WorldWideScience

Sample records for volumetric dose output

  1. Dose verification for respiratory-gated volumetric modulated arc therapy

    Energy Technology Data Exchange (ETDEWEB)

    Qian Jianguo; Xing Lei; Liu Wu; Luxton, Gary, E-mail: gluxton@stanford.edu [Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA 94305 (United States)

    2011-08-07

    A novel commercial medical linac system (TrueBeam(TM), Varian Medical Systems, Palo Alto, CA) allows respiratory-gated volumetric modulated arc therapy (VMAT), a new modality for treating moving tumors with high precision and improved accuracy by allowing for regular motion associated with a patient's breathing during VMAT delivery. The purpose of this work is to adapt a previously-developed dose reconstruction technique to evaluate the fidelity of VMAT treatment during gated delivery under clinic-relevant periodic motion related to patient breathing. A Varian TrueBeam system was used in this study. VMAT plans were created for three patients with lung or pancreas tumors. Conventional 6 and 15 MV beams with flattening filter and high-dose-rate 10 MV beams with no flattening filter were used in these plans. Each patient plan was delivered to a phantom first without gating and then with gating for three simulated respiratory periods (3, 4.5 and 6 s). Using the adapted log-file-based dose reconstruction procedure supplemented with ion chamber array (Seven29(TM), PTW, Freiburg, Germany) measurements, the delivered dose was used to evaluate the fidelity of gated VMAT delivery. Comparison of Seven29 measurements with and without gating showed good agreement with gamma-index passing rates above 99% for 1%/1 mm dose accuracy/distance-to-agreement criteria. With original plans as reference, gamma-index passing rates were 100% for the reconstituted plans (1%/1 mm criteria) and 93.5-100% for gated Seven29 measurements (3%/3 mm criteria). In the presence of leaf error deliberately introduced into the gated delivery of a pancreas patient plan, both dose reconstruction and Seven29 measurement consistently indicated substantial dosimetric differences from the original plan. In summary, a dose reconstruction procedure was demonstrated for evaluating the accuracy of respiratory-gated VMAT delivery. This technique showed that under clinical operation, the TrueBeam system

  2. Dose-volumetric parameters for predicting hypothyroidism after radiotherapy for head and neck cancer

    International Nuclear Information System (INIS)

    Kim, Mi Young; Yu, Tosol; Wu, Hong-Gyun

    2014-01-01

    To investigate predictors affecting the development of hypothyroidism after radiotherapy for head and neck cancer, focusing on radiation dose-volumetric parameters, and to determine the appropriate radiation dose-volumetric threshold of radiation-induced hypothyroidism. A total of 114 patients with head and neck cancer whose radiotherapy fields included the thyroid gland were analysed. The purpose of the radiotherapy was either definitive (n=81) or post-operative (n=33). Thyroid function was monitored before starting radiotherapy and after completion of radiotherapy at 1 month, 6 months, 1 year and 2 years. A diagnosis of hypothyroidism was based on a thyroid stimulating hormone value greater than the maximum value of laboratory range, regardless of symptoms. In all patients, dose volumetric parameters were analysed. Median follow-up duration was 25 months (range; 6-38). Forty-six percent of the patients were diagnosed as hypothyroidism after a median time of 8 months (range; 1-24). There were no significant differences in the distribution of age, gender, surgery, radiotherapy technique and chemotherapy between the euthyroid group and the hypothyroid group. In univariate analysis, the mean dose and V35-V50 results were significantly associated with hypothyroidism. The V45 is the only variable that independently contributes to the prediction of hypothyroidism in multivariate analysis and V45 of 50% was a threshold value. If V45 was <50%, the cumulative incidence of hypothyroidism at 1 year was 22.8%, whereas the incidence was 56.1% if V45 was ≥50%. (P=0.034). The V45 may predict risk of developing hypothyroidism after radiotherapy for head and neck cancer, and a V45 of 50% can be a useful dose-volumetric threshold of radiation-induced hypothyroidism. (author)

  3. Patient-Specific Quality Assurance Using Monte Carlo Dose Calculation and Elekta Log Files for Prostate Volumetric-Modulated Arc Therapy.

    Science.gov (United States)

    Katsuta, Yoshiyuki; Kadoya, Noriyuki; Fujita, Yukio; Shimizu, Eiji; Matsunaga, Kenichi; Sawada, Kinya; Matsushita, Haruo; Majima, Kazuhiro; Jingu, Keiichi

    2017-12-01

    Log file-based methods are attracting increasing interest owing to their ability to validate volumetric-modulated arc therapy outputs with high resolution in the leaf and gantry positions and in delivered dose. Cross-validation of these methods for comparison with measurement-based methods using the ionization chamber/ArcCHECK-3DVH software (version 3.2.0) under the same conditions of treatment anatomy and plan enables an efficient evaluation of this method. In this study, with the purpose of cross-validation, we evaluate the accuracy of a log file-based method using Elekta log files and an X-ray voxel Monte Carlo dose calculation technique in the case of leaf misalignment during prostate volumetric-modulated arc therapy. In this study, 10 prostate volumetric-modulated arc therapy plans were used. Systematic multileaf collimator leaf positional errors (±0.4 and ±0.8 mm for each single bank) were deliberately introduced into the optimized plans. Then, the delivered 3-dimensional doses to a phantom with a certain patient anatomy were estimated by our system. These doses were compared with the ionization chamber dose and the ArcCHECK-3DVH dose. For the given phantom and patient anatomy, the estimated dose strongly coincided with the ionization chamber/ArcCHECK-3DVH dose ( P < .01). In addition, good agreement between the estimated dose and the ionization chamber/ArcCHECK-3DVH dose was observed. The dose estimation accuracy of our system, which combines Elekta log files and X-ray voxel Monte Carlo dose calculation, was evaluated.

  4. The elementary discussion of volumetric modulated arc therapy using the orthogonal plane dose verification

    International Nuclear Information System (INIS)

    Shi Jinping; Chen Lixin; Xie Qiuying; Zhang Liwen; Teng Jianjian

    2012-01-01

    Objective: This study was to explore the feasibility of using the orthogonal plane dose formed by the coronal and sagittal plane to verify the volumetric modulated arc therapy (VMAT) plan. Methods: The VMAT plans of 12 patients were included in this study. The orthogonal plane dose formed by the coronal and sagittal plane were measured based on the combination of 2D ionization chamber array and multicube phantom, and the point dose were measured based on a multiple hole cylindrical phantom attached with two 0.125 cm 3 ionization chamber probes. Results: In the measurement of the point dose, the average error was 1.5% in high dose area (more than 80% of maximum), and 1.7% in low dose area (less than 80% of maximum), respectively. The discrepancy of point dose measurement was 1.3% between the 2D ionization chamber array and the VMAT planning system. In the measurement of the orthogonal plane dose, the pass rate of γ were 93.7% for 2%/2 mm and 97.2% for 3%/3 mm. Conclusion: It is reliable for using the orthogonal plane dose formed by the coronal and sagittal plane to verify the VMAT plan. (authors)

  5. Gafchromic EBT-XD film: Dosimetry characterization in high-dose, volumetric-modulated arc therapy.

    Science.gov (United States)

    Miura, Hideharu; Ozawa, Shuichi; Hosono, Fumika; Sumida, Naoki; Okazue, Toshiya; Yamada, Kiyoshi; Nagata, Yasushi

    2016-11-08

    Radiochromic films are important tools for assessing complex dose distributions. Gafchromic EBT-XD films have been designed for optimal performance in the 40-4,000 cGy dose range. We investigated the dosimetric characteristics of these films, including their dose-response, postexposure density growth, and dependence on scanner orientation, beam energy, and dose rate with applications to high-dose volumetric-modulated arc therapy (VMAT) verification. A 10 MV beam from a TrueBeam STx linear accelerator was used to irradiate the films with doses in the 0-4,000 cGy range. Postexposure coloration was analyzed at postirradiation times ranging from several minutes to 48 h. The films were also irradiated with 6 MV (dose rate (DR): 600 MU/min), 6 MV flattening filter-free (FFF) (DR: 1,400 MU/ min), and 10 MV FFF (DR: 2,400 MU/min) beams to determine the energy and dose-rate dependence. For clinical examinations, we compared the dose distribu-tion measured with EBT-XD films and calculated by the planning system for four VMAT cases. The red channel of the EBT-XD film exhibited a wider dynamic range than the green and blue channels. Scanner orientation yielded a variation of ~ 3% in the net optical density (OD). The difference between the film front and back scan orientations was negligible, with variation of ~ 1.3% in the net OD. The net OD increased sharply within the first 6 hrs after irradiation and gradually afterwards. No significant difference was observed for the beam energy and dose rate, with a variation of ~ 1.5% in the net OD. The gamma passing rates (at 3%, 3 mm) between the film- measured and treatment planning system (TPS)-calculated dose distributions under a high dose VMAT plan in the absolute dose mode were more than 98.9%. © 2016 The Authors.

  6. 4D dose simulation in volumetric arc therapy: Accuracy and affecting parameters

    Science.gov (United States)

    Werner, René

    2017-01-01

    Radiotherapy of lung and liver lesions has changed from normofractioned 3D-CRT to stereotactic treatment in a single or few fractions, often employing volumetric arc therapy (VMAT)-based techniques. Potential unintended interference of respiratory target motion and dynamically changing beam parameters during VMAT dose delivery motivates establishing 4D quality assurance (4D QA) procedures to assess appropriateness of generated VMAT treatment plans when taking into account patient-specific motion characteristics. Current approaches are motion phantom-based 4D QA and image-based 4D VMAT dose simulation. Whereas phantom-based 4D QA is usually restricted to a small number of measurements, the computational approaches allow simulating many motion scenarios. However, 4D VMAT dose simulation depends on various input parameters, influencing estimated doses along with mitigating simulation reliability. Thus, aiming at routine use of simulation-based 4D VMAT QA, the impact of such parameters as well as the overall accuracy of the 4D VMAT dose simulation has to be studied in detail–which is the topic of the present work. In detail, we introduce the principles of 4D VMAT dose simulation, identify influencing parameters and assess their impact on 4D dose simulation accuracy by comparison of simulated motion-affected dose distributions to corresponding dosimetric motion phantom measurements. Exploiting an ITV-based treatment planning approach, VMAT treatment plans were generated for a motion phantom and different motion scenarios (sinusoidal motion of different period/direction; regular/irregular motion). 4D VMAT dose simulation results and dose measurements were compared by local 3% / 3 mm γ-evaluation, with the measured dose distributions serving as ground truth. Overall γ-passing rates of simulations and dynamic measurements ranged from 97% to 100% (mean across all motion scenarios: 98% ± 1%); corresponding values for comparison of different day repeat measurements were

  7. Dose evaluation from multiple detector outputs using convex optimisation

    International Nuclear Information System (INIS)

    Hashimoto, M.; Iimoto, T.; Kosako, T.

    2011-01-01

    A dose evaluation using multiple radiation detectors can be improved by the convex optimisation method. It enables flexible dose evaluation corresponding to the actual radiation energy spectrum. An application to the neutron ambient dose equivalent evaluation is investigated using a mixed-gas proportional counter. The convex derives the certain neutron ambient dose with certain width corresponding to the true neutron energy spectrum. The range of the evaluated dose is comparable to the error of conventional neutron dose measurement equipments. An application to the neutron individual dose equivalent measurement is also investigated. Convexes of particular dosemeter combinations evaluate the individual dose equivalent better than the dose evaluation of a single dosemeter. The combinations of dosemeters with high orthogonality of their response characteristics tend to provide a good suitability for dose evaluation. (authors)

  8. Assessment of volumetric-modulated arc therapy for constant and variable dose rates

    Directory of Open Access Journals (Sweden)

    Mariluz De Ornelas-Couto

    2017-01-01

    Full Text Available Purpose: The aim of this study is to compare the effects of dose rate on volumetric-modulated arc therapy plans to determine optimal dose rates for prostate and head and neck (HN cases. Materials and Methods: Ten prostate and ten HN cases were retrospectively studied. For each case, seven plans were generated: one variable dose rate (VDR and six constant dose rate (CDR (100–600 monitor units [MUs]/min plans. Prescription doses were: 80 Gy to planning target volume (PTV for the prostate cases, and 70, 60, and 54 Gy to PTV1, PTV2, and PTV3, respectively, for HN cases. Plans were normalized to 95% of the PTV and PTV1, respectively, with the prescription dose. Plans were assessed using Dose-Volume-Histogram metrics, homogeneity index, conformity index, MUs, and delivery time. Results: For the prostate cases, significant differences were found for rectum D35 between VDR and all CDR plans, except CDR500. Furthermore, VDR was significantly different than CDR100 and 200 for bladder D50. Delivery time for all CDR plans and MUs for CDR400–600 were significantly higher when compared to VDR. HN cases showed significant differences between VDR and CDR100, 500 and 600 for D2 to the cord and brainstem. Significant differences were found for delivery time and MUs for all CDR plans, except CDR100 for number of MUs. Conclusion: The most significant differences were observed in delivery time and number of MUs. All-in-all, the best CDR for prostate cases was found to be 300 MUs/min and 200 or 300 MUs/min for HN cases. However, VDR plans are still the choice in terms of MU efficiency and plan quality.

  9. The accuracy evaluation according to dose delivery interruption and restart for volumetric modulated arc therapy

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Dong Hyung; Bae, Sun Myung; Kwak, Jung Won; Kang, Tae Young; Bck, Geum Mun [Dept. of Radiation Oncology, Asan Medical Center, Seoul(Korea, Republic of)

    2013-03-15

    The accurate movement of gantry rotation, collimator and correct application of dose rate are very important to approach the successful performance of Volumetric Modulated Arc Therapy (VMAT), because it is tightly interlocked with a complex treatment plan. The interruption and restart of dose delivery, however, are able to occur on treatment by various factors of a treatment machine and treatment plan. If unexpected problems of a treat machine or a patient interrupt the VMAT, the movement of treatment machine for delivering the remaining dose will be restarted at the start point. In this investigation, We would like to know the effect of interruptions and restart regarding dose delivery at VMAT. Treatment plans of 10 patients who had been treated at our center were used to measure and compare the dose distribution of each VMAT after converting to a form of digital image and communications in Medicine (DICOM) with treatment planning system (Eclipse V 10.0, Varian, USA). We selected the 6 MV photon energy of Trilogy (Varian, USA) and used OmniPro I'mRT system (V 1.7b, IBA dosimetry, Germany) to analyze the data that were acquired through this measurement with two types of interruptions four times for each case. The door interlock and the beam-off were used to stop and then to restart the dose delivery of VMAT. The gamma index in OmniPro I'mRT system and T-test in Microsoft Excel 2007 were used to evaluate the result of this investigation. The deviations of average gamma index in cases with door interlock, beam-off and without interruption on VMAT are 0.141, 0.128 and 0.1. The standard deviations of acquired gamma values are 0.099, 0.091, 0.071 and The maximum gamma value in each case is 0.413, 0.379, 0.286, respectively. This analysis has a 95-percent confidence level and the P-value of T-test is under 0.05. Gamma pass rate (3%, 3 mm) is acceptable in all of measurements. As a result, We could make sure that the interruption of this investgation are not

  10. Online dose reconstruction for tracked volumetric arc therapy: Real-time implementation and offline quality assurance for prostate SBRT.

    Science.gov (United States)

    Kamerling, Cornelis Ph; Fast, Martin F; Ziegenhein, Peter; Menten, Martin J; Nill, Simeon; Oelfke, Uwe

    2017-11-01

    Firstly, this study provides a real-time implementation of online dose reconstruction for tracked volumetric arc therapy (VMAT). Secondly, this study describes a novel offline quality assurance tool, based on commercial dose calculation algorithms. Online dose reconstruction for VMAT is a computationally challenging task in terms of computer memory usage and calculation speed. To potentially reduce the amount of memory used, we analyzed the impact of beam angle sampling for dose calculation on the accuracy of the dose distribution. To establish the performance of the method, we planned two single-arc VMAT prostate stereotactic body radiation therapy cases for delivery with dynamic MLC tracking. For quality assurance of our online dose reconstruction method we have also developed a stand-alone offline dose reconstruction tool, which utilizes the RayStation treatment planning system to calculate dose. For the online reconstructed dose distributions of the tracked deliveries, we could establish strong resemblance for 72 and 36 beam co-planar equidistant beam samples with less than 1.2% deviation for the assessed dose-volume indicators (clinical target volume D98 and D2, and rectum D2). We could achieve average runtimes of 28-31 ms per reported MLC aperture for both dose computation and accumulation, meeting our real-time requirement. To cross-validate the offline tool, we have compared the planned dose to the offline reconstructed dose for static deliveries and found excellent agreement (3%/3 mm global gamma passing rates of 99.8%-100%). Being able to reconstruct dose during delivery enables online quality assurance and online replanning strategies for VMAT. The offline quality assurance tool provides the means to validate novel online dose reconstruction applications using a commercial dose calculation engine. © 2017 The Authors. Medical Physics published by Wiley Periodicals, Inc. on behalf of American Association of Physicists in Medicine.

  11. Radiation-induced liver disease after stereotactic body radiotherapy for small hepatocellular carcinoma: clinical and dose-volumetric parameters

    International Nuclear Information System (INIS)

    Jung, Jinhong; Choi, Eun Kyung; Kim, Jong Hoon; Yoon, Sang Min; Kim, So Yeon; Cho, Byungchul; Park, Jin-hong; Kim, Su Ssan; Song, Si Yeol; Lee, Sang-wook; Ahn, Seung Do

    2013-01-01

    To investigate the clinical and dose–volumetric parameters that predict the risk of radiation-induced liver disease (RILD) for patients with small, unresectable hepatocellular carcinoma (HCC) treated with stereotactic body radiotherapy (SBRT). Between March 2007 and December 2009, 92 patients with HCC treated with SBRT were reviewed for RILD within 3 months of completing treatment. RILD was evaluated according to the Common Terminology Criteria for Adverse Events, version 3.0. A dose of 10–20 Gy (median, 15 Gy) per fraction was given over 3–4 consecutive days for a total dose of 30–60 Gy (median, 45 Gy). The following clinical and dose–volumetric parameters were examined: age, gender, Child-Pugh class, presence of hepatitis B virus, gross tumor volume, normal liver volume, radiation dose, fraction size, mean dose to the normal liver, and normal liver volumes receiving from < 5 Gy to < 60 Gy (in increments of 5 Gy). Seventeen (18.5%) of the 92 patients developed grade 2 or worse RILD after SBRT (49 patients in grade 1, 11 in grade 2, and 6 in ≥ grade 3). On univariate analysis, Child-Pugh class was identified as a significant clinical parameter, while normal liver volume and normal liver volumes receiving from < 15 Gy to < 60 Gy were the significant dose–volumetric parameters. Upon multivariate analysis, only Child-Pugh class was a significant parameter for predicting grade 2 or worse RILD. The Child-Pugh B cirrhosis was found to have a significantly greater susceptibility to the development of grade 2 or worse RILD after SBRT in patients with small, unresectable HCC. Additional efforts aimed at testing other models to predict the risk of RILD in a large series of HCC patients treated with SBRT are needed

  12. A feasibility study for image guided radiotherapy using low dose, high speed, cone beam X-ray volumetric imaging

    International Nuclear Information System (INIS)

    Sykes, Jonathan R.; Amer, Ali; Czajka, Jadwiga; Moore, Christopher J.

    2005-01-01

    Background and purpose: Image Guidance of patient set-up for radiotherapy can be achieved by acquiring X-ray volumetric images (XVI) with Elekta Synergy and registering these to the planning CT scan. This enables full 3D registration of structures from similar 3D imaging modalities and offers superior image quality, rotational set-up information and a large field of view. This study uses the head section of the Rando phantom to demonstrate a new paradigm of faster, lower dose XVI that still allows registration to high precision. Materials and methods: One high exposure XVI scan and one low exposure XVI scan were performed with a Rando Head Phantom. The second scan was used to simulate ultra low dose, fast acquisition, full and half scans by discarding a large number of projections before reconstruction. Dose measurements were performed using Thermo Luminescent Dosimeters (TLD) and an ion chamber. The reconstructed XVI scans were automatically registered with a helical CT scan of the Rando Head using the volumetric, grey-level, cross-correlation algorithm implemented in the Syntegra software package (Philips Medical Systems). Reproducibility of the registration process was investigated. Results: In both XVI scans the body surface, bone-tissue and tissue air interfaces were clearly visible. Although the subjective image quality of the low dose cone beam scan was reduced, registration of both cone beam scans with the planning CT scan agreed within 0.1 mm and 0.1 deg. Dose to the patient was reduced from 28 mGy to less than 1 mGy and the equivalent scan speed reduced to one minute or less. Conclusions: Automatic 3D registration of high speed, ultra low dose XVI scans with the planning CT scan can be used for precision 3D patient set-up verification/image guidance on a daily basis with out loss of accuracy when compared to higher dose XVI scans

  13. Radiation therapy for gastric mucosa-associated lymphoid tissue lymphoma: Dose-volumetric analysis and its clinical implications

    International Nuclear Information System (INIS)

    Lim, Hyeon Won; Kim, Tae Hyun; Choi, Il Ju; Kim, Chan Gyoo; Lee, Jong Yeul; Cho, Soo Jeong; Eom, Hyeon Seok; Moon, Sung Ho; Kim, Dae Yong

    2016-01-01

    To assess the clinical outcomes of radiotherapy (RT) using two-dimensional (2D) and three-dimensional conformal RT (3D-CRT) for patients with gastric mucosa-associated lymphoid tissue (MALT) lymphoma to evaluate the effectiveness of involved field RT with moderate-dose and to evaluate the benefit of 3D-CRT comparing with 2D-RT. Between July 2003 and March 2015, 33 patients with stage IE and IIE gastric MALT lymphoma received RT were analyzed. Of 33 patients, 17 patients (51.5%) were Helicobacter pylori (HP) negative and 16 patients (48.5%) were HP positive but refractory to HP eradication (HPE). The 2D-RT (n = 14) and 3D-CRT (n = 19) were performed and total dose was 30.6 Gy/17 fractions. Of 11 patients who RT planning data were available, dose-volumetric parameters between 2D-RT and 3D-CRT plans was compared. All patients reached complete remission (CR) eventually and median time to CR was 3 months (range, 1 to 15 months). No local relapse occurred and one patient died with second primary malignancy. Tumor response, survival, and toxicity were not significantly different between 2D-RT and 3D-CRT (p > 0.05, each). In analysis for dose-volumetric parameters, Dmax and CI for PTV were significantly lower in 3D-CRT plans than 2D-RT plans (p < 0.05, each) and Dmean and V15 for right kidney and Dmean for left kidney were significantly lower in 3D-CRT than 2D-RT (p < 0.05, each). Our data suggested that involved field RT with moderate-dose for gastric MALT lymphoma could be promising and 3D-CRT could be considered to improve the target coverage and reduce radiation dose to the both kidneys

  14. Radiation therapy for gastric mucosa-associated lymphoid tissue lymphoma: Dose-volumetric analysis and its clinical implications

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Hyeon Won; Kim, Tae Hyun; Choi, Il Ju; Kim, Chan Gyoo; Lee, Jong Yeul; Cho, Soo Jeong; Eom, Hyeon Seok; Moon, Sung Ho; Kim, Dae Yong [Research Institute and Hospital, National Cancer Center, Goyang (Korea, Republic of)

    2016-09-15

    To assess the clinical outcomes of radiotherapy (RT) using two-dimensional (2D) and three-dimensional conformal RT (3D-CRT) for patients with gastric mucosa-associated lymphoid tissue (MALT) lymphoma to evaluate the effectiveness of involved field RT with moderate-dose and to evaluate the benefit of 3D-CRT comparing with 2D-RT. Between July 2003 and March 2015, 33 patients with stage IE and IIE gastric MALT lymphoma received RT were analyzed. Of 33 patients, 17 patients (51.5%) were Helicobacter pylori (HP) negative and 16 patients (48.5%) were HP positive but refractory to HP eradication (HPE). The 2D-RT (n = 14) and 3D-CRT (n = 19) were performed and total dose was 30.6 Gy/17 fractions. Of 11 patients who RT planning data were available, dose-volumetric parameters between 2D-RT and 3D-CRT plans was compared. All patients reached complete remission (CR) eventually and median time to CR was 3 months (range, 1 to 15 months). No local relapse occurred and one patient died with second primary malignancy. Tumor response, survival, and toxicity were not significantly different between 2D-RT and 3D-CRT (p > 0.05, each). In analysis for dose-volumetric parameters, Dmax and CI for PTV were significantly lower in 3D-CRT plans than 2D-RT plans (p < 0.05, each) and Dmean and V15 for right kidney and Dmean for left kidney were significantly lower in 3D-CRT than 2D-RT (p < 0.05, each). Our data suggested that involved field RT with moderate-dose for gastric MALT lymphoma could be promising and 3D-CRT could be considered to improve the target coverage and reduce radiation dose to the both kidneys.

  15. The calculation of relative output factor and depth dose for irregular electron fields in water

    International Nuclear Information System (INIS)

    Dunscombe, Peter; McGhee, Peter; Chu, Terence

    1996-01-01

    Purpose: A technique, based on sector integration and interpolation, has been developed for the computation of both relative output factor and depth dose of irregular electron fields in water. The purpose of this study was to determine the minimum experimental data set required for the technique to yield results within accepted dosimetric tolerances. Materials and Methods: PC based software has been written to perform the calculations necessary to dosimetrically characterize irregular shaped electron fields. The field outline is entered via digitiser and the SSD and energy via the keyboard. The irregular field is segmented into sectors of specified angle (2 deg. was used for this study) and the radius of each sector computed. The central ray depth dose is reconstructed by summing the contributions from each sector deduced from calibration depth doses measured for circular fields. Relative output factors and depth doses at SSDs at which calibrations were not performed are found by interpolation. Calibration data were measured for circular fields from 2 to 9 cm diameter at 100, 105, 110, and 115 cm SSD. A clinical cut out can be characterized in less than 2 minutes including entry of the outline using this software. The performance of the technique was evaluated by comparing calculated relative output factors, surface dose and the locations of d 80 , d 50 and d 20 with experimental measurements on a variety of cut out shapes at 9 and 18 MeV. The calibration data set (derived from circular cut outs) was systematically reduced to identify the minimum required to yield an accuracy consistent with current recommendations. Results: The figure illustrates the ability of the technique to calculate the depth dose for an irregular field (shown in the insert). It was found that to achieve an accuracy of 2% in relative output factor and 2% or 2 mm (our criterion) in percentage depth dose, calibration data from five circular fields at the four SSDs spanning the range 100-115 cm

  16. Dosimetric and radiobiological comparison of volumetric modulated arc therapy, high-dose rate brachytherapy, and low-dose rate permanent seeds implant for localized prostate cancer

    International Nuclear Information System (INIS)

    Yang, Ruijie; Zhao, Nan; Liao, Anyan; Wang, Hao; Qu, Ang

    2016-01-01

    To investigate the dosimetric and radiobiological differences among volumetric modulated arc therapy (VMAT), high-dose rate (HDR) brachytherapy, and low-dose rate (LDR) permanent seeds implant for localized prostate cancer. A total of 10 patients with localized prostate cancer were selected for this study. VMAT, HDR brachytherapy, and LDR permanent seeds implant plans were created for each patient. For VMAT, planning target volume (PTV) was defined as the clinical target volume plus a margin of 5 mm. Rectum, bladder, urethra, and femoral heads were considered as organs at risk. A 78 Gy in 39 fractions were prescribed for PTV. For HDR and LDR plans, the dose prescription was D 90 of 34 Gy in 8.5 Gy per fraction, and 145 Gy to clinical target volume, respectively. The dose and dose volume parameters were evaluated for target, organs at risk, and normal tissue. Physical dose was converted to dose based on 2-Gy fractions (equivalent dose in 2 Gy per fraction, EQD 2 ) for comparison of 3 techniques. HDR and LDR significantly reduced the dose to rectum and bladder compared with VMAT. The D mean (EQD 2 ) of rectum decreased 22.36 Gy in HDR and 17.01 Gy in LDR from 30.24 Gy in VMAT, respectively. The D mean (EQD 2 ) of bladder decreased 6.91 Gy in HDR and 2.53 Gy in LDR from 13.46 Gy in VMAT. For the femoral heads and normal tissue, the mean doses were also significantly reduced in both HDR and LDR compared with VMAT. For the urethra, the mean dose (EQD 2 ) was 80.26, 70.23, and 104.91 Gy in VMAT, HDR, and LDR brachytherapy, respectively. For localized prostate cancer, both HDR and LDR brachytherapy were clearly superior in the sparing of rectum, bladder, femoral heads, and normal tissue compared with VMAT. HDR provided the advantage in sparing of urethra compared with VMAT and LDR.

  17. Cross-validation of two commercial methods for volumetric high-resolution dose reconstruction on a phantom for non-coplanar VMAT beams

    International Nuclear Information System (INIS)

    Feygelman, Vladimir; Stambaugh, Cassandra; Opp, Daniel; Zhang, Geoffrey; Moros, Eduardo G.; Nelms, Benjamin E.

    2014-01-01

    Background and purpose: Delta 4 (ScandiDos AB, Uppsala, Sweden) and ArcCHECK with 3DVH software (Sun Nuclear Corp., Melbourne, FL, USA) are commercial quasi-three-dimensional diode dosimetry arrays capable of volumetric measurement-guided dose reconstruction. A method to reconstruct dose for non-coplanar VMAT beams with 3DVH is described. The Delta 4 3D dose reconstruction on its own phantom for VMAT delivery has not been thoroughly evaluated previously, and we do so by comparison with 3DVH. Materials and methods: Reconstructed volumetric doses for VMAT plans delivered with different table angles were compared between the Delta 4 and 3DVH using gamma analysis. Results: The average γ (2% local dose-error normalization/2mm) passing rate comparing the directly measured Delta 4 diode dose with 3DVH was 98.2 ± 1.6% (1SD). The average passing rate for the full volumetric comparison of the reconstructed doses on a homogeneous cylindrical phantom was 95.6 ± 1.5%. No dependence on the table angle was observed. Conclusions: Modified 3DVH algorithm is capable of 3D VMAT dose reconstruction on an arbitrary volume for the full range of table angles. Our comparison results between different dosimeters make a compelling case for the use of electronic arrays with high-resolution 3D dose reconstruction as primary means of evaluating spatial dose distributions during IMRT/VMAT verification

  18. Fitting and benchmarking of Monte Carlo output parameters for iridium-192 high dose rate brachytherapy source

    International Nuclear Information System (INIS)

    Acquah, F.G.

    2011-01-01

    Brachytherapy, the use of radioactive sources for the treatment of tumours is an important tool in radiation oncology. Accurate calculations of dose delivered to malignant and normal tissues are the main responsibility of the Medical Physics staff. With the use of Treatment Planning System (TPS) computers now becoming a standard practice in the Radiation Oncology Departments, Independent calculations to certify the results of these commercial TPSs are important part of a good quality management system for brachytherapy implants. There are inherent errors in the dose distributions produced by these TPSs due to its failure to account for heterogeneity in the calculation algorithms and Monte Carlo (MC) method seems to be the panacea for these corrections. In this study, a fit functional form using MC output parameters was performed to reduce dose calculation uncertainty using the Matlab software curve fitting applications. This includes the modification of the AAPM TG-43 parameters to accommodate the new developments for a rapid brachytherapy dose rate calculation. Analytical computations were performed to hybridize the anisotropy function, F(r,θ) and radial dose function, g(r) into a single new function f(r,θ) for the Nucletron microSelectron High Dose Rate 'new or v2' (mHDRv2) 192 Ir brachytherapy source. In order to minimize computation time and to improve the accuracy of manual calculations, the dosimetry function f(r,θ) used fewer parameters and formulas for the fit. Using MC outputs as the standard, the percentage errors for the fits were calculated and used to evaluate the average and maximum uncertainties. Dose rate deviation between the MC data and fit were also quantified as errors(E), which showed minimal values. These results showed that the dosimetry parameters from this study as compared to those of MC outputs parameters were in good agreement and better than the results obtained from literature. The work confirms a lot of promise in building robust

  19. Feasibility of dose painting using volumetric modulated arc optimization and delivery

    DEFF Research Database (Denmark)

    Korreman, Stine; Ulrich, Silke; Bowen, Stephen

    2010-01-01

    Dose painting strategies are limited by optimization algorithms in treatment planning systems and physical constraints of the beam delivery. We investigate dose conformity using the RapidArc optimizer and beam delivery technique. Furthermore, robustness of the plans with respect to positioning un...

  20. Spectroscopic output of {sup 125}I and {sup 103}Pd low dose rate brachytherapy sources

    Energy Technology Data Exchange (ETDEWEB)

    Usher-Moga, Jacqueline; Beach, Stephen M.; DeWerd, Larry A. [Department of Medical Physics, University of Wisconsin--Madison, Madison, Wisconsin 53705 (United States); Global Physics Solutions, St. Joseph, Michigan 49085 (United States); Department of Medical Physics, University of Wisconsin-Madison, Madison, Wisconsin 53705 (United States)

    2009-01-15

    The spectroscopic output of low dose rate (LDR) brachytherapy sources is dependent on the physical design and construction of the source. Characterization of the emitted photons from 12 {sup 125}I and 3 {sup 103}Pd LDR brachytherapy source models is presented. Photon spectra, both along the transverse bisector and at several polar angles, were measured in air with a high-purity reverse electrode germanium (REGe) detector. Measured spectra were corrected to in vacuo conditions via Monte Carlo and analytical methods. The tabulated and plotted spectroscopic data provide a more complete understanding of each source model's output characteristics than can be obtained with other measurement techniques. The variation in fluorescence yield of the {sup 125}I sources containing silver caused greater differences in the emitted spectra and average energies among these seed models than was observed for the {sup 103}Pd sources or the {sup 125}I sources that do not contain silver. Angular spectroscopic data further highlighted the effects of source construction unique to each model, as well as the asymmetric output of many seeds. These data demonstrate the need for the incorporation of such physically measured output characteristics in the Monte Carlo modeling process.

