An in vivo dose verification method for SBRT–VMAT delivery using the EPID

Energy Technology Data Exchange (ETDEWEB)

McCowan, P. M., E-mail: peter.mccowan@cancercare.mb.ca [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); Van Uytven, E.; Van Beek, T.; Asuni, G. [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)

2015-12-15

Purpose: Radiation treatments have become increasingly more complex with the development of volumetric modulated arc therapy (VMAT) and the use of stereotactic body radiation therapy (SBRT). SBRT involves the delivery of substantially larger doses over fewer fractions than conventional therapy. SBRT–VMAT treatments will strongly benefit from in vivo patient dose verification, as any errors in delivery can be more detrimental to the radiobiology of the patient as compared to conventional therapy. Electronic portal imaging devices (EPIDs) are available on most commercial linear accelerators (Linacs) and their documented use for dosimetry makes them valuable tools for patient dose verification. In this work, the authors customize and validate a physics-based model which utilizes on-treatment EPID images to reconstruct the 3D dose delivered to the patient during SBRT–VMAT delivery. Methods: The SBRT Linac head, including jaws, multileaf collimators, and flattening filter, were modeled using Monte Carlo methods and verified with measured data. The simulation provides energy spectrum data that are used by their “forward” model to then accurately predict fluence generated by a SBRT beam at a plane above the patient. This fluence is then transported through the patient and then the dose to the phosphor layer in the EPID is calculated. Their “inverse” model back-projects the EPID measured focal fluence to a plane upstream of the patient and recombines it with the extra-focal fluence predicted by the forward model. This estimate of total delivered fluence is then forward projected onto the patient’s density matrix and a collapsed cone convolution algorithm calculates the dose delivered to the patient. The model was tested by reconstructing the dose for two prostate, three lung, and two spine SBRT–VMAT treatment fractions delivered to an anthropomorphic phantom. It was further validated against actual patient data for a lung and spine SBRT–VMAT plan. The

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.

Dose-response characteristics of an amorphous silicon EPID

International Nuclear Information System (INIS)

Winkler, Peter; Hefner, Alfred; Georg, Dietmar

2005-01-01

Electronic portal imaging devices (EPIDs) were originally developed for the purpose of patient setup verification. Nowadays, they are increasingly used as dosimeters (e.g., for IMRT verification and linac-specific QA). A prerequisite for any clinical dosimetric application is a detailed understanding of the detector's dose-response behavior. The aim of this study is to investigate the dosimetric properties of an amorphous silicon EPID (Elekta IVIEWGT) with respect to three photon beam qualities: 6, 10, and 25 MV. The EPID showed an excellent temporal stability on short term as well as on long term scales. The stability throughout the day was strongly influenced by warming up, which took several hours and affected EPID response by 2.5%. Ghosting effects increased the sensitivity of the EPID. They became more pronounced with decreasing time intervals between two exposures as well as with increasing dose. Due to ghosting, changes in pixel sensitivity amounted up to 16% (locally) for the 25 MV photon beam. It was observed that the response characteristics of our EPID depended on dose as well as on dose rate. Doubling the dose rate increased the EPID sensitivity by 1.5%. This behavior was successfully attributed to a dose per frame effect, i.e., a nonlinear relationship between the EPID signal and the dose which was delivered to the panel between two successive readouts. The sensitivity was found to vary up to 10% in the range of 1 to 1000 monitor units. This variation was governed by two independent effects. For low doses, the EPID signal was reduced due to the linac's changing dose rate during startup. Furthermore, the detector reading was influenced by intrabeam variations of EPID sensitivity, namely, an increase of detector response during uniform exposure. For the beam qualities which were used, the response characteristics of the EPID did not depend on energy. Differences in relative dose-response curves resulted from energy dependent temporal output

Time dependent pre-treatment EPID dosimetry for standard and FFF VMAT.

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Podesta, Mark; Nijsten, Sebastiaan M J J G; Persoon, Lucas C G G; Scheib, Stefan G; Baltes, Christof; Verhaegen, Frank

2014-08-21

Methods to calibrate Megavoltage electronic portal imaging devices (EPIDs) for dosimetry have been previously documented for dynamic treatments such as intensity modulated radiotherapy (IMRT) using flattened beams and typically using integrated fields. While these methods verify the accumulated field shape and dose, the dose rate and differential fields remain unverified. The aim of this work is to provide an accurate calibration model for time dependent pre-treatment dose verification using amorphous silicon (a-Si) EPIDs in volumetric modulated arc therapy (VMAT) for both flattened and flattening filter free (FFF) beams. A general calibration model was created using a Varian TrueBeam accelerator, equipped with an aS1000 EPID, for each photon spectrum 6 MV, 10 MV, 6 MV-FFF, 10 MV-FFF. As planned VMAT treatments use control points (CPs) for optimization, measured images are separated into corresponding time intervals for direct comparison with predictions. The accuracy of the calibration model was determined for a range of treatment conditions. Measured and predicted CP dose images were compared using a time dependent gamma evaluation using criteria (3%, 3 mm, 0.5 sec). Time dependent pre-treatment dose verification is possible without an additional measurement device or phantom, using the on-board EPID. Sufficient data is present in trajectory log files and EPID frame headers to reliably synchronize and resample portal images. For the VMAT plans tested, significantly more deviation is observed when analysed in a time dependent manner for FFF and non-FFF plans than when analysed using only the integrated field. We show EPID-based pre-treatment dose verification can be performed on a CP basis for VMAT plans. This model can measure pre-treatment doses for both flattened and unflattened beams in a time dependent manner which highlights deviations that are missed in integrated field verifications.

Development of a daily dosimetric control for radiation therapy using an electronic portal imaging device (EPID)

International Nuclear Information System (INIS)

Saboori, Mohammadsaeed

2015-01-01

Electronic Portal Imaging Devices (EPIDs) can be used to perform dose measurements during radiation therapy treatments if dedicated calibration and correction procedures are applied. The purpose of this study was to provide a new calibration and correction model for an amorphous silicon (a-Si) EPID for use in transit dose verification of step-and-shoot intensity modulated radiation therapy (IMRT). A model was created in a commercial treatment planning system to calculate the nominal two-dimensional (2D) dose map of each radiation field at the EPID level. The EPID system was calibrated and correction factors were determined using a reference set-up, which consisted a patient phantom and an EPID phantom. The advantage of this method is that for the calibration, the actual beam spectrum is used to mimic a patient measurement. As proof-of-principle, the method was tested for the verification of two 7-field IMRT treatment plans with tumor sites in the head-and-neck and pelvic region. Predicted and measured EPID responses were successfully compared to the nominal data from treatment planning using dose difference maps and gamma analyses. Based on our result it can be concluded that this new method of 2D EPID dosimetry is a potential tool for simple patient treatment fraction dose verification.

An EPID-based method for comprehensive verification of gantry, EPID and the MLC carriage positional accuracy in Varian linacs during arc treatments

International Nuclear Information System (INIS)

Rowshanfarzad, Pejman; McGarry, Conor K; Barnes, Michael P; Sabet, Mahsheed; Ebert, Martin A

2014-01-01

In modern radiotherapy, it is crucial to monitor the performance of all linac components including gantry, collimation system and electronic portal imaging device (EPID) during arc deliveries. In this study, a simple EPID-based measurement method has been introduced in conjunction with an algorithm to investigate the stability of these systems during arc treatments with the aim of ensuring the accuracy of linac mechanical performance. The Varian EPID sag, gantry sag, changes in source-to-detector distance (SDD), EPID and collimator skewness, EPID tilt, and the sag in MLC carriages as a result of linac rotation were separately investigated by acquisition of EPID images of a simple phantom comprised of 5 ball-bearings during arc delivery. A fast and robust software package was developed for automated analysis of image data. Twelve Varian linacs of different models were investigated. The average EPID sag was within 1 mm for all tested linacs. All machines showed less than 1 mm gantry sag. Changes in SDD values were within 1.7 mm except for three linacs of one centre which were within 9 mm. Values of EPID skewness and tilt were negligible in all tested linacs. The maximum sag in MLC leaf bank assemblies was around 1 mm. The EPID sag showed a considerable improvement in TrueBeam linacs. The methodology and software developed in this study provide a simple tool for effective investigation of the behaviour of linac components with gantry rotation. It is reproducible and accurate and can be easily performed as a routine test in clinics

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

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

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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.

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.

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.

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

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

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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

Numident Online Verification Utility (NOVU)

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Social Security Administration — NOVU is a mainframe application that accesses the NUMIDENT to perform real-time SSN verifications. This program is called by other SSA online programs that serve as...

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

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

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)

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).

Dosimetry in radiotherapy using a-Si EPIDs: Systems, methods, and applications focusing on 3D patient dose estimation

Science.gov (United States)

McCurdy, B. M. C.

2013-06-01

An overview is provided of the use of amorphous silicon electronic portal imaging devices (EPIDs) for dosimetric purposes in radiation therapy, focusing on 3D patient dose estimation. EPIDs were originally developed to provide on-treatment radiological imaging to assist with patient setup, but there has also been a natural interest in using them as dosimeters since they use the megavoltage therapy beam to form images. The current generation of clinically available EPID technology, amorphous-silicon (a-Si) flat panel imagers, possess many characteristics that make them much better suited to dosimetric applications than earlier EPID technologies. Features such as linearity with dose/dose rate, high spatial resolution, realtime capability, minimal optical glare, and digital operation combine with the convenience of a compact, retractable detector system directly mounted on the linear accelerator to provide a system that is well-suited to dosimetric applications. This review will discuss clinically available a-Si EPID systems, highlighting dosimetric characteristics and remaining limitations. Methods for using EPIDs in dosimetry applications will be discussed. Dosimetric applications using a-Si EPIDs to estimate three-dimensional dose in the patient during treatment will be overviewed. Clinics throughout the world are implementing increasingly complex treatments such as dynamic intensity modulated radiation therapy and volumetric modulated arc therapy, as well as specialized treatment techniques using large doses per fraction and short treatment courses (ie. hypofractionation and stereotactic radiosurgery). These factors drive the continued strong interest in using EPIDs as dosimeters for patient treatment verification.

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.

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)

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

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

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

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

Impact of the frequency of online verifications on the patient set-up accuracy and set-up margins

International Nuclear Information System (INIS)

Rudat, Volker; Hammoud, Mohamed; Pillay, Yogin; Alaradi, Abdul Aziz; Mohamed, Adel; Altuwaijri, Saleh

2011-01-01

The purpose of the study was to evaluate the patient set-up error of different anatomical sites, to estimate the effect of different frequencies of online verifications on the patient set-up accuracy, and to calculate margins to accommodate for the patient set-up error (ICRU set-up margin, SM). Alignment data of 148 patients treated with inversed planned intensity modulated radiotherapy (IMRT) or three-dimensional conformal radiotherapy (3D-CRT) of the head and neck (n = 31), chest (n = 72), abdomen (n = 15), and pelvis (n = 30) were evaluated. The patient set-up accuracy was assessed using orthogonal megavoltage electronic portal images of 2328 fractions of 173 planning target volumes (PTV). In 25 patients, two PTVs were analyzed where the PTVs were located in different anatomical sites and treated in two different radiotherapy courses. The patient set-up error and the corresponding SM were retrospectively determined assuming no online verification, online verification once a week and online verification every other day. The SM could be effectively reduced with increasing frequency of online verifications. However, a significant frequency of relevant set-up errors remained even after online verification every other day. For example, residual set-up errors larger than 5 mm were observed on average in 18% to 27% of all fractions of patients treated in the chest, abdomen and pelvis, and in 10% of fractions of patients treated in the head and neck after online verification every other day. In patients where high set-up accuracy is desired, daily online verification is highly recommended

Detection and correction for EPID and gantry sag during arc delivery using cine EPID imaging.

Science.gov (United States)

Rowshanfarzad, Pejman; Sabet, Mahsheed; O'Connor, Daryl J; McCowan, Peter M; McCurdy, Boyd M C; Greer, Peter B

2012-02-01

Electronic portal imaging devices (EPIDs) have been studied and used for pretreatment and in-vivo dosimetry applications for many years. The application of EPIDs for dosimetry in arc treatments requires accurate characterization of the mechanical sag of the EPID and gantry during rotation. Several studies have investigated the effects of gravity on the sag of these systems but each have limitations. In this study, an easy experiment setup and accurate algorithm have been introduced to characterize and correct for the effect of EPID and gantry sag during arc delivery. Three metallic ball bearings were used as markers in the beam: two of them fixed to the gantry head and the third positioned at the isocenter. EPID images were acquired during a 360° gantry rotation in cine imaging mode. The markers were tracked in EPID images and a robust in-house developed MATLAB code was used to analyse the images and find the EPID sag in three directions as well as the EPID + gantry sag by comparison to the reference gantry zero image. The algorithm results were then tested against independent methods. The method was applied to compare the effect in clockwise and counter clockwise gantry rotations and different source-to-detector distances (SDDs). The results were monitored for one linear accelerator over a course of 15 months and six other linear-accelerators from two treatment centers were also investigated using this method. The generalized shift patterns were derived from the data and used in an image registration algorithm to correct for the effect of the mechanical sag in the system. The Gamma evaluation (3%, 3 mm) technique was used to investigate the improvement in alignment of cine EPID images of a fixed field, by comparing both individual images and the sum of images in a series with the reference gantry zero image. The mechanical sag during gantry rotation was dependent on the gantry angle and was larger in the in-plane direction, although the patterns were not

Impact of the frequency of online verifications on the patient set-up accuracy and set-up margins

Directory of Open Access Journals (Sweden)

Mohamed Adel

2011-08-01

Full Text Available Abstract Purpose The purpose of the study was to evaluate the patient set-up error of different anatomical sites, to estimate the effect of different frequencies of online verifications on the patient set-up accuracy, and to calculate margins to accommodate for the patient set-up error (ICRU set-up margin, SM. Methods and materials Alignment data of 148 patients treated with inversed planned intensity modulated radiotherapy (IMRT or three-dimensional conformal radiotherapy (3D-CRT of the head and neck (n = 31, chest (n = 72, abdomen (n = 15, and pelvis (n = 30 were evaluated. The patient set-up accuracy was assessed using orthogonal megavoltage electronic portal images of 2328 fractions of 173 planning target volumes (PTV. In 25 patients, two PTVs were analyzed where the PTVs were located in different anatomical sites and treated in two different radiotherapy courses. The patient set-up error and the corresponding SM were retrospectively determined assuming no online verification, online verification once a week and online verification every other day. Results The SM could be effectively reduced with increasing frequency of online verifications. However, a significant frequency of relevant set-up errors remained even after online verification every other day. For example, residual set-up errors larger than 5 mm were observed on average in 18% to 27% of all fractions of patients treated in the chest, abdomen and pelvis, and in 10% of fractions of patients treated in the head and neck after online verification every other day. Conclusion In patients where high set-up accuracy is desired, daily online verification is highly recommended.

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)

Online fingerprint verification.

Science.gov (United States)

Upendra, K; Singh, S; Kumar, V; Verma, H K

2007-01-01

As organizations search for more secure authentication methods for user access, e-commerce, and other security applications, biometrics is gaining increasing attention. With an increasing emphasis on the emerging automatic personal identification applications, fingerprint based identification is becoming more popular. The most widely used fingerprint representation is the minutiae based representation. The main drawback with this representation is that it does not utilize a significant component of the rich discriminatory information available in the fingerprints. Local ridge structures cannot be completely characterized by minutiae. Also, it is difficult quickly to match two fingerprint images containing different number of unregistered minutiae points. In this study filter bank based representation, which eliminates these weakness, is implemented and the overall performance of the developed system is tested. The results have shown that this system can be used effectively for secure online verification applications.

Incorrect, fake, and false: Journalists' perceived online source credibility and verification behavior

NARCIS (Netherlands)

Vergeer, M.R.M.

2018-01-01

This study focuses on the extent journalists verify information provided by online sources, and tests to what extent this verification behavior can be explained by journalists' perceived credibility of online information and other factors, such as journalism education of journalists, work and

A method for online verification of adapted fields using an independent dose monitor

International Nuclear Information System (INIS)

Chang Jina; Norrlinger, Bernhard D.; Heaton, Robert K.; Jaffray, David A.; Cho, Young-Bin; Islam, Mohammad K.; Mahon, Robert

2013-01-01

Purpose: Clinical implementation of online adaptive radiotherapy requires generation of modified fields and a method of dosimetric verification in a short time. We present a method of treatment field modification to account for patient setup error, and an online method of verification using an independent monitoring system.Methods: The fields are modified by translating each multileaf collimator (MLC) defined aperture in the direction of the patient setup error, and magnifying to account for distance variation to the marked isocentre. A modified version of a previously reported online beam monitoring system, the integral quality monitoring (IQM) system, was investigated for validation of adapted fields. The system consists of a large area ion-chamber with a spatial gradient in electrode separation to provide a spatially sensitive signal for each beam segment, mounted below the MLC, and a calculation algorithm to predict the signal. IMRT plans of ten prostate patients have been modified in response to six randomly chosen setup errors in three orthogonal directions.Results: A total of approximately 49 beams for the modified fields were verified by the IQM system, of which 97% of measured IQM signal agree with the predicted value to within 2%.Conclusions: The modified IQM system was found to be suitable for online verification of adapted treatment fields

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

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

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.

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

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

SU-F-T-240: EPID-Based Quality Assurance for Dosimetric Credentialing

Energy Technology Data Exchange (ETDEWEB)

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

2016-06-15

Purpose: We propose a novel dosimetric audit method for clinical trials using EPID measurements at each center and a standardized EPID to dose conversion algorithm. The aim of this work is to investigate the applicability of the EPID method to different linear accelerator, EPID and treatment planning system (TPS) combinations. Methods: Combination of delivery and planning systems were three Varian linacs including one Pinnacle and two Eclipse TPS and, two ELEKTA linacs including one Pinnacle and one Monaco TPS. All Varian linacs had the same EPID structure and similarly for the ELEKTA linacs. Initially, dose response of the EPIDs was investigated by acquiring integrated pixel value (IPV) of the central area of 10 cm2 images versus MUs, 5-400 MU. Then, the EPID to dose conversion was investigated for different system combinations. Square field size images, 2, 3, 4, 6, 10, 15, 20, 25 cm2 acquired by all systems were converted to dose at isocenter of a virtual flat phantom then the dose was compared to the corresponding TPS dose. Results: All EPIDs showed a relatively linear behavior versus MU except at low MUs which showed irregularities probably due to initial inaccuracies of irradiation. Furthermore, for all the EPID models, the model predicted TPS dose with a mean dose difference percentage of 1.3. However the model showed a few inaccuracies for ELEKTA EPID images at field sizes larger than 20 cm2. Conclusion: The EPIDs demonstrated similar behavior versus MU and the model was relatively accurate for all the systems. Therefore, the model could be employed as a global dosimetric method to audit clinical trials. Funding has been provided from Department of Radiation Oncology, TROG Cancer Research and the University of Newcastle. Narges Miri is a recipient of a University of Newcastle postgraduate scholarship.

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.

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

, with maximum differences ≤3% for ionization chamber and ≤1.7% for Gafchromic EBT3 dosimetry film, respectively. We have shown that the EPID response is linear with tube current (mA) for the entire range of tube kilovoltage peak. Notably, a close relationship was seen between the detector response vs mA slope, and the kilovoltage peak, allowing an independent verification of kilovoltage peak stability based solely on EPID response. In addition to dosimetry tests, according to the beam-targeting measurement using portal images, maximum displacement of the central axis of the x-ray beam (due to sag) was 0.76 ± 0.09 mm at gantry 135°/couch 0° and 0.89 ± 0.06 mm at gantry 0°/couch -135°. We performed the first comprehensive analysis on the dosimetric properties of an EPID operating at kilovoltage x-ray energies. We characterized the detector performance over a 11-month period. Our results indicate that the imager is a stable and convenient tool for SARRP routine QA tests. We then developed EPID-based tests to perform routine SA-IGRT systems QA tasks, such as verifying constancy of beam quality, energy, output, and profile measurements, relative output factors, and beam targeting. © 2018 American Association of Physicists in Medicine.

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.

Image intelligence online consulting: A flexible and remote access to strategic information applied to verification of declaration

International Nuclear Information System (INIS)

Chassy, A.F. de; Denizot, L.

2001-01-01

Commercial satellite imagery is giving International Institutions specialized Information Departments access to a great source of valuable intelligence. High resolution and multiple sensors have also led to a growing complexity of interpretation that calls for a greater need of consulting, verification and training in the field in order to make it eligible as an operational source of verification. Responding to this need, Fleximage is extending its Image intelligence (IMINT) training program to include a fully operational and flexible online consulting and training program. Image Intelligence (IMINT) Online Program, a new approach to acquiring IMINT expertise, supported by Internet technologies, and managed by a professional team of experts and technical staff. Fleximage has developed a virtual learning environment on the Internet for acquiring IMINT expertise. Called the IMINT Online Program, this dynamic learning environment provides complete flexibility and personalization of the process for acquiring expertise. The IMINT online program includes two services: Online Consulting and Online Training. The Online Consulting service is designed for the technical staff of an organization who are already operational in the field of image intelligence. Online Consulting enables these staff members to acquire pertinent expertise online that can be directly applied to their professional activity, such as IAEA verification tasks. The Online Training service is designed for the technical staff of an organization who are relatively new to the field of image intelligence. These staff members need to build expertise within a formal training program. Online Training is a flexible and structured program for acquiring IMINT expertise online

Image intelligence online consulting: A flexible and remote access to strategic information applied to verification of declaration

International Nuclear Information System (INIS)

Chassy, A.F. de; Denizot, L.

2001-01-01

Commercial satellite imagery is giving International Institutions specialized Information Departments access to a great source of valuable intelligence. High resolution and multiple sensors have also led to a growing complexity of interpretation that calls for a greater need of consulting, verification and training in the field in order to make it eligible as an operational source of verification. Responding to this need, Fleximage is extending its Image Intelligence (IMINT) training program to include a fully operational and flexible online consulting and training program. Image Intelligence (IMINT) Online Program, a new approach to acquiring IMINT expertise, supported by Internet technologies, and managed by a professional team of experts and technical staff. Fleximage has developed a virtual learning environment on the Internet for acquiring IMINT expertise. Called the IMINT Online Program, this dynamic learning environment provides complete flexibility and personalization of the process for acquiring expertise. The IMINT online program includes two services: Online Consulting and Online Training. The Online Consulting service is designed for the technical staff of an organization who are already operational in the field of image intelligence. Online Consulting enables these staff members to acquire pertinent expertise online that can be directly applied to their professional activity, such as IAEA verification tasks. The IMINT virtual Consulting and Training services indicated above are made possible thanks to the latest in Internet-based technologies including: multimedia CD-ROM, Internet technologies, rich media content (Audio, Video and Flash), application sharing, platform Maintenance Tools, secured connections and authentication, knowledge database technologies. IMINT Online Program operates owing to: specialized experts in fields relating to IMINT. These experts carry out the tasks of consultants, coaches, occasional speakers, and course content designers

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

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

Role of IGRT in patient positioning and verification

International Nuclear Information System (INIS)

Mijnheer, Ben

2008-01-01

Image-guided radiation therapy is 'Frequent imaging in the treatment room during a course of radiotherapy to guide the treatment process'. Instrumentation related to IGRT is highlighted. Focus of the lecture was on clinical experience gained by NKI-AVL, such as the use of EPID (electronic portal imaging devices) and CBCT (cone beam computed tomography) and their comparison: good results for head and neck and prostate/bladder patients: portal imaging was replaced by CBCT. After further investigation convincing results for lung patients were obtained: portal imaging was replaced by CBCT. Scan protocols were developed for these patient groups. Since February 2004 CBCT-based decision rules have been developed for: Head and Neck (Bony anatomy); Prostate (Bony anatomy; Soft tissue registration); Lung (Bony anatomy, Soft tissue registration); Brain (Bony anatomy); and Breast, bladder and liver (in progress). Final remarks are as follows: The introduction of various IGRT techniques allowed 3D verification of the position of target volumes and organs at risk just before or during treatment. Because the information is in 3D, or sometimes even in 4D, in principle these IGRT approaches provide more information compared to the use of 2D verification methods (e.g. EPIDs). Clinical data are becoming available to assess quantitatively for which treatment techniques IGRT approaches are advantageous compared to the use of conventional verification methods taking the additional resources (time, money, manpower) into account. (P.A.)

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)

An Optimized Online Verification Imaging Procedure for External Beam Partial Breast Irradiation

International Nuclear Information System (INIS)

Willis, David J.; Kron, Tomas; Chua, Boon

2011-01-01

The purpose of this study was to evaluate the capabilities of a kilovoltage (kV) on-board imager (OBI)-equipped linear accelerator in the setting of on-line verification imaging for external-beam partial breast irradiation. Available imaging techniques were optimized and assessed for image quality using a modified anthropomorphic phantom. Imaging dose was also assessed. Imaging techniques were assessed for physical clearance between patient and treatment machine using a volunteer. Nonorthogonal kV image pairs were identified as optimal in terms of image quality, clearance, and dose. After institutional review board approval, this approach was used for 17 patients receiving accelerated partial breast irradiation. Imaging was performed before every fraction verification with online correction of setup deviations >5 mm (total image sessions = 170). Treatment staff rated risk of collision and visibility of tumor bed surgical clips where present. Image session duration and detected setup deviations were recorded. For all cases, both image projections (n = 34) had low collision risk. Surgical clips were rated as well as visualized in all cases where they were present (n = 5). The average imaging session time was 6 min, 16 sec, and a reduction in duration was observed as staff became familiar with the technique. Setup deviations of up to 1.3 cm were detected before treatment and subsequently confirmed offline. Nonorthogonal kV image pairs allowed effective and efficient online verification for partial breast irradiation. It has yet to be tested in a multicenter study to determine whether it is dependent on skilled treatment staff.

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

Optimized procedure for calibration and verification multileaf collimator from Elekta Synergy accelerator

International Nuclear Information System (INIS)

Castel Millan, A.; Perellezo Mazon, A.; Fernandez Ibiza, J.; Arnalte Olloquequi, M.; Armengol Martinez, S.; Rodriguez Rey, A.; Guedea Edo, F.

2011-01-01

The objective of this work is to design an optimized procedure for calibration and verification of a multileaf collimator used so as to allow the EPID and the image plate in a complementary way, using different processing systems. With this procedure we have two equivalent alternative as the same parameters obtained for the calibration of multileaf Elekta Synergy accelerator.

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.

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

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.)

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

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.

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)

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.

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.

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.

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

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.

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.)

Online Signature Verification using Recurrent Neural Network and Length-normalized Path Signature

OpenAIRE

Lai, Songxuan; Jin, Lianwen; Yang, Weixin

2017-01-01

Inspired by the great success of recurrent neural networks (RNNs) in sequential modeling, we introduce a novel RNN system to improve the performance of online signature verification. The training objective is to directly minimize intra-class variations and to push the distances between skilled forgeries and genuine samples above a given threshold. By back-propagating the training signals, our RNN network produced discriminative features with desired metrics. Additionally, we propose a novel d...

SU-E-T-602: Patient-Specific Online Dose Verification Based On Transmission Detector Measurements

Energy Technology Data Exchange (ETDEWEB)

Thoelking, J; Yuvaraj, S; Jens, F; Lohr, F; Wenz, F; Wertz, H; Wertz, H [University Medical Center Mannheim, University of Heidelberg, Mannheim, Baden-Wuerttemberg (Germany)

2015-06-15

Purpose: Intensity modulated radiotherapy requires a comprehensive quality assurance program in general and ideally independent verification of dose delivery. Since conventional 2D detector arrays allow only pre-treatment verification, there is a debate concerning the need of online dose verification. This study presents the clinical performance, including dosimetric plan verification in 2D as well as in 3D and the error detection abilities of a new transmission detector (TD) for online dose verification of 6MV photon beam. Methods: To validate the dosimetric performance of the new device, dose reconstruction based on TD measurements were compared to a conventional pre-treatment verification method (reference) and treatment planning system (TPS) for 18 IMRT and VMAT treatment plans. Furthermore, dose reconstruction inside the patient based on TD read-out was evaluated by comparing various dose volume indices and 3D gamma evaluations against independent dose computation and TPS. To investigate the sensitivity of the new device, different types of systematic and random errors for leaf positions and linac output were introduced in IMRT treatment sequences. Results: The 2D gamma index evaluation of transmission detector based dose reconstruction showed an excellent agreement for all IMRT and VMAT plans compared to reference measurements (99.3±1.2)% and TPS (99.1±0.7)%. Good agreement was also obtained for 3D dose reconstruction based on TD read-out compared to dose computation (mean gamma value of PTV = 0.27±0.04). Only a minimal dose underestimation within the target volume was observed when analyzing DVH indices (<1%). Positional errors in leaf banks larger than 1mm and errors in linac output larger than 2% could clearly identified with the TD. Conclusion: Since 2D and 3D evaluations for all IMRT and VMAT treatment plans were in excellent agreement with reference measurements and dose computation, the new TD is suitable to qualify for routine treatment plan

SU-E-T-602: Patient-Specific Online Dose Verification Based On Transmission Detector Measurements

International Nuclear Information System (INIS)

Thoelking, J; Yuvaraj, S; Jens, F; Lohr, F; Wenz, F; Wertz, H; Wertz, H

2015-01-01

Purpose: Intensity modulated radiotherapy requires a comprehensive quality assurance program in general and ideally independent verification of dose delivery. Since conventional 2D detector arrays allow only pre-treatment verification, there is a debate concerning the need of online dose verification. This study presents the clinical performance, including dosimetric plan verification in 2D as well as in 3D and the error detection abilities of a new transmission detector (TD) for online dose verification of 6MV photon beam. Methods: To validate the dosimetric performance of the new device, dose reconstruction based on TD measurements were compared to a conventional pre-treatment verification method (reference) and treatment planning system (TPS) for 18 IMRT and VMAT treatment plans. Furthermore, dose reconstruction inside the patient based on TD read-out was evaluated by comparing various dose volume indices and 3D gamma evaluations against independent dose computation and TPS. To investigate the sensitivity of the new device, different types of systematic and random errors for leaf positions and linac output were introduced in IMRT treatment sequences. Results: The 2D gamma index evaluation of transmission detector based dose reconstruction showed an excellent agreement for all IMRT and VMAT plans compared to reference measurements (99.3±1.2)% and TPS (99.1±0.7)%. Good agreement was also obtained for 3D dose reconstruction based on TD read-out compared to dose computation (mean gamma value of PTV = 0.27±0.04). Only a minimal dose underestimation within the target volume was observed when analyzing DVH indices (<1%). Positional errors in leaf banks larger than 1mm and errors in linac output larger than 2% could clearly identified with the TD. Conclusion: Since 2D and 3D evaluations for all IMRT and VMAT treatment plans were in excellent agreement with reference measurements and dose computation, the new TD is suitable to qualify for routine treatment plan

Tracking tumor boundary in MV-EPID images without implanted markers: A feasibility study

International Nuclear Information System (INIS)

Zhang, Xiaoyong; Homma, Noriyasu; Ichiji, Kei; Takai, Yoshihiro; Yoshizawa, Makoto

2015-01-01

Purpose: To develop a markerless tracking algorithm to track the tumor boundary in megavoltage (MV)-electronic portal imaging device (EPID) images for image-guided radiation therapy. Methods: A level set method (LSM)-based algorithm is developed to track tumor boundary in EPID image sequences. Given an EPID image sequence, an initial curve is manually specified in the first frame. Driven by a region-scalable energy fitting function, the initial curve automatically evolves toward the tumor boundary and stops on the desired boundary while the energy function reaches its minimum. For the subsequent frames, the tracking algorithm updates the initial curve by using the tracking result in the previous frame and reuses the LSM to detect the tumor boundary in the subsequent frame so that the tracking processing can be continued without user intervention. The tracking algorithm is tested on three image datasets, including a 4-D phantom EPID image sequence, four digitally deformable phantom image sequences with different noise levels, and four clinical EPID image sequences acquired in lung cancer treatment. The tracking accuracy is evaluated based on two metrics: centroid localization error (CLE) and volume overlap index (VOI) between the tracking result and the ground truth. Results: For the 4-D phantom image sequence, the CLE is 0.23 ± 0.20 mm, and VOI is 95.6% ± 0.2%. For the digital phantom image sequences, the total CLE and VOI are 0.11 ± 0.08 mm and 96.7% ± 0.7%, respectively. In addition, for the clinical EPID image sequences, the proposed algorithm achieves 0.32 ± 0.77 mm in the CLE and 72.1% ± 5.5% in the VOI. These results demonstrate the effectiveness of the authors’ proposed method both in tumor localization and boundary tracking in EPID images. In addition, compared with two existing tracking algorithms, the proposed method achieves a higher accuracy in tumor localization. Conclusions: In this paper, the authors presented a feasibility study of tracking

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%.

TH-AB-202-02: Real-Time Verification and Error Detection for MLC Tracking Deliveries Using An Electronic Portal Imaging Device

International Nuclear Information System (INIS)

J Zwan, B; Colvill, E; Booth, J; J O’Connor, D; Keall, P; B Greer, P

2016-01-01

Purpose: The added complexity of the real-time adaptive multi-leaf collimator (MLC) tracking increases the likelihood of undetected MLC delivery errors. In this work we develop and test a system for real-time delivery verification and error detection for MLC tracking radiotherapy using an electronic portal imaging device (EPID). Methods: The delivery verification system relies on acquisition and real-time analysis of transit EPID image frames acquired at 8.41 fps. In-house software was developed to extract the MLC positions from each image frame. Three comparison metrics were used to verify the MLC positions in real-time: (1) field size, (2) field location and, (3) field shape. The delivery verification system was tested for 8 VMAT MLC tracking deliveries (4 prostate and 4 lung) where real patient target motion was reproduced using a Hexamotion motion stage and a Calypso system. Sensitivity and detection delay was quantified for various types of MLC and system errors. Results: For both the prostate and lung test deliveries the MLC-defined field size was measured with an accuracy of 1.25 cm 2 (1 SD). The field location was measured with an accuracy of 0.6 mm and 0.8 mm (1 SD) for lung and prostate respectively. Field location errors (i.e. tracking in wrong direction) with a magnitude of 3 mm were detected within 0.4 s of occurrence in the X direction and 0.8 s in the Y direction. Systematic MLC gap errors were detected as small as 3 mm. The method was not found to be sensitive to random MLC errors and individual MLC calibration errors up to 5 mm. Conclusion: EPID imaging may be used for independent real-time verification of MLC trajectories during MLC tracking deliveries. Thresholds have been determined for error detection and the system has been shown to be sensitive to a range of delivery errors.

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

Cine EPID evaluation of two non-commercial techniques for DIBH

Energy Technology Data Exchange (ETDEWEB)

Jensen, Christopher; Urribarri, Jaime; Cail, Daniel; Rottmann, Joerg; Mishra, Pankaj; Lingos, Tatiana; Niedermayr, Thomas; Berbeco, Ross, E-mail: rberbeco@lroc.harvard.edu [Brigham and Women' s Hospital, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts 02115 (United States)

2014-02-15

Purpose: To evaluate the efficacy of two noncommercial techniques for deep inspiration breathhold (DIBH) treatment of left-sided breast cancer (LSBC) usingcine electronic portal imaging device (EPID) images. Methods: 23 875 EPID images of 65 patients treated for LSBC at two different cancer treatment centers were retrieved. At the Milford Regional Cancer Center, DIBH stability was maintained by visual alignment of inroom lasers and patient skin tattoos (TAT). At the South Shore Hospital, a distance-measuring laser device (RTSSD) was implemented. For both centers,cine EPID images were acquired at least once per week during beam-on. Chest wall position relative to image boundary was measured and tracked over the course of treatment for every patient and treatment fraction for which data were acquired. Results: Median intrabeam chest motion was 0.31 mm for the TAT method and 0.37 mm for the RTSSD method. The maximum excursions exceeded our treatment protocol threshold of 3 mm in 0.3% of cases (TAT) and 1.2% of cases (RTSSD). The authors did not observe a clinically significant difference between the two datasets. Conclusions: Both noncommercial techniques for monitoring the DIBH location provided DIBH stability within the predetermined treatment protocol parameters (<3 mm). The intreatment imaging offered by the EPID operating incine mode facilitates retrospective analysis and validation of both techniques.

