastinal tumours

International Nuclear Information System (INIS)

Brandt-Mainz, K.; Eising, E.G.; Bockisch, A.

2001-01-01

The aim of the study was to evaluate dysphageal symptoms and to measure the effect of local analgesic treatment using parametric oesophageal multiple swallow scintigraphy (PES) during external beam irradiation of the mediastinal region. Fifteen patients (most with lung cancer) with dysphagia grade II underwent PES during external beam radiotherapy of the mediastinum before and after application of local analgesics. Dynamic parametric condensed images were recorded. The intensity of clinical symptoms was correlated with the emptying rate at 10 s (ER-10 s) and the mean transit time (MTT). Visual analysis of the images was performed and the results were correlated with the fields of irradiation portals. Of the 15 patients, 12 showed a correlation between irradiation portals and the region of oesophageal motility disorder. Concordant results of clinical symptoms and PES data were found. In nine patients with a decrease in dysphagia following local analgesia, an increase in mean ER-10 s and a decrease in MTT were observed. In three patients with deterioration in clinical symptoms after analgesic treatment, a similar decrease in mean ER-10 s was found, though MTT remained constant. In three patients with normal values, motility disorders were detected in the dynamic study. In conclusion, PES was found to be a sensitive tool for the validation of dysphageal symptoms in patients during external beam irradiation of mediastinal tumours and for the evaluation and quantification of the efficacy of local analgesic treatment. Additional visual analysis of the dynamic study is helpful in diagnosing minimal disorders. (orig.)

Electrical Characterization of Gold-DNA-Gold Structures in Presence of an External Magnetic Field by Means of I-V Curve Analysis

Directory of Open Access Journals (Sweden)

Wan Haliza Abd Majid

2012-03-01

Full Text Available This work presents an experimental study of gold-DNA-gold structures in the presence and absence of external magnetic fields with strengths less than 1,200.00 mT. The DNA strands, extracted by standard method were used to fabricate a Metal-DNA-Metal (MDM structure. Its electric behavior when subjected to a magnetic field was studied through its current-voltage (I-V curve. Acquisition of the I-V curve demonstrated that DNA as a semiconductor exhibits diode behavior in the MDM structure. The current versus magnetic field strength followed a decreasing trend because of a diminished mobility in the presence of a low magnetic field. This made clear that an externally imposed magnetic field would boost resistance of the MDM structure up to 1,000.00 mT and for higher magnetic field strengths we can observe an increase in potential barrier in MDM junction. The magnetic sensitivity indicates the promise of using MDM structures as potential magnetic sensors.

Minimal requirements for quality controls in radiotherapy with external beams; Controlli di qualita' essenziali in radioterapia con fasci esterni

Energy Technology Data Exchange (ETDEWEB)

NONE

1999-07-01

Physical dosimetric guidelines have been developed by the Italian National Institute of Health study group on quality assurance in radiotherapy to define protocols for quality controls in external beam radiotherapy. While the document does not determine strict rules or firm recommendations, it suggests minimal requirements for quality controls necessary to guarantee an adequate degree of accuracy in external beam radiotherapy. [Italian] Il gruppo di studio Assicurazione di qualita' in radioterapia dell'Istituto Superiore di Sanita' presenta le linee guida per la stesura dei protocolli di controllo di qualita' essenziali necessari a garantire un adeguato livello di accuratezza del trattamento radiante e rappresenta pertanto una parte essenziale del contributo fisico-dosimetrico globale di assicurazione di qualita' in radioterapia con fasci esterni.

External-beam radiation therapy after surgical resection and intraoperative electron-beam radiation therapy for oligorecurrent gynecological cancer. Long-term outcome

International Nuclear Information System (INIS)

Sole, C.V.; Calvo, F.A.; Lozano, M.A.; Gonzalez-Sansegundo, C.; Gonzalez-Bayon, L.; Alvarez, A.; Lizarraga, S.; Garcia-Sabrido, J.L.

2014-01-01

The goal of the present study was to analyze prognostic factors in patients treated with external-beam radiation therapy (EBRT), surgical resection and intraoperative electron-beam radiotherapy (IOERT) for oligorecurrent gynecological cancer (ORGC). From January 1995 to December 2012, 61 patients with ORGC [uterine cervix (52 %), endometrial (30 %), ovarian (15 %), vagina (3 %)] underwent IOERT (12.5 Gy, range 10-15 Gy), and surgical resection to the pelvic (57 %) and paraaortic (43 %) recurrence tumor bed. In addition, 29 patients (48 %) also received EBRT (range 30.6-50.4 Gy). Survival outcomes were estimated using the Kaplan-Meier method, and risk factors were identified by univariate and multivariate analyses. Median follow-up time for the entire cohort of patients was 42 months (range 2-169 months). The 10-year rates for overall survival (OS) and locoregional control (LRC) were 17 and 65 %, respectively. On multivariate analysis, no tumor fragmentation (HR 0.22; p = 0.03), time interval from primary tumor diagnosis to locoregional recurrence (LRR) < 24 months (HR 4.02; p = 0.02) and no EBRT at the time of pelvic recurrence (HR 3.95; p = 0.02) retained significance with regard to LRR. Time interval from primary tumor to LRR < 24 months (HR 2.32; p = 0.02) and no EBRT at the time of pelvic recurrence (HR 3.77; p = 0.04) showed a significant association with OS after adjustment for other covariates. External-beam radiation therapy at the time of pelvic recurrence, time interval for relapse ≥24 months and not multi-involved fragmented resection specimens are associated with improved LRC in patients with ORGC. As suggested from the present analysis a significant group of ORGC patients could potentially benefit from multimodality rescue treatment. (orig.)

External-beam radiation therapy after surgical resection and intraoperative electron-beam radiation therapy for oligorecurrent gynecological cancer. Long-term outcome

Energy Technology Data Exchange (ETDEWEB)

Sole, C.V. [Hospital General Universitario Gregorio Maranon, Department of Oncology, Madrid (Spain); Complutense University, School of Medicine, Madrid (Spain); Instituto de Radiomedicina, Service of Radiation Oncology, Santiago (Chile); Hospital General Universitario Gregorio Maranon, Institute of Research Investigation, Madrid (Spain); Calvo, F.A. [Hospital General Universitario Gregorio Maranon, Department of Oncology, Madrid (Spain); Complutense University, School of Medicine, Madrid (Spain); Hospital General Universitario Gregorio Maranon, Institute of Research Investigation, Madrid (Spain); Lozano, M.A.; Gonzalez-Sansegundo, C. [Hospital General Universitario Gregorio Maranon, Department of Oncology, Madrid (Spain); Hospital General Universitario Gregorio Maranon, Service of Radiation Oncology, Madrid (Spain); Hospital General Universitario Gregorio Maranon, Institute of Research Investigation, Madrid (Spain); Gonzalez-Bayon, L. [Hospital General Universitario Gregorio Maranon, Service of General Surgery, Madrid (Spain); Hospital General Universitario Gregorio Maranon, Institute of Research Investigation, Madrid (Spain); Alvarez, A. [Hospital General Universitario Gregorio Maranon, Service of Radiation Oncology, Madrid (Spain); Hospital General Universitario Gregorio Maranon, Institute of Research Investigation, Madrid (Spain); Lizarraga, S. [Hospital General Universitario Gregorio Maranon, Department of Gynecology, Madrid (Spain); Hospital General Universitario Gregorio Maranon, Institute of Research Investigation, Madrid (Spain); Garcia-Sabrido, J.L. [Complutense University, School of Medicine, Madrid (Spain); Hospital General Universitario Gregorio Maranon, Service of General Surgery, Madrid (Spain); Hospital General Universitario Gregorio Maranon, Department of Gynecology, Madrid (Spain)

2014-02-15

The goal of the present study was to analyze prognostic factors in patients treated with external-beam radiation therapy (EBRT), surgical resection and intraoperative electron-beam radiotherapy (IOERT) for oligorecurrent gynecological cancer (ORGC). From January 1995 to December 2012, 61 patients with ORGC [uterine cervix (52 %), endometrial (30 %), ovarian (15 %), vagina (3 %)] underwent IOERT (12.5 Gy, range 10-15 Gy), and surgical resection to the pelvic (57 %) and paraaortic (43 %) recurrence tumor bed. In addition, 29 patients (48 %) also received EBRT (range 30.6-50.4 Gy). Survival outcomes were estimated using the Kaplan-Meier method, and risk factors were identified by univariate and multivariate analyses. Median follow-up time for the entire cohort of patients was 42 months (range 2-169 months). The 10-year rates for overall survival (OS) and locoregional control (LRC) were 17 and 65 %, respectively. On multivariate analysis, no tumor fragmentation (HR 0.22; p = 0.03), time interval from primary tumor diagnosis to locoregional recurrence (LRR) < 24 months (HR 4.02; p = 0.02) and no EBRT at the time of pelvic recurrence (HR 3.95; p = 0.02) retained significance with regard to LRR. Time interval from primary tumor to LRR < 24 months (HR 2.32; p = 0.02) and no EBRT at the time of pelvic recurrence (HR 3.77; p = 0.04) showed a significant association with OS after adjustment for other covariates. External-beam radiation therapy at the time of pelvic recurrence, time interval for relapse ≥24 months and not multi-involved fragmented resection specimens are associated with improved LRC in patients with ORGC. As suggested from the present analysis a significant group of ORGC patients could potentially benefit from multimodality rescue treatment. (orig.)

Adjuvant external beam radiotherapy in the treatment of endometrial cancer (MRC ASTEC and NCIC CTG EN.5 randomised trials): pooled trial results, systematic review, and meta-analysis.

Science.gov (United States)

Blake, P; Swart, Ann Marie; Orton, J; Kitchener, H; Whelan, T; Lukka, H; Eisenhauer, E; Bacon, M; Tu, D; Parmar, M K B; Amos, C; Murray, C; Qian, W

2009-01-10

Early endometrial cancer with low-risk pathological features can be successfully treated by surgery alone. External beam radiotherapy added to surgery has been investigated in several small trials, which have mainly included women at intermediate risk of recurrence. In these trials, postoperative radiotherapy has been shown to reduce the risk of isolated local recurrence but there is no evidence that it improves recurrence-free or overall survival. We report the findings from the ASTEC and EN.5 trials, which investigated adjuvant external beam radiotherapy in women with early-stage disease and pathological features suggestive of intermediate or high risk of recurrence and death from endometrial cancer. Between July, 1996, and March, 2005, 905 (789 ASTEC, 116 EN.5) women with intermediate-risk or high-risk early-stage disease from 112 centres in seven countries (UK, Canada, Poland, Norway, New Zealand, Australia, USA) were randomly assigned after surgery to observation (453) or to external beam radiotherapy (452). A target dose of 40-46 Gy in 20-25 daily fractions to the pelvis, treating five times a week, was specified. Primary outcome measure was overall survival, and all analyses were by intention to treat. These trials were registered ISRCTN 16571884 (ASTEC) and NCT 00002807 (EN.5). After a median follow-up of 58 months, 135 women (68 observation, 67 external beam radiotherapy) had died. There was no evidence that overall survival with external beam radiotherapy was better than observation, hazard ratio 1.05 (95% CI 0.75-1.48; p=0.77). 5-year overall survival was 84% in both groups. Combining data from ASTEC and EN.5 in a meta-analysis of trials confirmed that there was no benefit in terms of overall survival (hazard ratio 1.04; 95% CI 0.84-1.29) and can reliably exclude an absolute benefit of external beam radiotherapy at 5 years of more than 3%. With brachytherapy used in 53% of women in ASTEC/EN.5, the local recurrence rate in the observation group at 5 years

On Interactions of Oscillation Modes for a Weakly Non-Linear Undamped Elastic Beam with AN External Force

Science.gov (United States)

BOERTJENS, G. J.; VAN HORSSEN, W. T.

2000-08-01

In this paper an initial-boundary value problem for the vertical displacement of a weakly non-linear elastic beam with an harmonic excitation in the horizontal direction at the ends of the beam is studied. The initial-boundary value problem can be regarded as a simple model describing oscillations of flexible structures like suspension bridges or iced overhead transmission lines. Using a two-time-scales perturbation method an approximation of the solution of the initial-boundary value problem is constructed. Interactions between different oscillation modes of the beam are studied. It is shown that for certain external excitations, depending on the phase of an oscillation mode, the amplitude of specific oscillation modes changes.

External beam milli-PIXE as analytical tool for Neolithic obsidian provenance studies

Energy Technology Data Exchange (ETDEWEB)

Constantinescu, B.; Cristea-Stan, D. [National Institute for Nuclear Physics and Engineering Horia Hulubei, Bucharest-Magurele (Romania); Kovács, I.; Szõkefalvi-Nagy, Z. [Wigner Research Centre for Phyics, Institute for Particle and Nuclear Physics, Budapest (Hungary)

2013-07-01

Full text: Obsidian is the most important archaeological material used for tools and weapons before metals appearance. Its geological sources are limited and concentrated in few geographical zones: Armenia, Eastern Anatolia, Italian Lipari and Sardinia islands, Greek Melos and Yali islands, Hungarian and Slovak Tokaj Mountains. Due to this fact, in Mesolithic and Neolithic periods obsidian was the first archaeological material intensively traded even at long distances. To determine the geological provenance of obsidian and to identify the prehistoric long-range trade routes and possible population migrations elemental concentration ratios can help a 101, since each geological source has its 'fingerprints'. In this work external milli-PIXE technique was applied for elemental concentration ratio determinations in some Neolithic tools found in Transylvania and in the lron Gales region near Danube, and on few relevant geological samples (Slovak Tokaj Mountains, Lipari,Armenia). In Transylvania (the North-Western part of Romania, a region surrounded by Carpathian Mountains), Neolithic obsidian tools were discovered mainly in three regions: North-West - Oradea (near the border with Hungary, Slovakia and Ukraine), Centre -Cluj and Southwest- Banat (near the border with Serbia). A special case is lron Gales - Mesolithic and Early Neolithic sites, directly related to the appearance of agriculture replacing the Mesolithic economy based on hunting and fishing. Three long-distance trade routes could be considered: from Caucasus Mountains via North of the Black Sea, from Greek islands or Asia Minor via ex-Yugoslavia area or via Greece-Bulgaria or from Central Europe- Tokaj Mountains in the case of obsidian. As provenance 'fingerprints', we focused on Ti to Mn, and Rb-Sr-Y-Zr ratios. The measurements were performed at the external milli-PIXE beam-line of the 5MV VdG accelerator of the Wigner RCP. Proton energy of 3MeV and beam currents in the range of 1 ±1 D

External beam milli-PIXE as analytical tool for Neolithic obsidian provenance studies

International Nuclear Information System (INIS)

Constantinescu, B.; Cristea-Stan, D.; Kovács, I.; Szõkefalvi-Nagy, Z.

2013-01-01

Full text: Obsidian is the most important archaeological material used for tools and weapons before metals appearance. Its geological sources are limited and concentrated in few geographical zones: Armenia, Eastern Anatolia, Italian Lipari and Sardinia islands, Greek Melos and Yali islands, Hungarian and Slovak Tokaj Mountains. Due to this fact, in Mesolithic and Neolithic periods obsidian was the first archaeological material intensively traded even at long distances. To determine the geological provenance of obsidian and to identify the prehistoric long-range trade routes and possible population migrations elemental concentration ratios can help a 101, since each geological source has its 'fingerprints'. In this work external milli-PIXE technique was applied for elemental concentration ratio determinations in some Neolithic tools found in Transylvania and in the lron Gales region near Danube, and on few relevant geological samples (Slovak Tokaj Mountains, Lipari,Armenia). In Transylvania (the North-Western part of Romania, a region surrounded by Carpathian Mountains), Neolithic obsidian tools were discovered mainly in three regions: North-West - Oradea (near the border with Hungary, Slovakia and Ukraine), Centre -Cluj and Southwest- Banat (near the border with Serbia). A special case is lron Gales - Mesolithic and Early Neolithic sites, directly related to the appearance of agriculture replacing the Mesolithic economy based on hunting and fishing. Three long-distance trade routes could be considered: from Caucasus Mountains via North of the Black Sea, from Greek islands or Asia Minor via ex-Yugoslavia area or via Greece-Bulgaria or from Central Europe- Tokaj Mountains in the case of obsidian. As provenance 'fingerprints', we focused on Ti to Mn, and Rb-Sr-Y-Zr ratios. The measurements were performed at the external milli-PIXE beam-line of the 5MV VdG accelerator of the Wigner RCP. Proton energy of 3MeV and beam currents in the range of 1 ±1 D

A practical method to calculate head scatter factors in wedged rectangular and irregular MLC shaped beams for external and internal wedges

International Nuclear Information System (INIS)

Georg, Dietmar; Olofsson, Joergen; Kuenzler, Thomas; Aiginger, Hannes; Karlsson, Mikael

2004-01-01

Factor based methods for absorbed dose or monitor unit calculations are often based on separate data sets for open and wedged beams. The determination of basic beam parameters can be rather time consuming, unless equivalent square methods are applied. When considering irregular wedged beams shaped with a multileaf collimator, parametrization methods for dosimetric quantities, e.g. output ratios or wedge factors as a function of field size and shape, become even more important. A practical method is presented to derive wedged output ratios in air (S c,w ) for any rectangular field and for any irregular MLC shaped beam. This method was based on open field output ratios in air (S c ) for a field with the same collimator setting, and a relation f w between S c,w and S c . The relation f w can be determined from measured output ratios in air for a few open and wedged fields including the maximum wedged field size. The function f w and its parametrization were dependent on wedge angle and treatment head design, i.e. they were different for internal and external wedges. The proposed method was tested for rectangular wedged fields on three accelerators with internal wedges (GE, Elekta, BBC) and two accelerators with external wedges (Varian). For symmetric regular beams the average deviation between calculated and measured S c,w /S c ratios was 0.3% for external wedges and about 0.6% for internal wedges. Maximum deviations of 1.8% were obtained for elongated rectangular fields on the GE and ELEKTA linacs with an internal wedge. The same accuracy was achieved for irregular MLC shaped wedged beams on the accelerators with MLC and internal wedges (GE and Elekta), with an average deviation <1% for the fields tested. The proposed method to determine output ratios in air for wedged beams from output ratios of open beams, combined with equivalent square approaches, can be easily integrated in empirical or semi-empirical methods for monitor unit calculations

Optimum location of external markers using feature selection algorithms for real-time tumor tracking in external-beam radiotherapy: a virtual phantom study.

Science.gov (United States)

Nankali, Saber; Torshabi, Ahmad Esmaili; Miandoab, Payam Samadi; Baghizadeh, Amin

2016-01-08

In external-beam radiotherapy, using external markers is one of the most reliable tools to predict tumor position, in clinical applications. The main challenge in this approach is tumor motion tracking with highest accuracy that depends heavily on external markers location, and this issue is the objective of this study. Four commercially available feature selection algorithms entitled 1) Correlation-based Feature Selection, 2) Classifier, 3) Principal Components, and 4) Relief were proposed to find optimum location of external markers in combination with two "Genetic" and "Ranker" searching procedures. The performance of these algorithms has been evaluated using four-dimensional extended cardiac-torso anthropomorphic phantom. Six tumors in lung, three tumors in liver, and 49 points on the thorax surface were taken into account to simulate internal and external motions, respectively. The root mean square error of an adaptive neuro-fuzzy inference system (ANFIS) as prediction model was considered as metric for quantitatively evaluating the performance of proposed feature selection algorithms. To do this, the thorax surface region was divided into nine smaller segments and predefined tumors motion was predicted by ANFIS using external motion data of given markers at each small segment, separately. Our comparative results showed that all feature selection algorithms can reasonably select specific external markers from those segments where the root mean square error of the ANFIS model is minimum. Moreover, the performance accuracy of proposed feature selection algorithms was compared, separately. For this, each tumor motion was predicted using motion data of those external markers selected by each feature selection algorithm. Duncan statistical test, followed by F-test, on final results reflected that all proposed feature selection algorithms have the same performance accuracy for lung tumors. But for liver tumors, a correlation-based feature selection algorithm, in

Treatment of Head and Neck Paragangliomas With External Beam Radiation Therapy

International Nuclear Information System (INIS)

Dupin, Charles; Lang, Philippe; Dessard-Diana, Bernadette; Simon, Jean-Marc; Cuenca, Xavier; Mazeron, Jean-Jacques; Feuvret, Loïc

2014-01-01

Purpose: To retrospectively assess the outcomes of radiation therapy in patients with head and neck paragangliomas. Methods and Materials: From 1990 to 2009, 66 patients with 81 head and neck paragangliomas were treated by conventional external beam radiation therapy in 25 fractions at a median dose of 45 Gy (range, 41.4-68 Gy). One case was malignant. The median gross target volume and planning target volume were 30 cm 3 (range, 0.9-243 cm 3 ) and 116 cm 3 (range, 24-731 cm 3 ), respectively. Median age was 57.4 years (range, 15-84 years). Eleven patients had multicentric lesions, and 8 had family histories of paraganglioma. Paragangliomas were located in the temporal bone, the carotid body, and the glomus vagal in 51, 18, and 10 patients, respectively. Forty-six patients had exclusive radiation therapy, and 20 had salvage radiation therapy. The median follow-up was 4.1 years (range, 0.1-21.2 years). Results: One patient had a recurrence of temporal bone paraganglioma 8 years after treatment. The actuarial local control rates were 100% at 5 years and 98.7% at 10 years. Patients with multifocal tumors and family histories were significantly younger (42 years vs 58 years [P=.002] and 37 years vs 58 years [P=.0003], respectively). The association between family predisposition and multifocality was significant (P<.001). Two patients had cause-specific death within the 6 months after irradiation. During radiation therapy, 9 patients required hospitalization for weight loss, nausea, mucositis, or ophthalmic zoster. Two late vascular complications occurred (middle cerebral artery and carotid stenosis), and 2 late radiation-related meningiomas appeared 15 and 18 years after treatment. Conclusion: Conventional external beam radiation therapy is an effective and safe treatment option that achieves excellent local control; it should be considered as a first-line treatment of choice for head and neck paragangliomas

Quasi-plane-hypothesis of strain coordination for RC beams seismically strengthened with externally-bonded or near-surface mounted fiber reinforced plastic

Science.gov (United States)

Ren, Zhenhua; Zeng, Xiantao; Liu, Hanlong; Zhou, Fengjun

2013-03-01

The application of fiber reinforced plastic (FRP), including carbon FRP and glass FRP, for structural repair and strengthening has grown due to their numerous advantages over conventional materials such as externally bonded reinforcement (EBR) and near-surface mounted (NSM) strengthening techniques. This paper summarizes the results from 21 reinforced concrete beams strengthened with different methods, including externally-bonded and near-surface mounted FRP, to study the strain coordination of the FRP and steel rebar of the RC beam. Since there is relative slipping between the RC beam and the FRP, the strain of the FRP and steel rebar of the RC beam satisfy the quasi-plane-hypothesis; that is, the strain of the longitudinal fiber that parallels the neutral axis of the plated beam within the scope of the effective height ( h 0) of the cross section is in direct proportion to the distance from the fiber to the neutral axis. The strain of the FRP and steel rebar satisfies the equation: ɛ FRP= βɛ steel, and the value of β is equal to 1.1-1.3 according to the test results.

X-ray Beam Spectral Reconstruction Using Laplace Transform and Attenuation Curves

International Nuclear Information System (INIS)

Maeng, Seongjin; Lee, Sang Hoo; Kwon, Dahye; Seo, Jihye; Seo, Kyung Won

2015-01-01

As the use of X-ray tubes is widely spread mainly for medical diagnostic purposes or industrial applications, there is increasing demand for accurate and convenient way getting of X-ray beam spectral information. While measurement methods may provide quite accurate spectral information, these methods still require expensive detectors (example: HPGe, High Purity Germanium detector) and some conversion of measurement information into real spectrum. It is concluded that Laplace transform-based spectral reconstruction technique given in equations (1) and (2) works well for a 50-kV X-ray source. In this paper we obtained the attenuation curve by the use of MCNPX simulations. We were able to rebuild the X-ray spectrum of 50 kV through this research by Monte Carlo simulation (fitting parameters, a: 1.2921, b: 0.2342, ν: 0.6190, R-squared: 0.9930)

A simple technique for treating age-related macular degeneration with external beam radiotherapy

International Nuclear Information System (INIS)

Roos, Daniel E.; Francis, J. Winston; Newnham, W. John

1999-01-01

Purpose: To develop a simple external beam photon radiotherapy technique to treat age-related macular degeneration without the need for simulation, planning computed tomography (CT) or computer dosimetry. Methods and Materials: The goal was to enable the treatment to be set up reliably on the treatment machine on Day 1 with the patient supine in a head cast without any prior planning. Using measurements of ocular globe topography from Karlsson et al. (Int J Radiat Oncol Biol Phys 1996; 33: 705-712), we chose a point 1.5 cm behind the anterior surface of the upper eyelid (ASUE) as the isocentre of a half-beam, blocked, 5.0 x 3.0-cm, angled lateral field to treat the involved eye. This would position the isocentre about 0.5 cm behind the posterior surface of the lens, and a little over 1 cm in front of the macula, according to Karlsson et al. The setup requires initial adjustment of the gantry from horizontal (to account for any asymmetry of position of the eyes), then angling 15 deg. posteriorly to avoid the contralateral eye. Finally, the couch is raised to position the isocentre 1.5 cm behind the ASUE. Results: To verify the applicability of the technique, we performed CT and computer dosimetry on the first 11 eyes so treated. Our CT measurements were in good agreement with Karlsson et al. The lens dose was < 5% and the macula was within the 95% isodose curve in each case (6-MV linac). Treatment setup time is approximately 10 min each day. The 11 patients were treated with 5 x 2.00 Gy (2 patients) or 5 x 3.00 Gy (9 patients), and subjective response on follow-up over 1 to 12 months (median 4 months) was comparable to previously reported results, with no significant acute side effects. Conclusion: Our technique is easy to set up and reliably treats the macula, with sparing of the lens and contralateral eye. It enables treatment to commence rapidly and cost-effectively without the need for simulation or CT computer planning

External Beam Radiotherapy for Prostate Cancer Patients on Anticoagulation Therapy: How Significant is the Bleeding Toxicity?

International Nuclear Information System (INIS)

Choe, Kevin S.; Jani, Ashesh B.; Liauw, Stanley L.

2010-01-01

Purpose: To characterize the bleeding toxicity associated with external beam radiotherapy for prostate cancer patients receiving anticoagulation (AC) therapy. Methods and Materials: The study cohort consisted of 568 patients with adenocarcinoma of the prostate who were treated with definitive external beam radiotherapy. Of these men, 79 were receiving AC therapy with either warfarin or clopidogrel. All patients were treated with three-dimensional conformal radiotherapy or intensity-modulated radiotherapy. Bleeding complications were recorded during treatment and subsequent follow-up visits. Results: With a median follow-up of 48 months, the 4-year actuarial risk of Grade 3 or worse bleeding toxicity was 15.5% for those receiving AC therapy compared with 3.6% among those not receiving AC (p < .0001). On multivariate analysis, AC therapy was the only significant factor associated with Grade 3 or worse bleeding (p < .0001). For patients taking AC therapy, the crude rate of bleeding was 39.2%. Multivariate analysis within the AC group demonstrated that a higher radiotherapy dose (p = .0408), intensity-modulated radiotherapy (p = 0.0136), and previous transurethral resection of the prostate (p = .0001) were associated with Grade 2 or worse bleeding toxicity. Androgen deprivation therapy was protective against bleeding, with borderline significance (p = 0.0599). Dose-volume histogram analysis revealed that Grade 3 or worse bleeding was minimized if the percentage of the rectum receiving ≥70 Gy was <10% or the rectum receiving ≥50 Gy was <50%. Conclusion: Patients taking AC therapy have a substantial risk of bleeding toxicity from external beam radiotherapy. In this setting, dose escalation or intensity-modulated radiotherapy should be used judiciously. With adherence to strict dose-volume histogram criteria and minimizing hotspots, the risk of severe bleeding might be reduced.

SRF cavity alignment detection method using beam-induced HOM with curved beam orbit

Science.gov (United States)

Hattori, Ayaka; Hayano, Hitoshi

2017-09-01

We have developed a method to obtain mechanical centers of nine cell superconducting radio frequency (SRF) cavities from localized dipole modes, that is one of the higher order modes (HOM) induced by low-energy beams. It is to be noted that low-energy beams, which are used as alignment probes, are easy to bend in fringe fields of accelerator cavities. The estimation of the beam passing orbit is important because only information about the beam positions measured by beam position monitors outside the cavities is available. In this case, the alignment information about the cavities can be obtained by optimizing the parameters of the acceleration components over the beam orbit simulation to consistently represent the position of the beam position monitors measured at every beam sweep. We discuss details of the orbit estimation method, and estimate the mechanical center of the localized modes through experiments performed at the STF accelerator. The mechanical center is determined as (x , y) =(0 . 44 ± 0 . 56 mm , - 1 . 95 ± 0 . 40 mm) . We also discuss the error and the applicable range of this method.

Research of transportation efficiency of low-energy high- current electron beam in plasma channel in external magnetic field

International Nuclear Information System (INIS)

Vagin, E S; Grigoriev, V P

2015-01-01

Effective high current (5-20 kA) and low energy (tens of keV) electrons beam transportation is possible only with almost complete charging neutralization. It is also necessary to use quite high current neutralization for elimination beam self-pinching effect. The research is based on the self-consistent mathematical model that takes into account beam and plasma particles dynamic, current and charge neutralization of electron beam and examines the transportation of electron beam into a chamber with low-pressure plasma in magnetic field. A numerical study was conducted using particle in cell (PIC) method. The study was performed with various system parameters: rise time and magnitude of the beam current, gas pressure and plasma density and geometry of the system. Regularities of local virtual cathode field generated by the beam in the plasma channel, as well as ranges of parameters that let transportation beam with minimal losses, depending on the external magnetic field were determined through a series of numerical studies. In addition, the assessment of the impact of the plasma ion mobility during the transition period and during steady beam was performed. (paper)

Radiation dose to laterally transposed ovaries during external beam radiotherapy for cervical cancer

International Nuclear Information System (INIS)

Mazonakis, Michael; Damilakis, John; Varveris, Haris; Gourtsoyiannis, Nicholas

2006-01-01

The purpose of this study was to estimate the radiation dose to laterally transposed ovaries from external beam radiotherapy for cervical cancer. Dose measurements were performed in a modified humanoid phantom using a 6 MV photon beam. The dependence of the ovarian dose upon the field size, the distance from the primary irradiation field and the presence of wedges or gonadal shielding was determined. For a tumor dose of 45 Gy, ovarian dose was 0.88-8.51 Gy depending on the field size employed and the location of the transposed ovary in respect to the treatment field. Positioning of 7 cm thick shielding reduced the dose to ovary by less than 19%. The use of wedges increased the ovarian dose by a factor up to 1.5. Accurate radiographic localization of the ovaries allows the use of the presented dosimetric results to obtain a reasonable prediction of the ovarian dose

Technique of Injection of Hyaluronic Acid as a Prostatic Spacer and Fiducials Before Hypofractionated External Beam Radiotherapy for Prostate Cancer.

Science.gov (United States)

Boissier, Romain; Udrescu, Corina; Rebillard, Xavier; Terrier, Jean-Etienne; Faix, Antoine; Chapet, Olivier; Azria, David; Devonec, Marian; Paparel, Philippe; Ruffion, Alain

2017-01-01

To describe a technique combining the implantation of fiducials and a prostatic spacer (hyaluronic acid [HA]) to decrease the rectal toxicity after an image-guided external beam radiotherapy (EBRT) with hypofractionation for prostate cancer and to assess the tolerance and the learning curve of the procedure. Thirty patients with prostate cancer at low or intermediate risk were included in a phase II trial: image-guided EBRT of 62 Gy in 20 fractions of 3.1 Gy with intensity-modulated radiotherapy. A transrectal implantation of 3 fiducials and transperineal injection of 10 cc of HA (NASHA gel spacer, Q-Med AB, Uppsala, Sweden) between the rectum and the prostate was performed by 1 operator. The thickness of HA was measured at 10 points on magnetic resonance imaging to establish a quality score of the injection (maximum score = 10) and determine the learning curve of the procedure. The quality score increased from patients 1-10, 11-20, to 21-30 with respective median scores: 7 [2-10], 5 [4-7], and 8 [3-10]. The average thicknesses of HA between the base, middle part, and apex of the prostate and the rectum were the following: 15.1 mm [6.4-29], 9.8 mm [5-21.2], and 9.9 mm [3.2-21.5]. The injection of the HA induced a median pain score of 4 [1-8] and no residual pain at mid-long term. Creating an interface between the rectum and the prostate and the implantation of fiducials were feasible under local anesthesia with a short learning curve and could become a standard procedure before a hypofractionated EBRT for prostate cancer. Copyright © 2016 Elsevier Inc. All rights reserved.

Anticipated Intraoperative Electron Beam Boost, External Beam Radiation Therapy, and Limb-Sparing Surgical Resection for Patients with Pediatric Soft-Tissue Sarcomas of the Extremity: A Multicentric Pooled Analysis of Long-Term Outcomes

Energy Technology Data Exchange (ETDEWEB)

Sole, Claudio V., E-mail: cvsole@uc.cl [Department of Oncology, Hospital General Universitario Gregorio Marañón, Madrid (Spain); School of Medicine, Complutense University, Madrid (Spain); Service of Radiation Oncology, Instituto de Radiomedicina, Santiago (Chile); Calvo, Felipe A. [Department of Oncology, Hospital General Universitario Gregorio Marañón, Madrid (Spain); School of Medicine, Complutense University, Madrid (Spain); Polo, Alfredo [Service of Radiation Oncology, Hospital Universitario Ramón y Cajal, Madrid (Spain); Cambeiro, Mauricio [Service of Radiation Oncology, Clínica Universidad de Navarra, Pamplona (Spain); Alvarez, Ana; Gonzalez, Carmen [Service of Radiation Oncology, Hospital General Universitario Gregorio Marañón, Madrid (Spain); Gonzalez, Jose [Service of Pediatric Orthopedics and Traumatology, Hospital General Universitario Gregorio Marañón, Madrid (Spain); San Julian, Mikel [Service of Orthopedics and Traumatology, Clínica Universidad de Navarra, Pamplona (Spain); Martinez-Monge, Rafael [Service of Radiation Oncology, Clínica Universidad de Navarra, Pamplona (Spain)

2014-09-01

Purpose: To perform a joint analysis of data from 3 contributing centers within the intraoperative electron-beam radiation therapy (IOERT)-Spanish program, to determine the potential of IOERT as an anticipated boost before external beam radiation therapy in the multidisciplinary treatment of pediatric extremity soft-tissue sarcomas. Methods and Materials: From June 1993 to May 2013, 62 patients (aged <21 years) with a histologic diagnosis of primary extremity soft-tissue sarcoma with absence of distant metastases, undergoing limb-sparing grossly resected surgery, external beam radiation therapy (median dose 40 Gy) and IOERT (median dose 10 Gy) were considered eligible for this analysis. Results: After a median follow-up of 66 months (range, 4-235 months), 10-year local control, disease-free survival, and overall survival was 85%, 76%, and 81%, respectively. In multivariate analysis after adjustment for other covariates, tumor size >5 cm (P=.04) and R1 margin status (P=.04) remained significantly associated with local relapse. In regard to overall survival only margin status (P=.04) retained association on multivariate analysis. Ten patients (16%) reported severe chronic toxicity events (all grade 3). Conclusions: An anticipated IOERT boost allowed for external beam radiation therapy dose reduction, with high local control and acceptably low toxicity rates. The combined radiosurgical approach needs to be tested in a prospective trial to confirm these results.

Anticipated Intraoperative Electron Beam Boost, External Beam Radiation Therapy, and Limb-Sparing Surgical Resection for Patients with Pediatric Soft-Tissue Sarcomas of the Extremity: A Multicentric Pooled Analysis of Long-Term Outcomes

International Nuclear Information System (INIS)

Sole, Claudio V.; Calvo, Felipe A.; Polo, Alfredo; Cambeiro, Mauricio; Alvarez, Ana; Gonzalez, Carmen; Gonzalez, Jose; San Julian, Mikel; Martinez-Monge, Rafael

2014-01-01

Purpose: To perform a joint analysis of data from 3 contributing centers within the intraoperative electron-beam radiation therapy (IOERT)-Spanish program, to determine the potential of IOERT as an anticipated boost before external beam radiation therapy in the multidisciplinary treatment of pediatric extremity soft-tissue sarcomas. Methods and Materials: From June 1993 to May 2013, 62 patients (aged <21 years) with a histologic diagnosis of primary extremity soft-tissue sarcoma with absence of distant metastases, undergoing limb-sparing grossly resected surgery, external beam radiation therapy (median dose 40 Gy) and IOERT (median dose 10 Gy) were considered eligible for this analysis. Results: After a median follow-up of 66 months (range, 4-235 months), 10-year local control, disease-free survival, and overall survival was 85%, 76%, and 81%, respectively. In multivariate analysis after adjustment for other covariates, tumor size >5 cm (P=.04) and R1 margin status (P=.04) remained significantly associated with local relapse. In regard to overall survival only margin status (P=.04) retained association on multivariate analysis. Ten patients (16%) reported severe chronic toxicity events (all grade 3). Conclusions: An anticipated IOERT boost allowed for external beam radiation therapy dose reduction, with high local control and acceptably low toxicity rates. The combined radiosurgical approach needs to be tested in a prospective trial to confirm these results

Interstitial gold and external beam irradiation for prostate cancer

International Nuclear Information System (INIS)

Boileau, M.A.; Dowling, R.A.; Gonzales, M.; Handel, P.H.; Benson, G.S.; Corriere, J.N. Jr.

1988-01-01

We treated 65 patients with prostatic cancer confined clinically to the prostate or periprostatic area during an 8-year period. Seven patients had stage A2, 38 stage B and 20 stage C disease. All 65 patients underwent staging pelvic lymphadenectomy and implantation of gold grains into the prostate (mean dose 3,167 rad). A total of 64 patients then completed a course of external beam irradiation to a mean total tumor dose of 6,965 rad. Complications of therapy were mild and limited (less than 3 months in duration) in most patients, and they included radiation cystitis (32 per cent), diarrhea (31 per cent), extremity lymphedema (7.7 per cent) and wound infection (3 per cent). Two patients suffered urinary incontinence after therapy and 2 (3 per cent) had diarrhea more than 3 months in duration. The actuarial 5-year survival rate for all patients was 87 per cent and the 5-year survival free of disease was 72 per cent

Dosimetric comparison between intensity modulated brachytherapy versus external beam intensity modulated radiotherapy for cervix cancer: a treatment planning study

International Nuclear Information System (INIS)

Subramani, V.; Sharma, D.N.; Jothy Basu, K.S.; Rath, G.K.; Gopishankar, N.

2008-01-01

To evaluate the dosimetric superiority of intensity modulated brachytherapy (IMBT) based on inverse planning optimization technique with classical brachytherapy optimization and also with external beam intensity modulated radiotherapy planning technique in patients of cervical carcinoma

Internal hemipelvectomy with intraoperative and external beam radiotherapy in the limb-sparing treatment of a pelvic girdle chondrosarcoma

NARCIS (Netherlands)

Hoekstra, HJ; Szabo, BG

The case of a patient with an extensive pelvic girdle chondrosarcoma treated with internal hemipelvectomy and intraoperative radiotherapy, followed by adjuvant high-dose external beam radiotherapy, with a successful attempt in achieving long-term local tumor control and limb-sparing treatment is

Magneto-electro-elastic buckling analysis of nonlocal curved nanobeams

Science.gov (United States)

Ebrahimi, Farzad; Reza Barati, Mohammad

2016-09-01

In this work, a size-dependent curved beam model is developed to take into account the effects of nonlocal stresses on the buckling behavior of curved magneto-electro-elastic FG nanobeams for the first time. The governing differential equations are derived based on the principle of virtual work and Euler-Bernoulli beam theory. The power-law function is employed to describe the spatially graded magneto-electro-elastic properties. By extending the radius of the curved nanobeam to infinity, the results of straight nonlocal FG beams can be rendered. The effects of magnetic potential, electric voltage, opening angle, nonlocal parameter, power-law index and slenderness ratio on buckling loads of curved MEE-FG nanobeams are studied.

Phase-space database for external beam radiotherapy. Summary report of a consultants' meeting

International Nuclear Information System (INIS)

Capote, R.; Jeraj, R.; Ma, C.M.; Rogers, D.W.O.; Sanchez-Doblado, F.; Sempau, J.; Seuntjens, J.; Siebers, J.V.

2006-01-01

A summary is given of a Consultants' Meeting assembled to discuss and recommend actions and activities to prepare a Phase-space Database for External Beam Radiotherapy. The new database should serve to disseminate phase-space data of those accelerators and 60 Co units used in radiotherapy through the compilation of existing data that have been properly validated. Both the technical discussions and the resulting work plan are described, along with the detailed recommendations for implementation. The meeting was jointly organized by NAPC-Nuclear Data Section and NAHU-Dosimetry and Medical Radiation Physics Section. (author)

Development of a multi-detector and a systematic imaging system on the AGLAE external beam

International Nuclear Information System (INIS)

Pichon, L.; Moignard, B.; Lemasson, Q.; Pacheco, C.; Walter, P.

2014-01-01

The New AGLAE external beamline provides analytical data for the understanding of the structure of archaeological and artistic objects, their composition, properties, and changes over time. One of the objectives of this project is to design and set up a new non-invasive acquisition system increasing the quality of the X-ray spectra and reducing the beam current on sensitive materials from work of art. To that end, the surface and the number of PIXE detectors have been increased to implement a cluster of SDD detectors. This can also provide the possibility to accomplish large and/or fast maps on artifacts with a scanning of the beam on the sample. During the mapping, a multi-parameter system saves each event from X-ray, gamma and particle detectors, simultaneously with the X and Y positions of the beam on the sample. To process the data, different softwares have been developed or updated. A first example on a decorated medieval shard highlights the perspectives of the technique

Development of a multi-detector and a systematic imaging system on the AGLAE external beam

Energy Technology Data Exchange (ETDEWEB)

Pichon, L., E-mail: laurent.pichon@culture.gouv.fr [Centre de recherche et de restauration des musées de France, C2RMF, Palais du Louvre – Porte des Lions, 14 Quai François Mitterrand, 75001 Paris (France); Fédération de recherche NewAGLAE, FR3506 CNRS/Ministère de la Culture/UPMC, Palais du Louvre, 75001 Paris (France); Moignard, B.; Lemasson, Q.; Pacheco, C. [Centre de recherche et de restauration des musées de France, C2RMF, Palais du Louvre – Porte des Lions, 14 Quai François Mitterrand, 75001 Paris (France); Fédération de recherche NewAGLAE, FR3506 CNRS/Ministère de la Culture/UPMC, Palais du Louvre, 75001 Paris (France); Walter, P. [Fédération de recherche NewAGLAE, FR3506 CNRS/Ministère de la Culture/UPMC, Palais du Louvre, 75001 Paris (France); UPMC Univ Paris 06, CNRS-UMR 8220, Laboratoire d’archéologie moléculaire et structurale, LAMS, F-75005 Paris (France)

2014-01-01

The New AGLAE external beamline provides analytical data for the understanding of the structure of archaeological and artistic objects, their composition, properties, and changes over time. One of the objectives of this project is to design and set up a new non-invasive acquisition system increasing the quality of the X-ray spectra and reducing the beam current on sensitive materials from work of art. To that end, the surface and the number of PIXE detectors have been increased to implement a cluster of SDD detectors. This can also provide the possibility to accomplish large and/or fast maps on artifacts with a scanning of the beam on the sample. During the mapping, a multi-parameter system saves each event from X-ray, gamma and particle detectors, simultaneously with the X and Y positions of the beam on the sample. To process the data, different softwares have been developed or updated. A first example on a decorated medieval shard highlights the perspectives of the technique.

On finding the analytic dependencies of the external field potential on the control function when optimizing the beam dynamics

Science.gov (United States)

Ovsyannikov, A. D.; Kozynchenko, S. A.; Kozynchenko, V. A.

2017-12-01

When developing a particle accelerator for generating the high-precision beams, the injection system design is of importance, because it largely determines the output characteristics of the beam. At the present paper we consider the injection systems consisting of electrodes with given potentials. The design of such systems requires carrying out simulation of beam dynamics in the electrostatic fields. For external field simulation we use the new approach, proposed by A.D. Ovsyannikov, which is based on analytical approximations, or finite difference method, taking into account the real geometry of the injection system. The software designed for solving the problems of beam dynamics simulation and optimization in the injection system for non-relativistic beams has been developed. Both beam dynamics and electric field simulations in the injection system which use analytical approach and finite difference method have been made and the results presented in this paper.

The external beam facility used to characterize corrosion products in metallic statuettes

International Nuclear Information System (INIS)

Rizzutto, M.A.; Tabacniks, M.H.; Added, N.; Barbosa, M.D.L.; Curado, J.F.; Santos, W.A.; Lima, S.C.; Melo, H.G.; Neiva, A.C.

2005-01-01

To open new possibilities in nuclear applied physics research, mainly for the analysis of art objects in air, an external beam facility was installed at LAMFI (Laboratorio de Analise de Materiais por Feixes Ionicos) of University of Sao Paulo. PIXE measurements were made using an XR-100CR (Si-PIN) X-ray detector pointed to the sample mounted after an approximate 11 mm air path, hence with effective beam energy of 0.9 MeV. This setup was used to characterize the corrosion products of two ethnological metallic statuettes from the African collection of the Museum of Archaeology and Etnology. PIXE analysis of the corrosion free base of one statuette showed that Cu and Zn are the main components of the alloy, while Pb is present in smaller amount. The analysis of some corrosion products showed a Zn:Cu relationship higher than that of the base, evidencing selective corrosion. The main components of the other statuette were Cu and Pb, while S and Zn were found in smaller amounts

Minimal requirements for quality controls in radiotherapy with external beams; Controlli di qualita' essenziali in radioterapia con fasci esterni

Energy Technology Data Exchange (ETDEWEB)

NONE

1999-07-01

Physical dosimetric guidelines have been developed by the Italian National Institute of Health study group on quality assurance in radiotherapy to define protocols for quality controls in external beam radiotherapy. While the document does not determine strict rules or firm recommendations, it suggests minimal requirements for quality controls necessary to guarantee an adequate degree of accuracy in external beam radiotherapy. [Italian] Il gruppo di studio Assicurazione di qualita' in radioterapia dell'Istituto Superiore di Sanita' presenta le linee guida per la stesura dei protocolli di controllo di qualita' essenziali necessari a garantire un adeguato livello di accuratezza del trattamento radiante e rappresenta pertanto una parte essenziale del contributo fisico-dosimetrico globale di assicurazione di qualita' in radioterapia con fasci esterni.