  1. SU-E-T-421: Feasibility Study of Volumetric Modulated Arc Therapy with Constant Dose Rate for Endometrial Cancer

    Energy Technology Data Exchange (ETDEWEB)

    Yang, R; Wang, J [Peking University Third Hospital, Beijing, Beijing (China)

    2014-06-01

    Purpose: To investigate the feasibility, efficiency, and delivery accuracy of volumetric modulated arc therapy with constant dose rate (VMAT-CDR) for whole-pelvic radiotherapy (WPRT) of endometrial cancer. Methods: The nine-Field intensity-modulated radiotherapy (IMRT), VMAT with variable dose-rate (VMAT-VDR), and VMAT-CDR plans were created for 9 patients with endometrial cancer undergoing WPRT. The dose distribution of planning target volume (PTV), organs at risk (OARs), and normal tissue (NT) were compared. The monitor units (MUs) and treatment delivery time were also evaluated. For each VMAT-CDR plan, a dry Run was performed to assess the dosimetric accuracy with MatriXX from IBA. Results: Compared with IMRT, the VMAT-CDR plans delivered a slightly greater V20 of the bowel, bladder, pelvis bone, and NT, but significantly decreased the dose to the high-dose region of the rectum and pelvis bone. The MUs Decreased from 1105 with IMRT to 628 with VMAT-CDR. The delivery time also decreased from 9.5 to 3.2 minutes. The average gamma pass rate was 95.6% at the 3%/3 mm criteria with MatriXX pretreatment verification for 9 patients. Conclusion: VMAT-CDR can achieve comparable plan quality with significant shorter delivery time and smaller number of MUs compared with IMRT for patients with endometrial cancer undergoing WPRT. It can be accurately delivered and be an alternative to IMRT on the linear accelerator without VDR capability. This work is supported by the grant project, National Natural; Science Foundation of China (No. 81071237)

  2. An investigation of the dose distribution effect related with collimator angle in volumetric arc therapy of prostate cancer

    Directory of Open Access Journals (Sweden)

    Bora Tas

    2016-01-01

    Full Text Available To investigate the dose-volume variations of planning target volume (PTV and organ at risks (OARs in eleven prostate cancer patients planned with single and double arc volumetric modulated arc therapy (VMAT when varying collimator angle. Single and double arc VMAT treatment plans were created using Monaco5.0® with collimator angle set to 0°. All plans were normalized 7600 cGy dose to the 95% of clinical target volume (CTV volume. The single arc VMAT plans were reoptimized with different collimator angles (0°, 15°, 30°, 45°, 60°, 75°, and 90°, and for double arc VMAT plans (0–0°, 15°–345, 30–330°, 45–315°, 60–300°, 75–285°, 90–270° using the same optimization parameters. For the comparison the parameters of heterogeneity index (HI, dose-volume histogram and minimum dose to the 95% of PTV volume (D95 PTV calculated and analyzed. The best plans were verified using 2 dimensional ion chamber array IBA Matrixx® and three-dimensional IBA Compass® program. The comparison between calculation and measurement were made by the γ-index (3%/3 mm analysis. A higher D95 (PTV were found for single arc VMAT with 15° collimator angle. For double arc, VMAT with 60–300° and 75–285° collimator angles. However, lower rectum doses obtained for 75–285° collimator angles. There was no significant dose difference, based on other OARs which are bladder and femur head. When we compared single and double arc VMAT's D95 (PTV, we determined 2.44% high coverage and lower HI with double arc VMAT. All plans passed the γ-index (3%/3 mm analysis with more than 97% of the points and we had an average γ-index for CTV 0.36, for PTV 0.32 with double arc VMAT. These results were significant by Wilcoxon signed rank test statistically. The results show that dose coverage of target and OAR's doses also depend significantly on the collimator angles due to the geometry of target and OARs. Based on the results we have decided to plan prostate

  3. Dose estimate by personal music players based on weighted output voltage

    DEFF Research Database (Denmark)

    Hammershøi, Dorte; Ordoñez Pizarro, Rodrigo Eduardo; Christensen, Anders Tornvig

    2015-01-01

    The exposure by personal music players may in future be displayed to users, as described in the current draft of EN 50332-3. The suggested procedure includes a weighting of the electrical output voltages of the music player, and does not include the significance of the earphone sensitivity. It does...... not include the weighting principles necessary for sound sources close to the ears either, which constitutes an inverse head-related transfer function for the free- or diffuse field. The purpose of the present study is to assess the uncertainties in the dose estimate determined this way. Measurements for 20...

  4. Dosimetric analysis of testicular doses in prostate intensity-modulated and volumetric-modulated arc radiation therapy at different energy levels

    Energy Technology Data Exchange (ETDEWEB)

    Onal, Cem, E-mail: hcemonal@hotmail.com; Arslan, Gungor; Dolek, Yemliha; Efe, Esma

    2016-01-01

    The aim of this study is to evaluate the incidental testicular doses during prostate radiation therapy with intensity-modulated radiotherapy (IMRT) and volumetric-modulated arc radiotherapy (VMAT) at different energies. Dosimetric data of 15 patients with intermediate-risk prostate cancer who were treated with radiotherapy were analyzed. The prescribed dose was 78 Gy in 39 fractions. Dosimetric analysis compared testicular doses generated by 7-field intensity-modulated radiotherapy and volumetric-modulated arc radiotherapy with a single arc at 6, 10, and 15 MV energy levels. Testicular doses calculated from the treatment planning system and doses measured from the detectors were analyzed. Mean testicular doses from the intensity-modulated radiotherapy and volumetric-modulated arc radiotherapy per fraction calculated in the treatment planning system were 16.3 ± 10.3 cGy vs 21.5 ± 11.2 cGy (p = 0.03) at 6 MV, 13.4 ± 10.4 cGy vs 17.8 ± 10.7 cGy (p = 0.04) at 10 MV, and 10.6 ± 8.5 cGy vs 14.5 ± 8.6 cGy (p = 0.03) at 15 MV, respectively. Mean scattered testicular doses in the phantom measurements were 99.5 ± 17.2 cGy, 118.7 ± 16.4 cGy, and 193.9 ± 14.5 cGy at 6, 10, and 15 MV, respectively, in the intensity-modulated radiotherapy plans. In the volumetric-modulated arc radiotherapy plans, corresponding testicular doses per course were 90.4 ± 16.3 cGy, 103.6 ± 16.4 cGy, and 139.3 ± 14.6 cGy at 6, 10, and 15 MV, respectively. In conclusions, this study was the first to measure the incidental testicular doses by intensity-modulated radiotherapy and volumetric-modulated arc radiotherapy plans at different energy levels during prostate-only irradiation. Higher photon energy and volumetric-modulated arc radiotherapy plans resulted in higher incidental testicular doses compared with lower photon energy and intensity-modulated radiotherapy plans.

  5. Dosimetric and radiobiological comparison of volumetric modulated arc therapy, high-dose rate brachytherapy, and low-dose rate permanent seeds implant for localized prostate cancer

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Ruijie, E-mail: ruijyang@yahoo.com; Zhao, Nan; Liao, Anyan; Wang, Hao; Qu, Ang

    2016-10-01

    To investigate the dosimetric and radiobiological differences among volumetric modulated arc therapy (VMAT), high-dose rate (HDR) brachytherapy, and low-dose rate (LDR) permanent seeds implant for localized prostate cancer. A total of 10 patients with localized prostate cancer were selected for this study. VMAT, HDR brachytherapy, and LDR permanent seeds implant plans were created for each patient. For VMAT, planning target volume (PTV) was defined as the clinical target volume plus a margin of 5 mm. Rectum, bladder, urethra, and femoral heads were considered as organs at risk. A 78 Gy in 39 fractions were prescribed for PTV. For HDR and LDR plans, the dose prescription was D{sub 90} of 34 Gy in 8.5 Gy per fraction, and 145 Gy to clinical target volume, respectively. The dose and dose volume parameters were evaluated for target, organs at risk, and normal tissue. Physical dose was converted to dose based on 2-Gy fractions (equivalent dose in 2 Gy per fraction, EQD{sub 2}) for comparison of 3 techniques. HDR and LDR significantly reduced the dose to rectum and bladder compared with VMAT. The D{sub mean} (EQD{sub 2}) of rectum decreased 22.36 Gy in HDR and 17.01 Gy in LDR from 30.24 Gy in VMAT, respectively. The D{sub mean} (EQD{sub 2}) of bladder decreased 6.91 Gy in HDR and 2.53 Gy in LDR from 13.46 Gy in VMAT. For the femoral heads and normal tissue, the mean doses were also significantly reduced in both HDR and LDR compared with VMAT. For the urethra, the mean dose (EQD{sub 2}) was 80.26, 70.23, and 104.91 Gy in VMAT, HDR, and LDR brachytherapy, respectively. For localized prostate cancer, both HDR and LDR brachytherapy were clearly superior in the sparing of rectum, bladder, femoral heads, and normal tissue compared with VMAT. HDR provided the advantage in sparing of urethra compared with VMAT and LDR.

  6. On the impact of dose rate variation upon RapidArc implementation of volumetric modulated arc therapy

    International Nuclear Information System (INIS)

    Nicolini, Giorgia; Clivio, Alessandro; Cozzi, Luca; Fogliata, Antonella; Vanetti, Eugenio

    2011-01-01

    Purpose: A study was carried out to evaluate the robustness and mutual interplay of two variables concurring to generate modulation patterns of the RapidArc (RapidArc) implementation of volumetric modulated arc therapy. Dose rate (DR) and gantry speed (GS) are free parameters optimized alongside field aperture shape by the RapidArc engine; however, they are limited by machine constraints and mutually compensate in order to deliver the proper MU/deg during the gantry rotation. Methods: Four test cases (one geometrical and three clinical) were selected and RapidArc plans were optimized using maximum allowed dose rates from 100 to 600 MU/min. The maximum gantry speed was fixed at 4.8 deg/s. Qualitative analysis of DR and GS patterns from these cases was summarized together with quantitative assessment of delivery parameters. Pretreatment quality assurance measurements and scoring of plan quality aimed to determine whether preferable initial conditions might be identified or the optimization engine might be invariant to those variables and capable of providing adequate plans independently from the limits applied. Results: The results of the study were: (i) High dynamic range in MU/deg is achievable across all dose rates by means of gantry speed modulation; (ii) there is a robust compensation mechanism between the two variables; (iii) from a machine delivery point-of-view, slightly improved accuracy is achieved when lower DRs are applied; however, this does not have practical consequences since measurements and plan evaluation showed a lack of clinically relevant deviation; and (iv) reduced total treatment time is a major advantage of high DR. Conclusions: A trend toward improved plan quality for clinical cases was observed with high DR but cannot be generalized, due to the limited amount of cases investigated and the consequent limited significance of the observed differences. As a minimum benefit, the reduced total treatment time should be considered as well.

  7. Differences in dose-volumetric data between the analytical anisotropic algorithm and the x-ray voxel Monte Carlo algorithm in stereotactic body radiation therapy for lung cancer

    International Nuclear Information System (INIS)

    Mampuya, Wambaka Ange; Matsuo, Yukinori; Nakamura, Akira; Nakamura, Mitsuhiro; Mukumoto, Nobutaka; Miyabe, Yuki; Narabayashi, Masaru; Sakanaka, Katsuyuki; Mizowaki, Takashi; Hiraoka, Masahiro

    2013-01-01

    The objective of this study was to evaluate the differences in dose-volumetric data obtained using the analytical anisotropic algorithm (AAA) vs the x-ray voxel Monte Carlo (XVMC) algorithm for stereotactic body radiation therapy (SBRT) for lung cancer. Dose-volumetric data from 20 patients treated with SBRT for solitary lung cancer generated using the iPlan XVMC for the Novalis system consisting of a 6-MV linear accelerator and micro-multileaf collimators were recalculated with the AAA in Eclipse using the same monitor units and identical beam setup. The mean isocenter dose was 100.2% and 98.7% of the prescribed dose according to XVMC and AAA, respectively. Mean values of the maximal dose (D max ), the minimal dose (D min ), and dose received by 95% volume (D 95 ) for the planning target volume (PTV) with XVMC were 104.3%, 75.1%, and 86.2%, respectively. When recalculated with the AAA, those values were 100.8%, 77.1%, and 85.4%, respectively. Mean dose parameter values considered for the normal lung, namely the mean lung dose, V 5 , and V 20 , were 3.7 Gy, 19.4%, and 5.0% for XVMC and 3.6 Gy, 18.3%, and 4.7% for the AAA, respectively. All of these dose-volumetric differences between the 2 algorithms were within 5% of the prescribed dose. The effect of PTV size and tumor location, respectively, on the differences in dose parameters for the PTV between the AAA and XVMC was evaluated. A significant effect of the PTV on the difference in D 95 between the AAA and XVMC was observed (p = 0.03). Differences in the marginal doses, namely D min and D 95 , were statistically significant between peripherally and centrally located tumors (p = 0.04 and p = 0.02, respectively). Tumor location and volume might have an effect on the differences in dose-volumetric parameters. The differences between AAA and XVMC were considered to be within an acceptable range (<5 percentage points)

  8. A shape and mesh adaptive computational methodology for gamma ray dose from volumetric sources

    International Nuclear Information System (INIS)

    Mirza, N.M.; Ali, B.; Mirza, S.M.; Tufail, M.; Ahmad, N.

    1991-01-01

    Indoor external exposure to the population is dominated by gamma rays emitted from the walls and the floor of a room. A shape and mesh size adaptive flux calculational approach has been developed for a typical wall source. Parametric studies of the effect of mesh size on flux calculations have been done. The optimum value of the mesh size is found to depend strongly on distance from the source, permissible limits on uncertainty in flux predictions and on computer Central Processing Unit time. To test the computations, a typical wall source was reduced to a point, a line and an infinite volume source having finite thickness, and the computed flux values were compared with values from corresponding analytical expressions for these sources. Results indicate that the errors under optimum conditions remain less than 6% for the fluxes calculated from this approach when compared with the analytical values for the point and the line source approximations. Also, when the wall is simulated as an infinite volume source having finite thickness, the errors in computed to analytical flux ratios remain large for smaller wall dimensions. However, the errors become less than 10% when the wall dimensions are greater than ten mean free paths for 3 MeV gamma rays. Also, specific dose rates from this methodology remain within the difference of 15% for the values obtained by Monte Carlo method. (author)

  9. Final Aperture Superposition Technique applied to fast calculation of electron output factors and depth dose curves

    International Nuclear Information System (INIS)

    Faddegon, B.A.; Villarreal-Barajas, J.E.

    2005-01-01

    The Final Aperture Superposition Technique (FAST) is described and applied to accurate, near instantaneous calculation of the relative output factor (ROF) and central axis percentage depth dose curve (PDD) for clinical electron beams used in radiotherapy. FAST is based on precalculation of dose at select points for the two extreme situations of a fully open final aperture and a final aperture with no opening (fully shielded). This technique is different than conventional superposition of dose deposition kernels: The precalculated dose is differential in position of the electron or photon at the downstream surface of the insert. The calculation for a particular aperture (x-ray jaws or MLC, insert in electron applicator) is done with superposition of the precalculated dose data, using the open field data over the open part of the aperture and the fully shielded data over the remainder. The calculation takes explicit account of all interactions in the shielded region of the aperture except the collimator effect: Particles that pass from the open part into the shielded part, or visa versa. For the clinical demonstration, FAST was compared to full Monte Carlo simulation of 10x10,2.5x2.5, and 2x8 cm 2 inserts. Dose was calculated to 0.5% precision in 0.4x0.4x0.2 cm 3 voxels, spaced at 0.2 cm depth intervals along the central axis, using detailed Monte Carlo simulation of the treatment head of a commercial linear accelerator for six different electron beams with energies of 6-21 MeV. Each simulation took several hours on a personal computer with a 1.7 Mhz processor. The calculation for the individual inserts, done with superposition, was completed in under a second on the same PC. Since simulations for the pre calculation are only performed once, higher precision and resolution can be obtained without increasing the calculation time for individual inserts. Fully shielded contributions were largest for small fields and high beam energy, at the surface, reaching a maximum

  10. The impact of central lung distance, maximal heart distance, and radiation technique on the volumetric dose of the lung and heart for intact breast radiation

    International Nuclear Information System (INIS)

    Kong, F.-M.; Klein, Eric E.; Bradley, Jeffrey D.; Mansur, David B.; Taylor, Marie E.; Perez, Carlos A.; Myerson, Robert J.; Harms, William B.

    2002-01-01

    Purpose: To investigate the impact of radiographic parameter and radiation technique on the volumetric dose of lung and heart for intact breast radiation. Methods and Materials: Forty patients with both two-dimensional (2D) and computed tomographic (CT) simulations were enrolled in the study. Central lung distance (CLD), maximal heart distance (MHD), and maximal heart length (MHL) were measured under virtual simulation. Four plans were compared for each patient. Plan A used a traditional 2D tangential setup. Plan B used clinical target volume (CTV) based three-dimensional (3D) planning. Both plans C and D used a combination of a medial breast field with shallow tangents. Plan D is a further modification of plan C. Results: Under the traditional tangential setup, the mean ipsilateral lung dose and volume at 20, 30, and 40 Gy correlated linearly with CLD (R = 0.85∼0.91). The mean ipsilateral lung dose (Gy) approximated 4 times the CLD value (cm), whereas the percentage volume (%) of ipsilateral lung at 20, 30, and 40 Gy was about 10 times the CLD (cm). The mean heart dose and percentage volume at 20, 30, and 40 Gy correlated with MHD (R = 0.76∼0.80) and MHL (R 0.65∼0.75). The mean heart dose (Gy) approximated 3 times the MHD value (cm), and the percentage volume (%) of the heart at 10, 20, 30, and 40 Gy was about 6 times MHD (cm). Radiation technique impacted lung and heart dose. The 3D tangential plan (plan B) failed to reduce the volumetric dose of lung and heart from that of the 2D plan (plan A). The medial breast techniques (plans C and D) significantly decreased the volume of lung and heart receiving high doses (30 and 40 Gy). Plan D further decreased the 20 Gy volumes. By use of the medial breast technique, the lung and heart dose were not impacted by original CLD and MHD/MHL. Therefore, the improvement from the tangential technique was more remarkable for patients with CLD ≥ 3.0 cm (p<0.001). Conclusions: The CLD and MHD impact the volumetric dose of

  11. Comparison of testicular dose delivered by intensity-modulated radiation therapy (IMRT) and volumetric-modulated arc therapy (VMAT) in patients with prostate cancer

    International Nuclear Information System (INIS)

    Martin, Jeffrey M.; Handorf, Elizabeth A.; Price, Robert A.; Cherian, George; Buyyounouski, Mark K.; Chen, David Y.; Kutikov, Alexander; Johnson, Matthew E.; Ma, Chung-Ming Charlie; Horwitz, Eric M.

    2015-01-01

    A small decrease in testosterone level has been documented after prostate irradiation, possibly owing to the incidental dose to the testes. Testicular doses from prostate external beam radiation plans with either intensity-modulated radiation therapy (IMRT) or volumetric-modulated arc therapy (VMAT) were calculated to investigate any difference. Testicles were contoured for 16 patients being treated for localized prostate cancer. For each patient, 2 plans were created: 1 with IMRT and 1 with VMAT. No specific attempt was made to reduce testicular dose. Minimum, maximum, and mean doses to the testicles were recorded for each plan. Of the 16 patients, 4 received a total dose of 7800 cGy to the prostate alone, 7 received 8000 cGy to the prostate alone, and 5 received 8000 cGy to the prostate and pelvic lymph nodes. The mean (range) of testicular dose with an IMRT plan was 54.7 cGy (21.1 to 91.9) and 59.0 cGy (25.1 to 93.4) with a VMAT plan. In 12 cases, the mean VMAT dose was higher than the mean IMRT dose, with a mean difference of 4.3 cGy (p = 0.019). There was a small but statistically significant increase in mean testicular dose delivered by VMAT compared with IMRT. Despite this, it unlikely that there is a clinically meaningful difference in testicular doses from either modality

  12. Comparison of testicular dose delivered by intensity-modulated radiation therapy (IMRT) and volumetric-modulated arc therapy (VMAT) in patients with prostate cancer

    Energy Technology Data Exchange (ETDEWEB)

    Martin, Jeffrey M. [Department of Radiation Oncology, Fox Chase Cancer Center, Philadelphia, PA (United States); Handorf, Elizabeth A. [Department of Biostatistics, Fox Chase Cancer Center, Philadelphia, PA (United States); Price, Robert A.; Cherian, George [Department of Radiation Oncology, Fox Chase Cancer Center, Philadelphia, PA (United States); Buyyounouski, Mark K. [Department of Radiation Oncology, Stanford University, Stanford, CA (United States); Chen, David Y.; Kutikov, Alexander [Department of Urologic Oncology, Fox Chase Cancer Center, Philadelphia, PA (United States); Johnson, Matthew E.; Ma, Chung-Ming Charlie [Department of Radiation Oncology, Fox Chase Cancer Center, Philadelphia, PA (United States); Horwitz, Eric M., E-mail: eric.horwitz@fccc.edu [Department of Radiation Oncology, Fox Chase Cancer Center, Philadelphia, PA (United States)

    2015-10-01

    A small decrease in testosterone level has been documented after prostate irradiation, possibly owing to the incidental dose to the testes. Testicular doses from prostate external beam radiation plans with either intensity-modulated radiation therapy (IMRT) or volumetric-modulated arc therapy (VMAT) were calculated to investigate any difference. Testicles were contoured for 16 patients being treated for localized prostate cancer. For each patient, 2 plans were created: 1 with IMRT and 1 with VMAT. No specific attempt was made to reduce testicular dose. Minimum, maximum, and mean doses to the testicles were recorded for each plan. Of the 16 patients, 4 received a total dose of 7800 cGy to the prostate alone, 7 received 8000 cGy to the prostate alone, and 5 received 8000 cGy to the prostate and pelvic lymph nodes. The mean (range) of testicular dose with an IMRT plan was 54.7 cGy (21.1 to 91.9) and 59.0 cGy (25.1 to 93.4) with a VMAT plan. In 12 cases, the mean VMAT dose was higher than the mean IMRT dose, with a mean difference of 4.3 cGy (p = 0.019). There was a small but statistically significant increase in mean testicular dose delivered by VMAT compared with IMRT. Despite this, it unlikely that there is a clinically meaningful difference in testicular doses from either modality.

  13. Confidence in Assessment of Lumbar Spondylolysis Using Three-Dimensional Volumetric T2-Weighted MRI Compared With Limited Field of View, Decreased-Dose CT.

    Science.gov (United States)

    Delavan, Joshua Adam; Stence, Nicholas V; Mirsky, David M; Gralla, Jane; Fadell, Michael F

    2016-07-01

    Limited z-axis-coverage computed tomography (CT) to evaluate for pediatric lumbar spondylolysis, altering the technique such that the dose to the patient is comparable or lower than radiographs, is currently used at our institution. The objective of the study was to determine whether volumetric 3-dimensional fast spin echo magnetic resonance imaging (3D MRI) can provide equal or greater diagnostic accuracy compared with limited CT in the diagnosis of pediatric lumbar spondylolysis without ionizing radiation. Volumetric 3D MRI can provide equal or greater diagnostic accuracy compared with low-dose CT for pediatric lumbar spondylolysis without ionizing radiation. Clinical review. Level 2. Three pediatric neuroradiologists evaluated 2-dimensional (2D) MRI, 2D + 3D MRI, and limited CT examinations in 42 pediatric patients who obtained imaging for low back pain and suspected spondylolysis. As there is no gold standard for the diagnosis of spondylolysis besides surgery, interobserver agreement and degree of confidence were compared to determine which modality is preferable. Decreased-dose CT provided a greater level of agreement than 2D MRI and 2D + 3D MRI. The kappa for rater agreement with 2D MRI, 2D + 3D MRI, and CT was 0.19, 0.32, and 1.0, respectively. All raters agreed in 31%, 40%, and 100% of cases with 2D MRI, 2D + 3D MRI, and CT. Lack of confidence was significantly lower with CT (0%) than with 2D MRI (30%) and 2D + 3D MRI (25%). For diagnosing spondylolysis, radiologist agreement and confidence trended toward improvement with the addition of a volumetric 3D MRI sequence to standard 2D MRI sequences compared with 2D MRI alone; however, agreement and confidence remain significantly greater using decreased-dose CT when compared with either MRI acquisition. Decreased-dose CT of the lumbar spine remains the optimal examination to confirm a high suspicion of spondylolysis, with dose essentially equivalent to radiographs. If clinical symptoms are not classic for

  14. Is volumetric modulated arc therapy with constant dose rate a valid option in radiation therapy for head and neck cancer patients?

    Science.gov (United States)

    Didona, Annamaria; Lancellotta, Valentina; Zucchetti, Claudio; Panizza, Bianca Moira; Frattegiani, Alessandro; Iacco, Martina; Di Pilato, Anna Concetta; Saldi, Simonetta; Aristei, Cynthia

    2018-01-01

    Intensity-modulated radiotherapy (IMRT) improves dose distribution in head and neck (HN) radiation therapy. Volumetric-modulated arc therapy (VMAT), a new form of IMRT, delivers radiation in single or multiple arcs, varying dose rates (VDR-VMAT) and gantry speeds, has gained considerable attention. Constant dose rate VMAT (CDR-VMAT) associated with a fixed gantry speed does not require a dedicated linear accelerator like VDR-VMAT. The present study explored the feasibility, efficiency and delivery accuracy of CDR-VMAT, by comparing it with IMRT and VDR-VMAT in treatment planning for HN cancer. Step and shoot IMRT (SS-IMRT), CDR-VMAT and VDR-VMAT plans were created for 15 HN cancer patients and were generated by Pinnacle 3 TPS (v 9.8) using 6 MV photon energy. Three PTVs were defined to receive respectively prescribed doses of 66 Gy, 60 Gy and 54 Gy, in 30 fractions. Organs at risk (OARs) included the mandible, spinal cord, brain stem, parotids, salivary glands, esophagus, larynx and thyroid. SS-IMRT plans were based on 7 co-planar beams at fixed gantry angles. CDR-VMAT and VDR-VMAT plans, generated by the SmartArc module, used a 2-arc technique: one clockwise from 182° to 178° and the other one anti-clockwise from 178° to 182°. Comparison parameters included dose distribution to PTVs ( D mean , D 2% , D 50% , D 95% , D 98% and Homogeneity Index), maximum or mean doses to OARs, specific dose-volume data, the monitor units and treatment delivery times. Compared with SS-IMRT, CDR-VMAT significantly reduced the maximum doses to PTV1 and PTV2 and significantly improved all PTV3 parameters, except D 98% and D 95% . It significantly spared parotid and submandibular glands and was associated with a lower D mean to the larynx. Compared with VDR-VMAT, CDR-VMAT was linked to a significantly better D mean , to the PTV3 but results were worse for the parotids, left submandibular gland, esophagus and mandible. Furthermore, the D mean to the larynx was also worse

  15. Comparison of intensity-modulated radiotherapy and volumetric-modulated arc therapy dose measurement for head and neck cancer using optical stimulated luminescence dosimeter

    International Nuclear Information System (INIS)

    Lai, Lu-Han; Chuang, Keh-Shih; Lin, Hsin-Hon; Liu, Yi-Chi; Kuo, Chiung-Wen; Lin, Jao-Perng

    2017-01-01

    The in-vivo dose distributions of intensity-modulated radiotherapy (IMRT) and volumetric-modulated arc therapy (VMAT), a newly developed technique, for head and neck cancer have been investigated for several years. The present study used a head-and-neck RANDO phantom to simulate the clinical conditions of nasopharyngeal carcinoma and compare the radiation doses between VMAT and IMRT. Three types of planning target volume (PTV) profiles were targeted by reducing the PTV surface margin by 0, 3, and 5 mm. An optically stimulated luminescence dosimeter was used to measure the surface doses. The results revealed that VMAT provided on average 16.8–13.8% lower surface doses within the PTV target areas than IMRT. When the PTV margin was reduced by 0 mm, the surface doses for IMRT reached their maximum value, accounting for 75.1% of its prescribed dose (Dp); however, the Dp value of VMAT was only 61.1%. When the PTV margin was reduced by 3 or 5 mm, the surface doses decreased considerably. The observed surface doses were insufficient when the tumours invaded the body surface; however, VMAT exerted larger skin-sparing effects than IMRT when the tumours away from the skin. These results suggest that the skin doses for these two techniques are insufficient for surface tumours. Notably, VMAT can provide lower skin doses for deep tumours. - Highlights: • The surface doses of NPC patients are compared between VMAT and IMRT. • VMAT exerts lower skin dose than IMRT for deep tumours. • The surface tumour coverage is insufficient for VMAT and IMRT.

  16. The intercomparison of 137Cs irradiator output measurement and personal dose equivalent, Hp(10), using TLD and film

    International Nuclear Information System (INIS)

    Nazaroh; Susetyo Trijoko; Sri Inang Sunaryati

    2010-01-01

    Intercomparison of output measurement of 137 Cs irradiator and personal dose equivalent, Hp(10) using TLD and film have been carried out in the year of 2006 to 2008. According to IAEA recommendation, intercomparison is one of audit activities but it is performed in the spirit of collaboration and support rather than in the spirit of inspection. The aim of intercomparison of output measurement of 137 Cs irradiator is to verify the dose stated by the participant laboratories. Intercomparison is also to assess the competency of the participant, to keep traceability and consistency of measurement result, to assure that instrument work correctly and the result of evaluation was in agreement, and also for fulfilling one of the clauses of ISO-17025-2005. Besides that, this intercomparison aimed to facilitate link between the system and members of national measurement and transfer of experience in measurement technique and dose evaluation of radiation. The benefit of intercomparison is important among others as tests of proficiency in dose evaluation or measurement, upgrading quality of service and for obeying supervisor body legislation (BAPETEN). TLD was used as a means of output 137 Cs irradiator measurement, whereas film and TLD were used for dose intercomparison. This paper presented result of intercomparison of output measurement and evaluation of personal dose equivalent, Hp(10) in the year of 2006 to 2008 followed by 6 participants: Balai Pengamanan Fasilitas Kesehatan (BPFK) Jakarta, Medan, Surabaya, Makasar, PTLR and Laboratory of Keselamatan dan Kesehatan Lingkungan (KKL)-PTKMR BATAN. In this intercomparison, the dose of TLD stated by participant were compared with the dose measured by Radiation Metrology Laboratory (LMR), and the results showed the differences were within 10 %, so it was satisfied. The results of intercomparison of personal dose equivalent, Hp(10) were evaluated based on ISO/IEC Guide 43-1, 1997 analysis and expressed as E n . The values of E n

  17. 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.

  18. Effect of low dose, short-term creatine supplementation on muscle power output in elite youth soccer players.

    Science.gov (United States)

    Yáñez-Silva, Aquiles; Buzzachera, Cosme F; Piçarro, Ivan Da C; Januario, Renata S B; Ferreira, Luis H B; McAnulty, Steven R; Utter, Alan C; Souza-Junior, Tacito P

    2017-01-01

    To determine the effects of a low dose, short-term Creatine monohydrate (Cr) supplementation (0.03 g.kg.d -1 during 14 d) on muscle power output in elite youth soccer players. Using a two-group matched, double blind, placebo-controlled design, nineteen male soccer players (mean age = 17.0 ± 0.5 years) were randomly assigned to either Cr ( N  = 9) or placebo ( N  = 10) group. Before and after supplementation, participants performed a 30s Wingate Anaerobic Test (WAnT) to assess peak power output (PPO), mean power output (MPO), fatigue index (FI), and total work. There were significant increases in both PPO and MPO after the Cr supplementation period ( P  ≤ 0.05) but not the placebo period. There were also significant increases in total work, but not FI, after the Cr supplementation and placebo periods ( P  ≤ 0.05). Notably, there were differences in total work between the Cr and placebo groups after ( P  ≤ 0.05) but not before the 14 d supplementation period. There is substantial evidence to indicate that a low-dose, short-term oral Cr supplementation beneficially affected muscle power output in elite youth soccer players.

  19. Bladder dose accumulation based on a biomechanical deformable image registration algorithm in volumetric modulated arc therapy for prostate cancer

    International Nuclear Information System (INIS)

    Andersen, E S; Muren, L P; Thor, M; Petersen, J B; Tanderup, K; Sørensen, T S; Noe, K Ø; Høyer, M; Bentzen, L

    2012-01-01

    Variations in bladder position, shape and volume cause uncertainties in the doses delivered to this organ during a course of radiotherapy for pelvic tumors. The purpose of this study was to evaluate the potential of dose accumulation based on repeat imaging and deformable image registration (DIR) to improve the accuracy of bladder dose assessment. For each of nine prostate cancer patients, the initial treatment plan was re-calculated on eight to nine repeat computed tomography (CT) scans. The planned bladder dose–volume histogram (DVH) parameters were compared to corresponding parameters derived from DIR-based accumulations as well as DVH summation based on dose re-calculations. It was found that the deviations between the DIR-based accumulations and the planned treatment were substantial and ranged (−0.5–2.3) Gy and (−9.4–13.5) Gy for D 2% and D mean , respectively, whereas the deviations between DIR-based accumulations and DVH summation were small and well within 1 Gy. For the investigated treatment scenario, DIR-based bladder dose accumulation did not result in substantial improvement of dose estimation as compared to the straightforward DVH summation. Large variations were found in individual patients between the doses from the initial treatment plan and the accumulated bladder doses. Hence, the use of repeat imaging has a potential for improved accuracy in treatment dose reporting. (paper)

  20. SU-E-T-166: Evaluation of Integral Dose in Intensity-Modulated Radiotherapy and Volumetric Modulated Arc Therapy for Head and Neck Cancer Patient

    Energy Technology Data Exchange (ETDEWEB)

    Al-Basheer, A; Hunag, J; Kaminski, J; Dasher, B; Howington, J; Stewart, J; Martin, D; Kong, F; Jin, J [Georgia Regents University, Augusta, GA (Georgia)

    2014-06-01

    Purpose: Volumetric Modulated Arc Therapy (VMAT) usually achieves higher conformity of radiation doses to targets and less delivery time than Intensity Modulated Radiation Therapy (IMRT). We hypothesized that VMAT will increase integral dose (ID) to patients which will decrease the count of white blood count (WBC) lymphocytes, and consequently has a subsequent impact on the immune system. The purpose of this study is to evaluate the ID to patients undergoing IMRT and VMAT for Head and Neck cancers and its impact on the immune system. Methods: As a pilot study, 30 head and neck patients who received 9-fields IMRT or 3-arcs Radip-Arcbased VMAT were included in this study. Ten of these patients who received the VMAT plans were re-planned using IMRT with the same objectives. ID was calculated for all cases. All patients also had a baseline WBC obtained prior to treatment, and 3 sets of labs drawn during the course of radiation treatment. Results: For the 10 re-planned patients, the mean ID was 13.3 Gy/voxel (range 10.2–17.5 Gy/voxel) for the 9-fields IMRT plans, and was 15.9 Gy/voxel (range 12.4-20.9 Gy/voxel) for the 3-Arc VMAT plan (p=0.01). The integral dose was significant correlated with reducing WBC count during RT even when controlling for concurrent chemotherapy (R square =0.56, p=0.008). Conclusion: Although VMAT can deliver higher radiation dose conformality to targets, this benefit is achieved generally at the cost of greater integral doses to normal tissue outside the planning target volume (PTV). Lower WBC counts during RT were associated with higher Integral doses even when controlling for concurrent chemotherapy. This study is ongoing in our Institution to exam the impact of integral doses and WBC on overall survival.

