SU-D-201-06: Remote Dosmetric Auditing of VMAT Deliveries for Clinical Trials Using EPID

Energy Technology Data Exchange (ETDEWEB)

Legge, K; Miri, N [University of Newcastle (Australia); Lehmann, J [Calvary Mater Newcastle (Australia); Vial, P [Liverpool Hospital (Australia); Greer, P [University of Newcastle (Australia); Calvary Mater Newcastle (Australia)

2016-06-15

Purpose: To develop a method for remote dosimetric auditing the delivery of VMAT using EPID which allows for simple, inexpensive and time efficient dosimetric credentialing for clinical trials. Methods: Remote centers are provided with CT datasets and planning guidelines to produce VMAT plans for a head and neck and a post-prostatectomy treatment. Plans are transferred in the planning system to two virtual water equivalent phantoms, one flat and one cylindrical. Cine images are acquired during VMAT delivery to the EPID in air with gantry angle recorded in image headers. Centers also deliver provided calibration plans to enable EPID signal to dose conversion, determination of the central axis, and correction of EPID sag prior to analysis. EPID images and planned doses are sent to the central site. EPID cine images are converted to dose in the virtual phantoms using an established backprojection method (King et al., Med.Phys. 2012) with EPID backscatter correction. Individual arcs (with gantry angles collapsed to zero) are evaluated at 10 cm depth in the flat phantom using 2D gamma, and total doses are evaluated in the cylindrical phantom using 3D gamma. Results are reported for criteria of 3%,3mm, 3%,2mm and 2%,2mm for all points greater than 10% of global maximum. Results: The pilot study for Varian centers has commenced, and three centers have been audited for head and neck plans and two for post-prostatectomy plans to date. The mean pass rate for arc-by-arc 2D analysis at 3%,3mm is 99.5% and for 3D analysis is 95.8%. A method for Elekta linacs using an inclinometer for gantry angle information is under development. Conclusion: Preliminary results for this new method are promising. The method takes advantage of EPID equipment available at most centers and clinically established software to provide a feasible, low cost solution to credentialing centers for clinical trials. Funding has been provided from Calvary Mater Newcastle Department of Radiation Oncology, TROG

Quality control of portal imaging with PTW EPID QC PHANTOM registered

International Nuclear Information System (INIS)

Pesznyak, Csilla; Kiraly, Reka; Polgar, Istvan; Zarand, Pal; Mayer, Arpad; Fekete, Gabor; Mozes, Arpad; Kiss, Balazs

2009-01-01

Purpose: quality assurance (QA) and quality control (QC) of different electronic portal imaging devices (EPID) and portal images with the PTW EPID QC PHANTOM registered . Material and methods: characteristic properties of images of different file formats were measured on Siemens OptiVue500aSi registered , Siemens BeamView Plus registered , Elekta iView registered , and Varian PortalVision trademark and analyzed with the epidSoft registered 2.0 program in four radiation therapy centers. The portal images were taken with Kodak X-OMAT V registered and the Kodak Portal Localisation ReadyPack registered films and evaluated with the same program. Results: the optimal exposition both for EPIDs and portal films of different kind was determined. For double exposition, the 2+1 MU values can be recommended in the case of Siemens OptiVue500aSi registered , Elekta iView registered and Kodak Portal Localisation ReadyPack registered films, while for Siemens BeamView Plus registered , Varian PortalVision trademark and Kodak X-OMAT V registered film 7+7 MU is recommended. Conclusion: the PTW EPID QC PHANTOM registered can be used not only for amorphous silicon EPIDs but also for images taken with a video-based system or by using an ionization chamber matrix or for portal film. For analysis of QC tests, a standardized format (used at the acceptance test) should be applied, as the results are dependent on the file format used. (orig.)

SU-F-T-259: GPR Tables for the Estimation of Mid-Plane Dose Using EPID

International Nuclear Information System (INIS)

Annamalai, Gopiraj; Watanabe, Yoichi

2016-01-01

Purpose: To develop a simple method for estimating the mid-plane dose (MPD) of a patient using Electronic Portal imaging Device (EPID). Methods: A Varian TrueBeam with aSi100 EPID was used in this study. The EPID images were acquired for a 30 cm × 30 cm homogeneous slab phantom and a 30 cm diameter 20 cm thick cylindrical phantom in the continuous dosimetry mode. The acquired EPID images in XIM format were imported into in-house MATLAB program for the data analysis. First, the dosimetric characteristics of EPID were studied for dose-response linearity, dose-rate dependence, and field size dependence. Next, the average pixels values of the EPID images were correlated with the MPD measured by an ionisation chamber for various thicknesses of the slab phantom (8 cm – 30 cm) and for various square field sizes (3×3 cm 2 – 25×25 cm 2 at the isocenter). Look-up tables called as GPR tables were then generated for both SSD and SAD setup by taking the ratio of MPD measured by the ionisation chamber and the corresponding EPID pixel values. The accuracy of the GPR tables was evaluated by varying the field size, phantom thickness, and wedge angles with the slab and cylindrical phantoms. Results: The dose response of EPID was linear from 20 MU to 300 MU. The EPID response for different dose rates from 40 MU/min to 600 MU/min was within ±1%. The difference in the doses from the GPR tables and the doses measured by the ionization chambers were within 2% for slab phantoms, and 3% for the cylindrical phantom for various field sizes, phantom thickness, and wedge angles. Conclusion: GPR tables are a ready reckoner for in-vivo dosimetry and it can be used to quickly estimate the MPD value from the EPID images with an accuracy of ±3% for common clinical treatment. project work funded by Union for International cancer control(UICC) under ICRETT fellowship

SU-F-T-259: GPR Tables for the Estimation of Mid-Plane Dose Using EPID

Energy Technology Data Exchange (ETDEWEB)

Annamalai, Gopiraj [Government Arignar Anna Memorial Cancer Hospital & Research Institute, Kanchipuram, TAMILNADU (India); Watanabe, Yoichi [University of Minnesota, Minneapolis, MN (United States)

2016-06-15

Purpose: To develop a simple method for estimating the mid-plane dose (MPD) of a patient using Electronic Portal imaging Device (EPID). Methods: A Varian TrueBeam with aSi100 EPID was used in this study. The EPID images were acquired for a 30 cm × 30 cm homogeneous slab phantom and a 30 cm diameter 20 cm thick cylindrical phantom in the continuous dosimetry mode. The acquired EPID images in XIM format were imported into in-house MATLAB program for the data analysis. First, the dosimetric characteristics of EPID were studied for dose-response linearity, dose-rate dependence, and field size dependence. Next, the average pixels values of the EPID images were correlated with the MPD measured by an ionisation chamber for various thicknesses of the slab phantom (8 cm – 30 cm) and for various square field sizes (3×3 cm{sup 2} – 25×25 cm{sup 2} at the isocenter). Look-up tables called as GPR tables were then generated for both SSD and SAD setup by taking the ratio of MPD measured by the ionisation chamber and the corresponding EPID pixel values. The accuracy of the GPR tables was evaluated by varying the field size, phantom thickness, and wedge angles with the slab and cylindrical phantoms. Results: The dose response of EPID was linear from 20 MU to 300 MU. The EPID response for different dose rates from 40 MU/min to 600 MU/min was within ±1%. The difference in the doses from the GPR tables and the doses measured by the ionization chambers were within 2% for slab phantoms, and 3% for the cylindrical phantom for various field sizes, phantom thickness, and wedge angles. Conclusion: GPR tables are a ready reckoner for in-vivo dosimetry and it can be used to quickly estimate the MPD value from the EPID images with an accuracy of ±3% for common clinical treatment. project work funded by Union for International cancer control(UICC) under ICRETT fellowship.

21 CFR 573.450 - Fermented ammoniated condensed whey.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Fermented ammoniated condensed whey. 573.450... ANIMALS Food Additive Listing § 573.450 Fermented ammoniated condensed whey. (a) Identity. The product is produced by the Lactobacillus bulgaricus fermentation of whey with the addition of ammonia. (b...

Source position verification and dosimetry in HDR brachytherapy using an EPID

International Nuclear Information System (INIS)

Smith, R. L.; Taylor, M. L.; McDermott, L. N.; Franich, R. D.; Haworth, A.; Millar, J. L.

2013-01-01

Purpose: Accurate treatment delivery in high dose rate (HDR) brachytherapy requires correct source dwell positions and dwell times to be administered relative to each other and to the surrounding anatomy. Treatment delivery inaccuracies predominantly occur for two reasons: (i) anatomical movement or (ii) as a result of human errors that are usually related to incorrect implementation of the planned treatment. Electronic portal imaging devices (EPIDs) were originally developed for patient position verification in external beam radiotherapy and their application has been extended to provide dosimetric information. The authors have characterized the response of an EPID for use with an 192 Ir brachytherapy source to demonstrate its use as a verification device, providing both source position and dosimetric information.Methods: Characterization of the EPID response using an 192 Ir brachytherapy source included investigations of reproducibility, linearity with dose rate, photon energy dependence, and charge build-up effects associated with exposure time and image acquisition time. Source position resolution in three dimensions was determined. To illustrate treatment verification, a simple treatment plan was delivered to a phantom and the measured EPID dose distribution compared with the planned dose.Results: The mean absolute source position error in the plane parallel to the EPID, for dwells measured at 50, 100, and 150 mm source to detector distances (SDD), was determined to be 0.26 mm. The resolution of the z coordinate (perpendicular distance from detector plane) is SDD dependent with 95% confidence intervals of ±0.1, ±0.5, and ±2.0 mm at SDDs of 50, 100, and 150 mm, respectively. The response of the EPID is highly linear to dose rate. The EPID exhibits an over-response to low energy incident photons and this nonlinearity is incorporated into the dose calibration procedure. A distance (spectral) dependent dose rate calibration procedure has been developed. The

SU-F-T-562: Validation of EPID-Based Dosimetry for FSRS Commissioning

International Nuclear Information System (INIS)

Song, Y; Saleh, Z; Obcemea, C; Chan, M; Tang, X; Lim, S; Lovelock, D; Ballangrud, A; Mueller, B; Zinovoy, M; Gelblum, D; Mychalczak, B; Both, S

2016-01-01

Purpose: The prevailing approach to frameless SRS (fSRS) small field dosimetry is Gafchromic film. Though providing continuous information, its intrinsic uncertainties in fabrication, response, scan, and calibration often make film dosimetry subject to different interpretations. In this study, we explored the feasibility of using EPID portal dosimetry as a viable alternative to film for small field dosimetry. Methods: Plans prescribed a dose of 21 Gy were created on a flat solid water phantom with Eclipse V11 and iPlan for small static square fields (1.0 to 3.0 cm). In addition, two clinical test plans were computed by employing iPlan on a CIRS Kesler head phantom for target dimensions of 1.2cm and 2.0cm. Corresponding portal dosimetry plans were computed using the Eclipse TPS and delivered on a Varian TrueBeam machine. EBT-XD film dosimetry was performed as a reference. The isocenter doses were measured using EPID, OSLD, stereotactic diode, and CC01 ion chamber. Results: EPID doses at the center of the square field were higher than Eclipse TPS predicted portal doses, with the mean difference being 2.42±0.65%. Doses measured by EBT-XD film, OSLD, stereotactic diode, and CC01 ion chamber revealed smaller differences (except OSLDs), with mean differences being 0.36±3.11%, 4.12±4.13%, 1.7±2.76%, 1.45±2.37% for Eclipse and −1.36±0.85%, 2.38±4.2%, −0.03±0.50%, −0.27±0.78% for iPlan. The profiles measured by EPID and EBT-XD film resembled TPS (Eclipse and iPlan) predicted ones within 3.0%. For the two clinical test plans, the EPID mean doses at the center of field were 2.66±0.68% and 2.33±0.32% higher than TPS predicted doses. Conclusion: We found that results obtained with EPID portal dosimetry were slightly higher (∼2%) than those obtained with EBT-XD film, diode, and CC01 ion chamber with the exception of OSLDs, but well within IROC tolerance (5.0%). Therefore, EPID has the potential to become a viable real-time alternative method to film dosimetry.

SU-F-T-562: Validation of EPID-Based Dosimetry for FSRS Commissioning

Energy Technology Data Exchange (ETDEWEB)

Song, Y; Saleh, Z; Obcemea, C; Chan, M; Tang, X; Lim, S; Lovelock, D; Ballangrud, A; Mueller, B; Zinovoy, M; Gelblum, D; Mychalczak, B; Both, S [Memorial Sloan Kettering Cancer Center, NY (United States)

2016-06-15

Purpose: The prevailing approach to frameless SRS (fSRS) small field dosimetry is Gafchromic film. Though providing continuous information, its intrinsic uncertainties in fabrication, response, scan, and calibration often make film dosimetry subject to different interpretations. In this study, we explored the feasibility of using EPID portal dosimetry as a viable alternative to film for small field dosimetry. Methods: Plans prescribed a dose of 21 Gy were created on a flat solid water phantom with Eclipse V11 and iPlan for small static square fields (1.0 to 3.0 cm). In addition, two clinical test plans were computed by employing iPlan on a CIRS Kesler head phantom for target dimensions of 1.2cm and 2.0cm. Corresponding portal dosimetry plans were computed using the Eclipse TPS and delivered on a Varian TrueBeam machine. EBT-XD film dosimetry was performed as a reference. The isocenter doses were measured using EPID, OSLD, stereotactic diode, and CC01 ion chamber. Results: EPID doses at the center of the square field were higher than Eclipse TPS predicted portal doses, with the mean difference being 2.42±0.65%. Doses measured by EBT-XD film, OSLD, stereotactic diode, and CC01 ion chamber revealed smaller differences (except OSLDs), with mean differences being 0.36±3.11%, 4.12±4.13%, 1.7±2.76%, 1.45±2.37% for Eclipse and −1.36±0.85%, 2.38±4.2%, −0.03±0.50%, −0.27±0.78% for iPlan. The profiles measured by EPID and EBT-XD film resembled TPS (Eclipse and iPlan) predicted ones within 3.0%. For the two clinical test plans, the EPID mean doses at the center of field were 2.66±0.68% and 2.33±0.32% higher than TPS predicted doses. Conclusion: We found that results obtained with EPID portal dosimetry were slightly higher (∼2%) than those obtained with EBT-XD film, diode, and CC01 ion chamber with the exception of OSLDs, but well within IROC tolerance (5.0%). Therefore, EPID has the potential to become a viable real-time alternative method to film dosimetry.

Quality control of portal imaging with PTW EPID QC PHANTOM {sup registered}

Energy Technology Data Exchange (ETDEWEB)

Pesznyak, Csilla; Kiraly, Reka; Polgar, Istvan; Zarand, Pal; Mayer, Arpad [Inst. of Oncoradiology, Uzsoki Hospital, Budapest (Hungary); Fekete, Gabor [Dept. of Oncotherapy, Univ. of Szeged (Hungary); Mozes, Arpad [Oncology Center, Kalman Pandy County Hospital, Gyula (Hungary); Kiss, Balazs [Dept. of Radiation Oncology, Markusovszky County Hospital, Szombathely (Hungary)

2009-01-15

Purpose: quality assurance (QA) and quality control (QC) of different electronic portal imaging devices (EPID) and portal images with the PTW EPID QC PHANTOM {sup registered}. Material and methods: characteristic properties of images of different file formats were measured on Siemens OptiVue500aSi {sup registered}, Siemens BeamView Plus {sup registered}, Elekta iView {sup registered}, and Varian PortalVision trademark and analyzed with the epidSoft {sup registered} 2.0 program in four radiation therapy centers. The portal images were taken with Kodak X-OMAT V {sup registered} and the Kodak Portal Localisation ReadyPack {sup registered} films and evaluated with the same program. Results: the optimal exposition both for EPIDs and portal films of different kind was determined. For double exposition, the 2+1 MU values can be recommended in the case of Siemens OptiVue500aSi {sup registered}, Elekta iView {sup registered} and Kodak Portal Localisation ReadyPack {sup registered} films, while for Siemens BeamView Plus {sup registered}, Varian PortalVision trademark and Kodak X-OMAT V {sup registered} film 7+7 MU is recommended. Conclusion: the PTW EPID QC PHANTOM {sup registered} can be used not only for amorphous silicon EPIDs but also for images taken with a video-based system or by using an ionization chamber matrix or for portal film. For analysis of QC tests, a standardized format (used at the acceptance test) should be applied, as the results are dependent on the file format used. (orig.)

Evaluation of two methods of predicting MLC leaf positions using EPID measurements

International Nuclear Information System (INIS)

Parent, Laure; Seco, Joao; Evans, Phil M.; Dance, David R.; Fielding, Andrew

2006-01-01

In intensity modulated radiation treatments (IMRT), the position of the field edges and the modulation within the beam are often achieved with a multileaf collimator (MLC). During the MLC calibration process, due to the finite accuracy of leaf position measurements, a systematic error may be introduced to leaf positions. Thereafter leaf positions of the MLC depend on the systematic error introduced on each leaf during MLC calibration and on the accuracy of the leaf position control system (random errors). This study presents and evaluates two methods to predict the systematic errors on the leaf positions introduced during the MLC calibration. The two presented methods are based on a series of electronic portal imaging device (EPID) measurements. A comparison with film measurements showed that the EPID could be used to measure leaf positions without introducing any bias. The first method, referred to as the 'central leaf method', is based on the method currently used at this center for MLC leaf calibration. It mimics the manner in which leaf calibration parameters are specified in the MLC control system and consequently is also used by other centers. The second method, a new method proposed by the authors and referred to as the ''individual leaf method,'' involves the measurement of two positions for each leaf (-5 and +15 cm) and the interpolation and extrapolation from these two points to any other given position. The central leaf method and the individual leaf method predicted leaf positions at prescribed positions of -11, 0, 5, and 10 cm within 2.3 and 1.0 mm, respectively, with a standard deviation (SD) of 0.3 and 0.2 mm, respectively. The individual leaf method provided a better prediction of the leaf positions than the central leaf method. Reproducibility tests for leaf positions of -5 and +15 cm were performed. The reproducibility was within 0.4 mm on the same day and 0.4 mm six weeks later (1 SD). Measurements at gantry angles of 0 deg., 90 deg., and 270 deg

12 CFR 573.2 - Model privacy form and examples.

Science.gov (United States)

2010-01-01

... 12 Banks and Banking 5 2010-01-01 2010-01-01 false Model privacy form and examples. 573.2 Section... FINANCIAL INFORMATION § 573.2 Model privacy form and examples. (a) Model privacy form. Use of the model... privacy form is not required. (b) Examples. The examples in this part are not exclusive. Compliance with...

WE-DE-BRA-06: Evaluation of the Imaging Performance of a Novel Water-Equivalent EPID

Energy Technology Data Exchange (ETDEWEB)

Blake, SJ [School of Physics, The University of Sydney, Sydney, NSW (Australia); The Ingham Institute, Liverpool, NSW (Australia); Cheng, J; Atakaramians, S; Kuncic, Z [School of Physics, The University of Sydney, Sydney, NSW (Australia); Vial, P [School of Physics, The University of Sydney, Sydney, NSW (Australia); The Ingham Institute, Liverpool, NSW (Australia); Department of Medical Physics, Liverpool & Macarthur Cancer Therapy Centres, Liverpool, NSW (Australia); Lu, M [Perkin-Elmer Medical Imaging, Santa Clara, California (United States); Meikle, S [Faculty of Health Sciences and Brain and Mind Centre, The University of Sydney, Sydney, NSW (Australia)

2016-06-15

Purpose: To evaluate the megavoltage imaging performance of a novel, water-equivalent electronic portal imaging device (EPID) developed for simultaneous imaging and dosimetry applications in radiotherapy. Methods: A novel EPID prototype based on active matrix flat panel imager technology has been developed by our group and previously reported to exhibit a water-equivalent dose response. It was constructed by replacing all components above the photodiode detector in a standard clinical EPID (including the copper plate and phosphor screen) with a 15 × 15 cm{sup 2} array of plastic scintillator fibers. Individual fibers measured 0.5 × 0.5 × 30 mm{sup 3}. Spatial resolution was evaluated experimentally relative to that of a standard EPID with the thin slit technique to measure the modulation transfer function (MTF) for 6 MV x-ray beams. Monte Carlo (MC) EPID models were used to benchmark simulated MTFs against the measurements. The zero spatial frequency detective quantum efficiency (DQE(0)) was simulated for both EPID configurations and a preliminary optimization of the prototype was performed by evaluating DQE(0) as a function of fiber length up to 50 mm. Results: The MC-simulated DQE(0) for the prototype EPID configuration was ∼7 times greater than that of the standard EPID. The prototype’s DQE(0) also increased approximately linearly with fiber length, from ∼1% at 5 mm length to ∼11% at 50 mm length. The standard EPID MTF was greater than the prototype EPID’s for all spatial frequencies, reflecting the trade off between x-ray detection efficiency and spatial resolution with thick scintillators. Conclusion: This study offers promising evidence that a water-equivalent EPID previously demonstrated for radiotherapy dosimetry may also be used for radiotherapy imaging applications. Future studies on optimising the detector design will be performed to develop a next-generation prototype that offers improved megavoltage imaging performance, with the aim to at

WE-DE-BRA-06: Evaluation of the Imaging Performance of a Novel Water-Equivalent EPID

International Nuclear Information System (INIS)

Blake, SJ; Cheng, J; Atakaramians, S; Kuncic, Z; Vial, P; Lu, M; Meikle, S

2016-01-01

Purpose: To evaluate the megavoltage imaging performance of a novel, water-equivalent electronic portal imaging device (EPID) developed for simultaneous imaging and dosimetry applications in radiotherapy. Methods: A novel EPID prototype based on active matrix flat panel imager technology has been developed by our group and previously reported to exhibit a water-equivalent dose response. It was constructed by replacing all components above the photodiode detector in a standard clinical EPID (including the copper plate and phosphor screen) with a 15 × 15 cm 2 array of plastic scintillator fibers. Individual fibers measured 0.5 × 0.5 × 30 mm 3 . Spatial resolution was evaluated experimentally relative to that of a standard EPID with the thin slit technique to measure the modulation transfer function (MTF) for 6 MV x-ray beams. Monte Carlo (MC) EPID models were used to benchmark simulated MTFs against the measurements. The zero spatial frequency detective quantum efficiency (DQE(0)) was simulated for both EPID configurations and a preliminary optimization of the prototype was performed by evaluating DQE(0) as a function of fiber length up to 50 mm. Results: The MC-simulated DQE(0) for the prototype EPID configuration was ∼7 times greater than that of the standard EPID. The prototype’s DQE(0) also increased approximately linearly with fiber length, from ∼1% at 5 mm length to ∼11% at 50 mm length. The standard EPID MTF was greater than the prototype EPID’s for all spatial frequencies, reflecting the trade off between x-ray detection efficiency and spatial resolution with thick scintillators. Conclusion: This study offers promising evidence that a water-equivalent EPID previously demonstrated for radiotherapy dosimetry may also be used for radiotherapy imaging applications. Future studies on optimising the detector design will be performed to develop a next-generation prototype that offers improved megavoltage imaging performance, with the aim to at least

Using an EPID for patient-specific VMAT quality assurance

International Nuclear Information System (INIS)

Bakhtiari, M.; Kumaraswamy, L.; Bailey, D. W.; Boer, S. de; Malhotra, H. K.; Podgorsak, M. B.

2011-01-01

Purpose: A patient-specific quality assurance (QA) method was developed to verify gantry-specific individual multileaf collimator (MLC) apertures (control points) in volumetric modulated arc therapy (VMAT) plans using an electronic portal imaging device (EPID). Methods: VMAT treatment plans were generated in an Eclipse treatment planning system (TPS). DICOM images from a Varian EPID (aS1000) acquired in continuous acquisition mode were used for pretreatment QA. Each cine image file contains the grayscale image of the MLC aperture related to its specific control point and the corresponding gantry angle information. The TPS MLC file of this RapidArc plan contains the leaf positions for all 177 control points (gantry angles). In-house software was developed that interpolates the measured images based on the gantry angle and overlays them with the MLC pattern for all control points. The 38% isointensity line was used to define the edge of the MLC leaves on the portal images. The software generates graphs and tables that provide analysis for the number of mismatched leaf positions for a chosen distance to agreement at each control point and the frequency in which each particular leaf mismatches for the entire arc. Results: Seven patients plans were analyzed using this method. The leaves with the highest mismatched rate were found to be treatment plan dependent. Conclusions: This in-house software can be used to automatically verify the MLC leaf positions for all control points of VMAT plans using cine images acquired by an EPID.

MO-FG-CAMPUS-TeP1-01: An Efficient Method of 3D Patient Dose Reconstruction Based On EPID Measurements for Pre-Treatment Patient Specific QA

Energy Technology Data Exchange (ETDEWEB)

David, R; Lee, C [Central Coast Cancer Centre, Gosford, NSW (Australia); Calvary Mater Newcastle, Newcastle (Australia); Zwan, B; Hindmarsh, J; Seymour, E; Kandasamy, K; Arthur, G [Central Coast Cancer Centre, Gosford, NSW (Australia); Greer, P [Calvary Mater Newcastle, Newcastle (Australia); University of Newcastle, Newcastle, NSW (Australia)

2016-06-15

Purpose: To demonstrate an efficient and clinically relevant patient specific QA method by reconstructing 3D patient dose from 2D EPID images for IMRT plans. Also to determine the usefulness of 2D QA metrics when assessing 3D patient dose deviations. Methods: Using the method developed by King et al (Med Phys 39(5),2839–2847), EPID images of IMRT fields were acquired in air and converted to dose at 10 cm depth (SAD setup) in a flat virtual water phantom. Each EPID measured dose map was then divided by the corresponding treatment planning system (TPS) dose map calculated with an identical setup, to derive a 2D “error matrix”. For each field, the error matrix was used to adjust the doses along the respective ray lines in the original patient 3D dose. All field doses were combined to derive a reconstructed 3D patient dose for quantitative analysis. A software tool was developed to efficiently implement the entire process and was tested with a variety of IMRT plans for 2D (virtual flat phantom) and 3D (in-patient) QA analysis. Results: The method was tested on 60 IMRT plans. The mean (± standard deviation) 2D gamma (2%,2mm) pass rate (2D-GPR) was 97.4±3.0% and the mean 2D gamma index (2D-GI) was 0.35±0.06. The 3D PTV mean dose deviation was 1.8±0.8%. The analysis showed very weak correlations between both the 2D-GPR and 2D-GI when compared with PTV mean dose deviations (R2=0.3561 and 0.3632 respectively). Conclusion: Our method efficiently calculates 3D patient dose from 2D EPID images, utilising all of the advantages of an EPID-based dosimetry system. In this study, the 2D QA metrics did not predict the 3D patient dose deviation. This tool allows reporting of the 3D volumetric dose parameters thus providing more clinically relevant patient specific QA.

SU-F-T-261: Reconstruction of Initial Photon Fluence Based On EPID Images

Energy Technology Data Exchange (ETDEWEB)

Seliger, T; Engenhart-Cabillic, R [Philipp University of Marburg, Marburg (Germany); Czarnecki, D; Maeder, U; Zink, K [Technische Hochschule Mittelhessen - University of Applied Sciences, Giessen (Germany); Kussaether, R [MedCom GmbH, Darmstadt (Germany); Poppe, B [University Hospital for Medical Radiation Physics, Pius-Hospital, Medical Campus, Carl von Ossietzky University of Oldenburg (Germany)

2016-06-15

Purpose: Verifying an algorithm to reconstruct relative initial photon fluence for clinical use. Clinical EPID and CT images were acquired to reconstruct an external photon radiation treatment field. The reconstructed initial photon fluence could be used to verify the treatment or calculate the applied dose to the patient. Methods: The acquired EPID images were corrected for scatter caused by the patient and the EPID with an iterative reconstruction algorithm. The transmitted photon fluence behind the patient was calculated subsequently. Based on the transmitted fluence the initial photon fluence was calculated using a back-projection algorithm which takes the patient geometry and its energy dependent linear attenuation into account. This attenuation was gained from the acquired cone-beam CT or the planning CT by calculating a water-equivalent radiological thickness for each irradiation direction. To verify the algorithm an inhomogeneous phantom consisting of three inhomogeneities was irradiated by a static 6 MV photon field and compared to a reference flood field image. Results: The mean deviation between the reconstructed relative photon fluence for the inhomogeneous phantom and the flood field EPID image was 3% rising up to 7% for off-axis fluence. This was probably caused by the used clinical EPID calibration, which flattens the inhomogeneous fluence profile of the beam. Conclusion: In this clinical experiment the algorithm achieved good results in the center of the field while it showed high deviation of the lateral fluence. This could be reduced by optimizing the EPID calibration, considering the off-axis differential energy response. In further progress this and other aspects of the EPID, eg. field size dependency, CT and dose calibration have to be studied to realize a clinical acceptable accuracy of 2%.

Clinical validation of an in-house EPID dosimetry system for IMRT QA at the Prince of Wales Hospital

Science.gov (United States)

Tyler, M.; Vial, P.; Metcalfe, P.; Downes, S.

2013-06-01

In this study a simple method using standard flood-field corrected Electronic Portal Imaging Device (EPID) images for routine Intensity Modulated Radiation Therapy (IMRT) Quality Assurance (QA) was investigated. The EPID QA system was designed and tested on a Siemens Oncor Impression linear accelerator with an OptiVue 1000ST EPID panel (Siemens Medical Solutions USA, Inc, USA) and an Elekta Axesse linear accelerator with an iViewGT EPID (Elekta AB, Sweden) for 6 and 10 MV IMRT fields with Step-and-Shoot and dynamic-MLC delivery. Two different planning systems were used for patient IMRT field generation for comparison with the measured EPID fluences. All measured IMRT plans had >95% agreement to the planning fluences (using 3 cGy / 3 mm Gamma Criteria) and were comparable to the pass-rates calculated using a 2-D diode array dosimeter.

Clinical validation of an in-house EPID dosimetry system for IMRT QA at the Prince of Wales Hospital

International Nuclear Information System (INIS)

Tyler, M; Downes, S; Vial, P; Metcalfe, P

2013-01-01

In this study a simple method using standard flood-field corrected Electronic Portal Imaging Device (EPID) images for routine Intensity Modulated Radiation Therapy (IMRT) Quality Assurance (QA) was investigated. The EPID QA system was designed and tested on a Siemens Oncor Impression linear accelerator with an OptiVue 1000ST EPID panel (Siemens Medical Solutions USA, Inc, USA) and an Elekta Axesse linear accelerator with an iViewGT EPID (Elekta AB, Sweden) for 6 and 10 MV IMRT fields with Step-and-Shoot and dynamic-MLC delivery. Two different planning systems were used for patient IMRT field generation for comparison with the measured EPID fluences. All measured IMRT plans had >95% agreement to the planning fluences (using 3 cGy / 3 mm Gamma Criteria) and were comparable to the pass-rates calculated using a 2-D diode array dosimeter.

SU-F-T-476: Performance of the AS1200 EPID for Periodic Photon Quality Assurance

Energy Technology Data Exchange (ETDEWEB)

DeMarco, J; Fraass, B; Yang, W; McKenzie Boehnke, E [Cedars-Sinai Medical Center, Los Angeles, CA (United States); Moran, J [University Michigan Medical Center, Ann Arbor, MI (United States); Barnes, M [Calvary Mater Hospital Newcastle, Warratah, NSW (Australia); Greer, P [Calvary Mater Newcastle, Newcastle (Australia); Kim, G [University of California, San Diego, La Jolla, CA (United States)

2016-06-15

Purpose: To assess the dosimetric performance of a new amorphous silicon flat-panel electronic portal imaging device (EPID) suitable for high-intensity, flattening-filter-free delivery mode. Methods: An EPID-based QA suite was created with automation to periodically monitor photon central-axis output and two-dimensional beam profile constancy as a function of gantry angle and dose-rate. A Varian TrueBeamTM linear accelerator installed with Developer Mode was used to customize and deliver XML script routines for the QA suite using the dosimetry mode image acquisition for an aS1200 EPID. Automatic post-processing software was developed to analyze the resulting DICOM images. Results: The EPID was used to monitor photon beam output constancy (central-axis), flatness, and symmetry over a period of 10 months for four photon beam energies (6x, 15x, 6xFFF, and 10xFFF). EPID results were consistent to those measured with a standard daily QA check device. At the four cardinal gantry angles, the standard deviation of the EPID central-axis output was <0.5%. Likewise, EPID measurements were independent for the wide range of dose rates (including up to 2400 mu/min for 10xFFF) studied with a standard deviation of <0.8% relative to the nominal dose rate for each energy. Also, profile constancy and field size measurements showed good agreement with the reference acquisition of 0° gantry angle and nominal dose rate. XML script files were also tested for MU linearity and picket-fence delivery. Using Developer Mode, the test suite was delivered in <60 minutes for all 4 photon energies with 4 dose rates per energy and 5 picket-fence acquisitions. Conclusion: Dosimetry image acquisition using a new EPID was found to be accurate for standard and high-intensity photon beams over a broad range of dose rates over 10 months. Developer Mode provided an efficient platform to customize the EPID acquisitions by using custom script files which significantly reduced the time. This work was funded

Dosimetric characterization of an electronic portal imaging device (EPID) and development of a portal dosimetry simple model; Caracterizacion dosimetrica de un dispositivo electronico de imagen portal (EPID) y desarrollo de un modelo simple de dosimetria portal

Energy Technology Data Exchange (ETDEWEB)

Ripol ValentIn, O.; GarcIa Romero, A.; Hernandez Vitoria, A.; Jimenez Albericio, J.; Cortes Rodicio, J.; Millan Cebrian, E.; Ruiz Manzano, P.; Canellas Anoz, M.

2010-07-01

The use of the Electronic Portal Imaging Devices (EPID) for the quality control of linear accelerators of electrons is increasingly extended in practice. In this work the dosimetric characteristics of an EPID OptiVue{sup TM}1000 ST were studied and a friendly and simple method for the absorbed dose calibration was suggested. This method is based on a simple mathematical model, including: an absorbed dose transformation coefficient and image lag and field shape corrections. Software tools were developed in order to process the information and the results were validated by comparing them with the measured data with ionization chambers. The studied device showed suitable characteristics for its use for EPID dosimetry and the calculated results fitted satisfactorily with the dose planes obtained with the ionization chambers. Keeping in mind the model limitations, we concluded that it is possible to start the use of the EPID for the accelerator quality control and improvements for the current model should be studied, as well as other suitable applications: e.g. the Intensity Modulated Radiation Therapy (IMRT) treatment verification procedures. (Author).

Measuring linac photon beam energy through EPID image analysis of physically wedged fields

Energy Technology Data Exchange (ETDEWEB)

Dawoud, S. M., E-mail: samir.dawoud@leedsth.nhs.uk; Weston, S. J.; Bond, I.; Ward, G. C.; Rixham, P. A.; Mason, J.; Huckle, A. [Department of Medical Physics and Engineering, St. James Institute of Oncology, St. James University Hospital, Leeds LS9 7TF (United Kingdom); Sykes, J. R. [Institute of Medical Physics, School of Physics, The University of Sydney, New South Wales 2006, Australia and Department of Medical Physics and Engineering, St. James Institute of Oncology, St. James University Hospital, Leeds LS9 7TF (United Kingdom)

2014-02-15

Purpose: Electronic portal imaging devices (EPIDs) have proven to be useful tools for measuring several parameters of interest in linac quality assurance (QA). However, a method for measuring linac photon beam energy using EPIDs has not previously been reported. In this report, such a method is devised and tested, based on fitting a second order polynomial to the profiles of physically wedged beams, where the metric of interest is the second order coefficientα. The relationship between α and the beam quality index [percentage depth dose at 10 cm depth (PDD{sub 10})] is examined to produce a suitable calibration curve between these two parameters. Methods: Measurements were taken in a water-tank for beams with a range of energies representative of the local QA tolerances about the nominal value 6 MV. In each case, the beam quality was found in terms of PDD{sub 10} for 100 × 100 mm{sup 2} square fields. EPID images of 200 × 200 mm{sup 2} wedged fields were then taken for each beam and the wedge profile was fitted in MATLAB 2010b (The MathWorks, Inc., Natick, MA). α was then plotted against PDD{sub 10} and fitted with a linear relation to produce the calibration curve. The uncertainty in α was evaluated by taking five repeat EPID images of the wedged field for a beam of 6 MV nominal energy. The consistency of measuring α was found by taking repeat measurements on a single linac over a three month period. The method was also tested at 10 MV by repeating the water-tank crosscalibration for a range of energies centered approximately about a 10 MV nominal value. Finally, the calibration curve from the test linac and that from a separate clinical machine were compared to test consistency of the method across machines in a matched fleet. Results: The relationship betweenα and PDD{sub 10} was found to be strongly linear (R{sup 2} = 0.979) while the uncertainty in α was found to be negligible compared to that associated with measuring PDD{sub 10} in the water-tank (�

A comprehensive study of the mechanical performance of gantry, EPID and the MLC assembly in Elekta linacs during gantry rotation.

Science.gov (United States)

Rowshanfarzad, P; Riis, H L; Zimmermann, S J; Ebert, M A

2015-07-01

In radiotherapy treatments, it is crucial to monitor the performance of linear accelerator (linac) components, including gantry, collimation system and electronic portal imaging device (EPID) during arc deliveries. In this study, a simple EPID-based measurement method is suggested in conjunction with an algorithm to investigate the stability of these systems at various gantry angles with the aim of evaluating machine-related errors in treatments. The EPID sag, gantry sag, changes in source-to-detector distance (SDD), EPID and collimator skewness, EPID tilt and the sag in leaf bank assembly owing to linac rotation were separately investigated by acquisition of 37 EPID images of a simple phantom with 5 ball bearings at various gantry angles. A fast and robust software package was developed for automated analysis of the image data. Nine Elekta AB (Stockholm, Sweden) linacs of different models and number of years in service were investigated. The average EPID sag was within 2 mm for all tested linacs. Some machines showed >1-mm gantry sag. Changes in the SDD values were within 1.3 cm. EPID skewness and tilt values were <1° in all machines. The maximum sag in multileaf collimator leaf bank assemblies was around 1 mm. A meaningful correlation was found between the age of the linacs and their mechanical performance. Conclusions and Advances in knowledge: The method and software developed in this study provide a simple tool for effective investigation of the behaviour of Elekta linac components with gantry rotation. Such a comprehensive study has been performed for the first time on Elekta machines.

SU-E-T-05: A 2D EPID Transit Dosimetry Model Based On An Empirical Quadratic Formalism

International Nuclear Information System (INIS)

Tan, Y; Metwaly, M; Glegg, M; Baggarley, S; Elliott, A

2014-01-01

Purpose: To describe a 2D electronic portal imaging device (EPID) transit dosimetry model, based on an empirical quadratic formalism, that can predict either EPID or in-phantom dose distribution for comparisons with EPID captured image or treatment planning system (TPS) dose respectively. Methods: A quadratic equation can be used to relate the reduction in intensity of an exit beam to the equivalent path length of the attenuator. The calibration involved deriving coefficients from a set of dose planes measured for homogeneous phantoms with known thicknesses under reference conditions. In this study, calibration dose planes were measured with EPID and ionisation chamber (IC) in water for the same reference beam (6MV, 100mu, 20×20cm 2 ) and set of thicknesses (0–30cm). Since the same calibration conditions were used, the EPID and IC measurements can be related through the quadratic equation. Consequently, EPID transit dose can be predicted from TPS exported dose planes and in-phantom dose can be predicted using EPID distribution captured during treatment as an input. The model was tested with 4 open fields, 6 wedge fields, and 7 IMRT fields on homogeneous and heterogeneous phantoms. Comparisons were done using 2D absolute gamma (3%/3mm) and results were validated against measurements with a commercial 2D array device. Results: The gamma pass rates for comparisons between EPID measured and predicted ranged from 93.6% to 100.0% for all fields and phantoms tested. Results from this study agreed with 2D array measurements to within 3.1%. Meanwhile, comparisons in-phantom between TPS computed and predicted ranged from 91.6% to 100.0%. Validation with 2D array device was not possible for inphantom comparisons. Conclusion: A 2D EPID transit dosimetry model for treatment verification was described and proven to be accurate. The model has the advantage of being generic and allows comparisons at the EPID plane as well as multiple planes in-phantom

Automated x-ray/light field congruence using the LINAC EPID panel

Energy Technology Data Exchange (ETDEWEB)

Polak, Wojciech [Department of Medical Physics, Royal Surrey County Hospital, Guildford GU2 7XX (United Kingdom); Department of Medical Physics, Radiotherapy Section, Queen Alexandra Hospital NHS Trust, Portsmouth PO6 3LY (United Kingdom); O' Doherty, Jim [Division of Imaging Sciences and Biomedical Engineering, King' s College London, London SE1 7EH, United Kingdom and Department of Medical Physics, Royal Surrey County Hospital, Guildford GU2 7XX (United Kingdom); Jones, Matt [Department of Medical Physics, Royal Surrey County Hospital, Guildford GU2 7XX (United Kingdom)

2013-03-15

Purpose: X-ray/light field alignment is a test described in many guidelines for the routine quality control of clinical linear accelerators (LINAC). Currently, the gold standard method for measuring alignment is through utilization of radiographic film. However, many modern LINACs are equipped with an electronic portal imaging device (EPID) that may be used to perform this test and thus subsequently reducing overall cost, processing, and analysis time, removing operator dependency and the requirement to sustain the departmental film processor. Methods: This work describes a novel method of utilizing the EPID together with a custom inhouse designed jig and automatic image processing software allowing measurement of the light field size, x-ray field size, and congruence between them. The authors present results of testing the method for aS1000 and aS500 Varian EPID detectors for six LINACs at a range of energies (6, 10, and 15 MV) in comparison with the results obtained from the use of radiographic film. Results: Reproducibility of the software in fully automatic operation under a range of operating conditions for a single image showed a congruence of 0.01 cm with a coefficient of variation of 0. Slight variation in congruence repeatability was noted through semiautomatic processing by four independent operators due to manual marking of positions on the jig. Testing of the methodology using the automatic method shows a high precision of 0.02 mm compared to a maximum of 0.06 mm determined by film processing. Intraindividual examination of operator measurements of congruence was shown to vary as much as 0.75 mm. Similar congruence measurements of 0.02 mm were also determined for a lower resolution EPID (aS500 model), after rescaling of the image to the aS1000 image size. Conclusions: The designed methodology was proven to be time efficient, cost effective, and at least as accurate as using the gold standard radiographic film. Additionally, congruence testing can be

Automated x-ray/light field congruence using the LINAC EPID panel

International Nuclear Information System (INIS)

Polak, Wojciech; O’Doherty, Jim; Jones, Matt

2013-01-01

Purpose: X-ray/light field alignment is a test described in many guidelines for the routine quality control of clinical linear accelerators (LINAC). Currently, the gold standard method for measuring alignment is through utilization of radiographic film. However, many modern LINACs are equipped with an electronic portal imaging device (EPID) that may be used to perform this test and thus subsequently reducing overall cost, processing, and analysis time, removing operator dependency and the requirement to sustain the departmental film processor. Methods: This work describes a novel method of utilizing the EPID together with a custom inhouse designed jig and automatic image processing software allowing measurement of the light field size, x-ray field size, and congruence between them. The authors present results of testing the method for aS1000 and aS500 Varian EPID detectors for six LINACs at a range of energies (6, 10, and 15 MV) in comparison with the results obtained from the use of radiographic film. Results: Reproducibility of the software in fully automatic operation under a range of operating conditions for a single image showed a congruence of 0.01 cm with a coefficient of variation of 0. Slight variation in congruence repeatability was noted through semiautomatic processing by four independent operators due to manual marking of positions on the jig. Testing of the methodology using the automatic method shows a high precision of 0.02 mm compared to a maximum of 0.06 mm determined by film processing. Intraindividual examination of operator measurements of congruence was shown to vary as much as 0.75 mm. Similar congruence measurements of 0.02 mm were also determined for a lower resolution EPID (aS500 model), after rescaling of the image to the aS1000 image size. Conclusions: The designed methodology was proven to be time efficient, cost effective, and at least as accurate as using the gold standard radiographic film. Additionally, congruence testing can be

Use of local noise power spectrum and wavelet analysis in quantitative image quality assurance for EPIDs

Energy Technology Data Exchange (ETDEWEB)

Lee, Soyoung [Department of Radiation Oncology, University Hospitals Case and Medical Center, Cleveland, Ohio 44106 (United States); Yan, Guanghua; Bassett, Philip; Samant, Sanjiv, E-mail: samant@ufl.edu [Department of Radiation Oncology, University of Florida College of Medicine, Gainesville, Florida 32608 (United States); Gopal, Arun [Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, Maryland 21201 (United States)

2016-09-15

Purpose: To investigate the use of local noise power spectrum (NPS) to characterize image noise and wavelet analysis to isolate defective pixels and inter-subpanel flat-fielding artifacts for quantitative quality assurance (QA) of electronic portal imaging devices (EPIDs). Methods: A total of 93 image sets including custom-made bar-pattern images and open exposure images were collected from four iViewGT a-Si EPID systems over three years. Global quantitative metrics such as modulation transform function (MTF), NPS, and detective quantum efficiency (DQE) were computed for each image set. Local NPS was also calculated for individual subpanels by sampling region of interests within each subpanel of the EPID. The 1D NPS, obtained by radially averaging the 2D NPS, was fitted to a power-law function. The r-square value of the linear regression analysis was used as a singular metric to characterize the noise properties of individual subpanels of the EPID. The sensitivity of the local NPS was first compared with the global quantitative metrics using historical image sets. It was then compared with two commonly used commercial QA systems with images collected after applying two different EPID calibration methods (single-level gain and multilevel gain). To detect isolated defective pixels and inter-subpanel flat-fielding artifacts, Haar wavelet transform was applied on the images. Results: Global quantitative metrics including MTF, NPS, and DQE showed little change over the period of data collection. On the contrary, a strong correlation between the local NPS (r-square values) and the variation of the EPID noise condition was observed. The local NPS analysis indicated image quality improvement with the r-square values increased from 0.80 ± 0.03 (before calibration) to 0.85 ± 0.03 (after single-level gain calibration) and to 0.96 ± 0.03 (after multilevel gain calibration), while the commercial QA systems failed to distinguish the image quality improvement between the two

A method for evaluating treatment quality using in vivo EPID dosimetry and statistical process control in radiation therapy.

Science.gov (United States)

Fuangrod, Todsaporn; Greer, Peter B; Simpson, John; Zwan, Benjamin J; Middleton, Richard H

2017-03-13

Purpose Due to increasing complexity, modern radiotherapy techniques require comprehensive quality assurance (QA) programmes, that to date generally focus on the pre-treatment stage. The purpose of this paper is to provide a method for an individual patient treatment QA evaluation and identification of a "quality gap" for continuous quality improvement. Design/methodology/approach A statistical process control (SPC) was applied to evaluate treatment delivery using in vivo electronic portal imaging device (EPID) dosimetry. A moving range control chart was constructed to monitor the individual patient treatment performance based on a control limit generated from initial data of 90 intensity-modulated radiotherapy (IMRT) and ten volumetric-modulated arc therapy (VMAT) patient deliveries. A process capability index was used to evaluate the continuing treatment quality based on three quality classes: treatment type-specific, treatment linac-specific, and body site-specific. Findings The determined control limits were 62.5 and 70.0 per cent of the χ pass-rate for IMRT and VMAT deliveries, respectively. In total, 14 patients were selected for a pilot study the results of which showed that about 1 per cent of all treatments contained errors relating to unexpected anatomical changes between treatment fractions. Both rectum and pelvis cancer treatments demonstrated process capability indices were less than 1, indicating the potential for quality improvement and hence may benefit from further assessment. Research limitations/implications The study relied on the application of in vivo EPID dosimetry for patients treated at the specific centre. Sampling patients for generating the control limits were limited to 100 patients. Whilst the quantitative results are specific to the clinical techniques and equipment used, the described method is generally applicable to IMRT and VMAT treatment QA. Whilst more work is required to determine the level of clinical significance, the

Monte Carlo modelling of a-Si EPID response: The effect of spectral variations with field size and position

International Nuclear Information System (INIS)

Parent, Laure; Seco, Joao; Evans, Phil M.; Fielding, Andrew; Dance, David R.

2006-01-01

This study focused on predicting the electronic portal imaging device (EPID) image of intensity modulated radiation treatment (IMRT) fields in the absence of attenuation material in the beam with Monte Carlo methods. As IMRT treatments consist of a series of segments of various sizes that are not always delivered on the central axis, large spectral variations may be observed between the segments. The effect of these spectral variations on the EPID response was studied with fields of various sizes and off-axis positions. A detailed description of the EPID was implemented in a Monte Carlo model. The EPID model was validated by comparing the EPID output factors for field sizes between 1x1 and 26x26 cm 2 at the isocenter. The Monte Carlo simulations agreed with the measurements to within 1.5%. The Monte Carlo model succeeded in predicting the EPID response at the center of the fields of various sizes and offsets to within 1% of the measurements. Large variations (up to 29%) of the EPID response were observed between the various offsets. The EPID response increased with field size and with field offset for most cases. The Monte Carlo model was then used to predict the image of a simple test IMRT field delivered on the beam axis and with an offset. A variation of EPID response up to 28% was found between the on- and off-axis delivery. Finally, two clinical IMRT fields were simulated and compared to the measurements. For all IMRT fields, simulations and measurements agreed within 3%--0.2 cm for 98% of the pixels. The spectral variations were quantified by extracting from the spectra at the center of the fields the total photon yield (Y total ), the photon yield below 1 MeV (Y low ), and the percentage of photons below 1 MeV (P low ). For the studied cases, a correlation was shown between the EPID response variation and Y total , Y low , and P low

Automated x-ray/light field congruence using the LINAC EPID panel.

Science.gov (United States)

Polak, Wojciech; O'Doherty, Jim; Jones, Matt

2013-03-01

X-ray/light field alignment is a test described in many guidelines for the routine quality control of clinical linear accelerators (LINAC). Currently, the gold standard method for measuring alignment is through utilization of radiographic film. However, many modern LINACs are equipped with an electronic portal imaging device (EPID) that may be used to perform this test and thus subsequently reducing overall cost, processing, and analysis time, removing operator dependency and the requirement to sustain the departmental film processor. This work describes a novel method of utilizing the EPID together with a custom inhouse designed jig and automatic image processing software allowing measurement of the light field size, x-ray field size, and congruence between them. The authors present results of testing the method for aS1000 and aS500 Varian EPID detectors for six LINACs at a range of energies (6, 10, and 15 MV) in comparison with the results obtained from the use of radiographic film. Reproducibility of the software in fully automatic operation under a range of operating conditions for a single image showed a congruence of 0.01 cm with a coefficient of variation of 0. Slight variation in congruence repeatability was noted through semiautomatic processing by four independent operators due to manual marking of positions on the jig. Testing of the methodology using the automatic method shows a high precision of 0.02 mm compared to a maximum of 0.06 mm determined by film processing. Intraindividual examination of operator measurements of congruence was shown to vary as much as 0.75 mm. Similar congruence measurements of 0.02 mm were also determined for a lower resolution EPID (aS500 model), after rescaling of the image to the aS1000 image size. The designed methodology was proven to be time efficient, cost effective, and at least as accurate as using the gold standard radiographic film. Additionally, congruence testing can be easily performed for all four cardinal

Investigation of the dosimetric properties of an a-Si flat panel epid

International Nuclear Information System (INIS)

Fielding, A.L.; Jahangir, S.T.

2004-01-01

Full text: Electronic portal imaging devices (EPIDs) are primarily used as an electronic replacement for film to verify the set-up of radiotherapy patients based on imaged anatomy. There has recently been much interest in the use of amorphous silicon (a-Si) flat panel EPIDs for dosimetric verification in radiotherapy. The work presented here has been carried out to determine their suitability for dosimetric applications by investigating some of the basic response characteristics and the implications these might have. The measurements reported in this paper were performed using 6-MV photon beams from an Elekta Precise linear accelerator fitted with Elekta iViewGT amorphous silicon flat panel EPIDs. Measurements were performed to investigate the response of the EPID as a function of exposure and field size. Similar measurements were made with an ionisation chamber for comparison. Further measurements were carried out to investigate the response of the EPID to multiple low dose exposures (e.g. 5x2 MU) such as might be encountered in Intensity Modulated Radiotherapy (IMRT). This was compared with the response to a single high dose exposure (e.g. 10 MU) and repeated for a range of exposures. The results show the response of the EPID, to a good approximation, to be linear with dose over the range of 1 -200 MU. However, 'under-responses' in the EPID of up to 5% were seen at the lowest exposures. For multiple low dose segments the sum of the EPID responses was found to be less than the response to the same total exposure in a single large segment. This effect reduces with increase in the magnitude of the low dose segments. The variation in EPID response with field size was found to be greater than that indicated by the ionisation chamber. The results show that the a-Si detector responds to dose, to a good approximation, in a linear manner. The EPID under-response at low doses is thought to be related to the so called ghosting effect. Each image frame has a residual

Assessment of an amorphous silicon EPID for quality assurance of enhanced dynamic wedge

International Nuclear Information System (INIS)

Greer, P.

2004-01-01

Full text: Routine quality assurance (QA) of enhanced dynamic wedge (EDW) is usually performed weekly to monthly. Wedge factors are measured with ion-chamber, and profiles usually with diode-arrays such as the Profiler. The use of an electronic portal imaging device (EPID) for these measurements would combine these into a single rapid set-up and measurement. Currently the Varian EPID in standard imaging mode will not acquire integrated images during EDW treatments, and therefore has not been utilised for EDW dosimetry. Modification to image acquisition was made to enable imaging for EDW, and the performance of the EPID for suitability for quality assurance of EDW was investigated. The accuracy of EDW profiles measured with the EPID were assessed by comparison to Profiler measurements. The EPID was positioned at 105 cm to the detector surface, with 4 cm of additional solid water build-up to give total build-up including EPID inherent build-up of 5 cm. Images of EDW fields were acquired with continuous frame-averaging throughout the delivery. Field sizes of 10x10 cm, and 20x20 cm were used for 30 deg and 60 deg wedge angles for both 6 MV and 18 MV x-rays. Profiler measurements of the same fields were made with 5 cm of solid water build-up with 105 cm to the detector. Profiles in the wedged direction along the central axis of the beam were then compared. The reproducibility of the EPID measured profiles was assessed by three measurements made at weekly intervals. The accuracy of EPID measured wedge factors was investigated with the same experimental set-up. Three images of a 10x10 cm open field were acquired, and the mean pixel value in a 9x9 pixel region at the central axis was found. As the pixel value is the average of all acquired frames, this was multiplied by the number of frames to yield an integrated pixel value. This was repeated for three 10x10 cm 60 deg wedge irradiations. The wedge factor measured with the EPID was then compared to routine weekly

Virtual EPID standard phantom audit (VESPA) for remote IMRT and VMAT credentialing

Science.gov (United States)

Miri, Narges; Lehmann, Joerg; Legge, Kimberley; Vial, Philip; Greer, Peter B.

2017-06-01

A virtual EPID standard phantom audit (VESPA) has been implemented for remote auditing in support of facility credentialing for clinical trials using IMRT and VMAT. VESPA is based on published methods and a clinically established IMRT QA procedure, here extended to multi-vendor equipment. Facilities are provided with comprehensive instructions and CT datasets to create treatment plans. They deliver the treatment directly to their EPID without any phantom or couch in the beam. In addition, they deliver a set of simple calibration fields per instructions. Collected EPID images are uploaded electronically. In the analysis, the dose is projected back into a virtual cylindrical phantom. 3D gamma analysis is performed. 2D dose planes and linear dose profiles are provided and can be considered when needed for clarification. In addition, using a virtual flat-phantom, 2D field-by-field or arc-by-arc gamma analyses are performed. Pilot facilities covering a range of planning and delivery systems have performed data acquisition and upload successfully. Advantages of VESPA are (1) fast turnaround mainly driven by the facility’s capability of providing the requested EPID images, (2) the possibility for facilities performing the audit in parallel, as there is no need to wait for a phantom, (3) simple and efficient credentialing for international facilities, (4) a large set of data points, and (5) a reduced impact on resources and environment as there is no need to transport heavy phantoms or audit staff. Limitations of the current implementation of VESPA for trials credentialing are that it does not provide absolute dosimetry, therefore a Level I audit is still required, and that it relies on correctly delivered open calibration fields, which are used for system calibration. The implemented EPID based IMRT and VMAT audit system promises to dramatically improve credentialing efficiency for clinical trials and wider applications.

Normalize the response of EPID in pursuit of linear accelerator dosimetry standardization.

Science.gov (United States)

Cai, Bin; Goddu, S Murty; Yaddanapudi, Sridhar; Caruthers, Douglas; Wen, Jie; Noel, Camille; Mutic, Sasa; Sun, Baozhou

2018-01-01

Normalize the response of electronic portal imaging device (EPID) is the first step toward an EPID-based standardization of Linear Accelerator (linac) dosimetry quality assurance. In this study, we described an approach to generate two-dimensional (2D) pixel sensitivity maps (PSM) for EPIDs response normalization utilizing an alternative beam and dark-field (ABDF) image acquisition technique and large overlapping field irradiations. The automated image acquisition was performed by XML-controlled machine operation and the PSM was generated based on a recursive calculation algorithm for Varian linacs equipped with aS1000 and aS1200 imager panels. Cross-comparisons of normalized beam profiles and 1.5%/1.5 mm 1D Gamma analysis was adopted to quantify the improvement of beam profile matching before and after PSM corrections. PSMs were derived for both photon (6, 10, 15 MV) and electron (6, 20 MeV) beams via proposed method. The PSM-corrected images reproduced a horn-shaped profile for photon beams and a relative uniform profiles for electrons. For dosimetrically matched linacs equipped with aS1000 panels, PSM-corrected images showed increased 1D-Gamma passing rates for all energies, with an average 10.5% improvement for crossline and 37% for inline beam profiles. Similar improvements in the phantom study were observed with a maximum improvement of 32% for 15 MV and 22% for 20 MeV. The PSM value showed no significant change for all energies over a 3-month period. In conclusion, the proposed approach correct EPID response for both aS1000 and aS1200 panels. This strategy enables the possibility to standardize linac dosimetry QA and to benchmark linac performance utilizing EPID as the common detector. © 2017 The Authors. Journal of Applied Clinical Medical Physics published by Wiley Periodicals, Inc. on behalf of American Association of Physicists in Medicine.

21 CFR 573.1000 - Verxite.

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2010-04-01

... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Verxite. 573.1000 Section 573.1000 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS... Listing § 573.1000 Verxite. The food additive verxite may be safely used in animal feed in accordance with...

Comparison of ghosting effects for three commercial a-Si EPIDs

International Nuclear Information System (INIS)

McDermott, L. N.; Nijsten, S. M. J. J. G.; Sonke, J.-J.; Partridge, M.; Herk, M. van; Mijnheer, B. J.

2006-01-01

Many studies have reported dosimetric characteristics of amorphous silicon electronic portal imaging devices (EPIDs). Some studies ascribed a non-linear signal to gain ghosting and image lag. Other reports, however, state the effect is negligible. This study compares the signal-to-monitor unit (MU) ratio for three different brands of EPID systems. The signal was measured for a wide range of monitor units (5-1000), dose-rates, and beam energies. All EPIDs exhibited a relative under-response for beams of few MUs; giving 4 to 10% lower signal-to-MU ratios relative to that of 1000 MUs. This under-response is consistent with ghosting effects due to charge trapping

Epid cine acquisition mode for in vivo dosimetry in dynamic arc radiation therapy

International Nuclear Information System (INIS)

Fidanzio, Andrea; Mameli, Alessandra; Placidi, Elisa; Greco, Francesca; Stimato, Gerardina; Gaudino, Diego; Ramella, Sara; D'Angelillo, Rolando; Cellini, Francesco; Trodella, Lucio; Cilla, Savino; Grimaldi, Luca; D'Onofrio, Guido; Azario, Luigi; Piermattei, Angelo

2008-01-01

In this paper the cine acquisition mode of an electronic portal imaging device (EPID) has been calibrated and tested to determine the in vivo dose for dynamic conformal arc radiation therapy (DCAT). The EPID cine acquisition mode, that allows a frame acquisition rate of one image every 1.66 s, was studied with a monitor unit rate equal to 100 UM/min. In these conditions good signal stability, ±1% (2SD) evaluated during three months, signal reproducibility within ±0.8% (2SD) and linearity with dose and dose rate within ±1% (2SD) were obtained. The transit signal, S t , (due to the transmitted beam below the phantom) measured by the EPID cine acquisition mode was used to determine, (i) a set of correlation functions, F(w,L), defined as the ratio between S t and the dose at half thickness, D m , measured in solid water phantoms of different thicknesses, w and with square fields of side L, (ii) a set of factors, f(d,L), that take into account the different X-ray scatter contribution from the phantom to the S t signal as a function of the variation, d, of the air gap between the phantom and the EPID. The reconstruction of the isocenter dose, D iso , for DCAT was obtained convolving the transit signal values, obtained at different gantry angles, with the respective reconstruction factors determined by a house-made software. The method was tested with cylindrical and anthropomorphic phantoms and the results show that the reconstructed D iso values can be obtained with an accuracy within ±2.5% in cylindrical phantom and within ±3.4% for anthropomorphic phantom. In conclusion, the transit dosimetry by EPID was assessed to be adequate to perform DCAT in vivo dosimetry, that is not realizable with the other traditional techniques. Moreover, the method proposed here could be implemented to supply in vivo dose values in real time

Implementation of DMLC quality control using EPID (Portal Dosimetry); Implementacao de um controle de qualidade de DMLC utilizando um EPID (Portal Dosimetry)

Energy Technology Data Exchange (ETDEWEB)

Mattos, Fabio R.; Furnari, Laura, E-mail: mattos.fr@gmail.com [Universidade de Sao Paulo (USP), Sao Paulo, SP (Brazil). Faculdade de Medicina; Universidade de Sao Paulo (INRAD/HC/FMUSP), Sao Paulo, SP (Brazil). Instituto de Radiologia. Setor de Radioterapia

2017-11-01

A Quality Assurance (QA) to ensure the expected performance of a Multileaf Collimator System (MLC) is essential to deliver dose in a safety and appropriate way. The time required for equipment control and dosimetry may be reduced when the Electronic Portal Image Device (EPID) is used. The aim of this work was to check the resolution limits of the detection system for IMRT mode, and to propose a set of tests that can provide positioning analysis of a multileaf system. A Varian iX Clinac equipped with an 80 leaf Millenium MLC, and an amorphous silicon based EPID (aS1000) was used. The EPID proved itself effective for detecting errors up to 0.5 mm. The proposed tests provided relevant results of leaf position, and revealed that the MLC system is within acceptable limits found in literature. (author)

On the use of EPID-based implanted marker tracking for 4D radiotherapy

International Nuclear Information System (INIS)

Keall, P.J.; Todor, A.D.; Vedam, S.S.; Bartee, C.L.; Siebers, J.V.; Kini, V.R.; Mohan, R.

2004-01-01

Four-dimensional (4D) radiotherapy delivery to dynamically moving tumors requires a real-time signal of the tumor position as a function of time so that the radiation beam can continuously track the tumor during the respiration cycle. The aim of this study was to develop and evaluate an electronic portal imaging device (EPID)-based marker-tracking system that can be used for real-time tumor targeting, or 4D radiotherapy. Three gold cylinders, 3 mm in length and 1 mm in diameter, were implanted in a dynamic lung phantom. The phantom range of motion was 4 cm with a 3-s 'breathing' period. EPID image acquisition parameters were modified, allowing image acquisition in 0.1 s. Images of the stationary and moving phantom were acquired. Software was developed to segment automatically the marker positions from the EPID images. Images acquired in 0.1 s displayed higher noise and a lower signal-noise ratio than those obtained using regular (>1 s) acquisition settings. However, the markers were still clearly visible on the 0.1-s images. The motion of the phantom blurred the images of the markers and further reduced the signal-noise ratio, though they could still be successfully segmented from the images in 10-30 ms of computation time. The positions of gold markers placed in the lung phantom were detected successfully, even for phantom velocities substantially higher than those observed for typical lung tumors. This study shows that using EPID-based marker tracking for 4D radiotherapy is feasible, however, changes in linear accelerator technology and EPID-based image acquisition as well as patient studies are required before this method can be implemented clinically

An improved Monte-Carlo model of the Varian EPID separating support arm and rear-housing backscatter

International Nuclear Information System (INIS)

Monville, M E; Greer, P B; Kuncic, Z

2014-01-01

Previous investigators of EPID dosimetric properties have ascribed the backscatter, that contaminates dosimetric EPID images, to its supporting arm. Accordingly, Monte-Carlo (MC) EPID models have approximated the backscatter signal from the layers under the detector and the robotic support arm using either uniform or non-uniform solid water slabs, or through convolutions with back-scatter kernels. The aim of this work is to improve the existent MC models by measuring and modelling the separate backscatter contributions of the robotic arm and the rear plastic housing of the EPID. The EPID plastic housing is non-uniform with a 11.9 cm wide indented section that runs across the cross-plane direction in the superior half of the EPID which is 1.75 cm closer to the EPID sensitive layer than the rest of the housing. The thickness of the plastic housing is 0.5 cm. Experiments were performed with and without the housing present by removing all components of the EPID from the housing. The robotic support arm was not present for these measurements. A MC model of the linear accelerator and the EPID was modified to include the rear-housing indentation and results compared to the measurement. The rear housing was found to contribute a maximum of 3% additional signal. The rear housing contribution to the image is non-uniform in the in-plane direction with 2% asymmetry across the central 20 cm of an image irradiating the entire detector. The MC model was able to reproduce this non-uniform contribution. The EPID rear housing contributes a non-uniform backscatter component to the EPID image, which has not been previously characterized. This has been incorporated into an improved MC model of the EPID.

First Experience With Real-Time EPID-Based Delivery Verification During IMRT and VMAT Sessions

International Nuclear Information System (INIS)

Woodruff, Henry C.; Fuangrod, Todsaporn; Van Uytven, Eric; McCurdy, Boyd M.C.; Beek, Timothy van; Bhatia, Shashank; Greer, Peter B.

2015-01-01

Purpose: Gantry-mounted megavoltage electronic portal imaging devices (EPIDs) have become ubiquitous on linear accelerators. WatchDog is a novel application of EPIDs, in which the image frames acquired during treatment are used to monitor treatment delivery in real time. We report on the preliminary use of WatchDog in a prospective study of cancer patients undergoing intensity modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT) and identify the challenges of clinical adoption. Methods and Materials: At the time of submission, 28 cancer patients (head and neck, pelvis, and prostate) undergoing fractionated external beam radiation therapy (24 IMRT, 4 VMAT) had ≥1 treatment fraction verified in real time (131 fractions or 881 fields). EPID images acquired continuously during treatment were synchronized and compared with model-generated transit EPID images within a frame time (∼0.1 s). A χ comparison was performed to cumulative frames to gauge the overall delivery quality, and the resulting pass rates were reported graphically during treatment delivery. Every frame acquired (500-1500 per fraction) was saved for postprocessing and analysis. Results: The system reported the mean ± standard deviation in real time χ 91.1% ± 11.5% (83.6% ± 13.2%) for cumulative frame χ analysis with 4%, 4 mm (3%, 3 mm) criteria, global over the integrated image. Conclusions: A real-time EPID-based radiation delivery verification system for IMRT and VMAT has been demonstrated that aims to prevent major mistreatments in radiation therapy.

First Experience With Real-Time EPID-Based Delivery Verification During IMRT and VMAT Sessions

Energy Technology Data Exchange (ETDEWEB)

Woodruff, Henry C., E-mail: henry.woodruff@newcastle.edu.au [Faculty of Science and Information Technology, School of Mathematical and Physical Sciences, University of Newcastle, New South Wales (Australia); Fuangrod, Todsaporn [Faculty of Engineering and Built Environment, School of Electrical Engineering and Computer Science, University of Newcastle, New South Wales (Australia); Van Uytven, Eric; McCurdy, Boyd M.C.; Beek, Timothy van [Division of Medical Physics, CancerCare Manitoba, Winnipeg, Manitoba (Canada); Department of Physics and Astronomy, University of Manitoba, Winnipeg, Manitoba (Canada); Department of Radiology, University of Manitoba, Winnipeg, Manitoba (Canada); Bhatia, Shashank [Department of Radiation Oncology, Calvary Mater Newcastle Hospital, Newcastle, New South Wales (Australia); Greer, Peter B. [Faculty of Science and Information Technology, School of Mathematical and Physical Sciences, University of Newcastle, New South Wales (Australia); Department of Radiation Oncology, Calvary Mater Newcastle Hospital, Newcastle, New South Wales (Australia)

2015-11-01

Purpose: Gantry-mounted megavoltage electronic portal imaging devices (EPIDs) have become ubiquitous on linear accelerators. WatchDog is a novel application of EPIDs, in which the image frames acquired during treatment are used to monitor treatment delivery in real time. We report on the preliminary use of WatchDog in a prospective study of cancer patients undergoing intensity modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT) and identify the challenges of clinical adoption. Methods and Materials: At the time of submission, 28 cancer patients (head and neck, pelvis, and prostate) undergoing fractionated external beam radiation therapy (24 IMRT, 4 VMAT) had ≥1 treatment fraction verified in real time (131 fractions or 881 fields). EPID images acquired continuously during treatment were synchronized and compared with model-generated transit EPID images within a frame time (∼0.1 s). A χ comparison was performed to cumulative frames to gauge the overall delivery quality, and the resulting pass rates were reported graphically during treatment delivery. Every frame acquired (500-1500 per fraction) was saved for postprocessing and analysis. Results: The system reported the mean ± standard deviation in real time χ 91.1% ± 11.5% (83.6% ± 13.2%) for cumulative frame χ analysis with 4%, 4 mm (3%, 3 mm) criteria, global over the integrated image. Conclusions: A real-time EPID-based radiation delivery verification system for IMRT and VMAT has been demonstrated that aims to prevent major mistreatments in radiation therapy.

SU-G-TeP4-07: Automatic EPID-Based 2D Measurement of MLC Leaf Offset as a Quality Control Tool

Energy Technology Data Exchange (ETDEWEB)

Ritter, T; Moran, J [The University of Michigan, Ann Arbor, MI (United States); Schultz, B [University of Michigan, Ann Arbor, MI (United States); Kim, G [University of California, San Diego, La Jolla, CA (United States); Barnes, M [Calvary Mater Hospital Newcastle, Warratah, NSW (Australia); Perez, M [North Sydney Cancer Center, Sydney (Australia); Farrey, K [University of Chicago, Chicago, IL (United States); Popple, R [University Alabama Birmingham, Birmingham, AL (United States); Greer, P [Calvary Mater Newcastle, Newcastle (Australia)

2016-06-15

Purpose: The MLC dosimetric leaf gap (DLG) and transmission are measured parameters which impact the dosimetric accuracy of IMRT and VMAT plans. This investigation aims to develop an efficient and accurate routine constancy check of the physical DLG in two dimensions. Methods: The manufacturer’s recommended DLG measurement method was modified by using 5 fields instead of 11 and by utilizing the Electronic Portal Imaging Device (EPID). Validations were accomplished using an ion chamber (IC) in solid water and a 2D IC array. EPID data was collected for 6 months on multiple TrueBeam linacs using both Millennium and HD MLCs at 5 different clinics in an international consortium. Matlab code was written to automatically analyze the images and calculate the 2D results. Sensitivity was investigated by introducing deliberate leaf position errors. MLC calibration and initialization history was recorded to allow quantification of their impact. Results were analyzed using statistical process control (SPC). Results: The EPID method took approximately 5 minutes. Due to detector response, the EPID measured DLG and transmission differed from the IC values but were reproducible and consistent with changes measured using the ICs. For the Millennium MLC, the EPID measured DLG and transmission were both consistently lower than IC results. The EPID method was implemented as leaf offset and transmission constancy tests (LOC and TC). Based on 6 months of measurements, the initial leaf-specific action thresholds for changes from baseline were set to 0.1 mm. Upper and lower control limits for variation were developed for each machine. Conclusion: Leaf offset and transmission constancy tests were implemented on Varian HD and Millennium MLCs using an EPID and found to be efficient and accurate. The test is effective for monitoring MLC performance using dynamic delivery and performing process control on the DLG in 2D, thus enhancing dosimetric accuracy. This work was supported by a grant

Characterization of the a-Si EPID in the unity MR-linac for dosimetric applications

Science.gov (United States)

Torres-Xirau, I.; Olaciregui-Ruiz, I.; Baldvinsson, G.; Mijnheer, B. J.; van der Heide, U. A.; Mans, A.

2018-01-01

Electronic portal imaging devices (EPIDs) are frequently used in external beam radiation therapy for dose verification purposes. The aim of this study was to investigate the dose-response characteristics of the EPID in the Unity MR-linac (Elekta AB, Stockholm, Sweden) relevant for dosimetric applications under clinical conditions. EPID images and ionization chamber (IC) measurements were used to study the effects of the magnetic field, the scatter generated in the MR housing reaching the EPID, and inhomogeneous attenuation from the MR housing. Dose linearity and dose rate dependencies were also determined. The magnetic field strength at EPID level did not exceed 10 mT, and dose linearity and dose rate dependencies proved to be comparable to that on a conventional linac. Profiles of fields, delivered with and without the magnetic field, were indistinguishable. The EPID center had an offset of 5.6 cm in the longitudinal direction, compared to the beam central axis, meaning that large fields in this direction will partially fall outside the detector area and not be suitable for verification. Beam attenuation by the MRI scanner and the table is gantry angle dependent, presenting a minimum attenuation of 67% relative to the 90° measurement. Repeatability, observed over two months, was within 0.5% (1 SD). In order to use the EPID for dosimetric applications in the MR-linac, challenges related to the EPID position, scatter from the MR housing, and the inhomogeneous, gantry angle-dependent attenuation of the beam will need to be solved.

21 CFR 573.340 - Diatomaceous earth.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Diatomaceous earth. 573.340 Section 573.340 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additive Listing § 573.340 Diatomaceous earth. (a) Identity. The additive consists of siliceous skeletal...

Impact of daily anatomical changes on EPID-based in vivo dosimetry of VMAT treatments of head-and-neck cancer

International Nuclear Information System (INIS)

Rozendaal, Roel A.; Mijnheer, Ben J.; Hamming-Vrieze, Olga; Mans, Anton; Herk, Marcel van

2015-01-01

Background and purpose: Target dose verification for VMAT treatments of head-and-neck (H&N) cancer using 3D in vivo EPID dosimetry is expected to be affected by daily anatomical changes. By including these anatomical changes through cone-beam CT (CBCT) information, the magnitude of this effect is investigated. Materials and methods: For 20 VMAT-treated H&N cancer patients, all plan-CTs (pCTs), 633 CBCTs and 1266 EPID movies were used to compare four dose distributions per fraction: treatment planning system (TPS) calculated dose and EPID reconstructed in vivo dose, both determined using the pCT and using the CBCT. D2, D50 and D98 of the planning target volume (PTV) were determined per dose distribution. Results: When including daily anatomical information, D2, D50 and D98 of the PTV change on average by 0.0 ± 0.4% according to TPS calculations; the standard deviation of the difference between EPID and TPS target dose changes from 2.5% (pCT) to 2.1% (CBCT). Small time trends are seen for both TPS and EPID dose distributions when using the pCT, which disappear when including CBCT information. Conclusions: Daily anatomical changes hardly influence the target dose distribution for H&N VMAT treatments according to TPS recalculations. Including CBCT information in EPID dose reconstructions slightly improves the agreement with TPS calculations

Development of a software of VMAT delivery using EPID

International Nuclear Information System (INIS)

Arumugam, Sankar; Xing, Aitang; Jameson, Michael; Holloway, Lois; Goozee, Gary

2011-01-01

Full text: Volumetric Modulated Arc Therapy (VMAT) is more complex than standard IMRT, requiring new methodology to evaluate delivery accuracy. Here, we present the development of methodology and a software tool to perform control point based verification of VMAT delivery using an EPID. Individual segment dose comparison allows the verification of VMAT deli very accuracy for individual control-points. An in-house software tool was developed to predict the individual segment dose as measured by EPID for Pinnacle (Philips) generated VMAT plans. The VMAT plans were delivered using an Elekta-synergy accelerator and the segment doses were measured using EPID. A normalised dose comparison of measured and predicted doses was performed using gamma analysis with 3% dose tolerance and 3 mm DTA. The sensitivity of the proposed methodology in detecting delivery errors was studied by delivering a standard intensity pattern with a preset dose error of 4 and 5% in two of its eight control-points. Four clinical plans were also tested using this methodology. The developed software accurately predicts the EPID dose by considering all possible leaf trajectories in VMAT delivery. The mean gamma value and percentage of pixels exceeding the gamma tolerance for a segment with and without delivery errors are shown in Table. From the tabulated values it is evident that the proposed methodology is sensitive in detecting delivery errors above 3% tolerance level. The clinical plans were successfully validated showing a maximum 2.5% of pixels exceeding gamma tolerance. Methodology and a software were successfully developed to perform control-point validation of VMAT delivery using an EPID. Set error in Delivery (%) Mean gamma value% of pixels exceeding Gamma tolerance 0 0.40 1.240.5417.050.6221.8.