Serum testosterone levels after external beam radiation for clinically localized prostate cancer

International Nuclear Information System (INIS)

Zagars, Gunar K.; Pollack, Alan

1997-01-01

Purpose: To determine whether serum total testosterone levels change after external beam radiation therapy for localized prostate cancer. Methods and Materials: Eighty-five men with clinically localized prostate cancer (T1-T3, N0/NX, M0) who underwent external beam radiation therapy without androgen ablation had pretreatment and 3-month posttreatment total serum testosterone levels determined by radioimmunoassay. Scattered doses to the testicles were measured with thermoluminescent dosimetry in 10 men. Results: Pretreatment serum testosterone levels ranged from 185 to 783 ng/dl, with a mean of 400 ng/dl and a median of 390 ng/dl. The coefficient of variation was 30%. Postradiation 3-month testosterone levels ranged from 163 ng/dl to 796 ng/dl, with mean and median values of 356 ng/dl and 327 ng/ml, respectively. The coefficient of variation was 34%. The 3-month value was significantly lower than the pretreatment value (Wilcoxon paired p = 0.0001). The mean absolute fall was 94 ng/dl and the mean percentage fall was 9%. Although the fall in testosterone level was statistically significant, the difference was very small quantitatively. In contrast, serum prostate-specific antigen levels fell dramatically by 3 months after radiation. Testicular scattered doses ranged from 1.84 to 2.42 Gy, with a mean of 2.07 Gy for a prostatic tumor dose of 68 Gy. Conclusions: Although significant, the fall in serum testosterone level after radiation for localized prostate cancer was small and likely of no pathophysiologic consequence. It is unlikely that scattered testicular radiation plays any significant role in the genesis of this change in testosterone level, which most likely occurs as a nonspecific stress response

SU-E-T-571: Newly Emerging Integrated Transmission Detector Systems Provide Online Quality Assurance of External Beam Radiation Therapy

International Nuclear Information System (INIS)

Hoffman, D; Chung, E; Hess, C; Stern, R; Benedict, S

2015-01-01

Purpose: Two newly emerging transmission detectors positioned upstream from the patient have been evaluated for online quality assurance of external beam radiotherapy. The prototype for the Integral Quality Monitor (IQM), developed by iRT Systems GmbH (Koblenz, Germany) is a large-area ion chamber mounted on the linac accessory tray to monitor photon fluence, energy, beam shape, and gantry position during treatment. The ion chamber utilizes a thickness gradient which records variable response dependent on beam position. The prototype of Delta4 Discover™, developed by ScandiDos (Uppsala, Sweden) is a linac accessory tray mounted 4040 diode array that measures photon fluence during patient treatment. Both systems are employable for patient specific QA prior to treatment delivery. Methods: Our institution evaluated the reproducibility of measurements using various beam types, including VMAT treatment plans with both the IQM ion chamber and the Delta4 Discover diode array. Additionally, the IQM’s effect on photon fluence, dose response, simulated beam error detection, and the accuracy of the integrated barometer, thermometer, and inclinometer were characterized. The evaluated photon beam errors are based on the annual tolerances specified in AAPM TG-142. Results: Repeated VMAT treatments were measured with 0.16% reproducibility by the IQM and 0.55% reproducibility by the Delta4 Discover. The IQM attenuated 6, 10, and 15 MV photon beams by 5.43±0.02%, 4.60±0.02%, and 4.21±0.03% respectively. Photon beam profiles were affected <1.5% in the non-penumbra regions. The IQM’s ion chamber’s dose response was linear and the thermometer, barometer, and inclinometer agreed with other calibrated devices. The device detected variations in monitor units delivered (1%), field position (3mm), single MLC leaf positions (13mm), and photon energy. Conclusion: We have characterized two new transmissions detector systems designed to provide in-vivo like measurements upstream

SU-E-T-571: Newly Emerging Integrated Transmission Detector Systems Provide Online Quality Assurance of External Beam Radiation Therapy

Energy Technology Data Exchange (ETDEWEB)

Hoffman, D; Chung, E; Hess, C; Stern, R; Benedict, S [UC Davis Cancer Center, Sacramento, CA (United States)

2015-06-15

Purpose: Two newly emerging transmission detectors positioned upstream from the patient have been evaluated for online quality assurance of external beam radiotherapy. The prototype for the Integral Quality Monitor (IQM), developed by iRT Systems GmbH (Koblenz, Germany) is a large-area ion chamber mounted on the linac accessory tray to monitor photon fluence, energy, beam shape, and gantry position during treatment. The ion chamber utilizes a thickness gradient which records variable response dependent on beam position. The prototype of Delta4 Discover™, developed by ScandiDos (Uppsala, Sweden) is a linac accessory tray mounted 4040 diode array that measures photon fluence during patient treatment. Both systems are employable for patient specific QA prior to treatment delivery. Methods: Our institution evaluated the reproducibility of measurements using various beam types, including VMAT treatment plans with both the IQM ion chamber and the Delta4 Discover diode array. Additionally, the IQM’s effect on photon fluence, dose response, simulated beam error detection, and the accuracy of the integrated barometer, thermometer, and inclinometer were characterized. The evaluated photon beam errors are based on the annual tolerances specified in AAPM TG-142. Results: Repeated VMAT treatments were measured with 0.16% reproducibility by the IQM and 0.55% reproducibility by the Delta4 Discover. The IQM attenuated 6, 10, and 15 MV photon beams by 5.43±0.02%, 4.60±0.02%, and 4.21±0.03% respectively. Photon beam profiles were affected <1.5% in the non-penumbra regions. The IQM’s ion chamber’s dose response was linear and the thermometer, barometer, and inclinometer agreed with other calibrated devices. The device detected variations in monitor units delivered (1%), field position (3mm), single MLC leaf positions (13mm), and photon energy. Conclusion: We have characterized two new transmissions detector systems designed to provide in-vivo like measurements upstream

Measurement and properties of the dose-area product ratio in external small-beam radiotherapy.

Science.gov (United States)

Niemelä, Jarkko; Partanen, Mari; Ojala, Jarkko; Sipilä, Petri; Björkqvist, Mikko; Kapanen, Mika; Keyriläinen, Jani

2017-06-21

In small-beam radiation therapy (RT) the measurement of the beam quality parameter, i.e. the tissue-phantom ratio or TPR 20,10 , using a conventional point detector is a challenge. To obtain reliable results, one has to consider potential sources of error, including volume averaging and adjustment of the point detector into the narrow beam. To overcome these challenges, a different type of beam quality parameter in small beams was studied, namely the dose-area product ratio, or DAPR 20,10 . With this method, the measurement of a dose-area product (DAP) using a large-area plane-parallel chamber (LAC) eliminates the uncertainties in detector positioning and volume averaging that are present when using a point detector. In this study, the properties of the DAPR 20,10 of a cone-collimated 6 MV photon beam were investigated using Monte Carlo (MC) calculations and the obtained values were compared to measurements obtained using two LAC detectors, PTW Type 34073 and PTW Type 34070. In addition, the possibility of determining the DAP using EBT3 film and a Razor diode detector was studied. The determination of the DAPR 20,10 value was found to be feasible in external small-beam radiotherapy using cone-collimated beams with diameters from 4-40 mm, based on the results of the two LACs, the MC calculations and the Razor diode. The measurements indicated a constant DAPR 20,10 value for fields 20-40 mm in diameter, with a maximum relative change of 0.6%, but an increase of 7.0% for fields from 20-4 mm in diameter for the PTW Type 34070 chamber. Simulations and measurements showed an increase of DAPR 20,10 with increasing LAC size or dose integral area for the studied 4-40 mm cone-collimated 6 MV photon beams. This has the consequence that there should be a reference to the size of the used LAC active area or the DAP integration area with the reported DAPR 20,10 value.

Measurement and properties of the dose-area product ratio in external small-beam radiotherapy

Science.gov (United States)

Niemelä, Jarkko; Partanen, Mari; Ojala, Jarkko; Sipilä, Petri; Björkqvist, Mikko; Kapanen, Mika; Keyriläinen, Jani

2017-06-01

In small-beam radiation therapy (RT) the measurement of the beam quality parameter, i.e. the tissue-phantom ratio or TPR20,10, using a conventional point detector is a challenge. To obtain reliable results, one has to consider potential sources of error, including volume averaging and adjustment of the point detector into the narrow beam. To overcome these challenges, a different type of beam quality parameter in small beams was studied, namely the dose-area product ratio, or DAPR20,10. With this method, the measurement of a dose-area product (DAP) using a large-area plane-parallel chamber (LAC) eliminates the uncertainties in detector positioning and volume averaging that are present when using a point detector. In this study, the properties of the DAPR20,10 of a cone-collimated 6 MV photon beam were investigated using Monte Carlo (MC) calculations and the obtained values were compared to measurements obtained using two LAC detectors, PTW Type 34073 and PTW Type 34070. In addition, the possibility of determining the DAP using EBT3 film and a Razor diode detector was studied. The determination of the DAPR20,10 value was found to be feasible in external small-beam radiotherapy using cone-collimated beams with diameters from 4-40 mm, based on the results of the two LACs, the MC calculations and the Razor diode. The measurements indicated a constant DAPR20,10 value for fields 20-40 mm in diameter, with a maximum relative change of 0.6%, but an increase of 7.0% for fields from 20-4 mm in diameter for the PTW Type 34070 chamber. Simulations and measurements showed an increase of DAPR20,10 with increasing LAC size or dose integral area for the studied 4-40 mm cone-collimated 6 MV photon beams. This has the consequence that there should be a reference to the size of the used LAC active area or the DAP integration area with the reported DAPR20,10 value.

Simulation, Experimental and Analitical Study of Deflection at End Curved Beam Affected by Single Concentrated Load

Directory of Open Access Journals (Sweden)

Dewa Ngakan Ketut Putra Negara

2012-11-01

Full Text Available Deflection has an important role in order to design structure or machine component, beside consideration of stresscalculation. This is due to although stress is still smaller then stress allowed by material strength, but probably happen thatdeflection exceeds limit allowed. That condition affects serious hazard on machine elements or structure due to it can affectof component deviate from its main function. One of element which is often experience of deflection is beam. Beams playsignificant roles in many engineering applications, including buildings, bridges, automobiles, and airplane structures. In thisresearch, material to be used was Steel ASTM 1060, with specimen in the form of curved beam. Physical condition of beamwas modeled use of BEAM3 2D. Variation of loads to be applied were W = 100, 150, 200, 250, 300, 350, 400, 450, 500, and550 gr in vertical direction. The result of simulation was verificated by analytical and experimental data. Evaluation wascarried out by statistical test (t-test. The result of simulation is categorized to be good if the result of simulation is samewith analytical and experimental data. The result of research shows that loading has a significant effect on the deflection.The higher load affect the higher of deflection Modeling use of BEAM3 2D gave good result of deflection. This is showedfrom t-test have done, where the result of simulation was same with analytical and experimental data. Other advantage ofsimulation was deflection result obtained was not limited only at the end of beam, but it can predict of deflection at eachnode or point desired

A new external microbeam system in Fudan University

International Nuclear Information System (INIS)

Zheng, Y.; Shen, H.; Li, Y.Q.; Li, X.Y.; Yang, M.J.; Mi, Y.

2013-01-01

A cost-effective and removable external beam system is set up based on the Oxford Microbeam system in Fudan University. In our external beam system, 7.5-μm-thick Kapton film is used as exit window with a diameter of 3.5 mm. The spatial resolution is about 18 μm full width at half maximum (FWHM) on a copper grid. As an example, calcium distribution in otolith is present by the external micro-PIXE. In addition, little change can be done to the external system mentioned above for radiobiology experiments. The exit window can be changed from the focal plane to the observation window of vacuum chamber. By calculation, the beam spot size can reach less than 30 μm. Since the Oxford type octagonal target chamber is popular among the nuclear microprobe facilities, this method can be provided to easily replace the in-vacuum system with the external system, extending the in-vacuum analysis to external beam analysis

A new external microbeam system in Fudan University

Energy Technology Data Exchange (ETDEWEB)

Zheng, Y.; Shen, H., E-mail: haoshen@fudan.edu.cn; Li, Y.Q.; Li, X.Y.; Yang, M.J.; Mi, Y.

2013-07-01

A cost-effective and removable external beam system is set up based on the Oxford Microbeam system in Fudan University. In our external beam system, 7.5-μm-thick Kapton film is used as exit window with a diameter of 3.5 mm. The spatial resolution is about 18 μm full width at half maximum (FWHM) on a copper grid. As an example, calcium distribution in otolith is present by the external micro-PIXE. In addition, little change can be done to the external system mentioned above for radiobiology experiments. The exit window can be changed from the focal plane to the observation window of vacuum chamber. By calculation, the beam spot size can reach less than 30 μm. Since the Oxford type octagonal target chamber is popular among the nuclear microprobe facilities, this method can be provided to easily replace the in-vacuum system with the external system, extending the in-vacuum analysis to external beam analysis.

A new external microbeam system in Fudan University

Energy Technology Data Exchange (ETDEWEB)

Zheng, Y. [Applied Ion Beam Physics Laboratory, Institute of Modern Physics, Fudan University, Shanghai 200433 (China); Shen, H., E-mail: haoshen@fudan.edu.cn [Applied Ion Beam Physics Laboratory, Institute of Modern Physics, Fudan University, Shanghai 200433 (China); Li, Y.Q.; Li, X.Y.; Yang, M.J.; Mi, Y. [Applied Ion Beam Physics Laboratory, Institute of Modern Physics, Fudan University, Shanghai 200433 (China)

2013-02-01

A cost-effective and removable external beam system is set up based on the Oxford Microbeam system in Fudan University. In our external beam system, 7.5-μm-thick Kapton film is used as exit window with a diameter of 3.5 mm. The spatial resolution is about 18 μm full width at half maximum (FWHM) on a copper grid. As an example, calcium distribution in otolith is present by the external micro-PIXE. In addition, little change can be done to the external system mentioned above for radiobiology experiments. The exit window can be changed from the focal plane to the observation window of vacuum chamber. By calculation, the beam spot size can reach less than 30 μm. Since the Oxford type octagonal target chamber is popular among the nuclear microprobe facilities, this method can be provided to easily replace the in-vacuum system with the external system, extending the in-vacuum analysis to external beam analysis.

In vivo dosimetry in external beam radiotherapy

International Nuclear Information System (INIS)

Mijnheer, Ben; Beddar, Sam; Izewska, Joanna; Reft, Chester

2013-01-01

In vivo dosimetry (IVD) is in use in external beam radiotherapy (EBRT) to detect major errors, to assess clinically relevant differences between planned and delivered dose, to record dose received by individual patients, and to fulfill legal requirements. After discussing briefly the main characteristics of the most commonly applied IVD systems, the clinical experience of IVD during EBRT will be summarized. Advancement of the traditional aspects of in vivo dosimetry as well as the development of currently available and newly emerging noninterventional technologies are required for large-scale implementation of IVD in EBRT. These new technologies include the development of electronic portal imaging devices for 2D and 3D patient dosimetry during advanced treatment techniques, such as IMRT and VMAT, and the use of IVD in proton and ion radiotherapy by measuring the decay of radiation-induced radionuclides. In the final analysis, we will show in this Vision 20/20 paper that in addition to regulatory compliance and reimbursement issues, the rationale for in vivo measurements is to provide an accurate and independent verification of the overall treatment procedure. It will enable the identification of potential errors in dose calculation, data transfer, dose delivery, patient setup, and changes in patient anatomy. It is the authors’ opinion that all treatments with curative intent should be verified through in vivo dose measurements in combination with pretreatment checks

External Beam Radiation in Differentiated Thyroid Carcinoma

Directory of Open Access Journals (Sweden)

Salem Billan

2016-01-01

Full Text Available The treatment of differentiated thyroid carcinoma (DTC is surgery followed in some cases by adjuvant treatment, mostly with radioactive iodine (RAI. External beam radiotherapy (EBRT is less common and not a well-established treatment modality in DTC. The risk of recurrence depends on three major prognostic factors: extra-thyroid extension, patient’s age, and tumor with reduced iodine uptake. Increased risk for recurrence is a major factor in the decision whether to treat the patient with EBRT. Data about the use of EBRT in DTC are limited to small retrospective studies. Most series have demonstrated an increase in loco-regional control. The risk/benefit from giving EBRT requires careful patient selection. Different scoring systems have been proposed by different investigators and centers. The authors encourage clinicians treating DTC to become familiarized with those scoring systems and to use them in the management of different cases. The irradiated volume should include areas of risk for microscopic disease. Determining those areas in each case can be difficult and requires detailed knowledge of the surgery and pathological results, and also understanding of the disease-spreading pattern. Treatment with EBRT in DTC can be beneficial, and data support the use of EBRT in high-risk patients. Randomized controlled trials are needed for better confirmation of the role of EBRT.

In vivo dosimetry in external beam radiotherapy

Energy Technology Data Exchange (ETDEWEB)

Mijnheer, Ben [Department of Radiation Oncology, Netherlands Cancer Institute-Antoni van Leeuwenhoek Hospital, Amsterdam 1066 CX (Netherlands); Beddar, Sam [Department of Radiation Physics, University of Texas MD Anderson Cancer Center, Houston, Texas 77030 (United States); Izewska, Joanna [Division of Human Health, International Atomic Energy Agency, Vienna 1400 (Austria); Reft, Chester [Department of Radiation and Cellular Oncology, University of Chicago Medical Center, Chicago, Illinois 60637 (United States)

2013-07-15

In vivo dosimetry (IVD) is in use in external beam radiotherapy (EBRT) to detect major errors, to assess clinically relevant differences between planned and delivered dose, to record dose received by individual patients, and to fulfill legal requirements. After discussing briefly the main characteristics of the most commonly applied IVD systems, the clinical experience of IVD during EBRT will be summarized. Advancement of the traditional aspects of in vivo dosimetry as well as the development of currently available and newly emerging noninterventional technologies are required for large-scale implementation of IVD in EBRT. These new technologies include the development of electronic portal imaging devices for 2D and 3D patient dosimetry during advanced treatment techniques, such as IMRT and VMAT, and the use of IVD in proton and ion radiotherapy by measuring the decay of radiation-induced radionuclides. In the final analysis, we will show in this Vision 20/20 paper that in addition to regulatory compliance and reimbursement issues, the rationale for in vivo measurements is to provide an accurate and independent verification of the overall treatment procedure. It will enable the identification of potential errors in dose calculation, data transfer, dose delivery, patient setup, and changes in patient anatomy. It is the authors' opinion that all treatments with curative intent should be verified through in vivo dose measurements in combination with pretreatment checks.

Coupled PIXE and RBS using a 6MeV 4He2+ external beam: A new experimental device for particle detection and dose monitoring

International Nuclear Information System (INIS)

Mathis, F.; Moignard, B.; Pichon, L.; Dubreuil, O.; Salomon, J.

2005-01-01

AGLAE (Accelerateur Grand Louvre d'Analyses Elementaire), the IBA facility of the 'Centre de Recherche et de Restauration des Musees de France' (C2RMF) has been equipped for several years with an external micro-beam line, in order to perform ion beam analysis on materials relevant to cultural heritage. This beam line is undergoing constant improvement. Recently, a new extraction nozzle for the external beam of the accelerator has been designed in order to obtain simultaneously from the same spot: - detection of the X-ray emission by two detectors, for low and high energies; - detection of the backscattered particles for a backscattering angle between 170 and 175 deg., thanks to an annular surface barrier detector included in the nozzle; - particle current monitoring by intermittent beam deflection on a reference material included in the system. This technical development has been induced by the study of artificial patinas on archaeological copper-alloy objects and the attempt to characterize them with a 6MeV 4 He 2+ beam, an unusual beam for this type of investigation. A detailed description of the new device and some results on an application of the use of high-energy alpha beam in PIXE and RBS made on a Roman strigil are presented here

Nonlinear dynamics and chaotization of oscillations of a virtual cathode in an annular electron beam in a uniform external magnetic field

International Nuclear Information System (INIS)

Kurkin, S. A.; Koronovski, A. A.; Hramov, A. E.

2009-01-01

Results are presented from a numerical study of the effect of an external magnetic field on the conditions and mechanisms for the formation of a virtual cathode in a relativistic electron beam. Characteristic features of the nonlinear dynamics of an electron beam with a virtual cathode are considered when the external magnetic field is varied. Various mechanisms are investigated by which the virtual cathode oscillations become chaotic and their spectrum becomes a multifrequency spectrum, thereby complicating the dynamics of the vircator system. A general mechanism for chaotization of the oscillations of a virtual cathode in a vircator system is revealed: the electron structures that form in an electron beam interact by means of a common space charge field to give rise to additional internal feedback. That the oscillations of a virtual cathode change from the chaotic to the periodic regime is due to the suppression of the mechanism for forming secondary electron structures.

External beam radiation therapy for squamous cell carcinoma of the soft palate

International Nuclear Information System (INIS)

Medini, Eitan; Medini, Allen; Gapany, Markus; Levitt, Seymour H.

1997-01-01

Purpose: External beam radiation therapy for carcinoma of the soft palate aims to achieve loco-regional control with normal speech, nasal function, swallowing mechanism, and minimal side effects such as nasal speech and regurgitation of food into the nasopharynx. In this report we present our results of radiotherapy in the treatment of 24 patients with squamous cell carcinoma of the soft palate. Methods and Materials: A total of 24 patients with squamous cell carcinoma of the soft palate were treated at the Veterans Administration Medical Center Minneapolis, MN, between February 1977 and May 1992. Of the 24 patients 2 had T1, 19 T2, 1 T3, and 2 had T4 lesions. Nineteen patients did not have clinical nodal disease, stage (N0), 1 had N1, 2 N2, and 2 N3 disease (Table 1). All the patients were treated by 4 MeV linear accelerator. A 1.75 Gy median dose was administered per fraction to a total of 70 Gy median dose. Bilateral opposed compensated shrinking fields technique was used. Results: The 3-year disease free survival rate after external beam radiation therapy was 100% (1 out of 1), 64.7% (11 out of 17), 100% (1 out of 1), and 0%, for patients with T1, T2, T3, and T4 disease, respectively. Salvage surgery for recurrent disease was successful in 57.1% (4 out of 7 patients). The ultimate 3-year disease free survival rate for the entire group, including surgical salvage, was 81% (17 out of 21). Conclusion: Radiation therapy alone in our institution resulted in tumor control and survival rates compare favorably to previously published reports in the literature. Surgery can be reserved as salvage procedure

Treatment of Head and Neck Paragangliomas With External Beam Radiation Therapy

Energy Technology Data Exchange (ETDEWEB)

Dupin, Charles, E-mail: c.dupin@bordeaux.unicancer.fr [Department of Radiotherapy, Comprehensive Cancer Center, Institut Bergonié, Bordeaux (France); Lang, Philippe [Department of Radiotherapy, Pitié Salpétrière, Paris (France); Dessard-Diana, Bernadette [Department of Radiotherapy, Hopital Européen Georges Pompidou, Paris (France); Simon, Jean-Marc; Cuenca, Xavier; Mazeron, Jean-Jacques; Feuvret, Loïc [Department of Radiotherapy, Pitié Salpétrière, Paris (France)

2014-06-01

Purpose: To retrospectively assess the outcomes of radiation therapy in patients with head and neck paragangliomas. Methods and Materials: From 1990 to 2009, 66 patients with 81 head and neck paragangliomas were treated by conventional external beam radiation therapy in 25 fractions at a median dose of 45 Gy (range, 41.4-68 Gy). One case was malignant. The median gross target volume and planning target volume were 30 cm{sup 3} (range, 0.9-243 cm{sup 3}) and 116 cm{sup 3} (range, 24-731 cm{sup 3}), respectively. Median age was 57.4 years (range, 15-84 years). Eleven patients had multicentric lesions, and 8 had family histories of paraganglioma. Paragangliomas were located in the temporal bone, the carotid body, and the glomus vagal in 51, 18, and 10 patients, respectively. Forty-six patients had exclusive radiation therapy, and 20 had salvage radiation therapy. The median follow-up was 4.1 years (range, 0.1-21.2 years). Results: One patient had a recurrence of temporal bone paraganglioma 8 years after treatment. The actuarial local control rates were 100% at 5 years and 98.7% at 10 years. Patients with multifocal tumors and family histories were significantly younger (42 years vs 58 years [P=.002] and 37 years vs 58 years [P=.0003], respectively). The association between family predisposition and multifocality was significant (P<.001). Two patients had cause-specific death within the 6 months after irradiation. During radiation therapy, 9 patients required hospitalization for weight loss, nausea, mucositis, or ophthalmic zoster. Two late vascular complications occurred (middle cerebral artery and carotid stenosis), and 2 late radiation-related meningiomas appeared 15 and 18 years after treatment. Conclusion: Conventional external beam radiation therapy is an effective and safe treatment option that achieves excellent local control; it should be considered as a first-line treatment of choice for head and neck paragangliomas.

Respiratory gated beam delivery cannot facilitate margin reduction, unless combined with respiratory correlated image guidance

International Nuclear Information System (INIS)

Korreman, Stine S.; Juhler-Nottrup, Trine; Boyer, Arthur L.

2008-01-01

Purpose/objective: In radiotherapy of targets moving with respiration, beam gating is offered as a means of reducing the target motion. The purpose of this study is to evaluate the safe magnitude of margin reduction for respiratory gated beam delivery. Materials/methods: The study is based on data for 17 lung cancer patients in separate protocols at Rigshospitalet and Stanford Cancer Center. Respiratory curves for external optical markers and implanted fiducials were collected using equipment based on the RPM system (Varian Medical Systems). A total of 861 respiratory curves represented external measurements over 30 fraction treatment courses for 10 patients, and synchronous external/internal measurements in single sessions for seven patients. Variations in respiratory amplitude (simulated coaching) and external/internal phase shifts were simulated by perturbation with realistic values. Variations were described by medians and standard deviations (SDs) of position distributions of the markers. Gating windows (35% duty cycle) were retrospectively applied to the respiratory data for each session, mimicking the use of commercially available gating systems. Medians and SDs of gated data were compared to those of ungated data, to assess potential margin reductions. Results: External respiratory data collected over entire treatment courses showed SDs from 1.6 to 8.1 mm, the major part arising from baseline variations. The gated data had SDs from 1.5 to 7.7 mm, with a mean reduction of 0.3 mm (6%). Gated distributions were more skewed than ungated, and in a few cases a marginal miss of gated respiration would be found even if no margin reduction was applied. Regularization of breathing amplitude to simulate coaching did not alter these results significantly. Simulation of varying phase shifts between internal and external respiratory signals showed that the SDs of gated distributions were the same as for the ungated or smaller, but the median values were markedly shifted

Ocular complications after external-beam irradiation - a literature overview

International Nuclear Information System (INIS)

Ziolkowska, E.; Zarzycka, M.; Wisniewski, T.; Meller, A.

2009-01-01

Radiotherapy is one of the treatment methods applied to patients suffering from head and neck cancer. The efficiency of this method is comparable to surgery, yet it allows one to save the organ and avoid its permanent deformation. In the case of radiation not only the tumour is influenced but the surrounding, normal structures as well. Radiation causes deformation of normal structures as early or side effects. The aim of this study is to present plausible ocular complications after external beam irradiation of head and neck cancer, such as radiation- induced cataract, radiation retinopathy, dry-eye syndrome or radiation neuropathy. By the use of basic principles of radiotherapy planning we can avoid or minimize possible ocular complications occurring after irradiation. The treatment of ocular complications is difficult and very often does not give the expected outcome. Therefore, in such cases in order to restore vision surgery is required. This study shows that radiotherapy can be helpful but can increase the risk of occurrence of some ocular complications. (authors)

Computational tools for the construction of calibration curves for use in dose calculations in radiotherapy treatment planning

International Nuclear Information System (INIS)

Oliveira, Alex C.H.; Vieira, Jose W.; Escola Politecnica de Pernambuco , Recife, PE

2011-01-01

The realization of tissue inhomogeneity corrections in image-based treatment planning improves the accuracy of radiation dose calculations for patients undergoing external-beam radiotherapy. Before the tissue inhomogeneity correction can be applied, the relationship between the computed tomography (CT) numbers and density must be established. This relationship is typically established by a calibration curve empirically obtained from CT images of a phantom that has several inserts of tissue-equivalent materials, covering a wide range of densities. This calibration curve is scanner-dependent and allows the conversion of CT numbers in densities for use in dose calculations. This paper describes the implementation of computational tools necessary to construct calibration curves. These tools are used for reading and displaying of CT images in DICOM format, determination of the mean CT numbers (and their standard deviations) of each tissue-equivalent material and construction of calibration curves by fits with bilinear equations. All these tools have been implemented in the Microsoft Visual Studio 2010 in C≠ programming language. (author)

Phase I study of twice-weekly gemcitabine and concomitant external-beam radiotherapy in patients with adenocarcinoma of the pancreas

International Nuclear Information System (INIS)

Pipas, J. Marc; Mitchell, Sandra E.; Barth, Richard J.; Vera-Gimon, Raul; Rathmann, Joerg; Meyer, Louise P.; Wagman, Richard S.; Lewis, Lionel D.; McDonnell, Carol; Colacchio, Thomas A.; Perez, Raymond P.

2001-01-01

Purpose: To determine the maximum tolerated dose and dose-limiting toxicity associated with twice-weekly gemcitabine and concomitant external-beam radiotherapy in patients with adenocarcinoma of the pancreas. Methods and Materials: Twenty-one patients with biopsy-proven adenocarcinoma of the pancreas were treated with external-beam radiotherapy to a dose of 50.4 Gy in 28 fractions, concurrent with gemcitabine, infused over 30 min before irradiation on a Monday and Thursday schedule. The dose of gemcitabine was escalated in 5 cohorts of 3-6 patients each. Initial gemcitabine dose was 10 mg/m 2 , with dose escalation until dose-limiting toxicity was observed. Results: The maximum tolerated dose of gemcitabine was 50 mg/m 2 , when given in a twice-weekly schedule with radiation. Dose-limiting toxicity was seen in 2 patients at 60 mg/m 2 , and consisted of severe upper gastrointestinal bleeding approximately 1 month after completion of treatment. Six patients had radiographic evidence of response to treatment, and 5 of these underwent complete surgical resection. Three patients who underwent complete resection had been deemed to have unresectable tumors before enrollment on trial. Four patients are alive, including 2 without evidence of disease more than 1 year after resection. Conclusion: The combination of external-beam radiation and twice-weekly gemcitabine at a dose of 50 mg/m 2 is well tolerated and shows promising activity for the treatment of pancreatic cancer. Our data suggest a higher maximum tolerated dose and different dose-limiting toxicity than previously reported. Further investigation of this regimen is warranted

Experimental study of the molecular beam destruction by beam-beam and beam-background scattering

International Nuclear Information System (INIS)

Bossel, U.; Dettleff, G.

1974-01-01

The extraction of flow properties related to the molecular motion normal to stream lines of an expanding gas jet from observed intensity profiles of supersonic beams is critically assessed. The perturbation of the profile curves by various effects is studied for a helium beam. Exponential laws appear to describe scattering effects to a satisfactory degree

ACR Appropriateness Criteria for external beam radiation therapy treatment planning for clinically localized prostate cancer, part II of II

Directory of Open Access Journals (Sweden)

Nicholas G. Zaorsky, MD

2017-07-01

Conclusions: External beam radiation is a key component of the curative management of T1 and T2 prostate cancer. By combining the most recent medical literature, these Appropriateness Criteria can aid clinicians in determining the appropriate treatment delivery and personalized approaches for individual patients.

Metasurface external cavity laser

Energy Technology Data Exchange (ETDEWEB)

Xu, Luyao, E-mail: luyaoxu.ee@ucla.edu; Curwen, Christopher A.; Williams, Benjamin S. [Department of Electrical Engineering, University of California, Los Angeles, California 90095 (United States); California NanoSystems Institute, University of California, Los Angeles, California 90095 (United States); Hon, Philip W. C.; Itoh, Tatsuo [Department of Electrical Engineering, University of California, Los Angeles, California 90095 (United States); Chen, Qi-Sheng [Northrop Grumman Aerospace Systems, Redondo Beach, California 90278 (United States)

2015-11-30

A vertical-external-cavity surface-emitting-laser is demonstrated in the terahertz range, which is based upon an amplifying metasurface reflector composed of a sub-wavelength array of antenna-coupled quantum-cascade sub-cavities. Lasing is possible when the metasurface reflector is placed into a low-loss external cavity such that the external cavity—not the sub-cavities—determines the beam properties. A near-Gaussian beam of 4.3° × 5.1° divergence is observed and an output power level >5 mW is achieved. The polarized response of the metasurface allows the use of a wire-grid polarizer as an output coupler that is continuously tunable.

Cone-beam computed tomography analysis of curved root canals after mechanical preparation with three nickel-titanium rotary instruments

Science.gov (United States)

Elsherief, Samia M.; Zayet, Mohamed K.; Hamouda, Ibrahim M.

2013-01-01

Cone beam computed tomography is a 3-dimensional high resolution imaging method. The purpose of this study was to compare the effects of 3 different NiTi rotary instruments used to prepare curved root canals on the final shape of the curved canals and total amount of root canal transportation by using cone-beam computed tomography. A total of 81 mesial root canals from 42 extracted human mandibular molars, with a curvature ranging from 15 to 45 degrees, were selected. Canals were randomly divided into 3 groups of 27 each. After preparation with Protaper, Revo-S and Hero Shaper, the amount of transportation and centering ability that occurred were assessed by using cone beam computed tomography. Utilizing pre- and post-instrumentation radiographs, straightening of the canal curvatures was determined with a computer image analysis program. Canals were metrically assessed for changes (surface area, changes in curvature and transportation) during canal preparation by using software SimPlant; instrument failures were also recorded. Mean total widths and outer and inner width measurements were determined on each central canal path and differences were statistically analyzed. The results showed that all instruments maintained the original canal curvature well with no significant differences between the different files (P = 0.226). During preparation there was failure of only one file (the protaper group). In conclusion, under the conditions of this study, all instruments maintained the original canal curvature well and were safe to use. Areas of uninstrumented root canal wall were left in all regions using the various systems. PMID:23885273

Analysis of the variation of the attenuation curve in function of the radiation field size for k Vp X-ray beams using the MCNP-5C code

Energy Technology Data Exchange (ETDEWEB)

Fernandes, Marco A.R., E-mail: marco@cetea.com.b, E-mail: marfernandes@fmb.unesp.b [Universidade Estadual Paulista Julio de Mesquita Filho (FMB/UNESP), Botucatu, SP (Brazil). Fac. de Medicina; Ribeiro, Victor A.B. [Universidade Estadual Paulista Julio de Mesquita Filho (IBB/UNESP), Botucatu, SP (Brazil). Inst. de Biociencias; Viana, Rodrigo S.S.; Coelho, Talita S. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

2011-07-01

The paper illustrates the use of the Monte Carlo method, MCNP-5C code, to analyze the attenuation curve behavior of the 50 kVp radiation beam from superficial radiotherapy equipment as Dermopan2 model. The simulations seek to verify the MCNP-5C code performance to study the variation of the attenuation curve - percentage depth dose (PDD) curve - in function of the radiation field dimension used at radiotherapy of skin tumors with 50 kVp X-ray beams. The PDD curve was calculated for six different radiation field sizes with circular geometry of 1.0, 2.0, 3.0, 4.0, 5.0 and 6.0 cm in diameter. The radiation source was modeled considering a tungsten target with inclination 30 deg, focal point of 6.5 mm in diameter and energy beam of 50 kVp; the X-ray spectrum was calculated with the MCNP-5C code adopting total filtration (beryllium window of 1 mm and aluminum additional filter of 1 mm). The PDD showed decreasing behavior with the attenuation depth similar what is presented on the literature. There was not significant variation at the PDD values for the radiation field between 1.0 and 4.0 cm in diameter. The differences increased for fields of 5.0 and 6.0 cm and at attenuation depth higher than 1.0 cm. When it is compared the PDD values for fields of 3.0 and 6.0 cm in diameter, it verifies the greater difference (12.6 %) at depth of 5.7 cm, proving the scattered radiation effect. The MCNP-5C code showed as an appropriate procedure to analyze the attenuation curves of the superficial radiotherapy beams. (author)

A comparison in cosmetic outcome between per-operative interstitial breast implants and delayed interstitial breast implants after external beam radiotherapy

NARCIS (Netherlands)

Pieters, Bradley R.; Hart, Augustinus A. M.; Russell, Nicola S.; Jansen, Edwin P. M.; Peterse, Johannes L.; Borger, Jacques; Rutgers, Emiel J. Th

2003-01-01

Background and purpose: Interstitial implants for brachytherapy boost in the breast conserving therapy of breast cancer can be performed in two ways; implants during the tumor excision (per-operative implants) or after the external beam therapy (delayed interstitial implants). Differences in

Comprehensive MRI simulation methodology using a dedicated MRI scanner in radiation oncology for external beam radiation treatment planning

International Nuclear Information System (INIS)

Paulson, Eric S.; Erickson, Beth; Schultz, Chris; Allen Li, X.

2015-01-01

Purpose: The use of magnetic resonance imaging (MRI) in radiation oncology is expanding rapidly, and more clinics are integrating MRI into their radiation therapy workflows. However, radiation therapy presents a new set of challenges and places additional constraints on MRI compared to diagnostic radiology that, if not properly addressed, can undermine the advantages MRI offers for radiation treatment planning (RTP). The authors introduce here strategies to manage several challenges of using MRI for virtual simulation in external beam RTP. Methods: A total of 810 clinical MRI simulation exams were performed using a dedicated MRI scanner for external beam RTP of brain, breast, cervix, head and neck, liver, pancreas, prostate, and sarcoma cancers. Patients were imaged in treatment position using MRI-optimal immobilization devices. Radiofrequency (RF) coil configurations and scan protocols were optimized based on RTP constraints. Off-resonance and gradient nonlinearity-induced geometric distortions were minimized or corrected prior to using images for RTP. A multidisciplinary MRI simulation guide, along with window width and level presets, was created to standardize use of MR images during RTP. A quality assurance program was implemented to maintain accuracy and repeatability of MRI simulation exams. Results: The combination of a large bore scanner, high field strength, and circumferentially wrapped, flexible phased array RF receive coils permitted acquisition of thin slice images with high contrast-to-noise ratio (CNR) and image intensity uniformity, while simultaneously accommodating patient setup and immobilization devices. Postprocessing corrections and alternative acquisition methods were required to reduce or correct off-resonance and gradient nonlinearity induced geometric distortions. Conclusions: The methodology described herein contains practical strategies the authors have implemented through lessons learned performing clinical MRI simulation exams. In

Comprehensive MRI simulation methodology using a dedicated MRI scanner in radiation oncology for external beam radiation treatment planning

Energy Technology Data Exchange (ETDEWEB)

Paulson, Eric S., E-mail: epaulson@mcw.edu [Department of Radiation Oncology, Medical College of Wisconsin, Milwaukee, Wisconsin 53226 and Department of Radiology, Medical College of Wisconsin, Milwaukee, Wisconsin 53226 (United States); Erickson, Beth; Schultz, Chris; Allen Li, X. [Department of Radiation Oncology, Medical College of Wisconsin, Milwaukee, Wisconsin 53226 (United States)

2015-01-15

Purpose: The use of magnetic resonance imaging (MRI) in radiation oncology is expanding rapidly, and more clinics are integrating MRI into their radiation therapy workflows. However, radiation therapy presents a new set of challenges and places additional constraints on MRI compared to diagnostic radiology that, if not properly addressed, can undermine the advantages MRI offers for radiation treatment planning (RTP). The authors introduce here strategies to manage several challenges of using MRI for virtual simulation in external beam RTP. Methods: A total of 810 clinical MRI simulation exams were performed using a dedicated MRI scanner for external beam RTP of brain, breast, cervix, head and neck, liver, pancreas, prostate, and sarcoma cancers. Patients were imaged in treatment position using MRI-optimal immobilization devices. Radiofrequency (RF) coil configurations and scan protocols were optimized based on RTP constraints. Off-resonance and gradient nonlinearity-induced geometric distortions were minimized or corrected prior to using images for RTP. A multidisciplinary MRI simulation guide, along with window width and level presets, was created to standardize use of MR images during RTP. A quality assurance program was implemented to maintain accuracy and repeatability of MRI simulation exams. Results: The combination of a large bore scanner, high field strength, and circumferentially wrapped, flexible phased array RF receive coils permitted acquisition of thin slice images with high contrast-to-noise ratio (CNR) and image intensity uniformity, while simultaneously accommodating patient setup and immobilization devices. Postprocessing corrections and alternative acquisition methods were required to reduce or correct off-resonance and gradient nonlinearity induced geometric distortions. Conclusions: The methodology described herein contains practical strategies the authors have implemented through lessons learned performing clinical MRI simulation exams. In

Analyses of inks and papers in historical documents through external beam PIXE techniques

International Nuclear Information System (INIS)

Cahill, T.A.; Kusko, B.; California Univ., Davis; Schwab, R.N.

1981-01-01

PIXE analyses of documents can be carried out to high senstitivty in an external beam configuration designed to protect historical materials from damage. Test runs have shown that a properbly designed system with high solid angle can operate at less than 1% of the flux necessary to cause any discoloration whatsoever on papers of the 17th and 18th centuries. The composition of these papers is suprisingly complex, yet retains distinct association with the historical period, paper source, and even the individual sheets of paper that are folded and cut to make groups of pages. Early studies are planned on historical forgeries. (orig.)

Neoadjuvant hormonal therapy and external-beam radiotherapy versus external-beam irradiation alone for prostate cancer. A quality-of-life analysis

Energy Technology Data Exchange (ETDEWEB)

Pinkawa, Michael; Piroth, Marc D.; Asadpour, Branka; Gagel, Bernd; Fischedick, Karin; Siluschek, Jaroslav; Kehl, Mareike; Krenkel, Barbara; Eble, Michael J. [RWTH Aachen (Germany). Dept. of Radiotherapy

2009-02-15

To evaluate the impact of neoadjuvant hormonal therapy (NHT) on quality of life after external-beam radiotherapy (EBRT) for prostate cancer. A group of 170 patients (85 with and 85 without NHT) has been surveyed prospectively before EBRT (70.2-72 Gy), at the last day of EBRT, a median time of 2 months and 15 months after EBRT using a validated questionnaire (Expanded Prostate Cancer Index Composite). Pairs with and without NHT (median treatment time of 3.5 months before EBRT) were matched according to the respective planning target volume and prostate volume. Before EBRT, significantly lower urinary function/bother, sexual function and hormonal function/bother scores were found for patients with NHT. More than 1 year after EBRT, only sexual function scores remained lower. In a multivariate analysis, NHT and adjuvant hormonal therapy (HT) versus NHT only (hazard ratio 14; 95% confidence interval 2.7-183; p = 0.02) and luteinizing hormone-releasing hormone (LHRH) agonists versus antiandrogens (hazard ratio 3.6; 95% confidence interval 1.1-12; p = 0.04) proved to be independent risk factors for long-term erectile dysfunction (no or very poor ability to have an erection). With the exception of sexual function (additional adjuvant HT and application of LHRH analog independently adverse), short-term NHT was not found to decrease quality of life after EBRT for prostate cancer. (orig.)

External beam irradiation inhibits neointimal hyperplasia after injury-induced arterial smooth muscle cell proliferation

International Nuclear Information System (INIS)

Schaefer, U.; Micke, O.; Dorszewski, A.; Breithardt, G.; Willich, N.

1996-01-01

Purpose/Objective: Restenosis after catheter-based revascularization has been demonstrated to be primarily caused by smooth muscle cell proliferation. This study examines the effects of external beam irradiation on neointimal proliferation after external injury to the central artery of the rabbit ear. Materials and Methods: 30 male New Zealand White rabbits were used in this study. Crush lesions were performed on each ear under general anesthesia and bilateral auricular nerve blockade. A single dose of 12 Gy (n=10), 16 Gy (n=10), or 20 Gy (n=10) gamma radiation was delivered to the left or right central artery of the ear 24 hours after injury; the contralateral central artery served as control. All rabbits were sacrificed after twenty-one days and the central arteries of the ear were fixed for morphometric measurements. Results: Mean (± SD) neointimal area was 0.062 ± 0.005 mm 2 (12 Gy), 0.022 ± 0.005 mm 2 (16 Gy) and 0.028 ± 0.006 mm 2 in irradiated arteries compared with 0.081 ± 0.009 mm 2 in the control group. Mean (± SD) luminal area was 0.049 ± 0.004 mm 2 (12 Gy), 0.059 ± 0.002 mm 2 (16 Gy) and 0.072 ± 0.006 mm 2 (24 Gy) in irradiated arteries compared with 0.043 ± 0.008 mm 2 in the control group. The difference in neointimal and luminal area between control and irradiated arteries was significant (p<0.05) only for the 16 and 20 Gy group compared to control. Conclusion: We conclude that in this model, external beam X-ray irradiation was successful in reducing neointimal proliferation after injury of the central artery of the rabbit ear. Marked reductions in neointimal proliferation were demonstrated in vessels subjected to 16 and 20 Gy radiation, a less prominent effect was noted for 12 Gy. Whether this approach can be used successfully to inhibit restenosis in the clinical setting requires further investigation

Stress analysis in curved composites due to thermal loading

Science.gov (United States)

Polk, Jared Cornelius

Many structures in aircraft, cars, trucks, ships, machines, tools, bridges, and buildings, consist of curved sections. These sections vary from straight line segments that have curvature at either one or both ends, segments with compound curvatures, segments with two mutually perpendicular curvatures or Gaussian curvatures, and segments with a simple curvature. With the advancements made in multi-purpose composites over the past 60 years, composites slowly but steadily have been appearing in these various vehicles, compound structures, and buildings. These composite sections provide added benefits over isotropic, polymeric, and ceramic materials by generally having a higher specific strength, higher specific stiffnesses, longer fatigue life, lower density, possibilities in reduction of life cycle and/or acquisition cost, and greater adaptability to intended function of structure via material composition and geometry. To be able to design and manufacture a safe composite laminate or structure, it is imperative that the stress distributions, their causes, and effects are thoroughly understood in order to successfully accomplish mission objectives and manufacture a safe and reliable composite. The objective of the thesis work is to expand upon the knowledge of simply curved composite structures by exploring and ascertaining all pertinent parameters, phenomenon, and trends in stress variations in curved laminates due to thermal loading. The simply curved composites consist of composites with one radius of curvature throughout the span of the specimen about only one axis. Analytical beam theory, classical lamination theory, and finite element analysis were used to ascertain stress variations in a flat, isotropic beam. An analytical method was developed to ascertain the stress variations in an isotropic, simply curved beam under thermal loading that is under both free-free and fixed-fixed constraint conditions. This is the first such solution to Author's best knowledge

Chaotic dynamics of flexible beams driven by external white noise

Science.gov (United States)

Awrejcewicz, J.; Krysko, A. V.; Papkova, I. V.; Zakharov, V. M.; Erofeev, N. P.; Krylova, E. Yu.; Mrozowski, J.; Krysko, V. A.