  1. Bladder dose accumulation based on a biomechanical deformable image registration algorithm in volumetric modulated arc therapy for prostate cancer

    DEFF Research Database (Denmark)

    Andersen, E S; Muren, L P; Sørensen, T S

    2012-01-01

    Variations in bladder position, shape and volume cause uncertainties in the doses delivered to this organ during a course of radiotherapy for pelvic tumors. The purpose of this study was to evaluate the potential of dose accumulation based on repeat imaging and deformable image registration (DIR)...

  2. Minimizing dose variation from the interplay effect in stereotactic radiation therapy using volumetric modulated arc therapy for lung cancer.

    Science.gov (United States)

    Kubo, Kazuki; Monzen, Hajime; Tamura, Mikoto; Hirata, Makoto; Ishii, Kentaro; Okada, Wataru; Nakahara, Ryuta; Kishimoto, Shun; Kawamorita, Ryu; Nishimura, Yasumasa

    2018-03-01

    It is important to improve the magnitude of dose variation that is caused by the interplay effect. The aim of this study was to investigate the impact of the number of breaths (NBs) to the dose variation for VMAT-SBRT to lung cancer. Data on respiratory motion and multileaf collimator (MLC) sequence were collected from the cases of 30 patients who underwent radiotherapy with VMAT-SBRT for lung cancer. The NBs in the total irradiation time with VMAT and the maximum craniocaudal amplitude of the target were calculated. The MLC sequence complexity was evaluated using the modulation complexity score for VMAT (MCSv). Static and dynamic measurements were performed using a cylindrical respiratory motion phantom and a micro ionization chamber. The 1 standard deviation which were obtained from 10 dynamic measurements for each patient were defined as dose variation caused by the interplay effect. The dose distributions were also verified with radiochromic film to detect undesired hot and cold dose spot. Dose measurements were also performed with different NBs in the same plan for 16 patients in 30 patients. The correlations between dose variations and parameters assessed for each treatment plan including NBs, MCSv, the MCSv/amplitude quotient (TMMCSv), and the MCSv/amplitude quotient × NBs product (IVS) were evaluated. Dose variation was decreased with increasing NBs, and NBs of >40 times maintained the dose variation within 3% in 15 cases. The correlation between dose variation and IVS which were considered NBs was shown stronger (R 2  = 0.43, P 40 times during irradiation of two partial arcs VMAT (i.e., NBs = 16 breaths per minute) may be suitable for VMAT-SBRT for lung cancer. © 2018 The Authors. Journal of Applied Clinical Medical Physics published by Wiley Periodicals, Inc. on behalf of American Association of Physicists in Medicine.

  3. Output factor determination for dose measurements in axial and perpendicular planes using a silicon strip detector

    Science.gov (United States)

    Abou-Haïdar, Z.; Bocci, A.; Alvarez, M. A. G.; Espino, J. M.; Gallardo, M. I.; Cortés-Giraldo, M. A.; Ovejero, M. C.; Quesada, J. M.; Arráns, R.; Prieto, M. Ruiz; Vega-Leal, A. Pérez; Nieto, F. J. Pérez

    2012-04-01

    In this work we present the output factor measurements of a clinical linear accelerator using a silicon strip detector coupled to a new system for complex radiation therapy treatment verification. The objective of these measurements is to validate the system we built for treatment verification. The measurements were performed at the Virgin Macarena University Hospital in Seville. Irradiations were carried out with a Siemens ONCOR™ linac used to deliver radiotherapy treatment for cancer patients. The linac was operating in 6 MV photon mode; the different sizes of the fields were defined with the collimation system provided within the accelerator head. The output factor was measured with the silicon strip detector in two different layouts using two phantoms. In the first, the active area of the detector was placed perpendicular to the beam axis. In the second, the innovation consisted of a cylindrical phantom where the detector was placed in an axial plane with respect to the beam. The measured data were compared with data given by a commercial treatment planning system. Results were shown to be in a very good agreement between the compared set of data.

  4. Use of FDG-PET to guide dose prescription heterogeneity in stereotactic body radiation therapy for lung cancers with volumetric modulated arc therapy: a feasibility study

    International Nuclear Information System (INIS)

    Henriques de Figueiredo, Bénédicte; Antoine, Mikael; Trouette, Renaud; Lagarde, Philippe; Petit, Adeline; Lamare, Frédéric; Hatt, Mathieu; Fernandez, Philippe

    2014-01-01

    The aim of this study was to assess if FDG-PET could guide dose prescription heterogeneity and decrease arbitrary location of hotspots in SBRT. For three patients with stage I lung cancer, a CT-simulation and a FDG-PET were registered to define respectively the PTV CT and the biological target volume (BTV). Two plans involving volumetric modulated arc therapy (VMAT) and simultaneous integrated boost (SIB) were calculated. The first plan delivered 4 × 12 Gy within the PTV CT and the second plan, with SIB, 4 × 12 Gy and 13.8 Gy (115% of the prescribed dose) within the PTV CT and the BTV respectively. The Dmax-PTV CT had to be inferior to 60 Gy (125% of the prescribed dose). Plans were evaluated through the D95%, D99% and Dmax-PTV CT , the D2 cm, the R50% and R100% and the dice similarity coefficient (DSC) between the isodose 115% and BTV. DSC allows verifying the location of the 115% isodose (ideal value = 1). The mean PTV CT and BTV were 36.7 (±12.5) and 6.5 (±2.2) cm 3 respectively. Both plans led to similar target coverage, same doses to the OARs and equivalent fall-off of the dose outside the PTV CT . On the other hand, the location of hotspots, evaluated through the DSC, was improved for the SIB plans with a mean DSC of 0.31 and 0.45 for the first and the second plans respectively. Use of PET to decrease arbitrary location of hotspots is feasible with VMAT and SIB for lung cancer

  5. Use of FDG-PET to guide dose prescription heterogeneity in stereotactic body radiation therapy for lung cancers with volumetric modulated arc therapy: a feasibility study.

    Science.gov (United States)

    de Figueiredo, Bénédicte Henriques; Antoine, Mikael; Trouette, Renaud; Lagarde, Philippe; Petit, Adeline; Lamare, Frédéric; Hatt, Mathieu; Fernandez, Philippe

    2014-12-23

    The aim of this study was to assess if FDG-PET could guide dose prescription heterogeneity and decrease arbitrary location of hotspots in SBRT. For three patients with stage I lung cancer, a CT-simulation and a FDG-PET were registered to define respectively the PTVCT and the biological target volume (BTV). Two plans involving volumetric modulated arc therapy (VMAT) and simultaneous integrated boost (SIB) were calculated. The first plan delivered 4 × 12 Gy within the PTV(CT) and the second plan, with SIB, 4 × 12 Gy and 13.8 Gy (115% of the prescribed dose) within the PTV(CT) and the BTV respectively. The Dmax-PTV(CT) had to be inferior to 60 Gy (125% of the prescribed dose). Plans were evaluated through the D95%, D99% and Dmax-PTV(CT), the D2 cm, the R50% and R100% and the dice similarity coefficient (DSC) between the isodose 115% and BTV. DSC allows verifying the location of the 115% isodose (ideal value = 1). The mean PTV(CT) and BTV were 36.7 (±12.5) and 6.5 (±2.2) cm3 respectively. Both plans led to similar target coverage, same doses to the OARs and equivalent fall-off of the dose outside the PTV(CT). On the other hand, the location of hotspots, evaluated through the DSC, was improved for the SIB plans with a mean DSC of 0.31 and 0.45 for the first and the second plans respectively. Use of PET to decrease arbitrary location of hotspots is feasible with VMAT and SIB for lung cancer.

  6. Cystic Fibrosis: Are Volumetric Ultra-Low-Dose Expiratory CT Scans Sufficient for Monitoring Related Lung Disease?

    DEFF Research Database (Denmark)

    Loeve, Martine; Lequin, Maarten H; Bruijne, Marleen de

    2009-01-01

    Purpose: To assess whether chest computed tomography (CT) scores from ultra-low-dose end-expiratory scans alone could suffice for assessment of all cystic fibrosis (CF)-related structural lung abnormalities. Materials and Methods: In this institutional review board–approved study, 20 patients...... with CF aged 6–20 years (eight males, 12 females) underwent low-dose end-inspiratory CT and ultra-low-dose end-expiratory CT. Informed consent was obtained. Scans were randomized and scored by using the Brody-II CT scoring system to assess bronchiectasis, airway wall thickening, mucus plugging......-Altman plots. Results: Median age was 12.6 years (range, 6.3–20.3 years), median forced expiratory volume in 1 second was 100% (range, 46%–127%) of the predicted value, and median forced vital capacity was 99% (range, 61%–123%) of the predicted value. Very good agreement was observed between end...

  7. SU-E-T-226: Junction Free Craniospinal Irradiation in Linear Accelerator Using Volumetric Modulated Arc Therapy : A Novel Technique Using Dose Tapering

    Energy Technology Data Exchange (ETDEWEB)

    Sarkar, B; Roy, S; Paul, S; Munshi, A; Roy, Shilpi; Jassal, K; Ganesh, T; Mohanti, BK [Fortis Memorial Research Institute, Gurgaon (India)

    2014-06-01

    Purpose: Spatially separated fields are required for craniospinal irradiation due to field size limitation in linear accelerator. Field junction shits are conventionally done to avoid hot or cold spots. Our study was aimed to demonstrate the feasibility of junction free irradiation plan of craniospinal irradiation (CSI) for Meduloblastoma cases treated in linear accelerator using Volumetric modulated arc therapy (VMAT) technique. Methods: VMAT was planned using multiple isocenters in Monaco V 3.3.0 and delivered in Elekta Synergy linear accelerator. A full arc brain and 40° posterior arc spine fields were planned using two isocentre for short (<1.3 meter height ) and 3 isocentres for taller patients. Unrestricted jaw movement was used in superior-inferior direction. Prescribed dose to PTV was achieved by partial contribution from adjacent beams. A very low dose gradient was generated to taper the isodoses over a long length (>10 cm) at the conventional field junction. Results: In this primary study five patients were planned and three patients were delivered using this novel technique. As the dose contribution from the adjacent beams were varied (gradient) to create a complete dose distribution, therefore there is no specific junction exists in the plan. The junction were extended from 10–14 cm depending on treatment plan. Dose gradient were 9.6±2.3% per cm for brain and 7.9±1.7 % per cm for spine field respectively. Dose delivery error due to positional inaccuracy was calculated for brain and spine field for ±1mm, ±2mm, ±3mm and ±5 mm were 1%–0.8%, 2%–1.6%, 2.8%–2.4% and 4.3%–4% respectively. Conclusion: Dose tapering in junction free CSI do not require a junction shift. Therefore daily imaging for all the field is also not essential. Due to inverse planning dose to organ at risk like thyroid kidney, heart and testis can be reduced significantly. VMAT gives a quicker delivery than Step and shoot or dynamic IMRT.

  8. SU-E-T-226: Junction Free Craniospinal Irradiation in Linear Accelerator Using Volumetric Modulated Arc Therapy : A Novel Technique Using Dose Tapering

    International Nuclear Information System (INIS)

    Sarkar, B; Roy, S; Paul, S; Munshi, A; Roy, Shilpi; Jassal, K; Ganesh, T; Mohanti, BK

    2014-01-01

    Purpose: Spatially separated fields are required for craniospinal irradiation due to field size limitation in linear accelerator. Field junction shits are conventionally done to avoid hot or cold spots. Our study was aimed to demonstrate the feasibility of junction free irradiation plan of craniospinal irradiation (CSI) for Meduloblastoma cases treated in linear accelerator using Volumetric modulated arc therapy (VMAT) technique. Methods: VMAT was planned using multiple isocenters in Monaco V 3.3.0 and delivered in Elekta Synergy linear accelerator. A full arc brain and 40° posterior arc spine fields were planned using two isocentre for short (<1.3 meter height ) and 3 isocentres for taller patients. Unrestricted jaw movement was used in superior-inferior direction. Prescribed dose to PTV was achieved by partial contribution from adjacent beams. A very low dose gradient was generated to taper the isodoses over a long length (>10 cm) at the conventional field junction. Results: In this primary study five patients were planned and three patients were delivered using this novel technique. As the dose contribution from the adjacent beams were varied (gradient) to create a complete dose distribution, therefore there is no specific junction exists in the plan. The junction were extended from 10–14 cm depending on treatment plan. Dose gradient were 9.6±2.3% per cm for brain and 7.9±1.7 % per cm for spine field respectively. Dose delivery error due to positional inaccuracy was calculated for brain and spine field for ±1mm, ±2mm, ±3mm and ±5 mm were 1%–0.8%, 2%–1.6%, 2.8%–2.4% and 4.3%–4% respectively. Conclusion: Dose tapering in junction free CSI do not require a junction shift. Therefore daily imaging for all the field is also not essential. Due to inverse planning dose to organ at risk like thyroid kidney, heart and testis can be reduced significantly. VMAT gives a quicker delivery than Step and shoot or dynamic IMRT

  9. Dosimetric accuracy and clinical quality of Acuros XB and AAA dose calculation algorithm for stereotactic and conventional lung volumetric modulated arc therapy plans

    International Nuclear Information System (INIS)

    Kroon, Petra S; Hol, Sandra; Essers, Marion

    2013-01-01

    The main aim of the current study was to assess the dosimetric accuracy and clinical quality of volumetric modulated arc therapy (VMAT) plans for stereotactic (stage I) and conventional (stage III) lung cancer treatments planned with Eclipse version 10.0 Anisotropic Analytical Algorithm (AAA) and Acuros XB (AXB) algorithm. The dosimetric impact of using AAA instead of AXB, and grid size 2.5 mm instead of 1.0 mm for VMAT treatment plans was evaluated. The clinical plan quality of AXB VMAT was assessed using 45 stage I and 73 stage III patients, and was compared with published results, planned with VMAT and hybrid-VMAT techniques. The dosimetric impact on near-minimum PTV dose (D 98% ) using AAA instead of AXB was large (underdose up to 12.3%) for stage I and very small (underdose up to 0.8%) for stage III lung treatments. There were no significant differences for dose volume histogram (DVH) values between grid sizes. The calculation time was significantly higher for AXB grid size 1.0 than 2.5 mm (p < 0.01). The clinical quality of the VMAT plans was at least comparable with clinical qualities given in literature of lung treatment plans with VMAT and hybrid-VMAT techniques. The average mean lung dose (MLD), lung V 20Gy and V 5Gy in this study were respectively 3.6 Gy, 4.1% and 15.7% for 45 stage I patients and 12.4 Gy, 19.3% and 46.6% for 73 stage III lung patients. The average contra-lateral lung dose V 5Gy-cont was 35.6% for stage III patients. For stereotactic and conventional lung treatments, VMAT calculated with AXB grid size 2.5 mm resulted in accurate dose calculations. No hybrid technique was needed to obtain the dose constraints. AXB is recommended instead of AAA for avoiding serious overestimation of the minimum target doses compared to the actual delivered dose

  10. SU-F-T-359: Incorporating Dose Volume Histogram Prediction Into Auto-Planning for Volumetric-Modulated Arc Therapy in Rectal Cancer

    International Nuclear Information System (INIS)

    Li, K; Chen, X; Wang, J; Lu, S; Chen, Y; Hu, W

    2016-01-01

    Purpose: To incorporate dose volume histogram (DVH) prediction into Auto-Planning for volumetric-modulated arc therapy (VMAT) treatment planning and investigate the benefit of this new technique for rectal cancer. Methods: Ninety clinically accepted VMAT plans for patients with rectal cancer were selected and trained in the RapidPlan for DVH prediction. Both internal and external validations were performed before implementing the prediction model. A new VMAT planning method (hybrid-VMAT) was created with combining the DVH prediction and Auto-Planning. For each new patient, the DVH will be predicted and individual DVH constrains will be obtained and were exported as the original optimization parameters to the Auto-Planning (Pinnacle3 treatment planning system, v9.10) for planning. A total of 20 rectal cancer patients previously treated with manual VMAT (manual-VMAT) plans were replanned using this new method. Dosimetric comparisons were performed between manual VMAT and new method plans. Results: Hybrid-VMAT shows similar PTV coverage to manual-VMAT in D2%, D98% and HI (p>0.05) and superior coverage in CI (p=0.000). For the bladder, the means of V40 and mean dose are 36.0% and 35.6Gy for hybrid-VMAT and 42% and 38.0Gy for the manual-VMAT. For the left (right) femur, the means of V30 and mean dose are 10.6% (11.6%) and 17.9Gy (19.2Gy) for the hybrid-VMAT and 25.6% (24.1%) and 27.3Gy (26.2Gy) for the manual-VMAT. The hybrid-VMAT has significantly improved the organs at risk sparing. Conclusion: The integration of DVH prediction and Auto-Planning significantly improve the VMAT plan quality in the rectal cancer radiotherapy. Our results show the benefit of the new method and will be further investigated in other tumor sites.

  11. SU-F-T-359: Incorporating Dose Volume Histogram Prediction Into Auto-Planning for Volumetric-Modulated Arc Therapy in Rectal Cancer

    Energy Technology Data Exchange (ETDEWEB)

    Li, K; Chen, X; Wang, J; Lu, S; Chen, Y; Hu, W [Fudan University Shanghai Cancer Center, Shanghai, Shanghai (China)

    2016-06-15

    Purpose: To incorporate dose volume histogram (DVH) prediction into Auto-Planning for volumetric-modulated arc therapy (VMAT) treatment planning and investigate the benefit of this new technique for rectal cancer. Methods: Ninety clinically accepted VMAT plans for patients with rectal cancer were selected and trained in the RapidPlan for DVH prediction. Both internal and external validations were performed before implementing the prediction model. A new VMAT planning method (hybrid-VMAT) was created with combining the DVH prediction and Auto-Planning. For each new patient, the DVH will be predicted and individual DVH constrains will be obtained and were exported as the original optimization parameters to the Auto-Planning (Pinnacle3 treatment planning system, v9.10) for planning. A total of 20 rectal cancer patients previously treated with manual VMAT (manual-VMAT) plans were replanned using this new method. Dosimetric comparisons were performed between manual VMAT and new method plans. Results: Hybrid-VMAT shows similar PTV coverage to manual-VMAT in D2%, D98% and HI (p>0.05) and superior coverage in CI (p=0.000). For the bladder, the means of V40 and mean dose are 36.0% and 35.6Gy for hybrid-VMAT and 42% and 38.0Gy for the manual-VMAT. For the left (right) femur, the means of V30 and mean dose are 10.6% (11.6%) and 17.9Gy (19.2Gy) for the hybrid-VMAT and 25.6% (24.1%) and 27.3Gy (26.2Gy) for the manual-VMAT. The hybrid-VMAT has significantly improved the organs at risk sparing. Conclusion: The integration of DVH prediction and Auto-Planning significantly improve the VMAT plan quality in the rectal cancer radiotherapy. Our results show the benefit of the new method and will be further investigated in other tumor sites.

  12. Comparison of radiation dose estimates, image noise, and scan duration in pediatric body imaging for volumetric and helical modes on 320-detector CT and helical mode on 64-detector CT

    International Nuclear Information System (INIS)

    Johnston, Jennifer H.; Podberesky, Daniel J.; Larson, David B.; Alsip, Christopher; Yoshizumi, Terry T.; Angel, Erin; Barelli, Alessandra; Toncheva, Greta; Egelhoff, John C.; Anderson-Evans, Colin; Nguyen, Giao B.; Frush, Donald P.; Salisbury, Shelia R.

    2013-01-01

    Advanced multidetector CT systems facilitate volumetric image acquisition, which offers theoretic dose savings over helical acquisition with shorter scan times. Compare effective dose (ED), scan duration and image noise using 320- and 64-detector CT scanners in various acquisition modes for clinical chest, abdomen and pelvis protocols. ED and scan durations were determined for 64-detector helical, 160-detector helical and volume modes under chest, abdomen and pelvis protocols on 320-detector CT with adaptive collimation and 64-detector helical mode on 64-detector CT without adaptive collimation in a phantom representing a 5-year-old child. Noise was measured as standard deviation of Hounsfield units. Compared to 64-detector helical CT, all acquisition modes on 320-detector CT resulted in lower ED and scan durations. Dose savings were greater for chest (27-46%) than abdomen/pelvis (18-28%) and chest/abdomen/pelvis imaging (8-14%). Noise was similar across scanning modes, although some protocols on 320-detector CT produced slightly higher noise. Dose savings can be achieved for chest, abdomen/pelvis and chest/abdomen/pelvis examinations on 320-detector CT compared to helical acquisition on 64-detector CT, with shorter scan durations. Although noise differences between some modes reached statistical significance, this is of doubtful diagnostic significance and will be studied further in a clinical setting. (orig.)

  13. Bio-equivalent doses of recombinent HCG and recombinent LH during ovarian stimulation result in similar oestradiol output

    DEFF Research Database (Denmark)

    Alsbjerg, Birgit; Elbaek, Helle Olesen; Laursen, Rita Jakubcionyte

    2017-01-01

    In nature, HCG is secreted by the implanting embryo from peri-implantation and onwards. In contrast, LH is mandatory for steroidogenesis and follicular development during the follicular phase, working in synergy with FSH. Moreover, LH is mandatory for the function of the corpus luteum. Although LH...... and HCG bind to the same receptor, significant molecular, structural and functional differences exist, inducing differences in bioactivity. This randomized controlled study compared the effect of recombinant FSH stimulation combined with daily either micro-dose recombinant HCG or recombinant LH...

  14. Non-coplanar volumetric-modulated arc therapy (VMAT) for craniopharyngiomas reduces radiation doses to the bilateral hippocampus: a planning study comparing dynamic conformal arc therapy, coplanar VMAT, and non-coplanar VMAT

    International Nuclear Information System (INIS)

    Uto, Megumi; Mizowaki, Takashi; Ogura, Kengo; Hiraoka, Masahiro

    2016-01-01

    Recent studies suggest that radiation-induced injuries to the hippocampus play important roles in compromising neurocognitive functioning for patients with brain tumors and it could be important to spare the hippocampus using modern planning methods for patients with craniopharyngiomas. As bilateral hippocampus are located on the same level as the planning target volume (PTV) in patients with craniopharyngioma, it seems possible to reduce doses to hippocampus using non-coplanar beams. While the use of non-coplanar beams in volumetric-modulated arc therapy (VMAT) of malignant intracranial tumors has recently been reported, no dosimetric comparison has yet been made between VMAT using non-coplanar arcs (ncVMAT) and VMAT employing only coplanar arcs (coVMAT) among patients with craniopharyngiomas. We performed a planning study comparing dose distributions to the PTV, hippocampus, and other organs at risk (OAR) of dynamic conformal arc therapy (DCAT), coVMAT, and ncVMAT. DCAT, coVMAT, and ncVMAT plans were created for 10 patients with craniopharyngiomas. The prescription dose was 52.2 Gy in 29 fractions, and 99 % of each PTV was covered by 90 % of the prescribed dose. The maximum dose was held below 107 % of the prescribed dose. CoVMAT and ncVMAT plans were formulated to satisfy the following criteria: the doses to the hippocampus were minimized, and the doses to the OAR were similar to or lower than those of DCAT. The mean equivalent doses in 2-Gy fractions to 40 % of the volumes of the bilateral hippocampus [EQD 2 (40% hippos )] were 15.4/10.8/6.5 Gy for DCAT/coVMAT/ncVMAT, respectively. The EQD 2 (40% hippos ) for ncVMAT were <7.3 Gy, which is the threshold predicting cognitive impairment, as defined by Gondi et al.. The mean doses to normal brain tissue and the conformity indices were similar for the three plans, and the homogeneity indices were significantly better for coVMAT and ncVMAT compared with DCAT. NcVMAT is more appropriate than DCAT and coVMAT for

  15. Skin dose differences between intensity-modulated radiation therapy and volumetric-modulated arc therapy and between boost and integrated treatment regimens for treating head and neck and other cancer sites in patients

    International Nuclear Information System (INIS)

    Penoncello, Gregory P.; Ding, George X.

    2016-01-01

    The purpose of this study was (1) to evaluate dose to skin between volumetric-modulated arc therapy (VMAT) and intensity-modulated radiation therapy (IMRT) treatment techniques for target sites in the head and neck, pelvis, and brain and (2) to determine if the treatment dose and fractionation regimen affect the skin dose between traditional sequential boost and integrated boost regimens for patients with head and neck cancer. A total of 19 patients and 48 plans were evaluated. The Eclipse (v11) treatment planning system was used to plan therapy in 9 patients with head and neck cancer, 5 patients with prostate cancer, and 5 patients with brain cancer with VMAT and static-field IMRT. The mean skin dose and the maximum dose to a contiguous volume of 2 cm"3 for head and neck plans and brain plans and a contiguous volume of 5 cm"3 for pelvis plans were compared for each treatment technique. Of the 9 patients with head and neck cancer, 3 underwent an integrated boost regimen. One integrated boost plan was replanned with IMRT and VMAT using a traditional boost regimen. For target sites located in the head and neck, VMAT reduced the mean dose and contiguous hot spot most noticeably in the shoulder region by 5.6% and 5.4%, respectively. When using an integrated boost regimen, the contiguous hot spot skin dose in the shoulder was larger on average than a traditional boost pattern by 26.5% and the mean skin dose was larger by 1.7%. VMAT techniques largely decrease the contiguous hot spot in the skin in the pelvis by an average of 36% compared with IMRT. For the same target coverage, VMAT can reduce the skin dose in all the regions of the body, but more noticeably in the shoulders in patients with head and neck and pelvis cancer. We also found that using integrated boost regimens in patients with head and neck cancer leads to higher shoulder skin doses compared with traditional boost regimens.

  16. Skin dose differences between intensity-modulated radiation therapy and volumetric-modulated arc therapy and between boost and integrated treatment regimens for treating head and neck and other cancer sites in patients.

    Science.gov (United States)

    Penoncello, Gregory P; Ding, George X

    2016-01-01

    The purpose of this study was (1) to evaluate dose to skin between volumetric-modulated arc therapy (VMAT) and intensity-modulated radiation therapy (IMRT) treatment techniques for target sites in the head and neck, pelvis, and brain and (2) to determine if the treatment dose and fractionation regimen affect the skin dose between traditional sequential boost and integrated boost regimens for patients with head and neck cancer. A total of 19 patients and 48 plans were evaluated. The Eclipse (v11) treatment planning system was used to plan therapy in 9 patients with head and neck cancer, 5 patients with prostate cancer, and 5 patients with brain cancer with VMAT and static-field IMRT. The mean skin dose and the maximum dose to a contiguous volume of 2cm(3) for head and neck plans and brain plans and a contiguous volume of 5cm(3) for pelvis plans were compared for each treatment technique. Of the 9 patients with head and neck cancer, 3 underwent an integrated boost regimen. One integrated boost plan was replanned with IMRT and VMAT using a traditional boost regimen. For target sites located in the head and neck, VMAT reduced the mean dose and contiguous hot spot most noticeably in the shoulder region by 5.6% and 5.4%, respectively. When using an integrated boost regimen, the contiguous hot spot skin dose in the shoulder was larger on average than a traditional boost pattern by 26.5% and the mean skin dose was larger by 1.7%. VMAT techniques largely decrease the contiguous hot spot in the skin in the pelvis by an average of 36% compared with IMRT. For the same target coverage, VMAT can reduce the skin dose in all the regions of the body, but more noticeably in the shoulders in patients with head and neck and pelvis cancer. We also found that using integrated boost regimens in patients with head and neck cancer leads to higher shoulder skin doses compared with traditional boost regimens. Copyright © 2016 American Association of Medical Dosimetrists. Published by

  17. Measurement and Analysis of Output Radiation Dose on X-Ray Device over 10 Years at Hospitals in Medan City

    Directory of Open Access Journals (Sweden)

    Herty Afrina Sianturi

    2018-01-01

    Adhikari, Suraj Raj. 2012. Effect And Application      Of Ionization Radiation (X-Ray In Living  Organism. Kaski: Volume 3.The Himalaya  Physics. Badan Pengawas Tenaga Nuklir, Peraturan Kepala BAPETEN No. 8 Tahun 2011  tentang Keselamatan Radiasi dalam Penggunaan Pesawat Sinar-X Radiologi Diagnostik dan Intervensional, 2011. BAPETEN, 1999, Surat Keputusan Kepala Bapeten nomor 01/Ka-Bapeten/V-99 tentang Kesehatan terhadap radiasi pengion, Jakarta BATAN, 2005, Disain Penahan Ruang Sinar – X, Pusdiklat, BATAN, Jakarta Bushong, Steward C. 2013. Radologic Science for Technologists. 10th edition.United State of  America : CV. Mosby Company. Kramer, H. M., dan Selbach, H. J. 2008. Extension of the Range of Definition of the Practical Peak Voltage up to 300 kV. The British Journal of  Radiologhy (81:693-698. Rassad, S. dkk, Radiologi Diagnostik, Fakultas Kedokteran Universitas Indonesia Rumah Sakit Dr Cipto Mangunkusumo, Jakarta (2000. Suryanto, Sigit Bachtiar. 2011. Analisis Pembentukan Gambar Dan Batas Toleransi Uji Kesesuaian Pada Pesawat Sinar-X Diagnostik. Prosiding Seminar Penelitian Dan Pengelolaan Perangkat Nuklir. Trikasjono, T. dkk. 2009. Analisis Keselamatan Pesawat Sinar-X di Instalasi Radiologi Rumah Sakit Umum daerah Sleman Yogyakarta. Prosiding Seminar Nasional Sains dan Teknologi Nuklir PTNBR – BATAN. Vassileva, J. 2004. A Phantom for Dose Image Quality Optimization in Chest Radiography. The British Journal of Radiologhy 75:837-842. Wadianto, Azis Muslim. 2017. Uji Akurasi Tegangan Tinggi Alat Rontgen Radiography Mobile. INOVASI, Volume XIX Nomor 1,Januari 2017

  18. Feasibility study of entrance and exit dose measurements at the contra lateral breast with alanine/electron spin resonance dosimetry in volumetric modulated radiotherapy of breast cancer

    Science.gov (United States)

    Wagner, Daniela M.; Hüttenrauch, Petra; Anton, Mathias; von Voigts-Rhetz, Philip; Zink, Klemens; Wolff, Hendrik A.

    2017-07-01

    The Physikalisch-Technische Bundesanstalt has established a secondary standard measurement system for the dose to water, D W, based on alanine/ESR (Anton et al 2013 Phys. Med. Biol. 58 3259-82). The aim of this study was to test the established measurement system for the out-of-field measurements of inpatients with breast cancer. A set of five alanine pellets were affixed to the skin of each patient at the contra lateral breast beginning at the sternum and extending over the mammilla to the distal surface. During 28 fractions with 2.2 Gy per fraction, the accumulated dose was measured in four patients. A cone beam computer tomography (CBCT) scan was generated for setup purposes before every treatment. The reference CT dataset was registered rigidly and deformably to the CBCT dataset for 28 fractions. To take the actual alanine pellet position into account, the dose distribution was calculated for every fraction using the Acuros XB algorithm. The results of the ESR measurements were compared to the calculated doses. The maximum dose measured at the sternum was 19.9 Gy  ±  0.4 Gy, decreasing to 6.8 Gy  ±  0.2 Gy at the mammilla and 4.5 Gy  ±  0.1 Gy at the distal surface of the contra lateral breast. The absolute differences between the calculated and measured doses ranged from  -1.9 Gy to 0.9 Gy. No systematic error could be seen. It was possible to achieve a combined standard uncertainty of 1.63% for D W  =  5 Gy for the measured dose. The alanine/ESR method is feasible for in vivo measurements.

  19. Image quality, radiation dose and diagnostic accuracy of 70 kVp whole brain volumetric CT perfusion imaging: a preliminary study

    Energy Technology Data Exchange (ETDEWEB)

    Fang, Xiao Kun; Ni, Qian Qian; Zhou, Chang Sheng; Chen, Guo Zhong; Luo, Song; Zhang, Long Jiang; Lu, Guang Ming [Medical School of Nanjing University, Department of Medical Imaging, Jinling Hospital, Nanjing, Jiangsu (China); Schoepf, U.J. [Medical School of Nanjing University, Department of Medical Imaging, Jinling Hospital, Nanjing, Jiangsu (China); Medical University of South Carolina, Ashley River Tower, Division of Cardiovascular Imaging, Charleston, SC (United States); Fuller, Stephen R.; De Cecco, Carlo N. [Medical University of South Carolina, Ashley River Tower, Division of Cardiovascular Imaging, Charleston, SC (United States)

    2016-11-15

    To evaluate image quality and diagnostic accuracy for acute infarct detection and radiation dose of 70 kVp whole brain CT perfusion (CTP) and CT angiography (CTA) reconstructed from CTP source data. Patients were divided into three groups (n = 50 each): group A, 80 kVp, 21 scanning time points; groups B, 70 kVp, 21 scanning time points; group C, 70 kVp, 17 scanning time points. Objective and subjective image quality of CTP and CTA were compared. Diagnostic accuracy for detecting acute infarct and cerebral artery stenosis ≥ 50 % was calculated for CTP and CTA with diffusion weighted imaging and digital subtraction angiography as reference standards. Effective radiation dose was compared. There were no differences in any perfusion parameter value between three groups (P > 0.05). No difference was found in subjective image quality between three groups (P > 0.05). Diagnostic accuracy for detecting acute infarct and vascular stenosis showed no difference between three groups (P > 0.05). Compared with group A, radiation doses of groups B and C were decreased by 28 % and 37 % (both P < 0.001), respectively. Compared with 80 kVp protocol, 70 kVp brain CTP allows comparable vascular and perfusion assessment and lower radiation dose while maintaining high diagnostic accuracy in detecting acute infarct. (orig.)

  20. Sensitivity of volumetric modulated arc therapy patient specific QA results to multileaf collimator errors and correlation to dose volume histogram based metrics.

    LENUS (Irish Health Repository)

    Coleman, Linda

    2013-11-01

    This study investigates the impact of systematic multileaf collimator (MLC) positional errors on gamma analysis results used for quality assurance (QA) of Rapidarc treatments. In addition, this study evaluates the relationship of these gamma analysis results and clinical dose volume histogram metrics (DVH) for Rapidarc treatment plans.

  1. 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.

  2. Dose planning and dose delivery in radiation therapy

    International Nuclear Information System (INIS)

    Knoeoes, T.