Cine EPID evaluation of two non-commercial techniques for DIBH

International Nuclear Information System (INIS)

Jensen, Christopher; Urribarri, Jaime; Cail, Daniel; Rottmann, Joerg; Mishra, Pankaj; Lingos, Tatiana; Niedermayr, Thomas; Berbeco, Ross

2014-01-01

Purpose: To evaluate the efficacy of two noncommercial techniques for deep inspiration breathhold (DIBH) treatment of left-sided breast cancer (LSBC) usingcine electronic portal imaging device (EPID) images. Methods: 23 875 EPID images of 65 patients treated for LSBC at two different cancer treatment centers were retrieved. At the Milford Regional Cancer Center, DIBH stability was maintained by visual alignment of inroom lasers and patient skin tattoos (TAT). At the South Shore Hospital, a distance-measuring laser device (RTSSD) was implemented. For both centers,cine EPID images were acquired at least once per week during beam-on. Chest wall position relative to image boundary was measured and tracked over the course of treatment for every patient and treatment fraction for which data were acquired. Results: Median intrabeam chest motion was 0.31 mm for the TAT method and 0.37 mm for the RTSSD method. The maximum excursions exceeded our treatment protocol threshold of 3 mm in 0.3% of cases (TAT) and 1.2% of cases (RTSSD). The authors did not observe a clinically significant difference between the two datasets. Conclusions: Both noncommercial techniques for monitoring the DIBH location provided DIBH stability within the predetermined treatment protocol parameters (<3 mm). The intreatment imaging offered by the EPID operating incine mode facilitates retrospective analysis and validation of both techniques

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.

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.

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.

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)

Verification test for on-line diagnosis algorithm based on noise analysis

International Nuclear Information System (INIS)

Tamaoki, T.; Naito, N.; Tsunoda, T.; Sato, M.; Kameda, A.

1980-01-01

An on-line diagnosis algorithm was developed and its verification test was performed using a minicomputer. This algorithm identifies the plant state by analyzing various system noise patterns, such as power spectral densities, coherence functions etc., in three procedure steps. Each obtained noise pattern is examined by using the distances from its reference patterns prepared for various plant states. Then, the plant state is identified by synthesizing each result with an evaluation weight. This weight is determined automatically from the reference noise patterns prior to on-line diagnosis. The test was performed with 50 MW (th) Steam Generator noise data recorded under various controller parameter values. The algorithm performance was evaluated based on a newly devised index. The results obtained with one kind of weight showed the algorithm efficiency under the proper selection of noise patterns. Results for another kind of weight showed the robustness of the algorithm to this selection. (orig.)

The radiation isocenter verification using an electronic system of image portal; Verificacion del isocentro de radiacion utilizando un sistema electronico de imagen portal

Energy Technology Data Exchange (ETDEWEB)

Merino Gestoso, J. A.; Portas Ferradas, B. C.; Rosa Menendez, P.; Chapel Gomez, M. L.; Fernandez Cerezo, S.; Vazquez Varela, P.

2013-07-01

In this paper we present a procedure optimized for verification the isocenter of radiation with respect to the rotation of the gantry and the turn isocentric table of two accelerators SIEMENS, ONCOR and ARTISTE with a mannequin developed in our service and analyzing the images acquired with the EPID from each of the teams. (Author)

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

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.

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

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

Gated Treatment Delivery Verification With On-Line Megavoltage Fluoroscopy

International Nuclear Information System (INIS)

Tai An; Christensen, James D.; Gore, Elizabeth; Khamene, Ali; Boettger, Thomas; Li, X. Allen

2010-01-01

Purpose: To develop and clinically demonstrate the use of on-line real-time megavoltage (MV) fluoroscopy for gated treatment delivery verification. Methods and Materials: Megavoltage fluoroscopy (MVF) image sequences were acquired using a flat panel equipped for MV cone-beam CT in synchrony with the respiratory signal obtained from the Anzai gating device. The MVF images can be obtained immediately before or during gated treatment delivery. A prototype software tool (named RTReg4D) was developed to register MVF images with phase-sequenced digitally reconstructed radiograph images generated from the treatment planning system based on four-dimensional CT. The image registration can be used to reposition the patient before or during treatment delivery. To demonstrate the reliability and clinical usefulness, the system was first tested using a thoracic phantom and then prospectively in actual patient treatments under an institutional review board-approved protocol. Results: The quality of the MVF images for lung tumors is adequate for image registration with phase-sequenced digitally reconstructed radiographs. The MVF was found to be useful for monitoring inter- and intrafractional variations of tumor positions. With the planning target volume contour displayed on the MVF images, the system can verify whether the moving target stays within the planning target volume margin during gated delivery. Conclusions: The use of MVF images was found to be clinically effective in detecting discrepancies in tumor location before and during respiration-gated treatment delivery. The tools and process developed can be useful for gated treatment delivery verification.

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.

Feasibility study of a dual detector configuration concept for simultaneous megavoltage imaging and dose verification in radiotherapy

International Nuclear Information System (INIS)

Deshpande, Shrikant; McNamara, Aimee L.; Holloway, Lois; Metcalfe, Peter; Vial, Philip

2015-01-01

Purpose: To test the feasibility of a dual detector concept for comprehensive verification of external beam radiotherapy. Specifically, the authors test the hypothesis that a portal imaging device coupled to a 2D dosimeter provides a system capable of simultaneous imaging and dose verification, and that the presence of each device does not significantly detract from the performance of the other. Methods: The dual detector configuration comprised of a standard radiotherapy electronic portal imaging device (EPID) positioned directly on top of an ionization-chamber array (ICA) with 2 cm solid water buildup material (between EPID and ICA) and 5 cm solid backscatter material. The dose response characteristics of the ICA and the imaging performance of the EPID in the dual detector configuration were compared to the performance in their respective reference clinical configurations. The reference clinical configurations were 6 cm solid water buildup material, an ICA, and 5 cm solid water backscatter material as the reference dosimetry configuration, and an EPID with no additional buildup or solid backscatter material as the reference imaging configuration. The dose response of the ICA was evaluated by measuring the detector’s response with respect to off-axis position, field size, and transit object thickness. Clinical dosimetry performance was evaluated by measuring a range of clinical intensity-modulated radiation therapy (IMRT) beams in transit and nontransit geometries. The imaging performance of the EPID was evaluated quantitatively by measuring the contrast-to-noise ratio (CNR) and spatial resolution. Images of an anthropomorphic phantom were also used for qualitative assessment. Results: The measured off-axis and field size response with the ICA in both transit and nontransit geometries for both dual detector configuration and reference dosimetry configuration agreed to within 1%. Transit dose response as a function of object thickness agreed to within 0.5%. All

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)

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...

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.

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

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.

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)

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.

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.

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.

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

Online Signature Verification: To What Extent Should a Classifier be Trusted in?

Directory of Open Access Journals (Sweden)

Marianela Parodi

2017-08-01

Full Text Available To select the best features to model the signatures is one of the major challenges in the field of online signature verification. To combine different feature sets, selected by different criteria, is a useful technique to address this problem. In this line, the analysis of different features and their discriminative power has been researchers’ main concern, paying less attention to the way in which the different kind of features are combined. Moreover, the fact that conflicting results may appear when several classifiers are being used, has rarely been taken into account. In this paper, a score level fusion scheme is proposed to combine three different and meaningful feature sets, viz., an automatically selected feature set, a feature set relevant to Forensic Handwriting Experts (FHEs, and a global feature set. The score level fusion is performed within the framework of the Belief Function Theory (BFT, in order to address the problem of the conflicting results appearing when multiple classifiers are being used. Two different models, namely, the Denoeux and the Appriou models, are used to embed the problem within this framework, where the fusion is performed resorting to two well-known combination rules, namely, the Dempster-Shafer (DS and the Proportional Conflict Redistribution (PCR5 one. In order to analyze the robustness of the proposed score level fusion approach, the combination is performed for the same verification system using two different classification techniques, namely, Ramdon Forests (RF and Support Vector Machines (SVM. Experimental results, on a publicly available database, show that the proposed score level fusion approach allows the system to have a very good trade-off between verification results and reliability.

Data Exchanges and Verifications Online (DEVO)

Data.gov (United States)

Social Security Administration — DEVO is the back-end application for processing SSN verifications and data exchanges. DEVO uses modern technology for parameter driven processing of both batch and...

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

SU-D-BRC-03: Development and Validation of an Online 2D Dose Verification System for Daily Patient Plan Delivery Accuracy Check

International Nuclear Information System (INIS)

Zhao, J; Hu, W; Xing, Y; Wu, X; Li, Y

2016-01-01

Purpose: All plan verification systems for particle therapy are designed to do plan verification before treatment. However, the actual dose distributions during patient treatment are not known. This study develops an online 2D dose verification tool to check the daily dose delivery accuracy. Methods: A Siemens particle treatment system with a modulated scanning spot beam is used in our center. In order to do online dose verification, we made a program to reconstruct the delivered 2D dose distributions based on the daily treatment log files and depth dose distributions. In the log files we can get the focus size, position and particle number for each spot. A gamma analysis is used to compare the reconstructed dose distributions with the dose distributions from the TPS to assess the daily dose delivery accuracy. To verify the dose reconstruction algorithm, we compared the reconstructed dose distributions to dose distributions measured using PTW 729XDR ion chamber matrix for 13 real patient plans. Then we analyzed 100 treatment beams (58 carbon and 42 proton) for prostate, lung, ACC, NPC and chordoma patients. Results: For algorithm verification, the gamma passing rate was 97.95% for the 3%/3mm and 92.36% for the 2%/2mm criteria. For patient treatment analysis,the results were 97.7%±1.1% and 91.7%±2.5% for carbon and 89.9%±4.8% and 79.7%±7.7% for proton using 3%/3mm and 2%/2mm criteria, respectively. The reason for the lower passing rate for the proton beam is that the focus size deviations were larger than for the carbon beam. The average focus size deviations were −14.27% and −6.73% for proton and −5.26% and −0.93% for carbon in the x and y direction respectively. Conclusion: The verification software meets our requirements to check for daily dose delivery discrepancies. Such tools can enhance the current treatment plan and delivery verification processes and improve safety of clinical treatments.

SU-D-BRC-03: Development and Validation of an Online 2D Dose Verification System for Daily Patient Plan Delivery Accuracy Check

Energy Technology Data Exchange (ETDEWEB)

Zhao, J; Hu, W [Fudan University Shanghai Cancer Center, Shanghai, Shanghai (China); Xing, Y [Fudan univercity shanghai proton and heavy ion center, Shanghai (China); Wu, X [Fudan university shanghai proton and heavy ion center, Shanghai, shagnhai (China); Li, Y [Department of Medical physics at Shanghai Proton and Heavy Ion Center, Shanghai, Shanghai (China)

2016-06-15

Purpose: All plan verification systems for particle therapy are designed to do plan verification before treatment. However, the actual dose distributions during patient treatment are not known. This study develops an online 2D dose verification tool to check the daily dose delivery accuracy. Methods: A Siemens particle treatment system with a modulated scanning spot beam is used in our center. In order to do online dose verification, we made a program to reconstruct the delivered 2D dose distributions based on the daily treatment log files and depth dose distributions. In the log files we can get the focus size, position and particle number for each spot. A gamma analysis is used to compare the reconstructed dose distributions with the dose distributions from the TPS to assess the daily dose delivery accuracy. To verify the dose reconstruction algorithm, we compared the reconstructed dose distributions to dose distributions measured using PTW 729XDR ion chamber matrix for 13 real patient plans. Then we analyzed 100 treatment beams (58 carbon and 42 proton) for prostate, lung, ACC, NPC and chordoma patients. Results: For algorithm verification, the gamma passing rate was 97.95% for the 3%/3mm and 92.36% for the 2%/2mm criteria. For patient treatment analysis,the results were 97.7%±1.1% and 91.7%±2.5% for carbon and 89.9%±4.8% and 79.7%±7.7% for proton using 3%/3mm and 2%/2mm criteria, respectively. The reason for the lower passing rate for the proton beam is that the focus size deviations were larger than for the carbon beam. The average focus size deviations were −14.27% and −6.73% for proton and −5.26% and −0.93% for carbon in the x and y direction respectively. Conclusion: The verification software meets our requirements to check for daily dose delivery discrepancies. Such tools can enhance the current treatment plan and delivery verification processes and improve safety of clinical treatments.

Development of a Compton camera for online ion beam range verification via prompt γ detection

Energy Technology Data Exchange (ETDEWEB)

Aldawood, S. [LMU Munich, Garching (Germany); King Saud University, Riyadh (Saudi Arabia); Liprandi, S.; Marinsek, T.; Bortfeldt, J.; Lang, C.; Lutter, R.; Dedes, G.; Parodi, K.; Thirolf, P.G. [LMU Munich, Garching (Germany); Maier, L.; Gernhaeuser, R. [TU Munich, Garching (Germany); Kolff, H. van der [LMU Munich, Garching (Germany); TU Delft (Netherlands); Castelhano, I. [LMU Munich, Garching (Germany); University of Lisbon, Lisbon (Portugal); Schaart, D.R. [TU Delft (Netherlands)

2015-07-01

Precise and preferably online ion beam range verification is a mandatory prerequisite to fully exploit the advantages of hadron therapy in cancer treatment. An imaging system is being developed in Garching aiming to detect promptγ rays induced by nuclear reactions between the ion beam and biological tissue. The Compton camera prototype consists of a stack of six customized double-sided Si-strip detectors (DSSSD, 50 x 50 mm{sup 2}, 0.5 mm thick, 128 strips/side) acting as scatterer, while the absorber is formed by a monolithic LaBr{sub 3}:Ce scintillator crystal (50 x 50 x 30 mm{sup 3}) read out by a position-sensitive multi-anode photomultiplier (Hamamatsu H9500). The on going characterization of the Compton camera properties and its individual components both offline in the laboratory as well as online using proton beam are presented.

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.

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

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.

Analyzing personalized policies for online biometric verification.

Science.gov (United States)

Sadhwani, Apaar; Yang, Yan; Wein, Lawrence M

2014-01-01

Motivated by India's nationwide biometric program for social inclusion, we analyze verification (i.e., one-to-one matching) in the case where we possess similarity scores for 10 fingerprints and two irises between a resident's biometric images at enrollment and his biometric images during his first verification. At subsequent verifications, we allow individualized strategies based on these 12 scores: we acquire a subset of the 12 images, get new scores for this subset that quantify the similarity to the corresponding enrollment images, and use the likelihood ratio (i.e., the likelihood of observing these scores if the resident is genuine divided by the corresponding likelihood if the resident is an imposter) to decide whether a resident is genuine or an imposter. We also consider two-stage policies, where additional images are acquired in a second stage if the first-stage results are inconclusive. Using performance data from India's program, we develop a new probabilistic model for the joint distribution of the 12 similarity scores and find near-optimal individualized strategies that minimize the false reject rate (FRR) subject to constraints on the false accept rate (FAR) and mean verification delay for each resident. Our individualized policies achieve the same FRR as a policy that acquires (and optimally fuses) 12 biometrics for each resident, which represents a five (four, respectively) log reduction in FRR relative to fingerprint (iris, respectively) policies previously proposed for India's biometric program. The mean delay is [Formula: see text] sec for our proposed policy, compared to 30 sec for a policy that acquires one fingerprint and 107 sec for a policy that acquires all 12 biometrics. This policy acquires iris scans from 32-41% of residents (depending on the FAR) and acquires an average of 1.3 fingerprints per resident.

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

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.

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

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

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

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.

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

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

Online Kidney Position Verification Using Non-Contrast Radiographs on a Linear Accelerator with on Board KV X-Ray Imaging Capability

International Nuclear Information System (INIS)

Willis, David J.; Kron, Tomas; Hubbard, Patricia; Haworth, Annette; Wheeler, Greg; Duchesne, Gillian M.

2009-01-01

The kidneys are dose-limiting organs in abdominal radiotherapy. Kilovoltage (kV) radiographs can be acquired using on-board imager (OBI)-equipped linear accelerators with better soft tissue contrast and lower radiation doses than conventional portal imaging. A feasibility study was conducted to test the suitability of anterior-posterior (AP) non-contrast kV radiographs acquired at treatment time for online kidney position verification. Anthropomorphic phantoms were used to evaluate image quality and radiation dose. Institutional Review Board approval was given for a pilot study that enrolled 5 adults and 5 children. Customized digitally reconstructed radiographs (DRRs) were generated to provide a priori information on kidney shape and position. Radiotherapy treatment staff performed online evaluation of kidney visibility on OBI radiographs. Kidney dose measured in a pediatric anthropomorphic phantom was 0.1 cGy for kV imaging and 1.7 cGy for MV imaging. Kidneys were rated as well visualized in 60% of patients (90% confidence interval, 34-81%). The likelihood of visualization appears to be influenced by the relative AP separation of the abdomen and kidneys, the axial profile of the kidneys, and their relative contrast with surrounding structures. Online verification of kidney position using AP non-contrast kV radiographs on an OBI-equipped linear accelerator appears feasible for patients with suitable abdominal anatomy. Kidney position information provided is limited to 2-dimensional 'snapshots,' but this is adequate in some clinical situations and potentially advantageous in respiratory-correlated treatments. Successful clinical implementation requires customized partial DRRs, appropriate imaging parameters, and credentialing of treatment staff.

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

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.

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

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

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.

The Prevalence and Gratification of Nude Self-Presentation of Men Who Have Sex with Men in Online-Dating Environments: Attracting Attention, Empowerment, and Self-Verification.

Science.gov (United States)

Lemke, Richard; Merz, Simon

2018-01-01

This study builds on research about the importance of body presentation among men who have sex with men (MSM) by exploring the phenomenon of nude body presentation in online dating environments. In a quantitative survey of N = 9,235 MSM users of a gay online dating site (ODS) in Germany, the prevalence of nude pictures and gratifications sought while displaying them were investigated. About two-thirds of the participants declared that they use nude pictures in their dating profiles, with only small differences in prevalence between members of different ages, education levels, and sexual orientation. Furthermore, the results indicate that the use of nudity is driven by three underlying gratifications: (1) Attracting attention, meaning that nudity is used to accelerate sexual outcomes from online dating use; (2) empowerment, meaning that nudity online serves as an environment for otherwise and elsewhere inhibited forms of body presentation; and (3) self-verification, whereby nudity is used as a means of receiving affirmation from others. Regression analyses are used to investigate associations of these gratifications with sociodemographics and online dating behavior. Findings are discussed in relation to earlier research on self-presentation as well as theories of body importance among gay men. While earlier research has mainly focused on the negative implications of body presentation (e.g., self-objectification; reinforcing standards of beauty), the findings of this study hint that ODS may provide a platform for acts of nude body presentation that are not possible elsewhere and are thus accompanied by empowerment and self-verification.

A comparison of the use of bony anatomy and internal markers for offline verification and an evaluation of the potential benefit of online and offline verification protocols for prostate radiotherapy.

Science.gov (United States)

McNair, Helen A; Hansen, Vibeke N; Parker, Christopher C; Evans, Phil M; Norman, Andrew; Miles, Elizabeth; Harris, Emma J; Del-Acroix, Louise; Smith, Elizabeth; Keane, Richard; Khoo, Vincent S; Thompson, Alan C; Dearnaley, David P

2008-05-01

To evaluate the utility of intraprostatic markers in the treatment verification of prostate cancer radiotherapy. Specific aims were: to compare the effectiveness of offline correction protocols, either using gold markers or bony anatomy; to estimate the potential benefit of online correction protocol's using gold markers; to determine the presence and effect of intrafraction motion. Thirty patients with three gold markers inserted had pretreatment and posttreatment images acquired and were treated using an offline correction protocol and gold markers. Retrospectively, an offline protocol was applied using bony anatomy and an online protocol using gold markers. The systematic errors were reduced from 1.3, 1.9, and 2.5 mm to 1.1, 1.1, and 1.5 mm in the right-left (RL), superoinferior (SI), and anteroposterior (AP) directions, respectively, using the offline correction protocol and gold markers instead of bony anatomy. The subsequent decrease in margins was 1.7, 3.3, and 4 mm in the RL, SI, and AP directions, respectively. An offline correction protocol combined with an online correction protocol in the first four fractions reduced random errors further to 0.9, 1.1, and 1.0 mm in the RL, SI, and AP directions, respectively. A daily online protocol reduced all errors to markers is effective in reducing the systematic error. The value of online protocols is reduced by intrafraction motion.

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

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

A fast online hit verification method for the single ion hit system at GSI

International Nuclear Information System (INIS)

Du, G.; Fischer, B.; Barberet, P.; Heiss, M.

2006-01-01

For a single ion hit facility built to irradiate specific targets inside biological cells, it is necessary to prove that the ions hit the selected targets reliably because the ion hits usually cannot be seen. That ability is traditionally tested either indirectly by aiming at pre-etched tracks in a nuclear track detector or directly by making the ion tracks inside cells visible using a stain coupled to special proteins produced in response to ion hits. However, both methods are time consuming and hits can be verified only after the experiment. This means that targeting errors in the experiment cannot be corrected during the experiment. Therefore, we have developed a fast online hit verification method that measures the targeting accuracy electronically with a spatial resolution of ±1 μm before cell irradiation takes place. (authors)

Computerized method for estimation of the location of a lung tumor on EPID cine images without implanted markers in stereotactic body radiotherapy

International Nuclear Information System (INIS)

Arimura, H; Toyofuku, F; Higashida, Y; Onizuka, Y; Terashima, H; Egashira, Y; Shioyama, Y; Nomoto, S; Honda, H; Nakamura, K; Yoshidome, S; Anai, S

2009-01-01

The purpose of this study was to develop a computerized method for estimation of the location of a lung tumor in cine images on an electronic portal imaging device (EPID) without implanted markers during stereotactic body radiotherapy (SBRT). Each tumor region was segmented in the first EPID cine image, i.e., reference portal image, based on a multiple-gray level thresholding technique and a region growing technique, and then the image including the tumor region was cropped as a 'tumor template' image. The tumor location was determined as the position in which the tumor template image took the maximum cross-correlation value within each consecutive portal image, which was acquired in cine mode on the EPID in treatment. EPID images with 512 x 384 pixels (pixel size: 0.56 mm) were acquired at a sampling rate of 0.5 frame s -1 by using energies of 4, 6 or 10 MV on linear accelerators. We applied our proposed method to EPID cine images (226 frames) of 12 clinical cases (ages: 51-83, mean: 72) with a non-small cell lung cancer. As a result, the average location error between tumor points obtained by our method and the manual method was 1.47 ± 0.60 mm. This preliminary study suggests that our method based on the tumor template matching technique might be feasible for tracking the location of a lung tumor without implanted markers in SBRT.

A Comparison of the Use of Bony Anatomy and Internal Markers for Offline Verification and an Evaluation of the Potential Benefit of Online and Offline Verification Protocols for Prostate Radiotherapy

International Nuclear Information System (INIS)

McNair, Helen A.; Hansen, Vibeke N.; Parker, Christopher; Evans, Phil M.; Norman, Andrew; Miles, Elizabeth; Harris, Emma J.; Del-Acroix, Louise; Smith, Elizabeth; Keane, Richard; Khoo, Vincent S.; Thompson, Alan C.; Dearnaley, David P.

2008-01-01

Purpose: To evaluate the utility of intraprostatic markers in the treatment verification of prostate cancer radiotherapy. Specific aims were: to compare the effectiveness of offline correction protocols, either using gold markers or bony anatomy; to estimate the potential benefit of online correction protocol's using gold markers; to determine the presence and effect of intrafraction motion. Methods and Materials: Thirty patients with three gold markers inserted had pretreatment and posttreatment images acquired and were treated using an offline correction protocol and gold markers. Retrospectively, an offline protocol was applied using bony anatomy and an online protocol using gold markers. Results: The systematic errors were reduced from 1.3, 1.9, and 2.5 mm to 1.1, 1.1, and 1.5 mm in the right-left (RL), superoinferior (SI), and anteroposterior (AP) directions, respectively, using the offline correction protocol and gold markers instead of bony anatomy. The subsequent decrease in margins was 1.7, 3.3, and 4 mm in the RL, SI, and AP directions, respectively. An offline correction protocol combined with an online correction protocol in the first four fractions reduced random errors further to 0.9, 1.1, and 1.0 mm in the RL, SI, and AP directions, respectively. A daily online protocol reduced all errors to <1 mm. Intrafraction motion had greater impact on the effectiveness of the online protocol than the offline protocols. Conclusions: An offline protocol using gold markers is effective in reducing the systematic error. The value of online protocols is reduced by intrafraction motion

ON-LINE MONITORING OF I&C TRANSMITTERS AND SENSORS FOR CALIBRATION VERIFICATION AND RESPONSE TIME TESTING WAS SUCCESSFULLY IMPLEMENTED AT ATR

Energy Technology Data Exchange (ETDEWEB)

Erickson, Phillip A.; O' Hagan, Ryan; Shumaker, Brent; Hashemian, H. M.

2017-03-01

The Advanced Test Reactor (ATR) has always had a comprehensive procedure to verify the performance of its critical transmitters and sensors, including RTDs, and pressure, level, and flow transmitters. These transmitters and sensors have been periodically tested for response time and calibration verification to ensure accuracy. With implementation of online monitoring techniques at ATR, the calibration verification and response time testing of these transmitters and sensors are verified remotely, automatically, hands off, include more portions of the system, and can be performed at almost any time during process operations. The work was done under a DOE funded SBIR project carried out by AMS. As a result, ATR is now able to save the manpower that has been spent over the years on manual calibration verification and response time testing of its temperature and pressure sensors and refocus those resources towards more equipment reliability needs. More importantly, implementation of OLM will help enhance the overall availability, safety, and efficiency. Together with equipment reliability programs of ATR, the integration of OLM will also help with I&C aging management goals of the Department of Energy and long-time operation of ATR.

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.

Verification of setup errors in external beam radiation therapy using electronic portal imaging

International Nuclear Information System (INIS)

Krishna Murthy, K.; Al-Rahbi, Zakiya; Sivakumar, S.S.; Davis, C.A.; Ravichandran, R.

2008-01-01

The objective of this study was to conduct an audit on QA aspects of treatment delivery by the verification of the treatment fields position on different days to document the efficiency of immobilization methods and reproducibility of treatment. A retrospective study was carried out on 60 patients, each 20 treated for head and neck, breast, and pelvic sites; and a total of 506 images obtained by electronic portal imaging device (EPID) were analyzed. The portal images acquired using the EPID systems attached to the Varian linear accelerators were superimposed on the reference images. The anatomy matching software (Varian portal Vision. 6.0) was used, and the displacements in two dimensions and rotation were noted for each treated field to study the patient setup errors. The percentages of mean deviations more than 3 mm in lateral (X) and longitudinal (Y) directions were 17.5%, 11.25%, and 7.5% for breast, pelvis, and head and neck cases respectively. In all cases, the percentage of mean deviation with more than 5 mm error was 0.83%. The maximum average mean deviation in all the cases was 1.87. The average mean SD along X and Y directions in all the cases was less than 2.65. The results revealed that the ranges of setup errors are site specific and immobilization methods improve reproducibility. The observed variations were well within the limits. The study confirmed the accuracy and quality of treatments delivered to the patients. (author)

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

Amorphous silicon EPID calibration for dosimetric applications: comparison of a method based on Monte Carlo prediction of response with existing techniques

International Nuclear Information System (INIS)

Parent, L; Fielding, A L; Dance, D R; Seco, J; Evans, P M

2007-01-01

For EPID dosimetry, the calibration should ensure that all pixels have a similar response to a given irradiation. A calibration method (MC), using an analytical fit of a Monte Carlo simulated flood field EPID image to correct for the flood field image pixel intensity shape, was proposed. It was compared with the standard flood field calibration (FF), with the use of a water slab placed in the beam to flatten the flood field (WS) and with a multiple field calibration where the EPID was irradiated with a fixed 10 x 10 field for 16 different positions (MF). The EPID was used in its normal configuration (clinical setup) and with an additional 3 mm copper slab (modified setup). Beam asymmetry measured with a diode array was taken into account in MC and WS methods. For both setups, the MC method provided pixel sensitivity values within 3% of those obtained with the MF and WS methods (mean difference 2 ) and IMRT fields to within 3% of that obtained with WS and MF calibrations while differences with images calibrated with the FF method for fields larger than 10 x 10 cm 2 were up to 8%. MC, WS and MF methods all provided a major improvement on the FF method. Advantages and drawbacks of each method were reviewed

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.

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

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...

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

An ideal commissioning and quality assurance (QA) program for Volumetric Modulated Arc Therapy (VMAT) delivery systems should assess the performance of each individual dynamic component as a function of gantry angle. Procedures within such a program should also be time-efficient, independent of the delivery system and be sensitive to all types of errors. The purpose of this work is to develop a system for automated time-resolved commissioning and QA of VMAT control systems which meets these criteria. The procedures developed within this work rely solely on images obtained, using an electronic portal imaging device (EPID) without the presence of a phantom. During the delivery of specially designed VMAT test plans, EPID frames were acquired at 9.5 Hz, using a frame grabber. The set of test plans was developed to individually assess the performance of the dose delivery and multileaf collimator (MLC) control systems under varying levels of delivery complexities. An in-house software tool was developed to automatically extract features from the EPID images and evaluate the following characteristics as a function of gantry angle: dose delivery accuracy, dose rate constancy, beam profile constancy, gantry speed constancy, dynamic MLC positioning accuracy, MLC speed and acceleration constancy, and synchronization between gantry angle, MLC positioning and dose rate. Machine log files were also acquired during each delivery and subsequently compared to information extracted from EPID image frames. The largest difference between measured and planned dose at any gantry angle was 0.8% which correlated with rapid changes in dose rate and gantry speed. For all other test plans, the dose delivered was within 0.25% of the planned dose for all gantry angles. Profile constancy was not found to vary with gantry angle for tests where gantry speed and dose rate were constant, however, for tests with varying dose rate and gantry speed, segments with lower dose rate and higher gantry

A simple method to back-project isocenter dose of radiotherapy treatments using EPID transit dosimetry

Energy Technology Data Exchange (ETDEWEB)

Silveira, T.B.; Cerbaro, B.Q.; Rosa, L.A.R. da, E-mail: thiago.fisimed@gmail.com, E-mail: tbsilveira@inca.gov.br [Instituto de Radioproteção e Dosimetria (IRD/CNEN-RJ), Rio de Janeiro - RJ (Brazil)

2017-07-01

The aim of this work was to implement a simple algorithm to evaluate isocenter dose in a phantom using the back-projected transmitted dose acquired using an Electronic Portal Imaging Device (EPID) available in a Varian Trilogy accelerator with two nominal 6 and 10 MV photon beams. This algorithm was developed in MATLAB language, to calibrate EPID measured dose in absolute dose, using a deconvolution process, and to incorporate all scattering and attenuation contributions due to photon interactions with phantom. Modeling process was simplified by using empirical curve adjustments to describe the contribution of scattering and attenuation effects. The implemented algorithm and method were validated employing 19 patient treatment plans with 104 clinical irradiation fields projected on the phantom used. Results for EPID absolute dose calibration by deconvolution have showed percent deviations lower than 1%. Final method validation presented average percent deviations between isocenter doses calculated by back-projection and isocenter doses determined with ionization chamber of 1,86% (SD of 1,00%) and -0,94% (SD of 0,61%) for 6 and 10 MV, respectively. Normalized field by field analysis showed deviations smaller than 2% for 89% of all data for 6 MV beams and 94% for 10 MV beams. It was concluded that the proposed algorithm possesses sufficient accuracy to be used for in vivo dosimetry, being sensitive to detect dose delivery errors bigger than 3-4% for conformal and intensity modulated radiation therapy techniques. (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 (�

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.

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%.

State Online Query System (SOLQ)

Data.gov (United States)

Social Security Administration — Designed specifically for State Human Service agencies, SOLQ allows States real-time online access to SSA's SSN verification service and, if permitted, retrieval of...

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)

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)

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.

Amorphous silicon EPID calibration for dosimetric applications: comparison of a method based on Monte Carlo prediction of response with existing techniques

Energy Technology Data Exchange (ETDEWEB)

Parent, L [Joint Department of Physics, Institute of Cancer Research and Royal Marsden NHS Foundation Trust, Sutton (United Kingdom); Fielding, A L [School of Physical and Chemical Sciences, Queensland University of Technology, Brisbane (Australia); Dance, D R [Joint Department of Physics, Institute of Cancer Research and Royal Marsden NHS Foundation Trust, London (United Kingdom); Seco, J [Department of Radiation Oncology, Francis Burr Proton Therapy Center, Massachusetts General Hospital, Harvard Medical School, Boston (United States); Evans, P M [Joint Department of Physics, Institute of Cancer Research and Royal Marsden NHS Foundation Trust, Sutton (United Kingdom)

2007-07-21

For EPID dosimetry, the calibration should ensure that all pixels have a similar response to a given irradiation. A calibration method (MC), using an analytical fit of a Monte Carlo simulated flood field EPID image to correct for the flood field image pixel intensity shape, was proposed. It was compared with the standard flood field calibration (FF), with the use of a water slab placed in the beam to flatten the flood field (WS) and with a multiple field calibration where the EPID was irradiated with a fixed 10 x 10 field for 16 different positions (MF). The EPID was used in its normal configuration (clinical setup) and with an additional 3 mm copper slab (modified setup). Beam asymmetry measured with a diode array was taken into account in MC and WS methods. For both setups, the MC method provided pixel sensitivity values within 3% of those obtained with the MF and WS methods (mean difference <1%, standard deviation <2%). The difference of pixel sensitivity between MC and FF methods was up to 12.2% (clinical setup) and 11.8% (modified setup). MC calibration provided images of open fields (5 x 5 to 20 x 20 cm{sup 2}) and IMRT fields to within 3% of that obtained with WS and MF calibrations while differences with images calibrated with the FF method for fields larger than 10 x 10 cm{sup 2} were up to 8%. MC, WS and MF methods all provided a major improvement on the FF method. Advantages and drawbacks of each method were reviewed.

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.

Fast, daily linac verification for segmented IMRT using electronic portal imaging

International Nuclear Information System (INIS)

Vieira, Sandra C.; Bolt, Rene A.; Dirkx, Maarten L.P.; Visser, Andries G.; Heijmen, Ben J.M.

2006-01-01

Purpose: Intensity modulated radiotherapy (IMRT) requires dedicated quality assurance (QA). Recently, we have published a method for fast (1-2 min) and accurate linac quality control for dynamic multileaf collimation, using a portal imaging device. This method is in routine use for daily leaf motion verification. The purpose of the present study was to develop an equivalent procedure for QA of IMRT with segmented (static) multileaf collimation (SMLC). Materials and methods: The QA procedure is based on measurements performed during 3- to 8-month periods at Elekta, Siemens and Varian accelerators. On each measurement day, images were acquired for a field consisting of five 3 x 22 cm 2 segments. These 10 monitor unit (MU) segments were delivered in SMLC mode, moving the leaves from left to right. Deviations of realized leaf gap widths from the prescribed width were analysed to study the leaf positioning accuracy. To assess hysteresis in leaf positioning, the sequential delivery of the SMLC segments was also inverted. A static 20 x 20 cm 2 field was delivered with exposures between 1 and 50 MU to study the beam output and beam profile at low exposures. Comparisons with an ionisation chamber were made to verify the EPID dose measurements at low MU. Dedicated software was developed to improve the signal-to-noise ratio and to correct for image distortion. Results and conclusions: The observed long-term leaf gap reproducibility (1 standard deviation) was 0.1 mm for the Varian, and 0.2 mm for the Siemens and the Elekta accelerators. In all cases the hysteresis was negligible. Down to the lowest MU, beam output measurements performed with the EPID agreed within 1 ± 1% (1SD) with ionisation chamber measurements. These findings led to a fast (3-4 min) procedure for accurate, daily linac quality control for SMLC

Verification in Referral-Based Crowdsourcing

Science.gov (United States)

Naroditskiy, Victor; Rahwan, Iyad; Cebrian, Manuel; Jennings, Nicholas R.

2012-01-01

Online social networks offer unprecedented potential for rallying a large number of people to accomplish a given task. Here we focus on information gathering tasks where rare information is sought through “referral-based crowdsourcing”: the information request is propagated recursively through invitations among members of a social network. Whereas previous work analyzed incentives for the referral process in a setting with only correct reports, misreporting is known to be both pervasive in crowdsourcing applications, and difficult/costly to filter out. A motivating example for our work is the DARPA Red Balloon Challenge where the level of misreporting was very high. In order to undertake a formal study of verification, we introduce a model where agents can exert costly effort to perform verification and false reports can be penalized. This is the first model of verification and it provides many directions for future research, which we point out. Our main theoretical result is the compensation scheme that minimizes the cost of retrieving the correct answer. Notably, this optimal compensation scheme coincides with the winning strategy of the Red Balloon Challenge. PMID:23071530

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.

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

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)

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

Learning a Genetic Measure for Kinship Verification Using Facial Images

Directory of Open Access Journals (Sweden)

Lu Kou

2015-01-01

Full Text Available Motivated by the key observation that children generally resemble their parents more than other persons with respect to facial appearance, distance metric (similarity learning has been the dominant choice for state-of-the-art kinship verification via facial images in the wild. Most existing learning-based approaches to kinship verification, however, are focused on learning a genetic similarity measure in a batch learning manner, leading to less scalability for practical applications with ever-growing amount of data. To address this, we propose a new kinship verification approach by learning a sparse similarity measure in an online fashion. Experimental results on the kinship datasets show that our approach is highly competitive to the state-of-the-art alternatives in terms of verification accuracy, yet it is superior in terms of scalability for practical applications.