2016-10-01

Mathematical models of continuous structural members (beams, plates and shells) subjected to an external additive white noise are studied. The structural members are considered as systems with infinite number of degrees of freedom. We show that in mechanical structural systems external noise can not only lead to quantitative changes in the system dynamics (that is obvious), but also cause the qualitative, and sometimes surprising changes in the vibration regimes. Furthermore, we show that scenarios of the transition from regular to chaotic regimes quantified by Fast Fourier Transform (FFT) can lead to erroneous conclusions, and a support of the wavelet analysis is needed. We have detected and illustrated the modifications of classical three scenarios of transition from regular vibrations to deterministic chaos. The carried out numerical experiment shows that the white noise lowers the threshold for transition into spatio-temporal chaotic dynamics. A transition into chaos via the proposed modified scenarios developed in this work is sensitive to small noise and significantly reduces occurrence of periodic vibrations. Increase of noise intensity yields decrease of the duration of the laminar signal range, i.e., time between two successive turbulent bursts decreases. Scenario of transition into chaos of the studied mechanical structures essentially depends on the control parameters, and it can be different in different zones of the constructed charts (control parameter planes). Furthermore, we found an interesting phenomenon, when increase of the noise intensity yields surprisingly the vibrational characteristics with a lack of noisy effect (chaos is destroyed by noise and windows of periodicity appear).

A new mapping acquisition and processing system for simultaneous PIXE-RBS analysis with external beam

International Nuclear Information System (INIS)

Pichon, L.; Beck, L.; Walter, Ph.; Moignard, B.; Guillou, T.

2010-01-01

The combination of ion beam analysis techniques is particularly fruitful for the study of cultural heritage objects. For several years, the AGLAE facility of the Louvre laboratory has been implementing these techniques with an external beam. The recent set-up permits to carry out PIXE, PIGE and RBS simultaneously on the same analyzed spot with a particle beam of approximately 20 μm diameter. A new mapping system has been developed in order to provide elemental concentration maps from the PIXE and RBS spectra. This system combines the Genie2000 spectroscopy software with a homemade software that creates maps by handling acquisition with the object position. Each pixel of each PIXE and RBS maps contains the spectrum normalised by the dose. After analysing each pixel of the PIXE maps (low and high energy X-ray spectra) with the Gupixwin peak-fitting software, quantitative elemental concentrations are obtained for the major and trace elements. This paper presents the quantitative elemental maps extracted from the PIXE spectra and the development of RBS data processing for light element distribution and thin layer characterization. Examples on rock painting and lustrous ceramics will be presented.

Multicenter study differentiated thyroid carcinoma (MSDS). Diminished acceptance of adjuvant external beam radiotherapy

International Nuclear Information System (INIS)

Biermann, M.; Pixberg, M.K.; Schober, O.; Schuck, A.; Willich, N.; Heinecke, A.; Koepke, W.; Schmid, K.W.; Dralle, H.

2003-01-01

Aim: The Multicenter Study Differentiated Thyroid Carcinoma (MSDS) is an ongoing study in Germany, Austria, and Switzerland on the clinical benefit of adjuvant external beam radiotherapy (RTx) for locally invasive differentiated thyroid carcinoma (DTC) in TNM stages pT4 pNO/1/xMO/x (5th ed. 1997). Methods: MSDS was designed as a prospective randomized trial. Patients receive thyroidectomy, radioiodine therapy (RIT) to ablate the thyroid remnant, and TSH-suppressive L-thyroxine therapy with or without RTx after documented elimination of cervical iodine-131 uptake (http://msds-studie.uni-muenster.de). Results: 311 patients were enrolled between January 2000 and March 2003. 279 patients met the trial's inclusion criteria. 45 consented to randomization, of whom 17 were randomized into treatment arm A (RTx) and 18 into arm B (no RTx). Advised by the trial's independent Data Monitoring and Safety Committee, the MSDS steering committee decided to terminate randomization in April 2003 and continue MSDS as a prospective cohort study. 23 of the 234 patients in the observation arm of the trial were prescribed RTx by their physicians. Thus, 14% of the trial cohort were randomized or assigned to receive RTx (intention-to-treat analysis). In contrast, at least 44% of all patients with pT4 papillary DTC in Germany in the nationwide PCES study underwent RTx in 1996 (p 2 -test). Conclusions: Acceptance of external beam RTx as a treatment modality for DTC has receded to a degree that accrual of a sufficient number of patients for a randomized trial has been impossible. Observation of the trial cohort is continued in order to assess clinical event rates with and without RTx and chronic RTx toxicity. (orig.) [de

The feasibility and safety of high-intensity focused ultrasound combined with low-dose external beam radiotherapy as supplemental therapy for advanced prostate cancer following hormonal therapy.

Science.gov (United States)

Wu, Rui-Yi; Wang, Guo-Min; Xu, Lei; Zhang, Bo-Heng; Xu, Ye-Qing; Zeng, Zhao-Chong; Chen, Bing

2011-05-01

The aim of this study was to investigate the feasibility and safety of high-intensity focused ultrasound (HIFU) combined with (+) low-dose external beam radiotherapy (LRT) as supplemental therapy for advanced prostate cancer (PCa) following hormonal therapy (HT). Our definition of HIFU+LRT refers to treating primary tumour lesions with HIFU in place of reduced field boost irradiation to the prostate, while retaining four-field box irradiation to the pelvis in conventional-dose external beam radiotherapy (CRT). We performed a prospective, controlled and non-randomized study on 120 patients with advanced PCa after HT who received HIFU, CRT, HIFU+LRT and HT alone, respectively. CT/MR imaging showed the primary tumours and pelvic lymph node metastases visibly shrank or even disappeared after HIFU+LRT treatment. There were significant differences among four groups with regard to overall survival (OS) and disease-specific survival (DSS) curves (P = 0.018 and 0.015). Further comparison between each pair of groups suggested that the long-term DSS of the HIFU+LRT group was higher than those of the other three groups, but there was no significant difference between the HIFU+LRT group and the CRT group. Multivariable Cox's proportional hazard model showed that both HIFU+LRT and CRT were independently associated with DSS (P = 0.001 and 0.035) and had protective effects with regard to the risk of death. Compared with CRT, HIFU+LRT significantly decreased incidences of radiation-related late gastrointestinal (GI) and genitourinary (GU) toxicity grade ≥ II. In conclusion, long-term survival of patients with advanced PCa benefited from strengthening local control of primary tumour and regional lymph node metastases after HT. As an alternative to CRT, HIFU+LRT showed good efficacy and better safety.

The international protocol for the dosimetry of external radiotherapy beams based on standards of absorbed dose to water

International Nuclear Information System (INIS)

Andreo, P.

2001-01-01

An International Code of Practice (CoP, or dosimetry protocol) for external beam radiotherapy dosimetry based on standards of absorbed dose to water has been published by the IAEA on behalf of IAEA, WHO, PAHO and ESTRO. The CoP provides a systematic and internationally unified approach for the determination of the absorbed dose to water in reference conditions with radiotherapy beams. The development of absorbed-dose-to-water standards for high-energy photons and electrons offers the possibility of reducing the uncertainty in the dosimetry of radiotherapy beams. Many laboratories already provide calibrations at the radiation quality of 60Co gamma-rays and some have extended calibrations to high-energy photon and electron beams. The dosimetry of kilovoltage x-rays, as well as that of proton and ion beams can also be based on these standards. Thus, a coherent dosimetry system based on the same formalism is achieved for practically all radiotherapy beams. The practical use of the CoP as simple. The document is formed by a set of different CoPs for each radiation type, which include detailed procedures and worksheets. All CoPs are based on ND,w chamber calibrations at a reference beam quality Qo, together with radiation beam quality correction factors kQ preferably measured directly for the user's chamber in a standards laboratory. Calculated values of kQ are provided together with their uncertainty estimates. Beam quality specifiers are 60Co, TPR20,10 (high-energy photons), R50 (electrons), HVL and kV (x-rays) and Rres (protons and ions) [es

High Power Diode Lasers with External Feedback: Overview and Prospects

DEFF Research Database (Denmark)

Chi, Mingjun; Petersen, Paul Michael

2012-01-01

In summary, different external-cavity feedback techniques to improve the spatial beam quality and narrow the linewidth of the output beam from both BALs and TDLs are presented. Broad-area diode laser system with external-cavity feedback around 800 nm can produce several Watts of output power...... with a good beam quality. Tapered diode laser systems with external-cavity feedback around 800 and 1060 nm can deliver more than 2 W output power with diffraction-limited beam quality and can be operated in single-longitudinal mode. These high-brightness, narrow linewidth, and tunable external-cavity diode...... lasers emerge as the next generation of compact lasers that have the potential of replacing conventional high power laser systems in many existing applications....

Trace elements in human, cattle and swine teeth, measured by external beam PIXE-PIGE setup

International Nuclear Information System (INIS)

Tabacniks, M.H.; Rizzutto, M.A.; Added, N.; Liguori Neto, R.; Acquadro, J.C.; Vilela, M.; Oliveira, T.R.C.F.; Markarian, R.A.; Mori, M.

2001-01-01

The use of animal teeth to replace human teeth in dentistry school classes and to test chemicals and fillings, motivated for a better characterization of the elementary composition of their enamel, since some of the chemical properties, adhesion and chemical compatibility may depend on these parameters. Cattle, swine and human teeth were collected by dentists of the University of Sao Paulo. These teeth came primarily from Sao Paulo region and were analyzed for trace elements at the Open Nuclear Physics Laboratory, using a high energy external proton beam, PIXE-PIGE setup

Characterization of the dose perturbation in tissue by stents as a function of external beam energy

International Nuclear Information System (INIS)

Schell, M.C.; Rosenzweig, D.P.; Weaver, K.A.; Rubin, P.

1997-01-01

Purpose: External beam irradiation of coronary arteries was shown to be detrimental in an animal model for the prevention of neointimal hyperplasia in the presence of stents when orthovoltage x-ray beams are used. This present study investigated the effect of beam energy on the dose distribution in the wall of the artery as a function of energy in the presence of stents in order to ascertain the effect on the dose due to beam energy. Materials and Methods: 250 kVp x-rays and 6-MV x rays were used to irradiate a stent placed in an homogeneous phantom. Radiochromic film densitometry and Monte Carlo calculations were used to measure and to simulate the dose distribution in the proximity of the stent. Result: External beam irradiation was reported to not only fail to prevent neointimal hyperplasia, but actually accentuate the neointimal response to a prompt mechanical injury in the artery. The photoelectric effect, which dominates low-energy x-ray interactions, produces recoil electrons in the stent which enhance the dose surrounding intima. The photoelectrons generated in nickel and iron have an extremely short range in normal tissue, approximately 0.1 mm. Initial estimates of orthovoltage x-ray interactions with the stent indicate a dose enhancement in the orthovoltage range by a factor of 2 to 3 due to the rise in the photoelectric cross section in this energy range depending on the elemental composition of the stent. Film densitometry verifies this dose enhancement. The Monte Carlo calculations yield a dose enhancement and the dose fall off with distance from the stent when irradiated with orthovoltage x-rays. Conversely when the tissue and stent are irradiated with megavoltage x-rays, the dose enhancement in this region is a factor of 1.15 in close proximity to the stent and 1.0 at distances greater than 0.1 mm. 6-MV photon interactions in tissue and iron are predominantly through Compton scattering. The Compton effect is dependent on the electron density in the

Experimental and analytical investigation of reinforced high strength concrete continuous beams strengthened with fiber reinforced polymer

International Nuclear Information System (INIS)

Akbarzadeh, H.; Maghsoudi, A.A.

2010-01-01

Carbon and glass fiber reinforced polymer (CFRP and GFRP) are two materials suitable for strengthening the reinforced concrete (RC) beams. Although many in situ RC beams are of continuous constructions, there has been very limited research on the behavior of such beams with externally applied FRP laminate. In addition, most design guidelines were developed for simply supported beams with external FRP laminates. This paper presents an experimental program conducted to study the flexural behavior and redistribution in moment of reinforced high strength concrete (RHSC) continuous beams strengthened with CFRP and GFRP sheets. Test results showed that with increasing the number of CFRP sheet layers, the ultimate strength increases, while the ductility, moment redistribution, and ultimate strain of CFRP sheet decrease. Also, by using the GFRP sheet in strengthening the continuous beam reduced loss in ductility and moment redistribution but it did not significantly increase ultimate strength of beam. The moment enhancement ratio of the strengthened continuous beams was significantly higher than the ultimate load enhancement ratio in the same beam. An analytical model for moment-curvature and load capacity are developed and used for the tested continuous beams in current and other similar studies. The stress-strain curves of concrete, steel and FRP were considered as integrity model. Stress-strain model of concrete is extended from Oztekin et al.'s model by modifying the ultimate strain. Also, new parameters of equivalent stress block are obtained for flexural calculation of RHSC beams. Good agreement between experiment and prediction values is achieved.

Complete response in a patient with gynecological hidradenocarcinoma treated with exclusive external beam radiotherapy and brachytherapy: a case report.

Science.gov (United States)

Giannelli, Flavio; Chiola, Ilaria; Belgioia, Liliana; Garelli, Stefania; Pastorino, Alice; Marcenaro, Michela; Mammoliti, Serafina; Costantini, Sergio; Bizzarri, Nicolò; Vellone, Valerio; Barra, Salvina; Corvò, Renzo

2017-12-01

Hidradenocarcinoma (HC) is a very rare disease. This case report illustrates a successful treatment of a 60-year-old woman with vulvo-vaginal localization of hidradenocarcinoma treated with external beam radiotherapy delivered by helical tomotherapy with a simultaneous integrated boost (SIB), followed by brachytherapy. External beam radiotherapy dose prescription was 50.4 Gy in 28 fractions, five fractions per week to whole pelvis (planning target volume 1 - PTV1), 60.2 Gy in 28 fractions to SIB1 (fundus of uterus and right inguinal node), and 58.8 Gy in 28 fractions to SIB2 (lower/middle third of vagina, paraurethral region and right inguinal lymph nodes). Brachytherapy dose prescription was 28 Gy in 4 fractions for cervix, fundus of uterus and upper third of vagina (HR-CTV1), and 22 Gy in 4 fractions to middle third of vagina and paraurethral region (HR-CTV2). D 90 for whole treatment was 91.9 Gy and 86.0 Gy for HR-CTV1 and HR-CTV2, respectively. Patient remained 12-months disease-free without treatment related side effects.

Complete response in a patient with gynecological hidradenocarcinoma treated with exclusive external beam radiotherapy and brachytherapy: a case report

Directory of Open Access Journals (Sweden)

Flavio Giannelli

2017-12-01

Full Text Available Hidradenocarcinoma (HC is a very rare disease. This case report illustrates a successful treatment of a 60-year-old woman with vulvo-vaginal localization of hidradenocarcinoma treated with external beam radiotherapy delivered by helical tomotherapy with a simultaneous integrated boost (SIB, followed by brachytherapy. External beam radiotherapy dose prescription was 50.4 Gy in 28 fractions, five fractions per week to whole pelvis (planning target volume 1 – PTV1, 60.2 Gy in 28 fractions to SIB1 (fundus of uterus and right inguinal node, and 58.8 Gy in 28 fractions to SIB2 (lower/middle third of vagina, paraurethral region and right inguinal lymph nodes. Brachytherapy dose prescription was 28 Gy in 4 fractions for cervix, fundus of uterus and upper third of vagina (HR-CTV1, and 22 Gy in 4 fractions to middle third of vagina and paraurethral region (HR-CTV2. D90 for whole treatment was 91.9 Gy and 86.0 Gy for HR-CTV1 and HR-CTV2, respectively. Patient remained 12-months disease-free without treatment related side effects.

Mechanical Behavior of Steel Fiber-Reinforced Concrete Beams Bonded with External Carbon Fiber Sheets.

Science.gov (United States)

Gribniak, Viktor; Tamulenas, Vytautas; Ng, Pui-Lam; Arnautov, Aleksandr K; Gudonis, Eugenijus; Misiunaite, Ieva

2017-06-17

This study investigates the mechanical behavior of steel fiber-reinforced concrete (SFRC) beams internally reinforced with steel bars and externally bonded with carbon fiber-reinforced polymer (CFRP) sheets fixed by adhesive and hybrid jointing techniques. In particular, attention is paid to the load resistance and failure modes of composite beams. The steel fibers were used to avoiding the rip-off failure of the concrete cover. The CFRP sheets were fixed to the concrete surface by epoxy adhesive as well as combined with various configurations of small-diameter steel pins for mechanical fastening to form a hybrid connection. Such hybrid jointing techniques were found to be particularly advantageous in avoiding brittle debonding failure, by promoting progressive failure within the hybrid joints. The use of CFRP sheets was also effective in suppressing the localization of the discrete cracks. The development of the crack pattern was monitored using the digital image correlation method. As revealed from the image analyses, with an appropriate layout of the steel pins, brittle failure of the concrete-carbon fiber interface could be effectively prevented. Inverse analysis of the moment-curvature diagrams was conducted, and it was found that a simplified tension-stiffening model with a constant residual stress level at 90% of the strength of the SFRC is adequate for numerically simulating the deformation behavior of beams up to the debonding of the CFRP sheets.

A consensus-based guideline defining clinical target volume for primary disease in external beam radiotherapy for intact uterine cervical cancer

International Nuclear Information System (INIS)

Toita, Takafumi; Ohno, Tatsuya; Kaneyasu, Yuko

2011-01-01

The objective of this study was to develop a consensus-based guideline to define clinical target volume for primary disease (clinical target volume primary) in external beam radiotherapy for intact uterine cervical cancer. The working subgroup of the Japan Clinical Oncology Group (JCOG) Radiation Therapy Study Group began developing a guideline for primary clinical target volume in November 2009. The group consisted of 10 radiation oncologists and 2 gynecologic oncologists. The process started with comparing the contouring on computed tomographic images of actual cervical cancer cases among the members. This was followed by a comprehensive literature review that included primary research articles and textbooks as well as information on surgical procedures. Extensive discussion occurred in face-to-face meetings (three occasions) and frequent e-mail communications until a consensus was reached. The working subgroup reached a consensus on the definition for the clinical target volume primary. The clinical target volume primary consists of the gross tumor volume, uterine cervix, uterine corpus, parametrium, vagina and ovaries. Definitions for these component structures were determined. Anatomical boundaries in all directions were defined for the parametrium. Examples delineating these boundaries were prepared for the posterior border of the parametrium for various clinical situations (id est (i.e.) central tumor bulk, degree of parametrial involvement). A consensus-based guideline defining the clinical target volume primary was developed for external beam radiotherapy for intact uterine cervical cancer. This guideline will serve as a template for radiotherapy protocols in future clinical trials. It may also be used in actual clinical practice in the setting of highly precise external beam radiotherapy, including intensity-modulated radiotherapy. (author)

A comparative study for different shielding material composition and beam geometry applied to PET facilities: simulated transmission curves

OpenAIRE

Hoff, Gabriela; Costa, Paulo Roberto

2013-01-01

The aim of this work is to simulate transmission data for different beam geometry and material composition in order to evaluate the effect of these parameters on transmission curves. The simulations are focused on outgoing spectra for shielding barriers used in PET facilities. The behavior of the transmission was evaluated as a function of the shielding material composition and thickness using Geant4 Monte Carlo code, version 9.2 p 03.The application was benchmarked for barited mortar and com...

Computation of undulator tuning curves

International Nuclear Information System (INIS)

Dejus, Roger J.

1997-01-01

Computer codes for fast computation of on-axis brilliance tuning curves and flux tuning curves have been developed. They are valid for an ideal device (regular planar device or a helical device) using the Bessel function formalism. The effects of the particle beam emittance and the beam energy spread on the spectrum are taken into account. The applicability of the codes and the importance of magnetic field errors of real insertion devices are addressed. The validity of the codes has been experimentally verified at the APS and observed discrepancies are in agreement with predicted reduction of intensities due to magnetic field errors. The codes are distributed as part of the graphical user interface XOP (X-ray OPtics utilities), which simplifies execution and viewing of the results

A digital fluoroscopic imaging system for verification during external beam radiotherapy

International Nuclear Information System (INIS)

Takai, Michikatsu

1990-01-01

A digital fluoroscopic (DF) imaging system has been constructed to obtain portal images for verification during external beam radiotherapy. The imaging device consists of a fluorescent screen viewed by a highly sensitive video camera through a mirror. The video signal is digitized and processed by an image processor which is linked on-line with a host microcomputer. The image quality of the DF system was compared with that of film for portal images of the Burger phantom and the Alderson anthropomorphic phantom using 10 MV X-rays. Contrast resolution of the DF image integrated for 8.5 sec. was superior to the film resolution, while spatial resolution was slightly inferior. The DF image of the Alderson phantom processed by the adaptive histogram equalization was better in showing anatomical landmarks than the film portal image. The DF image integrated for 1 sec. which is used for movie mode can show patient movement during treatment. (author)

Compact TXRF system using doubly curved crystal optics

International Nuclear Information System (INIS)

Chen, Z.W.

2000-01-01

Doubly curved crystal optics can provide large collection solid angle from a small x-ray source but were difficult to be fabricated in the past. The recent innovative doubly curved crystal optic technology provides accurate bending figure of thin crystal and produces high performance doubly curved crystal optics. The high quality doubly curved crystal can increase the intensity of the primary beam significantly for total reflection x-ray fluorescence application based on a low power x-ray source. In this report, toroidal Si(220) crystals are used to focused Cu Kα and Mo Kα x-rays from low power compact x-ray tubes that have maximum power setting at 50 kV and 1 mA. With a slit aperture to control the convergent angle, a fan Cu Kα1 beam with 15 degree x 0.2 degree convergent angles is obtained for TXRF excitation. Similarly, a fan Mo Kα1 beam with 6 degree x 0.1 degree convergent angles is used for high energy excitation. Si wafer based TXRF samples will be prepared and measured using this technique and the experimental data. (author)

A comparison of two methods for estimating the technical costs of external beam radiation therapy

International Nuclear Information System (INIS)

Hayman, James A.; Lash, Kathy A.; Tao, May L.; Halman, Marc A.

2000-01-01

Purpose: To accurately assess the cost-effectiveness of treatment with external beam radiation, it is necessary to have accurate estimates of its cost. One of the most common methods for estimating technical costs has been to convert Medicare charges into costs using Medicare Cost-to-Charge Ratios (CCR). More recently, health care organizations have begun to invest in sophisticated cost-accounting systems (CAS) that are capable of providing procedure-specific cost estimates. The purpose of this study was to examine whether these competing approaches result in similar cost estimates for four typical courses of external beam radiation therapy (EBRT). Methods and Materials: Technical costs were estimated for the following treatment courses: 1) a palliative 'simple' course of 10 fractions using a single field without blocks; 2) a palliative 'complex' course of 10 fractions using two opposed fields with custom blocks; 3) a curative course of 30 fractions for breast cancer using tangent fields followed by an electron beam boost; and 4) a curative course of 35 fractions for prostate cancer using CT-planning and a 4-field technique. Costs were estimated using the CCR approach by multiplying the number of units of each procedure billed by its Medicare charge and CCR and then summing these costs. Procedure-specific cost estimates were obtained from a cost-accounting system, and overall costs were then estimated for the CAS approach by multiplying the number of units billed by the appropriate unit cost estimate and then summing these costs. All costs were estimated using data from 1997. The analysis was also repeated using data from another academic institution to estimate their costs using the CCR and CAS methods, as well as the appropriate relative value units (RVUs) and conversion factor from the 1997 Medicare Fee Schedule to estimate Medicare reimbursement for the four treatment courses. Results: The estimated technical costs for the CCR vs. CAS approaches for the four

External beam radiotherapy for subretinal neovascularization in age-related macular degeneration: is this treatment efficient?

International Nuclear Information System (INIS)

Staar, Susanne; Krott, Ralf; Mueller, Rolf-Peter; Bartz-Schmidt, Karl U.; Heimann, Klaus

1999-01-01

Purpose: Control of the natural course of sub retinal neovascularization (SRNV) in age-related macular degeneration (AMD) is difficult. Only a subset of patients is suitable for laser coagulation. This prospective study aimed to determine the efficacy and individual benefit of external beam radiotherapy (EBRT). Methods and Materials: The prospective trial included 287 patients with subfoveal neovascularization due to AMD which was verified by fluorescein angiography. Patients have been treated between January 1996 and October 1997. All patients received a total dose of 16 Gy in 2-Gy daily fractions with 5-6 MeV photons based on computerized treatment planning in individual head mask fixation. This first analysis is based on 73 patients (50 women, 23 men, median age 74.3 years), with a median follow-up of 13.3 months and a minimum follow-up of 11 months. Results: All patients completed therapy and tolerability was good. First clinical control with second angiography was performed 6 weeks after irradiation, then in 3-month intervals. Eighteen patients with SRNV refusing radiotherapy served as a control group and were matched with 18 irradiated patients. After 7 months median visual acuity (VA) was 20/160 for the irradiated and 20/400 for the untreated patients. One year after radiotherapy final median VA was 20/400 in both groups. Conclusion: These results suggest that 16 Gy of conventionally fractionated external beam irradiation slows down the visual loss in exudative AMD for only a few months. Patients' reading vision could not be saved for a long-term run

An examination of human factors in external beam radiation therapy: Findings and implications

International Nuclear Information System (INIS)

Henriksen, K.; Kaye, R.D.; Jones, R.E. Jr.; Morisseau, D.S.; Persensky, J.J.

1994-01-01

To better understand the contributing factors to human error in external beam radiation therapy, the US Nuclear Regulatory Commission has undertaken a series of human factors evaluations. A team of human factors specialists, assisted by a panel of radiation oncologists, medical physicists, and radiation technologists, conducted visits to 24 radiation oncology departments at community hospitals, university centers, and free-standing clinics. A function and task analysis was initially performed to guide subsequent evaluations in the areas of human-system interfaces, procedures, training and qualifications, and organizational policies and practices. Representative findings and implications for improvement are discussed within the context of a dynamic model which holds that misadministration likely results from the unanticipated interaction of several necessary but singly insufficient conditions

Electromechanical response of a curved piezoelectric nanobeam with the consideration of surface effects

International Nuclear Information System (INIS)

Yan Zhi; Jiang Liying

2011-01-01

This work investigates the electromechanical response of a curved piezoelectric nanobeam with the consideration of surface effects through the surface-layer-based model and the generalized Young-Laplace equations. For nanoscale piezoelectric structures, the surface effects also include surface piezoelectricity in addition to the residual surface stress and surface elasticity for elastic nanomaterials. A Euler-Bernoulli curved beam theory is used to get the explicit solutions for the electroelastic fields of a curved cantilever beam when subjected to mechanical and electrical loads. In order to apply the appropriate boundary conditions on the beam, effective axial force, shear force and moment are derived. The results indicate that the surface effects play a significant role in the electroelastic fields and the piezoelectric response of the curved piezoelectric nanobeam. It is also found that the coupling of the residual surface stress, the surface elasticity and the surface piezoelectricity may be dramatic despite that the influence of the individual one is small under some circumstances. This study is expected to be useful for design and applications of curved beam based piezoelectric nanodevices, such as the curved nanowires/nanobelts or nanorings as nanoswitches or nanoactuators for displacement control purpose.

Effect of beam arrangement on oral cavity dose in external beam radiotherapy of nasopharyngeal carcinoma

International Nuclear Information System (INIS)

Wu, Vincent W.C.; Yang Zhining; Zhang Wuzhe; Wu Lili; Lin Zhixiong

2012-01-01

This study compared the oral cavity dose between the routine 7-beam intensity-modulated radiotherapy (IMRT) beam arrangement and 2 other 7-beam IMRT with the conventional radiotherapy beam arrangements in the treatment of nasopharyngeal carcinoma (NPC). Ten NPC patients treated by the 7-beam routine IMRT technique (IMRT-7R) between April 2009 and June 2009 were recruited. Using the same computed tomography data, target information, and dose constraints for all the contoured structures, 2 IMRT plans with alternative beam arrangements (IMRT-7M and IMRT-7P) by avoiding the anterior facial beam and 1 conventional radiotherapy plan (CONRT) were computed using the Pinnacle treatment planning system. Dose-volume histograms were generated for the planning target volumes (PTVs) and oral cavity from which the dose parameters and the conformity index of the PTV were recorded for dosimetric comparisons among the plans with different beam arrangements. The dose distributions to the PTVs were similar among the 3 IMRT beam arrangements, whereas the differences were significant between IMRT-7R and CONRT plans. For the oral cavity dose, the 3 IMRT beam arrangements did not show significant difference. Compared with IMRT-7R, CONRT plan showed a significantly lower mean dose, V30 and V-40, whereas the V-60 was significantly higher. The 2 suggested alternative beam arrangements did not significantly reduce the oral cavity dose. The impact of varying the beam angles in IMRT of NPC did not give noticeable effect on the target and oral cavity. Compared with IMRT, the 2-D conventional radiotherapy irradiated a greater high-dose volume in the oral cavity.

Urinary incontinence in prostate cancer patients treated with external beam radiotherapy

International Nuclear Information System (INIS)

Liu, Mitchell; Pickles, Tom; Berthelet, Eric; Agranovich, Alexander; Kwan, Winkle; Tyldesley, Scott; McKenzie, Michael; Keyes, Mira; Morris, James; Pai, Howard

2005-01-01

Background and purpose: To describe the incidence of urinary incontinence among prostate cancer patients treated with external beam radiotherapy (RT) and to investigate associated risk factors. Patients and methods: One thousand and hundred ninety-two patients with ≥24 months follow-up were the subjects of this series. All patients received between 50 and 72 Gy in 20-37 fractions (median 66 Gy/33). Post-RT urinary incontinence was scored by direct patient interviewing according to the modified RTOG/SOMA scale: Grade 1-occasional use of incontinence pads, Grade 2-intermittent use of incontinence pads, Grade 3-persistent use of incontinence pads, and Grade 4-permanent catheter. Risk-factors investigated were: age, diabetes, TURP prior to RT, elapsed time from TURP to RT, clinical stage, RT dose and presence of Grade ≥2 acute GU and GI toxicity. Non-parametric, actuarial univariate (Kaplan-Meier) and multivariate tests (MVA, Cox regression) were performed. Results: Median follow-up for the group is 52 months (24-109). Thirty-four patients (2.9%) had incontinence prior to RT, which was more common in TURP patients (7.8% vs 1.6% P<0.001). These are excluded from further analysis. Fifty-seven patients (4.9%) developed Grade 1 incontinence, 7 (0.6%) Grade 2, and 7 (0.6%) Grade 3. There was no Grade 4 incontinence. Actuarial rates for Grade ≥1 and ≥2 incontinence at 5 years are 7 and 1.7%, respectively. Risk factors on MVA associated with the development of Grade 1 or worse incontinence are pre-RT TURP (5-year rates 10% vs 6%, P=0.026), presence of Grade ≥2 acute GU toxicity (5-year rates 11% vs 5%, P=0.002). Age, diabetes, clinical stage, elapsed time from TURP to RT, RT dose or fraction size, acute GI toxicity were not significant. Patients who underwent post-RT TURP or dilatation for obstructive symptoms (4.3%), were more likely to develop Grade 2-3 incontinence (5-year rate 8 vs 1.5%, P=0.0015). Conclusions: Grade 2 or greater urinary incontinence is rare

A Phase II study of external-beam radiotherapy and endovascular brachytherapy with PTA and stenting for femoropopliteal artery restenosis

International Nuclear Information System (INIS)

Narayan, Kailash; Denton, Michael; Das, Ram; Bernshaw, David; Rolfo, Aldo; Dyk, Sylvia van; Mirakian, Alex

2006-01-01

Purpose: To assess the safety and seek evidence of efficacy of combined external-beam radiotherapy (EBRT) and endovascular brachytherapy in the treatment of stenotic vascular lesions. Methods and Materials: Seventeen patients with high risk for restenosis of femoropopliteal arteries were enrolled in this study from February 2000 to August 2002. The external beam radiotherapy regimen consisted of 10 Gy in 5 fractions of 2 Gy, starting on Day 0. This was followed on Day 6 by angiography, stent placement, and intraluminal brachytherapy to a dose of 10 Gy at 1.2 mm from stent surface. The EBRT was continued from the same day to another 10 Gy in 2 Gy daily fractions for 5 days. Results: The follow up ranged from 33 months to 60 months. At the time of analysis 15 of 17 patients were alive with patent stents. Of these, 10 were symptom-free. Two patients died of unrelated causes. Conclusions: The combination of EBRT and endovascular brachytherapy provided adequate dose distribution without any geographical miss or 'candy wrapper' restenosis. No incidence of aneurysmal dilation of radiated vascular segment was observed. The treatment was feasible, well tolerated, and achieved 88% stenosis free survival

Study on Flexural Behaviour of Ternary Blended Reinforced Self Compacting Concrete Beam with Conventional RCC Beam

Science.gov (United States)

Marshaline Seles, M.; Suryanarayanan, R.; Vivek, S. S.; Dhinakaran, G.

2017-07-01

The conventional concrete when used for structures having dense congested reinforcement, the problems such as external compaction and vibration needs special attention. In such case, the self compacting concrete (SCC) which has the properties like flow ability, passing and filling ability would be an obvious answer. All those SCC flow behavior was governed by EFNARC specifications. In present study, the combination type of SCC was prepared by replacing cement with silica fume (SF) and metakaolin (MK) along with optimum dosages of chemical admixtures. From the fresh property test, cube compressive strength and cylinder split tensile strength, optimum ternary mix was obtained. In order to study the flexural behavior, the optimum ternary mix was taken in which beam specimens of size 1200 mm x 100 mm x 200 mm was designed as singly reinforced section according to IS: 456-2000, Limit state method. Finally the comparative experimental analysis was made between conventional RCC and SCC beams of same grade in terms of flexural strength namely yield load & ultimate load, load- deflection curve, crack size and pattern respectively.

Bevalac external beamline optics

International Nuclear Information System (INIS)

Kalnins, J.G.; Krebs, G.F.; Tekawa, M.M.; Alonso, J.R.

1987-04-01

This handbook is intended as an aid for tuning the external particle beam (EPB) lines at the Lawrence Berkeley Laboratory's Bevalac. The information contained within will be useful to the Bevalac's Main Control Room and experimenters alike. First, some general information is given concerning the EPB lines and beam optics. Next, each beam line is described in detail: schematics of the beam line components are shown, all the variables required to run a beam transport program are presented, beam envelopes are given with wire chamber pictures and magnet currents, focal points and magnifications. Some preliminary scaling factors are then presented which should aid in choosing a given EPB magnet's current for a given central Bevalac field. Finally, some tuning hints are suggested

Finite Element Simulation of GFRP Reinforced Concrete Beam Externally Strengthened With CFRP Plates

Directory of Open Access Journals (Sweden)

Salleh Norhafizah

2017-01-01

Full Text Available The construction technology now has become more and more advanced allowing the development of new technologies or material to replace the previous one and also solved some of the troubles confronted by construction experts. The Glass Fibre Reinforced Polymer (GFRP composite is an alternative to replace the current usage of steel as it is rust proof and stronger in terms of stiffness compared to steel. Furthermore, GFRP bars have a high strength-to-weight ratio, making them attractive as reinforcement for concrete structures. However, the tensile behavior of GFRP bars is characterized by a linear elastic stress–strain relationship up to failure and, therefore, concrete elements reinforced with GFRP reinforcement exhibit brittle failure without warning. Design codes encourage over-reinforced GFRP design since it is more progressive and leads to a less catastrophic failure with a higher degree of deformability. Moreover, because of GFRP low modulus of elasticity, GFRP reinforced concrete members exhibit larger deflections and wider cracks width than steel reinforced concrete. This aims of this paper is to developed 2D Finite Element (FE models that can accurately simulate the respond on an improvement in the deflection of GFRP reinforced concrete beam externally strengthened with CFRP plates on the tension part of beam. The prediction of flexural response according to RCCSA software was also discussed. It was observed that the predicted FE results are given similar result with the experimental measured test data. Base on this good agreement, a parametric study was the performed using the validation FE model to investigate the effect of flexural reinforcement ratio and arrangement of the beams strengthened with different regions of CFRP plates.

Nonlinear vibrations of an inclined beam subjected to a moving load

International Nuclear Information System (INIS)

Mamandi, A; Kargarnovin, M H; Younesian, D

2009-01-01

In this paper, the nonlinear dynamic responses of an inclined pinned-pinned Euler-Bernoulli beam with a constant cross section and finite length subjected to a concentrated vertical force traveling with constant velocity is investigated by using the mode summation method. Frequency analysis of the PDE's governing equations of motion for steady-state response is studied by applying multiple scales method. The nonlinear dynamic deflections of the beam are obtained by solving two coupled nonlinear PDE's governing equations of planar motion for both longitudinal and transverse oscillations of the beam. The dynamic magnification factor and normalized time histories of mid-point of the beam are obtained for various load velocity ratios and the numerical results are compared with those obtained from traditional linear solution. It is found that quadratic nonlinearity renders the softening effect on the dynamic response of the beam under the act of traveling load. Also stability analysis of the steady-state response for the modes equations having quadratic nonlinearity is carried out and it is observed from the amplitude response curves that for the case of internal-external primary resonance, both saturation phenomenon and jump phenomenon are predicted for the longitudinal excitation.

High intensity beam dump for the Tevatron beam abort system

International Nuclear Information System (INIS)

Kidd, J.; Mokhov, N.; Murphy, T.; Palmer, M.; Toohig, T.; Turkot, F.; VanGinneken, A.

1981-01-01

The beam abort system proposed for the Fermilab Tevatron Accelerator will extract the proton beam from the ring in a single turn (approximately 20/mu/s) and direct it to an external beam dump. It is the function of the beam dump to absorb the unwanted beam and limit the escaping radiation to levels that are acceptable to the surrounding populace and apparatus. A beam dump that is expected to meet these requirements has been designed and constructed. Detailed design of the dump, including considerations leading to the choice of materials, are given. 6 refs

TU-D-201-03: Results of a Survey On the Implementation of the TG-51 Protocol and Associated Addendum On Reference Dosimetry of External Beams

Energy Technology Data Exchange (ETDEWEB)

Kim, G [University of California, San Diego, La Jolla, CA (United States); Muir, B [National Research Council, Ottawa, AB (Canada); Culberson, W [University of Wisconsin Madison, Madison, WI (United States); Davis, S [McGill University Health Center, Montreal, QC (Canada); Huang, Y [Henry Ford Health System, West Bloomfield, MI (United States); Lee, S [University of Maryland School of Medicine, Columbia, MD (United States); Lowenstein, J [UT MD Anderson Cancer Center, Houston, TX (United States); Sarfehnia, A [Sunnybrook Health Science Center, Toronto, ON (Canada); Tolani, N [Michael E. DeBakey VA Medical Center, Sugarland (United States); Siebers, J [University of Virginia Health System, Charlottesville, VA (United States)

2016-06-15

Purpose: The working group on the review and extension of the TG-51 protocol (WGTG51) collected data from American Association of Physicists in Medicine (AAPM) members with respect to their current TG-51 and associated addendum usage in the interest of considering future protocol addenda and guidance on reference dosimetry best practices. This study reports an overview of this survey on dosimetry of external beams. Methods: Fourteen survey questions were developed by WGTG51 and released in November 2015. The questions collected information on reference dosimetry, beam quality specification, and ancillary calibration equipment. Results: Of the 190 submissions completed worldwide (U.S. 70%), 83% were AAPM members. Of the respondents, 33.5% implemented the TG-51 addendum, with the maximum calibration difference for any photon beam, with respect to the original TG-51 protocol, being <1% for 97.4% of responses. One major finding is that 81.8% of respondents used the same cylindrical ionization chamber for photon and electron dosimetry, implying that many clinics are foregoing the use of parallel-plate chambers. Other evidence suggests equivalent dosimetric results can be obtained with both cylindrical and parallel-plate chambers in electron beams. This, combined with users comfort with cylindrical chambers for electrons will likely impact recommendations put forward in an upcoming electron beam addendum to the TG-51 protocol. Data collected on ancillary equipment showed 58.2% (45.0%) of the thermometers (barometers) in use for beam calibration had NIST traceable calibration certificates, but 48.4% (42.7%) were never recalibrated. Conclusion: This survey provides a snapshot of TG-51 external beam reference dosimetry practice in radiotherapy centers. Findings demonstrate the rapid take-up of the TG-51 photon beam addendum and raise issues for the WGTG51 to focus on going forward, including guidelines on ancillary equipment and the choice of chamber for electron beam

Noninvasive referencing of intraocular tumors for external beam radiation therapy using optical coherence tomography: A proof of concept

International Nuclear Information System (INIS)

Rüegsegger, Michael B.; Steiner, Patrick; Kowal, Jens H.; Geiser, Dominik; Pica, Alessia; Aebersold, Daniel M.

2014-01-01

Purpose: External beam radiation therapy is currently considered the most common treatment modality for intraocular tumors. Localization of the tumor and efficient compensation of tumor misalignment with respect to the radiation beam are crucial. According to the state of the art procedure, localization of the target volume is indirectly performed by the invasive surgical implantation of radiopaque clips or is limited to positioning the head using stereoscopic radiographies. This work represents a proof-of-concept for direct and noninvasive tumor referencing based on anterior eye topography acquired using optical coherence tomography (OCT). Methods: A prototype of a head-mounted device has been developed for automatic monitoring of tumor position and orientation in the isocentric reference frame for LINAC based treatment of intraocular tumors. Noninvasive tumor referencing is performed with six degrees of freedom based on anterior eye topography acquired using OCT and registration of a statistical eye model. The proposed prototype was tested based on enucleated pig eyes and registration accuracy was measured by comparison of the resulting transformation with tilt and torsion angles manually induced using a custom-made test bench. Results: Validation based on 12 enucleated pig eyes revealed an overall average registration error of 0.26 ± 0.08° in 87 ± 0.7 ms for tilting and 0.52 ± 0.03° in 94 ± 1.4 ms for torsion. Furthermore, dependency of sampling density on mean registration error was quantitatively assessed. Conclusions: The tumor referencing method presented in combination with the statistical eye model introduced in the past has the potential to enable noninvasive treatment and may improve quality, efficacy, and flexibility of external beam radiotherapy of intraocular tumors

Beam-centric algorithm for pretreatment patient position correction in external beam radiation therapy

International Nuclear Information System (INIS)

Bose, Supratik; Shukla, Himanshu; Maltz, Jonathan

2010-01-01

Purpose: In current image guided pretreatment patient position adjustment methods, image registration is used to determine alignment parameters. Since most positioning hardware lacks the full six degrees of freedom (DOF), accuracy is compromised. The authors show that such compromises are often unnecessary when one models the planned treatment beams as part of the adjustment calculation process. The authors present a flexible algorithm for determining optimal realizable adjustments for both step-and-shoot and arc delivery methods. Methods: The beam shape model is based on the polygonal intersection of each beam segment with the plane in pretreatment image volume that passes through machine isocenter perpendicular to the central axis of the beam. Under a virtual six-DOF correction, ideal positions of these polygon vertices are computed. The proposed method determines the couch, gantry, and collimator adjustments that minimize the total mismatch of all vertices over all segments with respect to their ideal positions. Using this geometric error metric as a function of the number of available DOF, the user may select the most desirable correction regime. Results: For a simulated treatment plan consisting of three equally weighted coplanar fixed beams, the authors achieve a 7% residual geometric error (with respect to the ideal correction, considered 0% error) by applying gantry rotation as well as translation and isocentric rotation of the couch. For a clinical head-and-neck intensity modulated radiotherapy plan with seven beams and five segments per beam, the corresponding error is 6%. Correction involving only couch translation (typical clinical practice) leads to a much larger 18% mismatch. Clinically significant consequences of more accurate adjustment are apparent in the dose volume histograms of target and critical structures. Conclusions: The algorithm achieves improvements in delivery accuracy using standard delivery hardware without significantly increasing

Controlling laser ablation plasma with external electrodes. Application to sheath dynamics study and beam physics

International Nuclear Information System (INIS)

Isono, Fumika; Nakajima, Mitsuo; Hasegawa, Jun; Kawamura, Tohru; Horioka, Kazuhiko

2013-01-01

The potential of laser ablation plasma was controlled successfully by using external ring electrodes. We found that an electron sheath is formed at the plasma boundary, which plays an important role in the potential formation. When the positively biased plasma reaches a grounded grid, electrons in the plasma are turned away and ions are accelerated, which leads to the formation of a virtual anode between the grid and an ion probe. We think that this device which can raise the plasma potential up to order of kV can be applied to the study of sheath dynamics and to a new type of ion beam extraction. (author)

Peripheral photon and neutron doses from prostate cancer external beam irradiation.