    1991-01-01

    A method has been developed for calibration of CT-numbers to volumetric electron density distributions using tissue substitutes of known elemental composition and experimentally determined electron density. This information have been used in a dose calculation method based on photon and electron interaction processes. The method utilizes a convolution integral between the photon fluence matrix and dose distribution kernels. Inhomogeneous media are accounted for using the theorems of Fano and O'Connor for scaling dose distribution kernels in proportion to electron density. For clinical application of a calculated dose plan, a method for prediction of accelerator output have been developed. The methods gives the number of monitor units that has to be given to obtain a certain absorbed dose to a point inside an irregular, inhomogeneous object. The method for verification of dose distributions outlined in this study makes it possible to exclude the treatment related variance contributions, making an objective evaluation of dose calculations with experiments feasible. The methods for electron density determination, dose calculation and prediction of accelerator output discussed in this study will all contribute to an increased accuracy in the mean absorbed dose to the target volume. However, a substantial gain in the accuracy for the spatial absorbed dose distribution will also follow, especially using CT for mapping of electron density together with the dose calculation algorithm. (au)

  3. MRI-based volumetric assessment of cardiac anatomy and dose reduction via active breathing control during irradiation for left-sided breast cancer

    International Nuclear Information System (INIS)

    Krauss, Daniel J.; Kestin, Larry L.; Raff, Gilbert; Yan Di; Wong, John; Gentry, Ralph; Letts, Nicola; Vargas, Carlos E.; Martinez, Alvaro A.; Vicini, Frank A.

    2005-01-01

    Purpose: Heart dose-volume analysis using computed tomography (CT) is limited because of motion artifact and poor delineation between myocardium and ventricular space. We used dedicated cardiac magnetic resonance imaging (MRI) to quantify exclusion of left ventricular (LV) myocardium via active breathing control (ABC) during left breast irradiation and to determine the correlation between irradiated whole heart and LV volumes. Methods and materials: Fifteen patients who completed adjuvant irradiation for early-stage left breast cancer participated. Treatment consisted of 45 Gy to the entire breast using ABC followed by a 16-Gy electron boost to the lumpectomy cavity. Patients underwent planning CT scans in free breathing (FB) and moderate deep inspiration breath hold (mDIBH). Electrocardiogram-gated cardiac MRI was performed in the treatment position using α-cradle immobilization. MRI scans were acquired in late diastole (LD), mid-diastole (MD), and systole (S) for both FB and mDIBH. After image fusion with the patients' radiation therapy planning CT scan, MRI LV volumes were defined for the three examined phases of the cardiac cycle, and comparative dose-volume analysis was performed. Results: Cardiac volume definition was found to differ significantly because of combinations of respiratory and intrinsic heart motion. The fraction of LV myocardium receiving 50% (22.5 Gy) of the prescribed whole breast dose (V 22.5 ) was reduced by 85.3%, 91.8%, and 94.6% via ABC for LD, MD, and S, respectively. Linear regression revealed strong correlation between MRI-defined whole heart and LV V 22.5 reduction via ABC, suggesting that LV myocardium accounts for up to approximately 50% of the excluded heart volume through this technique. Significant but weaker correlations were noted between CT-defined whole heart and LV V 22.5 reductions with marked variability in the measurements of patients with larger amounts of heart in the treatment field. Conclusions: Cardiac MRI

  4. Exploring interaction with 3D volumetric displays

    Science.gov (United States)

    Grossman, Tovi; Wigdor, Daniel; Balakrishnan, Ravin

    2005-03-01

    Volumetric displays generate true volumetric 3D images by actually illuminating points in 3D space. As a result, viewing their contents is similar to viewing physical objects in the real world. These displays provide a 360 degree field of view, and do not require the user to wear hardware such as shutter glasses or head-trackers. These properties make them a promising alternative to traditional display systems for viewing imagery in 3D. Because these displays have only recently been made available commercially (e.g., www.actuality-systems.com), their current use tends to be limited to non-interactive output-only display devices. To take full advantage of the unique features of these displays, however, it would be desirable if the 3D data being displayed could be directly interacted with and manipulated. We investigate interaction techniques for volumetric display interfaces, through the development of an interactive 3D geometric model building application. While this application area itself presents many interesting challenges, our focus is on the interaction techniques that are likely generalizable to interactive applications for other domains. We explore a very direct style of interaction where the user interacts with the virtual data using direct finger manipulations on and around the enclosure surrounding the displayed 3D volumetric image.

  5. SU-F-T-348: The Impact of Model Library Population On RapidPlan Based Dose-Volume Histograms (DVHs) Prediction for Rectal Cancer Patients Treated with Volumetric-Modulated Radiotherapy (VMAT)

    International Nuclear Information System (INIS)

    Li, K; Zhou, L; Chen, Z; Peng, J; Hu, W

    2016-01-01

    Purpose: RapidPlan uses a library consisting of expert plans from different patients to create a model that can predict achievable dose-volume histograms (DVHs) for new patients. The goal of this study is to investigate the impacts of model library population (plan numbers) on the DVH prediction for rectal cancer patients treated with volumetric-modulated radiotherapy (VMAT) Methods: Ninety clinically accepted rectal cancer patients’ VMAT plans were selected to establish 3 models, named as Model30, Model60 and Model90, with 30,60, and 90 plans in the model training. All plans had sufficient target coverage and bladder and femora sparings. Additional 10 patients were enrolled to test the DVH prediction differences with these 3 models. The predicted DVHs from these 3 models were compared and analyzed. Results: Predicted V40 (Vx, percent of volume that received x Gy for the organs at risk) and Dmean (mean dose, cGy) of the bladder were 39.84±13.38 and 2029.4±141.6 for the Model30,37.52±16.00 and 2012.5±152.2 for the Model60, and 36.33±18.35 and 2066.5±174.3 for the Model90. Predicted V30 and Dmean of the left femur were 23.33±9.96 and 1443.3±114.5 for the Model30, 21.83±5.75 and 1436.6±61.9 for the Model60, and 20.31±4.6 and 1415.0±52.4 for the Model90.There were no significant differences among the 3 models for the bladder and left femur predictions. Predicted V40 and Dmean of the right femur were 19.86±10.00 and 1403.6±115.6 (Model30),18.97±6.19 and 1401.9±68.78 (Model60), and 21.08±7.82 and 1424.0±85.3 (Model90). Although a slight lower DVH prediction of the right femur was found on the Model60, the mean differences for V30 and mean dose were less than 2% and 1%, respectively. Conclusion: There were no significant differences among Model30, Model60 and Model90 for predicting DVHs on rectal patients treated with VMAT. The impact of plan numbers for model library might be limited for cancers with similar target shape.

  6. SU-F-T-348: The Impact of Model Library Population On RapidPlan Based Dose-Volume Histograms (DVHs) Prediction for Rectal Cancer Patients Treated with Volumetric-Modulated Radiotherapy (VMAT)

    Energy Technology Data Exchange (ETDEWEB)

    Li, K; Zhou, L; Chen, Z; Peng, J; Hu, W [Fudan University Shanghai Cancer Center, Shanghai, Shanghai (China)

    2016-06-15

    Purpose: RapidPlan uses a library consisting of expert plans from different patients to create a model that can predict achievable dose-volume histograms (DVHs) for new patients. The goal of this study is to investigate the impacts of model library population (plan numbers) on the DVH prediction for rectal cancer patients treated with volumetric-modulated radiotherapy (VMAT) Methods: Ninety clinically accepted rectal cancer patients’ VMAT plans were selected to establish 3 models, named as Model30, Model60 and Model90, with 30,60, and 90 plans in the model training. All plans had sufficient target coverage and bladder and femora sparings. Additional 10 patients were enrolled to test the DVH prediction differences with these 3 models. The predicted DVHs from these 3 models were compared and analyzed. Results: Predicted V40 (Vx, percent of volume that received x Gy for the organs at risk) and Dmean (mean dose, cGy) of the bladder were 39.84±13.38 and 2029.4±141.6 for the Model30,37.52±16.00 and 2012.5±152.2 for the Model60, and 36.33±18.35 and 2066.5±174.3 for the Model90. Predicted V30 and Dmean of the left femur were 23.33±9.96 and 1443.3±114.5 for the Model30, 21.83±5.75 and 1436.6±61.9 for the Model60, and 20.31±4.6 and 1415.0±52.4 for the Model90.There were no significant differences among the 3 models for the bladder and left femur predictions. Predicted V40 and Dmean of the right femur were 19.86±10.00 and 1403.6±115.6 (Model30),18.97±6.19 and 1401.9±68.78 (Model60), and 21.08±7.82 and 1424.0±85.3 (Model90). Although a slight lower DVH prediction of the right femur was found on the Model60, the mean differences for V30 and mean dose were less than 2% and 1%, respectively. Conclusion: There were no significant differences among Model30, Model60 and Model90 for predicting DVHs on rectal patients treated with VMAT. The impact of plan numbers for model library might be limited for cancers with similar target shape.

  7. Volumetric composition of nanocomposites

    DEFF Research Database (Denmark)

    Madsen, Bo; Lilholt, Hans; Mannila, Juha

    2015-01-01

    is presented, using cellulose/epoxy and aluminosilicate/polylactate nanocomposites as case materials. The buoyancy method is used for the accurate measurements of materials density. The accuracy of the method is determined to be high, allowing the measured nanocomposite densities to be reported with 5...... significant figures. The plotting of the measured nanocomposite density as a function of the nanofibre weight content is shown to be a first good approach of assessing the porosity content of the materials. The known gravimetric composition of the nanocomposites is converted into a volumetric composition...

  8. Coaxial volumetric velocimetry

    Science.gov (United States)

    Schneiders, Jan F. G.; Scarano, Fulvio; Jux, Constantin; Sciacchitano, Andrea

    2018-06-01

    This study describes the working principles of the coaxial volumetric velocimeter (CVV) for wind tunnel measurements. The measurement system is derived from the concept of tomographic PIV in combination with recent developments of Lagrangian particle tracking. The main characteristic of the CVV is its small tomographic aperture and the coaxial arrangement between the illumination and imaging directions. The system consists of a multi-camera arrangement subtending only few degrees solid angle and a long focal depth. Contrary to established PIV practice, laser illumination is provided along the same direction as that of the camera views, reducing the optical access requirements to a single viewing direction. The laser light is expanded to illuminate the full field of view of the cameras. Such illumination and imaging conditions along a deep measurement volume dictate the use of tracer particles with a large scattering area. In the present work, helium-filled soap bubbles are used. The fundamental principles of the CVV in terms of dynamic velocity and spatial range are discussed. Maximum particle image density is shown to limit tracer particle seeding concentration and instantaneous spatial resolution. Time-averaged flow fields can be obtained at high spatial resolution by ensemble averaging. The use of the CVV for time-averaged measurements is demonstrated in two wind tunnel experiments. After comparing the CVV measurements with the potential flow in front of a sphere, the near-surface flow around a complex wind tunnel model of a cyclist is measured. The measurements yield the volumetric time-averaged velocity and vorticity field. The measurements of the streamlines in proximity of the surface give an indication of the skin-friction lines pattern, which is of use in the interpretation of the surface flow topology.

  9. Evaluation of Energy Dose and Output Power Optimum of Diode’s Laser of 450 nm and 650 nm in Photoantimicrobial Mechanisms Against Inhibition of C. Albicans Biofilm Cells

    Science.gov (United States)

    Dewi-Astuty, S.; Suhariningsih; Dyah-Astuti, S.; Baktir, A.

    2018-03-01

    Photoantimicrobial as a pathogenic microbial inhibitory therapy system such as C. albicans in biofilms forms has been studied in vitro. Mechanisms of inhibiting called inactivating used the absorb principles of a dye agents such as chlorophyll against the photon energy of diode laser which any number of ROS product depend on energy doses of a laser, time of irradiation, concentration and time of incubation the dyes agent. The inactivation profile of C. albicans biofilm cells was observed based on cell viability reduction after photoantimicrobial treatment with or without oxygenation by XTT assay test. Results show that the inhibiting significantly with the time incubation of the dye agents and the oxygen degree inside the sample. The inhibition for oxygenation biofilm’s group 10% lower than without oxygenation biofilm’s group at the maximum of reduction of cell viability occurred in the 3hour incubation group. Optimum of inactivation are 89.6% (without oxygenation) and 94.8% (with oxygenation) after irradiation with 450 nm laser (power output 128.73 at energy dose 86.09 J/cm2), While, by 650 nm laser (power output 164.53 mW at energy dose 92.52 J/cm2) irradiation treatment obtained optimum of inactivation are 89.5% (without oxygenation) and 92.3% (with oxygenation).

  10. Point absorbed dose verification for volumetric modulated arc therapy plans. A comparative study between ionization microchamber and chamber array; Verificacion de dosis absorbida en un punto para planes de arcoterapia volumetrica modulada. Estudio comparativo entre microcamara de ionizacion y matriz de camaras

    Energy Technology Data Exchange (ETDEWEB)

    Caudepon Moreno, F.; Pizarro Trigo, F.; Sanchez Jimenez, J.; Nunez Martinez, L.; Morillas Ruiz, J.; Palomo Llinares, R.

    2016-10-01

    According to the international recommendations a quality control must be made for IMRT treatments before these can be delivered. These recommendations are applied to volumetric modulated arc therapy treatments in our Department. As a part of the verifications chain, measurements of absorbed dose in a phantom point and in the phantom volume are made for a specific patient with ionization chamber and ionization chambers array, respectively. The aim of this issue is to compare measurements of absorbed dose between these two kinds of detectors. The predictions of absorbed dose from Treatment Planning System are taken as the reference one. The differences among these measurements and the reference are calculated for 105 specific patients. A statistical analysis shows that the measurements of absorbed dose with chamber and array are strongly correlated. This result allows us to eliminate from our verifications chain the measurements of absorbed dose in a phantom point with ionization chamber because these ones are included in measurements of absorbed dose in the volume with a very small statistic risk. As a result, much time can be saved in the verifications process without any lack of quality. (Author)

  11. Aspects of volumetric efficiency measurement for reciprocating engines

    Directory of Open Access Journals (Sweden)

    Pešić Radivoje B.

    2013-01-01

    Full Text Available The volumetric efficiency significantly influences engine output. Both design and dimensions of an intake and exhaust system have large impact on volumetric efficiency. Experimental equipment for measuring of airflow through the engine, which is placed in the intake system, may affect the results of measurements and distort the real picture of the impact of individual structural factors. This paper deals with the problems of experimental determination of intake airflow using orifice plates and the influence of orifice plate diameter on the results of the measurements. The problems of airflow measurements through a multi-process Otto/Diesel engine were analyzed. An original method for determining volumetric efficiency was developed based on in-cylinder pressure measurement during motored operation, and appropriate calibration of the experimental procedure was performed. Good correlation between the results of application of the original method for determination of volumetric efficiency and the results of theoretical model used in research of influence of the intake pipe length on volumetric efficiency was determined. [Acknowledgments. The paper is the result of the research within the project TR 35041 financed by the Ministry of Science and Technological Development of the Republic of Serbia

  12. TECHNIQUE OF ESTIMATION OF ERROR IN THE REFERENCE VALUE OF THE DOSE DURING THE LINEAR ACCELERATOR RADIATION OUTPUT CALIBRATION PROCEDURE. Part 2. Dependence on the characteristics of collimator, optical sourse-distance indicator, treatment field, lasers and treatment couch

    Directory of Open Access Journals (Sweden)

    Y. V. Tsitovich

    2016-01-01

    Full Text Available To ensure the safety of radiation oncology patients needed to provide consistent functional characteristics of the medical linear accelerators, which affect the accuracy of dose delivery. To this end, their quality control procedures, which include the calibration of radiation output of the linac, the error in determining the dose reference value during which must not exceed 2 %, is provided. The aim is to develop a methodology for determining the error (difference between a measured value of quantity and its true value in determining this value, depending on the characteristics of the collimator, the source to surface distance pointer, lasers, radiation field and treatment table. To achieve the objectives have been carried out dosimetric measurements of Trilogy S/N 3567 linac dose distributions, on the basis of which dose errors depending on the accuracy setting the zero position of the collimator, the deviation of the collimator rotation isocenter, the sourcesurface distance pointer accuracy, field size accuracy, the accuracy of lasers and treatment table positioning were obtained. It was found that the greatest impact on the value of the error has the error in the optical SSD indication and the error in the lasers position in the plane perpendicular to the plane of incidence of the radiation beam (up to 3.64 % for the energy of 6 MV. Dose errors caused by error in the field size were different for two photon energies, and reached 2.54 % for 6 MeV and 1.33% for 18 MeV. Errors caused by the rest of the characteristic do not exceed 1 %. Thus, it is possible to express the results of periodic quality control of these devices integrated in linac in terms of dose and use them to conduct a comprehensive assessment of the possibility of clinical use of a linear accelerator for oncology patients irradiation on the basis of the calibration of radiation output in case of development of techniques that allow to analyze the influence dosimetric

  13. Verificação do fator de calibração e indicador da qualidade do feixe de aceleradores lineares Verification of dose output and beam quality indicator in linear accelerators

    Directory of Open Access Journals (Sweden)

    Maria da Penha Silva

    2001-10-01

    Full Text Available Um programa de garantia da qualidade é um pré-requisito obrigatório para a exatidão necessária em radioterapia. Este trabalho relata parte dos testes de rotina mensal do controle da qualidade dos aceleradores lineares do Instituto Nacional do Câncer, relativos à calibração dos feixes de fótons e elétrons, no período de dois anos. Os resultados foram comparados com as recomendações do protocolo AAPM TG-40. Na análise do fator de calibração para o feixe de fótons foi encontrado um desvio máximo de 12%; para o feixe de elétrons o maior desvio encontrado foi 10%. A flutuação observada no indicador da qualidade do feixe para os feixes de elétrons foi maior que para os feixes de fótons. Os resultados confirmam a importância de um programa de garantia da qualidade em um serviço de radioterapia, permitindo correções rápidas da dose administrada ao paciente.A quality assurance program is a mandatory prerequisite for obtaining the high level of accuracy required for radiotherapy. This paper reports the results of part of the routine quality control tests for linear accelerators at the National Cancer Institute, Brazil, performed monthly over a period of two years. These tests included dose output and beam quality indicator. The results were compared with the guidelines of the AAPM TG-40 protocol. The results for the photon beams have shown dose output variations of up to 12%; for electron beams, the largest deviation found was 10%. The fluctuations observed in the beam quality indicator for the electron beams were greater than for the photon beams. These results strongly emphasize the importance of a quality assurance program in radiotherapy services in order to allow prompt corrections of the dose delivered to the patient.

  14. Output factors and scatter ratios

    Energy Technology Data Exchange (ETDEWEB)

    Shrivastava, P N; Summers, R E; Samulski, T V; Baird, L C [Allegheny General Hospital, Pittsburgh, PA (USA); Ahuja, A S; Dubuque, G L; Hendee, W R; Chhabra, A S

    1979-07-01

    Reference is made to a previous publication on output factors and scatter ratios for radiotherapy units in which it was suggested that the output factor should be included in the definitions of scatter-air ratio and tissue-maximum ratio. In the present correspondence from other authors and from the authors of the previous publication, the original definitions and the proposed changes are discussed. Radiation scatter from source and collimator degradation of beam energy and calculation of dose in tissue are considered in relation to the objective of accurate dosimetry.

  15. In Vivo Real Time Volumetric Synthetic Aperture Ultrasound Imaging

    DEFF Research Database (Denmark)

    Bouzari, Hamed; Rasmussen, Morten Fischer; Brandt, Andreas Hjelm

    2015-01-01

    Synthetic aperture (SA) imaging can be used to achieve real-time volumetric ultrasound imaging using 2-D array transducers. The sensitivity of SA imaging is improved by maximizing the acoustic output, but one must consider the limitations of an ultrasound system, both technical and biological....... This paper investigates the in vivo applicability and sensitivity of volumetric SA imaging. Utilizing the transmit events to generate a set of virtual point sources, a frame rate of 25 Hz for a 90° x 90° field-of-view was achieved. Data were obtained using a 3.5 MHz 32 x 32 elements 2-D phased array...... transducer connected to the experimental scanner (SARUS). Proper scaling is applied to the excitation signal such that intensity levels are in compliance with the U.S. Food and Drug Administration regulations for in vivo ultrasound imaging. The measured Mechanical Index and spatial-peak- temporal...

  16. Real-time volumetric scintillation dosimetry

    International Nuclear Information System (INIS)

    Beddar, S

    2015-01-01

    The goal of this brief review is to review the current status of real-time 3D scintillation dosimetry and what has been done so far in this area. The basic concept is to use a large volume of a scintillator material (liquid or solid) to measure or image the dose distributions from external radiation therapy (RT) beams in three dimensions. In this configuration, the scintillator material fulfills the dual role of being the detector and the phantom material in which the measurements are being performed. In this case, dose perturbations caused by the introduction of a detector within a phantom will not be at issue. All the detector configurations that have been conceived to date used a Charge-Coupled Device (CCD) camera to measure the light produced within the scintillator. In order to accurately measure the scintillation light, one must correct for various optical artefacts that arise as the light propagates from the scintillating centers through the optical chain to the CCD chip. Quenching, defined in its simplest form as a nonlinear response to high-linear energy transfer (LET) charged particles, is one of the disadvantages when such systems are used to measure the absorbed dose from high-LET particles such protons. However, correction methods that restore the linear dose response through the whole proton range have been proven to be effective for both liquid and plastic scintillators. Volumetric scintillation dosimetry has the potential to provide fast, high-resolution and accurate 3D imaging of RT dose distributions. Further research is warranted to optimize the necessary image reconstruction methods and optical corrections needed to achieve its full potential

  17. Visualization and computer graphics on isotropically emissive volumetric displays.

    Science.gov (United States)

    Mora, Benjamin; Maciejewski, Ross; Chen, Min; Ebert, David S

    2009-01-01

    The availability of commodity volumetric displays provides ordinary users with a new means of visualizing 3D data. Many of these displays are in the class of isotropically emissive light devices, which are designed to directly illuminate voxels in a 3D frame buffer, producing X-ray-like visualizations. While this technology can offer intuitive insight into a 3D object, the visualizations are perceptually different from what a computer graphics or visualization system would render on a 2D screen. This paper formalizes rendering on isotropically emissive displays and introduces a novel technique that emulates traditional rendering effects on isotropically emissive volumetric displays, delivering results that are much closer to what is traditionally rendered on regular 2D screens. Such a technique can significantly broaden the capability and usage of isotropically emissive volumetric displays. Our method takes a 3D dataset or object as the input, creates an intermediate light field, and outputs a special 3D volume dataset called a lumi-volume. This lumi-volume encodes approximated rendering effects in a form suitable for display with accumulative integrals along unobtrusive rays. When a lumi-volume is fed directly into an isotropically emissive volumetric display, it creates a 3D visualization with surface shading effects that are familiar to the users. The key to this technique is an algorithm for creating a 3D lumi-volume from a 4D light field. In this paper, we discuss a number of technical issues, including transparency effects due to the dimension reduction and sampling rates for light fields and lumi-volumes. We show the effectiveness and usability of this technique with a selection of experimental results captured from an isotropically emissive volumetric display, and we demonstrate its potential capability and scalability with computer-simulated high-resolution results.

  18. Commissioning of a 3D pretreatment quality-assurance system in volumetric techniques based in 2D detector arrays; Validacin de un sistema de control de calidad pre-tratamiento 3D en tecnicas volumetricas basado en matrices bidimensionales de detectores

    Energy Technology Data Exchange (ETDEWEB)

    Clemente Gutierrez, F.; Perez Vara, C.

    2015-05-01

    The present experience about intensity-modulated radiation therapy pre-treatment QA points to a paradigm shift oriented to metrics based in clinically relevant parameters. This work shows the commissioning of a QA system used in the verification of volumetric treatments based in 2D ion chamber arrays. This system accomplishes with the initial hypothesis making the dose calculation and reconstruction in actual patient anatomy possible from measurements taken during the verification process. Beam reference parameters are compared with those obtained with the system: absolute dose, output factors and relative dose distributions. Simple test cases are evaluated comparing dose-volume parameters and ion chamber-based measurements. Finally the system is applied to the verification of 12 actual clinical test cases, comparing ion chamber measurements, usual planar dose distributions analysis, dose-volume parameters from each anatomic site and 3D gamma tests. Results make the potential advantage of these systems clear compared with those based in traditional metrics. (Author)

  19. Volumetric modulated arc radiotherapy for esophageal cancer

    International Nuclear Information System (INIS)

    Vivekanandan, Nagarajan; Sriram, Padmanaban; Syam Kumar, S.A.; Bhuvaneswari, Narayanan; Saranya, Kamalakannan

    2012-01-01

    A treatment planning study was performed to evaluate the performance of volumetric arc modulation with RapidArc (RA) against 3D conformal radiation therapy (3D-CRT) and conventional intensity-modulated radiation therapy (IMRT) techniques for esophageal cancer. Computed tomgraphy scans of 10 patients were included in the study. 3D-CRT, 4-field IMRT, and single-arc and double-arc RA plans were generated with the aim to spare organs at risk (OAR) and healthy tissue while enforcing highly conformal target coverage. The planning objective was to deliver 54 Gy to the planning target volume (PTV) in 30 fractions. Plans were evaluated based on target conformity and dose-volume histograms of organs at risk (lung, spinal cord, and heart). The monitor unit (MU) and treatment delivery time were also evaluated to measure the treatment efficiency. The IMRT plan improves target conformity and spares OAR when compared with 3D-CRT. Target conformity improved with RA plans compared with IMRT. The mean lung dose was similar in all techniques. However, RA plans showed a reduction in the volume of the lung irradiated at V 20Gy and V 30Gy dose levels (range, 4.62–17.98%) compared with IMRT plans. The mean dose and D 35% of heart for the RA plans were better than the IMRT by 0.5–5.8%. Mean V 10Gy and integral dose to healthy tissue were almost similar in all techniques. But RA plans resulted in a reduced low-level dose bath (15–20 Gy) in the range of 14–16% compared with IMRT plans. The average MU needed to deliver the prescribed dose by RA technique was reduced by 20–25% compared with IMRT technique. The preliminary study on RA for esophageal cancers showed improvements in sparing OAR and healthy tissue with reduced beam-on time, whereas only double-arc RA offered improved target coverage compared with IMRT and 3D-CRT plans.

  20. Unit 16 - Output

    OpenAIRE

    Unit 16, CC in GIS; Star, Jeffrey L.

    1990-01-01

    This unit discusses issues related to GIS output, including the different types of output possible and the hardware for producing each. It describes text, graphic and digital data that can be generated by a GIS as well as line printers, dot matrix printers/plotters, pen plotters, optical scanners and cathode ray tubes (CRTs) as technologies for generating the output.

  1. VMAT QA: Measurement-guided 4D dose reconstruction on a patient

    Energy Technology Data Exchange (ETDEWEB)

    Nelms, Benjamin E.; Opp, Daniel; Robinson, Joshua; Wolf, Theresa K.; Zhang, Geoffrey; Moros, Eduardo; Feygelman, Vladimir [Canis Lupus LLC, Merrimac, Wisconsin 53561 (United States); Department of Radiation Oncology, Moffitt Cancer Center, Tampa, Florida 33612 (United States); Department of Physics, University of South Florida, Tampa, Florida 33612 (United States); Live Oak Technologies LLC, Kirkwood, Missouri 63122 (United States); Department of Radiation Oncology, Moffitt Cancer Center, Tampa, Florida 33612 (United States)

    2012-07-15

    Purpose: To develop and validate a volume-modulated arc therapy (VMAT) quality assurance (QA) tool that takes as input a time-resolved, low-density ({approx}10 mm) cylindrical surface dose map from a commercial helical diode array, and outputs a high density, volumetric, time-resolved dose matrix on an arbitrary patient dataset. This first validation study is limited to a homogeneous 'patient.'Methods: A VMAT treatment is delivered to a diode array phantom (ARCCHECK, Sun Nuclear Corp., Melbourne, FL). 3DVH software (Sun Nuclear) derives the high-density volumetric dose using measurement-guided dose reconstruction (MGDR). MGDR cylindrical phantom results are then used to perturb the three-dimensional (3D) treatment planning dose on the patient dataset, producing a semiempirical volumetric dose grid. Four-dimensional (4D) dose reconstruction on the patient is also possible by morphing individual sub-beam doses instead of the composite. For conventional (3D) dose comparison two methods were developed, using the four plans (Multi-Target, C-shape, Mock Prostate, and Head and Neck), including their structures and objectives, from the AAPM TG-119 report. First, 3DVH and treatment planning system (TPS) cumulative point doses were compared to ion chamber in a cube water-equivalent phantom ('patient'). The shape of the phantom is different from the ARCCHECK and furthermore the targets were placed asymmetrically. Second, coronal and sagittal absolute film dose distributions in the cube were compared with 3DVH and TPS. For time-resolved (4D) comparisons, three tests were performed. First, volumetric dose differences were calculated between the 3D MGDR and cumulative time-resolved patient (4D MGDR) dose at the end of delivery, where they ideally should be identical. Second, time-resolved (10 Hz sampling rate) ion chamber doses were compared to cumulative point dose vs time curves from 4D MGDR. Finally, accelerator output was varied to assess the linearity of

  2. A feasibility study of digital tomosynthesis for volumetric dental imaging

    International Nuclear Information System (INIS)

    Cho, M K; Kim, H K; Youn, H; Kim, S S

    2012-01-01

    We present a volumetric dental tomography method that compensates for insufficient projection views obtained from limited-angle scans. The reconstruction algorithm is based on the backprojection filtering method which employs apodizing filters that reduce out-of-plane blur artifacts and suppress high-frequency noise. In order to accompolish this volumetric imaging two volume-reconstructed datasets are synthesized. These individual datasets provide two different limited-angle scans performed at orthogonal angles. The obtained reconstructed images, using less than 15% of the number of projection views needed for a full skull phantom scan, demonstrate the potential use of the proposed method in dental imaging applications. This method enables a much smaller radiation dose for the patient compared to conventional dental tomography.

  3. Predicting positional error of MLC using volumetric analysis

    International Nuclear Information System (INIS)

    Hareram, E.S.

    2008-01-01

    IMRT normally using multiple beamlets (small width of the beam) for a particular field to deliver so that it is imperative to maintain the positional accuracy of the MLC in order to deliver integrated computed dose accurately. Different manufacturers have reported high precession on MLC devices with leaf positional accuracy nearing 0.1 mm but measuring and rectifying the error in this accuracy is very difficult. Various methods are used to check MLC position and among this volumetric analysis is one of the technique. Volumetric approach was adapted in our method using primus machine and 0.6cc chamber at 5 cm depth In perspex. MLC of 1 mm error introduces an error of 20%, more sensitive to other methods

  4. Input-output supervisor

    International Nuclear Information System (INIS)

    Dupuy, R.

    1970-01-01

    The input-output supervisor is the program which monitors the flow of informations between core storage and peripheral equipments of a computer. This work is composed of three parts: 1 - Study of a generalized input-output supervisor. With sample modifications it looks like most of input-output supervisors which are running now on computers. 2 - Application of this theory on a magnetic drum. 3 - Hardware requirement for time-sharing. (author) [fr

  5. Dual-gated volumetric modulated arc therapy

    International Nuclear Information System (INIS)

    Fahimian, Benjamin; Wu, Junqing; Wu, Huanmei; Geneser, Sarah; Xing, Lei

    2014-01-01

    Gated Volumetric Modulated Arc Therapy (VMAT) is an emerging radiation therapy modality for treatment of tumors affected by respiratory motion. However, gating significantly prolongs the treatment time, as delivery is only activated during a single respiratory phase. To enhance the efficiency of gated VMAT delivery, a novel dual-gated VMAT (DG-VMAT) technique, in which delivery is executed at both exhale and inhale phases in a given arc rotation, is developed and experimentally evaluated. Arc delivery at two phases is realized by sequentially interleaving control points consisting of MUs, MLC sequences, and angles of VMAT plans generated at the exhale and inhale phases. Dual-gated delivery is initiated when a respiration gating signal enters the exhale window; when the exhale delivery concludes, the beam turns off and the gantry rolls back to the starting position for the inhale window. The process is then repeated until both inhale and exhale arcs are fully delivered. DG-VMAT plan delivery accuracy was assessed using a pinpoint chamber and diode array phantom undergoing programmed motion. DG-VMAT delivery was experimentally implemented through custom XML scripting in Varian’s TrueBeam™ STx Developer Mode. Relative to single gated delivery at exhale, the treatment time was improved by 95.5% for a sinusoidal breathing pattern. The pinpoint chamber dose measurement agreed with the calculated dose within 0.7%. For the DG-VMAT delivery, 97.5% of the diode array measurements passed the 3%/3 mm gamma criterion. The feasibility of DG-VMAT delivery scheme has been experimentally demonstrated for the first time. By leveraging the stability and natural pauses that occur at end-inspiration and end-exhalation, DG-VMAT provides a practical method for enhancing gated delivery efficiency by up to a factor of two

  6. Hologlyphics: volumetric image synthesis performance system

    Science.gov (United States)

    Funk, Walter

    2008-02-01

    This paper describes a novel volumetric image synthesis system and artistic technique, which generate moving volumetric images in real-time, integrated with music. The system, called the Hologlyphic Funkalizer, is performance based, wherein the images and sound are controlled by a live performer, for the purposes of entertaining a live audience and creating a performance art form unique to volumetric and autostereoscopic images. While currently configured for a specific parallax barrier display, the Hologlyphic Funkalizer's architecture is completely adaptable to various volumetric and autostereoscopic display technologies. Sound is distributed through a multi-channel audio system; currently a quadraphonic speaker setup is implemented. The system controls volumetric image synthesis, production of music and spatial sound via acoustic analysis and human gestural control, using a dedicated control panel, motion sensors, and multiple musical keyboards. Music can be produced by external acoustic instruments, pre-recorded sounds or custom audio synthesis integrated with the volumetric image synthesis. Aspects of the sound can control the evolution of images and visa versa. Sounds can be associated and interact with images, for example voice synthesis can be combined with an animated volumetric mouth, where nuances of generated speech modulate the mouth's expressiveness. Different images can be sent to up to 4 separate displays. The system applies many novel volumetric special effects, and extends several film and video special effects into the volumetric realm. Extensive and various content has been developed and shown to live audiences by a live performer. Real world applications will be explored, with feedback on the human factors.

  7. Volumetric velocimetry for fluid flows

    Science.gov (United States)

    Discetti, Stefano; Coletti, Filippo

    2018-04-01

    In recent years, several techniques have been introduced that are capable of extracting 3D three-component velocity fields in fluid flows. Fast-paced developments in both hardware and processing algorithms have generated a diverse set of methods, with a growing range of applications in flow diagnostics. This has been further enriched by the increasingly marked trend of hybridization, in which the differences between techniques are fading. In this review, we carry out a survey of the prominent methods, including optical techniques and approaches based on medical imaging. An overview of each is given with an example of an application from the literature, while focusing on their respective strengths and challenges. A framework for the evaluation of velocimetry performance in terms of dynamic spatial range is discussed, along with technological trends and emerging strategies to exploit 3D data. While critical challenges still exist, these observations highlight how volumetric techniques are transforming experimental fluid mechanics, and that the possibilities they offer have just begun to be explored.