Verification of PTV margins for IMRT prostate cancer using EPID; Verificacao das margens de PTV para IMRT de cancer de prostata utilizando EPID

Energy Technology Data Exchange (ETDEWEB)

Leidens, Matheus; Santos, Romulo R.; Estacio, Daniela R. [Pontificia Universidade Catolica do Rio Grande do Sul (PUCRS), Porto Alegre, RS (Brazil). Hospital Sao Lucas. Servico de Fisica Medica; Silva, Ana Maria Marques da, E-mail: matheus_leidens@hotmail.com [Pontificia Universidade Catolica do Rio Grande do Sul (PUCRS), Porto Alegre, RS (Brazil). Faculdade de Fisica

2014-12-15

The aim of this work is to present the results of a strategy to define the PTV margins for patients with prostate cancer treated with IMRT technique, due to geometrical uncertainties associated with the planned placement. 341 images of 31 patients in supine position, before applying the fractions, were obtained using an EPID attached to a linear accelerator, where only setup errors were studied. The displacements were analyzed in relation to the AP (antero-posterior), SI (superior-inferior) and LR (left-right) directions. The distribution pattern of systematic displacement deviation values were 0.12 cm, 0.06 cm, 0.02 cm and the standard deviation of the distribution of random deviations was 0.62 cm, 0.53 cm, and 0.24 cm in the AP, SI and LR directions, respectively. Data evaluation, according to Stroom and Heijmen’s method, suggests that PTV margins should be 0.66 cm in the AP direction, 0.49 cm in the SI direction and 0.20 cm in the LR direction. These data show a high reproducibility in the positioning of patients, given by a method for the correction of planned relative to the bony anatomy checked with the EPID position. (author)

21 CFR 573.440 - Ethylene dichloride.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Ethylene dichloride. 573.440 Section 573.440 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additive Listing § 573.440 Ethylene dichloride. The food additive ethylene dichloride may be safely used in...

21 CFR 573.260 - Calcium silicate.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Calcium silicate. 573.260 Section 573.260 Food and... Listing § 573.260 Calcium silicate. Calcium silicate, including synthetic calcium silicate, may be safely used as an anticaking agent in animal feed, provided that the amount of calcium silicate does not...

24 CFR 573.4 - Loan term.

Science.gov (United States)

2010-04-01

... 24 Housing and Urban Development 3 2010-04-01 2010-04-01 false Loan term. 573.4 Section 573.4 Housing and Urban Development Regulations Relating to Housing and Urban Development (Continued) OFFICE OF... COMMUNITY FACILITIES LOAN GUARANTEE RECOVERY FUND § 573.4 Loan term. The term of the loan to be guaranteed...

21 CFR 573.240 - Calcium periodate.

Science.gov (United States)

2010-04-01

... with calcium hydroxide or calcium oxide to form a substance consisting of not less than 60 percent by... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Calcium periodate. 573.240 Section 573.240 Food... Additive Listing § 573.240 Calcium periodate. The food additive calcium periodate may be safely used in...

21 CFR 573.420 - Ethyl cellulose.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Ethyl cellulose. 573.420 Section 573.420 Food and... Listing § 573.420 Ethyl cellulose. The food additive ethyl cellulose may be safely used in animal feed in accordance with the following prescribed conditions: (a) The food additive is a cellulose ether containing...

21 CFR 573.680 - Mineral oil.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Mineral oil. 573.680 Section 573.680 Food and... Listing § 573.680 Mineral oil. Mineral oil may be safely used in animal feed, subject to the provisions of this section. (a) Mineral oil, for the purpose of this section, is that complying with the definition...

MO-AB-BRA-03: Development of Novel Real Time in Vivo EPID Treatment Verification for Brachytherapy

Energy Technology Data Exchange (ETDEWEB)

Fonseca, G; Podesta, M [Department of Radiation Oncology (MAASTRO), GROW School for Oncology and Developmental Biology, Maastricht University Medical Center, Maastricht 6201 BN (Netherlands); Reniers, B [Department of Radiation Oncology (MAASTRO), GROW School for Oncology and Developmental Biology, Maastricht University Medical Center, Maastricht 6201 BN (Netherlands); Research Group NuTeC, CMK, Hasselt University, Agoralaan Gebouw H, Diepenbeek B-3590 (Belgium); Verhaegen, F [Department of Radiation Oncology (MAASTRO), GROW School for Oncology and Developmental Biology, Maastricht University Medical Center, Maastricht 6201 BN (Netherlands); Medical Physics Unit, Department of Oncology, McGill University, Montreal, Quebec H3G 1A4 (Canada)

2016-06-15

Purpose: High Dose Rate (HDR) brachytherapy treatments are employed worldwide to treat a wide variety of cancers. However, in vivo dose verification remains a challenge with no commercial dosimetry system available to verify the treatment dose delivered to the patient. We propose a novel dosimetry system that couples an independent Monte Carlo (MC) simulation platform and an amorphous silicon Electronic Portal Imaging Device (EPID) to provide real time treatment verification. Methods: MC calculations predict the EPID response to the photon fluence emitted by the HDR source by simulating the patient, the source dwell positions and times, and treatment complexities such as tissue compositions/densities and different applicators. Simulated results are then compared against EPID measurements acquired with ∼0.14s time resolution which allows dose measurements for each dwell position. The EPID has been calibrated using an Ir-192 HDR source and experiments were performed using different phantoms, including tissue equivalent materials (PMMA, lung and bone). A source positioning accuracy of 0.2 mm, without including the afterloader uncertainty, was ensured using a robotic arm moving the source. Results: An EPID can acquire 3D Cartesian source positions and its response varies significantly due to differences in the material composition/density of the irradiated object, allowing detection of changes in patient geometry. The panel time resolution allows dose rate and dwell time measurements. Moreover, predicted EPID images obtained from clinical treatment plans provide anatomical information that can be related to the patient anatomy, mostly bone and air cavities, localizing the source inside of the patient using its anatomy as reference. Conclusion: Results obtained show the feasibility of the proposed dose verification system that is capable to verify all the brachytherapy treatment steps in real time providing data about treatment delivery quality and also applicator

A system for EPID-based real-time treatment delivery verification during dynamic IMRT treatment

Energy Technology Data Exchange (ETDEWEB)

Fuangrod, Todsaporn [Faculty of Engineering and Built Environment, School of Electrical Engineering and Computer Science, the University of Newcastle, NSW 2308 (Australia); Woodruff, Henry C.; O’Connor, Daryl J. [Faculty of Science and IT, School of Mathematical and Physical Sciences, the University of Newcastle, NSW 2308 (Australia); Uytven, Eric van; McCurdy, Boyd M. C. [Division of Medical Physics, CancerCare Manitoba, 675 McDermot Avenue, Winnipeg, Manitoba R3E 0V9 (Canada); Department of Physics and Astronomy, University of Manitoba, Winnipeg, Manitoba R3T 2N2 (Canada); Department of Radiology, University of Manitoba, Winnipeg, Manitoba R3T 2N2 (Canada); Kuncic, Zdenka [School of Physics, University of Sydney, Sydney, NSW 2006 (Australia); Greer, Peter B. [Faculty of Science and IT, School of Mathematical and Physical Sciences, the University of Newcastle, NSW 2308, Australia and Department of Radiation Oncology, Calvary Mater Newcastle Hospital, Locked Bag 7, Hunter region Mail Centre, Newcastle, NSW 2310 (Australia)

2013-09-15

Purpose: To design and develop a real-time electronic portal imaging device (EPID)-based delivery verification system for dynamic intensity modulated radiation therapy (IMRT) which enables detection of gross treatment delivery errors before delivery of substantial radiation to the patient.Methods: The system utilizes a comprehensive physics-based model to generate a series of predicted transit EPID image frames as a reference dataset and compares these to measured EPID frames acquired during treatment. The two datasets are using MLC aperture comparison and cumulative signal checking techniques. The system operation in real-time was simulated offline using previously acquired images for 19 IMRT patient deliveries with both frame-by-frame comparison and cumulative frame comparison. Simulated error case studies were used to demonstrate the system sensitivity and performance.Results: The accuracy of the synchronization method was shown to agree within two control points which corresponds to approximately ∼1% of the total MU to be delivered for dynamic IMRT. The system achieved mean real-time gamma results for frame-by-frame analysis of 86.6% and 89.0% for 3%, 3 mm and 4%, 4 mm criteria, respectively, and 97.9% and 98.6% for cumulative gamma analysis. The system can detect a 10% MU error using 3%, 3 mm criteria within approximately 10 s. The EPID-based real-time delivery verification system successfully detected simulated gross errors introduced into patient plan deliveries in near real-time (within 0.1 s).Conclusions: A real-time radiation delivery verification system for dynamic IMRT has been demonstrated that is designed to prevent major mistreatments in modern radiation therapy.

A system for EPID-based real-time treatment delivery verification during dynamic IMRT treatment

International Nuclear Information System (INIS)

Fuangrod, Todsaporn; Woodruff, Henry C.; O’Connor, Daryl J.; Uytven, Eric van; McCurdy, Boyd M. C.; Kuncic, Zdenka; Greer, Peter B.

2013-01-01

Purpose: To design and develop a real-time electronic portal imaging device (EPID)-based delivery verification system for dynamic intensity modulated radiation therapy (IMRT) which enables detection of gross treatment delivery errors before delivery of substantial radiation to the patient.Methods: The system utilizes a comprehensive physics-based model to generate a series of predicted transit EPID image frames as a reference dataset and compares these to measured EPID frames acquired during treatment. The two datasets are using MLC aperture comparison and cumulative signal checking techniques. The system operation in real-time was simulated offline using previously acquired images for 19 IMRT patient deliveries with both frame-by-frame comparison and cumulative frame comparison. Simulated error case studies were used to demonstrate the system sensitivity and performance.Results: The accuracy of the synchronization method was shown to agree within two control points which corresponds to approximately ∼1% of the total MU to be delivered for dynamic IMRT. The system achieved mean real-time gamma results for frame-by-frame analysis of 86.6% and 89.0% for 3%, 3 mm and 4%, 4 mm criteria, respectively, and 97.9% and 98.6% for cumulative gamma analysis. The system can detect a 10% MU error using 3%, 3 mm criteria within approximately 10 s. The EPID-based real-time delivery verification system successfully detected simulated gross errors introduced into patient plan deliveries in near real-time (within 0.1 s).Conclusions: A real-time radiation delivery verification system for dynamic IMRT has been demonstrated that is designed to prevent major mistreatments in modern radiation therapy

MO-D-213-08: Remote Dosimetric Credentialing for Clinical Trials with the Virtual EPID Standard Phantom Audit (VESPA)

International Nuclear Information System (INIS)

Lehmann, J; Miri, N; Vial, P; Hatton, J; Zwan, B; Sloan, K; Craig, A; Beenstock, V; Molloy, T; Greer, P

2015-01-01

Purpose: Report on implementation of a Virtual EPID Standard Phantom Audit (VESPA) for IMRT to support credentialing of facilities for clinical trials. Data is acquired by local facility staff and transferred electronically. Analysis is performed centrally. Methods: VESPA is based on published methods and a clinically established IMRT QA procedure, here extended to multi-vendor equipment. Facilities, provided with web-based comprehensive instructions and CT datasets, create IMRT treatment plans. They deliver the treatments directly to their EPID without phantom or couch in the beam. They also deliver a set of simple calibration fields. Collected EPID images are uploaded electronically. In the analysis, the dose is projected back into a virtual phantom and 3D gamma analysis is performed. 2D dose planes and linear dose profiles can be analysed when needed for clarification. Results: Pilot facilities covering a range of planning and delivery systems have performed data acquisition and upload successfully. Analysis showed agreement comparable to local experience with the method. Advantages of VESPA are (1) fast turnaround mainly driven by the facility’s capability to provide the requested EPID images, (2) the possibility for facilities performing the audit in parallel, as there is no need to wait for a phantom, (3) simple and efficient credentialing for international facilities, (4) a large set of data points, and (5) a reduced impact on resources and environment as there is no need to transport heavy phantoms or audit staff. Limitations of the current implementation of VESPA for trials credentialing are that it does not provide absolute dosimetry, therefore a Level 1 audit still required, and that it relies on correctly delivered open calibration fields, which are used for system calibration. Conclusion: The implemented EPID based IMRT audit system promises to dramatically improve credentialing efficiency for clinical trials and wider applications. VESPA for VMAT

MO-D-213-08: Remote Dosimetric Credentialing for Clinical Trials with the Virtual EPID Standard Phantom Audit (VESPA)

Energy Technology Data Exchange (ETDEWEB)

Lehmann, J [Calvary Mater Newcastle, Newcastle, NSW (Australia); University of Sydney, Sydney, NSW (Australia); Miri, N [University of Newcastle, Newcastle, NSW (Australia); Vial, P [Liverpool Hospital, Liverpool, NSW (Australia); Hatton, J [Trans Tasman Radiation Oncology Group (TROG), Newcastle, NSW (Australia); Zwan, B; Sloan, K [Gosford Hospital, Gosford, NSW (Australia); Craig, A; Beenstock, V [Canterbury Regional Cancer and Haematology Service, Christchurch (New Zealand); Molloy, T [Orange Hospital, Orange, NSW (Australia); Greer, P [Calvary Mater Newcastle, Newcastle, NSW (Australia); University of Newcastle, Newcastle, NSW (Australia)

2015-06-15

Purpose: Report on implementation of a Virtual EPID Standard Phantom Audit (VESPA) for IMRT to support credentialing of facilities for clinical trials. Data is acquired by local facility staff and transferred electronically. Analysis is performed centrally. Methods: VESPA is based on published methods and a clinically established IMRT QA procedure, here extended to multi-vendor equipment. Facilities, provided with web-based comprehensive instructions and CT datasets, create IMRT treatment plans. They deliver the treatments directly to their EPID without phantom or couch in the beam. They also deliver a set of simple calibration fields. Collected EPID images are uploaded electronically. In the analysis, the dose is projected back into a virtual phantom and 3D gamma analysis is performed. 2D dose planes and linear dose profiles can be analysed when needed for clarification. Results: Pilot facilities covering a range of planning and delivery systems have performed data acquisition and upload successfully. Analysis showed agreement comparable to local experience with the method. Advantages of VESPA are (1) fast turnaround mainly driven by the facility’s capability to provide the requested EPID images, (2) the possibility for facilities performing the audit in parallel, as there is no need to wait for a phantom, (3) simple and efficient credentialing for international facilities, (4) a large set of data points, and (5) a reduced impact on resources and environment as there is no need to transport heavy phantoms or audit staff. Limitations of the current implementation of VESPA for trials credentialing are that it does not provide absolute dosimetry, therefore a Level 1 audit still required, and that it relies on correctly delivered open calibration fields, which are used for system calibration. Conclusion: The implemented EPID based IMRT audit system promises to dramatically improve credentialing efficiency for clinical trials and wider applications. VESPA for VMAT

21 CFR 573.480 - Formic acid.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Formic acid. 573.480 Section 573.480 Food and... Listing § 573.480 Formic acid. Formic acid may be safely used as a preservative in hay crop silage in an.... The top foot of silage stored should not contain formic acid and silage should not be fed to livestock...

MO-FG-202-07: Real-Time EPID-Based Detection Metric For VMAT Delivery Errors

International Nuclear Information System (INIS)

Passarge, M; Fix, M K; Manser, P; Stampanoni, M F M; Siebers, J V

2016-01-01

Purpose: To create and test an accurate EPID-frame-based VMAT QA metric to detect gross dose errors in real-time and to provide information about the source of error. Methods: A Swiss cheese model was created for an EPID-based real-time QA process. The system compares a treatmentplan- based reference set of EPID images with images acquired over each 2° gantry angle interval. The metric utilizes a sequence of independent consecutively executed error detection Methods: a masking technique that verifies infield radiation delivery and ensures no out-of-field radiation; output normalization checks at two different stages; global image alignment to quantify rotation, scaling and translation; standard gamma evaluation (3%, 3 mm) and pixel intensity deviation checks including and excluding high dose gradient regions. Tolerances for each test were determined. For algorithm testing, twelve different types of errors were selected to modify the original plan. Corresponding predictions for each test case were generated, which included measurement-based noise. Each test case was run multiple times (with different noise per run) to assess the ability to detect introduced errors. Results: Averaged over five test runs, 99.1% of all plan variations that resulted in patient dose errors were detected within 2° and 100% within 4° (∼1% of patient dose delivery). Including cases that led to slightly modified but clinically equivalent plans, 91.5% were detected by the system within 2°. Based on the type of method that detected the error, determination of error sources was achieved. Conclusion: An EPID-based during-treatment error detection system for VMAT deliveries was successfully designed and tested. The system utilizes a sequence of methods to identify and prevent gross treatment delivery errors. The system was inspected for robustness with realistic noise variations, demonstrating that it has the potential to detect a large majority of errors in real-time and indicate the error

MO-FG-202-07: Real-Time EPID-Based Detection Metric For VMAT Delivery Errors

Energy Technology Data Exchange (ETDEWEB)

Passarge, M; Fix, M K; Manser, P [Division of Medical Radiation Physics and Department of Radiation Oncology, Inselspital, Bern University Hospital, and University of Bern, Bern (Switzerland); Stampanoni, M F M [Institute for Biomedical Engineering, ETH Zurich, and PSI, Villigen (Switzerland); Siebers, J V [Department of Radiation Oncology, University of Virginia, Charlottesville, VA (United States)

2016-06-15

Purpose: To create and test an accurate EPID-frame-based VMAT QA metric to detect gross dose errors in real-time and to provide information about the source of error. Methods: A Swiss cheese model was created for an EPID-based real-time QA process. The system compares a treatmentplan- based reference set of EPID images with images acquired over each 2° gantry angle interval. The metric utilizes a sequence of independent consecutively executed error detection Methods: a masking technique that verifies infield radiation delivery and ensures no out-of-field radiation; output normalization checks at two different stages; global image alignment to quantify rotation, scaling and translation; standard gamma evaluation (3%, 3 mm) and pixel intensity deviation checks including and excluding high dose gradient regions. Tolerances for each test were determined. For algorithm testing, twelve different types of errors were selected to modify the original plan. Corresponding predictions for each test case were generated, which included measurement-based noise. Each test case was run multiple times (with different noise per run) to assess the ability to detect introduced errors. Results: Averaged over five test runs, 99.1% of all plan variations that resulted in patient dose errors were detected within 2° and 100% within 4° (∼1% of patient dose delivery). Including cases that led to slightly modified but clinically equivalent plans, 91.5% were detected by the system within 2°. Based on the type of method that detected the error, determination of error sources was achieved. Conclusion: An EPID-based during-treatment error detection system for VMAT deliveries was successfully designed and tested. The system utilizes a sequence of methods to identify and prevent gross treatment delivery errors. The system was inspected for robustness with realistic noise variations, demonstrating that it has the potential to detect a large majority of errors in real-time and indicate the error

SU-E-T-775: Use of Electronic Portal Imaging Device (EPID) for Quality Assurance (QA) of Electron Beams On Varian Truebeam System

Energy Technology Data Exchange (ETDEWEB)

Cai, B; Yaddanapudi, S; Sun, B; Li, H; Noel, C; Mutic, S; Goddu, S [Department of Radiation Oncology, Washington University in St Louis, St. Louis, MO (United States)

2015-06-15

Purpose: In a previous study we have demonstrated the feasibility of using EPID to QA electron beam parameters on a single Varian TrueBeam LINAC. This study aims to provide further investigation on (1) reproducibility of using EPID to detect electron beam energy changes on multiple machines and (2) evaluation of appropriate calibration methods to compare results from different EPIDs. Methods: Ad-hoc mode electron beam images were acquired in developer mode with XML code. Electron beam data were collected on a total of six machines from four institutions. A custom-designed double-wedge phantom was placed on the EPID detector. Two calibration methods - Pixel Sensitivity Map (PSM) and Large Source-to-Imager Distance Flood Field (LSID-FF) - were used. To test the sensitivity of EPID in detecting energy drifts, Bending Magnet Current (BMC) was detuned to invoke energy changes corresponding to ∼±1.5 mm change in R50% of PDD on two machines from two institutions. Percent depth ionization (PDI) curves were then analyzed and compared with the respective baseline images using LSID-FF calibration. For reproducibility testing, open field EPID images and images with a standard testing phantom were collected on multiple machines. Images with and without PSM correction for same energies on different machines were overlaid and compared. Results: Two pixel shifts were observed in PDI curve when energy changes exceeded the TG142 tolerance. PSM showed the potential to correct the differences in pixel response of different imagers. With PSM correction, the histogram of images differences obtained from different machines showed narrower distributions than those images without PSM correction. Conclusion: EPID is sensitive for electron energy changes and the results are reproducible on different machines. When overlaying images from different machines, PSM showed the ability to partially eliminate the intrinsic variation of various imagers. Research Funding from Varian Medical Systems

21 CFR 573.625 - Menadione nicotinamide bisulfite.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Menadione nicotinamide bisulfite. 573.625 Section 573.625 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... ANIMALS Food Additive Listing § 573.625 Menadione nicotinamide bisulfite. The food additive may be safely...

A comprehensive study of the mechanical performance of gantry, EPID and the MLC assembly in Elekta linacs during gantry rotation

DEFF Research Database (Denmark)

Rowshanfarzad, P; Lynggaard Riis, Hans; Zimmermann, S J

2015-01-01

OBJECTIVE: In radiotherapy treatments, it is crucial to monitor the performance of linear accelerator (linac) components, including gantry, collimation system and electronic portal imaging device (EPID) during arc deliveries. In this study, a simple EPID-based measurement method is suggested...... collimator leaf bank assemblies was around 1 mm. A meaningful correlation was found between the age of the linacs and their mechanical performance. Conclusions and Advances in knowledge: The method and software developed in this study provide a simple tool for effective investigation of the behaviour...

A quantitative method to the analysis of MLC leaf position and speed based on EPID and EBT3 film for dynamic IMRT treatment with different types of MLC.

Science.gov (United States)

Li, Yinghui; Chen, Lixin; Zhu, Jinhan; Wang, Bin; Liu, Xiaowei

2017-07-01

A quantitative method based on the electronic portal imaging system (EPID) and film was developed for MLC position and speed testing; this method was used for three MLC types (Millennium, MLCi, and Agility MLC). To determine the leaf position, a picket fence designed by the dynamic (DMLC) model was used. The full-width half-maximum (FWHM) values of each gap measured by EPID and EBT3 were converted to the gap width using the FWHM versus nominal gap width relationship. The algorithm developed for the picket fence analysis was able to quantify the gap width, the distance between gaps, and each individual leaf position. To determine the leaf speed, a 0.5 × 20 cm 2 MLC-defined sliding gap was applied across a 14 × 20 cm 2 symmetry field. The linacs ran at a fixed-dose rate. The use of different monitor units (MUs) for this test led to different leaf speeds. The effect of leaf transmission was considered in a speed accuracy analysis. The difference between the EPID and film results for the MLC position is less than 0.1 mm. For the three MLC types, twice the standard deviation (2 SD) is provided; 0.2, 0.4, and 0.4 mm for gap widths of three MLC types, and 0.1, 0.2, and 0.2 mm for distances between gaps. The individual leaf positions deviate from the preset positions within 0.1 mm. The variations in the speed profiles for the EPID and EBT3 results are consistent, but the EPID results are slightly better than the film results. Different speeds were measured for each MLC type. For all three MLC types, speed errors increase with increasing speed. The analysis speeds deviate from the preset speeds within approximately 0.01 cm s -1 . This quantitative analysis of MLC position and speed provides an intuitive evaluation for MLC quality assurance (QA). © 2017 The Authors. Journal of Applied Clinical Medical Physics published by Wiley Periodicals, Inc. on behalf of American Association of Physicists in Medicine.

21 CFR 573.160 - Ammoniated rice hulls.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Ammoniated rice hulls. 573.160 Section 573.160... Additive Listing § 573.160 Ammoniated rice hulls. The food additive ammoniated rice hulls may be safely... obtained by the treatment of ground rice hulls with monocalcium phosphate and anhydrous ammonia at a...

Characterization of an extremely salt-tolerant and thermostable phytase from Bacillus amyloliquefaciens US573.

Science.gov (United States)

Boukhris, Ines; Farhat-Khemakhem, Ameny; Blibech, Monia; Bouchaala, Kameleddine; Chouayekh, Hichem

2015-09-01

The extracellular phytase produced by the Bacillus amyloliquefaciens US573 strain, isolated from geothermal soil located in Southern Tunisia was purified and characterized. This calcium-dependent and bile-stable enzyme (PHY US573) was optimally active at pH 7.5 and 70 °C. It showed a good stability at pH ranging from 4 to 10, and especially, an exceptional thermostability as it recovered 50 and 62% of activity after heating for 10 min at 100 and 90 °C, respectively. In addition, PHY US573 was found to be extremely salt-tolerant since it preserved 80 and 95% of activity in the presence of 20 g/l of NaCl and LiCl, respectively. The gene corresponding to PHY US573 was cloned. It encodes a 383 amino acids polypeptide exhibiting 99% identity with the highly thermostable phytases from Bacillus sp. MD2 and B. amyloliquefaciens DS11 (3 and 5 residues difference, respectively), suggesting the existence of common molecular determinants responsible for their remarkable heat stability. Overall, our findings illustrated that in addition to its high potential for application in feed industry, the salt tolerance of the PHY US573 phytase, may represent an exciting new avenue for improvement of phosphorus-use efficiency of salt-tolerant plants in soils with high salt and phytate content. Copyright © 2015 Elsevier B.V. All rights reserved.

TU-G-BRD-08: In-Vivo EPID Dosimetry: Quantifying the Detectability of Four Classes of Errors

Energy Technology Data Exchange (ETDEWEB)

Ford, E; Phillips, M; Bojechko, C [University of Washington, Seattle, WA (United States)

2015-06-15

Purpose: EPID dosimetry is an emerging method for treatment verification and QA. Given that the in-vivo EPID technique is in clinical use at some centers, we investigate the sensitivity and specificity for detecting different classes of errors. We assess the impact of these errors using dose volume histogram endpoints. Though data exist for EPID dosimetry performed pre-treatment, this is the first study quantifying its effectiveness when used during patient treatment (in-vivo). Methods: We analyzed 17 patients; EPID images of the exit dose were acquired and used to reconstruct the planar dose at isocenter. This dose was compared to the TPS dose using a 3%/3mm gamma criteria. To simulate errors, modifications were made to treatment plans using four possible classes of error: 1) patient misalignment, 2) changes in patient body habitus, 3) machine output changes and 4) MLC misalignments. Each error was applied with varying magnitudes. To assess the detectability of the error, the area under a ROC curve (AUC) was analyzed. The AUC was compared to changes in D99 of the PTV introduced by the simulated error. Results: For systematic changes in the MLC leaves, changes in the machine output and patient habitus, the AUC varied from 0.78–0.97 scaling with the magnitude of the error. The optimal gamma threshold as determined by the ROC curve varied between 84–92%. There was little diagnostic power in detecting random MLC leaf errors and patient shifts (AUC 0.52–0.74). Some errors with weak detectability had large changes in D99. Conclusion: These data demonstrate the ability of EPID-based in-vivo dosimetry in detecting variations in patient habitus and errors related to machine parameters such as systematic MLC misalignments and machine output changes. There was no correlation found between the detectability of the error using the gamma pass rate, ROC analysis and the impact on the dose volume histogram. Funded by grant R18HS022244 from AHRQ.

An initial study on the estimation of time-varying volumetric treatment images and 3D tumor localization from single MV cine EPID images

Energy Technology Data Exchange (ETDEWEB)

Mishra, Pankaj, E-mail: pankaj.mishra@varian.com; Mak, Raymond H.; Rottmann, Joerg; Bryant, Jonathan H.; Williams, Christopher L.; Berbeco, Ross I.; Lewis, John H. [Brigham and Women' s Hospital, Dana-Farber Cancer Institute and Harvard Medical School, Boston, Massachusetts 02115 (United States); Li, Ruijiang [Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California 94305 (United States)

2014-08-15

Purpose: In this work the authors develop and investigate the feasibility of a method to estimate time-varying volumetric images from individual MV cine electronic portal image device (EPID) images. Methods: The authors adopt a two-step approach to time-varying volumetric image estimation from a single cine EPID image. In the first step, a patient-specific motion model is constructed from 4DCT. In the second step, parameters in the motion model are tuned according to the information in the EPID image. The patient-specific motion model is based on a compact representation of lung motion represented in displacement vector fields (DVFs). DVFs are calculated through deformable image registration (DIR) of a reference 4DCT phase image (typically peak-exhale) to a set of 4DCT images corresponding to different phases of a breathing cycle. The salient characteristics in the DVFs are captured in a compact representation through principal component analysis (PCA). PCA decouples the spatial and temporal components of the DVFs. Spatial information is represented in eigenvectors and the temporal information is represented by eigen-coefficients. To generate a new volumetric image, the eigen-coefficients are updated via cost function optimization based on digitally reconstructed radiographs and projection images. The updated eigen-coefficients are then multiplied with the eigenvectors to obtain updated DVFs that, in turn, give the volumetric image corresponding to the cine EPID image. Results: The algorithm was tested on (1) Eight digital eXtended CArdiac-Torso phantom datasets based on different irregular patient breathing patterns and (2) patient cine EPID images acquired during SBRT treatments. The root-mean-squared tumor localization error is (0.73 ± 0.63 mm) for the XCAT data and (0.90 ± 0.65 mm) for the patient data. Conclusions: The authors introduced a novel method of estimating volumetric time-varying images from single cine EPID images and a PCA-based lung motion model

Dosimetric characterization of an a-based EPID for quality control if patient-specific IMRT

International Nuclear Information System (INIS)

Larrinaga Cortina, Eduardo Francisco; Alfonso Laguardia, Rodolfo; Silvestre Patallo, Ileana; Garcia Yip, Fernando

2009-01-01

The Electronic portal imaging devices, EPID for its acronym in English is a technology widely used for verification of patient positioning on linear accelerators routinely. Its use as a dosimetry device is not as widespread, although many researches in this field. It assessed the availability and versatility of the use EPID based on an amorphous silicon (a-Si) as a means of quality control specific patient for a methodology of Radiation Intensity Modulated IMRT. Dosimetric parameters were determined for the linearity of dose versus response, dispersion and sensitivity factors off-axis radiation. For absolute measurements the linearity of the dose-response relationship EPID was better than 1.1 and 1.5% for photon beams of 6 and 15mV respectively, in the range from 2 to 500 UM. The dose dependence with field size was studied and compared with the factors of dispersion in water at different depths, in agreement with those measured at 5 cm depth, Scp (z = 5cm). Off-axis sensitivity of the EPID was determined by comparing the measured profiles versus the same profiles at different depths in water. The best correspondence was observed at 5 cm depth, where the EPID response underestimates the dose to 4% for all sizes of fields in the plateau area. The EPID can be used for the evaluation of dosimetric parameters of the beam at a specific depth in water of 5 cm and a discrepancy in an acceptable maximum rate of 4%. (author)

Managing the backscatter component from the robotic arm of an a-Si EPID

International Nuclear Information System (INIS)

Lee, C.G.; Menk, F.; Greer, P.B.

2010-01-01

Full text: Backscatter from the robotic arm mechanism of an a-Si EPID in IMRT images was examined. Images corrected with a conventional flood field (FF) containing a backscatter component (BSC) from the robotic ann were compared with a BSC-free FF. A Yarian 21 EX linac (6 MV, 18 MV) was used. All images were acquired with two aS500 EPIDs, one R-arm and one E-arm. The BSC of an EPID image is the ratio of an image acquired with the EPID attached to the arm then detaching the arm from the EPID and acquiring the same image. A range of square field sizes from 2.5 x 2.5 cm to 27.5 x 27.5 cm were acquired and the BSC analyzed. The BSC of the FFs were also measured. A series of IMRT fields were acquired. Each field was corrected with a conventional FF and compared with a BSC-free FF. Figure I shows the magnitude of the BSC from each arm in the inplane for a 6 x beam. Square fields above 16 x l6 cm (R-arm) and lO x 10 cm (E-arm) benefited from a conventional FF as it tended to cancel out the BSC in the acquired square field. The opposite was observed for smaller field sizes. A gamma analysis of the IMRT fields showed a FF correction containing a BSC reduces the effect of the arm in the final image. IMRT EPID images using conventional FFs have been shown to be less affected by backscatter from the robotic arm compared to BSC-free flood fields. (author)

A system for EPID-based real-time treatment delivery verification during dynamic IMRT treatment.

Science.gov (United States)

Fuangrod, Todsaporn; Woodruff, Henry C; van Uytven, Eric; McCurdy, Boyd M C; Kuncic, Zdenka; O'Connor, Daryl J; Greer, Peter B

2013-09-01

To design and develop a real-time electronic portal imaging device (EPID)-based delivery verification system for dynamic intensity modulated radiation therapy (IMRT) which enables detection of gross treatment delivery errors before delivery of substantial radiation to the patient. The system utilizes a comprehensive physics-based model to generate a series of predicted transit EPID image frames as a reference dataset and compares these to measured EPID frames acquired during treatment. The two datasets are using MLC aperture comparison and cumulative signal checking techniques. The system operation in real-time was simulated offline using previously acquired images for 19 IMRT patient deliveries with both frame-by-frame comparison and cumulative frame comparison. Simulated error case studies were used to demonstrate the system sensitivity and performance. The accuracy of the synchronization method was shown to agree within two control points which corresponds to approximately ∼1% of the total MU to be delivered for dynamic IMRT. The system achieved mean real-time gamma results for frame-by-frame analysis of 86.6% and 89.0% for 3%, 3 mm and 4%, 4 mm criteria, respectively, and 97.9% and 98.6% for cumulative gamma analysis. The system can detect a 10% MU error using 3%, 3 mm criteria within approximately 10 s. The EPID-based real-time delivery verification system successfully detected simulated gross errors introduced into patient plan deliveries in near real-time (within 0.1 s). A real-time radiation delivery verification system for dynamic IMRT has been demonstrated that is designed to prevent major mistreatments in modern radiation therapy.

An EPID response calculation algorithm using spatial beam characteristics of primary, head scattered and MLC transmitted radiation

International Nuclear Information System (INIS)

Rosca, Florin; Zygmanski, Piotr

2008-01-01

We have developed an independent algorithm for the prediction of electronic portal imaging device (EPID) response. The algorithm uses a set of images [open beam, closed multileaf collimator (MLC), various fence and modified sweeping gap patterns] to separately characterize the primary and head-scatter contributions to EPID response. It also characterizes the relevant dosimetric properties of the MLC: Transmission, dosimetric gap, MLC scatter [P. Zygmansky et al., J. Appl. Clin. Med. Phys. 8(4) (2007)], inter-leaf leakage, and tongue and groove [F. Lorenz et al., Phys. Med. Biol. 52, 5985-5999 (2007)]. The primary radiation is modeled with a single Gaussian distribution defined at the target position, while the head-scatter radiation is modeled with a triple Gaussian distribution defined downstream of the target. The distances between the target and the head-scatter source, jaws, and MLC are model parameters. The scatter associated with the EPID is implicit in the model. Open beam images are predicted to within 1% of the maximum value across the image. Other MLC test patterns and intensity-modulated radiation therapy fluences are predicted to within 1.5% of the maximum value. The presented method was applied to the Varian aS500 EPID but is designed to work with any planar detector with sufficient spatial resolution

MO-FG-202-01: A Fast Yet Sensitive EPID-Based Real-Time Treatment Verification System

International Nuclear Information System (INIS)

Ahmad, M; Nourzadeh, H; Neal, B; Siebers, J; Watkins, W

2016-01-01

Purpose: To create a real-time EPID-based treatment verification system which robustly detects treatment delivery and patient attenuation variations. Methods: Treatment plan DICOM files sent to the record-and-verify system are captured and utilized to predict EPID images for each planned control point using a modified GPU-based digitally reconstructed radiograph algorithm which accounts for the patient attenuation, source energy fluence, source size effects, and MLC attenuation. The DICOM and predicted images are utilized by our C++ treatment verification software which compares EPID acquired 1024×768 resolution frames acquired at ∼8.5hz from Varian Truebeam™ system. To maximize detection sensitivity, image comparisons determine (1) if radiation exists outside of the desired treatment field; (2) if radiation is lacking inside the treatment field; (3) if translations, rotations, and magnifications of the image are within tolerance. Acquisition was tested with known test fields and prior patient fields. Error detection was tested in real-time and utilizing images acquired during treatment with another system. Results: The computational time of the prediction algorithms, for a patient plan with 350 control points and 60×60×42cm^3 CT volume, is 2–3minutes on CPU and <27 seconds on GPU for 1024×768 images. The verification software requires a maximum of ∼9ms and ∼19ms for 512×384 and 1024×768 resolution images, respectively, to perform image analysis and dosimetric validations. Typical variations in geometric parameters between reference and the measured images are 0.32°for gantry rotation, 1.006 for scaling factor, and 0.67mm for translation. For excess out-of-field/missing in-field fluence, with masks extending 1mm (at isocenter) from the detected aperture edge, the average total in-field area missing EPID fluence was 1.5mm2 the out-of-field excess EPID fluence was 8mm^2, both below error tolerances. Conclusion: A real-time verification software, with

MO-FG-202-01: A Fast Yet Sensitive EPID-Based Real-Time Treatment Verification System

Energy Technology Data Exchange (ETDEWEB)

Ahmad, M; Nourzadeh, H; Neal, B; Siebers, J [University of Virginia Health System, Charlottesville, VA (United States); Watkins, W

2016-06-15

Purpose: To create a real-time EPID-based treatment verification system which robustly detects treatment delivery and patient attenuation variations. Methods: Treatment plan DICOM files sent to the record-and-verify system are captured and utilized to predict EPID images for each planned control point using a modified GPU-based digitally reconstructed radiograph algorithm which accounts for the patient attenuation, source energy fluence, source size effects, and MLC attenuation. The DICOM and predicted images are utilized by our C++ treatment verification software which compares EPID acquired 1024×768 resolution frames acquired at ∼8.5hz from Varian Truebeam™ system. To maximize detection sensitivity, image comparisons determine (1) if radiation exists outside of the desired treatment field; (2) if radiation is lacking inside the treatment field; (3) if translations, rotations, and magnifications of the image are within tolerance. Acquisition was tested with known test fields and prior patient fields. Error detection was tested in real-time and utilizing images acquired during treatment with another system. Results: The computational time of the prediction algorithms, for a patient plan with 350 control points and 60×60×42cm^3 CT volume, is 2–3minutes on CPU and <27 seconds on GPU for 1024×768 images. The verification software requires a maximum of ∼9ms and ∼19ms for 512×384 and 1024×768 resolution images, respectively, to perform image analysis and dosimetric validations. Typical variations in geometric parameters between reference and the measured images are 0.32°for gantry rotation, 1.006 for scaling factor, and 0.67mm for translation. For excess out-of-field/missing in-field fluence, with masks extending 1mm (at isocenter) from the detected aperture edge, the average total in-field area missing EPID fluence was 1.5mm2 the out-of-field excess EPID fluence was 8mm^2, both below error tolerances. Conclusion: A real-time verification software, with

Comparative performance evaluation of a new a-Si EPID that exceeds quad high-definition resolution.

Science.gov (United States)

McConnell, Kristen A; Alexandrian, Ara; Papanikolaou, Niko; Stathakis, Sotiri

2018-01-01

Electronic portal imaging devices (EPIDs) are an integral part of the radiation oncology workflow for treatment setup verification. Several commercial EPID implementations are currently available, each with varying capabilities. To standardize performance evaluation, Task Group Report 58 (TG-58) and TG-142 outline specific image quality metrics to be measured. A LinaTech Image Viewing System (IVS), with the highest commercially available pixel matrix (2688x2688 pixels), was independently evaluated and compared to an Elekta iViewGT (1024x1024 pixels) and a Varian aSi-1000 (1024x768 pixels) using a PTW EPID QC Phantom. The IVS, iViewGT, and aSi-1000 were each used to acquire 20 images of the PTW QC Phantom. The QC phantom was placed on the couch and aligned at isocenter. The images were exported and analyzed using the epidSoft image quality assurance (QA) software. The reported metrics were signal linearity, isotropy of signal linearity, signal-tonoise ratio (SNR), low contrast resolution, and high-contrast resolution. These values were compared between the three EPID solutions. Computed metrics demonstrated comparable results between the EPID solutions with the IVS outperforming the aSi-1000 and iViewGT in the low and high-contrast resolution analysis. The performance of three commercial EPID solutions have been quantified, evaluated, and compared using results from the PTW QC Phantom. The IVS outperformed the other panels in low and high-contrast resolution, but to fully realize the benefits of the IVS, the selection of the monitor on which to view the high-resolution images is important to prevent down sampling and visual of resolution.

SU-E-T-781: Using An Electronic Portal Imaging Device (EPID) for Correlating Linac Photon Beam Energies

Energy Technology Data Exchange (ETDEWEB)

Yaddanapudi, S; Cai, B; Sun, B; Noel, C; Goddu, S; Mutic, S [Washington University School of Medicine, Saint Louis, MO (United States)

2015-06-15

Purpose: Electronic portal imaging devices (EPIDs) have proven to be useful for measuring several parameters of interest in linear accelerator (linac) quality assurance (QA). The purpose of this project was to evaluate the feasibility of using EPIDs for determining linac photon beam energies. Methods: Two non-clinical Varian TrueBeam linacs (Varian Medical Systems, Palo Alto, CA) with 6MV and 10MV photon beams were used to perform the measurements. The linacs were equipped with an amorphous silicon based EPIDs (aSi1000) that were used for the measurements. We compared the use of flatness versus percent depth dose (PDD) for predicting changes in linac photon beam energy. PDD was measured in 1D water tank (Sun Nuclear Corporation, Melbourne FL) and the profiles were measured using 2D ion-chamber array (IC-Profiler, Sun Nuclear) and the EPID. Energy changes were accomplished by varying the bending magnet current (BMC). The evaluated energies conformed with the AAPM TG142 tolerance of ±1% change in PDD. Results: BMC changes correlating with a ±1% change in PDD corresponded with a change in flatness of ∼1% to 2% from baseline values on the EPID. IC Profiler flatness values had the same correlation. We observed a similar trend for the 10MV beam energy changes. Our measurements indicated a strong correlation between changes in linac photon beam energy and changes in flatness. For all machines and energies, beam energy changes produced change in the uniformity (AAPM TG-142), varying from ∼1% to 2.5%. Conclusions: EPID image analysis of beam profiles can be used to determine linac photon beam energy changes. Flatness-based metrics or uniformity as defined by AAPM TG-142 were found to be more sensitive to linac photon beam energy changes than PDD. Research funding provided by Varian Medical Systems. Dr. Sasa Mutic receives compensation for providing patient safety training services from Varian Medical Systems, the sponsor of this study.

An assessment of a 3D EPID-based dosimetry system using conventional two- and three-dimensional detectors for VMAT.

Science.gov (United States)

Stevens, S; Dvorak, P; Spevacek, V; Pilarova, K; Bray-Parry, M; Gesner, J; Richmond, A

2018-01-01

To provide a 3D dosimetric evaluation of a commercial portal dosimetry system using 2D/3D detectors under ideal conditions using VMAT. A 2D ion chamber array, radiochromic film and gel dosimeter were utilised to provide a dosimetric evaluation of transit phantom and pre-treatment 'fluence' EPID back-projected dose distributions for a standard VMAT plan. In-house 2D and 3D gamma methods compared pass statistics relative to each dosimeter and TPS dose distributions. Fluence mode and transit EPID dose distributions back-projected onto phantom geometry produced 2D gamma pass rates in excess of 97% relative to other tested detectors and exported TPS dose planes when a 3%, 3 mm global gamma criterion was applied. Use of a gel dosimeter within a glass vial allowed comparison of measured 3D dose distributions versus EPID 3D dose and TPS calculated distributions. 3D gamma comparisons between modalities at 3%, 3 mm gave pass rates in excess of 92%. Use of fluence mode was indicative of transit results under ideal conditions with slightly reduced dose definition. 3D EPID back projected dose distributions were validated against detectors in both 2D and 3D. Cross validation of transit dose delivered to a patient is limited due to reasons of practicality and the tests presented are recommended as a guideline for 3D EPID dosimetry commissioning; allowing direct comparison between detector, TPS, fluence and transit modes. The results indicate achievable gamma scores for a complex VMAT plan in a homogenous phantom geometry and contributes to growing experience of 3D EPID dosimetry. Copyright © 2017 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

21 CFR 573.750 - Pichia pastoris dried yeast.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Pichia pastoris dried yeast. 573.750 Section 573... Food Additive Listing § 573.750 Pichia pastoris dried yeast. (a) Identity. The food additive Pichia pastoris dried yeast may be used in feed formulations of broiler chickens as a source of protein not to...

Ghosting effect in Siemens electronic portal imaging devices (EPIDs) for step and shoot IMRT dosimetry

International Nuclear Information System (INIS)

Deshpande, S.; Vial, P.; Goozee, G.; Holloway, L.

2010-01-01

Full text: To assess the ghosting effect of a Siemens EPID (Optivue 1000: while acquiring IMRT fluence with step and shoot delivery. Six sets of segmented fields with 1,2,3,5, J( and 20 monitor units (MU) per segment were designed. Each set consisted of ten segments of equal MU and field size (J 0 x 10 cm 2 ) Standard single fields (non-segmented) of the same total MU as the segmented fields were also created (10-200 MU). EPID images for these fields were acquired with multi-frame acquisition mode. The integrated EPID response was determined as the mean central 20 x 21 pixel readout multiplied by the number of frames. The same fields wen measured with an ionization chamber at a depth of dose maximum in, solid water phantom. The total signal measured from the segmented fields was compared to the corresponding non-segmented fields. The ratio of EPID response between segmented and non-segmented delivery indicates an under-response for segmented fields by 5, 4, 2.5 and 2% for 1,2,3, and 5 MU per segment exposures respectively compared to ionisation chamber response (se Fig. I). The ratio was within 2% for 5 MU per segment and above. Th error bar in Fig. I indicate the intra-segment response variation. The Siemens EPID exhibited significant ghosting effect and variation in response for small M U segments. EPID dosimetry ( IMRT fields with less than 5 MU per segment requires corrections t maintain dose calibration accuracy to within 2%. (author)

SU-G-TeP2-01: Can EPID Based Measurement Replace Traditional Daily Output QA On Megavoltage Linac?

International Nuclear Information System (INIS)

Saleh, Z; Tang, X; Song, Y; Obcemea, C; Beeban, N; Chan, M; Li, X; Tang, G; Lim, S; Lovelock, D; LoSasso, T; Mechalakos, J; Both, S

2016-01-01

Purpose: To investigate the long term stability and viability of using EPID-based daily output QA via in-house and vendor driven protocol, to replace conventional QA tools and improve QA efficiency. Methods: Two Varian TrueBeam machines (TB1&TB2) equipped with electronic portal imaging devices (EPID) were employed in this study. Both machines were calibrated per TG-51 and used clinically since Oct 2014. Daily output measurement for 6/15 MV beams were obtained using SunNuclear DailyQA3 device as part of morning QA. In addition, in-house protocol was implemented for EPID output measurement (10×10 cm fields, 100 MU, 100cm SID, output defined over an ROI of 2×2 cm around central axis). Moreover, the Varian Machine Performance Check (MPC) was used on both machines to measure machine output. The EPID and DailyQA3 based measurements of the relative machine output were compared and cross-correlated with monthly machine output as measured by an A12 Exradin 0.65cc Ion Chamber (IC) serving as ground truth. The results were correlated using Pearson test. Results: The correlations among DailyQA3, in-house EPID and Varian MPC output measurements, with the IC for 6/15 MV were similar for TB1 (0.83–0.95) and TB2 (0.55–0.67). The machine output for the 6/15MV beams on both machines showed a similar trend, namely an increase over time as indicated by all measurements, requiring a machine recalibration after 6 months. This drift is due to a known issue with pressurized monitor chamber which tends to leak over time. MPC failed occasionally but passed when repeated. Conclusion: The results indicate that the use of EPID for daily output measurements has the potential to become a viable and efficient tool for daily routine LINAC QA, thus eliminating weather (T,P) and human setup variability and increasing efficiency of the QA process.

SU-G-TeP2-01: Can EPID Based Measurement Replace Traditional Daily Output QA On Megavoltage Linac?

Energy Technology Data Exchange (ETDEWEB)

Saleh, Z; Tang, X; Song, Y; Obcemea, C; Beeban, N; Chan, M; Li, X; Tang, G; Lim, S; Lovelock, D; LoSasso, T; Mechalakos, J; Both, S [Memorial Sloan-Kettering Cancer Center, NY (United States)

2016-06-15

Purpose: To investigate the long term stability and viability of using EPID-based daily output QA via in-house and vendor driven protocol, to replace conventional QA tools and improve QA efficiency. Methods: Two Varian TrueBeam machines (TB1&TB2) equipped with electronic portal imaging devices (EPID) were employed in this study. Both machines were calibrated per TG-51 and used clinically since Oct 2014. Daily output measurement for 6/15 MV beams were obtained using SunNuclear DailyQA3 device as part of morning QA. In addition, in-house protocol was implemented for EPID output measurement (10×10 cm fields, 100 MU, 100cm SID, output defined over an ROI of 2×2 cm around central axis). Moreover, the Varian Machine Performance Check (MPC) was used on both machines to measure machine output. The EPID and DailyQA3 based measurements of the relative machine output were compared and cross-correlated with monthly machine output as measured by an A12 Exradin 0.65cc Ion Chamber (IC) serving as ground truth. The results were correlated using Pearson test. Results: The correlations among DailyQA3, in-house EPID and Varian MPC output measurements, with the IC for 6/15 MV were similar for TB1 (0.83–0.95) and TB2 (0.55–0.67). The machine output for the 6/15MV beams on both machines showed a similar trend, namely an increase over time as indicated by all measurements, requiring a machine recalibration after 6 months. This drift is due to a known issue with pressurized monitor chamber which tends to leak over time. MPC failed occasionally but passed when repeated. Conclusion: The results indicate that the use of EPID for daily output measurements has the potential to become a viable and efficient tool for daily routine LINAC QA, thus eliminating weather (T,P) and human setup variability and increasing efficiency of the QA process.

Genotipificación de HLA-B en pacientes colombianos afectados por el síndrome Stevens-Johnson y la Necrólisis Epidérmica Tóxica

OpenAIRE

León Ruiz, Maria Juliana

2014-01-01

Las reacciones alérgicas a medicamentos cutáneas severas (RAM) como el Síndrome Stevens Johnson (SJS) y la Necrólisis Epidérmica Tóxica (NET),caracterizadas por exantema, erosión de la piel y las membranas mucosas, flictenas, desprendimiento de la piel secundario a la muerte de queratinocitos y compromiso ocular. Son infrecuentes en la población pero con elevada morbi-mortalidad, se presentan luego de la administración de diferentes fármacos. En Asia se ha asociado el alelo HLA-B*15:02 como m...

Síndrome de Stevens-Johnson e necrólise epidérmica tóxica

OpenAIRE

Coelho, Inês Dionísio

2013-01-01

Trabalho final de mestrado integrado em Medicina (Dermatologia), apresentado à Faculdade de Medicina da Universidade de Coimbra. A Síndrome de Stevens-Johnson (SSJ) e a necrólise epidérmica tóxica (NET) são reacções mucocutâneas raras consideradas emergências médicas, podendo tornar-se fatais. Constituem dois extremos do mesmo espectro clínico das reacções cutâneas severas adversas a fármacos com necrose epidérmica, diferindo apenas na extensão do descolamento epidérmico. A gra...

21 CFR 573.700 - Sodium nitrite.

Science.gov (United States)

2010-04-01

..., FEEDS, AND RELATED PRODUCTS FOOD ADDITIVES PERMITTED IN FEED AND DRINKING WATER OF ANIMALS Food Additive... as a preservative and color fixative in canned pet food containing fish, meat, and fish and meat... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Sodium nitrite. 573.700 Section 573.700 Food and...

MLC quality assurance using EPID: A fitting technique with subpixel precision

International Nuclear Information System (INIS)

Mamalui-Hunter, Maria; Li, Harold; Low, Daniel A.

2008-01-01

Amorphous silicon based electronic portal imaging devices (EPIDs) have been shown to be a good alternative to radiographic film for routine quality assurance (QA) of multileaf collimator (MLC) positioning accuracy. In this work, we present a method of acquiring an EPID image of a traditional strip-test image using analytical fits of the interleaf and leaf abutment image signatures. After exposure, the EPID image pixel values are divided by an open field image to remove EPID response and radiation field variations. Profiles acquired in the direction orthogonal to the leaf motion exhibit small peaks caused by interleaf leakage. Gaussian profiles are fitted to the interleaf leakage peaks, the results of which are, using multiobjective optimization, used to calculate the image rotational angle with respect to the collimator axis of rotation. The relative angle is used to rotate the image to align the MLC leaf travel to the image pixel axes. The leaf abutments also present peaks that are fitted by heuristic functions, in this case modified Lorentzian functions. The parameters of the Lorentzian functions are used to parameterize the leaf gap width and positions. By imaging a set of MLC fields with varying gaps forming symmetric and asymmetric abutments, calibration curves with regard to relative peak height (RPH) versus nominal gap width are obtained. Based on this calibration data, the individual leaf positions are calculated to compare with the nominal programmed positions. The results demonstrate that the collimator rotation angle can be determined as accurate as 0.01 deg. . A change in MLC gap width of 0.2 mm leads to a change in RPH of about 10%. For asymmetrically produced gaps, a 0.2 mm MLC leaf gap width change causes 0.2 pixel peak position change. Subpixel resolution is obtained by using a parameterized fit of the relatively large abutment peaks. By contrast, for symmetrical gap changes, the peak position remains unchanged with a standard deviation of 0

Verification of respiratory-gated radiotherapy with new real-time tumour-tracking radiotherapy system using cine EPID images and a log file.

Science.gov (United States)

Shiinoki, Takehiro; Hanazawa, Hideki; Yuasa, Yuki; Fujimoto, Koya; Uehara, Takuya; Shibuya, Keiko

2017-02-21

A combined system comprising the TrueBeam linear accelerator and a new real-time tumour-tracking radiotherapy system, SyncTraX, was installed at our institution. The objectives of this study are to develop a method for the verification of respiratory-gated radiotherapy with SyncTraX using cine electronic portal image device (EPID) images and a log file and to verify this treatment in clinical cases. Respiratory-gated radiotherapy was performed using TrueBeam and the SyncTraX system. Cine EPID images and a log file were acquired for a phantom and three patients during the course of the treatment. Digitally reconstructed radiographs (DRRs) were created for each treatment beam using a planning CT set. The cine EPID images, log file, and DRRs were analysed using a developed software. For the phantom case, the accuracy of the proposed method was evaluated to verify the respiratory-gated radiotherapy. For the clinical cases, the intra- and inter-fractional variations of the fiducial marker used as an internal surrogate were calculated to evaluate the gating accuracy and set-up uncertainty in the superior-inferior (SI), anterior-posterior (AP), and left-right (LR) directions. The proposed method achieved high accuracy for the phantom verification. For the clinical cases, the intra- and inter-fractional variations of the fiducial marker were  ⩽3 mm and  ±3 mm in the SI, AP, and LR directions. We proposed a method for the verification of respiratory-gated radiotherapy with SyncTraX using cine EPID images and a log file and showed that this treatment is performed with high accuracy in clinical cases.

SU-G-BRB-10: New Generation of High Frame-Rate and High Spatial-Resolution EPID QA System for Full-Body MLC-Based Robotic Radiosurgery

International Nuclear Information System (INIS)

Han, B; Xing, L; Wang, L

2016-01-01

Purpose: To systematically investigate an ultra-high spatial-resolution amorphous silicon flat-panel electronic portal imaging device (EPID) for MLC-based full-body robotic radiosurgery geometric and dosimetric quality assurance (QA). Methods: The high frame-rate and ultra-high spatial resolution EPID is an outstanding detector for measuring profiles, MLC-shaped radiosurgery field aperture verification, and small field dosimetry. A Monte Carlo based technique with a robotic linac specific response and calibration is developed to convert a raw EPID-measured image of a radiosurgery field into water-based dose distribution. The technique is applied to measure output factors and profiles for 6MV MLC-defined radiosurgery fields with various sizes ranging from 7.6mm×7.7mm to 100mm×100.1mm and the results are compared with the radiosurgery diode scan measurements in water tank. The EPID measured field sizes and the penumbra regions are analyzed to evaluate the MLC positioning accuracy. Results: For all MLC fields, the EPID measured output factors of MLC-shaped fields are in good agreement with the diode measurements. The mean output difference between the EPID and diode measurement is 0.05±0.87%. The max difference is −1.33% for 7.6mm×7.7mm field. The MLC field size derived from the EPID measurements are in good agreement comparing to the diode scan result. For crossline field sizes, the mean difference is −0.17mm±0.14mm with a maximum of −0.35mm for the 30.8mm×30.8mm field. For inline field sizes, the mean difference is +0.08mm±0.18mm with a maximum of +0.45mm for the 100mm×100.1mm field. The high resolution EPID is able to measure the whole radiation field, without the need to align the detector center perfectly at field center as diode or ion chamber measurement. The setup time is greatly reduced so that the whole process is possible for machine and patient-specific QA. Conclusion: The high spatial-resolution EPID is proved to be an accurate and efficient

A novel method for sub-arc VMAT dose delivery verification based on portal dosimetry with an EPID.

Science.gov (United States)

Cools, Ruud A M; Dirkx, Maarten L P; Heijmen, Ben J M

2017-11-01

The EPID-based sub-arc verification of VMAT dose delivery requires synchronization of the acquired electronic portal images (EPIs) with the VMAT delivery, that is, establishment of the start- and stop-MU of the acquired images. To realize this, published synchronization methods propose the use of logging features of the linac or dedicated hardware solutions. In this study, we developed a novel, software-based synchronization method that only uses information inherently available in the acquired images. The EPIs are continuously acquired during pretreatment VMAT delivery and converted into Portal Dose Images (PDIs). Sub-arcs of approximately 10 MU are then defined by combining groups of sequentially acquired PDIs. The start- and stop-MUs of measured sub-arcs are established in a synchronization procedure, using only dosimetric information in measured and predicted PDIs. Sub-arc verification of a VMAT dose delivery is based on comparison of measured sub-arc PDIs with synchronized, predicted sub-arc PDIs, using γ-analyses. To assess the accuracy of this new method, measured and predicted PDIs were compared for 20 clinically applied VMAT prostate cancer plans. The sensitivity of the method for detection of delivery errors was investigated using VMAT deliveries with intentionally inserted, small perturbations (25 error scenarios; leaf gap deviations ≤ 1.5 mm, leaf motion stops during ≤ 15 MU, linac output error ≤ 2%). For the 20 plans, the average failed pixel rates (FPR) for full-arc and sub-arc dose QA were 0.36% ± 0.26% (1 SD) and 0.64% ± 0.88%, based on 2%/2 mm and 3%/3 mm γ-analyses, respectively. Small systematic perturbations of up to 1% output error and 1 mm leaf offset were detected using full-arc QA. Sub-arc QA was able to detect positioning errors in three leaves only during approximately 20 MU and small dose delivery errors during approximately 40 MU. In an ROC analysis, the area under the curve (AUC) for the combined full-arc/sub-arc approach was

21 CFR 573.660 - Methyl glucoside-coconut oil ester.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Methyl glucoside-coconut oil ester. 573.660 Section 573.660 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... ANIMALS Food Additive Listing § 573.660 Methyl glucoside-coconut oil ester. Methyl glucoside-coconut oil...

Preliminary studies for implementation of a MCL quality control using EPID (Portal Dosimetry); Estudos preliminares para implementacao de um controle de qualidade de MLC com o uso do EPID (Portal Dosimetry)

Energy Technology Data Exchange (ETDEWEB)

Mattos, Fabio R.; Furnari, Laura [Universidade de Sao Paulo (USP), Sao Paulo, SP (Brazil). Faculdade de Medicina

2016-07-01

A Quality Control (CQ) to ensure the expected performance of a Multileaf Collimator System (MLC) is essential for delivering dose in a safety and appropriate way. The time required for equipment control and dosimetry may be lowered when the Electronic Portal Image Device (EPID) is used. The aim of this paper was to check the resolution limits of the detection system for IMRT mode, and to do the analysis of three tests of MLC performance: Picket Fence, Slinding GAP, MLC versus Gantry. A Varian iX Clinac equipped with an 80 leaf Millennium MLC and with amorphous silicon based EPID (aS1000) was use. The EPID proved Effective, where errors up to 0,5 mm can be detected. Information about interleaf transmissions, dose profile and gravity influence in the leaf banks also were included. (author)

21 CFR 573.620 - Menadione dimethylpyrimidinol bisulfite.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Menadione dimethylpyrimidinol bisulfite. 573.620... ANIMALS Food Additive Listing § 573.620 Menadione dimethylpyrimidinol bisulfite. The food additive, menadione dimethylpyrimidinol bisulfite, may be safely used in accordance with the following conditions: (a...

Preliminary X-ray crystallographic analysis of SMU.573, a putative sugar kinase from Streptococcus mutans

Energy Technology Data Exchange (ETDEWEB)

Zhou, Yan-Feng; Li, Lan-Fen [National Laboratory of Protein Engineering and Plant Genetic Engineering, College of Life Sciences, Peking University, Beijing 100871 (China); Yang, Cheng [National Laboratory of Protein Engineering and Plant Genetic Engineering, College of Life Sciences, Peking University, Beijing 100871 (China); Rigaku/MSC Inc., 9009 New Trails Drive, The Woodlands, TX 77381 (United States); Liang, Yu-He, E-mail: liangyh@pku.edu.cn [National Laboratory of Protein Engineering and Plant Genetic Engineering, College of Life Sciences, Peking University, Beijing 100871 (China); Su, Xiao-Dong, E-mail: liangyh@pku.edu.cn [National Laboratory of Protein Engineering and Plant Genetic Engineering, College of Life Sciences, Peking University, Beijing 100871 (China); Shenzhen Graduate School of Peking University, Shenzhen 518055 (China)

2008-01-01

SMU.573 from S. mutans was expressed in E. coli and crystallized. The crystals belong to space group I4 and 2.5 Å resolution diffraction data were collected at an in-house chromium radiation source. SMU.573 from Streptococcus mutans is a structurally and functionally uncharacterized protein that was selected for structural biology studies. Native and SeMet-labelled proteins were expressed with an N-His tag in Escherichia coli BL21 (DE3) and purified by Ni{sup 2+}-chelating and size-exclusion chromatography. Crystals of the SeMet-labelled protein were obtained by the hanging-drop vapour-diffusion method and a 2.5 Å resolution diffraction data set was collected using an in-house chromium radiation source. The crystals belong to space group I4, with unit-cell parameters a = b = 96.53, c = 56.26 Å, α = β = γ = 90°.

Preliminary X-ray crystallographic analysis of SMU.573, a putative sugar kinase from Streptococcus mutans

International Nuclear Information System (INIS)

Zhou, Yan-Feng; Li, Lan-Fen; Yang, Cheng; Liang, Yu-He; Su, Xiao-Dong

2007-01-01

SMU.573 from S. mutans was expressed in E. coli and crystallized. The crystals belong to space group I4 and 2.5 Å resolution diffraction data were collected at an in-house chromium radiation source. SMU.573 from Streptococcus mutans is a structurally and functionally uncharacterized protein that was selected for structural biology studies. Native and SeMet-labelled proteins were expressed with an N-His tag in Escherichia coli BL21 (DE3) and purified by Ni 2+ -chelating and size-exclusion chromatography. Crystals of the SeMet-labelled protein were obtained by the hanging-drop vapour-diffusion method and a 2.5 Å resolution diffraction data set was collected using an in-house chromium radiation source. The crystals belong to space group I4, with unit-cell parameters a = b = 96.53, c = 56.26 Å, α = β = γ = 90°

21 CFR 573.914 - Salts of volatile fatty acids.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Salts of volatile fatty acids. 573.914 Section 573... Food Additive Listing § 573.914 Salts of volatile fatty acids. (a) Identity. The food additive is a... contains ammonium or calcium salts of volatile fatty acids and shall conform to the following...

Necrolisis epidérmica tóxica: un paradigma de enfermedad crítica

Directory of Open Access Journals (Sweden)

Alfonso Estrella-Alonso

Full Text Available RESUMEN La necrolisis epidérmica tóxica es una reacción cutánea adversa de tipo inmunológico secundaria en la mayor parte de los casos a la administración de un fármaco. La necrolisis epidérmica tóxica, el síndrome de Steven Johnson y el eritema exudativo multiforme forman parte del mismo espectro de enfermedad. La mortalidad de la necrolisis epidérmica tóxica es alrededor del 30%. La fisiopatología de la necrolisis epidérmica tóxica es semejante en muchos aspectos a la de las quemaduras dérmicas superficiales. La afectación mucosa del epitelio ocular y genital se asocia con secuelas graves si no se trata de forma temprana. Se acepta en general que los pacientes con necrolisis epidérmica tóxica son tratados mejor en unidades de grandes quemados, donde existe experiencia en el manejo de enfermos con pérdida cutánea extensa. El tratamiento es de soporte, eliminación y cobertura con derivados biosintéticos de la piel de las zonas afectadas, tratamiento de la afectación mucosa, y tratamiento inmunosupresor específico. De los tratamientos ensayados sólo se usa actualmente en la mayor parte de los centros la inmunoglobulina G y la ciclosporina A, aun cuando no existe evidencia sólida para recomendar ningún tratamiento específico. Entre los aspectos particulares del tratamiento de esta enfermedad se encuentra la prevención de secuelas relacionadas con la formación de sinequias, los cuidados oculares para prevenir secuelas graves que pueden conducir a la ceguera, y el tratamiento específico inmunosupresor. Un mejor conocimiento de los principios del manejo de la necrolisis epidérmica tóxica llevará a un mejor manejo de la enfermedad, a una mayor supervivencia y una menor prevalencia de las secuelas.

Dosimetric pre-treatment verification of IMRT using an EPID; clinical experience

International Nuclear Information System (INIS)

Zijtveld, Mathilda van; Dirkx, Maarten L.P.; Boer, Hans C.J. de; Heijmen, Ben J.M.

2006-01-01

Background and purpose: In our clinic a QA program for IMRT verification, fully based on dosimetric measurements with electronic portal imaging devices (EPID), has been running for over 3 years. The program includes a pre-treatment dosimetric check of all IMRT fields. During a complete treatment simulation at the linac, a portal dose image (PDI) is acquired with the EPID for each patient field and compared with a predicted PDI. In this paper, the results of this pre-treatment procedure are analysed, and intercepted errors are reported. An automated image analysis procedure is proposed to limit the number of fields that need human intervention in PDI comparison. Materials and methods: Most of our analyses are performed using the γ index with 3% local dose difference and 3 mm distance to agreement as reference values. Scalar parameters are derived from the γ values to summarize the agreement between measured and predicted 2D PDIs. Areas with all pixels having γ values larger than one are evaluated, making decisions based on clinically relevant criteria more straightforward. Results: In 270 patients, the pre-treatment checks revealed four clinically relevant errors. Calculation of statistics for a group of 75 patients showed that the patient-averaged mean γ value inside the field was 0.43 ± 0.13 (1 SD) and only 6.1 ± 6.8% of pixels had a γ value larger than one. With the proposed automated image analysis scheme, visual inspection of images can be avoided in 2/3 of the cases. Conclusion: EPIDs may be used for high accuracy and high resolution routine verification of IMRT fields to intercept clinically relevant dosimetric errors prior to the start of treatment. For the majority of fields, PDI comparison can fully rely on an automated procedure, avoiding excessive workload

Comparison of forward- and back-projection in vivo EPID dosimetry for VMAT treatment of the prostate

Science.gov (United States)

Bedford, James L.; Hanson, Ian M.; Hansen, Vibeke N.

2018-01-01

In the forward-projection method of portal dosimetry for volumetric modulated arc therapy (VMAT), the integrated signal at the electronic portal imaging device (EPID) is predicted at the time of treatment planning, against which the measured integrated image is compared. In the back-projection method, the measured signal at each gantry angle is back-projected through the patient CT scan to give a measure of total dose to the patient. This study aims to investigate the practical agreement between the two types of EPID dosimetry for prostate radiotherapy. The AutoBeam treatment planning system produced VMAT plans together with corresponding predicted portal images, and a total of 46 sets of gantry-resolved portal images were acquired in 13 patients using an iViewGT portal imager. For the forward-projection method, each acquisition of gantry-resolved images was combined into a single integrated image and compared with the predicted image. For the back-projection method, iViewDose was used to calculate the dose distribution in the patient for comparison with the planned dose. A gamma index for 3% and 3 mm was used for both methods. The results were investigated by delivering the same plans to a phantom and repeating some of the deliveries with deliberately introduced errors. The strongest agreement between forward- and back-projection methods is seen in the isocentric intensity/dose difference, with moderate agreement in the mean gamma. The strongest correlation is observed within a given patient, with less correlation between patients, the latter representing the accuracy of prediction of the two methods. The error study shows that each of the two methods has its own distinct sensitivity to errors, but that overall the response is similar. The forward- and back-projection EPID dosimetry methods show moderate agreement in this series of prostate VMAT patients, indicating that both methods can contribute to the verification of dose delivered to the patient.

SU-F-T-486: A Simple Approach to Performing Light Versus Radiation Field Coincidence Quality Assurance Using An Electronic Portal Imaging Device (EPID)

Energy Technology Data Exchange (ETDEWEB)

Herchko, S; Ding, G [Vanderbilt University, Nashville, TN (United States)

2016-06-15

Purpose: To develop an accurate, straightforward, and user-independent method for performing light versus radiation field coincidence quality assurance utilizing EPID images, a simple phantom made of readily-accessible materials, and a free software program. Methods: A simple phantom consisting of a blocking tray, graph paper, and high-density wire was constructed. The phantom was used to accurately set the size of a desired light field and imaged on the electronic portal imaging device (EPID). A macro written for use in ImageJ, a free image processing software, was then use to determine the radiation field size utilizing the high density wires on the phantom for a pixel to distance calibration. The macro also performs an analysis on the measured radiation field utilizing the tolerances recommended in the AAPM Task Group #142. To verify the accuracy of this method, radiochromic film was used to qualitatively demonstrate agreement between the film and EPID results, and an additional ImageJ macro was used to quantitatively compare the radiation field sizes measured both with the EPID and film images. Results: The results of this technique were benchmarked against film measurements, which have been the gold standard for testing light versus radiation field coincidence. The agreement between this method and film measurements were within 0.5 mm. Conclusion: Due to the operator dependency associated with tracing light fields and measuring radiation fields by hand when using film, this method allows for a more accurate comparison between the light and radiation fields with minimal operator dependency. Removing the need for radiographic or radiochromic film also eliminates a reoccurring cost and increases procedural efficiency.

SU-F-T-486: A Simple Approach to Performing Light Versus Radiation Field Coincidence Quality Assurance Using An Electronic Portal Imaging Device (EPID)

International Nuclear Information System (INIS)

Herchko, S; Ding, G

2016-01-01

Purpose: To develop an accurate, straightforward, and user-independent method for performing light versus radiation field coincidence quality assurance utilizing EPID images, a simple phantom made of readily-accessible materials, and a free software program. Methods: A simple phantom consisting of a blocking tray, graph paper, and high-density wire was constructed. The phantom was used to accurately set the size of a desired light field and imaged on the electronic portal imaging device (EPID). A macro written for use in ImageJ, a free image processing software, was then use to determine the radiation field size utilizing the high density wires on the phantom for a pixel to distance calibration. The macro also performs an analysis on the measured radiation field utilizing the tolerances recommended in the AAPM Task Group #142. To verify the accuracy of this method, radiochromic film was used to qualitatively demonstrate agreement between the film and EPID results, and an additional ImageJ macro was used to quantitatively compare the radiation field sizes measured both with the EPID and film images. Results: The results of this technique were benchmarked against film measurements, which have been the gold standard for testing light versus radiation field coincidence. The agreement between this method and film measurements were within 0.5 mm. Conclusion: Due to the operator dependency associated with tracing light fields and measuring radiation fields by hand when using film, this method allows for a more accurate comparison between the light and radiation fields with minimal operator dependency. Removing the need for radiographic or radiochromic film also eliminates a reoccurring cost and increases procedural efficiency.

21 CFR 573.880 - Normal propyl alcohol.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Normal propyl alcohol. 573.880 Section 573.880 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS FOOD ADDITIVES PERMITTED IN FEED AND DRINKING WATER OF ANIMALS Food...

Verification of respiratory-gated radiotherapy with new real-time tumour-tracking radiotherapy system using cine EPID images and a log file

Science.gov (United States)

Shiinoki, Takehiro; Hanazawa, Hideki; Yuasa, Yuki; Fujimoto, Koya; Uehara, Takuya; Shibuya, Keiko

2017-02-01

A combined system comprising the TrueBeam linear accelerator and a new real-time tumour-tracking radiotherapy system, SyncTraX, was installed at our institution. The objectives of this study are to develop a method for the verification of respiratory-gated radiotherapy with SyncTraX using cine electronic portal image device (EPID) images and a log file and to verify this treatment in clinical cases. Respiratory-gated radiotherapy was performed using TrueBeam and the SyncTraX system. Cine EPID images and a log file were acquired for a phantom and three patients during the course of the treatment. Digitally reconstructed radiographs (DRRs) were created for each treatment beam using a planning CT set. The cine EPID images, log file, and DRRs were analysed using a developed software. For the phantom case, the accuracy of the proposed method was evaluated to verify the respiratory-gated radiotherapy. For the clinical cases, the intra- and inter-fractional variations of the fiducial marker used as an internal surrogate were calculated to evaluate the gating accuracy and set-up uncertainty in the superior-inferior (SI), anterior-posterior (AP), and left-right (LR) directions. The proposed method achieved high accuracy for the phantom verification. For the clinical cases, the intra- and inter-fractional variations of the fiducial marker were  ⩽3 mm and  ±3 mm in the SI, AP, and LR directions. We proposed a method for the verification of respiratory-gated radiotherapy with SyncTraX using cine EPID images and a log file and showed that this treatment is performed with high accuracy in clinical cases. This work was partly presented at the 58th Annual meeting of American Association of Physicists in Medicine.