Science.gov (United States)

Bezak, Eva; Takam, Rundgham; Marcu, Loredana G

2015-12-01

Peripheral photon and neutron doses from external beam radiotherapy (EBRT) are associated with increased risk of carcinogenesis in the out-of-field organs; thus, dose estimations of secondary radiation are imperative. Peripheral photon and neutron doses from EBRT of prostate carcinoma were measured in Rando phantom. (6)LiF:Mg,Cu,P and (7)LiF:Mg,Cu,P glass-rod thermoluminescence dosemeters (TLDs) were inserted in slices of a Rando phantom followed by exposure to 80 Gy with 18-MV photon four-field 3D-CRT technique. The TLDs were calibrated using 6- and 18-MV X-ray beam. Neutron dose equivalents measured with CR-39 etch-track detectors were used to derive readout-to-neutron dose conversion factor for (6)LiF:Mg,Cu,P TLDs. Average neutron dose equivalents per 1 Gy of isocentre dose were 3.8±0.9 mSv Gy(-1) for thyroid and 7.0±5.4 mSv Gy(-1) for colon. For photons, the average dose equivalents per 1 Gy of isocentre dose were 0.2±0.1 mSv Gy(-1) for thyroid and 8.1±9.7 mSv Gy(-1) for colon. Paired (6)LiF:Mg,Cu,P and (7)LiF:Mg,Cu,P TLDs can be used to measure photon and neutron doses simultaneously. Organs in close proximity to target received larger doses from photons than those from neutrons whereas distally located organs received higher neutron versus photon dose. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Future of external beam irradiation as initial treatment of rectal cancer

Energy Technology Data Exchange (ETDEWEB)

Papillon, J.

1987-06-01

The authors' protocol consists of a split-course regimen with a short course of cobalt-60 arc rotation (3000 c/Gy in 12 days). After 2 months rest, the second stage treatment depends upon the pressure of residual disease and the tumour site. It consists of either radical surgery (82 cases) or conservative treatment by intracavitary irradiation in the event of a favourable initial response or in the case of poor risk patients (73 cases). In the radiotherapy-surgical group, the subsequent operative specimens were tumour free in 17% of cases and assigned to Dukes' A category in 32% of cases. Of 91 patients with T/sub 2/ or T/sub 3/ tumour involving the lower third of the rectum (followed up for more than 3 years) 72(84%) had no recurrence. Thirty-three of these patients (46%) underwent a colostomy while 39 (54%) has normal anal function. These results demonstrate the major place that a properly planned external beam irradiation can have in the curative management of cancers of the low rectum.

Accelerated partial breast irradiation with external beam radiotherapy. First results of the German phase 2 trial

Energy Technology Data Exchange (ETDEWEB)

Ott, Oliver J.; Strnad, Vratislav; Stillkrieg, Wilhelm; Fietkau, Rainer [University Hospital Erlangen, Department of Radiation Oncology, Erlangen (Germany); Uter, Wolfgang [University Erlangen-Nuremberg, Dept. of Medical Informatics, Biometry and Epidemiology, Erlangen (Germany); Beckmann, Matthias W. [University Hospital Erlangen, Dept. of Gynecology, Erlangen (Germany)

2017-01-15

To evaluate the feasibility and efficacy of external beam three-dimensional (3D) conformal accelerated partial breast irradiation (APBI) for selected patients with early breast cancer. Between 2011 and 2016, 72 patients were recruited for this prospective phase 2 trial. Patients were eligible for APBI if they had histologically confirmed breast cancer or pure ductal carcinoma in situ (DCIS), a tumor diameter ≤3 cm, clear resection margins ≥2 mm, no axillary lymph node involvement, no distant metastases, tumor bed clips, and were aged ≥50 years. Patients were excluded if mammography showed a multicentric invasive growth pattern, or if they had residual diffuse microcalcifications postoperatively, an extensive intraductal component, or vessel invasion. Patients received 3D conformal external beam APBI with a total dose of 38 Gy in 10 fractions in 1-2 weeks. The trial had been registered at the German Clinical Trials Register, DRKS-ID: DRKS00004417. Median follow-up was 25.5 months (range 1-61 months). Local control was maintained in 71 of 72 patients. The 3-year local recurrence rate was 2.1% (95% confidence interval, CI: 0-6.1%). Early toxicity (grade 1 radiodermatitis) was seen in 34.7% (25/72). Late side effects ≥ grade 3 did not occur. Cosmetic results were rated as excellent/good in 96.7% (59/61). APBI with external beam radiotherapy techniques is feasible with low toxicity and, according to the results of the present and other studies, on the way to becoming a standard treatment option for a selected subgroup of patients. (orig.) [German] Untersuchung der Vertraeglichkeit und Sicherheit der externen, 3-D-konformalen akzelerierten Teilbrustbestrahlung (APBI) fuer ausgewaehlte Patientinnen mit einem fruehen Mammakarzinom. Von 2011 bis 2016 wurden 72 Patientinnen in diese prospektive Phase-2-Studie eingebracht. Einschlusskriterien waren ein histologisch gesichertes Mammakarzinom oder DCIS, ein Tumordurchmesser ≤ 3 cm, tumorfreie Resektionsraender ≥ 2

Bevalac external beamline optics

Energy Technology Data Exchange (ETDEWEB)

Kalnins, J.G.; Krebs, G.F.; Tekawa, M.M.; Alonso, J.R.

1987-04-01

This handbook is intended as an aid for tuning the external particle beam (EPB) lines at the Lawrence Berkeley Laboratory's Bevalac. The information contained within will be useful to the Bevalac's Main Control Room and experimenters alike. First, some general information is given concerning the EPB lines and beam optics. Next, each beam line is described in detail: schematics of the beam line components are shown, all the variables required to run a beam transport program are presented, beam envelopes are given with wire chamber pictures and magnet currents, focal points and magnifications. Some preliminary scaling factors are then presented which should aid in choosing a given EPB magnet's current for a given central Bevalac field. Finally, some tuning hints are suggested.

External Beam Radiotherapy for Clinically Localized Hormone-Refractory Prostate Cancer: Clinical Significance of Nadir Prostate-Specific Antigen Value Within 12 Months

International Nuclear Information System (INIS)

Ogawa, Kazuhiko; Nakamura, Katsumasa; Sasaki, Tomonari; Onishi, Hiroshi; Koizumi, Masahiko; Shioyama, Yoshiyuki; Araya, Masayuki; Mukumoto, Nobutaka M.S.; Mitsumori, Michihide; Teshima, Teruki

2009-01-01

Purpose: To analyze retrospectively the results of external beam radiotherapy for clinically localized hormone-refractory prostate cancer and investigate the clinical significance of nadir prostate-specific antigen (PSA) value within 12 months (nPSA12) as an early estimate of clinical outcomes after radiotherapy. Methods and Materials: Eighty-four patients with localized hormone-refractory prostate cancer treated with external beam radiotherapy were retrospectively reviewed. The total radiation doses ranged from 30 to 76 Gy (median, 66 Gy), and the median follow-up period for all 84 patients was 26.9 months (range, 2.7-77.3 months). Results: The 3-year actuarial overall survival, progression-free survival (PFS), and local control rates in all 84 patients after radiotherapy were 67%, 61%, and 93%, respectively. Although distant metastases and/or regional lymph node metastases developed in 34 patients (40%) after radiotherapy, local progression was observed in only 5 patients (6%). Of all 84 patients, the median nPSA12 in patients with clinical failure and in patients without clinical failure was 3.1 ng/mL and 0.5 ng/mL, respectively. When dividing patients according to low (<0.5 ng/mL) and high (≥0.5 ng/mL) nPSA12 levels, the 3-year PFS rate in patients with low nPSA12 and in those with high nPSA12 was 96% and 44%, respectively (p < 0.0001). In univariate analysis, nPSA12 and pretreatment PSA value had a significant impact on PFS, and in multivariate analysis nPSA12 alone was an independent prognostic factor for PFS after radiotherapy. Conclusions: External beam radiotherapy had an excellent local control rate for clinically localized hormone-refractory prostate cancer, and nPSA12 was predictive of clinical outcomes after radiotherapy.

Comparative sensitivities of functional MRI sequences in detection of local recurrence of prostate carcinoma after radical prostatectomy or external-beam radiotherapy.

Science.gov (United States)

Roy, Catherine; Foudi, Fatah; Charton, Jeanne; Jung, Michel; Lang, Hervé; Saussine, Christian; Jacqmin, Didier

2013-04-01

The aim of this retrospective study was to determine the respective accuracies of three types of functional MRI sequences-diffusion-weighted imaging (DWI), dynamic contrast-enhanced (DCE) MRI, and 3D (1)H-MR spectroscopy (MRS)-in the depiction of local prostate cancer recurrence after two different initial therapy options. From a cohort of 83 patients with suspicion of local recurrence based on prostate-specific antigen (PSA) kinetics who were imaged on a 3-T MRI unit using an identical protocol including the three functional sequences with an endorectal coil, we selected 60 patients (group A, 28 patients who underwent radical prostatectomy; group B, 32 patients who underwent external-beam radiation) who had local recurrence ascertained on the basis of a transrectal ultrasound-guided biopsy results and a reduction in PSA level after salvage therapy. All patients presented with a local relapse. Sensitivity with T2-weighted MRI and 3D (1)H-MRS sequences was 57% and 53%, respectively, for group A and 71% and 78%, respectively, for group B. DCE-MRI alone showed a sensitivity of 100% and 96%, respectively, for groups A and B. DWI alone had a higher sensitivity for group B (96%) than for group A (71%). The combination of T2-weighted imaging plus DWI plus DCE-MRI provided a sensitivity as high as 100% in group B. The performance of functional imaging sequences for detecting recurrence is different after radical prostatectomy and external-beam radiotherapy. DCE-MRI is a valid and efficient tool to detect prostate cancer recurrence in radical prostatectomy as well as in external-beam radiotherapy. The combination of DCE-MRI and DWI is highly efficient after radiation therapy. Three-dimensional (1)H-MRS needs to be improved. Even though it is not accurate enough, T2-weighted imaging remains essential for the morphologic analysis of the area.

Injectable silver nanosensors: in vivo dosimetry for external beam radiotherapy using positron emission tomography

DEFF Research Database (Denmark)

Christensen, Anders Nymark; Rydhög, J. S.; Søndergaard, Rikke Vicki

2016-01-01

Development of safe and efficient radiotherapy routines requires quantification of the delivered absorbed dose to the cancer tissue in individual patients. In vivo dosimetry can provide accurate information about the absorbed dose delivered during treatment. In the current study, a novel silver......-nanosensor formulation based on poly(vinylpyrrolidinone)-coated silver nanoparticles formulated in a gelation matrix composed of sucrose acetate isobutyrate has been developed for use as an in vivo dosimeter for external beam radiotherapy. In situ photonuclear reactions trigger the formation of radioactive (106)Ag......, which enables post treatment verification of the delivered dose using positron emission tomography imaging. The silver-nanosensor was investigated in a tissue equivalent thorax phantom using clinical settings and workflow for both standard fractionated radiotherapy (2 Gy) and stereotactic radiotherapy...

Numerical study of chaotic oscillations in the electron beam with virtual cathode in the external non-uniform magnetic fields

Energy Technology Data Exchange (ETDEWEB)

Hramov, Alexander E., E-mail: aeh@nonlin.sgu.r [Faculty of Nonlinear Processes, Saratov State University, 83, Astrakhanskaya, Saratov, 410012 (Russian Federation); Koronovskii, Alexey A., E-mail: alkor@nonlin.sgu.r [Faculty of Nonlinear Processes, Saratov State University, 83, Astrakhanskaya, Saratov, 410012 (Russian Federation); Kurkin, Semen, E-mail: KurkinSA@nonlin.sgu.r [Faculty of Nonlinear Processes, Saratov State University, 83, Astrakhanskaya, Saratov, 410012 (Russian Federation)

2010-07-05

In this Letter the results of theoretical investigations of the chaotic microwave oscillator based on the electron beam with a virtual cathode are presented. Nonlinear non-stationary processes in these electron systems are studied by means of numerical analysis of 2.5D model. It was discovered that the non-uniform external magnetic field value controls the dynamical regime of oscillations in the virtual cathode oscillator. The processes of the chaotization of output microwave radiation are described and interpreted from the point of view of the formation and interaction of electron structures (bunches) in the electron beams. The numerical results have shown that the investigated electron system with virtual cathode could be considered as a promising controlled source of wideband chaotic oscillations in the microwave range.

Determination of the secondary energy from the electron beam with a flattening foil by computer. Percentage depth dose curve fitting using the specific higher order polynomial

Energy Technology Data Exchange (ETDEWEB)

Kawakami, H [Kyushu Univ., Beppu, Oita (Japan). Inst. of Balneotherapeutics

1980-09-01

A computer program written in FORTRAN is described for determining the secondary energy of the electron beam which passed through a flattening foil, using a time-sharing computer service. The procedure of this program is first to fit the specific higher order polynomial to the measured percentage depth dose curve. Next, the practical range is evaluated by the point of intersection R of the line tangent to the fitted curve at the inflection point P and the given dose E, as shown in Fig. 2. Finally, the secondary energy corresponded to the determined practical range can be obtained by the experimental equation (2.1) between the practial range R (g/cm/sup 2/) and the electron energy T (MeV). A graph for the fitted polynomial with the inflection points and the practical range can be plotted on a teletype machine by request of user. In order to estimate the shapes of percentage depth dose curves correspond to the electron beams of different energies, we tried to find some specific functional relationships between each coefficient of the fitted seventh-degree equation and the incident electron energies. However, exact relationships could not be obtained for irreguarity among these coefficients.

SU-E-T-577: Commissioning of a Deterministic Algorithm for External Photon Beams

International Nuclear Information System (INIS)

Zhu, T; Finlay, J; Mesina, C; Liu, H

2014-01-01

Purpose: We report commissioning results for a deterministic algorithm for external photon beam treatment planning. A deterministic algorithm solves the radiation transport equations directly using a finite difference method, thus improve the accuracy of dose calculation, particularly under heterogeneous conditions with results similar to that of Monte Carlo (MC) simulation. Methods: Commissioning data for photon energies 6 – 15 MV includes the percentage depth dose (PDD) measured at SSD = 90 cm and output ratio in water (Spc), both normalized to 10 cm depth, for field sizes between 2 and 40 cm and depths between 0 and 40 cm. Off-axis ratio (OAR) for the same set of field sizes was used at 5 depths (dmax, 5, 10, 20, 30 cm). The final model was compared with the commissioning data as well as additional benchmark data. The benchmark data includes dose per MU determined for 17 points for SSD between 80 and 110 cm, depth between 5 and 20 cm, and lateral offset of up to 16.5 cm. Relative comparisons were made in a heterogeneous phantom made of cork and solid water. Results: Compared to the commissioning beam data, the agreement are generally better than 2% with large errors (up to 13%) observed in the buildup regions of the FDD and penumbra regions of the OAR profiles. The overall mean standard deviation is 0.04% when all data are taken into account. Compared to the benchmark data, the agreements are generally better than 2%. Relative comparison in heterogeneous phantom is in general better than 4%. Conclusion: A commercial deterministic algorithm was commissioned for megavoltage photon beams. In a homogeneous medium, the agreement between the algorithm and measurement at the benchmark points is generally better than 2%. The dose accuracy for a deterministic algorithm is better than a convolution algorithm in heterogeneous medium

Non-rigid CT/CBCT to CBCT registration for online external beam radiotherapy guidance

Science.gov (United States)

Zachiu, Cornel; de Senneville, Baudouin Denis; Tijssen, Rob H. N.; Kotte, Alexis N. T. J.; Houweling, Antonetta C.; Kerkmeijer, Linda G. W.; Lagendijk, Jan J. W.; Moonen, Chrit T. W.; Ries, Mario

2018-01-01

Image-guided external beam radiotherapy (EBRT) allows radiation dose deposition with a high degree of accuracy and precision. Guidance is usually achieved by estimating the displacements, via image registration, between cone beam computed tomography (CBCT) and computed tomography (CT) images acquired at different stages of the therapy. The resulting displacements are then used to reposition the patient such that the location of the tumor at the time of treatment matches its position during planning. Moreover, ongoing research aims to use CBCT-CT image registration for online plan adaptation. However, CBCT images are usually acquired using a small number of x-ray projections and/or low beam intensities. This often leads to the images being subject to low contrast, low signal-to-noise ratio and artifacts, which ends-up hampering the image registration process. Previous studies addressed this by integrating additional image processing steps into the registration procedure. However, these steps are usually designed for particular image acquisition schemes, therefore limiting their use on a case-by-case basis. In the current study we address CT to CBCT and CBCT to CBCT registration by the means of the recently proposed EVolution registration algorithm. Contrary to previous approaches, EVolution does not require the integration of additional image processing steps in the registration scheme. Moreover, the algorithm requires a low number of input parameters, is easily parallelizable and provides an elastic deformation on a point-by-point basis. Results have shown that relative to a pure CT-based registration, the intrinsic artifacts present in typical CBCT images only have a sub-millimeter impact on the accuracy and precision of the estimated deformation. In addition, the algorithm has low computational requirements, which are compatible with online image-based guidance of EBRT treatments.

Doughnut laser beam as an incoherent superposition of two petal beams

CSIR Research Space (South Africa)

Litvin, IA

2014-02-01

Full Text Available Laguerre–Gaussian beams with a nonzero azimuthal index are known to carry orbital angular momentum (OAM), and are routinely created external to laser cavities. The few reports of obtaining such beams from laser cavities suffer from inconclusive...

New ICRU quantities for the environmental and individual monitoring. Standardization of individual dosemeters by using external beams of photon radiation

International Nuclear Information System (INIS)

Brosed, A.; Delgado, A.; Granados, C. E.

1987-01-01

The quantities introduced by ICRU for the radiological monitoring are commented, specially those implied in individual protection against external photons. A procedure is proposed in order to standardize the individual dosemeters by using the kerma in air references of CIEMAT-JEN. The reference radiation beams are described in connection with ISO standards. Provisional values are selected for the appropriate conversion and correction factors. (Author) 23 refs

Low-dose-rate intraoperative brachytherapy combined with external beam irradiation in the conservative treatment of soft tissue sarcoma

International Nuclear Information System (INIS)

Delannes, M.; Thomas, L.; Martel, P.; Bonnevialle, P.; Stoeckle, E.; Chevreau, Ch.; Bui, B.N.; Daly-Schveitzer, N.; Pigneux, J.; Kantor, G.

2000-01-01

Purpose: Conservative treatment of soft tissue sarcomas most often implies combination of surgical resection and irradiation. The aim of this study was to evaluate low-dose-rate intraoperative brachytherapy, delivered as a boost, in the local control of primary tumors, with special concern about treatment complications. Methods and Materials: Between 1986 and 1995, 112 patients underwent intraoperative implant. This report focuses on the group of 58 patients with primary sarcomas treated by combination of conservative surgery, intraoperative brachytherapy, and external irradiation. Most of the tumors were located in the lower limbs (46/58--79%). Median size of the tumor was 10 cm, most of the lesions being T2-T3 (51/58--88%), Grade 2 or 3 (48/58--83%). The mean brachytherapy dose was 20 Gy and external beam irradiation dose 45 Gy. In 36/58 cases, iridium wires had to be placed on contact with neurovascular structures. Results: With a median follow-up of 54 months, the 5-year actuarial survival was 64.9%, with a 5-year actuarial local control of 89%. Of the 6 patients with local relapse, 3 were salvaged. Acute side effects, essentially wound healing problems, occurred in 20/58 patients, late side effects in 16/58 patients (7 neuropathies G2 to G4). No amputation was required. The only significant factor correlated with early side effects was the location of the tumor in the lower limb (p = 0.003), and with late side effects the vicinity of the tumor with neurovascular structures (p = 0.009). Conclusion: Brachytherapy allows early delivery of a boost dose in a reduced volume of tissue, precisely mapped by the intraoperative procedure. Combined with external beam irradiation, it is a safe and efficient treatment technique leading to high local control rates and limited functional impairment

Introduction of beam flatness filter for 60Co teletherapy beam and its efficacy in clinical radiotherapy

International Nuclear Information System (INIS)

Sathiyan, S.; Ravichandran, R.; Ravikumar, M.

2003-01-01

In the western countries cobalt-60 machines have become obsolete, whereas in India we have about 250 machines operational for clinical radiotherapy. The basic differences of 6 MV x-ray beam and cobalt-60 beam are: a) build-up d max point, b) flatness of beam at depths, and c) sharpness of the beam edge. We looked at the homogeneity of delivered dose in the target volume in a 3 field SAD technique for 60 Co (80 cm, 100 cm) and 6 MV treatments. More dose variations are seen in 60 Co treated volume. The excess curvature of isodose curves of 60 Co at depths may be one of the reasons for this inhomogeneity in dose to target volume. Therefore, there is need for achieving perfect flatness in the isodose curves at desired depths. A flattening filter was fabricated using dental wax impression material to account for depths of curvature of 50% 60 Co isodose curve. The filter was fabricated for the Theratron 780C machine for necessary flatness. The beam flatness with filter was measured with a) ionization and b) TL dosimetry methods. The flattened beam profile was compared with 6 MV x-ray beam (Clinac-1800, M/s Varian, USA). Our measurements show uniform flatness of cobalt-60 isodose curve at desired depth and useful radiation field width comparable to 6 MV x-ray photon profile at full width at half maximum (FWHM). If this concept is extendable to short field widths, it appears that there is scope for use of such filter in the treatments of oesophagus, larynx, and pituitary tumours to achieve dose homogeneity. Using this flatness filter and penumbra trimmer, we may achieve better quality cobalt-60 beam for radiotherapy. (author)

WE-F-16A-05: Use of 3D-Printers to Create a Tissue Equivalent 3D-Bolus for External Beam Therapy

Energy Technology Data Exchange (ETDEWEB)

Burleson, S; Baker, J; Hsia, A; Xu, Z [Stony Brook Medicine, Stony Brook, NY (United States)

2014-06-15

Purpose: The purpose of this project is to demonstrate that a non-expensive 3D-printer can be used to manufacture a 3D-bolus for external beam therapy. The printed bolus then can be modeled in our treatment planning system to ensure accurate dose delivery to the patient. Methods: We developed a simple method to manufacture a patient-specific custom 3Dbolus. The bolus is designed using Eclipse Treatment Planning System, contoured onto the patients CT images. The bolus file is exported from Eclipse to 3D-printer software, and then printed using a 3D printer. Various tests were completed to determine the properties of the printing material. Percent depth dose curves in this material were measured with electron and photon beams for comparison to other materials. In order to test the validity of the 3D printed bolus for treatment planning, a custom bolus was printed and tested on the Rando phantom using film for a dose plane comparison. We compared the dose plane measured on the film to the same dose plane exported from our treatment planning system using Film QA software. The gamma-dose distribution tool was used in our film analysis. Results: We compared point measurements throughout the dose plane and were able to achieve greater than 95% passing rate at 3% dose difference and 3 mm distance to agreement, which is our departments acceptable gamma pixel parameters. Conclusion: The printed 3D bolus has proven to be accurately modeled in our treatment planning system, it is more conformal to the patient surface and more durable than other bolus currently used (wax, superflab etc.). It is also more convenient and less costly than comparable bolus from milling machine companies.

WE-F-16A-05: Use of 3D-Printers to Create a Tissue Equivalent 3D-Bolus for External Beam Therapy

International Nuclear Information System (INIS)

Burleson, S; Baker, J; Hsia, A; Xu, Z

2014-01-01

Purpose: The purpose of this project is to demonstrate that a non-expensive 3D-printer can be used to manufacture a 3D-bolus for external beam therapy. The printed bolus then can be modeled in our treatment planning system to ensure accurate dose delivery to the patient. Methods: We developed a simple method to manufacture a patient-specific custom 3Dbolus. The bolus is designed using Eclipse Treatment Planning System, contoured onto the patients CT images. The bolus file is exported from Eclipse to 3D-printer software, and then printed using a 3D printer. Various tests were completed to determine the properties of the printing material. Percent depth dose curves in this material were measured with electron and photon beams for comparison to other materials. In order to test the validity of the 3D printed bolus for treatment planning, a custom bolus was printed and tested on the Rando phantom using film for a dose plane comparison. We compared the dose plane measured on the film to the same dose plane exported from our treatment planning system using Film QA software. The gamma-dose distribution tool was used in our film analysis. Results: We compared point measurements throughout the dose plane and were able to achieve greater than 95% passing rate at 3% dose difference and 3 mm distance to agreement, which is our departments acceptable gamma pixel parameters. Conclusion: The printed 3D bolus has proven to be accurately modeled in our treatment planning system, it is more conformal to the patient surface and more durable than other bolus currently used (wax, superflab etc.). It is also more convenient and less costly than comparable bolus from milling machine companies

A nonlinear beam model to describe the postbuckling of wide neo-Hookean beams

Science.gov (United States)

Lubbers, Luuk A.; van Hecke, Martin; Coulais, Corentin

2017-09-01

Wide beams can exhibit subcritical buckling, i.e. the slope of the force-displacement curve can become negative in the postbuckling regime. In this paper, we capture this intriguing behaviour by constructing a 1D nonlinear beam model, where the central ingredient is the nonlinearity in the stress-strain relation of the beams constitutive material. First, we present experimental and numerical evidence of a transition to subcritical buckling for wide neo-Hookean hyperelastic beams, when their width-to-length ratio exceeds a critical value of 12%. Second, we construct an effective 1D energy density by combining the Mindlin-Reissner kinematics with a nonlinearity in the stress-strain relation. Finally, we establish and solve the governing beam equations to analytically determine the slope of the force-displacement curve in the postbuckling regime. We find, without any adjustable parameters, excellent agreement between the 1D theory, experiments and simulations. Our work extends the understanding of the postbuckling of structures made of wide elastic beams and opens up avenues for the reverse-engineering of instabilities in soft and metamaterials.

Multistage Coupling of Laser-Wakefield Accelerators with Curved Plasma Channels

Science.gov (United States)

Luo, J.; Chen, M.; Wu, W. Y.; Weng, S. M.; Sheng, Z. M.; Schroeder, C. B.; Jaroszynski, D. A.; Esarey, E.; Leemans, W. P.; Mori, W. B.; Zhang, J.

2018-04-01

Multistage coupling of laser-wakefield accelerators is essential to overcome laser energy depletion for high-energy applications such as TeV-level electron-positron colliders. Current staging schemes feed subsequent laser pulses into stages using plasma mirrors while controlling electron beam focusing with plasma lenses. Here a more compact and efficient scheme is proposed to realize the simultaneous coupling of the electron beam and the laser pulse into a second stage. A partly curved channel, integrating a straight acceleration stage with a curved transition segment, is used to guide a fresh laser pulse into a subsequent straight channel, while the electrons continue straight. This scheme benefits from a shorter coupling distance and continuous guiding of the electrons in plasma while suppressing transverse beam dispersion. Particle-in-cell simulations demonstrate that the electron beam from a previous stage can be efficiently injected into a subsequent stage for further acceleration while maintaining high capture efficiency, stability, and beam quality.

Intraoperative plus external beam irradiation in nonresectable lung cancer

International Nuclear Information System (INIS)

Arian-Schad, K.S.; Juettner, F.M.; Ratzenhofer, B.; Leitner, H.; Porsch, G.; Pinter, H.; Ebner, F.; Hackl, A.G.; Friehs, G.B.

1990-01-01

Since 1987, 24 patients with inoperable non-small-cell lung cancer (NSCLC), stage T 1-3 N 0-2 M 0 , have undergone lymph node dissection and intraoperative radiation therapy (IORT) to the primary with 10-20 Gy. Patient selection criteria were nonresectability based on severe cardiorespiratory impairment, no radiological evidence of distant metastases and a Karnofsky performance status of >80. In 18 patients the IORT procedure was followed by an external beam radiation series (EBR) including the tumor with 46 Gy and the regional lymph nodes with 45/56 Gy. The tumor response was assessed by CAT-scan volumetry before the institution of IORT, 4 weeks later, before the onset of EBR, 8 weeks after the combined treatment course and on a 3 months basis thereafter. Prospectively, MRI of the thorax with/without Gadolinium-DTPA was performed to examine contrast enhancement and signal behavior of the tumor, in an attempt to differentiate residual disease compared to therapy-related collateral damage. So far, 18 patients have completed the combined treatment course with a median follow-up of 11 months (range 4.5 to 25 months). The overall local response rate (CR and PR) was 88.2 per cent. In detail, 11 complete responses, 6 partial responses and one minimal response were observed. The overall and recurrent-free survival at 25 months was 49.6 per cent and 83.3 per cent, respectively. (author). 31 refs.; 2 figs.; 3 tabs

Beam properties and stability of a flattening-filter free 7 MV beam--An overview

International Nuclear Information System (INIS)

Dzierma, Yvonne; Licht, Norbert; Nuesken, Frank; Ruebe, Christian

2012-01-01

Purpose: Several works have recently focused on flattening-filter-free (FFF) beams of linear accelerators of various companies (in particular, Varian and Elekta), but no overview as yet exists for the flattening-filter free 7XU beam (Siemens Artiste). Methods: Dosimetric properties of the 7XU beam were measured in May and September 2011. We present depth dose curves and beam profiles, output factors, and MLC transmission and assess the stability of the measurements. The 7XU beam was commissioned in the Pinnacle³ treatment planning system (TPS), and modeling results including the spectrum are presented. Results: The percent depth dose curve of the 7XU beam is similar to the flat 6X beam line, with a slightly smaller surface dose. The beam profiles show the characteristic shape of flattening-filter free beams, with deviations between measurements of generally less than 1%. The output factors of the 7XU beam decrease more slowly than for the 6X beam. The MLC transmission is comparable but slightly less for the 7XU beam. The 7XU beam can be adequately modeled by the Pinnacle³ TPS, with successful dosimetric verification. The spectrum of the 7XU beam has lower photon fluence up to approximately 2.5 MeV and higher fluence beyond, with a slightly higher mean energy. Conclusions: The 7XU beam has been commissioned for clinical use after successful modeling, stability checks, and dosimetric verification.

Self-Nulling Beam Combiner Using No External Phase Inverter

Science.gov (United States)

Bloemhof, Eric E.

2010-01-01

A self-nulling beam combiner is proposed that completely eliminates the phase inversion subsystem from the nulling interferometer, and instead uses the intrinsic phase shifts in the beam splitters. Simplifying the flight instrument in this way will be a valuable enhancement of mission reliability. The tighter tolerances on R = T (R being reflection and T being transmission coefficients) required by the self-nulling configuration actually impose no new constraints on the architecture, as two adaptive nullers must be situated between beam splitters to correct small errors in the coatings. The new feature is exploiting the natural phase shifts in beam combiners to achieve the 180 phase inversion necessary for nulling. The advantage over prior art is that an entire subsystem, the field-flipping optics, can be eliminated. For ultimate simplicity in the flight instrument, one might fabricate coatings to very high tolerances and dispense with the adaptive nullers altogether, with all their moving parts, along with the field flipper subsystem. A single adaptive nuller upstream of the beam combiner may be required to correct beam train errors (systematic noise), but in some circumstances phase chopping reduces these errors substantially, and there may be ways to further reduce the chop residuals. Though such coatings are beyond the current state of the art, the mechanical simplicity and robustness of a flight system without field flipper or adaptive nullers would perhaps justify considerable effort on coating fabrication.

Californium-252 Brachytherapy Combined With External-Beam Radiotherapy for Cervical Cancer: Long-Term Treatment Results

International Nuclear Information System (INIS)

Lei Xin; Qian Chengyuan; Qing Yi; Zhao Kewei; Yang Zhengzhou; Dai Nan; Zhong Zhaoyang; Tang Cheng; Li Zheng; Gu Xianqing; Zhou Qian; Feng Yan; Xiong Yanli; Shan Jinlu; Wang Dong

2011-01-01

Purpose: To observe, by retrospective analysis, the curative effects and complications due to californium-252 ( 252 Cf) neutron intracavitary brachytherapy (ICBT) combined with external-beam radiotherapy (EBRT) in the treatment of cervical cancer. Methods and Materials: From February 1999 to December 2007, 696 patients with cervical cancer (Stages IB to IIIB) were treated with 252 Cf-ICBT in combination of EBRT. Of all, 31 patients were at Stage IB, 104 at IIA, 363 at IIB, 64 at IIIA, and 134 at IIIB. Californium-252 ICBT was delivered at 7–12 Gy per insertion per week, with a total dose of 29–45 Gy to reference point A in three to five insertions. The whole pelvic cavity was treated with 8-MV X-ray external irradiation at 2 Gy per fraction, four times per week. After 16–38 Gy of external irradiation, the center of the whole pelvic field was blocked with a 4-cm-wide lead shield, with a total external irradiation dose of 44–56 Gy. The total treatment course was 5 to 6 weeks. Results: Overall survival rate at 3 and 5 years for all patients was 76.0% and 64.9%, respectively. Disease-free 3- and 5-year survival rates of patients were 71.2% and 58.4%, respectively. Late complications included vaginal contracture and adhesion, radiation proctitis, radiation cystitis, and inflammatory bowel, which accounted for 5.8%, 7.1%, 6.2%, and 4.9%, respectively. Univariate analysis results showed significant correlation of stage, age, histopathologic grade, and lymph node status with overall survival. Cox multiple regression analysis showed that the independent variables were stage, histopathologic grade, tumor size, and lymphatic metastasis in all patients. Conclusion: Results of this series suggest that the combined use of 252 Cf-ICBT with EBRT is an effective method for treatment of cervical cancer.

Ion-beam plasma and propagation of intense compensated ion beams

Energy Technology Data Exchange (ETDEWEB)

Gabovich, M D [AN Ukrainskoj SSR, Kiev. Inst. Fiziki

1977-02-01

Discussed are the results of investigation of plasma properties received by neutralization of intense ion beam space charge. Considered is the process of ion beam compensation by charges, formed as a result of gas ionization by this beam or by externally introduced ones. Emphasis is placed on collective phenomena in ion-beam plasma, in particular on non-linear effects limiting amplitude of oscillations. It is shown that not only dynamic decompensation but the Coulomb collisions of ions with electrons as well as other collective oscillations significantly affects the propagation of compensated ion beams. All the processes are to be taken into account in solving the problem of obtaining ''superdense'' compensated beams.

Ion-beam plasma and propagation of intense compensated ion beams

International Nuclear Information System (INIS)

Gabovich, M.D.

1977-01-01

Discussed are the results of investigation of plasma properties recieved by neutralization of intensive ion beam space charge. Considered is the process of ion beam compensation by charges, formed as a result of gas ionization by this beam or by externally introduced ones. Emphasis is placed on collective phenomena in ion-beam plasma, in particular on non-linear effects limiting amplitude of oscillations. It is shown, that not only dinamic decompensation but the Coulomb collisions of ions with electrons as well as other collective oscillations significantly affects the propagation of compensated ion beams. All the processes are to be taken into account at solving the problem of obtaining ''superdense'' compensated beams

A simple Lissajous curves experimental setup

Science.gov (United States)

Şahin Kızılcık, Hasan; Damlı, Volkan

2018-05-01

The aim of this study is to develop an experimental setup to produce Lissajous curves. The setup was made using a smartphone, a powered speaker (computer speaker), a balloon, a laser pointer and a piece of mirror. Lissajous curves are formed as follows: a piece of mirror is attached to a balloon. The balloon is vibrated with the sound signal provided by the speaker that is connected to a smartphone. The laser beam is reflected off the mirror and the reflection is shaped as a Lissajous curve. Because of the intersection of two frequencies (frequency of the sound signal and natural vibration frequency of the balloon), these curves are formed. They can be used to measure the ratio of frequencies.

External beam radiotherapy for head and neck carcinomas with preservation of parotid function: indications, techniques and long term results

International Nuclear Information System (INIS)

Ding-Jen, Lee; Fairbanks, Robert; Lee, Frank C.

1995-01-01

Purpose/Objective: To reduce the incidence of radiotherapy induced xerostomia, we developed techniques of external beam irradiation with preservation of parotid function for patients with early to intermediate stage carcinomas of the head and neck. This analysis reports the efficacy of our methods. Materials and Methods: From 1985 to 1993, 42 patients with early to intermediate stage (T 1-3 N 0-2 M 0 ) head and neck carcinomas received a course of external beam radiotherapy. There were 13 patients with carcinoma of the oropharynx, 26 with carcinomas of the oral cavity and 3 with carcinomas of the hypopharynx (lateral wall). 7 patients received a course of definitive radiotherapy (66 to 72 Gy), while 35 patients received a course of postoperative radiotherapy (60-66 Gy). The fraction size was 2 Gy per day. In terms of treatment planning, the primary site (plus a margin) and the ipsilateral neck were covered by the irradiation volume. The ipsilateral parotid gland was within the treatment volume while the contralateral parotid gland was not. The most frequently used field arrangement was a paired wedge fields with an AP (medially just across the mid-line) and an ipsilateral posterior oblique field (usually 30 deg. off vertical axis with a spinal cord block). Multiple level of contours were taken and transmission blocks were used to improve dose homogeneity. In all patients, the ipsilateral parotid gland (and the neck) was irradiated while the contralateral parotid gland (and the neck) was not. Results: With a median follow up of 4 years (ranged from 1.5 to 9 years), only one patient developed symptomatic xerostomia. None had radiation induced dental caries. No patient developed recurrent disease in the contralateral neck. The local control rate was (38(42)) (90%) in the primary site and(41(42)) (98%) in the ipsilateral neck. Conclusion: With appropriate treatment planning, external beam irradiation with parotid function preservation can be achieved. Our results

The development of an interdepartmental audit as part of a physics quality assurance programme for external beam therapy

International Nuclear Information System (INIS)

Bonnett, D.E.; Jaukett, R.J.; Mills, J.A.; Martin-Smith, P.

1994-01-01

A cost-effective audit system has been developed that will both detect systematic error in data and procedures, and evaluate the quality assurance programme provided by a physics department for radiotherapy. The audit has been developed for external beam radiotherapy and assesses one modality and one treatment machine per year. The method of assessing the quality assurance programme and the schedule of measurements are described. The process is illustrated using the results of trial audits between the medical physics department at Coventry and Leicester. (author)

MD 400: LHC emittance growth in presence of an external source of noise during collision

CERN Document Server

Barranco Garcia, Javier; Pieloni, Tatiana; Tambasco, Claudia; Trad, Georges; Valuch, Daniel; Betz, Michael; Wendt, Manfred; Pojer, Mirko; Solfaroli Camillocci, Matteo; Salvachua Ferrando, Belen Maria; Fuchsberger, Kajetan; Albert, Markus; Qiang, Ji; CERN. Geneva. ATS Department

2016-01-01

The interplay between head-on beam-beam interaction and external sources of noise can be a significant source of emittance growth, especially when considering large beam-beam tune shifts as for the HL-LHC upgrade project. In this experiment the emittance growth of colliding bunches with different brightness and therefore different beam-beam parameters in the presence of an external white noise source with different amplitudes is measured for different gains of the transverse feedback.

Successful treatment of a 67-year-old woman with urethral adenocarcinoma with the use of external beam radiotherapy and image guided adaptive interstitial brachytherapy

DEFF Research Database (Denmark)

Mujkanovic, Jasmin; Tanderup, Kari; Agerbæk, Mads

2016-01-01

Primary urethral cancer (PUC) is a very rare disease. This case report illustrates a successful treatment approach of a 67-year-old woman with a urethral adenocarcinoma selected for an organ preserving treatment with external beam radiotherapy (EBRT) and interstitial brachytherapy (BT) boost, using...

Locally advanced prostatic cancer: experience with combined pelvic external beam irradiation and interstitial thermobrachytherapy

Energy Technology Data Exchange (ETDEWEB)

Hancock, Steven L; Kapp, Daniel S; Goffinet, Don R; Prionas, Stavros; Cox, Richard S; Bagshaw, Malcolm A

1995-07-01

Purpose: Recurrence of prostatic carcinoma within the prostate gland remains a significant problem for patients who present with locally advanced disease. In an attempt to improve the local control of such tumors, an iridium-192 transperineal, template-guided prostatic implant was combined wit radiofrequency-induced hyperthermia after external beam irradiation of the pelvic lymph nodes and prostate gland. This study evaluates the influence of pre-treatment patient characteristics and treatment parameters upon outcome. Materials and Methods: Between July 1987 and April 1992 33 patients with adenocarcinoma of the prostate were selected for treatment: 28 of these patients had extensive local disease on clinical examination (AJCC-4 stages T2b or c: 9 patients; T3: 19 patients); two patients with T2a tumors had Gleason grade 5 + 4 disease or disproportionately high prostate specific antigen (PSA) values and a mass encroaching upon the bladder on computerized tomographic scan. Three patients with more clinically limited T2a or T2b involvement elected implantation in lieu of an external beam irradiation boost. The mean pre-treatment serum PSA value was 25.6 ng/ml (Hybritech scale), with values of above 19 ng/ml for 17 of the patients. Treatment consisted of 50 Gy of external beam irradiation to the prostate and pelvic lymph nodes followed by a transperineal needle implant of the prostate gland. Thirty-two patients had no evidence of pelvic nodal involvement during exploration at laparotomy performed after external irradiation, and 25 of these had lymph node samplings that were histologically negative for metastasis. Perineal template oriented needles were placed by inspection and palpation at laparotomy; 2 were performed closed under ultrasound guidance. Needles were afterloaded with {sup 192}Ir to provide a dose of 30 Gy to the periphery of the prostate gland. Interstitial radiofrequency-induced hyperthermia treatments were given in conjunction with the implant, one just

Intraoperative electron beam radiation therapy (IOEBRT) for carcinoma of the exocrine pancreas

International Nuclear Information System (INIS)

Dobelbower, R.R. Jr.; Konski, A.A.; Merrick, H.W. III; Bronn, D.G.; Schifeling, D.; Kamen, C.

1991-01-01

The abdominal cavities of 50 patients were explored in a specially constructed intraoperative radiotherapy operating amphitheater at the Medical College of Ohio. Twenty-six patients were treated with intraoperative and postoperative precision high dose external beam therapy, 12 with intraoperative irradiation but no external beam therapy, and 12 with palliative surgery alone. All but two patients completed the postoperative external beam radiation therapy as initially prescribed. The median survival time for patients treated with palliative surgery alone was 4 months, and that for patients treated with intraoperative radiotherapy without external beam therapy was 3.5 months. Patients undergoing intraoperative irradiation and external beam radiation therapy had a median survival time of 10.5 months. Four patients died within 30 days of surgery and two patients died of gastrointestinal hemorrhage 5 months posttreatment

Mid-infrared PbTe vertical external cavity surface emitting laser on Si-substrate with above 1 W output power

Science.gov (United States)

Rahim, M.; Fill, M.; Felder, F.; Chappuis, D.; Corda, M.; Zogg, H.

2009-12-01

Mid-infrared vertical external cavity surface emitting lasers (VECSELs) emitting above 1 W output power in pulsed mode and up to 17 mW in continuous mode at -172 °C were realized. Emission wavelength changes from 5 μm at -172 °C to 3.6 μm at 20 °C heat sink temperature. The active medium is a one wavelength thick PbTe layer grown by molecular beam epitaxy on a Si-substrate. It is followed by a 2.5 pair Pb1-yEuyTe/EuTe epitaxial Bragg mirror. The cavity is completed with an external curved Pb1-yEuyTe/BaF2 mirror. The VECSEL is optically pumped with 1.55 μm wavelength laser and In-soldered to Cu heat sink. No microstructural processing is needed.

Phenomenological studies of electron-beam transport in wire-plasma channels

International Nuclear Information System (INIS)

Lockwood, G.J.; Beezhold, W.