  8. Volumetric Visualization of Human Skin

    Science.gov (United States)

    Kawai, Toshiyuki; Kurioka, Yoshihiro

    We propose a modeling and rendering technique of human skin, which can provide realistic color, gloss and translucency for various applications in computer graphics. Our method is based on volumetric representation of the structure inside of the skin. Our model consists of the stratum corneum and three layers of pigments. The stratum corneum has also layered structure in which the incident light is reflected, refracted and diffused. Each layer of pigment has carotene, melanin or hemoglobin. The density distributions of pigments which define the color of each layer can be supplied as one of the voxel values. Surface normals of upper-side voxels are fluctuated to produce bumps and lines on the skin. We apply ray tracing approach to this model to obtain the rendered image. Multiple scattering in the stratum corneum, reflective and absorptive spectrum of pigments are considered. We also consider Fresnel term to calculate the specular component for glossy surface of skin. Some examples of rendered images are shown, which can successfully visualize a human skin.

  9. Output hardcopy devices

    CERN Document Server

    Durbeck, Robert

    1988-01-01

    Output Hardcopy Devices provides a technical summary of computer output hardcopy devices such as plotters, computer output printers, and CRT generated hardcopy. Important related technical areas such as papers, ribbons and inks, color techniques, controllers, and character fonts are also covered. Emphasis is on techniques primarily associated with printing, as well as the plotting capabilities of printing devices that can be effectively used for computer graphics in addition to their various printing functions. Comprised of 19 chapters, this volume begins with an introduction to vector and ras

  10. Volumetric Modulated Arc Therapy (VMAT) Treatment Planning for Superficial Tumors

    International Nuclear Information System (INIS)

    Zacarias, Albert S.; Brown, Mellonie F.; Mills, Michael D.

    2010-01-01

    The physician's planning objective is often a uniform dose distribution throughout the planning target volume (PTV), including superficial PTVs on or near the surface of a patient's body. Varian's Eclipse treatment planning system uses a progressive resolution optimizer (PRO), version 8.2.23, for RapidArc dynamic multileaf collimator volumetric modulated arc therapy planning. Because the PRO is a fast optimizer, optimization convergence errors (OCEs) produce dose nonuniformity in the superficial area of the PTV. We present a postsurgical cranial case demonstrating the recursive method our clinic uses to produce RapidArc treatment plans. The initial RapidArc treatment plan generated using one 360 o arc resulted in substantial dose nonuniformity in the superficial section of the PTV. We demonstrate the use of multiple arcs to produce improved dose uniformity in this region. We also compare the results of this superficial dose compensation method to the results of a recursive method of dose correction that we developed in-house to correct optimization convergence errors in static intensity-modulated radiation therapy treatment plans. The results show that up to 4 arcs may be necessary to provide uniform dose to the surface of the PTV with the current version of the PRO.

  11. WRF Model Output

    Data.gov (United States)

    U.S. Environmental Protection Agency — This dataset contains WRF model output. There are three months of data: July 2012, July 2013, and January 2013. For each month, several simulations were made: A...

  12. VMS forms Output Tables

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — These output tables contain parsed and format validated data from the various VMS forms that are sent from any given vessel, while at sea, from the VMS devices on...

  13. Governmentally amplified output volatility

    Science.gov (United States)

    Funashima, Yoshito

    2016-11-01

    Predominant government behavior is decomposed by frequency into several periodic components: updating cycles of infrastructure, Kuznets cycles, fiscal policy over business cycles, and election cycles. Little is known, however, about the theoretical impact of such cyclical behavior in public finance on output fluctuations. Based on a standard neoclassical growth model, this study intends to examine the frequency at which public investment cycles are relevant to output fluctuations. We find an inverted U-shaped relationship between output volatility and length of cycle in public investment. This implies that periodic behavior in public investment at a certain frequency range can cause aggravated output resonance. Moreover, we present an empirical analysis to test the theoretical implication, using the U.S. data in the period from 1968 to 2015. The empirical results suggest that such resonance phenomena change from low to high frequency.

  14. CMAQ Model Output

    Data.gov (United States)

    U.S. Environmental Protection Agency — CMAQ and CMAQ-VBS model output. This dataset is not publicly accessible because: Files too large. It can be accessed through the following means: via EPA's NCC tape...

  15. 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.

  16. Extended Kalman filtering for continuous volumetric MR-temperature imaging.

    Science.gov (United States)

    Denis de Senneville, Baudouin; Roujol, Sébastien; Hey, Silke; Moonen, Chrit; Ries, Mario

    2013-04-01

    Real time magnetic resonance (MR) thermometry has evolved into the method of choice for the guidance of high-intensity focused ultrasound (HIFU) interventions. For this role, MR-thermometry should preferably have a high temporal and spatial resolution and allow observing the temperature over the entire targeted area and its vicinity with a high accuracy. In addition, the precision of real time MR-thermometry for therapy guidance is generally limited by the available signal-to-noise ratio (SNR) and the influence of physiological noise. MR-guided HIFU would benefit of the large coverage volumetric temperature maps, including characterization of volumetric heating trajectories as well as near- and far-field heating. In this paper, continuous volumetric MR-temperature monitoring was obtained as follows. The targeted area was continuously scanned during the heating process by a multi-slice sequence. Measured data and a priori knowledge of 3-D data derived from a forecast based on a physical model were combined using an extended Kalman filter (EKF). The proposed reconstruction improved the temperature measurement resolution and precision while maintaining guaranteed output accuracy. The method was evaluated experimentally ex vivo on a phantom, and in vivo on a porcine kidney, using HIFU heating. On the in vivo experiment, it allowed the reconstruction from a spatio-temporally under-sampled data set (with an update rate for each voxel of 1.143 s) to a 3-D dataset covering a field of view of 142.5×285×54 mm(3) with a voxel size of 3×3×6 mm(3) and a temporal resolution of 0.127 s. The method also provided noise reduction, while having a minimal impact on accuracy and latency.

  17. Programmable segmented volumetric modulated arc therapy for respiratory coordination in pancreatic cancer

    International Nuclear Information System (INIS)

    Wu, Jian-Kuen; Wu, Chien-Jang; Cheng, Jason Chia-Hsien

    2012-01-01

    We programmably divided long-arc volumetric modulated arc therapy (VMAT) into split short arcs, each taking less than 30 s for respiratory coordination. The VMAT plans of five pancreatic cancer patients were modified; the short-arc plans had negligible dose differences and satisfied the 3%/3-mm gamma index on a MapCHECK-2 device.

  18. Oil output's changing fortunes

    International Nuclear Information System (INIS)

    Eldridge, D.

    1994-01-01

    The Petroleum Economist, previously the Petroleum Press Service, has been making annual surveys of output levels of petroleum in all the oil-producing countries since its founding in 1934. This article documents trends and changes in the major oil-producing countries output from 1934 until the present. This analysis is linked with the political and historical events accompanying these changes, notably the growth of Middle Eastern oil production, the North Sea finds and most recently, Iraq's invasion of Kuwait in 1990. (UK)

  19. Cardiac output measurement

    Directory of Open Access Journals (Sweden)

    Andreja Möller Petrun

    2014-02-01

    Full Text Available In recent years, developments in the measuring of cardiac output and other haemodynamic variables are focused on the so-called minimally invasive methods. The aim of these methods is to simplify the management of high-risk and haemodynamically unstable patients. Due to the need of invasive approach and the possibility of serious complications the use of pulmonary artery catheter has decreased. This article describes the methods for measuring cardiac output, which are based on volume measurement (Fick method, indicator dilution method, pulse wave analysis, Doppler effect, and electrical bioimpedance.

  20. Determination of output factor for 6 MV small photon beam: comparison between Monte Carlo simulation technique and microDiamond detector

    International Nuclear Information System (INIS)

    Krongkietlearts, K; Tangboonduangjit, P; Paisangittisakul, N

    2016-01-01

    In order to improve the life's quality for a cancer patient, the radiation techniques are constantly evolving. Especially, the two modern techniques which are intensity modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT) are quite promising. They comprise of many small beam sizes (beamlets) with various intensities to achieve the intended radiation dose to the tumor and minimal dose to the nearby normal tissue. The study investigates whether the microDiamond detector (PTW manufacturer), a synthetic single crystal diamond detector, is suitable for small field output factor measurement. The results were compared with those measured by the stereotactic field detector (SFD) and the Monte Carlo simulation (EGSnrc/BEAMnrc/DOSXYZ). The calibration of Monte Carlo simulation was done using the percentage depth dose and dose profile measured by the photon field detector (PFD) of the 10×10 cm 2 field size with 100 cm SSD. Comparison of the values obtained from the calculations and measurements are consistent, no more than 1% difference. The output factors obtained from the microDiamond detector have been compared with those of SFD and Monte Carlo simulation, the results demonstrate the percentage difference of less than 2%. (paper)

  1. Volumetric composition in composites and historical data

    DEFF Research Database (Denmark)

    Lilholt, Hans; Madsen, Bo

    2013-01-01

    The obtainable volumetric composition in composites is of importance for the prediction of mechanical and physical properties, and in particular to assess the best possible (normally the highest) values for these properties. The volumetric model for the composition of (fibrous) composites gives...... guidance to the optimal combination of fibre content, matrix content and porosity content, in order to achieve the best obtainable properties. Several composite materials systems have been shown to be handleable with this model. An extensive series of experimental data for the system of cellulose fibres...... and polymer (resin) was produced in 1942 – 1944, and these data have been (re-)analysed by the volumetric composition model, and the property values for density, stiffness and strength have been evaluated. Good agreement has been obtained and some further observations have been extracted from the analysis....

  2. Process conditions and volumetric composition in composites

    DEFF Research Database (Denmark)

    Madsen, Bo

    2013-01-01

    The obtainable volumetric composition in composites is linked to the gravimetric composition, and it is influenced by the conditions of the manufacturing process. A model for the volumetric composition is presented, where the volume fractions of fibers, matrix and porosity are calculated...... as a function of the fiber weight fraction, and where parameters are included for the composite microstructure, and the fiber assembly compaction behavior. Based on experimental data of composites manufactured with different process conditions, together with model predictions, different types of process related...... effects are analyzed. The applied consolidation pressure is found to have a marked effect on the volumetric composition. A power-law relationship is found to well describe the found relations between the maximum obtainable fiber volume fraction and the consolidation pressure. The degree of fiber...

  3. Concentrated fed-batch cell culture increases manufacturing capacity without additional volumetric capacity.

    Science.gov (United States)

    Yang, William C; Minkler, Daniel F; Kshirsagar, Rashmi; Ryll, Thomas; Huang, Yao-Ming

    2016-01-10

    Biomanufacturing factories of the future are transitioning from large, single-product facilities toward smaller, multi-product, flexible facilities. Flexible capacity allows companies to adapt to ever-changing pipeline and market demands. Concentrated fed-batch (CFB) cell culture enables flexible manufacturing capacity with limited volumetric capacity; it intensifies cell culture titers such that the output of a smaller facility can rival that of a larger facility. We tested this hypothesis at bench scale by developing a feeding strategy for CFB and applying it to two cell lines. CFB improved cell line A output by 105% and cell line B output by 70% compared to traditional fed-batch (TFB) processes. CFB did not greatly change cell line A product quality, but it improved cell line B charge heterogeneity, suggesting that CFB has both process and product quality benefits. We projected CFB output gains in the context of a 2000-L small-scale facility, but the output was lower than that of a 15,000-L large-scale TFB facility. CFB's high cell mass also complicated operations, eroded volumetric productivity, and showed our current processes require significant improvements in specific productivity in order to realize their full potential and savings in manufacturing. Thus, improving specific productivity can resolve CFB's cost, scale-up, and operability challenges. Copyright © 2015 Elsevier B.V. All rights reserved.

  4. Volumetric, dashboard-mounted augmented display

    Science.gov (United States)

    Kessler, David; Grabowski, Christopher

    2017-11-01

    The optical design of a compact volumetric display for drivers is presented. The system displays a true volume image with realistic physical depth cues, such as focal accommodation, parallax and convergence. A large eyebox is achieved with a pupil expander. The windshield is used as the augmented reality combiner. A freeform windshield corrector is placed at the dashboard.

  5. A 4 MV flattening filter-free beam: commissioning and application to conformal therapy and volumetric modulated arc therapy

    International Nuclear Information System (INIS)

    Stevens, S W; Rosser, K E; Bedford, J L

    2011-01-01

    Recent studies have indicated that radiotherapy treatments undertaken on a flattening filter-free (FFF) linear accelerator have a number of advantages over treatments undertaken on a conventional linear accelerator. In addition, 4 MV photon beams may give improved isodose coverage for some treatment volumes at air/tissue interfaces, compared to when utilizing the clinical standard of 6 MV photons. In order to investigate these benefits, FFF beams were established on an Elekta Beam Modulator linear accelerator for 4 MV photons. Commissioning beam data were obtained for open and wedged fields. The measured data were then imported into a treatment planning system and a beam model was commissioned. The beam model was optimized to improve dose calculations at shallow, clinically relevant depths. Following verification, the beam model was utilized in a treatment planning study, including volumetric modulated arc therapy, for a selection of lung, breast/chest wall and larynx patients. Increased dose rates of around 800 MU min -1 were recorded for open fields (relative to 320 MU min -1 for filtered open fields) and reduced head scatter was inferred from output factor measurements. Good agreement between planned and delivered dose was observed in verification of treatment plans. The planning study indicated that with a FFF beam, equivalent (and in some cases improved) isodose profiles could be achieved for small lung and larynx treatment volumes relative to 4 MV filtered treatments. Furthermore, FFF treatments with wedges could be replicated using open fields together with an 'effective wedge' technique and isocentre shift. Clinical feasibility of a FFF beam was therefore demonstrated, with beam modelling, treatment planning and verification being successfully accomplished.

  6. Aqueous Extract of Flueggea leucopyrus Increases Urine Output in ...

    African Journals Online (AJOL)

    FLAE) on the urinary output of rats. Method: Three different doses of FLAE (500, 1000 and 1500 mgkg-1), furosemide (13 mg kg-1 as diuretic reference) and distilled water (as control) were orally administered to healthy adult hydrated rats.

  7. Plant fibre composites - porosity and volumetric interaction

    DEFF Research Database (Denmark)

    Madsen, Bo; Thygesen, Anders; Lilholt, Hans

    2007-01-01

    the combination of a high fibre volume fraction, a low porosity and a high composite density is optimal. Experimental data from the literature on volumetric composition and density of four types of plant fibre composites are used to validate the model. It is demonstrated that the model provides a concept......Plant fibre composites contain typically a relative large amount of porosity, which considerably influences properties and performance of the composites. The large porosity must be integrated in the conversion of weight fractions into volume fractions of the fibre and matrix parts. A model...... is presented to predict the porosity as a function of the fibre weight fractions, and to calculate the related fibre and matrix volume fractions, as well as the density of the composite. The model predicts two cases of composite volumetric interaction separated by a transition fibre weight fraction, at which...

  8. Combined surface and volumetric occlusion shading

    KAUST Repository

    Schott, Matthias O.; Martin, Tobias; Grosset, A. V Pascal; Brownlee, Carson; Hollt, Thomas; Brown, Benjamin P.; Smith, Sean T.; Hansen, Charles D.

    2012-01-01

    In this paper, a method for interactive direct volume rendering is proposed that computes ambient occlusion effects for visualizations that combine both volumetric and geometric primitives, specifically tube shaped geometric objects representing streamlines, magnetic field lines or DTI fiber tracts. The proposed algorithm extends the recently proposed Directional Occlusion Shading model to allow the rendering of those geometric shapes in combination with a context providing 3D volume, considering mutual occlusion between structures represented by a volume or geometry. © 2012 IEEE.

  9. Combined surface and volumetric occlusion shading

    KAUST Repository

    Schott, Matthias O.

    2012-02-01

    In this paper, a method for interactive direct volume rendering is proposed that computes ambient occlusion effects for visualizations that combine both volumetric and geometric primitives, specifically tube shaped geometric objects representing streamlines, magnetic field lines or DTI fiber tracts. The proposed algorithm extends the recently proposed Directional Occlusion Shading model to allow the rendering of those geometric shapes in combination with a context providing 3D volume, considering mutual occlusion between structures represented by a volume or geometry. © 2012 IEEE.

  10. Volumetric and superficial characterization of carbon activated

    International Nuclear Information System (INIS)

    Carrera G, L.M.; Garcia S, I.; Jimenez B, J.; Solache R, M.; Lopez M, B.; Bulbulian G, S.; Olguin G, M.T.

    2000-01-01

    The activated carbon is the resultant material of the calcination process of natural carbonated materials as coconut shells or olive little bones. It is an excellent adsorbent of diluted substances, so much in colloidal form, as in particles form. Those substances are attracted and retained by the carbon surface. In this work is make the volumetric and superficial characterization of activated carbon treated thermically (300 Centigrade) in function of the grain size average. (Author)

  11. Volumetric polymerization shrinkage of contemporary composite resins

    OpenAIRE

    Nagem Filho, Halim; Nagem, Haline Drumond; Francisconi, Paulo Afonso Silveira; Franco, Eduardo Batista; Mondelli, Rafael Francisco Lia; Coutinho, Kennedy Queiroz

    2007-01-01

    The polymerization shrinkage of composite resins may affect negatively the clinical outcome of the restoration. Extensive research has been carried out to develop new formulations of composite resins in order to provide good handling characteristics and some dimensional stability during polymerization. The purpose of this study was to analyze, in vitro, the magnitude of the volumetric polymerization shrinkage of 7 contemporary composite resins (Definite, Suprafill, SureFil, Filtek Z250, Fill ...

  12. GPU-based Scalable Volumetric Reconstruction for Multi-view Stereo

    Energy Technology Data Exchange (ETDEWEB)

    Kim, H; Duchaineau, M; Max, N

    2011-09-21

    We present a new scalable volumetric reconstruction algorithm for multi-view stereo using a graphics processing unit (GPU). It is an effectively parallelized GPU algorithm that simultaneously uses a large number of GPU threads, each of which performs voxel carving, in order to integrate depth maps with images from multiple views. Each depth map, triangulated from pair-wise semi-dense correspondences, represents a view-dependent surface of the scene. This algorithm also provides scalability for large-scale scene reconstruction in a high resolution voxel grid by utilizing streaming and parallel computation. The output is a photo-realistic 3D scene model in a volumetric or point-based representation. We demonstrate the effectiveness and the speed of our algorithm with a synthetic scene and real urban/outdoor scenes. Our method can also be integrated with existing multi-view stereo algorithms such as PMVS2 to fill holes or gaps in textureless regions.

  13. A volumetric data system for environmental robotics

    International Nuclear Information System (INIS)

    Tourtellott, J.

    1994-01-01

    A three-dimensional, spatially organized or volumetric data system provides an effective means for integrating and presenting environmental sensor data to robotic systems and operators. Because of the unstructed nature of environmental restoration applications, new robotic control strategies are being developed that include environmental sensors and interactive data interpretation. The volumetric data system provides key features to facilitate these new control strategies including: integrated representation of surface, subsurface and above-surface data; differentiation of mapped and unmapped regions in space; sculpting of regions in space to best exploit data from line-of-sight sensors; integration of diverse sensor data (for example, dimensional, physical/geophysical, chemical, and radiological); incorporation of data provided at different spatial resolutions; efficient access for high-speed visualization and analysis; and geometric modeling tools to update a open-quotes world modelclose quotes of an environment. The applicability to underground storage tank remediation and buried waste site remediation are demonstrated in several examples. By integrating environmental sensor data into robotic control, the volumetric data system will lead to safer, faster, and more cost-effective environmental cleanup

  14. MR volumetric assessment of endolymphatic hydrops

    International Nuclear Information System (INIS)

    Guerkov, R.; Berman, A.; Jerin, C.; Krause, E.; Dietrich, O.; Flatz, W.; Ertl-Wagner, B.; Keeser, D.

    2015-01-01

    We aimed to volumetrically quantify endolymph and perilymph spaces of the inner ear in order to establish a methodological basis for further investigations into the pathophysiology and therapeutic monitoring of Meniere's disease. Sixteen patients (eight females, aged 38-71 years) with definite unilateral Meniere's disease were included in this study. Magnetic resonance (MR) cisternography with a T2-SPACE sequence was combined with a Real reconstruction inversion recovery (Real-IR) sequence for delineation of inner ear fluid spaces. Machine learning and automated local thresholding segmentation algorithms were applied for three-dimensional (3D) reconstruction and volumetric quantification of endolymphatic hydrops. Test-retest reliability was assessed by the intra-class coefficient; correlation of cochlear endolymph volume ratio with hearing function was assessed by the Pearson correlation coefficient. Endolymph volume ratios could be reliably measured in all patients, with a mean (range) value of 15 % (2-25) for the cochlea and 28 % (12-40) for the vestibulum. Test-retest reliability was excellent, with an intra-class coefficient of 0.99. Cochlear endolymphatic hydrops was significantly correlated with hearing loss (r = 0.747, p = 0.001). MR imaging after local contrast application and image processing, including machine learning and automated local thresholding, enable the volumetric quantification of endolymphatic hydrops. This allows for a quantitative assessment of the effect of therapeutic interventions on endolymphatic hydrops. (orig.)

  15. MR volumetric assessment of endolymphatic hydrops

    Energy Technology Data Exchange (ETDEWEB)

    Guerkov, R.; Berman, A.; Jerin, C.; Krause, E. [University of Munich, Department of Otorhinolaryngology Head and Neck Surgery, Grosshadern Medical Centre, Munich (Germany); University of Munich, German Centre for Vertigo and Balance Disorders, Grosshadern Medical Centre, Marchioninistr. 15, 81377, Munich (Germany); Dietrich, O.; Flatz, W.; Ertl-Wagner, B. [University of Munich, Institute of Clinical Radiology, Grosshadern Medical Centre, Munich (Germany); Keeser, D. [University of Munich, Institute of Clinical Radiology, Grosshadern Medical Centre, Munich (Germany); University of Munich, German Centre for Vertigo and Balance Disorders, Grosshadern Medical Centre, Marchioninistr. 15, 81377, Munich (Germany); University of Munich, Department of Psychiatry and Psychotherapy, Innenstadtkliniken Medical Centre, Munich (Germany)

    2014-10-16

    We aimed to volumetrically quantify endolymph and perilymph spaces of the inner ear in order to establish a methodological basis for further investigations into the pathophysiology and therapeutic monitoring of Meniere's disease. Sixteen patients (eight females, aged 38-71 years) with definite unilateral Meniere's disease were included in this study. Magnetic resonance (MR) cisternography with a T2-SPACE sequence was combined with a Real reconstruction inversion recovery (Real-IR) sequence for delineation of inner ear fluid spaces. Machine learning and automated local thresholding segmentation algorithms were applied for three-dimensional (3D) reconstruction and volumetric quantification of endolymphatic hydrops. Test-retest reliability was assessed by the intra-class coefficient; correlation of cochlear endolymph volume ratio with hearing function was assessed by the Pearson correlation coefficient. Endolymph volume ratios could be reliably measured in all patients, with a mean (range) value of 15 % (2-25) for the cochlea and 28 % (12-40) for the vestibulum. Test-retest reliability was excellent, with an intra-class coefficient of 0.99. Cochlear endolymphatic hydrops was significantly correlated with hearing loss (r = 0.747, p = 0.001). MR imaging after local contrast application and image processing, including machine learning and automated local thresholding, enable the volumetric quantification of endolymphatic hydrops. This allows for a quantitative assessment of the effect of therapeutic interventions on endolymphatic hydrops. (orig.)

  16. Synchronous prostate and rectal adenocarcinomas irradiation utilising volumetric modulated arc therapy

    OpenAIRE

    Ng, Sweet Ping; Tran, Thu; Moloney, Philip; Sale, Charlotte; Mathlum, Maitham; Ong, Grace; Lynch, Rod

    2015-01-01

    Abstract Cases of synchronous prostate and colorectal adenocarcinomas have been sporadically reported. There are case reports on patients with synchronous prostate and rectal cancers treated with external beam radiotherapy alone or combined with high?dose rate brachytherapy boost to the prostate. Here, we illustrate a patient with synchronous prostate and rectal cancers treated using the volumetric arc therapy (VMAT) technique. The patient was treated with radical radiotherapy to 50.4 Gy in 2...

  17. Cardiac output during exercise

    DEFF Research Database (Denmark)

    Siebenmann, C; Rasmussen, P.; Sørensen, H.

    2015-01-01

    Several techniques assessing cardiac output (Q) during exercise are available. The extent to which the measurements obtained from each respective technique compares to one another, however, is unclear. We quantified Q simultaneously using four methods: the Fick method with blood obtained from...... the right atrium (Q(Fick-M)), Innocor (inert gas rebreathing; Q(Inn)), Physioflow (impedance cardiography; Q(Phys)), and Nexfin (pulse contour analysis; Q(Pulse)) in 12 male subjects during incremental cycling exercise to exhaustion in normoxia and hypoxia (FiO2  = 12%). While all four methods reported...... a progressive increase in Q with exercise intensity, the slopes of the Q/oxygen uptake (VO2) relationship differed by up to 50% between methods in both normoxia [4.9 ± 0.3, 3.9 ± 0.2, 6.0 ± 0.4, 4.8 ± 0.2 L/min per L/min (mean ± SE) for Q(Fick-M), Q(Inn), QP hys and Q(Pulse), respectively; P = 0...

  18. Floating Gate CMOS Dosimeter With Frequency Output

    Science.gov (United States)

    Garcia-Moreno, E.; Isern, E.; Roca, M.; Picos, R.; Font, J.; Cesari, J.; Pineda, A.

    2012-04-01

    This paper presents a gamma radiation dosimeter based on a floating gate sensor. The sensor is coupled with a signal processing circuitry, which furnishes a square wave output signal, the frequency of which depends on the total dose. Like any other floating gate dosimeter, it exhibits zero bias operation and reprogramming capabilities. The dosimeter has been designed in a standard 0.6 m CMOS technology. The whole dosimeter occupies a silicon area of 450 m250 m. The initial sensitivity to a radiation dose is Hz/rad, and to temperature and supply voltage is kHz/°C and 0.067 kHz/mV, respectively. The lowest detectable dose is less than 1 rad.

  19. Ultrafast treatment plan optimization for volumetric modulated arc therapy (VMAT).

    Science.gov (United States)

    Men, Chunhua; Romeijn, H Edwin; Jia, Xun; Jiang, Steve B

    2010-11-01

    To develop a novel aperture-based algorithm for volumetric modulated are therapy (VMAT) treatment plan optimization with high quality and high efficiency. The VMAT optimization problem is formulated as a large-scale convex programming problem solved by a column generation approach. The authors consider a cost function consisting two terms, the first enforcing a desired dose distribution and the second guaranteeing a smooth dose rate variation between successive gantry angles. A gantry rotation is discretized into 180 beam angles and for each beam angle, only one MLC aperture is allowed. The apertures are generated one by one in a sequential way. At each iteration of the column generation method, a deliverable MLC aperture is generated for one of the unoccupied beam angles by solving a subproblem with the consideration of MLC mechanic constraints. A subsequent master problem is then solved to determine the dose rate at all currently generated apertures by minimizing the cost function. When all 180 beam angles are occupied, the optimization completes, yielding a set of deliverable apertures and associated dose rates that produce a high quality plan. The algorithm was preliminarily tested on five prostate and five head-and-neck clinical cases, each with one full gantry rotation without any couch/collimator rotations. High quality VMAT plans have been generated for all ten cases with extremely high efficiency. It takes only 5-8 min on CPU (MATLAB code on an Intel Xeon 2.27 GHz CPU) and 18-31 s on GPU (CUDA code on an NVIDIA Tesla C1060 GPU card) to generate such plans. The authors have developed an aperture-based VMAT optimization algorithm which can generate clinically deliverable high quality treatment plans at very high efficiency.

  20. Volumetric polymerization shrinkage of contemporary composite resins

    Directory of Open Access Journals (Sweden)

    Halim Nagem Filho

    2007-10-01

    Full Text Available The polymerization shrinkage of composite resins may affect negatively the clinical outcome of the restoration. Extensive research has been carried out to develop new formulations of composite resins in order to provide good handling characteristics and some dimensional stability during polymerization. The purpose of this study was to analyze, in vitro, the magnitude of the volumetric polymerization shrinkage of 7 contemporary composite resins (Definite, Suprafill, SureFil, Filtek Z250, Fill Magic, Alert, and Solitaire to determine whether there are differences among these materials. The tests were conducted with precision of 0.1 mg. The volumetric shrinkage was measured by hydrostatic weighing before and after polymerization and calculated by known mathematical equations. One-way ANOVA (a or = 0.05 was used to determine statistically significant differences in volumetric shrinkage among the tested composite resins. Suprafill (1.87±0.01 and Definite (1.89±0.01 shrank significantly less than the other composite resins. SureFil (2.01±0.06, Filtek Z250 (1.99±0.03, and Fill Magic (2.02±0.02 presented intermediate levels of polymerization shrinkage. Alert and Solitaire presented the highest degree of polymerization shrinkage. Knowing the polymerization shrinkage rates of the commercially available composite resins, the dentist would be able to choose between using composite resins with lower polymerization shrinkage rates or adopting technical or operational procedures to minimize the adverse effects deriving from resin contraction during light-activation.

  1. Inverter communications using output signal

    Science.gov (United States)

    Chapman, Patrick L.

    2017-02-07

    Technologies for communicating information from an inverter configured for the conversion of direct current (DC) power generated from an alternative source to alternating current (AC) power are disclosed. The technologies include determining information to be transmitted from the inverter over a power line cable connected to the inverter and controlling the operation of an output converter of the inverter as a function of the information to be transmitted to cause the output converter to generate an output waveform having the information modulated thereon.

  2. Volumetric expiratory high-resolution CT of the lung

    International Nuclear Information System (INIS)

    Nishino, Mizuki; Hatabu, Hiroto

    2004-01-01

    We developed a volumetric expiratory high-resolution CT (HRCT) protocol that provides combined inspiratory and expiratory volumetric imaging of the lung without increasing radiation exposure, and conducted a preliminary feasibility assessment of this protocol to evaluate diffuse lung disease with small airway abnormalities. The volumetric expiratory high-resolution CT increased the detectability of the conducting airway to the areas of air trapping (P<0.0001), and added significant information about extent and distribution of air trapping (P<0.0001)

  3. Gamma-index method sensitivity for gauging plan delivery accuracy of volumetric modulated arc therapy.

    Science.gov (United States)

    Park, Jong In; Park, Jong Min; Kim, Jung-In; Park, So-Yeon; Ye, Sung-Joon

    2015-12-01

    The aim of this study was to investigate the sensitivity of the gamma-index method according to various gamma criteria for volumetric modulated arc therapy (VMAT). Twenty head and neck (HN) and twenty prostate VMAT plans were retrospectively selected for this study. Both global and local 2D gamma evaluations were performed with criteria of 3%/3 mm, 2%/2 mm, 1%/2 mm and 2%/1 mm. In this study, the global and local gamma-index calculated the differences in doses relative to the maximum dose and the dose at the current measurement point, respectively. Using log files acquired during delivery, the differences in parameters at every control point between the VMAT plans and the log files were acquired. The differences in dose-volumetric parameters between reconstructed VMAT plans using the log files and the original VMAT plans were calculated. The Spearman's rank correlation coefficients (rs) were calculated between the passing rates and those differences. Considerable correlations with statistical significances were observed between global 1%/2 mm, local 1%/2 mm and local 2%/1 mm and the MLC position differences (rs = -0.712, -0.628 and -0.581). The numbers of rs values with statistical significance between the passing rates and the changes in dose-volumetric parameters were largest in global 2%/2 mm (n = 16), global 2%/1 mm (n = 15) and local 2%/1 mm (n = 13) criteria. Local gamma-index method with 2%/1 mm generally showed higher sensitivity to detect deviations between a VMAT plan and the delivery of the VMAT plan. Copyright © 2015 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

  4. Adaptive controller for volumetric display of neuroimaging studies

    Science.gov (United States)

    Bleiberg, Ben; Senseney, Justin; Caban, Jesus

    2014-03-01

    Volumetric display of medical images is an increasingly relevant method for examining an imaging acquisition as the prevalence of thin-slice imaging increases in clinical studies. Current mouse and keyboard implementations for volumetric control provide neither the sensitivity nor specificity required to manipulate a volumetric display for efficient reading in a clinical setting. Solutions to efficient volumetric manipulation provide more sensitivity by removing the binary nature of actions controlled by keyboard clicks, but specificity is lost because a single action may change display in several directions. When specificity is then further addressed by re-implementing hardware binary functions through the introduction of mode control, the result is a cumbersome interface that fails to achieve the revolutionary benefit required for adoption of a new technology. We address the specificity versus sensitivity problem of volumetric interfaces by providing adaptive positional awareness to the volumetric control device by manipulating communication between hardware driver and existing software methods for volumetric display of medical images. This creates a tethered effect for volumetric display, providing a smooth interface that improves on existing hardware approaches to volumetric scene manipulation.

  5. Low-cost Volumetric Ultrasound by Augmentation of 2D Systems: Design and Prototype.

    Science.gov (United States)

    Herickhoff, Carl D; Morgan, Matthew R; Broder, Joshua S; Dahl, Jeremy J

    2018-01-01

    Conventional two-dimensional (2D) ultrasound imaging is a powerful diagnostic tool in the hands of an experienced user, yet 2D ultrasound remains clinically underutilized and inherently incomplete, with output being very operator dependent. Volumetric ultrasound systems can more fully capture a three-dimensional (3D) region of interest, but current 3D systems require specialized transducers, are prohibitively expensive for many clinical departments, and do not register image orientation with respect to the patient; these systems are designed to provide improved workflow rather than operator independence. This work investigates whether it is possible to add volumetric 3D imaging capability to existing 2D ultrasound systems at minimal cost, providing a practical means of reducing operator dependence in ultrasound. In this paper, we present a low-cost method to make 2D ultrasound systems capable of quality volumetric image acquisition: we present the general system design and image acquisition method, including the use of a probe-mounted orientation sensor, a simple probe fixture prototype, and an offline volume reconstruction technique. We demonstrate initial results of the method, implemented using a Verasonics Vantage research scanner.