Overview of 3-year experience with large-scale electronic portal imaging device-based 3-dimensional transit dosimetry

NARCIS (Netherlands)

Mijnheer, Ben J.; González, Patrick; Olaciregui-Ruiz, Igor; Rozendaal, Roel A.; van Herk, Marcel; Mans, Anton

2015-01-01

To assess the usefulness of electronic portal imaging device (EPID)-based 3-dimensional (3D) transit dosimetry in a radiation therapy department by analyzing a large set of dose verification results. In our institution, routine in vivo dose verification of all treatments is performed by means of 3D

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 ...

Independent verification: operational phase liquid metal breeder reactors

International Nuclear Information System (INIS)

Bourne, P.B.

1981-01-01

The Fast Flux Test Facility (FFTF) recently achieved 100-percent power and now is in the initial stages of operation as a test reactor. An independent verification program has been established to assist in maintaining stable plant conditions, and to assure the safe operation of the reactor. Independent verification begins with the development of administrative procedures to control all other procedures and changes to the plant configurations. The technical content of the controlling procedures is subject to independent verification. The actual accomplishment of test procedures and operational maneuvers is witnessed by personnel not responsible for operating the plant. Off-normal events are analyzed, problem reports from other operating reactors are evaluated, and these results are used to improve on-line performance. Audits are used to confirm compliance with established practices and to identify areas where individual performance can be improved

Electronic portal imaging devices

International Nuclear Information System (INIS)

Lief, Eugene

2008-01-01

The topics discussed include, among others, the following: Role of portal imaging; Port films vs. EPID; Image guidance: Elekta volume view; Delivery verification; Automation tasks of portal imaging; Types of portal imaging (Fluorescent screen, mirror, and CCD camera-based imaging; Liquid ion chamber imaging; Amorpho-silicon portal imagers; Fluoroscopic portal imaging; Kodak CR reader; and Other types of portal imaging devices); QA of EPID; and Portal dosimetry (P.A.)

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

Energy Technology Data Exchange (ETDEWEB)

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.

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 ...

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

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.

Software verification in on-line systems

International Nuclear Information System (INIS)

Ehrenberger, W.

1980-01-01

Operator assistance is more and more provided by computers. Computers contain programs, whose quality should be above a certain level, before they are allowed to be used in reactor control rooms. Several possibilities for gaining software reliability figures are discussed in this paper. By supervising the testing procedure of a program, one can estimate the number of remaining programming errors. Such an estimation, however, is not very accurate. With mathematical proving procedures one can gain some knowledge on program properties. Such proving procedures are important for the verification of general WHILE-loops, which tend to be error prone. The program analysis decomposes a program into its parts. First the program structure is made visible, which includes the data movements and the control flow. From this analysis test cases can be derived that lead to a complete test. Program analysis can be done by hand or automatically. A statistical program test normally requires a large number of test runs. This number is diminished if details concerning both the program to be tested or its use are known in advance. (orig.)

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)

Poster — Thur Eve — 55: An automated XML technique for isocentre verification on the Varian TrueBeam

International Nuclear Information System (INIS)

Asiev, Krum; Mullins, Joel; DeBlois, François; Liang, Liheng; Syme, Alasdair

2014-01-01

Isocentre verification tests, such as the Winston-Lutz (WL) test, have gained popularity in the recent years as techniques such as stereotactic radiosurgery/radiotherapy (SRS/SRT) treatments are more commonly performed on radiotherapy linacs. These highly conformal treatments require frequent monitoring of the geometrical accuracy of the isocentre to ensure proper radiation delivery. At our clinic, the WL test is performed by acquiring with the EPID a collection of 8 images of a WL phantom fixed on the couch for various couch/gantry angles. This set of images is later analyzed to determine the isocentre size. The current work addresses the acquisition process. A manual WL test acquisition performed by and experienced physicist takes in average 25 minutes and is prone to user manipulation errors. We have automated this acquisition on a Varian TrueBeam STx linac (Varian, Palo Alto, USA). The Varian developer mode allows the execution of custom-made XML script files to control all aspects of the linac operation. We have created an XML-WL script that cycles through each couch/gantry combinations taking an EPID image at each position. This automated acquisition is done in less than 4 minutes. The reproducibility of the method was verified by repeating the execution of the XML file 5 times. The analysis of the images showed variation of the isocenter size less than 0.1 mm along the X, Y and Z axes and compares favorably to a manual acquisition for which we typically observe variations up to 0.5 mm

Image Processing Based Signature Verification Technique to Reduce Fraud in Financial Institutions

Directory of Open Access Journals (Sweden)

Hussein Walid

2016-01-01

Full Text Available Handwritten signature is broadly utilized as personal verification in financial institutions ensures the necessity for a robust automatic signature verification tool. This tool aims to reduce fraud in all related financial transactions’ sectors. This paper proposes an online, robust, and automatic signature verification technique using the recent advances in image processing and machine learning. Once the image of a handwritten signature for a customer is captured, several pre-processing steps are performed on it including filtration and detection of the signature edges. Afterwards, a feature extraction process is applied on the image to extract Speeded up Robust Features (SURF and Scale-Invariant Feature Transform (SIFT features. Finally, a verification process is developed and applied to compare the extracted image features with those stored in the database for the specified customer. Results indicate high accuracy, simplicity, and rapidity of the developed technique, which are the main criteria to judge a signature verification tool in banking and other financial institutions.

WE-EF-303-06: Feasibility of PET Image-Based On-Line Proton Beam-Range Verification with Simulated Uniform Phantom and Human Brain Studies

International Nuclear Information System (INIS)

Lou, K; Sun, X; Zhu, X; Grosshans, D; Clark, J; Shao, Y

2015-01-01

Purpose: To study the feasibility of clinical on-line proton beam range verification with PET imaging Methods: We simulated a 179.2-MeV proton beam with 5-mm diameter irradiating a PMMA phantom of human brain size, which was then imaged by a brain PET with 300*300*100-mm 3 FOV and different system sensitivities and spatial resolutions. We calculated the mean and standard deviation of positron activity range (AR) from reconstructed PET images, with respect to different data acquisition times (from 5 sec to 300 sec with 5-sec step). We also developed a technique, “Smoothed Maximum Value (SMV)”, to improve AR measurement under a given dose. Furthermore, we simulated a human brain irradiated by a 110-MeV proton beam of 50-mm diameter with 0.3-Gy dose at Bragg peak and imaged by the above PET system with 40% system sensitivity at the center of FOV and 1.7-mm spatial resolution. Results: MC Simulations on the PMMA phantom showed that, regardless of PET system sensitivities and spatial resolutions, the accuracy and precision of AR were proportional to the reciprocal of the square root of image count if image smoothing was not applied. With image smoothing or SMV method, the accuracy and precision could be substantially improved. For a cylindrical PMMA phantom (200 mm diameter and 290 mm long), the accuracy and precision of AR measurement could reach 1.0 and 1.7 mm, with 100-sec data acquired by the brain PET. The study with a human brain showed it was feasible to achieve sub-millimeter accuracy and precision of AR measurement with acquisition time within 60 sec. Conclusion: This study established the relationship between count statistics and the accuracy and precision of activity-range verification. It showed the feasibility of clinical on-line BR verification with high-performance PET systems and improved AR measurement techniques. Cancer Prevention and Research Institute of Texas grant RP120326, NIH grant R21CA187717, The Cancer Center Support (Core) Grant CA016672

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

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

Online pretreatment verification of high-dose rate brachytherapy using an imaging panel

Science.gov (United States)

Fonseca, Gabriel P.; Podesta, Mark; Bellezzo, Murillo; Van den Bosch, Michiel R.; Lutgens, Ludy; Vanneste, Ben G. L.; Voncken, Robert; Van Limbergen, Evert J.; Reniers, Brigitte; Verhaegen, Frank

2017-07-01

Brachytherapy is employed to treat a wide variety of cancers. However, an accurate treatment verification method is currently not available. This study describes a pre-treatment verification system that uses an imaging panel (IP) to verify important aspects of the treatment plan. A detailed modelling of the IP was only possible with an extensive calibration performed using a robotic arm. Irradiations were performed with a high dose rate (HDR) 192Ir source within a water phantom. An empirical fit was applied to measure the distance between the source and the detector so 3D Cartesian coordinates of the dwell positions can be obtained using a single panel. The IP acquires 7.14 fps to verify the dwell times, dwell positions and air kerma strength (Sk). A gynecological applicator was used to create a treatment plan that was registered with a CT image of the water phantom used during the experiments for verification purposes. Errors (shifts, exchanged connections and wrong dwell times) were simulated to verify the proposed verification system. Cartesian source positions (panel measurement plane) have a standard deviation of about 0.02 cm. The measured distance between the source and the panel (z-coordinate) have a standard deviation up to 0.16 cm and maximum absolute error of  ≈0.6 cm if the signal is close to sensitive limit of the panel. The average response of the panel is very linear with Sk. Therefore, Sk measurements can be performed with relatively small errors. The measured dwell times show a maximum error of 0.2 s which is consistent with the acquisition rate of the panel. All simulated errors were clearly identified by the proposed system. The use of IPs is not common in brachytherapy, however, it provides considerable advantages. It was demonstrated that the IP can accurately measure Sk, dwell times and dwell positions.

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.

Optimization and verification of image reconstruction for a Compton camera towards application as an on-line monitor for particle therapy

Science.gov (United States)

Taya, T.; Kataoka, J.; Kishimoto, A.; Tagawa, L.; Mochizuki, S.; Toshito, T.; Kimura, M.; Nagao, Y.; Kurita, K.; Yamaguchi, M.; Kawachi, N.

2017-07-01

Particle therapy is an advanced cancer therapy that uses a feature known as the Bragg peak, in which particle beams suddenly lose their energy near the end of their range. The Bragg peak enables particle beams to damage tumors effectively. To achieve precise therapy, the demand for accurate and quantitative imaging of the beam irradiation region or dosage during therapy has increased. The most common method of particle range verification is imaging of annihilation gamma rays by positron emission tomography. Not only 511-keV gamma rays but also prompt gamma rays are generated during therapy; therefore, the Compton camera is expected to be used as an on-line monitor for particle therapy, as it can image these gamma rays in real time. Proton therapy, one of the most common particle therapies, uses a proton beam of approximately 200 MeV, which has a range of ~ 25 cm in water. As gamma rays are emitted along the path of the proton beam, quantitative evaluation of the reconstructed images of diffuse sources becomes crucial, but it is far from being fully developed for Compton camera imaging at present. In this study, we first quantitatively evaluated reconstructed Compton camera images of uniformly distributed diffuse sources, and then confirmed that our Compton camera obtained 3 %(1 σ) and 5 %(1 σ) uniformity for line and plane sources, respectively. Based on this quantitative study, we demonstrated on-line gamma imaging during proton irradiation. Through these studies, we show that the Compton camera is suitable for future use as an on-line monitor for particle therapy.

Investigation of the spatial resolution of an online dose verification device

International Nuclear Information System (INIS)

Asuni, G.; Rickey, D. W.; McCurdy, B. M. C.

2012-01-01

Purpose: The aim of this work is to characterize a new online dose verification device, COMPASS transmission detector array (IBA Dosimetry, Schwarzenbruck, Germany). The array is composed of 1600 cylindrical ionization chambers of 3.8 mm diameter, separated by 6.5 mm center-to-center spacing, in a 40 x 40 arrangement. Methods: The line spread function (LSF) of a single ion chamber in the detector was measured with a narrow slit collimator for a 6 MV photon beam. The 0.25 x 10 mm 2 slit was formed by two machined lead blocks. The LSF was obtained by laterally translating the detector in 0.25 mm steps underneath the slit over a range of 24 mm and taking a measurement at each step. This measurement was validated with Monte Carlo simulation using BEAMnrc and DOSXYZnrc. The presampling modulation transfer function (MTF), the Fourier transform of the line spread function, was determined and compared to calculated (Monte Carlo and analytical) MTFs. Two head-and-neck intensity modulated radiation therapy (IMRT) fields were measured using the device and were used to validate the LSF measurement. These fields were simulated with the BEAMnrc Monte Carlo model, and the Monte Carlo generated incident fluence was convolved with the 2D detector response function (derived from the measured LSF) to obtain calculated dose. The measured and calculated dose distributions were then quantitatively compared using χ-comparison criteria of 3% dose difference and 3 mm distance-to-agreement for in-field points (defined as those above the 10% maximum dose threshold). Results: The full width at half-maximum (FWHM) of the measured detector response for a single chamber is 4.3 mm, which is comparable to the chamber diameter of 3.8 mm. The pre-sampling MTF was calculated, and the resolution of one chamber was estimated as 0.25 lp/mm from the first zero crossing. For both examined IMRT fields, the χ-comparison between measured and calculated data show good agreement with 95.1% and 96.3% of in

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

Examining the examiners: an online eyebrow verification experiment inspired by FISWG

NARCIS (Netherlands)

Zeinstra, Christopher Gerard; Veldhuis, Raymond N.J.; Spreeuwers, Lieuwe Jan

2015-01-01

In forensic face comparison, one of the features taken into account are the eyebrows. In this paper, we investigate human performance on an eyebrow verification task. This task is executed twice by participants: a "best-effort" approach and an approach using features based on forensic knowledge. The

Time Series Based for Online Signature Verification

Directory of Open Access Journals (Sweden)

I Ketut Gede Darma Putra

2013-11-01

Full Text Available Signature verification system is to match the tested signature with a claimed signature. This paper proposes time series based for feature extraction method and dynamic time warping for match method. The system made by process of testing 900 signatures belong to 50 participants, 3 signatures for reference and 5 signatures from original user, simple imposters and trained imposters for signatures test. The final result system was tested with 50 participants with 3 references. This test obtained that system accuracy without imposters is 90,44897959% at threshold 44 with rejection errors (FNMR is 5,2% and acceptance errors (FMR is 4,35102%, when with imposters system accuracy is 80,1361% at threshold 27 with error rejection (FNMR is 15,6% and acceptance errors (average FMR is 4,263946%, with details as follows: acceptance errors is 0,391837%, acceptance errors simple imposters is 3,2% and acceptance errors trained imposters is 9,2%.

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)

TRACEABILITY OF PRECISION MEASUREMENTS ON COORDINATE MEASURING MACHINES – PERFORMANCE VERIFICATION OF CMMs

DEFF Research Database (Denmark)

De Chiffre, Leonardo; Sobiecki, René; Tosello, Guido

This document is used in connection with one exercise of 30 minutes duration as a part of the course VISION ONLINE – One week course on Precision & Nanometrology. The exercise concerns performance verification of the volumetric measuring capability of a small volume coordinate measuring machine...

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

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.

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.

Societal Verification: Intellectual Game or International Game-Changer

International Nuclear Information System (INIS)

Hartigan, Kelsey; Hinderstein, Corey

2013-01-01

Within the nuclear nonproliferation and arms control field, there is an increasing appreciation for the potential of open source information technologies to supplement existing verification and compliance regimes. While clearly not a substitute for on-site inspections or national technical means, it may be possible to better leverage information gleaned from commercial satellite imagery, international trade records and the vast amount of data being exchanged online and between publics (including social media) so as to develop a more comprehensive set of tools and practices for monitoring and verifying a state’s nuclear activities and helping judge compliance with international obligations. The next generation “toolkit” for monitoring and verifying items, facility operations and activities will likely include a more diverse set of analytical tools and technologies than are currently used internationally. To explore these and other issues, the Nuclear Threat Initiative has launched an effort that examines, in part, the role that emerging technologies and “citizen scientists” might play in future verification regimes. This paper will include an assessment of past proliferation and security “events” and whether emerging tools and technologies would have provided indicators concurrently or in advance of these actions. Such case studies will be instrumental in understanding the reliability of these technologies and practices and in thinking through the requirements of a 21st century verification regime. Keywords: Verification, social media, open-source information, arms control, disarmament.

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.

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.

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

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

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...

Development of a Compton camera for online ion beam range verification via prompt γ detection. Session: HK 12.6 Mo 18:30

Energy Technology Data Exchange (ETDEWEB)

Aldawood, S. [LMU Munich, Garching (Germany); King Saud University, Riyadh (Saudi Arabia); Liprandi, S.; Marinsek, T.; Bortfeldt, J.; Lang, C.; Lutter, R.; Dedes, G.; Parodi, K.; Thirolf, P.G. [LMU Munich, Garching (Germany); Maier, L.; Gernhaeuser, R. [TU Munich, Garching (Germany); Kolff, H. van der; Schaart, D. [TU Delft (Netherlands); Castelhano, I. [University of Lisbon, Lisbon (Portugal)

2015-07-01

A real-time ion beam verification in hadron-therapy is playing a major role in cancer treatment evaluation. This will make the treatment interuption possible if the planned and actual ion range are mismatched. An imaging system is being developed in Garching aiming to detect prompt γ rays induced by nuclear reactions between the ion beam and biological tissue. The Compton camera prototype consists of a stack of six customized double-sided Si-strip detectors (DSSSD, 50 x 50 mm{sup 2}, 128 strips/side) acting as scatterer, while the absorber is formed by a monolithic LaBr{sub 3}:Ce scintillator crystal (50 x 50 x 30 mm{sup 3}) read out by a position-sensitive multi-anode photomultiplier (Hamamatsu H9500). The study of the Compton camera properties and its individual component are in progress both in the laboratory as well as at the online facilities.

A Scala DSL for RETE-Based Runtime Verification

Science.gov (United States)

Havelund, Klaus

2013-01-01

Runtime verification (RV) consists in part of checking execution traces against formalized specifications. Several systems have emerged, most of which support specification notations based on state machines, regular expressions, temporal logic, or grammars. The field of Artificial Intelligence (AI) has for an even longer period of time studied rule-based production systems, which at a closer look appear to be relevant for RV, although seemingly focused on slightly different application domains, such as for example business processes and expert systems. The core algorithm in many of these systems is the Rete algorithm. We have implemented a Rete-based runtime verification system, named LogFire (originally intended for offline log analysis but also applicable to online analysis), as an internal DSL in the Scala programming language, using Scala's support for defining DSLs. This combination appears attractive from a practical point of view. Our contribution is in part conceptual in arguing that such rule-based frameworks originating from AI may be suited for RV.

On-power verification of the dynamic response of self-powered in-core detectors

International Nuclear Information System (INIS)

Serdula, K.; Beaudet, M.

1996-01-01

Self-powered in-core detectors are used for on-line safety and regulation purposes in CANDU reactors. Such applications require use of detectors whose response is primarily prompt to changes in flux. In-service verification of the detectors' response is required to ensure significant degradation in performance has not occurred during long-term operation. Changes in the detector characteristics occur due to nuclear interactions and failures. Present verification requires significant station resources and disrupts power production. Use of the 'noise' in the detector signal is being investigated as an alternative to assess the dynamic response of the detectors during long-term operation. Measurements of reference 'signatures' were obtained from replacement shutdown system detectors. Results show 'noise' measurements are a promising alternative to the current verification method. Identification of changes in the detector response function assist in accurate diagnosis and prognosis of changes in detector signals due to process changes. (author)

Availability of prescription drugs for bipolar disorder at online pharmacies.

Science.gov (United States)

Monteith, Scott; Glenn, Tasha; Bauer, Rita; Conell, Jörn; Bauer, Michael

2016-03-15

There is increasing use of online pharmacies to purchase prescription drugs. While some online pharmacies are legitimate and safe, there are many unsafe and illegal so-called "rogue" online pharmacies. This study investigated the availability of psychotropic drugs online to consumers in the US, using 5 commonly prescribed drugs for bipolar disorder. Using the search term "buy [drug name]" in the Google, Yahoo and Bing search engines, the characteristics of the online pharmacies found on the first two pages of search results were investigated. The availability of the requested dosage and formulations of two brand (Seroquel XR, Abilify) and three generic drugs (lamotrigine, lithium carbonate and bupropion SR) were determined. Of 30 online pharmacies found, 17 (57%) were rated as rogue by LegitScript. Of the 30 pharmacies, 15 (50%) require a prescription, 21 (70%) claim to be from Canada, with 20 of these having a Canadian International Pharmacy association (CIPA) seal on the website. Only 13 of the 20 sites with a CIPA seal were active CIPA members. There were about the same number of trust verification seals on the rogue and legitimate pharmacy sites. Some rogue pharmacies are professional in appearance, and may be difficult for consumers to recognize as rogue. All five brand and generic drugs were offered for sale online, with or without a prescription. However, many substitutions were presented such as different strengths and formulations including products not approved by the FDA. No evaluation of product quality, packaging or purchasing. Psychotropic medications are available online with or without a prescription. The majority of online pharmacy websites were rogue. Physicians should ask about the use of online pharmacies. For those who choose to use online pharmacies, two measures to detect rogue pharmacies are recommended: (1) only purchase drugs from pharmacies that require a prescription, and (2) check all pharmacy verification seals directly on the website

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

Opt-Out Parental Consent in Online Surveys: Ethical Considerations.

Science.gov (United States)

Harris, Jane; Porcellato, Lorna

2018-07-01

This article aims to foster discussion and debate around seeking parental consent from young people recruited online. The growth of social media, particularly for young people, has led to increased interest in young people's online activities as both a research topic and recruitment setting. In a health-related study, which sought to recruit young people aged 13 to 18 years old from YouTuber fan communities to an online survey, the question arose of how parental consent could be sought from young people below 16 when no link existed between researcher and parents/guardians. A practical strategy is proposed which combines novel communication methods for participant information, opt-out online consent and age verification to address this issue. Strengths and limitations of these approaches are discussed.

Advanced verification topics

CERN Document Server

Bhattacharya, Bishnupriya; Hall, Gary; Heaton, Nick; Kashai, Yaron; Khan Neyaz; Kirshenbaum, Zeev; Shneydor, Efrat

2011-01-01

The Accellera Universal Verification Methodology (UVM) standard is architected to scale, but verification is growing and in more than just the digital design dimension. It is growing in the SoC dimension to include low-power and mixed-signal and the system integration dimension to include multi-language support and acceleration. These items and others all contribute to the quality of the SOC so the Metric-Driven Verification (MDV) methodology is needed to unify it all into a coherent verification plan. This book is for verification engineers and managers familiar with the UVM and the benefits it brings to digital verification but who also need to tackle specialized tasks. It is also written for the SoC project manager that is tasked with building an efficient worldwide team. While the task continues to become more complex, Advanced Verification Topics describes methodologies outside of the Accellera UVM standard, but that build on it, to provide a way for SoC teams to stay productive and profitable.

Re-evaluating journalistic routines in a digital age: A review of research on the use of online sources

NARCIS (Netherlands)

Lecheler, S.; Kruikemeier, S.

This review article provides a critical discussion of empirical studies that deal with the use of online news sources in journalism. We evaluate how online sources have changed the journalist–source relationship regarding selection of sources as well as verification strategies. We also discuss how

Quantitative evaluation of patient-specific quality assurance using online dosimetry system

Science.gov (United States)

Jung, Jae-Yong; Shin, Young-Ju; Sohn, Seung-Chang; Min, Jung-Whan; Kim, Yon-Lae; Kim, Dong-Su; Choe, Bo-Young; Suh, Tae-Suk

2018-01-01

In this study, we investigated the clinical performance of an online dosimetry system (Mobius FX system, MFX) by 1) dosimetric plan verification using gamma passing rates and dose volume metrics and 2) error-detection capability evaluation by deliberately introduced machine error. Eighteen volumetric modulated arc therapy (VMAT) plans were studied. To evaluate the clinical performance of the MFX, we used gamma analysis and dose volume histogram (DVH) analysis. In addition, to evaluate the error-detection capability, we used gamma analysis and DVH analysis utilizing three types of deliberately introduced errors (Type 1: gantry angle-independent multi-leaf collimator (MLC) error, Type 2: gantry angle-dependent MLC error, and Type 3: gantry angle error). A dosimetric verification comparison of physical dosimetry system (Delt4PT) and online dosimetry system (MFX), gamma passing rates of the two dosimetry systems showed very good agreement with treatment planning system (TPS) calculation. For the average dose difference between the TPS calculation and the MFX measurement, most of the dose metrics showed good agreement within a tolerance of 3%. For the error-detection comparison of Delta4PT and MFX, the gamma passing rates of the two dosimetry systems did not meet the 90% acceptance criterion with the magnitude of error exceeding 2 mm and 1.5 ◦, respectively, for error plans of Types 1, 2, and 3. For delivery with all error types, the average dose difference of PTV due to error magnitude showed good agreement between calculated TPS and measured MFX within 1%. Overall, the results of the online dosimetry system showed very good agreement with those of the physical dosimetry system. Our results suggest that a log file-based online dosimetry system is a very suitable verification tool for accurate and efficient clinical routines for patient-specific quality assurance (QA).

Prostate Dose Escalation by a Innovative Inverse Planning-Driven IMRT

National Research Council Canada - National Science Library

Xing, Lei

2008-01-01

...) Developed a voxel-specific penalty scheme for TRV-based inverse planning; (iv) Established a cine-EPID image retrospective dose reconstruction in IMRT dose delivery for adaptive planning and IMRT dose verification. These works are both timely and important and should lead to widespread impact on prostate cancer management.

Establishment of action levels for quality control of IMRT flat panel: experience with the algorithm iGRiMLO

International Nuclear Information System (INIS)

Gonzalez, V.; Dolores, VV. de los; Pastor, V.; Martinez, J.; Gimeno, J.; Guardino, C.; Crispin, V.

2011-01-01

Algorithm has been used at our institution iGRiMLO scheduled for individual verification of treatment plans for intensity modulated radiotherapy (IMRT) step and shoot through portal dosimetry pretreatment of non-transmission, triggering the plan directly to a portal imaging device (EPID) of an amorphous silicon flat panel.

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 ...

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

SU-F-J-199: Predictive Models for Cone Beam CT-Based Online Verification of Pencil Beam Scanning Proton Therapy

Energy Technology Data Exchange (ETDEWEB)

Yin, L; Lin, A; Ahn, P; Solberg, T; McDonough, J; Teo, B [The Hospital of the University of Pennsylvania, Philadelphia, PA (United States); Janssens, G [IBA, Louvain-la-neuve (Belgium)

2016-06-15

Purpose: To utilize online CBCT scans to develop models for predicting DVH metrics in proton therapy of head and neck tumors. Methods: Nine patients with locally advanced oropharyngeal cancer were retrospectively selected in this study. Deformable image registration was applied to the simulation CT, target volumes, and organs at risk (OARs) contours onto each weekly CBCT scan. Intensity modulated proton therapy (IMPT) treatment plans were created on the simulation CT and forward calculated onto each corrected CBCT scan. Thirty six potentially predictive metrics were extracted from each corrected CBCT. These features include minimum/maximum/mean over and under-ranges at the proximal and distal surface of PTV volumes, and geometrical and water equivalent distance between PTV and each OARs. Principal component analysis (PCA) was used to reduce the dimension of the extracted features. Three principal components were found to account for over 90% of variances in those features. Datasets from eight patients were used to train a machine learning model to fit these principal components with DVH metrics (dose to 95% and 5% of PTV, mean dose or max dose to OARs) from the forward calculated dose on each corrected CBCT. The accuracy of this model was verified on the datasets from the 9th patient. Results: The predicted changes of DVH metrics from the model were in good agreement with actual values calculated on corrected CBCT images. Median differences were within 1 Gy for most DVH metrics except for larynx and constrictor mean dose. However, a large spread of the differences was observed, indicating additional training datasets and predictive features are needed to improve the model. Conclusion: Intensity corrected CBCT scans hold the potential to be used for online verification of proton therapy and prediction of delivered dose distributions.

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.

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)

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.

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...

A multi-professional software tool for radiation therapy treatment verification

International Nuclear Information System (INIS)

Fox, Tim; Brooks, Ken; Davis, Larry

1996-01-01

Purpose: Verification of patient setup is important in conformal therapy because it provides a means of quality assurance for treatment delivery. Electronic portal imaging systems have led to software tools for performing digital comparison and verification of patient setup. However, these software tools are typically designed from a radiation oncologist's perspective even though treatment verification is a team effort involving oncologists, physicists, and therapists. A new software tool, Treatment Verification Tool (TVT), has been developed as an interactive, multi-professional application for reviewing and verifying treatment plan setup using conventional personal computers. This study will describe our approach to electronic treatment verification and demonstrate the features of TVT. Methods and Materials: TVT is an object-oriented software tool written in C++ using the PC-based Windows NT environment. The software utilizes the selection of a patient's images from a database. The software is also developed as a single window interface to reduce the amount of windows presented to the user. However, the user can select from four different possible views of the patient data. One of the views is side-by-side comparison of portal images (on-line portal images or digitized port film) with a prescription image (digitized simulator film or digitally reconstructed radiograph), and another view is a textual summary of the grades of each portal image. The grades of a portal image are assigned by a radiation oncologist using an evaluation method, and the physicists and therapists may only review these results. All users of TVT can perform image enhancement processes, measure distances, and perform semi-automated registration methods. An electronic dialogue can be established through a set of annotations and notes among the radiation oncologists and the technical staff. Results: Features of TVT include: 1) side-by-side comparison of portal images and a prescription image; 2

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

Introduction to IGRT and additional components

International Nuclear Information System (INIS)

Mijnheer, Ben

2008-01-01

Image-guided radiation therapy is 'Any use of planar imaging, volumetric imaging or volumetric cine imaging, marker localization, marker tracking, patient surface imaging or patient surface tracking to improve the precision of radiation-therapy delivery' , or 'Frequent imaging in the treatment room during a course of radiotherapy to guide the treatment process'. Purpose: To verify if the correct volume in a patient is irradiated by imaging the target and/or healthy tissue prior to or during treatment. Imaging modalities include: Electronic Portal Imaging Devices (EPIDs); (Portal) imaging of implanted markers; Imaging of external markers; Ultrasound; X-ray fluoroscopy; and CT (MR) scanner in treatment room. Final remarks are as follows: The introduction of various IGRT techniques allowed 3D verification of the position of target volumes and organs at risk just before or during treatment. Because the information is in 3D, or sometimes even in 4D, in principle these IGRT approaches provide more information compared to the use of 2D verification methods (e.g. EPIDs). Clinical data are becoming available to assess quantitatively for which treatment techniques IGRT approaches are advantageous compared to the use of conventional verification methods taking the additional resources (time, money, manpower) into account. (P.A.)

Multilateral disarmament verification

International Nuclear Information System (INIS)

Persbo, A.

2013-01-01

Non-governmental organisations, such as VERTIC (Verification Research, Training and Information Centre), can play an important role in the promotion of multilateral verification. Parties involved in negotiating nuclear arms accords are for the most part keen that such agreements include suitable and robust provisions for monitoring and verification. Generally progress in multilateral arms control verification is often painstakingly slow, but from time to time 'windows of opportunity' - that is, moments where ideas, technical feasibility and political interests are aligned at both domestic and international levels - may occur and we have to be ready, so the preparatory work is very important. In the context of nuclear disarmament, verification (whether bilateral or multilateral) entails an array of challenges, hurdles and potential pitfalls relating to national security, health, safety and even non-proliferation, so preparatory work is complex and time-greedy. A UK-Norway Initiative was established in order to investigate the role that a non-nuclear-weapon state such as Norway could potentially play in the field of nuclear arms control verification. (A.C.)

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)

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

Embedded software verification and debugging

CERN Document Server

Winterholer, Markus

2017-01-01

This book provides comprehensive coverage of verification and debugging techniques for embedded software, which is frequently used in safety critical applications (e.g., automotive), where failures are unacceptable. Since the verification of complex systems needs to encompass the verification of both hardware and embedded software modules, this book focuses on verification and debugging approaches for embedded software with hardware dependencies. Coverage includes the entire flow of design, verification and debugging of embedded software and all key approaches to debugging, dynamic, static, and hybrid verification. This book discusses the current, industrial embedded software verification flow, as well as emerging trends with focus on formal and hybrid verification and debugging approaches. Includes in a single source the entire flow of design, verification and debugging of embedded software; Addresses the main techniques that are currently being used in the industry for assuring the quality of embedded softw...

Software verification for nuclear industry

International Nuclear Information System (INIS)

Wilburn, N.P.

1985-08-01

Why verification of software products throughout the software life cycle is necessary is considered. Concepts of verification, software verification planning, and some verification methodologies for products generated throughout the software life cycle are then discussed

The design of verification regimes

International Nuclear Information System (INIS)

Gallagher, N.W.

1991-01-01

Verification of a nuclear agreement requires more than knowledge of relevant technologies and institutional arrangements. It also demands thorough understanding of the nature of verification and the politics of verification design. Arms control efforts have been stymied in the past because key players agreed to verification in principle, only to disagree radically over verification in practice. In this chapter, it is shown that the success and stability of arms control endeavors can be undermined by verification designs which promote unilateral rather than cooperative approaches to security, and which may reduce, rather than enhance, the security of both sides. Drawing on logical analysis and practical lessons from previous superpower verification experience, this chapter summarizes the logic and politics of verification and suggests implications for South Asia. The discussion begins by determining what properties all forms of verification have in common, regardless of the participants or the substance and form of their agreement. Viewing verification as the political process of making decisions regarding the occurrence of cooperation points to four critical components: (1) determination of principles, (2) information gathering, (3) analysis and (4) projection. It is shown that verification arrangements differ primarily in regards to how effectively and by whom these four stages are carried out

On-line monitoring of water amount in fresh concrete by radioactive-wave method

International Nuclear Information System (INIS)

Kemi, T.; Arai, M.; Enomoto, S.; Suzki, K.; Kumahara, Y.

2003-01-01

The committee on nondestructive inspection for steel reinforced concrete structures in the Federation of Construction Materials Industries, Japan has published a proposed standard for on-line monitoring of water amount in fresh concrete by the radioactive wave method. By applying a neutron technique, water amount in fresh concrete is estimated continuously from the energy consumption of neutron due to hydrogen. A standard is discussed along with results of verification tests. Thus, on-line monitoring for water amount is proposed

Improved verification methods for safeguards verifications at enrichment plants

International Nuclear Information System (INIS)

Lebrun, A.; Kane, S. C.; Bourva, L.; Poirier, S.; Loghin, N. E.; Langlands, D.

2009-01-01

The International Atomic Energy Agency (IAEA) has initiated a coordinated research and development programme to improve its verification methods and equipment applicable to enrichment plants. The programme entails several individual projects to meet the objectives of the IAEA Safeguards Model Approach for Gas Centrifuge Enrichment Plants updated in 2006. Upgrades of verification methods to confirm the absence of HEU (highly enriched uranium) production have been initiated and, in particular, the Cascade Header Enrichment Monitor (CHEM) has been redesigned to reduce its weight and incorporate an electrically cooled germanium detector. Such detectors are also introduced to improve the attended verification of UF 6 cylinders for the verification of the material balance. Data sharing of authenticated operator weighing systems such as accountancy scales and process load cells is also investigated as a cost efficient and an effective safeguards measure combined with unannounced inspections, surveillance and non-destructive assay (NDA) measurement. (authors)

Improved verification methods for safeguards verifications at enrichment plants

Energy Technology Data Exchange (ETDEWEB)

Lebrun, A.; Kane, S. C.; Bourva, L.; Poirier, S.; Loghin, N. E.; Langlands, D. [Department of Safeguards, International Atomic Energy Agency, Wagramer Strasse 5, A1400 Vienna (Austria)

2009-07-01

The International Atomic Energy Agency (IAEA) has initiated a coordinated research and development programme to improve its verification methods and equipment applicable to enrichment plants. The programme entails several individual projects to meet the objectives of the IAEA Safeguards Model Approach for Gas Centrifuge Enrichment Plants updated in 2006. Upgrades of verification methods to confirm the absence of HEU (highly enriched uranium) production have been initiated and, in particular, the Cascade Header Enrichment Monitor (CHEM) has been redesigned to reduce its weight and incorporate an electrically cooled germanium detector. Such detectors are also introduced to improve the attended verification of UF{sub 6} cylinders for the verification of the material balance. Data sharing of authenticated operator weighing systems such as accountancy scales and process load cells is also investigated as a cost efficient and an effective safeguards measure combined with unannounced inspections, surveillance and non-destructive assay (NDA) measurement. (authors)

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

Online Signature Verification on MOBISIG Finger-Drawn Signature Corpus

Directory of Open Access Journals (Sweden)

Margit Antal

2018-01-01

Full Text Available We present MOBISIG, a pseudosignature dataset containing finger-drawn signatures from 83 users captured with a capacitive touchscreen-based mobile device. The database was captured in three sessions resulting in 45 genuine signatures and 20 skilled forgeries for each user. The database was evaluated by two state-of-the-art methods: a function-based system using local features and a feature-based system using global features. Two types of equal error rate computations are performed: one using a global threshold and the other using user-specific thresholds. The lowest equal error rate was 0.01% against random forgeries and 5.81% against skilled forgeries using user-specific thresholds that were computed a posteriori. However, these equal error rates were significantly raised to 1.68% (random forgeries case and 14.31% (skilled forgeries case using global thresholds. The same evaluation protocol was performed on the DooDB publicly available dataset. Besides verification performance evaluations conducted on the two finger-drawn datasets, we evaluated the quality of the samples and the users of the two datasets using basic quality measures. The results show that finger-drawn signatures can be used by biometric systems with reasonable accuracy.