1980-01-01

Multiple electron-beam transport in air through plasma channels is an important method for delivering many intense beams to a bremsstrahlung converter system. This paper reports work intended to optimize this transport technique with emphasis on transport through curved channels and on transport efficiencies. Curved-channel transport allows accelerators such as Sandia's PROTO II and PBFA I facilities to be used as flash x-ray sources for weapon effects simulation without reconfiguring the diodes or developing advanced converters. The formation mechanisms of wire-initiated plasma channels in air were examined and the subsequent transport efficiencies of relativistic electron beams through various-length straight and curved plasma channels were determined. Electron transport efficiency through a channel was measured to be 80 to 100% of a zero length channel for 40 cm long straight channels and for curved channels which re-directed the electron beam through an angle of 90 0 . Studies of simultaneous e-beam transport along two curved channels closely spaced at the converter showed that transport efficiency remained at 80 to 100%. However, it was observed that the two e-beams were displaced towards each other. Transport efficiency was observed to depend only weakly on parameters such as wire material, wire length and shape, diode anode aperture, e-beam injection time, and wire-channel applied voltage. For off-center injection conditions the electron beam strongly perturbed the plasma channel in periodic or regularly spaced patterns even though the total energy lost by the electron beam remained small. Plasma-channel transport, when all experimental parameters have been optimized for maximum transport efficiency, is a workable method for directing electron beams to a converter target

Leaflet manual of external beam radiation therapy for hepatocellular carcinoma: a review of the indications, evidences, and clinical trials

Directory of Open Access Journals (Sweden)

Rim CH

2018-05-01

Full Text Available Chai Hong Rim, Won Sup Yoon Department of Radiation Oncology, Ansan Hospital, Korea University Medical College, Ansan, Republic of Korea Abstract: The use of external beam radiation therapy (EBRT in the treatment of hepatocellular carcinoma (HCC, which was rarely performed due to liver toxicity with a previous technique, has increased. Palliation of portal vein thrombosis, supplementation for insufficient transarterial chemoembolization, and provision of new curative opportunities using stereotactic body radiotherapy are the potential indications for use of EBRT. The mechanism of EBRT treatment, with its radiobiological and physical perspectives, differs from those of conventional medical treatment or surgery. Therefore, understanding the effects of EBRT may be unfamiliar to physicians other than radiation oncologists, especially in the field of HCC, where EBRT has recently begun to be applied. The first objective of this review was to concisely explain the indications for use of EBRT for HCC for all physicians treating HCC. Therefore, this review focuses on the therapeutic outcomes rather than the detailed biological and physical background. We also reviewed recent clinical trials that may extend the indications for use of EBRT. Finally, we reviewed the current clinical practice guidelines for the treatment of HCC and discuss the current recommendations and future perspectives. Keywords: hepatocellular carcinoma, liver neoplasm, external beam radiotherapy, stereotactic body radiotherapy, clinical trials, sorafenib, guidelines

Buckling Capacity Curves for Steel Spherical Shells Loaded by the External Pressure

Science.gov (United States)

Błażejewski, Paweł; Marcinowski, Jakub

2015-03-01

Assessment of buckling resistance of pressurised spherical cap is not an easy task. There exist two different approaches which allow to achieve this goal. The first approach involves performing advanced numerical analyses in which material and geometrical nonlinearities would be taken into account as well as considering the worst imperfections of the defined amplitude. This kind of analysis is customarily called GMNIA and is carried out by means of the computer software based on FEM. The other, comparatively easier approach, relies on the utilisation of earlier prepared procedures which enable determination of the critical resistance pRcr, the plastic resistance pRpl and buckling parameters a, b, h, l 0 needed to the definition of the standard buckling resistance curve. The determination of the buckling capacity curve for the particular class of spherical caps is the principal goal of this work. The method of determination of the critical pressure and the plastic resistance were described by the authors in [1] whereas the worst imperfection mode for the considered class of spherical shells was found in [2]. The determination of buckling parameters defining the buckling capacity curve for the whole class of shells is more complicated task. For this reason the authors focused their attention on spherical steel caps with the radius to thickness ratio of R/t = 500, the semi angle j = 30o and the boundary condition BC2 (the clamped supporting edge). Taking into account all imperfection forms considered in [2] and different amplitudes expressed by the multiple of the shell thickness, sets of buckling parameters defining the capacity curve were determined. These parameters were determined by the methods proposed by Rotter in [3] and [4] where the method of determination of the exponent h by means of additional parameter k was presented. As a result of the performed analyses the standard capacity curves for all considered imperfection modes and amplitudes 0.5t, 1.0t, 1.5t

Palliative external-beam radiotherapy for bone metastases from hepatocellular carcinoma

Institute of Scientific and Technical Information of China (English)

Shinya; Hayashi; Hidekazu; Tanaka; Hiroaki; Hoshi

2014-01-01

The incidence of bone metastases(BMs)from hepatocellular carcinoma(HCC)is relatively low compared to those of other cancers,but it has increased recently,especially in Asian countries.Typically,BMs from HCC appear radiologically as osteolytic,destructive,and expansive components with large,bulky soft-tissue masses.These soft-tissue masses are unique to bone metastases from HCC and often replace the normal bone matrix and exhibit expansive growth.They often compress the peripheral nerves,spinal cord,or cranial nerves,causing not only bone pain but also neuropathic pain and neurological symptoms.In patients with spinal BMs,the consequent metastatic spinal cord compression(MSCC)causes paralysis.Skull base metastases(SBMs)with cranial nerve involvement can cause neurological symptoms.Therefore,patients with bony lesions often suffer from pain or neurological symptoms that have a severe,adverse effect on the quality of life.External-beam radiotherapy(EBRT)can effectively relieve bone pain and neurological symptoms caused by BMs.However,EBRT is not yet widely used for the palliative management of BMs from HCC because of the limited number of relevant studies.Furthermore,the optimal dosing schedule remains unclear,despite clinical evidence to support single-fraction ra-diation schedules for primary cancers.In this review,we outline data describing palliative EBRT for BMs from HCC in the context of(1)bone pain;(2)MSCC;and(3)SBMs.

Absorbed dose determination in external beam radiotherapy. An international code of practice for dosimetry based on standards of absorbed dose to water

International Nuclear Information System (INIS)

2000-01-01

The International Atomic Energy Agency published in 1987 an International Code of Practice entitled 'Absorbed Dose Determination in Photon and Electron Beams' (IAEA Technical Reports Series No. 277 (TRS-277)), recommending procedures to obtain the absorbed dose in water from measurements made with an ionization chamber in external beam radiotherapy. A second edition of TRS-277 was published in 1997 updating the dosimetry of photon beams, mainly kilovoltage X rays. Another International Code of Practice for radiotherapy dosimetry entitled 'The Use of Plane-Parallel Ionization Chambers in High Energy Electron and Photon Beams' (IAEA Technical Reports Series No. 381 (TRS-381)) was published in 1997 to further update TRS-277 and complement it with respect to the area of parallel-plate ionization chambers. Both codes have proven extremely valuable for users involved in the dosimetry of the radiation beams used in radiotherapy. In TRS-277 the calibration of the ionization chambers was based on primary standards of air kerma; this procedure was also used in TRS-381, but the new trend of calibrating ionization chambers directly in a water phantom in terms of absorbed dose to water was introduced. The development of primary standards of absorbed dose to water for high energy photon and electron beams, and improvements in radiation dosimetry concepts, offer the possibility of reducing the uncertainty in the dosimetry of radiotherapy beams. The dosimetry of kilovoltage X rays, as well as that of proton and heavy ion beams, interest in which has grown considerably in recent years, can also be based on these standards. Thus a coherent dosimetry system based on standards of absorbed dose to water is possible for practically all radiotherapy beams. Many Primary Standard Dosimetry Laboratories (PSDLs) already provide calibrations in terms of absorbed dose to water at the radiation quality of 60 Co gamma rays. Some laboratories have extended calibrations to high energy photon and

External Beam Radiotherapy for Colon Cancer: Patterns of Care

International Nuclear Information System (INIS)

Dunn, Emily F.; Kozak, Kevin R.; Moody, John S.

2010-01-01

Purpose: Despite its common and well characterized use in other gastrointestinal malignancies, little is known about radiotherapy (RT) use in nonmetastatic colon cancer in the United States. To address the paucity of data regarding RT use in colon cancer management, we examined the RT patterns of care in this patient population. Methods and Materials: Patients with nonmetastatic colon cancer, diagnosed between 1988 and 2005, were identified in the Surveillance, Epidemiology, and End Results (SEER) database. Univariate and multivariate methods were used to identify factors associated with RT use. Results: On univariate analysis, tumor location, age, sex, race, T stage, N stage, and geographic location were each associated with differences in RT use (all p < 0.01). In general, younger patients, male patients, and patients with more advanced disease were more likely to receive RT. On multivariate analysis, tumor location, age, gender, T and N stage, time of diagnosis and geographic location were significantly associated with RT use (all p < 0.001). Race, however, was not associated with RT use. On multivariate analysis, patients diagnosed in 1988 were 2.5 times more likely to receive RT than those diagnosed in 2005 (p = 0.001). Temporal changes in RT use reflect a responsiveness to evolving evidence related to the therapeutic benefits of adjuvant RT. Conclusions: External beam RT is infrequently used for colon cancer, and its use varies according to patient and tumor characteristics. RT use has declined markedly since the late 1980s; however, it continues to be used for nonmetastatic disease in a highly individualized manner.

Cracking of Beams Strengthened with Externally Bonded SRP Tapes

Science.gov (United States)

Krzywoń, Rafał

2017-10-01

Paper discusses strengthening efficiency of relatively new kind of SRP composite based on high strength steel wires. They are made of ultra-high strength steel primarily used in cords of car tires. Through advanced treatment, the mechanical properties of SRP steel are similar to other high carbon cold drawn steels used in construction industry. Strength significantly exceed 2000 MPa, there is no perfect plasticity at yield stress level. Almost linear stress-strain relationship makes SRP steel mechanical properties similar to carbon fibers. Also flexibility and weight ratio of the composite overlay is slightly worse than CFRP strip. Despite these advantages SRP is not as popular as other composites reinforced with fibers of high strength. This is due to the small number of studies of SRP behavior and applicability. Paper shows selected results of the laboratory test of beams strengthened with use of SRP and CFRP externally bonded overlays. Attention has been focused primarily on the phenomenon of cracking. Comparison include the cracking moment, crack width and spacing, coverage of crack zone. Despite the somewhat lower rigidity of SRP tapes, they have a much better adhesion to concrete, so that the crack width is comparable in almost the whole load range. The paper also includes an assessment of the common methods of checking the condition of cracking in relation to the tested SRP strengthening. The paper presents actual calculation procedures to determine the crack spacing and crack width. The discussed formulas are verified with results of provided laboratory tests.

Flexural Strength Of Prestressed Concrete Beams With Openings And Strengthened With CFRP Sheets

Directory of Open Access Journals (Sweden)

Dr. Mustafa B. Dawood

2015-06-01

Full Text Available Abstract This paper presents an experimental investigation of flexural strength of pretensioned prestressed concrete beams with openings and strengthened with CFRP sheets tested as simply supported span subjected under two-point loading. The experimental work includes testing of nine prestressed concrete beams specimens with dimensions effective length 1800mm depth 300mm width 130mm two of which were without openings as a control beams one without and the other with strengthening by CFRP three were with openings and the remaining four with openings and strengthened with CFRP sheets. The opening was made at square shape 100100 mm in flexure zone at mid span of beam. Several design parameters were varied such as opening width opening depth and strengthening of openings of beams by CFRP sheets at compression and tension zone. Experimental results showed that the presence of square opening with ratio hH 0.333 and rectangular opening with ratio hH from 0.333-0.5 at mid span of beams decreased the ultimate load about 5.5 and 5.5-33.1 respectively when compared with beam without openings control beam. The externally strengthened prestressed concrete beams with bonded CFRP sheets showed a significant increase at the ultimate load this increase was about 10.9-28.8 for flexure beams when compared with the unstrengthened beams. Moreover the load-deflection curves for flexure beams strengthened with CFRP sheets were stiffer than the unstrengthened beams. Therefore this results gave a good indication about using CFRP sheets in improvement of deflection.

Cobalt-60 Machines and Medical Linear Accelerators: Competing Technologies for External Beam Radiotherapy.

Science.gov (United States)

Healy, B J; van der Merwe, D; Christaki, K E; Meghzifene, A

2017-02-01

Medical linear accelerators (linacs) and cobalt-60 machines are both mature technologies for external beam radiotherapy. A comparison is made between these two technologies in terms of infrastructure and maintenance, dosimetry, shielding requirements, staffing, costs, security, patient throughput and clinical use. Infrastructure and maintenance are more demanding for linacs due to the complex electric componentry. In dosimetry, a higher beam energy, modulated dose rate and smaller focal spot size mean that it is easier to create an optimised treatment with a linac for conformal dose coverage of the tumour while sparing healthy organs at risk. In shielding, the requirements for a concrete bunker are similar for cobalt-60 machines and linacs but extra shielding and protection from neutrons are required for linacs. Staffing levels can be higher for linacs and more staff training is required for linacs. Life cycle costs are higher for linacs, especially multi-energy linacs. Security is more complex for cobalt-60 machines because of the high activity radioactive source. Patient throughput can be affected by source decay for cobalt-60 machines but poor maintenance and breakdowns can severely affect patient throughput for linacs. In clinical use, more complex treatment techniques are easier to achieve with linacs, and the availability of electron beams on high-energy linacs can be useful for certain treatments. In summary, there is no simple answer to the question of the choice of either cobalt-60 machines or linacs for radiotherapy in low- and middle-income countries. In fact a radiotherapy department with a combination of technologies, including orthovoltage X-ray units, may be an option. Local needs, conditions and resources will have to be factored into any decision on technology taking into account the characteristics of both forms of teletherapy, with the primary goal being the sustainability of the radiotherapy service over the useful lifetime of the equipment

Beam front accelerators

International Nuclear Information System (INIS)

Reiser, M.

1982-01-01

An intense relativistic electron beam cannot propagate in a metal drift tube when the current exceeds the space charge limit. Very high charge density and electric field gradients (10 2 to 10 3 MV/m) develop at the beam front and the electrons are reflected. When a neutral gas or a plasma is present, collective acceleration of positive ions occur, and the resulting charge neutralization enables the beam to propagate. Experimental results, theoretical understanding, and schemes to achieve high ion energies by external control of the beam front velocity will be reviewed

Short-term Androgen-Deprivation Therapy Improves Prostate Cancer-Specific Mortality in Intermediate-Risk Prostate Cancer Patients Undergoing Dose-Escalated External Beam Radiation Therapy

International Nuclear Information System (INIS)

Zumsteg, Zachary S.; Spratt, Daniel E.; Pei, Xin; Yamada, Yoshiya; Kalikstein, Abraham; Kuk, Deborah; Zhang, Zhigang; Zelefsky, Michael J.

2013-01-01

Purpose: We investigated the benefit of short-term androgen-deprivation therapy (ADT) in patients with intermediate-risk prostate cancer (PC) receiving dose-escalated external beam radiation therapy. Methods and Materials: The present retrospective study comprised 710 intermediate-risk PC patients receiving external beam radiation therapy with doses of ≥81 Gy at a single institution from 1992 to 2005, including 357 patients receiving neoadjuvant and concurrent ADT. Prostate-specific antigen recurrence-free survival (PSA-RFS) and distant metastasis (DM) were compared using the Kaplan-Meier method and Cox proportional hazards models. PC-specific mortality (PCSM) was assessed using competing-risks analysis. Results: The median follow-up was 7.9 years. Despite being more likely to have higher PSA levels, Gleason score 4 + 3 = 7, multiple National Comprehensive Cancer Network intermediate-risk factors, and older age (P≤.001 for all comparisons), patients receiving ADT had improved PSA-RFS (hazard ratio [HR], 0.598; 95% confidence interval [CI], 0.435-0.841; P=.003), DM (HR, 0.424; 95% CI, 0.219-0.819; P=.011), and PCSM (HR, 0.380; 95% CI, 0.157-0.921; P=.032) on univariate analysis. Using multivariate analysis, ADT was an even stronger predictor of improved PSA-RFS (adjusted HR [AHR], 0.516; 95% CI, 0.360-0.739; P<.001), DM (AHR, 0.347; 95% CI, 0.176-0.685; P=.002), and PCSM (AHR, 0.297; 95% CI, 0.128-0.685; P=.004). Gleason score 4 + 3 = 7 and ≥50% positive biopsy cores were other independent predictors of PCSM. Conclusions: Short-term ADT improves PSA-RFS, DM, and PCSM in patients with intermediate-risk PC undergoing dose-escalated external beam radiation therapy

Two Methods For Simulating the Strong-Strong Beam-Beam Interaction in Hadron Colliders

International Nuclear Information System (INIS)

Warnock, Robert L.

2002-01-01

We present and compare the method of weighted macro particle tracking and the Perron-Frobenius operator technique for simulating the time evolution of two beams coupled via the collective beam-beam interaction in 2-D and 4-D (transverse) phase space. The coherent dipole modes, with and without lattice nonlinearities and external excitation, are studied by means of the Vlasov-Poisson system

Early observed transient prostate-specific antigen elevations on a pilot study of external beam radiation therapy and fractionated MRI guided High Dose Rate brachytherapy boost

International Nuclear Information System (INIS)

Singh, Anurag K; Godette, Denise J; Stall, Bronwyn R; Coleman, C Norman; Camphausen, Kevin; Ménard, Cynthia; Guion, Peter; Susil, Robert C; Citrin, Deborah E; Ning, Holly; Miller, Robert W; Ullman, Karen; Smith, Sharon; Crouse, Nancy Sears

2006-01-01

To report early observation of transient PSA elevations on this pilot study of external beam radiation therapy and magnetic resonance imaging (MRI) guided high dose rate (HDR) brachytherapy boost. Eleven patients with intermediate-risk and high-risk localized prostate cancer received MRI guided HDR brachytherapy (10.5 Gy each fraction) before and after a course of external beam radiotherapy (46 Gy). Two patients continued on hormones during follow-up and were censored for this analysis. Four patients discontinued hormone therapy after RT. Five patients did not receive hormones. PSA bounce is defined as a rise in PSA values with a subsequent fall below the nadir value or to below 20% of the maximum PSA level. Six previously published definitions of biochemical failure to distinguish true failure from were tested: definition 1, rise >0.2 ng/mL; definition 2, rise >0.4 ng/mL; definition 3, rise >35% of previous value; definition 4, ASTRO defined guidelines, definition 5 nadir + 2 ng/ml, and definition 6, nadir + 3 ng/ml. Median follow-up was 24 months (range 18–36 mo). During follow-up, the incidence of transient PSA elevation was: 55% for definition 1, 44% for definition 2, 55% for definition 3, 33% for definition 4, 11% for definition 5, and 11% for definition 6. We observed a substantial incidence of transient elevations in PSA following combined external beam radiation and HDR brachytherapy for prostate cancer. Such elevations seem to be self-limited and should not trigger initiation of salvage therapies. No definition of failure was completely predictive

A Bile Duct Cancer Patient Whose Stent Shifted Significantly Over the Course of External Beam Radiotherapy

International Nuclear Information System (INIS)

Yun, Hyong Geun

2011-01-01

The author reports a bile duct cancer patient whose stent shifted significantly from right to left over the course of radiotherapy. The 80-year-old female patient had a short stature with thoracic kyphosis and mutiple spinal compression fractures. She was also emaciated and very lean. By comparing the weekly scanned computed tomography images, the author found her stent to have shifted by more than 4 cm from right to left over the course of external beam radiotherapy. The results of this case study suggest that for a very lean and emaciated kyphotic bile duct cancer patient, the possibility of large interfractional movement of the bile duct or stent during radiotherapy should be considered.

The effect of additional equilibrium stress functions on the three-node hybrid-mixed curved beam element

International Nuclear Information System (INIS)

Kim, Jin Gon; Park, Yong Kuk

2008-01-01

To develop an effective hybrid-mixed element, it is extremely critical as to how to assume the stress field. This research article demonstrates the effect of additional equilibrium stress functions to enhance the numerical performance of the locking-free three-node hybrid-mixed curved beam element, proposed in Saleeb and Chang's previous work. It is exceedingly complicated or even infeasible to determine the stress functions to satisfy fully both the equilibrium conditions and suppression of kinematic deformation modes in the three-node hybrid-mixed formulation. Accordingly, the additional stress functions to satisfy partially or fully equilibrium conditions are incorporated in this study. Several numerical examples for static and dynamic problems confirm that the newly proposed element with these additional stress functions is highly effective regardless of the slenderness ratio and curvature of arches in static and dynamic analyses

Combination of peptide receptor radionuclide therapy with fractionated external beam radiotherapy for treatment of advanced symptomatic meningioma

International Nuclear Information System (INIS)

Kreissl, Michael C; Flentje, Michael; Sweeney, Reinhart A; Hänscheid, Heribert; Löhr, Mario; Verburg, Frederik A; Schiller, Markus; Lassmann, Michael; Reiners, Christoph; Samnick, Samuel S; Buck, Andreas K

2012-01-01

External beam radiotherapy (EBRT) is the treatment of choice for irresectable meningioma. Due to the strong expression of somatostatin receptors, peptide receptor radionuclide therapy (PRRT) has been used in advanced cases. We assessed the feasibility and tolerability of a combination of both treatment modalities in advanced symptomatic meningioma. 10 patients with irresectable meningioma were treated with PRRT ( 177 Lu-DOTA0,Tyr3 octreotate or - DOTA0,Tyr3 octreotide) followed by external beam radiotherapy (EBRT). EBRT performed after PRRT was continued over 5–6 weeks in IMRT technique (median dose: 53.0 Gy). All patients were assessed morphologically and by positron emission tomography (PET) before therapy and were restaged after 3–6 months. Side effects were evaluated according to CTCAE 4.0. Median tumor dose achieved by PRRT was 7.2 Gy. During PRRT and EBRT, no side effects > CTCAE grade 2 were noted. All patients reported stabilization or improvement of tumor-associated symptoms, no morphologic tumor progression was observed in MR-imaging (median follow-up: 13.4 months). The median pre-therapeutic SUV max in the meningiomas was 14.2 (range: 4.3–68.7). All patients with a second PET after combined PRRT + EBRT showed an increase in SUV max (median: 37%; range: 15%–46%) to a median value of 23.7 (range: 8.0–119.0; 7 patients) while PET-estimated volume generally decreased to 81 ± 21% of the initial volume. The combination of PRRT and EBRT is feasible and well tolerated. This approach represents an attractive strategy for the treatment of recurring or progressive symptomatic meningioma, which should be further evaluated

Flexural Strength of Carbon Fiber Reinforced Polymer Repaired Cracked Rectangular Hollow Section Steel Beams

Directory of Open Access Journals (Sweden)

Tao Chen

2015-01-01

Full Text Available The flexural behavior of rectangular hollow section (RHS steel beams with initial crack strengthened externally with carbon fiber reinforced polymer (CFRP plates was studied. Eight specimens were tested under three-point loading to failure. The experimental program included three beams as control specimens and five beams strengthened with CFRP plates with or without prestressing. The load deflection curves were graphed and failure patterns were observed. The yield loads and ultimate loads with or without repairing were compared together with the strain distributions of the CFRP plate. It was concluded that yield loads of cracked beams could be enhanced with repairing. Meanwhile, the ultimate loads were increased to some extent. The effect of repair became significant with the increase of the initial crack depth. The failure patterns of the repaired specimens were similar to those of the control ones. Mechanical clamping at the CFRP plate ends was necessary to avoid premature peeling between the CFRP plate and the steel beam. The stress levels in CFRP plates were relatively low during the tests. The use of prestressing could improve the utilization efficiency of CFRP plates. It could be concluded that the patching repair could be used to restore the load bearing capacity of the deficient steel beams.

External beam radiotherapy of localized prostatic adenocarcinoma. Evaluation of conformal therapy, field number and target margins

International Nuclear Information System (INIS)

Lennernaes, B.; Rikner, G.; Letocha, H.; Nilsson, S.

1995-01-01

The purpose of the present study was to identify factors of importance in the planning of external beam radiotherapy of prostatic adenocarcinoma. Seven patients with urogenital cancers were planned for external radiotherapy of the prostate. Four different techniques were used, viz. a 4-field box technique and four-, five- or six-field conformal therapy set-ups combined with three different margins (1-3 cm). The evaluations were based on the doses delivered to the rectum and the urinary bladder. A normal tissue complication probability (NTCP) was calculated for each plan using Lyman's dose volume reduction method. The most important factors that resulted in a decrease of the dose delivered to the rectum and the bladder were the use of conformal therapy and smaller margins. Conformal therapy seemed more important for the dose distribution in the urinary bladder. Five- and six-field set-ups were not significantly better than those with four fields. NTCP calculations were in accordance with the evaluation of the dose volume histograms. To conclude, four-field conformal therapy utilizing reduced margins improves the dose distribution to the rectum and the urinary bladder in the radiotherapy of prostatic adenocarcinoma. (orig.)

A criterion-based audit of the technical quality of external beam radiotherapy for prostate cancer

International Nuclear Information System (INIS)

Brundage, Michael; Danielson, Brita; Pearcey, Robert; Bass, Brenda; Pickles, Tom; Bahary, Jean-Paul; Peng, Yingwei; Wallace, David; Mackillop, William

2013-01-01

Purpose: To evaluate the technical quality of external beam radiotherapy for prostate cancer in Canada. Methods: This was a multi-institution, retrospective study of a random sample of patients undergoing radiotherapy (RT) for prostate cancer in Canada. Patterns of care were determined by abstracting details of the patients’ management from original records. The quality of patient’s technical care was measured against a previously published, comprehensive suite of quality indicators. Results: 32 of the 37 RT centres participated. The total study population of 810 patients included 25% low-risk, 44% intermediate-risk, and 28% high-risk cases. 649 received external beam RT (EBRT) only, for whom compliance with 12 indicators of the quality of pre-treatment assessment ranged from 56% (sexual function documented) to 96% (staging bone scan obtained in high-risk patients). Compliance with treatment-related indicators ranged from 78% (dose to prostate ⩾74 Gy in intermediate risk patients not receiving hormone therapy) to 100% (3DCRT or IMRT plan). Compliance varied among centres; no centre demonstrated 100% compliance on all indicators and every centre was 100% compliant on at least some indicators. The number of assessment-related indicators (n = 13) with which a given centre was 100% compliant ranged from 4 to 11 (median 7) and the number of the treatment-specific indicators (n = 8) with which a given centre was 100% compliant ranged from 6 to 8 (median 8). ADT therapy was utilised in most high-risk cases (191, 92.3%). Conclusions: While patterns of prostate cancer care in Canada vary somewhat, compliance on the majority of quality indicators is very high. However, all centres showed room for improvement on several indicators and few individual patients received care that met target benchmarks on all quality measures. This variation is particularly important for indicators such as delivered dose where impact on disease outcome is known to exist, and suggests that

Normal tissue tolerance to external beam radiation therapy: Thyroid; Dose de tolerance des tissus sains: la thyroide

Energy Technology Data Exchange (ETDEWEB)

Berges, O.; Giraud, P. [Service d' oncologie-radiotherapie, hopital europeen Georges-Pompidou, universite Paris Descartes, 75 - Paris (France); Belkacemi, Y. [Service d' oncologie-radiotherapie, CHU Henri-Mondor, universite Paris 12, 94 - Creteil (France)

2010-07-15

The thyroid is the most developed endocrine gland of the body. Due to its anatomical location, it may be exposed to ionizing radiation in external radiotherapy involving head and neck. This review aims to describe the thyroid radiation disorders, probably under-reported in the literature, their risk factors and follow-up procedures. The functional changes after external beam radiation consists mainly of late effects occurring beyond 6 months, and are represented by the clinical and subclinical hypothyroidism. Its incidence is approximately 20 to 30% and it can occur after more than 25 years after radiation exposure. Hyperthyroidism and auto-immune manifestations have been described in a lesser proportion. The morphological changes consist of benign lesions, primarily adenomas, and malignant lesions, the most feared and which incidence is 0.35%. The onset of hypothyroidism depends of the total dose delivered to the gland, and the irradiated. Modern techniques of conformal radiotherapy with modulated intensity could improve the preservation of the thyroid, at the expense of the increase in low doses and the theoretical risk of secondary cancers. (authors)

Anesthesia for pediatric external beam radiation therapy

International Nuclear Information System (INIS)

Fortney, Jennifer T.; Halperin, Edward C.; Hertz, Caryn M.; Schulman, Scott R.

1999-01-01

Background: For very young patients, anesthesia is often required for radiotherapy. This results in multiple exposures to anesthetic agents over a short period of time. We report a consecutive series of children anesthetized for external beam radiation therapy (EBRT). Methods: Five hundred twelve children ≤ 16 years old received EBRT from January 1983 to February 1996. Patient demographics, diagnosis, anesthesia techniques, monitoring, airway management, complications, and outcome were recorded for the patients requiring anesthesia. Results: One hundred twenty-three of the 512 children (24%) required 141 courses of EBRT with anesthesia. Anesthetized patients ranged in age from 20 days to 11 years (mean 2.6 ± 1.8 ). The frequency of a child receiving EBRT and requiring anesthesia by age cohort was: ≤ 1 year (96%), 1-2 years (93%), 2-3 years (80%), 3-4 years (51%), 4-5 years (36%), 5-6 years (13%), 6-7 years (11%), and 7-16 years (0.7%). Diagnoses included: primary CNS tumor (28%), retinoblastoma (27%), neuroblastoma (20%), acute leukemia (9%), rhabdomyosarcoma (6%), and Wilms' tumor (4%). Sixty-three percent of the patients had been exposed to chemotherapy prior to EBRT. The mean number of anesthesia sessions per patient was 22 ± 16. Seventy-eight percent of the treatment courses were once daily and 22% were twice daily. Anesthesia techniques included: short-acting barbiturate induction + inhalation maintenance (21%), inhalation only (20%), ketamine (19%), propofol only (12%), propofol induction + inhalation maintenance (7%), ketamine induction + inhalation maintenance (6%), ketamine or short-acting barbiturate induction + inhalation maintenance (6%). Monitoring techniques included: EKG (95%), O 2 saturation (93%), fraction of inspired O 2 (57%), and end-tidal CO 2 (55%). Sixty-four percent of patients had central venous access. Eleven of the 74 children with a central line developed sepsis (15%): 6 of the 11 were anesthetized with propofol (55%), 4 with a

Measuring the beaming angle of GRB 030329 by fitting the rebrightenings in its multiband afterglow

International Nuclear Information System (INIS)

Deng Wei; Huang Yongfeng; Kong Siwei

2010-01-01

Multiple rebrightenings have been observed in the multiband afterglow of GRB 030329. In particular, a marked and quick rebrightening occurred at about t ∼ 1.2 x 10 5 s. Energy injection from late and slow shells seems to be the best interpretation for these rebrightenings. Usually it is assumed that the energy is injected into the whole external shock. However, in the case of GRB 030329, the rebrightenings are so quick that the usual consideration fails to give a satisfactory fit to the observed light curves. Actually, since these late/slow shells freely coast in the wake of the external shock, they should be cold and may not expand laterally. The energy injection then should only occur at the central region of the external shock. Considering this effect, we numerically re-fit the quick rebrightenings observed in GRB 030329. By doing this, we were able to derive the beaming angle of the energy injection process. Our result, with a relative residual of only 5% - 10% during the major rebrightening, is better than any previous modeling. The derived energy injection angle is about 0.035. We assume that these late shells are ejected by the central engine via the same mechanism as those early shells that produce the prompt gamma-ray burst. The main difference is that their velocities are much slower, so that they catch up with the external shock relatively late and are manifested as the observed quick rebrightenings. If this were true, then the derived energy injection angle can give a good measure of the beaming angle of the prompt γ-ray emission. Our study may hopefully provide a novel method to measure the beaming angle of gamma-ray bursts. (research papers)

Optical bistability and multistability driven by external magnetic field in a dielectric slab doped with nanodiamond nitrogen vacancy centres

Science.gov (United States)

Nasehi, R.; Norouzi, F.

2016-08-01

The theoretical investigation of controlling the optical bistability (OB) and optical multistability (OM) in a dielectric medium doped with nanodiamond nitrogen vacancy centres under optical excitation are reported. The shape of the OB curve from dielectric slab can be tuned by changing the external magnetic field and polarization of the control beam. The effect of the intensity of the control laser field and the frequency detuning of probe laser field on the OB and OM behaviour are also discussed in this paper. The results obtained can be used for realizing an all-optical bistable switching or development of nanoelectronic devices.

Evaluation of the response of concurrent high dose rate intracavitary brachytherapy with external beam radiotherapy in management of early stage carcinoma cervix.

Science.gov (United States)

Patidar, Arvind Kumar; Kumar, H S; Walke, Rahul V; Hirapara, Pushpendra H; Jakhar, Shankar Lal; Bardia, M R

2012-10-01

To evaluate local disease control and early complications of concomitant brachytherapy with external beam-radiotherapy in early stage carcinoma cervix. Fifty patients of early stage carcinoma cervix (FIGO-IB/IIA) were randomly divided into study group concomitant external beam irradiation (EBRT) and HDR-ICBT (intra-cavitary brachytherapy, xrt = 50 Gy/25 Fr, HDR 5.2 Gy*5 Fr) and the control group EBRT followed by HDR-ICBT (xrt = 50 Gy/25 Fr, HDR 7.5 Gy*3 Fr). Acute reactions and local disease response were compared between treatment and at 6-month follow up. Median overall treatment times were 38 and 61 days in the study and the control groups, respectively. Acute skin reactions and diarrhea were more in the study but manageable. At the completion of the study, there were 80 and 68 % complete responses, 16 and 20 % partial responses, 0 and 8 % stable diseases in the study group and the control group, respectively. Response was better in the study group but statistically insignificant. Larger number of patients and longer follow up are required to arrive at concrete conclusion.

Salvage external beam radiotherapy for clinical failure after cryosurgery for prostate cancer

International Nuclear Information System (INIS)

McDonough, Michael J.; Feldmeier, John J.; Parsai, Ishmael; Dobelbower, Ralph R.; Selman, Steven H.

2001-01-01

Purpose: To investigate the role of external beam radiotherapy (EBRT) as salvage treatment of prostate cancer after cryosurgery failure. Methods and Materials: Between 1993 and 1998, 6 patients underwent EBRT with curative intent for local recurrence of prostate cancer after cryosurgery. All 6 patients had biopsy-proven recurrence and palpable disease on digital rectal examination at the time of EBRT. The median follow-up was 34 months (range 8-46). The median prostate-specific antigen level was 2.3 ng/mL (range 0.8-4.1). No patient had evidence of metastatic disease. Two patients received hormonal therapy before beginning EBRT. No patient received hormonal therapy after EBRT completion. The median elapsed time between cryosurgery and EBRT was 3 years (range 1.5-4). The median delivered dose was 66 Gy (range 62-70.2) using a 10-MeV photon beam. An in-house-developed three-dimensional treatment planning system was used to plan delivery of the prescribed dose with conformal radiotherapy techniques. Results: After EBRT, all patients had complete resolution of palpable disease. Four patients (66%) were disease free at the time of the last follow-up. Two patients developed biochemical failure as defined by the American Society for Therapeutic Radiology and Oncology consensus definition. One of these patients had a prostate-specific antigen level of 97 ng/mL before cryosurgery. No patient developed distant metastasis during follow-up. Two patients (33%) developed proctitis; 1 case resolved with Rowasa suppositories and 1 required blood transfusion. Conclusions: Our preliminary results suggest that EBRT can render a significant number of patients biochemically free of disease and can cause complete resolution of clinically palpable disease after initial cryosurgery. The results also showed that EBRT can be given without excessive morbidity. EBRT should be considered as a treatment option in these potentially curable cases

External-beam boost prior to total-body irradiation in relapsed NHL transplant patients

Energy Technology Data Exchange (ETDEWEB)

Monson, Jedidiah M; Neuberg, Donna; Freedman, Arnold S; Tarbell, Nancy J; Nadler, Lee M; Mauch, Peter

1995-07-01

PURPOSE: To determine the impact of an external beam boost (EBB) on the outcome, relapse pattern and normal tissue toxicities of patients undergoing total-body irradiation (TBI) prior to bone marrow transplantation (BMT) for relapsed NHL. MATERIALS AND METHODS: Between 1982 and 1994, 299 patients at our institution underwent BMT for relapsed NHL. Patients underwent induction chemotherapy (CT) followed by conditioning with cyclophosphamide and 12 Gy TBI delivered in 6 fractions over 3 days. A total of 77 patients had persistent gross disease, defined as 2 cm or greater, after induction CT and received an EBB prior to BMT (EBB cohort). The median EBB dose was 28.8 Gy (range, 5-63), the median field size was 13 cm{sup 2} (range, 5-29.4) and the median time from EBB to BMT was 3 weeks (range, 1-20). A total of 222 patients were free of measurable disease or had disease measuring <2cm after CT and did not receive EBB (no-EBB cohort). To assess normal tissue toxicity, patients' simulation films and/or treatment records were reviewed for all 77 patients treated with local EBB and estimates were made of the percentage lung, heart and kidney in the radiation field. RESULTS: A total of 79 of 222 patients (36%) in the no-EBB cohort have relapsed; 33 of 77 patients (43%) in the EBB cohort have relapsed (p=0.28, by Fisher exact test). Median time to relapse after BMT was 54 months for the no-EBB cohort and 38 months for the EBB cohort (p=0.26, by log-rank test). The 3-year actuarial freedom from relapse (deaths in remission censored) was 59% for the no-EBB cohort (90% CI: 52-66%) and 51% for the EBB cohort (90% CI: 40-62%). Data on site of relapse was available for 101 of the 112 relapses (75 no-EBB, 26 EBB). For the no-EBB cohort 33 of 75 relapses (44%) were in sites of prior nodal disease only. For the EBB cohort, 12 of 26 relapses (46%) were in sites of prior nodal disease only, of these, only 6 (23%) were within the EBB treatment field. A total of 26 patients had thoracic

Rotating light ion beam-plasma system in inertial confinement fusion

International Nuclear Information System (INIS)

Murakami, H.; Okada, T.

1997-01-01

The stabilizing mechanism of filamentation instability in light ion beam propagation is studied numerically by using a particle-in-cell code. Rotating light ion beam scheme has been proposed for the light ion beam propagation. The filamentation instability is stabilized by the external magnetic field which is induced by the rotating light ion beams. From a dispersion relation, linear growth rates of filamentation instabilities are obtained in a light ion beam-plasma system with an external magnetic field. The theory and simulation comparisons illustrate the results. (author)

Analytical Model for Fictitious Crack Propagation in Concrete Beams

DEFF Research Database (Denmark)

Ulfkjær, J. P.; Krenk, Steen; Brincker, Rune

1995-01-01

An analytical model for load-displacement curves of concrete beams is presented. The load-displacement curve is obtained by combining two simple models. The fracture is modeled by a fictitious crack in an elastic layer around the midsection of the beam. Outside the elastic layer the deformations...... are modeled by beam theory. The state of stress in the elastic layer is assumed to depend bilinearly on local elongation corresponding to a linear softening relation for the fictitious crack. Results from the analytical model are compared with results from a more detailed model based on numerical methods...... for different beam sizes. The analytical model is shown to be in agreement with the numerical results if the thickness of the elastic layer is taken as half the beam depth. It is shown that the point on the load-displacement curve where the fictitious crack starts to develop and the point where the real crack...

Long-Term Results of an RTOG Phase II Trial (00-19) of External-Beam Radiation Therapy Combined With Permanent Source Brachytherapy for Intermediate-Risk Clinically Localized Adenocarcinoma of the Prostate

Energy Technology Data Exchange (ETDEWEB)

Lawton, Colleen A., E-mail: clawton@mcw.edu [Department of Radiation Oncology, Medical College of Wisconsin, Milwaukee, WI (United States); Yan, Yan [Radiation Therapy Oncology Group Statistical Center, Philadelphia, PA (United States); Lee, W. Robert [Department of Radiation Oncology, Duke University School of Medicine, Durham, NC (United States); Gillin, Michael [Department of Radiation Oncology, MD Anderson Cancer Center, University of Texas MD Anderson Cancer Center, Houston, TX (United States); Firat, Selim [Department of Radiation Oncology, Medical College of Wisconsin, Milwaukee, WI (United States); Baikadi, Madhava [Department of Radiation Oncology, Northeast Radiation Oncology Center, Scranton, PA (United States); Crook, Juanita [Department of Radiation Oncology, University of British Columbia, Kelowna, BC (Canada); Kuettel, Michael [Department of Radiation Medicine, Roswell Park Cancer Institute, Buffalo, NY (United States); Morton, Gerald [Department of Radiation Oncology, Toronto-Sunnybrook Regional Cancer Center, Toronto, ON (Canada); Sandler, Howard [Department of Radiation Oncology, Cedars-Sinai Medical Center, Los Angeles, CA (United States)

2012-04-01

Purpose: External-beam radiation therapy combined with low-doserate permanent brachytherapy are commonly used to treat men with localized prostate cancer. This Phase II trial was performed to document late gastrointestinal or genitourinary toxicity as well as biochemical control for this treatment in a multi-institutional cooperative group setting. This report defines the long-term results of this trial. Methods and Materials: All eligible patients received external-beam radiation (45 Gy in 25 fractions) followed 2-6 weeks later by a permanent iodine 125 implant of 108 Gy. Late toxicity was defined by the Radiation Therapy Oncology Group/European Organization for Research and Treatment of Cancer late radiation morbidity scoring scheme. Biochemical control was defined by the American Society for Therapeutic Radiology and Oncology (ASTRO) Consensus definition and the ASTRO Phoenix definition. Results: One hundred thirty-eight patients were enrolled from 20 institutions, and 131 were eligible. Median follow-up (living patients) was 8.2 years (range, 2.7-9.3 years). The 8-year estimate of late grade >3 genitourinary and/or gastrointestinal toxicity was 15%. The most common grade >3 toxicities were urinary frequency, dysuria, and proctitis. There were two grade 4 toxicities, both bladder necrosis, and no grade 5 toxicities. In addition, 42% of patients complained of grade 3 impotence (no erections) at 8 years. The 8-year estimate of biochemical failure was 18% and 21% by the Phoenix and ASTRO consensus definitions, respectively. Conclusion: Biochemical control for this treatment seems durable with 8 years of follow-up and is similar to high-dose external beam radiation alone or brachytherapy alone. Late toxicity in this multi-institutional trial is higher than reports from similar cohorts of patients treated with high-dose external-beam radiation alone or permanent low-doserate brachytherapy alone, perhaps suggesting further attention to strategies that limit doses to

Surface sterilization by low energy electron beams

International Nuclear Information System (INIS)

Sekiguchi, Masayuki; Tabei, Masae

1989-01-01

The germicidal effectiveness of low energy electron beams (175 KV) against bacterial cells was investigated. The dry spores of Bacillus pumilus ATCC 27142 and Bacillus globigii ATCC 9372 inoculated on carrier materials and irradiated by gamma rays showed the exponential type of survival curves whereas they showed sigmoidal ones when exposed to low energy electron beams. When similarly irradiated, the wet spores inoculated on membrane filter showed the same survival curves as the dry spores inoculated on carrier materials. The wet vegetative cells of Escherichia coli ATCC 25922 showed exponential curves when exposed to gamma and electron beam irradiation. Low energy electron beams in air showed little differences from nitrogen stream in their germicidal effectiveness against dry spores of B. pumilus. The D values of B. pumilus spores inoculated on metal plates decreased as the amounts of backscattering electrons from the plates increased. There was adequate correlation between the D value (linear region of survival curve), average D value (6D/6) and 1% survival dose and backscattering factor. Depth dose profile and backscatterig dose of low energy electron beams were measured by radiochromic dye film dosimeter (RCD). These figures were not always in accord with the observed germicidal effectiveness against B. pumilus spores because of varying thickness of RCD and spores inoculated on carrier material. The dry spores were very thin and this thinness was useful in evaluating the behavior of low energy electrons. (author)

High intensity beam profile monitors for the LAMPF primary beam lines

International Nuclear Information System (INIS)

Hoffman, E.W.; Macek, R.J.; van Dyck, O.; Lee, D.; Harvey, A.; Bridge, J.; Cainet, J.

1979-01-01

Two types of beam profile monitors are in use at LAMPF to measure the properties of the 800 MeV, 500 μA proton beam external to the linac. Both types use secondary electron emission from a wire to produce a current signal proportional to the amount of proton beam that intercepts the wire. The wire scanner system uses a pair of orthogonal wires which are passed through the beam and the harp system uses two fixed planes of parallel wires. Most of the harps are not retractable and are exposed continuously to the primary beam. The high beam intensities available lead to a number of technical problems for instruments that intercept the beam or are close to primary beam targets. The thermal, electrical, radiation-damage, and material selection problems encountered, and some solutions which have been implemented are discussed

5-μm vertical external-cavity surface-emitting laser (VECSEL) for spectroscopic applications

Science.gov (United States)

Rahim, M.; Khiar, A.; Felder, F.; Fill, M.; Zogg, H.; Sigrist, M. W.

2010-08-01

Mid-IR tunable VECSELs (Vertical External-Cavity Surface-Emitting Lasers) emitting at 4-7 μm wavelengths and suitable for spectroscopic sensing applications are described. They are realized with lead-chalcogenide (IV-VI) narrow band gap materials. The active part, a single 0.6-2-μm thick PbTe or PbSe gain layer, is grown onto an epitaxial Bragg mirror consisting of two or three Pb1- y Eu y Te/BaF2 quarter-wavelength layer pairs. All layers are deposited by MBE in a single run employing a BaF2 or Si substrate, no further processing is needed. The cavity is completed with an external curved top mirror, which is again realized with an epitaxial Bragg structure. Pumping is performed optically with a 1.5-μm laser. Maximum output power for pulsed operation is currently up to >1 Wp at -173°C and >10 mW at 10°C. In continuous wave (CW) operation, 18 mW at 100 K are reached. Still higher operating temperatures and/or powers are expected with better heat-removal structures and better designs employing QW (Quantum-Wells). Advantages of mid-IR VECSELs compared to edge-emitting lasers are their very good beam quality (circular beam with 15 μm are accessible with Pb1- y X y Z (X=Sr, Eu, Sn, Z=Se, Te) and/or including QW.

The Relationship Between Local Recurrence and Radiotherapy Treatment Volume for Soft Tissue Sarcomas Treated With External Beam Radiotherapy and Function Preservation Surgery

Energy Technology Data Exchange (ETDEWEB)

Dickie, Colleen I., E-mail: Colleen.dickie@rmp.uhn.on.ca [Radiation Medicine Program, Princess Margaret Hospital, Toronto (Canada); Griffin, Anthony M. [Division of Orthopaedic Surgery, University Musculoskeletal Oncology Unit, Mount Sinai Hospital, Toronto (Canada); University of Toronto, Toronto (Canada); Parent, Amy L. [Radiation Medicine Program, Princess Margaret Hospital, Toronto (Canada); Chung, Peter W.M.; Catton, Charles N. [Radiation Medicine Program, Princess Margaret Hospital, Toronto (Canada); University of Toronto, Toronto (Canada); Svensson, Jon [AngliaRuskin University, Cambridge (United Kingdom); Ferguson, Peter C.; Wunder, Jay S.; Bell, Robert S. [Division of Orthopaedic Surgery, University Musculoskeletal Oncology Unit, Mount Sinai Hospital, Toronto (Canada); University of Toronto, Toronto (Canada); Sharpe, Michael B.; O' Sullivan, Brian [Radiation Medicine Program, Princess Margaret Hospital, Toronto (Canada); University of Toronto, Toronto (Canada)

2012-03-15

Purpose: To examine the geometric relationship between local recurrence (LR) and external beam radiotherapy (RT) volumes for soft-tissue sarcoma (STS) patients treated with function-preserving surgery and RT. Methods and Materials: Sixty of 768 (7.8%) STS patients treated with combined therapy within our institution from 1990 through 2006 developed an LR. Thirty-two received preoperative RT, 16 postoperative RT, and 12 preoperative RT plus a postoperative boost. Treatment records, RT simulation images, and diagnostic MRI/CT data sets of the original and LR disease were retrospectively compared. For LR location analysis, three RT target volumes were defined according to the International Commission on Radiation Units and Measurements 29 as follows: (1) the gross tumor or operative bed; (2) the treatment volume (TV) extending 5 cm longitudinally beyond the tumor or operative bed unless protected by intact barriers to spread and at least 1-2 cm axially (the TV was enclosed by the isodose curve representing the prescribed target absorbed dose [TAD] and accounted for target/patient setup uncertainty and beam characteristics), and (3) the irradiated volume (IRV) that received at least 50% of the TAD, including the TV. LRs were categorized as developing in field within the TV, marginal (on the edge of the IRV), and out of field (occurring outside of the IRV). Results: Forty-nine tumors relapsed in field (6.4% overall). Nine were out of field (1.1% overall), and 2 were marginal (0.3% overall). Conclusions: The majority of STS tumors recur in field, indicating that the incidence of LR may be affected more by differences in biologic and molecular characteristics rather than aberrations in RT dose or target volume coverage. In contrast, only two patients relapsed at the IRV boundary, suggesting that the risk of a marginal relapse is low when the TV is appropriately defined. These data support the accurate delivery of optimal RT volumes in the most precise way using advanced

The Relationship Between Local Recurrence and Radiotherapy Treatment Volume for Soft Tissue Sarcomas Treated With External Beam Radiotherapy and Function Preservation Surgery

International Nuclear Information System (INIS)

Dickie, Colleen I.; Griffin, Anthony M.; Parent, Amy L.; Chung, Peter W.M.; Catton, Charles N.; Svensson, Jon; Ferguson, Peter C.; Wunder, Jay S.; Bell, Robert S.; Sharpe, Michael B.; O’Sullivan, Brian

2012-01-01

Purpose: To examine the geometric relationship between local recurrence (LR) and external beam radiotherapy (RT) volumes for soft-tissue sarcoma (STS) patients treated with function-preserving surgery and RT. Methods and Materials: Sixty of 768 (7.8%) STS patients treated with combined therapy within our institution from 1990 through 2006 developed an LR. Thirty-two received preoperative RT, 16 postoperative RT, and 12 preoperative RT plus a postoperative boost. Treatment records, RT simulation images, and diagnostic MRI/CT data sets of the original and LR disease were retrospectively compared. For LR location analysis, three RT target volumes were defined according to the International Commission on Radiation Units and Measurements 29 as follows: (1) the gross tumor or operative bed; (2) the treatment volume (TV) extending 5 cm longitudinally beyond the tumor or operative bed unless protected by intact barriers to spread and at least 1–2 cm axially (the TV was enclosed by the isodose curve representing the prescribed target absorbed dose [TAD] and accounted for target/patient setup uncertainty and beam characteristics), and (3) the irradiated volume (IRV) that received at least 50% of the TAD, including the TV. LRs were categorized as developing in field within the TV, marginal (on the edge of the IRV), and out of field (occurring outside of the IRV). Results: Forty-nine tumors relapsed in field (6.4% overall). Nine were out of field (1.1% overall), and 2 were marginal (0.3% overall). Conclusions: The majority of STS tumors recur in field, indicating that the incidence of LR may be affected more by differences in biologic and molecular characteristics rather than aberrations in RT dose or target volume coverage. In contrast, only two patients relapsed at the IRV boundary, suggesting that the risk of a marginal relapse is low when the TV is appropriately defined. These data support the accurate delivery of optimal RT volumes in the most precise way using advanced

Statistical modeling of the eye for multimodal treatment planning for external beam radiation therapy of intraocular tumors.