  6. Volumetric modulated arc therapy: IMRT in a single gantry arc

    International Nuclear Information System (INIS)

    Otto, Karl

    2008-01-01

    In this work a novel plan optimization platform is presented where treatment is delivered efficiently and accurately in a single dynamically modulated arc. Improvements in patient care achieved through image-guided positioning and plan adaptation have resulted in an increase in overall treatment times. Intensity-modulated radiation therapy (IMRT) has also increased treatment time by requiring a larger number of beam directions, increased monitor units (MU), and, in the case of tomotherapy, a slice-by-slice delivery. In order to maintain a similar level of patient throughput it will be necessary to increase the efficiency of treatment delivery. The solution proposed here is a novel aperture-based algorithm for treatment plan optimization where dose is delivered during a single gantry arc of up to 360 deg. The technique is similar to tomotherapy in that a full 360 deg. of beam directions are available for optimization but is fundamentally different in that the entire dose volume is delivered in a single source rotation. The new technique is referred to as volumetric modulated arc therapy (VMAT). Multileaf collimator (MLC) leaf motion and number of MU per degree of gantry rotation is restricted during the optimization so that gantry rotation speed, leaf translation speed, and dose rate maxima do not excessively limit the delivery efficiency. During planning, investigators model continuous gantry motion by a coarse sampling of static gantry positions and fluence maps or MLC aperture shapes. The technique presented here is unique in that gantry and MLC position sampling is progressively increased throughout the optimization. Using the full gantry range will theoretically provide increased flexibility in generating highly conformal treatment plans. In practice, the additional flexibility is somewhat negated by the additional constraints placed on the amount of MLC leaf motion between gantry samples. A series of studies are performed that characterize the relationship

  7. Automatic interactive optimization for volumetric modulated arc therapy planning

    International Nuclear Information System (INIS)

    Tol, Jim P; Dahele, Max; Peltola, Jarkko; Nord, Janne; Slotman, Ben J; Verbakel, Wilko FAR

    2015-01-01

    Intensity modulated radiotherapy treatment planning for sites with many different organs-at-risk (OAR) is complex and labor-intensive, making it hard to obtain consistent plan quality. With the aim of addressing this, we developed a program (automatic interactive optimizer, AIO) designed to automate the manual interactive process for the Eclipse treatment planning system. We describe AIO and present initial evaluation data. Our current institutional volumetric modulated arc therapy (RapidArc) planning approach for head and neck tumors places 3-4 adjustable OAR optimization objectives along the dose-volume histogram (DVH) curve that is displayed in the optimization window. AIO scans this window and uses color-coding to differentiate between the DVH-lines, allowing it to automatically adjust the location of the optimization objectives frequently and in a more consistent fashion. We compared RapidArc AIO plans (using 9 optimization objectives per OAR) with the clinical plans of 10 patients, and evaluated optimal AIO settings. AIO consistency was tested by replanning a single patient 5 times. Average V95&V107 of the boost planning target volume (PTV) and V95 of the elective PTV differed by ≤0.5%, while average elective PTV V107 improved by 1.5%. Averaged over all patients, AIO reduced mean doses to individual salivary structures by 0.9-1.6Gy and provided mean dose reductions of 5.6Gy and 3.9Gy to the composite swallowing structures and oral cavity, respectively. Re-running AIO five times, resulted in the aforementioned parameters differing by less than 3%. Using the same planning strategy as manually optimized head and neck plans, AIO can automate the interactive Eclipse treatment planning process and deliver dosimetric improvements over existing clinical plans

  8. Linac-based total body irradiation (TBI) with volumetric modulated arc therapy (VMAT)

    Science.gov (United States)

    Tas, B.; Durmus, I. F.; Okumus, A.; Uzel, O. E.

    2017-02-01

    To evaluate dose distribution of Volumetric modulated arc therapy (VMAT) planning tecnique using Versa HD® lineer accelerator to deliver Total Body Irradiation (TBI) on the coach. Eight TBI patient's Treatment Planning System (TPS) were performed with dual arc VMAT for each patient. The VMAT-TBI consisted of three isocentres and three dual overlapping arcs. The prescribed dose was 12 Gy. Mean dose to lung and kidney were restricted less than 10 Gy and max. dose to lens were restricted less than 6 Gy. The plans were verified using 2D array and ion chamber. The comparison between calculation and measurement were made by γ-index analysis and absolute dose. An average total delivery time was determined 923±34 seconds and an average MU was determined 2614±228 MUs for dual arc VMAT. Mean dose to lungs was 9.7±0.2 Gy, mean dose to kidneys was 8.8±0.3 Gy, max. dose to lens was 5.5±0.3 Gy and max. dose was 14.6±0.3 Gy, HI of PTV was 1.13±0.2, mean dose to PTV was 12.6±1.5 Gy and mean γ-index pass rate was %97.1±1.9. The results show that the tecnique for TBI using VMAT on the treatment coach is feasible.

  9. Enhanced performance CCD output amplifier

    Science.gov (United States)

    Dunham, Mark E.; Morley, David W.

    1996-01-01

    A low-noise FET amplifier is connected to amplify output charge from a che coupled device (CCD). The FET has its gate connected to the CCD in common source configuration for receiving the output charge signal from the CCD and output an intermediate signal at a drain of the FET. An intermediate amplifier is connected to the drain of the FET for receiving the intermediate signal and outputting a low-noise signal functionally related to the output charge signal from the CCD. The amplifier is preferably connected as a virtual ground to the FET drain. The inherent shunt capacitance of the FET is selected to be at least equal to the sum of the remaining capacitances.

  10. Volumetric visualization of anatomy for treatment planning

    International Nuclear Information System (INIS)

    Pelizzari, Charles A.; Grzeszczuk, Robert; Chen, George T. Y.; Heimann, Ruth; Haraf, Daniel J.; Vijayakumar, Srinivasan; Ryan, Martin J.

    1996-01-01

    Purpose: Delineation of volumes of interest for three-dimensional (3D) treatment planning is usually performed by contouring on two-dimensional sections. We explore the usage of segmentation-free volumetric rendering of the three-dimensional image data set for tumor and normal tissue visualization. Methods and Materials: Standard treatment planning computed tomography (CT) studies, with typically 5 to 10 mm slice thickness, and spiral CT studies with 3 mm slice thickness were used. The data were visualized using locally developed volume-rendering software. Similar to the method of Drebin et al., CT voxels are automatically assigned an opacity and other visual properties (e.g., color) based on a probabilistic classification into tissue types. Using volumetric compositing, a projection into the opacity-weighted volume is produced. Depth cueing, perspective, and gradient-based shading are incorporated to achieve realistic images. Unlike surface-rendered displays, no hand segmentation is required to produce detailed renditions of skin, muscle, or bony anatomy. By suitable manipulation of the opacity map, tissue classes can be made transparent, revealing muscle, vessels, or bone, for example. Manually supervised tissue masking allows irrelevant tissues overlying tumors or other structures of interest to be removed. Results: Very high-quality renditions are produced in from 5 s to 1 min on midrange computer workstations. In the pelvis, an anteroposterior (AP) volume rendered view from a typical planning CT scan clearly shows the skin and bony anatomy. A muscle opacity map permits clear visualization of the superficial thigh muscles, femoral veins, and arteries. Lymph nodes are seen in the femoral triangle. When overlying muscle and bone are cut away, the prostate, seminal vessels, bladder, and rectum are seen in 3D perspective. Similar results are obtained for thorax and for head and neck scans. Conclusion: Volumetric visualization of anatomy is useful in treatment

  11. Choreographing Couch and Collimator in Volumetric Modulated Arc Therapy

    International Nuclear Information System (INIS)

    Yang Yingli; Zhang Pengpeng; Happersett, Laura; Xiong Jianping; Yang Jie; Chan, Maria; Beal, Kathryn; Mageras, Gig; Hunt, Margie

    2011-01-01

    Purpose: To design and optimize trajectory-based, noncoplanar subarcs for volumetric modulated arc therapy (VMAT) deliverable on both Varian TrueBEAM system and traditional accelerators; and to investigate their potential advantages for treating central nervous system (CNS) tumors. Methods and Materials: To guide the computerized selection of beam trajectories consisting of simultaneous couch, gantry, and collimator motion, a score function was implemented to estimate the geometric overlap between targets and organs at risk for each couch/gantry angle combination. An initial set of beam orientations is obtained as a function of couch and gantry angle, according to a minimum search of the score function excluding zones of collision. This set is grouped into multiple continuous and extended subarcs subject to mechanical limitations using a hierarchical clustering algorithm. After determination of couch/gantry trajectories, a principal component analysis finds the collimator angle at each beam orientation that minimizes residual target-organ at risk overlaps. An in-house VMAT optimization algorithm determines the optimal multileaf collimator position and monitor units for control points within each subarc. A retrospective study of 10 CNS patients compares the proposed method of VMAT trajectory with dynamic gantry, leaves, couch, and collimator motion (Tra-VMAT); a standard noncoplanar VMAT with no couch/collimator motion within subarcs (Std-VMAT); and noncoplanar intensity-modulated radiotherapy (IMRT) plans that were clinically used. Results: Tra-VMAT provided improved target dose conformality and lowered maximum dose to brainstem, optic nerves, and chiasm by 7.7%, 1.1%, 2.3%, and 1.7%, respectively, compared with Std-VMAT. Tra-VMAT provided higher planning target volume minimum dose and reduced maximum dose to chiasm, optic nerves, and cochlea by 6.2%, 1.3%, 6.3%, and 8.4%, respectively, and reduced cochlea mean dose by 8.7%, compared with IMRT. Tra-VMAT averaged

  12. GDP Growth, Potential Output, and Output Gaps in Mexico

    OpenAIRE

    Ebrima A Faal

    2005-01-01

    This paper analyzes the sources of Mexico's economic growth since the 1960s and compares various decompositions of historical growth into its trend and cyclical components. The role of the implied output gaps in the inflationary process is then assessed. Looking ahead, the paper presents medium-term paths for GDP based on alternative assumptions for productivity growth rates. The results indicate that the most important factor underlying the slowdown in output growth was a decline in trend to...

  13. A comprehensive formulation for volumetric modulated arc therapy planning

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, Dan; Lyu, Qihui; Ruan, Dan; O’Connor, Daniel; Low, Daniel A.; Sheng, Ke, E-mail: ksheng@mednet.ucla.edu [Department of Radiation Oncology, University of California Los Angeles, Los Angeles, California 90024 (United States)

    2016-07-15

    Purpose: Volumetric modulated arc therapy (VMAT) is a widely employed radiation therapy technique, showing comparable dosimetry to static beam intensity modulated radiation therapy (IMRT) with reduced monitor units and treatment time. However, the current VMAT optimization has various greedy heuristics employed for an empirical solution, which jeopardizes plan consistency and quality. The authors introduce a novel direct aperture optimization method for VMAT to overcome these limitations. Methods: The comprehensive VMAT (comVMAT) planning was formulated as an optimization problem with an L2-norm fidelity term to penalize the difference between the optimized dose and the prescribed dose, as well as an anisotropic total variation term to promote piecewise continuity in the fluence maps, preparing it for direct aperture optimization. A level set function was used to describe the aperture shapes and the difference between aperture shapes at adjacent angles was penalized to control MLC motion range. A proximal-class optimization solver was adopted to solve the large scale optimization problem, and an alternating optimization strategy was implemented to solve the fluence intensity and aperture shapes simultaneously. Single arc comVMAT plans, utilizing 180 beams with 2° angular resolution, were generated for a glioblastoma multiforme case, a lung (LNG) case, and two head and neck cases—one with three PTVs (H&N{sub 3PTV}) and one with foue PTVs (H&N{sub 4PTV})—to test the efficacy. The plans were optimized using an alternating optimization strategy. The plans were compared against the clinical VMAT (clnVMAT) plans utilizing two overlapping coplanar arcs for treatment. Results: The optimization of the comVMAT plans had converged within 600 iterations of the block minimization algorithm. comVMAT plans were able to consistently reduce the dose to all organs-at-risk (OARs) as compared to the clnVMAT plans. On average, comVMAT plans reduced the max and mean OAR dose by 6

  14. Determination of Uncertainty for a One Milli Litre Volumetric Pipette

    International Nuclear Information System (INIS)

    Torowati; Asminar; Rahmiati; Arif-Sasongko-Adi

    2007-01-01

    An observation had been conducted to determine the uncertainty of volumetric pipette. The uncertainty was determined from data obtained from a determine process which used method of gravimetry. Calculation result from an uncertainty of volumetric pipette the confidence level of 95% and k=2. (author)

  15. Volumetric accuracy of cone-beam computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Park, Cheol Woo; Kim, Jin Ho; Seo, Yu Kyeong; Lee, Sae Rom; Kang, Ju Hee; Oh, Song Hee; Kim, Gyu Tae; Choi, Yong Suk; Hwang, Eui Hwan [Dept. of Oral and Maxillofacial Radiology, Graduate School, Kyung Hee University, Seoul (Korea, Republic of)

    2017-09-15

    This study was performed to investigate the influence of object shape and distance from the center of the image on the volumetric accuracy of cone-beam computed tomography (CBCT) scans, according to different parameters of tube voltage and current. Four geometric objects (cylinder, cube, pyramid, and hexagon) with predefined dimensions were fabricated. The objects consisted of Teflon-perfluoroalkoxy embedded in a hydrocolloid matrix (Dupli-Coe-Loid TM; GC America Inc., Alsip, IL, USA), encased in an acrylic resin cylinder assembly. An Alphard Vega Dental CT system (Asahi Roentgen Ind. Co., Ltd, Kyoto, Japan) was used to acquire CBCT images. OnDemand 3D (CyberMed Inc., Seoul, Korea) software was used for object segmentation and image analysis. The accuracy was expressed by the volume error (VE). The VE was calculated under 3 different exposure settings. The measured volumes of the objects were compared to the true volumes for statistical analysis. The mean VE ranged from −4.47% to 2.35%. There was no significant relationship between an object's shape and the VE. A significant correlation was found between the distance of the object to the center of the image and the VE. Tube voltage affected the volume measurements and the VE, but tube current did not. The evaluated CBCT device provided satisfactory volume measurements. To assess volume measurements, it might be sufficient to use serial scans with a high resolution, but a low dose. This information may provide useful guidance for assessing volume measurements.

  16. Volumetric accuracy of cone-beam computed tomography

    International Nuclear Information System (INIS)

    Park, Cheol Woo; Kim, Jin Ho; Seo, Yu Kyeong; Lee, Sae Rom; Kang, Ju Hee; Oh, Song Hee; Kim, Gyu Tae; Choi, Yong Suk; Hwang, Eui Hwan

    2017-01-01

    This study was performed to investigate the influence of object shape and distance from the center of the image on the volumetric accuracy of cone-beam computed tomography (CBCT) scans, according to different parameters of tube voltage and current. Four geometric objects (cylinder, cube, pyramid, and hexagon) with predefined dimensions were fabricated. The objects consisted of Teflon-perfluoroalkoxy embedded in a hydrocolloid matrix (Dupli-Coe-Loid TM; GC America Inc., Alsip, IL, USA), encased in an acrylic resin cylinder assembly. An Alphard Vega Dental CT system (Asahi Roentgen Ind. Co., Ltd, Kyoto, Japan) was used to acquire CBCT images. OnDemand 3D (CyberMed Inc., Seoul, Korea) software was used for object segmentation and image analysis. The accuracy was expressed by the volume error (VE). The VE was calculated under 3 different exposure settings. The measured volumes of the objects were compared to the true volumes for statistical analysis. The mean VE ranged from −4.47% to 2.35%. There was no significant relationship between an object's shape and the VE. A significant correlation was found between the distance of the object to the center of the image and the VE. Tube voltage affected the volume measurements and the VE, but tube current did not. The evaluated CBCT device provided satisfactory volume measurements. To assess volume measurements, it might be sufficient to use serial scans with a high resolution, but a low dose. This information may provide useful guidance for assessing volume measurements

  17. 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

  18. Output

    DEFF Research Database (Denmark)

    Mehlsen, Camilla

    2010-01-01

    Hvad får vi egentlig ud af internationale komparative undersøgelser som PISA, PIRLS og TIMSS? Hvordan påvirker de dansk uddannelsespolitik? Asterisk har talt med tre forskere med ekspertise på området.......Hvad får vi egentlig ud af internationale komparative undersøgelser som PISA, PIRLS og TIMSS? Hvordan påvirker de dansk uddannelsespolitik? Asterisk har talt med tre forskere med ekspertise på området....

  19. Role of intracanalicular volumetric and dosimetric parameters on hearing preservation after vestibular schwannoma radiosurgery

    International Nuclear Information System (INIS)

    Massager, Nicolas; Nissim, Ouzi; Delbrouck, Carine; Devriendt, Daniel; David, Philippe; Desmedt, Francoise; Wikler, David; Hassid, Sergio; Brotchi, Jacques; Levivier, Marc

    2006-01-01

    Purpose: To analyze the relationship between hearing preservation after gamma knife radiosurgery (GKR) for vestibular schwannoma (VS) and some volumetric and dosimetric parameters of the intracanalicular components of VS. Methods and Materials: This study included 82 patients with a VS treated by GKR; all patients had no NF2 disease, a Gardner-Robertson hearing class 1-4 before treatment, a marginal dose of 12 Gy, and a radiologic and audiologic follow-up ≥1 year post-GKR. The volume of both the entire tumor and the intracanalicular part of the tumor and the mean and integrated dose of these two volumes were correlated to the auditory outcomes of patients. Results: At last hearing follow-up, 52 patients had no hearing worsening, and 30 patients had an increase of ≥1 class on Gardner-Robertson classification. We found that hearing preservation after GKR is significantly correlated with the intracanalicular tumor volume, as well as with the integrated dose delivered to the intracanalicular tumor volume. Conclusions: Some volumetric and dosimetric parameters of the intracanalicular part of the tumor influence hearing preservation after GKR of VS. Consequently, we advise the direct treatment of patients with preserved functional hearing and a VS including a small intracanalicular volume

  20. Dedicated mobile volumetric cone-beam computed tomography for human brain imaging: A phantom study.

    Science.gov (United States)

    Ryu, Jong-Hyun; Kim, Tae-Hoon; Jeong, Chang-Won; Jun, Hong-Young; Heo, Dong-Woon; Lee, Jinseok; Kim, Kyong-Woo; Yoon, Kwon-Ha

    2015-01-01

    Mobile computed tomography (CT) with a cone-beam source is increasingly used in the clinical field. Mobile cone-beam CT (CBCT) has great merits; however, its clinical utility for brain imaging has been limited due to problems including scan time and image quality. The aim of this study was to develop a dedicated mobile volumetric CBCT for obtaining brain images, and to optimize the imaging protocol using a brain phantom. The mobile volumetric CBCT system was evaluated with regards to scan time and image quality, measured as signal-to-noise-ratio (SNR), contrast-to-noise-ratio (CNR), spatial resolution (10% MTF), and effective dose. Brain images were obtained using a CT phantom. The CT scan took 5.14 s at 360 projection views. SNR and CNR were 5.67 and 14.5 at 120 kV/10 mA. SNR and CNR values showed slight improvement as the x-ray voltage and current increased (p < 0.001). Effective dose and 10% MTF were 0.92 mSv and 360 μ m at 120 kV/10 mA. Various intracranial structures were clearly visible in the brain phantom images. Using this CBCT under optimal imaging acquisition conditions, it is possible to obtain human brain images with low radiation dose, reproducible image quality, and fast scan time.

  1. Volumetric image-guidance: Does routine usage prompt adaptive re-planning? An institutional review

    International Nuclear Information System (INIS)

    Tanyi, James A.; Fuss, Martin H.

    2008-01-01

    Purpose. To investigate how the use of volumetric image-guidance using an on-board cone-beam computed tomography (CBCT) system impacts on the frequency of adaptive re-planning. Material and methods. Treatment courses of 146 patients who have undergone a course of external beam radiation therapy (EBRT) using volumetric CBCT image-guidance were analyzed. Target locations included the brain, head and neck, chest, abdomen, as well as prostate and non-prostate pelvis. The majority of patients (57.5%) were treated with hypo-fractionated treatment regimens (three to 15 fraction courses). The frequency of image-guidance ranged from daily (87.7%) to weekly or twice weekly. The underlying medical necessity for adaptive re-planning as well as frequency and consequences of plan adaptation to dose-volume parameters was assessed. Results. Radiation plans of 34 patients (23.3%) were adapted at least once (up to six time) during their course of EBRT as a result of image-guidance CBCT review. Most common causes for adaptive planning were: tumor change (mostly shrinkage: 10 patients; four patients more than one re-plan), change in abdominal girth (systematic change in hollow organ filling; n=7, two patients more than one re-plan), weight loss (n=5), and systematic target setup deviation from simulation (n=5). Adaptive re-plan was required mostly for conventionally fractionated courses; only 5 patient plans undergoing hypo-fractionated treatment were adjusted. In over 91% of adapted plans, the dose-volume parameters did deviate from the prescribed plan parameters by more than 5% for at least 10% of the target volume, or organs-at-risk in close proximity to the target volume. Discussion. Routine use of volumetric image-guidance has in our practice increased the demand for adaptive re-planning. Volumetric CBCT image-guidance provides sufficient imaging information to reliably predict the need for dose adjustment. In the vast majority of cases evaluated, the initial and adapted dose

  2. Soil volumetric water content measurements using TDR technique

    Directory of Open Access Journals (Sweden)

    S. Vincenzi

    1996-06-01

    Full Text Available A physical model to measure some hydrological and thermal parameters in soils will to be set up. The vertical profiles of: volumetric water content, matric potential and temperature will be monitored in different soils. The volumetric soil water content is measured by means of the Time Domain Reflectometry (TDR technique. The result of a test to determine experimentally the reproducibility of the volumetric water content measurements is reported together with the methodology and the results of the analysis of the TDR wave forms. The analysis is based on the calculation of the travel time of the TDR signal in the wave guide embedded in the soil.

  3. Paediatric dose display

    International Nuclear Information System (INIS)

    Griffin, D.W.; Derges, S.; Hesslewood, S.

    1984-01-01

    A compact, inexpensive unit, based on an 8085 microprocessor, has been designed for calculating doses of intravenous radioactive injections for children. It has been used successfully for over a year. The dose is calculated from the body surface area and the result displayed in MBq. The operator can obtain the required dose on a twelve character alphanumeric display by entering the age of the patient and the adult dose using a hexadecimal keyboard. Circuit description, memory map and input/output, and firmware are dealt with. (U.K.)

  4. Redesign lifts prep output 288%

    Energy Technology Data Exchange (ETDEWEB)

    Hamric, J

    1987-02-01

    This paper outlines the application of engineering creativity and how it brought output at an Ohio coal preparation plant up from 12,500 tpd to nearly four times that figure, 48,610 tpd. By streamlining the conveyor systems, removing surplus belt length and repositioning subplants the whole operation was able to run far more efficiently with a greater output. Various other alterations including the raw material supply and management and operating practices were also undertaken to provide a test for the achievements possible with such reorganization. The new developments have been in the following fields: fine coal cleaning, heavy media cyclones, feeders, bins, filter presses, dewatering equipment and settling tanks. Output is now limited only by the reduced demand by the Gavin power station nearby.

  5. Region-of-interest volumetric visual hull refinement

    KAUST Repository

    Knoblauch, Daniel; Kuester, Falko

    2010-01-01

    This paper introduces a region-of-interest visual hull refinement technique, based on flexible voxel grids for volumetric visual hull reconstructions. Region-of-interest refinement is based on a multipass process, beginning with a focussed visual

  6. Non-uniform volumetric structures in Richtmyer-Meshkov flows

    NARCIS (Netherlands)

    Staniç, M.; McFarland, J.; Stellingwerf, R.F.; Cassibry, J.T.; Ranjan, D.; Bonazza, R.; Greenough, J.A.; Abarzhi, S.I.

    2013-01-01

    We perform an integrated study of volumetric structures in Richtmyer-Meshkov (RM) flows induced by moderate shocks. Experiments, theoretical analyses, Smoothed Particle Hydrodynamics simulations, and ARES Arbitrary Lagrange Eulerian simulations are employed to analyze RM evolution for fluids with

  7. Characterizing volumetric deformation behavior of naturally occuring bituminous sand materials

    CSIR Research Space (South Africa)

    Anochie-Boateng, Joseph

    2009-05-01

    Full Text Available newly proposed hydrostatic compression test procedure. The test procedure applies field loading conditions of off-road construction and mining equipment to closely simulate the volumetric deformation and stiffness behaviour of oil sand materials. Based...

  8. World Input-Output Network.

    Directory of Open Access Journals (Sweden)

    Federica Cerina

    Full Text Available Production systems, traditionally analyzed as almost independent national systems, are increasingly connected on a global scale. Only recently becoming available, the World Input-Output Database (WIOD is one of the first efforts to construct the global multi-regional input-output (GMRIO tables. By viewing the world input-output system as an interdependent network where the nodes are the individual industries in different economies and the edges are the monetary goods flows between industries, we analyze respectively the global, regional, and local network properties of the so-called world input-output network (WION and document its evolution over time. At global level, we find that the industries are highly but asymmetrically connected, which implies that micro shocks can lead to macro fluctuations. At regional level, we find that the world production is still operated nationally or at most regionally as the communities detected are either individual economies or geographically well defined regions. Finally, at local level, for each industry we compare the network-based measures with the traditional methods of backward linkages. We find that the network-based measures such as PageRank centrality and community coreness measure can give valuable insights into identifying the key industries.

  9. Remote input/output station

    CERN Multimedia

    1972-01-01

    A general view of the remote input/output station installed in building 112 (ISR) and used for submitting jobs to the CDC 6500 and 6600. The card reader on the left and the line printer on the right are operated by programmers on a self-service basis.

  10. Compact Circuit Preprocesses Accelerometer Output

    Science.gov (United States)

    Bozeman, Richard J., Jr.

    1993-01-01

    Compact electronic circuit transfers dc power to, and preprocesses ac output of, accelerometer and associated preamplifier. Incorporated into accelerometer case during initial fabrication or retrofit onto commercial accelerometer. Made of commercial integrated circuits and other conventional components; made smaller by use of micrologic and surface-mount technology.

  11. Volumetric optoacoustic monitoring of endovenous laser treatments

    Science.gov (United States)

    Fehm, Thomas F.; Deán-Ben, Xosé L.; Schaur, Peter; Sroka, Ronald; Razansky, Daniel

    2016-03-01

    Chronic venous insufficiency (CVI) is one of the most common medical conditions with reported prevalence estimates as high as 30% in the adult population. Although conservative management with compression therapy may improve the symptoms associated with CVI, healing often demands invasive procedures. Besides established surgical methods like vein stripping or bypassing, endovenous laser therapy (ELT) emerged as a promising novel treatment option during the last 15 years offering multiple advantages such as less pain and faster recovery. Much of the treatment success hereby depends on monitoring of the treatment progression using clinical imaging modalities such as Doppler ultrasound. The latter however do not provide sufficient contrast, spatial resolution and three-dimensional imaging capacity which is necessary for accurate online lesion assessment during treatment. As a consequence, incidence of recanalization, lack of vessel occlusion and collateral damage remains highly variable among patients. In this study, we examined the capacity of volumetric optoacoustic tomography (VOT) for real-time monitoring of ELT using an ex-vivo ox foot model. ELT was performed on subcutaneous veins while optoacoustic signals were acquired and reconstructed in real-time and at a spatial resolution in the order of 200μm. VOT images showed spatio-temporal maps of the lesion progression, characteristics of the vessel wall, and position of the ablation fiber's tip during the pull back. It was also possible to correlate the images with the temperature elevation measured in the area adjacent to the ablation spot. We conclude that VOT is a promising tool for providing online feedback during endovenous laser therapy.

  12. Serial volumetric registration of pulmonary CT studies

    Science.gov (United States)

    Silva, José Silvestre; Silva, Augusto; Sousa Santos, Beatriz

    2008-03-01

    Detailed morphological analysis of pulmonary structures and tissue, provided by modern CT scanners, is of utmost importance as in the case of oncological applications both for diagnosis, treatment, and follow-up. In this case, a patient may go through several tomographic studies throughout a period of time originating volumetric sets of image data that must be appropriately registered in order to track suspicious radiological findings. The structures or regions of interest may change their position or shape in CT exams acquired at different moments, due to postural, physiologic or pathologic changes, so, the exams should be registered before any follow-up information can be extracted. Postural mismatching throughout time is practically impossible to avoid being particularly evident when imaging is performed at the limiting spatial resolution. In this paper, we propose a method for intra-patient registration of pulmonary CT studies, to assist in the management of the oncological pathology. Our method takes advantage of prior segmentation work. In the first step, the pulmonary segmentation is performed where trachea and main bronchi are identified. Then, the registration method proceeds with a longitudinal alignment based on morphological features of the lungs, such as the position of the carina, the pulmonary areas, the centers of mass and the pulmonary trans-axial principal axis. The final step corresponds to the trans-axial registration of the corresponding pulmonary masked regions. This is accomplished by a pairwise sectional registration process driven by an iterative search of the affine transformation parameters leading to optimal similarity metrics. Results with several cases of intra-patient, intra-modality registration, up to 7 time points, show that this method provides accurate registration which is needed for quantitative tracking of lesions and the development of image fusion strategies that may effectively assist the follow-up process.

  13. Volumetric breast density affects performance of digital screening mammography

    OpenAIRE

    Wanders, JO; Holland, K; Veldhuis, WB; Mann, RM; Pijnappel, RM; Peeters, PH; Van Gils, CH; Karssemeijer, N

    2016-01-01

    PURPOSE: To determine to what extent automatically measured volumetric mammographic density influences screening performance when using digital mammography (DM). METHODS: We collected a consecutive series of 111,898 DM examinations (2003-2011) from one screening unit of the Dutch biennial screening program (age 50-75 years). Volumetric mammographic density was automatically assessed using Volpara. We determined screening performance measures for four density categories comparable to the Ameri...

  14. Increasing the volumetric efficiency of Diesel engines by intake pipes

    Science.gov (United States)

    List, Hans

    1933-01-01

    Development of a method for calculating the volumetric efficiency of piston engines with intake pipes. Application of this method to the scavenging pumps of two-stroke-cycle engines with crankcase scavenging and to four-stroke-cycle engines. The utility of the method is demonstrated by volumetric-efficiency tests of the two-stroke-cycle engines with crankcase scavenging. Its practical application to the calculation of intake pipes is illustrated by example.

  15. Soft bilateral filtering volumetric shadows using cube shadow maps.

    Directory of Open Access Journals (Sweden)

    Hatam H Ali

    Full Text Available Volumetric shadows often increase the realism of rendered scenes in computer graphics. Typical volumetric shadows techniques do not provide a smooth transition effect in real-time with conservation on crispness of boundaries. This research presents a new technique for generating high quality volumetric shadows by sampling and interpolation. Contrary to conventional ray marching method, which requires extensive time, this proposed technique adopts downsampling in calculating ray marching. Furthermore, light scattering is computed in High Dynamic Range buffer to generate tone mapping. The bilateral interpolation is used along a view rays to smooth transition of volumetric shadows with respect to preserving-edges. In addition, this technique applied a cube shadow map to create multiple shadows. The contribution of this technique isreducing the number of sample points in evaluating light scattering and then introducing bilateral interpolation to improve volumetric shadows. This contribution is done by removing the inherent deficiencies significantly in shadow maps. This technique allows obtaining soft marvelous volumetric shadows, having a good performance and high quality, which show its potential for interactive applications.

  16. Visualization and volumetric structures from MR images of the brain

    Energy Technology Data Exchange (ETDEWEB)

    Parvin, B.; Johnston, W.; Robertson, D.

    1994-03-01

    Pinta is a system for segmentation and visualization of anatomical structures obtained from serial sections reconstructed from magnetic resonance imaging. The system approaches the segmentation problem by assigning each volumetric region to an anatomical structure. This is accomplished by satisfying constraints at the pixel level, slice level, and volumetric level. Each slice is represented by an attributed graph, where nodes correspond to regions and links correspond to the relations between regions. These regions are obtained by grouping pixels based on similarity and proximity. The slice level attributed graphs are then coerced to form a volumetric attributed graph, where volumetric consistency can be verified. The main novelty of our approach is in the use of the volumetric graph to ensure consistency from symbolic representations obtained from individual slices. In this fashion, the system allows errors to be made at the slice level, yet removes them when the volumetric consistency cannot be verified. Once the segmentation is complete, the 3D surfaces of the brain can be constructed and visualized.

  17. Equivalent uniform dose concept evaluated by theoretical dose volume histograms for thoracic irradiation.

    Science.gov (United States)

    Dumas, J L; Lorchel, F; Perrot, Y; Aletti, P; Noel, A; Wolf, D; Courvoisier, P; Bosset, J F

    2007-03-01

    The goal of our study was to quantify the limits of the EUD models for use in score functions in inverse planning software, and for clinical application. We focused on oesophagus cancer irradiation. Our evaluation was based on theoretical dose volume histograms (DVH), and we analyzed them using volumetric and linear quadratic EUD models, average and maximum dose concepts, the linear quadratic model and the differential area between each DVH. We evaluated our models using theoretical and more complex DVHs for the above regions of interest. We studied three types of DVH for the target volume: the first followed the ICRU dose homogeneity recommendations; the second was built out of the first requirements and the same average dose was built in for all cases; the third was truncated by a small dose hole. We also built theoretical DVHs for the organs at risk, in order to evaluate the limits of, and the ways to use both EUD(1) and EUD/LQ models, comparing them to the traditional ways of scoring a treatment plan. For each volume of interest we built theoretical treatment plans with differences in the fractionation. We concluded that both volumetric and linear quadratic EUDs should be used. Volumetric EUD(1) takes into account neither hot-cold spot compensation nor the differences in fractionation, but it is more sensitive to the increase of the irradiated volume. With linear quadratic EUD/LQ, a volumetric analysis of fractionation variation effort can be performed.

  18. UFO - The Universal FEYNRULES Output

    Science.gov (United States)

    Degrande, Céline; Duhr, Claude; Fuks, Benjamin; Grellscheid, David; Mattelaer, Olivier; Reiter, Thomas

    2012-06-01

    We present a new model format for automatized matrix-element generators, the so-called Universal FEYNRULES Output (UFO). The format is universal in the sense that it features compatibility with more than one single generator and is designed to be flexible, modular and agnostic of any assumption such as the number of particles or the color and Lorentz structures appearing in the interaction vertices. Unlike other model formats where text files need to be parsed, the information on the model is encoded into a PYTHON module that can easily be linked to other computer codes. We then describe an interface for the MATHEMATICA package FEYNRULES that allows for an automatic output of models in the UFO format.