Physics Verification Overview

Energy Technology Data Exchange (ETDEWEB)

Doebling, Scott William [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2017-09-12

The purpose of the verification project is to establish, through rigorous convergence analysis, that each ASC computational physics code correctly implements a set of physics models and algorithms (code verification); Evaluate and analyze the uncertainties of code outputs associated with the choice of temporal and spatial discretization (solution or calculation verification); and Develop and maintain the capability to expand and update these analyses on demand. This presentation describes project milestones.

Game Theory Models for the Verification of the Collective Behaviour of Autonomous Cars

OpenAIRE

Varga, László Z.

2017-01-01

The collective of autonomous cars is expected to generate almost optimal traffic. In this position paper we discuss the multi-agent models and the verification results of the collective behaviour of autonomous cars. We argue that non-cooperative autonomous adaptation cannot guarantee optimal behaviour. The conjecture is that intention aware adaptation with a constraint on simultaneous decision making has the potential to avoid unwanted behaviour. The online routing game model is expected to b...

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

Free and Reduced-Price Meal Application and Income Verification Practices in School Nutrition Programs in the United States

Science.gov (United States)

Kwon, Junehee; Lee, Yee Ming; Park, Eunhye; Wang, Yujia; Rushing, Keith

2017-01-01

Purpose/Objectives: This study assessed current practices and attitudes of school nutrition program (SNP) management staff regarding free and reduced-price (F-RP) meal application and verification in SNPs. Methods: Stratified, randomly selected 1,500 SNP management staff in 14 states received a link to an online questionnaire and/or a printed…

An automated portal verification system for the tangential breast portal field

International Nuclear Information System (INIS)

Yin, F.-F.; Lai, W.; Chen, C. W.; Nelson, D. F.

1995-01-01

Purpose/Objective: In order to ensure the treatment is delivered as planned, a portal image is acquired in the accelerator and is compared to the reference image. At present, this comparison is performed by radiation oncologists based on the manually-identified features, which is both time-consuming and potentially error-prone. With the introduction of various electronic portal imaging devices, real-time patient positioning correction is becoming clinically feasible to replace time-delayed analysis using films. However, this procedure requires present of radiation oncologists during patient treatment which is not cost-effective and practically not realistic. Therefore, the efficiency and quality of radiation therapy could be substantially improved if this procedure can be automated. The purpose of this study is to develop a fully computerized verification system for the radiation therapy of breast cancer for which a similar treatment setup is generally employed. Materials/Methods: The automated verification system involves image acquisition, image feature extraction, feature correlation between reference and portal images, and quantitative evaluation of patient setup. In this study, a matrix liquid ion-chamber EPID was used to acquire digital portal images which is directly attached to Varian CL2100C accelerator. For effective use of computation memory, the 12-bit gray levels in original portal images were quantized to form a range of 8-bit gray levels. A typical breast portal image includes three important components: breast and lung tissues in the treatment field, air space within the treatment field, and non-irradiated region. A hierarchical region processing technique was developed to separate these regions sequentially. The inherent hierarchical features were formulated based on different radiation attenuation for different regions as: treatment field edge -- breast skin line -- chest wall. Initially, a combination of a Canny edge detector and a constrained

The verification of ethnographic data.

Science.gov (United States)

Pool, Robert

2017-09-01

Anthropologists are increasingly required to account for the data on which they base their interpretations and to make it available for public scrutiny and re-analysis. While this may seem straightforward (why not place our data in online repositories?), it is not. Ethnographic 'data' may consist of everything from verbatim transcripts ('hard data') to memories and impressions ('soft data'). Hard data can be archived and re-analysed; soft data cannot. The focus on hard 'objective' data contributes to the delegitimizing of the soft data that are essential for ethnographic understanding, and without which hard data cannot be properly interpreted. However, the credibility of ethnographic interpretation requires the possibility of verification. This could be achieved by obligatory, standardised forms of personal storage with the option for audit if required, and by being more explicit in publications about the nature and status of the data and the process of interpretation.

FMCT verification: Case studies

International Nuclear Information System (INIS)

Hui Zhang

2001-01-01

Full text: How to manage the trade-off between the need for transparency and the concern about the disclosure of sensitive information would be a key issue during the negotiations of FMCT verification provision. This paper will explore the general concerns on FMCT verification; and demonstrate what verification measures might be applied to those reprocessing and enrichment plants. A primary goal of an FMCT will be to have the five declared nuclear weapon states and the three that operate unsafeguarded nuclear facilities become parties. One focus in negotiating the FMCT will be verification. Appropriate verification measures should be applied in each case. Most importantly, FMCT verification would focus, in the first instance, on these states' fissile material production facilities. After the FMCT enters into force, all these facilities should be declared. Some would continue operating to produce civil nuclear power or to produce fissile material for non- explosive military uses. The verification measures necessary for these operating facilities would be essentially IAEA safeguards, as currently being applied to non-nuclear weapon states under the NPT. However, some production facilities would be declared and shut down. Thus, one important task of the FMCT verifications will be to confirm the status of these closed facilities. As case studies, this paper will focus on the verification of those shutdown facilities. The FMCT verification system for former military facilities would have to differ in some ways from traditional IAEA safeguards. For example, there could be concerns about the potential loss of sensitive information at these facilities or at collocated facilities. Eventually, some safeguards measures such as environmental sampling might be seen as too intrusive. Thus, effective but less intrusive verification measures may be needed. Some sensitive nuclear facilities would be subject for the first time to international inspections, which could raise concerns

An investigation into the use of CMOS active pixel technology in image-guided radiotherapy

International Nuclear Information System (INIS)

Osmond, J P F; Holland, A D; Harris, E J; Ott, R J; Evans, P M; Clark, A T

2008-01-01

The increased intelligence, read-out speed, radiation hardness and potential large size of CMOS active pixel sensors (APS) gives them a potential advantage over systems currently used for verification of complex treatments such as IMRT and the tracking of moving tumours. The aim of this work is to investigate the feasibility of using an APS-based system to image the megavoltage treatment beam produced by a linear accelerator (Linac), and to demonstrate the logic which may ultimately be incorporated into future sensor and FPGA design to evaluate treatment and track motion. A CMOS APS was developed by the MI 3 consortium and incorporated into a megavoltage imaging system using the standard lens and mirror configuration employed in camera-based EPIDs. The ability to resolve anatomical structure was evaluated using an Alderson RANDO head phantom, resolution evaluated using a quality control (QC3) phantom and contrast using an in-house developed phantom. A complex intensity-modulated radiotherapy (IMRT) treatment was imaged and two algorithms were used to determine the field-area and delivered dose, and the position of multi-leaf collimator (MLC) leaves off-line. Results were compared with prediction from the prescription and found to agree within a single image frame time for dose delivery and 0.02-0.03 cm for the position of collimator leaves. Such a system therefore shows potential as the basis for an on-line verification system capable of treatment verification and monitoring patient motion

Inspector measurement verification activities

International Nuclear Information System (INIS)

George, R.S.; Crouch, R.

e most difficult and complex activity facing a safeguards inspector involves the verification of measurements and the performance of the measurement system. Remeasurement is the key to measurement verification activities. Remeasurerements using the facility's measurement system provide the bulk of the data needed for determining the performance of the measurement system. Remeasurements by reference laboratories are also important for evaluation of the measurement system and determination of systematic errors. The use of these measurement verification activities in conjunction with accepted inventory verification practices provides a better basis for accepting or rejecting an inventory. (U.S.)

Verification and disarmament

Energy Technology Data Exchange (ETDEWEB)

Blix, H. [IAEA, Vienna (Austria)

1998-07-01

The main features are described of the IAEA safeguards verification system that non-nuclear weapon states parties of the NPT are obliged to accept. Verification activities/problems in Iraq and North Korea are discussed.

Verification and disarmament

International Nuclear Information System (INIS)

Blix, H.

1998-01-01

The main features are described of the IAEA safeguards verification system that non-nuclear weapon states parties of the NPT are obliged to accept. Verification activities/problems in Iraq and North Korea are discussed

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.

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...

HDL to verification logic translator

Science.gov (United States)

Gambles, J. W.; Windley, P. J.

1992-01-01

The increasingly higher number of transistors possible in VLSI circuits compounds the difficulty in insuring correct designs. As the number of possible test cases required to exhaustively simulate a circuit design explodes, a better method is required to confirm the absence of design faults. Formal verification methods provide a way to prove, using logic, that a circuit structure correctly implements its specification. Before verification is accepted by VLSI design engineers, the stand alone verification tools that are in use in the research community must be integrated with the CAD tools used by the designers. One problem facing the acceptance of formal verification into circuit design methodology is that the structural circuit descriptions used by the designers are not appropriate for verification work and those required for verification lack some of the features needed for design. We offer a solution to this dilemma: an automatic translation from the designers' HDL models into definitions for the higher-ordered logic (HOL) verification system. The translated definitions become the low level basis of circuit verification which in turn increases the designer's confidence in the correctness of higher level behavioral models.

SU-E-P-35: Real-Time Patient Transit Dose Verification of Volumetric Modulated Arc Radiotherapy by a 2D Ionization Chamber Array

Energy Technology Data Exchange (ETDEWEB)

Liu, X

2015-06-15

Purpose: To explore the real-time dose verification method in volumetric modulated arc radiotherapy (VMAT) with a 2D array ion chamber array. Methods: The 2D ion chamber array was fixed on the panel of electronic portal imaging device (EPID). Source-detector distance (SDD)was 140cm. 8mm RW3 solid water was added to the detector panel to achieve maximum readings.The patient plans for esophageal, prostate and liver cancers were selected to deliver on the cylindrical Cheese phantom 5 times in order to validate the reproducibility of doses. Real-time patient transit dose measurements were performed at each fraction. Dose distributions wereevaluated using gamma index criteria of 3mm DTA and 3% dose difference referred to the firsttime Result. Results: The gamma index pass rate in the Cheese phantom were about 98%; The gamma index pass rate for esophageal, liver and prostate cancer patient were about 92%,94%, and 92%, respectively; Gamma pass rate for all single fraction were more than 90%. Conclusion: The 2D array is capable of monitoring the real time transit doses during VMAT delivery. It is helpful to improve the treatment accuracy.

SU-C-207A-06: On-Line Beam Range Verification with Multiple Scanning Particle Beams: Initial Feasibility Study with Simulations

Energy Technology Data Exchange (ETDEWEB)

Zhong, Y; Sun, X; Lu, W; Jia, X; Wang, J; Shao, Y [The University of Texas Southwestern Medical Ctr., Dallas, TX (United States)

2016-06-15

Purpose: To investigate the feasibility and requirement for intra-fraction on-line multiple scanning particle beam range verifications (BRVs) with in-situ PET imaging, which is beyond the current single-beam BRV with extra factors that will affect the BR measurement accuracy, such as beam diameter, separation between beams, and different image counts at different BRV positions. Methods: We simulated a 110-MeV proton beam with 5-mm diameter irradiating a uniform PMMA phantom by GATE simulation, which generated nuclear interaction-induced positrons. In this preliminary study, we simply duplicated these positrons and placed them next to the initial protons to approximately mimic the two spatially separated positron distributions produced by two beams parallel to each other but with different beam ranges. These positrons were then imaged by a PET (∼2-mm resolution, 10% sensitivity, 320×320×128 mm^3 FOV) with different acquisition times. We calculated the positron activity ranges (ARs) from reconstructed PET images and compared them with the corresponding ARs of original positron distributions. Results: Without further image data processing and correction, the preliminary study show the errors between the measured and original ARs varied from 0.2 mm to 2.3 mm as center-to-center separations and range differences were in the range of 8–12 mm and 2–8 mm respectively, indicating the accuracy of AR measurement strongly depends on the beam separations and range differences. In addition, it is feasible to achieve ≤ 1.0-mm accuracy for both beams with 1-min PET acquisition and 12 mm beam separation. Conclusion: This study shows that the overlap between the positron distributions from multiple scanning beams can significantly impact the accuracy of BRVs of distributed particle beams and need to be further addressed beyond the established method of single-beam BRV, but it also indicates the feasibility to achieve accurate on-line multi-beam BRV with further improved

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

Assessment of dosimetrical performance in 11 Varian a-Si500 electronic portal imaging devices

International Nuclear Information System (INIS)

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

2008-01-01

Dosimetrical characteristics of 11 Varian a-Si-500 electronic portal imaging devices (EPIDs) in clinical use for periods ranging between 10 and 86 months were investigated for consistency of performance and portal dosimetry implications. Properties studied include short-term reproducibility, signal linearity with monitor units, response to reference beam, signal uniformity across the detector panel, signal dependence on field size, dose-rate influence, memory effects and image profiles as a function of monitor units. The EPID measurements were also compared with those of the ionization chambers' to ensure stability of the linear accelerators. Depending on their clinical installation date, the EPIDs were interfaced with one of the two different acquisition control software packages, IAS2/IDU-II or IAS3/IDU-20. Both the EPID age and image acquisition system influenced the dosimetric characteristics with the newer version (IAS3 with IDU-20) giving better data reproducibility and linearity fit than the older version (IAS2 with IDU-II). The relative signal response (uniformity) after 50 MU was better than 95% of the central value and independent of detector. Sensitivity for all EPIDs reduced continuously with increasing dose rates for the newer image acquisition software. In the dose-rate range 100-600 MU min -1 , the maximum variation in sensitivity ranged between 1 and 1.8% for different EPIDs. For memory effects, the increase in the measured signal at the centre of the irradiated field for successive images was within 1.8% and 1.0% for the older and newer acquisition systems, respectively. Image profiles acquired at a lower MU in the radial plane (gun-target) had gradients in measured pixel values of up to 25% for the older system. Detectors with software/hardware versions IAS3/IDU-20 have a high degree of accuracy and are more suitable for routine quantitative IMRT dosimetrical verification.

Model-based verification method for solving the parameter uncertainty in the train control system

International Nuclear Information System (INIS)

Cheng, Ruijun; Zhou, Jin; Chen, Dewang; Song, Yongduan

2016-01-01

This paper presents a parameter analysis method to solve the parameter uncertainty problem for hybrid system and explore the correlation of key parameters for distributed control system. For improving the reusability of control model, the proposed approach provides the support for obtaining the constraint sets of all uncertain parameters in the abstract linear hybrid automata (LHA) model when satisfying the safety requirements of the train control system. Then, in order to solve the state space explosion problem, the online verification method is proposed to monitor the operating status of high-speed trains online because of the real-time property of the train control system. Furthermore, we construct the LHA formal models of train tracking model and movement authority (MA) generation process as cases to illustrate the effectiveness and efficiency of the proposed method. In the first case, we obtain the constraint sets of uncertain parameters to avoid collision between trains. In the second case, the correlation of position report cycle and MA generation cycle is analyzed under both the normal and the abnormal condition influenced by packet-loss factor. Finally, considering stochastic characterization of time distributions and real-time feature of moving block control system, the transient probabilities of wireless communication process are obtained by stochastic time petri nets. - Highlights: • We solve the parameters uncertainty problem by using model-based method. • We acquire the parameter constraint sets by verifying linear hybrid automata models. • Online verification algorithms are designed to monitor the high-speed trains. • We analyze the correlation of key parameters and uncritical parameters. • The transient probabilities are obtained by using reliability analysis.

Exploring Marijuana Advertising on Weedmaps, a Popular Online Directory

OpenAIRE

Bierut, Tatiana; Krauss, Melissa J.; Sowles, Shaina J.; Cavazos-Rehg, Patricia A.

2017-01-01

With an increase in the legalization of recreational marijuana across the U.S., advertising for marijuana products is more widespread, especially on the Internet where such practices pose a regulatory challenge. In this study, we examined the content of marijuana advertising on Weedmaps, a popular website that markets marijuana retailers online. A total of 146 recreational marijuana retailers in Colorado and Washington were examined on Weedmaps. We studied the age verification practices made ...

Likelihood-ratio-based biometric verification

NARCIS (Netherlands)

Bazen, A.M.; Veldhuis, Raymond N.J.

2002-01-01

This paper presents results on optimal similarity measures for biometric verification based on fixed-length feature vectors. First, we show that the verification of a single user is equivalent to the detection problem, which implies that for single-user verification the likelihood ratio is optimal.

Likelihood Ratio-Based Biometric Verification

NARCIS (Netherlands)

Bazen, A.M.; Veldhuis, Raymond N.J.

The paper presents results on optimal similarity measures for biometric verification based on fixed-length feature vectors. First, we show that the verification of a single user is equivalent to the detection problem, which implies that, for single-user verification, the likelihood ratio is optimal.

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...

Validation of an online replanning technique for prostate adaptive radiotherapy

Energy Technology Data Exchange (ETDEWEB)

Peng Cheng; Chen Guangpei; Ahunbay, Ergun; Wang Dian; Lawton, Colleen; Li, X Allen, E-mail: ali@mcw.edu [Department of Radiation Oncology, Medical College of Wisconsin, Milwaukee, WI (United States)

2011-06-21

We have previously developed an online adaptive replanning technique to rapidly adapt the original plan according to daily CT. This paper reports the quality assurance (QA) developments in its clinical implementation for prostate cancer patients. A series of pre-clinical validation tests were carried out to verify the overall accuracy and consistency of the online replanning procedure. These tests include (a) phantom measurements of 22 individual patient adaptive plans to verify their accuracy and deliverability and (b) efficiency and applicability of the online replanning process. A four-step QA procedure was established to ensure the safe and accurate delivery of an adaptive plan, including (1) offline phantom measurement of the original plan, (2) online independent monitor unit (MU) calculation for a redundancy check, (3) online verification of plan-data transfer using an in-house software and (4) offline validation of actually delivered beam parameters. The pre-clinical validations demonstrate that the newly implemented online replanning technique is dosimetrically accurate and practically efficient. The four-step QA procedure is capable of identifying possible errors in the process of online adaptive radiotherapy and to ensure the safe and accurate delivery of the adaptive plans. Based on the success of this work, the online replanning technique has been used in the clinic to correct for interfractional changes during the prostate radiation therapy.

Validation of an online replanning technique for prostate adaptive radiotherapy

International Nuclear Information System (INIS)

Peng Cheng; Chen Guangpei; Ahunbay, Ergun; Wang Dian; Lawton, Colleen; Li, X Allen

2011-01-01

We have previously developed an online adaptive replanning technique to rapidly adapt the original plan according to daily CT. This paper reports the quality assurance (QA) developments in its clinical implementation for prostate cancer patients. A series of pre-clinical validation tests were carried out to verify the overall accuracy and consistency of the online replanning procedure. These tests include (a) phantom measurements of 22 individual patient adaptive plans to verify their accuracy and deliverability and (b) efficiency and applicability of the online replanning process. A four-step QA procedure was established to ensure the safe and accurate delivery of an adaptive plan, including (1) offline phantom measurement of the original plan, (2) online independent monitor unit (MU) calculation for a redundancy check, (3) online verification of plan-data transfer using an in-house software and (4) offline validation of actually delivered beam parameters. The pre-clinical validations demonstrate that the newly implemented online replanning technique is dosimetrically accurate and practically efficient. The four-step QA procedure is capable of identifying possible errors in the process of online adaptive radiotherapy and to ensure the safe and accurate delivery of the adaptive plans. Based on the success of this work, the online replanning technique has been used in the clinic to correct for interfractional changes during the prostate radiation therapy.

Scalable Techniques for Formal Verification

CERN Document Server

Ray, Sandip

2010-01-01

This book presents state-of-the-art approaches to formal verification techniques to seamlessly integrate different formal verification methods within a single logical foundation. It should benefit researchers and practitioners looking to get a broad overview of the spectrum of formal verification techniques, as well as approaches to combining such techniques within a single framework. Coverage includes a range of case studies showing how such combination is fruitful in developing a scalable verification methodology for industrial designs. This book outlines both theoretical and practical issue

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).

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

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

Content analysis of age verification, purchase and delivery methods of internet e-cigarette vendors, 2013 and 2014.

Science.gov (United States)

Williams, Rebecca S; Derrick, Jason; Liebman, Aliza Kate; LaFleur, Kevin; Ribisl, Kurt M

2018-05-01

Identify the population of internet e-cigarette vendors (IEVs) and conduct content analyses of their age verification, purchase and delivery methods in 2013 and 2014. We used multiple sources to identify IEV websites, primarily complex search algorithms scanning more than 180 million websites. In 2013, we manually screened 32 446 websites, identifying 980 IEVs, selecting the 281 most popular for content analysis. This methodology yielded 31 239 websites for screening in 2014, identifying 3096 IEVs, with 283 selected for content analysis. The proportion of vendors that sold online-only, with no retail store, dropped significantly from 2013 (74.7%) to 2014 (64.3%) (ponline age verification services (7.1% in 2013 and 8.5% in 2014), driving licences (1.8% in 2013 and 7.4% in 2014, ponline e-cigarette sales are needed, including strict age and identity verification requirements. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Can self-verification strivings fully transcend the self-other barrier? Seeking verification of ingroup identities.

Science.gov (United States)

Gómez, Angel; Seyle, D Conor; Huici, Carmen; Swann, William B

2009-12-01

Recent research has demonstrated self-verification strivings in groups, such that people strive to verify collective identities, which are personal self-views (e.g., "sensitive") associated with group membership (e.g., "women"). Such demonstrations stop short of showing that the desire for self-verification can fully transcend the self-other barrier, as in people working to verify ingroup identities (e.g., "Americans are loud") even when such identities are not self-descriptive ("I am quiet and unassuming"). Five studies focus on such ingroup verification strivings. Results indicate that people prefer to interact with individuals who verify their ingroup identities over those who enhance these identities (Experiments 1-5). Strivings for ingroup identity verification were independent of the extent to which the identities were self-descriptive but were stronger among participants who were highly invested in their ingroup identities, as reflected in high certainty of these identities (Experiments 1-4) and high identification with the group (Experiments 1-5). In addition, whereas past demonstrations of self-verification strivings have been limited to efforts to verify the content of identities (Experiments 1 to 3), the findings also show that they strive to verify the valence of their identities (i.e., the extent to which the identities are valued; Experiments 4 and 5). Self-verification strivings, rather than self-enhancement strivings, appeared to motivate participants' strivings for ingroup identity verification. Links to collective self-verification strivings and social identity theory are discussed.

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

Utterance Verification for Text-Dependent Speaker Recognition

DEFF Research Database (Denmark)

Kinnunen, Tomi; Sahidullah, Md; Kukanov, Ivan

2016-01-01

Text-dependent automatic speaker verification naturally calls for the simultaneous verification of speaker identity and spoken content. These two tasks can be achieved with automatic speaker verification (ASV) and utterance verification (UV) technologies. While both have been addressed previously...

Online beam energy measurement of Beijing electron positron collider II linear accelerator

Science.gov (United States)

Wang, S.; Iqbal, M.; Liu, R.; Chi, Y.

2016-02-01

This paper describes online beam energy measurement of Beijing Electron Positron Collider upgraded version II linear accelerator (linac) adequately. It presents the calculation formula, gives the error analysis in detail, discusses the realization in practice, and makes some verification. The method mentioned here measures the beam energy by acquiring the horizontal beam position with three beam position monitors (BPMs), which eliminates the effect of orbit fluctuation, and is much better than the one using the single BPM. The error analysis indicates that this online measurement has further potential usage such as a part of beam energy feedback system. The reliability of this method is also discussed and demonstrated in this paper.

SU-F-T-469: A Clinically Observed Discrepancy Between Image-Based and Log- Based MLC Position

Energy Technology Data Exchange (ETDEWEB)

Neal, B; Ahmed, M; Siebers, J [University of Virginia Health System, Charlottesville, VA (United States)

2016-06-15

Purpose: To present a clinical case which challenges the base assumption of log-file based QA, by showing that the actual position of a MLC leaf can suddenly deviate from its programmed and logged position by >1 mm as observed with real-time imaging. Methods: An EPID-based exit-fluence dosimetry system designed to prevent gross delivery errors was used in cine mode to capture portal images during treatment. Visual monitoring identified an anomalous MLC leaf pair gap not otherwise detected by the automatic position verification. The position of the erred leaf was measured on EPID images and log files were analyzed for the treatment in question, the prior day’s treatment, and for daily MLC test patterns acquired on those treatment days. Additional standard test patterns were used to quantify the leaf position. Results: Whereas the log file reported no difference between planned and recorded positions, image-based measurements showed the leaf to be 1.3±0.1 mm medial from the planned position. This offset was confirmed with the test pattern irradiations. Conclusion: It has been clinically observed that log-file derived leaf positions can differ from their actual positions by >1 mm, and therefore cannot be considered to be the actual leaf positions. This cautions the use of log-based methods for MLC or patient quality assurance without independent confirmation of log integrity. Frequent verification of MLC positions through independent means is a necessary precondition to trusting log file records. Intra-treatment EPID imaging provides a method to capture departures from MLC planned positions. Work was supported in part by Varian Medical Systems.

A Practitioners Perspective on Verification

Science.gov (United States)

Steenburgh, R. A.

2017-12-01

NOAAs Space Weather Prediction Center offers a wide range of products and services to meet the needs of an equally wide range of customers. A robust verification program is essential to the informed use of model guidance and other tools by both forecasters and end users alike. In this talk, we present current SWPC practices and results, and examine emerging requirements and potential approaches to satisfy them. We explore the varying verification needs of forecasters and end users, as well as the role of subjective and objective verification. Finally, we describe a vehicle used in the meteorological community to unify approaches to model verification and facilitate intercomparison.

Nuclear power plant C and I design verification by simulation

International Nuclear Information System (INIS)

Storm, Joachim; Yu, Kim; Lee, D.Y

2003-01-01

An important part of the Advanced Boiling Water Reactor (ABWR) in the Taiwan NPP Lungmen Units no.1 and no.2 is the Full Scope Simulator (FSS). The simulator was to be built according to design data and therefore, apart from the training aspect, a major part of the development is to apply a simulation based test bed for the verification, validation and improvement of plant design in the control and instrumentation (C and I) areas of unit control room equipment, operator Man Machine Interface (MMI), process computer functions and plant procedures. Furthermore the Full Scope Simulator will be used after that to allow proper training of the plant operators two years before Unit no.1 fuel load. The article describes scope, methods and results of the advanced verification and validation process and highlights the advantages of test bed simulation for real power plant design and implementation. Subsequent application of advanced simulation software tools like instrumentation and control translators, graphical model builders, process models, graphical on-line test tools and screen based or projected soft panels, allowed a team to fulfil the task of C and I verification in time before the implementation of the Distributed Control and Information System (DCIS) started. An additional area of activity was the Human Factors Engineering (HFE) for the operator MMI. Due to the fact that the ABWR design incorporates a display-based operation with most of the plant components, a dedicated verification and validation process is required by NUREG-0711. In order to support this activity an engineering test system had been installed for all the necessary HFE investigations. All detected improvements had been properly documented and used to update the plant design documentation by a defined process. The Full Scope Simulator (FSS) with hard panels and stimulated digital control and information system are in the final acceptance test process with the end customer, Taiwan Power Company

Nuclear disarmament verification

International Nuclear Information System (INIS)

DeVolpi, A.

1993-01-01

Arms control treaties, unilateral actions, and cooperative activities -- reflecting the defusing of East-West tensions -- are causing nuclear weapons to be disarmed and dismantled worldwide. In order to provide for future reductions and to build confidence in the permanency of this disarmament, verification procedures and technologies would play an important role. This paper outlines arms-control objectives, treaty organization, and actions that could be undertaken. For the purposes of this Workshop on Verification, nuclear disarmament has been divided into five topical subareas: Converting nuclear-weapons production complexes, Eliminating and monitoring nuclear-weapons delivery systems, Disabling and destroying nuclear warheads, Demilitarizing or non-military utilization of special nuclear materials, and Inhibiting nuclear arms in non-nuclear-weapons states. This paper concludes with an overview of potential methods for verification

Verification Account Management System (VAMS)

Data.gov (United States)

Social Security Administration — The Verification Account Management System (VAMS) is the centralized location for maintaining SSA's verification and data exchange accounts. VAMS account management...

Quantum money with classical verification

Energy Technology Data Exchange (ETDEWEB)

Gavinsky, Dmitry [NEC Laboratories America, Princeton, NJ (United States)

2014-12-04

We propose and construct a quantum money scheme that allows verification through classical communication with a bank. This is the first demonstration that a secure quantum money scheme exists that does not require quantum communication for coin verification. Our scheme is secure against adaptive adversaries - this property is not directly related to the possibility of classical verification, nevertheless none of the earlier quantum money constructions is known to possess it.

Quantum money with classical verification

International Nuclear Information System (INIS)

Gavinsky, Dmitry

2014-01-01

We propose and construct a quantum money scheme that allows verification through classical communication with a bank. This is the first demonstration that a secure quantum money scheme exists that does not require quantum communication for coin verification. Our scheme is secure against adaptive adversaries - this property is not directly related to the possibility of classical verification, nevertheless none of the earlier quantum money constructions is known to possess it

NEW APPROACHES TO EFFICIENCY OF MASSIVE ONLINE COURSE

Directory of Open Access Journals (Sweden)

Liubov S. Lysitsina

2014-09-01

Full Text Available This paper is focused on efficiency of e-learning, in general, and massive online course in programming and information technology, in particular. Several innovative approaches and scenarios have been proposed, developed, implemented and verified by the authors, including 1 a new approach to organize and use automatic immediate feedback that significantly helps a learner to verify developed code and increases an efficiency of learning, 2 a new approach to construct learning interfaces – it is based on “develop a code – get a result – validate a code” technique, 3 three scenarios of visualization and verification of developed code, 4 a new multi-stage approach to solve complex programming assignments, 5 a new implementation of “perfectionism” game mechanics in a massive online course. Overall, due to implementation of proposed and developed approaches, the efficiency of massive online course has been considerably increased, particularly 1 the additional 27.9 % of students were able to complete successfully “Web design and development using HTML5 and CSS3” massive online course at ITMO University, and 2 based on feedback from 5588 students a “perfectionism” game mechanics noticeably improves students’ involvement into course activities and retention factor.

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

Particularities of Verification Processes for Distributed Informatics Applications

Directory of Open Access Journals (Sweden)

Ion IVAN

2013-01-01

Full Text Available This paper presents distributed informatics applications and characteristics of their development cycle. It defines the concept of verification and there are identified the differences from software testing. Particularities of the software testing and software verification processes are described. The verification steps and necessary conditions are presented and there are established influence factors of quality verification. Software optimality verification is analyzed and some metrics are defined for the verification process.

Nuclear test ban verification

International Nuclear Information System (INIS)

Chun, Kin-Yip

1991-07-01

This report describes verification and its rationale, the basic tasks of seismic verification, the physical basis for earthquake/explosion source discrimination and explosion yield determination, the technical problems pertaining to seismic monitoring of underground nuclear tests, the basic problem-solving strategy deployed by the forensic seismology resarch team at the University of Toronto, and the scientific significance of the team's research. The research carried out at the Univeristy of Toronto has two components: teleseismic verification using P wave recordings from the Yellowknife Seismic Array (YKA), and regional (close-in) verification using high-frequency L g and P n recordings from the Eastern Canada Telemetered Network. Major differences have been found in P was attenuation among the propagation paths connecting the YKA listening post with seven active nuclear explosion testing areas in the world. Significant revisions have been made to previously published P wave attenuation results, leading to more interpretable nuclear explosion source functions. (11 refs., 12 figs.)

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

Verification of results of core physics on-line simulation by NGFM code

International Nuclear Information System (INIS)

Zhao Yu; Cao Xinrong; Zhao Qiang

2008-01-01

Nodal Green's Function Method program NGFM/TNGFM has been trans- planted to windows system. The 2-D and 3-D benchmarks have been checked by this program. And the program has been used to check the results of QINSHAN-II reactor simulation. It is proved that the NGFM/TNGFM program is applicable for reactor core physics on-line simulation system. (authors)

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.

Java bytecode verification via static single assignment form

DEFF Research Database (Denmark)

Gal, Andreas; Probst, Christian W.; Franz, Michael

2008-01-01

Java Virtual Machines (JVMs) traditionally perform bytecode verification by way of an iterative data-flow analysis. Bytecode verification is necessary to ensure type safety because temporary variables in the JVM are not statically typed. We present an alternative verification mechanism that trans......Java Virtual Machines (JVMs) traditionally perform bytecode verification by way of an iterative data-flow analysis. Bytecode verification is necessary to ensure type safety because temporary variables in the JVM are not statically typed. We present an alternative verification mechanism...

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.)

Formal verification of algorithms for critical systems

Science.gov (United States)

Rushby, John M.; Von Henke, Friedrich

1993-01-01

We describe our experience with formal, machine-checked verification of algorithms for critical applications, concentrating on a Byzantine fault-tolerant algorithm for synchronizing the clocks in the replicated computers of a digital flight control system. First, we explain the problems encountered in unsynchronized systems and the necessity, and criticality, of fault-tolerant synchronization. We give an overview of one such algorithm, and of the arguments for its correctness. Next, we describe a verification of the algorithm that we performed using our EHDM system for formal specification and verification. We indicate the errors we found in the published analysis of the algorithm, and other benefits that we derived from the verification. Based on our experience, we derive some key requirements for a formal specification and verification system adequate to the task of verifying algorithms of the type considered. Finally, we summarize our conclusions regarding the benefits of formal verification in this domain, and the capabilities required of verification systems in order to realize those benefits.

FIR signature verification system characterizing dynamics of handwriting features

Science.gov (United States)

Thumwarin, Pitak; Pernwong, Jitawat; Matsuura, Takenobu

2013-12-01

This paper proposes an online signature verification method based on the finite impulse response (FIR) system characterizing time-frequency characteristics of dynamic handwriting features. First, the barycenter determined from both the center point of signature and two adjacent pen-point positions in the signing process, instead of one pen-point position, is used to reduce the fluctuation of handwriting motion. In this paper, among the available dynamic handwriting features, motion pressure and area pressure are employed to investigate handwriting behavior. Thus, the stable dynamic handwriting features can be described by the relation of the time-frequency characteristics of the dynamic handwriting features. In this study, the aforesaid relation can be represented by the FIR system with the wavelet coefficients of the dynamic handwriting features as both input and output of the system. The impulse response of the FIR system is used as the individual feature for a particular signature. In short, the signature can be verified by evaluating the difference between the impulse responses of the FIR systems for a reference signature and the signature to be verified. The signature verification experiments in this paper were conducted using the SUBCORPUS MCYT-100 signature database consisting of 5,000 signatures from 100 signers. The proposed method yielded equal error rate (EER) of 3.21% on skilled forgeries.

Challenges for effective WMD verification

International Nuclear Information System (INIS)

Andemicael, B.

2006-01-01

Effective verification is crucial to the fulfillment of the objectives of any disarmament treaty, not least as regards the proliferation of weapons of mass destruction (WMD). The effectiveness of the verification package depends on a number of factors, some inherent in the agreed structure and others related to the type of responses demanded by emerging challenges. The verification systems of three global agencies-the IAEA, the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO, currently the Preparatory Commission), and the Organization for the Prohibition of Chemical Weapons (OPCW)-share similarities in their broad objectives of confidence-building and deterrence by assuring members that rigorous verification would deter or otherwise detect non-compliance. Yet they are up against various constraints and other issues, both internal and external to the treaty regime. These constraints pose major challenges to the effectiveness and reliability of the verification operations. In the nuclear field, the IAEA safeguards process was the first to evolve incrementally from modest Statute beginnings to a robust verification system under the global Treaty on the Non-Proliferation of Nuclear Weapons (NPT). The nuclear non-proliferation regime is now being supplemented by a technology-intensive verification system of the nuclear test-ban treaty (CTBT), a product of over three decades of negotiation. However, there still remain fundamental gaps and loopholes in the regime as a whole, which tend to diminish the combined effectiveness of the IAEA and the CTBT verification capabilities. He three major problems are (a) the lack of universality of membership, essentially because of the absence of three nuclear weapon-capable States-India, Pakistan and Israel-from both the NPT and the CTBT, (b) the changes in US disarmament policy, especially in the nuclear field, and (c) the failure of the Conference on Disarmament to conclude a fissile material cut-off treaty. The world is

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

Science.gov (United States)

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.

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.

A Syntactic-Semantic Approach to Incremental Verification

OpenAIRE

Bianculli, Domenico; Filieri, Antonio; Ghezzi, Carlo; Mandrioli, Dino

2013-01-01

Software verification of evolving systems is challenging mainstream methodologies and tools. Formal verification techniques often conflict with the time constraints imposed by change management practices for evolving systems. Since changes in these systems are often local to restricted parts, an incremental verification approach could be beneficial. This paper introduces SiDECAR, a general framework for the definition of verification procedures, which are made incremental by the framework...

Verification and validation benchmarks.