21 CFR 573.870 - Poly(2-vinylpyridine-co-styrene).

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2010-04-01

... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Poly(2-vinylpyridine-co-styrene). 573.870 Section 573.870 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS FOOD ADDITIVES PERMITTED IN FEED AND DRINKING WATER OF ANIMALS Food Additive Listing § 573.870 Poly(2...

Frame average optimization of cine-mode EPID images used for routine clinical in vivo patient dose verification of VMAT deliveries

Energy Technology Data Exchange (ETDEWEB)

McCowan, P. M., E-mail: pmccowan@cancercare.mb.ca [Department of Physics and Astronomy, University of Manitoba, Winnipeg, Manitoba R3T 2N2, Canada and Medical Physics Department, CancerCare Manitoba, 675 McDermot Avenue, Winnipeg, Manitoba R3E 0V9 (Canada); McCurdy, B. M. C. [Department of Physics and Astronomy, University of Manitoba, Winnipeg, Manitoba R3T 2N2 (Canada); Medical Physics Department, CancerCare Manitoba, 675 McDermot Avenue, Winnipeg, Manitoba R3E 0V9 (Canada); Department of Radiology, University of Manitoba, 820 Sherbrook Street, Winnipeg, Manitoba R3A 1R9 (Canada)

2016-01-15

Purpose: The in vivo 3D dose delivered to a patient during volumetric modulated arc therapy (VMAT) delivery can be calculated using electronic portal imaging device (EPID) images. These images must be acquired in cine-mode (i.e., “movie” mode) in order to capture the time-dependent delivery information. The angle subtended by each cine-mode EPID image during an arc can be changed via the frame averaging number selected within the image acquisition software. A large frame average number will decrease the EPID’s angular resolution and will result in a decrease in the accuracy of the dose information contained within each image. Alternatively, less EPID images acquired per delivery will decrease the overall 3D patient dose calculation time, which is appealing for large-scale clinical implementation. Therefore, the purpose of this study was to determine the optimal frame average value per EPID image, defined as the highest frame averaging that can be used without an appreciable loss in 3D dose reconstruction accuracy for VMAT treatments. Methods: Six different VMAT plans and six different SBRT-VMAT plans were delivered to an anthropomorphic phantom. Delivery was carried out on a Varian 2300ix model linear accelerator (Linac) equipped with an aS1000 EPID running at a frame acquisition rate of 7.5 Hz. An additional PC was set up at the Linac console area, equipped with specialized frame-grabber hardware and software packages allowing continuous acquisition of all EPID frames during delivery. Frames were averaged into “frame-averaged” EPID images using MATLAB. Each frame-averaged data set was used to calculate the in vivo dose to the patient and then compared to the single EPID frame in vivo dose calculation (the single frame calculation represents the highest possible angular resolution per EPID image). A mean percentage dose difference of low dose (<20% prescription dose) and high dose regions (>80% prescription dose) was calculated for each frame averaged

Frame average optimization of cine-mode EPID images used for routine clinical in vivo patient dose verification of VMAT deliveries

International Nuclear Information System (INIS)

McCowan, P. M.; McCurdy, B. M. C.

2016-01-01

Purpose: The in vivo 3D dose delivered to a patient during volumetric modulated arc therapy (VMAT) delivery can be calculated using electronic portal imaging device (EPID) images. These images must be acquired in cine-mode (i.e., “movie” mode) in order to capture the time-dependent delivery information. The angle subtended by each cine-mode EPID image during an arc can be changed via the frame averaging number selected within the image acquisition software. A large frame average number will decrease the EPID’s angular resolution and will result in a decrease in the accuracy of the dose information contained within each image. Alternatively, less EPID images acquired per delivery will decrease the overall 3D patient dose calculation time, which is appealing for large-scale clinical implementation. Therefore, the purpose of this study was to determine the optimal frame average value per EPID image, defined as the highest frame averaging that can be used without an appreciable loss in 3D dose reconstruction accuracy for VMAT treatments. Methods: Six different VMAT plans and six different SBRT-VMAT plans were delivered to an anthropomorphic phantom. Delivery was carried out on a Varian 2300ix model linear accelerator (Linac) equipped with an aS1000 EPID running at a frame acquisition rate of 7.5 Hz. An additional PC was set up at the Linac console area, equipped with specialized frame-grabber hardware and software packages allowing continuous acquisition of all EPID frames during delivery. Frames were averaged into “frame-averaged” EPID images using MATLAB. Each frame-averaged data set was used to calculate the in vivo dose to the patient and then compared to the single EPID frame in vivo dose calculation (the single frame calculation represents the highest possible angular resolution per EPID image). A mean percentage dose difference of low dose ( 80% prescription dose) was calculated for each frame averaged scenario for each plan. The authors defined their

SU-F-SPS-06: Implementation of a Back-Projection Algorithm for 2D in Vivo Dosimetry with An EPID System

Energy Technology Data Exchange (ETDEWEB)

Hernandez Reyes, B; Rodriguez Perez, E; Sosa Aquino, M [Universidad de Guanajuato, Leon, Guanajuato (Mexico)

2016-06-15

Purpose: To implement a back-projection algorithm for 2D dose reconstructions for in vivo dosimetry in radiation therapy using an Electronic Portal Imaging Device (EPID) based on amorphous silicon. Methods: An EPID system was used to calculate dose-response function, pixel sensitivity map, exponential scatter kernels and beam hardenig correction for the back-projection algorithm. All measurements were done with a 6 MV beam. A 2D dose reconstruction for an irradiated water phantom (30×30×30 cm{sup 3}) was done to verify the algorithm implementation. Gamma index evaluation between the 2D reconstructed dose and the calculated with a treatment planning system (TPS) was done. Results: A linear fit was found for the dose-response function. The pixel sensitivity map has a radial symmetry and was calculated with a profile of the pixel sensitivity variation. The parameters for the scatter kernels were determined only for a 6 MV beam. The primary dose was estimated applying the scatter kernel within EPID and scatter kernel within the patient. The beam hardening coefficient is σBH= 3.788×10{sup −4} cm{sup 2} and the effective linear attenuation coefficient is µAC= 0.06084 cm{sup −1}. The 95% of points evaluated had γ values not longer than the unity, with gamma criteria of ΔD = 3% and Δd = 3 mm, and within the 50% isodose surface. Conclusion: The use of EPID systems proved to be a fast tool for in vivo dosimetry, but the implementation is more complex that the elaborated for pre-treatment dose verification, therefore, a simplest method must be investigated. The accuracy of this method should be improved modifying the algorithm in order to compare lower isodose curves.

Dicty_cDB: SHD573 [Dicty_cDB

Lifescience Database Archive (English)

Full Text Available SH (Link to library) SHD573 (Link to dictyBase) - - - Contig-U11503-1 SHD573E (Link...Clone ID SHD573 (Link to dictyBase) Atlas ID - NBRP ID - dictyBase ID - Link to Contig Contig-U11503-1 Original site URL http://dict...LFAIFLKIVFVVSAPLCPNSTILLNYNILTVYNSSEGCGFNN EPICTSLKDAVSRAFLLISNNSRVCIGIIGNINVTSEQITLGNYCGALWITSENINNENN NYTI...ststtts ax***d*eyyhcysyfgldl Frame C: fsl*iy*YMIRKSNNFSILFAIFLKIVFVVSAPLCPNSTILLNYNILTVYNSSEGCGFNN EPICTSLKD...vegicus clone CH230-428C17, WORKING DRAFT SEQUENCE, 3 unordered pieces. 48 3e-12 3 AC116984 |AC116984.2 Dict

Development and implementation of EPID-based quality assurance tests for the small animal radiation research platform (SARRP).

Science.gov (United States)

Anvari, Akbar; Poirier, Yannick; Sawant, Amit

2018-04-28

Although small animal image-guided radiotherapy (SA-IGRT) systems are used increasingly in preclinical research, tools for performing routine quality assurance (QA) have not been optimized and are not readily available. Robust, efficient, and reliable QA tools are needed to ensure the accuracy and reproducibility of SA-IGRT systems. Several investigators have reported custom-made phantoms and protocols for SA-IGRT systems QA. These are typically time and resource intensive and are therefore not well suited to the preclinical radiotherapy environment, in which physics support is limited and routine QA is performed by technical staff. We investigated the use of the inbuilt electronic portal imaging device (EPID) to develop and validate routine QA tests and procedures. In this work, we focus on the Xstrahl Small Animal Radiation Research Platform (SARRP) EPID. However, the methodology and tests developed here are applicable to any SA-IGRT system that incorporates an EPID. We performed a comprehensive characterization of the dosimetric properties of the camera-based EPID at kilovoltage energies over a 11-month period, including detector warm-up time, radiation dose history effect, stability and short- and long-term reproducibility, gantry angle dependency, output factor, and linearity of the EPID response. We developed a test to measure the constancy of beam quality in terms of half-value layer and tube peak potential using the EPID. We verified the SARRP daily output and beam profile constancy using the imager. We investigated the use of the imager to monitor beam-targeting accuracy at various gantry and couch angles. The EPID response was stable and reproducible, exhibiting maximum variations of ≤0.3% and ≤1.9% for short and long terms, respectively. The detector showed no dependence on response at different gantry angles, with a maximum variation ≤0.5%. We found close agreement in output factor measurement between the portal imager and reference dosimeters

Feasibility study on the verification of actual beam delivery in a treatment room using EPID transit dosimetry

International Nuclear Information System (INIS)

Baek, Tae Seong; Chung, Eun Ji; Son, Jaeman; Yoon, Myonggeun

2014-01-01

The aim of this study is to evaluate the ability of transit dosimetry using commercial treatment planning system (TPS) and an electronic portal imaging device (EPID) with simple calibration method to verify the beam delivery based on detection of large errors in treatment room. Twenty four fields of intensity modulated radiotherapy (IMRT) plans were selected from four lung cancer patients and used in the irradiation of an anthropomorphic phantom. The proposed method was evaluated by comparing the calculated dose map from TPS and EPID measurement on the same plane using a gamma index method with a 3% dose and 3 mm distance-to-dose agreement tolerance limit. In a simulation using a homogeneous plastic water phantom, performed to verify the effectiveness of the proposed method, the average passing rate of the transit dose based on gamma index was high enough, averaging 94.2% when there was no error during beam delivery. The passing rate of the transit dose for 24 IMRT fields was lower with the anthropomorphic phantom, averaging 86.8% ± 3.8%, a reduction partially due to the inaccuracy of TPS calculations for inhomogeneity. Compared with the TPS, the absolute value of the transit dose at the beam center differed by −0.38% ± 2.1%. The simulation study indicated that the passing rate of the gamma index was significantly reduced, to less than 40%, when a wrong field was erroneously irradiated to patient in the treatment room. This feasibility study suggested that transit dosimetry based on the calculation with commercial TPS and EPID measurement with simple calibration can provide information about large errors for treatment beam delivery

Quality control program of multi-leaf collimation based EPID for teams with Rapidarc

International Nuclear Information System (INIS)

Pujades Claumarchirant, M. C.; Richart Sancho, J.; Gimeno Olmos, J.; Lliso Valverde, F.; Carmona Mesenguer, V.; Garcia Martinez, M. T.; Palomo Llinares, R.; Ballester Pallares, F.; Perez Calatayud, J.

2013-01-01

The objective of this work is to show a collection of different recommendations on the control of quality of collimation multi-leaf system and present the selection of tests based on the electronic imaging device (EPID) portal that have decided to establish in our Center, where in addition to the requirements of quality assurance generic for collimation multi-leaf system quality control methods have been included for RapidArc. (Author)

Green synthesis in acid water of 5,7,3’,4’-O-tetramethylquercetin

Directory of Open Access Journals (Sweden)

Zhong-lei WANG

2014-04-01

Full Text Available Objective: To synthesize 5,7,3′,4′-O-tetramethylrutin. Methods: With absolute N,N-dimethylformamide as the solvent, rutin and methyl iodide were stirring reaction at room temperature for 48h in the presence of potassium carbonate to obtain 5,7,3′,4′-O-tetramethylrutin, after filtering, rinsing with acetone and concentration under reduced pressure. The concentrate was heated and refluxed for about 1h in 0.50% hydrochloric acid, and then cooled and filtered. The precipitation was washed to neutral with distilled water. Results: The synthesis of 5,7,3′,4′-O-tetramethylquercetin was achieved through the steps above, and it has the same anti-influenza virus effect with oseltamivir, the yield was 92.2%. Conclusion: This method owns the characteristics of high yield, simple process, stable and feasible.

SU-E-T-490: Independent Three-Dimensional (3D) Dose Verification of VMAT/SBRT Using EPID and Cloud Computing

Energy Technology Data Exchange (ETDEWEB)

Ding, A; Han, B; Bush, K; Wang, L; Xing, L [Stanford University School of Medicine, Stanford, CA (United States)

2015-06-15

Purpose: Dosimetric verification of VMAT/SBRT is currently performed on one or two planes in a phantom with either film or array detectors. A robust and easy-to-use 3D dosimetric tool has been sought since the advent of conformal radiation therapy. Here we present such a strategy for independent 3D VMAT/SBRT plan verification system by a combined use of EPID and cloud-based Monte Carlo (MC) dose calculation. Methods: The 3D dosimetric verification proceeds in two steps. First, the plan was delivered with a high resolution portable EPID mounted on the gantry, and the EPID-captured gantry-angle-resolved VMAT/SBRT field images were converted into fluence by using the EPID pixel response function derived from MC simulations. The fluence was resampled and used as the input for an in-house developed Amazon cloud-based MC software to reconstruct the 3D dose distribution. The accuracy of the developed 3D dosimetric tool was assessed using a Delta4 phantom with various field sizes (square, circular, rectangular, and irregular MLC fields) and different patient cases. The method was applied to validate VMAT/SBRT plans using WFF and FFF photon beams (Varian TrueBeam STX). Results: It was found that the proposed method yielded results consistent with the Delta4 measurements. For points on the two detector planes, a good agreement within 1.5% were found for all the testing fields. Patient VMAT/SBRT plan studies revealed similar level of accuracy: an average γ-index passing rate of 99.2± 0.6% (3mm/3%), 97.4± 2.4% (2mm/2%), and 72.6± 8.4 % ( 1mm/1%). Conclusion: A valuable 3D dosimetric verification strategy has been developed for VMAT/SBRT plan validation. The technique provides a viable solution for a number of intractable dosimetry problems, such as small fields and plans with high dose gradient.

SU-E-T-490: Independent Three-Dimensional (3D) Dose Verification of VMAT/SBRT Using EPID and Cloud Computing

International Nuclear Information System (INIS)

Ding, A; Han, B; Bush, K; Wang, L; Xing, L

2015-01-01

Purpose: Dosimetric verification of VMAT/SBRT is currently performed on one or two planes in a phantom with either film or array detectors. A robust and easy-to-use 3D dosimetric tool has been sought since the advent of conformal radiation therapy. Here we present such a strategy for independent 3D VMAT/SBRT plan verification system by a combined use of EPID and cloud-based Monte Carlo (MC) dose calculation. Methods: The 3D dosimetric verification proceeds in two steps. First, the plan was delivered with a high resolution portable EPID mounted on the gantry, and the EPID-captured gantry-angle-resolved VMAT/SBRT field images were converted into fluence by using the EPID pixel response function derived from MC simulations. The fluence was resampled and used as the input for an in-house developed Amazon cloud-based MC software to reconstruct the 3D dose distribution. The accuracy of the developed 3D dosimetric tool was assessed using a Delta4 phantom with various field sizes (square, circular, rectangular, and irregular MLC fields) and different patient cases. The method was applied to validate VMAT/SBRT plans using WFF and FFF photon beams (Varian TrueBeam STX). Results: It was found that the proposed method yielded results consistent with the Delta4 measurements. For points on the two detector planes, a good agreement within 1.5% were found for all the testing fields. Patient VMAT/SBRT plan studies revealed similar level of accuracy: an average γ-index passing rate of 99.2± 0.6% (3mm/3%), 97.4± 2.4% (2mm/2%), and 72.6± 8.4 % ( 1mm/1%). Conclusion: A valuable 3D dosimetric verification strategy has been developed for VMAT/SBRT plan validation. The technique provides a viable solution for a number of intractable dosimetry problems, such as small fields and plans with high dose gradient

TU-C-BRE-10: A Streamlined Approach to EPID Transit Dosimetry

Energy Technology Data Exchange (ETDEWEB)

Morris, B; Fontenot, J [Louisiana State University, Baton Rouge, LA (United States); Mary Bird Perkins Cancer Center, Baton Rouge, LA (United States)

2014-06-15

Purpose: To investigate the feasibility of a simple and efficient transit dosimetry method using the electronic portal imaging device (EPID) for dose delivery error detection and prevention. Methods: In the proposed method, 2D reference transit images are generated for comparison with online images acquired during treatment. Reference transit images are generated by convolving through-air EPID measurements of each field with pixel-specific kernels selected from a library of pre-calculated Monte Carlo pencil kernels of varying radiological thickness. The kernel used for each pixel is selected based on the calculated radiological thickness of the patient along a line joining the pixel and the virtual source. The accuracy of the technique was evaluated in flat homogeneous and heterogeneous plastic water phantoms, a heterogeneous cylindrical phantom, and an anthropomorphic head phantom. Gamma criteria of 3%/3 mm was used to quantify the accuracy of the technique for the various cases. Results: An average of 99.9% and 99.7% of the points in the comparison between the measured and predicted images passed a 3%/3mm gamma for the homogeneous and heterogeneous plastic water phantoms, respectively. 97.1% of the points passed for the analysis of the heterogeneous cylindrical phantom. For the anthropomorphic head phantom, an average of 97.8% of points passed the 3%/3mm gamma criteria for all field sizes. Failures were observed primarily in areas of drastic thickness or material changes and at the edges of the fields. Conclusion: The data suggest that the proposed transit dosimetry method is a feasible approach to in vivo dose monitoring. Future research efforts could include implementation for more complex fields and sensitivity testing of the method to setup errors and changes in anatomy. Oncology Data Systems provided partial funding support but did not participate in the collection or analysis of data.

21 CFR 573.200 - Condensed animal protein hydrolysate.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Condensed animal protein hydrolysate. 573.200... ANIMALS Food Additive Listing § 573.200 Condensed animal protein hydrolysate. (a) Identity. The condensed animal protein hydrolysate is produced from the meat byproducts scraped from cured (salted) hides taken...

Use of an amorphous silicon EPID for measuring MLC calibration at varying gantry angle

International Nuclear Information System (INIS)

Clarke, M F; Budgell, G J

2008-01-01

Amorphous silicon electronic portal imaging devices (EPIDs) are used to perform routine quality control (QC) checks on the multileaf collimators (MLCs) at this centre. Presently, these checks are performed at gantry angle 0 0 and are considered to be valid for all other angles. Since therapeutic procedures regularly require the delivery of MLC-defined fields to the patient at a wide range of gantry angles, the accuracy of the QC checks at other gantry angles has been investigated. When the gantry is rotated to angles other than 0 0 it was found that the apparent pixel size measured using the EPID varies up to a maximum value of 0.0015 mm per pixel due to a sag in the EPID of up to 9.2 mm. A correction factor was determined using two independent methods at a range of gantry angles between 0 deg. and 360 deg. The EPID was used to measure field sizes (defined by both x-jaws and MLC) at a range of gantry angles and, after this correction had been applied, any residual gravitational sag was studied. It was found that, when fields are defined by the x-jaws and y-back-up jaws, no errors of greater than 0.5 mm were measured and that these errors were no worse when the MLC was used. It was therefore concluded that, provided the correction is applied, measurements of the field size are, in practical terms, unaffected by gantry angle. Experiments were also performed to study how the reproducibility of individual leaves is affected by gantry angle. Measurements of the relative position of each individual leaf (minor offsets) were performed at a range of gantry angles and repeated three times. The position reproducibility was defined by the RMS error in the position of each leaf and this was found to be 0.24 mm and 0.21 mm for the two leaf banks at a gantry angle of 0 0 . When measurements were performed at a range of gantry angles, these reproducibility values remained within 0.09 mm and 0.11 mm. It was therefore concluded that the calibration of the Elekta MLC is stable at

12 CFR 573.11 - Limits on redisclosure and reuse of information.

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2010-01-01

... PRIVACY OF CONSUMER FINANCIAL INFORMATION Limits on Disclosures § 573.11 Limits on redisclosure and reuse... information from a nonaffiliated financial institution under an exception in § 573.14 or 573.15 of this part, your disclosure and use of that information is limited as follows: (i) You may disclose the information...

Verification of the linac isocenter for stereotactic radiosurgery using cine-EPID imaging and arc delivery

International Nuclear Information System (INIS)

Rowshanfarzad, Pejman; Sabet, Mahsheed; O' Connor, Daryl J.; Greer, Peter B.

2011-01-01

Purpose:Verification of the mechanical isocenter position is required as part of comprehensive quality assurance programs for stereotactic radiosurgery/radiotherapy (SRS/SRT) treatments. Several techniques have been proposed for this purpose but each of them has certain drawbacks. In this paper, a new efficient and more comprehensive method using cine-EPID images has been introduced for automatic verification of the isocenter with sufficient accuracy for stereotactic applications. Methods: Using a circular collimator fixed to the gantry head to define the field, EPID images of a Winston-Lutz phantom were acquired in cine-imaging mode during 360 deg. gantry rotations. A robust matlab code was developed to analyze the data by finding the center of the field and the center of the ball bearing shadow in each image with sub-pixel accuracy. The distance between these two centers was determined for every image. The method was evaluated by comparison to results of a mechanical pointer and also by detection of a manual shift applied to the phantom position. The repeatability and reproducibility of the method were tested and it was also applied to detect couch and collimator wobble during rotation. Results:The accuracy of the algorithm was 0.03 ± 0.02 mm. The repeatability was less than 3 μm and the reproducibility was less than 86 μm. The time elapsed for the analysis of more than 100 cine images of Varian aS1000 and aS500 EPIDs were ∼65 and 20 s, respectively. Processing of images taken in integrated mode took 0.1 s. The output of the analysis software is printable and shows the isocenter shifts as a function of angle in both in-plane and cross-plane directions. It gives warning messages where the shifts exceed the criteria for SRS/SRT and provides useful data for the necessary adjustments in the system including bearing system and/or room lasers. Conclusions: The comprehensive method introduced in this study uses cine-images, is highly accurate, fast, and independent

Verification of the linac isocenter for stereotactic radiosurgery using cine-EPID imaging and arc delivery

Energy Technology Data Exchange (ETDEWEB)

Rowshanfarzad, Pejman; Sabet, Mahsheed; O' Connor, Daryl J.; Greer, Peter B. [School of Mathematical and Physical Sciences, University of Newcastle, Newcastle, New South Wales 2308 (Australia); Department of Radiation Oncology, Calvary Mater Newcastle Hospital, Newcastle, New South Wales 2310, Australia and School of Mathematical and Physical Sciences, University of Newcastle, Newcastle, New South Wales 2308 (Australia)

2011-07-15

Purpose:Verification of the mechanical isocenter position is required as part of comprehensive quality assurance programs for stereotactic radiosurgery/radiotherapy (SRS/SRT) treatments. Several techniques have been proposed for this purpose but each of them has certain drawbacks. In this paper, a new efficient and more comprehensive method using cine-EPID images has been introduced for automatic verification of the isocenter with sufficient accuracy for stereotactic applications. Methods: Using a circular collimator fixed to the gantry head to define the field, EPID images of a Winston-Lutz phantom were acquired in cine-imaging mode during 360 deg. gantry rotations. A robust matlab code was developed to analyze the data by finding the center of the field and the center of the ball bearing shadow in each image with sub-pixel accuracy. The distance between these two centers was determined for every image. The method was evaluated by comparison to results of a mechanical pointer and also by detection of a manual shift applied to the phantom position. The repeatability and reproducibility of the method were tested and it was also applied to detect couch and collimator wobble during rotation. Results:The accuracy of the algorithm was 0.03 {+-} 0.02 mm. The repeatability was less than 3 {mu}m and the reproducibility was less than 86 {mu}m. The time elapsed for the analysis of more than 100 cine images of Varian aS1000 and aS500 EPIDs were {approx}65 and 20 s, respectively. Processing of images taken in integrated mode took 0.1 s. The output of the analysis software is printable and shows the isocenter shifts as a function of angle in both in-plane and cross-plane directions. It gives warning messages where the shifts exceed the criteria for SRS/SRT and provides useful data for the necessary adjustments in the system including bearing system and/or room lasers. Conclusions: The comprehensive method introduced in this study uses cine-images, is highly accurate, fast, and

SU-E-J-61: Monitoring Tumor Motion in Real-Time with EPID Imaging During Cervical Cancer Treatment

International Nuclear Information System (INIS)

Mao, W; Hrycushko, B; Yan, Y; Foster, R; Albuquerque, K

2015-01-01

Purpose: Traditional external beam radiotherapy for cervical cancer requires setup by external skin marks. In order to improve treatment accuracy and reduce planning margin for more conformal therapy, it is essential to monitor tumor positions interfractionally and intrafractionally. We demonstrate feasibility of monitoring cervical tumor motion online using EPID imaging from Beam’s Eye View. Methods: Prior to treatment, 1∼2 cylindrical radio opaque markers were implanted into inferior aspect of cervix tumor. During external beam treatments on a Varian 2100C by 4-field 3D plans, treatment beam images were acquired continuously by an EPID. A Matlab program was developed to locate internal markers on MV images. Based on 2D marker positions obtained from different treatment fields, their 3D positions were estimated for every treatment fraction. Results: There were 398 images acquired during different treatment fractions of three cervical cancer patients. Markers were successfully located on every frame of image at an analysis speed of about 1 second per frame. Intrafraction motions were evaluated by comparing marker positions relative to the position on the first frame of image. The maximum intrafraction motion of the markers was 1.6 mm. Interfraction motions were evaluated by comparing 3D marker positions at different treatment fractions. The maximum interfraction motion was up to 10 mm. Careful comparison found that this is due to patient positioning since the bony structures shifted with the markers. Conclusion: This method provides a cost-free and simple solution for online tumor tracking for cervical cancer treatment since it is feasible to acquire and export EPID images with fast analysis in real time. This method does not need any extra equipment or deliver extra dose to patients. The online tumor motion information will be very useful to reduce planning margins and improve treatment accuracy, which is particularly important for SBRT treatment with long

SU-E-J-61: Monitoring Tumor Motion in Real-Time with EPID Imaging During Cervical Cancer Treatment

Energy Technology Data Exchange (ETDEWEB)

Mao, W; Hrycushko, B; Yan, Y; Foster, R; Albuquerque, K [UT Southwestern Medical Center, Dallas, TX (United States)

2015-06-15

Purpose: Traditional external beam radiotherapy for cervical cancer requires setup by external skin marks. In order to improve treatment accuracy and reduce planning margin for more conformal therapy, it is essential to monitor tumor positions interfractionally and intrafractionally. We demonstrate feasibility of monitoring cervical tumor motion online using EPID imaging from Beam’s Eye View. Methods: Prior to treatment, 1∼2 cylindrical radio opaque markers were implanted into inferior aspect of cervix tumor. During external beam treatments on a Varian 2100C by 4-field 3D plans, treatment beam images were acquired continuously by an EPID. A Matlab program was developed to locate internal markers on MV images. Based on 2D marker positions obtained from different treatment fields, their 3D positions were estimated for every treatment fraction. Results: There were 398 images acquired during different treatment fractions of three cervical cancer patients. Markers were successfully located on every frame of image at an analysis speed of about 1 second per frame. Intrafraction motions were evaluated by comparing marker positions relative to the position on the first frame of image. The maximum intrafraction motion of the markers was 1.6 mm. Interfraction motions were evaluated by comparing 3D marker positions at different treatment fractions. The maximum interfraction motion was up to 10 mm. Careful comparison found that this is due to patient positioning since the bony structures shifted with the markers. Conclusion: This method provides a cost-free and simple solution for online tumor tracking for cervical cancer treatment since it is feasible to acquire and export EPID images with fast analysis in real time. This method does not need any extra equipment or deliver extra dose to patients. The online tumor motion information will be very useful to reduce planning margins and improve treatment accuracy, which is particularly important for SBRT treatment with long

SU-E-T-164: Clinical Implementation of ASi EPID Panels for QA of IMRT/VMAT Plans.

Science.gov (United States)

Hosier, K; Wu, C; Beck, K; Radevic, M; Asche, D; Bareng, J; Kroner, A; Lehmann, J; Logsdon, M; Dutton, S; Rosenthal, S

2012-06-01

To investigate various issues for clinical implementation of aSi EPID panels for IMRT/VMAT QA. Six linacs are used in our clinic for EPID-based plan QA; two Varian Truebeams, two Varian 2100 series, two Elekta Infiniti series. Multiple corrections must be accounted for in the calibration of each panel for dosimetric use. Varian aSi panels are calibrated with standard dark field, flood field, and 40×40 diagonal profile for beam profile correction. Additional corrections to account for off-axis and support arm backscatter are needed for larger field sizes. Since Elekta iViewGT system does not export gantry angle with images, a third-party inclinometer must be physically mounted to back of linac gantry and synchronized with data acquisition via iViewGT PC clock. A T/2 offset correctly correlates image and gantry angle for arc plans due to iView image time stamp at the end of data acquisition for each image. For both Varian and Elekta panels, a 5 MU 10×10 calibration field is used to account for the nonlinear MU to dose response at higher energies. Acquired EPID images are deconvolved via a high pass filter in Fourier space and resultant fluence maps are used to reconstruct a 3D dose 'delivered' to patient using DosimetryCheck. Results are compared to patient 3D dose computed by TPS using a 3D-gamma analysis. 120 IMRT and 100 VMAT cases are reported. Two 3D gamma quantities (Gamma(V10) and Gamma(PTV)) are proposed for evaluating QA results. The Gamma(PTV) is sensitive to MLC offsets while Gamma(V10) is sensitive to gantry rotations. When a 3mm/3% criteria and 90% or higher 3D gamma pass rate is used, all IMRT and 90% of VMAT QA pass QA. After appropriate calibration of aSi panels and setup of image acquisition systems, EPID based 3D dose reconstruction method is found clinically feasible. © 2012 American Association of Physicists in Medicine.

Evaluation of usefulness of portal image using Electronic Portal Imaging Device (EPID) in the patients who received pelvic radiation therapy

International Nuclear Information System (INIS)

Kim, Woo Chul; Kim, Heon Jong; Park, Seong Young; Cho, Young Kap; Loh, John J. K.; Park, Won; Suh, Chang Ok; Kim, Gwi Eon

1998-01-01

To evaluate the usefulness of electronic portal imaging device through objective compare of the images acquired using an EPID and a conventional port film. From Apr. to Oct. 1997, a total of 150 sets of images from 20 patients who received radiation therapy in the pelvis area were evaluated in the Inha University Hospital and Severance Hospital. A dual image recording technique was devised to obtain both electronic portal images and port film images simultaneously with one treatment course. We did not perform double exposure. Five to ten images were acquired from each patient. All images were acquired from posteroanterior (PA) view except images from two patients. A dose rate of 100-300 MU/min and a 10-MV X-ray beam were used and 2-10 MUs were required to produce a verification image during treatment. Kodak diagnostic film with metal/film imaging cassette which was located on the top of the EPID detector was used for the port film. The source to detector distance was 140 cm. Eight anatomical landmarks (pelvic brim, sacrum, acetabulum, iliopectineal line, symphysis, ischium, obturator foramen, sacroiliac joint) were assessed. Four radiation oncologist joined to evaluate each image. The individual landmarks in the port film or in the EPID were rated-very clear (1), clear (2), visible (3), notclear (4), not visible (5). Using an video camera based EPID system, there was no difference of image quality between no enhanced EPID images and port film images. However, when we provided some change with window level for the portal image, the visibility of the sacrum and obturator foramen was improved in the portal images than in the port film images. All anatomical landmarks were more visible in the portal images than in the port film when we applied the CLAHE mode enhancement. The images acquired using an matrix ion chamber type EPID were also improved image quality after window level adjustment. The quality of image acquired using an electronic portal imaging device was

TU-FG-201-06: Remote Dosimetric Auditing for Clinical Trials Using EPID Dosimetry: A Pilot Study

Energy Technology Data Exchange (ETDEWEB)

Miri, N; Legge, K; Greer, P [Newcastle University, Newcastle, NSW (Australia); Lehmann, J [Calvary Mater Newcastle, Newcastle, NSW (Australia); Vial, P [Liverpool Hospital, Sydney, NSW (Australia)

2016-06-15

Purpose: To perform a pilot study for remote dosimetric credentialing of intensity modulated radiation therapy (IMRT) based clinical trials. The study introduces a novel, time efficient and inexpensive dosimetry audit method for multi-center credentialing. The method employs electronic portal imaging device (EPID) to reconstruct delivered dose inside a virtual flat/cylindrical water phantom. Methods: Five centers, including different accelerator types and treatment planning systems (TPS), were asked to download two CT data sets of a Head and Neck (H&N) and Postprostatectomy (P-P) patients to produce benchmark plans. These were then transferred to virtual flat and cylindrical phantom data sets that were also provided. In-air EPID images of the plans were then acquired, and the data sent to the central site for analysis. At the central site, these were converted to DICOM format, all images were used to reconstruct 2D and 3D dose distributions inside respectively the flat and cylindrical phantoms using inhouse EPID to dose conversion software. 2D dose was calculated for individual fields and 3D dose for the combined fields. The results were compared to corresponding TPS doses. Three gamma criteria were used, 3%3mm-3%/2mm–2%/2mm with a 10% dose threshold, to compare the calculated and prescribed dose. Results: All centers had a high pass rate for the criteria of 3%/3 mm. For 2D dose, the average of centers mean pass rate was 99.6% (SD: 0.3%) and 99.8% (SD: 0.3%) for respectively H&N and PP patients. For 3D dose, 3D gamma was used to compare the model dose with TPS combined dose. The mean pass rate was 97.7% (SD: 2.8%) and 98.3% (SD: 1.6%). Conclusion: Successful performance of the method for the pilot centers establishes the method for dosimetric multi-center credentialing. The results are promising and show a high level of gamma agreement and, the procedure is efficient, consistent and inexpensive. Funding has been provided from Department of Radiation Oncology

Commissioning and quality assurance for VMAT delivery systems: An efficient time-resolved system using real-time EPID imaging.

Science.gov (United States)

Zwan, Benjamin J; Barnes, Michael P; Hindmarsh, Jonathan; Lim, Seng B; Lovelock, Dale M; Fuangrod, Todsaporn; O'Connor, Daryl J; Keall, Paul J; Greer, Peter B

2017-08-01

speed exhibited less profile stability. MLC positional accuracy was not observed to be dependent on the degree of interdigitation. MLC speed was measured for each individual leaf and slower leaf speeds were shown to be compensated for by lower dose rates. The test procedures were found to be sensitive to 1 mm systematic MLC errors, 1 mm random MLC errors, 0.4 mm MLC gap errors and synchronization errors between the MLC, dose rate and gantry angle controls systems of 1°. In general, parameters measured by both EPID and log files agreed with the plan, however, a greater average departure from the plan was evidenced by the EPID measurements. QA test plans and analysis methods have been developed to assess the performance of each dynamic component of VMAT deliveries individually and as a function of gantry angle. This methodology relies solely on time-resolved EPID imaging without the presence of a phantom and has been shown to be sensitive to a range of delivery errors. The procedures developed in this work are both comprehensive and time-efficient and can be used for streamlined commissioning and QA of VMAT delivery systems. © 2017 American Association of Physicists in Medicine.

A quantification of the effectiveness of EPID dosimetry and software-based plan verification systems in detecting incidents in radiotherapy

Energy Technology Data Exchange (ETDEWEB)

Bojechko, Casey; Phillps, Mark; Kalet, Alan; Ford, Eric C., E-mail: eford@uw.edu [Department of Radiation Oncology, University of Washington, 1959 N. E. Pacific Street, Seattle, Washington 98195 (United States)

2015-09-15

Purpose: Complex treatments in radiation therapy require robust verification in order to prevent errors that can adversely affect the patient. For this purpose, the authors estimate the effectiveness of detecting errors with a “defense in depth” system composed of electronic portal imaging device (EPID) based dosimetry and a software-based system composed of rules-based and Bayesian network verifications. Methods: The authors analyzed incidents with a high potential severity score, scored as a 3 or 4 on a 4 point scale, recorded in an in-house voluntary incident reporting system, collected from February 2012 to August 2014. The incidents were categorized into different failure modes. The detectability, defined as the number of incidents that are detectable divided total number of incidents, was calculated for each failure mode. Results: In total, 343 incidents were used in this study. Of the incidents 67% were related to photon external beam therapy (EBRT). The majority of the EBRT incidents were related to patient positioning and only a small number of these could be detected by EPID dosimetry when performed prior to treatment (6%). A large fraction could be detected by in vivo dosimetry performed during the first fraction (74%). Rules-based and Bayesian network verifications were found to be complimentary to EPID dosimetry, able to detect errors related to patient prescriptions and documentation, and errors unrelated to photon EBRT. Combining all of the verification steps together, 91% of all EBRT incidents could be detected. Conclusions: This study shows that the defense in depth system is potentially able to detect a large majority of incidents. The most effective EPID-based dosimetry verification is in vivo measurements during the first fraction and is complemented by rules-based and Bayesian network plan checking.

Online 3D EPID-based dose verification: Proof of concept

Energy Technology Data Exchange (ETDEWEB)

Spreeuw, Hanno; Rozendaal, Roel, E-mail: r.rozendaal@nki.nl; Olaciregui-Ruiz, Igor; González, Patrick; Mans, Anton; Mijnheer, Ben [Department of Radiation Oncology, The Netherlands Cancer Institute, Amsterdam 1066 CX (Netherlands); Herk, Marcel van [University of Manchester, Manchester Academic Health Science Centre, The Christie NHS Foundation Trust, Manchester M20 4BX (United Kingdom)

2016-07-15

Purpose: Delivery errors during radiotherapy may lead to medical harm and reduced life expectancy for patients. Such serious incidents can be avoided by performing dose verification online, i.e., while the patient is being irradiated, creating the possibility of halting the linac in case of a large overdosage or underdosage. The offline EPID-based 3D in vivo dosimetry system clinically employed at our institute is in principle suited for online treatment verification, provided the system is able to complete 3D dose reconstruction and verification within 420 ms, the present acquisition time of a single EPID frame. It is the aim of this study to show that our EPID-based dosimetry system can be made fast enough to achieve online 3D in vivo dose verification. Methods: The current dose verification system was sped up in two ways. First, a new software package was developed to perform all computations that are not dependent on portal image acquisition separately, thus removing the need for doing these calculations in real time. Second, the 3D dose reconstruction algorithm was sped up via a new, multithreaded implementation. Dose verification was implemented by comparing planned with reconstructed 3D dose distributions delivered to two regions in a patient: the target volume and the nontarget volume receiving at least 10 cGy. In both volumes, the mean dose is compared, while in the nontarget volume, the near-maximum dose (D2) is compared as well. The real-time dosimetry system was tested by irradiating an anthropomorphic phantom with three VMAT plans: a 6 MV head-and-neck treatment plan, a 10 MV rectum treatment plan, and a 10 MV prostate treatment plan. In all plans, two types of serious delivery errors were introduced. The functionality of automatically halting the linac was also implemented and tested. Results: The precomputation time per treatment was ∼180 s/treatment arc, depending on gantry angle resolution. The complete processing of a single portal frame

Online 3D EPID-based dose verification: Proof of concept

International Nuclear Information System (INIS)

Spreeuw, Hanno; Rozendaal, Roel; Olaciregui-Ruiz, Igor; González, Patrick; Mans, Anton; Mijnheer, Ben; Herk, Marcel van

2016-01-01

Purpose: Delivery errors during radiotherapy may lead to medical harm and reduced life expectancy for patients. Such serious incidents can be avoided by performing dose verification online, i.e., while the patient is being irradiated, creating the possibility of halting the linac in case of a large overdosage or underdosage. The offline EPID-based 3D in vivo dosimetry system clinically employed at our institute is in principle suited for online treatment verification, provided the system is able to complete 3D dose reconstruction and verification within 420 ms, the present acquisition time of a single EPID frame. It is the aim of this study to show that our EPID-based dosimetry system can be made fast enough to achieve online 3D in vivo dose verification. Methods: The current dose verification system was sped up in two ways. First, a new software package was developed to perform all computations that are not dependent on portal image acquisition separately, thus removing the need for doing these calculations in real time. Second, the 3D dose reconstruction algorithm was sped up via a new, multithreaded implementation. Dose verification was implemented by comparing planned with reconstructed 3D dose distributions delivered to two regions in a patient: the target volume and the nontarget volume receiving at least 10 cGy. In both volumes, the mean dose is compared, while in the nontarget volume, the near-maximum dose (D2) is compared as well. The real-time dosimetry system was tested by irradiating an anthropomorphic phantom with three VMAT plans: a 6 MV head-and-neck treatment plan, a 10 MV rectum treatment plan, and a 10 MV prostate treatment plan. In all plans, two types of serious delivery errors were introduced. The functionality of automatically halting the linac was also implemented and tested. Results: The precomputation time per treatment was ∼180 s/treatment arc, depending on gantry angle resolution. The complete processing of a single portal frame

Suitability of markerless EPID tracking for tumor position verification in gated radiotherapy

International Nuclear Information System (INIS)

Serpa, Marco; Baier, Kurt; Guckenberger, Matthias; Cremers, Florian; Meyer, Juergen

2014-01-01

Purpose: To maximize the benefits of respiratory gated radiotherapy (RGRT) of lung tumors real-time verification of the tumor position is required. This work investigates the feasibility of markerless tracking of lung tumors during beam-on time in electronic portal imaging device (EPID) images of the MV therapeutic beam. Methods: EPID movies were acquired at ∼2 fps for seven lung cancer patients with tumor peak-to-peak motion ranges between 7.8 and 17.9 mm (mean: 13.7 mm) undergoing stereotactic body radiotherapy. The external breathing motion of the abdomen was synchronously measured. Both datasets were retrospectively analyzed inPortalTrack, an in-house developed tracking software. The authors define a three-step procedure to run the simulations: (1) gating window definition, (2) gated-beam delivery simulation, and (3) tumor tracking. First, an amplitude threshold level was set on the external signal, defining the onset of beam-on/-off signals. This information was then mapped onto a sequence of EPID images to generate stamps of beam-on/-hold periods throughout the EPID movies in PortalTrack, by obscuring the frames corresponding to beam-off times. Last, tumor motion in the superior-inferior direction was determined on portal images by the tracking algorithm during beam-on time. The residual motion inside the gating window as well as target coverage (TC) and the marginal target displacement (MTD) were used as measures to quantify tumor position variability. Results: Tumor position monitoring and estimation from beam's-eye-view images during RGRT was possible in 67% of the analyzed beams. For a reference gating window of 5 mm, deviations ranging from 2% to 86% (35% on average) were recorded between the reference and measured residual motion. TC (range: 62%–93%; mean: 77%) losses were correlated with false positives incidence rates resulting mostly from intra-/inter-beam baseline drifts, as well as sudden cycle-to-cycle fluctuations in exhale positions. Both

49 CFR 195.573 - What must I do to monitor external corrosion control?

Science.gov (United States)

2010-10-01

... SAFETY TRANSPORTATION OF HAZARDOUS LIQUIDS BY PIPELINE Corrosion Control § 195.573 What must I do to... 49 Transportation 3 2010-10-01 2010-10-01 false What must I do to monitor external corrosion control? 195.573 Section 195.573 Transportation Other Regulations Relating to Transportation (Continued...

21 CFR 573.500 - Condensed, extracted glutamic acid fermentation product.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Condensed, extracted glutamic acid fermentation product. 573.500 Section 573.500 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND... fermentation product. Condensed, extracted glutamic acid fermentation product may be safely used in animal feed...

SU-C-BRD-06: Sensitivity Study of An Automated System to Acquire and Analyze EPID Exit Dose Images

Energy Technology Data Exchange (ETDEWEB)

Olch, A; Zhuang, A [University of Southern California, Los Angeles, CA (United States)

2015-06-15

Purpose: The dosimetric consequences of errors in patient setup or beam delivery and anatomical changes are not readily known. A new product, PerFRACTION (Sun Nuclear Corporation), is designed to detect these errors by comparing the EPID exit dose image from each field of each fraction to those from baseline fraction images. This work investigates the sensitivity of PerFRACTION to detect the deviation of induced errors in a variety of realistic scenarios. Methods: Eight plans were created mimicking potential delivery or setup errors. The plans consisted of a nominal field and the field with an induced error. These were used to irradiate the EPID simulating multiple fractions with and without the error. Integrated EPID images were acquired in clinical mode and saved in ARIA. PerFRACTION automatically pulls the images into its database and performs the user defined comparison. In some cases, images were manually pushed to PerFRACTION. We varied the distance-to-agreement or dose tolerance until PerFRACTION showed failing pixels in the affected region and recorded the values. We induced errors of 1mm and greater in jaw, MLC, and couch position, 2 degree collimation rotation (patient yaw), and 0.5% to 1.5% in machine output. Both static and arc fields with the rails in or out were also acquired and compared. Results: PerFRACTION detected position errors of the jaws, MLC, and couch with an accuracy of better than 0.5 mm, and 0.2 degrees for collimator and gantry error. PerFRACTION detected a machine output error within 0.2% and detected the change in rail position. Conclusion: A new automated system for monitoring daily treatments for machine or patient variations from the first fraction using integrated EPID images was found to be sensitive enough to detect small positional, angular, and dosimetric errors within 0.5mm, 0.2 degrees, and 0.2%, respectively. Sun Nuclear Corporation has provided a software license for the product described.

The impact of cine EPID image acquisition frame rate on markerless soft-tissue tracking

Energy Technology Data Exchange (ETDEWEB)

Yip, Stephen, E-mail: syip@lroc.harvard.edu; Rottmann, Joerg; Berbeco, Ross [Department of Radiation Oncology, Brigham and Women' s Hospital, Dana-Farber Cancer Institute and Harvard Medical School, Boston, Massachusetts 02115 (United States)

2014-06-15

Purpose: Although reduction of the cine electronic portal imaging device (EPID) acquisition frame rate through multiple frame averaging may reduce hardware memory burden and decrease image noise, it can hinder the continuity of soft-tissue motion leading to poor autotracking results. The impact of motion blurring and image noise on the tracking performance was investigated. Methods: Phantom and patient images were acquired at a frame rate of 12.87 Hz with an amorphous silicon portal imager (AS1000, Varian Medical Systems, Palo Alto, CA). The maximum frame rate of 12.87 Hz is imposed by the EPID. Low frame rate images were obtained by continuous frame averaging. A previously validated tracking algorithm was employed for autotracking. The difference between the programmed and autotracked positions of a Las Vegas phantom moving in the superior-inferior direction defined the tracking error (δ). Motion blurring was assessed by measuring the area change of the circle with the greatest depth. Additionally, lung tumors on 1747 frames acquired at 11 field angles from four radiotherapy patients are manually and automatically tracked with varying frame averaging. δ was defined by the position difference of the two tracking methods. Image noise was defined as the standard deviation of the background intensity. Motion blurring and image noise are correlated with δ using Pearson correlation coefficient (R). Results: For both phantom and patient studies, the autotracking errors increased at frame rates lower than 4.29 Hz. Above 4.29 Hz, changes in errors were negligible withδ < 1.60 mm. Motion blurring and image noise were observed to increase and decrease with frame averaging, respectively. Motion blurring and tracking errors were significantly correlated for the phantom (R = 0.94) and patient studies (R = 0.72). Moderate to poor correlation was found between image noise and tracking error with R −0.58 and −0.19 for both studies, respectively. Conclusions: Cine EPID

The impact of cine EPID image acquisition frame rate on markerless soft-tissue tracking

International Nuclear Information System (INIS)

Yip, Stephen; Rottmann, Joerg; Berbeco, Ross

2014-01-01

Purpose: Although reduction of the cine electronic portal imaging device (EPID) acquisition frame rate through multiple frame averaging may reduce hardware memory burden and decrease image noise, it can hinder the continuity of soft-tissue motion leading to poor autotracking results. The impact of motion blurring and image noise on the tracking performance was investigated. Methods: Phantom and patient images were acquired at a frame rate of 12.87 Hz with an amorphous silicon portal imager (AS1000, Varian Medical Systems, Palo Alto, CA). The maximum frame rate of 12.87 Hz is imposed by the EPID. Low frame rate images were obtained by continuous frame averaging. A previously validated tracking algorithm was employed for autotracking. The difference between the programmed and autotracked positions of a Las Vegas phantom moving in the superior-inferior direction defined the tracking error (δ). Motion blurring was assessed by measuring the area change of the circle with the greatest depth. Additionally, lung tumors on 1747 frames acquired at 11 field angles from four radiotherapy patients are manually and automatically tracked with varying frame averaging. δ was defined by the position difference of the two tracking methods. Image noise was defined as the standard deviation of the background intensity. Motion blurring and image noise are correlated with δ using Pearson correlation coefficient (R). Results: For both phantom and patient studies, the autotracking errors increased at frame rates lower than 4.29 Hz. Above 4.29 Hz, changes in errors were negligible withδ < 1.60 mm. Motion blurring and image noise were observed to increase and decrease with frame averaging, respectively. Motion blurring and tracking errors were significantly correlated for the phantom (R = 0.94) and patient studies (R = 0.72). Moderate to poor correlation was found between image noise and tracking error with R −0.58 and −0.19 for both studies, respectively. Conclusions: Cine EPID

47 CFR 1.573 - Processing FM broadcast and translator station applications.

Science.gov (United States)

2010-10-01

... 47 Telecommunication 1 2010-10-01 2010-10-01 false Processing FM broadcast and translator station applications. 1.573 Section 1.573 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL PRACTICE AND... and translator station applications. See § 73.3573. ...

12 CFR 573.4 - Initial privacy notice to consumers required.

Science.gov (United States)

2010-01-01

... customer, not later than when you establish a customer relationship, except as provided in paragraph (e) of... as authorized by §§ 573.14 and 573.15; and (2) You do not have a customer relationship with the consumer. (c) When you establish a customer relationship—(1) General rule. You establish a customer...

Modelos epidémicos con control por vacunación

OpenAIRE

Saralegui Vallejo, Unai

2016-01-01

Existen diferentes tipos de modelos epidémicos no lineales en los que las dinámicas de las sub-poblaciones ( susceptibles, infectados , recobrados , vacunados etc. ) están acopladas. La vacunación puede interpretatrse como un control cuyo objetivo es eliminar la infección. Se estudian estos modelos matemáticamente, para despues comprobar los resultados obtenidos mediante simulaciones.

21 CFR 573.640 - Methyl esters of higher fatty acids.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Methyl esters of higher fatty acids. 573.640... ANIMALS Food Additive Listing § 573.640 Methyl esters of higher fatty acids. The food additive methyl esters of higher fatty acids may be safely used in animal feeds in accordance with the following...

12 CFR 573.16 - Protection of Fair Credit Reporting Act.

Science.gov (United States)

2010-01-01

... CONSUMER FINANCIAL INFORMATION Relation to Other Laws; Effective Date § 573.16 Protection of Fair Credit Reporting Act. Nothing in this part shall be construed to modify, limit, or supersede the operation of the... 12 Banks and Banking 5 2010-01-01 2010-01-01 false Protection of Fair Credit Reporting Act. 573.16...

SU-E-T-133: Assessing IMRT Treatment Delivery Accuracy and Consistency On a Varian TrueBeam Using the SunNuclear PerFraction EPID Dosimetry Software

Energy Technology Data Exchange (ETDEWEB)

Dieterich, S [UC Davis Medical Center, Sacramento, CA (United States); Trestrail, E; Holt, R [Pacific Crest Medical Physics, Chico, CA (United States); Saini, S [Sun Nuclear Corporation, Melbourne, FL (Australia); Pfeiffer, I [VMTH, UC Davis, Davis, CA (United States); Kent, M; Hansen, K [Surgical and Radiological Sciences, UC Davis, Davis, CA (United States)

2015-06-15

Purpose: To assess if the TrueBeam HD120 collimator is delivering small IMRT fields accurately and consistently throughout the course of treatment using the SunNuclear PerFraction software. Methods: 7-field IMRT plans for 8 canine patients who passed IMRT QA using SunNuclear Mapcheck DQA were selected for this study. The animals were setup using CBCT image guidance. The EPID fluence maps were captured for each treatment field and each treatment fraction, with the first fraction EPID data serving as the baseline for comparison. The Sun Nuclear PerFraction Software was used to compare the EPID data for subsequent fractions using a Gamma (3%/3mm) pass rate of 90%. To simulate requirements for SRS, the data was reanalyzed using a Gamma (3%/1mm) pass rate of 90%. Low-dose, low- and high gradient thresholds were used to focus the analysis on clinically relevant parts of the dose distribution. Results: Not all fractions could be analyzed, because during some of the treatment courses the DICOM tags in the EPID images intermittently change from CU to US (unspecified), which would indicate a temporary loss of EPID calibration. This technical issue is still being investigated. For the remaining fractions, the vast majority (7/8 of patients, 95% of fractions, and 96.6% of fields) are passing the less stringent Gamma criteria. The more stringent Gamma criteria caused a drop in pass rate (90 % of fractions, 84% of fields). For the patient with the lowest pass rate, wet towel bolus was used. Another patient with low pass rates experienced masseter muscle wasting. Conclusion: EPID dosimetry using the PerFraction software demonstrated that the majority of fields passed a Gamma (3%/3mm) for IMRT treatments delivered with a TrueBeam HD120 MLC. Pass rates dropped for a DTA of 1mm to model SRS tolerances. PerFraction pass rates can flag missing bolus or internal shields. Sanjeev Saini is an employee of Sun Nuclear Corporation. For this study, a pre-release version of PerFRACTION 1

EPID-based verification of the MLC performance for dynamic IMRT and VMAT

International Nuclear Information System (INIS)

Rowshanfarzad, Pejman; Sabet, Mahsheed; Barnes, Michael P.; O’Connor, Daryl J.; Greer, Peter B.

2012-01-01

Purpose: In advanced radiotherapy treatments such as intensity modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT), verification of the performance of the multileaf collimator (MLC) is an essential part of the linac QA program. The purpose of this study is to use the existing measurement methods for geometric QA of the MLCs and extend them to more comprehensive evaluation techniques, and to develop dedicated robust algorithms to quantitatively investigate the MLC performance in a fast, accurate, and efficient manner. Methods: The behavior of leaves was investigated in the step-and-shoot mode by the analysis of integrated electronic portal imaging device (EPID) images acquired during picket fence tests at fixed gantry angles and arc delivery. The MLC was also studied in dynamic mode by the analysis of cine EPID images of a sliding gap pattern delivered in a variety of conditions including different leaf speeds, deliveries at fixed gantry angles or in arc mode, and changing the direction of leaf motion. The accuracy of the method was tested by detection of the intentionally inserted errors in the delivery patterns. Results: The algorithm developed for the picket fence analysis was able to find each individual leaf position, gap width, and leaf bank skewness in addition to the deviations from expected leaf positions with respect to the beam central axis with sub-pixel accuracy. For the three tested linacs over a period of 5 months, the maximum change in the gap width was 0.5 mm, the maximum deviation from the expected leaf positions was 0.1 mm and the MLC skewness was up to 0.2°. The algorithm developed for the sliding gap analysis could determine the velocity and acceleration/deceleration of each individual leaf as well as the gap width. There was a slight decrease in the accuracy of leaf performance with increasing leaf speeds. The analysis results were presented through several graphs. The accuracy of the method was assessed as 0.01 mm

Application of an EPID for fast daily dosimetric quality control of a fully computer-controlled treatment unit

Energy Technology Data Exchange (ETDEWEB)

Dirkx, M L.P.; Kroonwijk, M; De Boer, J C.J.; Heijmen, B J.M. [Nederlands Kanker Inst. ` Antoni van Leeuwenhoekhuis` , Amsterdam (Netherlands)

1995-12-01

The MM50 Racetrack Microtron, suited for sophisticated three-dimensional computer-controlled conformal radiotherapy techniques, is a complex treatment unit in various respects. Therefore, for a number of gantry angles, daily quality control of the absolute output and the profiles of the scanned photon beams in mandatory. A fast method for these daily checks, based on dosimetric measurements with the Philips SRI-100 Electronic Portal Imaging Device, has been developed and tested. Open beams are checked for four different gantry angles; for gantry angle 0, a wedged field is checked as well. The fields are set up one after another under full computer control. Performing and analyzing the measurements takes about ten minutes. The applied EPID has favourable characteristics for dosimetric quality control measurements: absolute measurements reproduce within 0.5% (1 SD) and the reproducibility of a relative (2-D) fluence profile is 0.2% (1 SD). The day-to-day sensitivity stability over a period of a month is 0.6% (1 SD). EPID-signals are within 0.2% linear with the applied dose. The 2-D fluence profile of the 25 MV photon beam of the MM50 is very stable in time: during a period of one year, a maximum fluctuation of 2.6% was observed. Once, a deviation in the cGy/MU-value of 6% was detected. Only because of the performed morning quality control checks with the EPID, erroneous dose delivery to patients could be avoided; there is no interlock in the MM50-system that would have prevented patient treatment. Based on our experiences and on clinical requirements regarding the acceptability of deviations of beam characteristics, a protocol has been developed including action levels for additional investigations. Studies on the application of the SRI-100 for in vivo dosimetry on the MM50 have been started.

Application of an EPID for fast daily dosimetric quality control of a fully computer-controlled treatment unit

International Nuclear Information System (INIS)

Dirkx, M.L.P.; Kroonwijk, M.; De Boer, J.C.J.; Heijmen, B.J.M.

1995-01-01

The MM50 Racetrack Microtron, suited for sophisticated three-dimensional computer-controlled conformal radiotherapy techniques, is a complex treatment unit in various respects. Therefore, for a number of gantry angles, daily quality control of the absolute output and the profiles of the scanned photon beams in mandatory. A fast method for these daily checks, based on dosimetric measurements with the Philips SRI-100 Electronic Portal Imaging Device, has been developed and tested. Open beams are checked for four different gantry angles; for gantry angle 0, a wedged field is checked as well. The fields are set up one after another under full computer control. Performing and analyzing the measurements takes about ten minutes. The applied EPID has favourable characteristics for dosimetric quality control measurements: absolute measurements reproduce within 0.5% (1 SD) and the reproducibility of a relative (2-D) fluence profile is 0.2% (1 SD). The day-to-day sensitivity stability over a period of a month is 0.6% (1 SD). EPID-signals are within 0.2% linear with the applied dose. The 2-D fluence profile of the 25 MV photon beam of the MM50 is very stable in time: during a period of one year, a maximum fluctuation of 2.6% was observed. Once, a deviation in the cGy/MU-value of 6% was detected. Only because of the performed morning quality control checks with the EPID, erroneous dose delivery to patients could be avoided; there is no interlock in the MM50-system that would have prevented patient treatment. Based on our experiences and on clinical requirements regarding the acceptability of deviations of beam characteristics, a protocol has been developed including action levels for additional investigations. Studies on the application of the SRI-100 for in vivo dosimetry on the MM50 have been started

EPID-based in vivo dosimetry for stereotactic body radiotherapy of non-small cell lung tumors: Initial clinical experience.

Science.gov (United States)

Consorti, R; Fidanzio, A; Brainovich, V; Mangiacotti, F; De Spirito, M; Mirri, M A; Petrucci, A

2017-10-01

EPID-based in vivo dosimetry (IVD) has been implemented for stereotactic body radiotherapy treatments of non-small cell lung cancer to check both isocenter dose and the treatment reproducibility comparing EPID portal images. 15 patients with lung tumors of small dimensions and treated with volumetric modulated arc therapy were enrolled for this initial experience. IVD tests supplied ratios R between in vivo reconstructed and planned isocenter doses. Moreover a γ-like analysis between daily EPID portal images and a reference one, in terms of percentage of points with γ-value smaller than 1, P γlevels of 5% for R ratio, P γlevel, and an average P γ90%. Paradigmatic discrepancies were observed in three patients: a set-up error and a patient morphological change were identified thanks to CBCT image analysis whereas the third discrepancy was not fully justified. This procedure can provide improved patient safety as well as a first step to integrate IVD and CBCT dose recalculation. Copyright © 2017 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

Robustness and precision of an automatic marker detection algorithm for online prostate daily targeting using a standard V-EPID.

Science.gov (United States)

Aubin, S; Beaulieu, L; Pouliot, S; Pouliot, J; Roy, R; Girouard, L M; Martel-Brisson, N; Vigneault, E; Laverdière, J

2003-07-01

An algorithm for the daily localization of the prostate using implanted markers and a standard video-based electronic portal imaging device (V-EPID) has been tested. Prior to planning, three gold markers were implanted in the prostate of seven patients. The clinical images were acquired with a BeamViewPlus 2.1 V-EPID for each field during the normal course radiotherapy treatment and are used off-line to determine the ability of the automatic marker detection algorithm to adequately and consistently detect the markers. Clinical images were obtained with various dose levels from ranging 2.5 to 75 MU. The algorithm is based on marker attenuation characterization in the portal image and spatial distribution. A total of 1182 clinical images were taken. The results show an average efficiency of 93% for the markers detected individually and 85% for the group of markers. This algorithm accomplishes the detection and validation in 0.20-0.40 s. When the center of mass of the group of implanted markers is used, then all displacements can be corrected to within 1.0 mm in 84% of the cases and within 1.5 mm in 97% of cases. The standard video-based EPID tested provides excellent marker detection capability even with low dose levels. The V-EPID can be used successfully with radiopaque markers and the automatic detection algorithm to track and correct the daily setup deviations due to organ motions.

Quiste epidérmico de inclusión de párpado. Presentación de 2 casos

OpenAIRE

Eréndira Güemez Sandoval; Fátima Cedillo Azuela; Rosalba García Ramírez

2017-01-01

El quiste epidérmico de inclusión o quiste epidermoide es una lesión intraepitelial, redonda u ovalada, de color amarillo, de crecimiento progresivo y consistencia suave; de diversa etiología, se origina por la proliferación de las células epidérmicas superficiales dentro de la dermis y su contenido es queratina. Se presenta frecuentemente en los párpados. El diagnóstico se realiza por la clínica y por el estudio histopatológico; el tratamiento es con escisión quirúrgica completa.

Investigations on uncertainties in patient positioning for prostate treatment with EPID

International Nuclear Information System (INIS)

Bakai, A.; Nuesslin, F.; Paulsen, F.; Plasswilm, L.; Bamberg, M.

2002-01-01

Background: Conformal radiotherapy techniques as used in prostate treatment allow to spare normal tissue by conforming the radiation fields to the shape of the planning target volume (PTV). To be able to fully utilize the advantages of these techniques correct patient positioning is an important prerequisite. This study employing an electronic portal imaging device (EPID) investigated the positioning uncertainties that occur in the pelvic region for different patient positioning devices. Patients and Methods: 15 patients with prostate cancer were irradiated with or without rectal balloon/pelvic mask at a linear accelerator with multileaf collimator (MLC). For each patient multiple portal images were taken from different directions and compared to the digitally reconstructed radiographs (DRRs) of the treatment planning system and to simulation films (Table 1, Figure 1). Results: In spite of different positioning devices, all patients showed comparable total positioning uncertainties of 4.0 mm (lateral), 4.5 mm (cranio-caudal) and 1.7 mm (dorso-ventral). The lateral positioning error was reduced for the pelvic mask patients while the cranio-caudal error increased (Table 2, Figure 2). A systematic and a random component sum up to the total positioning error, and a good estimate of the magnitudes of the two is possible from six to eight portal images (Figure 3). Conclusions: With a small number of portal images it is possible to find out the systematic and random positioning error of a patient. Knowledge of the random error can be used to resize the treatment margin which is clinically relevant since this error differs greatly for different patients (Figure 4). Image analysis with EPID is convenient, yet has some problems. For example, one only gets indirect information on the movement of the ventral rectum wall. The successful operation of positioning devices, although, needs further improvement - especially if one focuses on IMRT. (orig.) [de

SU-F-T-263: Dosimetric Characteristics of the Cine Acquisition Mode of An A-Si EPID

Energy Technology Data Exchange (ETDEWEB)

Bawazeer, O; Deb, P [RMIT University, Melbourne, VIC (Australia); Sarasanandarajah, S [Peter MacCallum Cancer Institute, Melbourne, Victoria (Australia); Herath, S; Kron, T [Peter MacCallum Cancer Institute, Melbourne, VIC (Australia)

2016-06-15

Purpose: To investigate the dosimetric characteristics of Varian a-Si-500 electronic portal imaging device (EPID) operated in cine mode particularly considering linearity with delivered dose, dose rate, field size, phantom thickness, MLC speed and common IMRT fields. Methods: The EPID that attached to a Varian Clinac 21iX linear accelerator, was irradiated with 6 and 18 MV using 600 MU/min. Image acquisition is controlled by the IAS3 software, Trigger delay was 6 ms, BeamOnDelay and FrameStartDelay were zero. Different frame rates were utilized. Cine mode response was calculated using MATLAB as summation of mean pixel values in a region of interest of the acquired images. The performance of cine mode was compared to integrated mode and dose measurements in water using CC13 ionization chamber. Results: Figure1 illustrates that cine mode has nonlinear response for small MU, when delivering 10 MU was about 0.5 and 0.64 for 6 and 18 MV respectively. This is because the missing acquired images that were calculated around four images missing in each delivery. With the increase MU the response became linear and comparable with integrated mode and ionization chamber within 2%. Figure 2 shows that cine mode has comparable response with integrated mode and ionization chamber within 2% with changing dose rate for 10 MU delivered. This indicates that the dose rate change has no effect on nonlinearity of cine mode response. Except nonlinearity, cine mode is well matched to integrated mode response within 2% for field size, phantom thickness, MLC speed dependences. Conclusion: Cine mode has similar dosimetric characteristics to integrated mode with open and IMRT fields, and the main limitation with cine mode is missing images. Therefore, the calibration of EPID images with this mode should be run with large MU, and when IMRT verification field has low MU, the correction for missing images are required.

SU-F-T-263: Dosimetric Characteristics of the Cine Acquisition Mode of An A-Si EPID

International Nuclear Information System (INIS)

Bawazeer, O; Deb, P; Sarasanandarajah, S; Herath, S; Kron, T

2016-01-01

Purpose: To investigate the dosimetric characteristics of Varian a-Si-500 electronic portal imaging device (EPID) operated in cine mode particularly considering linearity with delivered dose, dose rate, field size, phantom thickness, MLC speed and common IMRT fields. Methods: The EPID that attached to a Varian Clinac 21iX linear accelerator, was irradiated with 6 and 18 MV using 600 MU/min. Image acquisition is controlled by the IAS3 software, Trigger delay was 6 ms, BeamOnDelay and FrameStartDelay were zero. Different frame rates were utilized. Cine mode response was calculated using MATLAB as summation of mean pixel values in a region of interest of the acquired images. The performance of cine mode was compared to integrated mode and dose measurements in water using CC13 ionization chamber. Results: Figure1 illustrates that cine mode has nonlinear response for small MU, when delivering 10 MU was about 0.5 and 0.64 for 6 and 18 MV respectively. This is because the missing acquired images that were calculated around four images missing in each delivery. With the increase MU the response became linear and comparable with integrated mode and ionization chamber within 2%. Figure 2 shows that cine mode has comparable response with integrated mode and ionization chamber within 2% with changing dose rate for 10 MU delivered. This indicates that the dose rate change has no effect on nonlinearity of cine mode response. Except nonlinearity, cine mode is well matched to integrated mode response within 2% for field size, phantom thickness, MLC speed dependences. Conclusion: Cine mode has similar dosimetric characteristics to integrated mode with open and IMRT fields, and the main limitation with cine mode is missing images. Therefore, the calibration of EPID images with this mode should be run with large MU, and when IMRT verification field has low MU, the correction for missing images are required.

SU-G-BRB-11: On the Sensitivity of An EPID-Based 3D Dose Verification System to Detect Delivery Errors in VMAT Treatments

Energy Technology Data Exchange (ETDEWEB)

Gonzalez, P; Olaciregui-Ruiz, I; Mijnheer, B; Mans, A; Rozendaal, R [Netherlands Cancer Institute - Antoni van Leeuwenhoek, Amsterdam, Noord-Holland (Netherlands)

2016-06-15

Purpose: To investigate the sensitivity of an EPID-based 3D dose verification system to detect delivery errors in VMAT treatments. Methods: For this study 41 EPID-reconstructed 3D in vivo dose distributions of 15 different VMAT plans (H&N, lung, prostate and rectum) were selected. To simulate the effect of delivery errors, their TPS plans were modified by: 1) scaling of the monitor units by ±3% and ±6% and 2) systematic shifting of leaf bank positions by ±1mm, ±2mm and ±5mm. The 3D in vivo dose distributions where then compared to the unmodified and modified treatment plans. To determine the detectability of the various delivery errors, we made use of a receiver operator characteristic (ROC) methodology. True positive and false positive rates were calculated as a function of the γ-parameters γmean, γ1% (near-maximum γ) and the PTV dose parameter ΔD{sub 50} (i.e. D{sub 50}(EPID)-D{sub 50}(TPS)). The ROC curve is constructed by plotting the true positive rate vs. the false positive rate. The area under the ROC curve (AUC) then serves as a measure of the performance of the EPID dosimetry system in detecting a particular error; an ideal system has AUC=1. Results: The AUC ranges for the machine output errors and systematic leaf position errors were [0.64 – 0.93] and [0.48 – 0.92] respectively using γmean, [0.57 – 0.79] and [0.46 – 0.85] using γ1% and [0.61 – 0.77] and [ 0.48 – 0.62] using ΔD{sub 50}. Conclusion: For the verification of VMAT deliveries, the parameter γmean is the best discriminator for the detection of systematic leaf position errors and monitor unit scaling errors. Compared to γmean and γ1%, the parameter ΔD{sub 50} performs worse as a discriminator in all cases.

Online 3D EPID-based dose verification: Proof of concept.

Science.gov (United States)

Spreeuw, Hanno; Rozendaal, Roel; Olaciregui-Ruiz, Igor; González, Patrick; Mans, Anton; Mijnheer, Ben; van Herk, Marcel

2016-07-01

Delivery errors during radiotherapy may lead to medical harm and reduced life expectancy for patients. Such serious incidents can be avoided by performing dose verification online, i.e., while the patient is being irradiated, creating the possibility of halting the linac in case of a large overdosage or underdosage. The offline EPID-based 3D in vivo dosimetry system clinically employed at our institute is in principle suited for online treatment verification, provided the system is able to complete 3D dose reconstruction and verification within 420 ms, the present acquisition time of a single EPID frame. It is the aim of this study to show that our EPID-based dosimetry system can be made fast enough to achieve online 3D in vivo dose verification. The current dose verification system was sped up in two ways. First, a new software package was developed to perform all computations that are not dependent on portal image acquisition separately, thus removing the need for doing these calculations in real time. Second, the 3D dose reconstruction algorithm was sped up via a new, multithreaded implementation. Dose verification was implemented by comparing planned with reconstructed 3D dose distributions delivered to two regions in a patient: the target volume and the nontarget volume receiving at least 10 cGy. In both volumes, the mean dose is compared, while in the nontarget volume, the near-maximum dose (D2) is compared as well. The real-time dosimetry system was tested by irradiating an anthropomorphic phantom with three VMAT plans: a 6 MV head-and-neck treatment plan, a 10 MV rectum treatment plan, and a 10 MV prostate treatment plan. In all plans, two types of serious delivery errors were introduced. The functionality of automatically halting the linac was also implemented and tested. The precomputation time per treatment was ∼180 s/treatment arc, depending on gantry angle resolution. The complete processing of a single portal frame, including dose verification, took

A simple approach for EPID dosimetric calibration to overcome the effect of image-lag and ghosting

International Nuclear Information System (INIS)

Alshanqity, Mukhtar; Duane, Simon; Nisbet, Andrew

2012-01-01

EPID dosimetry has known drawbacks. The main issue is that a measurable residual signal is observed after the end of irradiation for prolonged periods of time, thus making measurement difficult. We present a detailed analysis of EPID response and suggest a simple, yet accurate approach for calibration that avoids the complexity of incorporating ghosting and image-lag using the maximum integrated signal instead of the total integrated signal. This approach is linear with dose and independent of dose rate. - Highlights: ► Image-lag and ghosting effects dosimetric accuracy. ► Image-lag and ghosting result in the reduction of total integrated signal for low doses. ► Residual signal is the most significant result for the image-lag and ghosting effects. ► Image-lag and ghosting can result in under-dosing of up to 2.5%.

A methodology to determine margins by EPID measurements of patient setup variation and motion as applied to immobilization devices

International Nuclear Information System (INIS)

Prisciandaro, Joann I.; Frechette, Christina M.; Herman, Michael G.; Brown, Paul D.; Garces, Yolanda I.; Foote, Robert L.

2004-01-01

Assessment of clinic and site specific margins are essential for the effective use of three-dimensional and intensity modulated radiation therapy. An electronic portal imaging device (EPID) based methodology is introduced which allows individual and population based CTV-to-PTV margins to be determined and compared with traditional margins prescribed during treatment. This method was applied to a patient cohort receiving external beam head and neck radiotherapy under an IRB approved protocol. Although the full study involved the use of an EPID-based method to assess the impact of (1) simulation technique (2) immobilization, and (3) surgical intervention on inter- and intrafraction variations of individual and population-based CTV-to-PTV margins, the focus of the paper is on the technique. As an illustration, the methodology is utilized to examine the influence of two immobilization devices, the UON TM thermoplastic mask and the Type-S TM head/neck shoulder immobilization system on margins. Daily through port images were acquired for selected fields for each patient with an EPID. To analyze these images, simulation films or digitally reconstructed radiographs (DRR's) were imported into the EPID software. Up to five anatomical landmarks were identified and outlined by the clinician and up to three of these structures were matched for each reference image. Once the individual based errors were quantified, the patient results were grouped into populations by matched anatomical structures and immobilization device. The variation within the subgroup was quantified by calculating the systematic and random errors (Σ sub and σ sub ). Individual patient margins were approximated as 1.65 times the individual-based random error and ranged from 1.1 to 6.3 mm (A-P) and 1.1 to 12.3 mm (S-I) for fields matched on skull and cervical structures, and 1.7 to 10.2 mm (L-R) and 2.0 to 13.8 mm (S-I) for supraclavicular fields. Population-based margins ranging from 5.1 to 6.6 mm (A

Commissioning of Portal Dosimetry and characterization of an EPID; Comissionamento de Portal Dosimetry e caracterizacao de EPID

Energy Technology Data Exchange (ETDEWEB)

Olbi, D.S.; Sales, C.P. [Universidade de Sao Paulo (USP), SP (Brazil). Faculdade de Medicina; Nakandakari, M.V.N., E-mail: diego.olbi@hc.fm.usp.br [Instituto do Cancer do Estado de Sao Paulo, SP (Brazil). Servico de Radioterapia

2016-07-01

The development of technologies compensator blocks, MLC, high dose rate accelerators, treatment planning systems, among others, permitted that new treatment techniques in radiotherapy were created. Such techniques have the capacity to modulate radiation beam fluency (IMRT, VMAT), or to deliver high doses in few fractions or unique fractions (SRS). Following the same tendency, quality control of planning became more complex. It is necessary to evaluate the fluency delivered by the accelerator. Its levels of does and its spatial distribution should co-occur with the fluency calculated by TPS. Acquisition of new detector devices in quality control of treatments is fundamental to apply techniques. Portal Vision is a device EPID has the capacity to operate either in image mode or dosimetry mode, with the allowance of Portal Dosimetry. To evaluated planning in IMRT, the device is irradiated using planning e, therefore, the fluency measured is compared with calculated fluency, through gamma analysis. The aim of this work was to perform tests of commissioning of this device. (author)

SU-E-T-335: Transit Dosimetry for Verification of Dose Delivery Using Electronic Portal Imaging Device (EPID)

Energy Technology Data Exchange (ETDEWEB)

Baek, T [Korea University, Seoul (Korea, Republic of); National Health Insurance Co.Ilsan Hospital, Ilsan (Korea, Republic of); Chung, E [National Health Insurance Co.Ilsan Hospital, Ilsan (Korea, Republic of); Lee, S [Cheil General Hospital and Women Healthcare Center, Kwandong University, Seoul (Korea, Republic of); Yoon, M [Korea University, Seoul (Korea, Republic of)

2014-06-01

Purpose: To evaluate the effectiveness of transit dose, measured with an electronic portal imaging device (EPID), in verifying actual dose delivery to patients. Methods: Plans of 5 patients with lung cancer, who received IMRT treatment, were examined using homogeneous solid water phantom and inhomogeneous anthropomorphic phantom. To simulate error in patient positioning, the anthropomorphic phantom was displaced from 5 mm to 10 mm in the inferior to superior (IS), superior to inferior (SI), left to right (LR), and right to left (RL) directions. The transit dose distribution was measured with EPID and was compared to the planed dose using gamma index. Results: Although the average passing rate based on gamma index (GI) with a 3% dose and a 3 mm distance-to-dose agreement tolerance limit was 94.34 % for the transit dose with homogeneous phantom, it was reduced to 84.63 % for the transit dose with inhomogeneous anthropomorphic phantom. The Result also shows that the setup error of 5mm (10mm) in IS, SI, LR and SI direction can Result in the decrease in values of GI passing rates by 1.3% (3.0%), 2.2% (4.3%), 5.9% (10.9%), and 8.9% (16.3%), respectively. Conclusion: Our feasibility study suggests that the transit dose-based quality assurance may provide information regarding accuracy of dose delivery as well as patient positioning.