Science.gov (United States)

Rüegsegger, Michael B; Bach Cuadra, Meritxell; Pica, Alessia; Amstutz, Christoph A; Rudolph, Tobias; Aebersold, Daniel; Kowal, Jens H

2012-11-15

Ocular anatomy and radiation-associated toxicities provide unique challenges for external beam radiation therapy. For treatment planning, precise modeling of organs at risk and tumor volume are crucial. Development of a precise eye model and automatic adaptation of this model to patients' anatomy remain problematic because of organ shape variability. This work introduces the application of a 3-dimensional (3D) statistical shape model as a novel method for precise eye modeling for external beam radiation therapy of intraocular tumors. Manual and automatic segmentations were compared for 17 patients, based on head computed tomography (CT) volume scans. A 3D statistical shape model of the cornea, lens, and sclera as well as of the optic disc position was developed. Furthermore, an active shape model was built to enable automatic fitting of the eye model to CT slice stacks. Cross-validation was performed based on leave-one-out tests for all training shapes by measuring dice coefficients and mean segmentation errors between automatic segmentation and manual segmentation by an expert. Cross-validation revealed a dice similarity of 95%±2% for the sclera and cornea and 91%±2% for the lens. Overall, mean segmentation error was found to be 0.3±0.1 mm. Average segmentation time was 14±2 s on a standard personal computer. Our results show that the solution presented outperforms state-of-the-art methods in terms of accuracy, reliability, and robustness. Moreover, the eye model shape as well as its variability is learned from a training set rather than by making shape assumptions (eg, as with the spherical or elliptical model). Therefore, the model appears to be capable of modeling nonspherically and nonelliptically shaped eyes. Copyright © 2012 Elsevier Inc. All rights reserved.

Statistical Modeling of the Eye for Multimodal Treatment Planning for External Beam Radiation Therapy of Intraocular Tumors

Energy Technology Data Exchange (ETDEWEB)

Rueegsegger, Michael B. [ARTORG Center for Biomedical Engineering Research, University of Bern (Switzerland); Bach Cuadra, Meritxell [Department of Radiology, University Hospital Center (CHUV) and University of Lausanne (UNIL), Signal Processing Laboratory - LTS5, Ecole Polytechnique Federale de Lausanne (Switzerland); Pica, Alessia [Department of Radiation Oncology, Inselspital, Bern University Hospital, and University of Bern (Switzerland); Amstutz, Christoph A. [Department of Ophthalmology, University Hospital Zurich (Switzerland); Rudolph, Tobias [ARTORG Center for Biomedical Engineering Research, University of Bern (Switzerland); Aebersold, Daniel [Department of Radiation Oncology, Inselspital, Bern University Hospital, and University of Bern (Switzerland); Kowal, Jens H., E-mail: jens.kowal@artorg.unibe.ch [ARTORG Center for Biomedical Engineering Research, University of Bern (Switzerland)

2012-11-15

Purpose: Ocular anatomy and radiation-associated toxicities provide unique challenges for external beam radiation therapy. For treatment planning, precise modeling of organs at risk and tumor volume are crucial. Development of a precise eye model and automatic adaptation of this model to patients' anatomy remain problematic because of organ shape variability. This work introduces the application of a 3-dimensional (3D) statistical shape model as a novel method for precise eye modeling for external beam radiation therapy of intraocular tumors. Methods and Materials: Manual and automatic segmentations were compared for 17 patients, based on head computed tomography (CT) volume scans. A 3D statistical shape model of the cornea, lens, and sclera as well as of the optic disc position was developed. Furthermore, an active shape model was built to enable automatic fitting of the eye model to CT slice stacks. Cross-validation was performed based on leave-one-out tests for all training shapes by measuring dice coefficients and mean segmentation errors between automatic segmentation and manual segmentation by an expert. Results: Cross-validation revealed a dice similarity of 95% {+-} 2% for the sclera and cornea and 91% {+-} 2% for the lens. Overall, mean segmentation error was found to be 0.3 {+-} 0.1 mm. Average segmentation time was 14 {+-} 2 s on a standard personal computer. Conclusions: Our results show that the solution presented outperforms state-of-the-art methods in terms of accuracy, reliability, and robustness. Moreover, the eye model shape as well as its variability is learned from a training set rather than by making shape assumptions (eg, as with the spherical or elliptical model). Therefore, the model appears to be capable of modeling nonspherically and nonelliptically shaped eyes.

Sexual function after external-beam radiotherapy for prostate cancer: what do we know?

Science.gov (United States)

Incrocci, Luca

2006-02-01

Quality of life in general and sexual functioning in particular have become very important in cancer patients. Due to modern surgical techniques, improved quality of drugs for chemotherapy and very modern radiation techniques, more patients can be successfully treated without largely compromising sexual functioning. One can assume that because of the life-threatening nature of cancer, sexual activity is not important to patients and their partners, but this is not true. Prostate cancer has become the most common non-skin malignant neoplasm in older men in Western countries. In this paper, we discuss the various methods used to evaluate erectile and sexual dysfunction and the definition of potency. Data on the etiology of erectile dysfunction after external-beam radiotherapy for prostate cancer is reviewed, and the literature is been summarized. Patients should be offered sexual counseling and informed about the availability of effective treatments for erectile dysfunction, such as sildenafil, intracavernosal injection, and vacuum devices. Cancer affects quality of life and sexual function. The challenge for oncologists is to address this with compassion.

Reducing the risk of radiocarcinogenesis in paediatric patients treated with external beam radiotherapy

International Nuclear Information System (INIS)

Taylor, M.L.; Franich, R.D.; Kron, Tomas

2010-01-01

Full text: The aim of this study was to determine readily-implementable means of out-of-field dose reduction in paediatric patients undergoing external beam radiotherapy for intracranial lesions. [n this way, the risk of secondary cancer induction may be reduced. Dose measurements were taken using LiF:Mg, Cu, P TLD 1 00 H chips in a 5 year old paediatric phantom. Multiple TLDs were placed at: the right and left lenses of the eye, optic nerve, brain, thyroid, lungs, heart, kidneys, abdomen and gonads. Varian 600 C and Varian Trilogy linear accelerators, both at 6 MV, were investigated, using different delivery parameters. Most of the out-of-field dose at large distances is attributable to leakage. The difference between stereotactic and larger field sizes is less significant far from the primary field. Out-of-field dose from the Trilogy was 40% higher than the 600 e . Aligning the craniocaudal axis of the patient with the x-plane of the collimator results in a dose reduction of 40%, for both machines. - A simple shielding arrangement may halve out-of-field dose. (author)

Effect of a spectrometer magnet on the beam-beam interaction

International Nuclear Information System (INIS)

Cornacchia, M.; Parzen, G.

1981-01-01

The presence of experimental apparatus in the interaction regions of an intersecting beam accelerator changes the configuration of the crossing beams. This changes the space-charge forces with respect to the standard, magnet-free crossing. The question is: what is the maximum allowable perturbation caused by the spectrometer magnet that can be tolerated from the point of view of the beam dynamics. This paper is limited to the perturbations that the curved trajectories cause the beam-beam space charge nonlinearities. The question has arisen of how one defines the strength of the perturbation. The only solution is to compute the strength of the most important nonlinear resources. In what follows, the computational method used in calculating these resonances is described, and compared with those induced by random orbit errors

Effect of a spectrometer magnet on the beam-beam interaction

Energy Technology Data Exchange (ETDEWEB)

Cornacchia, M; Parzen, G

1981-01-01

The presence of experimental apparatus in the interaction regions of an intersecting beam accelerator changes the configuration of the crossing beams. This changes the space-charge forces with respect to the standard, magnet-free crossing. The question is: what is the maximum allowable perturbation caused by the spectrometer magnet that can be tolerated from the point of view of the beam dynamics. This paper is limited to the perturbations that the curved trajectories cause the beam-beam space charge nonlinearities. The question has arisen of how one defines the strength of the perturbation. The only solution is to compute the strength of the most important nonlinear resources. In what follows, the computational method used in calculating these resonances is described, and compared with those induced by random orbit errors.

103PD brachytherapy and external beam irradiation for clinically localized, high-risk prostatic carcinoma

International Nuclear Information System (INIS)

Dattoli, Michael; Wallner, Kent; Sorace, Richard; Koval, John; Cash, Jennifer; Acosta, Rudolph; Brown, Charles; Etheridge, James; Binder, Michael; Brunelle, Richard; Kirwan, Novelle; Sanchez, Servando; Stein, Douglas; Wasserman, Stuart

1996-01-01

Purpose: To summarize biochemical failure rates and morbidity of external beam irradiation (EBRT) combined with palladium ( 103 Pd) boost for clinically localized high-risk prostate carcinoma. Methods and Materials: Seventy-three consecutive patients with stage T2a-T3 prostatic carcinoma were treated from 1991 through 1994. Each patient had at least one of the following risk factors for extracapsular disease extension: Stage T2b or greater (71 patients), Gleason score 7-10 (40 patients), prostate specific antigen (PSA) >15 (32 patients), or elevated prostatic acid phosphatase (PAP) (17 patients). Patients received 41 Gy EBRT to a limited pelvic field, followed 4 weeks later by a 103 Pd boost (prescription dose: 80 Gy). Biochemical failure was defined as a PSA greater than 1.0 ng/ml (normal 103 Pd brachytherapy for clinically localized, high-risk prostate cancer compare favorably with that reported after conventional dose EBRT alone. Morbidity has been acceptable

Differentiated Thyroid Cancer with Extrathyroidal Extension: Prognosis and the Role of External Beam Radiotherapy

Directory of Open Access Journals (Sweden)

Michael A. Sia

2010-01-01

Full Text Available A study was performed to identify variables that affected cause-specific survival (CSS and local relapse-free rate (LRFR in patients with differentiated thyroid cancer (DTC and extrathyroid extension (ETE and to examine the role of external beam radiotherapy (XRT. Prognostic factors were similar to those found in studies of all patients with DTC. In patients with postoperative gross residual disease treated with radiotherapy, 10-year CSS and LRFR were 48% and 90%. For patients with no residual or microscopic disease, 10-year CSS and LRFR were 92% and 93%. In patients older than 60 years with T3 ETE but no gross residual disease postoperatively there was an improved LRFR at 5 years of 96%, compared to 87.5% without XRT (P=.02. Patients with gross ETE benefit from XRT and there may be a potential benefit in reducing locoregional failure in patients over 60 years with minimal extrathyroidal extension (T3.

Six fractions per week of external beam radiotherapy and high-dose-rate brachytherapy for carcinoma of the uterine cervix: A phase I/II study

International Nuclear Information System (INIS)

Yoon, Sang Min; Huh, Seung Jae; Park, Won; Lee, Jeung Eun; Park, Young Je; Nam, Hee Rim; Lim, Do Hoon; Ahn, Yong Chan

2006-01-01

Purpose: This study evaluated the treatment results of external beam radiotherapy administered in six fractions per week and high-dose-rate (HDR) brachytherapy for the treatment of cervical cancer. Methods and Materials: From July 2000 to July 2003, 43 patients were enrolled in this study. The patients received 45 Gy from a 10-MV photon beam using four-field box or anterior-posterior beams. Parametrial regions and the pelvic side walls were boosted with up to 50.4 Gy using a midline block. The daily fraction dose was 1.8 Gy administered in six-weekly fractions, from Monday to Saturday. HDR brachytherapy was also delivered at doses of 24 Gy to point A in six fractions twice a week. The median follow-up time was 37 months (range, 9-60 months). Results: The median overall treatment time was 51 days for all patients (range, 44-62 days). Thirty-four patients (79.1%) achieved complete remission and 8 (18.6%) achieved partial remission after radiotherapy. Locoregional recurrence occurred in 5 patients (11.6%), and a distant metastasis was encountered in 6 patients (13.9%). The 3-year overall survival, locoregional, and distant metastasis-free survival rates were 74.7%, 87.8%, and 84.7%, respectively. Grade 2 and 3 late rectal complications were encountered in 3 (6.5%) and 1 (2.2%), respectively. There were no Grade 3 late bladder complications. Conclusions: Six fractions per week of external beam radiotherapy and HDR brachytherapy is an effective treatment for patients with a carcinoma of the uterine cervix and can be used as a possible alternative to concomitant chemoradiotherapy in elderly patients or in patients with co-morbidity

Oncologic and functional outcome of base of tongue cancer treated with external-beam radiation and I-192 implant

International Nuclear Information System (INIS)

Harrison, L.B.; Sessions, R.B.; Strong, E.W.; Fass, D.E.; Armstrong, J.G.; Zelefsky, M.J.

1991-01-01

This paper assesses tumor control and functional outcome for squamous cancer of the base of the tongue managed with external irradiation plus Ir-192 implant. Between January 1981 and June 1990, 36 previously untreated patients were treated with 5,000-5,400 cGy of external-beam radiation plus a 2,000-3,000 cGy boost to the base of tongue with an Ir-192 implant. Negative necks were irradiated alone, and positive necks were treated with irradiation followed by neck dissection. Crude local control by T stage are as follows: T1, 10 of 11; T2, 13 of 14; T3, 8 of 10; and T4 1 of 1. Actuarial local control is 87.5%. Of the four local failures, two were salvaged by surgery. Neck control was achieved in 35 of 36 patients. Complications occurred in 25%. When implantation was done with the nonlooping technique, the injury rate was statistically higher than when done with the looping technique (6 of 12 = 50% vs 3 of 24 = 12.5%, P = .02)

An implantable radiation dosimeter for use in external beam radiation therapy

International Nuclear Information System (INIS)

Scarantino, Charles W.; Ruslander, David M.; Rini, Christopher J.; Mann, Gregory G.; Nagle, H. Troy; Black, Robert D.

2004-01-01

An implantable radiation dosimeter for use with external beam therapy has been developed and tested both in vitro and in canines. The device uses a MOSFET dosimeter and is polled telemetrically every day during the course of therapy. The device is designed for permanent implantation and also acts as a radiographic fiducial marker. Ten dogs (companion animals) that presented with spontaneous, malignant tumors were enrolled in the study and received an implant in the tumor CTV. Three dogs received an additional implant in collateral normal tissue. Radiation therapy plans were created for the animals and they were treated with roughly 300 cGy daily fractions until completion of the prescribed cumulative dose. The primary endpoints of the study were to record any adverse events due to sensor placement and to monitor any movement away from the point of placement. No adverse events were recorded. Unacceptable device migration was experienced in two subjects and a retention mechanism was developed to prevent movement in the future. Daily dose readings were successfully acquired in all subjects. A rigorous in vitro calibration methodology has been developed to ensure that the implanted devices maintain an accuracy of ±3.5% relative to an ionization chamber standard. The authors believe that an implantable radiation dosimeter is a practical and powerful tool that fosters individualized patient QA on a daily basis

Measure of the attenuation curve of a beam of X-rays with TLD-100 dosimeters of LiF; Medicion de la curva de atenuacion de un haz de rayos X con dosimetros TLD-100 de LiF

Energy Technology Data Exchange (ETDEWEB)

Bonzi, E. V.; Mainardi, R. T. [Universidad Nacional de Cordoba, Facultad de Matematica, Astronomia y Fisica, Av. Haya de la Torre y Av. Medina Allende s/n, Ciudad Universitaria, Cordoba (Argentina); Germanier, A. [Ministerio de Ciencia y Tecnologia, Ceprocor, Unidad de Estudios Fisicos, Alvarez de Arenas 230, X5004AAP Barrio Juniors, Cordoba (Argentina); Delgado, V. [Universidad Complutense de Madrid, Departamento de Fisica Medica, Ciudad Universitaria, 28040 Madrid (Spain)

2011-10-15

The attenuation curve of a beam of X-rays represents the beam intensity in function of the attenuator thickness interposed between the source and the detector. To know with the major possible precision the attenuation curve is indispensable in procedures of spectral reconstruction. Their periodic measuring also offers valuable information on the correct operation of a tube of X-rays, diagnostic or therapy, when not have a specific detector for that activity. In this work was measured the attenuation curve of a tube of X-rays operated to 50 kV and 0.5 ma, using existent elements in any diagnostic or therapy laboratory with radiations. In the measures commercial aluminum foil was used, bent until 24 times and thermoluminescent dosimeters TLD 100 - LiF. Also, for comparison, was measured this attenuation curve with an ionization chamber brand Capintec model 192. Was determined by X-rays fluorescence the composition of the aluminium foil, since the present elements in the alloy can to affect the form of the attenuation curve. It is interesting to observe that these elements are in very low proportion (ppm) that they do not alter the attenuation capacity of the pure aluminium. Finally in a precision balance we weigh a big piece (30 cm x 100 cm) of aluminium foil and we obtained the thickness in g/c m2. It is possible to obtain attenuation curves of a beam of X-rays, with a high precision procedure and reproducibility. The use of TLD-100 dosimeters of LiF or similar makes that this activity was also quick and simple. (Author)

SU-E-T-554: Comparison of Electron Disequilibrium Factor in External Photon Beams for Different Models of Linear Accelerators

International Nuclear Information System (INIS)

LIU, B; Zhu, T

2014-01-01

Purpose: The dose in the buildup region of a photon beam is usually determined by the transport of the primary secondary electrons and the contaminating electrons from accelerator head. This can be quantified by the electron disequilibrium factor, E, defined as the ratio between total dose and equilibrium dose (proportional to total kerma), E = 1 in regions beyond buildup region. Ecan be different among accelerators of different models and/or manufactures of the same machine. This study compares E in photon beams from different machine models/ Methods: Photon beam data such as fractional depth dose curve (FDD) and phantom scatter factors as a function of field size and phantom depth were measured for different Linac machines. E was extrapolated from these fractional depth dose data while taking into account inverse-square law. The ranges of secondary electron were chosen as 3 and 6 cm for 6 and 15 MV photon beams, respectively. The field sizes range from 2x2 to 40x40 cm 2 . Results: The comparison indicates the standard deviations of electron contamination among different machines are about 2.4 - 3.3% at 5 mm depth for 6 MV and 1.2 - 3.9% at 1 cm depth for 15 MV for the same field size. The corresponding maximum deviations are 3.0 - 4.6% and 2 - 4% for 6 and 15 MV, respectively. Both standard and maximum deviations are independent of field sizes in the buildup region for 6 MV photons, and slightly decreasing with increasing field size at depths up to 1 cm for 15 MV photons. Conclusion: The deviations of electron disequilibrium factor for all studied Linacs are less than 3% beyond the depth of 0.5 cm for the photon beams for the full range of field sizes (2-40 cm) so long as they are from the same manufacturer

Dosimetric characterization of VIPARnd gel by optical analysis to high-energy photon beam used in external radiotherapy

International Nuclear Information System (INIS)

Dias, Juliana R.; Lima, Renata S.; Lopes, Roseany de V. Vieira; Ceschin, Artemis Marti

2015-01-01

Polymer gel dosimetry has been proposed as a possibility for measurements of dose distribution in radiotherapy. This work aims to evaluate the dosimetric characteristics of a VIPARnd for 6 MV photon beam used in radiotherapy using optical investigations. The absorbance spectrum of irradiated gel dosimeter was optical evaluated with spectrophotometer techniques and with CMOS camera readout for dose range of 0 to 50 Gy. Data shows that the VIPARnd has a maximum absorbance at 300 to 320 nm depending on the absorbed dose. The CMOS camera readouts were obtained in RGB color, the absorbance measurements suggest a major response of dose for blue matrix verified with data. The dose-response curve for blue component showed interval of linearity from 1 Gy to 20 Gy. (author)

Improvement of the beam quality of a diode laser with two active broad-area segments

DEFF Research Database (Denmark)

Chi, Mingjun; Thestrup, B.; Mortensen, J.L.

2003-01-01

The beam quality of a diode laser with two active segments was improved using an external cavity with collimating optics, a grating, and an output coupler. The beam quality of the output beam, which is the first-order diffractive beam from the grating, was improved by a factor of 2, and at least...... half of the freely running power of the laser was coupled out from the external cavity. The output power can be enhanced further by the feedback from the zeroth-order beam. The possibility of improving the beam quality further is discussed and a new double-external-cavity configuration is suggested....

Prediction of the external work of the native heart from the dynamic H-Q curves of the rotary blood pumps during left heart bypass.

Science.gov (United States)

Yokoyama, Yoshimasa; Kawaguchi, Osamu; Kitao, Takashi; Kimura, Taro; Steinseifer, Ulrich; Takatani, Setsuo

2010-09-01

The ventricular performance is dependent on the drainage effect of rotary blood pumps (RBPs) and the performance of RBPs is affected by the ventricular pulsation. In this study, the interaction between the ventricle and RBPs was examined using the pressure-volume (P-V) diagram of the ventricle and dynamic head pressure-bypass flow (H-Q) curves (H, head pressure: arterial pressure minus ventricular pressure vs. Q, bypass flow) of the RBPs. We first investigated the relationships in a mock loop with a passive fill ventricle, followed by validation in ex vivo animal experiments. An apical drainage cannula with a micro-pressure sensor was especially fabricated to obtain ventricular pressure, while three pairs of ultrasonic crystals placed on the heart wall were used to derive ventricular volume. The mock loop-configured ventricular apical-descending aorta bypass revealed that the external work of the ventricle expressed by the area inside the P-V diagrams (EW(Heart) ) correlated strongly with the area inside dynamic H-Q curves (EW(VAD)), with the coefficients of correlation being R² = 0.869 ∼ 0.961. The results in the mock loop were verified in the ex vivo studies using three Shiba goats (10-25 kg in body weight), showing the correlation coefficients of R² = 0.802 ∼ 0.817. The linear regression analysis indicated that the increase in the bypass flow reduced pulsatility in the ventricle expressed in EW(Heart) as well as in EW(VAD) . Experimental results, both mock loop and animal studies, showed that the interaction between cardiac external work and H-Q performance of RBPs can be expressed by the relationships "EW(Heart) versus EW(VAD) ." The pulsatile nature of the native heart can be expressed in the area underneath the H-Q curves of RBPs EW(VAD) during left heart bypass indicating the status of the level of assistance by RBPs and the native heart function. © 2010, Copyright the Authors. Artificial Organs © 2010, International Center for Artificial Organs and

Rectification of light refraction in curved waveguide arrays.

Science.gov (United States)

Longhi, Stefano

2009-02-15

An "optical ratchet" for discretized light in photonic lattices, which enables observing rectification of light refraction at any input beam conditions, is theoretically presented, and a possible experimental implementation based on periodically curved zigzag waveguide arrays is proposed.

External beam techniques to boost cervical cancer when brachytherapy is not an option—theories and applications

Science.gov (United States)

Kilic, Sarah; Khan, Atif J.; Beriwal, Sushil; Small, William

2017-01-01

The management of locally advanced cervical cancer relies on brachytherapy (BT) as an integral part of the radiotherapy delivery armamentarium. Occasionally, intracavitary BT is neither possible nor available. In these circumstances, post-external beam radiotherapy (EBRT) interstitial brachytherapy and/or hysterectomy may represent viable options that must be adequately executed in a timely manner. However, if these options are not applicable due to patient related or facility related reasons, a formal contingency plan should be in place. Innovative EBRT techniques such as intensity modulated and stereotactic radiotherapy may be considered for patients unable to undergo brachytherapy. Relying on provocative arguments and recent data, this review explores the rationale for and limitations of non-brachytherapy substitutes in that setting aiming to establish a formal process for the optimal execution of this alternative plan. PMID:28603722

Beam induced vacuum measurement error in BEPC II

Institute of Scientific and Technical Information of China (English)

无

2011-01-01

When the beam in BEPCII storage ring aborts suddenly, the measured pressure of cold cathode gauges and ion pumps will drop suddenly and decrease to the base pressure gradually. This shows that there is a beam induced positive error in the pressure measurement during beam operation. The error is the difference between measured and real pressures. Right after the beam aborts, the error will disappear immediately and the measured pressure will then be equal to real pressure. For one gauge, we can fit a non-linear pressure-time curve with its measured pressure data 20 seconds after a sudden beam abortion. From this negative exponential decay pumping-down curve, real pressure at the time when the beam starts aborting is extrapolated. With the data of several sudden beam abortions we have got the errors of that gauge in different beam currents and found that the error is directly proportional to the beam current, as expected. And a linear data-fitting gives the proportion coefficient of the equation, which we derived to evaluate the real pressure all the time when the beam with varied currents is on.

Statistically generated weighted curve fit of residual functions for modal analysis of structures

Science.gov (United States)

Bookout, P. S.

1995-01-01

A statistically generated weighting function for a second-order polynomial curve fit of residual functions has been developed. The residual flexibility test method, from which a residual function is generated, is a procedure for modal testing large structures in an external constraint-free environment to measure the effects of higher order modes and interface stiffness. This test method is applicable to structures with distinct degree-of-freedom interfaces to other system components. A theoretical residual function in the displacement/force domain has the characteristics of a relatively flat line in the lower frequencies and a slight upward curvature in the higher frequency range. In the test residual function, the above-mentioned characteristics can be seen in the data, but due to the present limitations in the modal parameter evaluation (natural frequencies and mode shapes) of test data, the residual function has regions of ragged data. A second order polynomial curve fit is required to obtain the residual flexibility term. A weighting function of the data is generated by examining the variances between neighboring data points. From a weighted second-order polynomial curve fit, an accurate residual flexibility value can be obtained. The residual flexibility value and free-free modes from testing are used to improve a mathematical model of the structure. The residual flexibility modal test method is applied to a straight beam with a trunnion appendage and a space shuttle payload pallet simulator.

The influence of single and fractionated dose external beam irradiation on injury-induced arterial smooth muscle cell proliferation

International Nuclear Information System (INIS)

Schaefer, U.; Micke, O.; Dorszewski, A.; Breithardt, G.; Willich, N.

1997-01-01

Purpose/Objective: Restenosis after catheter-based revascularization has been demonstrated to be primarily caused by smooth muscle cell proliferation. This study examined the effects of external beam irradiation on neointimal proliferation after external injury to the central artery of the rabbit ear. Materials and Methods: 40 male New Zealand White rabbits were used in this study. Crush lesions were performed on each ear under general anesthesia and bilateral auricular nerve blockade. A single dose of 12 Gy (n=10), 16 Gy (n=10), or 20 Gy (n=10) and a fractionated dose of 4 x 5 Gy (n=10) gamma radiation was delivered to the left or right central artery of the ear 24 hours after injury; the contralateral central artery served as control. All rabbits were sacrificed after twenty-one days and the central arteries of the ear were fixed for morphometric measurements. Results: Mean (± SD) neointimal area was 0.062 ± 0.005 mm 2 (12 Gy), 0.022 ± 0,005 mm 2 (16 Gy), 0,028 ± 0,006 mm 2 and 0.038 mm 2 ± 0,02 mm 2 (4 x 5 Gy) in irradiated arteries compared with 0,081 ± 0,009 mm 2 in the control group. Mean (±SD) luminal area was 0.049 ± 0.004 mm 2 (12 Gy), 0.059 ± 0.002 mm 2 (16 Gy), 0.072 ± 0,006 mm 2 (20 Gy) and 0.048 mm 2 ± 0,018 mm 2 (4 x 5 Gy) in irradiated arteries compared with 0,043 ± 0,008 mm 2 in the control group. The difference in neointimal and luminal area between control and irradiated arteries was significant (p<0.05) only for the 16 and 20 Gy group compared to control. Conclusion: We conclude that in this model, external beam X-ray irradiation was successful in reducing neointimal proliferation after injury of the central artery of the rabbit ear. The optimal dose seems to be a single dose of 16 Gy - 20 Gy. Only a less prominent effect was noted for a fractionated dose of 4 x 5 Gy. Whether this approach can be used successfully to inhibit restenosis in the clinical setting requires further investigation

Spill control and intensity monitoring for the Bevatron--Bevalac external particle beams

International Nuclear Information System (INIS)

Barale, J.J.; Crebbin, K.C.

1975-03-01

Time-intensity modulation in beam spill can be of primary concern in some experiments. The major source of this beam structure is from main-guide field-magnet power supply ripple. If the time constants are appropriate, then final control of beam structure can be accomplished by closed loop control of the intensity of beam spill. The response characteristics of the feedback system will determine the final structure. At high beam fluxes signal to noise ratio of beam detectors, in the feedback loop, can be improved by at least four orders of magnitude by using photomultiplier tubes and a water Cherenkov counter in place of the normal secondary emission monitor. At beam fluxes below 10 10 particles per second (PPS), a plastic scintillator and photomultiplier tube are used in the feedback system. A plastic scintillator and photomultiplier are also used in the beam as intensity monitors. At intensities below about 10 7 PPS standard counting techniques are used. For intensities between 10 6 to 110 9 PPS, the photomultiplier is used as a current source driving an integrating circuit which is then calibrated to read the number of particles per pulse. (U.S.)

Rectification of light refraction in curved waveguide arrays

OpenAIRE

Longhi, S.

2010-01-01

An 'optical ratchet' for discretized light in photonic lattices, which enables to observe rectification of light refraction at any input beam conditions, is theoretically presented, and a possible experimental implementation based on periodically-curved zigzag waveguide arrays is proposed.

Holographic gratings in photorefractive polymers without external electric field

DEFF Research Database (Denmark)

Kukhtarev, N.; Lyuksyutov, S.; Buchhave, Preben

1997-01-01

Using anomalous large diffusion we report a recording of reflection type gratings in a PVK-based photorefractive polymer without any external electric field. The diffraction efficiency of the gratings was measured to be 7%. An efficient modulation of beams during two-beam coupling up to 12...

Signal amplification and Pierce's instability in convergent particle beams

International Nuclear Information System (INIS)

Gnavi, G.; Gratton, F.T.

1988-01-01

Relativistic electron beams flowing between cylindrical and spherical electrodes (or solid angles sections of electrodes with these geometries) are studied. The beams are focused through the axis in the cylindrical case or through the center when spherical electrodes are considered. It is assumed that the external electrode is part of a device which accelerates the particles, the inner electrode is passive and removes the beams from the system. Electrons move by inertia in the interelectrode space, neutralized by an ion background. Properties of radial, small amplitude, perturbations are analyzed theoretically. Previous analyses of counterstreaming beams indicated that convergence modifies considerably the oscillations spectrum. Here, results on the amplification of signals when a beam is modulated at the external electrode are reported. Then, conditions for the instability of a beam when it flows through grounded electrodes (Pierce's instability of only one beam) are examined

Megavoltage external beam irradiation of craniopharyngiomas: Analysis of tumor control and morbidity

International Nuclear Information System (INIS)

Flickinger, J.C.; Lunsford, L.D.; Singer, J.; Cano, E.R.; Deutsch, M.

1990-01-01

From 1971 to 1985, 21 patients received megavoltage external beam radiation therapy at the University of Pittsburgh for control of craniopharyngioma. Minimum tumor doses prescribed to the 95% isodose volume ranged between 51.3 to 70.0 Gy. Median total dose was 60.00 Gy and median dose per fraction was 1.83 Gy. Three deaths occurred from intercurrent disease and no deaths from tumor progression. Actuarial overall survival was 89% and 82% at 5 and 10 years. Actuarial local control was 95% at 5 and 10 years. Radiation related complications included one patient with optic neuropathy, one with brain necrosis, and one that developed optic neuropathy followed by brain necrosis. The high dose group of patients who received a NSD or Neuret equivalent of greater than 60 Gy at 1.8 Gy per fraction had a significantly greater risk of radiation complications (p = .024). The actuarial risk at 5 years for optic neuropathy was 30% and brain necrosis was 12.5% in the high dose group. Tumor control in the high dose group was not shown to be significantly better. Any possible benefit in tumor control in treating patients with craniopharyngioma with doses above 60 Gy at 1.8 Gy per fraction appears to be offset by the increased risk of radiation injury

The Antiproton Depth-Dose Curve in Water

DEFF Research Database (Denmark)

Bassler, Niels; Holzscheiter, Michael; Jäkel, Oliver

2008-01-01

We have measured the depth-dose curve of 126 MeV antiprotons in a water phantom using ionization chambers. Since the antiproton beam provided by CERN has a pulsed structure and possibly carries a high-LET component from the antiproton annihilation, it is necessary to correct the acquired charge...

EPI moved in beam S3

CERN Multimedia

1977-01-01

The housing of the External Particle Identifier (EPI) is being moved to S3 beam. Test measurements with EPI were performed in the S3 beam between 20 and 110 GeV/c, before installing it behind BEBC. 110 GeV/c before

American Brachytherapy Society Task Group Report: Combination of brachytherapy and external beam radiation for high-risk prostate cancer.

Science.gov (United States)

Spratt, Daniel E; Soni, Payal D; McLaughlin, Patrick W; Merrick, Gregory S; Stock, Richard G; Blasko, John C; Zelefsky, Michael J

To review outcomes for high-risk prostate cancer treated with combined modality radiation therapy (CMRT) utilizing external beam radiation therapy (EBRT) with a brachytherapy boost. The available literature for high-risk prostate cancer treated with combined modality radiation therapy was reviewed and summarized. At this time, the literature suggests that the majority of high-risk cancers are curable with multimodal treatment. Several large retrospective studies and three prospective randomized trials comparing CMRT to dose-escalated EBRT have demonstrated superior biochemical control with CMRT. Longer followup of the randomized trials will be required to determine if this will translate to a benefit in metastasis-free survival, disease-specific survival, and overall survival. Although greater toxicity has been associated with CMRT compared to EBRT, recent studies suggest that technological advances that allow better definition and sparing of critical adjacent structures as well as increasing experience with brachytherapy have improved implant quality and the toxicity profile of brachytherapy. The role of androgen deprivation therapy is well established in the external beam literature for high-risk disease, but there is controversy regarding the applicability of these data in the setting of dose escalation. At this time, there is not sufficient evidence for the omission of androgen deprivation therapy with dose escalation in this population. Comparisons with surgery remain limited by differences in patient selection, but the evidence would suggest better disease control with CMRT compared to surgery alone. Due to a series of technological advances, modern combination series have demonstrated unparalleled rates of disease control in the high-risk population. Given the evidence from recent randomized trials, combination therapy may become the standard of care for high-risk cancers. Copyright © 2016 American Brachytherapy Society. Published by Elsevier Inc. All

The importance of adequate follow-up in defining treatment success after external beam irradiation for prostate cancer

International Nuclear Information System (INIS)

Vicini, Frank A.; Kestin, Larry L.; Martinez, Alvaro A.

1999-01-01

Purpose: We reviewed our institution's experience treating patients with localized prostate cancer with external beam radiation therapy (RT) to determine how differences in the length of follow-up affect the determination of treatment outcome using the American Society for Therapeutic Radiology and Oncology (ASTRO) Consensus Panel Definition of biochemical failure (BF). Methods and Materials: From January 1987 through December 1997, 1109 patients with localized prostate cancer were treated with definitive external beam RT at William Beaumont Hospital, Royal Oak, Michigan. All patients received external beam RT to a median total prostate dose of 66.6 Gy (range: 59.4-70.4 Gy). A total of 1096 patients (99%) had sufficient prostate-specific antigen (PSA) follow-up to determine their biochemical status. To test the impact of differences in follow-up on the calculation of BF, 389 patients with at least 5 years of PSA follow-up were selected as the reference group for the initial analysis. BF was then retrospectively determined using the Consensus Panel definition at yearly intervals, ignoring the remainder of each patient's follow-up. The median follow-up for this group of patients was 6.6 years (range: 5.0-11.6 years). In a second analysis, patient cohorts were randomly selected with varying median PSA follow-up intervals in order to more accurately represent a population whose follow-up is distributed continuously over a defined range. Seven cohorts were randomly selected with 200 patients in each cohort. Cohorts were individually identified such that half of the patients (100) had 2 years or less follow-up than the stated time point for analysis and half (100) had up to 2 years more follow-up than the time point chosen for analysis. For example, in the cohort with a median follow-up of 3 years, 100 patients with a PSA follow-up from 1 to 3 years were randomly selected, and 100 patients with a follow-up from 3 to 5 years were randomly selected, thus generating a

MeV single-ion beam irradiation of mammalian cells using the Surrey vertical nanobeam, compared with broad proton beam and X-ray irradiations

Energy Technology Data Exchange (ETDEWEB)

Prakrajang, K. [Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Faculty of Science, Maejo University, Chiang Mai 50290 (Thailand); Jeynes, J.C.G.; Merchant, M.J.; Kirkby, K.; Kirkby, N. [Surrey Ion Beam Center, Faculty of Engineering and Physical Science, University of Surrey, Guildford Surrey, GU2 7XH (United Kingdom); Thopan, P. [Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Yu, L.D., E-mail: yuld@fnrf.science.cmu.ac.th [Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Thailand Center of Excellence in Physics, Commission on Higher Education, 328 Si Ayutthaya Road, Bangkok 10400 (Thailand)

2013-07-15

Highlights: •Recently completed nanobeam at the Surrey Ion Beam Centre was used. •3.8-MeV single and broad proton beams irradiated Chinese hamster cells. •Cell survival curves were measured and compared with 300-kV X-ray irradiation. •Single ion irradiation had a lower survival part at ultra-low dose. •It implies hypersensitivity, bystander effect and cell cycle phase of cell death. -- Abstract: As a part of a systematic study on mechanisms involved in physical cancer therapies, this work investigated response of mammalian cells to ultra-low-dose ion beam irradiation. The ion beam irradiation was performed using the recently completed nanobeam facility at the Surrey Ion Beam Centre. A scanning focused vertical ion nano-beam was applied to irradiate Chinese hamster V79 cells. The V79 cells were irradiated in two different beam modes, namely, focused single ion beam and defocused scanning broad ion beam of 3.8-MeV protons. The single ion beam was capable of irradiating a single cell with a precisely controlled number of the ions to extremely low doses. After irradiation and cell incubation, the number of surviving colonies as a function of the number of the irradiating ions was measured for the cell survival fraction curve. A lower survival for the single ion beam irradiation than that of the broad beam case implied the hypersensitivity and bystander effect. The ion-beam-induced cell survival curves were compared with that from 300-kV X-ray irradiation. Theoretical studies indicated that the cell death in single ion irradiation mainly occurred in the cell cycle phases of cell division and intervals between the cell division and the DNA replication. The success in the experiment demonstrated the Surrey vertical nanobeam successfully completed.

Incidence of primary hypothyroidism in patients exposed to therapeutic external beam radiation, where radiation portals include a part or whole of the thyroid gland

Directory of Open Access Journals (Sweden)

B A Laway

2012-01-01

Full Text Available Introduction: Hypothyroidism is a known consequence of external-beam radiotherapy to the neck encompassing a part or whole of the thyroid gland. In this non-randomized prospective study, we have tried to evaluate the response of the thyroid gland to radiation by assessing thyroid function before irradiation and at regular intervals after irradiation. Aims and Objectives: The aim of this study were to assess in the cancer patients, who were exposed to the therapeutic external beam radiation, where radiation portals include a part or whole of the thyroid gland: the incidence of primary hypothyroidism, the time required to become hypothyroid, any relation between the total dose for the development of hypothyroidism, and whether there are any patient or treatment-related factors that are predictive for the development of hypothyroidism, including the use of concurrent chemotherapy. Materials and Methods: This non-randomized, prospective study was conducted for a period of 2 years in which thyroid function was assessed in 59 patients (cases of head and neck cancer, breast cancer, lymphoma patients and other malignancies, who had received radiotherapy to the neck region. 59 euthyroid healthy patients (controls were also taken, who had not received the neck irradiation. These patients/controls were assessed periodically for 2 years. Results: The incidence of hypothyroidism after external beam radiation therapy (EBRT to neck where radiation portals include part or whole of the thyroid gland was 16.94%, seven cases had subclinical hypothyroidism (11.86% and three cases had clinical hypothyroidism (5.08%. Mean time for development of hypothyroidism was 4.5 months. There was no effect of age, gender, primary tumor site, radiation dose and chemotherapy, whether neoadjuvant or concurrent with the development of hypothyroidism. Conclusion: In summary, we found that thyroid dysfunction is a prevalent, yet easily treatable source of morbidity in patients

Elemental mapping of large samples by external ion beam analysis with sub-millimeter resolution and its applications

Science.gov (United States)

Silva, T. F.; Rodrigues, C. L.; Added, N.; Rizzutto, M. A.; Tabacniks, M. H.; Mangiarotti, A.; Curado, J. F.; Aguirre, F. R.; Aguero, N. F.; Allegro, P. R. P.; Campos, P. H. O. V.; Restrepo, J. M.; Trindade, G. F.; Antonio, M. R.; Assis, R. F.; Leite, A. R.

2018-05-01

The elemental mapping of large areas using ion beam techniques is a desired capability for several scientific communities, involved on topics ranging from geoscience to cultural heritage. Usually, the constraints for large-area mapping are not met in setups employing micro- and nano-probes implemented all over the world. A novel setup for mapping large sized samples in an external beam was recently built at the University of São Paulo employing a broad MeV-proton probe with sub-millimeter dimension, coupled to a high-precision large range XYZ robotic stage (60 cm range in all axis and precision of 5 μ m ensured by optical sensors). An important issue on large area mapping is how to deal with the irregularities of the sample's surface, that may introduce artifacts in the images due to the variation of the measuring conditions. In our setup, we implemented an automatic system based on machine vision to correct the position of the sample to compensate for its surface irregularities. As an additional benefit, a 3D digital reconstruction of the scanned surface can also be obtained. Using this new and unique setup, we have produced large-area elemental maps of ceramics, stones, fossils, and other sort of samples.

Influence of the external neutron sources in the criticality prediction using 1/M curve

Energy Technology Data Exchange (ETDEWEB)

Pereira, Valmir [COPPE/UFRJ, Programa de Engenharia Nuclear, Caixa Postal 68509, 21941-972 Rio de Janeiro (Brazil); Carvalho da Silva, Fernando [COPPE/UFRJ, Programa de Engenharia Nuclear, Caixa Postal 68509, 21941-972 Rio de Janeiro (Brazil); Martinez, Aquilino Senra [COPPE/UFRJ, Programa de Engenharia Nuclear, Caixa Postal 68509, 21941-972 Rio de Janeiro (Brazil)]. E-mail: aquilino@lmp.ufrj.br

2005-11-15

The influence of external neutron sources in the process to obtain the criticality condition is estimated. To reach this objective, the three-dimensional neutron diffusion equation in two groups of energy is solved, for a subcritical PWR reactor core with external neutron sources. The results are compared with the solution of the corresponding problem without external neutron sources, that is an eigenvalue problem. The method developed for this purposes it makes use of both the nodal method (for calculation of the neutron flux) and the finite differences method (for calculation of the adjoint flux). A coarse mesh finite difference method was developed for the adjoint flux calculation, which uses the output of the nodal expansion method. The results regarding the influence of the external neutron source presence for attaining criticality have shown that far from criticality it is necessary to calculate the reactivity values of the system.

Influence of the external neutron sources in the criticality prediction using 1/M curve

International Nuclear Information System (INIS)

Pereira, Valmir; Carvalho da Silva, Fernando; Martinez, Aquilino Senra

2005-01-01

The influence of external neutron sources in the process to obtain the criticality condition is estimated. To reach this objective, the three-dimensional neutron diffusion equation in two groups of energy is solved, for a subcritical PWR reactor core with external neutron sources. The results are compared with the solution of the corresponding problem without external neutron sources, that is an eigenvalue problem. The method developed for this purposes it makes use of both the nodal method (for calculation of the neutron flux) and the finite differences method (for calculation of the adjoint flux). A coarse mesh finite difference method was developed for the adjoint flux calculation, which uses the output of the nodal expansion method. The results regarding the influence of the external neutron source presence for attaining criticality have shown that far from criticality it is necessary to calculate the reactivity values of the system

Characteristics of therapeutic electron beams and their determination from depth dose curves

Energy Technology Data Exchange (ETDEWEB)

Novotny, J; Pernicka, F [Ceskoslovenska Akademie Ved, Prague. Ustav Dozimetrie Zareni

1980-09-01

The distribution of absorbed dose in the environment irradiated with broad beams of high-energy electrons is analyzed physically and therapeutically. A number of parameters are defined with the aid of which the beams of electrons may be characterized in great detail and compared. The theoretical calculations of individual parameters are compared with the values measured using the Ostron betatron in the central axis of the beam at a distance of 65 cm from the target; the differences found are ascribed to the spectrum of electrons, the scattering of electrons on the homogenizing foils, collimators, monitoring chambers, etc.