Energy Technology Data Exchange (ETDEWEB)

Oberkampf, William Louis; Trucano, Timothy Guy

2007-02-01

Verification and validation (V&V) are the primary means to assess the accuracy and reliability of computational simulations. V&V methods and procedures have fundamentally improved the credibility of simulations in several high-consequence fields, such as nuclear reactor safety, underground nuclear waste storage, and nuclear weapon safety. Although the terminology is not uniform across engineering disciplines, code verification deals with assessing the reliability of the software coding, and solution verification deals with assessing the numerical accuracy of the solution to a computational model. Validation addresses the physics modeling accuracy of a computational simulation by comparing the computational results with experimental data. Code verification benchmarks and validation benchmarks have been constructed for a number of years in every field of computational simulation. However, no comprehensive guidelines have been proposed for the construction and use of V&V benchmarks. For example, the field of nuclear reactor safety has not focused on code verification benchmarks, but it has placed great emphasis on developing validation benchmarks. Many of these validation benchmarks are closely related to the operations of actual reactors at near-safety-critical conditions, as opposed to being more fundamental-physics benchmarks. This paper presents recommendations for the effective design and use of code verification benchmarks based on manufactured solutions, classical analytical solutions, and highly accurate numerical solutions. In addition, this paper presents recommendations for the design and use of validation benchmarks, highlighting the careful design of building-block experiments, the estimation of experimental measurement uncertainty for both inputs and outputs to the code, validation metrics, and the role of model calibration in validation. It is argued that the understanding of predictive capability of a computational model is built on the level of

Verification of Ceramic Structures

Science.gov (United States)

Behar-Lafenetre, Stephanie; Cornillon, Laurence; Rancurel, Michael; De Graaf, Dennis; Hartmann, Peter; Coe, Graham; Laine, Benoit

2012-07-01

In the framework of the “Mechanical Design and Verification Methodologies for Ceramic Structures” contract [1] awarded by ESA, Thales Alenia Space has investigated literature and practices in affiliated industries to propose a methodological guideline for verification of ceramic spacecraft and instrument structures. It has been written in order to be applicable to most types of ceramic or glass-ceramic materials - typically Cesic®, HBCesic®, Silicon Nitride, Silicon Carbide and ZERODUR®. The proposed guideline describes the activities to be performed at material level in order to cover all the specific aspects of ceramics (Weibull distribution, brittle behaviour, sub-critical crack growth). Elementary tests and their post-processing methods are described, and recommendations for optimization of the test plan are given in order to have a consistent database. The application of this method is shown on an example in a dedicated article [7]. Then the verification activities to be performed at system level are described. This includes classical verification activities based on relevant standard (ECSS Verification [4]), plus specific analytical, testing and inspection features. The analysis methodology takes into account the specific behaviour of ceramic materials, especially the statistical distribution of failures (Weibull) and the method to transfer it from elementary data to a full-scale structure. The demonstration of the efficiency of this method is described in a dedicated article [8]. The verification is completed by classical full-scale testing activities. Indications about proof testing, case of use and implementation are given and specific inspection and protection measures are described. These additional activities are necessary to ensure the required reliability. The aim of the guideline is to describe how to reach the same reliability level as for structures made of more classical materials (metals, composites).

Is flow verification necessary

International Nuclear Information System (INIS)

Beetle, T.M.

1986-01-01

Safeguards test statistics are used in an attempt to detect diversion of special nuclear material. Under assumptions concerning possible manipulation (falsification) of safeguards accounting data, the effects on the statistics due to diversion and data manipulation are described algebraically. A comprehensive set of statistics that is capable of detecting any diversion of material is defined in terms of the algebraic properties of the effects. When the assumptions exclude collusion between persons in two material balance areas, then three sets of accounting statistics are shown to be comprehensive. Two of the sets contain widely known accountancy statistics. One of them does not require physical flow verification - comparisons of operator and inspector data for receipts and shipments. The third set contains a single statistic which does not require physical flow verification. In addition to not requiring technically difficult and expensive flow verification, this single statistic has several advantages over other comprehensive sets of statistics. This algebraic approach as an alternative to flow verification for safeguards accountancy is discussed in this paper

Procedure generation and verification

International Nuclear Information System (INIS)

Sheely, W.F.

1986-01-01

The Department of Energy has used Artificial Intelligence of ''AI'' concepts to develop two powerful new computer-based techniques to enhance safety in nuclear applications. The Procedure Generation System, and the Procedure Verification System, can be adapted to other commercial applications, such as a manufacturing plant. The Procedure Generation System can create a procedure to deal with the off-normal condition. The operator can then take correct actions on the system in minimal time. The Verification System evaluates the logic of the Procedure Generator's conclusions. This evaluation uses logic techniques totally independent of the Procedure Generator. The rapid, accurate generation and verification of corrective procedures can greatly reduce the human error, possible in a complex (stressful/high stress) situation

A Scalable Approach for Hardware Semiformal Verification

OpenAIRE

Grimm, Tomas; Lettnin, Djones; Hübner, Michael

2018-01-01

The current verification flow of complex systems uses different engines synergistically: virtual prototyping, formal verification, simulation, emulation and FPGA prototyping. However, none is able to verify a complete architecture. Furthermore, hybrid approaches aiming at complete verification use techniques that lower the overall complexity by increasing the abstraction level. This work focuses on the verification of complex systems at the RT level to handle the hardware peculiarities. Our r...

On-line estimations of delivered radiation doses in three-dimensional conformal radiotherapy treatments of carcinoma uterine cervix patients in linear accelerator.

Science.gov (United States)

Putha, Suman Kumar; Saxena, P U; Banerjee, S; Srinivas, Challapalli; Vadhiraja, B M; Ravichandran, Ramamoorthy; Joan, Mary; Pai, K Dinesh

2016-01-01

Transmission of radiation fluence through patient's body has a correlation to the planned target dose. A method to estimate the delivered dose to target volumes was standardized using a beam level 0.6 cc ionization chamber (IC) positioned at electronic portal imaging device (EPID) plane from the measured transit signal (S t ) in patients with cancer of uterine cervix treated with three-dimensional conformal radiotherapy (3DCRT). The IC with buildup cap was mounted on linear accelerator EPID frame with fixed source to chamber distance of 146.3 cm, using a locally fabricated mount. S t s were obtained for different water phantom thicknesses and radiation field sizes which were then used to generate a calibration table against calculated midplane doses at isocenter (D iso,TPS ), derived from the treatment planning system. A code was developed using MATLAB software which was used to estimate the in vivo dose at isocenter (D iso,Transit ) from the measured S t s. A locally fabricated pelvic phantom validated the estimations of D iso,Transit before implementing this method on actual patients. On-line dose estimations were made (3 times during treatment for each patient) in 24 patients. The D iso,Transit agreement with D iso,TPS in phantom was within 1.7% and the mean percentage deviation with standard deviation is -1.37% ±2.03% ( n = 72) observed in patients. Estimated in vivo dose at isocenter with this method provides a good agreement with planned ones which can be implemented as part of quality assurance in pelvic sites treated with simple techniques, for example, 3DCRT where there is a need for documentation of planned dose delivery.

Quality assurance for online adapted treatment plans: Benchmarking and delivery monitoring simulation

International Nuclear Information System (INIS)

Li, Taoran; Wu, Qiuwen; Yang, Yun; Rodrigues, Anna; Yin, Fang-Fang; Jackie Wu, Q.

2015-01-01

Purpose: An important challenge facing online adaptive radiation therapy is the development of feasible and efficient quality assurance (QA). This project aimed to validate the deliverability of online adapted plans and develop a proof-of-concept online delivery monitoring system for online adaptive radiation therapy QA. Methods: The first part of this project benchmarked automatically online adapted prostate treatment plans using traditional portal dosimetry IMRT QA. The portal dosimetry QA results of online adapted plans were compared to original (unadapted) plans as well as randomly selected prostate IMRT plans from our clinic. In the second part, an online delivery monitoring system was designed and validated via a simulated treatment with intentional multileaf collimator (MLC) errors. This system was based on inputs from the dynamic machine information (DMI), which continuously reports actual MLC positions and machine monitor units (MUs) at intervals of 50 ms or less during delivery. Based on the DMI, the system performed two levels of monitoring/verification during the delivery: (1) dynamic monitoring of cumulative fluence errors resulting from leaf position deviations and visualization using fluence error maps (FEMs); and (2) verification of MLC positions against the treatment plan for potential errors in MLC motion and data transfer at each control point. Validation of the online delivery monitoring system was performed by introducing intentional systematic MLC errors (ranging from 0.5 to 2 mm) to the DMI files for both leaf banks. These DMI files were analyzed by the proposed system to evaluate the system’s performance in quantifying errors and revealing the source of errors, as well as to understand patterns in the FEMs. In addition, FEMs from 210 actual prostate IMRT beams were analyzed using the proposed system to further validate its ability to catch and identify errors, as well as establish error magnitude baselines for prostate IMRT delivery

Quality assurance for online adapted treatment plans: Benchmarking and delivery monitoring simulation

Energy Technology Data Exchange (ETDEWEB)

Li, Taoran, E-mail: taoran.li.duke@gmail.com; Wu, Qiuwen; Yang, Yun; Rodrigues, Anna; Yin, Fang-Fang; Jackie Wu, Q. [Department of Radiation Oncology, Duke University Medical Center Durham, North Carolina 27710 (United States)

2015-01-15

Purpose: An important challenge facing online adaptive radiation therapy is the development of feasible and efficient quality assurance (QA). This project aimed to validate the deliverability of online adapted plans and develop a proof-of-concept online delivery monitoring system for online adaptive radiation therapy QA. Methods: The first part of this project benchmarked automatically online adapted prostate treatment plans using traditional portal dosimetry IMRT QA. The portal dosimetry QA results of online adapted plans were compared to original (unadapted) plans as well as randomly selected prostate IMRT plans from our clinic. In the second part, an online delivery monitoring system was designed and validated via a simulated treatment with intentional multileaf collimator (MLC) errors. This system was based on inputs from the dynamic machine information (DMI), which continuously reports actual MLC positions and machine monitor units (MUs) at intervals of 50 ms or less during delivery. Based on the DMI, the system performed two levels of monitoring/verification during the delivery: (1) dynamic monitoring of cumulative fluence errors resulting from leaf position deviations and visualization using fluence error maps (FEMs); and (2) verification of MLC positions against the treatment plan for potential errors in MLC motion and data transfer at each control point. Validation of the online delivery monitoring system was performed by introducing intentional systematic MLC errors (ranging from 0.5 to 2 mm) to the DMI files for both leaf banks. These DMI files were analyzed by the proposed system to evaluate the system’s performance in quantifying errors and revealing the source of errors, as well as to understand patterns in the FEMs. In addition, FEMs from 210 actual prostate IMRT beams were analyzed using the proposed system to further validate its ability to catch and identify errors, as well as establish error magnitude baselines for prostate IMRT delivery

Quality assurance for online adapted treatment plans: benchmarking and delivery monitoring simulation.

Science.gov (United States)

Li, Taoran; Wu, Qiuwen; Yang, Yun; Rodrigues, Anna; Yin, Fang-Fang; Jackie Wu, Q

2015-01-01

An important challenge facing online adaptive radiation therapy is the development of feasible and efficient quality assurance (QA). This project aimed to validate the deliverability of online adapted plans and develop a proof-of-concept online delivery monitoring system for online adaptive radiation therapy QA. The first part of this project benchmarked automatically online adapted prostate treatment plans using traditional portal dosimetry IMRT QA. The portal dosimetry QA results of online adapted plans were compared to original (unadapted) plans as well as randomly selected prostate IMRT plans from our clinic. In the second part, an online delivery monitoring system was designed and validated via a simulated treatment with intentional multileaf collimator (MLC) errors. This system was based on inputs from the dynamic machine information (DMI), which continuously reports actual MLC positions and machine monitor units (MUs) at intervals of 50 ms or less during delivery. Based on the DMI, the system performed two levels of monitoring/verification during the delivery: (1) dynamic monitoring of cumulative fluence errors resulting from leaf position deviations and visualization using fluence error maps (FEMs); and (2) verification of MLC positions against the treatment plan for potential errors in MLC motion and data transfer at each control point. Validation of the online delivery monitoring system was performed by introducing intentional systematic MLC errors (ranging from 0.5 to 2 mm) to the DMI files for both leaf banks. These DMI files were analyzed by the proposed system to evaluate the system's performance in quantifying errors and revealing the source of errors, as well as to understand patterns in the FEMs. In addition, FEMs from 210 actual prostate IMRT beams were analyzed using the proposed system to further validate its ability to catch and identify errors, as well as establish error magnitude baselines for prostate IMRT delivery. Online adapted plans were

Marijuana Promotion Online: an Investigation of Dispensary Practices.

Science.gov (United States)

Cavazos-Rehg, Patricia A; Krauss, Melissa J; Cahn, Elizabeth; Lee, Kiriam Escobar; Ferguson, Erin; Rajbhandari, Biva; Sowles, Shaina J; Floyd, Glennon M; Berg, Carla; Bierut, Laura J

2018-04-09

Marijuana product advertising will become more common, as the use of medical and/or recreational marijuana becomes increasingly legal in the USA. In this study, we investigate the marketing tactics being used on marijuana dispensary websites in the USA that could influence substance use behaviors. One hundred dispensary websites were randomly selected from 10 states that allowed the legal use of medical or recreational marijuana and had at least 10 operational dispensaries. Three dispensaries were excluded due to non-functioning websites, leaving a sample of 97 dispensaries. Content analysis was conducted on these dispensaries' websites, with the primary areas of focus including website age verification, marijuana effects, warnings, and promotional tactics. Among the 97 dispensaries, 75% did not include age verification. Roughly 30% offered online ordering and 21% offered delivery services. Sixty-seven percent made health claims pertaining to medical conditions that could be treated by their marijuana products, with moderate or conclusive evidence to support their claims. Less than half of the dispensaries (45%) advised consumers of possible side effects, and only 18% included warnings about contraindications. Nearly half (44%) offered reduced prices or coupons, 19% offered "buy one get one free" offers, and 16% provided giveaways or free samples. Our findings indicate that marijuana dispensary websites are easily accessible to youth. In addition, only a small amount of the websites advised consumers about possible side effects or contraindications. This study suggests the need for surveillance of marijuana commercialization and online advertising especially in the context of state policy reforms.

Survey on Offline Finger Print Verification System

NARCIS (Netherlands)

Suman, R.; Kaur, R.

2012-01-01

The fingerprint verification, means where "verification" implies a user matching a fingerprint against a single fingerprint associated with the identity that the user claims. Biometrics can be classified into two types Behavioral (signature verification, keystroke dynamics, etc.) And Physiological

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

In-core Instrument Subcritical Verification (INCISV) - Core Design Verification Method - 358

International Nuclear Information System (INIS)

Prible, M.C.; Heibel, M.D.; Conner, S.L.; Sebastiani, P.J.; Kistler, D.P.

2010-01-01

According to the standard on reload startup physics testing, ANSI/ANS 19.6.1, a plant must verify that the constructed core behaves sufficiently close to the designed core to confirm that the various safety analyses bound the actual behavior of the plant. A large portion of this verification must occur before the reactor operates at power. The INCISV Core Design Verification Method uses the unique characteristics of a Westinghouse Electric Company fixed in-core self powered detector design to perform core design verification after a core reload before power operation. A Vanadium self powered detector that spans the length of the active fuel region is capable of confirming the required core characteristics prior to power ascension; reactivity balance, shutdown margin, temperature coefficient and power distribution. Using a detector element that spans the length of the active fuel region inside the core provides a signal of total integrated flux. Measuring the integrated flux distributions and changes at various rodded conditions and plant temperatures, and comparing them to predicted flux levels, validates all core necessary core design characteristics. INCISV eliminates the dependence on various corrections and assumptions between the ex-core detectors and the core for traditional physics testing programs. This program also eliminates the need for special rod maneuvers which are infrequently performed by plant operators during typical core design verification testing and allows for safer startup activities. (authors)

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.

Fingerprint verification prediction model in hand dermatitis.

Science.gov (United States)

Lee, Chew K; Chang, Choong C; Johor, Asmah; Othman, Puwira; Baba, Roshidah

2015-07-01

Hand dermatitis associated fingerprint changes is a significant problem and affects fingerprint verification processes. This study was done to develop a clinically useful prediction model for fingerprint verification in patients with hand dermatitis. A case-control study involving 100 patients with hand dermatitis. All patients verified their thumbprints against their identity card. Registered fingerprints were randomized into a model derivation and model validation group. Predictive model was derived using multiple logistic regression. Validation was done using the goodness-of-fit test. The fingerprint verification prediction model consists of a major criterion (fingerprint dystrophy area of ≥ 25%) and two minor criteria (long horizontal lines and long vertical lines). The presence of the major criterion predicts it will almost always fail verification, while presence of both minor criteria and presence of one minor criterion predict high and low risk of fingerprint verification failure, respectively. When none of the criteria are met, the fingerprint almost always passes the verification. The area under the receiver operating characteristic curve was 0.937, and the goodness-of-fit test showed agreement between the observed and expected number (P = 0.26). The derived fingerprint verification failure prediction model is validated and highly discriminatory in predicting risk of fingerprint verification in patients with hand dermatitis. © 2014 The International Society of Dermatology.

Brote epidémico de neumonías por Legionella pneumophila en niños cubanos

Directory of Open Access Journals (Sweden)

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

Verification and validation benchmarks

International Nuclear Information System (INIS)

Oberkampf, William Louis; Trucano, Timothy Guy

2007-01-01

Verification and validation (V and V) are the primary means to assess the accuracy and reliability of computational simulations. V and V methods and procedures have fundamentally improved the credibility of simulations in several high-consequence fields, such as nuclear reactor safety, underground nuclear waste storage, and nuclear weapon safety. Although the terminology is not uniform across engineering disciplines, code verification deals with assessing the reliability of the software coding, and solution verification deals with assessing the numerical accuracy of the solution to a computational model. Validation addresses the physics modeling accuracy of a computational simulation by comparing the computational results with experimental data. Code verification benchmarks and validation benchmarks have been constructed for a number of years in every field of computational simulation. However, no comprehensive guidelines have been proposed for the construction and use of V and V benchmarks. For example, the field of nuclear reactor safety has not focused on code verification benchmarks, but it has placed great emphasis on developing validation benchmarks. Many of these validation benchmarks are closely related to the operations of actual reactors at near-safety-critical conditions, as opposed to being more fundamental-physics benchmarks. This paper presents recommendations for the effective design and use of code verification benchmarks based on manufactured solutions, classical analytical solutions, and highly accurate numerical solutions. In addition, this paper presents recommendations for the design and use of validation benchmarks, highlighting the careful design of building-block experiments, the estimation of experimental measurement uncertainty for both inputs and outputs to the code, validation metrics, and the role of model calibration in validation. It is argued that the understanding of predictive capability of a computational model is built on the

Verification and validation benchmarks

International Nuclear Information System (INIS)

Oberkampf, William L.; Trucano, Timothy G.

2008-01-01

Verification and validation (V and V) are the primary means to assess the accuracy and reliability of computational simulations. V and V methods and procedures have fundamentally improved the credibility of simulations in several high-consequence fields, such as nuclear reactor safety, underground nuclear waste storage, and nuclear weapon safety. Although the terminology is not uniform across engineering disciplines, code verification deals with assessing the reliability of the software coding, and solution verification deals with assessing the numerical accuracy of the solution to a computational model. Validation addresses the physics modeling accuracy of a computational simulation by comparing the computational results with experimental data. Code verification benchmarks and validation benchmarks have been constructed for a number of years in every field of computational simulation. However, no comprehensive guidelines have been proposed for the construction and use of V and V benchmarks. For example, the field of nuclear reactor safety has not focused on code verification benchmarks, but it has placed great emphasis on developing validation benchmarks. Many of these validation benchmarks are closely related to the operations of actual reactors at near-safety-critical conditions, as opposed to being more fundamental-physics benchmarks. This paper presents recommendations for the effective design and use of code verification benchmarks based on manufactured solutions, classical analytical solutions, and highly accurate numerical solutions. In addition, this paper presents recommendations for the design and use of validation benchmarks, highlighting the careful design of building-block experiments, the estimation of experimental measurement uncertainty for both inputs and outputs to the code, validation metrics, and the role of model calibration in validation. It is argued that the understanding of predictive capability of a computational model is built on the

Recruitment Strategies of Methamphetamine-Using Men Who Have Sex with Men into an Online Survey.

Science.gov (United States)

Wilkerson, J Michael; Shenk, Jared E; Grey, Jeremy A; Simon Rosser, B R; Noor, Syed W

Recruiting hidden populations into online research remains challenging. In this manuscript, we report lessons learned from our efforts to recruit methamphetamine-using men who have sex with men. Between July and October 2012, we implemented a four-phase recruitment strategy to enroll a total of 343 methamphetamine-using MSM into an online survey about recent substance use, sexual behavior, and various psychosocial measures. The four phases were implemented sequentially. During phase one, we placed advertisements on mobile applications, and during phase two, we placed advertisements on traditional websites formatted for browsers. During phase three, we used e-mail to initiate snowball recruitment, and during phase four, we used social media for snowball recruitment. Advertisements on mobile devices and websites formatted for browsers proved to be expensive options and resulted in few eligible participants. Our attempts to initiate a snowball through e-mail also proved unsuccessful. The majority (n=320) of observations in our final dataset came from our use of social media. However, participant fraud was a concern, requiring us to implement a strong participant verification protocol. For maximum recruitment and cost-effectiveness, researchers should use social media for recruitment provided they employ strong participant verification protocols.

Reliability-Based Decision Fusion in Multimodal Biometric Verification Systems

Directory of Open Access Journals (Sweden)

Kryszczuk Krzysztof

2007-01-01

Full Text Available We present a methodology of reliability estimation in the multimodal biometric verification scenario. Reliability estimation has shown to be an efficient and accurate way of predicting and correcting erroneous classification decisions in both unimodal (speech, face, online signature and multimodal (speech and face systems. While the initial research results indicate the high potential of the proposed methodology, the performance of the reliability estimation in a multimodal setting has not been sufficiently studied or evaluated. In this paper, we demonstrate the advantages of using the unimodal reliability information in order to perform an efficient biometric fusion of two modalities. We further show the presented method to be superior to state-of-the-art multimodal decision-level fusion schemes. The experimental evaluation presented in this paper is based on the popular benchmarking bimodal BANCA database.

Quantitative analysis of patient-specific dosimetric IMRT verification

International Nuclear Information System (INIS)

Budgell, G J; Perrin, B A; Mott, J H L; Fairfoul, J; Mackay, R I

2005-01-01

Patient-specific dosimetric verification methods for IMRT treatments are variable, time-consuming and frequently qualitative, preventing evidence-based reduction in the amount of verification performed. This paper addresses some of these issues by applying a quantitative analysis parameter to the dosimetric verification procedure. Film measurements in different planes were acquired for a series of ten IMRT prostate patients, analysed using the quantitative parameter, and compared to determine the most suitable verification plane. Film and ion chamber verification results for 61 patients were analysed to determine long-term accuracy, reproducibility and stability of the planning and delivery system. The reproducibility of the measurement and analysis system was also studied. The results show that verification results are strongly dependent on the plane chosen, with the coronal plane particularly insensitive to delivery error. Unexpectedly, no correlation could be found between the levels of error in different verification planes. Longer term verification results showed consistent patterns which suggest that the amount of patient-specific verification can be safely reduced, provided proper caution is exercised: an evidence-based model for such reduction is proposed. It is concluded that dose/distance to agreement (e.g., 3%/3 mm) should be used as a criterion of acceptability. Quantitative parameters calculated for a given criterion of acceptability should be adopted in conjunction with displays that show where discrepancies occur. Planning and delivery systems which cannot meet the required standards of accuracy, reproducibility and stability to reduce verification will not be accepted by the radiotherapy community

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.

Post-silicon and runtime verification for modern processors

CERN Document Server

Wagner, Ilya

2010-01-01

The purpose of this book is to survey the state of the art and evolving directions in post-silicon and runtime verification. The authors start by giving an overview of the state of the art in verification, particularly current post-silicon methodologies in use in the industry, both for the domain of processor pipeline design and for memory subsystems. They then dive into the presentation of several new post-silicon verification solutions aimed at boosting the verification coverage of modern processors, dedicating several chapters to this topic. The presentation of runtime verification solution

Verification and the safeguards legacy

International Nuclear Information System (INIS)

Perricos, Demetrius

2001-01-01

A number of inspection or monitoring systems throughout the world over the last decades have been structured drawing upon the IAEA experience of setting up and operating its safeguards system. The first global verification system was born with the creation of the IAEA safeguards system, about 35 years ago. With the conclusion of the NPT in 1968, inspections were to be performed under safeguards agreements, concluded directly between the IAEA and non-nuclear weapon states parties to the Treaty. The IAEA developed the safeguards system within the limitations reflected in the Blue Book (INFCIRC 153), such as limitations of routine access by the inspectors to 'strategic points', including 'key measurement points', and the focusing of verification on declared nuclear material in declared installations. The system, based as it was on nuclear material accountancy. It was expected to detect a diversion of nuclear material with a high probability and within a given time and therefore determine also that there had been no diversion of nuclear material from peaceful purposes. The most vital element of any verification system is the inspector. Technology can assist but cannot replace the inspector in the field. Their experience, knowledge, intuition and initiative are invaluable factors contributing to the success of any inspection regime. The IAEA inspectors are however not part of an international police force that will intervene to prevent a violation taking place. To be credible they should be technically qualified with substantial experience in industry or in research and development before they are recruited. An extensive training program has to make sure that the inspectors retain their professional capabilities and that it provides them with new skills. Over the years, the inspectors and through them the safeguards verification system gained experience in: organization and management of large teams; examination of records and evaluation of material balances

RESRAD-BUILD verification

International Nuclear Information System (INIS)

Kamboj, S.; Yu, C.; Biwer, B. M.; Klett, T.

2002-01-01

The results generated by the RESRAD-BUILD code (version 3.0) were verified with hand or spreadsheet calculations using equations given in the RESRAD-BUILD manual for different pathways. For verification purposes, different radionuclides--H-3, C-14, Na-22, Al-26, Cl-36, Mn-54, Co-60, Au-195, Ra-226, Ra-228, Th-228, and U-238--were chosen to test all pathways and models. Tritium, Ra-226, and Th-228 were chosen because of the special tritium and radon models in the RESRAD-BUILD code. Other radionuclides were selected to represent a spectrum of radiation types and energies. Verification of the RESRAD-BUILD code was conducted with an initial check of all the input parameters for correctness against their original source documents. Verification of the calculations was performed external to the RESRAD-BUILD code with Microsoft Excel to verify all the major portions of the code. In some cases, RESRAD-BUILD results were compared with those of external codes, such as MCNP (Monte Carlo N-particle) and RESRAD. The verification was conducted on a step-by-step basis and used different test cases as templates. The following types of calculations were investigated: (1) source injection rate, (2) air concentration in the room, (3) air particulate deposition, (4) radon pathway model, (5) tritium model for volume source, (6) external exposure model, (7) different pathway doses, and (8) time dependence of dose. Some minor errors were identified in version 3.0; these errors have been corrected in later versions of the code. Some possible improvements in the code were also identified

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

Spent fuel verification options for final repository safeguards in Finland. A study on verification methods, their feasibility and safety aspects

International Nuclear Information System (INIS)

Hautamaeki, J.; Tiitta, A.

2000-12-01

The verification possibilities of the spent fuel assemblies from the Olkiluoto and Loviisa NPPs and the fuel rods from the research reactor of VTT are contemplated in this report. The spent fuel assemblies have to be verified at the partial defect level before the final disposal into the geologic repository. The rods from the research reactor may be verified at the gross defect level. Developing a measurement system for partial defect verification is a complicated and time-consuming task. The Passive High Energy Gamma Emission Tomography and the Fork Detector combined with Gamma Spectrometry are the most potential measurement principles to be developed for this purpose. The whole verification process has to be planned to be as slick as possible. An early start in the planning of the verification and developing the measurement devices is important in order to enable a smooth integration of the verification measurements into the conditioning and disposal process. The IAEA and Euratom have not yet concluded the safeguards criteria for the final disposal. E.g. criteria connected to the selection of the best place to perform the verification. Measurements have not yet been concluded. Options for the verification places have been considered in this report. One option for a verification measurement place is the intermediate storage. The other option is the encapsulation plant. Crucial viewpoints are such as which one offers the best practical possibilities to perform the measurements effectively and which would be the better place in the safeguards point of view. Verification measurements may be needed both in the intermediate storages and in the encapsulation plant. In this report also the integrity of the fuel assemblies after wet intermediate storage period is assessed, because the assemblies have to stand the handling operations of the verification measurements. (orig.)

The development of intensity modulated radiotherapy (IMRT) for prostate cancer at Austin and Repatriation Medical Centre (ARMC)

International Nuclear Information System (INIS)

Joon, D.L.; Mantle, C.; Viotto, A.; Rolfo, A.; Rykers, K.; Fernando, W.; Grace, M.; Liu, G.; Quong, G.; Feigen, M.; Wada, M.; Joon, M.L.; Fogarty, G.; Chao, M.W.; Khoo, V.

2003-01-01

To describe the protocol development of the IMRT program for prostate cancer at the ARMC. A series of protocols were defined and developed to facilitate the delivery of intensity modulated radiotherapy for prostate cancer. These included the following: 1. Physical Simulation including bowel and bladder preparation and immobilization 2. Image Acquisition including CT and MRI simulation scans with image co-registration 3. Contouring Definitions including target and organ at risk volumes as well as IMRT optimization and evaluation volumes 4. Radiotherapy Planning including constraint definition, inverse planning and CMS Focus specific parameters 5. DICOM RT interface including data transfer between CMS Focus and the Elekta Linac Desktop record and verify system 6. Verification including action limits and pre-treatment online EPID verification 7. Radiotherapy Delivery being that of step and shoot 8. Quality Assurance including physics testing and documentation The protocol development and testing has lead to the precise clinical delivery of IMRT for prostate cancer at ARMC that exceeds most of the parameters that were previously measured with our conventional and 3D conformal radiotherapy. Further development is now underway to allow it to be implemented as the routine treatment of prostate cancer at ARMC. The clinical implementation of IMRT for prostate cancer involves a collaborative team approach including radiation oncologists, radiation therapists, and radiation physics. This is necessary to develop the appropriate protocols and quality assurance for precision radiotherapy that is required for IMRT

Verification of safety critical software

International Nuclear Information System (INIS)

Son, Ki Chang; Chun, Chong Son; Lee, Byeong Joo; Lee, Soon Sung; Lee, Byung Chai

1996-01-01

To assure quality of safety critical software, software should be developed in accordance with software development procedures and rigorous software verification and validation should be performed. Software verification is the formal act of reviewing, testing of checking, and documenting whether software components comply with the specified requirements for a particular stage of the development phase[1]. New software verification methodology was developed and was applied to the Shutdown System No. 1 and 2 (SDS1,2) for Wolsung 2,3 and 4 nuclear power plants by Korea Atomic Energy Research Institute(KAERI) and Atomic Energy of Canada Limited(AECL) in order to satisfy new regulation requirements of Atomic Energy Control Boars(AECB). Software verification methodology applied to SDS1 for Wolsung 2,3 and 4 project will be described in this paper. Some errors were found by this methodology during the software development for SDS1 and were corrected by software designer. Outputs from Wolsung 2,3 and 4 project have demonstrated that the use of this methodology results in a high quality, cost-effective product. 15 refs., 6 figs. (author)

Future of monitoring and verification

International Nuclear Information System (INIS)

Wagenmakers, H.

1991-01-01

The organized verification entrusted to IAEA for the implementation of the NPT, of the Treaty of Tlatelolco and of the Treaty of Rarotonga, reaches reasonable standards. The current dispute with the Democratic People's Republic of Korea about the conclusion of a safeguards agreement with IAEA, by its exceptional nature, underscores rather than undermines the positive judgement to be passed on IAEA's overall performance. The additional task given to the Director General of IAEA under Security Council resolution 687 (1991) regarding Iraq's nuclear-weapons-usable material is particularly challenging. For the purposes of this paper, verification is defined as the process for establishing whether the States parties are complying with an agreement. In the final stage verification may lead into consideration of how to respond to non-compliance. Monitoring is perceived as the first level in the verification system. It is one generic form of collecting information on objects, activities or events and it involves a variety of instruments ranging from communications satellites to television cameras or human inspectors. Monitoring may also be used as a confidence-building measure

On-line surveillance system for Borssele nuclear power plant monitoring and diagnostics

International Nuclear Information System (INIS)

Tuerkcan, E.; Ciftcioglu, Oe.

1993-08-01

An operating on-line surveillance and diagnostic system is described where information processing for monitoring and fault diagnosis and plant maintenance are addressed. The surveillance system by means of its realtime multiprocessing, multitasking execution capabilities can perform plant-wide and wide-range monitoring for enhanced plant safety and operational reliability as well as enhanced maintenance. At the same time the system provides the possibilities for goal-oriented research and development such as estimation, filtering, verification and validation and neural networks. (orig./HP)

Concepts for inventory verification in critical facilities

International Nuclear Information System (INIS)

Cobb, D.D.; Sapir, J.L.; Kern, E.A.; Dietz, R.J.

1978-12-01

Materials measurement and inventory verification concepts for safeguarding large critical facilities are presented. Inspection strategies and methods for applying international safeguards to such facilities are proposed. The conceptual approach to routine inventory verification includes frequent visits to the facility by one inspector, and the use of seals and nondestructive assay (NDA) measurements to verify the portion of the inventory maintained in vault storage. Periodic verification of the reactor inventory is accomplished by sampling and NDA measurement of in-core fuel elements combined with measurements of integral reactivity and related reactor parameters that are sensitive to the total fissile inventory. A combination of statistical sampling and NDA verification with measurements of reactor parameters is more effective than either technique used by itself. Special procedures for assessment and verification for abnormal safeguards conditions are also considered. When the inspection strategies and inventory verification methods are combined with strict containment and surveillance methods, they provide a high degree of assurance that any clandestine attempt to divert a significant quantity of fissile material from a critical facility inventory will be detected. Field testing of specific hardware systems and procedures to determine their sensitivity, reliability, and operational acceptability is recommended. 50 figures, 21 tables

Verification and Examination Management of Complex Systems

Directory of Open Access Journals (Sweden)

Stian Ruud

2014-10-01

Full Text Available As ship systems become more complex, with an increasing number of safety-critical functions, many interconnected subsystems, tight integration to other systems, and a large amount of potential failure modes, several industry parties have identified the need for improved methods for managing the verification and examination efforts of such complex systems. Such needs are even more prominent now that the marine and offshore industries are targeting more activities and operations in the Arctic environment. In this paper, a set of requirements and a method for verification and examination management are proposed for allocating examination efforts to selected subsystems. The method is based on a definition of a verification risk function for a given system topology and given requirements. The marginal verification risks for the subsystems may then be evaluated, so that examination efforts for the subsystem can be allocated. Two cases of requirements and systems are used to demonstrate the proposed method. The method establishes a systematic relationship between the verification loss, the logic system topology, verification method performance, examination stop criterion, the required examination effort, and a proposed sequence of examinations to reach the examination stop criterion.

Monitoring and verification R and D

International Nuclear Information System (INIS)

Pilat, Joseph F.; Budlong-Sylvester, Kory W.; Fearey, Bryan L.

2011-01-01

The 2010 Nuclear Posture Review (NPR) report outlined the Administration's approach to promoting the agenda put forward by President Obama in Prague on April 5, 2009. The NPR calls for a national monitoring and verification R and D program to meet future challenges arising from the Administration's nonproliferation, arms control and disarmament agenda. Verification of a follow-on to New START could have to address warheads and possibly components along with delivery capabilities. Deeper cuts and disarmament would need to address all of these elements along with nuclear weapon testing, nuclear material and weapon production facilities, virtual capabilities from old weapon and existing energy programs and undeclared capabilities. We only know how to address some elements of these challenges today, and the requirements may be more rigorous in the context of deeper cuts as well as disarmament. Moreover, there is a critical need for multiple options to sensitive problems and to address other challenges. There will be other verification challenges in a world of deeper cuts and disarmament, some of which we are already facing. At some point, if the reductions process is progressing, uncertainties about past nuclear materials and weapons production will have to be addressed. IAEA safeguards will need to continue to evolve to meet current and future challenges, and to take advantage of new technologies and approaches. Transparency/verification of nuclear and dual-use exports will also have to be addressed, and there will be a need to make nonproliferation measures more watertight and transparent. In this context, and recognizing we will face all of these challenges even if disarmament is not achieved, this paper will explore possible agreements and arrangements; verification challenges; gaps in monitoring and verification technologies and approaches; and the R and D required to address these gaps and other monitoring and verification challenges.

Necrólisis epidérmica tóxica: Descripción de 1 caso

Directory of Open Access Journals (Sweden)

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.