Comparison Between the Spectrum reconstruction methodology and release transmitted by both based in pictures taken EPID; Comparacion entre la metodologia de recostruccion de espectros por transmision y por disperison, ambas basadas en imagenes tomadas con EPID

Energy Technology Data Exchange (ETDEWEB)

Juste, B.; Miro, R.; Jambrina, A.; Campayo, J. M.; Diez, S.; Santos, A.; Verdu, V.

2013-07-01

A comparison of the spectral reconstruction based on data transmission and spectral reconstruction based on scattering data is presented, we have both developed using EPID images. It is shown that the reconstruction results based on transmission offer much better fit with the theoretical predictions.

Effects of BM-573 on Endothelial Dependent Relaxation and Increased Blood Pressure at Early Stages of Atherosclerosis.

Directory of Open Access Journals (Sweden)

Miguel Romero

Full Text Available Endothelial dysfunction is considered to be an early event in atherosclerosis and plays a pivotal role in the development, progression and clinical complications of atherosclerosis. Previous studies have shown the beneficial effects of combined inhibition of thromboxane synthase and antagonism of thromboxane receptors by BM-573 on atherosclerosis; however our knowledge about the beneficial effects of BM-573 on endothelial function and increased blood pressure related to early stage of atherosclerosis is limited. In the present study, we investigated the effects of short-term (3 μM, 1 hour and chronic (10 mg/L, 8 weeks treatments with BM-573 on vasodilatory function, nitric oxide (NO bioavailability, oxidative stress and systolic blood pressure in 15 weeks old apolipoprotein E-deficient (ApoE-KO mice. ApoE-KO mice showed a reduced endothelium-derived relaxation. In addition, NO bioavailability was reduced and oxidative stress and blood pressure were increased in ApoE-KO mice versus wild-type mice. BM-573 treatments were able to improve the relaxation profile in ApoE-KO mice. Short-term effects of BM-573 were mainly mediated by an increased phosphorylation of both eNOS and Akt, whereas BM-573 in vivo treatment also reduced oxidative stress and restored NO bioavailability. In addition, chronic administration of BM-573 reduced systolic blood pressure in ApoE-KO mice. In conclusion, pharmacological modulation of TxA2 biosynthesis and biological activities by dual TP antagonism/TxAS inhibition with BM-573, already known to prevent plaque formation, has the potential to correct vasodilatory dysfunction at the early stages of atherosclerosis.

SU-E-T-139: Automated Daily EPID Exit Dose Analysis Uncovers Treatment Variations

Energy Technology Data Exchange (ETDEWEB)

Olch, A [University of Southern California, Los Angeles, CA (United States)

2015-06-15

Purpose: To evaluate a fully automated EPID exit dose system for its ability to detect daily treatment deviations including patient setup, delivery, and anatomy changes. Methods: PerFRACTION (Sun Nuclear Corporation) software is a system that uses integrated EPID images taken during patient treatment and automatically pulled from the Aria database and analyzed based on user-defined comparisons. This was used to monitor 20 plans consisting of a total of 859 fields for 18 patients, for a total of 251 fractions. Nine VMAT, 5 IMRT, and 6 3D plans were monitored. The Gamma analysis was performed for each field within a plan, comparing the first fraction against each of the other fractions in each treatment course. A 2% dose difference, 1 mm distance-to-agreement, and 10% dose threshold was used. These tight tolerances were chosen to achieve a high sensitivity to treatment variations. The field passed if 93% of the pixels had a Gamma of 1 or less. Results: Twenty-nine percent of the fields failed. The average plan passing rate was 92.5%.The average 3D plan passing rate was less than for VMAT or IMRT, 84%, vs. an average of 96.2%. When fields failed, an investigation revealed changes in patient anatomy or setup variations, often also leading to variations of transmission through immobilization devices. Conclusion: PerFRACTION is a fully automated system for determining daily changes in dose transmission through the patient that requires no effort other than for the imager panel to be deployed during treatment. A surprising number of fields failed the analysis and can be attributed to important treatment variations that would otherwise not be appreciated. Further study of inter-fraction treatment variations is possible and warranted. Sun Nuclear Corporation provided a license to the software described.

Hardening and embrittlement mechanisms of reduced activation ferritic/martensitic steels irradiated at 573 K

Energy Technology Data Exchange (ETDEWEB)

Tanigawa, H. [Japan Atomic Energy Agency, Tokai-mura, Naga-gun, Ibaraki-ken (Japan); Klueh, R.L. [Oak Ridge Noational Laboratory, TN (United States); Hashimoto, N. [Hokkaido Univ., Materials Science and Engineering Div., Graduate School of Engineering, Sapporo (Japan); Sokolov, M. [Oak Ridge National Laboratory, Materials Science and Technology Div., TN (United States)

2007-07-01

Full text of publication follows: It has been reported that reduced-activation ferritic/martensitic steels (RAFMs), such as F82H, ORNL9Cr-2WVTa, and JLF-1, showed a variety of changes in ductile-brittle transition temperature and yield stress after irradiation at 573 K up to 5 dpa, and those differences could not be interpreted solely by the difference of dislocation microstructure induced by irradiation. To investigate the impact of other microstructural feature, i.e. precipitates, the precipitation behavior of F82H, ORNL 9Cr-2WVTa, and JLF-1 was examined. It was revealed that irradiation-induced precipitation and amorphization of precipitates partly occurred and caused the different precipitation on block, packet and prior austenitic grain boundaries. In addition to these phenomena, irradiation-induced nano-size precipitates were also observed in the matrix. It was also revealed that the chemical compositions of precipitates approached the calculated thermal equilibrium state of M{sub 23}C{sub 6} at an irradiation temperature of 573 K. The calculation also suggests the presence of Laves phase at 573 K, which is usually not observed at this temperature, but the ion irradiation on aged F82H with Laves phase suggests that Laves phase becomes amorphous and could not be stable under irradiation at 573 K. This observation indicates the possibility that the irradiation-induced nano-size precipitation could be the consequence of the conflict between precipitation and amorphization of Laves phase. Over all, these observations suggests that the variety of embrittlement and hardening of RAFMs observed at 573 K irradiation up to 5 dpa might be the consequence of the transition phenomena that occur as the microstructure approaches thermal equilibrium during irradiation at 573 K. (authors)

12 CFR 573.13 - Exception to opt out requirements for service providers and joint marketing.

Science.gov (United States)

2010-01-01

... this section to a financial institution with which you perform joint marketing, your contractual... products or services or marketing of financial products or services offered pursuant to joint agreements... providers and joint marketing. 573.13 Section 573.13 Banks and Banking OFFICE OF THRIFT SUPERVISION...

Feasibility of megavoltage portal CT using an electronic portal imaging device (EPID) and a multi-level scheme algebraic reconstruction technique (MLS-ART)

International Nuclear Information System (INIS)

Guan, Huaiqun; Zhu, Yunping

1998-01-01

Although electronic portal imaging devices (EPIDs) are efficient tools for radiation therapy verification, they only provide images of overlapped anatomic structures. We investigated using a fluorescent screen/CCD-based EPID, coupled with a novel multi-level scheme algebraic reconstruction technique (MLS-ART), for a feasibility study of portal computed tomography (CT) reconstructions. The CT images might be useful for radiation treatment planning and verification. We used an EPID, set it to work at the linear dynamic range and collimated 6 MV photons from a linear accelerator to a slit beam of 1 cm wide and 25 cm long. We performed scans under a total of ∼200 monitor units (MUs) for several phantoms in which we varied the number of projections and MUs per projection. The reconstructed images demonstrated that using the new MLS-ART technique megavoltage portal CT with a total of 200 MUs can achieve a contrast detectibility of ∼2.5% (object size 5mmx5mm) and a spatial resolution of 2.5 mm. (author)

TH-E-17A-10: Markerless Lung Tumor Tracking Based On Beams Eye View EPID Images

Energy Technology Data Exchange (ETDEWEB)

Chiu, T; Kearney, V; Liu, H; Jiang, L; Foster, R; Mao, W [UT Southwestern Medical Center, Dallas, Texas (United States); Rozario, T; Bereg, S [University of Texas at Dallas, Richardson, Texas (United States); Klash, S [Premier Cancer Centers, Dallas, TX (United States)

2014-06-15

Purpose: Dynamic tumor tracking or motion compensation techniques have proposed to modify beam delivery following lung tumor motion on the flight. Conventional treatment plan QA could be performed in advance since every delivery may be different. Markerless lung tumor tracking using beams eye view EPID images provides a best treatment evaluation mechanism. The purpose of this study is to improve the accuracy of the online markerless lung tumor motion tracking method. Methods: The lung tumor could be located on every frame of MV images during radiation therapy treatment by comparing with corresponding digitally reconstructed radiograph (DRR). A kV-MV CT corresponding curve is applied on planning kV CT to generate MV CT images for patients in order to enhance the similarity between DRRs and MV treatment images. This kV-MV CT corresponding curve was obtained by scanning a same CT electron density phantom by a kV CT scanner and MV scanner (Tomotherapy) or MV CBCT. Two sets of MV DRRs were then generated for tumor and anatomy without tumor as the references to tracking the tumor on beams eye view EPID images. Results: Phantom studies were performed on a Varian TrueBeam linac. MV treatment images were acquired continuously during each treatment beam delivery at 12 gantry angles by iTools. Markerless tumor tracking was applied with DRRs generated from simulated MVCT. Tumors were tracked on every frame of images and compared with expected positions based on programed phantom motion. It was found that the average tracking error were 2.3 mm. Conclusion: This algorithm is capable of detecting lung tumors at complicated environment without implanting markers. It should be noted that the CT data has a slice thickness of 3 mm. This shows the statistical accuracy is better than the spatial accuracy. This project has been supported by a Varian Research Grant.

Epidémiologie de l'infection urinaire chez l'enfant au CHU-Campus ...

African Journals Online (AJOL)

Titre : Epidémiologie de l'infection urinaire chez l'enfant au CHU-Campus de Lomé. Objectif : Evaluer la prévalence et étudier l'épidémiologie des infections urinaires. Méthodologie : Il s'agit d'une étude prospective qui s'est déroulée du 1er janvier au 31décembre 2009, dans le service de pédiatrie du CHU-Campus de ...

SU-F-T-262: Commissioning Varian Portal Dosimetry for EPID-Based Patient Specific QA in a Non-Aria Environment

Energy Technology Data Exchange (ETDEWEB)

Schmidt, M; Knutson, N [Rhode Island Hospital, Providence RI (United States); University of Rhode Island, Kingston, RI (United States); University of Massachusetts Lowell, Lowell, MA (United States); Herrington, J [University of Rhode Island, Kingston, RI (United States); Price, M [Rhode Island Hospital, Providence RI (United States); University of Rhode Island, Kingston, RI (United States); Alpert Medical School of Brown University, Providence, RI (United States)

2016-06-15

Purpose: Development of an in-house program facilitates a workflow that allows Electronic Portal Imaging Device (EPID) patient specific quality assurance (QA) measurements to be acquired and analyzed in the Portal Dosimetry Application (Varian Medical Systems, Palo Alto, CA) using a non-Aria Record and Verify (R&V) system (MOSAIQ, Elekta, Crawley, UK) to deliver beams in standard clinical treatment mode. Methods: Initial calibration of an in-house software tool includes characterization of EPID dosimetry parameters by importing DICOM images of varying delivered MUs to determine linear mapping factors in order to convert image pixel values to Varian-defined Calibrated Units (CU). Using this information, the Portal Dose Image Prediction (PDIP) algorithm was commissioned by converting images of various field sizes to output factors using the Eclipse Scripting Application Programming Interface (ESAPI) and converting a delivered configuration fluence to absolute dose units. To verify the algorithm configuration, an integrated image was acquired, exported directly from the R&V client, automatically converted to a compatible, calibrated dosimetric image, and compared to a PDIP calculated image using Varian’s Portal Dosimetry Application. Results: For two C-Series and one TrueBeam Varian linear accelerators, gamma comparisons (global 3% / 3mm) of PDIP algorithm predicted dosimetric images and images converted via the inhouse system demonstrated agreement for ≥99% of all pixels, exceeding vendor-recommended commissioning guidelines. Conclusion: Combinations of a programmatic image conversion tool and ESAPI allow for an efficient and accurate method of patient IMRT QA incorporating a 3rd party R&V system.

Perfil de ingresos y urgencias pediátricas en período epidémico de rotavirus en Valladolid: Utilidad de un modelo predictivo Profile of paediatric admissions and emergencies during an epidemic period of rotavirus in Valladolid [Spain]: Utility of a predictive model

Directory of Open Access Journals (Sweden)

Francisco Javier Luquero

2009-02-01

Full Text Available Introducción: Este estudio pretende determinar las semanas de alta circulación de rotavirus en valladolid, y comparar las características de los ingresos y urgencias en período epidémico con respecto al período no epidémico. Métodos: Se utilizaron las declaraciones al sistema de información microbiológica, el conjunto mínimo básico de datos y el registro de urgencias. Se calcularon los casos esperados para 2006 a partir de un modelo elaborado previamente. Si los casos observados superaban el umbral superior del 95% de los esperados, la semana se consideró epidémica. Se compararon las características de los ingresos y urgencias en ambos períodos. Resultados: En 2006 se diagnosticaron un 42% menos de los casos esperados. La media de ingresos diarios fue superior en período epidémico (diferencia=1,49; p=0,01, y también fue mayor la duración media del ingreso. Conclusión: La actividad del servicio de pediatría se incrementó en período epidémico, por lo que es oportuna la implantación de actividades de vigilancia, programas de prevención y control frente a rotavirus en el ámbito hospitalario.Introduction: The aim of this study was to determine the weeks of high rotavirus circulation in Valladolid (Spain and to compare the characteristics of hospitalizations and emergencies in epidemic and nonepidemic periods. Methods: The information sources consisted of the weekly notifications to the Microbiological Information System, the Minimum Data Set, and the Emergency Registry. Expected cases for 2006 were calculated using a previously developed model. Weeks with observed cases over the upper limit of the 95% confidence interval for expected cases were considered epidemic periods. Hospitalization and emergencies in epidemic and nonepidemic periods were compared. Results: The number of cases in 2006 was 42% less than the expected number. The mean number of daily admissions was higher in epidemic periods (d=1.49; p=0.01 and the

21 CFR 573.380 - Ethoxyquin in animal feeds.

Science.gov (United States)

2010-04-01

...) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS FOOD ADDITIVES PERMITTED IN FEED AND DRINKING WATER OF ANIMALS Food Additive Listing § 573.380 Ethoxyquin in animal feeds. Ethoxyquin (1,2-dihydro-6-ethoxy-2,2,4... oxidation of carotene, xanthophylls, and vitamins A and E in animal feed and fish food and, (2) as an aid in...

Estudio de diez casos de encefalitis letárgica epidémica

OpenAIRE

Grossman, Morris

2014-01-01

La aparición en forma epidémica de una rara enfermedad que afecta profundamente el sistema nervioso central ha suscitado, durante estos últimos tres años, mucho interés en el mundo científico. Esta enfermedad ha sido estudiada con mayor ahinco en Austria y Australia, en donde apareció en 1917 y en Inglaterra, Francia y Estados Unidos en donde se presentó después. The appearance in epidemic form of a rare disease that profoundly affects the central nervous system has raised during the past ...

TH-CD-207A-02: Implementation of Live EPID-Based Inspiration Level Assessment (LEILA) for Deepinspiration Breath-Hold (DIBH) Monitoring Using MV Fluoroscopy

Energy Technology Data Exchange (ETDEWEB)

Lehmann, J [Calvary Mater Newcastle, Newcastle (Australia); The University of Sydney, Sydney (Australia); The University of Newcastle, Newcastle (Australia); Sun, J; Fuangrod, T; Bhatia, S [Calvary Mater Newcastle, Newcastle (Australia); Doebrich, M; Greer, P [Calvary Mater Newcastle, Newcastle (Australia); The University of Newcastle, Newcastle (Australia); Zwan, B [The University of Newcastle, Newcastle (Australia); Central Coast Cancer Centre, Gosford (Australia)

2016-06-15

Purpose: As prior work has shown that current DIBH monitoring approaches using surrogate measures (marker block on chest) do not always correspond with the clinical quantity of interest (lung depth, LD), a software tool and workflow are introduced to use MV fluoroscopy during treatment for real-time / Live EPID-based Inspiration Level Assessment (LEILA). Methods: A prototype software tool calculates and displays the LD during the treatment of left sided breast cancer. Calculations are based on MV cine images which are acquired with the treatment beam thereby not incurring any additional imaging dose. Image capture and processing are implemented using a dedicated frame grabber computer. The calculation engine automatically detects image orientation and includes provisions for large treatment fields that exceed the size of the EPID panel. LD is measured along a line profile in the middle of the field. LEILA’s interface displays the current MV image, a reference image (DRR), the current LD, as well as a trace of LD over treatment time. The display includes patient specific LD tolerances. Tolerances are specified for each field and loaded before the treatment. A visual warning is generated when the tolerance is exceeded. LEILA is initially run in parallel with current DIBH techniques. When later run by itself DIBH setup will be done using skin marks and room laser. Results: Offline tests of LEILA confirmed accurate automatic LD measurement for a variety of patient geometries. Deployment of the EPID during all left sided breast treatments was well tolerated by patients and staff during a multi-month pilot. The frame grabber provides 11 frames-per-second; the MATLAB based LEILA prototype software can analyze five frames-per-second standalone on standard desktop hardware. Conclusion: LEILA provides an automated approach to quantitatively monitor LD on MV images during DIBH treatment. Future improvements include a database and further speed optimization.

31 CFR 500.573 - Certain donations of funds and goods to meet basic human needs authorized.

Science.gov (United States)

2010-07-01

... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Certain donations of funds and goods to meet basic human needs authorized. 500.573 Section 500.573 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued) OFFICE OF FOREIGN ASSETS CONTROL, DEPARTMENT OF THE TREASURY...

Investigations on uncertainties in patient positioning for prostate treatment with EPID; Untersuchungen zur Positionierungsgenauigkeit bei Prostatakonformationsbestrahlungen mittels Portal-Imaging

Energy Technology Data Exchange (ETDEWEB)

Bakai, A.; Nuesslin, F. [Universitaetsklinik fuer Radioonkologie, Tuebingen (Germany). Abt. Medizinische Physik; Paulsen, F.; Plasswilm, L.; Bamberg, M. [Universitaetsklinik fuer Radioonkologie, Tuebingen (Germany). Abt. Strahlentherapie

2002-02-01

Background: Conformal radiotherapy techniques as used in prostate treatment allow to spare normal tissue by conforming the radiation fields to the shape of the planning target volume (PTV). To be able to fully utilize the advantages of these techniques correct patient positioning is an important prerequisite. This study employing an electronic portal imaging device (EPID) investigated the positioning uncertainties that occur in the pelvic region for different patient positioning devices. Patients and Methods: 15 patients with prostate cancer were irradiated with or without rectal balloon/pelvic mask at a linear accelerator with multileaf collimator (MLC). For each patient multiple portal images were taken from different directions and compared to the digitally reconstructed radiographs (DRRs) of the treatment planning system and to simulation films (Table 1, Figure 1). Results: In spite of different positioning devices, all patients showed comparable total positioning uncertainties of 4.0 mm (lateral), 4.5 mm (cranio-caudal) and 1.7 mm (dorso-ventral). The lateral positioning error was reduced for the pelvic mask patients while the cranio-caudal error increased (Table 2, Figure 2). A systematic and a random component sum up to the total positioning error, and a good estimate of the magnitudes of the two is possible from six to eight portal images (Figure 3). Conclusions: With a small number of portal images it is possible to find out the systematic and random positioning error of a patient. Knowledge of the random error can be used to resize the treatment margin which is clinically relevant since this error differs greatly for different patients (Figure 4). Image analysis with EPID is convenient, yet has some problems. For example, one only gets indirect information on the movement of the ventral rectum wall. The successful operation of positioning devices, although, needs further improvement - especially if one focuses on IMRT. (orig.) [German] Hintergrund

20 CFR 416.573 - How much will we withhold from your title II and title VIII benefits to recover a title XVI...

Science.gov (United States)

2010-04-01

... 20 Employees' Benefits 2 2010-04-01 2010-04-01 false How much will we withhold from your title II... Payment of Benefits, Overpayments, and Underpayments § 416.573 How much will we withhold from your title...-due benefits. (b)(1) We will collect the overpayment from current monthly benefits due in a month by...

WE-D-BRA-04: Online 3D EPID-Based Dose Verification for Optimum Patient Safety

International Nuclear Information System (INIS)

Spreeuw, H; Rozendaal, R; Olaciregui-Ruiz, I; Mans, A; Mijnheer, B; Herk, M van; Gonzalez, P

2015-01-01

Purpose: To develop an online 3D dose verification tool based on EPID transit dosimetry to ensure optimum patient safety in radiotherapy treatments. Methods: A new software package was developed which processes EPID portal images online using a back-projection algorithm for the 3D dose reconstruction. The package processes portal images faster than the acquisition rate of the portal imager (∼ 2.5 fps). After a portal image is acquired, the software seeks for “hot spots” in the reconstructed 3D dose distribution. A hot spot is in this study defined as a 4 cm 3 cube where the average cumulative reconstructed dose exceeds the average total planned dose by at least 20% and 50 cGy. If a hot spot is detected, an alert is generated resulting in a linac halt. The software has been tested by irradiating an Alderson phantom after introducing various types of serious delivery errors. Results: In our first experiment the Alderson phantom was irradiated with two arcs from a 6 MV VMAT H&N treatment having a large leaf position error or a large monitor unit error. For both arcs and both errors the linac was halted before dose delivery was completed. When no error was introduced, the linac was not halted. The complete processing of a single portal frame, including hot spot detection, takes about 220 ms on a dual hexacore Intel Xeon 25 X5650 CPU at 2.66 GHz. Conclusion: A prototype online 3D dose verification tool using portal imaging has been developed and successfully tested for various kinds of gross delivery errors. The detection of hot spots was proven to be effective for the timely detection of these errors. Current work is focused on hot spot detection criteria for various treatment sites and the introduction of a clinical pilot program with online verification of hypo-fractionated (lung) treatments

Craniocaudal Safety Margin Calculation Based on Interfractional Changes in Tumor Motion in Lung SBRT Assessed With an EPID in Cine Mode

International Nuclear Information System (INIS)

Ueda, Yoshihiro; Miyazaki, Masayoshi; Nishiyama, Kinji; Suzuki, Osamu; Tsujii, Katsutomo; Miyagi, Ken

2012-01-01

Purpose: To evaluate setup error and interfractional changes in tumor motion magnitude using an electric portal imaging device in cine mode (EPID cine) during the course of stereotactic body radiation therapy (SBRT) for non–small-cell lung cancer (NSCLC) and to calculate margins to compensate for these variations. Materials and Methods: Subjects were 28 patients with Stage I NSCLC who underwent SBRT. Respiratory-correlated four-dimensional computed tomography (4D-CT) at simulation was binned into 10 respiratory phases, which provided average intensity projection CT data sets (AIP). On 4D-CT, peak-to-peak motion of the tumor (M-4DCT) in the craniocaudal direction was assessed and the tumor center (mean tumor position [MTP]) of the AIP (MTP-4DCT) was determined. At treatment, the tumor on cone beam CT was registered to that on AIP for patient setup. During three sessions of irradiation, peak-to-peak motion of the tumor (M-cine) and the mean tumor position (MTP-cine) were obtained using EPID cine and in-house software. Based on changes in tumor motion magnitude (∆M) and patient setup error (∆MTP), defined as differences between M-4DCT and M-cine and between MTP-4DCT and MTP-cine, a margin to compensate for these variations was calculated with Stroom’s formula. Results: The means (±standard deviation: SD) of M-4DCT and M-cine were 3.1 (±3.4) and 4.0 (±3.6) mm, respectively. The means (±SD) of ∆M and ∆MTP were 0.9 (±1.3) and 0.2 (±2.4) mm, respectively. Internal target volume-planning target volume (ITV-PTV) margins to compensate for ∆M, ∆MTP, and both combined were 3.7, 5.2, and 6.4 mm, respectively. Conclusion: EPID cine is a useful modality for assessing interfractional variations of tumor motion. The ITV-PTV margins to compensate for these variations can be calculated.

TU-FG-201-01: 18-Month Clinical Experience of a Linac Daily Quality Assurance (QA) Solution Using Only EPID and OBI

Energy Technology Data Exchange (ETDEWEB)

Cai, B; Sun, B; Yaddanapudi, S; Goddu, S; Li, H; Caruthers, D; Kavanaugh, J; Mutic, S [Washington University School of Medicine, Saint Louis, MO (United States)

2016-06-15

Purpose: To describe the clinical use of a Linear Accelerator (Linac) DailyQA system with only EPID and OBI. To assess the reliability over an 18-month period and improve the robustness of this system based on QA failure analysis. Methods: A DailyQA solution utilizing an in-house designed phantom, combined EPID and OBI image acquisitions, and a web-based data analysis and reporting system was commissioned and used in our clinic to measure geometric, dosimetry and imaging components of a Varian Truebeam Linac. During an 18-month period (335 working days), the Daily QA results, including the output constancy, beam flatness and symmetry, uniformity, TPR20/10, MV and KV imaging quality, were collected and analyzed. For output constancy measurement, an independent monthly QA system with an ionization chamber (IC) and annual/incidental TG51 measurements with ADCL IC were performed and cross-compared to Daily QA system. Thorough analyses were performed on the recorded QA failures to evaluate the machine performance, optimize the data analysis algorithm, adjust the tolerance setting and improve the training procedure to prevent future failures. Results: A clinical workflow including beam delivery, data analysis, QA report generation and physics approval was established and optimized to suit daily clinical operation. The output tests over the 335 working day period cross-correlated with the monthly QA system within 1.3% and TG51 results within 1%. QA passed with one attempt on 236 days out of 335 days. Based on the QA failures analysis, the Gamma criteria is revised from (1%, 1mm) to (2%, 1mm) considering both QA accuracy and efficiency. Data analysis algorithm is improved to handle multiple entries for a repeating test. Conclusion: We described our 18-month clinical experience on a novel DailyQA system using only EPID and OBI. The long term data presented demonstrated the system is suitable and reliable for Linac daily QA.

Closure Report for Corrective Action Unit 573: Alpha Contaminated Sites Nevada National Security Site, Nevada

Energy Technology Data Exchange (ETDEWEB)

Matthews, Patrick [Navarro, Las Vegas, NV (United States)

2017-03-01

This Closure Report (CR) presents information supporting the closure of Corrective Action Unit (CAU) 573: Alpha Contaminated Sites, Nevada National Security Site, Nevada. CAU 573 comprises the two corrective action sites (CASs): 05-23-02-GMX Alpha Contaminated Are-Closure in Place and 05-45-01-Atmospheric Test Site - Hamilton- Clean Closure. The purpose of this CR is to provide justification and documentation supporting the recommendation that no further corrective action is needed for CAU 573 based on the implementation of the corrective actions. Corrective action activities were performed at Hamilton from May 25 through June 30, 2016; and at GMX from May 25 to October 27, 2016, as set forth in the Corrective Action Decision Document (CADD)/Corrective Action Plan (CAP) for Corrective Action Unit 573: Alpha Contaminated Sites; and in accordance with the Soils Activity Quality Assurance Plan, which establishes requirements, technical planning, and general quality practices. Verification sample results were evaluated against data quality objective criteria developed by stakeholders that included representatives from the Nevada Division of Environmental Protection and the DOE, National Nuclear Security Administration Nevada Field Office (NNSA/NFO) during the corrective action alternative (CAA) meeting held on November 24, 2015. Radiological doses exceeding the final action level were assumed to be present within the high contamination areas associated with CAS 05-23-02, thus requiring corrective action. It was also assumed that radionuclides were present at levels that require corrective action within the soil/debris pile associated with CAS 05-45-01. During the CAU 573 CAA meeting, the CAA of closure in place with a use restriction (UR) was selected by the stakeholders as the preferred corrective action of the high contamination areas at CAS 05-23-02 (GMX), which contain high levels of removable contamination; and the CAA of clean closure was selected by the

Potential Capsule Switching from Serogroup Y to B: The Characterization of Three such Neisseria meningitidis Isolates Causing Invasive Meningococcal Disease in Canada

Directory of Open Access Journals (Sweden)

Raymond SW Tsang

2005-01-01

Full Text Available Three group B Neisseria meningitidis isolates, recovered from meningococcal disease cases in Canada and typed as B:2c:P1.5, were characterized. Multilocus sequence typing showed that all three isolates were related because of an identical sequence type (ST 573. Isolates typed as 2c:P1.5 are common in serogroup Y meningococci but rare in isolates from serogroups B or C. Although no serogroup Y isolates have been typed as ST-573, eight isolates showed five to six housekeeping gene alleles that were identical to that of ST-573. This suggested that the B:2c:P1.5 isolates may have originated from serogroup Y organisms, possibly by capsule switching.

Commissioning of Portal Dosimetry and characterization of an EPID

International Nuclear Information System (INIS)

Olbi, D.S.; Sales, C.P.; Nakandakari, M.V.N.

2016-01-01

The development of technologies compensator blocks, MLC, high dose rate accelerators, treatment planning systems, among others, permitted that new treatment techniques in radiotherapy were created. Such techniques have the capacity to modulate radiation beam fluency (IMRT, VMAT), or to deliver high doses in few fractions or unique fractions (SRS). Following the same tendency, quality control of planning became more complex. It is necessary to evaluate the fluency delivered by the accelerator. Its levels of does and its spatial distribution should co-occur with the fluency calculated by TPS. Acquisition of new detector devices in quality control of treatments is fundamental to apply techniques. Portal Vision is a device EPID has the capacity to operate either in image mode or dosimetry mode, with the allowance of Portal Dosimetry. To evaluated planning in IMRT, the device is irradiated using planning e, therefore, the fluency measured is compared with calculated fluency, through gamma analysis. The aim of this work was to perform tests of commissioning of this device. (author)

Corrective Action Investigation Plan for Corrective Action Unit 573: Alpha Contaminated Sites, Nevada National Security Site, Nevada, Revision 0

Energy Technology Data Exchange (ETDEWEB)

Matthews, Patrick

2014-05-01

Corrective Action Unit (CAU) 573 is located in Area 5 of the Nevada National Security Site, which is approximately 65 miles northwest of Las Vegas, Nevada. CAU 573 is a grouping of sites where there has been a suspected release of contamination associated with non-nuclear experiments and nuclear testing. This document describes the planned investigation of CAU 573, which comprises the following corrective action sites (CASs): • 05-23-02, GMX Alpha Contaminated Area • 05-45-01, Atmospheric Test Site - Hamilton These sites are being investigated because existing information on the nature and extent of potential contamination is insufficient to evaluate and recommend corrective action alternatives.

12 CFR 573.6 - Information to be included in privacy notices.

Science.gov (United States)

2010-01-01

... and 573.15; (4) The categories of nonpublic personal information about your former customers that you... personal information about your former customers, other than those parties to whom you disclose information... applicable; and (ii) State whether the third party is: (A) A service provider that performs marketing...

SU-E-J-112: The Impact of Cine EPID Image Acquisition Frame Rate On Markerless Soft-Tissue Tracking

Energy Technology Data Exchange (ETDEWEB)

Yip, S; Rottmann, J; Berbeco, R [Brigham and Women' s Hospital, Boston, MA (United States)

2014-06-01

Purpose: Although reduction of the cine EPID acquisition frame rate through multiple frame averaging may reduce hardware memory burden and decrease image noise, it can hinder the continuity of soft-tissue motion leading to poor auto-tracking results. The impact of motion blurring and image noise on the tracking performance was investigated. Methods: Phantom and patient images were acquired at a frame rate of 12.87Hz on an AS1000 portal imager. Low frame rate images were obtained by continuous frame averaging. A previously validated tracking algorithm was employed for auto-tracking. The difference between the programmed and auto-tracked positions of a Las Vegas phantom moving in the superior-inferior direction defined the tracking error (δ). Motion blurring was assessed by measuring the area change of the circle with the greatest depth. Additionally, lung tumors on 1747 frames acquired at eleven field angles from four radiotherapy patients are manually and automatically tracked with varying frame averaging. δ was defined by the position difference of the two tracking methods. Image noise was defined as the standard deviation of the background intensity. Motion blurring and image noise were correlated with δ using Pearson correlation coefficient (R). Results: For both phantom and patient studies, the auto-tracking errors increased at frame rates lower than 4.29Hz. Above 4.29Hz, changes in errors were negligible with δ<1.60mm. Motion blurring and image noise were observed to increase and decrease with frame averaging, respectively. Motion blurring and tracking errors were significantly correlated for the phantom (R=0.94) and patient studies (R=0.72). Moderate to poor correlation was found between image noise and tracking error with R -0.58 and -0.19 for both studies, respectively. Conclusion: An image acquisition frame rate of at least 4.29Hz is recommended for cine EPID tracking. Motion blurring in images with frame rates below 4.39Hz can substantially reduce the

SU-E-J-112: The Impact of Cine EPID Image Acquisition Frame Rate On Markerless Soft-Tissue Tracking

International Nuclear Information System (INIS)

Yip, S; Rottmann, J; Berbeco, R

2014-01-01

Purpose: Although reduction of the cine EPID acquisition frame rate through multiple frame averaging may reduce hardware memory burden and decrease image noise, it can hinder the continuity of soft-tissue motion leading to poor auto-tracking results. The impact of motion blurring and image noise on the tracking performance was investigated. Methods: Phantom and patient images were acquired at a frame rate of 12.87Hz on an AS1000 portal imager. Low frame rate images were obtained by continuous frame averaging. A previously validated tracking algorithm was employed for auto-tracking. The difference between the programmed and auto-tracked positions of a Las Vegas phantom moving in the superior-inferior direction defined the tracking error (δ). Motion blurring was assessed by measuring the area change of the circle with the greatest depth. Additionally, lung tumors on 1747 frames acquired at eleven field angles from four radiotherapy patients are manually and automatically tracked with varying frame averaging. δ was defined by the position difference of the two tracking methods. Image noise was defined as the standard deviation of the background intensity. Motion blurring and image noise were correlated with δ using Pearson correlation coefficient (R). Results: For both phantom and patient studies, the auto-tracking errors increased at frame rates lower than 4.29Hz. Above 4.29Hz, changes in errors were negligible with δ<1.60mm. Motion blurring and image noise were observed to increase and decrease with frame averaging, respectively. Motion blurring and tracking errors were significantly correlated for the phantom (R=0.94) and patient studies (R=0.72). Moderate to poor correlation was found between image noise and tracking error with R -0.58 and -0.19 for both studies, respectively. Conclusion: An image acquisition frame rate of at least 4.29Hz is recommended for cine EPID tracking. Motion blurring in images with frame rates below 4.39Hz can substantially reduce the

Genetic structure of Neisseria meningitidis serogroup C epidemic strains in South Brazil Estrutura genética de cepas epidêmicas de Neisseria meningitidis sorogrupo C do Sul do Brasil

Directory of Open Access Journals (Sweden)

Claudio Tavares Sacchi

1995-08-01

Full Text Available In the present study we report the results of an analysis, based on serotyping, multilocus enzyme electrophoresis (MEE, and ribotyping of N. meningitidis serogroup C strains isolated from patients with meningococcal disease (MD in Rio Grande do Sul (RS and Santa Catarina (SC States, Brazil, as the Center of Epidemiology Control of Ministry of Health detected an increasing of MD cases due to this serogroup in the last two years (1992-1993. We have demonstrated that the MD due to N.meningitidis serogroup C strains in RS and SC States occurring in the last 4 years were caused mainly by one clone of strains (ET 40, with isolates indistinguishable by serogroup, serotype, subtype and even by ribotyping. One small number of cases that were not due to an ET 40 strains, represent closely related clones that probably are new lineages generated from the ET 40 clone referred as ET 11A complex. We have also analyzed N.meningitidis serogroup C strains isolated in the greater São Paulo in 1976 as representative of the first post epidemic year in that region. The ribotyping method, as well as MEE, could provide useful information about the clonal characteristics of those isolates and also of strains isolated in south Brazil. The strains from 1976 have more similarity with the actual endemic than epidemic strains, by the ribotyping, sulfonamide sensitivity, and MEE results. In conclusion, serotyping with monoclonal antibodies (C:2b:P1.3, MEE (ET 11 and ET 11A complex, and ribotyping by using ClaI restriction enzyme (Rb2, were useful to characterize these epidemic strains of N.meningitidis related to the increased incidence of MD in different States of south Brazil. It is mostly probable that these N.meningitidis serogroup C strains have poor or no genetic corelation with 1971-1975 epidemic serogroup C strains. The genetic similarity of members of the ET 11 and ET 11A complex were confirmed by the ribotyping method by using three restriction endonucleases

Diagnóstico temprano en un brote epidémico del virus Dengue en Piura usando RT-PCR y nested-PCR

Directory of Open Access Journals (Sweden)

Oscar Nolasco

1997-07-01

Full Text Available Un test de diagnóstico temprano (RT-PCR y Nested-PCR fue evaluado y comparado con métodos convencionales (cultivo in vitro, IFI y MAC-ELISA. Treinta y cuatro sueros de pacientes correspondientes de un brote epidémico de la costa norte peruana (Mancora, Piura en mayo de 1997 fueron incluidos en este estudio. Todos los sueros fueron obtenidos de pacientes que presentaron en los primeros cinco días manifestaciones clínicas siendo diagnosticados luego como dengue serotipo 1. Asimismo, RT-PCR permitió diagnosticar 82% de los sueros (28/34, sin embargo Mac-ELISA y cultivo in vitro reconocieron unicamente 41% de los sueros (14/34 y 38% de los sueros (13/34 respectivamente. Por lo tanto, el uso de esta herramienta molecular (RT-PCR y Nested-PCR permitiró dar un diagnóstico temprano a estos pacientes y actuar inmediatamente ante la presencia de un brote epidémico.

Engraftment Site and Effectiveness of the Pan-Caspase Inhibitor F573 to Improve Engraftment in Mouse and Human Islet Transplantation in Mice.

Science.gov (United States)

Pepper, Andrew R; Bruni, Antonio; Pawlick, Rena; Wink, John; Rafiei, Yasmin; Gala-Lopez, Boris; Bral, Mariusz; Abualhassan, Nasser; Kin, Tatsuya; Shapiro, A M James

2017-10-01

Islet transplantation is an effective therapy in type 1 diabetes and recalcitrant hypoglycemia. However, there is an ongoing need to circumvent islet loss posttransplant. We explore herein the potential of the pan-caspase inhibitor F573 to mitigate early apoptosis-mediated islet death within portal and extrahepatic portal sites in mice. Mouse or human islets were cultured in standard media ±100 μM F573 and subsequently assessed for viability and apoptosis via terminal deoxynucleotidyl transferase dUTP nick end labeling staining and caspase-3 activation. Diabetic mice were transplanted with syngeneic islets placed under the kidney capsule (KC) or into the subcutaneous deviceless (DL) site at a marginal islet dose (150 islets), or into the portal vein (PV) at a full dose (500 islets). Human islets were transplanted under the KC of diabetic immunodeficient mice at a marginal dose (500 islet equivalents). Islets were cultured in the presence of F573, and F573 was administered subcutaneously on days 0 to 5 posttransplant. Control mice were transplanted with nontreated islets and were injected with saline. Graft function was measured by nonfasting blood glucose and glucose tolerance testing. F573 markedly reduced human and mouse islet apoptosis after in vitro culture (P islet function when transplanted under the KC (P islet marginal KC transplants. Conversely, F573 significantly improved mouse islet engraftment in the PV and DL site (P islet apoptosis and improves engraftment most effectively in the portal and DL subcutaneous sites.

WE-DE-BRA-04: A Cost-Effective Pixelated EPID Scintillator for Enhanced Contrast and DQE

Energy Technology Data Exchange (ETDEWEB)

Rottmann, J; Myronakis, M; Hu, Y; Berbeco, R [Brigham and Woman’s Hospital, Dana-Farber Cancer Institute and Harvard Medical School, Boston, MA (United States); Shedlock, D; Wang, A; Humber, D; Star-Lack, J [Varian Medical Systems, Palo Alto, CA (United States); Morf, D; Fueglistaller, R [Varian Medical Systems, Daettwil (Switzerland)

2016-06-15

Purpose: Beams-eye-view imaging applications such as real-time soft-tissue motion estimation and MV-CBCT are hindered by the inherently low image contrast of electronic portal imaging devices (EPID) currently in clinical use. We investigate a cost effective scintillating glass that provides substantially increased detective quantum efficiency (DQE) and contrast to noise ratio (CNR). Methods: A pixelated scintillator prototype was built from LKH-5 glass. The array is 12mm thick; 42.4×42.4cm2 wide and features 1.51mm pixel pitch with 20µm separation (glue+septa). The LKH-5 array was mounted on the active matrix flat panel imager (AMPFI) of an AS-1200 (Varian) with the GdO2S2:Tb removed. A second AS-1200 was utilized as reference detector. The prototype EPID was characterized in terms of CNR, modulation transfer function (MTF) and DQE. Additionally, the visibility of various fiducial markers typically used in the clinic as well as a realistic 3D-printed lung tumor model was assessed. All items were placed in a 12cm thick solid water phantom. CNR is estimated using a Las Vegas contrast phantom, presampled MTF is estimated using a slanted slit technique and the DQE is calculated from measured normalized noise power spectra (NPS) and the MTF. Results: DQE(0) for the LKH-5 prototype increased by a factor of 8× to about 10%, compared to the AS-1200 equipped with its standard GdO2S2:Tb scintillator. CNR increased by a factor of 5.3×. Due to the pixel size the MTF50 decreased by about 55% to 0.23lp/mm. The visibility of all fiducial markers as well as the tumor model were however markedly improved in comparison to an acquisition with the same parameters using the GdO2S2:Tb scintillator. Conclusion: LKH-5 scintillating glasses allow the cost effective construction of thick pixelated scintillators for portal imaging which can yield a substantial increase in DQE and CNR. Soft tissue and fiducial marker visibility was found to be markedly improved. The project was supported

Corrective Action Decision Document/Corrective Action Plan for Corrective Action Unit 573: Alpha Contaminated Sites Nevada National Security Site, Nevada, Revision 0

Energy Technology Data Exchange (ETDEWEB)

Matthews, Patrick [Nevada Site Office, Las Vegas, NV (United States)

2016-02-01

CAU 573 comprises the following corrective action sites (CASs): • 05-23-02, GMX Alpha Contaminated Area • 05-45-01, Atmospheric Test Site - Hamilton These two CASs include the release at the Hamilton weapons-related tower test and a series of 29 atmospheric experiments conducted at GMX. The two CASs are located in two distinctly separate areas within Area 5. To facilitate site investigation and data quality objective (DQO) decisions, all identified releases (i.e., CAS components) were organized into study groups. The reporting of investigation results and the evaluation of DQO decisions are at the release level. The corrective action alternatives (CAAs) were evaluated at the FFACO CAS level. The purpose of this CADD/CAP is to evaluate potential CAAs, provide the rationale for the selection of recommended CAAs, and provide the plan for implementation of the recommended CAA for CAU 573. Corrective action investigation (CAI) activities were performed from January 2015 through November 2015, as set forth in the CAU 573 Corrective Action Investigation Plan (CAIP). Analytes detected during the CAI were evaluated against appropriate final action levels (FALs) to identify the contaminants of concern. Assessment of the data generated from investigation activities conducted at CAU 573 revealed the following: • Radiological contamination within CAU 573 does not exceed the FALs (based on the Occasional Use Area exposure scenario). • Chemical contamination within CAU 573 does not exceed the FALs. • Potential source material—including lead plates, lead bricks, and lead-shielded cables—was removed during the investigation and requires no additional corrective action.

Corrective Action Decision Document/Corrective Action Plan for Corrective Action Unit 573: Alpha Contaminated Sites Nevada National Security Site, Nevada, Revision 0

International Nuclear Information System (INIS)

Matthews, Patrick

2016-01-01

CAU 573 comprises the following corrective action sites (CASs): • 05-23-02, GMX Alpha Contaminated Area • 05-45-01, Atmospheric Test Site - Hamilton These two CASs include the release at the Hamilton weapons-related tower test and a series of 29 atmospheric experiments conducted at GMX. The two CASs are located in two distinctly separate areas within Area 5. To facilitate site investigation and data quality objective (DQO) decisions, all identified releases (i.e., CAS components) were organized into study groups. The reporting of investigation results and the evaluation of DQO decisions are at the release level. The corrective action alternatives (CAAs) were evaluated at the FFACO CAS level. The purpose of this CADD/CAP is to evaluate potential CAAs, provide the rationale for the selection of recommended CAAs, and provide the plan for implementation of the recommended CAA for CAU 573. Corrective action investigation (CAI) activities were performed from January 2015 through November 2015, as set forth in the CAU 573 Corrective Action Investigation Plan (CAIP). Analytes detected during the CAI were evaluated against appropriate final action levels (FALs) to identify the contaminants of concern. Assessment of the data generated from investigation activities conducted at CAU 573 revealed the following: • Radiological contamination within CAU 573 does not exceed the FALs (based on the Occasional Use Area exposure scenario). • Chemical contamination within CAU 573 does not exceed the FALs. • Potential source material - including lead plates, lead bricks, and lead-shielded cables was removed during the investigation and requires no additional corrective action.

A study on characteristics of X-ray detector for CCD-based EPID

International Nuclear Information System (INIS)

Chung, Yong Hyun

1999-02-01

The combination of the metal plate/phosphor screen as a x-ray detector with a CCD camera is the most popular detector system among various electronic portal imaging devices (EPIDs). There is a need to optimize the thickness of the metal plate/phosphor screen with high detection efficiency and high spatial resolution for effective transferring of anatomical information. In this study, the thickness dependency on the detection efficiency and the spatial resolution of the metal plate/phosphor screen was investigated by calculation and measurement. The result can be used to determine the optimal thickness of the metal plate as well as of the phosphor screen for the x-ray detector design of therapeutic x-ray imaging and for any specific application. Bremsstrahlung spectrum was calculated by Monte Carlo simulation and by Schiff formula. The detection efficiency was calculated from the total absorbed energy in the phosphor screen using the Monte Carlo simulation and the light output was measured. The spatial resolution, which was defined from the spatial distribution of the absorbed energy, was also calculated and the edge spread function was measured. It was found that the detection efficiency and the spatial resolution were mainly determined by the thickness of metal plate and phosphor screen, respectively. It was also revealed that the detection efficiency and the spatial resolution have trade-off in term of the thickness of the phosphor screen. As the phosphor thickness increases, the detection efficiency increases but the spatial resolution decreases. The curve illustrating the trade-off between the detection efficiency and the spatial resolution of the metal plate/phosphor screen detector is obtained as a function of the phosphor thickness. Based on the calculations, prototype CCD-based EPID was developed and then tested by acquiring phantom images for 6 MV x-ray beam. While, among the captured images, each frame suffered from quantum noise, the frame averaging

12 CFR 573.15 - Other exceptions to notice and opt out requirements.

Science.gov (United States)

2010-01-01

... consumer. (2) A consumer may revoke consent by subsequently exercising the right to opt out of future... PRIVACY OF CONSUMER FINANCIAL INFORMATION Exceptions § 573.15 Other exceptions to notice and opt out... consumer, provided that the consumer has not revoked the consent or direction; (2)(i) To protect the...

B Vitamins and the Brain: Mechanisms, Dose and Efficacy—A Review

OpenAIRE

Kennedy, David

2016-01-01

The B-vitamins comprise a group of eight water soluble vitamins that perform essential, closely inter-related roles in cellular functioning, acting as co-enzymes in a vast array of catabolic and anabolic enzymatic reactions. Their collective effects are particularly prevalent to numerous aspects of brain function, including energy production, DNA/RNA synthesis/repair, genomic and non-genomic methylation, and the synthesis of numerous neurochemicals and signaling molecules. However, human epid...

12 CFR 573.12 - Limits on sharing account number information for marketing purposes.

Science.gov (United States)

2010-01-01

... 12 Banks and Banking 5 2010-01-01 2010-01-01 false Limits on sharing account number information..., DEPARTMENT OF THE TREASURY PRIVACY OF CONSUMER FINANCIAL INFORMATION Limits on Disclosures § 573.12 Limits on sharing account number information for marketing purposes. (a) General prohibition on disclosure of...

Evaluación neuroquímica de la neuropatía óptica epidémica

OpenAIRE

González-Quevedo Monteagudo , Alina

2004-01-01

La aparición súbita en Cuba de una epidemia de neuropatía óptica en 1992,desencadenó una serie de investigaciones dirigidas a esclarecer las causas subyacentes. El presente trabajo investigó la participación del balance de aminoácidos sistémicos y en el sistema nervioso, la permeabilidad de la barrera hematoencefálica (BHE) y la neurotoxicidad del metanol en la fisiopatología de la neuropatía óptica epidémica (NOE). Se llevaron a cabo estudios en pacientes con NOE y en un modelo experimental ...

The drift velocity of electrons in carbon dioxide at temperatures between 193 and 573 K

International Nuclear Information System (INIS)

Elford, M.T.; Haddad, G.N.

1980-01-01

The drift velocity of electrons in carbon dioxide has been measured at gas temperatures ranging from 193 to 573 K and at E/N values up to 20 Td at 193 K, 50 Td at 293 K and 40 Td at 573 K. The measured drift velocities were found to decrease linearly with increasing gas number density at a given value of E/N for gas temperatures less than 293 K. This dependence has been attributed to multiple scattering and the data have been extrapolated to zero number density to correct for this effect. Comparisons are made with previous measurements where available. The present data for the variation of μN(thermal) with temperature agree to within the experimental error with the data of Pact et al. (1962)

Estimating output fluence with MCNP4 for shaped fields and their comparison with measurements in the EPID system aS1000 for dosimetry 2D in-vivo; Estimacion de la fluencia de salida con MCNP4 para campos conformados y su comparacion con mediciones en el sistema EPID aS1000 para dosimetria in-vivo 2D

Energy Technology Data Exchange (ETDEWEB)

Hernandez R, B.; Rodriguez P, X.; Sosa, M., E-mail: bhernandez@fisica.ugto.mx [Universidad de Guanajuato, Division de Ciencias e Ingenierias, Loma del Bosque No. 103, 37150 Leon, Guanajuato (Mexico)

2015-10-15

Full text: Radiotherapy dosimetry is a fundamental process in quality control of the treatments performed with this technique. Different systems exist to quantify radiation dose in radiotherapy, one of them is the Electronic Portal Imaging Device (EPID), which is widely used in IMRT to measure the output fluence of a radiation field for comparison with a predicted fluence in a planning system. The objective of this work was to simulate a Varian linear accelerator model Clinac i X using the MCNP4 code for obtaining curves of percentage depth dose (Pdd) and open fields dosimetric profiles of 5 x 5, 10 x 10, 20 x 20 and 30 x 30 cm{sup 2}. The simulations were validated by comparing them with measurements made with ionization chamber. Then a mannequin of solid water (30 x 30 x 20 cm{sup 3}) with an open field of 10 x 10 cm{sup 2} was irradiated to measure the output fluence with EPID aS1000 system of Varian. A simulation of the solid water mannequin under the same conditions of irradiation was conducted to estimate the output fluence. Tests of index gamma and percentage differences were calculated to compare that simulated with that measured. In all cases was found that more than 95% of the evaluated points passed the acceptance criteria (ΔD= 1% and ΔS= 1 mm for curves Pdd and profiles, and ΔD= 3% and ΔS= 3 mm for fluence two-dimensional). This paper will contribute to the implementation of in-vivo dosimetry three-dimensional with the EPID system. (Author)

Laminite experimental: aspectos morfológicos, morfométricos e ultra-estruturais das lâminas dérmicas e epidérmicas do casco de eqüinos tratados com a trinitroglicerina

OpenAIRE

Sampaio, Rita de Cássia de Lima [UNESP

2007-01-01

As alterações ultra-estruturais ocorridas nas lâminas epidérmicas e dérmicas de eqüinos com laminite são responsáveis pela rotação ou afundamento da falange distal dentro do casco. Com o objetivo de prevenir esta ocorrência foram estudados os efeitos da sobrecarga de carboidratos (SCHO), assim como da utilização de trinitroglicerina na fase prodrômica da laminite, nas lâminas epidérmicas do casco de quinze eqüinos. A indução da laminite por meio da sobrecarga de carboidratos alterou siginific...

SU-F-J-41: Experimental Validation of a Cascaded Linear System Model for MVCBCT with a Multi-Layer EPID

Energy Technology Data Exchange (ETDEWEB)

Hu, Y; Rottmann, J; Myronakis, M; Berbeco, R [Department of Radiation Oncology, Brigham and Women’s Hospital, Dana Farber Cancer Institute and Harvard Medical School, Boston, MA. (United States); Fueglistaller, R; Morf, D [Varian Medical Systems, Dattwil, Aargau (Switzerland); Wang, A; Shedlock, D; Star-Lack, J [Varian Medical Systems, Palo Alto, CA (United States)

2016-06-15

Purpose: The purpose of this study was to validate the use of a cascaded linear system model for MV cone-beam CT (CBCT) using a multi-layer (MLI) electronic portal imaging device (EPID) and provide experimental insight into image formation. A validated 3D model provides insight into salient factors affecting reconstructed image quality, allowing potential for optimizing detector design for CBCT applications. Methods: A cascaded linear system model was developed to investigate the potential improvement in reconstructed image quality for MV CBCT using an MLI EPID. Inputs to the three-dimensional (3D) model include projection space MTF and NPS. Experimental validation was performed on a prototype MLI detector installed on the portal imaging arm of a Varian TrueBeam radiotherapy system. CBCT scans of up to 898 projections over 360 degrees were acquired at exposures of 16 and 64 MU. Image volumes were reconstructed using a Feldkamp-type (FDK) filtered backprojection (FBP) algorithm. Flat field images and scans of a Catphan model 604 phantom were acquired. The effect of 2×2 and 4×4 detector binning was also examined. Results: Using projection flat fields as an input, examination of the modeled and measured NPS in the axial plane exhibits good agreement. Binning projection images was shown to improve axial slice SDNR by a factor of approximately 1.4. This improvement is largely driven by a decrease in image noise of roughly 20%. However, this effect is accompanied by a subsequent loss in image resolution. Conclusion: The measured axial NPS shows good agreement with the theoretical calculation using a linear system model. Binning of projection images improves SNR of large objects on the Catphan phantom by decreasing noise. Specific imaging tasks will dictate the implementation image binning to two-dimensional projection images. The project was partially supported by a grant from Varian Medical Systems, Inc. and grant No. R01CA188446-01 from the National Cancer Institute.

Accelerated test techniques for micro-circuits: Evaluation of high temperature (473 k - 573 K) accelerated life test techniques as effective microcircuit screening methods

Science.gov (United States)

Johnson, G. M.

1976-01-01

The application of high temperature accelerated test techniques was shown to be an effective method of microcircuit defect screening. Comprehensive microcircuit evaluations and a series of high temperature (473 K to 573 K) life tests demonstrated that a freak or early failure population of surface contaminated devices could be completely screened in thirty two hours of test at an ambient temperature of 523 K. Equivalent screening at 398 K, as prescribed by current Military and NASA specifications, would have required in excess of 1,500 hours of test. All testing was accomplished with a Texas Instruments' 54L10, low power triple-3 input NAND gate manufactured with a titanium- tungsten (Ti-W), Gold (Au) metallization system. A number of design and/or manufacturing anomalies were also noted with the Ti-W, Au metallization system. Further study of the exact nature and cause(s) of these anomalies is recommended prior to the use of microcircuits with Ti-W, Au metallization in long life/high reliability applications. Photomicrographs of tested circuits are included.

Human immunodeficiency virus/human parvovirus B19 co-infection in blood donors and AIDS patients in Sichuan, China

Science.gov (United States)

He, Miao; Zhu, Jiang; Yin, Huimin; Ke, Ling; Gao, Lei; Pan, Zhihong; Yang, Xiuhua; Li, Wuping

2012-01-01

Background Human parvovirus B19 (B19) is a common pathogen which causes a variety of diseases. Persistent B19 infection is related to the degree of host immunodeficiency in patients with human immunodeficiency virus (HIV) infection. However, the existence, loading, virus evolution and distribution of B19 in Chinese HIV-positive patients have not been determined. Materials and methods. We investigated 573 HIV-positive blood donors and AIDS patients in Sichuan, China in the last two decades. Bl9-specific serology and quantitative polymerase chain reaction were used to determine the prevalence of B19/HIV co-infection. Viral genome fragments were subjected to phylogeny and haplotype analysis. Results B19 genomic DNA was found in 26 of 573 (4.5%) HIV-positive individuals, a higher prevalence than in blood donors. DNA levels ranged from 5.3×102–1.1×105 copies/mL. The seroprevalence of IgG was significantly lower in HIV-positive samples than in HIV-negative blood donors, indicating deficient production of B19-specific IgG in the former. The B19 isolates were genotype-1 subtype B19-1A which formed a monophyletic group; seven distinct haplotypes were discovered with 60% of the B19/HIV co-infected variants sharing one central haplotype. Discussion. This study on the prevalence, phylogeny and distribution of human parvovirus B19 in Sichuan, China, demonstrates the persistence of B19 in the circulation of both immunocompetent and immunocompromised subjects, with implications for blood safety. PMID:22790259

Epidermal growth factor enemas for induction of remission in left-sided ulcerative colitis Enemas de factor de crecimiento epidérmico para inducir la remisión de la colitis ulcerosa izquierda

Directory of Open Access Journals (Sweden)

Hugo Nodarse-Cuní

2013-03-01

Full Text Available Introduction: ulcerative colitis is a little known chronic inflammatory disease in colonic mucosa. The positive effect of epidermal growth factor was shown in a previous report, with enema use for treatment of mild to moderate left-sided manifestation of the disease. This evidence provided the basis for evaluating the efficacy and safety profile of a viscous solution of this product. Methods: thirty-one patients were randomized to three groups for daily medications during 14 days. Twelve received one 10 mg enema of epidermal growth factor dissolved in 100 mL of viscous solution whereas nine were treated with placebo enema; both groups also received 1.2 g of oral mesalamine per day. The other group included ten patients with 3 g / 100 mL of mesalamine enema. Primary end point was clinical responses after two weeks of treatment, defined as a decreased of, at least three points from baseline, the Disease Activity Index and endoscopic or histological evidences of improvement. Results: remission of disease was observed in all patients in the epidermal growth factor group, and six in both, mesalamine enema and placebo group. All the comparisons between groups showed statistically significant superiority for epidermal growth factor, the only product with significant reduction in disease activity index as well as the presence and intensity of digestive symptoms in patients after treatment. None adverse event was reported. Conclusions: the results agree with previous molecular and clinical evidences, indicating that the epidermal growth factor is effective to reduce disease activity and to induce remission. A new study involving more patients should be conducted to confirm the efficacy of the epidermal growth factor enemas.Introducción: la colitis ulcerosa es una enfermedad inflamatoria crónica de etiología poco conocida, que afecta la mucosa del colon. El efecto positivo del factor de crecimiento epidérmico fue reportado en estudio previo con uso de

Transmission portal in vivo dosimetry by means of the Monte Carlo method and the mathematical programming language MATLAB

International Nuclear Information System (INIS)

BadraouiCuprova, K.

2014-01-01

Modern radiotherapy has increased demand for dose delivery verification. In this paper transmission portal dosimetry was considered. Portal detectors are a promising tool for 2D dosimetric verification and they are nowadays one of the most widely investigated topics. In this study an Electronic Portal Imaging Device (EPID) was positioned below the patient and the transmission images were captured during the irradiation. The principle of this verification consists of comparison of the acquired images with images predicted on the basis of the entrance fluence map and the tissue distribution in the patient. Such verification is not performed at any radiotherapy department in the Czech Republic. There is no system available for the prediction of transmission portal images. Even worldwide, there is still a lack of commercially available solutions. The aim of this paper is to present a new method of prediction of transmission portal images by means of the Monte Carlo (MC) method and the mathematical programming language MATLAB. The MC code EGSnrc (Electron Gamma Shower) was used. The validity of the presented method was verified by comparison of the predicted images with the acquired ones. The acquisition of EPID images was performed at the Hospital Na Bulovce. Three different validation tests were performed. In the first case, the EPID was irradiated by regular and irregular fields while there was nothing present in the beam path. In the second case, a water-equivalent phantom was added to the EPID and was irradiated by a number of irregular fields. In the third case, a real patient was present in the beam path and the EPID images were acquired during the patient's treatment. The patient was irradiated by 8 treatment fields and the portal images were acquired during 5 treatment fractions. All of the acquired images were compared with the MC predicted ones by gamma analysis with gamma criteria of 3%, 3 mm. The average gamma values were 0.31-0.4, 0.34-0.4 and 0.35-0.61 in

Partial molar volumes of organic solutes in water. XXVI. 15-Crown-5 and 18-crown-6 ethers at temperatures (298 to 573) K and pressures up to 30 MPa

International Nuclear Information System (INIS)

Cibulka, Ivan

2015-01-01

Highlights: • Density data were obtained in the range T from (298 to 573) K and p up to 30 MPa. • Standard molar volumes of two crown ethers in water are presented. • Group contribution method was designed to estimate standard molar volumes of cyclic ethers. - Abstract: Densities of dilute aqueous solutions of two cyclic ethers, viz. 15-crown-5 and 18-crown-6, measured over the temperature range from (298 to 573) K and at pressures up to 30 MPa using an automated flow vibrating-tube densimeter are reported. Standard molar volumes were evaluated from the measured data. Present data were combined with those obtained previously for several cyclic ethers and predictions of standard molar volumes based on group contribution approach were tested and analysed

SU-E-J-27: Shifting Multiple EPID Imager Layers to Improve Image Quality and Resolution in MV CBCT

Energy Technology Data Exchange (ETDEWEB)

Chen, H; Rottmann, J; Yip, S; Berbeco, R [Brigham and Women’s Hospital, Boston, Massachusetts (United States); Morf, D; Fueglistaller, R; Star-Lack, J; Zentai, G [Varian Medical Systems, Palo Alto, CA (United States)

2015-06-15

Purpose: Vertical stacking of four conventional EPID layers can improve DQE for MV-CBCT applications. We hypothesize that shifting each layer laterally by half a pixel relative to the layer above, will improve the contrast-to-noise ratio (CNR) and image resolution. Methods: For CNR assessment, a 20 cm diameter digital phantom with 8 inserts is created. The attenuation coefficient of the phantom is similar to lung at the average energy of a 6 MV photon beam. The inserts have attenuations 1, 2…8 times of lung. One of the inserts is close to soft tissue, resembling the case of a tumor in lung. For resolution assessment, a digital phantom featuring a bar pattern is created. The phantom has an attenuation coefficient similar to soft tissue and the bars have an attenuation coefficient of calcium sulfate. A 2 MeV photon beam is attenuated through these phantoms and hits each of the four stacked detector layers. Each successive layer is shifted by half a pixel in the x only, y only, and x and y (combined) directions, respectively. Blurring and statistical noise are added to the projections. Projections from one, two, three and four layers are used for reconstruction. CNR and image resolution are evaluated and compared. Results: When projections from multiple layers are combined for reconstruction, CNR increases with the number of layers involved. CNR in reconstructions from two, three and four layers are 1.4, 1.7 and 1.99 times that from one layer. The resolution from the shifted four layer detector is also improved from a single layer. In a comparison between one layer versus four layers in this preliminary study, the resolution from four shifted layers is at least 20% better. Conclusion: Layer-shifting in a stacked EPID imager design enhances resolution as well as CNR for half scan MV-CBCT. The project described was supported, in part, by a grant from Varian Medical Systems, Inc., and Award No. R01CA188446-01 from the National Cancer Institute. The content is solely

Partial molar volumes of organic solutes in water. XXIII. Cyclic ketones at T = (298 to 573) K and pressures up to 30 MPa

International Nuclear Information System (INIS)

Cibulka, Ivan; Simurka, Lukas; Hnedkovsky, Lubomir; Bolotov, Alexander

2011-01-01

Research highlights: → In this study we examine standard molar volumes of aqueous cyclic ketones. → State parameters of measurements were (298 to 573) K and pressures up to 30 MPa. → Differences in behavior of monoketones and cyclohexane-1,4-dione were observed. → Group contribution method was designed and examined. - Abstract: Density data for dilute aqueous solutions of four cyclic ketones (cyclopentanone, cyclohexanone, cycloheptanone, and cyclohexane-1,4-dione) are presented together with standard molar volumes (partial molar volumes at infinite dilution) calculated from the experimental data. The measurements were performed at temperatures from T = 298 K up to T = 573 K. Experimental pressures were close to the saturated vapor pressure of water, and (15 and 30) MPa. The data were obtained using a high-temperature high-pressure flow vibrating-tube densimeter. Experimental standard molar volumes were correlated as a function of temperature and pressure using an empirical polynomial function. Contributions of the molecular structural segments (methylene and carbonyl groups) to the standard molar volume were also evaluated and analyzed.

Estudio de un brote epidémico de tos ferina en Castellón

Directory of Open Access Journals (Sweden)

González Morán Francisco

2002-01-01

Full Text Available Fundamento: A partir de la declaración de varios casos en un centro escolar se inicia el estudio de brote con el objetivo de caracterizar éste desde el punto de vista de persona, lugar y tiempo; se calcula la efectividad de la vacuna, y se estudia la concordancia entre los casos y el resultado positivo del estudio serológico. Métodos: Se define caso a la persona que presenta tos persistente de dos semanas de duración. Se realiza estudio de la difusión de la enfermedad a través de la curva epidémica, y de la efectividad de la dosis de refuerzo de la vacuna antipertussis. La concordancia entre los casos y la serología positiva se evalúa por el índice Kappa. Resultados: Entre los alumnos de varios centros escolares y sus convivientes se encuesta a 130 personas, de los que 94 entran en la definición de caso. La media de edad de los casos es 10,5 años, un 42,6% son varones, el 84% escolares, el 71,3% muestra signos de infección reciente (IgM positiva, y el tiempo medio desde la última dosis de vacuna antipertussis es de 8,25 años. La efectividad de la dosis de refuerzo de la vacuna es del 66%. La concordancia entre los casos y el resultado positivo de la serología muestra un Kappa igual a 0,45. No se aisló B. Pertussis en las 25 muestras de frotis faríngeo. Conclusiones: Las aulas y el medio familiar son un factor de difusión de la enfermedad. La inclusión de una dosis de refuerzo a los 18 meses mejora la efectividad de la vacuna antipertussis. El aislamiento de la B. Pertussis es poco frecuente, y la serología, puede ser una alternativa ante la sospecha clínica de la enfermedad.

SU-E-J-64: Evaluation of a Commercial EPID-Based in Vivo Dosimetric System in the Presence of Lung Tissue Heterogeneity

Energy Technology Data Exchange (ETDEWEB)

Gimeno-Olmos, J; Palomo-Llinares, R; Candela-Juan, C; Carmona Meseguer, V; Lliso-Valverde, F [Hospital Universitari i Politecnic La Fe, Valencia, Valencia (Spain); Garcia-Martinez, T [Hospital de la Ribera, Alzira, Valencia (Spain); Richart-Sancho, J [Clinica Benidorm, Benidorm, Alicante (Spain); Ballester, F [University of Valencia, Burjassot (Spain); Perez-Calatayud, J [Hospital Universitari i Politecnic La Fe, Valencia, Valencia (Spain); Clinica Benidorm, Benidorm, Alicante (Spain)

2014-06-01

Purpose: To study the performance of Dosimetry Check (DC), an EPID-based dosimetry software, which allows performing transit dosimetry, in low density medium, by comparing calculations in-phantom, and analysing results for 15 lung patients. Methods: DC software (v.3.8, pencil beam-based algorithm) has been tested, for plans (Eclipse v.10.0 TPS) delivered in two Varian Clinac iX equipped with aS1000 EPIDs.In the CIRS lung phantom, comparisons between DC and Eclipse (Acuros) were performed for several plans: (1) four field box; (2) square field delivered in arc mode; (3) RapidArc lung patient plan medially centred; (4) RapidArc lung patient plan centred in one lung. Reference points analysed: P1 (medial point, plans 1–3) and P2 (located inside one lung, plan 4).For fifteen lung patients treated with RapidArc, the isocentre and 9 additional points inside the PTV as well as the gamma passing rate (3%/3mm) for the PTV and at the main planes were studied. Results: In-phantom:P1: Per-field differences in plan 1: good agreement for AP-PA fields; discrepancy of 7% for the lateral fields. Global differences (plans 1–3): about 4%, showing a compensating effect of the individual differences.P2: Global difference (plan 4): 15 %. This represents the worst case situation as it is a point surrounded by lung tissue, where the DC pencil beam algorithm is expected to give the greater difference against Acuros.Lung patients: Mean point difference inside the PTV:(5.4±4.2) %. Gamma passing rate inside the PTV:(45±12) %. Conclusion: The performance of DC in heterogeneous lung medium was studied with a special phantom and the results for 15 patients were analysed. The found deviations show that even though DC is a highly promising in vivo dosimetry tool, there is a need of incorporating a more accurate algorithm mainly for plans with low density regions involved.

Narrativa epidémica. La construcción social de las crisis sanitarias en la ficción literaria

OpenAIRE

Nespereira García, Javier

2015-01-01

Las crisis sanitarias de las últimas décadas han sido al mismo tiempo crisis mediáticas, históricas y socioculturales. En este contexto, numerosos autores han señalado la importancia de las narrativas de ficción en la transformación y transmisión de los valores morales e ideológicos implicados. En el siguiente trabajo presentamos el estudio comparativo de dos obras de ficción narrativa literaria en las que el relato se estructura en torno a la gestión de una crisis epidémica...

Detección del receptor de factor de crecimiento epidérmico en lesiones orales premalignas por relaxometría

OpenAIRE

Alonso Geli, Yamirka; De la Cruz, Enrique Reynaldo; Dutok Sánchez, Carlos M.; Álvarez Guerra, Eloy D

2014-01-01

Objetivo: detectar la sobreexpresión del receptor de factor de crecimiento epidérmico en células epiteliales de lesiones premalignas de la mucosa bucal, marcadas magnéticamente por relaxometría. Métodos: las células exfoliadas de mucosa oral de individuos sanos y enfermos se marcaron con el sistema: IgG anti-EGF-R biotinilada/IgG anti-biotina conjugada con partículas superparamagnéticas y se midieron los tiempos de relajación T1 y T2. Resultados: disminuyeron los tiempos de relajación (T1 y T...

aSi EPIDs for the in-vivo dosimetry of static and dynamic beams

Science.gov (United States)

Piermattei, A.; Cilla, S.; Azario, L.; Greco, F.; Russo, M.; Grusio, M.; Orlandini, L.; Fidanzio, A.

2015-10-01

Portal imaging by amorphous silicon (aSi) photodiode is currently the most applied technology for in-vivo dosimetry (IVD) of static and dynamic radiotherapy beams. The strategy, adopted in this work to perform the IVD procedure by aSi EPID, is based on: in patient reconstruction of the isocenter dose and day to day comparison between 2D-portal images to verify the reproducibility of treatment delivery. About 20.000 tests have been carried out in this last 3 years in 8 radiotherapy centers using the SOFTDISO program. The IVD results show that: (i) the procedure can be implemented for linacs of different manufacturer, (ii) the IVD analysis can be obtained on a computer screen, in quasi real time (about 2 min after the treatment delivery) and (iii) once the causes of the discrepancies were eliminated, all the global IVD tests for single patient were within the acceptance criteria defined by: ±5% for the isocenter dose, and PγFisica Nucleare (INFN) and Università Cattolica del S.Cuore (UCSC).

Hiperplasia de Músculo Liso no Epidídimo: Revisão de Literatura/Smooth Muscle Hyperplasia of the Epididymis: A Literature Review

Directory of Open Access Journals (Sweden)

Ana Cecília Vieira Lisboa

2014-12-01

Full Text Available O epidídimo pode ser acometido por hiperplasia ou neoplasia, benigna ou maligna, sempre diferenciadas pelo estudo histopatológico. Ele tem como função coletar, amadurecer e armazenar espermatozóides constantemente produzidos pelos túbulos seminíferos. Patologias do epidídimo acometem homens na puberdade, o que pode resultar em alterações na maturação dos espermatozóides e até mesmo levar a infertilidade. A conduta dessa afecção é cirúrgica e pode ser desde ressecção da tumoração preservando-se estruturas hígidas como, por exemplo, os testículos, em casos benignos, até exploração peritoneal para esvaziamento linfonodal mais orquiectomia, em casos malignos. O objetivo foi realizar uma revisão de literatura sobre hiperplasia do epidídimo que auxilie no diagnóstico e tratamento precoces que diminuam a mortalidade, morbidade e sequelas dos pacientes. Como a patologia em questão tem baixa incidência, com predomínio de casos benignos e evolução sem complicações, conclui-se que há a necessidade de mais análises sobre o tema para melhor elucidar seu tratamento e, principalmente, as consequências. The epididymis may be affected by hyperplasia or neoplastic cells, always differentiated by histopathological study. It has the function of collecting, maturing and storing sperm that are constantly produced by the seminiferous tubules. Pathologies of epididymis affect male puberty, which may result in changes in the maturation of sperm and even lead to infertility. The conduct in this condition can be from a tumor resection preserving healthy structures such as, for example, the testicles, in benign cases, while in malignant cases chooses whether the peritoneal exploration for a lymph node dissection plus orchiectomy. The purpose was to conduct a literature review of hyperplasia of the epididymis that helps in the diagnosis and early treatment, which can lead to lower risk of mortality and morbidity allowing a decrease in

40 CFR 80.573 - What labeling requirements apply to retailers and wholesale purchaser-consumers of NRLM diesel...

Science.gov (United States)

2010-07-01

... (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Motor Vehicle Diesel Fuel; Nonroad, Locomotive, and Marine Diesel Fuel; and ECA Marine Fuel Labeling Requirements § 80.573 What labeling requirements apply to... retailers and wholesale purchaser-consumers of NRLM diesel fuel and heating oil beginning June 1, 2012? 80...