Locoregional recurrences following radical external beam irradiation and interstitial implantation for operable breast cancer - a twenty three year experience

International Nuclear Information System (INIS)

Leung, S.; Otmezguine, Y.; Calitchi, E.; Mazeron, J.J.; Le Bourgeois, J.P.; Pierquin, B.

1986-01-01

Locoregional recurrences are reported in 493 consecutive with T1 T2 N0 N1 breast cancer patients who were treated with radical external beam irradiation and interstitial 192 Ir implant between 1961 and 1979. Follow-up ranges from 5-23 years (mean 10 years) with 195 patients having 10-23 years follow up (mean 12 years). There were 51 (10%) locoregional recurrences with 34 mammary, 14 combined mammary/axillary and 3 isolated axillary recurrences. The 10 year relapse rate was 20/195 (10%). The results have been compared with other series in the literature and changes in the authors' current protocol are described. (Auth.)

Unresectable Retiform Hemangioendothelioma Treated with External Beam Radiation Therapy and Chemotherapy: A Case Report and Review of the Literature

Directory of Open Access Journals (Sweden)

Alina Z. Hirsh

2010-01-01

Full Text Available Retiform hemangioendothelioma (RH is an infrequently encountered vascular neoplasm of intermediate or borderline malignancy. Treatment of RH is controversial. We present a case of a 44-year-old Asian male presenting with an unresectable RH of the pelvis. The patient was treated with concurrent low-dose Cisplatin and External beam Radiation (4140cGy in 180cGy per fraction. This is the first report of a clinical complete response and a long-term local control of this rare tumor. This has significant clinical implication, since it gives the first evidence of treatment of this rare tumor using concurrent low-dose chemotherapy and radiation.

Simulation of the development and interaction of instabilities in a relativistic electron beam under variation of the beam wall thickness

Energy Technology Data Exchange (ETDEWEB)

Badarin, A. A.; Kurkin, S. A. [Saratov State University (Russian Federation); Koronovskii, A. A. [Yuri Gagarin State Technical University (Russian Federation); Rak, A. O. [Belorussian State University of Informatics and Radioelectronics (Belarus); Hramov, A. E., E-mail: hramovae@gmail.com [Saratov State University (Russian Federation)

2017-03-15

The development and interaction of Bursian and diocotron instabilities in an annular relativistic electron beam propagating in a cylindrical drift chamber are investigated analytically and numerically as functions of the beam wall thickness and the magnitude of the external uniform magnetic field. It is found that the interaction of instabilities results in the formation of a virtual cathode with a complicated rotating helical structure and several reflection regions (electron bunches) in the azimuthal direction. It is shown that the number of electron bunches in the azimuthal direction increases with decreasing beam wall thickness and depends in a complicated manner on the magnitude of the external magnetic field.

Temperature dependence of the beam-foil interaction

International Nuclear Information System (INIS)

Gay, T.J.; Berry, H.G.

1978-01-01

The beam energy dependence between 50 and 200 keV of the linear polarization fraction (M/I) of the 2s 1 S--3p 1 P, 5016 A transition in He I on temperature was measured. The thin carbon exciter foils were heated externally by nichrome resistance elements. The measurements of Hight et al. are duplicated; the energy and current dependences are the same for corresponding between beam heating and external heating. It was also observed that γ, the number of slow secondary electrons produced per incident ion, decreases with increasing foil temperature. These two effects, in conjunction, offer a plausible explanation for the variation of polarization with beam current density. 5 figures

Transient pressure and productivity analysis in carbonate geothermal reservoirs with changing external boundary flux

Directory of Open Access Journals (Sweden)

Wang Dongying

2017-01-01

Full Text Available In this paper, a triple-medium flow model for carbonate geothermal reservoirs with an exponential external boundary flux is established. The pressure solution under constant production conditions in Laplace space is solved. The geothermal wellbore pressure change considering wellbore storage and skin factor is obtained by Stehfest numerical inversion. The well test interpretation charts and Fetkovich production decline chart for carbonate geothermal reservoirs are proposed for the first time. The proposed Fetkovich production decline curves are applied to analyze the production decline behavior. The results indicate that in carbonate geothermal reservoirs with exponential external boundary flux, the pressure derivative curve contains a triple dip, which represents the interporosity flow between the vugs or matrix and fracture system and the invading flow of the external boundary flux. The interporosity flow of carbonate geothermal reservoirs and changing external boundary flux can both slow down the extent of production decline and the same variation tendency is observed in the Fetkovich production decline curve.

The antiproton depth–dose curve in water

CERN Document Server

Bassler, N; Jäkel, O; Knudsen, H V; Kovacevic, S

2008-01-01

We have measured the depth–dose curve of 126 MeV antiprotons in a water phantom using ionization chambers. Since the antiproton beam provided by CERN has a pulsed structure and possibly carries a high-LET component from the antiproton annihilation, it is necessary to correct the acquired charge for ion recombination effects. The results are compared with Monte Carlo calculations and were found to be in good agreement. Based on this agreement we calculate the antiproton depth–dose curve for antiprotons and compare it with that for protons and find a doubling of the physical dose in the peak region for antiprotons.

Intercomparison of radiotherapy treatment planning systems using calculated and measured dose distributions for external photon and electron beams

International Nuclear Information System (INIS)

Kosunen, A.; Jaervinen, H.; Vatnitskij, S.; Ermakov, I.; Chervjakov, A.; Kulmala, J.; Pitkaenen, M.; Vaeyrynen, T.; Vaeaenaenen, A.

1991-02-01

The requirement of 5 % overall accuracy for the target absorbed dose in radiotherapy implies that the accuracy of the relative dose calculation should be within only a few per cent. According to the recommendation by the International Commission on radiation units and measurements (ICRU), a computer-produced dose distribution can be considered to be accurate enough if it differs from the results of relative dose measurements by less than 2 %, or 2 mm in the position of isodose curves involving very steep dose gradients. In this study five treatment planning systems, currently used by the hospitals in Finland or in the USSR, were intercompared with respect to the above requirement. Five typical cases of irradiation were selected: regular fields, oblique incidence, irregular field, wedge field and inhomogeneity in a water equivalent phantom. Complete dose distributions were used for the intercomparison, and the beam data for each TPS was that pertaining to the beam where the comparative relative measurements were performed. The results indicate that the dose distributions produced by different TPS:s can differ from each other as well as from the measured dose distributions up to a level which is not acceptable in terms of the above requirement. Greatest differences seem to be related to the omission or undue consideration of the scatter components of the beam. A suitable quality assurance program for the systematic testing of the performance of the treatment planning systems could be based on a selection of tests as used in this study.(orig.)

Gamma-ray lasing by free nuclei and by matter-antimatter beams

International Nuclear Information System (INIS)

Rivlin, L.A.

1997-01-01

I discuss the possibilities to induce the gamma-ray emission departing from attempts to use the Moessbauer effect. Three separate approaches are considered: (A) Stimulated radiative transitions in deeply cooled nuclear beams with hidden inversion; (B) external two-photon ignition of nuclear lasing accompanied by gamma-ray giant pulse emission; and (C) burst-like radiative annihilation of relativistic beams of electrons and positrons or parapositronium atoms ignited by an external beam of soft photons

Ion beam generation and focusing

International Nuclear Information System (INIS)

Miller, P.A.; Mendel, C.W.; Swain, D.W.; Goldstein, S.A.

1975-01-01

Calculations have shown that efficiently generated and focused ion beams could have significant advantages over electron beams in achieving ignition of inertially-confined thermonuclear fuel. Efficient ion beam generation implies use of a good ion source and suppression of net electron current. Net electron flow can be reduced by allowing electrons to reflex through a highly transparent anode or by use of transverse magnetic fields (either beam self-fields or externally applied fields). Geometric focusing can be achieved if the beam is generated by appropriately shaped electrodes. Experimental results are presented which demonstrate ion beam generation in both reflexing and pinched-flow diodes. Spherically shaped electrodes are used to concentrate a proton beam, and target response to proton deposition is studied

Investigations on transport and storage of high ion beam intensities

International Nuclear Information System (INIS)

Joshi, Ninad Shrikrishna

2009-01-01

In the framework of this thesis the intense low energy ion beam transport was investigated. Especially, the beam transport in toroidal magnetic field configurations was discussed, as it may allow the accumulation of high intensive beams in the future. One of the specific tasks is to design an injection system that can be used for the proposed low energy accumulator ring. A simulation code (TBT) was written to describe the particle motion in curved segments. Particle in Cell techniques were utilized to simulate a multi particle dynamics. A possibility of reading an external data file was made available so that a measured distribution can be used to compare simulation results with measured ones. A second order cloud in cell method was used to calculate charge density and in turn to solve Poisson's equation. Further simulations were performed to study the self field effects on beam transport. Experiments were performed to compare the simulation results and gain practical experience. The preparatory experiments consisted of building and characterization of the ion source in a first step. Along with the momentum spectrometer and emittance scanner the beam properties were studied. Low mass ion beams He + and mixed p, H 2+ , H 3+ beams were analyzed. In the second stage, beams were transported through a solenoid and the phase space distribution was measured as a function of the magnetic field for different beam energies. The phase-space as distributions measured in a first stage were simulated backward and then again forward transported through the solenoid. The simulated results were then compared with the measured distribution. The LINTRA transport program was used. The phase-space distribution was further simulated for transport experiments in a toroidal magnetic field. The transport program that was used to simulate the beam in the toroid was also used to design the injection system. The injection system with its special field configurations was designed to perform

Investigations on transport and storage of high ion beam intensities

Energy Technology Data Exchange (ETDEWEB)

Joshi, Ninad Shrikrishna

2009-08-25

In the framework of this thesis the intense low energy ion beam transport was investigated. Especially, the beam transport in toroidal magnetic field configurations was discussed, as it may allow the accumulation of high intensive beams in the future. One of the specific tasks is to design an injection system that can be used for the proposed low energy accumulator ring. A simulation code (TBT) was written to describe the particle motion in curved segments. Particle in Cell techniques were utilized to simulate a multi particle dynamics. A possibility of reading an external data file was made available so that a measured distribution can be used to compare simulation results with measured ones. A second order cloud in cell method was used to calculate charge density and in turn to solve Poisson's equation. Further simulations were performed to study the self field effects on beam transport. Experiments were performed to compare the simulation results and gain practical experience. The preparatory experiments consisted of building and characterization of the ion source in a first step. Along with the momentum spectrometer and emittance scanner the beam properties were studied. Low mass ion beams He{sup +} and mixed p, H{sup 2+}, H{sup 3+} beams were analyzed. In the second stage, beams were transported through a solenoid and the phase space distribution was measured as a function of the magnetic field for different beam energies. The phase-space as distributions measured in a first stage were simulated backward and then again forward transported through the solenoid. The simulated results were then compared with the measured distribution. The LINTRA transport program was used. The phase-space distribution was further simulated for transport experiments in a toroidal magnetic field. The transport program that was used to simulate the beam in the toroid was also used to design the injection system. The injection system with its special field configurations was

Monte Carlo simulation of Varian Linac for 6 MV photon beam with BEAMnrc code

Science.gov (United States)

Mohammed, Maged; El Bardouni, T.; Chakir, E.; Boukhal, H.; Saeed, M.; Ahmed, Abdul-Aziz

2018-03-01

The purpose of this study is to investigate the effects of the initial electron beam parameters on the absorbed dose distribution calculated with EGSnrc Monte Carlo code, for 6 MV photon beam. A proposed methodology for benchmarking the BEAMnrc model of Varian Linac has been used. Also, a new photon cross section data based on ENDF/B-VII release 8 evaluation has been employed. The parameters tested include mean energy, radial intensity distribution and angular spread of the initial electron beam. Mean energy and angular spread were tested for a square irradiation field 10 × 10 cm2, whereas beam width of the electron beam was studied for 10 × 10 cm2 at different depths and 30 × 30 cm2 at depth of 10 cm. The results obtained are compared with measurement data to select the optimal electron beam parameters. The differences between MC calculation and measurements data are analyzed using gamma index criteria which fixed within 1% -1 mm accuracy. The obtained results indicated that the depth-dose and dose-profile curves were considerably influenced by the mean energy of the electron beam. The depth-dose curves were unaffected by the beam width of the electron beam, for both irradiation fields. On the contrary, lateral dose-profile curves were affected by the beam width of initial electron beam. Both dose-profile and depth-dose curves were unaffected to the angular spread of the electron beam. A deep depth of 10 × 10 cm2 is very accurate to tune the beam width. Mean energy and beam width must be tuned precisely, to get the MC does distribution with acceptable accuracy.

Cornell electron beam ion source

International Nuclear Information System (INIS)

Kostroun, V.O.; Ghanbari, E.; Beebe, E.N.; Janson, S.W.

1981-01-01

An electron beam ion source (EBIS) for the production of low energy, multiply charged ion beams to be used in atomic physics experiments has been designed and constructed. An external high perveance electron gun is used to launch the electron beam into a conventional solenoid. Novel features of the design include a distributed sputter ion pump to create the ultrahigh vacuum environment in the ionization region of the source and microprocessor control of the axial trap voltage supplies

Beam optics of the AmPS extraction line

International Nuclear Information System (INIS)

Hoekstra, R.

1991-01-01

The design of the Amsterdam Pulse Stretcher includes a feasibility study of part of the extraction trajectory. The latter includes some proposed curves projected through the hall of the beam switch yard. Since extraction is performed in the north line of the ring and the connection to the trajectory of the spectrometers is planned in a trajectory parallel to the east line of the ring the curves contain bending magnets for bending 90 degrees either by only two magnets or by making use of ring bending magnets in the same way as the ring curves are constructed. The bending through 90 degrees has optimal imaging properties of a unit cell much the same as the curves in the ring. This one-to-one (or one-to-minus-one) property is intended to shift the known required beam dimensions stream upwards from a defined point in the trajectory of the spectrometers to be able to create the dimensions at this shifted point by means of a so called beam transformer, placed in between the extraction point and this position. This report deals with the further developments with respect to the extraction trajectory. (author). 5 refs.; 9 figs.; 3 tabs

Parametric x-ray FEL operating with external Bragg reflectors

International Nuclear Information System (INIS)

Baryshevsky, V.G.; Batrakov, K.G.; Dubovskaya, I.Ya.

1995-01-01

In the crystal X-ray FELs using channeling and parametric quasi-Cherenkov mechanisms of spontaneous radiation were considered as versions of FEL allowing, in principle, to obtain coherent X-ray source. In this case a crystal is both radiator and resonator for X-rays emitted by a particle beam passing through crystal. However, it is well-known that a beam current density required for lasing is extremely high in X-ray spectral range for any radiation mechanisms and it is very important to find a way to lower its magnitude. The application of three-dimensional distributed feedback formed by dynamical diffraction of emitted photons permitted to reduce starting beam current density 10 2 -10 4 times up to 10 9 . One of ways to lower the starting current is the formation of multi-wave distributed feedback the another one is the application of external reflectors. The thing is that lasing regime was shown to be produced at frequencies in the vicinity of degeneration point for roots of dispersion equation describing radiation modes excited in an active medium (crystal plus particle beam). Unfortunately, in case of parametric quasi-Cherenkov FEL this region coincides with the region of strong self-absorption of radiation inside a crystal. That fact, obviously, increases the starting beam current. In this report we have shown that the application of external Bragg reflectors gives the possibility to lower radiation self-absorption inside a crystal by modifying radiation modes excited in the active medium under consideration. The corresponding dispersion equation and the expression for excited modes are derived. The generation equation determining starting conditions for lasing is obtained. Using these expressions we have shown that the application of external Bragg reflectors permits to reduce starting beam current density more than 10 times

Strengthening of structurally damaged wide shallow RC beams using externally bonded CFRP plates

Directory of Open Access Journals (Sweden)

Rajeh A. Al-Zaid

Full Text Available Reinforced concrete wide shallow beams (WSBs are commonly used in the joist flooring systems. The structural behavior of WSBs strengthened with carbon fiber reinforced polymer (CFRP reinforcement was studied on isolated beams and as part of full-scale building. The effect of structural damage on the performance of WSBs flexurally strengthened with CFRP plates was investigated and presented in this paper. Eight full-scale WSBs were tested under four-point bending up to failure. Seven beams were strengthened with CFRP plates bonded to the soffit of the beams and one beam was unstrengthened serving as control. Prior to strengthening, the beams were subjected to different levels of damaging by preloading to 30-95% of the beams' flexural capacity. One beam was fully damaged by preloading to failure and repaired before strengthening by replacing the crushed concrete. The data showed that the pre-damaged strengthened beams exhibited ultimate capacities up to 8% lower than those of the undamaged strengthened beams. However, the load carrying capacities of pre-damaged strengthened beams were more than those predicted by ACI 440 design guide, fib Bulletin 14, and JSCE design recommendations. Both fib Bulletin 14 and JSCE design recommendations gave very conservative predictions with average ratios of experimental to predicted ultimate capacity of 2.02 and 2.35, respectively. More accurate predictions were obtained by ACI 440 design guide as the corresponding ratio was 1.24. These results indicate that strong confidence and reliability can be placed in applying CFRP strengthening to structurally damaged WSBs.

Beam-smiling in bent-Laue monochromators

International Nuclear Information System (INIS)

Ren, B.; Dilmanian, F. A.; Wu, X. Y.; Huang, X.; Chapman, L. D.; Ivanov, I.; Zhong, Z.; Thomlinson, W. C.

1997-01-01

When a wide fan-shaped x-ray beam is diffracted by a bent crystal in the Laue geometry, the profile of the diffracted beam generally does not appear as a straight line, but as a line with its ends curved up or curved down. This effect, referred to as 'beam-smiling', has been a major obstacle in developing bent-Laue crystal monochromators for medical applications of synchrotron x-ray. We modeled a cylindrically bent crystal using the Finite Element Analysis (FEA) method, and we carried out experiments at the National Synchrotron Light Source and Cornell High Energy Synchrotron Source. Our studies show that, while beam-smiling exists in most of the crystal's area because of anticlastic bending effects, there is a region parallel to the bending axis of the crystal where the diffracted beam is 'smile-free'. By applying asymmetrical bending, this smile-free region can be shifted vertically away from the geometric center of the crystal, as desired. This leads to a novel method of compensating for beam-smiling. We will discuss the method of ''differential bending'' for smile removal, beam-smiling in the Cauchios and the polychromatic geometry, and the implications of the method on developing single- and double-bent Laue monochromators. The experimental results will be discussed, concentrating on specific beam-smiling observation and removal as applied to the new monochromator of the Multiple Energy Computed Tomography [MECT] project of the Medical Department, Brookhaven National Laboratory

A Doubly-Curved Piezoelectric Composite with 1-3 Connectivity for Underwater Transducer Applications

Science.gov (United States)

Zhang, Yanjun; Wang, Likun; Qin, Lei; Liao, Qingwei; Zhong, Chao

2018-03-01

Aim to increase the horizontal and vertical beam width of the high frequency transducer simultaneously, we present a doubly-curved 1-3 piezoelectric composite element. It consists of 54% piezoelectric ceramic volume fraction and two phases polymer matrix. The finite element analysis (FEA) is used to evaluate the dynamic response of composite. Electroacoustic response in water was measured for the doubly-curved composite being considered as underwater transducer. An underwater transducer was fabricated using the doubly-curved 1-3 piezoelectric composite element. The -3 dB full angle beam width of transducer is approximately 106° and 36° in the horizontal and vertical plane respectively. Both the FEA simulations and experimental results show the potential of a broad covered area of the composite transducer in underwater environment.

Potential for enhancing external beam radiotherapy for lung cancer using high-Z nanoparticles administered via inhalation

Science.gov (United States)

Hao, Yao; Altundal, Yucel; Moreau, Michele; Sajo, Erno; Kumar, Rajiv; Ngwa, Wilfred

2015-09-01

Nanoparticle-aided radiation therapy is emerging as a promising modality to enhance radiotherapy via the radiosensitizing action of high atomic number (Z) nanoparticles. However, the delivery of sufficiently potent concentrations of such nanoparticles to the tumor remain a challenge. This study investigates the dose enhancement to lung tumors due to high-Z nanoparticles (NPs) administered via inhalation during external beam radiotherapy. Here NPs investigated include: cisplatin nanoparticles (CNPs), carboplatin nanoparticles (CBNPs), and gold nanoparticles (GNPs). Using Monte Carlo-generated megavoltage energy spectra, a previously employed analytic method was used to estimate dose enhancement to lung tumors due to radiation-induced photoelectrons from the NPs administered via inhalation route (IR) in comparison to intravenous (IV) administration. Previous studies have indicated about 5% of FDA-approved cisplatin concentrations reach the lung via IV. Meanwhile recent experimental studies indicate that 3.5-14.6 times higher concentrations of NPs can reach the lung by IR compared to IV. Taking these into account, the dose enhancement factor (DEF) defined as the ratio of the radiotherapy dose with and without nanoparticles was calculated for a range of NPs concentrations and tumor sizes. The DEF for IR was then compared with that for IV. For IR with 3.5 times higher concentrations than IV, and 2 cm diameter tumor, clinically significant DEF values of up to 1.19, 1.26, and 1.51 were obtained for CNPs, CBNPs and GNPs. In comparison values of 1.06, 1.08, and 1.15 were obtained via IV administration. For IR with 14.6 times higher concentrations, even higher DEF values were obtained e.g. 1.81 for CNPs. Results also showed that the DEF increased with increasing field size or decreasing tumor volume, as expected. The results of this work indicate that IR administration of targeted high-Z CNPs/CBNPs/GNPs could enable clinically significant DEF to lung tumors compared to IV

Plasma flow in a curved magnetic field

International Nuclear Information System (INIS)

Lindberg, L.

1977-09-01

A beam of collisionless plasma is injected along a longitudinal magnetic field into a region of curved magnetic field. Two unpredicted phenomena are observed: The beam becomes deflected in the direction opposite to that in which the field is curved, and it contracts to a flat slab in the plane of curvature of the magnetic field. The phenomenon is of a general character and can be expected to occur in a very wide range of densities. The lower density limit is set by the condition for self-polarization, nm sub(i)/epsilon 0 B 2 >> 1 or, which is equivalent, c 2 /v 2 sub(A) >> 1, where c is the velocity of light, and v sup(A) the Alfven velocity. The upper limit is presumably set by the requirement ωsub(e)tau(e) >> 1. The phenomenon is likely to be of importance e.g. for injection of plasma into magnetic bottles and in space and solar physics. The paper illustrates the comlexity of plasma flow phenomena and the importance of close contact between experimental and theoretical work. (author)

The new external ion beam analysis setup at the Demokritos Tandem accelerator and first applications in cultural heritage

International Nuclear Information System (INIS)

Sokaras, Dimosthenis; Bistekos, Euthimios; Georgiou, Lambros; Salomon, Joseph; Bogovac, Mladen; Aloupi-Siotis, Eleni; Paschalis, Vasilis; Aslani, Ioanna; Karabagia, Sofia; Lagoyannis, Anastasios; Harissopulos, Sotirios; Kantarelou, Vasiliki; Karydas, Andreas-Germanos

2011-01-01

At the 5.5 MV Tandem VdG accelerator of the Institute of Nuclear Physics of N.C.S.R. 'Demokritos', Athens, Greece, an external ion-beam set-up has been recently developed and installed. The aim of this development was to integrate the analytical capabilities of the PIXE, RBS and PIGE ion beam techniques in one experimental set-up, so that to attain a complete elemental and near surface structural characterization of samples in an almost non-destructive way and without any limitation concerning their size or conductive state. A careful 3D mechanical drawing optimized the set-up experimental parameters achieving probe dimensions at the millimeter range (1 mm 2 ) and fulfilling the special requirements imposed for optimum performance of the aforementioned techniques, including the possibility to use heavier, than protons, ion beams. For the digital pulse processing of the X-ray, γ-ray and charged particle detector signals, novel hardware and software tools were developed based on a custom FPGA configuration. The first applications were focused in the quality control of materials that have been intentionally contaminated with a particular tracer-element ('tagged' materials). The tagged materials which were developed and tested are technologically authentic replicas of ancient attic ceramics with black glazed decoration. Analytical diagnostic studies were carried out for a few representative paintings of contemporary Greek painters in order to identify and document materials/pigments and techniques and eventually to prevent trade of fakes. Finally, ancient glass beads were also examined with respect to the sodium concentration and its in-depth homogeneity.

Nanostructures by ion beams

Science.gov (United States)

Schmidt, B.

Ion beam techniques, including conventional broad beam ion implantation, ion beam synthesis and ion irradiation of thin layers, as well as local ion implantation with fine-focused ion beams have been applied in different fields of micro- and nanotechnology. The ion beam synthesis of nanoparticles in high-dose ion-implanted solids is explained as phase separation of nanostructures from a super-saturated solid state through precipitation and Ostwald ripening during subsequent thermal treatment of the ion-implanted samples. A special topic will be addressed to self-organization processes of nanoparticles during ion irradiation of flat and curved solid-state interfaces. As an example of silicon nanocrystal application, the fabrication of silicon nanocrystal non-volatile memories will be described. Finally, the fabrication possibilities of nanostructures, such as nanowires and chains of nanoparticles (e.g. CoSi2), by ion beam synthesis using a focused Co+ ion beam will be demonstrated and possible applications will be mentioned.

Flexural Behavior of Self-Compacting RC Continuous Beams Strengthened by CFRP Sheets

Directory of Open Access Journals (Sweden)

Sabih Z. Al-Sarraf

2018-01-01

Full Text Available This search presented an experimental study of the flexural behavior of self-compacting reinforced concrete continuous beams externally strengthened by carbon fiber reinforced polymer (CFRP Sheets. The practical study contained eight self-compacting reinforced concrete continuous beams (with two span, each span had (1500 mm length and (150x250 mm cross sectional dimensions. Seven of these beams strengthened externally by CFRP sheets with and without external anchorage. The experimental variables included location of CFRP sheets and anchor type and location. The results, shows that the beams strengthened externally by CFRP sheets provided improvement in ultimate loads reached (60.71%. The usage of CFRP in the anchorage zone indicated an effective method in comparison to increasing the CFRP sheets lengths or extending them up to the support or under the loading points. Test results also showed that side strengthening provided an effective tool for increasing the load at the cracking stage and also the load capacity and reducing flexural crack widths.

Beam related response of in vivo diode detectors for external radiotherapy

Energy Technology Data Exchange (ETDEWEB)

Baci, Syrja, E-mail: sbarci2013@gmail.com [Department of Physics, Faculty of Natural Sciences, University of Gjirokastra, “Eqrem Çabej” (Albania); Telhaj, Ervis [Department of Medical Physics, Hygeia Hospital Tirana (Albania); Malkaj, Partizan [Department of Physical Engineering, Polytechnic University, Tirana (Albania)

2016-03-25

In Vivo Dosimetry (IVD) is a set of methods used in cancer treatment clinics to determine the real dose of radiation absorbed by target volume in a patient’s body. IVD has been widely implemented in radiotherapy treatment centers and is now recommended part of Quality Assurance program by many International health and radiation organizations. Because of cost and lack of specialized personnel, IVD has not been practiced as yet, in Albanian radiotherapy clinics. At Hygeia Hospital Tirana, patients are irradiated with high energy photons generated by Elekta Synergy Accelerators. We have recently started experimenting with the purpose of establishing an IVD practice at this hospital. The first set of experiments was aimed at calibration of diodes that are going to be used for IVD. PMMA, phantoms by PTW were used to calibrate p – type Si, semiconductor diode dosimeters, made by PTW Freiburg for entrance dose. Response of the detectors is affected by energy of the beam, accumulated radiation dose, dose rate, temperature, angle against the beam axis, etc. Here we present the work done for calculating calibration factor and correction factors of source to surface distance, field size, and beam incidence for the entrance dose for both 6 MV photon beam and 18 MV photon beam. Dependence of dosimeter response was found to be more pronounced with source to surface distance as compared to other variables investigated.

Beam related response of in vivo diode detectors for external radiotherapy

International Nuclear Information System (INIS)

Baci, Syrja; Telhaj, Ervis; Malkaj, Partizan

2016-01-01

In Vivo Dosimetry (IVD) is a set of methods used in cancer treatment clinics to determine the real dose of radiation absorbed by target volume in a patient’s body. IVD has been widely implemented in radiotherapy treatment centers and is now recommended part of Quality Assurance program by many International health and radiation organizations. Because of cost and lack of specialized personnel, IVD has not been practiced as yet, in Albanian radiotherapy clinics. At Hygeia Hospital Tirana, patients are irradiated with high energy photons generated by Elekta Synergy Accelerators. We have recently started experimenting with the purpose of establishing an IVD practice at this hospital. The first set of experiments was aimed at calibration of diodes that are going to be used for IVD. PMMA, phantoms by PTW were used to calibrate p – type Si, semiconductor diode dosimeters, made by PTW Freiburg for entrance dose. Response of the detectors is affected by energy of the beam, accumulated radiation dose, dose rate, temperature, angle against the beam axis, etc. Here we present the work done for calculating calibration factor and correction factors of source to surface distance, field size, and beam incidence for the entrance dose for both 6 MV photon beam and 18 MV photon beam. Dependence of dosimeter response was found to be more pronounced with source to surface distance as compared to other variables investigated.

Study of creep collapse of tubes subject to external pressure at elevated temperature

International Nuclear Information System (INIS)

Takikawa, N.

1982-01-01

Intermediate heat exchanger (IHX) tubes of VHTR form the boundary between the primary and secondary coolants of the reactor. The tubes are subject to external pressures at a postulated secondary coolant depressurization accident, which might lead to creep collapse. Therefore, it is necessary to ensure the integrity against creep collapse by analysis. The objective of this work is to study a simplified analytical method for predicting collapse time of a curved tube subjected to an external pressure. The study is made based on the comparison of experimental collapse time of curved and straight tubes. Creep collapse tests were conducted under an elevated temperature and an external pressure. Test results showed that curved tubes had longer collapse time than straight tubes with the same cross sectional ovality. The simplified analytical method for a curved tube is proposed in this report, which is to compute collapse time of a straight tube with the same ovality. And in this method the computed time is considered as collapse time of the curved tube. The above test results show that this simplified method gives the conservative collapse time. And it is confirmed by additional IHX tube tests that the method is applicable to creep collapse analysis of IHX tubes

Analytical Model for Fictitious Crack Propagation in Concrete Beams

DEFF Research Database (Denmark)

Ulfkjær, J. P.; Krenk, S.; Brincker, Rune

An analytical model for load-displacement curves of unreinforced notched and un-notched concrete beams is presented. The load displacement-curve is obtained by combining two simple models. The fracture is modelled by a fictitious crack in an elastic layer around the mid-section of the beam. Outside...... the elastic layer the deformations are modelled by the Timoshenko beam theory. The state of stress in the elastic layer is assumed to depend bi-lineary on local elongation corresponding to a linear softening relation for the fictitious crack. For different beam size results from the analytical model...... is compared with results from a more accurate model based on numerical methods. The analytical model is shown to be in good agreement with the numerical results if the thickness of the elastic layer is taken as half the beam depth. Several general results are obtained. It is shown that the point on the load...

External beam radiotherapy boosted with high dose rate brachytherapy in completely resected uterine sarcomas. Is this a treatment option?

Energy Technology Data Exchange (ETDEWEB)

Pellizzon, Antonio Cassio Assis; Novaes, Paulo Eduardo Ribeiro dos Santos; Maia, Maria Aparecida Conte; Ferrigno, Robson; Fogarolli, Ricardo; Salvajoli, Joao Vitor [Hospital de Cancer A.C. Camargo, Sao Paulo, SP (Brazil). Dept. de Oncologia de Radiacao]. E-mail: pellizzon@aol.com

2005-04-15

Uterine sarcoma (US) is a relative rare tumor, which accounts for only about 3-5% of all uterine cancers. Aggressive cytoreductive surgery at the time of the initial diagnosis with maximum tumor debulking may lead to a prolonged survival or cure. Objective: to identify and review the role of adjuvant external beam radiation therapy (EBRT) associated with high dose rate brachytherapy (HDRB) in the management of patients presenting US with complete resection. Material and methods: this study is a retrospective analysis of 23 patients with US treated from 10/92 to 03/03, with surgery, external beam radiation therapy (EBRT) and high dose rate brachytherapy (HDRB). The inclusion criteria for study participation included: histologically proven and graded US, completely resection of tumor, Karnofsky status 60-100, absence of significant infection, and recovery from recent surgery. Results: The median age of patients was 62 years (range 39-84); ten-year actuarial disease-free and overall survivals were 42.2% and 63.4%, respectively. On univariate analysis, predictive factors for disease-free survival (DFS) were age at initial presentation (p=0.0268), parity (p=0.0441), tumor grade (p= 0.0095), cervical or vaginal invasion (p=0.0014) and node dissection at time of surgery (p= 0.0471). On multivariate analysis, the only predictive factor was cervical or vaginal invasion (p= 0.048), hazard ratio of 4.7. Conclusion: it is quite likely that neither radiotherapy nor chemotherapy alone will appreciably improve survival in US. If radiation therapy provides better locoregional tumor control, hematogenous metastases will assume an even greater proportion of treatment failures. Unfortunately, our small and heterogeneous group analyzed precludes any definitive conclusions about the impact of HDRB associated to EBRT radiation therapy on recurrence or survival. (author)

External beam radiotherapy boosted with high dose rate brachytherapy in completely resected uterine sarcomas. Is this a treatment option?

International Nuclear Information System (INIS)

Pellizzon, Antonio Cassio Assis; Novaes, Paulo Eduardo Ribeiro dos Santos; Maia, Maria Aparecida Conte; Ferrigno, Robson; Fogarolli, Ricardo; Salvajoli, Joao Vitor

2005-01-01

Uterine sarcoma (US) is a relative rare tumor, which accounts for only about 3-5% of all uterine cancers. Aggressive cytoreductive surgery at the time of the initial diagnosis with maximum tumor debulking may lead to a prolonged survival or cure. Objective: to identify and review the role of adjuvant external beam radiation therapy (EBRT) associated with high dose rate brachytherapy (HDRB) in the management of patients presenting US with complete resection. Material and methods: this study is a retrospective analysis of 23 patients with US treated from 10/92 to 03/03, with surgery, external beam radiation therapy (EBRT) and high dose rate brachytherapy (HDRB). The inclusion criteria for study participation included: histologically proven and graded US, completely resection of tumor, Karnofsky status 60-100, absence of significant infection, and recovery from recent surgery. Results: The median age of patients was 62 years (range 39-84); ten-year actuarial disease-free and overall survivals were 42.2% and 63.4%, respectively. On univariate analysis, predictive factors for disease-free survival (DFS) were age at initial presentation (p=0.0268), parity (p=0.0441), tumor grade (p= 0.0095), cervical or vaginal invasion (p=0.0014) and node dissection at time of surgery (p= 0.0471). On multivariate analysis, the only predictive factor was cervical or vaginal invasion (p= 0.048), hazard ratio of 4.7. Conclusion: it is quite likely that neither radiotherapy nor chemotherapy alone will appreciably improve survival in US. If radiation therapy provides better locoregional tumor control, hematogenous metastases will assume an even greater proportion of treatment failures. Unfortunately, our small and heterogeneous group analyzed precludes any definitive conclusions about the impact of HDRB associated to EBRT radiation therapy on recurrence or survival. (author)

tion using external beam radiation in gynaecological cancers

African Journals Online (AJOL)

Enrique

The purpose of the modified technique is: (i) to accurately assess the lower extent of the disease and define the lower border of the external radiation field in both the anteropos- terior/ posteroanterior (AP/PA) and lateral fields; and (ii) to decrease the field size and reduce treatment-related side-effects. Methods and materials.

Relative level populations in S VI after beam-foil excitation, obtained from ANDC analyses of measured decay curves

International Nuclear Information System (INIS)

Engstroem, L.

1983-01-01

This paper reports the relative population of the levels 3p, 3d, 4d, 5d, 4f, 5g, 6g, 6h, 7h, 7i, 8i and 8k in Na-like sulfur, S VI, after beam-foil excitation at an energy of 3 MeV. For the first time the ANDC technique has been used to obtain the relative efficiency calibration of the detection system at discrete points in the wavelength interval 400-5000 A, from the analyses of measured decay curves. The advantages and limitations of this method are discussed. The populations obtained with this new technique are compared to previous measurements in multiply ionized atoms. The preferential population of the 3p and 3d levels observed in other Na-like ions is now accurately established. For the higher lying levels an almost constant population is observed. (Auth.)

Optimal Treatment of Malignant Long Bone Fracture: Influence of Method of Repair and External Beam Irradiation on the Pathway and Efficacy of Fracture Healing

Science.gov (United States)

2015-10-01

stiffness, or a partial snap with lower yield force and stiffness (Figure 4). Three dimensional micro CT analysis around fracture Figure 3. (a-b... fractures with plate fixation on both sides and irradiation on the left while the contralateral limb serves as a non-radiated internal control. The...AWARD NUMBER: W81XWH-13-1-0430 TITLE: Optimal Treatment of Malignant Long Bone Fracture : Influence of Method of Repair and External Beam

Treatment of locally advanced breast carcinoma with high-dose external beam supervoltage radiotherapy

International Nuclear Information System (INIS)

Brufman, G.; Weshler, Z.; Prosnitz, L.R.; Fuks, Z.

1981-01-01

Between 1960 and 1978, 87 patients with locally advanced Tsub(3-4)Nsub(0-3)M 0 carcinoma of the breast were treated with 5,000 to 8,000 rad of external beam supervoltage radiotherapy. Initial clinical eradication of the tumour was observed in 76 of 87 cases (87%), but the actuarial probability of local control at 5 yr was only 53%. Furthermore, the actuarial probability of disease-free survival was 25% at 5 yr and 13% at 10 yr. Most of the patients eventually succumbed to metastatic breast carcinoma and the actuarial survival at 5 yr was 43% and at 10 yr, 16%. The addition of adjuvant low-dose chemotherapy, given to 13 patients, did not affect the rates of local control, survival or disease-free survival. The most common long-term complication was extensive and deforming radiation-induced fibrosis of the treated breast. The actuarial probability of 10-yr survival without a local recurrence and without severe fibrosis of the treated breast was only 17.5%. The role of adjuvant high-dose chemotherapy in the treatment of locally advanced breast carcinoma and the possible use of improved radiotherapy techniques to achieve a more effective long-term local control and a more desirable cosmetic end result are discussed. (author)

Time of Decline in Sexual Function After External Beam Radiotherapy for Prostate Cancer

International Nuclear Information System (INIS)

Siglin, Joshua; Kubicek, Gregory J.; Leiby, Benjamin; Valicenti, Richard K.

2010-01-01

Purpose: Erectile dysfunction is one of the most concerning toxicities for patients in the treatment of prostate cancer. The inconsistent evaluation of sexual function (SF) and limited follow-up data have necessitated additional study to clarify the rate and timing of erectile dysfunction after external beam radiotherapy (EBRT) for prostate cancer. Methods and Materials: A total of 143 men completed baseline data on SF before treatment and at the subsequent follow-up visits. A total of 1187 validated SF inventories were analyzed from the study participants. Multiple domains of SF (sex drive, erectile function, ejaculatory function, and overall satisfaction) were analyzed for ≤8 years of follow-up. Results: The median follow-up was 4.03 years. The strongest predictor of SF after EBRT was SF before treatment. For all domains of SF, the only statistically significant decrease in function occurred in the first 24 months after EBRT. SF stabilized 2 years after treatment completion, with no statistically significant change in any area of SF >2 years after the end of EBRT. Conclusion: These data suggest that SF does not have a continuous decline after EBRT. Instead, SF decreases maximally within the first 24 months after EBRT, with no significant changes thereafter.

Beam tuning parameters for the Kolkata superconducting cyclotron

International Nuclear Information System (INIS)

Debnath, J.; Dey, M.K.; Paul, S.; Pradhan, J.; Bhunia, U.; Dutta, A.; Agrawal, A.; Naser, Md. Z.A.; Rashid, M.H.; Mallik, C.; Bhandari, R.K.

2009-01-01

The internal beam tuning in the Superconducting cyclotron at VECC will be started very soon. The magnetic field data has been used to explore the beam dynamical issues. There are two main coils and fourteen no. of trim coils. The optimised main coil and trim coil current settings for producing the required near-isochronous field fitting suitable phase-energy curve to accelerate different ion species in the operating region with minimum trim coil power as well as minimum error in the energy-phase curve have been calculated and reported here. The equilibrium orbit properties i.e., the radial and axial focusing frequencies, frequency error, integrated phase shift etc. have been studied. The important issues related to beam deliverables are explored. (author)

External-beam PIXE spectrometry for the study of Punic jewellery (SW Spain): The geographical provenance of the palladium-bearing gold

International Nuclear Information System (INIS)

Ontalba Salamanca, M.A.; Gomez-Tubio, B.; Ortega-Feliu, I.; Respaldiza, M.A.; Luisa de la Bandera, M.; Ovejero Zappino, G.; Bouzas, A.; Gomez-Moron, A.

2006-01-01

This paper presents the study of a set of Punic gold items (400 B.C.), from the Museum of Cadiz (Spain). An external beam set-up has been employed for the absolutely non-destructive analysis of the objects. PIXE spectrometry has been performed in order to characterize the metallic alloys and the manufacturing techniques. Compositional differences have been found and soldering procedures have been identified. By comparison with the rings and other coetaneous jewellery, the presence of palladium in the bulk alloy of the earrings can be pointed out. The geographical provenance of the palladium-bearing gold is discussed based on geological and archaeological considerations

External-beam PIXE spectrometry for the study of Punic jewellery (SW Spain): The geographical provenance of the palladium-bearing gold

Energy Technology Data Exchange (ETDEWEB)

Ontalba Salamanca, M.A. [Departamento de Fisica, Escuela Politecnica, Universidad de Extremadura, Avda. de la Universidad s/n., 10071 Caceres (Spain)]. E-mail: ontalba@unex.es; Gomez-Tubio, B. [Centro Nacional de Aceleradores, Sevilla (Spain); Ortega-Feliu, I. [Centro Nacional de Aceleradores, Sevilla (Spain); Respaldiza, M.A. [Centro Nacional de Aceleradores, Sevilla (Spain); Luisa de la Bandera, M. [Departamento de Arqueologia, Universidad de Sevilla (Spain); Ovejero Zappino, G. [Cobre Las Cruces SA, Gerena, Sevilla (Spain); Bouzas, A. [Instituto Andaluz de Patrimonio Historico, Sevilla (Spain); Gomez-Moron, A. [Instituto Andaluz de Patrimonio Historico, Sevilla (Spain)

2006-08-15

This paper presents the study of a set of Punic gold items (400 B.C.), from the Museum of Cadiz (Spain). An external beam set-up has been employed for the absolutely non-destructive analysis of the objects. PIXE spectrometry has been performed in order to characterize the metallic alloys and the manufacturing techniques. Compositional differences have been found and soldering procedures have been identified. By comparison with the rings and other coetaneous jewellery, the presence of palladium in the bulk alloy of the earrings can be pointed out. The geographical provenance of the palladium-bearing gold is discussed based on geological and archaeological considerations.

Characterization of a multilayer ionization chamber prototype for fast verification of relative depth ionization curves and spread-out-Bragg-peaks in light ion beam therapy.

Science.gov (United States)

Mirandola, Alfredo; Magro, Giuseppe; Lavagno, Marco; Mairani, Andrea; Molinelli, Silvia; Russo, Stefania; Mastella, Edoardo; Vai, Alessandro; Maestri, Davide; La Rosa, Vanessa; Ciocca, Mario

2018-05-01

To dosimetrically characterize a multilayer ionization chamber (MLIC) prototype for quality assurance (QA) of pristine integral ionization curves (ICs) and spread-out-Bragg-peaks (SOBPs) for scanning light ion beams. QUBE (De.Tec.Tor., Torino, Italy) is a modular detector designed for QA in particle therapy (PT). Its main module is a MLIC detector, able to evaluate particle beam relative depth ionization distributions at different beam energies and modulations. The charge collecting electrodes are made of aluminum, for a nominal water equivalent thickness (WET) of ~75 mm. The detector prototype was calibrated by acquiring the signals in the initial plateau region of a pristine BP and in terms of WET. Successively, it was characterized in terms of repeatability response, linearity, short-term stability and dose rate dependence. Beam-induced measurements of activation in terms of ambient dose equivalent rate were also performed. To increase the detector coarse native spatial resolution (~2.3 mm), several consecutive acquisitions with a set of certified 0.175-mm-thick PMMA sheets (Goodfellow, Cambridge Limited, UK), placed in front of the QUBE mylar entrance window, were performed. The ICs/SOBPs were achieved as the result of the sum of the set of measurements, made up of a one-by-one PMMA layer acquisition. The newly obtained detector spatial resolution allowed the experimental measurements to be properly comparable against the reference curves acquired in water with the PTW Peakfinder. Furthermore, QUBE detector was modeled in the FLUKA Monte Carlo (MC) code following the technical design details and ICs/SOBPs were calculated. Measurements showed a high repeatability: mean relative standard deviation within ±0.5% for all channels and both particle types. Moreover, the detector response was linear with dose (R 2  > 0.998) and independent on the dose rate. The mean deviation over the channel-by-channel readout respect to the reference beam flux (100%) was equal

Beam-smiling in bent-Laue monochromators

International Nuclear Information System (INIS)

Ren, B.; Dilmanian, F.A.; Wu, X.Y.; Huang, X.; Ivanov, I.; Thomlinson, W.C.