Online adaptation and verification of VMAT

Energy Technology Data Exchange (ETDEWEB)

Crijns, Wouter, E-mail: wouter.crijns@uzleuven.be [KU Leuven Department of Oncology, Laboratory of Experimental Radiotherapy, Herestraat 49, Leuven 3000, Belgium and KU Leuven Medical Imaging Research Center, Herestraat 49, Leuven 3000 (Belgium); Defraene, Gilles; Depuydt, Tom; Haustermans, Karin [KU Leuven Department of Oncology, Laboratory of Experimental Radiotherapy, Herestraat 49, Leuven 3000 (Belgium); Van Herck, Hans [KU Leuven Medical Imaging Research Center, Herestraat 49, Leuven 3000, Belgium and KU Leuven Department of Electrical Engineering (ESAT), PSI, Center for Processing Speech and Images, Leuven 3000 (Belgium); Maes, Frederik [KU Leuven Department of Electrical Engineering (ESAT), PSI, Center for Processing Speech and Images, Leuven 3000, Belgium and KU Leuven iMinds - Medical IT Department, Leuven 3000 (Belgium); Van den Heuvel, Frank [Department of Oncology, MRC-CR-UK Gray Institute of Radiation Oncology and Biology, University of Oxford, Oxford OX1 2JD (United Kingdom)

2015-07-15

Purpose: This work presents a method for fast volumetric modulated arc therapy (VMAT) adaptation in response to interfraction anatomical variations. Additionally, plan parameters extracted from the adapted plans are used to verify the quality of these plans. The methods were tested as a prostate class solution and compared to replanning and to their current clinical practice. Methods: The proposed VMAT adaptation is an extension of their previous intensity modulated radiotherapy (IMRT) adaptation. It follows a direct (forward) planning approach: the multileaf collimator (MLC) apertures are corrected in the beam’s eye view (BEV) and the monitor units (MUs) are corrected using point dose calculations. All MLC and MU corrections are driven by the positions of four fiducial points only, without need for a full contour set. Quality assurance (QA) of the adapted plans is performed using plan parameters that can be calculated online and that have a relation to the delivered dose or the plan quality. Five potential parameters are studied for this purpose: the number of MU, the equivalent field size (EqFS), the modulation complexity score (MCS), and the components of the MCS: the aperture area variability (AAV) and the leaf sequence variability (LSV). The full adaptation and its separate steps were evaluated in simulation experiments involving a prostate phantom subjected to various interfraction transformations. The efficacy of the current VMAT adaptation was scored by target mean dose (CTV{sub mean}), conformity (CI{sub 95%}), tumor control probability (TCP), and normal tissue complication probability (NTCP). The impact of the adaptation on the plan parameters (QA) was assessed by comparison with prediction intervals (PI) derived from a statistical model of the typical variation of these parameters in a population of VMAT prostate plans (n = 63). These prediction intervals are the adaptation equivalent of the tolerance tables for couch shifts in the current clinical

Online adaptation and verification of VMAT

International Nuclear Information System (INIS)

Crijns, Wouter; Defraene, Gilles; Depuydt, Tom; Haustermans, Karin; Van Herck, Hans; Maes, Frederik; Van den Heuvel, Frank

2015-01-01

Purpose: This work presents a method for fast volumetric modulated arc therapy (VMAT) adaptation in response to interfraction anatomical variations. Additionally, plan parameters extracted from the adapted plans are used to verify the quality of these plans. The methods were tested as a prostate class solution and compared to replanning and to their current clinical practice. Methods: The proposed VMAT adaptation is an extension of their previous intensity modulated radiotherapy (IMRT) adaptation. It follows a direct (forward) planning approach: the multileaf collimator (MLC) apertures are corrected in the beam’s eye view (BEV) and the monitor units (MUs) are corrected using point dose calculations. All MLC and MU corrections are driven by the positions of four fiducial points only, without need for a full contour set. Quality assurance (QA) of the adapted plans is performed using plan parameters that can be calculated online and that have a relation to the delivered dose or the plan quality. Five potential parameters are studied for this purpose: the number of MU, the equivalent field size (EqFS), the modulation complexity score (MCS), and the components of the MCS: the aperture area variability (AAV) and the leaf sequence variability (LSV). The full adaptation and its separate steps were evaluated in simulation experiments involving a prostate phantom subjected to various interfraction transformations. The efficacy of the current VMAT adaptation was scored by target mean dose (CTV mean ), conformity (CI 95% ), tumor control probability (TCP), and normal tissue complication probability (NTCP). The impact of the adaptation on the plan parameters (QA) was assessed by comparison with prediction intervals (PI) derived from a statistical model of the typical variation of these parameters in a population of VMAT prostate plans (n = 63). These prediction intervals are the adaptation equivalent of the tolerance tables for couch shifts in the current clinical practice

Development of on-line uranium enrichment monitor of gaseous UF6 for uranium enrichment plant

International Nuclear Information System (INIS)

Lu Xuesheng; Liu Guorong; Jin Huimin; Zhao Yonggang; Li Jinghuai; Hao Xueyuan; Ying Bin; Yu Zhaofei

2013-01-01

An on-line enrichment monitor was developed to measure the enrichment of UF 6 , flowing through the processing pipes in uranium enrichment plant. A Nal (Tl) detector was used to measure the count rates of the 185.7 keV γ-ray emitted from 235 U, and the total quantity of uranium was determined from thermodynamic characteristics of gaseous uranium hexafluoride. The results show that the maximum relative standard deviation is less than 1% when the measurement time is 120 s or more and the pressure is more than 2 kPa in the measurement chamber. Uranium enrichment of gaseous uranium hexafluoride in the output end of cascade can be monitored continuously by using the device. It should be effective for nuclear materials accountability verifications and materials balance verification at uranium enrichment plant. (authors)

Face Verification for Mobile Personal Devices

NARCIS (Netherlands)

Tao, Q.

2009-01-01

In this thesis, we presented a detailed study of the face verification problem on the mobile device, covering every component of the system. The study includes face detection, registration, normalization, and verification. Furthermore, the information fusion problem is studied to verify face

Gender Verification of Female Olympic Athletes.

Science.gov (United States)

Dickinson, Barry D.; Genel, Myron; Robinowitz, Carolyn B.; Turner, Patricia L.; Woods, Gary L.

2002-01-01

Gender verification of female athletes has long been criticized by geneticists, endocrinologists, and others in the medical community. Recently, the International Olympic Committee's Athletic Commission called for discontinuation of mandatory laboratory-based gender verification of female athletes. This article discusses normal sexual…

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...

Reload core safety verification

International Nuclear Information System (INIS)

Svetlik, M.; Minarcin, M.

2003-01-01

This paper presents a brief look at the process of reload core safety evaluation and verification in Slovak Republic. It gives an overview of experimental verification of selected nuclear parameters in the course of physics testing during reactor start-up. The comparison of IAEA recommendations and testing procedures at Slovak and European nuclear power plants of similar design is included. An introduction of two level criteria for evaluation of tests represents an effort to formulate the relation between safety evaluation and measured values (Authors)

Validation of Embedded System Verification Models

NARCIS (Netherlands)

Marincic, J.; Mader, Angelika H.; Wieringa, Roelf J.

The result of a model-based requirements verification shows that the model of a system satisfies (or not) formalised system requirements. The verification result is correct only if the model represents the system adequately. No matter what modelling technique we use, what precedes the model

On Verification Modelling of Embedded Systems

NARCIS (Netherlands)

Brinksma, Hendrik; Mader, Angelika H.

Computer-aided verification of embedded systems hinges on the availability of good verification models of the systems at hand. Such models must be much simpler than full design models or specifications to be of practical value, because of the unavoidable combinatorial complexities in the

Compositional verification of real-time systems using Ecdar

DEFF Research Database (Denmark)

David, Alexandre; Larsen, Kim Guldstrand; Legay, Axel

2012-01-01

We present a specification theory for timed systems implemented in the Ecdar tool. We illustrate the operations of the specification theory on a running example, showing the models and verification checks. To demonstrate the power of the compositional verification, we perform an in depth case study...... of a leader election protocol; Modeling it in Ecdar as Timed input/output automata Specifications and performing both monolithic and compositional verification of two interesting properties on it. We compare the execution time of the compositional to the classical verification showing a huge difference...

Disarmament Verification - the OPCW Experience

International Nuclear Information System (INIS)

Lodding, J.

2010-01-01

The Chemical Weapons Convention is the only multilateral treaty that bans completely an entire category of weapons of mass destruction under international verification arrangements. Possessor States, i.e. those that have chemical weapons stockpiles at the time of becoming party to the CWC, commit to destroying these. All States undertake never to acquire chemical weapons and not to help other States acquire such weapons. The CWC foresees time-bound chemical disarmament. The deadlines for destruction for early entrants to the CWC are provided in the treaty. For late entrants, the Conference of States Parties intervenes to set destruction deadlines. One of the unique features of the CWC is thus the regime for verifying destruction of chemical weapons. But how can you design a system for verification at military sites, while protecting military restricted information? What degree of assurance is considered sufficient in such circumstances? How do you divide the verification costs? How do you deal with production capability and initial declarations of existing stockpiles? The founders of the CWC had to address these and other challenges in designing the treaty. Further refinement of the verification system has followed since the treaty opened for signature in 1993 and since inspection work was initiated following entry-into-force of the treaty in 1997. Most of this work concerns destruction at the two large possessor States, Russia and the United States. Perhaps some of the lessons learned from the OPCW experience may be instructive in a future verification regime for nuclear weapons. (author)

Verification of Chemical Weapons Destruction

International Nuclear Information System (INIS)

Lodding, J.

2010-01-01

The Chemical Weapons Convention is the only multilateral treaty that bans completely an entire category of weapons of mass destruction under international verification arrangements. Possessor States, i.e. those that have chemical weapons stockpiles at the time of becoming party to the CWC, commit to destroying these. All States undertake never to acquire chemical weapons and not to help other States acquire such weapons. The CWC foresees time-bound chemical disarmament. The deadlines for destruction for early entrants to the CWC are provided in the treaty. For late entrants, the Conference of States Parties intervenes to set destruction deadlines. One of the unique features of the CWC is thus the regime for verifying destruction of chemical weapons. But how can you design a system for verification at military sites, while protecting military restricted information? What degree of assurance is considered sufficient in such circumstances? How do you divide the verification costs? How do you deal with production capability and initial declarations of existing stockpiles? The founders of the CWC had to address these and other challenges in designing the treaty. Further refinement of the verification system has followed since the treaty opened for signature in 1993 and since inspection work was initiated following entry-into-force of the treaty in 1997. Most of this work concerns destruction at the two large possessor States, Russia and the United States. Perhaps some of the lessons learned from the OPCW experience may be instructive in a future verification regime for nuclear weapons. (author)

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.

A Model for Collaborative Runtime Verification

NARCIS (Netherlands)

Testerink, Bas; Bulling, Nils; Dastani, Mehdi

2015-01-01

Runtime verification concerns checking whether a system execution satisfies a given property. In this paper we propose a model for collaborative runtime verification where a network of local monitors collaborates in order to verify properties of the system. A local monitor has only a local view on

HDM/PASCAL Verification System User's Manual

Science.gov (United States)

Hare, D.

1983-01-01

The HDM/Pascal verification system is a tool for proving the correctness of programs written in PASCAL and specified in the Hierarchical Development Methodology (HDM). This document assumes an understanding of PASCAL, HDM, program verification, and the STP system. The steps toward verification which this tool provides are parsing programs and specifications, checking the static semantics, and generating verification conditions. Some support functions are provided such as maintaining a data base, status management, and editing. The system runs under the TOPS-20 and TENEX operating systems and is written in INTERLISP. However, no knowledge is assumed of these operating systems or of INTERLISP. The system requires three executable files, HDMVCG, PARSE, and STP. Optionally, the editor EMACS should be on the system in order for the editor to work. The file HDMVCG is invoked to run the system. The files PARSE and STP are used as lower forks to perform the functions of parsing and proving.

Self-verification and contextualized self-views.

Science.gov (United States)

Chen, Serena; English, Tammy; Peng, Kaiping

2006-07-01

Whereas most self-verification research has focused on people's desire to verify their global self-conceptions, the present studies examined self-verification with regard to contextualized selfviews-views of the self in particular situations and relationships. It was hypothesized that individuals whose core self-conceptions include contextualized self-views should seek to verify these self-views. In Study 1, the more individuals defined the self in dialectical terms, the more their judgments were biased in favor of verifying over nonverifying feedback about a negative, situation-specific self-view. In Study 2, consistent with research on gender differences in the importance of relationships to the self-concept, women but not men showed a similar bias toward feedback about a negative, relationship-specific self-view, a pattern not seen for global self-views. Together, the results support the notion that self-verification occurs for core self-conceptions, whatever form(s) they may take. Individual differences in self-verification and the nature of selfhood and authenticity are discussed.

Verification of RESRAD-build computer code, version 3.1

International Nuclear Information System (INIS)

2003-01-01

RESRAD-BUILD is a computer model for analyzing the radiological doses resulting from the remediation and occupancy of buildings contaminated with radioactive material. It is part of a family of codes that includes RESRAD, RESRAD-CHEM, RESRAD-RECYCLE, RESRAD-BASELINE, and RESRAD-ECORISK. The RESRAD-BUILD models were developed and codified by Argonne National Laboratory (ANL); version 1.5 of the code and the user's manual were publicly released in 1994. The original version of the code was written for the Microsoft DOS operating system. However, subsequent versions of the code were written for the Microsoft Windows operating system. The purpose of the present verification task (which includes validation as defined in the standard) is to provide an independent review of the latest version of RESRAD-BUILD under the guidance provided by ANSI/ANS-10.4 for verification and validation of existing computer programs. This approach consists of a posteriori V and V review which takes advantage of available program development products as well as user experience. The purpose, as specified in ANSI/ANS-10.4, is to determine whether the program produces valid responses when used to analyze problems within a specific domain of applications, and to document the level of verification. The culmination of these efforts is the production of this formal Verification Report. The first step in performing the verification of an existing program was the preparation of a Verification Review Plan. The review plan consisted of identifying: Reason(s) why a posteriori verification is to be performed; Scope and objectives for the level of verification selected; Development products to be used for the review; Availability and use of user experience; and Actions to be taken to supplement missing or unavailable development products. The purpose, scope and objectives for the level of verification selected are described in this section of the Verification Report. The development products that were used

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.

A Verification Logic for GOAL Agents

Science.gov (United States)

Hindriks, K. V.

Although there has been a growing body of literature on verification of agents programs, it has been difficult to design a verification logic for agent programs that fully characterizes such programs and to connect agent programs to agent theory. The challenge is to define an agent programming language that defines a computational framework but also allows for a logical characterization useful for verification. The agent programming language GOAL has been originally designed to connect agent programming to agent theory and we present additional results here that GOAL agents can be fully represented by a logical theory. GOAL agents can thus be said to execute the corresponding logical theory.

Secure optical verification using dual phase-only correlation

International Nuclear Information System (INIS)

Liu, Wei; Liu, Shutian; Zhang, Yan; Xie, Zhenwei; Liu, Zhengjun

2015-01-01

We introduce a security-enhanced optical verification system using dual phase-only correlation based on a novel correlation algorithm. By employing a nonlinear encoding, the inherent locks of the verification system are obtained in real-valued random distributions, and the identity keys assigned to authorized users are designed as pure phases. The verification process is implemented in two-step correlation, so only authorized identity keys can output the discriminate auto-correlation and cross-correlation signals that satisfy the reset threshold values. Compared with the traditional phase-only-correlation-based verification systems, a higher security level against counterfeiting and collisions are obtained, which is demonstrated by cryptanalysis using known attacks, such as the known-plaintext attack and the chosen-plaintext attack. Optical experiments as well as necessary numerical simulations are carried out to support the proposed verification method. (paper)

Verification of DRAGON: the NXT tracking module

International Nuclear Information System (INIS)

Zkiek, A.; Marleau, G.

2007-01-01

The version of DRAGON-IST that has been verified for the calculation of the incremental cross sections associated with CANDU reactivity devices is version 3.04Bb that was released in 2001. Since then, various improvements were implemented in the code including the NXT: module that can track assemblies of clusters in 2-D and 3-D geometries. Here we will discuss the verification plan for the NXT: module of DRAGON, illustrate the verification procedure we selected and present our verification results. (author)

Technical challenges for dismantlement verification

International Nuclear Information System (INIS)

Olinger, C.T.; Stanbro, W.D.; Johnston, R.G.; Nakhleh, C.W.; Dreicer, J.S.

1997-01-01

In preparation for future nuclear arms reduction treaties, including any potential successor treaties to START I and II, the authors have been examining possible methods for bilateral warhead dismantlement verification. Warhead dismantlement verification raises significant challenges in the political, legal, and technical arenas. This discussion will focus on the technical issues raised by warhead arms controls. Technical complications arise from several sources. These will be discussed under the headings of warhead authentication, chain-of-custody, dismantlement verification, non-nuclear component tracking, component monitoring, and irreversibility. The authors will discuss possible technical options to address these challenges as applied to a generic dismantlement and disposition process, in the process identifying limitations and vulnerabilities. They expect that these considerations will play a large role in any future arms reduction effort and, therefore, should be addressed in a timely fashion

Safety Verification for Probabilistic Hybrid Systems

DEFF Research Database (Denmark)

Zhang, Lijun; She, Zhikun; Ratschan, Stefan

2010-01-01

The interplay of random phenomena and continuous real-time control deserves increased attention for instance in wireless sensing and control applications. Safety verification for such systems thus needs to consider probabilistic variations of systems with hybrid dynamics. In safety verification o...... on a number of case studies, tackled using a prototypical implementation....

SSN Verification Service

Data.gov (United States)

Social Security Administration — The SSN Verification Service is used by Java applications to execute the GUVERF02 service using the WebSphere/CICS Interface. It accepts several input data fields...

Enhanced Verification Test Suite for Physics Simulation Codes

Energy Technology Data Exchange (ETDEWEB)

Kamm, J R; Brock, J S; Brandon, S T; Cotrell, D L; Johnson, B; Knupp, P; Rider, W; Trucano, T; Weirs, V G

2008-10-10

This document discusses problems with which to augment, in quantity and in quality, the existing tri-laboratory suite of verification problems used by Los Alamos National Laboratory (LANL), Lawrence Livermore National Laboratory (LLNL), and Sandia National Laboratories (SNL). The purpose of verification analysis is demonstrate whether the numerical results of the discretization algorithms in physics and engineering simulation codes provide correct solutions of the corresponding continuum equations. The key points of this document are: (1) Verification deals with mathematical correctness of the numerical algorithms in a code, while validation deals with physical correctness of a simulation in a regime of interest. This document is about verification. (2) The current seven-problem Tri-Laboratory Verification Test Suite, which has been used for approximately five years at the DOE WP laboratories, is limited. (3) Both the methodology for and technology used in verification analysis have evolved and been improved since the original test suite was proposed. (4) The proposed test problems are in three basic areas: (a) Hydrodynamics; (b) Transport processes; and (c) Dynamic strength-of-materials. (5) For several of the proposed problems we provide a 'strong sense verification benchmark', consisting of (i) a clear mathematical statement of the problem with sufficient information to run a computer simulation, (ii) an explanation of how the code result and benchmark solution are to be evaluated, and (iii) a description of the acceptance criterion for simulation code results. (6) It is proposed that the set of verification test problems with which any particular code be evaluated include some of the problems described in this document. Analysis of the proposed verification test problems constitutes part of a necessary--but not sufficient--step that builds confidence in physics and engineering simulation codes. More complicated test cases, including physics models of

An Efficient Authentication Method For Smart Card Verification In Online

Directory of Open Access Journals (Sweden)

Kanamarlapudi Venkata Srinivasa Rao

2017-08-01

Full Text Available The great cards are getting a charge out of a critical part inside the on-line managing wherever we have tendency to can’t check the cardholder up close and personal. The phishing sites may parody the data in the middle of the customer website and along these lines the common webpage. To protect the data and managing here we have tendency to are presenting the three level confirmations. In arranged approach there are two stages i.e. Enlistment and login. All through enlistment part control the word which can figure and separated into two segments i.e. parcel one can keep inside the client or customer viewpoint, segment a couple of can keep in server perspective. Next level is to exchange the client icon which can figure and split into two shares each are keep severally. In the end zero information code will be get refreshed and it’s furthermore get keep as two components. All through the login part before starting the managing the client and server ought to uncover their three-genuine data offers if each stacked data got coordinate then the client is legitimate and server isn’t a phishing site.

Lessons Learned From Microkernel Verification — Specification is the New Bottleneck

Directory of Open Access Journals (Sweden)

Thorsten Bormer

2012-11-01

Full Text Available Software verification tools have become a lot more powerful in recent years. Even verification of large, complex systems is feasible, as demonstrated in the L4.verified and Verisoft XT projects. Still, functional verification of large software systems is rare – for reasons beyond the large scale of verification effort needed due to the size alone. In this paper we report on lessons learned for verification of large software systems based on the experience gained in microkernel verification in the Verisoft XT project. We discuss a number of issues that impede widespread introduction of formal verification in the software life-cycle process.

Advancing Disarmament Verification Tools: A Task for Europe?

International Nuclear Information System (INIS)

Göttsche, Malte; Kütt, Moritz; Neuneck, Götz; Niemeyer, Irmgard

2015-01-01

A number of scientific-technical activities have been carried out to establish more robust and irreversible disarmament verification schemes. Regardless of the actual path towards deeper reductions in nuclear arsenals or their total elimination in the future, disarmament verification will require new verification procedures and techniques. This paper discusses the information that would be required as a basis for building confidence in disarmament, how it could be principally verified and the role Europe could play. Various ongoing activities are presented that could be brought together to produce a more intensified research and development environment in Europe. The paper argues that if ‘effective multilateralism’ is the main goal of the European Union’s (EU) disarmament policy, EU efforts should be combined and strengthened to create a coordinated multilateral disarmament verification capacity in the EU and other European countries. The paper concludes with several recommendations that would have a significant impact on future developments. Among other things, the paper proposes a one-year review process that should include all relevant European actors. In the long run, an EU Centre for Disarmament Verification could be envisaged to optimize verification needs, technologies and procedures.

The verification of DRAGON: progress and lessons learned

International Nuclear Information System (INIS)

Marleau, G.

2002-01-01

The general requirements for the verification of the legacy code DRAGON are somewhat different from those used for new codes. For example, the absence of a design manual for DRAGON makes it difficult to confirm that the each part of the code performs as required since these requirements are not explicitly spelled out for most of the DRAGON modules. In fact, this conformance of the code can only be assessed, in most cases, by making sure that the contents of the DRAGON data structures, which correspond to the output generated by a module of the code, contains the adequate information. It is also possible in some cases to use the self-verification options in DRAGON to perform additional verification or to evaluate, using an independent software, the performance of specific functions in the code. Here, we will describe the global verification process that was considered in order to bring DRAGON to an industry standard tool-set (IST) status. We will also discuss some of the lessons we learned in performing this verification and present some of the modification to DRAGON that were implemented as a consequence of this verification. (author)

Simulation Environment Based on the Universal Verification Methodology

CERN Document Server

AUTHOR|(SzGeCERN)697338

2017-01-01

Universal Verification Methodology (UVM) is a standardized approach of verifying integrated circuit designs, targeting a Coverage-Driven Verification (CDV). It combines automatic test generation, self-checking testbenches, and coverage metrics to indicate progress in the design verification. The flow of the CDV differs from the traditional directed-testing approach. With the CDV, a testbench developer, by setting the verification goals, starts with an structured plan. Those goals are targeted further by a developed testbench, which generates legal stimuli and sends them to a device under test (DUT). The progress is measured by coverage monitors added to the simulation environment. In this way, the non-exercised functionality can be identified. Moreover, the additional scoreboards indicate undesired DUT behaviour. Such verification environments were developed for three recent ASIC and FPGA projects which have successfully implemented the new work-flow: (1) the CLICpix2 65 nm CMOS hybrid pixel readout ASIC desi...

Hierarchical Representation Learning for Kinship Verification.

Science.gov (United States)

Kohli, Naman; Vatsa, Mayank; Singh, Richa; Noore, Afzel; Majumdar, Angshul

2017-01-01

Kinship verification has a number of applications such as organizing large collections of images and recognizing resemblances among humans. In this paper, first, a human study is conducted to understand the capabilities of human mind and to identify the discriminatory areas of a face that facilitate kinship-cues. The visual stimuli presented to the participants determine their ability to recognize kin relationship using the whole face as well as specific facial regions. The effect of participant gender and age and kin-relation pair of the stimulus is analyzed using quantitative measures such as accuracy, discriminability index d' , and perceptual information entropy. Utilizing the information obtained from the human study, a hierarchical kinship verification via representation learning (KVRL) framework is utilized to learn the representation of different face regions in an unsupervised manner. We propose a novel approach for feature representation termed as filtered contractive deep belief networks (fcDBN). The proposed feature representation encodes relational information present in images using filters and contractive regularization penalty. A compact representation of facial images of kin is extracted as an output from the learned model and a multi-layer neural network is utilized to verify the kin accurately. A new WVU kinship database is created, which consists of multiple images per subject to facilitate kinship verification. The results show that the proposed deep learning framework (KVRL-fcDBN) yields the state-of-the-art kinship verification accuracy on the WVU kinship database and on four existing benchmark data sets. Furthermore, kinship information is used as a soft biometric modality to boost the performance of face verification via product of likelihood ratio and support vector machine based approaches. Using the proposed KVRL-fcDBN framework, an improvement of over 20% is observed in the performance of face verification.

Self-verification motives at the collective level of self-definition.

Science.gov (United States)

Chen, Serena; Chen, Karen Y; Shaw, Lindsay

2004-01-01

Three studies examined self-verification motives in relation to collective aspects of the self. Several moderators of collective self-verification were also examined--namely, the certainty with which collective self-views are held, the nature of one's ties to a source of self-verification, the salience of the collective self, and the importance of group identification. Evidence for collective self-verification emerged across all studies, particularly when collective self-views were held with high certainty (Studies 1 and 2), perceivers were somehow tied to the source of self-verification (Study 1), the collective self was salient (Study 2), and group identification was important (Study 3). To the authors' knowledge, these studies are the first to examine self-verification at the collective level of self-definition. The parallel and distinct ways in which self-verification processes may operate at different levels of self-definition are discussed.

24 CFR 5.512 - Verification of eligible immigration status.

Science.gov (United States)

2010-04-01

... immigration status. 5.512 Section 5.512 Housing and Urban Development Office of the Secretary, Department of... Noncitizens § 5.512 Verification of eligible immigration status. (a) General. Except as described in paragraph...) Primary verification—(1) Automated verification system. Primary verification of the immigration status of...

Verification of RADTRAN

International Nuclear Information System (INIS)

Kanipe, F.L.; Neuhauser, K.S.

1995-01-01

This document presents details of the verification process of the RADTRAN computer code which was established for the calculation of risk estimates for radioactive materials transportation by highway, rail, air, and waterborne modes

CASL Verification and Validation Plan

Energy Technology Data Exchange (ETDEWEB)

Mousseau, Vincent Andrew [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Dinh, Nam [North Carolina State Univ., Raleigh, NC (United States)

2016-06-30

This report documents the Consortium for Advanced Simulation of LWRs (CASL) verification and validation plan. The document builds upon input from CASL subject matter experts, most notably the CASL Challenge Problem Product Integrators, CASL Focus Area leaders, and CASL code development and assessment teams. This document will be a living document that will track progress on CASL to do verification and validation for both the CASL codes (including MPACT, CTF, BISON, MAMBA) and for the CASL challenge problems (CIPS, PCI, DNB). The CASL codes and the CASL challenge problems are at differing levels of maturity with respect to validation and verification. The gap analysis will summarize additional work that needs to be done. Additional VVUQ work will be done as resources permit. This report is prepared for the Department of Energy’s (DOE’s) CASL program in support of milestone CASL.P13.02.

The monitoring and verification of nuclear weapons

International Nuclear Information System (INIS)

Garwin, Richard L.

2014-01-01

This paper partially reviews and updates the potential for monitoring and verification of nuclear weapons, including verification of their destruction. Cooperative monitoring with templates of the gamma-ray spectrum are an important tool, dependent on the use of information barriers

DarcyTools, Version 2.1. Verification and validation

International Nuclear Information System (INIS)

Svensson, Urban

2004-03-01

DarcyTools is a computer code for simulation of flow and transport in porous and/or fractured media. The fractured media in mind is a fractured rock and the porous media the soil cover on the top of the rock; it is hence groundwater flows, which is the class of flows in mind. A number of novel methods and features form the present version of DarcyTools. In the verification studies, these methods are evaluated by comparisons with analytical solutions for idealized situations. The five verification groups, thus reflect the main areas of recent developments. The present report will focus on the Verification and Validation of DarcyTools. Two accompanying reports cover other aspects: - Concepts, Methods, Equations and Demo Simulations. - User's Guide. The objective of this report is to compile all verification and validation studies that have been carried out so far. After some brief introductory sections, all cases will be reported in Appendix A (verification cases) and Appendix B (validation cases)

Verification and quality control of routine hematology analyzers.

Science.gov (United States)

Vis, J Y; Huisman, A

2016-05-01

Verification of hematology analyzers (automated blood cell counters) is mandatory before new hematology analyzers may be used in routine clinical care. The verification process consists of several items which comprise among others: precision, accuracy, comparability, carryover, background and linearity throughout the expected range of results. Yet, which standard should be met or which verification limit be used is at the discretion of the laboratory specialist. This paper offers practical guidance on verification and quality control of automated hematology analyzers and provides an expert opinion on the performance standard that should be met by the contemporary generation of hematology analyzers. Therefore (i) the state-of-the-art performance of hematology analyzers for complete blood count parameters is summarized, (ii) considerations, challenges, and pitfalls concerning the development of a verification plan are discussed, (iii) guidance is given regarding the establishment of reference intervals, and (iv) different methods on quality control of hematology analyzers are reviewed. © 2016 John Wiley & Sons Ltd.

DarcyTools, Version 2.1. Verification and validation

Energy Technology Data Exchange (ETDEWEB)

Svensson, Urban [Computer-aided Fluid Engineering AB, Norrkoeping (Sweden)

2004-03-01

DarcyTools is a computer code for simulation of flow and transport in porous and/or fractured media. The fractured media in mind is a fractured rock and the porous media the soil cover on the top of the rock; it is hence groundwater flows, which is the class of flows in mind. A number of novel methods and features form the present version of DarcyTools. In the verification studies, these methods are evaluated by comparisons with analytical solutions for idealized situations. The five verification groups, thus reflect the main areas of recent developments. The present report will focus on the Verification and Validation of DarcyTools. Two accompanying reports cover other aspects: - Concepts, Methods, Equations and Demo Simulations. - User's Guide. The objective of this report is to compile all verification and validation studies that have been carried out so far. After some brief introductory sections, all cases will be reported in Appendix A (verification cases) and Appendix B (validation cases)

Verification-Based Interval-Passing Algorithm for Compressed Sensing

OpenAIRE

Wu, Xiaofu; Yang, Zhen

2013-01-01

We propose a verification-based Interval-Passing (IP) algorithm for iteratively reconstruction of nonnegative sparse signals using parity check matrices of low-density parity check (LDPC) codes as measurement matrices. The proposed algorithm can be considered as an improved IP algorithm by further incorporation of the mechanism of verification algorithm. It is proved that the proposed algorithm performs always better than either the IP algorithm or the verification algorithm. Simulation resul...

Multi-canister overpack project - verification and validation, MCNP 4A

International Nuclear Information System (INIS)

Goldmann, L.H.

1997-01-01

This supporting document contains the software verification and validation (V and V) package used for Phase 2 design of the Spent Nuclear Fuel Multi-Canister Overpack. V and V packages for both ANSYS and MCNP are included. Description of Verification Run(s): This software requires that it be compiled specifically for the machine it is to be used on. Therefore to facilitate ease in the verification process the software automatically runs 25 sample problems to ensure proper installation and compilation. Once the runs are completed the software checks for verification by performing a file comparison on the new output file and the old output file. Any differences between any of the files will cause a verification error. Due to the manner in which the verification is completed a verification error does not necessarily indicate a problem. This indicates that a closer look at the output files is needed to determine the cause of the error

The accuracy of CT-based inhomogeneity corrections and in vivo dosimetry for the treatment of lung cancer

International Nuclear Information System (INIS)

Essers, M.; Lanson, J.H.; Leunens, G.; Schnabel, T.; Mijnheer, B.J.

1995-01-01

Purpose: To determine the accuracy of dose calculations based on CT-densities for lung cancer patients irradiated with an anterioposterior parallel-opposed treatment technique and to evaluate, for this technique, the use of diodes and an Electronic Portal Imaging Device (EPID) for absolute exit dose and relative transmission dose verification, respectively. Materials and methods: Dose calculations were performed using a 3-dimensional treatment planning system, using CT-densities or assuming the patient to be water-equivalent. A simple inhomogeneity correction model was used to take CT-densities into account. For 22 patients, entrance and exit dose calculations at the central beam axis and at several off-axis positions were compared with diode measurements. For 12 patients, diode exit dose measurements and exit dose calculations were compared with EPID transmission dose values. Results: Using water-equivalent calculations, the actual exit dose value under lung was, on average, underestimated by 30%, with an overall spread of 10% (1 SD) in the ratio of measurement and calculation. Using inhomogeneity corrections, the exit dose was, on average, overestimated by 4%, with an overall spread of 6% (1 SD). Only 2% of the average deviation was due to the inhomogeneity correction model. The other 2% resulted from a small inaccuracy in beam fit parameters and the fact that lack of backscatter is not taken into account by the calculation model. Organ motion, resulting from the ventilatory or cardiac cycle, caused an estimated uncertainty in calculated exit dose of 2.5% (1 SD). The most important reason for the large overall spread was, however, the inaccuracy involved in point measurements, of about 4% (1 SD), which resulted from the systematic and random deviation in patient set-up and therefore in the diode position with respect to patient anatomy. Transmission and exit dose values agreed with an average difference of 1.1%. Transmission dose profiles also showed good

Runtime verification of embedded real-time systems.

Science.gov (United States)

Reinbacher, Thomas; Függer, Matthias; Brauer, Jörg

We present a runtime verification framework that allows on-line monitoring of past-time Metric Temporal Logic (ptMTL) specifications in a discrete time setting. We design observer algorithms for the time-bounded modalities of ptMTL, which take advantage of the highly parallel nature of hardware designs. The algorithms can be translated into efficient hardware blocks, which are designed for reconfigurability, thus, facilitate applications of the framework in both a prototyping and a post-deployment phase of embedded real-time systems. We provide formal correctness proofs for all presented observer algorithms and analyze their time and space complexity. For example, for the most general operator considered, the time-bounded Since operator, we obtain a time complexity that is doubly logarithmic both in the point in time the operator is executed and the operator's time bounds. This result is promising with respect to a self-contained, non-interfering monitoring approach that evaluates real-time specifications in parallel to the system-under-test. We implement our framework on a Field Programmable Gate Array platform and use extensive simulation and logic synthesis runs to assess the benefits of the approach in terms of resource usage and operating frequency.

Key Nuclear Verification Priorities: Safeguards and Beyond

International Nuclear Information System (INIS)

Carlson, J.

2010-01-01

In addressing nuclear verification priorities, we should look beyond the current safeguards system. Non-proliferation, which the safeguards system underpins, is not an end in itself, but an essential condition for achieving and maintaining nuclear disarmament. Effective safeguards are essential for advancing disarmament, and safeguards issues, approaches and techniques are directly relevant to the development of future verification missions. The extent to which safeguards challenges are successfully addressed - or otherwise - will impact not only on confidence in the safeguards system, but on the effectiveness of, and confidence in, disarmament verification. To identify the key nuclear verification priorities, we need to consider the objectives of verification, and the challenges to achieving these. The strategic objective of IAEA safeguards might be expressed as: To support the global nuclear non-proliferation regime by: - Providing credible assurance that states are honouring their safeguards commitments - thereby removing a potential motivation to proliferate; and - Early detection of misuse of nuclear material and technology - thereby deterring proliferation by the risk of early detection, enabling timely intervention by the international community. Or to summarise - confidence-building, detection capability, and deterrence. These will also be essential objectives for future verification missions. The challenges to achieving these involve a mix of political, technical and institutional dimensions. Confidence is largely a political matter, reflecting the qualitative judgment of governments. Clearly assessments of detection capability and deterrence have a major impact on confidence. Detection capability is largely thought of as 'technical', but also involves issues of legal authority, as well as institutional issues. Deterrence has both political and institutional aspects - including judgments on risk of detection and risk of enforcement action being taken. The

Key Nuclear Verification Priorities - Safeguards and Beyond

International Nuclear Information System (INIS)

Carlson, J.