The use of an electronic portal imaging device for exit dosimetry and quality control measurements

International Nuclear Information System (INIS)

Kirby, Michael C.; Williams, Peter C.

1995-01-01

Purpose: To determine ways in which electronic portal imaging devices (EPIDs) could be used to (a) measure exit doses for external beam radiotherapy and (b) perform quality control checks on linear accelerators. Methods and Materials: When imaging, our fluoroscopic EPID adjusts the gain, offset, and frame acquisition time of the charge coupled device (CCD) camera automatically, to allow for the range of photon transmissions through the patient, and to optimize the signal-to-noise ratio. However, our EPID can be programmed to act as an integrating dosemeter. EPID dosemeter measurements were made for 20 MV photons, for different field sizes and thicknesses of unit density phantom material placed at varying exit surface to detector distances. These were compared with simultaneous Silicon diode exit dose measurements. Our exit dosimetry technique was verified using an anthropomorphic type phantom, and some initial measurements have been made for patients treated with irregularly shaped 20 MV x-ray fields. In this dosimetry mode, our EPID was also used to measure certain quality control parameters, x-ray field flatness, and the verification of segmented intensity modulated field prescriptions. Results: Configured for dosimetry, our EPID exhibited a highly linear response, capable of resolving individual monitor units. Exit doses could be measured to within about 3% of that measured using Silicon diodes. Field flatness was determined to within 1.5% of Farmer dosemeter measurements. Segmented intensity modulated fields can be easily verified. Conclusions: Our EPID has the versatility to assess a range of parameters pertinent to the delivery of high quality, high precision radiotherapy. When configured appropriately, it can measure exit doses in vivo, with reasonable accuracy, perform certain quick quality control checks, and analyze segmented intensity modulated treatment fields

B-spline Collocation with Domain Decomposition Method

International Nuclear Information System (INIS)

Hidayat, M I P; Parman, S; Ariwahjoedi, B

2013-01-01

A global B-spline collocation method has been previously developed and successfully implemented by the present authors for solving elliptic partial differential equations in arbitrary complex domains. However, the global B-spline approximation, which is simply reduced to Bezier approximation of any degree p with C 0 continuity, has led to the use of B-spline basis of high order in order to achieve high accuracy. The need for B-spline bases of high order in the global method would be more prominent in domains of large dimension. For the increased collocation points, it may also lead to the ill-conditioning problem. In this study, overlapping domain decomposition of multiplicative Schwarz algorithm is combined with the global method. Our objective is two-fold that improving the accuracy with the combination technique, and also investigating influence of the combination technique to the employed B-spline basis orders with respect to the obtained accuracy. It was shown that the combination method produced higher accuracy with the B-spline basis of much lower order than that needed in implementation of the initial method. Hence, the approximation stability of the B-spline collocation method was also increased.

Use of the statistical control of processes through checking before treatment realised with the ionization chamber and by electronic portal system of imaging (E.P.I.D.) in intensity modulated radiotherapy (I.M.R.T.); Utilisation de la maitrise statistique des processus dans le cadre des controles avant traitement realises avec la chambre d'ionisation et par systeme d'imagerie portale electronique (EPID) en radiotherapie conformationnelle avec modulation d'intensite (RCMI)

Energy Technology Data Exchange (ETDEWEB)

Villani, N.; Gerard, K.; Noel, A. [Nancy univ., Lab. de Recherche en Radiophysique, CRAN UMR 7039, CNRS, Centre Alexis-Vautrin, 54 - Vandoeuvre-les-Nancy (France); Marchesi, V.; Huger, S. [Centre Alexis-Vautrin, Unite de Radiophysique Medicale, 54 - Vandoeuvre-les-Nancy (France)

2009-10-15

The expected results are to demonstrate that it is possible to reduce the times devoted to the pre-treatment controls, while keeping an optimal safety, on substituting the measures of the ionization chamber by this one of the electronic portal imaging device (E.P.I.D.). (N.C.)

Factores de riesgo asociados a infección aguda por hepatitis B en población militar destacada al departamento de Amazonas, Perú

OpenAIRE

César Cabezas; J. Jaime Miranda; Giovana Romero; Magna Suáre; Frine Samalvides; Juan Echevarría; Juan D. Valdivia; Walter A. Valdivia

2007-01-01

El Perú es considerado un país de endemicidad intermedia-alta para el virus de hepatitis B (VHB), con variaciones entre diferentes regiones. Existen pocos reportes del problema de infección por el VHB en personal militar. Objetivos. Determinar los factores de riesgo asociados con el desarrollo de infección por el VHB en un brote epidémico en personal militar destacado en Ampama, Amazonas, Perú. Material y métodos. Estudio caso-control en personal militar destacado al puesto de Ampama y a la b...

26 CFR 1.167(b)-4 - Other methods.

Science.gov (United States)

2010-04-01

... 26 Internal Revenue 2 2010-04-01 2010-04-01 false Other methods. 1.167(b)-4 Section 1.167(b)-4...) INCOME TAXES (CONTINUED) Itemized Deductions for Individuals and Corporations § 1.167(b)-4 Other methods. (a) Under section 167(b)(4) a taxpayer may use any consistent method of computing depreciation, such...

Investigation of the mechanical performance of Siemens linacs components during arc: gantry, MLC, and electronic portal imaging device.

Science.gov (United States)

Rowshanfarzad, Pejman; Häring, Peter; Riis, Hans L; Zimmermann, Sune J; Ebert, Martin A

2015-01-01

In radiotherapy treatments, it is crucial to monitor the performance of linac components including gantry, collimation system, and electronic portal imaging device (EPID) during arc deliveries. In this study, a simple EPID-based measurement method is suggested in conjunction with an algorithm to investigate the stability of these systems at various gantry angles with the aim of evaluating machine-related errors in treatments. The EPID sag, gantry sag, changes in source-to-detector distance (SDD), EPID and collimator skewness, EPID tilt, and the sag in leaf bank assembly due to linac rotation were separately investigated by acquisition of 37 EPID images of a simple phantom with five ball bearings at various gantry angles. A fast and robust software package was developed for automated analysis of image data. Three Siemens linacs were investigated. The average EPID sag was within 1 mm for all tested linacs. Two machines showed >1 mm gantry sag. Changes in the SDD values were within 7.5 mm. EPID skewness and tilt values were <1° in all machines. The maximum sag in leaf bank assembly was <1 mm. The method and software developed in this study provide a simple tool for effective investigation of the behavior of Siemens linac components with gantry rotation. Such a comprehensive study has been performed for the first time on Siemens machines.

Mannitol production by heterofermentative Lactobacillus reuteri CRL 1101 and Lactobacillus fermentum CRL 573 in free and controlled pH batch fermentations.

Science.gov (United States)

Rodríguez, Cecilia; Rimaux, Tom; Fornaguera, María José; Vrancken, Gino; de Valdez, Graciela Font; De Vuyst, Luc; Mozzi, Fernanda

2012-03-01

Certain lactic acid bacteria, especially heterofermentative strains, are capable to produce mannitol under adequate culture conditions. In this study, mannitol production by Lactobacillus reuteri CRL 1101 and Lactobacillus fermentum CRL 573 in modified MRS medium containing a mixture of fructose and glucose in a 6.5:1.0 ratio was investigated during batch fermentations with free pH and constant pH 6.0 and 5.0. Mannitol production and yields were higher under constant pH conditions compared with fermentations with free pH, the increase being more pronounced in the case of the L. fermentum strain. Maximum mannitol production and yields from fructose for L. reuteri CRL 1101 (122 mM and 75.7 mol%, respectively) and L. fermentum CRL 573 (312 mM and 93.5 mol%, respectively) were found at pH 5.0. Interestingly, depending on the pH conditions, fructose was used only as an alternative external electron acceptor or as both electron acceptor and energy source in the case of the L. reuteri strain. In contrast, L. fermentum CRL 573 used fructose both as electron acceptor and carbon source simultaneously, independently of the pH value, which strongly affected mannitol production by this strain. Studies on the metabolism of these relevant mannitol-producing lactobacilli provide important knowledge to either produce mannitol to be used as food additive or to produce it in situ during fermented food production.

Investigation of the mechanical performance of Siemens linacs components during arc: gantry, MLC, and electronic portal imaging device

Directory of Open Access Journals (Sweden)

Rowshanfarzad P

2015-11-01

Full Text Available Pejman Rowshanfarzad,1 Peter Häring,2 Hans L Riis,3 Sune J Zimmermann,3 Martin A Ebert1,4 1School of Physics, The University of Western Australia, Crawley, WA, Australia; 2German Cancer Research Center (DKFZ, Medical Physics in Radiation Oncology, Heidelberg, Germany; 3Radiofysisk Laboratorium, Odense University Hospital, Odense C, Denmark; 4Department of Radiation Oncology, Sir Charles Gairdner Hospital, Nedlands, WA, Australia Background: In radiotherapy treatments, it is crucial to monitor the performance of linac components including gantry, collimation system, and electronic portal imaging device (EPID during arc deliveries. In this study, a simple EPID-based measurement method is suggested in conjunction with an algorithm to investigate the stability of these systems at various gantry angles with the aim of evaluating machine-related errors in treatments. Methods: The EPID sag, gantry sag, changes in source-to-detector distance (SDD, EPID and collimator skewness, EPID tilt, and the sag in leaf bank assembly due to linac rotation were separately investigated by acquisition of 37 EPID images of a simple phantom with five ball bearings at various gantry angles. A fast and robust software package was developed for automated analysis of image data. Three Siemens linacs were investigated. Results: The average EPID sag was within 1 mm for all tested linacs. Two machines showed >1 mm gantry sag. Changes in the SDD values were within 7.5 mm. EPID skewness and tilt values were <1° in all machines. The maximum sag in leaf bank assembly was <1 mm. Conclusion: The method and software developed in this study provide a simple tool for effective investigation of the behavior of Siemens linac components with gantry rotation. Such a comprehensive study has been performed for the first time on Siemens machines. Keywords: linac, Siemens, arc, sag, EPID, gantry

Reliable detection of fluence anomalies in EPID-based IMRT pretreatment quality assurance using pixel intensity deviations

International Nuclear Information System (INIS)

Gordon, J. J.; Gardner, J. K.; Wang, S.; Siebers, J. V.

2012-01-01

Purpose: This work uses repeat images of intensity modulated radiation therapy (IMRT) fields to quantify fluence anomalies (i.e., delivery errors) that can be reliably detected in electronic portal images used for IMRT pretreatment quality assurance. Methods: Repeat images of 11 clinical IMRT fields are acquired on a Varian Trilogy linear accelerator at energies of 6 MV and 18 MV. Acquired images are corrected for output variations and registered to minimize the impact of linear accelerator and electronic portal imaging device (EPID) positioning deviations. Detection studies are performed in which rectangular anomalies of various sizes are inserted into the images. The performance of detection strategies based on pixel intensity deviations (PIDs) and gamma indices is evaluated using receiver operating characteristic analysis. Results: Residual differences between registered images are due to interfraction positional deviations of jaws and multileaf collimator leaves, plus imager noise. Positional deviations produce large intensity differences that degrade anomaly detection. Gradient effects are suppressed in PIDs using gradient scaling. Background noise is suppressed using median filtering. In the majority of images, PID-based detection strategies can reliably detect fluence anomalies of ≥5% in ∼1 mm 2 areas and ≥2% in ∼20 mm 2 areas. Conclusions: The ability to detect small dose differences (≤2%) depends strongly on the level of background noise. This in turn depends on the accuracy of image registration, the quality of the reference image, and field properties. The longer term aim of this work is to develop accurate and reliable methods of detecting IMRT delivery errors and variations. The ability to resolve small anomalies will allow the accuracy of advanced treatment techniques, such as image guided, adaptive, and arc therapies, to be quantified.

Virtual patient 3D dose reconstruction using in air EPID measurements and a back-projection algorithm for IMRT and VMAT treatments.

Science.gov (United States)

Olaciregui-Ruiz, Igor; Rozendaal, Roel; van Oers, René F M; Mijnheer, Ben; Mans, Anton

2017-05-01

At our institute, a transit back-projection algorithm is used clinically to reconstruct in vivo patient and in phantom 3D dose distributions using EPID measurements behind a patient or a polystyrene slab phantom, respectively. In this study, an extension to this algorithm is presented whereby in air EPID measurements are used in combination with CT data to reconstruct 'virtual' 3D dose distributions. By combining virtual and in vivo patient verification data for the same treatment, patient-related errors can be separated from machine, planning and model errors. The virtual back-projection algorithm is described and verified against the transit algorithm with measurements made behind a slab phantom, against dose measurements made with an ionization chamber and with the OCTAVIUS 4D system, as well as against TPS patient data. Virtual and in vivo patient dose verification results are also compared. Virtual dose reconstructions agree within 1% with ionization chamber measurements. The average γ-pass rate values (3% global dose/3mm) in the 3D dose comparison with the OCTAVIUS 4D system and the TPS patient data are 98.5±1.9%(1SD) and 97.1±2.9%(1SD), respectively. For virtual patient dose reconstructions, the differences with the TPS in median dose to the PTV remain within 4%. Virtual patient dose reconstruction makes pre-treatment verification based on deviations of DVH parameters feasible and eliminates the need for phantom positioning and re-planning. Virtual patient dose reconstructions have additional value in the inspection of in vivo deviations, particularly in situations where CBCT data is not available (or not conclusive). Copyright © 2017 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

Mathematical methods for B0 anti B0 oscillation analyses

International Nuclear Information System (INIS)

Moser, H.G.; Roussarie, A.

1996-01-01

The measurement of the B 0 s anti B 0 s mixing frequency Δm s requires the search for a periodic pattern in the time distribution of the data. Using Fourier analysis the consequences of vertex and boost resolution, mistag and statistical fluctuations are treated analytically and a general expression to estimate the significance of a B 0 anti B 0 mixing analysis is derived. With the help of Fourier analysis the behaviour of a classical maximum likelihood analysis in time space is studied, too. It can be shown that a naive maximum likelihood fit fails in general to give correct confidence levels. This is especially important if limits are calculated. Alternative methods, based on the likelihood, which give correct limits are discussed. A new method, the amplitude fit, is introduced which combines the advantages of a Fourier analysis with the power and simplicity of a maximum likelihood fit. (orig.)

Brote epidémico de neumonías por Legionella pneumophila en niños cubanos

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Roberto Razón Behar

2002-09-01

Full Text Available La Legionella pneumophila es uno de los patógenos responsable de neumonías atípicas, a través de la inhalación de aerosoles o aspiración de líquidos infectados. Se detectó un brote epidémico de neumonías por Legionella, originado por la aspiración de agua contaminada de una piscina en un grupo de niños cubanos. El agente causal se identificó en 5 de 9 pacientes, por la técnica de inmunofluorescencia indirecta en muestras de sueros pareados. Los síntomas y signos más frecuentes fueron malestar general, anorexia, astenia, fiebre persistente de 39 °C a 40 °C (103 °F a 105 °F, mialgias, cefaleas, náuseas, vómitos, dolor abdominal, diarreas, tos húmeda, dolor torácico y polipnea. Durante el desarrollo de la enfermedad, el tratamiento antibiótico fue empírico (incluyendo los macrólidos, por no tener confirmado el diagnóstico. Todos los pacientes evolucionaron satisfactoriamente. Se reportó un brote epidémico de neumonías por Legionella en niños por primera vez en Cuba, lo cual tiene importancia clínica y epidemiológica.The legionella pneumophila is one of the pathogens responsible for atypic pneumonias by the inhalation of aerosols or aspiration of infected liquids. An epidemic outbreak of pneumonias caused by Legionella was detected among a group of Cuban children. It was originated by the aspiration of contaminated water in a swimming pool. The causal agent was identified in 5 of 9 patients by using the indirect immunofluorescence technique in samples of matched sera. The most frequent symptoms and signs were malaise, anorexia, asthenia, persistent fever from 39°C to 40°C (103° F to 105° F, myalgias, headache, nauseas, vomits, abdominal pain, diarrheas, moist cough, thoracic pain and polypnoea. The antibiotic treatment was empiric (including the macrolides during the development of the disease, since the diagnosis was not confirmed. The patients’ evolution was satisfactory. An epidemic outbreak of pneumonias

Tipificación molecular del virus dengue 3 durante el brote epidémico de dengue clásico en Lima, Perú, 2005

Directory of Open Access Journals (Sweden)

Enrique Mamani Z

2005-07-01

Full Text Available Objetivos: Identificar mediante trascripción reversa-reacción en cadena de la polimerasa (RT-PCR y sitios específicos de restricción - reacción en cadena de la polimerasa (RSS-PCR al agente causal del brote epidémico presentado en el distrito de Comas, Lima en abril del año 2005. Materiales y métodos: veinte muestras de suero colectadas durante el brote de dengue fueron procesados por RT-PCR para determinar el serotipo, esta técnica se realizó en un solo paso. Luego se aplicó la técnica RSS-PCR para la identificación del genotipo circulante y se corroboraron los resultados posteriormente con aislamiento viral y secuenciamiento. Resultados: El análisis del RTPCR del ARN extraído de las muestras presentó un producto amplificado de 290pb que corresponden al dengue serotipo 3 (DEN 3. El análisis de los productos de RSS-PCR del ARN extraído a partir de aislamientos de DEN 3 correspondió al patrón C, incluido en el genotipo III. Los aislamientos de los virus dengue 3 en líneas celulares C6/36, tipificadas por IFI y el secuenciamiento genético confirmaron los resultados obtenidos por las pruebas previamente descritas. Conclusión: Durante el brote epidémico de dengue clásico en Lima, circuló el genotipo III del virus DEN 3.

SIFT: A method to verify the IMRT fluence delivered during patient treatment using an electronic portal imaging device

International Nuclear Information System (INIS)

Vieira, Sandra C.; Dirkx, Maarten L.P.; Heijmen, Ben J.M.; Boer, Hans C.J. de

2004-01-01

Purpose: Radiotherapy patients are increasingly treated with intensity-modulated radiotherapy (IMRT) and high tumor doses. As part of our quality control program to ensure accurate dose delivery, a new method was investigated that enables the verification of the IMRT fluence delivered during patient treatment using an electronic portal imaging device (EPID), irrespective of changes in patient geometry. Methods and materials: Each IMRT treatment field is split into a static field and a modulated field, which are delivered in sequence. Images are acquired for both fields using an EPID. The portal dose image obtained for the static field is used to determine changes in patient geometry between the planning CT scan and the time of treatment delivery. With knowledge of these changes, the delivered IMRT fluence can be verified using the portal dose image of the modulated field. This method, called split IMRT field technique (SIFT), was validated first for several phantom geometries, followed by clinical implementation for a number of patients treated with IMRT. Results: The split IMRT field technique allows for an accurate verification of the delivered IMRT fluence (generally within 1% [standard deviation]), even if large interfraction changes in patient geometry occur. For interfraction radiological path length changes of 10 cm, deliberately introduced errors in the delivered fluence could still be detected to within 1% accuracy. Application of SIFT requires only a minor increase in treatment time relative to the standard IMRT delivery. Conclusions: A new technique to verify the delivered IMRT fluence from EPID images, which is independent of changes in the patient geometry, has been developed. SIFT has been clinically implemented for daily verification of IMRT treatment delivery

Environmental Chemistry Methods (ECM) Index - B

Science.gov (United States)

Laboratories use testing methods to identify pesticides in water and soil. Environmental chemistry methods test soil and water samples to determine the fate of pesticides in the environment. Find methods for chemicals with B as the first character.

Using an electronic portal imaging device for exit dose measurements in radiotherapy

International Nuclear Information System (INIS)

Ganowicz, M.; Wozniak, B.; Bekman, A.; Maniakowski, Z.

2003-01-01

To present a method of determining the exit dose with the use of an electronic portal imaging device (EPID). The device used was the Portal Vision LC250 (Varian). The EPID signals on the central beam axis have been related to the exit dose. The exit dose measurements were performed with the ionisation chamber in the slab phantom at the distance of dose maximum from the exit surface of the phantom. EPID reading was investigated as a function of field size, phantom thickness and source-detector distance. The relation between dose rate and the EPID reading is described with empirical functions applicable to the obtained data. The exit dose is calculated from the EPID reading as a product of the calibration factor and appropriate correction factors. The determination of the exit dose rate from the EPID signal requires the knowledge of many parameters and earlier determination of essential characteristics. (author)

Using service design methods for B2b service brand concept development: Case company

OpenAIRE

Molina Escalante, Hugo

2014-01-01

A short time before this study was initiated, a small B2b service company had just began op-erating its business without a brand of it’s own. The company owners were looking to design an innovative brand for their business. The purpose of this thesis was to develop the brand for this service Company in the B2b context, using practical service design and Strategic design research methods. This thesis report represents a framework for developing a B2b service brand using research methods c...

Comparison between Electronic Portal Imaging Devices and ion chamber matrix for intensity-modulated radiotherapy quality assurance; Comparacao entre Dispositivos Eletronicos de Imagens Portais e matriz de camaras de ionizacao para garantia da qualidade de radioterapia de intensidade modulada

Energy Technology Data Exchange (ETDEWEB)

Silveira, Thiago B.; Rosa, Luiz A.R., E-mail: thiago.fisimed@gmail.com [Instituto de Radioprotecao e Dosimetria (IRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil); Lima, Marilia B., E-mail: thiago.fisimed@gmail.com [Instituto Nacional do Cancer (INCA), Rio de Janeiro, RJ (Brazil). Departamento de Fisica Medica

2012-08-15

The treatment with intensity-modulated radiotherapy (IMRT) demands an individual and specific quality assurance procedure. The use of ion chamber matrix is a well establish method to dose distribution verifications, despite the lower spatial resolution. An alternative method arising is the use of the Electronic Portal Imaging Devices (EPIDs). The aim of this paper is to validate the EPID use for quality assurance of IMRT comparing it to the previous method employing an ion chamber matrix. We analyzed 10 treatment planning for different tumor sites and photons energies of the linac Trilogy (Varian Medical Systems). We used Sliding-window IMRT and the measurements were acquired in EPID and in Physikalisch-Technische Werkstaetten (PTW) 2D Array seven29. Two different software were used to analyze the data: Verisoft version 4.0, for Array data; and Eclipse 8.6 with Portal Dosimetry for EPID data. The evaluation of concordance levels between measured and predicted images used the Gamma Index tool with 3% of dose difference and 3 mm of distance to agreement. The EPID showed worse results for approval percentiles, in average 2.17%, and bigger values of average gamma index, although its analysis confirmed the approvals of all planning. This happens because of the better sensitivity generated by the higher spatial resolution of the EPID, 0,784 mm against 1,0 cm of the Array, so it has bigger capacity to identify small dose variations. The EPID, jointly with the Portal Dosimetry, proved to be excellent tools to perform pre-treatment IMRT verifications, providing significant gain in dose distribution analysis. Also, the EPID is easier for positioning, for images manipulation, for data acquisition and analysis and has detection area 60% bigger. (author)

Polystyrene-b-polyethylene oxide block copolymer membranes, methods of making, and methods of use

KAUST Repository

Peinemann, Klaus-Viktor; Karunakaran, Madhavan

2015-01-01

Embodiments of the present disclosure provide for polystyrene-b-polyethylene oxide (PS-b-PEO) block copolymer nanoporous membranes, methods of making a PS-b-PEO block copolymer nanoporous membrane, methods of using PS-b-PEO block copolymer nanoporous membranes, and the like.

Polystyrene-b-polyethylene oxide block copolymer membranes, methods of making, and methods of use

KAUST Repository

Peinemann, Klaus-Viktor

2015-04-16

Embodiments of the present disclosure provide for polystyrene-b-polyethylene oxide (PS-b-PEO) block copolymer nanoporous membranes, methods of making a PS-b-PEO block copolymer nanoporous membrane, methods of using PS-b-PEO block copolymer nanoporous membranes, and the like.

Assay for vitamin B12 absorption and method of making labeled vitamin B12

Science.gov (United States)

Anderson, Peter J [Davis, CA; Dueker, Stephen [Davis, CA; Miller, Joshua [Davis, CA; Green, Ralph [Elmacero, CA; Roth, John [Davis, CA; Carkeet, Colleen [Silver Spring, MD; Buchholz,; Bruce, A [Orinda, CA

2012-06-19

The invention provides methods for labeling vitamin B12 with .sup.14C, .sup.13C, tritium, and deuterium. When radioisotopes are used, the invention provides for methods of labeling B12 with high specific activity. The invention also provides labeled vitamin B12 compositions made in accordance with the invention.

Necrólisis epidérmica tóxica: Descripción de 1 caso

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Odalis Peña Pérez

2001-12-01

Full Text Available Se presenta un caso de necrólisis epidérmica tóxica, enfermedad poco frecuente y con alto índice de mortalidad, en un neonato a término, de madre primigesta, con tiempo de gestación de 39,2 semanas; parto eutócico y apgar 8/9, con un peso corporal de 3 770 que a las 2 horas del nacimiento comenzó con lesiones eritematoampollosas y centro necrótico, que rápidamente evolucionó de forma desfavorable y fallece a las 33 horas de nacido. Se realiza revisión bibliográfica del tema y se emiten comentarios de su probable patogenia.A case of toxic epidermal necrolysis, a rare disease with a high mortality rate, is presented in a term infant of a primigravida with 39.2 weeks of gestation, eutocic delivery, apgar 8/9, and a body weight of 3 770 g, that presented erythematous and ampollous lesions and necrotic center 2 hours after having been delivered and had a fast unfavorable evolution and died 33 hours after birth. A bibliographic review of the topic was made and its probable pathogeny was commented.

Removal of the eye in a tertiary care center of China:a retrospective study on 573 cases in 20 years

Directory of Open Access Journals (Sweden)

Ying Zhang

2015-10-01

Full Text Available AIM:To investigate the original protopathy, direct indications, clinical characteristics, complications of orbit plants and visual conditions of eye enucleation/evisceration.METHODS: A retrospective study of 573 eyes removed (573 inpatients at Ophthalmology Department in a tertiary care center of China from January 1993 to December 2012 was completed.RESULTS:Cases underwent removal of the eye accounted for 2.15% of total ophthalmology inpatients, whose annual frequency declined from 3.80% to 0.52%. There were 167 eyes (29.14% being enucleated and 406 (70.86% eviscerated. Annual proportion of evisceration rose from 16.67% in 1993 to 90.48% in later years. Trauma was the top one (65.62% in original protopathies followed by neoplasm (13.44% and ocular infections (5.76%. Phthisis bulbi (45.20% was the most common direct indication, succeeded by malignant tumor (12.57%, loss/unreconstructed of intraocular tissues due to trauma (11.00%, untreatable inflammation (9.60%, intractable glaucoma (8.55% and sclerocorneal staphyloma (5.24%. Exenteration was underwent in 20 (25.97% cases (40% for recurrent carcinoma. Following evisceration, secondary prosthesis implantation was more and earlier, implant exposure occurred in less but earlier and infection and extraction/exchange of implants were more than those following enucleation. Male, phthisis bulbi, evisceration and secondary implantation meant lower risk of implant exposure; eyes removed within 24h following trauma was an independent risk factor. There were 14.37% of eyes with vision of light perception at least as been removed. In the residual contralateral eyes, low vision accounted 5.58% and blindness 3.14%.CONCLUSION:Ocular trauma, tumor and infections were great threats to eyeball preservation. Early and effective controlling of any original protopathies was vital. Generally evisceration presented more superior and safe outcomes than enucleation did. Visual conditions of the sufferers should be

Entre controversias científico-médicas y movilizaciones populares. Población epidémica y vacunas contra la fiebre hemorrágica argentina 1958-1990

Directory of Open Access Journals (Sweden)

Agnese, Graciela

2013-06-01

Full Text Available The emergence and gradual extension of a new epidemic disease, as it has been the Haemorrhagic Fever Argentina, from the Decade of the ‘ 50s, prompted the medical scientific research with the aim of finding a vaccine. In the period 1959-1990 developed three projects of vaccines with different results. This article aims to consider the behavior assumed by the epidemic population around the three vaccines in response to the tensions that exist between population and physicians and researchers in charge of vaccination campaigns; the struggles between the various scientific groups; the role of the press and the State.La irrupción y la progresiva extensión de una nueva enfermedad epidémica, como ha sido la Fiebre Hemorrágica Argentina, a partir de la década del ’50, impulsó la investigación científica médica con el objetivo fundamental de encontrar una vacuna. En el período 1959-1990 se desarrollaron tres proyectos de vacunas con distintos resultados. El objetivo de este artículo es considerar las conductas asumidas por la población epidémica en torno a las tres vacunas atendiendo a las tensiones existentes entre la población y los médicos e investigadores a cargo de las campañas de vacunación; las pugnas entre los distintos grupos científicos; el rol de la prensa y del estado.

26 CFR 1.167(b)-1 - Straight line method.

Science.gov (United States)

2010-04-01

... 26 Internal Revenue 2 2010-04-01 2010-04-01 false Straight line method. 1.167(b)-1 Section 1.167(b... Straight line method. (a) In general. Under the straight line method the cost or other basis of the... may be reduced to a percentage or fraction. The straight line method may be used in determining a...

GEMINI NEAR INFRARED FIELD SPECTROGRAPH OBSERVATIONS OF THE SEYFERT 2 GALAXY MRK 573: IN SITU ACCELERATION OF IONIZED AND MOLECULAR GAS OFF FUELING FLOWS

Energy Technology Data Exchange (ETDEWEB)

Fischer, Travis C.; Straughn, A. N. [Astrophysics Science Division, Goddard Space Flight Center, Code 665, Greenbelt, MD 20771 (United States); Machuca, C.; Crenshaw, D. M.; Baron, F.; Revalski, M.; Pope, C. L. [Department of Physics and Astronomy, Georgia State University, Astronomy Offices, 25 Park Place, Suite 605, Atlanta, GA 30303 (United States); Diniz, M. R.; Riffel, R. A. [Departamento de Física, Centro de Ciências Naturais e Exatas, Universidade Federal de Santa Maria, 97105-900 Santa Maria, RS (Brazil); Kraemer, S. B. [Institute for Astrophysics and Computational Sciences, Department of Physics, The Catholic University of America, Washington, DC 20064 (United States); Schmitt, H. R. [Naval Research Laboratory, Washington, DC 20375 (United States); Storchi-Bergmann, T., E-mail: travis.c.fischer@nasa.gov [Departamento de Astronomia, Universidade Federal do Rio Grande do Sul, IF, CP 15051, 91501-970 Porto Alegre, RS (Brazil)

2017-01-01

We present near-infrared and optical emission-line and stellar kinematics of the Seyfert 2 galaxy Mrk 573 using the Near-Infrared Field Spectrograph (NIFS) at Gemini North and Dual Imaging Spectrograph at Apache Point Observatory, respectively. By obtaining full kinematic maps of the infrared ionized and molecular gas and stellar kinematics in a ∼700 × 2100 pc{sup 2} circumnuclear region of Mrk 573, we find that kinematics within the Narrow-Line Region are largely due to a combination of both rotation and in situ acceleration of material originating in the host disk. Combining these observations with large-scale, optical long-slit spectroscopy that traces ionized gas emission out to several kpcs, we find that rotation kinematics dominate the majority of the gas. We find that outflowing gas extends to distances less than 1 kpc, suggesting that outflows in Seyfert galaxies may not be powerful enough to evacuate their entire bulges.

Gemini Near Infrared Field Spectrograph Observations of the Seyfert 2 Galaxy MRK 573: In Situ Acceleration of Ionized and Molecular Gas Off Fueling Flows

Science.gov (United States)

Fischer, Travis C.; Machuca, C.; Diniz, M. R.; Crenshaw, D. M.; Kraemer, S. B.; Riffel, R. A.; Schmitt, H. R.; Baron, F.; Storchi-Bergmann, T.; Straughn, A. N.;

Spectroscopic and density functional theory studies of 5,7,3‧,5‧-tetrahydroxyflavanone from the leaves of Olea ferruginea

Science.gov (United States)

Hashmi, Muhammad Ali; Khan, Afsar; Ayub, Khurshid; Farooq, Umar

2014-07-01

5,7,3‧,5‧-Tetrahydroxyflavanone (1) was isolated from the leaves of Olea ferruginea and a theoretical model was developed for obtaining the electronic and spectroscopic properties of 1. The geometric and electronic properties were calculated at B3LYP/6-311 G (d, p) level of Density Functional Theory (DFT). The theoretical data was in good agreement with the experimental one. The optimized geometric parameters of compound 1 were calculated for the first time. The theoretical vibrational frequencies of 1 were found to correlate with the experimental IR spectrum after a scaling factor of 0.9811. The UV and NMR spectral data computed theoretically were in good agreement with the experimental data. Electronic properties of the compound i.e., ionization potential (IP), electron affinity (EA), coefficients of HOMO and LUMO were estimated computationally for the first time which can be used to explain its antioxidant as well as other related activities and more active sites on it. The intermolecular interactions and their effects on IR frequencies, electronic and geometric parameters were simulated using water molecule as a model for hydrogen bonding with flavonoid hydroxyl groups.

Calculation of exit dose for conformal and dynamically‐wedged fields, based on water‐equivalent path length measured with an amorphous silicon electronic portal imaging device

Science.gov (United States)

Glegg, Martin; Metwaly, Mohamed; Currie, Garry; Elliott, Alex

2011-01-01

In this study, we use the quadratic calibration method (QCM), in which an EPID image is converted into a matrix of equivalent path lengths (EPLs) and, therefore, exit doses, so as to model doses in conformal and enhanced dynamic wedge (EDW) fields. The QCM involves acquiring series of EPID images at a reference field size for different thicknesses of homogeneous solid water blocks. From these, a set of coefficients is established that is used to compute the EPL of any other irradiated material. To determine the EPL, the irradiated area must be known in order to establish the appropriate scatter correction. A method was devised for the automatic calculation of areas from the EPID image that facilitated the calculation of EPL for any field and exit dose. For EDW fields, the fitting coefficients were modified by utilizing the linac manufacturer's golden segmented treatment tables (GSTT) methodology and MU fraction model. The nonlinear response of the EPL with lower monitor units (MUs) was investigated and slight modification of the algorithm performed to account for this. The method permits 2D dose distributions at the exit of phantom or patient to be generated by relating the EPL with an appropriate depth dose table. The results indicate that the inclusion of MU correction improved the EPL determination. The irradiated field areas can be accurately determined from EPID images to within ± 1% uncertainty. Cross‐plane profiles and 2D dose distributions of EPID predicted doses were compared with those calculated with the Eclipse treatment planning system (TPS) and those measured directly with MapCHECK 2 device. Comparison of the 2D EPID dose maps to those from TPS and MapCHECK shows that more than 90% of all points passed the gamma index acceptance criteria of 3% dose difference and 3 mm distance to agreement (DTA), for both conformal and EDW study cases. We conclude that the EPID QCM is an accurate and convenient method for in vivo dosimetry and may, therefore

Dose patient verification during treatment using an amorphous silicon electronic portal imaging device in radiotherapy

International Nuclear Information System (INIS)

Berger, Lucie

2006-01-01

Today, amorphous silicon electronic portal imaging devices (aSi EPID) are currently used to check the accuracy of patient positioning. However, they are not use for dose reconstruction yet and more investigations are required to allow the use of an aSi EPID for routine dosimetric verification. The aim of this work is first to study the dosimetric characteristics of the EPID available at the Institut Curie and then, to check patient dose during treatment using these EPID. First, performance optimization of the Varian aS500 EPID system is studied. Then, a quality assurance system is set up in order to certify the image quality on a daily basis. An additional study on the dosimetric performance of the aS500 EPID is monitored to assess operational stability for dosimetry applications. Electronic portal imaging device is also a useful tool to improve IMRT quality control. The validation and the quality assurance of a portal dose image prediction system for IMRT pre-treatment quality control are performed. All dynamic IMRT fields are verified in clinical routine with the new method based on portal dosimetry. Finally, a new formalism for in vivo dosimetry using transit dose measured with EPID is developed and validated. The absolute dose measurement issue using aSi EPID is described and the midplane dose determination using in vivo dose measurements in combination with portal imaging is used with 3D-conformal-radiation therapy. (author) [fr

A Monte Carlo calculation model of electronic portal imaging device for transit dosimetry through heterogeneous media

Energy Technology Data Exchange (ETDEWEB)

Yoon, Jihyung; Jung, Jae Won, E-mail: jungj@ecu.edu [Department of Physics, East Carolina University, Greenville, North Carolina 27858 (United States); Kim, Jong Oh [Department of Radiation Oncology, University of Pittsburgh Cancer Institute, Pittsburgh, Pennsylvania 15232 (United States); Yeo, Inhwan [Department of Radiation Medicine, Loma Linda University Medical Center, Loma Linda, California 92354 (United States)

2016-05-15

Purpose: To develop and evaluate a fast Monte Carlo (MC) dose calculation model of electronic portal imaging device (EPID) based on its effective atomic number modeling in the XVMC code. Methods: A previously developed EPID model, based on the XVMC code by density scaling of EPID structures, was modified by additionally considering effective atomic number (Z{sub eff}) of each structure and adopting a phase space file from the EGSnrc code. The model was tested under various homogeneous and heterogeneous phantoms and field sizes by comparing the calculations in the model with measurements in EPID. In order to better evaluate the model, the performance of the XVMC code was separately tested by comparing calculated dose to water with ion chamber (IC) array measurement in the plane of EPID. Results: In the EPID plane, calculated dose to water by the code showed agreement with IC measurements within 1.8%. The difference was averaged across the in-field regions of the acquired profiles for all field sizes and phantoms. The maximum point difference was 2.8%, affected by proximity of the maximum points to penumbra and MC noise. The EPID model showed agreement with measured EPID images within 1.3%. The maximum point difference was 1.9%. The difference dropped from the higher value of the code by employing the calibration that is dependent on field sizes and thicknesses for the conversion of calculated images to measured images. Thanks to the Z{sub eff} correction, the EPID model showed a linear trend of the calibration factors unlike those of the density-only-scaled model. The phase space file from the EGSnrc code sharpened penumbra profiles significantly, improving agreement of calculated profiles with measured profiles. Conclusions: Demonstrating high accuracy, the EPID model with the associated calibration system may be used for in vivo dosimetry of radiation therapy. Through this study, a MC model of EPID has been developed, and their performance has been rigorously

Epidermal characteristics of toxic plants for cattle from the Salado River basin (Buenos Aires, Argentina Caracteres epidérmicos de las plantas tóxicas para el ganado de la Depresión del Salado (Buenos Aires, Argentina

Directory of Open Access Journals (Sweden)

Susana E. Freire

2005-12-01

Full Text Available One hundred and eighty species belonging to 41 families inhabiting the Salado River Basin of the province of Buenos Aires (Argentina were previously reported to be toxic for cattle. The purpose of this study was to provide a tool to distinguish the taxa when the plant material is desintegrated. In this way, an approach to the identification of these taxa through leaf epidermal features (anticlinal epidermal cell wall patterns, cuticular ornamentation, stomata, and hair types is performed. A key to the 180 species as well as illustrations of diagnostic characters are given.Las plantas tóxicas para el ganado están representadas en la Depresión del Salado (provincia de Buenos Aires, Argentina por 180 especies pertenecientes a 41 familias. El objetivo del presente trabajo es determinar estos taxa a partir de material desintegrado, utilizando caracteres epidérmicos foliares (paredes anticlinales de las células epidérmicas, ornamentación de la cutícula, tipos de estomas y pelos. Se brinda una clave para la determinación de las especies e ilustraciones de los caracteres diagnósticos.

49 CFR Appendix B to Part 178 - Alternative Leakproofness Test Methods

Science.gov (United States)

2010-10-01

... 49 Transportation 2 2010-10-01 2010-10-01 false Alternative Leakproofness Test Methods B Appendix... FOR PACKAGINGS Pt. 178, App. B Appendix B to Part 178—Alternative Leakproofness Test Methods In addition to the method prescribed in § 178.604 of this subchapter, the following leakproofness test methods...

Implementation of an integral program of quality assurance based on EPID to the IMRT

International Nuclear Information System (INIS)

Yannez Ruiz-Labrandera; Emilio; Gonzalez Perez, Y.

2015-01-01

We bring forward with this research the implementation of a procedure related to the assurance guaranty in the control of tue quality of IMRT treatment based on the technology of electronic portal images digital (EPID). For the sake of accomplishing quality controls, based in pylic digital images, we used like main tool the System of pylic digital images IviewGT TM with his application software. For the control of positioning of the multi-plates, we implemented a program in MATLAB, which yields the errors of positioning of the plates. For the dosimetric controls, the images obtained for the fields of treatment were climbed with the software ImageJ, and compared with the treatment planning systems (TPS) model Elekta's PrecisePlan ® for it we used the software Verisoft. We managed to implement a comprehensive program of quality control for IMRT. The positioning errors of the multiplates intervening bayouth's test younger errors of positioning under a 1m threw which the requisite is for the IMRT. The rest of the geometric proofs yielded favorable results inmail with them tolerance, same as the test Picket Fence. We verified 2 cases with the technique step and shoot, for it we verified 16 field, where gamma Index varied 85,8 - 98,9. It was checked the possibility to accomplish the quality controls for IMRT using pylic digital images, in our case checked itself himself I apply the Linac Elekta specify on the Ameijeiras. (Author)

Development of a one-stop beam verification system using electronic portal imaging devices for routine quality assurance

International Nuclear Information System (INIS)

Lim, Sangwook; Ma, Sun Young; Jeung, Tae Sig; Yi, Byong Yong; Lee, Sang Hoon; Lee, Suk; Cho, Sam Ju; Choi, Jinho

2012-01-01

In this study, a computer-based system for routine quality assurance (QA) of a linear accelerator (linac) was developed by using the dosimetric properties of an amorphous silicon electronic portal imaging device (EPID). An acrylic template phantom was designed such that it could be placed on the EPID and be aligned with the light field of the collimator. After irradiation, portal images obtained from the EPID were transferred in DICOM format to a computer and analyzed using a program we developed. The symmetry, flatness, field size, and congruence of the light and radiation fields of the photon beams from the linac were verified simultaneously. To validate the QA system, the ion chamber and film (X-Omat V2; Kodak, New York, NY) measurements were compared with the EPID measurements obtained in this study. The EPID measurements agreed with the film measurements. Parameters for beams with energies of 6 MV and 15 MV were obtained daily for 1 month using this system. It was found that our QA tool using EPID could substitute for the film test, which is a time-consuming method for routine QA assessment.

Development of a one-stop beam verification system using electronic portal imaging devices for routine quality assurance

Energy Technology Data Exchange (ETDEWEB)

Lim, Sangwook, E-mail: medicalphysics@hotmail.com [Department of Radiation Oncology, Kosin University College of Medicine, Seo-gu, Busan (Korea, Republic of); Ma, Sun Young; Jeung, Tae Sig [Department of Radiation Oncology, Kosin University College of Medicine, Seo-gu, Busan (Korea, Republic of); Yi, Byong Yong [Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, MD (United States); Lee, Sang Hoon [Department of Radiation Oncology, Cheil General Hospital and Women' s Healthcare Center, Kwandong University College of Medicine, Jung-gu, Seoul (Korea, Republic of); Lee, Suk [Department of Radiation Oncology, College of Medicine, Korea University, Seongbuk-gu, Seoul (Korea, Republic of); Cho, Sam Ju [Department of Radiation Oncology, Eulji University School of Medicine, Eulji General Hospital, Nowon-gu, Seoul (Korea, Republic of); Choi, Jinho [Department of Radiation Oncology, Gachon University of Medicine and Science, Namdong-gu, Incheon (Korea, Republic of)

2012-10-01

In this study, a computer-based system for routine quality assurance (QA) of a linear accelerator (linac) was developed by using the dosimetric properties of an amorphous silicon electronic portal imaging device (EPID). An acrylic template phantom was designed such that it could be placed on the EPID and be aligned with the light field of the collimator. After irradiation, portal images obtained from the EPID were transferred in DICOM format to a computer and analyzed using a program we developed. The symmetry, flatness, field size, and congruence of the light and radiation fields of the photon beams from the linac were verified simultaneously. To validate the QA system, the ion chamber and film (X-Omat V2; Kodak, New York, NY) measurements were compared with the EPID measurements obtained in this study. The EPID measurements agreed with the film measurements. Parameters for beams with energies of 6 MV and 15 MV were obtained daily for 1 month using this system. It was found that our QA tool using EPID could substitute for the film test, which is a time-consuming method for routine QA assessment.

SU-F-P-36: Automation of Linear Accelerator Star Shot Measurement with Advanced XML Scripting and Electronic Portal Imaging Device

International Nuclear Information System (INIS)

Nguyen, N; Knutson, N; Schmidt, M; Price, M

2016-01-01

Purpose: To verify a method used to automatically acquire jaw, MLC, collimator and couch star shots for a Varian TrueBeam linear accelerator utilizing Developer Mode and an Electronic Portal Imaging Device (EPID). Methods: An XML script was written to automate motion of the jaws, MLC, collimator and couch in TrueBeam Developer Mode (TBDM) to acquire star shot measurements. The XML script also dictates MV imaging parameters to facilitate automatic acquisition and recording of integrated EPID images. Since couch star shot measurements cannot be acquired using a combination of EPID and jaw/MLC collimation alone due to a fixed imager geometry, a method utilizing a 5mm wide steel ruler placed on the table and centered within a 15×15cm2 open field to produce a surrogate of the narrow field aperture was investigated. Four individual star shot measurements (X jaw, Y jaw, MLC and couch) were obtained using our proposed as well as traditional film-based method. Integrated EPID images and scanned measurement films were analyzed and compared. Results: Star shot (X jaw, Y jaw, MLC and couch) measurements were obtained in a single 5 minute delivery using the TBDM XML script method compared to 60 minutes for equivalent traditional film measurements. Analysis of the images and films demonstrated comparable isocentricity results, agreeing within 0.3mm of each other. Conclusion: The presented automatic approach of acquiring star shot measurements using TBDM and EPID has proven to be more efficient than the traditional film approach with equivalent results.

Micronutrient dietary patterns associated with type 2 diabetes mellitus among women of the E3N-EPIC (Etude Epidémiologique auprès de femmes de l'Education Nationale) cohort study.

Science.gov (United States)

Mancini, Francesca Romana; Dow, Courtney; Affret, Aurélie; Rajaobelina, Kalina; Dartois, Laureen; Balkau, Beverley; Bonnet, Fabrice; Boutron-Ruault, Marie-Christine; Fagherazzi, Guy

2018-02-19

Micronutrients play a key role in type 2 diabetes mellitus (T2DM), but methodological difficulties arise from their collinearity and interdependencies with foods. The aim of the present study was to identify micronutrient dietary patterns in the E3N-EPIC (Etude Epidémiologique auprès de femmes de l'Education Nationale) cohort and to investigate their association with risk of T2DM. Principal component analysis was used to identify micronutrient patterns among 71 270 women from the E3N-EPIC cohort. Associations between micronutrient patterns and risk of T2DM were quantified by hazard ratios (HRs) and 95% confidence intervals (CIs) from Cox proportional hazards regression models, adjusted for potential confounders. Six micronutrient patterns were identified explaining 78% of the total variance in micronutrient intake. A positive association was found between T2DM and a pattern highly correlated with intake of vitamins B 2 and B 5 (HR 1.34; 95% CI 1.16-1.56). Similarly, a positive association was found with a pattern characterized by high intakes of vitamin B 12 and retinol, and a low intake of vitamin C (HR 1.30; 95% CI 1.15-1.48). An inverse association was observed between T2DM and another two patterns: one correlated with magnesium and vitamin B 3 (HR 0.75; 95% CI 0.66-0.86), and the other correlated with manganese intake (HR 0.82; 95% CI 0.72-0.94). The findings of the present study identify micronutrients that have an effect on the risk of T2DM, and enable better understanding of the complexity of the diet when investigating the association between micronutrients and T2DM. © 2018 Ruijin Hospital, Shanghai Jiaotong University School of Medicine and John Wiley & Sons Australia, Ltd.

SU-G-JeP1-08: Dual Modality Verification for Respiratory Gating Using New Real- Time Tumor Tracking Radiotherapy System

Energy Technology Data Exchange (ETDEWEB)

Shiinoki, T; Hanazawa, H; Shibuya, K [Yamaguchi University, Ube, Yamaguchi (Japan); Kawamura, S; Koike, M; Yuasa, Y; Uehara, T; Fujimoto, K [Yamaguchi University Hospital, Ube, Yamaguchi (Japan)

2016-06-15

Purpose: The respirato ry gating system combined the TrueBeam and a new real-time tumor-tracking radiotherapy system (RTRT) was installed. The RTRT system consists of two x-ray tubes and color image intensifiers. Using fluoroscopic images, the fiducial marker which was implanted near the tumor was tracked and was used as the internal surrogate for respiratory gating. The purposes of this study was to develop the verification technique of the respiratory gating with the new RTRT using cine electronic portal image device images (EPIDs) of TrueBeam and log files of the RTRT. Methods: A patient who underwent respiratory gated SBRT of the lung using the RTRT were enrolled in this study. For a patient, the log files of three-dimensional coordinate of fiducial marker used as an internal surrogate were acquired using the RTRT. Simultaneously, the cine EPIDs were acquired during respiratory gated radiotherapy. The data acquisition was performed for one field at five sessions during the course of SBRT. The residual motion errors were calculated using the log files (E{sub log}). The fiducial marker used as an internal surrogate into the cine EPIDs was automatically extracted by in-house software based on the template-matching algorithm. The differences between the the marker positions of cine EPIDs and digitally reconstructed radiograph were calculated (E{sub EPID}). Results: Marker detection on EPID using in-house software was influenced by low image contrast. For one field during the course of SBRT, the respiratory gating using the RTRT showed the mean ± S.D. of 95{sup th} percentile E{sub EPID} were 1.3 ± 0.3 mm,1.1 ± 0.5 mm,and those of E{sub log} were 1.5 ± 0.2 mm, 1.1 ± 0.2 mm in LR and SI directions, respectively. Conclusion: We have developed the verification method of respiratory gating combined TrueBeam and new real-time tumor-tracking radiotherapy system using EPIDs and log files.

Verification of multileaf collimator leaf positions using an electronic portal imaging device

International Nuclear Information System (INIS)

Samant, Sanjiv S.; Zheng Wei; Parra, Nestor Andres; Chandler, Jason; Gopal, Arun; Wu Jian; Jain Jinesh; Zhu Yunping; Sontag, Marc

2002-01-01

An automated method is presented for determining individual leaf positions of the Siemens dual focus multileaf collimator (MLC) using the Siemens BEAMVIEW(PLUS) electronic portal imaging device (EPID). Leaf positions are computed with an error of 0.6 mm at one standard deviation (σ) using separate computations of pixel dimensions, image distortion, and radiation center. The pixel dimensions are calculated by superimposing the film image of a graticule with the corresponding EPID image. A spatial correction is used to compensate for the optical distortions of the EPID, reducing the mean distortion from 3.5 pixels (uncorrected) per localized x-ray marker to 2 pixels (1 mm) for a rigid rotation and 1 pixel for a third degree polynomial warp. A correction for a nonuniform dosimetric response across the field of view of the EPID images is not necessary due to the sharp intensity gradients across leaf edges. The radiation center, calculated from the average of the geometric centers of a square field at 0 deg. and 180 deg. collimator angles, is independent of graticule placement error. Its measured location on the EPID image was stable to within 1 pixel based on 3 weeks of repeated extensions/retractions of the EPID. The MLC leaf positions determined from the EPID images agreed to within a pixel of the corresponding values measured using film and ionization chamber. Several edge detection algorithms were tested: contour, Sobel, Roberts, Prewitt, Laplace, morphological, and Canny. These agreed with each other to within ≤1.2 pixels for the in-air EPID images. Using a test pattern, individual MLC leaves were found to be typically within 1 mm of the corresponding record-and-verify values, with a maximum difference of 1.8 mm, and standard deviations of <0.3 mm in the daily reproducibility. This method presents a fast, automatic, and accurate alternative to using film or a light field for the verification and calibration of the MLC

Utilization of an electronic portal imaging device for measurement of dynamic wedge data

International Nuclear Information System (INIS)

Elder, Eric S.; Miner, Marc S.; Butker, Elizabeth K.; Sutton, Danny S.; Davis, Lawrence W.

1996-01-01

Purpose/Objective: Due to the motion of the collimator during dynamic wedge treatments, the conventional method of collecting comprehensive wedge data with a water tank and a scanning ionization chamber is obsolete. It is the objective of this work to demonstrate the use of an electronic portal imaging device (EPID) and software to accomplish this task. Materials and Methods: A Varian Clinac[reg] 2300 C/D, equipped with a PortalVision TM EPID and Dosimetry Research Mode experimental software, was used to produce the radiation field. The Dosimetry Research Mode experimental software allows for a band of 10 of 256 high voltage electrodes to be continuously read and averaged by the 256 electrometer electrodes. The file that is produced contains data relating to the integrated ionization at each of the 256 points, essentially the cross plane beam profile. Software was developed using Microsoft C ++ to reformat the data for import into a Microsoft Excel spreadsheet allowing for easy mathematical manipulation and graphical display. Beam profiles were measured by the EPID with a 100 cm TSD for various field sizes. Each field size was measured open, steel wedged, and dynamically wedged. Scanning ionization chamber measurements performed in a water tank were compared to the open and steel wedged fields. Ionization chamber measurements taken in a water tank were compared with the dynamically wedged measurements. For the EPID measurements the depth was varied using Gammex RMI Solid Water TM placed directly above the EPID sensitive volume. Bolus material was placed between the Solid Water TM and the EPID to avoid an air gap. Results: Comparison of EPID measurements with those from an ion chamber in a water tank showed a discrepancy of ∼5%. Scans were successfully obtained for open, steel wedged and dynamically wedged beams. Software has been developed to allow for easy graphical display of beam profiles. Conclusions: Measurement of dynamic wedge data proves to be easily

26 CFR 1.167(b)-0 - Methods of computing depreciation.

Science.gov (United States)

2010-04-01

... 26 Internal Revenue 2 2010-04-01 2010-04-01 false Methods of computing depreciation. 1.167(b)-0....167(b)-0 Methods of computing depreciation. (a) In general. Any reasonable and consistently applied method of computing depreciation may be used or continued in use under section 167. Regardless of the...

Clinical Implementation of a Model-Based In Vivo Dose Verification System for Stereotactic Body Radiation Therapy–Volumetric Modulated Arc Therapy Treatments Using the Electronic Portal Imaging Device

Energy Technology Data Exchange (ETDEWEB)

McCowan, Peter M., E-mail: pmccowan@cancercare.mb.ca [Medical Physics Department, CancerCare Manitoba, Winnipeg, Manitoba (Canada); Asuni, Ganiyu [Medical Physics Department, CancerCare Manitoba, Winnipeg, Manitoba (Canada); Van Uytven, Eric [Medical Physics Department, CancerCare Manitoba, Winnipeg, Manitoba (Canada); Department of Physics and Astronomy, University of Manitoba, Winnipeg, Manitoba (Canada); VanBeek, Timothy [Medical Physics Department, CancerCare Manitoba, Winnipeg, Manitoba (Canada); McCurdy, Boyd M.C. [Medical Physics Department, CancerCare Manitoba, Winnipeg, Manitoba (Canada); Department of Physics and Astronomy, University of Manitoba, Winnipeg, Manitoba (Canada); Department of Radiology, University of Manitoba, Winnipeg, Manitoba (Canada); Loewen, Shaun K. [Department of Oncology, University of Calgary, Calgary, Alberta (Canada); Ahmed, Naseer; Bashir, Bashir; Butler, James B.; Chowdhury, Amitava; Dubey, Arbind; Leylek, Ahmet; Nashed, Maged [CancerCare Manitoba, Winnipeg, Manitoba (Canada)

2017-04-01

Purpose: To report findings from an in vivo dosimetry program implemented for all stereotactic body radiation therapy patients over a 31-month period and discuss the value and challenges of utilizing in vivo electronic portal imaging device (EPID) dosimetry clinically. Methods and Materials: From December 2013 to July 2016, 117 stereotactic body radiation therapy–volumetric modulated arc therapy patients (100 lung, 15 spine, and 2 liver) underwent 602 EPID-based in vivo dose verification events. A developed model-based dose reconstruction algorithm calculates the 3-dimensional dose distribution to the patient by back-projecting the primary fluence measured by the EPID during treatment. The EPID frame-averaging was optimized in June 2015. For each treatment, a 3%/3-mm γ comparison between our EPID-derived dose and the Eclipse AcurosXB–predicted dose to the planning target volume (PTV) and the ≥20% isodose volume were performed. Alert levels were defined as γ pass rates <85% (lung and liver) and <80% (spine). Investigations were carried out for all fractions exceeding the alert level and were classified as follows: EPID-related, algorithmic, patient setup, anatomic change, or unknown/unidentified errors. Results: The percentages of fractions exceeding the alert levels were 22.6% for lung before frame-average optimization and 8.0% for lung, 20.0% for spine, and 10.0% for liver after frame-average optimization. Overall, mean (± standard deviation) planning target volume γ pass rates were 90.7% ± 9.2%, 87.0% ± 9.3%, and 91.2% ± 3.4% for the lung, spine, and liver patients, respectively. Conclusions: Results from the clinical implementation of our model-based in vivo dose verification method using on-treatment EPID images is reported. The method is demonstrated to be valuable for routine clinical use for verifying delivered dose as well as for detecting errors.

Application of heavy-light methods to B meson physics

International Nuclear Information System (INIS)

Eichten, E.; Hockney, G.; Thacker, H.B.

1989-01-01

The heavy-light method is applied to the study of the B meson spectrum, the pseudoscalar decay constant f B , the mixing (B) parameter, and exclusive semileptonic B meson decays. Preliminary results are discussed for f B and the B parameter at β = 5.7 and κ = 0.165 on a 12 3 x 24 lattice and at β = 5.9 and κ = 0.158 on a 16 3 x 32 lattice. 9 refs., 2 figs., 2 tabs

[Comparison of the quick Gram stain method to the B&M modified and favor methods].

Science.gov (United States)

Osawa, Kayo; Kataoka, Nobumasa; Maruo, Toshio

2011-01-01

The Gram stain is an established method for bacterial identification, but the time needed to carry out this stain is 2-3 min. We attempted to shorten this time and stained a total of 70 clinical specimens isolated from using the Bartholomew & Mittwer (B&M) modified or Favor methods with a 3 s duration for washing and staining steps. Results were plotted and analyzed using a Hue Saturation Intensity (HSI) model. The range based on a plot of the two methods with the HSI model was presented as a reference interval. Our results indicated that 100% (35/35) of strains were Gram positive and 97.1% (34/35) were Gram negative for the quick B&M modified method. In the quick Favor method, 80.0% (28/35) were Gram positive and 68.6% (24/35) of strains were Gram negative. We propose that the quick B&M modified method is equivalent to the standard Gram staining method and is superior to the quick Favor method.

Quality assurance for electronic portal imaging devices

International Nuclear Information System (INIS)

Shalev, S.; Rajapakshe, R.; Gluhchev, G.; Luchka, K.

1997-01-01

Electronic portal imaging devices (EPIDS) are assuming an ever-increasing role in the verification of radiation treatment accuracy. They are used both in a passive capacity, for the determination of field displacement distributions (''setup errors''), and also in an active role whereby the patient setup is corrected on the basis of electronic portal images. In spite of their potential impact on the precision of patient treatment, there are few quality assurance procedures available, and most of the EPIDS in clinical use are subject, at best, to only perfunctory quality assurance. The goals of this work are (a) to develop an objective and reproducible test for EPID image quality on the factory floor and during installation of the EPID on site; (b) to provide the user with a simple and accurate tool for acceptance, commissioning, and routine quality control; and (c) to initiate regional, national and international collaboration in the implementation of standardized, objective, and automated quality assurance procedures. To this end we have developed an automated test in which a simple test object is imaged daily, and the spatial and contrast resolution of the EPID are automatically evaluated in terms of ''acceptable'', ''warning'' and ''stop'' criteria. Our experience over two years shows the test to be highly sensitive, reproducible, and inexpensive in time and effort. Inter-institutional trials are under way in Canada, US and Europe which indicate large variations in EPID image quality from one EPID to another, and from one center to another. We expect the new standardized quality assurance procedure to lead to improved, and consistent image quality, increased operator acceptance of the technology, and agreement on uniform standards by equipment suppliers and health care agencies. (author)

TH-AB-202-01: Daily Lung Tumor Motion Characterization On EPIDs Using a Markerless Tiling Model

Energy Technology Data Exchange (ETDEWEB)

Rozario, T [University of Texas Southwestern Medical Center, Dallas, TX (United States); University of Texas at Dallas, Richardson, TX (United States); Chiu, T; Lu, W; Chen, M; Yan, Y [University of Texas Southwestern Medical Center, Dallas, TX (United States); Bereg, S [University of Texas at Dallas, Richardson, TX (United States); Mao, W [University of Texas Southwestern Medical Center, Dallas, TX (United States); Henry Ford Hospital, Detroit, MI (United States)

2016-06-15

Purpose: Tracking lung tumor motion in real time allows for target dose escalation while simultaneously reducing dose to sensitive structures, thus increasing local control without increasing toxicity. We present a novel intra-fractional markerless lung tumor tracking algorithm using MV treatment beam images acquired during treatment delivery. Strong signals superimposed on the tumor significantly reduced the soft tissue resolution; while different imaging modalities involved introduce global imaging discrepancies. This reduced the comparison accuracies. A simple yet elegant Tiling algorithm is reported to overcome the aforementioned issues. Methods: MV treatment beam images were acquired continuously in beam’s eye view (BEV) by an electronic portal imaging device (EPID) during treatment and analyzed to obtain tumor positions on every frame. Every frame of the MV image was simulated by a composite of two components with separate digitally reconstructed radiographs (DRRs): all non-moving structures and the tumor. This Titling algorithm divides the global composite DRR and the corresponding MV projection into sub-images called tiles. Rigid registration is performed independently on tile-pairs in order to improve local soft tissue resolution. This enables the composite DRR to be transformed accurately to match the MV projection and attain a high correlation value through a pixel-based linear transformation. The highest cumulative correlation for all tile-pairs achieved over a user-defined search range indicates the 2-D coordinates of the tumor location on the MV projection. Results: This algorithm was successfully applied to cine-mode BEV images acquired during two SBRT plans delivered five times with different motion patterns to each of two phantoms. Approximately 15000 beam’s eye view images were analyzed and tumor locations were successfully identified on every projection with a maximum/average error of 1.8 mm / 1.0 mm. Conclusion: Despite the presence of

New method for the radioactive determination of vitamin B12

International Nuclear Information System (INIS)

Lewin, Nathan; Fries, J.E.; Richards, C.S.

1975-01-01

A description is given of a method for the radioactive determination of vitamin B12 in a sample solution of serum in which a radioactive tracer of vitamin B12 and the vitamin B12 of the serum compete with respect to an intrinsic factor of limited linking capacity. The free radioactive vitamin B12 and the free vitamin B12 of the serum are separated from the intrinsic factor and from the radioactive vitamin B12 and from the serum vitamin B12 linked to this factor, before the radioactivity is measured against standard values. The method consists in separating the free radioactive vitamin B12 and the free serum vitamin B12 of the intrinsic factor and portions of radioactive and serum vitamin B12 linked to this factor, by adding an adequate quantity of bentonite to adsorb the free radioactive vitamin B12 and free serum vitamin B12 so that the intrinsic factor surface floating solution in association with the linked radioactive vitamin B12 and the linked serum vitamin B12 may be physically isolated from the solid bentonite that has adsorbed the free radioactive vitamin B12 and the free serum vitamin B12 [fr

Hepatitis B Core Antigen in Hepatocytes of Chronic Hepatitis B: Comparison between Indirect Immunofluorescence and Immunoperoxidase Method

Science.gov (United States)

Tabassum, Shahina; Al-Mahtab, Mamun; Nessa, Afzalun; Jahan, Munira; Shamim Kabir, Chowdhury Mohammad; Kamal, Mohammad; Cesar Aguilar, Julio

2015-01-01

Background Hepatitis B virus (HBV) infection has many faces. Precore and core promoter mutants resemble inactive carrier status. The identification of hepatitis B core antigen (HBcAg) in hepatocytes may have variable clinical significance. The present study was undertaken to detect HBcAg in chronic hepatitis B (CHB) patients and to assess the efficacy of detection system by indirect immunofluorescence (IIF) and indirect immunoperoxidase (IIP). Materials and methods The study was done in 70 chronic HBV-infected patients. Out of 70 patients, eight (11.4%) were hepatitis B e antigen (HBeAg) positive and 62 (88.57%) were HBeAg negative. Hepatitis B core antigen was detected by indirect immunofluorescence (IIF) and indirect immunoperoxidase (IIP) methods in liver tissue. Results All HBeAg positive patients expressed HBcAg by both IIF and IIP methods. Out of 62 patients with HBeAg-negative CHB, HBcAg was detected by IIF in 55 (88.7%) patients and by IIP in 51 (82.26%) patients. A positive relation among viral load and HBcAg detection was also found. This was more evident in the case of HBeAg negative patients and showed a positive relation with HBV DNA levels. Conclusion Hepatitis B core antigen can be detected using the IIF from formalin fixed paraffin block preparation and also by IIP method. This seems to reflect the magnitudes of HBV replication in CHB. How to cite this article Raihan R, Tabassum S, Al-Mahtab M, Nessa A, Jahan M, Kabir CMS, Kamal M, Aguilar JC. Hepatitis B Core Antigen in Hepatocytes of Chronic Hepatitis B: Comparison between Indirect Immunofluorescence and Immunoperoxidase Method. Euroasian J Hepato-Gastroenterol 2015;5(1):7-10. PMID:29201677

Neosporosis epidémica y endémica: descripción de dos eventos en bovinos para cría

Directory of Open Access Journals (Sweden)

Patricio M Calandra

2014-12-01

Full Text Available El objetivo de este trabajo es describir dos eventos producidos en la provincia de Buenos Aires en los cuales Neospora caninum estuvo asociado a la ocurrencia de abortos en bovinos de cría para carne. En uno de ellos se registraron 11 abortos en 57 vaquillonas durante 45 días, en este evento fue 5 veces más probable que una vaquillona que sufrió un aborto fuera seropositiva a N. caninum que una que no lo sufrió (odds ratio [OR] = 4,9 IC 1,2-19,9 (p 0,05. Se analizaron dos fetos de cada evento: estos resultaron negativos a otros patógenos de la reproducción, aunque presentaron anticuerpos específicos y lesiones histopatológicas compatibles con infecciones por N. caninum. Estos resultados sugieren dos posibles modalidades de presentación de abortos en bovinos causados por N. caninum: una epidémica, como la del primer evento aquí referido, y una endémica, como la del segundo.

An MLC calibration method using a detector array

International Nuclear Information System (INIS)

Simon, Thomas A.; Kahler, Darren; Simon, William E.; Fox, Christopher; Li, Jonathan; Palta, Jatinder; Liu, Chihray

2009-01-01

Purpose: The authors have developed a quantitative calibration method for a multileaf collimator (MLC) which measures individual leaf positions relative to the MLC backup jaw on an Elekta Synergy linear accelerator. Methods: The method utilizes a commercially available two-axis detector array (Profiler 2; Sun Nuclear Corporation, Melbourne, FL). To calibrate the MLC bank, its backup jaw is positioned at the central axis and the opposing jaw is retracted to create a half-beam configuration. The position of the backup jaws field edge is then measured with the array to obtain what is termed the radiation defined reference line. The positions of the individual leaf ends relative to this reference line are then inferred by the detector response in the leaf end penumbra. Iteratively adjusting and remeasuring the leaf end positions to within specifications completes the calibration. Using the backup jaw as a reference for the leaf end positions is based on three assumptions: (1) The leading edge of an MLC leaf bank is parallel to its backup jaw's leading edge, (2) the backup jaw position is reproducible, and (3) the measured radiation field edge created by each leaf end is representative of that leaf's position. Data from an electronic portal imaging device (EPID) were used in a similar analysis to check the results obtained with the array. Results: The relative leaf end positions measured with the array differed from those measured with the EPID by an average of 0.11 ±0.09 mm per leaf. The maximum leaf positional change measured with the Profiler 2 over a 3 month period was 0.51 mm. A leaf positional accuracy of ±0.4 mm is easily attainable through the iterative calibration process. The method requires an average of 40 min to measure both leaf banks. Conclusions: This work demonstrates that the Profiler 2 is an effective tool for efficient and quantitative MLC quality assurance and calibration.

An MLC calibration method using a detector array

Energy Technology Data Exchange (ETDEWEB)

Simon, Thomas A.; Kahler, Darren; Simon, William E.; Fox, Christopher; Li, Jonathan; Palta, Jatinder; Liu, Chihray [Department of Nuclear and Radiological Engineering, University of Florida, 202 Nuclear Science Building, Gainesville, Florida 32611-8300 (United States); Sun Nuclear Corporation, 425-A Pineda Court, Melbourne, Florida 32940 (United States) and Department of Radiation Oncology, Health Science Center, University of Florida, P.O. Box 100385, Gainesville, Florida 32610-0385 (United States); Department of Radiation Oncology, Health Science Center, University of Florida, P.O. Box 100385, Gainesville, Florida 32610-0385 (United States); Sun Nuclear Corporation, 425-A Pineda Court, Melbourne, Florida 32940 (United States); Department of Radiation Oncology, Tulane University, 1415 Tulane Ave, HC65, New Orleans, Louisiana 70112 (United States); Department of Radiation Oncology, Health Science Center, University of Florida, P.O. Box 100385, Gainesville, Florida 32610-0385 (United States)

2009-10-15

Purpose: The authors have developed a quantitative calibration method for a multileaf collimator (MLC) which measures individual leaf positions relative to the MLC backup jaw on an Elekta Synergy linear accelerator. Methods: The method utilizes a commercially available two-axis detector array (Profiler 2; Sun Nuclear Corporation, Melbourne, FL). To calibrate the MLC bank, its backup jaw is positioned at the central axis and the opposing jaw is retracted to create a half-beam configuration. The position of the backup jaws field edge is then measured with the array to obtain what is termed the radiation defined reference line. The positions of the individual leaf ends relative to this reference line are then inferred by the detector response in the leaf end penumbra. Iteratively adjusting and remeasuring the leaf end positions to within specifications completes the calibration. Using the backup jaw as a reference for the leaf end positions is based on three assumptions: (1) The leading edge of an MLC leaf bank is parallel to its backup jaw's leading edge, (2) the backup jaw position is reproducible, and (3) the measured radiation field edge created by each leaf end is representative of that leaf's position. Data from an electronic portal imaging device (EPID) were used in a similar analysis to check the results obtained with the array. Results: The relative leaf end positions measured with the array differed from those measured with the EPID by an average of 0.11 {+-}0.09 mm per leaf. The maximum leaf positional change measured with the Profiler 2 over a 3 month period was 0.51 mm. A leaf positional accuracy of {+-}0.4 mm is easily attainable through the iterative calibration process. The method requires an average of 40 min to measure both leaf banks. Conclusions: This work demonstrates that the Profiler 2 is an effective tool for efficient and quantitative MLC quality assurance and calibration.

Análisis de un brote epidémico de brucelosis en trabajadores de un matadero

Directory of Open Access Journals (Sweden)

Luna Sánchez Antonio

1998-01-01

Full Text Available FUNDAMENTO: La notificación mediante el Sistema de Vigilancia Epidemiológica de un número inusual de casos de Brucelosis en trabajadores de un matadero a finales de 1996 hizo sospechar la existencia de un brote epidémico entre dicho colectivo profesional. MÉTODOS: Se recopiló la información disponible respecto a: 1 animales sacrificados en el matadero diagnosticados de brucelosis; 2 bajas laborales producidas y 3 datos de la mutualidad laboral relativos a los empleados del matadero con la enfermedad. Se realizó una encuesta epidemiológica a los trabajadores sobre los antecedentes de enfermedad, actividad laboral y riesgos no laborales (ingesta de leche o derivados sin higienizar. Las dependencias y actividades del matadero fueron inspeccionadas. Se diseñó un estudio de casos y controles. Se estudió cada puesto de trabajo tomando como controles a los restantes empleados del matadero. Para su verificación se realizó un estudio retrospectivo de cohortes. RESULTADOS: El brote epidémico de la enfermedad entre los trabajadores comenzó durante el mes de septiembre y duró hasta febrero del siguiente año. Las encuestas epidemiológicas descubrieron 28 trabajadores con síntomas sugestivos de la enfermedad, siendo los operarios del área de sacrificio del matadero quienes presentan la tasa de ataque más alta: 56%. En el estudio de casos y controles el riesgo más elevado se observó en dicho colectivo de trabajadores con una OR de 4,27 (IC 95%: 1,6-15 y p<0.01. Del mismo modo en el estudio de cohortes apreciamos que estos trabajadores presentan un RR de 2,5 (IC 95%: 1,5-4,3 cuando son comparados con el resto de trabajadores de la cohorte y de 8 (IC 95%: 2-30 si los comparamos con el colectivo de menor exposición. Los RR de los operarios de la limpieza y de la sala de despiece fueron de 6,56 (IC 95%: 1,6-27 para los primeros y de 4,77 (IC 95%: 1,1-21 para los segundos. Las fracciones etiológicas fueron del 87% para los de la zona de

SU-F-E-19: A Novel Method for TrueBeam Jaw Calibration

Energy Technology Data Exchange (ETDEWEB)

Corns, R; Zhao, Y; Huang, V [Fraser Valley Cancer Centre - BC Cancer Agency, Surrey, BC (United Kingdom)

2016-06-15

Purpose: A simple jaw calibration method is proposed for Varian TrueBeam using an EPID-Encoder combination that gives accurate fields sizes and a homogeneous junction dose. This benefits clinical applications such as mono-isocentric half-beam block breast cancer or head and neck cancer treatment with junction/field matching. Methods: We use EPID imager with pixel size 0.392 mm × 0.392 mm to determine the radiation jaw position as measured from radio-opaque markers aligned with the crosshair. We acquire two images with different symmetric field sizes and record each individual jaw encoder values. A linear relationship between each jaw’s position and its encoder value is established, from which we predict the encoder values that produce the jaw positions required by TrueBeam’s calibration procedure. During TrueBeam’s jaw calibration procedure, we move the jaw with the pendant to set the jaw into position using the predicted encoder value. The overall accuracy is under 0.1 mm. Results: Our in-house software analyses images and provides sub-pixel accuracy to determine field centre and radiation edges (50% dose of the profile). We verified the TrueBeam encoder provides a reliable linear relationship for each individual jaw position (R{sup 2}>0.9999) from which the encoder values necessary to set jaw calibration points (1 cm and 19 cm) are predicted. Junction matching dose inhomogeneities were improved from >±20% to <±6% using this new calibration protocol. However, one technical challenge exists for junction matching, if the collimator walkout is large. Conclusion: Our new TrueBeam jaw calibration method can systematically calibrate the jaws to crosshair within sub-pixel accuracy and provides both good junction doses and field sizes. This method does not compensate for a larger collimator walkout, but can be used as the underlying foundation for addressing the walkout issue.