  19. Numerical analysis of radiation propagation in innovative volumetric receivers based on selective laser melting techniques

    Science.gov (United States)

    Alberti, Fabrizio; Santiago, Sergio; Roccabruna, Mattia; Luque, Salvador; Gonzalez-Aguilar, Jose; Crema, Luigi; Romero, Manuel

    2016-05-01

    Volumetric absorbers constitute one of the key elements in order to achieve high thermal conversion efficiencies in concentrating solar power plants. Regardless of the working fluid or thermodynamic cycle employed, design trends towards higher absorber output temperatures are widespread, which lead to the general need of components of high solar absorptance, high conduction within the receiver material, high internal convection, low radiative and convective heat losses and high mechanical durability. In this context, the use of advanced manufacturing techniques, such as selective laser melting, has allowed for the fabrication of intricate geometries that are capable of fulfilling the previous requirements. This paper presents a parametric design and analysis of the optical performance of volumetric absorbers of variable porosity conducted by means of detailed numerical ray tracing simulations. Sections of variable macroscopic porosity along the absorber depth were constructed by the fractal growth of single-cell structures. Measures of performance analyzed include optical reflection losses from the absorber front and rear faces, penetration of radiation inside the absorber volume, and radiation absorption as a function of absorber depth. The effects of engineering design parameters such as absorber length and wall thickness, material reflectance and porosity distribution on the optical performance of absorbers are discussed, and general design guidelines are given.

  20. Aggregate Supply and Potential Output

    OpenAIRE

    Razin, Assaf

    2004-01-01

    The New-Keynesian aggregate supply derives from micro-foundations an inflation-dynamics model very much like the tradition in the monetary literature. Inflation is primarily affected by: (i) economic slack; (ii) expectations; (iii) supply shocks; and (iv) inflation persistence. This paper extends the New Keynesian aggregate supply relationship to include also fluctuations in potential output, as an additional determinant of the relationship. Implications for monetary rules and to the estimati...

  1. Long-Term Volumetric Eruption Rates and Magma Budgets

    Energy Technology Data Exchange (ETDEWEB)

    Scott M. White Dept. Geological Sciences University of South Carolina Columbia, SC 29208; Joy A. Crisp Jet Propulsion Laboratory, California Institute of Technology Pasadena, CA 91109; Frank J. Spera Dept. Earth Science University of California, Santa Barbara Santa Barbara, CA 93106

    2005-01-01

    A global compilation of 170 time-averaged volumetric volcanic output rates (Qe) is evaluated in terms of composition and petrotectonic setting to advance the understanding of long-term rates of magma generation and eruption on Earth. Repose periods between successive eruptions at a given site and intrusive:extrusive ratios were compiled for selected volcanic centers where long-term (>104 years) data were available. More silicic compositions, rhyolites and andesites, have a more limited range of eruption rates than basalts. Even when high Qe values contributed by flood basalts (9 ± 2 Å~ 10-1 km3/yr) are removed, there is a trend in decreasing average Qe with lava composition from basaltic eruptions (2.6 ± 1.0 Å~ 10-2 km3/yr) to andesites (2.3 ± 0.8 Å~ 10-3 km3/yr) and rhyolites (4.0 ± 1.4 Å~ 10-3 km3/yr). This trend is also seen in the difference between oceanic and continental settings, as eruptions on oceanic crust tend to be predominately basaltic. All of the volcanoes occurring in oceanic settings fail to have statistically different mean Qe and have an overall average of 2.8 ± 0.4 Å~ 10-2 km3/yr, excluding flood basalts. Likewise, all of the volcanoes on continental crust also fail to have statistically different mean Qe and have an overall average of 4.4 ± 0.8 Å~ 10-3 km3/yr. Flood basalts also form a distinctive class with an average Qe nearly two orders of magnitude higher than any other class. However, we have found no systematic evidence linking increased intrusive:extrusive ratios with lower volcanic rates. A simple heat balance analysis suggests that the preponderance of volcanic systems must be open magmatic systems with respect to heat and matter transport in order to maintain eruptible magma at shallow depth throughout the observed lifetime of the volcano. The empirical upper limit of Å`10-2 km3/yr for magma eruption rate in systems with relatively high intrusive:extrusive ratios may be a consequence of the fundamental parameters

  2. Volumetric fat-water separated T2-weighted MRI

    International Nuclear Information System (INIS)

    Vasanawala, Shreyas S.; Sonik, Arvind; Madhuranthakam, Ananth J.; Venkatesan, Ramesh; Lai, Peng; Brau, Anja C.S.

    2011-01-01

    Pediatric body MRI exams often cover multiple body parts, making the development of broadly applicable protocols and obtaining uniform fat suppression a challenge. Volumetric T2 imaging with Dixon-type fat-water separation might address this challenge, but it is a lengthy process. We develop and evaluate a faster two-echo approach to volumetric T2 imaging with fat-water separation. A volumetric spin-echo sequence was modified to include a second shifted echo so two image sets are acquired. A region-growing reconstruction approach was developed to decompose separate water and fat images. Twenty-six children were recruited with IRB approval and informed consent. Fat-suppression quality was graded by two pediatric radiologists and compared against conventional fat-suppressed fast spin-echo T2-W images. Additionally, the value of in- and opposed-phase images was evaluated. Fat suppression on volumetric images had high quality in 96% of cases (95% confidence interval of 80-100%) and were preferred over or considered equivalent to conventional two-dimensional fat-suppressed FSE T2 imaging in 96% of cases (95% confidence interval of 78-100%). In- and opposed-phase images had definite value in 12% of cases. Volumetric fat-water separated T2-weighted MRI is feasible and is likely to yield improved fat suppression over conventional fat-suppressed T2-weighted imaging. (orig.)

  3. Volumetric image interpretation in radiology: scroll behavior and cognitive processes.

    Science.gov (United States)

    den Boer, Larissa; van der Schaaf, Marieke F; Vincken, Koen L; Mol, Chris P; Stuijfzand, Bobby G; van der Gijp, Anouk

    2018-05-16

    The interpretation of medical images is a primary task for radiologists. Besides two-dimensional (2D) images, current imaging technologies allow for volumetric display of medical images. Whereas current radiology practice increasingly uses volumetric images, the majority of studies on medical image interpretation is conducted on 2D images. The current study aimed to gain deeper insight into the volumetric image interpretation process by examining this process in twenty radiology trainees who all completed four volumetric image cases. Two types of data were obtained concerning scroll behaviors and think-aloud data. Types of scroll behavior concerned oscillations, half runs, full runs, image manipulations, and interruptions. Think-aloud data were coded by a framework of knowledge and skills in radiology including three cognitive processes: perception, analysis, and synthesis. Relating scroll behavior to cognitive processes showed that oscillations and half runs coincided more often with analysis and synthesis than full runs, whereas full runs coincided more often with perception than oscillations and half runs. Interruptions were characterized by synthesis and image manipulations by perception. In addition, we investigated relations between cognitive processes and found an overall bottom-up way of reasoning with dynamic interactions between cognitive processes, especially between perception and analysis. In sum, our results highlight the dynamic interactions between these processes and the grounding of cognitive processes in scroll behavior. It suggests, that the types of scroll behavior are relevant to describe how radiologists interact with and manipulate volumetric images.

  4. Judicial Influence on Policy Outputs?

    DEFF Research Database (Denmark)

    Martinsen, Dorte Sindbjerg

    2015-01-01

    to override unwanted jurisprudence. In this debate, the Court of Justice of the European Union (CJEU) has become famous for its central and occasionally controversial role in European integration. This article examines to what extent and under which conditions judicial decisions influence European Union (EU......) social policy outputs. A taxonomy of judicial influence is constructed, and expectations of institutional and political conditions on judicial influence are presented. The analysis draws on an extensive novel data set and examines judicial influence on EU social policies over time, that is, between 1958...

  5. Discrete pre-processing step effects in registration-based pipelines, a preliminary volumetric study on T1-weighted images.

    Science.gov (United States)

    Muncy, Nathan M; Hedges-Muncy, Ariana M; Kirwan, C Brock

    2017-01-01

    Pre-processing MRI scans prior to performing volumetric analyses is common practice in MRI studies. As pre-processing steps adjust the voxel intensities, the space in which the scan exists, and the amount of data in the scan, it is possible that the steps have an effect on the volumetric output. To date, studies have compared between and not within pipelines, and so the impact of each step is unknown. This study aims to quantify the effects of pre-processing steps on volumetric measures in T1-weighted scans within a single pipeline. It was our hypothesis that pre-processing steps would significantly impact ROI volume estimations. One hundred fifteen participants from the OASIS dataset were used, where each participant contributed three scans. All scans were then pre-processed using a step-wise pipeline. Bilateral hippocampus, putamen, and middle temporal gyrus volume estimations were assessed following each successive step, and all data were processed by the same pipeline 5 times. Repeated-measures analyses tested for a main effects of pipeline step, scan-rescan (for MRI scanner consistency) and repeated pipeline runs (for algorithmic consistency). A main effect of pipeline step was detected, and interestingly an interaction between pipeline step and ROI exists. No effect for either scan-rescan or repeated pipeline run was detected. We then supply a correction for noise in the data resulting from pre-processing.

  6. Full-spectrum volumetric solar thermal conversion via photonic nanofluids.

    Science.gov (United States)

    Liu, Xianglei; Xuan, Yimin

    2017-10-12

    Volumetric solar thermal conversion is an emerging technique for a plethora of applications such as solar thermal power generation, desalination, and solar water splitting. However, achieving broadband solar thermal absorption via dilute nanofluids is still a daunting challenge. In this work, full-spectrum volumetric solar thermal conversion is demonstrated over a thin layer of the proposed 'photonic nanofluids'. The underlying mechanism is found to be the photonic superposition of core resonances, shell plasmons, and core-shell resonances at different wavelengths, whose coexistence is enabled by the broken symmetry of specially designed composite nanoparticles, i.e., Janus nanoparticles. The solar thermal conversion efficiency can be improved by 10.8% compared with core-shell nanofluids. The extinction coefficient of Janus dimers with various configurations is also investigated to unveil the effects of particle couplings. This work provides the possibility to achieve full-spectrum volumetric solar thermal conversion, and may have potential applications in efficient solar energy harvesting and utilization.

  7. Volumetric display using a roof mirror grid array

    Science.gov (United States)

    Miyazaki, Daisuke; Hirano, Noboru; Maeda, Yuuki; Ohno, Keisuke; Maekawa, Satoshi

    2010-02-01

    A volumetric display system using a roof mirror grid array (RMGA) is proposed. The RMGA consists of a two-dimensional array of dihedral corner reflectors and forms a real image at a plane-symmetric position. A two-dimensional image formed with a RMGA is moved at thigh speed by a mirror scanner. Cross-sectional images of a three-dimensional object are displayed in accordance with the position of the image plane. A volumetric image can be observed as a stack of the cross-sectional images by high-speed scanning. Image formation by a RMGA is free from aberrations. Moreover, a compact optical system can be constructed because a RMGA doesn't have a focal length. An experimental volumetric display system using a galvanometer mirror and a digital micromirror device was constructed. The formation of a three-dimensional image consisting of 1024 × 768 × 400 voxels is confirmed by the experimental system.

  8. Gradients estimation from random points with volumetric tensor in turbulence

    Science.gov (United States)

    Watanabe, Tomoaki; Nagata, Koji

    2017-12-01

    We present an estimation method of fully-resolved/coarse-grained gradients from randomly distributed points in turbulence. The method is based on a linear approximation of spatial gradients expressed with the volumetric tensor, which is a 3 × 3 matrix determined by a geometric distribution of the points. The coarse grained gradient can be considered as a low pass filtered gradient, whose cutoff is estimated with the eigenvalues of the volumetric tensor. The present method, the volumetric tensor approximation, is tested for velocity and passive scalar gradients in incompressible planar jet and mixing layer. Comparison with a finite difference approximation on a Cartesian grid shows that the volumetric tensor approximation computes the coarse grained gradients fairly well at a moderate computational cost under various conditions of spatial distributions of points. We also show that imposing the solenoidal condition improves the accuracy of the present method for solenoidal vectors, such as a velocity vector in incompressible flows, especially when the number of the points is not large. The volumetric tensor approximation with 4 points poorly estimates the gradient because of anisotropic distribution of the points. Increasing the number of points from 4 significantly improves the accuracy. Although the coarse grained gradient changes with the cutoff length, the volumetric tensor approximation yields the coarse grained gradient whose magnitude is close to the one obtained by the finite difference. We also show that the velocity gradient estimated with the present method well captures the turbulence characteristics such as local flow topology, amplification of enstrophy and strain, and energy transfer across scales.

  9. Cost-effectiveness of volumetric alcohol taxation in Australia.

    Science.gov (United States)

    Byrnes, Joshua M; Cobiac, Linda J; Doran, Christopher M; Vos, Theo; Shakeshaft, Anthony P

    2010-04-19

    To estimate the potential health benefits and cost savings of an alcohol tax rate that applies equally to all alcoholic beverages based on their alcohol content (volumetric tax) and to compare the cost savings with the cost of implementation. Mathematical modelling of three scenarios of volumetric alcohol taxation for the population of Australia: (i) no change in deadweight loss, (ii) no change in tax revenue, and (iii) all alcoholic beverages taxed at the same rate as spirits. Estimated change in alcohol consumption, tax revenue and health benefit. The estimated cost of changing to a volumetric tax rate is $18 million. A volumetric tax that is deadweight loss-neutral would increase the cost of beer and wine and reduce the cost of spirits, resulting in an estimated annual increase in taxation revenue of $492 million and a 2.77% reduction in annual consumption of pure alcohol. The estimated net health gain would be 21 000 disability-adjusted life-years (DALYs), with potential cost offsets of $110 million per annum. A tax revenue-neutral scenario would result in an 0.05% decrease in consumption, and a tax on all alcohol at a spirits rate would reduce consumption by 23.85% and increase revenue by $3094 million [corrected]. All volumetric tax scenarios would provide greater health benefits and cost savings to the health sector than the existing taxation system, based on current understandings of alcohol-related health effects. An equalized volumetric tax that would reduce beer and wine consumption while increasing the consumption of spirits would need to be approached with caution. Further research is required to examine whether alcohol-related health effects vary by type of alcoholic beverage independent of the amount of alcohol consumed to provide a strong evidence platform for alcohol taxation policies.

  10. Hippocampal sparing radiotherapy for glioblastoma patients: a planning study using volumetric modulated arc therapy

    International Nuclear Information System (INIS)

    Hofmaier, Jan; Kantz, Steffi; Söhn, Matthias; Dohm, Oliver S.; Bächle, Stefan; Alber, Markus; Parodi, Katia; Belka, Claus; Niyazi, Maximilian

    2016-01-01

    The purpose of this study is to investigate the potential to reduce exposure of the contralateral hippocampus in radiotherapy for glioblastoma using volumetric modulated arc therapy (VMAT). Datasets of 27 patients who had received 3D conformal radiotherapy (3D-CRT) for glioblastoma with a prescribed dose of 60Gy in fractions of 2Gy were included in this planning study. VMAT plans were optimized with the aim to reduce the dose to the contralateral hippocampus as much as possible without compromising other parameters. Hippocampal dose and treatment parameters were compared to the 3D-CRT plans using the Wilcoxon signed-rank test. The influence of tumour location and PTV size on the hippocampal dose was investigated with the Mann–Whitney-U-test and Spearman’s rank correlation coefficient. The median reduction of the contralateral hippocampus generalized equivalent uniform dose (gEUD) with VMAT was 36 % compared to the original 3D-CRT plans (p < 0.05). Other dose parameters were maintained or improved. The median V30Gy brain could be reduced by 17.9 % (p < 0.05). For VMAT, a parietal and a non-temporal tumour localisation as well as a larger PTV size were predictors for a higher hippocampal dose (p < 0.05). Using VMAT, a substantial reduction of the radiotherapy dose to the contralateral hippocampus for patients with glioblastoma is feasible without compromising other treatment parameters. For larger PTV sizes, less sparing can be achieved. Whether this approach is able to preserve the neurocognitive status without compromising the oncological outcome needs to be investigated in the setting of prospective clinical trials

  11. Volumetric-modulated arc therapy in postprostatectomy radiotherapy patients: A planning comparison study

    International Nuclear Information System (INIS)

    Forde, Elizabeth; Kneebone, Andrew; Bromley, Regina; Guo, Linxin; Hunt, Peter; Eade, Thomas

    2013-01-01

    The purpose of this study was to compare postprostatectomy planning for volumetric-modulated arc therapy (VMAT) with both single arc (SA) and double arcs (DA) against dynamic sliding window intensity-modulated radiotherapy (IMRT). Ten cases were planned with IMRT, SA VMAT, and DA VMAT. All cases were planned to achieve a minimum dose of 68 Gy to 95% of the planning target volume (PTV) and goals to limit rectal volume >40 Gy to 35% and >65 Gy to 17%, and bladder volumes >40 Gy to 50% and >65 Gy to 25%. Plans were averaged across the 10 patients and compared for mean dose, conformity, homogeneity, rectal and bladder doses, and monitor units. The mean dose to the clinical target volume and PTV was significantly higher (p<0.05) for SA compared with DA or IMRT. The homogeneity index was not significantly different: SA = 0.09; DA = 0.08; and IMRT = 0.07. The rectal V40 was lowest for the DA plan. The rectal V20 was significantly lower (p<0.05) for both the VMAT plans compared with IMRT. There were no significant differences for bladder V40 or rectal and bladder V65. The IMRT plans required 1400 MU compared with 745 for DA and 708 for SA. This study shows that for equivalent dose coverage, SA and DA VMAT plans result in higher mean doses to the clinical target volume and PTV. This greater dose heterogeneity is balanced by improved low-range rectal doses and halving of the monitor units

  12. Volumetric-modulated arc therapy in postprostatectomy radiotherapy patients: A planning comparison study

    Energy Technology Data Exchange (ETDEWEB)

    Forde, Elizabeth, E-mail: eforde@tcd.ie [Radiation Oncology Department, Northern Sydney Cancer Centre, St Leonards, New South Wales (Australia); Kneebone, Andrew [Radiation Oncology Department, Northern Sydney Cancer Centre, St Leonards, New South Wales (Australia); Northern Clinical School, University of Sydney, New South Wales (Australia); Bromley, Regina [Institute of Medical Physics, School of Physics, University of Sydney, New South Wales (Australia); Guo, Linxin; Hunt, Peter [Radiation Oncology Department, Northern Sydney Cancer Centre, St Leonards, New South Wales (Australia); Eade, Thomas [Radiation Oncology Department, Northern Sydney Cancer Centre, St Leonards, New South Wales (Australia); Northern Clinical School, University of Sydney, New South Wales (Australia)

    2013-10-01

    The purpose of this study was to compare postprostatectomy planning for volumetric-modulated arc therapy (VMAT) with both single arc (SA) and double arcs (DA) against dynamic sliding window intensity-modulated radiotherapy (IMRT). Ten cases were planned with IMRT, SA VMAT, and DA VMAT. All cases were planned to achieve a minimum dose of 68 Gy to 95% of the planning target volume (PTV) and goals to limit rectal volume >40 Gy to 35% and >65 Gy to 17%, and bladder volumes >40 Gy to 50% and >65 Gy to 25%. Plans were averaged across the 10 patients and compared for mean dose, conformity, homogeneity, rectal and bladder doses, and monitor units. The mean dose to the clinical target volume and PTV was significantly higher (p<0.05) for SA compared with DA or IMRT. The homogeneity index was not significantly different: SA = 0.09; DA = 0.08; and IMRT = 0.07. The rectal V40 was lowest for the DA plan. The rectal V20 was significantly lower (p<0.05) for both the VMAT plans compared with IMRT. There were no significant differences for bladder V40 or rectal and bladder V65. The IMRT plans required 1400 MU compared with 745 for DA and 708 for SA. This study shows that for equivalent dose coverage, SA and DA VMAT plans result in higher mean doses to the clinical target volume and PTV. This greater dose heterogeneity is balanced by improved low-range rectal doses and halving of the monitor units.

  13. Kredsløbsmonitorering med lithium dilution cardiac output-systemet

    DEFF Research Database (Denmark)

    Christiansen, Christian; Hostrup, Anette; Tønnesen, Else

    2008-01-01

    The lithium dilution cardiac output (LiDCO) system measures cardiac output beat-to-beat with high precision. The system is based on an arterial pulse power analysis which is calibrated every eight hours with a small non-pharmacological dose of lithium. The system is minimally invasive; it requires...

  14. Monitoring Linear Accelerator Output Constancy Using the PTW Linacheck

    International Nuclear Information System (INIS)

    McDermott, Garry M.; Buckle, Andrew H.

    2011-01-01

    The PTW-Linacheck was assessed for its ability to monitor linear accelerator radiation output constancy. The key issues that were considered were the setup for daily output measurements, e.g., requirements for build-up and backscatter material, and the reproducibility and linearity of the device with linear accelerator output. An appropriate measurement setup includes a 10 x 10 cm field at 100 cm FSD, 5 cm backscatter, and no added build-up for 4 MeV electron beams, 1 cm added build-up for 6-16 MeV electron beams and 5 cm added build-up for 6-15 MV photon beams. Using this measurement setup, the dose linearity and short-term reproducibility were acceptable; however, the Linacheck should be recalibrated on a monthly basis to ensure acceptable long-term reproducibility.

  15. SU-D-BRE-06: Modeling the Dosimetric Effects of Volumetric and Layer-Based Repainting Strategies in Spot Scanning Proton Treatment Plans

    International Nuclear Information System (INIS)

    Johnson, J E; Beltran, C; Herman, M G; Kruse, J J

    2014-01-01

    Purpose: To compare multiple repainting techniques as strategies for mitigating the interplay effect in free-breathing, spot scanning proton plans. Methods: An analytic routine modeled three-dimensional dose distributions of pencil-beam proton plans delivered to a moving target. The interplay effect was studied in subsequent calculations by modeling proton delivery from a clinical synchrotron based spot scanning system and respiratory target motion, patterned from surrogate breathing traces from clinical 4DCT scans and normalized to nominal 0.5 and 1 cm amplitudes. Two distinct repainting strategies were modeled. In idealized volumetric repainting, the plan is divided up and delivered multiple times successively, with each instance only delivering a fraction of the total MU. Maximum-MU repainting involves delivering a fixed number of MU per spot and repeating a given energy layer until the prescribed MU are reached. For each of 13 patient breathing traces, the dose was computed for up to four volumetric repaints and an array of maximum-MU values. Delivery strategies were inter-compared based on target coverage, dose homogeneity, and delivery time. Results: Increasing levels of repainting generally improved plan quality and reduced dosimetric variability at the expense of longer delivery time. Motion orthogonal to the scan direction yielded substantially greater dose deviations than motion parallel to the scan direction. For a fixed delivery time, maximum-MU repainting was most effective relative to idealized volumetric repainting at small maximum-MU values. For 1 cm amplitude motion orthogonal to the scan direction, the average homogeneity metric (D5 – D95)[%] of 23.4% was reduced to 7.6% with a 168 s delivery using volumetric repainting compared with 8.7% in 157.2 s for maximum-MU repainting. The associated static target homogeneity metric was 2.5%. Conclusion: Maximum-MU repainting can provide a reasonably effective alternative to volumetric repainting for

  16. The dosimetric effects of photon energy on the quality of prostate volumetric modulated arc therapy.

    Science.gov (United States)

    Mattes, Malcolm D; Tai, Cyril; Lee, Alvin; Ashamalla, Hani; Ikoro, N C

    2014-01-01

    Studies comparing the dosimetric effects of high- and low-energy photons to treat prostate cancer using 3-dimensional conformal and intensity modulated radiation therapy have yielded mixed results. With the advent of newer radiation delivery systems like volumetric modulated arc therapy (VMAT), the impact of changing photon energy is readdressed. Sixty-five patients treated for prostate cancer at our institution from 2011 to 2012 underwent CT simulation. A target volume encompassing the prostate and entire seminal vesicles was treated to 50.4 Gy, followed by a boost to the prostate and proximal seminal vesicles to a total dose of 81 Gy. The VMAT plans were generated for 6-MV and 10-MV photons under identical optimization conditions using the Eclipse system version 8.6 (Varian Medical Systems, Palo Alto, CA). The analytical anisotropic algorithm was used for all dose calculations. Plans were normalized such that 98% of the planning target volume (PTV) received 100% of the prescribed dose. Dose-volumetric data from the treatment planning system was recorded for both 6-MV and 10-MV plans, which were compared for both the entire cohort and subsets of patients stratified according to the anterior-posterior separation. Plans using 10-MV photons had statistically significantly lower relative integral dose (4.1%), gradient measure (4.1%), skin Dmax (16.9%), monitor units (13.0%), and bladder V(30) (3.1%) than plans using 6-MV photons (P photons was more pronounced for thicker patients (anterior-posterior separation >21 cm) for most parameters, with statistically significant differences in bladder V(30), bladder V(65), integral dose, conformity index, and monitor units. The main dosimetric benefits of 10-MV as compared with 6-MV photons are seen in thicker patients, though for the entire cohort 10-MV plans resulted in a lower integral dose, gradient measure, skin Dmax, monitor units, and bladder V(30), possibly at the expense of higher rectum V(81). Copyright © 2014

  17. Evaluating the output stability of LINAC with a reference detector using 3D water phantom

    International Nuclear Information System (INIS)

    Shimozato, Tomohiro; Kojima, Tomo; Sakamoto, Masataka; Hata, Yuji; Sasaki, Koji; Araki, Noriyuki

    2013-01-01

    We report the discovery of abnormal fluctuations in the output obtained when measuring a water phantom and adjustments that reduce these outliers. Using a newly developed three-dimensional scanning water phantom system, we obtained the depth dose and off-axis dose ratio required for the beam data of a medical linear accelerator (LINAC). The field and reference detectors were set such that the measured values could be viewed in real time. We confirmed the scanning data using the field detector and the change in the output using the reference detector while measuring by using the water phantom. Prior to output adjustment of the LINAC, we observed output abnormalities as high as 18.4%. With optimization of accelerator conditions, the average of the output fluctuation width was reduced to less than ±0.5%. Through real-time graphing of reference detector measurements during measurement of field detector, we were able to rapidly identify abnormal fluctuations. Although beam data collected during radiation treatment planning are corrected for output fluctuations, it is possible that sudden abnormal fluctuations actually occur in the output. Therefore, the equipment should be tested for output fluctuations at least once a year. Even after minimization of fluctuations, we recommend determining the potential dose administered to the human body taking into account the width of the output fluctuation. (author)

  18. Peak Dose Assessment for Proposed DOE-PPPO Authorized Limits

    International Nuclear Information System (INIS)

    Maldonado, Delis

    2012-01-01

    The Oak Ridge Institute for Science and Education (ORISE), a U.S. Department of Energy (DOE) prime contractor, was contracted by the DOE Portsmouth/Paducah Project Office (DOE-PPPO) to conduct a peak dose assessment in support of the Authorized Limits Request for Solid Waste Disposal at Landfill C-746-U at the Paducah Gaseous Diffusion Plant (DOE-PPPO 2011a). The peak doses were calculated based on the DOE-PPPO Proposed Single Radionuclides Soil Guidelines and the DOE-PPPO Proposed Authorized Limits (AL) Volumetric Concentrations available in DOE-PPPO 2011a. This work is provided as an appendix to the Dose Modeling Evaluations and Technical Support Document for the Authorized Limits Request for the C-746-U Landfill at the Paducah Gaseous Diffusion Plant, Paducah, Kentucky (ORISE 2012). The receptors evaluated in ORISE 2012 were selected by the DOE-PPPO for the additional peak dose evaluations. These receptors included a Landfill Worker, Trespasser, Resident Farmer (onsite), Resident Gardener, Recreational User, Outdoor Worker and an Offsite Resident Farmer. The RESRAD (Version 6.5) and RESRAD-OFFSITE (Version 2.5) computer codes were used for the peak dose assessments. Deterministic peak dose assessments were performed for all the receptors and a probabilistic dose assessment was performed only for the Offsite Resident Farmer at the request of the DOE-PPPO. In a deterministic analysis, a single input value results in a single output value. In other words, a deterministic analysis uses single parameter values for every variable in the code. By contrast, a probabilistic approach assigns parameter ranges to certain variables, and the code randomly selects the values for each variable from the parameter range each time it calculates the dose (NRC 2006). The receptor scenarios, computer codes and parameter input files were previously used in ORISE 2012. A few modifications were made to the parameter input files as appropriate for this effort. Some of these changes

  19. Volumetric measurements of pulmonary nodules at multi-row detector CT: in vivo reproducibility

    International Nuclear Information System (INIS)

    Wormanns, Dag; Marheine, Anke; Beyer, Florian; Heindel, Walter; Diederich, Stefan; Kohl, Gerhard; Klotz, Ernst

    2004-01-01

    The aim of this study was to assess the in vivo measurement precision of a software tool for volumetric analysis of pulmonary nodules from two consecutive low-dose multi-row detector CT scans. A total of 151 pulmonary nodules (diameter 2.2-20.5 mm, mean diameter 7.4±4.5 mm) in ten subjects with pulmonary metastases were examined with low-dose four-detector-row CT (120 kVp, 20 mAs (effective), collimation 4 x 1 mm, normalized pitch 1.75, slice thickness 1.25 mm, reconstruction increment 0.8 mm; Somatom VolumeZoom, Siemens). Two consecutive low-dose scans covering the whole lung were performed within 10 min. Nodule volume was determined for all pulmonary nodules visually detected in both scans using the volumetry tool included in the Siemens LungCare software. The 95% limits of agreement between nodule volume measurements on different scans were calculated using the Bland and Altman method for assessing measurement agreement. Intra- and interobserver agreement of volume measurement were determined using repetitive measurements of 50 randomly selected nodules at the same scan by the same and different observers. Taking into account all 151 nodules, 95% limits of agreement were -20.4 to 21.9% (standard error 1.5%); they were -19.3 to 20.4% (standard error 1.7%) for 105 nodules <10 mm. Limits of agreement were -3.9 to 5.7% for intraobserver and -5.5 to 6.6% for interobserver agreement. Precision of in vivo volumetric analysis of nodules with an automatic volumetry software tool was sufficiently high to allow for detection of clinically relevant growth in small pulmonary nodules. (orig.)

  20. Integration of TMVA Output into Jupyter notebooks

    CERN Document Server

    Saliji, Albulena

    2016-01-01

    The purpose of this report is to describe the work that I have been doing during these past eight weeks as a Summer Student at CERN. The task which was assigned to me had to do with the integration of TMVA Output into Jupyter notebooks. In order to integrate the TMVA Output into the Jupyter notebook, first, improvement of the TMVA Output in the terminal was required. Once the output was improved, it needed to be transformed into HTML output and at the end it would be possible to integrate that output into the Jupyter notebook.

  1. Dosimetric comparison of volumetric modulated arc therapy (VMAT), DMlC (Dynamic IMRT), and 3DCRT in left breast cancer after breast conserving surgery receiving left breast irradiation

    International Nuclear Information System (INIS)

    Pratibha, Bauskar; Vibhay, Pareek; Rajendra, Bhalavat; Chandra, Manish

    2016-01-01

    Previous studies have demonstrated that the risk of ischemic heart disease is increased as a result of exposure to ionizing radiation in women treated for breast cancer. Alternative radiation techniques, such as dynamic intensity-modulated radiation therapy (DMLC), volumetric-modulated arc therapy (VMAT), have been shown to improve dosimetric parameters of the heart and substructures. However, these techniques have not been compared with each other to potentially guide treatment decisions. Volumetric modulated arc therapy (VMAT) is a novel extension of conventional intensity-modulated radiotherapy (c-IMRT), in which an optimized three dimensional dose distribution may be delivered in a single gantry rotation. VMAT is the predecessor to Rapid-Arc (Varian Medical System). This study uses VMAT, DMLC and 3DCRT to compare target volume coverage and doses to organs at risk (OARs), especially lung and heart doses, using these three techniques in whole breast irradiation after breast conserving surgery in left breast cancer cases

  2. SU-E-T-449: Hippocampal Sparing Radiotherapy Using Intensity Modulated Radiotherapy and Volumetric Modulated Arc Therapy

    Energy Technology Data Exchange (ETDEWEB)

    Moon, S [Korea University, Seoul (Korea, Republic of); Kyung Hee University Hospital at Gangdong, Gangdong-gu (Korea, Republic of); Kim, D; Chung, W [Kyung Hee University Hospital at Gangdong, Gangdong-gu (Korea, Republic of); Yoon, M [Korea University, Seoul (Korea, Republic of)

    2015-06-15

    Purpose: The hippocampus sparing during the cranial irradiation has become interesting because it may mitigate radiation-induced neurocognitive toxicity. Herein we report our preliminary study for sparing the hippocampus with and without tilling condition for patient with brain metastases. Methods: Ten patients previously treated with whole brain were reviewed. Five patients tilted the head to around 30 degrees and others were treated without tilting. Treatment plans of linear accelerator (Linac)-based volumetric modulated arc therapy (VMAT) and intensity modulated radiotherapy (IMRT) were generated for prescription dose of 30 Gy in 15 fractions. Hippocampal avoidance regions were created with 5-mm volumetric expansion around the hippocampus. Whole brain, hippocampus and hippocampal avoidance volume were 1372cm3, 6cm3 and 30cm3 and hippocampal avoidance volume was 2.2% of the whole brain planned target volume in average. Organs at risk (OARs) are hippocampus, eyes, lens, and cochleae. Coverage index (CVI), conformity index (CI), homogeneity index (HI) and mean dose to OARs were used to compare dose characteristic of tilted and non-tilted cases. Results: In IMRT, when CI, CVI and HI of whole brain were 0.88, 0.09 and 0.98 in both tilted and non-tilted cases, absorbed dose of hippocampal avoidance volume in tilted cases were 10% lower than non-tilted cases. Doses in other OARs such as eyes, lens, and cochleae were also decreased about 20% when tilting the head. When CI, HI and CVI in VMAT were 0.9, 0.08 and 0.99, the dose-decreased ratio of OARs in both with and without tilting cases were almost the same with IMRT. But absolute dose of hippocampal avoidance volume in VMAT was 30% lower than IMRT. Conclusion: This study confirms that dose to hippocampus decreases if patients tilt the head. When treating the whole brain with head tilted, patients can acquire the same successful treatment Result and also preserve their valuable memory.