2010-01-01

In addressing nuclear verification priorities, we should look beyond the current safeguards system. Non-proliferation, which the safeguards system underpins, is not an end in itself, but an essential condition for achieving and maintaining nuclear disarmament. Effective safeguards are essential for advancing disarmament, and safeguards issues, approaches and techniques are directly relevant to the development of future verification missions. The extent to which safeguards challenges are successfully addressed - or otherwise - will impact not only on confidence in the safeguards system, but on the effectiveness of, and confidence in, disarmament verification. To identify the key nuclear verification priorities, we need to consider the objectives of verification, and the challenges to achieving these. The strategic objective of IAEA safeguards might be expressed as: To support the global nuclear non-proliferation regime by: - Providing credible assurance that states are honouring their safeguards commitments - thereby removing a potential motivation to proliferate; and - Early detection of misuse of nuclear material and technology - thereby deterring proliferation by the risk of early detection, enabling timely intervention by the international community. Or to summarise - confidence-building, detection capability, and deterrence. These will also be essential objectives for future verification missions. The challenges to achieving these involve a mix of political, technical and institutional dimensions. Confidence is largely a political matter, reflecting the qualitative judgment of governments. Clearly assessments of detection capability and deterrence have a major impact on confidence. Detection capability is largely thought of as 'technical', but also involves issues of legal authority, as well as institutional issues. Deterrence has both political and institutional aspects - including judgments on risk of detection and risk of enforcement action being taken. The

On the organisation of program verification competitions

NARCIS (Netherlands)

Huisman, Marieke; Klebanov, Vladimir; Monahan, Rosemary; Klebanov, Vladimir; Beckert, Bernhard; Biere, Armin; Sutcliffe, Geoff

In this paper, we discuss the challenges that have to be addressed when organising program verification competitions. Our focus is on competitions for verification systems where the participants both formalise an informally stated requirement and (typically) provide some guidance for the tool to

Simulation environment based on the Universal Verification Methodology

International Nuclear Information System (INIS)

Fiergolski, A.

2017-01-01

Universal Verification Methodology (UVM) is a standardized approach of verifying integrated circuit designs, targeting a Coverage-Driven Verification (CDV). It combines automatic test generation, self-checking testbenches, and coverage metrics to indicate progress in the design verification. The flow of the CDV differs from the traditional directed-testing approach. With the CDV, a testbench developer, by setting the verification goals, starts with an structured plan. Those goals are targeted further by a developed testbench, which generates legal stimuli and sends them to a device under test (DUT). The progress is measured by coverage monitors added to the simulation environment. In this way, the non-exercised functionality can be identified. Moreover, the additional scoreboards indicate undesired DUT behaviour. Such verification environments were developed for three recent ASIC and FPGA projects which have successfully implemented the new work-flow: (1) the CLICpix2 65 nm CMOS hybrid pixel readout ASIC design; (2) the C3PD 180 nm HV-CMOS active sensor ASIC design; (3) the FPGA-based DAQ system of the CLICpix chip. This paper, based on the experience from the above projects, introduces briefly UVM and presents a set of tips and advices applicable at different stages of the verification process-cycle.

Feasibility study of image guided radiotherapy for lung tumor using online and offline cone-beam CT setup verification

International Nuclear Information System (INIS)

Li Hongsheng; Li Baosheng; Lu Jie; Yin Yong; Yu Ningsha; Chen Yiru

2009-01-01

Objective: To investigate the feasibility of online and offline cone-beam CT(CBCT) guided radiotherapy for lung cancer. Methods: Fourteen patients with lung tumor treated by three-dimensional conformal radiotherapy were investigated. Online kV CBCT scan, image registration and setup correction were performed before and immediately after radiotherapy. CBCT online-guided correction data were used to calculate the population-based CTV-PTV margins under the condition of non-correction and correction in every fraction respectively. The numbers of initial images and the population-based CTV-PTV margins after the offline compensation of the system setup error were evaluated with the permission of 0.5 mm and 1.5 mm maximal residue error, respectively. Results: Under the condition of non-correction, the required margins for total error were 5.7 mm, 8.0 mm and 7.8 mm in the left-right (x axis), cranio-caudal (y axis) and anterior-posterior(z axis) directions, respectively. When the tumor was corrected in every fraction, the required margins for intra-fraction error were 2.4 mm, 2.4 mm and 2.3 mm in x,y and z axes, respectively. To correct the systematic setup error, 9 sets of CBCT images for 3.3 mm, 3.7 mm and 3.6 mm PTV margins, and 7 sets of CBCT images for 3.9 mm, 4.3 mm and 4.3 mm PTV margins in x,y and z axes were necessary when 0.5 mm and 1.5 mm maximal residue error were permitted respectively. Conclusions: Both of the online CBCT correction and the offline adaptive correction can markedly reduce the impact of setup error and reduce the required PTV margins accordingly. It is feasible to deliver the online and offline image guided radiation for patients with lung tumor. (authors)

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)

HTGR analytical methods and design verification

International Nuclear Information System (INIS)

Neylan, A.J.; Northup, T.E.

1982-05-01

Analytical methods for the high-temperature gas-cooled reactor (HTGR) include development, update, verification, documentation, and maintenance of all computer codes for HTGR design and analysis. This paper presents selected nuclear, structural mechanics, seismic, and systems analytical methods related to the HTGR core. This paper also reviews design verification tests in the reactor core, reactor internals, steam generator, and thermal barrier

IMRT plan verification in radiotherapy

International Nuclear Information System (INIS)

Vlk, P.

2006-01-01

This article describes the procedure for verification of IMRT (Intensity modulated radiation therapy) plan, which is used in the Oncological Institute of St. Elisabeth in Bratislava. It contains basic description of IMRT technology and developing a deployment plan for IMRT planning system CORVUS 6.0, the device Mimic (Multilammelar intensity modulated collimator) and the overall process of verifying the schedule created. The aim of verification is particularly good control of the functions of MIMIC and evaluate the overall reliability of IMRT planning. (author)

Automatic Verification of Timing Constraints for Safety Critical Space Systems

Science.gov (United States)

Fernandez, Javier; Parra, Pablo; Sanchez Prieto, Sebastian; Polo, Oscar; Bernat, Guillem

2015-09-01

In this paper is presented an automatic process of verification. We focus in the verification of scheduling analysis parameter. This proposal is part of process based on Model Driven Engineering to automate a Verification and Validation process of the software on board of satellites. This process is implemented in a software control unit of the energy particle detector which is payload of Solar Orbiter mission. From the design model is generated a scheduling analysis model and its verification model. The verification as defined as constraints in way of Finite Timed Automatas. When the system is deployed on target the verification evidence is extracted as instrumented points. The constraints are fed with the evidence, if any of the constraints is not satisfied for the on target evidence the scheduling analysis is not valid.

A framework for nuclear agreement and verification

International Nuclear Information System (INIS)

Ali, A.

1991-01-01

This chapter assesses the prospects for a nuclear agreement between India and Pakistan. The chapter opens with a review of past and present political environments of the two countries. The discussion proceeds to describe the linkage of global arms control agreements, prospects for verification of a Comprehensive Test Ban Treaty, the role of nuclear power in any agreements, the intrusiveness of verification, and possible post-proliferation agreements. Various monitoring and verification technologies are described (mainly satellite oriented). The chapter concludes with an analysis of the likelihood of persuading India and Pakistan to agree to a nonproliferation arrangement

Verification of Many-Qubit States

Directory of Open Access Journals (Sweden)

Yuki Takeuchi

2018-06-01

Full Text Available Verification is a task to check whether a given quantum state is close to an ideal state or not. In this paper, we show that a variety of many-qubit quantum states can be verified with only sequential single-qubit measurements of Pauli operators. First, we introduce a protocol for verifying ground states of Hamiltonians. We next explain how to verify quantum states generated by a certain class of quantum circuits. We finally propose an adaptive test of stabilizers that enables the verification of all polynomial-time-generated hypergraph states, which include output states of the Bremner-Montanaro-Shepherd-type instantaneous quantum polynomial time (IQP circuits. Importantly, we do not make any assumption that the identically and independently distributed copies of the same states are given: Our protocols work even if some highly complicated entanglement is created among copies in any artificial way. As applications, we consider the verification of the quantum computational supremacy demonstration with IQP models, and verifiable blind quantum computing.

Formal Verification -26 ...

Indian Academy of Sciences (India)

by testing of the components and successful testing leads to the software being ... Formal verification is based on formal methods which are mathematically based ..... scenario under which a similar error could occur. There are various other ...

Verification of wet blasting decontamination technology

International Nuclear Information System (INIS)

Matsubara, Sachito; Murayama, Kazunari; Yoshida, Hirohisa; Igei, Shigemitsu; Izumida, Tatsuo

2013-01-01

Macoho Co., Ltd. participated in the projects of 'Decontamination Verification Test FY 2011 by the Ministry of the Environment' and 'Decontamination Verification Test FY 2011 by the Cabinet Office.' And we tested verification to use a wet blasting technology for decontamination of rubble and roads contaminated by the accident of Fukushima Daiichi Nuclear Power Plant of the Tokyo Electric Power Company. As a results of the verification test, the wet blasting decontamination technology showed that a decontamination rate became 60-80% for concrete paving, interlocking, dense-grated asphalt pavement when applied to the decontamination of the road. When it was applied to rubble decontamination, a decontamination rate was 50-60% for gravel and approximately 90% for concrete and wood. It was thought that Cs-134 and Cs-137 attached to the fine sludge scraped off from a decontamination object and the sludge was found to be separated from abrasives by wet cyclene classification: the activity concentration of the abrasives is 1/30 or less than the sludge. The result shows that the abrasives can be reused without problems when the wet blasting decontamination technology is used. (author)

Image-guided intensity-modulated radiotherapy of prostate cancer. Analysis of interfractional errors and acute toxicity

Energy Technology Data Exchange (ETDEWEB)

Rudat, Volker; Nour, A.; Hammoud, M.; Alaradi, A.; Mohammed, A. [Saad Specialist Hospital, Department of Radiation Oncology, Al Khobar (Saudi Arabia)

2016-02-15

The aim of the study was to estimate interfractional deviations in patient and prostate position, the impact of the frequency of online verification on the treatment margins, and to assess acute radiation reactions of high-dose external beam image-guided intensity-modulated radiotherapy (IG-IMRT) of localized prostate cancer. IG-IMRT was performed by daily online verification of implanted fiducial prostate markers using a megavoltage electronic portal imaging device (EPID). A total of 1011 image-guided treatment fractions from 23 consecutive unselected prostate cancer patients were analyzed. The median total dose was 79.2 Gy (range 77.4-81.0 Gy). Acute radiation reactions were assessed weekly during radiotherapy using the Common Terminology Criteria for Adverse Events (CTCAE) v.4.03. A relevant combined patient set-up and prostate motion population random error of 4-5 mm was observed. Compared to daily IGRT, image guidance every other day required an expansion of the CTV-PTV (clinical target volume-planning target volume) margin of 8.1, 6.6, and 4.1 mm in the longitudinal, vertical, and lateral directions, thereby, increasing the PTV by approximately 30-40 %. No grade 3 or 4 acute radiation reactions were observed with daily IG-IMRT. A high dose with surprisingly low acute toxicity can be applied with daily IG-IMRT using implanted fiducial prostate markers. Daily image guidance is clearly superior to image guidance every other fraction concerning adequate target coverage with minimal margins. (orig.) [German] Ziel der Studie war es, die interfraktionelle Variabilitaet der Patientenlagerung und Prostataposition, den Einfluss der Bildgebungsfrequenz und die akuten Strahlenreaktionen bei einer hochdosierten bildgesteuerten intensitaetsmodulierten Strahlentherapie (IG-IMRT) des Prostatakarzinoms zu untersuchen. IG-IMRT wurde durch taegliche Verifikation von implantierten roentgendichten Prostatamarkern mittels Megavolt-Bildgebung (''electronic portal imaging

Robust Digital Speech Watermarking For Online Speaker Recognition

Directory of Open Access Journals (Sweden)

Mohammad Ali Nematollahi

2015-01-01

Full Text Available A robust and blind digital speech watermarking technique has been proposed for online speaker recognition systems based on Discrete Wavelet Packet Transform (DWPT and multiplication to embed the watermark in the amplitudes of the wavelet’s subbands. In order to minimize the degradation effect of the watermark, these subbands are selected where less speaker-specific information was available (500 Hz–3500 Hz and 6000 Hz–7000 Hz. Experimental results on Texas Instruments Massachusetts Institute of Technology (TIMIT, Massachusetts Institute of Technology (MIT, and Mobile Biometry (MOBIO show that the degradation for speaker verification and identification is 1.16% and 2.52%, respectively. Furthermore, the proposed watermark technique can provide enough robustness against different signal processing attacks.

K Basins Field Verification Program

International Nuclear Information System (INIS)

Booth, H.W.

1994-01-01

The Field Verification Program establishes a uniform and systematic process to ensure that technical information depicted on selected engineering drawings accurately reflects the actual existing physical configuration. This document defines the Field Verification Program necessary to perform the field walkdown and inspection process that identifies the physical configuration of the systems required to support the mission objectives of K Basins. This program is intended to provide an accurate accounting of the actual field configuration by documenting the as-found information on a controlled drawing

Engineering drawing field verification program. Revision 3

International Nuclear Information System (INIS)

Ulk, P.F.

1994-01-01

Safe, efficient operation of waste tank farm facilities is dependent in part upon the availability of accurate, up-to-date plant drawings. Accurate plant drawings are also required in support of facility upgrades and future engineering remediation projects. This supporting document establishes the procedure for performing a visual field verification of engineering drawings, the degree of visual observation being performed and documenting the results. A copy of the drawing attesting to the degree of visual observation will be paginated into the released Engineering Change Notice (ECN) documenting the field verification for future retrieval and reference. All waste tank farm essential and support drawings within the scope of this program will be converted from manual to computer aided drafting (CAD) drawings. A permanent reference to the field verification status will be placed along the right border of the CAD-converted drawing, referencing the revision level, at which the visual verification was performed and documented

Verification of Open Interactive Markov Chains

OpenAIRE

Brazdil, Tomas; Hermanns, Holger; Krcal, Jan; Kretinsky, Jan; Rehak, Vojtech

2012-01-01

Interactive Markov chains (IMC) are compositional behavioral models extending both labeled transition systems and continuous-time Markov chains. IMC pair modeling convenience - owed to compositionality properties - with effective verification algorithms and tools - owed to Markov properties. Thus far however, IMC verification did not consider compositionality properties, but considered closed systems. This paper discusses the evaluation of IMC in an open and thus compositional interpretation....

Autonomous Integrated Navigation for Indoor Robots Utilizing On-Line Iterated Extended Rauch-Tung-Striebel Smoothing

Directory of Open Access Journals (Sweden)

Yuan Xu

2013-11-01

Full Text Available In order to reduce the estimated errors of the inertial navigation system (INS/Wireless sensor network (WSN-integrated navigation for mobile robots indoors, this work proposes an on-line iterated extended Rauch-Tung-Striebel smoothing (IERTSS utilizing inertial measuring units (IMUs and an ultrasonic positioning system. In this mode, an iterated Extended Kalman filter (IEKF is used in forward data processing of the Extended Rauch-Tung-Striebel smoothing (ERTSS to improve the accuracy of the filtering output for the smoother. Furthermore, in order to achieve the on-line smoothing, IERTSS is embedded into the average filter. For verification, a real indoor test has been done to assess the performance of the proposed method. The results show that the proposed method is effective in reducing the errors compared with the conventional schemes.

Earth Science Enterprise Scientific Data Purchase Project: Verification and Validation

Science.gov (United States)

Jenner, Jeff; Policelli, Fritz; Fletcher, Rosea; Holecamp, Kara; Owen, Carolyn; Nicholson, Lamar; Dartez, Deanna

2000-01-01

This paper presents viewgraphs on the Earth Science Enterprise Scientific Data Purchase Project's verification,and validation process. The topics include: 1) What is Verification and Validation? 2) Why Verification and Validation? 3) Background; 4) ESE Data Purchas Validation Process; 5) Data Validation System and Ingest Queue; 6) Shipment Verification; 7) Tracking and Metrics; 8) Validation of Contract Specifications; 9) Earth Watch Data Validation; 10) Validation of Vertical Accuracy; and 11) Results of Vertical Accuracy Assessment.

Design verification for large reprocessing plants (Proposed procedures)

International Nuclear Information System (INIS)

Rolandi, G.

1988-07-01

In the 1990s, four large commercial reprocessing plants will progressively come into operation: If an effective and efficient safeguards system is to be applied to these large and complex plants, several important factors have to be considered. One of these factors, addressed in the present report, concerns plant design verification. Design verification provides an overall assurance on plant measurement data. To this end design verification, although limited to the safeguards aspects of the plant, must be a systematic activity, which starts during the design phase, continues during the construction phase and is particularly performed during the various steps of the plant's commissioning phase. The detailed procedures for design information verification on commercial reprocessing plants must be defined within the frame of the general provisions set forth in INFCIRC/153 for any type of safeguards related activities and specifically for design verification. The present report is intended as a preliminary contribution on a purely technical level, and focusses on the problems within the Agency. For the purpose of the present study the most complex case was assumed: i.e. a safeguards system based on conventional materials accountancy, accompanied both by special input and output verification and by some form of near-real-time accountancy involving in-process inventory taking, based on authenticated operator's measurement data. C/S measures are also foreseen, where necessary to supplement the accountancy data. A complete ''design verification'' strategy comprehends: informing the Agency of any changes in the plant system which are defined as ''safeguards relevant''; ''reverifying by the Agency upon receiving notice from the Operator on any changes, on ''design information''. 13 refs

Material integrity verification radar

International Nuclear Information System (INIS)

Koppenjan, S.K.

1999-01-01

The International Atomic Energy Agency (IAEA) has the need for verification of 'as-built' spent fuel-dry storage containers and other concrete structures. The IAEA has tasked the Special Technologies Laboratory (STL) to fabricate, test, and deploy a stepped-frequency Material Integrity Verification Radar (MIVR) system to nondestructively verify the internal construction of these containers. The MIVR system is based on previously deployed high-frequency, ground penetrating radar (GPR) systems that have been developed by STL for the U.S. Department of Energy (DOE). Whereas GPR technology utilizes microwave radio frequency energy to create subsurface images, MTVR is a variation for which the medium is concrete instead of soil. The purpose is to nondestructively verify the placement of concrete-reinforcing materials, pipes, inner liners, and other attributes of the internal construction. The MIVR system underwent an initial field test on CANDU reactor spent fuel storage canisters at Atomic Energy of Canada Limited (AECL), Chalk River Laboratories, Ontario, Canada, in October 1995. A second field test at the Embalse Nuclear Power Plant in Embalse, Argentina, was completed in May 1996. The DOE GPR also was demonstrated at the site. Data collection and analysis were performed for the Argentine National Board of Nuclear Regulation (ENREN). IAEA and the Brazilian-Argentine Agency for the Control and Accounting of Nuclear Material (ABACC) personnel were present as observers during the test. Reinforcing materials were evident in the color, two-dimensional images produced by the MIVR system. A continuous pattern of reinforcing bars was evident and accurate estimates on the spacing, depth, and size were made. The potential uses for safeguard applications were jointly discussed. The MIVR system, as successfully demonstrated in the two field tests, can be used as a design verification tool for IAEA safeguards. A deployment of MIVR for Design Information Questionnaire (DIQ

Specification and Automated Verification of Real-Time Behaviour

DEFF Research Database (Denmark)

Kristensen, C.H.; Andersen, J.H.; Skou, A.

1995-01-01

In this paper we sketch a method for specification and automatic verification of real-time software properties.......In this paper we sketch a method for specification and automatic verification of real-time software properties....

Specification and Automated Verification of Real-Time Behaviour

DEFF Research Database (Denmark)

Andersen, J.H.; Kristensen, C.H.; Skou, A.

1996-01-01

In this paper we sketch a method for specification and automatic verification of real-time software properties.......In this paper we sketch a method for specification and automatic verification of real-time software properties....

Formal Verification of Continuous Systems

DEFF Research Database (Denmark)

Sloth, Christoffer

2012-01-01

and the verification procedures should be algorithmically synthesizable. Autonomous control plays an important role in many safety-critical systems. This implies that a malfunction in the control system can have catastrophic consequences, e.g., in space applications where a design flaw can result in large economic...... losses. Furthermore, a malfunction in the control system of a surgical robot may cause death of patients. The previous examples involve complex systems that are required to operate according to complex specifications. The systems cannot be formally verified by modern verification techniques, due...

Biometric Technologies and Verification Systems

CERN Document Server

Vacca, John R

2007-01-01

Biometric Technologies and Verification Systems is organized into nine parts composed of 30 chapters, including an extensive glossary of biometric terms and acronyms. It discusses the current state-of-the-art in biometric verification/authentication, identification and system design principles. It also provides a step-by-step discussion of how biometrics works; how biometric data in human beings can be collected and analyzed in a number of ways; how biometrics are currently being used as a method of personal identification in which people are recognized by their own unique corporal or behavior

Runtime Verification Through Forward Chaining

Directory of Open Access Journals (Sweden)

Alan Perotti

2014-12-01

Full Text Available In this paper we present a novel rule-based approach for Runtime Verification of FLTL properties over finite but expanding traces. Our system exploits Horn clauses in implication form and relies on a forward chaining-based monitoring algorithm. This approach avoids the branching structure and exponential complexity typical of tableaux-based formulations, creating monitors with a single state and a fixed number of rules. This allows for a fast and scalable tool for Runtime Verification: we present the technical details together with a working implementation.

Current status of verification practices in clinical biochemistry in Spain.

Science.gov (United States)

Gómez-Rioja, Rubén; Alvarez, Virtudes; Ventura, Montserrat; Alsina, M Jesús; Barba, Núria; Cortés, Mariano; Llopis, María Antonia; Martínez, Cecilia; Ibarz, Mercè

2013-09-01

Verification uses logical algorithms to detect potential errors before laboratory results are released to the clinician. Even though verification is one of the main processes in all laboratories, there is a lack of standardization mainly in the algorithms used and the criteria and verification limits applied. A survey in clinical laboratories in Spain was conducted in order to assess the verification process, particularly the use of autoverification. Questionnaires were sent to the laboratories involved in the External Quality Assurance Program organized by the Spanish Society of Clinical Biochemistry and Molecular Pathology. Seven common biochemical parameters were included (glucose, cholesterol, triglycerides, creatinine, potassium, calcium, and alanine aminotransferase). Completed questionnaires were received from 85 laboratories. Nearly all the laboratories reported using the following seven verification criteria: internal quality control, instrument warnings, sample deterioration, reference limits, clinical data, concordance between parameters, and verification of results. The use of all verification criteria varied according to the type of verification (automatic, technical, or medical). Verification limits for these parameters are similar to biological reference ranges. Delta Check was used in 24% of laboratories. Most laboratories (64%) reported using autoverification systems. Autoverification use was related to laboratory size, ownership, and type of laboratory information system, but amount of use (percentage of test autoverified) was not related to laboratory size. A total of 36% of Spanish laboratories do not use autoverification, despite the general implementation of laboratory information systems, most of them, with autoverification ability. Criteria and rules for seven routine biochemical tests were obtained.

Malignant T Cells Secrete Galectins and Induce Epidermal Hyperproliferation and Disorganized Stratification in a Skin Model of Cutaneous T Cell Lymphoma

DEFF Research Database (Denmark)

Thode, Christenze; Andersen, Anders Woetmann; Wandall, Hans H

2015-01-01

Cutaneous T cell lymphomas (CTCL) are the most common primary skin lymphomas; which are characterized by an accumulation of malignant T cells in the skin. The early lesion resembles both clinically and histologically benign inflammatory disorders, which also presents with hyperproliferative epide...... in CTCL.Journal of Investigative Dermatology accepted article preview online, 09 July 2014; doi:10.1038/jid.2014.284....

Characterization of a new transmission detector for patient individualized online plan verification and its influence on 6MV X-ray beam characteristics

Energy Technology Data Exchange (ETDEWEB)

Thoelking, Johannes; Sekar, Yuvaraj; Fleckenstein, Jens; Lohr, Frank; Wenz, Frederik; Wertz, Hansjoerg [Heidelberg Univ., University Medical Center Mannheim (Germany). Dept. of Radiation Oncology

2016-11-01

Online verification and 3D dose reconstruction on daily patient anatomy have the potential to improve treatment delivery, accuracy and safety. One possible implementation is to recalculate dose based on online fluence measurements with a transmission detector (TD) attached to the linac. This study provides a detailed analysis of the influence of a new TD on treatment beam characteristics. The influence of the new TD on surface dose was evaluated by measurements with an Advanced Markus Chamber (Adv-MC) in the build-up region. Based on Monte Carlo simulations, correction factors were determined to scale down the over-response of the Adv-MC close to the surface. To analyze the effects beyond d{sub max} percentage depth dose (PDD), lateral profiles and transmission measurements were performed. All measurements were carried out for various field sizes and different SSDs. Additionally, 5 IMRT-plans (head and neck, prostate, thorax) and 2 manually created test cases (3 x 3 cm{sup 2} fields with different dose levels, sweeping gap) were measured to investigate the influence of the TD on clinical treatment plans. To investigate the performance of the TD, dose linearity as well as dose rate dependency measurements were performed. With the TD inside the beam an increase in surface dose was observed depending on SSD and field size (maximum of +11%, SSD = 80 cm, field size = 30 x 30 cm{sup 2}). Beyond d{sub max} the influence of the TD on PDDs was below 1%. The measurements showed that the transmission factor depends slightly on the field size (0.893-0.921 for 5 x 5 cm{sup 2} to 30 x 30 cm{sup 2}). However, the evaluation of clinical IMRT-plans measured with and without the TD showed good agreement after using a single transmission factor (γ{sub (2%/2mm)} > 97%, δ{sub ±3%} >95%). Furthermore, the response of TD was found to be linear and dose rate independent (maximum difference <0.5% compared to reference measurements). When placed in the path of the beam, the TD introduced

Complementary technologies for verification of excess plutonium

International Nuclear Information System (INIS)

Langner, D.G.; Nicholas, N.J.; Ensslin, N.; Fearey, B.L.; Mitchell, D.J.; Marlow, K.W.; Luke, S.J.; Gosnell, T.B.

1998-01-01

Three complementary measurement technologies have been identified as candidates for use in the verification of excess plutonium of weapons origin. These technologies: high-resolution gamma-ray spectroscopy, neutron multiplicity counting, and low-resolution gamma-ray spectroscopy, are mature, robust technologies. The high-resolution gamma-ray system, Pu-600, uses the 630--670 keV region of the emitted gamma-ray spectrum to determine the ratio of 240 Pu to 239 Pu. It is useful in verifying the presence of plutonium and the presence of weapons-grade plutonium. Neutron multiplicity counting is well suited for verifying that the plutonium is of a safeguardable quantity and is weapons-quality material, as opposed to residue or waste. In addition, multiplicity counting can independently verify the presence of plutonium by virtue of a measured neutron self-multiplication and can detect the presence of non-plutonium neutron sources. The low-resolution gamma-ray spectroscopic technique is a template method that can provide continuity of knowledge that an item that enters the a verification regime remains under the regime. In the initial verification of an item, multiple regions of the measured low-resolution spectrum form a unique, gamma-radiation-based template for the item that can be used for comparison in subsequent verifications. In this paper the authors discuss these technologies as they relate to the different attributes that could be used in a verification regime

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.

A Synthesized Framework for Formal Verification of Computing Systems

Directory of Open Access Journals (Sweden)

Nikola Bogunovic

2003-12-01

Full Text Available Design process of computing systems gradually evolved to a level that encompasses formal verification techniques. However, the integration of formal verification techniques into a methodical design procedure has many inherent miscomprehensions and problems. The paper explicates the discrepancy between the real system implementation and the abstracted model that is actually used in the formal verification procedure. Particular attention is paid to the seamless integration of all phases of the verification procedure that encompasses definition of the specification language and denotation and execution of conformance relation between the abstracted model and its intended behavior. The concealed obstacles are exposed, computationally expensive steps identified and possible improvements proposed.

Independent verification in operations at nuclear power plants

International Nuclear Information System (INIS)

Donderi, D.C.; Smiley, A.; Ostry, D.J.; Moray, N.P.

1995-09-01

A critical review of approaches to independent verification in operations used in nuclear power plant quality assurance programs in other countries, was conducted for this study. This report identifies the uses of independent verification and provides an assessment of the effectiveness of the various approaches. The findings indicate that at Canadian nuclear power plants as much, if not more, independent verification is performed than at power plants in the other countries included in the study. Additional requirements in this area are not proposed for Canadian stations. (author)

On-line analysis of ETA and organic acids in secondary systems of PWR plants

International Nuclear Information System (INIS)

Kurashina, Masahiko; Uzawa, Hideo; Utagawa, Koya; Takaku, Hiroshi

2005-01-01

To reduce the iron concentration in the secondary water of plants with pressurized water reactors (PWRs), ethanolamine (ETA) is used as an alkalizing agent in the secondary cycle. An on-line ion chromatography (IC) monitoring system for monitoring concentrations of ETA and anions of organic acids was developed, its performance was evaluated, and verification tests were conducted at an actual PWR plant. It was demonstrated that the concentration of both ETA and anions of organic acids may be successfully monitored by IC in PWR secondary cycle streams alkalized by ETA. (orig.)

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)

Daily online bony correction is required for prostate patients without fiducial markers or soft-tissue imaging.

Science.gov (United States)

Johnston, M L; Vial, P; Wiltshire, K L; Bell, L J; Blome, S; Kerestes, Z; Morgan, G W; O'Driscoll, D; Shakespeare, T P; Eade, T N

2011-09-01

To compare online position verification strategies with offline correction protocols for patients undergoing definitive prostate radiotherapy. We analysed 50 patients with implanted fiducial markers undergoing curative prostate radiation treatment, all of whom underwent daily kilovoltage imaging using an on-board imager. For each treatment, patients were set-up initially with skin tattoos and in-room lasers. Orthogonal on-board imager images were acquired and the couch shift to match both bony anatomy and the fiducial markers recorded. The set-up error using skin tattoos and offline bone correction was compared with online bone correction. The fiducial markers were used as the reference. Data from 1923 fractions were analysed. The systematic error was ≤1 mm for all protocols. The average random error was 2-3mm for online bony correction and 3-5mm for skin tattoos or offline-bone. Online-bone showed a significant improvement compared with offline-bone in the number of patients with >5mm set-up errors for >10% (P20% (Pmarkers or daily soft-tissue imaging. Copyright © 2011 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.

Nuclear Data Verification and Standardization

Energy Technology Data Exchange (ETDEWEB)

Karam, Lisa R.; Arif, Muhammad; Thompson, Alan K.

2011-10-01

The objective of this interagency program is to provide accurate neutron interaction verification and standardization data for the U.S. Department of Energy Division of Nuclear Physics programs which include astrophysics, radioactive beam studies, and heavy-ion reactions. The measurements made in this program are also useful to other programs that indirectly use the unique properties of the neutron for diagnostic and analytical purposes. These include homeland security, personnel health and safety, nuclear waste disposal, treaty verification, national defense, and nuclear based energy production. The work includes the verification of reference standard cross sections and related neutron data employing the unique facilities and capabilities at NIST and other laboratories as required; leadership and participation in international intercomparisons and collaborations; and the preservation of standard reference deposits. An essential element of the program is critical evaluation of neutron interaction data standards including international coordinations. Data testing of critical data for important applications is included. The program is jointly supported by the Department of Energy and the National Institute of Standards and Technology.

Verification and quality control of routine hematology analyzers

NARCIS (Netherlands)

Vis, J Y; Huisman, A

2016-01-01

Verification of hematology analyzers (automated blood cell counters) is mandatory before new hematology analyzers may be used in routine clinical care. The verification process consists of several items which comprise among others: precision, accuracy, comparability, carryover, background and

Solid waste operations complex engineering verification program plan

International Nuclear Information System (INIS)

Bergeson, C.L.

1994-01-01

This plan supersedes, but does not replace, the previous Waste Receiving and Processing/Solid Waste Engineering Development Program Plan. In doing this, it does not repeat the basic definitions of the various types or classes of development activities nor provide the rigorous written description of each facility and assign the equipment to development classes. The methodology described in the previous document is still valid and was used to determine the types of verification efforts required. This Engineering Verification Program Plan will be updated on a yearly basis. This EVPP provides programmatic definition of all engineering verification activities for the following SWOC projects: (1) Project W-026 - Waste Receiving and Processing Facility Module 1; (2) Project W-100 - Waste Receiving and Processing Facility Module 2A; (3) Project W-112 - Phase V Storage Facility; and (4) Project W-113 - Solid Waste Retrieval. No engineering verification activities are defined for Project W-112 as no verification work was identified. The Acceptance Test Procedures/Operational Test Procedures will be part of each project's Title III operation test efforts. The ATPs/OTPs are not covered by this EVPP

21 CFR 21.44 - Verification of identity.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Verification of identity. 21.44 Section 21.44 Food... Verification of identity. (a) An individual seeking access to records in a Privacy Act Record System may be... identity. The identification required shall be suitable considering the nature of the records sought. No...

Rapid portal imaging with a high-efficiency, large field-of-view detector.

Science.gov (United States)

Mosleh-Shirazi, M A; Evans, P M; Swindell, W; Symonds-Tayler, J R; Webb, S; Partridge, M

1998-12-01

The design, construction, and performance evaluation of an electronic portal imaging device (EPID) are described. The EPID has the same imaging geometry as the current mirror-based systems except for the x-ray detection stage, where a two-dimensional (2D) array of 1 cm thick CsI(Tl) detector elements are utilized. The approximately 18% x-ray quantum efficiency of the scintillation detector and its 30 x 40 cm2 field-of-view at the isocenter are greater than other area-imaging EPIDs. The imaging issues addressed are theoretical and measured signal-to-noise ratio, linearity of the imaging chain, influence of frame-summing on image quality and image calibration. Portal images of test objects and a humanoid phantom are used to measure the performance of the system. An image quality similar to the current devices is achieved but with a lower dose. With approximately 1 cGy dose delivered by a 6 MV beam, a 2 mm diam structure of 1.3% contrast and an 18 mm diam object of 0.125% contrast can be resolved without using image-enhancement methods. A spatial resolution of about 2 mm at the isocenter is demonstrated. The capability of the system to perform fast sequential imaging, synchronized with the radiation pulses, makes it suitable for patient motion studies and verification of intensity-modulated beams as well as its application in cone-beam megavoltage computed tomography.

A methodology for the rigorous verification of plasma simulation codes

Science.gov (United States)

Riva, Fabio

2016-10-01

The methodology used to assess the reliability of numerical simulation codes constitutes the Verification and Validation (V&V) procedure. V&V is composed by two separate tasks: the verification, which is a mathematical issue targeted to assess that the physical model is correctly solved, and the validation, which determines the consistency of the code results, and therefore of the physical model, with experimental data. In the present talk we focus our attention on the verification, which in turn is composed by the code verification, targeted to assess that a physical model is correctly implemented in a simulation code, and the solution verification, that quantifies the numerical error affecting a simulation. Bridging the gap between plasma physics and other scientific domains, we introduced for the first time in our domain a rigorous methodology for the code verification, based on the method of manufactured solutions, as well as a solution verification based on the Richardson extrapolation. This methodology was applied to GBS, a three-dimensional fluid code based on a finite difference scheme, used to investigate the plasma turbulence in basic plasma physics experiments and in the tokamak scrape-off layer. Overcoming the difficulty of dealing with a numerical method intrinsically affected by statistical noise, we have now generalized the rigorous verification methodology to simulation codes based on the particle-in-cell algorithm, which are employed to solve Vlasov equation in the investigation of a number of plasma physics phenomena.

Verification and Performance Analysis for Embedded Systems

DEFF Research Database (Denmark)

Larsen, Kim Guldstrand

2009-01-01

This talk provides a thorough tutorial of the UPPAAL tool suite for, modeling, simulation, verification, optimal scheduling, synthesis, testing and performance analysis of embedded and real-time systems.......This talk provides a thorough tutorial of the UPPAAL tool suite for, modeling, simulation, verification, optimal scheduling, synthesis, testing and performance analysis of embedded and real-time systems....

Tolerance Verification of Micro and Nano Structures on Polycarbonate Substrates

DEFF Research Database (Denmark)

Gasparin, Stefania; Tosello, Guido; Hansen, Hans Nørgaard

2010-01-01

Micro and nano structures are an increasing challenge in terms of tolerance verification and process quality control: smaller dimensions led to a smaller tolerance zone to be evaluated. This paper focuses on the verification of CD, DVD and HD-DVD nanoscale features. CD tolerance features are defi......Micro and nano structures are an increasing challenge in terms of tolerance verification and process quality control: smaller dimensions led to a smaller tolerance zone to be evaluated. This paper focuses on the verification of CD, DVD and HD-DVD nanoscale features. CD tolerance features...

Standard Verification System (SVS)

Data.gov (United States)

Social Security Administration — SVS is a mainframe program that accesses the NUMIDENT to perform SSN verifications. This program is called by SSA Internal applications to verify SSNs. There is also...

Development of an On-Line Uranium Enrichment Monitor

International Nuclear Information System (INIS)

Xuesheng, L.; Guorong, L.; Yonggang, Z.; Xueyuan, H. X.-Y.