Quasi 3D dosimetry (EPID, conventional 2D/3D detector matrices)

International Nuclear Information System (INIS)

Bäck, A

2015-01-01

Patient specific pretreatment measurement for IMRT and VMAT QA should preferably give information with a high resolution in 3D. The ability to distinguish complex treatment plans, i.e. treatment plans with a difference between measured and calculated dose distributions that exceeds a specified tolerance, puts high demands on the dosimetry system used for the pretreatment measurements and the results of the measurement evaluation needs a clinical interpretation. There are a number of commercial dosimetry systems designed for pretreatment IMRT QA measurements. 2D arrays such as MapCHECK ® (Sun Nuclear), MatriXX Evolution (IBA Dosimetry) and OCTAVIOUS ® 1500 (PTW), 3D phantoms such as OCTAVIUS ® 4D (PTW), ArcCHECK ® (Sun Nuclear) and Delta 4 (ScandiDos) and software for EPID dosimetry and 3D reconstruction of the dose in the patient geometry such as EPIDose TM (Sun Nuclear) and Dosimetry Check TM (Math Resolutions) are available. None of those dosimetry systems can measure the 3D dose distribution with a high resolution (full 3D dose distribution). Those systems can be called quasi 3D dosimetry systems. To be able to estimate the delivered dose in full 3D the user is dependent on a calculation algorithm in the software of the dosimetry system. All the vendors of the dosimetry systems mentioned above provide calculation algorithms to reconstruct a full 3D dose in the patient geometry. This enables analyzes of the difference between measured and calculated dose distributions in DVHs of the structures of clinical interest which facilitates the clinical interpretation and is a promising tool to be used for pretreatment IMRT QA measurements. However, independent validation studies on the accuracy of those algorithms are scarce. Pretreatment IMRT QA using the quasi 3D dosimetry systems mentioned above rely on both measurement uncertainty and accuracy of calculation algorithms. In this article, these quasi 3D dosimetry systems and their use in patient specific

A distortion correction method for image intensifier and electronic portal images used in radiotherapy

Energy Technology Data Exchange (ETDEWEB)

Ioannidis, G T; Geramani, K N; Zamboglou, N [Strahlenklinik, Stadtische Kliniken Offenbach, Offenbach (Germany); Uzunoglu, N [Department of Electrical and Computer Engineering, National Technical University of Athens, Athens (Greece)

1999-12-31

At the most of radiation departments a simulator and an `on line` verification system of the treated volume, in form of an electronic portal imaging device (EPID), are available. Networking and digital handling (saving, archiving etc.) of the image information is a necessity in the image processing procedures in order to evaluate verification and simulation recordings at the computer screen. Distortion is on the other hand prerequisite for quantitative comparison of both image modalities. Another limitation factor, in order to make quantitative assertions, is the fact that the irradiation fields in radiotherapy are usually bigger than the field of view of an image intensifier. Several segments of the irradiation field must therefore be acquired. Using pattern recognition techniques these segments can be composed into a single image. In this paper a distortion correction method will be presented. The method is based upon a well defined Grid which is embedded during the registration process on the image. The video signal from the image intensifier is acquired and processed. The grid is then recognised using image processing techniques. Ideally if all grid points are recognised, various methods can be applied in order to correct the distortion. But in practice this is not the case. Overlapping structures (bones etc.) have as a consequence that not all of the grid points can be recognised. Mathematical models from the Graph theory are applied in order to reconstruct the whole grid. The deviation of the grid points positions from the rated value is then used to calculate correction coefficients. This method (well defined grid, grid recognition, correction factors) can also be applied in verification images from the EPID or in other image modalities, and therefore a quantitative comparison in radiation treatment is possible. The distortion correction method and the application on simulator images will be presented. (authors)

Inventory of LCIA selection methods for assessing toxic releases. Methods and typology report part B

DEFF Research Database (Denmark)

Larsen, Henrik Fred; Birkved, Morten; Hauschild, Michael Zwicky

method(s) in Work package 8 (WP8) of the OMNIITOX project. The selection methods and the other CRS methods are described in detail, a set of evaluation criteria are developed and the methods are evaluated against these criteria. This report (Deliverable 11B (D11B)) gives the results from task 7.1d, 7.1e......This report describes an inventory of Life Cycle Impact Assessment (LCIA) selection methods for assessing toxic releases. It consists of an inventory of current selection methods and other Chemical Ranking and Scoring (CRS) methods assessed to be relevant for the development of (a) new selection...... and 7.1f of WP 7 for selection methods. The other part of D11 (D11A) is reported in another report and deals with characterisation methods. A selection method is a method for prioritising chemical emissions to be included in an LCIA characterisation of toxic releases, i.e. calculating indicator scores...

Dilute solutions and phase behavior of polydisperse A-b-(A-co-B) diblock copolymers

Czech Academy of Sciences Publication Activity Database

Gromadzki, Daniel; Lokaj, Jan; Šlouf, Miroslav; Štěpánek, Petr

2009-01-01

Roč. 50, č. 11 (2009), s. 2451-2459 ISSN 0032-3861 Institutional research plan: CEZ:AV0Z40500505 Keywords : diblock copolymer * dilute solution properties * microphase separation Subject RIV: CD - Macromolecular Chemistry Impact factor: 3.573, year: 2009

Two self-referencing methods for the measurement of beam spot position

International Nuclear Information System (INIS)

Nyiri, Balazs J.; Smale, Jason R.; Gerig, Lee H.

2012-01-01

Purpose: Two quantitative methods of measuring electron beam spot position with respect to the collimator axis of rotation (CAOR) are described. Methods: Method 1 uses a cylindrical ion chamber (IC) mounted on a jig corotational with the collimator making the relationship among the chamber, jaws, and CAOR fixed and independent of collimator angle. A jaw parallel to the IC axis is set to zero and the IC position adjusted so that the IC signal is approximately 50% of the open field value, providing a large dose gradient in the region of the IC. The cGy/MU value is measured as a function of collimator rotation, e.g., every 30°. If the beam spot does not lie on the CAOR, the signal from the ion chamber will vary with collimator rotation. Based on a measured spatial sensitivity, the distance of the beam spot from the CAOR can be calculated from the IC signal variation with rotation. The 2nd method is image based. Two stainless steel rods, 3 mm in diameter, are mounted to a jig attached to the Linac collimator. The rods, offset from the CAOR, lay in different planes normal to the CAOR, one at 158 cm SSD and the other at 70 cm SSD. As the collimator rotates the rods move tangent along an envelope circle, the centers of which are on the CAOR in their respective planes. Three images, each at a different collimator rotation, containing the shadows of both rods, are acquired on the Linac EPID. At each angle the shadow of the rods on the EPID defines lines tangent to the projection of the envelope circles. From these the authors determine the projected centers of the two circles at different heights. From the distance of these two points using the two heights and the source to EPID distance, the authors calculate the distance of the beam spot from the CAOR. Measurements with all two techniques were performed on an Elekta Linac. Measurements were performed with the beam spot in nominal clinical position and in a deliberately offset position. Measurements were also performed

Two self-referencing methods for the measurement of beam spot position

Energy Technology Data Exchange (ETDEWEB)

Nyiri, Balazs J.; Smale, Jason R.; Gerig, Lee H. [Ottawa Hospital Cancer Centre, Ottawa K1H 8L6 (Canada) and Faculty of Medicine, University of Ottawa, Ottawa K1H 8M5 (Canada); Elekta Canada, Ottawa, Ontario K1Y 1Z3 (Canada); Ottawa Hospital Cancer Centre, Ottawa K1H 8L6 (Canada); Department of Physics, Carleton University, Ottawa K1S 5B6 (Canada) and Faculty of Medicine, University of Ottawa, Ottawa K1H 8M5 (Canada)

2012-12-15

Purpose: Two quantitative methods of measuring electron beam spot position with respect to the collimator axis of rotation (CAOR) are described. Methods: Method 1 uses a cylindrical ion chamber (IC) mounted on a jig corotational with the collimator making the relationship among the chamber, jaws, and CAOR fixed and independent of collimator angle. A jaw parallel to the IC axis is set to zero and the IC position adjusted so that the IC signal is approximately 50% of the open field value, providing a large dose gradient in the region of the IC. The cGy/MU value is measured as a function of collimator rotation, e.g., every 30 Degree-Sign . If the beam spot does not lie on the CAOR, the signal from the ion chamber will vary with collimator rotation. Based on a measured spatial sensitivity, the distance of the beam spot from the CAOR can be calculated from the IC signal variation with rotation. The 2nd method is image based. Two stainless steel rods, 3 mm in diameter, are mounted to a jig attached to the Linac collimator. The rods, offset from the CAOR, lay in different planes normal to the CAOR, one at 158 cm SSD and the other at 70 cm SSD. As the collimator rotates the rods move tangent along an envelope circle, the centers of which are on the CAOR in their respective planes. Three images, each at a different collimator rotation, containing the shadows of both rods, are acquired on the Linac EPID. At each angle the shadow of the rods on the EPID defines lines tangent to the projection of the envelope circles. From these the authors determine the projected centers of the two circles at different heights. From the distance of these two points using the two heights and the source to EPID distance, the authors calculate the distance of the beam spot from the CAOR. Measurements with all two techniques were performed on an Elekta Linac. Measurements were performed with the beam spot in nominal clinical position and in a deliberately offset position. Measurements were also

Constituição epidêmica: velho e novo nas teorias e práticas da epidemiologia Epidemic constitution: old and new theories and practices in epidemiology

Directory of Open Access Journals (Sweden)

Dina Czeresnia

2001-08-01

Full Text Available O artigo analisa a importância da idéia de constituição epidêmica, identificada pela presença recorrente do pensamento hipocrático na história da epidemiologia. Em termos gerais, constituição relaciona epidemias a circunstâncias geográfico-atmosféricas. O que se destaca é a concepção do fenômeno epidêmico como desequilíbrio da harmonia da natureza, como totalidade e ultrapassando a dimensão geográfica. Permanência de um pensamento hipocrático não significa a existência de uma continuidade. A idéia de constituição foi marcada por descontinuidades e definida por conceitos distintos no decorrer da história. A força desse pensamento deve ser compreendida a partir da base filosófica que a origina: a physis. O interesse pelo pensamento pré-socrático ganha significado especial na crise da modernidade, trazendo novos elementos, também, para a interpretação da idéia de constituição em epidemiologia.The article analyzes the importance of the concept of epidemic constitution, whose presence has been recurrently identified in Hippocratic thinking throughout the history of epidemiology. In general terms, constitution relates epidemics to geographic and atmospheric conditions. The outstanding point in the article is the view of epidemics as phenomena associated to disruption in the harmony of nature, here understood as a whole beyond geographic dimensions. The permanence of Hippocratic thinking does not imply continuity. The concept of epidemic constitution has been discontinuous and structurally different throughout history. The power of the concept lies on its philosophical foundations: physis. Pre-Socratic ideas gain special significance for the understanding of the crisis of modern times and introduces new elements for the interpretation and conceptualization of constitution in epidemiology.

Respiratory gating during stereotactic body radiotherapy for lung cancer reduces tumor position variability.

Science.gov (United States)

Saito, Tetsuo; Matsuyama, Tomohiko; Toya, Ryo; Fukugawa, Yoshiyuki; Toyofuku, Takamasa; Semba, Akiko; Oya, Natsuo

2014-01-01

We evaluated the effects of respiratory gating on treatment accuracy in lung cancer patients undergoing lung stereotactic body radiotherapy by using electronic portal imaging device (EPID) images. Our study population consisted of 30 lung cancer patients treated with stereotactic body radiotherapy (48 Gy/4 fractions/4 to 9 days). Of these, 14 were treated with- (group A) and 16 without gating (group B); typically the patients whose tumors showed three-dimensional respiratory motion ≧5 mm were selected for gating. Tumor respiratory motion was estimated using four-dimensional computed tomography images acquired during treatment simulation. Tumor position variability during all treatment sessions was assessed by measuring the standard deviation (SD) and range of tumor displacement on EPID images. The two groups were compared for tumor respiratory motion and position variability using the Mann-Whitney U test. The median three-dimensional tumor motion during simulation was greater in group A than group B (9 mm, range 3-30 mm vs. 2 mm, range 0-4 mm; psimulation, tumor position variability in the EPID images was low and comparable to patients treated without gating. This demonstrates the benefit of respiratory gating.

Spitzer Secondary Eclipse Depths with Multiple Intrapixel Sensitivity Correction Methods Observations of WASP-13b, WASP-15b, WASP-16b, WASP-62b, and HAT-P-22b

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Kilpatrick, Brian M.; Lewis, Nikole K.; Kataria, Tiffany; Deming, Drake; Ingalls, James G.; Krick, Jessica E.; Tucker, Gregory S.

2017-01-01

We measure the 4.5 μm thermal emission of five transiting hot Jupiters, WASP-13b, WASP-15b, WASP-16b, WASP-62b, and HAT-P-22b using channel 2 of the Infrared Array Camera (IRAC) on the Spitzer Space Telescope. Significant intrapixel sensitivity variations in Spitzer IRAC data require careful correction in order to achieve precision on the order of several hundred parts per million (ppm) for the measurement of exoplanet secondary eclipses. We determine eclipse depths by first correcting the raw data using three independent data reduction methods. The Pixel Gain Map (PMAP), Nearest Neighbors (NNBR), and Pixel Level Decorrelation (PLD) each correct for the intrapixel sensitivity effect in Spitzer photometric time-series observations. The results from each methodology are compared against each other to establish if they reach a statistically equivalent result in every case and to evaluate their ability to minimize uncertainty in the measurement. We find that all three methods produce reliable results. For every planet examined here NNBR and PLD produce results that are in statistical agreement. However, the PMAP method appears to produce results in slight disagreement in cases where the stellar centroid is not kept consistently on the most well characterized area of the detector. We evaluate the ability of each method to reduce the scatter in the residuals as well as in the correlated noise in the corrected data. The NNBR and PLD methods consistently minimize both white and red noise levels and should be considered reliable and consistent. The planets in this study span equilibrium temperatures from 1100 to 2000 K and have brightness temperatures that require either high albedo or efficient recirculation. However, it is possible that other processes such as clouds or disequilibrium chemistry may also be responsible for producing these brightness temperatures.

SPITZER SECONDARY ECLIPSE DEPTHS WITH MULTIPLE INTRAPIXEL SENSITIVITY CORRECTION METHODS OBSERVATIONS OF WASP-13b, WASP-15b, WASP-16b, WASP-62b, AND HAT-P-22b

Energy Technology Data Exchange (ETDEWEB)

Kilpatrick, Brian M.; Tucker, Gregory S. [Department of Physics, Box 1843, Brown University, Providence, RI 02904 (United States); Lewis, Nikole K. [Space Telescope Science Institute, Baltimore, MD 21218 (United States); Kataria, Tiffany [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States); Deming, Drake [Department of Astronomy, University of Maryland, College Park, MD 20742 (United States); Ingalls, James G.; Krick, Jessica E., E-mail: brian_kilpatrick@brown.edu, E-mail: nlewis@stsci.org, E-mail: tiffany.kataria@jpl.nasa.gov, E-mail: ddeming@astro.umd.edu, E-mail: krick@ipac.caltech.edu [Spitzer Science Center, Infrared Processing and Analysis Center, California Institute of Technology, Mail Code 220-6, Pasadena, CA 91125 (United States)

2017-01-01

We measure the 4.5 μ m thermal emission of five transiting hot Jupiters, WASP-13b, WASP-15b, WASP-16b, WASP-62b, and HAT-P-22b using channel 2 of the Infrared Array Camera (IRAC) on the Spitzer Space Telescope . Significant intrapixel sensitivity variations in Spitzer IRAC data require careful correction in order to achieve precision on the order of several hundred parts per million (ppm) for the measurement of exoplanet secondary eclipses. We determine eclipse depths by first correcting the raw data using three independent data reduction methods. The Pixel Gain Map (PMAP), Nearest Neighbors (NNBR), and Pixel Level Decorrelation (PLD) each correct for the intrapixel sensitivity effect in Spitzer photometric time-series observations. The results from each methodology are compared against each other to establish if they reach a statistically equivalent result in every case and to evaluate their ability to minimize uncertainty in the measurement. We find that all three methods produce reliable results. For every planet examined here NNBR and PLD produce results that are in statistical agreement. However, the PMAP method appears to produce results in slight disagreement in cases where the stellar centroid is not kept consistently on the most well characterized area of the detector. We evaluate the ability of each method to reduce the scatter in the residuals as well as in the correlated noise in the corrected data. The NNBR and PLD methods consistently minimize both white and red noise levels and should be considered reliable and consistent. The planets in this study span equilibrium temperatures from 1100 to 2000 K and have brightness temperatures that require either high albedo or efficient recirculation. However, it is possible that other processes such as clouds or disequilibrium chemistry may also be responsible for producing these brightness temperatures.

Gallium determination with Rodamina B: a simple method

International Nuclear Information System (INIS)

Queiroz, R.R.U. de.

1981-01-01

A simple method for determining gallium with Rhodamine B, by the modification of the method proposed by Onishi and Sandell. The complex (RH) GaCl 4 is extracted with a mixture benzene-ethylacetate (3:1 V/V), from an aqueous medium 6 M in hydrochloric acid. The interference of foreign ions is studied. (C.G.C.) [pt

Supernumerary epidermal shields and carapace variation in Orbigny's slider turtles, Trachemys dorbigni (Testudines, Emydidae Escudos epidérmicos supernumerários e variação na carapaça na tartaruga-tigre-d'água, Trachemys dorbigni (Testudines, Emydidae

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Clóvis S. Bujes

2007-01-01

Full Text Available The epidermal plates of the carapace and plastron of 51 adults (38 females and 13 males, 07 immature individuals, and 46 hatchlings of the freshwater turtle Trachemys dorbigni (Durémil & Bibron, 1835, originated from the delta of Rio Jacuí region, Rio Grande do Sul state, Brazil, were examined. The results showed that 7.7% of males, 10.52% of females, 14.28% of immature individuals, and 6.52% of the hatchlings presented a kind of anomaly on the shell, as well as a presence of supernumerary epidermal shields. Although the modification in the number of epidermal shields presents a high frequency in Testudines, these are the first descriptions of the variation in the pattern of carapacial scutation in eleven individuals from a population of T. dorbigni. The association of several environmental factors acting on the embryonic development of the individual may be responsible for the alteration of the pattern of carapacial scutation in this species.Os escudos epidérmicos da carapaça e do plastrão de 51 adultos (38 fêmeas e 13 machos, 07 imaturos e 46 filhotes da tartaruga de água doce Trachemys dorbigni (Durémil & Bibron, 1835, procedentes da região do delta do Rio Jacuí, Rio Grande do Sul, Brasil, foram examinados. Desta análise, 7,7% dos machos, 10,52% das fêmeas, 14,28% dos imaturos e 6,52% dos filhotes apresentaram algum tipo de anomalia no casco, bem como presença de escudos epidérmicos supernumerários. Embora a alteração no número dos escudos epidérmicos seja relativamente freqüente em Testudines, estas são as primeiras descrições de variação no padrão de escutelação em onze indivíduos de uma população de T. dorbigni. A associação de diferentes fatores ambientais, interagindo sobre o desenvolvimento embrionário do indivíduo, parece ser a responsável pela alteração do padrão de escutelação nessa espécie.

Partial molar volumes of organic solutes in water. XXVII. Two aliphatic polyethers (triglyme, tetraglyme) at temperatures T = 298–573 K and pressures up to 30 MPa

International Nuclear Information System (INIS)

Cibulka, Ivan

2016-01-01

Highlights: • Standard molar volumes of two linear aliphatic polyethers in water are presented. • Data were obtained in the range T from (298 to 573) K and p up to 30 MPa. • Data combined with those obtained previously are analyzed and compared with standard molar volumes of cyclic ethers. - Abstract: Densities of dilute aqueous solutions of two linear aliphatic polyethers: 2,5,8,11-tetraoxadodecane (triethylene glycol dimethyl ether, triglyme) and 2,5,8,11,14-pentaoxapentadecane (tetraethylene glycol dimethyl ether, tetraglyme), measured in the temperature range from (298 to 573) K and at pressures up to 30 MPa using an automated flow vibrating-tube densimeter are reported. Standard molar volumes were evaluated from the measured data. The present values complement previous measurements performed for the title polyethers at atmospheric pressure in the temperature range from (278 to 343) K and extend the knowledge to temperature and pressure ranges in which the data on standard molar volumes for lower members of the homologous series (monoglyme, diglyme) are already available.

Síndrome de Stevens-Johnson e Necrólise Epidérmica Tóxica em um hospital do Distrito Federal

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Mariane Ferreira Barbosa Emerick

2014-12-01

Full Text Available Objetivou-se analisar as características demográficas e clínicas dos clientes diagnosticados com Síndrome de Stevens Johnson (SSJ e Necrólise Epidérmica Tóxica (NET, bem como identificar as ações dos profissionais de saúde para o manejo das Reações Adversas a Medicamentos (RAM em um hospital público do Distrito Federal. Pesquisa descritiva, retrospectiva, com abordagem quantitativa. Dados coletados em todos os prontuários de 22 clientes internados de janeiro de 2005 a setembro de 2012. Análise mediante estatística descritiva. Houve aumento gradativo de casos, com maior número nos anos de 2007 e 2012. Dos casos analisados, 9 foram diagnosticados com NET e 7 com SSJ; predominaram as mulheres (14 e a faixa etária de 21 aos 40 anos (10; 21 obtiveram cura. Os fármacos associados a RAM mais frequentes foram os antiepilépticos (10. Observou-se fragilidade nos registros clínicos nos prontuários e nas ações de monitoramento de RAM no serviço estudado.

40 CFR Appendix B to Part 425 - Modified Monier-Williams Method

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 29 2010-07-01 2010-07-01 false Modified Monier-Williams Method B Appendix B to Part 425 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS LEATHER TANNING AND FINISHING POINT SOURCE CATEGORY Pt. 425, App. B Appendix B to...

Leaf trajectory verification during dynamic intensity modulated radiotherapy using an amorphous silicon flat panel imager

International Nuclear Information System (INIS)

Sonke, Jan-Jakob; Ploeger, Lennert S.; Brand, Bob; Smitsmans, Monique H.P.; Herk, Marcel van

2004-01-01

An independent verification of the leaf trajectories during each treatment fraction improves the safety of IMRT delivery. In order to verify dynamic IMRT with an electronic portal imaging device (EPID), the EPID response should be accurate and fast such that the effect of motion blurring on the detected moving field edge position is limited. In the past, it was shown that the errors in the detected position of a moving field edge determined by a scanning liquid-filled ionization chamber (SLIC) EPID are negligible in clinical practice. Furthermore, a method for leaf trajectory verification during dynamic IMRT was successfully applied using such an EPID. EPIDs based on amorphous silicon (a-Si) arrays are now widely available. Such a-Si flat panel imagers (FPIs) produce portal images with superior image quality compared to other portal imaging systems, but they have not yet been used for leaf trajectory verification during dynamic IMRT. The aim of this study is to quantify the effect of motion distortion and motion blurring on the detection accuracy of a moving field edge for an Elekta iViewGT a-Si FPI and to investigate its applicability for the leaf trajectory verification during dynamic IMRT. We found that the detection error for a moving field edge to be smaller than 0.025 cm at a speed of 0.8 cm/s. Hence, the effect of motion blurring on the detection accuracy of a moving field edge is negligible in clinical practice. Furthermore, the a-Si FPI was successfully applied for the verification of dynamic IMRT. The verification method revealed a delay in the control system of the experimental DMLC that was also found using a SLIC EPID, resulting in leaf positional errors of 0.7 cm at a leaf speed of 0.8 cm/s

Quality assurance of geometric accuracy based on an electronic portal imaging device and log data analysis for Dynamic WaveArc irradiation.

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Hirashima, Hideaki; Miyabe, Yuki; Nakamura, Mitsuhiro; Mukumoto, Nobutaka; Mizowaki, Takashi; Hiraoka, Masahiro

2018-04-06

The purpose of this study was to develop a simple verification method for the routine quality assurance (QA) of Dynamic WaveArc (DWA) irradiation using electronic portal imaging device (EPID) images and log data analysis. First, an automatic calibration method utilizing the outermost multileaf collimator (MLC) slits was developed to correct the misalignment between the center of the EPID and the beam axis. Moreover, to verify the detection accuracy of the MLC position according to the EPID images, various positions of the MLC with intentional errors in the range 0.1-1 mm were assessed. Second, to validate the geometric accuracy during DWA irradiation, tests were designed in consideration of three indices. Test 1 evaluated the accuracy of the MLC position. Test 2 assessed dose output consistency with variable dose rate (160-400 MU/min), gantry speed (2.2-6°/s), and ring speed (0.5-2.7°/s). Test 3 validated dose output consistency with variable values of the above parameters plus MLC speed (1.6-4.2 cm/s). All tests were delivered to the EPID and compared with those obtained using a stationary radiation beam with a 0° gantry angle. Irradiation log data were recorded simultaneously. The 0.1-mm intentional error on the MLC position could be detected by the EPID, which is smaller than the EPID pixel size. In Test 1, the MLC slit widths agreed within 0.20 mm of their exposed values. The averaged root-mean-square error (RMSE) of the dose outputs was less than 0.8% in Test 2 and Test 3. Using log data analysis in Test 3, the RMSE between the planned and recorded data was 0.1 mm, 0.12°, and 0.07° for the MLC position, gantry angle, and ring angle, respectively. The proposed method is useful for routine QA of the accuracy of DWA. © 2018 The Authors. Journal of Applied Clinical Medical Physics published by Wiley Periodicals, Inc. on behalf of American Association of Physicists in Medicine.

Training Extract, AFSC 113X0B, Flight Engineer, Helicopter Qualified.

Science.gov (United States)

1982-12-01

SUPLRVISE 0JT , ’ 2 CONDuCT OJT 2.13 .3 12.5 to.2 c.R 5.70 f’ :1 IMPLEMENT OJT PROGRAMS 1.87 .3 b.! 4.8 17., 5.73 12v WRITE TEST QUESTIONS 1.76 .0 18.8 24.0...37.4 T.98 SYSTEM STATIC PORTS .𔃽b INSPECT PRIMARY FL1-1 CjNTROL SYSTEW (PFCS! 0,,? L65. 6-.5 t5.3 7C.4 4.4 Z!7 I’SPECT SEATS, SEAT IELTS . OR S40ULDP...0 31.3 21.2 51.3 5.63 5? WRITE COORESPONOENCE 2.34 .0 6.3 20.2 62.6 5.55 4 z ’Sv1EUEUT s AFET T PquGŚWS- 2.32 .a 17.5 17.3 33.08 2 AASH AND

Formal methods applied to industrial complex systems implementation of the B method

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Boulanger, Jean-Louis

2014-01-01

This book presents real-world examples of formal techniques in an industrial context. It covers formal methods such as SCADE and/or the B Method, in various fields such as railways, aeronautics, and the automotive industry. The purpose of this book is to present a summary of experience on the use of "formal methods" (based on formal techniques such as proof, abstract interpretation and model-checking) in industrial examples of complex systems, based on the experience of people currently involved in the creation and assessment of safety critical system software. The involvement of people from

Factores de riesgo en la neuropatía epidémica periférica

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Valentina Herrero Vicente

2001-06-01

Full Text Available Se realizó un estudio de casos y controles con el objetivo de profundizar en el conocimiento de factores de riesgo relacionados con la neuropatía epidémica periférica. El universo de estudio estuvo conformado por la totalidad de enfermos diagnosticados por la comisión provincial durante el período de 1993 a 1998, correspondiente al área de salud del policlínico "13 de Marzo", y los controles fueron escogidos en forma aleatoria con similares variables epidemiológicas. Se comprobó que no hubo asociación con la edad, y que el sexo femenino fue el más afectado. El incremento de la actividad física y el hábito de fumar tuvieron alta significación estadística. El alcoholismo resultó importante asociado al tabaquismo. Se concluyó que la actividad física intensa, la no ingestión de suplemento vitamínico y la nutrición deficitaria son factores de riesgo importantes en la aparición de la enfermedadA case-control study was performed to expand the knowledge on risk factors related to peripheral epidemic neuropathy. The universe of study was made up of all the patients diagnosed by the provincial commission from 1993 to 1998 in the health area of "13 de Marzo" polyclinics whereas the controls with similar epidemiological variables were randomly selected. It was proved that there was no association with age, and that females were the most affected. The increased physical activity and smoking had statistical significance. Alcoholism was found to be important associated with smoking. It was concluded that the internal physical activity, no ingestion of vitamin supplements and malnutrition are important risk factors in the occurrence of the disease

SU-E-T-77: A Statistical Approach to Manage Quality for Pre-Treatment Verification in IMRT/VMAT

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Jassal, K [Fortis Memorial Research Institute, Gurgaon, Haryana (India); Sarkar, B [AMRI Cancer Centre and GLA university, Mathura, Kolkata, West Bengal (India); Mohanti, B; Roy, S; Ganesh, T [FMRI, Gurgaon, Haryana (India); Munshi, A [Fortis Memorial Research Institute, Gurgon, Haryana (India); Chougule, A [SMS Medical College and Hospital, Jaipur, Rajasthan (India); Sachdev, K [Malaviya National Institute of Technology, Jaipur, Rajasthan (India)

2015-06-15

Objective: The study presents the application of a simple concept of statistical process control (SPC) for pre-treatment quality assurance procedure analysis for planar dose measurements performed using 2D-array and a-Si electronic portal imaging device (a-Si EPID). Method: A total of 195 patients of four different anatomical sites: brain (n1=45), head & neck (n2=45), thorax (n3=50) and pelvis (n4=55) were selected for the study. Pre-treatment quality assurance for the clinically acceptable IMRT/VMAT plans was measured with 2D array and a-Si EPID of the accelerator. After the γ-analysis, control charts and the quality index Cpm was evaluated for each cohort. Results: Mean and σ of γ ( 3%/3 mm) were EPID γ %≤1= 99.9% ± 1.15% and array γ %<1 = 99.6% ± 1.06%. Among all plans γ max was consistently lower than for 2D array as compared to a-Si EPID. Fig.1 presents the X-bar control charts for every cohort. Cpm values for a-Si EPID were found to be higher than array, detailed results are presented in table 1. Conclusion: Present study demonstrates the significance of control charts used for quality management purposes in newer radiotherapy clinics. Also, provides a pictorial overview of the clinic performance for the advanced radiotherapy techniques.Higher Cpm values for EPID indicate its higher efficiency than array based measurements.

Error diagnóstico en la neuropatía óptica epidémica Diagnostic error in epidemic optic neuropathy

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Rosaralis Santiesteban Freixas

2005-12-01

Full Text Available La forma óptica de la epidemia de neuropatía, aparecida en el decenio pasado en Cuba, ha sido motivo de discusión por el posible hiperdiagnóstico, de los más de 22 000 casos notificados. El propósito principal de este trabajo es profundizar en la caracterización de esta enfermedad y dar a conocer la congruencia que debe de existir entre la agudeza visual y la visión de colores en las neuropatías de este tipo; además, estimar sobre la base de este elemento la posible cifra de errores diagnósticos de dos grupos de pacientes con neuropatía optica epidérmica y en un tercer grupo de pacientes que no mejoraron con tratamiento, donde se reunieron 78 casos remitidos porque no mejoraban con tratamiento vitamínico. Los resultados demostraron congruencia entre el estado de afectación de la agudeza visual y la visión de colores en más del 90 % de los 960 casos de los grupos 1 y 2, con diagnóstico de neuropatía óptica epidémica comprobados por expertos, a diferencia de los casos del tercer grupo, en los que se detectó que el 96,1 % tuvieron de inicio falsos diagnósticos de esta enfermedad p The optic form of the neuropathy epidemic that appeared in the last decade in Cuba has been discussed due to the possible hyperdiagnosis of the more than 22 000 notified cases. The main objective of this paper was to go deep into the characterization of this disease, to make known the congruency that should exist between the visual acuity and the vision of colors in the neuropathies of this type, and to estimate, on the basis of this element, the possible figure of diagnostic errors in 2 groups of patients with EON and of a third group of patients that did not improve with the treatment. In this group, there were 78 cases that were referred because they did not respond to vitamin therapy. The results showed congruency between the state of affection of visual acuity and the vision of colors in more than 90 % of the 960 cases from groups 1 and 2 with

Chemical constituents isolated from turnera subulata Sm. and electrochemical characterization of phaeophytin b

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Brito Filho, Severino Goncalves de; Fernandes, Marianne Guedes; Souza, Maria de Fatima Vanderlei de, E-mail: mfvanderlei@ltf.ufpb.br [Universidade Federal da Paraiba (UFPB), Joao Pessoa, PB (Brazil). Centro de Ciencias da Saude

2014-07-01

Turnera subulata Sm., known as 'Chanana' or 'flor-do-Guaruja' in Brazilian folklore, is a plant species belonging to the subfamily Turneroideae of family Passifloraceae, which is used for various medicinal purposes in Brazil. The phytochemical study conducted here led to the isolation and identification of ten compounds present in T. subulata: two mixtures of steroids, sitosterol and stigmasterol (nonglycosylated and glycosylated); a mixture of flavonoids, 5,7,4′-trihidroxiflavona-8-C-α-glucopyranoside and 5,7,3′,4′-tetrahidroxiflavona-8-C-α-glucopyranosidel; and four phaeophytins, phaeophytin purpurin-18-phytyl ester, a rare natural product, phaeophytin a , 13{sup 2}-hydroxy-(13{sup 2}-S)-phaeophytin a , and phaeophytin b Phaeophytin b exhibited electrochemical activity similar to that of phthalocyanines. (author)

SU-E-J-89: Deformable Registration Method Using B-TPS in Radiotherapy.

Science.gov (United States)

Xie, Y

2012-06-01

A novel deformable registration method for four-dimensional computed tomography (4DCT) images is developed in radiation therapy. The proposed method combines the thin plate spline (TPS) and B-spline together to achieve high accuracy and high efficiency. The method consists of two steps. First, TPS is used as a global registration method to deform large unfit regions in the moving image to match counterpart in the reference image. Then B-spline is used for local registration, the previous deformed moving image is further deformed to match the reference image more accurately. Two clinical CT image sets, including one pair of lung and one pair of liver, are simulated using the proposed algorithm, which results in a tremendous improvement in both run-time and registration quality, compared with the conventional methods solely using either TPS or B-spline. The proposed method can combine the efficiency of TPS and the accuracy of B-spline, performing good adaptively and robust in registration of clinical 4DCT image. © 2012 American Association of Physicists in Medicine.

A novel and sensitive method for determining vitamin B3 and B7 by pre-column derivatization and high-performance liquid chromatography method with fluorescence detection.

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Baolei Fan

Full Text Available A new labeling reagent for vitamin analysis, 2-amino-10-ethyl acridine ketone (AEAO, has been synthesized and successfully applied to the analysis of vitamin B3 and vitamin B7 in different tea samples. The reaction of AEAO with vitamins could proceed easily and quickly in the presence of 1-ethyl-3-(3-dimethylaminopropyl-carbodiimide hydrochloride (EDC as condensing reagent within 45 min. The derivatives exhibited excellent fluorescence property with excitation and emission wavelengths of 290 nm and 430 nm, respectively. Response surface methodology (RSM was applied to the optimization of pre-column derivatization. Solid phase extraction with HLB cartridges was used for the extraction and purification of water-soluble vitamins in tea samples. The LODs for vitamin B3 and vitamin B7 were 2.56 and 2.22 ng mL-1, respectively. The proposed method was successfully applied to the analysis of vitamin B3 and vitamin B7 in different tea samples. The study provided a highly sensitive method for accurate analysis of trace vitamins from natural products.

Partial molar volumes of organic solutes in water. XXVIII. Three aliphatic poly(ethylene glycols) at temperatures T = 298 K–573 K and pressures up to 30 MPa

International Nuclear Information System (INIS)

Cibulka, Ivan

2017-01-01

Highlights: • Standard molar volumes of three poly(ethylene glycols) in water are presented. • Data were obtained in the range T from (298 to 573) K and p up to 30 MPa. • Data are analyzed and compared with those of similar solutes. - Abstract: Densities of dilute aqueous solutions of three poly(ethylene glycols): 3-oxapentane-1,5-diol (diethylene glycol), 3,6-dioxaoctane-1,8-diol (triethylene glycol), and 3,5,9-trioxaundecane-1,11-diol (tetraethylene glycol) measured in the temperature range from (298 to 573) K and at pressures up to 30 MPa using an automated flow vibrating-tube densimeter are reported. Standard molar volumes were evaluated from the measured data. Present data complement both the previous measurements performed at atmospheric pressure in the temperature range from (278 to 343) K and the data already available for the first member of the homologous series (ethylene glycol). A comparison with data previously measured for the homologous series of linear aliphatic polyethers (poly(ethylene glycol) dimethyl ethers, glymes), diethylene glycol monomethyl ether (3,6-dioxaheptan-1-ol), and selected alkane-α,ω-diols is presented.

Measurement of the b hadron lifetime with the dipole method

Science.gov (United States)

Buskulic, D.; de Bonis, I.; Decamp, D.; Ghez, P.; Goy, C.; Lees, J.-P.; Minard, M.-N.; Pietrzyk, B.; Ariztizabal, F.; Comas, P.; Crespo, J. M.; Delfino, M.; Efthymiopoulos, I.; Fernandez, E.; Fernandez-Bosman, M.; Gaitan, V.; Garrido, Ll.; Mattison, T.; Pacheco, A.; Padilla, C.; Pascual, A.; Creanza, D.; de Palma, M.; Farilla, A.; Iaselli, G.; Maggi, G.; Marinelli, N.; Natali, S.; Nuzzo, S.; Ranieri, A.; Raso, G.; Romano, F.; Ruggieri, F.; Selvaggi, G.; Silvestris, L.; Tempesta, P.; Zito, G.; Chai, Y.; Hu, H.; Huang, D.; Huang, X.; Lin, J.; Wang, T.; Xie, Y.; Xu, D.; Xu, R.; Zhang, J.; Zhang, L.; Zhao, W.; Bonvicini, G.; Boudreau, J.; Casper, D.; Drevermann, H.; Forty, R. W.; Ganis, G.; Gay, C.; Hagelberg, R.; Harvey, J.; Hilgart, J.; Jacobsen, R.; Jost, B.; Knobloch, J.; Lehraus, I.; Maggi, M.; Markou, C.; Martinez, M.; Mato, P.; Meinhard, H.; Minten, A.; Miquel, R.; Moser, H.-G.; Palazzi, P.; Pater, J. R.; Perlas, J. A.; Pusztaszeri, J.-F.; Ranjard, F.; Rolandi, L.; Rothberg, J.; Ruan, T.; Saich, M.; Schlatter, D.; Schmelling, M.; Sefkow, F.; Tejessy, W.; Tomalin, I. R.; Veenhof, R.; Wachsmuth, H.; Wasserbaech, S.; Wiedenmann, W.; Wildish, T.; Witzeling, W.; Wotschack, J.; Ajaltouni, Z.; Badaud, F.; Bardadin-Otwinowska, M.; El Fellous, R.; Falvard, A.; Gay, P.; Guicheney, C.; Henrard, P.; Jousset, J.; Michel, B.; Montret, J.-C.; Pallin, D.; Perret, P.; Podlyski, F.; Proriol, J.; Prulhière, F.; Saadi, F.; Fearnley, T.; Hansen, J. B.; Hansen, J. D.; Hansen, J. R.; Hansen, P. H.; Møllerud, R.; Nilsson, B. S.; Kyriakis, A.; Simopoulou, E.; Siotis, I.; Vayaki, A.; Zachariadou, K.; Badier, J.; Blondel, A.; Bonneaud, G.; Brient, J. C.; Bourdon, P.; Fouque, G.; Orteu, S.; Rougé, A.; Rumpf, M.; Tanaka, R.; Verderi, M.; Videau, H.; Candlin, D. J.; Parsons, M. I.; Veitch, E.; Focardi, E.; Moneta, L.; Parrini, G.; Corden, M.; Georgiopoulos, C.; Ikeda, M.; Levinthal, D.; Antonelli, A.; Baldini, R.; Bencivenni, G.; Bologna, G.; Bossi, F.; Campana, P.; Capon, G.; Cerutti, F.; Chiarella, V.; D'Ettorre-Piazzoli, B.; Felici, G.; Laurelli, P.; Mannocchi, G.; Murtas, F.; Murtas, G. P.; Passalacqua, L.; Pepe-Altarelli, M.; Picchi, P.; Colrain, P.; Ten Have, I.; Lynch, J. G.; Maitland, W.; Morton, W. T.; Raine, C.; Reeves, P.; Scarr, J. M.; Smith, K.; Smith, M. G.; Thompson, A. S.; Turnbull, R. M.; Brandl, B.; Braun, O.; Geweniger, C.; Hanke, P.; Hepp, V.; Kluge, E. E.; Maumary, Y.; Putzer, A.; Rensch, B.; Stahl, A.; Tittel, K.; Wunsch, M.; Beuselinck, R.; Binnie, D. M.; Cameron, W.; Cattaneo, M.; Colling, D. J.; Dornan, P. J.; Greene, A. M.; Hassard, J. F.; Lieske, N. M.; Moutoussi, A.; Nash, J.; Patton, S.; Payne, D. G.; Phillips, M. J.; San Martin, G.; Sedgbeer, J. K.; Wright, A. G.; Girtler, P.; Kuhn, D.; Rudolph, G.; Vogl, R.; Bowdery, C. K.; Brodbeck, T. J.; Finch, A. J.; Foster, F.; Hughes, G.; Jackson, D.; Keemer, N. R.; Nuttall, M.; Patel, A.; Sloan, T.; Snow, S. W.; Whelan, E. P.; Kleinknecht, K.; Raab, J.; Renk, B.; Sander, H.-G.; Schmidt, H.; Walther, S. M.; Wanke, R.; Wolf, B.; Zimmermann, A.; Bencheikh, A. M.; Benchouk, C.; Bonissent, A.; Carr, J.; Coyle, P.; Drinkard, J.; Etienne, F.; Nicod, D.; Papalexiou, S.; Payre, P.; Roos, L.; Rousseau, D.; Schwemling, P.; Talby, M.; Adlung, S.; Assmann, R.; Bauer, C.; Blum, W.; Brown, D.; Cattaneo, P.; Dehning, B.; Dietl, H.; Dydak, F.; Frank, M.; Halley, A. W.; Jakobs, K.; Lauber, J.; Lütjens, G.; Lutz, G.; Männer, W.; Richter, R.; Schröder, J.; Schwarz, A. S.; Settles, R.; Seywerd, H.; Stierlin, U.; Stiegler, U.; St. Denis, R.; Wolf, G.; Alemany, R.; Boucrot, J.; Callot, O.; Cordier, A.; Davier, M.; Duflot, L.; Grivaz, J.-F.; Heusse, Ph.; Jaffe, D. E.; Janot, P.; Kim, D. W.; Le Diberder, F.; Lefrançois, J.; Lutz, A.-M.; Schune, M.-H.; Veillet, J.-J.; Videau, I.; Zhang, Z.; Abbaneo, D.; Bagliesi, G.; Batignani, G.; Bottigli, U.; Bozzi, C.; Calderini, G.; Carpinelli, M.; Ciocci, M. A.; Ciulli, V.; Dell'Orso, R.; Ferrante, I.; Fidecaro, F.; Foà, L.; Forti, F.; Giassi, A.; Giorgi, M. A.; Gregorio, A.; Ligabue, F.; Lusiani, A.; Mannelli, E. B.; Marrocchesi, P. S.; Messineo, A.; Palla, F.; Rizzo, G.; Sanguinetti, G.; Spagnolo, P.; Steinberger, J.; Tenchini, R.; Tonelli, G.; Triggiani, G.; Valassi, A.; Vannini, C.; Venturi, A.; Verdini, P. G.; Walsh, J.; Betteridge, A. P.; Gao, Y.; Green, M. G.; March, P. V.; Mir, Ll. M.; Medcalf, T.; Quazi, I. S.; Strong, J. A.; West, L. R.; Botterill, D. R.; Clifft, R. W.; Edgecock, T. R.; Haywood, S.; Norton, P. R.; Thompson, J. C.; Bloch-Devaux, B.; Colas, P.; Duarte, H.; Emery, S.; Kozanecki, W.; Lançon, E.; Lemaire, M. C.; Locci, E.; Marx, B.; Perez, P.; Rander, J.; Renardy, J.-F.; Rosowsky, A.; Roussarie, A.; Schuller, J.-P.; Schwindling, J.; Si Mohand, D.; Vallage, B.; Johnson, R. P.; Litke, A. M.; Taylor, G.; Wear, J.; Ashman, J. G.; Babbage, W.; Booth, C. N.; Buttar, C.; Cartwright, S.; Combley, F.; Dawson, I.; Thompson, L. F.; Barbeiro, E.; Böhrer, A.; Brandt, S.; Cowan, G.; Grupen, C.; Lutters, G.; Rivera, F.; Schäfer, U.; Smolik, L.; Bosisio, L.; Della Marina, R.; Giannini, G.; Gobbo, B.; Ragusa, F.; Bellantoni, L.; Chen, W.; Conway, J. S.; Feng, Z.; Ferguson, D. P. S.; Gao, Y. S.; Grahl, J.; Harton, J. L.; Hayes, O. J.; Nachtman, J. M.; Pan, Y. B.; Saadi, Y.; Schmitt, M.; Scott, I.; Sharma, V.; Shi, Z. H.; Turk, J. D.; Walsh, A. M.; Weber, F. V.; Sau Lan Wu; Wu, X.; Zheng, M.; Zobernig, G.; Aleph Collaboration

1993-09-01

A measurement of the average lifetime of b hadrons has been performed with dipole method on a sample of 260 000 hadronic Z decays recorded with the ALEPH detector during 1991. The dipole is the distance between the vertices built in the opposite hemispheres. The mean dipole is extracted from all the events without attempting b enrichment. Comparing the average of the data dipole distribution with a Monte Carlo calibration curve obtained with different b lifetimes, an average b hadron lifetime of 1.51±0.08 ps is extracted.

Análisis comparativo de los caracteres epidérmicos en Flourensia campestris y F. oolepis (Asteraceae Comparative analysis of the epidermal characters in Flourensia campestris and F. oolepis (Asteraceae

Directory of Open Access Journals (Sweden)

Natalia Delbón

Full Text Available En el presente estudio se examinaron y compararon cuantitativamente las epidermis foliares de Flourensia campestris Griseb. y F. oolepis S. F. Blake, especies endémicas que crecen en las sierras de Córdoba, Argentina. Para ello, se seleccionaron cinco variables: número de células epidérmicas propiamente dichas, estomas, tricomas glandulares y eglandulares e índice estomático. Los resultados obtenidos se evaluaron por métodos estadísticos; ellos indican que hay diferencias significativas entre ambas especies en las variables frecuencia de estomas, de células propiamente dichas, de tricomas glandulares e índice estomático. Estos datos podrían ser de interés para su reconocimiento cuando se dispone de muestras pequeñas o fragmentos.This study provides comparative analyses of foliar epidermis in Flourensia campestris Griseb. and F. oolepis S. F. Blake, endemic species that grow in Córdoba, Argentina. Five variables were selected: number of epidermal cells, stomata, glandular and eglandular trichomes and stomatal index. Results were evaluated by statistical methods; they show that there are significant differences between the variables of both species; these data could be of interest for their identification, when only are available small samples and fragments.

A direct method to solve optimal knots of B-spline curves: An application for non-uniform B-spline curves fitting.

Directory of Open Access Journals (Sweden)

Van Than Dung

Full Text Available B-spline functions are widely used in many industrial applications such as computer graphic representations, computer aided design, computer aided manufacturing, computer numerical control, etc. Recently, there exist some demands, e.g. in reverse engineering (RE area, to employ B-spline curves for non-trivial cases that include curves with discontinuous points, cusps or turning points from the sampled data. The most challenging task in these cases is in the identification of the number of knots and their respective locations in non-uniform space in the most efficient computational cost. This paper presents a new strategy for fitting any forms of curve by B-spline functions via local algorithm. A new two-step method for fast knot calculation is proposed. In the first step, the data is split using a bisecting method with predetermined allowable error to obtain coarse knots. Secondly, the knots are optimized, for both locations and continuity levels, by employing a non-linear least squares technique. The B-spline function is, therefore, obtained by solving the ordinary least squares problem. The performance of the proposed method is validated by using various numerical experimental data, with and without simulated noise, which were generated by a B-spline function and deterministic parametric functions. This paper also discusses the benchmarking of the proposed method to the existing methods in literature. The proposed method is shown to be able to reconstruct B-spline functions from sampled data within acceptable tolerance. It is also shown that, the proposed method can be applied for fitting any types of curves ranging from smooth ones to discontinuous ones. In addition, the method does not require excessive computational cost, which allows it to be used in automatic reverse engineering applications.

Methods of characterization of multiphase Nd-Fe-B melt-spun alloys

Directory of Open Access Journals (Sweden)

Grujić A.

2007-01-01

Full Text Available Nanocomposite permanent magnetic materials based on Nd-Fe-B alloys with a low Nd content are a new type of permanent magnetic material. The microstructure of these nanocomposite permanent magnets is composed of a mixture of magnetically soft and hard phases providing the so called exchange coupling effect. Beside the optimization process parameters, methods of characterization have a very important role in the design of an optimal magnetic matrix of multiphase melt-spun Nd-Fe-B alloys. Different methods and techniques of characterization were used for observation and study of the microstructure evolution during crystallization. A summary results of measurements using different methods of characterization are presented to enable a better insight into relations between the microstructure and magnetic properties of the investigated melt-spun Nd-Fe-B alloys. .

Basic dose response of fluorescent screen-based portal imaging device

International Nuclear Information System (INIS)

Yeo, In Hwan; Yonannes, Yonas; Zhu, Yunping

1999-01-01

The purpose of this study is to investigate fundamental aspects of the dose response of fluorescent screen-based electronic portal imaging devices (EPIDs). We acquired scanned signal across portal planes as we varied the radiation that entered the EPID by changing the thickness and anatomy of the phantom as well as the air gap between the phantom and the EPID. In addition, we simulated the relative contribution of the scintillation light signal in the EPID system. We have shown that the dose profile across portal planes is a function of the air gap and phantom thickness. We have also found that depending on the density change within the phantom geometry, errors associated with dose response based on the EPID scan can be as high as 7%. We also found that scintillation light scattering within the EPID system is an important source of error. This study revealed and demonstrated fundamental characteristics of dose response of EPID, as relative to that of ion chambers. This study showed that EPID based on fluorescent screen cannot be an accurate dosimetry system

Associations between Intake of Folate, Methionine, and Vitamins B-12, B-6 and Prostate Cancer Risk in American Veterans

Directory of Open Access Journals (Sweden)

Adriana C. Vidal

2012-01-01

Full Text Available Prostate cancer (PC is the second leading cause of cancer death in men. Recent reports suggest that excess of nutrients involved in the one-carbon metabolism pathway increases PC risk; however, empirical data are lacking. Veteran American men (272 controls and 144 PC cases who attended the Durham Veteran American Medical Center between 2004–2009 were enrolled into a case-control study. Intake of folate, vitamin B12, B6, and methionine were measured using a food frequency questionnaire. Regression models were used to evaluate the association among one-carbon cycle nutrients, MTHFR genetic variants, and prostate cancer. Higher dietary methionine intake was associated with PC risk (OR = 2.1; 95%CI 1.1–3.9 The risk was most pronounced in men with Gleason sum <7 (OR = 2.75; 95%CI 1.32– 5.73. The association of higher methionine intake and PC risk was only apparent in men who carried at least one MTHFR A1298C allele (OR =6.7; 95%CI = 1.6–27.8, compared to MTHFR A1298A noncarrier men (OR =0.9; 95%CI = 0.24–3.92 (p-interaction =0.045. There was no evidence for associations between B vitamins (folate, B12, and B6 and PC risk. Our results suggest that carrying the MTHFR A1298C variants modifies the association between high methionine intake and PC risk. Larger studies are required to validate these findings.

Study on the dose response characteristics of a scanning liquid ion-chamber electronic portal imaging device

CERN Document Server

Ma Shao Gang; Song Yi Xin

2002-01-01

Objective: To study the dose response characteristics and the influence factors such as gantry angle, field size and acquisition mode on the dosimetric response curves, when using a scanning liquid ion-chamber electronic portal imaging device (EPID) for dose verification. Methods: All experiments were carried out on a Varian 600 C/D accelerator (6 MV X-ray) equipped with a Varian PortalVision sup T sup M MK2 type EPID. To obtain the dose response curve, the relationship between the incident radiation intensity to the detector and the pixel value output from the EPID were established. Firstly, the different dose rates of 6 MV X-rays were obtained by varying SSD. Secondly, three digital portal images were acquired for each dose rate using the EPID and averaged to avoid the influence of the dose rate fluctuations of the accelerator. The pixel values of all images were read using self-designed image analysis software, and and average for a region consisting of 11 x 11 pixels around the center was taken as the res...

Phase transitions on (liquid + liquid) equilibria for (water + 1-methylnaphthalene + light aromatic hydrocarbon) ternary systems at T = (563, 573, and 583) K

International Nuclear Information System (INIS)

Togo, Masaki; Inamori, Yoshiki; Shimoyama, Yusuke

2012-01-01

Highlights: ► Mixtures of (water + 1-methylnaphthalene + light aromatic hydrocarbon) are focused. ► Phase transition pressures on (liquid + liquid) equilibria were measured. ► Effects of aromatic hydrocarbons on phase transition pressure are investigated. ► Phase transition pressures are discussed using dielectric constants of hydrocarbons. - Abstract: Phase transitions for (water + 1-methylnaphthalene + light aromatic hydrocarbon) ternary systems are observed at their (liquid + liquid) equilibria at T = (563, 573, and 583) K and (8.6 to 25.0) MPa. The phase transition pressures at T = (563, 573, and 583) K were measured for the five species of light aromatic hydrocarbons, o-, m-, p-xylenes, ethylbenzene, and mesitylene. The measurements of the phase transition pressures were carried out by changing the feed mole fraction of water and 1-methylnaphthalene in water free, respectively. Effects of the feed mole fraction of water on the phase transition pressures are very small. Increasing the feed mole fraction of 1-methylnaphthalene results in decreasing the phase transition pressures at constant temperature. The slopes depending on the feed mole fraction for 1-methylnaphthalene at the phase transition pressures are decreased with increasing temperature for (water + 1-methylnaphthalene + p-xylene), (water + 1-methylnaphthalene + o-xylene), and (water + 1-methylnaphthalene + mesitylene) systems. For xylene isomers, the highest and lowest of the phase transition pressures are obtained in the case of p- and o-xylenes, respectively. The phase transition pressures for ethylbenzene are lower than those in the case of p-xylene. The similar phase transition pressures are given for p-xylene and mesitylene.

A novel method for quantification of beam's-eye-view tumor tracking performance.

Science.gov (United States)

Hu, Yue-Houng; Myronakis, Marios; Rottmann, Joerg; Wang, Adam; Morf, Daniel; Shedlock, Daniel; Baturin, Paul; Star-Lack, Josh; Berbeco, Ross

2017-11-01

In-treatment imaging using an electronic portal imaging device (EPID) can be used to confirm patient and tumor positioning. Real-time tumor tracking performance using current digital megavolt (MV) imagers is hindered by poor image quality. Novel EPID designs may help to improve quantum noise response, while also preserving the high spatial resolution of the current clinical detector. Recently investigated EPID design improvements include but are not limited to multi-layer imager (MLI) architecture, thick crystalline and amorphous scintillators, and phosphor pixilation and focusing. The goal of the present study was to provide a method of quantitating improvement in tracking performance as well as to reveal the physical underpinnings of detector design that impact tracking quality. The study employs a generalizable ideal observer methodology for the quantification of tumor tracking performance. The analysis is applied to study both the effect of increasing scintillator thickness on a standard, single-layer imager (SLI) design as well as the effect of MLI architecture on tracking performance. The present study uses the ideal observer signal-to-noise ratio (d') as a surrogate for tracking performance. We employ functions which model clinically relevant tasks and generalized frequency-domain imaging metrics to connect image quality with tumor tracking. A detection task for relevant Cartesian shapes (i.e., spheres and cylinders) was used to quantitate trackability of cases employing fiducial markers. Automated lung tumor tracking algorithms often leverage the differences in benign and malignant lung tissue textures. These types of algorithms (e.g., soft-tissue localization - STiL) were simulated by designing a discrimination task, which quantifies the differentiation of tissue textures, measured experimentally and fit as a power-law in trend (with exponent β) using a cohort of MV images of patient lungs. The modeled MTF and NPS were used to investigate the effect of

SU-E-T-438: Commissioning of An In-Vivo Quality Assurance Method Using the Electronic Portal Imaging Device

International Nuclear Information System (INIS)

Morin, O; Held, M; Pouliot, J

2014-01-01

Purpose: Patient specific pre-treatment quality assurance (QA) using arrays of detectors or film have been the standard approach to assure the correct treatment is delivered to the patient. This QA approach is expensive, labor intensive and does not guarantee or document that all remaining fractions were treated properly. The purpose of this abstract is to commission and evaluate the performance of a commercially available in-vivo QA software using the electronic portal imaging device (EPID) to record the daily treatments. Methods: The platform EPIgray V2.0.2 (Dosisoft), which machine model compares ratios of TMR with EPID signal to predict dose was commissioned for an Artiste (Siemens Oncology Care Systems) and a Truebeam (Varian medical systems) linear accelerator following the given instructions. The systems were then tested on three different phantoms (homogeneous stack of solid water, anthropomorphic head and pelvis) and on a library of patient cases. Simple and complex fields were delivered at different exposures and for different gantry angles. The effects of the table attenuation and the EPID sagging were evaluated. Gamma analysis of the measured dose was compared to the predicted dose for complex clinical IMRT cases. Results: Commissioning of the EPIgray system for two photon energies took 8 hours. The difference between the dose planned and the dose measured with EPIgray was better than 3% for all phantom scenarios tested. Preliminary results on patients demonstrate an accuracy of 5% is achievable in high dose regions for both 3DCRT and IMRT. Large discrepancies (>5%) were observed due to metallic structures or air cavities and in low dose areas. Flat panel sagging was visible and accounted for in the EPIgray model. Conclusion: The accuracy achieved by EPIgray is sufficient to document the safe delivery of complex IMRT treatments. Future work will evaluate EPIgray for VMAT and high dose rate deliveries. This work is supported by Dosisoft, Cachan, France

NOTE: A method for controlling image acquisition in electronic portal imaging devices

Science.gov (United States)

Glendinning, A. G.; Hunt, S. G.; Bonnett, D. E.

2001-02-01

Certain types of camera-based electronic portal imaging devices (EPIDs) which initiate image acquisition based on sensing a change in video level have been observed to trigger unreliably at the beginning of dynamic multileaf collimation sequences. A simple, novel means of controlling image acquisition with an Elekta linear accelerator (Elekta Oncology Systems, Crawley, UK) is proposed which is based on illumination of a photodetector (ORP-12, Silonex Inc., Plattsburgh, NY, USA) by the electron gun of the accelerator. By incorporating a simple trigger circuit it is possible to derive a beam on/off status signal which changes at least 100 ms before any dose is measured by the accelerator. The status signal does not return to the beam-off state until all dose has been delivered and is suitable for accelerator pulse repetition frequencies of 50-400 Hz. The status signal is thus a reliable means of indicating the initiation and termination of radiation exposure, and thus controlling image acquisition of such EPIDs for this application.

Anisotropic ionizing radiation in Seyfert galaxies. I - The extended narrow-line region in Markarian 573

Science.gov (United States)

Tsvetanov, Zlatan; Walsh, J. R.

1992-01-01

The morphology, kinematics, and ionization state of the nuclear extended narrow-line region (ENLR) of the Seyfert 2 galaxy Mrk 573 are studied using narrow-band images of a grid of long-slit spectra. The entire ENLR is mapped spectroscopically, and velocity structure is studied. The velocity field map shows a typical galactic rotation picture with some important deviations. A simple geometric model, in accordance with the 'unified schemes', is employed to study the effects of various parameters of the observed picture. The best match is achieved when a biconical radiation field illuminates the ISM of the host galaxy that takes part in a normal galaxy rotation but also has radial motions close to the nucleus. The emission-line images reveal an ENLR elongated along the radio axis in the northwest-southeast direction, but a map of the flux ratio forbidden O III 5007/(H-alpha + forbidden N II) shows a different structure, with the highest excitation peak offset by about 4 arcsec along the radio axis to the southeast.

CHEERS Results on Mrk 573: A Study of Deep Chandra Observations

Science.gov (United States)

Paggi, Alessandro; Wang, Junfeng; Fabbiano, Giuseppina; Elvis, Martin; Karovska, Margarita

2012-09-01

We present results on Mrk 573 obtained as part of the CHandra survey of Extended Emission-line Regions in nearby Seyfert galaxies (CHEERS). Previous studies showed that this source features a biconical emission in the soft X-ray band closely related to the narrow-line region as mapped by the [O III] emission line and the radio emission, though on a smaller scale; we investigate the properties of soft X-ray emission from this source with new deep Chandra observations. Making use of the subpixel resolution of the Chandra/ACIS image and point-spread function deconvolution, we resolve and study substructures in each ionizing cone. The two cone spectra are fitted with a photoionization model, showing a mildly photoionized phase diffused over the bicone. Thermal collisional gas at about ~1.1 keV and ~0.8 keV appears to be located between the nucleus and the "knots" resolved in radio observations, and between the "arcs" resolved in the optical images, respectively; this can be interpreted in terms of shock interaction with the host galactic plane. The nucleus shows a significant flux decrease across the observations indicating variability of the active galactic nucleus (AGN), with the nuclear region featuring a higher ionization parameter with respect to the bicone region. The long exposure allows us to find extended emission up to ~7 kpc from the nucleus along the bicone axis. Significant emission is also detected in the direction perpendicular to the ionizing cones, disagreeing with the fully obscuring torus prescribed in the AGN unified model and suggesting instead the presence of a clumpy structure.

SU-F-T-260: Using Portal Image Device for Pre-Treatment QA in Volumetric Modulated Arc Plans with Flattening Filter Free (FFF) Beams

Energy Technology Data Exchange (ETDEWEB)

Qu, H; Qi, P; Yu, N; Xia, P [The Cleveland Clinic Foundation, Cleveland, OH (United States)

2016-06-15

Purpose: To implement and validate a method of using electronic portal image device (EPID) for pre-treatment quality assurance (QA) of volumetric modulated arc therapy (VMAT) plans using flattering filter free (FFF) beams for stereotactic body radiotherapy (SBRT). Methods: On Varian Edge with 6MV FFF beam, open field (from 2×2 cm to 20×20 cm) EPID images were acquired with 200 monitor unit (MU) at the image device to radiation source distance of 150cm. With 10×10 open field and calibration unit (CU) provided by vendor to EPID image pixel, a dose conversion factor was determined by dividing the center dose calculated from the treatment planning system (TPS) to the corresponding CU readout on the image. Water phantom measured beam profile and the output factors for various field sizes were further correlated to those of EPID images. The dose conversion factor and correction factors were then used for converting the portal images to the planner dose distributions of clinical fields. A total of 28 VMAT fields of 14 SBRT plans (8 lung, 2 prostate, 2 liver and 2 spine) were measured. With 10% low threshold cutoff, the delivered dose distributions were compared to the reference doses calculated in water phantom from the TPS. A gamma index analysis was performed for the comparison in percentage dose difference/distance-to-agreement specifications. Results: The EPID device has a linear response to the open fields with increasing MU. For the clinical fields, the gamma indices between the converted EPID dose distributions and the TPS calculated 2D dose distributions were 98.7%±1.1%, 94.0%±3.4% and 70.3%±7.7% for the criteria of 3%/3mm, 2%/2mm and 1%/1mm, respectively. Conclusion: Using a portal image device, a high resolution and high accuracy portal dosimerty was achieved for pre-treatment QA verification for SBRT VMAT plans with FFF beams.

Two-dimensional exit dosimetry using a liquid-filled electronic portal imaging device and a convolution model

International Nuclear Information System (INIS)

Boellaard, Ronald; Herk, Marcel van; Uiterwaal, Hans; Mijnheer, Ben

1997-01-01

Background and purpose: To determine the accuracy of two-dimensional exit dose measurements with an electronic portal imaging device, EPID, using a convolution model for a variety of clinically relevant situations. Materials and methods: Exit doses were derived from portal dose images, obtained with a liquid-filled EPID at distances of 50 cm or more behind the patient, by using a convolution model. The resulting on- and off-axis exit dose values were first compared with ionization chamber exit dose measurements for homogeneous and inhomogeneous phantoms in open and wedged 4,8 and 18 MV photon beams. The accuracy of the EPID exit dose measurements was then determined for a number of anthropomorphic phantoms (lung and larynx) irradiated under clinical conditions and for a few patients treated in an 8 MV beam. The latter results were compared with in vivo exit dose measurements using diodes. Results: The exit dose can be determined from portal images with an accuracy of 1.2% (1 SD) compared with ionization chamber measurements for open beams and homogeneous phantoms at all tested beam qualities. In the presence of wedges and for inhomogeneous phantoms the average relative accuracy slightly deteriorated to 1.7% (1 SD). For lung phantoms in a 4 MV beam a similar accuracy was obtained after refinement of our convolution model, which requires knowledge of the patient contour. Differences between diode and EPID exit dose measurements for an anthropomorphic lung phantom in an 8 MV beam were 2.5% at most, with an average agreement within 1% (1 SD). For larynx phantoms in a 4 MV beam exit doses obtained with an ionization chamber and EPID agreed within 1.5% (1 SD). Finally, exit doses in a few patients irradiated in an 8 MV beam could be determined with the EPID with an accuracy of 1.1% (1 SD) relative to exit dose measurements using diodes. Conclusions: Portal images, obtained with our EPID and analyzed with our convolution model, can be used to determine the exit dose

Use of Electronic Portal Image Detectors for Quality Assurance of Advanced Treatments

Energy Technology Data Exchange (ETDEWEB)

Moran, Jean M, E-mail: jmmoran@med.umich.ed [Department of Radiation Therapy, University of Michigan, 1500 E. Medical Center Drive, Ann Arbor MI 48109-0010 (United States)

2010-11-01

As the complexity of radiation therapy has increased, the need for quantitative dosimetric evaluation of treatment delivery has also increased. A growing number of investigations have expanded the use of EPIDs from anatomic applications to dosimetric verification. This work focuses on the applications of EPIDs for pre-treatment dosimetric verification of IMRT and intensity modulated arc therapy techniques. The advantages and disadvantages of these techniques are discussed along with methods to extrapolate to 3D dose verification applications.

A novel method for patient exit and entrance dose prediction based on water equivalent path length measured with an amorphous silicon electronic portal imaging device

Science.gov (United States)

Kavuma, Awusi; Glegg, Martin; Metwaly, Mohamed; Currie, Garry; Elliott, Alex

2010-01-01

In vivo dosimetry is one of the quality assurance tools used in radiotherapy to monitor the dose delivered to the patient. Electronic portal imaging device (EPID) images for a set of solid water phantoms of varying thicknesses were acquired and the data fitted onto a quadratic equation, which relates the reduction in photon beam intensity to the attenuation coefficient and material thickness at a reference condition. The quadratic model is used to convert the measured grey scale value into water equivalent path length (EPL) at each pixel for any material imaged by the detector. For any other non-reference conditions, scatter, field size and MU variation effects on the image were corrected by relative measurements using an ionization chamber and an EPID. The 2D EPL is linked to the percentage exit dose table, for different thicknesses and field sizes, thereby converting the plane pixel values at each point into a 2D dose map. The off-axis ratio is corrected using envelope and boundary profiles generated from the treatment planning system (TPS). The method requires field size, monitor unit and source-to-surface distance (SSD) as clinical input parameters to predict the exit dose, which is then used to determine the entrance dose. The measured pixel dose maps were compared with calculated doses from TPS for both entrance and exit depth of phantom. The gamma index at 3% dose difference (DD) and 3 mm distance to agreement (DTA) resulted in an average of 97% passing for the square fields of 5, 10, 15 and 20 cm. The exit dose EPID dose distributions predicted by the algorithm were in better agreement with TPS-calculated doses than phantom entrance dose distributions.

Light-reflection random-target method for measurement of the modulation transfer function of a digital video-camera

Czech Academy of Sciences Publication Activity Database

Pospíšil, Jaroslav; Jakubík, P.; Machala, L.

2005-01-01

Roč. 116, - (2005), s. 573-585 ISSN 0030-4026 Institutional research plan: CEZ:AV0Z10100522 Keywords : random-target measuring method * light-reflection white - noise target * digital video camera * modulation transfer function * power spectral density Subject RIV: BH - Optics, Masers, Lasers Impact factor: 0.395, year: 2005

Avaliação da expressão e amplificação da família do receptor de fator de crescimento epidérmico em colangiocarcinomas

Directory of Open Access Journals (Sweden)

Maria Olívia Ferreira Begnami

2014-10-01

Full Text Available Introdução: Colangiocarcinomas são neoplasias agressivas de origem no epitélio dos ductos biliares intra ou extra-hepáticos. Apresentam prognóstico sombrio e os esquemas usuais de quimioterapia geralmente mostram pouco benefício clínico. O tratamento com drogas antagonistas dos receptores de crescimento epidérmico tem apresentado boa resposta clínica no tratamento de carcinomas de origem em outros sítios como mama, pulmão e estômago. Poucos estudos prévios de literatura mostram a expressão ou amplificação dos genes desta família nos colangiocarcinomas. Objetivos: O objetivo deste estudo é determinar a frequência de expressão e amplificação dos genes da família dos receptores de crescimento epidérmico (EGFR, HER2, HER3 e HER4 nos colangiocarcinomas diagnosticados e tratados no Hospital AC Camargo através de imunoistoquímica e hibridização in situ (FISH e determinar possíveis correlações com achados clínicos e histopatológicos. Material e métodos: As reações imunoistoquímicas e de FISH estão sendo realizadas de acordo com os protocolos já estabelecidos no laboratório de imunoistoquímica e FISH do departamento de anatomia patológica do Hospital AC Camargo em lâminas representativas do tumor de 40 pacientes com diagnóstico de colangiocarcinoma no período de 1980 a 2006. A interpretação dos resultados segue as recomendações do fabricante e dos protocolos de interpretação do HER2 previamente estabelecidos para tumores de outras localizações. Resultados esperados: Espera-se com este estudo determinar a frequência de expressão e amplificação de EGFR, HER2, HER3 e HER4 e possíveis correlações com achados clínicos e histopatológicos dos colangiocarcinomas, identificando assim possíveis fatores prognósticos e alvos terapêuticos.

Curvelet-domain multiple matching method combined with cubic B-spline function

Science.gov (United States)

Wang, Tong; Wang, Deli; Tian, Mi; Hu, Bin; Liu, Chengming

2018-05-01

Since the large amount of surface-related multiple existed in the marine data would influence the results of data processing and interpretation seriously, many researchers had attempted to develop effective methods to remove them. The most successful surface-related multiple elimination method was proposed based on data-driven theory. However, the elimination effect was unsatisfactory due to the existence of amplitude and phase errors. Although the subsequent curvelet-domain multiple-primary separation method achieved better results, poor computational efficiency prevented its application. In this paper, we adopt the cubic B-spline function to improve the traditional curvelet multiple matching method. First, select a little number of unknowns as the basis points of the matching coefficient; second, apply the cubic B-spline function on these basis points to reconstruct the matching array; third, build constraint solving equation based on the relationships of predicted multiple, matching coefficients, and actual data; finally, use the BFGS algorithm to iterate and realize the fast-solving sparse constraint of multiple matching algorithm. Moreover, the soft-threshold method is used to make the method perform better. With the cubic B-spline function, the differences between predicted multiple and original data diminish, which results in less processing time to obtain optimal solutions and fewer iterative loops in the solving procedure based on the L1 norm constraint. The applications to synthetic and field-derived data both validate the practicability and validity of the method.

Hepatitis B vaccination: Efficiency of pretesting by RIA-methods

Energy Technology Data Exchange (ETDEWEB)

Hale, T I; Schmid, B

1984-04-01

Vaccination of individuals who possess antibodies against HBs virus from a previous infection is not necessary. Health-care personnel represents a large population of potential vaccine recipients. The risk of developing hepatitis B among these workers is proportional to the degree of their exposure to both blood and blood products as well as to patients with hepatitis B. The decision to screen before vaccination depends on the costs of screening, the costs of vaccination, and the likelihood of vaccination candidates having had hepatitis B. We have demonstrated the cost effective use of screening using RIA-methods in a group of health workers for anti-HBs. If care is taken in the organization of the vaccination program, prevaccination screening of vaccine candidates can save considerable amounts of money.

Application of conjugate gradient method to Commix-1B three-dimensional momentum equation

International Nuclear Information System (INIS)

King, J.B.; Domanus, H.

1987-01-01

Conjugate gradient method which is a special case of the variational method was implemented in the momentum section of the COMMIX-1B thermal hydraulics code. The comparisons between this method and the conventional iterative method of Successive Over Relation (S.O.R.) were made. Using COMMIX-1B, three steady state problems were analyzed. These problems were flow distribution in a scaled model of the Clinch River Fast Breeder Reactor outlet plenum, flow of coolant in the cold leg and downcomer of a PWR and isothermal air flow through a partially blocked pipe. It was found that if the conjugate gradient method is used, the execution time required to solve the resulting COMMIX-1B system of equations can be reduced by a factor of about 2 for the first two problems. For the isothermal air flow problem, the conjugate gradient method did not improve the execution time

WE-E-18A-08: Towards a Next-Generation Electronic Portal Device for Simultaneous Imaging and Dose Verification in Radiotherapy

International Nuclear Information System (INIS)

Blake, S; Vial, P; Holloway, L; Kuncic, Z

2014-01-01

Purpose: This work forms part of an ongoing study to develop a next-generation electronic portal imaging device (EPID) for simultaneous imaging and dose verification in radiotherapy. Monte Carlo (MC) simulations were used to characterize the imaging performance of a novel EPID that has previously been demonstrated to exhibit a water-equivalent response. The EPID ' s response was quantified in several configurations and model parameters were empirically validated against experimental measurements. Methods: A MC model of a novel a-Si EPID incorporating an array of plastic scintillating fibers was developed. Square BCF-99-06A scintillator fibers with PMMA cladding (Saint-Gobain Crystals) were modelled in a matrix with total area measuring 150×150 mm 2 . The standard electromagnetic and optical physics Geant4 classes were used to simulate radiation transport from an angled slit source (6 MV energy spectrum) through the EPID and optical photons reaching the photodiodes were scored. The prototype's modulation transfer function (MTF) was simulated and validated against experimental measurements. Several optical transport parameters, fiber lengths and thicknesses of an air gap between the scintillator and photodiodes were investigated to quantify their effects on the prototype's detection efficiency, sensitivity and MTF. Results: Simulated EPID response was more sensitive to variations in geometry than in the optical parameters studied. The MTF was particularly sensitive to the introduction of a 0.5–1.0 mm air gap between the scintillator and photodiodes, which lowered the MTF relative to that simulated without the gap. As expected, increasing the fiber length increased the detector efficiency and sensitivity while decreasing the MTF. Conclusion: A model of a novel water-equivalent EPID has been developed and benchmarked against measurements using a physical prototype. We have demonstrated the feasibility of this new device and are continuing to optimize

Dosimetric properties of an amorphous silicon electronic portal imaging device for verification of dynamic intensity modulated radiation therapy

International Nuclear Information System (INIS)

Greer, Peter B.; Popescu, Carmen C.