1997-01-01

When a wide fan-shaped x-ray beam is diffracted by a bent crystal in the Laue geometry, the profile of the diffracted beam generally does not appear as a straight line, but as a line with its ends curved up or curved down. This effect, referred to as ' beam-smiling', has been a major obstacle in developing bent-Laue crystal monochromators for medical applications of synchrotron x-ray. We modeled a cylindrically bent crystal using the Finite Element Analysis (FEA) method, and we carried out experiments at the National Synchrotron Light Source and Cornell High Energy Synchrotron Source. Our studies show that, while beam-smiling exists in most of the crystal close-quote s area because of anticlastic bending effects, there is a region parallel to the bending axis of the crystal where the diffracted beam is ' smile-free'. By applying asymmetrical bending, this smile-free region can be shifted vertically away from the geometric center of the crystal, as desired. This leads to a novel method of compensating for beam-smiling. We will discuss the method of ' differential bending' for smile removal, beam-smiling in the Cauchios and the polychromatic geometry, and the implications of the method on developing single- and double-bent Laue monochromators. The experimental results will be discussed, concentrating on specific beam-smiling observation and removal as applied to the new monochromator of the Multiple Energy Computed Tomography [MECT] project of the Medical Department, Brookhaven National Laboratory. copyright 1997 American Institute of Physics

External dosimetry sources and shielding

International Nuclear Information System (INIS)

Calisto, Washington

1994-01-01

A definition of external dosimetry r external sources dosimetry,physical and mathematical treatment of the interaction of gamma radiation with a minimal area in that direction. Concept of attenuation coefficient, cumulated effect by polyenergetic sources, exposition rate, units, cumulated dose,shielding, foton shielding, depth calculation, materials used for shielding.Beta shielding, consideration of range and maximum β energy , low stopping radiation by use of low Z shielding. Tables for β energy of β emitters, I (tau) factor, energy-range curves for β emitters in aqueous media, gamma attenuation factors for U, W and Pb. Y factor for bone tissue,muscle and air, build-up factors

External injection systems applied in modern cyclotrons designed and manufactured in NIIEFA

International Nuclear Information System (INIS)

Bogdanov, P.V.; Vasilchenko, I.N.; Veresov, O.L.; Gavrish, Yu.N.; Grigorenko, S.V.; Zuev, Yu.V.; Kozienko, M.T.; Mudrolyubov, V.G.; Strokach, A.P.; Tsygankov, S.S.

2012-01-01

The main parameters and design features of the external injection systems applied in modern cyclotrons designed and manufactured in NIIEFA and intended for production of radionuclides for medicine are presented. The use of these external injection systems instead of a traditional internal source allows the current of the accelerated beam to be significantly increased and the in-leakage of the working gas to the acceleration chamber to be reduced, which results in reduced beam losses in the process of acceleration and lower equipment activation.

Multiobjective optimization with a modified simulated annealing algorithm for external beam radiotherapy treatment planning

International Nuclear Information System (INIS)

Aubry, Jean-Francois; Beaulieu, Frederic; Sevigny, Caroline; Beaulieu, Luc; Tremblay, Daniel

2006-01-01

Inverse planning in external beam radiotherapy often requires a scalar objective function that incorporates importance factors to mimic the planner's preferences between conflicting objectives. Defining those importance factors is not straightforward, and frequently leads to an iterative process in which the importance factors become variables of the optimization problem. In order to avoid this drawback of inverse planning, optimization using algorithms more suited to multiobjective optimization, such as evolutionary algorithms, has been suggested. However, much inverse planning software, including one based on simulated annealing developed at our institution, does not include multiobjective-oriented algorithms. This work investigates the performance of a modified simulated annealing algorithm used to drive aperture-based intensity-modulated radiotherapy inverse planning software in a multiobjective optimization framework. For a few test cases involving gastric cancer patients, the use of this new algorithm leads to an increase in optimization speed of a little more than a factor of 2 over a conventional simulated annealing algorithm, while giving a close approximation of the solutions produced by a standard simulated annealing. A simple graphical user interface designed to facilitate the decision-making process that follows an optimization is also presented

Dose behind various immobilization and beam-modifying devices

International Nuclear Information System (INIS)

Mellenberg, David E.

1995-01-01

Purpose: To quantify the degradation of skin sparing associated with using beam modifiers such as compensators, immobilization devices, and custom blocks for high energy photon beams. Methods and Materials: The degradation of skin sparing was quantified by measuring dose build-up curves with an extrapolation chamber for 6 and 15 MV photon beams. Uniform thickness compensators made of gypsum and lead, thermoplastic mask material, immobilization cradle foam, and cerrobend custom blocks were placed in geometries that mimic relevant clinical situations. Results: Compensators, whether made of gypsum or lead, placed in the linear accelerator's wedge slot did not significantly effect the depth dose curve's build-up region. Immobilization devices such as cradle foam or thermoplastic placed in contact with the patient degrade the skin sparing expected from high energy photon beams proportional to their thickness and density. Measurements behind custom blocks show that surface and near surface doses for a blocked field are best described by build-up curves for an equivalent size open field. Conclusions: These results allow explanation and possibly prediction of skin reactions on patients in which compensators, foam immobilization cradles, thermoplastic masks, or custom blocks are used. These results also provide a baseline by which substitute materials can be evaluated

Prevalence and Predicting Factors for Commonly Neglected Sexual Side Effects to External-Beam Radiation Therapy for Prostate Cancer.

Science.gov (United States)

Frey, Anders; Pedersen, Christian; Lindberg, Henriette; Bisbjerg, Rasmus; Sønksen, Jens; Fode, Mikkel

2017-04-01

Changes in sexual function other than erectile dysfunction are sparsely investigated after radiation therapy for prostate cancer. To investigate orgasmic dysfunction, urinary incontinence during sexual activity, changes in penile morphology, and sensory disturbances in the penis in patients with prostate cancer treated with external-beam radiation therapy (EBRT). In February 2015, men treated with EBRT at our center 3 months to 5 years previously (N = 519) received a study-specific questionnaire. This was developed from purpose-built questions and validated tools including the Erection Hardness Scale. All patients had received a radiation dose of 78 Gy. Androgen deprivation therapy was administered according to disease characteristics. Outcome measurements were prevalence rates and predictors of these side effects as identified by multivariate logistic regression analyses. One hundred nine patients were eligible (sexually active and had completed androgen deprivation therapy) for inclusion. Twenty-four percent reported anorgasmia, 44% reported a decreased intensity of their orgasms, and 40% reported that the time it took to reach orgasm had increased. Eleven percent reported anejaculation. Fifteen percent reported orgasm-associated pain. Only 4% reported urinary incontinence during sexual activity. Subjective penile length loss in excess of 1 cm was reported by 42%. Twelve percent reported an altered curvature of their penis after EBRT. Six percent reported painful erections. Twenty-seven percent reported decreased sensitivity in the penis after EBRT, 2% reported a cold sensation, and 2% reported paresthesia. Increasing time since final treatment increased the risk of penile sensory disturbances (odds ratio = 1.05; P = .028). Orgasmic dysfunction, changes in penile morphology, and sensory disturbances in the penis are common side effects of ERBT. Patients should be properly informed of the occurrence of these side effects before deciding which treatment to

Risk of Fatal Cerebrovascular Accidents after External Beam Radiation Therapy for Early Stage Glottic Larynx Cancer

Science.gov (United States)

Swisher-McClure, Samuel; Mitra, Nandita; Lin, Alexander; Ahn, Peter; Wan, Fei; O’Malley, Bert; Weinstein, Gregory S.; Bekelman, Justin E.

2013-01-01

Background This study compared the risk of fatal cerebrovascular accidents (CVA) in patients with early stage glottic larynx cancer receiving surgery or external beam radiation therapy (EBRT). Methods and Materials Using a competing risks survival analysis, we compared the risk of death due to CVA among patients with early stage glottic larynx cancer receiving surgery or EBRT in the SEER database. Results The cumulative incidence of fatal CVA at 15 years was higher in patients receiving EBRT (2.8 %; 95% CI 2.3%–3.4%) compared to surgery (1.5 %; 95% CI 0.8 %–2.3%, p= 0.024). In multivariable competing risks regression models, EBRT remained associated with an increased risk of fatal CVA compared to surgery (adjusted HR 1.75; 95% CI 1.04–2.96, p= 0.037). Conclusion Treatment of early stage glottic larynx cancer with EBRT was associated with a small increase in the risk of late fatal CVA events relative to surgery. PMID:23595858

Improvements to the internal and external antenna H(-) ion sources at the Spallation Neutron Source.

Science.gov (United States)

Welton, R F; Dudnikov, V G; Han, B X; Murray, S N; Pennisi, T R; Pillar, C; Santana, M; Stockli, M P; Turvey, M W

2014-02-01

The Spallation Neutron Source (SNS), a large scale neutron production facility, routinely operates with 30-40 mA peak current in the linac. Recent measurements have shown that our RF-driven internal antenna, Cs-enhanced, multi-cusp ion sources injects ∼55 mA of H(-) beam current (∼1 ms, 60 Hz) at 65-kV into a Radio Frequency Quadrupole (RFQ) accelerator through a closely coupled electrostatic Low-Energy Beam Transport system. Over the last several years a decrease in RFQ transmission and issues with internal antennas has stimulated source development at the SNS both for the internal and external antenna ion sources. This report discusses progress in improving internal antenna reliability, H(-) yield improvements which resulted from modifications to the outlet aperture assembly (applicable to both internal and external antenna sources) and studies made of the long standing problem of beam persistence with the external antenna source. The current status of the external antenna ion source will also be presented.

Preirradiation PSA predicts biochemical disease-free survival in patients treated with postprostatectomy external beam irradiation

International Nuclear Information System (INIS)

Crane, Christopher H.; Rich, Tyvin A.; Read, Paul W.; Sanfilippo, Nicholas J.; Gillenwater, Jay Y.; Kelly, Maria D.

1997-01-01

Purpose: To assess the clinical outcome and prostate-specific antigen (PSA) response and to determine prognostic factors for biochemical disease-free survival in patients treated with external beam radiotherapy following radical prostatectomy without hormonal therapy. Methods and Materials: Forty-eight patients were treated after prostatectomy with radiotherapy between March, 1988 and December, 1993. Seven patients had undetectable PSA ( 2.7. Five-year actuarial biochemical disease-free survival values were 71, 48, and 0%, respectively, for the three groups. Biochemical disease-free survival was not affected by preoperative PSA level, clinical stage, Gleason's score, pathologic stage, surgical margins, presence of undetectable PSA after surgery, surgery to radiation interval, total dose, or presence of clinically suspicious local disease. Based on digital rectal exam, there were no local failures. Conclusion: Biochemical disease-free survival after postprostatectomy radiation is predicted by the PSA at the time of irradiation. Clinical local control is excellent, but distant failure remains a significant problem in this population. The addition of concomitant systemic therapy should be investigated in patients with PSA >2.7

Stability diagram of colliding beams

CERN Document Server

Buffat, X; Mounet, N; Pieloni, T

2014-01-01

The effect of the beam-beam interactions on the stability of impedance mode is discussed. The detuning is evaluated by the means of single particle tracking in arbitrarily complex collision configurations, including lattice non-linearities, and used to numerically evaluate the dispersion integral. This approach also allows the effect of non-Gaussian distributions to be considered. Distributions modified by the action of external noise are discussed.

The ''Amsterdam Castle'': A case study of wiggle matching and the proper calibration curve

NARCIS (Netherlands)

van der Plicht, J; Jansma, E|info:eu-repo/dai/nl/074965255; Kars, H

1995-01-01

We have performed a high-precision 14C wiggle-matching study on two oak beams from the "Castle of Amsterdam". These beams are also dated by dendrochronology. Our two dating methods can only be made consistent using the recommended calibration curve (1986) instead of the revised one (1993).

Parametrisation of linear accelerator electron beam for computerised dosimetry calculations

International Nuclear Information System (INIS)

Millan, P.E.; Millan, S.; Hernandez, A.; Andreo, P.

1979-01-01

A previously published age-diffusion model has been adapted to obtain parameters for the Saggittaire linear accelerator electron beams. The calculations are shown and the results discussed. A comparison is presented between measured and predicted percentage depth doses for electron beams at various energies between 10 and 32 MeV. Theoretical isodose curves are compared, for an energy of 10 MeV, with experimental curves. The parameters obtained are used for computer electron isodose curve calculation in a program called FIJOE adapted from a previously published program. This program makes it possible to correct for irregular body contours, but not for internal inhomogeneities. (UK)

An external proton beam at VERA to study objects of art by proton induced x-ray emission (PIXE)

International Nuclear Information System (INIS)

Kroepfl, P.; Forstner, O.; Kutschera, W.; Priller, A.; Steier, P.; Wallner, A.; Wuenschek, B.; Golser, R.

2006-01-01

Full text: PIXE is a very sensitive analytical method to determine the chemical composition of art objects, e.g. drawings, handwritings etc. A particular advantage is the possibility to analyze objects non-destructively under atmospheric pressure. Such an external beam PIXE facility is currently implemented at the Vienna Environmental Research Accelerator (VERA). The set-up allows to extract a 3 MeV proton beam of approximately 100 μm in diameter and currents in the range of a few nA's through an ultra-thin (0.1 μm) Silicon Nitride window. The characteristic x-rays emitted from the specimen are recorded with a Si(Li) and a Silicon Drift detector simultaneously to cover the widest possible Z-range of the detected elements. We have just completed an extensive period of studying beam effects on ancient paper to exclude possible damage to art objects, in particular drawings of the Renaissance that are among the most precious and rarest treasuries of graphical collections. They were created with different materials such as inks, chalks and metal points. A large collection of these fine arts objects is situated at the Albertina in Vienna. Together with scientists from the Centre de Recherche et de Restauration des Musees de France (C2RMF) in Paris, I. Reiche, A. Duval, H. Guicharnaud, from the CEREGE UMR CNRS 6635 in Aix-en-Provence, S. Merchel, from the Albertina in Vienna, E. Thobois, H. Singer, and from the Akademie der bildenden Kuenste in Vienna, M. Schreiner, we want then to analyze a few selected silverpoint drawings by Albrecht Duerer (1471-1528). (author)

Bandwidth increasing mechanism by introducing a curve fixture to the cantilever generator

Energy Technology Data Exchange (ETDEWEB)

Liu, Weiqun, E-mail: weiqunliu@home.swjtu.edu.cn; Liu, Congzhi; Ren, Bingyu; Zhu, Qiao; Hu, Guangdi [School of Mechanical Engineering, Southwest Jiaotong University, 610031 Chengdu (China); Yang, Weiqing [School of Materials Science and Engineering, Southwest Jiaotong University, 610031 Chengdu (China)

2016-07-25

A nonlinear wideband generator architecture by clamping the cantilever beam generator with a curve fixture is proposed. Devices with different nonlinear stiffness can be obtained by properly choosing the fixture curve according to the design requirements. Three available generator types are presented and discussed for polynomial curves. Experimental investigations show that the proposed mechanism effectively extends the operation bandwidth with good power performance. Especially, the simplicity and easy feasibility allow the mechanism to be widely applied for vibration generators in different scales and environments.

Fractionated external beam radiotherapy of skull base metastases with cranial nerve involvement

Energy Technology Data Exchange (ETDEWEB)

Droege, L.H.; Hinsche, T.; Hess, C.F.; Wolff, H.A. [University Hospital of Goettingen, Department of Radiotherapy and Radiation Oncology, Goettingen (Germany); Canis, M. [University of Goettingen, Department of Otorhinolaryngology, Head and Neck Surgery, Goettingen (Germany); Alt-Epping, B. [University of Goettingen, Department of Palliative Medicine, Goettingen (Germany)

2014-02-15

Skull base metastases frequently appear in a late stage of various tumor entities and cause pain and neurological disorders which strongly impair patient quality of life. This study retrospectively analyzed fractionated external beam radiotherapy (EBRT) as a palliative treatment approach with special respect to neurological outcome, feasibility and acute toxicity. A total of 30 patients with skull base metastases and cranial nerve disorders underwent EBRT with a mean total dose of 31.6 Gy. Neurological status was assessed before radiotherapy, during radiotherapy and 2 weeks afterwards categorizing orbital, parasellar, middle fossa, jugular foramen and occipital condyle involvement and associated clinical syndromes. Neurological outcome was scored as persistence of symptoms, partial response, good response and complete remission. Treatment-related toxicity and overall survival were assessed. Before EBRT 37 skull base involvement syndromes were determined with 4 patients showing more than 1 syndrome. Of the patients 81.1 % responded to radiotherapy with 10.8 % in complete remission, 48.6 % with good response and 21.6 % with partial response. Grade 1 toxicity of the skin occurred in two patients and grade 1 hematological toxicity in 1 patient under concurrent chemoradiotherapy. Median overall survival was 3.9 months with a median follow-up of 45 months. The use of EBRT for skull base metastases with symptomatic involvement of cranial nerves is marked by good therapeutic success in terms of neurological outcome, high feasibility and low toxicity rates. These findings underline EBRT as the standard therapeutic approach in the palliative setting. (orig.)

Fractionated external beam radiotherapy of skull base metastases with cranial nerve involvement

International Nuclear Information System (INIS)

Droege, L.H.; Hinsche, T.; Hess, C.F.; Wolff, H.A.; Canis, M.; Alt-Epping, B.

2014-01-01

Skull base metastases frequently appear in a late stage of various tumor entities and cause pain and neurological disorders which strongly impair patient quality of life. This study retrospectively analyzed fractionated external beam radiotherapy (EBRT) as a palliative treatment approach with special respect to neurological outcome, feasibility and acute toxicity. A total of 30 patients with skull base metastases and cranial nerve disorders underwent EBRT with a mean total dose of 31.6 Gy. Neurological status was assessed before radiotherapy, during radiotherapy and 2 weeks afterwards categorizing orbital, parasellar, middle fossa, jugular foramen and occipital condyle involvement and associated clinical syndromes. Neurological outcome was scored as persistence of symptoms, partial response, good response and complete remission. Treatment-related toxicity and overall survival were assessed. Before EBRT 37 skull base involvement syndromes were determined with 4 patients showing more than 1 syndrome. Of the patients 81.1 % responded to radiotherapy with 10.8 % in complete remission, 48.6 % with good response and 21.6 % with partial response. Grade 1 toxicity of the skin occurred in two patients and grade 1 hematological toxicity in 1 patient under concurrent chemoradiotherapy. Median overall survival was 3.9 months with a median follow-up of 45 months. The use of EBRT for skull base metastases with symptomatic involvement of cranial nerves is marked by good therapeutic success in terms of neurological outcome, high feasibility and low toxicity rates. These findings underline EBRT as the standard therapeutic approach in the palliative setting. (orig.)

Symptoms of internalizing and externalizing problems: modeling recovery curves after the death of a parent.

Science.gov (United States)

Schmiege, Sarah J; Khoo, Siek Toon; Sandler, Irwin N; Ayers, Tim S; Wolchik, Sharlene A

2006-12-01

The death of a parent is a major family disruption that can place children at risk for later depression and other mental health problems. Theoretically based randomized controlled trial for parentally bereaved children. Two-hundred and forty-four children and adolescents and their caregivers from 156 families were randomly assigned to the Family Bereavement Program (FBP) intervention condition (90 families; 135 children) or to a control condition (66 families; 109 children). Data collection occurred from 1996 to 1998. Children and caregivers in the intervention condition met separately for 12 two-hour weekly sessions. Skills targeted by the program for children included positive coping, stress appraisals, control beliefs, and self-esteem. The caregiver program targeted caregiver mental health, life stressors, and improved discipline in the home. Both child and caregiver programs focused on improved quality of the caregiver-child relationship. Child and caregiver reports of internalizing and externalizing symptoms. Longitudinal growth curve modeling was performed to model symptoms over time from the point of parental death. The rate of recovery for girls in the program condition was significantly different from that of girls in the control condition across all outcomes. Boys in both conditions showed reduced symptoms over time. The methodology offers a conceptually unique way of assessing recovery in terms of reduced mental health problems over time after an event and has contributed to further understanding of FBP intervention effects. The intervention program facilitated recovery among girls, who did not show reduction in behavior problems without the program, while boys demonstrated decreased symptoms even without intervention.

Multivariate normal tissue complication probability modeling of gastrointestinal toxicity after external beam radiotherapy for localized prostate cancer

International Nuclear Information System (INIS)

Cella, Laura; D’Avino, Vittoria; Liuzzi, Raffaele; Conson, Manuel; Doria, Francesca; Faiella, Adriana; Loffredo, Filomena; Salvatore, Marco; Pacelli, Roberto

2013-01-01

The risk of radio-induced gastrointestinal (GI) complications is affected by several factors other than the dose to the rectum such as patient characteristics, hormonal or antihypertensive therapy, and acute rectal toxicity. Purpose of this work is to study clinical and dosimetric parameters impacting on late GI toxicity after prostate external beam radiotherapy (RT) and to establish multivariate normal tissue complication probability (NTCP) model for radiation-induced GI complications. A total of 57 men who had undergone definitive RT for prostate cancer were evaluated for GI events classified using the RTOG/EORTC scoring system. Their median age was 73 years (range 53–85). The patients were assessed for GI toxicity before, during, and periodically after RT completion. Several clinical variables along with rectum dose-volume parameters (Vx) were collected and their correlation to GI toxicity was analyzed by Spearman’s rank correlation coefficient (Rs). Multivariate logistic regression method using resampling techniques was applied to select model order and parameters for NTCP modeling. Model performance was evaluated through the area under the receiver operating characteristic curve (AUC). At a median follow-up of 30 months, 37% (21/57) patients developed G1-2 acute GI events while 33% (19/57) were diagnosed with G1-2 late GI events. An NTCP model for late mild/moderate GI toxicity based on three variables including V65 (OR = 1.03), antihypertensive and/or anticoagulant (AH/AC) drugs (OR = 0.24), and acute GI toxicity (OR = 4.3) was selected as the most predictive model (Rs = 0.47, p < 0.001; AUC = 0.79). This three-variable model outperforms the logistic model based on V65 only (Rs = 0.28, p < 0.001; AUC = 0.69). We propose a logistic NTCP model for late GI toxicity considering not only rectal irradiation dose but also clinical patient-specific factors. Accordingly, the risk of G1-2 late GI increases as V65 increases, it is higher for patients experiencing

Stable propagation of light-ion beam in inertial confinement fusion

International Nuclear Information System (INIS)

Okada, T.; Murakami, H.

1996-01-01

The stabilization mechanism of the filamentation instability for a light ion beam (LIB) penetrating plasma is investigated. For the stabilization of the filamentation instability, external magnetic field which is parallel to the direction of the light ion beam propagation is applied. Linear growth rates of filamentation instabilities in a light ion beam-plasma system with an external magnetic field were obtained by means of a dispersion relation. Numerical simulations were carried out using the particle-in-cell (PIC) method. The stabilizing mechanism of the filamentation instability is described. The theory and simulation comparisons illustrate the results. (author). 1 tab., 1 fig., 10 refs

Stable propagation of light-ion beam in inertial confinement fusion

Energy Technology Data Exchange (ETDEWEB)

Okada, T; Murakami, H [Tokyo Univ. of Agriculture and Technology, Koganei (Japan). Faculty of Technology

1997-12-31

The stabilization mechanism of the filamentation instability for a light ion beam (LIB) penetrating plasma is investigated. For the stabilization of the filamentation instability, external magnetic field which is parallel to the direction of the light ion beam propagation is applied. Linear growth rates of filamentation instabilities in a light ion beam-plasma system with an external magnetic field were obtained by means of a dispersion relation. Numerical simulations were carried out using the particle-in-cell (PIC) method. The stabilizing mechanism of the filamentation instability is described. The theory and simulation comparisons illustrate the results. (author). 1 tab., 1 fig., 10 refs.

Curved manifolds with conserved Runge-Lenz vectors

International Nuclear Information System (INIS)

Ngome, J.-P.

2009-01-01

van Holten's algorithm is used to construct Runge-Lenz-type conserved quantities, induced by Killing tensors, on curved manifolds. For the generalized Taub-Newman-Unti-Tamburino metric, the most general external potential such that the combined system admits a conserved Runge-Lenz-type vector is found. In the multicenter case, the subclass of two-center metric exhibits a conserved Runge-Lenz-type scalar.

Reinforced concrete T-beams externally prestressed with unbonded carbon fiber-reinforced polymer tendons

DEFF Research Database (Denmark)

Bennitz, Anders; Nilimaa, Jonny; Täljsten, Björn

2012-01-01

force, and the presence of a deviator were investigated. The results were compared to those observed with analogous beams prestressed with steel tendons, common beam theory, and predictions made using an analytical model adapted from the literature. It was found that steel and CFRP tendons had very...... similar effects on the structural behavior of the strengthened beams; the minor differences that were observed are attributed to the difference between the modulus of elasticity of the CFRP and the steel used in the tests. The models predicted the beams' load-bearing behavior accurately but were less...

Optimum location of external markers using feature selection algorithms for real‐time tumor tracking in external‐beam radiotherapy: a virtual phantom study

Science.gov (United States)

Nankali, Saber; Miandoab, Payam Samadi; Baghizadeh, Amin

2016-01-01

In external‐beam radiotherapy, using external markers is one of the most reliable tools to predict tumor position, in clinical applications. The main challenge in this approach is tumor motion tracking with highest accuracy that depends heavily on external markers location, and this issue is the objective of this study. Four commercially available feature selection algorithms entitled 1) Correlation‐based Feature Selection, 2) Classifier, 3) Principal Components, and 4) Relief were proposed to find optimum location of external markers in combination with two “Genetic” and “Ranker” searching procedures. The performance of these algorithms has been evaluated using four‐dimensional extended cardiac‐torso anthropomorphic phantom. Six tumors in lung, three tumors in liver, and 49 points on the thorax surface were taken into account to simulate internal and external motions, respectively. The root mean square error of an adaptive neuro‐fuzzy inference system (ANFIS) as prediction model was considered as metric for quantitatively evaluating the performance of proposed feature selection algorithms. To do this, the thorax surface region was divided into nine smaller segments and predefined tumors motion was predicted by ANFIS using external motion data of given markers at each small segment, separately. Our comparative results showed that all feature selection algorithms can reasonably select specific external markers from those segments where the root mean square error of the ANFIS model is minimum. Moreover, the performance accuracy of proposed feature selection algorithms was compared, separately. For this, each tumor motion was predicted using motion data of those external markers selected by each feature selection algorithm. Duncan statistical test, followed by F‐test, on final results reflected that all proposed feature selection algorithms have the same performance accuracy for lung tumors. But for liver tumors, a correlation‐based feature

Study of dose distribution in high energy photon beam used in radiotherapy

International Nuclear Information System (INIS)

Rafaravavy, R.; Raoelina Andriambololona; Bridier, A.

2007-01-01

The dose distribution in a medium traversed by a photon beam depends on beam energy, field size and medium nature. Percent depth dose (PDD), Dose Profile (DP) and Opening Collimator Factor (OCF) curves will be established to study this distribution. So, the PDD curves are composed by tree parts: the build-up region, the maximal dose and the quasi-equilibrium region. The maximum dose depth and the dose in depth increase with increasing photon beam energy but the dose surface decreases. The PDD increases with increasing field size.

Muscle invasive bladder cancer treated by transurethral resection, followed by external beam radiation and interstitial iridium-192

International Nuclear Information System (INIS)

Wijnmaalen, Arendjan; Helle, Peter A.; Koper, Peter C.M.; Jansen, Peter P.; Hanssens, Patrick E.J.; Boeken Kruger, Cornelis G.G.; Putten, Wim L.J. van

1996-01-01

Purpose: In our center interstitial radiation has played an important role in the treatment of bladder cancer patients for over 40 years. Radium needles, that were initially used, were replaced by caesium needles in 1983, whereas the afterloading iridium wire technique was adopted in 1989. Patients with solitary tumors (T1, T2 and T3) with a surface diameter of < 5 cm are considered for interstitial radiation. In this study we report on the results of the afterloading iridium wire technique in patients with muscle invasive bladder cancer. Materials and Methods: From May 1989 to September 1993 interstitial radiation using iridium wires was part of the treatment in 46 patients with muscle invasive bladder cancer (37 T2, 9 T3). The mean age was 67 years. After transurethral resection of all visible tumor (if possible), in most cases 40 Gy (20 x 2.0 Gy, midplane dose) external beam radiation was delivered to the true pelvis, followed by 30 Gy interstitial radiation using iridium-192 wires covering the tumor area in the bladder. Results: After a median follow-up of 26 months, bladder relapses occurred in 7 patients. In 5 of them the tumor relapsed in the initial area, in 1 patient elsewhere in the bladder and in 1 patient tumor recurred in and outside the initial site. Recurrence was superficial (T1) in 4 patients. A relapse in the urethra was found once. Metastases developed in 13 patients, in 8 without bladder relapse. During the observation period 17 patients died, 13 due to bladder cancer. The actuarial bladder relapse-free survival at 4 years was 74% and 82% for T2 and T3 tumors, respectively. The actuarial distant metastases-free survival was 65% for both categories. No serious toxicity was recorded. Conclusion: In a selected group of patients with muscle invasive bladder cancer transurethral resection in combination with external beam and interstitial radiation provides an excellent opportunity to preserve the bladder with a high chance of success. Development of

Method for energy recovery of spent ERL beams

Energy Technology Data Exchange (ETDEWEB)

Marhauser, Frank; Hannon, Fay; Rimmer, Robert; Whitney, R. Roy

2018-01-16

A method for recovering energy from spent energy recovered linac (ERL) beams. The method includes adding a plurality of passive decelerating cavities at the beam dump of the ERL, adding one or more coupling waveguides between the passive decelerating cavities, setting an adequate external Q (Qext) to adjust to the beam loading situation, and extracting the RF energy through the coupling waveguides.

WE-D-210-04: Radiation-Induced Polymerization of Ultrasound Contrast Agents in View of Non-Invasive Dosimetry in External Beam Radiation Therapy

Energy Technology Data Exchange (ETDEWEB)

Callens, M; Verboven, E; Van Den Abeele, K [Department of Physics, Wave Propagation and Signal Processing, KU Leuven KULAK, Kortrijk (Belgium); D’Agostino, E [DoseVue NV, Hasselt (Belgium); Pfeiffer, H [Department of Materials Engineering, KU Leuven, Leuven (Belgium); D’hooge, J [Department of Cardiovascular Sciences, Bio-Medical Science Group, KU Leuven, Leuven (Belgium)

2015-06-15

Purpose: Ultrasound contrast agents (UCA’s) based on gas-filled microbubbles encapsulated by an amphiphilic shell are well established as safe and effective echo-enhancers in diagnostic imaging. In view of an alternative application of UCA’s, we investigated the use of targeted microbubbles as radiation sensors for external beam radiation therapy. As radiation induces permanent changes in the microbubble’s physico-chemical properties, a robust measure of these changes can provide a direct or indirect estimate of the applied radiation dose. For instance, by analyzing the ultrasonic dispersion characteristics of microbubble distributions before and after radiation treatment, an estimate of the radiation dose at the location of the irradiated volume can be made. To increase the radiation sensitivity of microbubbles, polymerizable diacetylene molecules can be incorporated into the shell. This study focuses on characterizing the acoustic response and quantifying the chemical modifications as a function of radiation dose. Methods: Lipid/diacetylene microbubbles were irradiated with a 6 MV photon beam using dose levels in the range of 0–150 Gy. The acoustic response of the microbubbles was monitored by ultrasonic through-transmission measurements in the range of 500 kHz to 20 MHz, thereby providing the dispersion relations of the phase velocity, attenuation and nonlinear coefficient. In addition, the radiation-induced chemical modifications were quantified using UV-VIS spectroscopy. Results: UV-VIS spectroscopy measurements indicate that ionizing radiation induces the polymerization of diacetylenes incorporated in the microbubble shell. The polymer yield strongly depends on the shell composition and the radiation-dose. The acoustic response is inherently related to the visco-elastic properties of the shell and is strongly influenced by the shell composition and the physico-chemical changes in the environment. Conclusion: Diacetylene-containing microbubbles are

Reduction of the beam pulse repetition rate of the Hamburg Isochronous Cyclotron

Energy Technology Data Exchange (ETDEWEB)

Krause, H; Langkau, R; Schirm, N [Hamburg Univ. (F.R. Germany). 1. Inst. fuer Experimentalphysik

1976-04-01

A system for the reduction of the beam pulse repetition rate of the energy-variable Hamburg Isochronous Cyclotron comprising beam pulse supression in the cyclotron center and in the external beam is described.

PIXE analysis using external proton beam

Energy Technology Data Exchange (ETDEWEB)

Potocek, V; Potockova, J; Dzmuran, R; Sikora, J

1985-03-01

The possibilities were studied of the practical use of the analytical PIXE method. Calibration samples were analyzed of Cu, Cd, Hg and Pb in concentrations of 50 to 500 ..mu..g/l as well as natural samples of drinking water, pond water, human blood plasma, dry waste from ground vegetation, mushrooms, pine needles, aerosols, human hair, leaves and flowers, etc. The samples were processed using precipitation, mineralization or incineration and were trapped on a membrane filter (Synpor) or on a Tatrafan ON 15 foil. Some samples were freeze-dried and compressed into pellets. A proton beam with an intensity of 10 to 70 nA was used for analysis and the proton energy was selected 2.2 MeV. For most targets an exposure of 120 s was preset and the measurement lasted at least 60 s and 600 s at the most. It was found that Synpor filters browned and became more brittle during longer exposures. The other targets did not change during analysis.

A new small-footprint external-beam PIXE facility for cultural heritage applications using pulsed proton beams

Science.gov (United States)

Vadrucci, M.; Bazzano, G.; Borgognoni, F.; Chiari, M.; Mazzinghi, A.; Picardi, L.; Ronsivalle, C.; Ruberto, C.; Taccetti, F.

2017-09-01

In the framework of the COBRA project, elemental analyses of cultural heritage objects based on the particle induced X-ray emission (PIXE) are planned in a collaboration between the APAM laboratory of ENEA-Frascati and the LABEC laboratory of INFN in Florence. With this aim a 3-7 MeV pulsed proton beam, driven by the injector of the protontherapy accelerator under construction for the TOP-IMPLART project, will be used to demonstrate the feasibility of the technique with a small-footprint pulsed accelerator to Italian small and medium enterprises interested in the composition analysis of ancient artifacts. The experimental set-up for PIXE analysis on the TOP-IMPLART machine consists of a modified assembly of the vertical beam line usually dedicated to radiobiology experiments: the beam produced by the injector (RFQ + DTL, a PL7 ACCSYSHITACHI model) is bent to 90° by a magnet, is collimated by a 300 μm aperture inserted in the end nozzle and extracted into ambient pressure by an exit window consisting of a Upilex foil 7.5 μm thick. The beam is pulsed with a variable pulse duration of 20-100 μs and a repetition rate variable from 10 to 100 Hz. The X-ray detection system is based on a Ketek Silicon Drift Detector (SDD) with 7 mm2 active area and 450 μm thickness, with a thin Beryllium entrance window (8 μm). The results of the calibration of this new PIXE set-up using thick target standards and of the analysis of the preliminary measurements on pigments are presented.

Phase II study of concurrent capecitabine and external beam radiotherapy for pain control of bone metastases of breast cancer origin.

Directory of Open Access Journals (Sweden)

Yulia Kundel

Full Text Available Pain from bone metastases of breast cancer origin is treated with localized radiation. Modulating doses and schedules has shown little efficacy in improving results. Given the synergistic therapeutic effect reported for combined systemic chemotherapy with local radiation in anal, rectal, and head and neck malignancies, we sought to evaluate the tolerability and efficacy of combined capecitabine and radiation for palliation of pain due to bone metastases from breast cancer.Twenty-nine women with painful bone metastases from breast cancer were treated with external beam radiation in 10 fractions of 3 Gy, 5 fractions a week for 2 consecutive weeks. Oral capecitabine 700 mg/m(2 twice daily was administered throughout radiation therapy. Rates of complete response, defined as a score of 0 on a 10-point pain scale and no increase in analgesic consumption, were 14% at 1 week, 38% at 2 weeks, 52% at 4 weeks, 52% at 8 weeks, and 48% at 12 weeks. Corresponding rates of partial response, defined as a reduction of at least 2 points in pain score without an increase in analgesics consumption, were 31%, 38%, 28%, 34% and 38%. The overall response rate (complete and partial at 12 weeks was 86%. Side effects were of mild intensity (grade I or II and included nausea (38% of patients, weakness (24%, diarrhea (24%, mucositis (10%, and hand and foot syndrome (7%.External beam radiation with concurrent capecitabine is safe and tolerable for the treatment of pain from bone metastases of breast cancer origin. The overall and complete response rates in our study are unusually high compared to those reported for radiation alone. Further evaluation of this approach, in a randomized study, is warranted.ClinicalTrials.gov NCT01784393NCT01784393.

Validation of an amino-acid-based radionuclide therapy plus external beam radiotherapy in heterotopic glioblastoma models

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Israel, Ina [Department of Nuclear Medicine, University of Wuerzburg, D-97080 Wuerzburg (Germany); Blass, Georg [Department of Radiotherapy and Radiooncology, Saarland University Medical Center, Homburg (Germany); Reiners, Christoph [Department of Nuclear Medicine, University of Wuerzburg, D-97080 Wuerzburg (Germany); Samnick, Samuel, E-mail: samnick_s@klinik.uni-wuerzburg.d [Department of Nuclear Medicine, University of Wuerzburg, D-97080 Wuerzburg (Germany)

2011-05-15

Background and purpose: Malignant gliomas represent a major therapeutic challenge because no efficient treatment is currently available. p-[{sup 131}I]iodo-L-phenylalanine ([{sup 131}I]IPA) is a glioma avid radiopharmaceutical that demonstrated antiproliferative and tumoricidal effects in gliomas. The present study validated the therapeutic efficiency of [{sup 131}I]IPA combined with external beam radiotherapy in experimental gliomas. Materials and methods: Glioma cells derived from the primary human A1207, T5135, Tx3868 and M059K glioblastoma cell lines or rat F98 glioma cell line were treated with various doses of [{sup 131}I]IPA, external photon irradiation (RT) or combined [{sup 131}I]IPA/RT treatment. Responsiveness of glioma cells to the different therapy modalities was investigated at 24, 48 and 72 h after treatments by trypan blue, WST-1 assay, propidium iodide and bisbenzimide staining as well as by clonogenic assay. In addition, the therapy-induced DNA damage and repair were evaluated using phosphorylated histone H2AX ({gamma}-H2AX). In vivo, the effectiveness of the combination treatment was validated in human Tx3868 and A1207 glioblastoma xenografts in CD1 nu/nu mice and RNU rats. Results: In vitro, the combination treatment resulted in a greater than additive increase in cytotoxic effect in glioma cell lines. Cell survival rate following a treatment with 1.0 {mu}Ci (37 kBq) of [{sup 131}I]IPA amounted to 70%{+-}15% and 60%{+-}10% after 48 and 72 h, respectively, and decreased under 20% after additional RT with 5 Gy. At higher RT doses, cell survival rate decreased below 5%. As a measure of DNA double-strand break, nuclear {gamma}-H2AX foci were determined as a function of time. Within 24 h, the number of {gamma}-H2AX foci per cell was significantly greater after combined modality compared with the individual treatments. In vivo, when combined with RT, the radionuclide therapy with [{sup 131}I]IPA resulted in an extended tumor growth delay, a reduction

The Outcome of Conventional External Beam Radiotherapy for Patients with Squamous Cell Carcinoma of the Esophagus

International Nuclear Information System (INIS)

Jang, Ji Young

2008-01-01

The best treatment for advanced esophageal cancer is chemoradiotherapy followed by surgery. In spite of the advance of multimodality therapy, most patients with esophageal cancer are treated with radiation therapy alone. This study reports the outcome of the use of conventional external beam radiotherapy alone for the treatment of esophageal cancer. Between January 1998 and December 2005, 30 patients with squamous cell carcinoma of the esophagus were treated with external beam radiotherapy using a total dose exceeding 40 Gy. Radiotherapy was delivered with a total dose of 44-60 Gy (median dose, 57.2 Gy) over 36 ∼115 days (median time, 45 days). Thirteen patients (43.3%) had a history of disorders such as diabetes, hypertension, tuberculosis, lye stricture, asthma, cerebral infarct, and cancers. Four patients metachronously had double primary cancers. The most common location of a tumor was the mid-thoracic portion of the esophagus (56.7%). Tumor lengths ranged from 2 cm to 11 cm, with a median length of 6 cm. For AJCC staging, stage III was the most common (63.3%). Five patients had metastases at diagnosis. The median overall survival was 8.3 months. The survival rates at 1-year and 2-years were 33.3% and 18.7%, respectively. The complete response rate 1∼3 months after radiotherapy was 20% (6/30) and the partial response rate was 70% (21/30). Sixteen patients (53.3%) had an improved symptom of dysphagia. Significant prognostic factors were age, tumor length, stage, degree of dysphagia at the time of diagnosis and tumor response. Cox regression analysis revealed the aim of treatment, clinical tumor response and tumor length as independent prognostic factors for overall survival. Twenty-eight patients had local failure and another four patients had metastases. Three patients were detected with double primary cancers in this analysis. A complication of esophageal stricture was observed in three patients (10%), and radiation pneumonitis occurred in two patients (6

The Outcome of Conventional External Beam Radiotherapy for Patients with Squamous Cell Carcinoma of the Esophagus

Energy Technology Data Exchange (ETDEWEB)

Jang, Ji Young [Chosun University College of Medicine, Gwangju (Korea, Republic of)

2008-03-15

The best treatment for advanced esophageal cancer is chemoradiotherapy followed by surgery. In spite of the advance of multimodality therapy, most patients with esophageal cancer are treated with radiation therapy alone. This study reports the outcome of the use of conventional external beam radiotherapy alone for the treatment of esophageal cancer. Between January 1998 and December 2005, 30 patients with squamous cell carcinoma of the esophagus were treated with external beam radiotherapy using a total dose exceeding 40 Gy. Radiotherapy was delivered with a total dose of 44-60 Gy (median dose, 57.2 Gy) over 36 {approx}115 days (median time, 45 days). Thirteen patients (43.3%) had a history of disorders such as diabetes, hypertension, tuberculosis, lye stricture, asthma, cerebral infarct, and cancers. Four patients metachronously had double primary cancers. The most common location of a tumor was the mid-thoracic portion of the esophagus (56.7%). Tumor lengths ranged from 2 cm to 11 cm, with a median length of 6 cm. For AJCC staging, stage III was the most common (63.3%). Five patients had metastases at diagnosis. The median overall survival was 8.3 months. The survival rates at 1-year and 2-years were 33.3% and 18.7%, respectively. The complete response rate 1{approx}3 months after radiotherapy was 20% (6/30) and the partial response rate was 70% (21/30). Sixteen patients (53.3%) had an improved symptom of dysphagia. Significant prognostic factors were age, tumor length, stage, degree of dysphagia at the time of diagnosis and tumor response. Cox regression analysis revealed the aim of treatment, clinical tumor response and tumor length as independent prognostic factors for overall survival. Twenty-eight patients had local failure and another four patients had metastases. Three patients were detected with double primary cancers in this analysis. A complication of esophageal stricture was observed in three patients (10%), and radiation pneumonitis occurred in two

Strengthening Performance of PALF-Epoxy Composite Plate on Reinforced Concrete Beams

Science.gov (United States)

Chin, Siew C.; Tong, Foo S.; Doh, Shu I.; Gimbun, Jolius; Ong, Huey R.; Serigar, Januar P.

2018-03-01

This paper presents the effective strengthening potential of pineapple leaves fiber (PALF)-epoxy composite plate on reinforced concrete (RC) beam. At first the PALF is treated with alkali (NaOH) and its morphology is observed via scanning electron microscope (SEM). The composite plates made of PALF and epoxy with fiber loading ranging from 0.1 to 0.4 v/v was tested for its flexural behaviour. The composite was then used for external RC beam strengthening. The structural properties of RC beams were evaluated and all the beams were tested under four-point bending. It was found that the flexural strength increased as the fiber volume ratio increases. The maximum flexural strength (301.94 MPa) was obtained at the fiber volume ratio of 40%. The beam strengthened with PALF-epoxy composite plate has a 7% higher beam capacity compared to the control beam. Cracks formed at the edge of the plate of PALF-strengthened beams resulted in diagonal cracking. Result from this work shows that the PALF-epoxy composite plate has the potential to be used as external strengthening material for RC beam.

Polyethylene glycol hydrogel rectal spacer implantation in patients with prostate cancer undergoing combination high-dose-rate brachytherapy and external beam radiotherapy.

Science.gov (United States)

Yeh, Jekwon; Lehrich, Brandon; Tran, Carolyn; Mesa, Albert; Baghdassarian, Ruben; Yoshida, Jeffrey; Torrey, Robert; Gazzaniga, Michael; Weinberg, Alan; Chalfin, Stuart; Ravera, John; Tokita, Kenneth

2016-01-01

To present rectal toxicity rates in patients administered a polyethylene glycol (PEG) hydrogel rectal spacer in conjunction with combination high-dose-rate brachytherapy and external beam radiotherapy. Between February 2010 and April 2015, 326 prostate carcinoma patients underwent combination high-dose-rate brachytherapy of 16 Gy (average dose 15.5 Gy; standard deviation [SD] = 1.6 Gy) and external beam radiotherapy of 59.4 Gy (average dose 60.2 Gy; SD = 2.9 Gy). In conjunction with the radiation therapy regimen, each patient was injected with 10 mL of a PEG hydrogel in the anterior perirectal fat space. The injectable spacer (rectal spacer) creates a gap between the prostate and the rectum. The rectum is displaced from the radiation field, and rectal dose is substantially reduced. The goal is a reduction in rectal radiation toxicity. Clinical efficacy was determined by measuring acute and chronic rectal toxicity using the National Cancer Center Institute Common Terminology Criteria for Adverse Events v4.0 grading scheme. Median followup was 16 months. The mean anterior-posterior separation achieved was 1.6 cm (SD = 0.4 cm). Rates of acute Grade 1 and 2 rectal toxicity were 37.4% and 2.8%, respectively. There were no acute Grade 3/4 toxicities. Rates of late Grade 1, 2, and 3 rectal toxicity were 12.7%, 1.4%, and 0.7%, respectively. There were no late Grade 4 toxicities. PEG rectal spacer implantation is safe and well tolerated. Acute and chronic rectal toxicities are low despite aggressive dose escalation. Copyright © 2016 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.