2015-01-01

An on-line enrichment monitor was developed to measure the enrichment of UF6 flowing through the processing pipes in centrifuge uranium enrichment plant. A NaI(Tl) detector was used to measure the count rates of the 186 keV gamma ray emitted from 235U, and the total quantity of uranium was determined from thermodynamic characteristics of gaseous uranium hexafluoride. The results show that the maximum relative standard deviation is less than 1% when the measurement time is 120 s or more and the pressure is more than 2 kPa in the measurement chamber. There are two working models for the monitor. The monitor works normally in the continuous model, When the gas's pressure in the pipe fluctuates greatly, it can work in the intermittent model, and the measurement result is very well. The background of the monitor can be measured automatically periodically. It can control automatically electromagnetic valves open and close, so as to change the gas's quantity in the chamber. It is a kind of unattended and remote monitor, all of data can be transfer to central control room. It should be effective for nuclear materials accountability verifications and materials balance verification at uranium enrichment plant by using the monitor to monitor Uranium enrichment of gaseous uranium hexafluoride in the output end of cascade continuously. (author)

Packaged low-level waste verification system

International Nuclear Information System (INIS)

Tuite, K.T.; Winberg, M.; Flores, A.Y.; Killian, E.W.; McIsaac, C.V.

1996-01-01

Currently, states and low-level radioactive waste (LLW) disposal site operators have no method of independently verifying the radionuclide content of packaged LLW that arrive at disposal sites for disposal. At this time, disposal sites rely on LLW generator shipping manifests and accompanying records to insure that LLW received meets the waste acceptance criteria. An independent verification system would provide a method of checking generator LLW characterization methods and help ensure that LLW disposed of at disposal facilities meets requirements. The Mobile Low-Level Waste Verification System (MLLWVS) provides the equipment, software, and methods to enable the independent verification of LLW shipping records to insure that disposal site waste acceptance criteria are being met. The MLLWVS system was developed under a cost share subcontract between WMG, Inc., and Lockheed Martin Idaho Technologies through the Department of Energy's National Low-Level Waste Management Program at the Idaho National Engineering Laboratory (INEL)

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

.No presente estudo, nós reportamos os resultados de uma análise, baseada na sorotipagem, multilocus enzimático (MEE e ribotipagem de N. meningitidis sorogrupo C isoladas de paciente com doença meningocócica no Rio Grande do Sul (RS e Santa Catarina (SC, onde o Centro de Controle Epidemiológico do Ministério da Saúde detectou um aumento do número de casos de doença meningocócica (DM devido a este sorogrupo nos últimos 2 anos (1992-1993. Nós demonstramos que a DM devido a cepas de N. meningitidis sorogrupo C no RS e SC que ocorreram nos últimos 4 anos foi devido principalmente por um clone (ET 40, com isolados indistinguíveis por sorogrupo, sorotipo, subtipo e até por ribotipagem. Um pequeno número de casos que não foram devidos a cepas do ET 40 representaram um grupo geneticamente relacionado, que provavelmente é uma nova linhagem gerada do clone ET 40, referido como complexo ET 11 A. Nós também analisamos cepas de N. meningitidis sorogrupo C isoladas na grande São Paulo em 1976 como um grupo representativo do primeiro ano pós-epidêmico na região. A ribotipagem, bem como MEE, puderam fornecer informações sobre as características clonais das cepas isoladas no período pós-epidêmico e também no Sul do Brasil. As cepas de 1976 possuem mais similaridades com as cepas endêmicas atuais do que com as cepas epidêmicas (1992-1993 por ribotipagem, sensibilidade a sulfonamida e MEE. Em conclusão, sorotipagem com anticorpos monoclonais (C:2b:P1.3, MEE (complexo ET11 e ET11A e ribotipagem usando a enzima de restrição ClaI, foram úteis em caracterizar estas cepas epidêmicas de N. meningitidis relacionadas com o aumento da incidência da DM em diferentes estados do sul do Brasil. É muito provável que estas cepas de N. meningitidis sorogrupo C possuam pouca ou nenhuma correlação genética com as cepas epidêmicas sorogrupo C de 1971-1975. A similaridade genética dos membros do complexo ET 11 e ET 11A foram confirmadas por ribotipagem usando-se 3

A digital fluoroscopic imaging system for verification during external beam radiotherapy

International Nuclear Information System (INIS)

Takai, Michikatsu

1990-01-01

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

Hybrid Decompositional Verification for Discovering Failures in Adaptive Flight Control Systems

Science.gov (United States)

Thompson, Sarah; Davies, Misty D.; Gundy-Burlet, Karen

2010-01-01

Adaptive flight control systems hold tremendous promise for maintaining the safety of a damaged aircraft and its passengers. However, most currently proposed adaptive control methodologies rely on online learning neural networks (OLNNs), which necessarily have the property that the controller is changing during the flight. These changes tend to be highly nonlinear, and difficult or impossible to analyze using standard techniques. In this paper, we approach the problem with a variant of compositional verification. The overall system is broken into components. Undesirable behavior is fed backwards through the system. Components which can be solved using formal methods techniques explicitly for the ranges of safe and unsafe input bounds are treated as white box components. The remaining black box components are analyzed with heuristic techniques that try to predict a range of component inputs that may lead to unsafe behavior. The composition of these component inputs throughout the system leads to overall system test vectors that may elucidate the undesirable behavior

Spent Nuclear Fuel (SNF) Project Design Verification and Validation Process

International Nuclear Information System (INIS)

OLGUIN, L.J.

2000-01-01

This document provides a description of design verification and validation activities implemented by the Spent Nuclear Fuel (SNF) Project. During the execution of early design verification, a management assessment (Bergman, 1999) and external assessments on configuration management (Augustenburg, 1999) and testing (Loscoe, 2000) were conducted and identified potential uncertainties in the verification process. This led the SNF Chief Engineer to implement corrective actions to improve process and design products. This included Design Verification Reports (DVRs) for each subproject, validation assessments for testing, and verification of the safety function of systems and components identified in the Safety Equipment List to ensure that the design outputs were compliant with the SNF Technical Requirements. Although some activities are still in progress, the results of the DVR and associated validation assessments indicate that Project requirements for design verification are being effectively implemented. These results have been documented in subproject-specific technical documents (Table 2). Identified punch-list items are being dispositioned by the Project. As these remaining items are closed, the technical reports (Table 2) will be revised and reissued to document the results of this work

As-Built Verification Plan Spent Nuclear Fuel Canister Storage Building MCO Handling Machine

International Nuclear Information System (INIS)

SWENSON, C.E.

2000-01-01

This as-built verification plan outlines the methodology and responsibilities that will be implemented during the as-built field verification activity for the Canister Storage Building (CSB) MCO HANDLING MACHINE (MHM). This as-built verification plan covers THE ELECTRICAL PORTION of the CONSTRUCTION PERFORMED BY POWER CITY UNDER CONTRACT TO MOWAT. The as-built verifications will be performed in accordance Administrative Procedure AP 6-012-00, Spent Nuclear Fuel Project As-Built Verification Plan Development Process, revision I. The results of the verification walkdown will be documented in a verification walkdown completion package, approved by the Design Authority (DA), and maintained in the CSB project files

37 CFR 262.7 - Verification of royalty payments.

Science.gov (United States)

2010-07-01

... Designated Agent have agreed as to proper verification methods. (b) Frequency of verification. A Copyright Owner or a Performer may conduct a single audit of the Designated Agent upon reasonable notice and... COPYRIGHT ARBITRATION ROYALTY PANEL RULES AND PROCEDURES RATES AND TERMS FOR CERTAIN ELIGIBLE...

40 CFR 1065.675 - CLD quench verification calculations.

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 32 2010-07-01 2010-07-01 false CLD quench verification calculations... POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Calculations and Data Requirements § 1065.675 CLD quench verification calculations. Perform CLD quench-check calculations as follows: (a) Perform a CLD analyzer quench...

Analysis and Transformation Tools for Constrained Horn Clause Verification

DEFF Research Database (Denmark)

Kafle, Bishoksan; Gallagher, John Patrick

2014-01-01

Several techniques and tools have been developed for verification of properties expressed as Horn clauses with constraints over a background theory (CHC). Current CHC verification tools implement intricate algorithms and are often limited to certain subclasses of CHC problems. Our aim in this work...... is to investigate the use of a combination of off-the-shelf techniques from the literature in analysis and transformation of Constraint Logic Programs (CLPs) to solve challenging CHC verification problems. We find that many problems can be solved using a combination of tools based on well-known techniques from...... abstract interpretation, semantics-preserving transformations, program specialisation and query-answer transformations. This gives insights into the design of automatic, more general CHC verification tools based on a library of components....

Verification of the thermal design of electronic equipment

Energy Technology Data Exchange (ETDEWEB)

Hienonen, R.; Karjalainen, M.; Lankinen, R. [VTT Automation, Espoo (Finland). ProTechno

1997-12-31

The project `Verification of the thermal design of electronic equipment` studied the methodology to be followed in the verification of thermal design of electronic equipment. This project forms part of the `Cool Electronics` research programme funded by TEKES, the Finnish Technology Development Centre. This project was carried out jointly by VTT Automation, Lappeenranta University of Technology, Nokia Research Center and ABB Industry Oy VSD-Technology. The thermal design of electronic equipment has a significant impact on the cost, reliability, tolerance to different environments, selection of components and materials, and ergonomics of the product. This report describes the method for verification of thermal design. It assesses the goals set for thermal design, environmental requirements, technical implementation of the design, thermal simulation and modelling, and design qualification testing and the measurements needed. The verification method covers all packaging levels of electronic equipment from the system level to the electronic component level. The method described in this report can be used as part of the quality system of a corporation. The report includes information about the measurement and test methods needed in the verification process. Some measurement methods for the temperature, flow and pressure of air are described. (orig.) Published in Finnish VTT Julkaisuja 824. 22 refs.

Development of Advanced Verification and Validation Procedures and Tools for the Certification of Learning Systems in Aerospace Applications

Science.gov (United States)

Jacklin, Stephen; Schumann, Johann; Gupta, Pramod; Richard, Michael; Guenther, Kurt; Soares, Fola

2005-01-01

Adaptive control technologies that incorporate learning algorithms have been proposed to enable automatic flight control and vehicle recovery, autonomous flight, and to maintain vehicle performance in the face of unknown, changing, or poorly defined operating environments. In order for adaptive control systems to be used in safety-critical aerospace applications, they must be proven to be highly safe and reliable. Rigorous methods for adaptive software verification and validation must be developed to ensure that control system software failures will not occur. Of central importance in this regard is the need to establish reliable methods that guarantee convergent learning, rapid convergence (learning) rate, and algorithm stability. This paper presents the major problems of adaptive control systems that use learning to improve performance. The paper then presents the major procedures and tools presently developed or currently being developed to enable the verification, validation, and ultimate certification of these adaptive control systems. These technologies include the application of automated program analysis methods, techniques to improve the learning process, analytical methods to verify stability, methods to automatically synthesize code, simulation and test methods, and tools to provide on-line software assurance.

Methods of Software Verification

Directory of Open Access Journals (Sweden)

R. E. Gurin

2015-01-01

Full Text Available This article is devoted to the problem of software verification (SW. Methods of software verification designed to check the software for compliance with the stated requirements such as correctness, system security and system adaptability to small changes in the environment, portability and compatibility, etc. These are various methods both by the operation process and by the way of achieving result. The article describes the static and dynamic methods of software verification and paid attention to the method of symbolic execution. In its review of static analysis are discussed and described the deductive method, and methods for testing the model. A relevant issue of the pros and cons of a particular method is emphasized. The article considers classification of test techniques for each method. In this paper we present and analyze the characteristics and mechanisms of the static analysis of dependencies, as well as their views, which can reduce the number of false positives in situations where the current state of the program combines two or more states obtained both in different paths of execution and in working with multiple object values. Dependences connect various types of software objects: single variables, the elements of composite variables (structure fields, array elements, the size of the heap areas, the length of lines, the number of initialized array elements in the verification code using static methods. The article pays attention to the identification of dependencies within the framework of the abstract interpretation, as well as gives an overview and analysis of the inference tools.Methods of dynamic analysis such as testing, monitoring and profiling are presented and analyzed. Also some kinds of tools are considered which can be applied to the software when using the methods of dynamic analysis. Based on the work a conclusion is drawn, which describes the most relevant problems of analysis techniques, methods of their solutions and

Verification and Validation in Systems Engineering

CERN Document Server

Debbabi, Mourad; Jarraya, Yosr; Soeanu, Andrei; Alawneh, Luay

2010-01-01

"Verification and validation" represents an important process used for the quality assessment of engineered systems and their compliance with the requirements established at the beginning of or during the development cycle. Debbabi and his coauthors investigate methodologies and techniques that can be employed for the automatic verification and validation of systems engineering design models expressed in standardized modeling languages. Their presentation includes a bird's eye view of the most prominent modeling languages for software and systems engineering, namely the Unified Model

37 CFR 260.6 - Verification of royalty payments.

Science.gov (United States)

2010-07-01

... verification of the payment of royalty fees to those parties entitled to receive such fees, according to terms... 37 Patents, Trademarks, and Copyrights 1 2010-07-01 2010-07-01 false Verification of royalty... COPYRIGHT ARBITRATION ROYALTY PANEL RULES AND PROCEDURES RATES AND TERMS FOR PREEXISTING SUBSCRIPTION...

A Roadmap for the Implementation of Continued Process Verification.

Science.gov (United States)

Boyer, Marcus; Gampfer, Joerg; Zamamiri, Abdel; Payne, Robin

2016-01-01

In 2014, the members of the BioPhorum Operations Group (BPOG) produced a 100-page continued process verification case study, entitled "Continued Process Verification: An Industry Position Paper with Example Protocol". This case study captures the thought processes involved in creating a continued process verification plan for a new product in response to the U.S. Food and Drug Administration's guidance on the subject introduced in 2011. In so doing, it provided the specific example of a plan developed for a new molecular antibody product based on the "A MAb Case Study" that preceded it in 2009.This document provides a roadmap that draws on the content of the continued process verification case study to provide a step-by-step guide in a more accessible form, with reference to a process map of the product life cycle. It could be used as a basis for continued process verification implementation in a number of different scenarios: For a single product and process;For a single site;To assist in the sharing of data monitoring responsibilities among sites;To assist in establishing data monitoring agreements between a customer company and a contract manufacturing organization. The U.S. Food and Drug Administration issued guidance on the management of manufacturing processes designed to improve quality and control of drug products. This involved increased focus on regular monitoring of manufacturing processes, reporting of the results, and the taking of opportunities to improve. The guidance and practice associated with it is known as continued process verification This paper summarizes good practice in responding to continued process verification guidance, gathered from subject matter experts in the biopharmaceutical industry. © PDA, Inc. 2016.

Land surface Verification Toolkit (LVT)

Science.gov (United States)

Kumar, Sujay V.

2017-01-01

LVT is a framework developed to provide an automated, consolidated environment for systematic land surface model evaluation Includes support for a range of in-situ, remote-sensing and other model and reanalysis products. Supports the analysis of outputs from various LIS subsystems, including LIS-DA, LIS-OPT, LIS-UE. Note: The Land Information System Verification Toolkit (LVT) is a NASA software tool designed to enable the evaluation, analysis and comparison of outputs generated by the Land Information System (LIS). The LVT software is released under the terms and conditions of the NASA Open Source Agreement (NOSA) Version 1.1 or later. Land Information System Verification Toolkit (LVT) NOSA.

On Backward-Style Anonymity Verification

Science.gov (United States)

Kawabe, Yoshinobu; Mano, Ken; Sakurada, Hideki; Tsukada, Yasuyuki

Many Internet services and protocols should guarantee anonymity; for example, an electronic voting system should guarantee to prevent the disclosure of who voted for which candidate. To prove trace anonymity, which is an extension of the formulation of anonymity by Schneider and Sidiropoulos, this paper presents an inductive method based on backward anonymous simulations. We show that the existence of an image-finite backward anonymous simulation implies trace anonymity. We also demonstrate the anonymity verification of an e-voting protocol (the FOO protocol) with our backward anonymous simulation technique. When proving the trace anonymity, this paper employs a computer-assisted verification tool based on a theorem prover.

Megavoltage cone beam computed tomography: commissioning and evaluation of patient dose

International Nuclear Information System (INIS)

Abou-elenein, Hassan S.; Attalla, Ehab M.; Ammar, H.; Eldesoky, Ismail; Farouk, Mohamed; Zaghloul, Mohamed S.

2011-01-01

The improvement in conformal radiotherapy techniques enables us to achieve steep dose gradients around the target which allows the delivery of higher doses to a tumor volume while maintaining the sparing of surrounding normal tissue. One of the reasons for this improvement was the implementation of intensity-modulated radio therapy (IMRT) by using linear accelerators fitted with multi-leaf collimator (MLC), Tomo therapy and Rapid arc. In this situation, verification of patient set-up and evaluation of internal organ motion just prior to radiation delivery become important. To this end, several volumetric image-guided techniques have been developed for patient localization, such as Siemens OPTIVUE/MVCB and MVision megavoltage cone beam CT (MV-CBCT) system. Quality assurance for MV-CBCT is important to insure that the performance of the Electronic portal image device (EPID) and MV-CBCT is suitable for the required treatment accuracy. In this work, the commissioning and clinical implementation of the OPTIVUE/MVCB system was presented. The geometry and gain calibration procedures for the system were described. The image quality characteristics of the OPTIVUE/MVCB system were measured and assessed qualitatively and quantitatively, including the image noise and uniformity, low-contrast resolution, and spatial resolution. The image reconstruction and registration software were evaluated. Dose at isocenter from CBCT and the EPID were evaluated using ionization chamber and thermo-luminescent dosimeters; then compared with that calculated by the treatment planning system (TPS- XiO 4.4). The results showed that there are no offsets greater than 1 mm in the flat panel alignment in the lateral and longitudinal direction over 18 months of the study. The image quality tests showed that the image noise and uniformity were within the acceptable range, and that a 2 cm large object with 1% electron density contrast can be detected with the OPTIVUE/MVCB system with 5 monitor units (MU

78 FR 27882 - VA Veteran-Owned Small Business (VOSB) Verification Guidelines

Science.gov (United States)

2013-05-13

... Verification Self-Assessment Tool that walks the veteran through the regulation and how it applies to the...) Verification Guidelines AGENCY: Department of Veterans Affairs. ACTION: Advanced notice of proposed rulemaking... regulations governing the Department of Veterans Affairs (VA) Veteran-Owned Small Business (VOSB) Verification...

Verification and validation for waste disposal models

International Nuclear Information System (INIS)

1987-07-01

A set of evaluation criteria has been developed to assess the suitability of current verification and validation techniques for waste disposal methods. A survey of current practices and techniques was undertaken and evaluated using these criteria with the items most relevant to waste disposal models being identified. Recommendations regarding the most suitable verification and validation practices for nuclear waste disposal modelling software have been made

On-line reconstruction of in-core power distribution by harmonics expansion method

International Nuclear Information System (INIS)

Wang Changhui; Wu Hongchun; Cao Liangzhi; Yang Ping

2011-01-01

Highlights: → A harmonics expansion method for the on-line in-core power reconstruction is proposed. → A harmonics data library is pre-generated off-line and a code named COMS is developed. → Numerical results show that the maximum relative error of the reconstruction is less than 5.5%. → This method has a high computational speed compared to traditional methods. - Abstract: Fixed in-core detectors are most suitable in real-time response to in-core power distributions in pressurized water reactors (PWRs). In this paper, a harmonics expansion method is used to reconstruct the in-core power distribution of a PWR on-line. In this method, the in-core power distribution is expanded by the harmonics of one reference case. The expansion coefficients are calculated using signals provided by fixed in-core detectors. To conserve computing time and improve reconstruction precision, a harmonics data library containing the harmonics of different reference cases is constructed. Upon reconstruction of the in-core power distribution on-line, the two closest reference cases are searched from the harmonics data library to produce expanded harmonics by interpolation. The Unit 1 reactor of DayaBay Nuclear Power Plant (DayaBay NPP) in China is considered for verification. The maximum relative error between the measurement and reconstruction results is less than 5.5%, and the computing time is about 0.53 s for a single reconstruction, indicating that this method is suitable for the on-line monitoring of PWRs.

A phantom study of dose compensation behind hip prosthesis using portal dosimetry and dynamic MLC

International Nuclear Information System (INIS)

Nielsen, Martin Skovmos; Carl, Jesper; Nielsen, Jane

2008-01-01

Background and purpose: A dose compensation method is presented for patients with hip prosthesis based on Dynamic Multi Leaves Collimator (DMLC) planning. Calculations are done from an exit Portal Dose Image (PDI) from 6 MV Photon beam using an Electronic Portal Imaging Device (EPID) from Varian. Four different hip prostheses are used for this work. Methods: From an exit PDI the fluence needed to yield a uniform dose distribution behind the prosthesis is calculated. To back-project the dose distribution through the phantom, the lateral scatter is removed by deconvolution with a point spread function (PSF) determined for depths from 10 to 40 cm. The dose maximum, D max , is determined from the primary plan which delivers the PDI. A further deconvolution to remove the dose glare effect in the EPID is performed as well. Additionally, this calculated fluence distribution is imported into the Treatment Planning System (TPS) for the final calculation of a DMLC plan. The fluence file contains information such as the relative central axis (CAX) position, grid size and fluence size needed for correct delivery of the DMLC plan. GafChromic EBT films positioned at 10 cm depth are used as verification of uniform dose distributions behind the prostheses. As the prosthesis is positioned at the phantom surface the dose verifications are done 10 cm from the prosthesis. Conclusion: The film measurement with 6 MV photon beam shows uniform doses within 5% for most points, but with hot/cold spots of 10% near the femoral head prostheses

Property-driven functional verification technique for high-speed vision system-on-chip processor

Science.gov (United States)

Nshunguyimfura, Victor; Yang, Jie; Liu, Liyuan; Wu, Nanjian

2017-04-01

The implementation of functional verification in a fast, reliable, and effective manner is a challenging task in a vision chip verification process. The main reason for this challenge is the stepwise nature of existing functional verification techniques. This vision chip verification complexity is also related to the fact that in most vision chip design cycles, extensive efforts are focused on how to optimize chip metrics such as performance, power, and area. Design functional verification is not explicitly considered at an earlier stage at which the most sound decisions are made. In this paper, we propose a semi-automatic property-driven verification technique. The implementation of all verification components is based on design properties. We introduce a low-dimension property space between the specification space and the implementation space. The aim of this technique is to speed up the verification process for high-performance parallel processing vision chips. Our experimentation results show that the proposed technique can effectively improve the verification effort up to 20% for the complex vision chip design while reducing the simulation and debugging overheads.

Design verification methodology for a solenoid valve for industrial applications

International Nuclear Information System (INIS)

Park, Chang Dae; Lim, Byung Ju; Chun, Kyung Yul

2015-01-01

Solenoid operated valves (SOV) are widely used in many applications due to their fast dynamic responses, cost effectiveness, and less contamination sensitive characteristics. In this paper, we tried to provide a convenient method of design verification of SOV to design engineers who depend on their experiences and experiment during design and development process of SOV. First, we summarize a detailed procedure for designing SOVs for industrial applications. All of the design constraints are defined in the first step of the design, and then the detail design procedure is presented based on design experiences as well as various physical and electromagnetic relationships. Secondly, we have suggested a verification method of this design using theoretical relationships, which enables optimal design of SOV from a point of view of safety factor of design attraction force. Lastly, experimental performance tests using several prototypes manufactured based on this design method show that the suggested design verification methodology is appropriate for designing new models of solenoids. We believe that this verification process is novel logic and useful to save time and expenses during development of SOV because verification tests with manufactured specimen may be substituted partly by this verification methodology.

Verification test report on a solar heating and hot water system

Science.gov (United States)

1978-01-01

Information is provided on the development, qualification and acceptance verification of commercial solar heating and hot water systems and components. The verification includes the performances, the efficiences and the various methods used, such as similarity, analysis, inspection, test, etc., that are applicable to satisfying the verification requirements.

Temporal Specification and Verification of Real-Time Systems.

Science.gov (United States)

1991-08-30

of concrete real - time systems can be modeled adequately. Specification: We present two conservative extensions of temporal logic that allow for the...logic. We present both model-checking algorithms for the automatic verification of finite-state real - time systems and proof methods for the deductive verification of real - time systems .

A verification regime for the spatial discretization of the SN transport equations

Energy Technology Data Exchange (ETDEWEB)

Schunert, S.; Azmy, Y. [North Carolina State Univ., Dept. of Nuclear Engineering, 2500 Stinson Drive, Raleigh, NC 27695 (United States)

2012-07-01

The order-of-accuracy test in conjunction with the method of manufactured solutions is the current state of the art in computer code verification. In this work we investigate the application of a verification procedure including the order-of-accuracy test on a generic SN transport solver that implements the AHOTN spatial discretization. Different types of semantic errors, e.g. removal of a line of code or changing a single character, are introduced randomly into the previously verified S{sub N} code and the proposed verification procedure is used to identify the coding mistakes (if possible) and classify them. Itemized by error type we record the stage of the verification procedure where the error is detected and report the frequency with which the errors are correctly identified at various stages of the verification. Errors that remain undetected by the verification procedure are further scrutinized to determine the reason why the introduced coding mistake eluded the verification procedure. The result of this work is that the verification procedure based on an order-of-accuracy test finds almost all detectable coding mistakes but rarely, 1.44% of the time, and under certain circumstances can fail. (authors)

Environmental technology verification methods

CSIR Research Space (South Africa)

Szewczuk, S

2016-03-01

Full Text Available Environmental Technology Verification (ETV) is a tool that has been developed in the United States of America, Europe and many other countries around the world to help innovative environmental technologies reach the market. Claims about...

Verification and Optimization of a PLC Control Schedule

NARCIS (Netherlands)

Brinksma, Hendrik; Mader, Angelika H.; Havelund, K.; Penix, J.; Visser, W.

We report on the use of the SPIN model checker for both the verification of a process control program and the derivation of optimal control schedules. This work was carried out as part of a case study for the EC VHS project (Verification of Hybrid Systems), in which the program for a Programmable

Compressive sensing using optimized sensing matrix for face verification

Science.gov (United States)

Oey, Endra; Jeffry; Wongso, Kelvin; Tommy

2017-12-01

Biometric appears as one of the solutions which is capable in solving problems that occurred in the usage of password in terms of data access, for example there is possibility in forgetting password and hard to recall various different passwords. With biometrics, physical characteristics of a person can be captured and used in the identification process. In this research, facial biometric is used in the verification process to determine whether the user has the authority to access the data or not. Facial biometric is chosen as its low cost implementation and generate quite accurate result for user identification. Face verification system which is adopted in this research is Compressive Sensing (CS) technique, in which aims to reduce dimension size as well as encrypt data in form of facial test image where the image is represented in sparse signals. Encrypted data can be reconstructed using Sparse Coding algorithm. Two types of Sparse Coding namely Orthogonal Matching Pursuit (OMP) and Iteratively Reweighted Least Squares -ℓp (IRLS-ℓp) will be used for comparison face verification system research. Reconstruction results of sparse signals are then used to find Euclidean norm with the sparse signal of user that has been previously saved in system to determine the validity of the facial test image. Results of system accuracy obtained in this research are 99% in IRLS with time response of face verification for 4.917 seconds and 96.33% in OMP with time response of face verification for 0.4046 seconds with non-optimized sensing matrix, while 99% in IRLS with time response of face verification for 13.4791 seconds and 98.33% for OMP with time response of face verification for 3.1571 seconds with optimized sensing matrix.

340 and 310 drawing field verification

International Nuclear Information System (INIS)

Langdon, J.

1996-01-01

The purpose of the drawing field verification work plan is to provide reliable drawings for the 310 Treated Effluent Disposal Facility (TEDF) and 340 Waste Handling Facility (340 Facility). The initial scope of this work plan is to provide field verified and updated versions of all the 340 Facility essential drawings. This plan can also be used for field verification of any other drawings that the facility management directs to be so updated. Any drawings revised by this work plan will be issued in an AutoCAD format

Verification of Scientific Simulations via Hypothesis-Driven Comparative and Quantitative Visualization

Energy Technology Data Exchange (ETDEWEB)

Ahrens, James P [ORNL; Heitmann, Katrin [ORNL; Petersen, Mark R [ORNL; Woodring, Jonathan [Los Alamos National Laboratory (LANL); Williams, Sean [Los Alamos National Laboratory (LANL); Fasel, Patricia [Los Alamos National Laboratory (LANL); Ahrens, Christine [Los Alamos National Laboratory (LANL); Hsu, Chung-Hsing [ORNL; Geveci, Berk [ORNL

2010-11-01

This article presents a visualization-assisted process that verifies scientific-simulation codes. Code verification is necessary because scientists require accurate predictions to interpret data confidently. This verification process integrates iterative hypothesis verification with comparative, feature, and quantitative visualization. Following this process can help identify differences in cosmological and oceanographic simulations.

Formal verification of Simulink/Stateflow diagrams a deductive approach

CERN Document Server

Zhan, Naijun; Zhao, Hengjun

2017-01-01

This book presents a state-of-the-art technique for formal verification of continuous-time Simulink/Stateflow diagrams, featuring an expressive hybrid system modelling language, a powerful specification logic and deduction-based verification approach, and some impressive, realistic case studies. Readers will learn the HCSP/HHL-based deductive method and the use of corresponding tools for formal verification of Simulink/Stateflow diagrams. They will also gain some basic ideas about fundamental elements of formal methods such as formal syntax and semantics, and especially the common techniques applied in formal modelling and verification of hybrid systems. By investigating the successful case studies, readers will realize how to apply the pure theory and techniques to real applications, and hopefully will be inspired to start to use the proposed approach, or even develop their own formal methods in their future work.

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.

Ontology Matching with Semantic Verification.

Science.gov (United States)

Jean-Mary, Yves R; Shironoshita, E Patrick; Kabuka, Mansur R

2009-09-01

ASMOV (Automated Semantic Matching of Ontologies with Verification) is a novel algorithm that uses lexical and structural characteristics of two ontologies to iteratively calculate a similarity measure between them, derives an alignment, and then verifies it to ensure that it does not contain semantic inconsistencies. In this paper, we describe the ASMOV algorithm, and then present experimental results that measure its accuracy using the OAEI 2008 tests, and that evaluate its use with two different thesauri: WordNet, and the Unified Medical Language System (UMLS). These results show the increased accuracy obtained by combining lexical, structural and extensional matchers with semantic verification, and demonstrate the advantage of using a domain-specific thesaurus for the alignment of specialized ontologies.

Interpolant tree automata and their application in Horn clause verification

DEFF Research Database (Denmark)

Kafle, Bishoksan; Gallagher, John Patrick

2016-01-01

This paper investigates the combination of abstract interpretation over the domain of convex polyhedra with interpolant tree automata, in an abstraction-refinement scheme for Horn clause verification. These techniques have been previously applied separately, but are combined in a new way in this ......This paper investigates the combination of abstract interpretation over the domain of convex polyhedra with interpolant tree automata, in an abstraction-refinement scheme for Horn clause verification. These techniques have been previously applied separately, but are combined in a new way...... clause verification problems indicates that the combination of interpolant tree automaton with abstract interpretation gives some increase in the power of the verification tool, while sometimes incurring a performance overhead....

Synergies across verification regimes: Nuclear safeguards and chemical weapons convention compliance

International Nuclear Information System (INIS)

Kadner, Steven P.; Turpen, Elizabeth

2001-01-01

In the implementation of all arms control agreements, accurate verification is essential. In setting a course for verifying compliance with a given treaty - whether the NPT or the CWC, one must make a technical comparison of existing information-gathering capabilities against the constraints in an agreement. Then it must be decided whether this level of verifiability is good enough. Generally, the policy standard of 'effective verification' includes the ability to detect significant violations, with high confidence, in sufficient time to respond effectively with policy adjustments or other responses, as needed. It is at this juncture where verification approaches have traditionally diverged. Nuclear safeguards requirements have taken one path while chemical verification methods have pursued another. However, recent technological advances have brought a number of changes affecting verification, and lately their pace has been accelerating. First, all verification regimes have more and better information as a result of new kinds of sensors, imagery, and other technologies. Second, the verification provisions in agreements have also advanced, to include on-site inspections, portal monitoring, data exchanges, and a variety of transparency, confidence-building, and other cooperative measures, Together these developments translate into a technological overlap of certain institutional verification measures such as the NPT's safeguards requirements and the IAEA and the CWC's verification visions and the OPCW. Hence, a priority of international treaty-implementing organizations is exploring the development of a synergistic and coordinated approach to WMD policy making that takes into account existing inter-linkages between nuclear, chemical, and biological weapons issues. Specific areas of coordination include harmonizing information systems and information exchanges and the shared application of scientific mechanisms, as well as collaboration on technological developments

Heavy water physical verification in power plants

International Nuclear Information System (INIS)

Morsy, S.; Schuricht, V.; Beetle, T.; Szabo, E.

1986-01-01

This paper is a report on the Agency experience in verifying heavy water inventories in power plants. The safeguards objectives and goals for such activities are defined in the paper. The heavy water is stratified according to the flow within the power plant, including upgraders. A safeguards scheme based on a combination of records auditing, comparing records and reports, and physical verification has been developed. This scheme has elevated the status of heavy water safeguards to a level comparable to nuclear material safeguards in bulk facilities. It leads to attribute and variable verification of the heavy water inventory in the different system components and in the store. The verification methods include volume and weight determination, sampling and analysis, non-destructive assay (NDA), and criticality check. The analysis of the different measurement methods and their limits of accuracy are discussed in the paper

A Correctness Verification Technique for Commercial FPGA Synthesis Tools

International Nuclear Information System (INIS)

Kim, Eui Sub; Yoo, Jun Beom; Choi, Jong Gyun; Kim, Jang Yeol; Lee, Jang Soo

2014-01-01

Once the FPGA (Filed-Programmable Gate Array) designers designs Verilog programs, the commercial synthesis tools automatically translate the Verilog programs into EDIF programs so that the designers can have largely focused on HDL designs for correctness of functionality. Nuclear regulation authorities, however, require more considerate demonstration of the correctness and safety of mechanical synthesis processes of FPGA synthesis tools, even if the FPGA industry have acknowledged them empirically as correct and safe processes and tools. In order to assure of the safety, the industry standards for the safety of electronic/electrical devices, such as IEC 61508 and IEC 60880, recommend using the formal verification technique. There are several formal verification tools (i.e., 'FormalPro' 'Conformal' 'Formality' and so on) to verify the correctness of translation from Verilog into EDIF programs, but it is too expensive to use and hard to apply them to the works of 3rd-party developers. This paper proposes a formal verification technique which can contribute to the correctness demonstration in part. It formally checks the behavioral equivalence between Verilog and subsequently synthesized Net list with the VIS verification system. A Net list is an intermediate output of FPGA synthesis process, and EDIF is used as a standard format of Net lists. If the formal verification succeeds, then we can assure that the synthesis process from Verilog into Net list worked correctly at least for the Verilog used. In order to support the formal verification, we developed the mechanical translator 'EDIFtoBLIFMV,' which translates EDIF into BLIF-MV as an input front-end of VIS system, while preserving their behavior equivalence.. We performed the case study with an example of a preliminary version of RPS in a Korean nuclear power plant in order to provide the efficiency of the proposed formal verification technique and implemented translator. It

A Correctness Verification Technique for Commercial FPGA Synthesis Tools

Energy Technology Data Exchange (ETDEWEB)

Kim, Eui Sub; Yoo, Jun Beom [Konkuk University, Seoul (Korea, Republic of); Choi, Jong Gyun; Kim, Jang Yeol; Lee, Jang Soo [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2014-10-15

Once the FPGA (Filed-Programmable Gate Array) designers designs Verilog programs, the commercial synthesis tools automatically translate the Verilog programs into EDIF programs so that the designers can have largely focused on HDL designs for correctness of functionality. Nuclear regulation authorities, however, require more considerate demonstration of the correctness and safety of mechanical synthesis processes of FPGA synthesis tools, even if the FPGA industry have acknowledged them empirically as correct and safe processes and tools. In order to assure of the safety, the industry standards for the safety of electronic/electrical devices, such as IEC 61508 and IEC 60880, recommend using the formal verification technique. There are several formal verification tools (i.e., 'FormalPro' 'Conformal' 'Formality' and so on) to verify the correctness of translation from Verilog into EDIF programs, but it is too expensive to use and hard to apply them to the works of 3rd-party developers. This paper proposes a formal verification technique which can contribute to the correctness demonstration in part. It formally checks the behavioral equivalence between Verilog and subsequently synthesized Net list with the VIS verification system. A Net list is an intermediate output of FPGA synthesis process, and EDIF is used as a standard format of Net lists. If the formal verification succeeds, then we can assure that the synthesis process from Verilog into Net list worked correctly at least for the Verilog used. In order to support the formal verification, we developed the mechanical translator 'EDIFtoBLIFMV,' which translates EDIF into BLIF-MV as an input front-end of VIS system, while preserving their behavior equivalence.. We performed the case study with an example of a preliminary version of RPS in a Korean nuclear power plant in order to provide the efficiency of the proposed formal verification technique and implemented translator. It