2003-01-01

Dosimetric properties of an amorphous silicon electronic portal imaging device (EPID) for verification of dynamic intensity modulated radiation therapy (IMRT) delivery were investigated. The EPID was utilized with continuous frame-averaging during the beam delivery. Properties studied included effect of buildup, dose linearity, field size response, sampling of rapid multileaf collimator (MLC) leaf speeds, response to dose-rate fluctuations, memory effect, and reproducibility. The dependence of response on EPID calibration and a dead time in image frame acquisition occurring every 64 frames were measured. EPID measurements were also compared to ion chamber and film for open and wedged static fields and IMRT fields. The EPID was linear with dose and dose rate, and response to MLC leaf speeds up to 2.5 cm s-1 was found to be linear. A field size dependent response of up to 5% relative to d max ion-chamber measurement was found. Reproducibility was within 0.8% (1 standard deviation) for an IMRT delivery recorded at intervals over a period of one month. The dead time in frame acquisition resulted in errors in the EPID that increased with leaf speed and were over 20% for a 1 cm leaf gap moving at 1.0 cm s-1. The EPID measurements were also found to depend on the input beam profile utilized for EPID flood-field calibration. The EPID shows promise as a device for verification of IMRT, the major limitation currently being due to dead-time in frame acquisition

Method of 10B determination in biological specimens

International Nuclear Information System (INIS)

Nikitina, R.G.; Frolova, E.I.

1981-01-01

The paper is concerned with the methods of 10 B determination in biological specimens (blood, skin and tissues of rats). On the basis of investigations conducted there have been proposed films based on cellulose triacetate with optimal characteristics in terms of their possible utilization as solid detectors to record α-particles and recoil nuclei. The conditions of film staining are also discussed

Partial molar volumes of organic solutes in water. XXIV. Selected alkane-α,ω-diols at temperatures T = 298 K to 573 K and pressures up to 30 MPa

International Nuclear Information System (INIS)

Cibulka, Ivan; Hnědkovský, Lubomír

2013-01-01

Highlights: • Standard molar volumes of three alkane-α,ω-diols (C 5 , C 8 , C 9 ) in water are presented. • Data were obtained in the range T from (298 to 573) K and p up to 30 MPa. • Dependences on carbon atom number, temperature, and pressure are analysed. -- Abstract: Density data for dilute aqueous solutions of three alkane-α,ω-diols (pentane-1,5-diol, octane-1,8-diol, nonane-1,9-diol) are presented together with standard molar volumes (partial molar volumes at infinite dilution) calculated from the experimental data. The measurements were performed at temperatures from T = 298 K up to T = 573 K. Experimental pressures were slightly above the saturation vapour pressure of water, and (15 and 30) MPa. The data were obtained using a high-temperature high-pressure flow vibrating-tube densimeter. Measured standard molar volumes were combined with data previously published for other members of the homologous series and discussed. Experimental standard molar volumes were correlated as a function of temperature and pressure using an empirical polynomial function. Dependences of standard molar volumes on temperature and pressure were analysed. Contributions of the methylene group to the standard molar volume were also evaluated and discussed

Hepatitis B vaccination: Efficiency of pretesting by RIA-methods

International Nuclear Information System (INIS)

Hale, T.I.; Schmid, B.

1984-01-01

Vaccination of individuals who possess antibodies against HBs virus from a previous infection is not necessary. Health-care personnel represents a large population of potential vaccine recipients. The risk of developing hepatitis B among these workers is proportional to the degree of their exposure to both blood and blood products as well as to patients with hepatitis B. The decision to screen before vaccination depends on the costs of screening, the costs of vaccination, and the likelihood of vaccination candidates having had hepatitis B. We have demonstrated the cost effective use of screening using RIA-methods in a group of health workers for anti-HBs. If care is taken in the organization of the vaccination program, prevaccination screening of vaccine candidates can save considerable amounts of money. (orig.) [de

Caracterización fenotípica de cepas invasivas de Neisseria meningitidis aisladas en Cuba durante 20 años

Directory of Open Access Journals (Sweden)

Isabel Martínez

2006-04-01

Full Text Available Se investigaron los marcadores epidemiológicos (serogrupos, serotipos, subtipos, inmunotipos de 429 cepas invasivas, aisladas en Cuba durante 20 años (1982-2002. Basándonos en el comportamiento de la incidencia de la Enfermedad Meningocócica (EM en el período investigado, las cepas se distribuyeron en dos etapas: epidémica y postepidémica. La epidémica, comprendió 279 cepas aisladas entre 1982-1992 y la ostepidémica, incluyó 150 aislamientos pertenecientes al período comprendido entre 1993-2002. Todas se cultivaron en Agar Mueller Hinton con suero fetal bovino (5% y se incubaron 24-48 horas, 37 0C, en atmósfera húmeda con 5% de C02. La identificación de género, especie y serogrupo, se realizó mediante métodos convencionales; para la caracterización de los sero/subtipos e inmunotipos, se utilizó el ensayo inmunoenzimático (ELISA de células enteras con anticuerpos monoclonales. En ambas etapas predominó el serogrupo B (97,90%: epidémica (96,77% y postepidémica (100%. Sin embargo, el serogrupo C (1,43% y cepas no agrupables (1,8%, sólo se observaron en aislamientos de la etapa epidémica. Los otros marcadores prevalentes fueron: serotipo 4 (86,48%, subtipo P1.19,15 (78,32%, inmunotipo L3,7,9 (90,2% , todos mostraron cifras similares en ambos períodos.Predominó el fenotipo B:4:P1.19,15:L3,7,9 (69,69%, aunque, en la etapa postepidémica (77,34%, el porcentaje fue superior al de la etapa epidémica (65,66% (p<0,05; además, en las cepas de este período, se observó una mayor diversidad de asociaciones fenotípicas. Los resultados obtenidos de esta caracterización fenotípica de las cepas de Neisseria meningitidis aisladas de enfermos aporta datos valiosos al estudio, prevención y control exitoso de la EM en Cuba.

New method to incorporate Type B uncertainty into least-squares procedures in radionuclide metrology

International Nuclear Information System (INIS)

Han, Jubong; Lee, K.B.; Lee, Jong-Man; Park, Tae Soon; Oh, J.S.; Oh, Pil-Jei

2016-01-01

We discuss a new method to incorporate Type B uncertainty into least-squares procedures. The new method is based on an extension of the likelihood function from which a conventional least-squares function is derived. The extended likelihood function is the product of the original likelihood function with additional PDFs (Probability Density Functions) that characterize the Type B uncertainties. The PDFs are considered to describe one's incomplete knowledge on correction factors being called nuisance parameters. We use the extended likelihood function to make point and interval estimations of parameters in the basically same way as the least-squares function used in the conventional least-squares method is derived. Since the nuisance parameters are not of interest and should be prevented from appearing in the final result, we eliminate such nuisance parameters by using the profile likelihood. As an example, we present a case study for a linear regression analysis with a common component of Type B uncertainty. In this example we compare the analysis results obtained from using our procedure with those from conventional methods. - Highlights: • A new method proposed to incorporate Type B uncertainty into least-squares method. • The method constructed from the likelihood function and PDFs of Type B uncertainty. • A case study performed to compare results from the new and the conventional method. • Fitted parameters are consistent but with larger uncertainties in the new method.

17 CFR 275.203(b)(3)-2 - Methods for counting clients in certain private funds.

Science.gov (United States)

2010-04-01

... 17 Commodity and Securities Exchanges 3 2010-04-01 2010-04-01 false Methods for counting clients....203(b)(3)-2 Methods for counting clients in certain private funds. (a) For purposes of section 203(b)(3) of the Act (15 U.S.C. 80b-3(b)(3)), you must count as clients the shareholders, limited partners...

Characterization of a high-elbow, fluoroscopic electronic portal imaging device for portal dosimetry

International Nuclear Information System (INIS)

Boer, J.C.J. de; Visser, A.G.

2000-01-01

The application of a newly developed fluoroscopic (CCD-camera based) electronic portal imaging device (EPID) in portal dosimetry is investigated. A description of the EPID response to dose is presented in terms of stability, linearity and optical cross-talk inside the mechanical structure. The EPID has a relatively large distance (41 cm on-axis) between the fluorescent screen and the mirror (high-elbow), which results in cross-talk with properties quite different from that of the low-elbow fluoroscopic EPIDs that have been studied in the literature. In contrast with low-elbow systems, the maximum cross-talk is observed for points of the fluorescent screen that have the largest distance to the mirror, which is explained from the geometry of the system. An algorithm to convert the images of the EPID into portal dose images (PDIs) is presented. The correction applied for cross-talk is a position-dependent additive operation on the EPID image pixel values, with a magnitude that depends on a calculated effective field width. Deconvolution with a point spread function, as applied for low-elbow systems, is not required. For a 25 MV beam, EPID PDIs and ionization chamber measurements in the EPID detector plane were obtained behind an anthropomorphic phantom and a homogeneous absorber for various field shapes. The difference in absolute dose between the EPID and ionization chamber measurements, averaged over the four test fields presented in this paper, was 0.1±0.5% (1 SD) over the entire irradiation field, with no deviation larger than 2%. (author)

Research on design methods and aerodynamics performance of CQUDTU-B21 airfoil

DEFF Research Database (Denmark)

Chen, Jin; Cheng, Jiangtao; Wen, Zhong Shen

2012-01-01

This paper presents the design methods of CQU-DTU-B21 airfoil for wind turbine. Compared with the traditional method of inverse design, the new method is described directly by a compound objective function to balance several conflicting requirements for design wind turbine airfoils, which based...... on design theory of airfoil profiles, blade element momentum (BEM) theory and airfoil Self-Noise prediction model. And then an optimization model with the target of maximum power performance on a 2D airfoil and low noise emission of design ranges for angle of attack has been developed for designing CQU......-DTU-B21 airfoil. To validate the optimization results, the comparison of the aerodynamics performance by XFOIL and wind tunnels test respectively at Re=3×106 is made between the CQU-DTU-B21 and DU93-W-210 which is widely used in wind turbines. © (2012) Trans Tech Publications, Switzerland....

A novel approach to EPID-based 3D volumetric dosimetry for IMRT and VMAT QA

Science.gov (United States)

Alhazmi, Abdulaziz; Gianoli, Chiara; Neppl, Sebastian; Martins, Juliana; Veloza, Stella; Podesta, Mark; Verhaegen, Frank; Reiner, Michael; Belka, Claus; Parodi, Katia

2018-06-01

Intensity modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT) are relatively complex treatment delivery techniques and require quality assurance (QA) procedures. Pre-treatment dosimetric verification represents a fundamental QA procedure in daily clinical routine in radiation therapy. The purpose of this study is to develop an EPID-based approach to reconstruct a 3D dose distribution as imparted to a virtual cylindrical water phantom to be used for plan-specific pre-treatment dosimetric verification for IMRT and VMAT plans. For each depth, the planar 2D dose distributions acquired in air were back-projected and convolved by depth-specific scatter and attenuation kernels. The kernels were obtained by making use of scatter and attenuation models to iteratively estimate the parameters from a set of reference measurements. The derived parameters served as a look-up table for reconstruction of arbitrary measurements. The summation of the reconstructed 3D dose distributions resulted in the integrated 3D dose distribution of the treatment delivery. The accuracy of the proposed approach was validated in clinical IMRT and VMAT plans by means of gamma evaluation, comparing the reconstructed 3D dose distributions with Octavius measurement. The comparison was carried out using (3%, 3 mm) criteria scoring 99% and 96% passing rates for IMRT and VMAT, respectively. An accuracy comparable to the one of the commercial device for 3D volumetric dosimetry was demonstrated. In addition, five IMRT and five VMAT were validated against the 3D dose calculation performed by the TPS in a water phantom using the same passing rate criteria. The median passing rates within the ten treatment plans was 97.3%, whereas the lowest was 95%. Besides, the reconstructed 3D distribution is obtained without predictions relying on forward dose calculation and without external phantom or dosimetric devices. Thus, the approach provides a fully automated, fast and easy QA

Multivariate analysis methods to tag b quark events at LEP/SLC

International Nuclear Information System (INIS)

Brandl, B.; Falvard, A.; Guicheney, C.; Henrard, P.; Jousset, J.; Proriol, J.

1992-01-01

Multivariate analyses are applied to tag Z → bb-bar events at LEP/SLC. They are based on the specific b-event shape caused by the large b-quark mass. Discriminant analyses, classification trees and neural networks are presented and their performances are compared. It is shown that the neural network approach, due to its non-linearity, copes best with the complexity of the problem. As an example for an application of the developed methods the measurement of Γ(Z → bb-bar) is discussed. The usefulness of methods based on the global event shape is limited by the uncertainties introduced by the necessity of event simulation. As solution a double tag method is presented which can be applied to many tasks of LEP/SLC heavy flavour physics. (author) 29 refs.; 6 figs.; 1 tab

An evaluation of setup uncertainties for patients treated to pelvic sites

International Nuclear Information System (INIS)

Hunt, Margie A.; Schultheiss, Timothy E.; Desobry, Gregory E.; Hakki, Morgan; Hanks, Gerald E.

1995-01-01

Purpose: Successful delivery of conformal fields requires stringent immobilization and treatment verification, as well as knowledge of the setup reproducibility. The purpose of this study was to compare the three-dimensional distribution of setup variations for patients treated to pelvic sites with electronic portal imaging devices (EPID) and portal film. Methods and Materials: Nine patients with genitourinary and gynecological cancers immobilized with custom casts and treated with a four-field whole-pelvis technique were imaged daily using an EPID and filmed once every five to seven treatments. The three-dimensional translational and rotational setup errors were determined using a technique that relies on anatomical landmarks identified on simulation and treatment images. The distributions of the translational and rotational variations in each dimension as well as the total displacement of the treatment isocenter from the simulation isocenter were determined. Results: Grouped analysis of all patients revealed average unidirectional translational deviations of less than 2 mm and a standard deviation of 5.3 mm. The average total undirected distance between the treatment and simulated isocenters was 8.3 mm with a standard deviation of 5 mm. Individual patient analysis revealed eight of nine patients had statistically significant nonzero mean translational variations (p < 0.05). Translational variations measured with film were an average of 1.4 mm less than those measured with EPID, but this difference was not statistically significant. Conclusion: Translational variations measured in this study are in general agreement with previous studies. The use of the EPID in this study was less intrusive and may have resulted in less additional attention being given each imaging setup. This may explain the slightly larger average translational variations observed with EPID vs. film, and suggests that the use of EPIDs is a superior method for assessing the true extent of setup

Method for In-vivo Synthetic Aperture B-flow Imaging

DEFF Research Database (Denmark)

Jensen, Jørgen Arendt

2004-01-01

. The signal received by the 64 elements closets to the en-fission are sampled at 40 MHz and 12 bits at a pulse repetition frequency of 3 kHz. A full second of data is acquired from a healthy 29 years old male volunteer from the carotid artery. The data is beamformed, combined, and echo canceled off-line. High-pass......B-flow techniques introduced in commercial scanners have been useful is visualizing places of flow. The method is relatively independent of flow angle and can give a good perception of vessel location and turbulence. This paper introduces a technique for making a synthetic aperture B-flow system...

Application of a practical method for the isocenter point in vivo dosimetry by a transit signal

International Nuclear Information System (INIS)

Piermattei, Angelo; Fidanzio, Andrea; Azario, Luigi

2007-01-01

This work reports the results of the application of a practical method to determine the in vivo dose at the isocenter point, D iso , of brain thorax and pelvic treatments using a transit signal S t . The use of a stable detector for the measurement of the signal S t (obtained by the x-ray beam transmitted through the patient) reduces many of the disadvantages associated with the use of solid-state detectors positioned on the patient as their periodic recalibration, and their positioning is time consuming. The method makes use of a set of correlation functions, obtained by the ratio between S t and the mid-plane dose value, D m , in standard water-equivalent phantoms, both determined along the beam central axis. The in vivo measurement of D iso required the determination of the water-equivalent thickness of the patient along the beam central axis by the treatment planning system that uses the electron densities supplied by calibrated Hounsfield numbers of the computed tomography scanner. This way it is, therefore, possible to compare D iso with the stated doses, D iso,TPS , generally used by the treatment planning system for the determination of the monitor units. The method was applied in five Italian centers that used beams of 6 MV, 10 MV, 15 MV x-rays and 60 Co γ-rays. In particular, in four centers small ion-chambers were positioned below the patient and used for the S t measurement. In only one center, the S t signals were obtained directly by the central pixels of an EPID (electronic portal imaging device) equipped with commercial software that enabled its use as a stable detector. In the four centers where an ion-chamber was positioned on the EPID, 60 pelvic treatments were followed for two fields, an anterior-posterior or a posterior-anterior irradiation and a lateral-lateral irradiation. Moreover, ten brain tumors were checked for a lateral-lateral irradiation, and five lung tumors carried out with three irradiations with different gantry angles were

Dosimetric verification of radiation therapy including intensity modulated treatments, using an amorphous-silicon electronic portal imaging device

Science.gov (United States)

Chytyk-Praznik, Krista Joy

Radiation therapy is continuously increasing in complexity due to technological innovation in delivery techniques, necessitating thorough dosimetric verification. Comparing accurately predicted portal dose images to measured images obtained during patient treatment can determine if a particular treatment was delivered correctly. The goal of this thesis was to create a method to predict portal dose images that was versatile and accurate enough to use in a clinical setting. All measured images in this work were obtained with an amorphous silicon electronic portal imaging device (a-Si EPID), but the technique is applicable to any planar imager. A detailed, physics-motivated fluence model was developed to characterize fluence exiting the linear accelerator head. The model was further refined using results from Monte Carlo simulations and schematics of the linear accelerator. The fluence incident on the EPID was converted to a portal dose image through a superposition of Monte Carlo-generated, monoenergetic dose kernels specific to the a-Si EPID. Predictions of clinical IMRT fields with no patient present agreed with measured portal dose images within 3% and 3 mm. The dose kernels were applied ignoring the geometrically divergent nature of incident fluence on the EPID. A computational investigation into this parallel dose kernel assumption determined its validity under clinically relevant situations. Introducing a patient or phantom into the beam required the portal image prediction algorithm to account for patient scatter and attenuation. Primary fluence was calculated by attenuating raylines cast through the patient CT dataset, while scatter fluence was determined through the superposition of pre-calculated scatter fluence kernels. Total dose in the EPID was calculated by convolving the total predicted incident fluence with the EPID-specific dose kernels. The algorithm was tested on water slabs with square fields, agreeing with measurement within 3% and 3 mm. The

Local IgG synthesis in three pediatric patients with cuban epidemic neuropathy Sintesis local de IgG en tres pacientes pediátricos com neuropatía epidêmica cubana

Directory of Open Access Journals (Sweden)

Alberto Dorta-Contreras

1996-03-01

Full Text Available Three pediatric patients with Cuban epidemic neuropathy were studied. Cerebrospinal fluid and sera were simultaneously obtained. Albumin and IgG were quantified by immunodifusion. Albumin quotient and local synthesis of IgG were calculated by Reiber/Felgenhauer formula. A patient with optic neuritis had a dysfunction of the blood-cerebrospinal fluid barrier. All the group had local synthesis of IgG.Se estudiaron tres pacientes pediátricos con neuropatia epidêmica cubana. Se obtuvieron suero y liquido cefalorraquídeo simultaneamente. Se cuantificaran los niveles de albúmina e IgG por inmunodifusion radial. Se calculo la razón albúmina y la fórmula de Reiber/Felgenhauer. Un paciente con neuritis óptica tuvo una disfunción de la barrera sangre-líquido cefaloraquídeo. Todo el grupo tuvo síntesis local de IgG.

Etude séro-epidémiologique de trois infections sexuellement transmissibles (Chlamydia Trachomatis, Hépatite B, Syphilis): cas de l’Hôpital de District de Nkoldongo à Yaoundé

Science.gov (United States)

Essome, Marie Chantal Ngonde; Nsawir, Bonglaisin Julius; Nana, Rodrigue Dongang; Molu, Patrick; Mohamadou, Mansour

2016-01-01

are still frequent in developing countries and particularly in Cameroon. The aim of this study was to determine the distribution of the following sexually transmitted infections: viral hepatitis B, Chlamydia trachomatis and syphilis in a population of women spontaneously visiting the Nkoldongo District Hospital in Yaoundé as well as to evaluate possible co-infections among these three conditions and to bring out women’s prior knowledge of how sexual transmission occurs. Methods We conducted a prospective and descriptive study including 182 women aged between 18 and 48 years. These women underwent serologic testing for Chlamydia trachomatis with ELISA (General Biological Corp laboratory test kit. Hepatitis B virus was detected using immunochromatographic method (Human laboratory kit) while syphilis was detected using RPR agglutination (Biocentric Laboratories kit )and TPHA agglutination (Human laboratory kit) method. Results Our results showed that the distribution of Chlamydia trachomatis, viral hepatitis B and syphilis was 22.52%, 4.39%, 0.54% respectively. Moreover, we reported a Chlamydia trachomatis and Viral hepatitis B coinfection rate of 2.74%. In addition, Chlamydia trachomatis reinfection was detected in 4.94% of cases. Regarding the mode of transmission of these infections, 67.57% and 70.87% of women didn’t know how Chlamydia trachomatis and viral hepatitis sexual transmission could occur respectively, while 91.2% of women knew how was syphilis spread. Conclusion The diagnosis of chlamydia trachomatis infection should prompt screening for viral hepatitis B. PMID:28293360

Set up of analytical methods for evaluation of specifications of recombinant Hepatitis-B vaccine

Directory of Open Access Journals (Sweden)

Daram M

2009-06-01

Full Text Available "nBackground: Hepatitis B vaccination has been included in routine immunization of all individuals according to WHO recommendations since 1991. Despite successful coverage, 3-5% of recipients fail to mount a desirable protection level of Ab. Vaccine failure results from: emergence of mutation, immune failure of individuals, decrease in vaccine potency, and etc. The quality of Hepatitis B vaccine should be evaluated by a reliable method. "n"nMethods: The amount of vaccine antigen was measured through the in vitro assay of Hepatitis B vaccines which consists of multiple dilutions of the reference material and samples. The preparations were evaluated by Elisa to determine the amount of HBsAg. The data were analyzed by parallel-line analysis software. The in vivo assay was performed by inoculating multiple doses of the reference and sample preparations in Balb/c mice. A control group was also inoculated with vaccine matrix. Four weeks later, the mice sera were evaluated to determine the presence of antibodies against Hepatitis B by Elisa method. The data were analyzed by Probit analysis software. "n"nResults: Both methods were set up in our laboratory by which different batches of Hepatitis B vaccine were evaluated. It was observed that In vivo and In vitro methods provide comparable results. Therefore we can use the in vitro method for routine testing of HB vaccine quality control. "n"nConclusion: In vitro method can be used in place of In vivo method because of its time and cost-effectiveness. Moreover, since no animals are used in in vitro method, it complies well with the 3R concept (Reduction, Refinement, and Replacement of animal testing and the current tendency to use alternative method.

Random magnetic anisotropy in thin films of amorphous Mn48B52

International Nuclear Information System (INIS)

Kistenmacher, T.J.; Bryden, W.A.; Moorjani, K.

1989-01-01

While crystalline MnB is a ferromagnet (T c =573 K), rf diode-sputtered thin films of composition Mn 48 B 52 are amorphous as ascertained by x-ray scattering and exhibit a low-field, hysteretic, static magnetization peak characteristic of a spin glass. High-field (up to 44 kG) static magnetization data at temperatures ranging between 6 and 200 K are analyzed within the random anisotropy model of Chudnovsky, Saslow, and Serota [Phys. Rev. B 33, 251 (1986)]. In this model, the field-dependent magnetization at a given temperature is expressed as M(H)=M(0)(1-CH -1/2 )+χ'H, where the lead term follows from the analysis of a ferromagnet with a wandering axis (FWA) and the second term accounts for contributions from induced moments. The T 3/2 dependence of the saturation magnetization of the FWA contribution, M(0), at low temperatures is suggestive of spin-wave excitations, while the temperature dependence of the fitting parameters C and χ' consistently identify several characteristic temperatures associated with the magnetic behavior of a-Mn 48 B 52 , including the low-field spin-glass transition temperature and Curie temperature and the curvature crossover temperature (established from a classical Arrott plot) that separates the FWA state and a pseudoparamagnetic limit

Estudios morfológicos y taxonómicos en Blechnum (Blechnaceae-Pteridophyta: B. tabulare y B. magellanicum

Directory of Open Access Journals (Sweden)

Rolleri, Cristina H.

2008-12-01

Full Text Available Specimens of B. tabulare and B. magellanicum from their whole geographical area were studied, and taxa were treated as different species. The following characters were analyzed: rhizomes, rhizomatic scales, stipes, division of dimorphic laminae, outline, texture, size, margins, indument, venation, epidermal patterns, stomata (size and density, mesophyll of pinnae in transversal section, mucilaginiferous unicellular glands of axes and laminae, and spores. Habit of plants, type of rhizome, rhizomatic scales, mucilage glands, and type of ornamentation of the perispore are characters shared by the two species, while the other traits vary at the specific level, allowing them to be identified as two separate taxa. Blechnum tabulare is distributed in the tropics and subtropics of South America, África, and Islands of the Atlantic and Indic Oceans, while B. magellanicum is a subantarctic, more restricted species, that grows in humid areas of Argentina and Chile, South America. New descriptions of both species are given, along with comments on their affinities with other arborescent species of the genus.Especímenes de B. tabulare y B. magellanicum procedentes de toda su área de distribución fueron estudiados en detalle y considerados especies diferentes. Se estudiaron los siguientes caracteres: rizomas, escamas rizomáticas, estípites, división de las láminas dimórficas, contorno, textura, tamaño, margen, indumento, venación, modelo epidérmico, estomas (densidad y dimensiones, mesofilo de las pinnas estériles en sección transversal y esporas. El hábito de las plantas, el tipo de rizoma, las escamas rizomáticas y el tipo de ornamentación del perisporio son rasgos compartidos por ambos táxones, pero los restantes caracteres varían en el nivel específico y permiten distinguirlos como especies diferentes. Blechnum tabulare se distribuye en los trópicos y subtrópicos de Sudamérica, África e islas de los océanos Atlántico e �

Validação de métodos cromatográficos por clae para análise das vitaminas B1, B2, B6 e niacina naturalmente presentes em farinha de cereais Validation of hplc methods for analysis of vitamins B1, B2, B6 and niacin naturally present in cereal flours

Directory of Open Access Journals (Sweden)

Ana Elisa Ferreira Presoto

2008-01-01

Full Text Available Complex B vitamins are present in some cereal foods and the ingestion of enriched products contributes to the recommended dietary intake of these micronutrients. To adapt the label of some products, it is necessary to develop and validate the analytical methods. These methods must be reliable and with enough sensitivity to analyze complex B vitamins naturally present in food at low concentration. The purpose of this work is to evaluate, with validated methods, the content of vitamins B1, B2, B6 and niacin in five cereal flours used in food industry (oat, rice, barley, corn and wheat.

Organizational Learning Supported by Machine Learning Models Coupled with General Explanation Methods: A Case of B2B Sales Forecasting

Directory of Open Access Journals (Sweden)

Bohanec Marko

2017-08-01

Full Text Available Background and Purpose: The process of business to business (B2B sales forecasting is a complex decision-making process. There are many approaches to support this process, but mainly it is still based on the subjective judgment of a decision-maker. The problem of B2B sales forecasting can be modeled as a classification problem. However, top performing machine learning (ML models are black boxes and do not support transparent reasoning. The purpose of this research is to develop an organizational model using ML model coupled with general explanation methods. The goal is to support the decision-maker in the process of B2B sales forecasting.

Limit on B$^{0}_{s}$ oscillation using a jet charge method

CERN Document Server

Buskulic, Damir; De Bonis, I; Décamp, D; Ghez, P; Goy, C; Lees, J P; Lucotte, A; Minard, M N; Odier, P; Pietrzyk, B; Ariztizabal, F; Chmeissani, M; Crespo, J M; Efthymiopoulos, I; Fernández, E; Fernández-Bosman, M; Gaitan, V; Garrido, L; Martínez, M; Orteu, S; Pacheco, A; Padilla, C; Palla, Fabrizio; Pascual, A; Perlas, J A; Sánchez, F; Teubert, F; Colaleo, A; Creanza, D; De Palma, M; Farilla, A; Gelao, G; Girone, M; Iaselli, Giuseppe; Maggi, G; Maggi, M; Marinelli, N; Natali, S; Nuzzo, S; Ranieri, A; Raso, G; Romano, F; Ruggieri, F; Selvaggi, G; Silvestris, L; Tempesta, P; Zito, G; Huang, X; Lin, J; Ouyang, Q; Wang, T; Xie, Y; Xu, R; Xue, S; Zhang, J; Zhang, L; Zhao, W; Bonvicini, G; Cassel, David G; Cattaneo, M; Comas, P; Coyle, P; Drevermann, H; Engelhardt, A; Forty, Roger W; Frank, M; Hagelberg, R; Harvey, J; Jacobsen, R; Janot, P; Jost, B; Knobloch, J; Lehraus, Ivan; Markou, C; Martin, E B; Mato, P; Mattison, T S; Meinhard, H; Minten, Adolf G; Miquel, R; Moffeit, K; Oest, T; Palazzi, P; Pater, J R; Pusztaszeri, J F; Ranjard, F; Rensing, P E; Rolandi, Luigi; Schlatter, W D; Schmelling, M; Schneider, O; Tejessy, W; Tomalin, I R; Venturi, A; Wachsmuth, H W; Wiedenmann, W; Wildish, T; Witzeling, W; Wotschack, J; Ajaltouni, Ziad J; Bardadin-Otwinowska, Maria; Barrès, A; Boyer, C; Falvard, A; Gay, P; Guicheney, C; Henrard, P; Jousset, J; Michel, B; Monteil, S; Montret, J C; Pallin, D; Perret, P; Podlyski, F; Proriol, J; Rossignol, J M; Saadi, F; Fearnley, Tom; Hansen, J B; Hansen, J D; Hansen, J R; Hansen, P H; Nilsson, B S; Kyriakis, A; Simopoulou, Errietta; Siotis, I; Vayaki, Anna; Zachariadou, K; Blondel, A; Bonneaud, G R; Brient, J C; Bourdon, P; Passalacqua, L; Rougé, A; Rumpf, M; Tanaka, R; Valassi, Andrea; Verderi, M; Videau, H L; Candlin, D J; Parsons, M I; Focardi, E; Parrini, G; Corden, M; Delfino, M C; Georgiopoulos, C H; Jaffe, D E; Antonelli, A; Bencivenni, G; Bologna, G; Bossi, F; Campana, P; Capon, G; Chiarella, V; Felici, G; Laurelli, P; Mannocchi, G; Murtas, F; Murtas, G P; Pepé-Altarelli, M; Dorris, S J; Halley, A W; ten Have, I; Knowles, I G; Lynch, J G; Morton, W T; O'Shea, V; Raine, C; Reeves, P; Scarr, J M; Smith, K; Smith, M G; Thompson, A S; Thomson, F; Thorn, S; Turnbull, R M; Becker, U; Braun, O; Geweniger, C; Graefe, G; Hanke, P; Hepp, V; Kluge, E E; Putzer, A; Rensch, B; Schmidt, M; Sommer, J; Stenzel, H; Tittel, K; Werner, S; Wunsch, M; Beuselinck, R; Binnie, David M; Cameron, W; Colling, D J; Dornan, Peter J; Konstantinidis, N P; Moneta, L; Moutoussi, A; Nash, J; San Martin, G; Sedgbeer, J K; Stacey, A M; Dissertori, G; Girtler, P; Kneringer, E; Kuhn, D; Rudolph, G; Bowdery, C K; Brodbeck, T J; Colrain, P; Crawford, G; Finch, A J; Foster, F; Hughes, G; Sloan, Terence; Whelan, E P; Williams, M I; Galla, A; Greene, A M; Kleinknecht, K; Quast, G; Raab, J; Renk, B; Sander, H G; Wanke, R; Zeitnitz, C; Aubert, Jean-Jacques; Bencheikh, A M; Benchouk, C; Bonissent, A; Bujosa, G; Calvet, D; Carr, J; Diaconu, C A; Etienne, F; Thulasidas, M; Nicod, D; Payre, P; Rousseau, D; Talby, M; Abt, I; Assmann, R W; Bauer, C; Blum, Walter; Brown, D; Dietl, H; Dydak, Friedrich; Ganis, G; Gotzhein, C; Jakobs, K; Kroha, H; Lütjens, G; Lutz, Gerhard; Männer, W; Moser, H G; Richter, R H; Rosado-Schlosser, A; Schwarz, A; Settles, Ronald; Seywerd, H C J; Stierlin, U; Saint-Denis, R; Wolf, G; Alemany, R; Boucrot, J; Callot, O; Cordier, A; Courault, F; Davier, M; Duflot, L; Grivaz, J F; Heusse, P; Jacquet, M; Kim, D W; Le Diberder, F R; Lefrançois, J; Lutz, A M; Musolino, G; Nikolic, I A; Park, H J; Park, I C; Schune, M H; Simion, S; Veillet, J J; Videau, I; Abbaneo, D; Azzurri, P; Bagliesi, G; Batignani, G; Bettarini, S; Bozzi, C; Calderini, G; Carpinelli, M; Ciocci, M A; Ciulli, V; Dell'Orso, R; Fantechi, R; Ferrante, I; Foà, L; Forti, F; Giassi, A; Giorgi, M A; Gregorio, A; Ligabue, F; Lusiani, A; Marrocchesi, P S; Messineo, A; Rizzo, G; Sanguinetti, G; Sciabà, A; Spagnolo, P; Steinberger, Jack; Tenchini, Roberto; Tonelli, G; Triggiani, G; Vannini, C; Verdini, P G; Walsh, J; Betteridge, A P; Blair, G A; Bryant, L M; Cerutti, F; Gao, Y; Green, M G; Johnson, D L; Medcalf, T; Mir, L M; Perrodo, P; Strong, J A; Bertin, V; Botterill, David R; Clifft, R W; Edgecock, T R; Haywood, S; Edwards, M; Maley, P; Norton, P R; Thompson, J C; Bloch-Devaux, B; Colas, P; Duarte, H; Emery, S; Kozanecki, Witold; Lançon, E; Lemaire, M C; Locci, E; Marx, B; Pérez, P; Rander, J; Renardy, J F; Rosowsky, A; Roussarie, A; Schuller, J P; Schwindling, J; Si Mohand, D; Trabelsi, A; Vallage, B; Johnson, R P; Kim, H Y; Litke, A M; McNeil, M A; Taylor, G; Beddall, A; Booth, C N; Boswell, R; Cartwright, S L; Combley, F; Dawson, I; Köksal, A; Letho, M; Newton, W M; Rankin, C; Thompson, L F; Böhrer, A; Brandt, S; Cowan, G D; Feigl, E; Grupen, Claus; Lutters, G; Minguet-Rodríguez, J A; Rivera, F; Saraiva, P; Smolik, L; Stephan, F; Apollonio, M; Bosisio, L; Della Marina, R; Giannini, G; Gobbo, B; Ragusa, F; Rothberg, J E; Wasserbaech, S R; Armstrong, S R; Bellantoni, L; Elmer, P; Feng, Z; Ferguson, D P S; Gao, Y S; González, S; Grahl, J; Harton, J L; Hayes, O J; Hu, H; McNamara, P A; Nachtman, J M; Orejudos, W; Pan, Y B; Saadi, Y; Schmitt, M; Scott, I J; Sharma, V; Turk, J; Walsh, A M; Wu Sau Lan; Wu, X; Yamartino, J M; Zheng, M; Zobernig, G

1995-01-01

A lower limit is set on the B_{s}^{0} meson oscillation parameter \\Delta m_{s} using data collected from 1991 to 1994 by the ALEPH detector. Events with a high transverse momentum lepton and a reconstructed secondary vertex are used. The high transverse momentum leptons are produced mainly by b hadron decays, and the sign of the lepton indicates the particle/antiparticle final state in decays of neutral B mesons. The initial state is determined by a jet charge technique using both sides of the event. A maximum likelihood method is used to set a lower limit of \\, \\Delta m_{s}. The 95\\% confidence level lower limit on \\Delta m_s ranges between 5.2 and 6.5(\\hbar/c^{2})~ps^{-1} when the fraction of b quarks from Z^0 decays that form B_{s}^{0} mesons is varied from 8\\% to 16\\%. Assuming that the B_{s}^{0} fraction is 12\\%, the lower limit would be \\Delta m_{s} > 6.1(\\hbar/c^{2})~ps^{-1} at 95\\% confidence level. For x_s = \\Delta m_s \\, \\tau_{B_s}, this limit also gives x_s > 8.8 using the B_{s}^{0} lifetime of \\ta...

Comprehensive fluence model for absolute portal dose image prediction

International Nuclear Information System (INIS)

Chytyk, K.; McCurdy, B. M. C.

2009-01-01

Amorphous silicon (a-Si) electronic portal imaging devices (EPIDs) continue to be investigated as treatment verification tools, with a particular focus on intensity modulated radiation therapy (IMRT). This verification could be accomplished through a comparison of measured portal images to predicted portal dose images. A general fluence determination tailored to portal dose image prediction would be a great asset in order to model the complex modulation of IMRT. A proposed physics-based parameter fluence model was commissioned by matching predicted EPID images to corresponding measured EPID images of multileaf collimator (MLC) defined fields. The two-source fluence model was composed of a focal Gaussian and an extrafocal Gaussian-like source. Specific aspects of the MLC and secondary collimators were also modeled (e.g., jaw and MLC transmission factors, MLC rounded leaf tips, tongue and groove effect, interleaf leakage, and leaf offsets). Several unique aspects of the model were developed based on the results of detailed Monte Carlo simulations of the linear accelerator including (1) use of a non-Gaussian extrafocal fluence source function, (2) separate energy spectra used for focal and extrafocal fluence, and (3) different off-axis energy spectra softening used for focal and extrafocal fluences. The predicted energy fluence was then convolved with Monte Carlo generated, EPID-specific dose kernels to convert incident fluence to dose delivered to the EPID. Measured EPID data were obtained with an a-Si EPID for various MLC-defined fields (from 1x1 to 20x20 cm 2 ) over a range of source-to-detector distances. These measured profiles were used to determine the fluence model parameters in a process analogous to the commissioning of a treatment planning system. The resulting model was tested on 20 clinical IMRT plans, including ten prostate and ten oropharyngeal cases. The model predicted the open-field profiles within 2%, 2 mm, while a mean of 96.6% of pixels over all

EPID detection of radio-opaque markers for the evaluation of prostate position during megavoltage irradiation: a clinical study

International Nuclear Information System (INIS)

Vigneault, E.; Pouliot, J.; Laverdiere, J.; Roy, J.

1995-01-01

Purpose: To assess daily prostatic apex motion relative to pelvic bone structures during megavoltage irradiation. Materials and Methods: Radio-opaque markers were implanted under ultrasound guidance near the prostatic apex of ten patients with localized prostatic carcinoma. Patients were subsequently treated with four field box technique at a beam energy of 23 MV. During treatment, on-line images were obtained with an Electronic Portal Imaging Device (EPID) for each field and fraction. The marker was easily identified, even on unprocessed images and the distance between the marker and a bony landmark was measured. Timelapse movie for the complete treatment of each patient were also reviewed. After the completion of treatment, a transrectal ultrasound examination was performed to verify the position of the marker relative to the apex. Results: Over 1000 digital portal images were acquired. Antero-posterior and lateral views of each fraction were analysed. The quality of portal images obtained with megavoltage irradiation was good. Even without image histogram equalization it was possible to evaluate pelvic bone structures. Moreover, the radio-opaque marker was easily visible on every on-line portal image. Qualitatively, the review of timelapse movies showed important interfraction motions of the marker while bone structures remained stable. Quantitatively, the position of the marker were measured for each fraction. Marker displacements of up to 1,4 cm were measured between two consecutive days of treatment. Important marker motions were predominately in the antero-posterior and cephalo-caudal directions. Position of the markers relative to the prostatic apex were verified with ultrasound at the end of the treatments and were found to remain globaly at their original position. Intratreatment images were reviewed in two cases and no change in marker positions was observed. Our results, obtained during the treatment courses, indicate similar or larger prostate motions

An isogeometric boundary element method for electromagnetic scattering with compatible B-spline discretizations

Science.gov (United States)

Simpson, R. N.; Liu, Z.; Vázquez, R.; Evans, J. A.

2018-06-01

We outline the construction of compatible B-splines on 3D surfaces that satisfy the continuity requirements for electromagnetic scattering analysis with the boundary element method (method of moments). Our approach makes use of Non-Uniform Rational B-splines to represent model geometry and compatible B-splines to approximate the surface current, and adopts the isogeometric concept in which the basis for analysis is taken directly from CAD (geometry) data. The approach allows for high-order approximations and crucially provides a direct link with CAD data structures that allows for efficient design workflows. After outlining the construction of div- and curl-conforming B-splines defined over 3D surfaces we describe their use with the electric and magnetic field integral equations using a Galerkin formulation. We use Bézier extraction to accelerate the computation of NURBS and B-spline terms and employ H-matrices to provide accelerated computations and memory reduction for the dense matrices that result from the boundary integral discretization. The method is verified using the well known Mie scattering problem posed over a perfectly electrically conducting sphere and the classic NASA almond problem. Finally, we demonstrate the ability of the approach to handle models with complex geometry directly from CAD without mesh generation.

Development of a method for detection and quantification of B. brongniartii and B. bassiana in soil

Science.gov (United States)

Canfora, L.; Malusà, E.; Tkaczuk, C.; Tartanus, M.; Łabanowska, B. H.; Pinzari, F.

2016-03-01

A culture independent method based on qPCR was developed for the detection and quantification of two fungal inoculants in soil. The aim was to adapt a genotyping approach based on SSR (Simple Sequence Repeat) marker to a discriminating tracing of two different species of bioinoculants in soil, after their in-field release. Two entomopathogenic fungi, Beauveria bassiana and B. brongniartii, were traced and quantified in soil samples obtained from field trials. These two fungal species were used as biological agents in Poland to control Melolontha melolontha (European cockchafer), whose larvae live in soil menacing horticultural crops. Specificity of SSR markers was verified using controls consisting of: i) soil samples containing fungal spores of B. bassiana and B. brongniartii in known dilutions; ii) the DNA of the fungal microorganisms; iii) soil samples singly inoculated with each fungus species. An initial evaluation of the protocol was performed with analyses of soil DNA and mycelial DNA. Further, the simultaneous detection and quantification of B. bassiana and B. brongniartii in soil was achieved in field samples after application of the bio-inoculants. The protocol can be considered as a relatively low cost solution for the detection, identification and traceability of fungal bio-inoculants in soil.

Nascimento de bezerros normais após inseminação artificial utilizando espermatozóides criopreservados obtidos de epidídimos refrigerados de bovinos após a morte Birth of normal calves after artificial insemination using cryopreserved spermatozoa obtained from refrigerated epididymides of death bovine

Directory of Open Access Journals (Sweden)

Priscila de Melo Costa

2011-05-01

Full Text Available O objetivo deste estudo foi avaliar as características morfológicas e funcionais dos espermatozóides bovinos recuperados de epidídimos resfriados por longos períodos e posteriormente criopreservados. Testículos bovinos foram coletados no abatedouro, transportados ao laboratório e armazenados a 5°C por 0, 24, 48 e 72 horas (n=10 para cada tratamento. Os espermatozóides foram extraídos de cada epidídimo, avaliados e diluídos em meio tris-gema-glicerol a 7% e criopreservados em nitrogênio líquido. As características morfológicas e funcionais dos espermatozóides foram avaliadas in vitro por análise microscópica e in vivo, por meio de inseminação artificial. Foram observadas alterações morfológicas características da imaturidade dos espermatozóides e redução da motilidade após 72 horas de refrigeração dos epidídimos. Esses parâmetros também foram alterados após o descongelamento, em todos os tratamentos. A manutenção dos espermatozoides a 5°C por 72h reduziu a motilidade espermática. Em todos os tratamentos foram observadas alterações morfológicas características da imaturidade dos espermatozoides e redução da motilidade após o descongelamento. A integridade de membrana plasmática e acrossoma somente foram afetadas pós criopreservação nos grupos mantidos a 5°C durante 48 ou 72h antes da criopreservação. Contudo, a capacidade de fecundação dos espermatozóides mantidos a 5°C durante 24 ou 72h antes da criopreservação foi suficiente para promover duas gestações e nascimento de bezerros saudáveis. Esses resultados indicam que a recuperação e a criopreservação de espermatozóides obtidos de epidídimos mantidos a 5°C, até 72h, provenientes de animais mortos é uma opção viável para preservar gametas masculinos para compor um banco de germoplasma.The objective of this study was to evaluate the morphological and functional characteristics of bovine spermatozoa retrieved from chilled

Enrichment of W2B5 from WO3 and B2O3 by Double SHS Method

Directory of Open Access Journals (Sweden)

Bora DERIN

2018-02-01

Full Text Available A second self-propagating high-temperature synthesis (SHS was carried out to enrich the W2B5 content in the SHS product containing a mixture of various tungsten boride compounds. In the experiment, the process called Double-SHS (D-SHS was conducted in two steps. In the first SHS reaction, an initial molar composition ratio of WO3:B2O3:Mg mixture was selected as 1:3:8. The product was then hot-leached with hydrochloric acid to eliminate MgO and Mg3B2O6 phases. The leached product, consisting of 72.6 wt.% W2B5, 16.1 wt.% WB, 8.4 wt.% W2B, and 2.9 wt.% W, was again reacted with the Mg and B2O3 mixture by second SHS. After another acid leaching step, W2B5 content in the D-SHS product was found to be 98.2 wt.%. The study showed that D-SHS is an effective method for boron enrichment in the tungsten compounds.DOI: http://dx.doi.org/10.5755/j01.ms.24.1.17834

10 CFR Appendix B1 to Subpart B of... - Uniform Test Method for Measuring the Energy Consumption of Freezers

Science.gov (United States)

2010-01-01

... 10 Energy 3 2010-01-01 2010-01-01 false Uniform Test Method for Measuring the Energy Consumption... to Subpart B of Part 430—Uniform Test Method for Measuring the Energy Consumption of Freezers 1... temperature, then these test results shall be used to determine energy consumption. If the compartment...

A simple quality assurance test tool for the visual verification of light and radiation field congruent using electronic portal images device and computed radiography

Directory of Open Access Journals (Sweden)

Njeh Christopher F

2012-03-01

Full Text Available Abstract Background The radiation field on most megavoltage radiation therapy units are shown by a light field projected through the collimator by a light source mounted inside the collimator. The light field is traditionally used for patient alignment. Hence it is imperative that the light field is congruent with the radiation field. Method A simple quality assurance tool has been designed for rapid and simple test of the light field and radiation field using electronic portal images device (EPID or computed radiography (CR. We tested this QA tool using Varian PortalVision and Elekta iViewGT EPID systems and Kodak CR system. Results Both the single and double exposure techniques were evaluated, with double exposure technique providing a better visualization of the light-radiation field markers. The light and radiation congruency could be detected within 1 mm. This will satisfy the American Association of Physicists in Medicine task group report number 142 recommendation of 2 mm tolerance. Conclusion The QA tool can be used with either an EPID or CR to provide a simple and rapid method to verify light and radiation field congruence.

Crystal and electronic structure of (N-CH3-2,2'-bipyridinium)(dodecahydro-dicarba-nido-undecaborate)

International Nuclear Information System (INIS)

Il'inchik, E.A.; Polyanskaya, T.M.; Volkov, V.V.

2007-01-01

The compound (N-CH 3 -2,2'-bipyridinium)(dodecahydro-dicarba-nido-undecaborate) is synthesized, and its structure is determined. The compound is characterized by IR, 11 B, 14 N NMR and X-ray photoelectron spectroscopy methods. Crystallographic data are: C 13 H 23 B 9 N 2 , M=304.62, monoclinic lattice, space group P2 1 /c, a=11.840(4), b=10.051(3), c=15.573(6) A, β=102.43(3) Deg, V=1809.8(10) A 3 , Z=4, d cal =1.118 g/cm 3 , R=0.0607 [ru

Advanced Portal Images Processing for Cobalt Radiotherapy Systems and Lineal Accelerator for cancer treatment

International Nuclear Information System (INIS)

Valdes Cabrera, D.

2013-01-01

It is presented an investigation project to design software that allows image processing and treatment of an Electronic Portal Image Device (EPID) for lineal accelerators and cobalt machines. For the development of the software it was used the programming language MATLAB and DICOM RT images with a spatial resolution in the isocenter of 0.40 mm/pixel, dimensions of 1024x1024 pixels and 65536 tones in grey scale, that were taken by a linac from Elekta trademark located in the National Institute of Oncology and Radiobiology. Methods and algorithms implemented were the improvements in the contrast, brightness, equalization and inversion of grey scale of images through modifications in their histogram; the possibility of making rotations, segmentations of zones of interest basing in users criteria for thresholding taking in count the visualization of pixels intensity and measuring of distances in pixels. For the calculations of displacements and rotations between the reference and the actual image was used the canny method for edges detection of the radiation fields and anatomical structures, and normalized bidimensional correlation algorithms for seeking and calculation of objects of interest between two images. The results were obtained using 23 pairs of images of six treatments and the average of the reported errors were: horizontal, vertical and rotational fields errors: ± .531 mm, ± 1.278 mm and ± 0.087 o ; horizontal, vertical and rotational anatomical structures errors: ± 0.766 mm, ± 0.573 mm, ± 0.174 o . these values are under the limit values for each one of these treatments according to the consulted bibliography. (Author)

40 CFR Appendix B to Part 80 - Test Methods for Lead in Gasoline

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 16 2010-07-01 2010-07-01 false Test Methods for Lead in Gasoline B... in Gasoline Method 1—Standard Method Test for Lead in Gasoline by Atomic Absorption Spectrometry 1. Scope. 1.1. This method covers the determination of the total lead content of gasoline. The procedure's...

49 CFR 573.7 - Quarterly reports.

Science.gov (United States)

2010-10-01

... number of vehicles or items of equipment determined to be unreachable for inspection due to export, theft... vehicles or items of replacement equipment involved in the campaign, whichever occurs first. (b) Each... notification began and the date completed. (3) The number of vehicles or items of equipment involved in the...

Machine learning-based methods for prediction of linear B-cell epitopes.

Science.gov (United States)

Wang, Hsin-Wei; Pai, Tun-Wen

2014-01-01

B-cell epitope prediction facilitates immunologists in designing peptide-based vaccine, diagnostic test, disease prevention, treatment, and antibody production. In comparison with T-cell epitope prediction, the performance of variable length B-cell epitope prediction is still yet to be satisfied. Fortunately, due to increasingly available verified epitope databases, bioinformaticians could adopt machine learning-based algorithms on all curated data to design an improved prediction tool for biomedical researchers. Here, we have reviewed related epitope prediction papers, especially those for linear B-cell epitope prediction. It should be noticed that a combination of selected propensity scales and statistics of epitope residues with machine learning-based tools formulated a general way for constructing linear B-cell epitope prediction systems. It is also observed from most of the comparison results that the kernel method of support vector machine (SVM) classifier outperformed other machine learning-based approaches. Hence, in this chapter, except reviewing recently published papers, we have introduced the fundamentals of B-cell epitope and SVM techniques. In addition, an example of linear B-cell prediction system based on physicochemical features and amino acid combinations is illustrated in details.

Application of a practical method for the isocenter point in vivo dosimetry by a transit signal

Energy Technology Data Exchange (ETDEWEB)

Piermattei, Angelo [UO di Fisica Sanitaria, Centro di Ricerca e Formazione ad Alta Tecnologia nelle Scienze Biomediche dell' Universita Cattolica Sacro Cuore, Campobasso (Italy); Fidanzio, Andrea [Istituto di Fisica, Universita Cattolica del Sacro Cuore, Rome (Italy); Azario, Luigi [Istituto di Fisica, Universita Cattolica del Sacro Cuore, Rome (Italy)] (and others)

2007-08-21

This work reports the results of the application of a practical method to determine the in vivo dose at the isocenter point, D{sub iso}, of brain thorax and pelvic treatments using a transit signal S{sub t}. The use of a stable detector for the measurement of the signal S{sub t} (obtained by the x-ray beam transmitted through the patient) reduces many of the disadvantages associated with the use of solid-state detectors positioned on the patient as their periodic recalibration, and their positioning is time consuming. The method makes use of a set of correlation functions, obtained by the ratio between S{sub t} and the mid-plane dose value, D{sub m}, in standard water-equivalent phantoms, both determined along the beam central axis. The in vivo measurement of D{sub iso} required the determination of the water-equivalent thickness of the patient along the beam central axis by the treatment planning system that uses the electron densities supplied by calibrated Hounsfield numbers of the computed tomography scanner. This way it is, therefore, possible to compare D{sub iso} with the stated doses, D{sub iso,TPS}, generally used by the treatment planning system for the determination of the monitor units. The method was applied in five Italian centers that used beams of 6 MV, 10 MV, 15 MV x-rays and {sup 60}Co {gamma}-rays. In particular, in four centers small ion-chambers were positioned below the patient and used for the S{sub t} measurement. In only one center, the S{sub t} signals were obtained directly by the central pixels of an EPID (electronic portal imaging device) equipped with commercial software that enabled its use as a stable detector. In the four centers where an ion-chamber was positioned on the EPID, 60 pelvic treatments were followed for two fields, an anterior-posterior or a posterior-anterior irradiation and a lateral-lateral irradiation. Moreover, ten brain tumors were checked for a lateral-lateral irradiation, and five lung tumors carried out with

B-spline tight frame based force matching method

Science.gov (United States)

Yang, Jianbin; Zhu, Guanhua; Tong, Dudu; Lu, Lanyuan; Shen, Zuowei

2018-06-01

In molecular dynamics simulations, compared with popular all-atom force field approaches, coarse-grained (CG) methods are frequently used for the rapid investigations of long time- and length-scale processes in many important biological and soft matter studies. The typical task in coarse-graining is to derive interaction force functions between different CG site types in terms of their distance, bond angle or dihedral angle. In this paper, an ℓ1-regularized least squares model is applied to form the force functions, which makes additional use of the B-spline wavelet frame transform in order to preserve the important features of force functions. The B-spline tight frames system has a simple explicit expression which is useful for representing our force functions. Moreover, the redundancy of the system offers more resilience to the effects of noise and is useful in the case of lossy data. Numerical results for molecular systems involving pairwise non-bonded, three and four-body bonded interactions are obtained to demonstrate the effectiveness of our approach.

Mechanical characterization of the Varian Exact-arm and R-arm support systems for eight aS500 electronic portal imaging devices

International Nuclear Information System (INIS)

Grattan, Mark W. D.; McGarry, Conor K.

2010-01-01

Purpose: The aim of this study is to compare the positioning accuracy at different gantry angles of two electronic portal imaging devices (EPIDs) support arm systems by using EPID difference images as a measure for displacement. This work presents a comparison of the mechanical performance of eight Varian aS500 (Varian Medical Systems, Palo Alto, CA) EPIDs, mounted using either the Varian Exact-arm or R-arm. Methods: The mechanical performance of the two arm systems was compared by investigating the variation in sensitivity with gantry angle, both before and after the EPID position was adjusted after gantry rotation. Positional errors were investigated by subtracting images from a reference image taken at gantry 0 deg., and the amplitude of the peaks and troughs at the field edges for longitudinal (radial) and lateral (transverse) profiles across the resulting image was related to the distance of displacement. Calibration curves based on a pixel-by-pixel shift were generated for each EPID and the Varian hand pendant accuracy was compared to the calibration data. Results: The response of the EPIDs was found to change with gantry rotation, with the largest difference at 180 deg. The Exact-arm was found to correct well for any displacement, while the R-arm tended to overcorrect following repositioning using the hand pendant. The calibration curves were consistent within each set of matched linacs, and the hand pendant accuracy was similar for both arm systems, although generally in different directions. With respect to gantry rotation effects, the mechanical performance of the Exact-arm systems was found to be much better than that of the R-arm systems. At gantry positions 90 deg., 270 deg., and 180 deg. the average misalignment in the longitudinal direction was +4.2±0.2, +1.8±1.6, and +7.4±0.5 mm for the R-arms, and +2.9±0.2, +2.1±0.8, and +4.9±0.7 mm for the Exact-arms. In the lateral direction the average positional errors were +2.1±0.4, -4.7±0.4, and -2.5�

Secure ADS-B authentication system and method

Science.gov (United States)

Viggiano, Marc J (Inventor); Valovage, Edward M (Inventor); Samuelson, Kenneth B (Inventor); Hall, Dana L (Inventor)

2010-01-01

A secure system for authenticating the identity of ADS-B systems, including: an authenticator, including a unique id generator and a transmitter transmitting the unique id to one or more ADS-B transmitters; one or more ADS-B transmitters, including a receiver receiving the unique id, one or more secure processing stages merging the unique id with the ADS-B transmitter's identification, data and secret key and generating a secure code identification and a transmitter transmitting a response containing the secure code and ADSB transmitter's data to the authenticator; the authenticator including means for independently determining each ADS-B transmitter's secret key, a receiver receiving each ADS-B transmitter's response, one or more secure processing stages merging the unique id, ADS-B transmitter's identification and data and generating a secure code, and comparison processing comparing the authenticator-generated secure code and the ADS-B transmitter-generated secure code and providing an authentication signal based on the comparison result.

Conditions for reliable time-resolved dosimetry of electronic portal imaging devices for fixed-gantry IMRT and VMAT

International Nuclear Information System (INIS)

Yeo, Inhwan Jason; Patyal, Baldev; Mandapaka, Anant; Jung, Jae Won; Yi, Byong Yong; Kim, Jong Oh

2013-01-01

Purpose: The continuous scanning mode of electronic portal imaging devices (EPID) that offers time-resolved information has been newly explored for verifying dynamic radiation deliveries. This study seeks to determine operating conditions (dose rate stability and time resolution) under which that mode can be used accurately for the time-resolved dosimetry of intensity-modulated radiation therapy (IMRT) beams.Methods: The authors have designed the following test beams with variable beam holdoffs and dose rate regulations: a 10 × 10 cm open beam to serve as a reference beam; a sliding window (SW) beam utilizing the motion of a pair of multileaf collimator (MLC) leaves outside the 10 × 10 cm jaw; a step and shoot (SS) beam to move the pair in step; a volumetric modulated arc therapy (VMAT) beam. The beams were designed in such a way that they all produce the same open beam output of 10 × 10 cm. Time-resolved ion chamber measurements at isocenter and time-resolved and integrating EPID measurements were performed for all beams. The time-resolved EPID measurements were evaluated through comparison with the ion chamber and integrating EPID measurements, as the latter are accepted procedures. For two-dimensional, time-resolved evaluation, a VMAT beam with an infield MLC travel was designed. Time-resolved EPID measurements and Monte Carlo calculations of such EPID dose images for this beam were performed and intercompared.Results: For IMRT beams (SW and SS), the authors found disagreement greater than 2%, caused by frame missing of the time-resolved mode. However, frame missing disappeared, yielding agreement better than 2%, when the dose rate of irradiation (and thus the frame acquisition rates) reached a stable and planned rate as the dose of irradiation was raised past certain thresholds (a minimum 12 s of irradiation per shoot used for SS IMRT). For VMAT, the authors found that dose rate does not affect the frame acquisition rate, thereby causing no frame missing

Revue de Médecine et de Pharmacie - Vol 2, No 1 (2012)

African Journals Online (AJOL)

Epidémie de choléra à Douala en 2011 épidémiologie, clinique et bactériologie · EMAIL FULL TEXT EMAIL FULL TEXT · DOWNLOAD FULL TEXT DOWNLOAD FULL TEXT. AAB Fouda, B Kollo, A Ngomba, JII Dissongo, LJO Manga, N Essomba, GE Sume, V Deli, MK Ngambi, 113-120 ...

A graph-based method for fitting planar B-spline curves with intersections

Directory of Open Access Journals (Sweden)

Pengbo Bo

2016-01-01

Full Text Available The problem of fitting B-spline curves to planar point clouds is studied in this paper. A novel method is proposed to deal with the most challenging case where multiple intersecting curves or curves with self-intersection are necessary for shape representation. A method based on Delauney Triangulation of data points is developed to identify connected components which is also capable of removing outliers. A skeleton representation is utilized to represent the topological structure which is further used to create a weighted graph for deciding the merging of curve segments. Different to existing approaches which utilize local shape information near intersections, our method considers shape characteristics of curve segments in a larger scope and is thus capable of giving more satisfactory results. By fitting each group of data points with a B-spline curve, we solve the problems of curve structure reconstruction from point clouds, as well as the vectorization of simple line drawing images by drawing lines reconstruction.

Models and methods can theory meet the B physics challenge?

CERN Document Server

Nierste, U

2004-01-01

The B physics experiments of the next generation, BTeV and LHCb, will perform measurements with an unprecedented accuracy. Theory predictions must control hadronic uncertainties with the same precision to extract the desired short-distance information successfully. I argue that this is indeed possible, discuss those theoretical methods in which hadronic uncertainties are under control and list hadronically clean observables.

Synthesis of Al-5Ti-1B Refiner by Melt Reaction Method

Directory of Open Access Journals (Sweden)

LI He

2017-02-01

Full Text Available Al-5Ti-1B refiner was successfully prepared by melt reaction method. Through the thermodynamics calculation, the initial reaction temperature was determined. The influence of reaction temperature on microstructure and absorption rate of the alloy was investigated. The phase and microstructure of the alloy were observed by X-ray diffraction, scanning electron microscope and energy dispersive spectrometer. The Al-5Ti-1B refiner was extruded at high temperature to wire with the diameter of 9.5mm, and then the refinement experiment was carried out on pure aluminium. The results indicate that the refiner consists of TiB2, TiAl3 and α-Al, and the microstructure prepared at 850℃ is the optimum and the absorption rate of Ti and B matches the best. The TiAl3 and TiB2 phases distribute homogeneously in the matrix after extrusion. When adding 0.2%(mass fraction of Al-5Ti-1B refiner, the grain size of pure aluminium reduces from 3.99mm to 0.45mm.

Draft genome sequences of the oomycete Pythium insidiosum strain CBS 573.85 from a horse with pythiosis and strain CR02 from the environment

Directory of Open Access Journals (Sweden)

Preecha Patumcharoenpol

2018-02-01

Full Text Available Pythium insidiosum is an aquatic oomycete microorganism that causes the fatal infectious disease, pythiosis, in humans and animals. The organism has been successfully isolated from the environment worldwide. Diagnosis and treatment of pythiosis is difficult and challenging. Genome sequences of P. insidiosum, isolated from humans, are available and accessible in public databases. To further facilitate biology-, pathogenicity-, and evolution-related genomic and genetic studies of P. insidiosum, we report two additional draft genome sequences of the P. insidiosum strain CBS 573.85 (35.6 Mb in size; accession number, BCFO00000000.1 isolated from a horse with pythiosis, and strain CR02 (37.7 Mb in size; accession number, BCFR00000000.1 isolated from the environment. Keywords: Pythium insidiosum, Pythiosis, Draft genome sequence

Synthesis of Al-5Ti-1B Refiner by Melt Reaction Method

OpenAIRE

LI He; CHAI Li-hua; MA Teng-fei; CHEN Zi-yong

2017-01-01

Al-5Ti-1B refiner was successfully prepared by melt reaction method. Through the thermodynamics calculation, the initial reaction temperature was determined. The influence of reaction temperature on microstructure and absorption rate of the alloy was investigated. The phase and microstructure of the alloy were observed by X-ray diffraction, scanning electron microscope and energy dispersive spectrometer. The Al-5Ti-1B refiner was extruded at high temperature to wire with the diameter of 9.5mm...

Use of an amorphous silicon electronic portal imaging device for multileaf collimator quality control and calibration

International Nuclear Information System (INIS)

Baker, S J K; Budgell, G J; MacKay, R I

2005-01-01

Multileaf collimator (MLC) calibration and quality control is a time-consuming procedure typically involving the processing, scanning and analysis of films to measure leaf and collimator positions. Faster and more reliable calibration procedures are required for these tasks, especially with the introduction of intensity modulated radiotherapy which requires more frequent checking and finer positional leaf tolerances than previously. A routine quality control (QC) technique to measure MLC leaf bank gain and offset, as well as minor offsets (individual leaf position relative to a reference leaf), using an amorphous silicon electronic portal imaging device (EPID) has been developed. The technique also tests the calibration of the primary and back-up collimators. A detailed comparison between film and EPID measurements has been performed for six linear accelerators (linacs) equipped with MLC and amorphous silicon EPIDs. Measurements of field size from 4 to 24 cm with the EPID were systematically smaller than film measurements over all field sizes by 0.4 mm for leaves/back-up collimators and by 0.2 mm for conventional collimators. This effect is due to the gain calibration correction applied by the EPID, resulting in a 'flattening' of primary beam profiles. Linac dependent systematic differences of up to 0.5 mm in individual leaf/collimator positions were also found between EPID and film measurements due to the difference between the mechanical and radiation axes of rotation. When corrections for these systematic differences were applied, the residual random differences between EPID and film were 0.23 mm and 0.26 mm (1 standard deviation) for field size and individual leaf/back-up collimator position, respectively. Measured gains (over a distance of 220 mm) always agreed within 0.4 mm with a standard deviation of 0.17 mm. Minor offset measurements gave a mean agreement between EPID and film of 0.01 ± 0.10 mm (1 standard deviation) after correction for the tilt of the

A method to construct covariance files in ENDF/B format for criticality safety applications

International Nuclear Information System (INIS)

Naberejnev, D.G.; Smith, D.L.

1999-01-01

Argonne National Laboratory is providing support for a criticality safety analysis project that is being performed at Oak Ridge National Laboratory. The ANL role is to provide the covariance information needed by ORNL for this project. The ENDF/B-V evaluation is being used for this particular criticality analysis. In this evaluation, covariance information for several isotopes or elements of interest to this analysis is either not given or needs to be reconsidered. For some required materials, covariance information does not exist in ENDF/B-V: 233 U, 236 U, Zr, Mg, Gd, and Hf. For others, existing covariance information may need to be re-examined in light of the newer ENDF/B-V evaluation and recent experimental data. In this category are the following materials: 235 U, 238 U, 239 Pu, 240 Pu, 241 Pu, Fe, H, C, N, O, Al, Si, and B. A reasonable estimation of the fractional errors for various evaluated neutron cross sections from ENDF/B-V can be based on the comparisons between the major more recent evaluations including ENDF/B-VI, JENDL3.2, BROND2.2, and JEF2.2, as well as a careful examination of experimental data. A reasonable method to construct correlation matrices is proposed here. Coupling both of these considerations suggests a method to construct covariances files in ENDF/B format that can be used to express uncertainties for specific ENDF/B-V cross sections

A simple quality assurance test tool for the visual verification of light and radiation field congruent using electronic portal images device and computed radiography

International Nuclear Information System (INIS)

Njeh, Christopher F; Caroprese, Blas; Desai, Pushkar

2012-01-01

The radiation field on most megavoltage radiation therapy units are shown by a light field projected through the collimator by a light source mounted inside the collimator. The light field is traditionally used for patient alignment. Hence it is imperative that the light field is congruent with the radiation field. A simple quality assurance tool has been designed for rapid and simple test of the light field and radiation field using electronic portal images device (EPID) or computed radiography (CR). We tested this QA tool using Varian PortalVision and Elekta iViewGT EPID systems and Kodak CR system. Both the single and double exposure techniques were evaluated, with double exposure technique providing a better visualization of the light-radiation field markers. The light and radiation congruency could be detected within 1 mm. This will satisfy the American Association of Physicists in Medicine task group report number 142 recommendation of 2 mm tolerance. The QA tool can be used with either an EPID or CR to provide a simple and rapid method to verify light and radiation field congruence

Poster — Thur Eve — 17: In-phantom and Fluence-based Measurements for Quality Assurance of Volumetric-driven Adaptation of Arc Therapy

International Nuclear Information System (INIS)

Schaly, B; Hoover, D; Mitchell, S; Wong, E

2014-01-01

During volumetric modulated arc therapy (VMAT) of head and neck cancer, some patients lose weight which may result in anatomical deviations from the initial plan. If these deviations are substantial a new treatment plan can be designed for the remainder of treatment (i.e., adaptive planning). Since the adaptive treatment process is resource intensive, one possible approach to streamlining the quality assurance (QA) process is to use the electronic portal imaging device (EPID) to measure the integrated fluence for the adapted plans instead of the currently-used ArcCHECK device (Sun Nuclear). Although ArcCHECK is recognized as the clinical standard for patient-specific VMAT plan QA, it has limited length (20 cm) for most head and neck field apertures and has coarser detector spacing than the EPID (10 mm vs. 0.39 mm). In this work we compared measurement of the integrated fluence using the EPID with corresponding measurements from the ArcCHECK device. In the past year nine patients required an adapted plan. Each of the plans (the original and adapted) is composed of two arcs. Routine clinical QA was performed using the ArcCHECK device, and the same plans were delivered to the EPID (individual arcs) in integrated mode. The dose difference between the initial plan and adapted plan was compared for ArcCHECK and EPID. In most cases, it was found that the EPID is more sensitive in detecting plan differences. Therefore, we conclude that EPID provides a viable alternative for QA of the adapted head and neck plans and should be further explored

B97-3c: A revised low-cost variant of the B97-D density functional method

Science.gov (United States)

Brandenburg, Jan Gerit; Bannwarth, Christoph; Hansen, Andreas; Grimme, Stefan

2018-02-01

A revised version of the well-established B97-D density functional approximation with general applicability for chemical properties of large systems is proposed. Like B97-D, it is based on Becke's power-series ansatz from 1997 and is explicitly parametrized by including the standard D3 semi-classical dispersion correction. The orbitals are expanded in a modified valence triple-zeta Gaussian basis set, which is available for all elements up to Rn. Remaining basis set errors are mostly absorbed in the modified B97 parametrization, while an established atom-pairwise short-range potential is applied to correct for the systematically too long bonds of main group elements which are typical for most semi-local density functionals. The new composite scheme (termed B97-3c) completes the hierarchy of "low-cost" electronic structure methods, which are all mainly free of basis set superposition error and account for most interactions in a physically sound and asymptotically correct manner. B97-3c yields excellent molecular and condensed phase geometries, similar to most hybrid functionals evaluated in a larger basis set expansion. Results on the comprehensive GMTKN55 energy database demonstrate its good performance for main group thermochemistry, kinetics, and non-covalent interactions, when compared to functionals of the same class. This also transfers to metal-organic reactions, which is a major area of applicability for semi-local functionals. B97-3c can be routinely applied to hundreds of atoms on a single processor and we suggest it as a robust computational tool, in particular, for more strongly correlated systems where our previously published "3c" schemes might be problematic.

Reliable B cell epitope predictions: impacts of method development and improved benchmarking

DEFF Research Database (Denmark)

Kringelum, Jens Vindahl; Lundegaard, Claus; Lund, Ole

2012-01-01

biomedical applications such as; rational vaccine design, development of disease diagnostics and immunotherapeutics. However, experimental mapping of epitopes is resource intensive making in silico methods an appealing complementary approach. To date, the reported performance of methods for in silico mapping...... evaluation data set improved from 0.712 to 0.727. Our results thus demonstrate that given proper benchmark definitions, B-cell epitope prediction methods achieve highly significant predictive performances suggesting these tools to be a powerful asset in rational epitope discovery. The updated version...

Pre-treatment verification of RapidArc® using Electronic Portal Imaging Device; Verificacao pre-tratamento de RapidArc® utilizando Dispositivo Eletronico de Imagem Porta

Energy Technology Data Exchange (ETDEWEB)

Lima, Marilia B.; Ferreira, Anne Caroline M.; Bittencourt, Guilherme R.; Pirani, Luis F.; Silveira, Thiago B., E-mail: mbeckerlima@gmail.com [Instituto Nacional do Cancer (INCA), Rio de Janeiro, RJ (Brazil)

2012-12-15

The RapidArc® is a novel but widespread technique to achieve intensity modulated beams. One of the major challenges concerning this technique is the pretreatment verification process. The aim of this paper was to analyze the viability of the Electronic Portal Imaging Device (EPID) used to perform the verification of RapidArc® using the Sun Nuclear SNC Patient software enable to EPID dose conversion (EPIDose license) and compare its results with punctual dose measurements against a low volume ion chamber. There were analyze five RapidArc® planning, evaluating, separately, planar and punctual doses for each arc. For punctual measurements was used a 0,15 cm³ volume ion chamber and the planar distributions, in Calibration Units (CU), were acquired using the EPID and then converted to absolute dose in centigray through EPIDose. The predicted doses were calculated using the AAA algorithm in Eclipse treatment planning system, version 8.6. The planar comparisons, performed in SNC Patient, employed the Gamma Index tool with a 4% dose difference, 4 mm distance to agreement and 20% threshold. The evaluation of punctual dose was defined by calculating deviations between predicted and measured doses. The mean approval percentage in planar distributions was 94.8% and the average deviation in punctual dose was -1.2%. The use of EPID for RapidArc® pre-treatment verification proved to be feasible and showed good sensibility, because of its high spatial resolution. However one must consider the uncertainty of the method. (author)

10B-NMR determination of 10B-BPA, 10B-BPA–fructose complex and total 10B in blood for BNCT

International Nuclear Information System (INIS)

Yoshino, K.; Yabe, T.; Hattori, T.; Saito, K.; Ishikawa, A.; Ohki, H.

2014-01-01

First spontaneous, noninvasive determination method of 10 B-BPA, 10 B-BPA–fructose complex, and total 10 B in blood is described. 10 B-NMR measurement with 100,000 FT accumulation enables us to obtain the result within 100 min/sample. The detection limits for the simultaneous analysis were 3 ppm, 3 ppm and 6 ppm for 10 B-BPA, 10 B-BPA–fructose complex and total 10 B respectively in this study. By this method, we can actually discuss behavior of the 10 B-BPA–fructose complex in blood. - Highlights: • First 10 B-NMR determination of 10 B-BPA and 10 B-BPA–fructose complex in blood. • Total 10 B concentration in blood could be obtained by this method • The detection limit was 3 ppm for total 10 B

Microscopic unravelling of nano-carbon doping in MgB2 superconductors fabricated by diffusion method

International Nuclear Information System (INIS)

Wong, D.C.K.; Yeoh, W.K.; De Silva, K.S.B.; Kondyurin, A.; Bao, P.; Li, W.X.; Xu, X.; Peleckis, G.; Dou, S.X.; Ringer, S.P.; Zheng, R.K.

2015-01-01

Highlights: • First report on nano-carbon doped MgB 2 superconductors synthesized by diffusion method. • Microstructure and superconducting properties of the superconductors are discussed. • B 4 C region blocks the Mg from reacting with B in the 10% nano-carbon doped sample. • MgB 2 with 2.5% nano-carbon doped showed the highest J c , ≈10 4 A/cm 2 for 20 K at 4 T. - Abstract: We investigated the effects of nano-carbon doping as the intrinsic (B-site nano-carbon substitution) and extrinsic (nano-carbon derivatives) pinning by diffusion method. The contraction of the in-plane lattice confirmed the presence of disorder in boron sublattice caused by carbon substitution. The increasing value in full width half maximum (FWHM) in the X-ray diffraction (XRD) patterns with each increment in the doping level reveal smaller grains and imperfect MgB 2 crystalline. The strain increased across the doping level due to the carbon substitution in the MgB 2 matrix. The broadening of the T c curves from low to high doping showed suppression of the connectivity of the bulk samples with progressive dirtying. At high doping, the presence of B 4 C region blocked the Mg from reacting with crystalline B thus hampering the formation of MgB 2 . Furthermore, the unreacted Mg acted as a current blocking phase in lowering down the grain connectivity hence depressing the J c of the 10% nano-carbon doped MgB 2 bulk superconductor

Software tool for portal dosimetry research.

Science.gov (United States)

Vial, P; Hunt, P; Greer, P B; Oliver, L; Baldock, C

2008-09-01

This paper describes a software tool developed for research into the use of an electronic portal imaging device (EPID) to verify dose for intensity modulated radiation therapy (IMRT) beams. A portal dose image prediction (PDIP) model that predicts the EPID response to IMRT beams has been implemented into a commercially available treatment planning system (TPS). The software tool described in this work was developed to modify the TPS PDIP model by incorporating correction factors into the predicted EPID image to account for the difference in EPID response to open beam radiation and multileaf collimator (MLC) transmitted radiation. The processes performed by the software tool include; i) read the MLC file and the PDIP from the TPS, ii) calculate the fraction of beam-on time that each point in the IMRT beam is shielded by MLC leaves, iii) interpolate correction factors from look-up tables, iv) create a corrected PDIP image from the product of the original PDIP and the correction factors and write the corrected image to file, v) display, analyse, and export various image datasets. The software tool was developed using the Microsoft Visual Studio.NET framework with the C# compiler. The operation of the software tool was validated. This software provided useful tools for EPID dosimetry research, and it is being utilised and further developed in ongoing EPID dosimetry and IMRT dosimetry projects.

Theoretical analysis and experimental evaluation of a CsI(Tl) based electronic portal imaging system

International Nuclear Information System (INIS)

Sawant, Amit; Zeman, Herbert; Samant, Sanjiv; Lovhoiden, Gunnar; Weinberg, Brent; DiBianca, Frank

2002-01-01

This article discusses the design and analysis of a portal imaging system based on a thick transparent scintillator. A theoretical analysis using Monte Carlo simulation was performed to calculate the x-ray quantum detection efficiency (QDE), signal to noise ratio (SNR) and the zero frequency detective quantum efficiency [DQE(0)] of the system. A prototype electronic portal imaging device (EPID) was built, using a 12.7 mm thick, 20.32 cm diameter, CsI(Tl) scintillator, coupled to a liquid nitrogen cooled CCD TV camera. The system geometry of the prototype EPID was optimized to achieve high spatial resolution. The experimental evaluation of the prototype EPID involved the determination of contrast resolution, depth of focus, light scatter and mirror glare. Images of humanoid and contrast detail phantoms were acquired using the prototype EPID and were compared with those obtained using conventional and high contrast portal film and a commercial EPID. A theoretical analysis was also carried out for a proposed full field of view system using a large area, thinned CCD camera and a 12.7 mm thick CsI(Tl) crystal. Results indicate that this proposed design could achieve DQE(0) levels up to 11%, due to its order of magnitude higher QDE compared to phosphor screen-metal plate based EPID designs, as well as significantly higher light collection compared to conventional TV camera based systems

Image-Guided Radiotherapy in Near Real Time With Intensity-Modulated Radiotherapy Megavoltage Treatment Beam Imaging

International Nuclear Information System (INIS)

Mao Weihua; Hsu, Annie; Riaz, Nadeem; Lee, Louis; Wiersma, Rodney; Luxton, Gary; King, Christopher; Xing Lei; Solberg, Timothy

2009-01-01

Purpose: To utilize image-guided radiotherapy (IGRT) in near real time by obtaining and evaluating the online positions of implanted fiducials from continuous electronic portal imaging device (EPID) imaging of prostate intensity-modulated radiotherapy (IMRT) delivery. Methods and Materials: Upon initial setup using two orthogonal images, the three-dimensional (3D) positions of all implanted fiducial markers are obtained, and their expected two-dimensional (2D) locations in the beam's-eye-view (BEV) projection are calculated for each treatment field. During IMRT beam delivery, EPID images of the megavoltage treatment beam are acquired in cine mode and subsequently analyzed to locate 2D locations of fiducials in the BEV. Simultaneously, 3D positions are estimated according to the current EPID image, information from the setup portal images, and images acquired at other gantry angles (the completed treatment fields). The measured 2D and 3D positions of each fiducial are compared with their expected 2D and 3D setup positions, respectively. Any displacements larger than a predefined tolerance may cause the treatment system to suspend the beam delivery and direct the therapists to reposition the patient. Results: Phantom studies indicate that the accuracy of 2D BEV and 3D tracking are better than 1 mm and 1.4 mm, respectively. A total of 7330 images from prostate treatments were acquired and analyzed, showing a maximum 2D displacement of 6.7 mm and a maximum 3D displacement of 6.9 mm over 34 fractions. Conclusions: This EPID-based, real-time IGRT method can be implemented on any external beam machine with portal imaging capabilities without purchasing any additional equipment, and there is no extra dose delivered to the patient.

SU-F-J-114: On-Treatment Imagereconstruction Using Transit Images of Treatment Beams Through Patient and Thosethrough Planning CT Images

International Nuclear Information System (INIS)

Lee, H; Cho, S; Cheong, K; Jung, J; Jung, S; Kim, J; Yeo, I

2016-01-01

Purpose: To reconstruct patient images at the time of radiation delivery using measured transit images of treatment beams through patient and calculated transit images through planning CT images. Methods: We hypothesize that the ratio of the measured transit images to the calculated images may provide changed amounts of the patient image between times of planning CT and treatment. To test, we have devised lung phantoms with a tumor object (3-cm diameter) placed at iso-center (simulating planning CT) and off-center by 1 cm (simulating treatment). CT images of the two phantoms were acquired; the image of the off-centered phantom, unavailable clinically, represents the reference on-treatment image in the image quality of planning CT. Cine-transit images through the two phantoms were also acquired in EPID from a non-modulated 6 MV beam when the gantry was rotated 360 degrees; the image through the centered phantom simulates calculated image. While the current study is a feasibility study, in reality our computational EPID model can be applicable in providing accurate transit image from MC simulation. Changed MV HU values were reconstructed from the ratio between two EPID projection data, converted to KV HU values, and added to the planning CT, thereby reconstructing the on-treatment image of the patient limited to the irradiated region of the phantom. Results: The reconstructed image was compared with the reference image. Except for local HU differences>200 as a maximum, excellent agreement was found. The average difference across the entire image was 16.2 HU. Conclusion: We have demonstrated the feasibility of a method of reconstructing on-treatment images of a patient using EPID image and planning CT images. Further studies will include resolving the local HU differences and investigation on the dosimetry impact of the reconstructed image.

SU-F-J-114: On-Treatment Imagereconstruction Using Transit Images of Treatment Beams Through Patient and Thosethrough Planning CT Images

Energy Technology Data Exchange (ETDEWEB)

Lee, H; Cho, S [KAIST, Yuseong-gu, Daejeon (Korea, Republic of); Cheong, K [Hallym University Sacred Heart Hospital, Anyang (Korea, Republic of); Jung, J [East Carolina University Greenville, NC (United States); Jung, S [Samsung Medical Cener, Gangnam-gu, Seoul (Korea, Republic of); Kim, J [Yonsei Cancer Center, Seoul (Korea, Republic of); Yeo, I [Loma Linda University Medical Center, Loma Linda, CA (United States)

2016-06-15

Purpose: To reconstruct patient images at the time of radiation delivery using measured transit images of treatment beams through patient and calculated transit images through planning CT images. Methods: We hypothesize that the ratio of the measured transit images to the calculated images may provide changed amounts of the patient image between times of planning CT and treatment. To test, we have devised lung phantoms with a tumor object (3-cm diameter) placed at iso-center (simulating planning CT) and off-center by 1 cm (simulating treatment). CT images of the two phantoms were acquired; the image of the off-centered phantom, unavailable clinically, represents the reference on-treatment image in the image quality of planning CT. Cine-transit images through the two phantoms were also acquired in EPID from a non-modulated 6 MV beam when the gantry was rotated 360 degrees; the image through the centered phantom simulates calculated image. While the current study is a feasibility study, in reality our computational EPID model can be applicable in providing accurate transit image from MC simulation. Changed MV HU values were reconstructed from the ratio between two EPID projection data, converted to KV HU values, and added to the planning CT, thereby reconstructing the on-treatment image of the patient limited to the irradiated region of the phantom. Results: The reconstructed image was compared with the reference image. Except for local HU differences>200 as a maximum, excellent agreement was found. The average difference across the entire image was 16.2 HU. Conclusion: We have demonstrated the feasibility of a method of reconstructing on-treatment images of a patient using EPID image and planning CT images. Further studies will include resolving the local HU differences and investigation on the dosimetry impact of the reconstructed image.

Acción del factor de crecimiento epidérmico sobre el desarrollo de las células estriatales cultivadas

Directory of Open Access Journals (Sweden)

Lázara Castillo

1996-06-01

Full Text Available En este trabajo se describe la acción del factor de crecimiento epidérmico (FCE sobre las células del estriado embrionario en un sistema de cultivo disociado de neuronas y glías. El cultivo de células se preparó a partir de embriones de ratas de 16-17 días. En el sistema de cultivo empleado, la población celular fue cultivada durante 20-24 horas en un medio que contenía suero y, posteriormente, fue tratada con 20 ng/mL del FCE en un medio libre de suero. La eliminación del suero en este período inicial de desarrollo provocó una disminución apreciable de las células vivas en los cultivos tratados y en los controles. Al parecer, la población de células sobrevivientes estaba integrada, en su mayoría, por precursores celulares teniendo en cuenta su capacidad proliferativa. La acción del FCE sobre las células se manifestó en un aumento del número de células debido fundamentalmente a un estímulo de la proliferación de los precursores neuronales y astrocitos. Este efecto estuvo acompañado por una reducción de la diferenciación morfológica neuronal cuando se comparó con los cultivos controles. En los cultivos, a los 16 días, la detección de la actividad específica de la colina acetiltrasferasa evidenció la diferenciación de una subpoblación neuronal colinérgica, las cuales respondieron al tratamiento con el factor de crecimiento nervioso con un aumento de la actividad de la enzima.

A high-speed scintillation-based electronic portal imaging device to quantitatively characterize IMRT delivery.

Science.gov (United States)

Ranade, Manisha K; Lynch, Bart D; Li, Jonathan G; Dempsey, James F

2006-01-01

We have developed an electronic portal imaging device (EPID) employing a fast scintillator and a high-speed camera. The device is designed to accurately and independently characterize the fluence delivered by a linear accelerator during intensity modulated radiation therapy (IMRT) with either step-and-shoot or dynamic multileaf collimator (MLC) delivery. Our aim is to accurately obtain the beam shape and fluence of all segments delivered during IMRT, in order to study the nature of discrepancies between the plan and the delivered doses. A commercial high-speed camera was combined with a terbium-doped gadolinium-oxy-sulfide (Gd2O2S:Tb) scintillator to form an EPID for the unaliased capture of two-dimensional fluence distributions of each beam in an IMRT delivery. The high speed EPID was synchronized to the accelerator pulse-forming network and gated to capture every possible pulse emitted from the accelerator, with an approximate frame rate of 360 frames-per-second (fps). A 62-segment beam from a head-and-neck IMRT treatment plan requiring 68 s to deliver was recorded with our high speed EPID producing approximately 6 Gbytes of imaging data. The EPID data were compared with the MLC instruction files and the MLC controller log files. The frames were binned to provide a frame rate of 72 fps with a signal-to-noise ratio that was sufficient to resolve leaf positions and segment fluence. The fractional fluence from the log files and EPID data agreed well. An ambiguity in the motion of the MLC during beam on was resolved. The log files reported leaf motions at the end of 33 of the 42 segments, while the EPID observed leaf motions in only 7 of the 42 segments. The static IMRT segment shapes observed by the high speed EPID were in good agreement with the shapes reported in the log files. The leaf motions observed during beam-on for step-and-shoot delivery were not temporally resolved by the log files.

A high-speed scintillation-based electronic portal imaging device to quantitatively characterize IMRT delivery

International Nuclear Information System (INIS)

Ranade, Manisha K.; Lynch, Bart D.; Li, Jonathan G.; Dempsey, James F.

2006-01-01

We have developed an electronic portal imaging device (EPID) employing a fast scintillator and a high-speed camera. The device is designed to accurately and independently characterize the fluence delivered by a linear accelerator during intensity modulated radiation therapy (IMRT) with either step-and-shoot or dynamic multileaf collimator (MLC) delivery. Our aim is to accurately obtain the beam shape and fluence of all segments delivered during IMRT, in order to study the nature of discrepancies between the plan and the delivered doses. A commercial high-speed camera was combined with a terbium-doped gadolinium-oxy-sulfide (Gd 2 O 2 S:Tb) scintillator to form an EPID for the unaliased capture of two-dimensional fluence distributions of each beam in an IMRT delivery. The high speed EPID was synchronized to the accelerator pulse-forming network and gated to capture every possible pulse emitted from the accelerator, with an approximate frame rate of 360 frames-per-second (fps). A 62-segment beam from a head-and-neck IMRT treatment plan requiring 68 s to deliver was recorded with our high speed EPID producing approximately 6 Gbytes of imaging data. The EPID data were compared with the MLC instruction files and the MLC controller log files. The frames were binned to provide a frame rate of 72 fps with a signal-to-noise ratio that was sufficient to resolve leaf positions and segment fluence. The fractional fluence from the log files and EPID data agreed well. An ambiguity in the motion of the MLC during beam on was resolved. The log files reported leaf motions at the end of 33 of the 42 segments, while the EPID observed leaf motions in only 7 of the 42 segments. The static IMRT segment shapes observed by the high speed EPID were in good agreement with the shapes reported in the log files. The leaf motions observed during beam-on for step-and-shoot delivery were not temporally resolved by the log files

Morphology evolution of ZrB2 nanoparticles synthesized by sol-gel method

International Nuclear Information System (INIS)

Zhang Yun; Li Ruixing; Jiang Yanshan; Zhao Bin; Duan Huiping; Li Junping; Feng Zhihai

2011-01-01

Zirconium diboride (ZrB 2 ) nanoparticles were synthesized by sol-gel method using zirconium n-propoxide (Zr(OPr) 4 ), boric acid (H 3 BO 3 ), sucrose (C 12 H 22 O 11 ), and acetic acid (AcOH). Clearly, it was a non-aqueous solution system at the very beginning of the reactions. Here, AcOH was used as both chemical modifier and solvent to control Zr(OPr) 4 hydrolysis. Actually, AcOH could dominate the hydrolysis by self-produced water of the chemical propulsion, rather than the help of outer water. C 12 H 22 O 11 was selected, since it can be completely decomposed to carbon. Thus, carbon might be accounted precisely for the carbothermal reduction reaction. Furthermore, we investigated the influence of the gelation temperature on the morphology of ZrB 2 particles. Increasing the gelation temperature, the particle shapes changed from sphere-like particles at 65 deg. C to a particle chain at 75 deg. C, and then form rod-like particles at 85 deg. C. An in-depth HRTEM observation revealed that the nanoparticles of ZrB 2 were gradually fused together to evolve into a particle chain, finally into a rod-like shape. These crystalline nature of ZrB 2 related to the gelation temperature obeyed the 'oriented attachment mechanism' of crystallography. - Graphical Abstract: Increasing the gelation temperature, the particle shapes changed from sphere-like particles at 65 deg. C to a particle chain at 75 deg. C, and then form rod-like particles at 85 deg. C. Highlights: → ZrB 2 nanoparticles were synthesized by sol-gel method in an non-aqueous solution system. → AcOH was used as both chemical modifier and solvent to control Zr(OPr) 4 hydrolysis. → C 12 H 22 O 11 was selected since it can be completely decomposed to carbon. → Increasing the gelation temperature, the particles changed from sphere-like to rod-like ones. → Crystalline nature of ZrB 2 obeyed the 'oriented attachment mechanism' of crystallography.

Hybrid B-Spline Collocation Method for Solving the Generalized Burgers-Fisher and Burgers-Huxley Equations

Directory of Open Access Journals (Sweden)

Imtiaz Wasim

2018-01-01

Full Text Available In this study, we introduce a new numerical technique for solving nonlinear generalized Burgers-Fisher and Burgers-Huxley equations using hybrid B-spline collocation method. This technique is based on usual finite difference scheme and Crank-Nicolson method which are used to discretize the time derivative and spatial derivatives, respectively. Furthermore, hybrid B-spline function is utilized as interpolating functions in spatial dimension. The scheme is verified unconditionally stable using the Von Neumann (Fourier method. Several test problems are considered to check the accuracy of the proposed scheme. The numerical results are in good agreement with known exact solutions and the existing schemes in literature.

Eritema necrolítico migratorio y glucagonoma pancreático

Directory of Open Access Journals (Sweden)

Gerzaín Rodríguez

2016-06-01

Se concluye que los cambios histológicos observados pueden ser claves en la búsqueda de una enfermedad distante de la piel y permiten hacer su diagnóstico. El patrón histológico de vacuolización y necrosis epidérmica subcórnea debe llevar a sospechar la presencia de un glucagonoma pancreático.

Validated HPLC method for determination of sennosides A and B in senna tablets.

Science.gov (United States)

Sun, Shao Wen; Su, Hsiu Ting

2002-07-31

This study developed an efficient and reliable ion-pair liquid chromatographic method for quantitation of sennosides A and B in commercial senna tablets. Separation was conducted on a Hypersil C 18 column (250 x 4.6 mm, 5 microm) at a temperature of 40 degrees C, using a mixture of 0.1 M acetate buffer (pH 6.0) and acetonitrile (70:30, v/v) containing 5 mM tetrahexylammonium bromide as mobile phase. Sennosides A and B were completely separated from other constituents within 14 min. The developed method was validated. Both run-to-run repeatability (n=10) and day-to-day reproducibility (n=3) of peak area were below 0.4% RSD. Linearity of peak area was tested in the range 30-70 microg/ml (r>0.9997). Accuracy was assessed with recovery and the recoveries for sennosides A and B were 101.73+/-1.30% and 101.81+/-2.18% (n=3 x 6), respectively. Robustness of the analytical method was tested using a three-leveled Plackett-Burman design in which 11 factors were assessed with 23 experiments. Eight factors (column, concentration of ion pair reagent, % of organic modifier (acetonitrile), buffer pH, column temperature, flow rate, time constant and detection wavelength) were investigated in a specified range above and below the nominal method conditions. It was found that: (1) column and % acetonitrile affected significantly resolution and retention time, (2) column, % acetonitrile, column temperature, flow rate and time constant affected significantly the plate number of sennoside A, and (3) column and time constant affected significantly the tailing factor.

Two-step B/T (burning and/or transmutation) method for self-completed nuclear fuel cycle with thermal and fast B/T reactors

International Nuclear Information System (INIS)

Kitamoto, A.; Mulyanto, M.R.; Marsodi, M.R.

1995-01-01

The total cost minimization for P and T (partitioning and transmutation) treatment with appropriate recycle period through out-core optimization was examined in order to find the possibility of P and T treatment of minor actinides (MA) and/or long lived fission products (LLFP) and the technology to be improved and/or developed in self-completed nuclear fuel cycle. The P and T should be done for B/T (burning and/or transmutation) treatment based on three criteria, and the grouping was closely related to the effectiveness of Two-Step B/T Method in B/T treatment. (authors)

Numerical Solution of the Blasius Viscous Flow Problem by Quartic B-Spline Method

Directory of Open Access Journals (Sweden)

Hossein Aminikhah

2016-01-01

Full Text Available A numerical method is proposed to study the laminar boundary layer about a flat plate in a uniform stream of fluid. The presented method is based on the quartic B-spline approximations with minimizing the error L2-norm. Theoretical considerations are discussed. The computed results are compared with some numerical results to show the efficiency of the proposed approach.

Efecto de Brugmansia arborea (L. Lagerheim (Solanacea en el sistema reproductor masculino de ratón

Directory of Open Access Journals (Sweden)

José Pino

2008-12-01

Full Text Available El objetivo del presente estudio fué investigar el efecto de la administracion del extracto acuoso de Brugmansia arborea (L. Lagerheim -floripondio-sobre algunos parámetros reproductivos en mamíferos. Ratones machos fueron tratados con 70 mg/kl/pc por 7 días, después de lo cual fueron eutanizados determinando los pesos de testículo, epidídimo e individualmente su región caudal; además, se contabilizó la concentración y malformaciones espermáticas. El peso del testículo y la cola del epidídimo disminuyeron; la concentración espermática fue menor que el control, se incrementaron las malformaciones espermáticas. Estos resultados sugieren que existe un efecto negativo de la dosis de B. arborea que alteraría la fertilidad del ratón.

Bulk superhard B-C-N nanocomposite compact and method for preparing thereof

Science.gov (United States)

Zhao, Yusheng; He, Duanwei

2004-07-06

Bulk, superhard, B-C-N nanocomposite compact and method for preparing thereof. The bulk, superhard, nanocomposite compact is a well-sintered compact and includes nanocrystalline grains of at least one high-pressure phase of B-C-N surrounded by amorphous diamond-like carbon grain boundaries. The bulk compact has a Vicker's hardness of about 41-68 GPa. It is prepared by ball milling a mixture of graphite and hexagonal boron nitride, encapsulating the ball-milled mixture, and sintering the encapsulated ball-milled mixture at a pressure of about 5-25 GPa and at a temperature of about 1000-2500 K.

An evaluation of commercial radioisotope methods for the determination of folate and vitamin B12

International Nuclear Information System (INIS)

Dawson, D.W.

1980-01-01

Five commercial kits for the determination of folate and six kits for the determination of vitamin B 12 were investigated. Their performance has been compared with microbiological methods for the two vitamins and with a non-commercial radioisotopic method for B 12 . The results show the importance of the determination of the reference range for an individual laboratory for each method. The precision of the kits varied appreciably, as did their performance using specimens from patients with different haematological disorders. In particular, certain kits failed to detect all patients with pernicious anaemia. The relative accuracy of the kits was assessed. Various factors which should be taken into account in the final selection of a satisfactory kit are discussed. (author)

Preparation and Microstructure of Porous ZrB2 Ceramics Using Reactive Spark Plasma Sintering Method

Institute of Scientific and Technical Information of China (English)

YUAN Huiping; LI Junguo; SHEN Qiang; ZHANG Lianmeng

2015-01-01

Zirconium oxide (ZrO2) and boron carbide (B4C) were added to ZrB2 raw powders to prepare ZrB2 porous ceramics by reactive spark plasma sintering (RSPS). The reactions between ZrO2 and B4C which produce ZrB2 and gas (such as CO and B2O3) result in pore formation. X-Ray Diffraction results indicated that the products phase was ZrB2 and the reaction was completed after the RSPS process. The porosity could be controlled by changing the ratio of synthesized ZrB2 to raw ZrB2 powders. The porosity of porous ceramics with 20 wt% and 40 wt% synthsized ZrB2 are 0.185 and 0.222, respectivly. And dense ZrB2-SiC ceramic with a porosity of 0.057 was prepared under the same conditions for comparison. The pores were homogeneously distributed within the microstructure of the porous ceramics. The results indicate a promising method for preparing porous ZrB2-based ceramics.

Automated analysis of images acquired with electronic portal imaging device during delivery of quality assurance plans for inversely optimized arc therapy

DEFF Research Database (Denmark)

Fredh, Anna; Korreman, Stine; Rosenschöld, Per Munck af

2010-01-01

This work presents an automated method for comprehensively analyzing EPID images acquired for quality assurance of RapidArc treatment delivery. In-house-developed software has been used for the analysis and long-term results from measurements on three linacs are presented....

An iterative method for the analysis of Cherenkov rings in the HERA-B RICH

International Nuclear Information System (INIS)

Staric, M.; Krizan, P.

1999-01-01

A new method is presented for the analysis of data recorded with a Ring Imaging Cherenkov (RICH) counter. The method, an iterative sorting of hits on the photon detector, is particularly useful for events where rings overlap considerably. The algorithm was tested on simulated data for the HERA-B experiment

An alternative effective method for verifying the multileaf collimator leaves speed by using a digital-video imaging system

International Nuclear Information System (INIS)

Hwang, Ing-Ming; Wu, Jay; Chuang, Keh-Shih; Ding, Hueisch-Jy

2010-01-01

We present an alternative effective method for verifying the multileaf collimator (MLC) leaves speed using a digital-video imaging system in daily dynamic conformal radiation therapy (DCRT) and intensity-modulation radiation therapy (IMRT) in achieving increased convenience and shorter treatment times. The horizontal leaves speed measured was within 1.76-2.08 cm/s. The mean full range of traveling time was 20 s. The initial speed-up time was within 1.5-2.0 s, and the slowing-down time was within 2.0-2.5 s. Due to gravity the maximum speed-up effect in the X1 bank was +0.10 cm/s, but the lagging effect in the X2 bank was -0.20 cm/s. This technique offered an alternative method with electronic portal imaging device (EPID), charged coupled device (CCD) or a light field for the measurement of MLC leaves speed. When time taken on the linac was kept to a minimum, the image could be processed off-line.

Estimation of four-dimensional dose distribution using electronic portal imaging device in radiation therapy

International Nuclear Information System (INIS)

Mizoguchi, Asumi; Arimura, Hidetaka; Shioyama, Yoshiyuki

2013-01-01

We are developing a method to evaluate four-dimensional radiation dose distribution in a patient body based upon the animated image of EPID (electronic portal imaging device) which is an image of beam-direction at the irradiation. In the first place, we have obtained the image of the dose which is emitted from patient body at therapy planning using therapy planning CT image and dose evaluation algorism. In the second place, we have estimated the emission dose image at the irradiation using EPID animated image which is obtained at the irradiation. In the third place, we have got an affine transformation matrix including respiratory movement in the body by performing linear registration on the emission dose image at therapy planning to get the one at the irradiation. In the fourth place, we have applied the affine transformation matrix on the therapy planning CT image and estimated the CT image 'at irradiation'. Finally we have evaluated four-dimensional dose distribution by calculating dose distribution in the CT image 'at irradiation' which has been estimated for each frame of the EPID animated-image. This scheme may be useful for evaluating therapy results and risk management. (author)

Microscopic unravelling of nano-carbon doping in MgB{sub 2} superconductors fabricated by diffusion method

Energy Technology Data Exchange (ETDEWEB)

Wong, D.C.K. [School of Physics, The University of Sydney, New South Wales 2006 (Australia); Yeoh, W.K. [School of Aerospace, Mechanical and Mechatronic Engineering, The University of Sydney, New South Wales 2006 (Australia); Australian Centre for Microscopy & Microanalysis, The University of Sydney, New South Wales 2006 (Australia); De Silva, K.S.B. [Institute for Superconducting & Electronic Materials, University of Wollongong, North Wollongong, New South Wales 2500 (Australia); Institute for Nanoscale Technology, Faculty of Science, University of Technology Sydney, Ultimo, New South Wales 2007 (Australia); Kondyurin, A.; Bao, P. [School of Physics, The University of Sydney, New South Wales 2006 (Australia); Li, W.X. [School of Materials Science and Engineering, Shanghai University, Shanghai 200072 (China); Xu, X.; Peleckis, G.; Dou, S.X. [Institute for Superconducting & Electronic Materials, University of Wollongong, North Wollongong, New South Wales 2500 (Australia); Ringer, S.P. [School of Aerospace, Mechanical and Mechatronic Engineering, The University of Sydney, New South Wales 2006 (Australia); Australian Centre for Microscopy & Microanalysis, The University of Sydney, New South Wales 2006 (Australia); Zheng, R.K., E-mail: rongkun.zheng@sydney.edu.au [School of Physics, The University of Sydney, New South Wales 2006 (Australia)

2015-09-25

Highlights: • First report on nano-carbon doped MgB{sub 2} superconductors synthesized by diffusion method. • Microstructure and superconducting properties of the superconductors are discussed. • B{sub 4}C region blocks the Mg from reacting with B in the 10% nano-carbon doped sample. • MgB{sub 2} with 2.5% nano-carbon doped showed the highest J{sub c}, ≈10{sup 4} A/cm{sup 2} for 20 K at 4 T. - Abstract: We investigated the effects of nano-carbon doping as the intrinsic (B-site nano-carbon substitution) and extrinsic (nano-carbon derivatives) pinning by diffusion method. The contraction of the in-plane lattice confirmed the presence of disorder in boron sublattice caused by carbon substitution. The increasing value in full width half maximum (FWHM) in the X-ray diffraction (XRD) patterns with each increment in the doping level reveal smaller grains and imperfect MgB{sub 2} crystalline. The strain increased across the doping level due to the carbon substitution in the MgB{sub 2} matrix. The broadening of the T{sub c} curves from low to high doping showed suppression of the connectivity of the bulk samples with progressive dirtying. At high doping, the presence of B{sub 4}C region blocked the Mg from reacting with crystalline B thus hampering the formation of MgB{sub 2}. Furthermore, the unreacted Mg acted as a current blocking phase in lowering down the grain connectivity hence depressing the J{sub c} of the 10% nano-carbon doped MgB{sub 2} bulk superconductor.

Experience Using DosimetryCheck software for IMRT and RapidArc Patient Pre-treatment QA and a New Feature for QA during Treatment

International Nuclear Information System (INIS)

Pinkerton, Arthur; Hannon, Michael; Kwag, Jae; Renner, Wendel Dean

2010-01-01

We have used the DosimetryCheck program with the EPID's on our Varian 2100EX's to perform pre-treatment QA on more than 350 patients, between the last quarter of 2006 and the present. The software uses the EPID measured fluences of the treatment fields to reconstruct the dose distribution in the CT planning model of the patient. Since the dose calculation algorithm, is different from that used by our Eclipse planning system, this provides an independent check of planning accuracy as well as treatment delivery. 2D and 3D dose distributions, point doses, Gamma distributions, DVH statistics and MU calculations can be compared. Absolute differences of Reference Point doses between Dosimetry Check and Eclipse average 1.20%, which is similar to the ionization chamber dose differences of 1.29% for the same patient verification plans. Examples of cases for various treatment sites and delivery modes will be presented. A Special Report in Medical Physics Vol. 37 Number 6 Pg. 2638-2644 from Mans et al at The Netherlands Cancer Institute demonstrated the ability of in vivo EPID dosimetry to detect treatment errors, that escaped other QA checks. A new version of DosimetryCheck awaiting FDA approval, is capable of successfully reconstructing the dose distribution in the patient from the EPID measured exit fluences. This can also be applied to CBCT images providing actual patient dose verification for a treatment session. This should be particularly useful for monitoring hypo-fractionated treatment regimens. Examples of this method will also be presented.

Initial Clinical Experience Performing Patient Treatment Verification With an Electronic Portal Imaging Device Transit Dosimeter

Energy Technology Data Exchange (ETDEWEB)

Berry, Sean L., E-mail: BerryS@MSKCC.org [Department of Applied Physics and Applied Mathematics, Columbia University, New York, New York (United States); Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, New York, New York (United States); Polvorosa, Cynthia; Cheng, Simon; Deutsch, Israel; Chao, K. S. Clifford; Wuu, Cheng-Shie [Department of Radiation Oncology, Columbia University, New York, New York (United States)

2014-01-01

Purpose: To prospectively evaluate a 2-dimensional transit dosimetry algorithm's performance on a patient population and to analyze the issues that would arise in a widespread clinical adoption of transit electronic portal imaging device (EPID) dosimetry. Methods and Materials: Eleven patients were enrolled on the protocol; 9 completed and were analyzed. Pretreatment intensity modulated radiation therapy (IMRT) patient-specific quality assurance was performed using a stringent local 3%, 3-mm γ criterion to verify that the planned fluence had been appropriately transferred to and delivered by the linear accelerator. Transit dosimetric EPID images were then acquired during treatment and compared offline with predicted transit images using a global 5%, 3-mm γ criterion. Results: There were 288 transit images analyzed. The overall γ pass rate was 89.1% ± 9.8% (average ± 1 SD). For the subset of images for which the linear accelerator couch did not interfere with the measurement, the γ pass rate was 95.7% ± 2.4%. A case study is presented in which the transit dosimetry algorithm was able to identify that a lung patient's bilateral pleural effusion had resolved in the time between the planning CT scan and the treatment. Conclusions: The EPID transit dosimetry algorithm under consideration, previously described and verified in a phantom study, is feasible for use in treatment delivery verification for real patients. Two-dimensional EPID transit dosimetry can play an important role in indicating when a treatment delivery is inconsistent with the original plan.

EPMLR: sequence-based linear B-cell epitope prediction method using multiple linear regression.

Science.gov (United States)

Lian, Yao; Ge, Meng; Pan, Xian-Ming

2014-12-19

B-cell epitopes have been studied extensively due to their immunological applications, such as peptide-based vaccine development, antibody production, and disease diagnosis and therapy. Despite several decades of research, the accurate prediction of linear B-cell epitopes has remained a challenging task. In this work, based on the antigen's primary sequence information, a novel linear B-cell epitope prediction model was developed using the multiple linear regression (MLR). A 10-fold cross-validation test on a large non-redundant dataset was performed to evaluate the performance of our model. To alleviate the problem caused by the noise of negative dataset, 300 experiments utilizing 300 sub-datasets were performed. We achieved overall sensitivity of 81.8%, precision of 64.1% and area under the receiver operating characteristic curve (AUC) of 0.728. We have presented a reliable method for the identification of linear B cell epitope using antigen's primary sequence information. Moreover, a web server EPMLR has been developed for linear B-cell epitope prediction: http://www.bioinfo.tsinghua.edu.cn/epitope/EPMLR/ .

Ultrastable, high efficiency picosecond green light generation using K3B6O10Br series nonlinear optical crystals

Science.gov (United States)

Hou, Z. Y.; Xia, M. J.; Wang, L. R.; Xu, B.; Yan, D. X.; Meng, L. P.; Liu, L. J.; Xu, D. G.; Zhang, L.; Wang, X. Y.; Li, R. K.; Chen, C. T.

2017-09-01

Two perovskite-structure K3B6O10Br1-x Cl x (x  =  0 and 0.5) series nonlinear optical crystals were thoroughly investigated for their picosecond 532 nm laser pulses abilities and high power outputs were achieved via second harmonic generation (SHG) technique for the first time. SHG conversion efficiency of 57.3% with a 13.2 mm length K3B6O10Br (KBB) crystal was achieved using a laser source of pulse repetition rate of 10 Hz and pulse width of 25 ps, which is the highest conversion efficiency of ps visible laser based on KBB crystal. And by employing an 80 MHz, 10 ps fundamental laser beam, maximum power outputs of 12 W with K3B6O10Br0.5Cl0.5 (KBBC) and 11.86 W with KBB crystals were successfully demonstrated. Furthermore, the standard deviation jitters of the average power outputs are less than 0.6% and 1.17% by KBB and KBBC, respectively, showing ultrastable power stabilities favorable for practical applications. In addition, the other optical parameters including acceptance angle and temperature bandwidth were also investigated.

Numerical simulation of reaction-diffusion systems by modified cubic B-spline differential quadrature method

International Nuclear Information System (INIS)

Mittal, R.C.; Rohila, Rajni

2016-01-01

In this paper, we have applied modified cubic B-spline based differential quadrature method to get numerical solutions of one dimensional reaction-diffusion systems such as linear reaction-diffusion system, Brusselator system, Isothermal system and Gray-Scott system. The models represented by these systems have important applications in different areas of science and engineering. The most striking and interesting part of the work is the solution patterns obtained for Gray Scott model, reminiscent of which are often seen in nature. We have used cubic B-spline functions for space discretization to get a system of ordinary differential equations. This system of ODE’s is solved by highly stable SSP-RK43 method to get solution at the knots. The computed results are very accurate and shown to be better than those available in the literature. Method is easy and simple to apply and gives solutions with less computational efforts.

A literature review of electronic portal imaging for radiotherapy dosimetry

NARCIS (Netherlands)

van Elmpt, Wouter; McDermott, Leah; Nijsten, Sebastiaan; Wendling, Markus; Lambin, Philippe; Mijnheer, Ben

2008-01-01

Electronic portal imaging devices (EPIDs) have been the preferred tools for verification of patient positioning for radiotherapy in recent decades. Since EPID images contain dose information, many groups have investigated their use for radiotherapy dose measurement. With the introduction of the

SU-E-T-195: Gantry Angle Dependency of MLC Leaf Position Error

Energy Technology Data Exchange (ETDEWEB)

Ju, S; Hong, C; Kim, M; Chung, K; Kim, J; Han, Y; Ahn, S; Chung, S; Shin, E; Shin, J; Kim, H; Kim, D; Choi, D [Department of Radiation Oncology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul (Korea, Republic of)

2014-06-01

Purpose: The aim of this study was to investigate the gantry angle dependency of the multileaf collimator (MLC) leaf position error. Methods: An automatic MLC quality assurance system (AutoMLCQA) was developed to evaluate the gantry angle dependency of the MLC leaf position error using an electronic portal imaging device (EPID). To eliminate the EPID position error due to gantry rotation, we designed a reference maker (RM) that could be inserted into the wedge mount. After setting up the EPID, a reference image was taken of the RM using an open field. Next, an EPID-based picket-fence test (PFT) was performed without the RM. These procedures were repeated at every 45° intervals of the gantry angle. A total of eight reference images and PFT image sets were analyzed using in-house software. The average MLC leaf position error was calculated at five pickets (-10, -5, 0, 5, and 10 cm) in accordance with general PFT guidelines using in-house software. This test was carried out for four linear accelerators. Results: The average MLC leaf position errors were within the set criterion of <1 mm (actual errors ranged from -0.7 to 0.8 mm) for all gantry angles, but significant gantry angle dependency was observed in all machines. The error was smaller at a gantry angle of 0° but increased toward the positive direction with gantry angle increments in the clockwise direction. The error reached a maximum value at a gantry angle of 90° and then gradually decreased until 180°. In the counter-clockwise rotation of the gantry, the same pattern of error was observed but the error increased in the negative direction. Conclusion: The AutoMLCQA system was useful to evaluate the MLC leaf position error for various gantry angles without the EPID position error. The Gantry angle dependency should be considered during MLC leaf position error analysis.

MO-FG-202-04: Gantry-Resolved Linac QA for VMAT: A Comprehensive and Efficient System Using An Electronic Portal Imaging Device

Energy Technology Data Exchange (ETDEWEB)

Zwan, B J [Central Coast Cancer Centre, Gosford, NSW (Australia); University of Newcastle, Newcastle, NSW (Australia); Barnes, M; Greer, P B [University of Newcastle, Newcastle, NSW (Australia); Calvary Mater Hospital, Newcastle, NSW (Australia); Hindmarsh, J; Seymour, E [Central Coast Cancer Centre, Gosford, NSW (Australia); O’Connor, D J [University of Newcastle, Newcastle, NSW (Australia); Keall, P J [University of Sydney, Camperdown, NSW (Australia)

2016-06-15

Purpose: To automate gantry-resolved linear accelerator (linac) quality assurance (QA) for volumetric modulated arc therapy (VMAT) using an electronic portal imaging device (EPID). Methods: A QA system for VMAT was developed that uses an EPID, frame-grabber assembly and in-house developed image processing software. The system relies solely on the analysis of EPID image frames acquired without the presence of a phantom. Images were acquired at 8.41 frames per second using a frame grabber and ancillary acquisition computer. Each image frame was tagged with a gantry angle from the linac’s on-board gantry angle encoder. Arc-dynamic QA plans were designed to assess the performance of each individual linac component during VMAT. By analysing each image frame acquired during the QA deliveries the following eight machine performance characteristics were measured as a function of gantry angle: MLC positional accuracy, MLC speed constancy, MLC acceleration constancy, MLC-gantry synchronisation, beam profile constancy, dose rate constancy, gantry speed constancy, dose-gantry angle synchronisation and mechanical sag. All tests were performed on a Varian iX linear accelerator equipped with a 120 leaf Millennium MLC and an aS1000 EPID (Varian Medical Systems, Palo Alto, CA, USA). Results: Machine performance parameters were measured as a function of gantry angle using EPID imaging and compared to machine log files and the treatment plan. Data acquisition is currently underway at 3 centres, incorporating 7 treatment units, at 2 weekly measurement intervals. Conclusion: The proposed system can be applied for streamlined linac QA and commissioning for VMAT. The set of test plans developed can be used to assess the performance of each individual components of the treatment machine during VMAT deliveries as a function of gantry angle. The methodology does not require the setup of any additional phantom or measurement equipment and the analysis is fully automated to allow for

MO-FG-202-04: Gantry-Resolved Linac QA for VMAT: A Comprehensive and Efficient System Using An Electronic Portal Imaging Device

International Nuclear Information System (INIS)

Zwan, B J; Barnes, M; Greer, P B; Hindmarsh, J; Seymour, E; O’Connor, D J; Keall, P J

2016-01-01

Purpose: To automate gantry-resolved linear accelerator (linac) quality assurance (QA) for volumetric modulated arc therapy (VMAT) using an electronic portal imaging device (EPID). Methods: A QA system for VMAT was developed that uses an EPID, frame-grabber assembly and in-house developed image processing software. The system relies solely on the analysis of EPID image frames acquired without the presence of a phantom. Images were acquired at 8.41 frames per second using a frame grabber and ancillary acquisition computer. Each image frame was tagged with a gantry angle from the linac’s on-board gantry angle encoder. Arc-dynamic QA plans were designed to assess the performance of each individual linac component during VMAT. By analysing each image frame acquired during the QA deliveries the following eight machine performance characteristics were measured as a function of gantry angle: MLC positional accuracy, MLC speed constancy, MLC acceleration constancy, MLC-gantry synchronisation, beam profile constancy, dose rate constancy, gantry speed constancy, dose-gantry angle synchronisation and mechanical sag. All tests were performed on a Varian iX linear accelerator equipped with a 120 leaf Millennium MLC and an aS1000 EPID (Varian Medical Systems, Palo Alto, CA, USA). Results: Machine performance parameters were measured as a function of gantry angle using EPID imaging and compared to machine log files and the treatment plan. Data acquisition is currently underway at 3 centres, incorporating 7 treatment units, at 2 weekly measurement intervals. Conclusion: The proposed system can be applied for streamlined linac QA and commissioning for VMAT. The set of test plans developed can be used to assess the performance of each individual components of the treatment machine during VMAT deliveries as a function of gantry angle. The methodology does not require the setup of any additional phantom or measurement equipment and the analysis is fully automated to allow for

LAMP-B: a Fortran program set for the lattice cell analysis by collision probability method

International Nuclear Information System (INIS)

Tsuchihashi, Keiichiro

1979-02-01

Nature of physical problem solved: LAMB-B solves an integral transport equation by the collision probability method for many variety of lattice cell geometries: spherical, plane and cylindrical lattice cell; square and hexagonal arrays of pin rods; annular clusters and square clusters. LAMP-B produces homogenized constants for multi and/or few group diffusion theory programs. Method of solution: LAMP-B performs an exact numerical integration to obtain the collision probabilities. Restrictions on the complexity of the problem: Not more than 68 group in the fast group calculation, and not more than 20 regions in the resonance integral calculation. Typical running time: It varies with the number of energy groups and the selection of the geometry. Unusual features of the program: Any or any combination of constituent subprograms can be used so that the partial use of this program is available. (author)

FDIR Strategy Validation with the B Method

Science.gov (United States)

Sabatier, D.; Dellandrea, B.; Chemouil, D.

2008-08-01

In a formation flying satellite system, the FDIR strategy (Failure Detection, Isolation and Recovery) is paramount. When a failure occurs, satellites should be able to take appropriate reconfiguration actions to obtain the best possible results given the failure, ranging from avoiding satellite-to-satellite collision to continuing the mission without disturbance if possible. To achieve this goal, each satellite in the formation has an implemented FDIR strategy that governs how it detects failures (from tests or by deduction) and how it reacts (reconfiguration using redundant equipments, avoidance manoeuvres, etc.). The goal is to protect the satellites first and the mission as much as possible. In a project initiated by the CNES, ClearSy experiments the B Method to validate the FDIR strategies developed by Thales Alenia Space, of the inter satellite positioning and communication devices that will be used for the SIMBOL-X (2 satellite configuration) and the PEGASE (3 satellite configuration) missions and potentially for other missions afterward. These radio frequency metrology sensor devices provide satellite positioning and inter satellite communication in formation flying. This article presents the results of this experience.

Study of the 10B(p,α)7Be Reaction through the Indirect Trojan Horse Method

International Nuclear Information System (INIS)

Puglia, S. M. R.; Romano, S.; Lamia, L.; Spitaleri, C.; Cherubini, S.; Gulino, M.; La Cognata, M.; Pizzone, R. G.; Rapisarda, G. G.; Sergi, M. L.; Tudisco, S.; Del Santo, M. G.; Carlin, N.; Souza, F.; Szanto de Toledo, A.; Kroha, V.; Kubono, S.; Wakabayashi, Y.; Yamaguchi, H.; Li, C.

2010-01-01

The 10 B(p,α) 7 Be reaction is the main responsible for 10 B destruction in stellar interior. In such environments the process takes places mainly through a resonant state of the compound 11 C nucleus. The 10 B(p,α) 7 Be reaction has been studied by means of the Trojan Horse Method using the 2 H( 10 B,α 7 Be)n three-body reaction. The experiment was performed at the Laboratori Nazionali del Sud in Catania. The 10 B(p,α) 7 Be reaction cross section has been extracted at low neutron momentum.

Investigations with a simplified method for radiometric determination of vitamin B12 in body fluids and feeding stuffs

International Nuclear Information System (INIS)

Menke, K.H.; Kohlberger, G.; Koenemund, A.

1979-01-01

A modified method for radiometrical determination of vitamin B 12 is described, which in difference to the known methods is based on measurement of free B 12 after absorption to albumin-coated charcoal instead of measurement of intrinsic factor B 12 -complex. The conditions for extraction from serum, milk, rumen-liquor and urine have been investigated and the effect of pH on IF-B 12 -binding in presence of these body fluids examined. Parallel microbiological determinations (O.m.- and L.1.-test) were in good correlation (r = 0,93-0,97) to radiometrically determined B 12 -contents in milk and rumen-liquor, but not to that in serum of dairy cows (r = 0,54-0,82). The analytical procedures are given in detail. (orig.) [de

10 CFR Appendix X to Subpart B of... - Uniform Test Method for Measuring the Energy Consumption of Dehumidifiers

Science.gov (United States)

2010-01-01

... 10 Energy 3 2010-01-01 2010-01-01 false Uniform Test Method for Measuring the Energy Consumption of Dehumidifiers X Appendix X to Subpart B of Part 430 Energy DEPARTMENT OF ENERGY ENERGY... Appendix X to Subpart B of Part 430—Uniform Test Method for Measuring the Energy Consumption of...

Comparison of two methods for purification of enterocin B, a bacteriocin produced by Enterococcus faecium W3.

Science.gov (United States)

Dündar, Halil; Atakay, Mehmet; Çelikbıçak, Ömür; Salih, Bekir; Bozoğlu, Faruk

2015-01-01

This study aimed to compare two different approaches for the purification of enterocin B from Enterococcus faecium strain W3 based on the observation that the bacteriocin was found both in cell associated form and in culture supernatant. The first approach employed ammonium sulfate precipitation, cation-exchange chromatography, and sequential reverse-phase high-performance liquid chromatography. The latter approach exploited a pH-mediated cell adsorption-desorption method to extract cell-bound bacteriocin, and one run of reverse-phase chromatography. The first method resulted in purification of enterocin B with a recovery of 4% of the initial bacteriocin activity found in culture supernatant. MALDI-TOF MS analysis and de novo peptide sequencing of the purified bacteriocin confirmed that the active peptide was enterocin B. The second method achieved the purification of enterocin B with a higher recovery (16%) and enabled us to achieve pure bacteriocin within a shorter period of time by avoiding time consuming purification protocols. The purity and identity of the active peptide were confirmed again by matrix-assisted laser desorption/ionization time-of flight (MALDI-TOF) mass spectrometry (MS) analysis. Although both approaches were satisfactory to obtain a sufficient amount of enterocin B for use in MS and amino acid sequence analysis, the latter was proved to be applicable in large-scale and rapid purification of enterocin B.

Iterative methods for solving Ax=b, GMRES/FOM versus QMR/BiCG

Energy Technology Data Exchange (ETDEWEB)

Cullum, J. [IBM Research Division, Yorktown Heights, NY (United States)

1996-12-31

We study the convergence of GMRES/FOM and QMR/BiCG methods for solving nonsymmetric Ax=b. We prove that given the results of a BiCG computation on Ax=b, we can obtain a matrix B with the same eigenvalues as A and a vector c such that the residual norms generated by a FOM computation on Bx=c are identical to those generated by the BiCG computations. Using a unitary equivalence for each of these methods, we obtain test problems where we can easily vary certain spectral properties of the matrices. We use these test problems to study the effects of nonnormality on the convergence of GMRES and QMR, to study the effects of eigenvalue outliers on the convergence of QMR, and to compare the convergence of restarted GMRES, QMR, and BiCGSTAB across a family of normal and nonnormal problems. Our GMRES tests on nonnormal test matrices indicate that nonnormality can have unexpected effects upon the residual norm convergence, giving misleading indications of superior convergence over QMR when the error norms for GMRES are not significantly different from those for QMR. Our QMR tests indicate that the convergence of the QMR residual and error norms is influenced predominantly by small and large eigenvalue outliers and by the character, real, complex, or nearly real, of the outliers and the other eigenvalues. In our comparison tests QMR outperformed GMRES(10) and GMRES(20) on both the normal and nonnormal test matrices.

Are steroids effective in toxic epidermal necrolysis and Stevens-Johnson syndrome?

Directory of Open Access Journals (Sweden)

Rodrigo Meza

2017-06-01

Full Text Available Resumen La necrólisis epidérmica tóxica y el síndrome de Stevens-Johnson son reacciones cutáneas adversas graves a medicamentos e infecciones. Los corticoides se describen como una alternativa terapéutica, sin embargo, su uso es aún controvertido. Utilizando la base de datos Epistemonikos, la cual es mantenida mediante búsquedas en múltiples bases de datos, identificamos cuatro revisiones sistemáticas que en conjunto incluyen once estudios primarios que responden la pregunta de interés. Extrajimos los datos y preparamos una tabla de resumen de los resultados utilizando el método GRADE. Concluimos que no está claro si los corticoides disminuyen la mortalidad o la estadía hospitalaria en la necrólisis epidérmica tóxica y el síndrome de Stevens-Johnson porque la certeza de la evidencia es muy baja.

Novel Spectrofluorimetric Method for the Determination of Perindopril Erbumine Based on Fluorescence Quenching of Rhodamine B.

Science.gov (United States)

Fael, Hanan; Sakur, Amir Al-Haj

2015-11-01

A novel, simple and specific spectrofluorimetric method was developed and validated for the determination of perindopril erbumine (PDE). The method is based on the fluorescence quenching of Rhodamine B upon adding perindopril erbumine. The quenched fluorescence was monitored at 578 nm after excitation at 500 nm. The optimization of the reaction conditions such as the solvent, reagent concentration, and reaction time were investigated. Under the optimum conditions, the fluorescence quenching was linear over a concentration range of 1.0-6.0 μg/mL. The proposed method was fully validated and successfully applied to the analysis of perindopril erbumine in pure form and tablets. Statistical comparison of the results obtained by the developed and reference methods revealed no significant differences between the methods compared in terms of accuracy and precision. The method was shown to be highly specific in the presence of indapamide, a diuretic that is commonly combined with perindopril erbumine. The mechanism of rhodamine B quenching was also discussed.

A spectral/B-spline method for the Navier-Stokes equations in unbounded domains

International Nuclear Information System (INIS)

Dufresne, L.; Dumas, G.

2003-01-01

The numerical method presented in this paper aims at solving the incompressible Navier-Stokes equations in unbounded domains. The problem is formulated in cylindrical coordinates and the method is based on a Galerkin approximation scheme that makes use of vector expansions that exactly satisfy the continuity constraint. More specifically, the divergence-free basis vector functions are constructed with Fourier expansions in the θ and z directions while mapped B-splines are used in the semi-infinite radial direction. Special care has been taken to account for the particular analytical behaviors at both end points r=0 and r→∞. A modal reduction algorithm has also been implemented in the azimuthal direction, allowing for a relaxation of the CFL constraint on the timestep size and a possibly significant reduction of the number of DOF. The time marching is carried out using a mixed quasi-third order scheme. Besides the advantages of a divergence-free formulation and a quasi-spectral convergence, the local character of the B-splines allows for a great flexibility in node positioning while keeping narrow bandwidth matrices. Numerical tests show that the present method compares advantageously with other similar methodologies using purely global expansions

Coercivity of Nd-Fe-B hot-deformed magnets produced by the spark plasma sintering method

Directory of Open Access Journals (Sweden)

Tetsuji Saito

2017-05-01

Full Text Available The effects of Nd-Cu alloy powder addition on the microstructures and magnetic properties of Nd-Fe-B hot-deformed magnets produced by the spark plasma sintering (SPS method were investigated. The addition of a small amount of Nd-Cu alloy powder, up to 2%, significantly increased the coercivity of the Nd-Fe-B hot-deformed magnets without deteriorating the crystallographic alignment of the Nd2Fe14B phase. The Nd-Fe-B hot-deformed magnet with 2% Nd-Cu alloy powder had the same remanence value as the Nd-Fe-B hot-deformed magnet without Nd-Cu alloy powder addition, but the magnet with 2% Nd-Cu alloy powder exhibited higher coercivity and a higher maximum energy product than the magnet without Nd-Cu alloy powder addition.

SU-E-J-35: Using CBCT as the Alternative Method of Assessing ITV Volume

Energy Technology Data Exchange (ETDEWEB)

Liao, Y; Turian, J; Templeton, A; Redler, G; Chu, J [Rush University Medical Center, Chicago, IL (United States)

2015-06-15

Purpose To study the accuracy of Internal Target Volumes (ITVs) created on cone beam CT (CBCT) by comparing the visible target volume on CBCT to volumes (GTV, ITV, and PTV) outlined on free breathing (FB) CT and 4DCT. Methods A Quasar Cylindrical Motion Phantom with a 3cm diameter ball (14.14 cc) embedded within a cork insert was set up to simulate respiratory motion with a period of 4 seconds and amplitude of 2cm superioinferiorly and 1cm anterioposteriorly. FBCT and 4DCT images were acquired. A PTV-4D was created on the 4DCT by applying a uniform margin of 5mm to the ITV-CT. PTV-FB was created by applying a margin of the motion range plus 5mm, i.e. total of 1.5cm laterally and 2.5cm superioinferiorly to the GTV outlined on the FBCT. A dynamic conformal arc was planned to treat the PTV-FB with 1mm margin. A CBCT was acquired before the treatment, on which the target was delineated. During the treatment, the position of the target was monitored using the EPID in cine mode. Results ITV-CBCT and ITV-CT were measured to be 56.6 and 62.7cc, respectively, with a Dice Coefficient (DC) of 0.94 and disagreement in center of mass (COM) of 0.59 mm. On the other hand, GTV-FB was 11.47cc, 19% less than the known volume of the ball. PTV-FB and PTV-4D were 149 and 116 cc, with a DC of 0.71. Part of the ITV-CT was not enclosed by the PTV-FB despite the large margin. The cine EPID images have confirmed geometrical misses of the target. Similar under-coverage was observed in one clinical case and captured by the CBCT, where the implanted fiducials moved outside PTV-FB. Conclusion ITV-CBCT is in good agreement with ITV-CT. When 4DCT was not available, CBCT can be an effective alternative in determining and verifying the PTV margin.

Comparison of the EUCAST and CLSI Broth Microdilution Methods for Testing Isavuconazole, Posaconazole, and Amphotericin B against Molecularly Identified Mucorales Species.

Science.gov (United States)

Chowdhary, Anuradha; Singh, Pradeep Kumar; Kathuria, Shallu; Hagen, Ferry; Meis, Jacques F

2015-12-01

We compared EUCAST and CLSI antifungal susceptibility testing (AFST) methods for triazoles and amphotericin B against 124 clinical Mucorales isolates. The EUCAST method yielded MIC values 1- to 3-fold dilutions higher than those of the CLSI method for amphotericin B. The essential agreements between the two methods for triazoles were high, i.e., 99.1% (voriconazole), 98.3% (isavuconazole), and 87% (posaconazole), whereas it was significantly lower for amphotericin B (66.1%). Strategies for harmonization of the two methods for Mucorales AFST are warranted. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Generation of low KV x-ray portal images with mega-voltage electron beams

International Nuclear Information System (INIS)

Kenny, J.; Ebert, M.

2004-01-01

Full text: The increasing complexity of radiation therapy plans and reduced target margins, have made accurate localization of patients at treatment a crucial quality assurance issue. Mega-voltage portal images, the standard for treatment localization, are inherently low in contrast because x-ray attenuation at these energies is similar for most body tissues. Thus anatomical features are difficult to distinguish and match to features on a reference diagnostic image. This project investigates the possibly of using x-rays created by an external target placed in the path of a clinical mega-voltage electron beam. This target is optimised to produce a higher proportion of useful imaging x-rays in the range of 50-200kV. It is thought that a high efficiency Varian aSi500 amorphous silicon EPID will be sufficient to compensate for the very low efficiency of x-ray production. The project was undertaken with concurrent theoretical and experimental components. The former involved Monte Carlo models of low Z target design while in the later, experimental data was gathered to validate the model and explore the practical issues associated with electron mode image acquisition. A 6 MeV electron beam model for a Varian Clinac 21EX was developed with EGS4/BEAMnrc User Code and compared to measured beam data. Phase space data scored at the secondary collimator then became the input for simulations of a target placed in the accessory tray. Target materials were predominately low atomic number (Z) because a) production of high energy x-rays is minimized and, b) fewer low energy x-rays produced will be absorbed within the target. Photon and electron energy spectrums of the modified beam were evaluated for a range of target geometries. Ultimately, several materials were used in combination to optimise an x-ray yield for energies <200kV while removing electrons and very low energy x-rays, that contribute to patient dose but not to image formation. Low energy images of a PIPs EPID QA

bNEAT: a Bayesian network method for detecting epistatic interactions in genome-wide association studies

Directory of Open Access Journals (Sweden)

Chen Xue-wen

2011-07-01

Full Text Available Abstract Background Detecting epistatic interactions plays a significant role in improving pathogenesis, prevention, diagnosis and treatment of complex human diseases. A recent study in automatic detection of epistatic interactions shows that Markov Blanket-based methods are capable of finding genetic variants strongly associated with common diseases and reducing false positives when the number of instances is large. Unfortunately, a typical dataset from genome-wide association studies consists of very limited number of examples, where current methods including Markov Blanket-based method may perform poorly. Results To address small sample problems, we propose a Bayesian network-based approach (bNEAT to detect epistatic interactions. The proposed method also employs a Branch-and-Bound technique for learning. We apply the proposed method to simulated datasets based on four disease models and a real dataset. Experimental results show that our method outperforms Markov Blanket-based methods and other commonly-used methods, especially when the number of samples is small. Conclusions Our results show bNEAT can obtain a strong power regardless of the number of samples and is especially suitable for detecting epistatic interactions with slight or no marginal effects. The merits of the proposed approach lie in two aspects: a suitable score for Bayesian network structure learning that can reflect higher-order epistatic interactions and a heuristic Bayesian network structure learning method.

Method of preparing an Al-Ti-B grain refiner for aluminium-comprising products, and a method of casting aluminium products

NARCIS (Netherlands)

Brinkman, H.J.; Duszczyk, J.; Katgerman, L.

1999-01-01

The invention relates to a method of preparing an Al-Ti-B grain refiner for cast aluminium-comprising products. According to the invention the preparation is realized by mixing powders selected from the group comprising aluminium, titanium, boron, and alloys and intermetallic compounds thereof,

Protocol for the quality control systems of electronic portal imaging used in verification of radiotherapy treatment

International Nuclear Information System (INIS)

Silvestre, Ileana; Alfonso, Rodolfo; Garcia, Fernando

2009-01-01

Following the approach of quality control of radiotherapy equipment, conceived in the IAEA TECDOC-1151, we analyzed the different tests must be to an EPID to guarantee levels of accuracy required in the administration of radiation treatments, including the study of the impact of different parameters, geometric and dosimetric imaging, involved in the process. Established the types and frequency of checks, as well as procedures for their implementation, the allowable tolerances set of values records and forms for recording . Was carried out assessment protocol in various services based on amorphous silicon EPID for its applicability and scope. Was designed and validated in clinical practice protocol for EPID quality control, demonstrating its applicability with a minimum of material and human resources. It We concluded that with proper and systematic quality control program, tests including dosimetry, the EPID can provide valuable information about physico-beam dosimetry, and ensure adequate accuracy geometric in the patient's location. (author)

An HPLC method to determine sennoside A and sennoside B in Sennae fructus and Sennae folium.

Science.gov (United States)

Rosenthal, Immanuel; Wolfram, Evelyn; Meier, Beat

2014-01-01

The current Ph. Eur. monographs for senna pods, senna leaf and senna leaf dry extract standardised describe a photometric assay based on the Bornträger reaction to determine hydroxyanthracene glycosides, calculated as sennoside B. The method is timeconsuming, unspecific for sennosides and the precision is not adequate for a modern assay. The photometric method shall therefore be replaced by a modern HPLC method. About 70 % of the total anthrachinone content in herbal drugs of senna species is due to sennoside A and sennoside B. These substances are therefore suitable for the standardisation of Senna products. The Japanese Pharmacopoeia (JP) already describes an HPLC method to determine sennoside A and sennoside B in the monograph for senna leaf. It uses ion-pair chromatography with tetraheptylammoniumbromide. The procedure described in the monograph has a runtime of 70 min. The adapted and validated method described here uses solid-phase extraction (SPE) which allows a selective sample preparation by using an anion exchange phase. A conventional RP C18 column Tosh TSKgel ODS-80TS (4.6 mm × 150 mm), 5 μm, was used as stationary phase and acetonitrile for chromatography R, water R, phosphoric acid R (200:800:1 V/V/V) as mobile phase. The flow rate was 1.2 mL/min, the column temperature 40 °C, the detection wavelength 380 nm, and the injection volume 20 μL. The runtime is 10 min, the chromatogram shows 2 peaks due to sennoside A/B and 2 additional smaller compounds. One of them is rhein-8-O-glucoside. The procedure has been successfully validated according to ICH guidelines. We analysed 6 batches of Senna. The pods (Senna angustifolia) showed a total content of sennoside A and B of 1.74-2.76 % m/m and the content of senna leaves was clearly lower with 1.07-1.19 % m/m, respectively. The suggested method is considered to be suitable to determine sennoside A and sennoside B in senna leaves and senna pods. The consideration is based on the performed validation and on

Image-guided radiotherapy in near real time with intensity-modulated radiotherapy megavoltage treatment beam imaging.

Science.gov (United States)

Mao, Weihua; Hsu, Annie; Riaz, Nadeem; Lee, Louis; Wiersma, Rodney; Luxton, Gary; King, Christopher; Xing, Lei; Solberg, Timothy

2009-10-01

To utilize image-guided radiotherapy (IGRT) in near real time by obtaining and evaluating the online positions of implanted fiducials from continuous electronic portal imaging device (EPID) imaging of prostate intensity-modulated radiotherapy (IMRT) delivery. Upon initial setup using two orthogonal images, the three-dimensional (3D) positions of all implanted fiducial markers are obtained, and their expected two-dimensional (2D) locations in the beam's-eye-view (BEV) projection are calculated for each treatment field. During IMRT beam delivery, EPID images of the megavoltage treatment beam are acquired in cine mode and subsequently analyzed to locate 2D locations of fiducials in the BEV. Simultaneously, 3D positions are estimated according to the current EPID image, information from the setup portal images, and images acquired at other gantry angles (the completed treatment fields). The measured 2D and 3D positions of each fiducial are compared with their expected 2D and 3D setup positions, respectively. Any displacements larger than a predefined tolerance may cause the treatment system to suspend the beam delivery and direct the therapists to reposition the patient. Phantom studies indicate that the accuracy of 2D BEV and 3D tracking are better than 1 mm and 1.4 mm, respectively. A total of 7330 images from prostate treatments were acquired and analyzed, showing a maximum 2D displacement of 6.7 mm and a maximum 3D displacement of 6.9 mm over 34 fractions. This EPID-based, real-time IGRT method can be implemented on any external beam machine with portal imaging capabilities without purchasing any additional equipment, and there is no extra dose delivered to the patient.

An image correlation procedure for digitally reconstructed radiographs and electronic portal images

International Nuclear Information System (INIS)

Dong, Lei; Boyer, Arthur L.

1995-01-01

Purpose: To study a procedure that uses megavoltage digitally reconstructed radiographs (DRRs) calculated from patient's three-dimensional (3D) computed tomography (CT) data as a reference image for correlation with on-line electronic portal images (EPIs) to detect patient setup errors. Methods and Materials: Megavoltage DRRs were generated by ray tracing through a modified volumetric CT data set in which CT numbers were converted into linear attenuation coefficients for the therapeutic beam energy. The DRR transmission image was transformed to the grayscale window of the EPI by a histogram-matching technique. An alternative approach was to calibrate the transmission DRR using a measured response curve of the electronic portal imaging device (EPID). This forces the calculated transmission fluence values to be distributed in the same range as that of the EPID image. A cross-correlation technique was used to determine the degree of alignment of the patient anatomy found in the EPID image relative to the reference DRR. Results: Phantom studies demonstrated that the correlation procedure had a standard deviation of 0.5 mm and 0.5 deg. in aligning translational shifts and in-plane rotations. Systematic errors were found between a reference DRR and a reference EPID image. The automated grayscale image-correlation process was completed within 3 s on a workstation computer or 12 s on a PC. Conclusion: The alignment procedure allows the direct comparison of a patient's treatment portal designed with a 3D planning computer with a patient's on-line portal image acquired at the treatment unit. The image registration process is automated to the extent that it requires minimal user intervention, and it is fast and accurate enough for on-line clinical applications

Production of branched tetraether lipids in the lower Pearl River and estuary: effects of extraction methods and impact on bGDGT proxies

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Chuanlun eZhang

2012-01-01

Full Text Available Branched glycerol dibiphytanyl glycerol tetraethers (bGDGTs are known as bacterial lipids that occur widely in terrestrial environments, particularly in anaerobic peat bogs and soil. We examined the abundance and distribution of bGDGTs in both core (C and polar (P lipid fractions from the water column and surface sediments in the lower Pearl River (PR and its estuary using two extraction methods (sonication vs. Bligh and Dyer. A number of soil samples in the lower PR drainage basin were also collected and extracted for bGDGTs using the sonication method. The results showed aquatic production of bGDGTs as supported by substantial abundances of P-bGDGTs in the water column and sediment samples. The bGDGT-based proxies (BIT, CBT, and MBT were not affected by the method of extraction when C-bGDGTs were analyzed; in such case, the pHCBT of the sediments reflected the soil pH of the lower PR drainage basin, and the temperature close to the annual mean air temperature in the lower PR basin. On the other hand, the P-bGDGT-derived proxies were inconsistent between the two methods. The P-bGDGTs (particularly those extracted using the sonication method may not be reliable indicators of annual mean air temperatures.

Flux pinning properties of impurity doped MgB2 bulks synthesized by diffusion method

International Nuclear Information System (INIS)

Ueda, Shinya; Shimoyama, Jun-ichi; Yamamoto, Akiyasu; Katsura, Yukari; Iwayama, Isao; Horii, Shigeru; Kishio, Kohji

2005-01-01

Doping effects of carbon-containing impurities on the critical current properties and microstructure were systematically studied for highly dense MgB 2 bulks prepared by the diffusion method starting from magnesium and boron which are separately packed in sealed stainless tubes. Obtained samples exhibited improved critical current density, J c , simply by an increase of effective current pass. A non-doped MgB 2 recorded almost double high J c at 20 K compared with those of the conventional porous MgB 2 bulks having ∼50% of the theoretical density, while irreversibility field, H irr , did not largely change. J c under high magnetic fields were enhanced by doping of carbon-containing impurities, such as SiC and B 4 C. Optimal doping levels of SiC and B 4 C for high critical current properties at 20 K are found to be ∼2% and 5%, respectively, as nominal carbon concentration at boron site. Difference in the optimal doping levels is originated from the difference in their reactivity

Clinical Experience and Evaluation of Patient Treatment Verification With a Transit Dosimeter

Energy Technology Data Exchange (ETDEWEB)

Ricketts, Kate, E-mail: k.ricketts@ucl.ac.uk [Division of Surgery and Interventional Sciences, University College London, London (United Kingdom); Department of Radiotherapy Physics, Royal Berkshire NHS Foundation Trust, Reading (United Kingdom); Navarro, Clara; Lane, Katherine; Blowfield, Claire; Cotten, Gary; Tomala, Dee; Lord, Christine; Jones, Joanne; Adeyemi, Abiodun [Department of Radiotherapy Physics, Royal Berkshire NHS Foundation Trust, Reading (United Kingdom)

2016-08-01

Purpose: To prospectively evaluate a protocol for transit dosimetry on a patient population undergoing intensity modulated radiation therapy (IMRT) and to assess the issues in clinical implementation of electronic portal imaging devices (EPIDs) for treatment verification. Methods and Materials: Fifty-eight patients were enrolled in the study. Amorphous silicon EPIDs were calibrated for dose and used to acquire images of delivered fields. Measured EPID dose maps were back-projected using the planning computed tomographic (CT) images to calculate dose at prespecified points within the patient and compared with treatment planning system dose offline using point dose difference and point γ analysis. The deviation of the results was used to inform future action levels. Results: Two hundred twenty-five transit images were analyzed, composed of breast, prostate, and head and neck IMRT fields. Patient measurements demonstrated the potential of the dose verification protocol to model dose well under complex conditions: 83.8% of all delivered beams achieved the initial set tolerance level of Δ{sub D} of 0 ± 5 cGy or %Δ{sub D} of 0% ± 5%. Importantly, the protocol was also sensitive to anatomic changes and spotted that 3 patients from 20 measured prostate patients had undergone anatomic change in comparison with the planning CT. Patient data suggested an EPID-reconstructed versus treatment planning system dose difference action level of 0% ± 7% for breast fields. Asymmetric action levels were more appropriate for inversed IMRT fields, using absolute dose difference (−2 ± 5 cGy) or summed field percentage dose difference (−6% ± 7%). Conclusions: The in vivo dose verification method was easy to use and simple to implement, and it could detect patient anatomic changes that impacted dose delivery. The system required no extra dose to the patient or treatment time delay and so could be used throughout the course of treatment to identify and limit

Validation of a screening method for the simultaneous identification of fat-soluble and water-soluble vitamins (A, E, B1, B2 and B6) in an aqueous micellar medium of hexadecyltrimethylammonium chloride.

Science.gov (United States)

León-Ruiz, V; Vera, S; San Andrés, M P

2005-04-01

Simultaneous determination of the fat-soluble vitamins A and E and the water-soluble vitamins B1, B2 and B6 has been carried using a screening method from fluorescence contour graphs. These graphs show different colour zones in relation to the fluorescence intensity measured for the pair of excitation/emission wavelengths. The identification of the corresponding excitation/emission wavelength zones allows the detection of different vitamins in an aqueous medium regardless of the fat or water solubility of each vitamin, owing to the presence of a surfactant which forms micelles in water at the used concentration (over the critical micelle concentration). The micelles dissolve very water insoluble compounds, such as fat-soluble vitamins, inside the aggregates. This approach avoids the use of organic solvents in determining these vitamins and offers the possibility of analysing fat- and water-soluble vitamins simultaneously. The method has been validated in terms of detection limit, cut-off limit, sensitivity, number of false positives, number of false negatives and uncertainty range. The detection limit is about microg L(-1). The screening method was applied to different samples such as pharmaceuticals, juices and isotonic drinks.

Vibration Analysis of Rectangular Plates with One or More Guided Edges via Bicubic B-Spline Method

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W.J. Si

2005-01-01

Full Text Available A simple and accurate method is proposed for the vibration analysis of rectangular plates with one or more guided edges, in which bicubic B-spline interpolation in combination with a new type of basis cubic B-spline functions is used to approximate the plate deflection. This type of basis cubic B-spline functions can satisfy simply supported, clamped, free, and guided edge conditions with easy numerical manipulation. The frequency characteristic equation is formulated based on classical thin plate theory by performing Hamilton's principle. The present solutions are verified with the analytical ones. Fast convergence, high accuracy and computational efficiency have been demonstrated from the comparisons. Frequency parameters for 13 cases of rectangular plates with at least one guided edge, which are possible by approximate or numerical methods only, are presented. These results are new in literature.

Quantification of immobilized Candida antarctica lipase B (CALB) using ICP-AES combined with Bradford method.

Science.gov (United States)

Nicolás, Paula; Lassalle, Verónica L; Ferreira, María L

2017-02-01

The aim of this manuscript was to study the application of a new method of protein quantification in Candida antarctica lipase B commercial solutions. Error sources associated to the traditional Bradford technique were demonstrated. Eight biocatalysts based on C. antarctica lipase B (CALB) immobilized onto magnetite nanoparticles were used. Magnetite nanoparticles were coated with chitosan (CHIT) and modified with glutaraldehyde (GLUT) and aminopropyltriethoxysilane (APTS). Later, CALB was adsorbed on the modified support. The proposed novel protein quantification method included the determination of sulfur (from protein in CALB solution) by means of Atomic Emission by Inductive Coupling Plasma (AE-ICP). Four different protocols were applied combining AE-ICP and classical Bradford assays, besides Carbon, Hydrogen and Nitrogen (CHN) analysis. The calculated error in protein content using the "classic" Bradford method with bovine serum albumin as standard ranged from 400 to 1200% when protein in CALB solution was quantified. These errors were calculated considering as "true protein content values" the results of the amount of immobilized protein obtained with the improved method. The optimum quantification procedure involved the combination of Bradford method, ICP and CHN analysis. Copyright © 2016 Elsevier Inc. All rights reserved.

40 CFR Appendix B to Part 136 - Definition and Procedure for the Determination of the Method Detection Limit-Revision 1.11

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2010-07-01

... calculated method detection limit. To insure that the estimate of the method detection limit is a good...) where: MDL = the method detection limit t(n-1,1- α=.99) = the students' t value appropriate for a 99... Determination of the Method Detection Limit-Revision 1.11 B Appendix B to Part 136 Protection of Environment...

Hybrid Multistarting GA-Tabu Search Method for the Placement of BtB Converters for Korean Metropolitan Ring Grid

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Remund J. Labios

2016-01-01

Full Text Available This paper presents a method to determine the optimal locations for installing back-to-back (BtB converters in a power grid as a countermeasure to reduce fault current levels. The installation of BtB converters can be regarded as network reconfiguration. For the purpose, a hybrid multistarting GA-tabu search method was used to determine the best locations from a preselected list of candidate locations. The constraints used in determining the best locations include circuit breaker fault current limits, proximity of proposed locations, and capability of the solution to reach power flow convergence. A simple power injection model after applying line-opening on selected branches was used as a means for power flows with BtB converters. Kron reduction was also applied as a method for network reduction for fast evaluation of fault currents with a given topology. Simulations of the search method were performed on the Korean power system, particularly the Seoul metropolitan area.

Determination of S_1_7 from systematic analyses on "8B Coulomb breakup with the Eikonal-CDCC method

International Nuclear Information System (INIS)

Ogata, K.; Matsumoto, T.; Yamashita, N.; Kamimura, M.; Yahiro, M.; Iseri, Y.

2003-01-01

Systematic analysis of "8B Coulomb dissociation with the Asymptotic Normalization Coefficient (ANC) method is proposed to determine the astrophysical factor S_1_7(0) accurately. An important advantage of the analysis is that uncertainties of the extracted S_1_7(0) coming from the use of the ANC method can quantitatively be evaluated, in contrast to previous analyses using the Virtual Photon Theory (VPT). Calculation of measured spectra in dissociation experiments is done by means of the method of Continuum-Discretized Coupled-Channels (CDCC). From the analysis of "5"8Ni("8B,"7Be+p) "5"8Ni at 25.8 MeV, S_1_7(0) = 22.83 ± 0.51(theo) ± 2.28(expt) (eVb) is obtained; the ANC method turned out to work in this case within 1% of error. Preceding systematic analysis of experimental data at intermediate energies, we propose hybrid (HY) Coupled-Channels (CC) calculation of "8B Coulomb dissociation, which makes numerical calculation much simple, retaining its accuracy. The validity of the HY calculation is tested for "5"8Ni("8B,"7Be+p) "5"8Ni at 240 MeV. The ANC method combined with the HY CC calculation is shown to be a powerful technique to obtain a reliable S_1_7(0).