  3. X-ray volumetric imaging in image-guided radiotherapy: The new standard in on-treatment imaging

    International Nuclear Information System (INIS)

    McBain, Catherine A.; Henry, Ann M.; Sykes, Jonathan; Amer, Ali; Marchant, Tom; Moore, Christopher M.; Davies, Julie; Stratford, Julia; McCarthy, Claire; Porritt, Bridget; Williams, Peter; Khoo, Vincent S.; Price, Pat

    2006-01-01

    Purpose: X-ray volumetric imaging (XVI) for the first time allows for the on-treatment acquisition of three-dimensional (3D) kV cone beam computed tomography (CT) images. Clinical imaging using the Synergy System (Elekta, Crawley, UK) commenced in July 2003. This study evaluated image quality and dose delivered and assessed clinical utility for treatment verification at a range of anatomic sites. Methods and Materials: Single XVIs were acquired from 30 patients undergoing radiotherapy for tumors at 10 different anatomic sites. Patients were imaged in their setup position. Radiation doses received were measured using TLDs on the skin surface. The utility of XVI in verifying target volume coverage was qualitatively assessed by experienced clinicians. Results: X-ray volumetric imaging acquisition was completed in the treatment position at all anatomic sites. At sites where a full gantry rotation was not possible, XVIs were reconstructed from projection images acquired from partial rotations. Soft-tissue definition of organ boundaries allowed direct assessment of 3D target volume coverage at all sites. Individual image quality depended on both imaging parameters and patient characteristics. Radiation dose ranged from 0.003 Gy in the head to 0.03 Gy in the pelvis. Conclusions: On-treatment XVI provided 3D verification images with soft-tissue definition at all anatomic sites at acceptably low radiation doses. This technology sets a new standard in treatment verification and will facilitate novel adaptive radiotherapy techniques

  4. What are the potential advantages and disadvantages of volumetric CT scanning?

    Science.gov (United States)

    Voros, Szilard

    2009-01-01

    After the introduction and dissemination of 64-slice multislice computed tomography systems, cardiovascular CT has arrived at a crossroad, and different philosophies lead down different paths of technologic development. Increased number of detector rows in the z-axis led to the introduction of dynamic, volumetric scanning of the heart and allows for whole-organ imaging. Dynamic, volumetric "whole-organ" scanning significantly reduces image acquisition time; "single-beat whole-heart imaging" results in improved image quality and reduced radiation exposure and reduced contrast dose. It eliminates helical and pitch artifacts and allows for simultaneous imaging of the base and apex of the heart. Beyond coronary arterial luminal imaging, such innovations open up the opportunity for myocardial perfusion and viability imaging and coronary arterial plaque imaging. Dual-source technology with 2 x-ray tubes placed at 90-degree angles provides heart rate-independent temporal resolution and has the potential for tissue characterization on the basis of different attenuation values at different energy levels. Refined detector technology allows for improved low-contrast resolution and may be beneficial for more detailed evaluation of coronary arterial plaque composition. The clinical benefit of each of these technologies will have to be evaluated in carefully designed clinical trials and in everyday clinical practice. Such combined experience will probably show the relative benefit of each of these philosophies in different patient populations and in different clinical scenarios.

  5. A retrospective analysis for patient-specific quality assurance of volumetric-modulated arc therapy plans

    International Nuclear Information System (INIS)

    Li, Guangjun; Wu, Kui; Peng, Guang; Zhang, Yingjie; Bai, Sen

    2014-01-01

    Volumetric-modulated arc therapy (VMAT) is now widely used clinically, as it is capable of delivering a highly conformal dose distribution in a short time interval. We retrospectively analyzed patient-specific quality assurance (QA) of VMAT and examined the relationships between the planning parameters and the QA results. A total of 118 clinical VMAT cases underwent pretreatment QA. All plans had 3-dimensional diode array measurements, and 69 also had ion chamber measurements. Dose distribution and isocenter point dose were evaluated by comparing the measurements and the treatment planning system (TPS) calculations. In addition, the relationship between QA results and several planning parameters, such as dose level, control points (CPs), monitor units (MUs), average field width, and average leaf travel, were also analyzed. For delivered dose distribution, a gamma analysis passing rate greater than 90% was obtained for all plans and greater than 95% for 100 of 118 plans with the 3%/3-mm criteria. The difference (mean ± standard deviation) between the point doses measured by the ion chamber and those calculated by TPS was 0.9% ± 2.0% for all plans. For all cancer sites, nasopharyngeal carcinoma and gastric cancer have the lowest and highest average passing rates, respectively. From multivariate linear regression analysis, the dose level (p = 0.001) and the average leaf travel (p < 0.001) showed negative correlations with the passing rate, and the average field width (p = 0.003) showed a positive correlation with the passing rate, all indicating a correlation between the passing rate and the plan complexity. No statistically significant correlation was found between MU or CP and the passing rate. Analysis of the results of dosimetric pretreatment measurements as a function of VMAT plan parameters can provide important information to guide the plan parameter setting and optimization in TPS

  6. A retrospective analysis for patient-specific quality assurance of volumetric-modulated arc therapy plans

    Energy Technology Data Exchange (ETDEWEB)

    Li, Guangjun [Radiation Physics Center, Cancer Center and State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan (China); Wu, Kui [Department of Radiotherapy, The Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, Zhejiang Province (China); Peng, Guang; Zhang, Yingjie [Radiation Physics Center, Cancer Center and State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan (China); Bai, Sen, E-mail: baisen@scu.edu.cn [Radiation Physics Center, Cancer Center and State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan (China)

    2014-01-01

    Volumetric-modulated arc therapy (VMAT) is now widely used clinically, as it is capable of delivering a highly conformal dose distribution in a short time interval. We retrospectively analyzed patient-specific quality assurance (QA) of VMAT and examined the relationships between the planning parameters and the QA results. A total of 118 clinical VMAT cases underwent pretreatment QA. All plans had 3-dimensional diode array measurements, and 69 also had ion chamber measurements. Dose distribution and isocenter point dose were evaluated by comparing the measurements and the treatment planning system (TPS) calculations. In addition, the relationship between QA results and several planning parameters, such as dose level, control points (CPs), monitor units (MUs), average field width, and average leaf travel, were also analyzed. For delivered dose distribution, a gamma analysis passing rate greater than 90% was obtained for all plans and greater than 95% for 100 of 118 plans with the 3%/3-mm criteria. The difference (mean ± standard deviation) between the point doses measured by the ion chamber and those calculated by TPS was 0.9% ± 2.0% for all plans. For all cancer sites, nasopharyngeal carcinoma and gastric cancer have the lowest and highest average passing rates, respectively. From multivariate linear regression analysis, the dose level (p = 0.001) and the average leaf travel (p < 0.001) showed negative correlations with the passing rate, and the average field width (p = 0.003) showed a positive correlation with the passing rate, all indicating a correlation between the passing rate and the plan complexity. No statistically significant correlation was found between MU or CP and the passing rate. Analysis of the results of dosimetric pretreatment measurements as a function of VMAT plan parameters can provide important information to guide the plan parameter setting and optimization in TPS.

  7. A retrospective analysis for patient-specific quality assurance of volumetric-modulated arc therapy plans.

    Science.gov (United States)

    Li, Guangjun; Wu, Kui; Peng, Guang; Zhang, Yingjie; Bai, Sen

    2014-01-01

    Volumetric-modulated arc therapy (VMAT) is now widely used clinically, as it is capable of delivering a highly conformal dose distribution in a short time interval. We retrospectively analyzed patient-specific quality assurance (QA) of VMAT and examined the relationships between the planning parameters and the QA results. A total of 118 clinical VMAT cases underwent pretreatment QA. All plans had 3-dimensional diode array measurements, and 69 also had ion chamber measurements. Dose distribution and isocenter point dose were evaluated by comparing the measurements and the treatment planning system (TPS) calculations. In addition, the relationship between QA results and several planning parameters, such as dose level, control points (CPs), monitor units (MUs), average field width, and average leaf travel, were also analyzed. For delivered dose distribution, a gamma analysis passing rate greater than 90% was obtained for all plans and greater than 95% for 100 of 118 plans with the 3%/3-mm criteria. The difference (mean ± standard deviation) between the point doses measured by the ion chamber and those calculated by TPS was 0.9% ± 2.0% for all plans. For all cancer sites, nasopharyngeal carcinoma and gastric cancer have the lowest and highest average passing rates, respectively. From multivariate linear regression analysis, the dose level (p = 0.001) and the average leaf travel (p < 0.001) showed negative correlations with the passing rate, and the average field width (p = 0.003) showed a positive correlation with the passing rate, all indicating a correlation between the passing rate and the plan complexity. No statistically significant correlation was found between MU or CP and the passing rate. Analysis of the results of dosimetric pretreatment measurements as a function of VMAT plan parameters can provide important information to guide the plan parameter setting and optimization in TPS. Copyright © 2014 American Association of Medical Dosimetrists. Published by

  8. Observability of linear systems with saturated outputs

    NARCIS (Netherlands)

    Koplon, R.; Sontag, E.D.; Hautus, M.L.J.

    1994-01-01

    We present necessary and sufficient conditions for observability of the class of output-saturated systems. These are linear systems whose output passes through a saturation function before it can be measured.

  9. Epithelioid hemangioendothelioma of the spine treated with RapidArc volumetric-modulated radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Guy, Jean-Baptiste; Trone, Jane-Chloé [Department of Radiotherapy, Institut de Cancérologie de la Loire, St Priest en Jarez (France); Chargari, Cyrus [Department of Radiation Oncology, HIA du Val de Grâce, Paris (France); Falk, Alexander Tuan [Department of Radiation Oncology, Centre Antoine Lacassagne, Nice (France); Khodri, Mustapha [Department of Physics, Institut de Cancérologie de la Loire, St Priest en Jarez (France); Magné, Nicolas, E-mail: nicolas.magne@icloire.fr [Department of Radiotherapy, Institut de Cancérologie de la Loire, St Priest en Jarez (France)

    2014-10-01

    Radiotherapy for epithelioid hemangioendothelioma (EHE) using volumetric intensity-modulated arc radiotherapy (VMAT). A 48-year-old woman was referred for curative irradiation of a vertebral EHE after failure of surgery. A comparison between VMAT and conventional conformal tridimensional (3D) dosimetry was performed and potential advantage of VMAT for sparing critical organs from irradiation's side effects was discussed. The total delivered dose on the planning target volume was 54 Gy in 27 fractions. The patient was finally treated with VMAT. The tolerance was excellent. There was no acute toxicity, including no increase in pain. With a follow-up of 18 months, no delayed toxicity was reported. The clinical response consisted of a decrease in the dorsal pain. The D{sub max} for the spinal cord was reduced from 55 Gy (3D-radiotherapy [RT]) (which would be an unacceptable dose to the spine because of the risk of myelopathy) to 42.8 Gy (VMAT), which remains below the recommended dose threshold (45 Gy). The dose delivered to 20% of organ volume (D{sub 20}) was reduced from 47 Gy (3D-RT) to 3 Gy (VMAT) for the spinal cord. The study shows that VMAT allows the delivery of curative treatment for vertebral EHEs because of critical organ sparing.

  10. VOLUMETRIC LEAK DETECTION IN LARGE UNDERGROUND STORAGE TANKS - VOLUME I

    Science.gov (United States)

    A set of experiments was conducted to determine whether volumetric leak detection system presently used to test underground storage tanks (USTs) up to 38,000 L (10,000 gal) in capacity could meet EPA's regulatory standards for tank tightness and automatic tank gauging systems whe...

  11. Tandem Gravimetric and Volumetric Apparatus for Methane Sorption Measurements

    Science.gov (United States)

    Burress, Jacob; Bethea, Donald

    Concerns about global climate change have driven the search for alternative fuels. Natural gas (NG, methane) is a cleaner fuel than gasoline and abundantly available due to hydraulic fracturing. One hurdle to the adoption of NG vehicles is the bulky cylindrical storage vessels needed to store the NG at high pressures (3600 psi, 250 bar). The adsorption of methane in microporous materials can store large amounts of methane at low enough pressures for the allowance of conformable, ``flat'' pressure vessels. The measurement of the amount of gas stored in sorbent materials is typically done by measuring pressure differences (volumetric, manometric) or masses (gravimetric). Volumetric instruments of the Sievert type have uncertainties that compound with each additional measurement. Therefore, the highest-pressure measurement has the largest uncertainty. Gravimetric instruments don't have that drawback, but can have issues with buoyancy corrections. An instrument will be presented with which methane adsorption measurements can be performed using both volumetric and gravimetric methods in tandem. The gravimetric method presented has no buoyancy corrections and low uncertainty. Therefore, the gravimetric measurements can be performed throughout an entire isotherm or just at the extrema to verify the results from the volumetric measurements. Results from methane sorption measurements on an activated carbon (MSC-30) and a metal-organic framework (Cu-BTC, HKUST-1, MOF-199) will be shown. New recommendations for calculations of gas uptake and uncertainty measurements will be discussed.

  12. 100KE/KW fuel storage basin surface volumetric factors

    International Nuclear Information System (INIS)

    Conn, K.R.

    1996-01-01

    This Supporting Document presents calculations of surface Volumetric factors for the 100KE and 100KW Fuel Storage Basins. These factors relate water level changes to basin loss or additions of water, or the equivalent water displacement volumes of objects added to or removed from the basin

  13. Designing remote web-based mechanical-volumetric flow meter ...

    African Journals Online (AJOL)

    Today, in water and wastewater industry a lot of mechanical-volumetric flow meters are used for the navigation of the produced water and the data of these flow meters, due to use in a wide geographical range, is done physically and by in person presence. All this makes reading the data costly and, in some cases, due to ...

  14. Probabilistic Output Analysis by Program Manipulation

    DEFF Research Database (Denmark)

    Rosendahl, Mads; Kirkeby, Maja Hanne

    2015-01-01

    The aim of a probabilistic output analysis is to derive a probability distribution of possible output values for a program from a probability distribution of its input. We present a method for performing static output analysis, based on program transformation techniques. It generates a probability...

  15. Comparative Study of the Volumetric Methods Calculation Using GNSS Measurements

    Science.gov (United States)

    Şmuleac, Adrian; Nemeş, Iacob; Alina Creţan, Ioana; Sorina Nemeş, Nicoleta; Şmuleac, Laura

    2017-10-01

    This paper aims to achieve volumetric calculations for different mineral aggregates using different methods of analysis and also comparison of results. To achieve these comparative studies and presentation were chosen two software licensed, namely TopoLT 11.2 and Surfer 13. TopoLT program is a program dedicated to the development of topographic and cadastral plans. 3D terrain model, level courves and calculation of cut and fill volumes, including georeferencing of images. The program Surfer 13 is produced by Golden Software, in 1983 and is active mainly used in various fields such as agriculture, construction, geophysical, geotechnical engineering, GIS, water resources and others. It is also able to achieve GRID terrain model, to achieve the density maps using the method of isolines, volumetric calculations, 3D maps. Also, it can read different file types, including SHP, DXF and XLSX. In these paper it is presented a comparison in terms of achieving volumetric calculations using TopoLT program by two methods: a method where we choose a 3D model both for surface as well as below the top surface and a 3D model in which we choose a 3D terrain model for the bottom surface and another 3D model for the top surface. The comparison of the two variants will be made with data obtained from the realization of volumetric calculations with the program Surfer 13 generating GRID terrain model. The topographical measurements were performed with equipment from Leica GPS 1200 Series. Measurements were made using Romanian position determination system - ROMPOS which ensures accurate positioning of reference and coordinates ETRS through the National Network of GNSS Permanent Stations. GPS data processing was performed with the program Leica Geo Combined Office. For the volumetric calculating the GPS used point are in 1970 stereographic projection system and for the altitude the reference is 1975 the Black Sea projection system.

  16. Model output: fact or artefact?

    Science.gov (United States)

    Melsen, Lieke

    2015-04-01

    As a third-year PhD-student, I relatively recently entered the wonderful world of scientific Hydrology. A science that has many pillars that directly impact society, for example with the prediction of hydrological extremes (both floods and drought), climate change, applications in agriculture, nature conservation, drinking water supply, etcetera. Despite its demonstrable societal relevance, hydrology is often seen as a science between two stools. Like Klemeš (1986) stated: "By their academic background, hydrologists are foresters, geographers, electrical engineers, geologists, system analysts, physicists, mathematicians, botanists, and most often civil engineers." Sometimes it seems that the engineering genes are still present in current hydrological sciences, and this results in pragmatic rather than scientific approaches for some of the current problems and challenges we have in hydrology. Here, I refer to the uncertainty in hydrological modelling that is often neglected. For over thirty years, uncertainty in hydrological models has been extensively discussed and studied. But it is not difficult to find peer-reviewed articles in which it is implicitly assumed that model simulations represent the truth rather than a conceptualization of reality. For instance in trend studies, where data is extrapolated 100 years ahead. Of course one can use different forcing datasets to estimate the uncertainty of the input data, but how to prevent that the output is not a model artefact, caused by the model structure? Or how about impact studies, e.g. of a dam impacting river flow. Measurements are often available for the period after dam construction, so models are used to simulate river flow before dam construction. Both are compared in order to qualify the effect of the dam. But on what basis can we tell that the model tells us the truth? Model validation is common nowadays, but validation only (comparing observations with model output) is not sufficient to assume that a

  17. Canada's helium output rising fast

    Energy Technology Data Exchange (ETDEWEB)

    1966-12-01

    About 12 months from now, International Helium Limited will be almost ready to start up Canada's second helium extraction plant at Mankota, in Saskatchewan's Wood Mountain area about 100 miles southwest of Moose Jaw. Another 80 miles north is Saskatchewan's (and Canada's) first helium plant, operated by Canadian Helium and sitting on a gas deposit at Wilhelm, 9 miles north of Swift Current. It contains almost 2% helium, some COD2U, and the rest nitrogen. One year in production was apparently enough to convince Canadian Helium that the export market (it sells most of its helium in W. Europe) can take a lot more than it's getting. Construction began this summer on an addition to the Swift Current plant that will raise its capacity from 12 to 36MMcf per yr when it goes on stream next spring. Six months later, International Helium's 40 MMcf per yr plant to be located about 4 miles from its 2 Wood Mountain wells will double Canada's helium output again.

  18. Synchronous prostate and rectal adenocarcinomas irradiation utilising volumetric modulated arc therapy.

    Science.gov (United States)

    Ng, Sweet Ping; Tran, Thu; Moloney, Philip; Sale, Charlotte; Mathlum, Maitham; Ong, Grace; Lynch, Rod

    2015-12-01

    Cases of synchronous prostate and colorectal adenocarcinomas have been sporadically reported. There are case reports on patients with synchronous prostate and rectal cancers treated with external beam radiotherapy alone or combined with high-dose rate brachytherapy boost to the prostate. Here, we illustrate a patient with synchronous prostate and rectal cancers treated using the volumetric arc therapy (VMAT) technique. The patient was treated with radical radiotherapy to 50.4 Gy in 28 fractions to the pelvis, incorporating the involved internal iliac node and the prostate. A boost of 24 Gy in 12 fractions was delivered to the prostate only, using VMAT. Treatment-related toxicities and follow-up prostate-specific antigen and carcinoembryonic antigen were collected for data analysis. At 12 months, the patient achieved complete response for both rectal and prostate cancers without significant treatment-related toxicities.

  19. Output calibration in solid water for high energy photon beams

    International Nuclear Information System (INIS)

    Reft, C.S.

    1989-01-01

    The AAPM Protocol recommends the use of water, polystyrene or acrylic media for measuring the output of high energy photon beams. It provides the appropriate restricted mass stopping powers and mass energy absorption coefficients for converting the dose to these media to dose to water. A water-equivalent solid has been developed for dosimetric applications. [C. Constantinou, F. Attix, and B. Paliwal, Med. Phys. 9, 436 (1982)]. Calculated values for the restricted mass stopping powers and mass energy absorption coefficients have been published for this material. [A. Ho and B. Paliwal, Med. Phys. 13, 403 (1986)]. The accuracy of these calculations was investigated by making output measurements, following the Protocol, with a Farmer type chamber in four materials for Co-60, 4, 6, 10, 18, and 24 MV photon beams. The results show that the scaled dose to water for the different media agree to better than 1%, and the analysis supports the methodology of the Protocol for obtaining the dose to water from the different media

  20. Dose volume assessment of high dose rate 192IR endobronchial implants

    International Nuclear Information System (INIS)

    Cheng, B. Saw; Korb, Leroy J.; Pawlicki, Todd; Wu, Andrew

    1996-01-01

    Purpose: To study the dose distributions of high dose rate (HDR) endobronchial implants using the dose nonuniformity ratio (DNR) and three volumetric irradiation indices. Methods and Materials: Multiple implants were configured by allowing a single HDR 192 Ir source to step through a length of 6 cm along an endobronchial catheter. Dwell times were computed to deliver a dose of 5 Gy to points 1 cm away from the catheter axis. Five sets of source configurations, each with different dwell position spacings from 0.5 to 3.0 cm, were evaluated. Three-dimensional (3D) dose distributions were then generated for each source configuration. Differential and cumulative dose-volume curves were generated to quantify the degree of target volume coverage, dose nonuniformity within the target volume, and irradiation of tissues outside the target volume. Evaluation of the implants were made using the DNR and three volumetric irradiation indices. Results: The observed isodose distributions were not able to satisfy all the dose constraints. The ability to optimally satisfy the dose constraints depended on the choice of dwell position spacing and the specification of the dose constraint points. The DNR and irradiation indices suggest that small dwell position spacing does not result in a more homogeneous dose distribution for the implant. This study supports the existence of a relationship between the dwell position spacing and the distance from the catheter axis to the reference dose or dose constraint points. Better dose homogeneity for an implant can be obtained if the spacing of the dwell positions are about twice the distance from the catheter axis to the reference dose or dose constraint points

  1. Retrospective evaluation of dosimetric quality for prostate carcinomas treated with 3D conformal, intensity modulated and volumetric modulated arc radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Crowe, Scott B [Science and Engineering Faculty, Queensland University of Technology, Brisbane, Queensland (Australia); Kairn, Tanya [Science and Engineering Faculty, Queensland University of Technology, Brisbane, Queensland (Australia); Premion, Wesley Medical Centre, Brisbane, Queensland (Australia); Middlebrook, Nigel; Hill, Brendan; Christie, David R H; Knight, Richard T [Premion, Wesley Medical Centre, Brisbane, Queensland (Australia); Kenny, John [Australian Clinical Dosimetry Services, Australian Radiation Protection and Nuclear Safety Agency, Melbourne, Victoria (Australia); Langton, Christian M; Trapp, Jamie V [Science and Engineering Faculty, Queensland University of Technology, Brisbane, Queensland (Australia)

    2013-12-15

    This study examines and compares the dosimetric quality of radiotherapy treatment plans for prostate carcinoma across a cohort of 163 patients treated across five centres: 83 treated with three-dimensional conformal radiotherapy (3DCRT), 33 treated with intensity modulated radiotherapy (IMRT) and 47 treated with volumetric modulated arc therapy (VMAT). Treatment plan quality was evaluated in terms of target dose homogeneity and organs at risk (OAR), through the use of a set of dose metrics. These included the mean, maximum and minimum doses; the homogeneity and conformity indices for the target volumes; and a selection of dose coverage values that were relevant to each OAR. Statistical significance was evaluated using two-tailed Welch's T-tests. The Monte Carlo DICOM ToolKit software was adapted to permit the evaluation of dose metrics from DICOM data exported from a commercial radiotherapy treatment planning system. The 3DCRT treatment plans offered greater planning target volume dose homogeneity than the other two treatment modalities. The IMRT and VMAT plans offered greater dose reduction in the OAR: with increased compliance with recommended OAR dose constraints, compared to conventional 3DCRT treatments. When compared to each other, IMRT and VMAT did not provide significantly different treatment plan quality for like-sized tumour volumes. This study indicates that IMRT and VMAT have provided similar dosimetric quality, which is superior to the dosimetric quality achieved with 3DCRT.

  2. Applicator-guided volumetric-modulated arc therapy for low-risk endometrial cancer

    Energy Technology Data Exchange (ETDEWEB)

    Cilla, Savino, E-mail: savinocilla@gmail.com [Medical Physics Unit, Fondazione di ricerca e cura “Giovanni Paolo II,” Università Cattolica del Sacro Cuore, Campobasso (Italy); Macchia, Gabriella [Radiation Oncology Unit, Fondazione di ricerca e cura “Giovanni Paolo II,” Università Cattolica del Sacro Cuore, Campobasso (Italy); Sabatino, Domenico [Medical Physics Unit, Fondazione di ricerca e cura “Giovanni Paolo II,” Università Cattolica del Sacro Cuore, Campobasso (Italy); Digesù, Cinzia; Deodato, Francesco [Radiation Oncology Unit, Fondazione di ricerca e cura “Giovanni Paolo II,” Università Cattolica del Sacro Cuore, Campobasso (Italy); Piermattei, Angelo [Physics Institute, Università Cattolica del Sacro Cuore, Rome (Italy); De Spirito, Marco [Medical Physics Unit, Fondazione di ricerca e cura “Giovanni Paolo II,” Università Cattolica del Sacro Cuore, Campobasso (Italy); Morganti, Alessio G. [Radiation Oncology Unit, Fondazione di ricerca e cura “Giovanni Paolo II,” Università Cattolica del Sacro Cuore, Campobasso (Italy); Radiation Oncology Unit, Università Cattolica del Sacro Cuore, Rome (Italy)

    2013-04-01

    The aim of this study was to report the feasibility of volumetric-modulated arc therapy (VMAT) in the postoperative irradiation of the vaginal vault. Moreover, the VMAT technique was compared with 3D conformal radiotherapy (3D-CRT) and fixed-field intensity-modulated radiotherapy (IMRT), in terms of target coverage and organs at risk sparing. The number of monitor units and the delivery time were analyzed to score the treatment efficiency. All plans were verified in a dedicated solid water phantom using a 2D array of ionization chambers. Twelve patients with endometrial carcinoma who underwent radical hystero-adenexectomy and fixed-field IMRT treatments were retrospectively included in this analysis; for each patient, plans were compared in terms of dose-volume histograms, homogeneity index, and conformity indexes. All techniques met the prescription goal for planning target volume coverage, with VMAT showing the highest level of conformity at all dose levels. VMAT resulted in significant reduction of rectal and bladder volumes irradiated at all dose levels compared with 3D-CRT. No significant differences were found with respect to IMRT. Moreover, a significant improvement of the dose conformity was reached by VMAT technique not only at the 95% dose level (0.74 vs. 0.67 and 0.62) but also at 50% and 75% levels of dose prescription. In addition, VMAT plans showed a significant reduction of monitor units by nearly 28% with respect to IMRT, and reduced treatment time from 11 to <3 minutes for a single 6-Gy fraction. In conclusion, VMAT plans can be planned and carried out with high quality and efficiency for the irradiation of vaginal vault alone, providing similar or better sparing of organs at risk to fixed-field IMRT and resulting in the most efficient treatment option. VMAT is currently our standard approach for radiotherapy of low-risk endometrial cancer.

  3. Development of an online radiology case review system featuring interactive navigation of volumetric image datasets using advanced visualization techniques

    International Nuclear Information System (INIS)

    Yang, Hyun Kyung; Kim, Boh Kyoung; Jung, Ju Hyun; Kang, Heung Sik; Lee, Kyoung Ho; Woo, Hyun Soo; Jo, Jae Min; Lee, Min Hee

    2015-01-01

    To develop an online radiology case review system that allows interactive navigation of volumetric image datasets using advanced visualization techniques. Our Institutional Review Board approved the use of the patient data and waived the need for informed consent. We determined the following system requirements: volumetric navigation, accessibility, scalability, undemanding case management, trainee encouragement, and simulation of a busy practice. The system comprised a case registry server, client case review program, and commercially available cloud-based image viewing system. In the pilot test, we used 30 cases of low-dose abdomen computed tomography for the diagnosis of acute appendicitis. In each case, a trainee was required to navigate through the images and submit answers to the case questions. The trainee was then given the correct answers and key images, as well as the image dataset with annotations on the appendix. After evaluation of all cases, the system displayed the diagnostic accuracy and average review time, and the trainee was asked to reassess the failed cases. The pilot system was deployed successfully in a hands-on workshop course. We developed an online radiology case review system that allows interactive navigation of volumetric image datasets using advanced visualization techniques

  4. Development of an online radiology case review system featuring interactive navigation of volumetric image datasets using advanced visualization techniques

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Hyun Kyung; Kim, Boh Kyoung; Jung, Ju Hyun; Kang, Heung Sik; Lee, Kyoung Ho [Dept. of Radiology, Seoul National University Bundang Hospital, Seongnam (Korea, Republic of); Woo, Hyun Soo [Dept. of Radiology, SMG-SNU Boramae Medical Center, Seoul (Korea, Republic of); Jo, Jae Min [Dept. of Computer Science and Engineering, Seoul National University, Seoul (Korea, Republic of); Lee, Min Hee [Dept. of Radiology, Soonchunhyang University Bucheon Hospital, Bucheon (Korea, Republic of)

    2015-11-15

    To develop an online radiology case review system that allows interactive navigation of volumetric image datasets using advanced visualization techniques. Our Institutional Review Board approved the use of the patient data and waived the need for informed consent. We determined the following system requirements: volumetric navigation, accessibility, scalability, undemanding case management, trainee encouragement, and simulation of a busy practice. The system comprised a case registry server, client case review program, and commercially available cloud-based image viewing system. In the pilot test, we used 30 cases of low-dose abdomen computed tomography for the diagnosis of acute appendicitis. In each case, a trainee was required to navigate through the images and submit answers to the case questions. The trainee was then given the correct answers and key images, as well as the image dataset with annotations on the appendix. After evaluation of all cases, the system displayed the diagnostic accuracy and average review time, and the trainee was asked to reassess the failed cases. The pilot system was deployed successfully in a hands-on workshop course. We developed an online radiology case review system that allows interactive navigation of volumetric image datasets using advanced visualization techniques.

  5. A three-dimensional reconstruction algorithm for an inverse-geometry volumetric CT system

    International Nuclear Information System (INIS)

    Schmidt, Taly Gilat; Fahrig, Rebecca; Pelc, Norbert J.

    2005-01-01

    An inverse-geometry volumetric computed tomography (IGCT) system has been proposed capable of rapidly acquiring sufficient data to reconstruct a thick volume in one circular scan. The system uses a large-area scanned source opposite a smaller detector. The source and detector have the same extent in the axial, or slice, direction, thus providing sufficient volumetric sampling and avoiding cone-beam artifacts. This paper describes a reconstruction algorithm for the IGCT system. The algorithm first rebins the acquired data into two-dimensional (2D) parallel-ray projections at multiple tilt and azimuthal angles, followed by a 3D filtered backprojection. The rebinning step is performed by gridding the data onto a Cartesian grid in a 4D projection space. We present a new method for correcting the gridding error caused by the finite and asymmetric sampling in the neighborhood of each output grid point in the projection space. The reconstruction algorithm was implemented and tested on simulated IGCT data. Results show that the gridding correction reduces the gridding errors to below one Hounsfield unit. With this correction, the reconstruction algorithm does not introduce significant artifacts or blurring when compared to images reconstructed from simulated 2D parallel-ray projections. We also present an investigation of the noise behavior of the method which verifies that the proposed reconstruction algorithm utilizes cross-plane rays as efficiently as in-plane rays and can provide noise comparable to an in-plane parallel-ray geometry for the same number of photons. Simulations of a resolution test pattern and the modulation transfer function demonstrate that the IGCT system, using the proposed algorithm, is capable of 0.4 mm isotropic resolution. The successful implementation of the reconstruction algorithm is an important step in establishing feasibility of the IGCT system

  6. PREVIMER : Meteorological inputs and outputs

    Science.gov (United States)

    Ravenel, H.; Lecornu, F.; Kerléguer, L.

    2009-09-01

    PREVIMER is a pre-operational system aiming to provide a wide range of users, from private individuals to professionals, with short-term forecasts about the coastal environment along the French coastlines bordering the English Channel, the Atlantic Ocean, and the Mediterranean Sea. Observation data and digital modelling tools first provide 48-hour (probably 96-hour by summer 2009) forecasts of sea states, currents, sea water levels and temperatures. The follow-up of an increasing number of biological parameters will, in time, complete this overview of coastal environment. Working in partnership with the French Naval Hydrographic and Oceanographic Service (Service Hydrographique et Océanographique de la Marine, SHOM), the French National Weather Service (Météo-France), the French public science and technology research institute (Institut de Recherche pour le Développement, IRD), the European Institute of Marine Studies (Institut Universitaire Européen de la Mer, IUEM) and many others, IFREMER (the French public institute fo marine research) is supplying the technologies needed to ensure this pertinent information, available daily on Internet at http://www.previmer.org, and stored at the Operational Coastal Oceanographic Data Centre. Since 2006, PREVIMER publishes the results of demonstrators assigned to limited geographic areas and to specific applications. This system remains experimental. The following topics are covered : Hydrodynamic circulation, sea states, follow-up of passive tracers, conservative or non-conservative (specifically of microbiological origin), biogeochemical state, primary production. Lastly, PREVIMER provides researchers and R&D departments with modelling tools and access to the database, in which the observation data and the modelling results are stored, to undertake environmental studies on new sites. The communication will focus on meteorological inputs to and outputs from PREVIMER. It will draw the lessons from almost 3 years during

  7. The 'icon' of output efficiency

    International Nuclear Information System (INIS)

    Bligh, L.N.; Evans, S.G.; Larcos, G.; Gruenewald, S.M.

    1999-01-01

    Full text: Output efficiency (OE) is a well-validated parameter used in the assessment of hydronephrosis. Current analysis on Microdelta appears to produce few low OE values and occasional inability to produce a result. We sought an OE program which gave a reliable response over the full range of values. The aims of this study were to determine: (1) whether OE results are comparable between two computer systems; (2) a normal range for OE on an ICON; (3) inter-observer reproducibility; and (4) the correlation between the two programs and the residual cortical activity ratio (RCA), an index which assesses tracer washout from the 20 min cortical activity/peak cortical activity. Accordingly, two blinded medical radiation scientists reviewed 41 kidneys (26 native, 15 transplant) and calculated OE for each kidney on the ICON and Microdelta computers The OE on the Microdelta and the ICON had good correspondence (r = 0.6%, SEE = 6.2). The extrapolated normal range for ICON OE was 69-92% (mean 80.9%). The inter-observer reproducibility on the ICON was excellent with a CV of 8.7%. ICON OE and RCA had a strong correlation (r = - 0.77, SEE = 0.09), compared with a weaker correlation for the Microdelta (r = 0.47, SEE = 0.13). Processing on the ICON was almost half that of the Microdelta at 4 min compared with 7 min. We conclude that OE generated by these computer programs has good correlation, an established normal range, excellent interobserver reproducibility, but differing correlation with RCA. The response of the ICON program to low ranges of OE is being investigated further

  8. Volumetric modulated arc therapy for spine SBRT patients to reduce treatment time and intrafractional motion

    Directory of Open Access Journals (Sweden)

    Ahmad Amoush

    2015-01-01

    Full Text Available Volumetric modulated arc therapy (VMAT is an efficient technique to reduce the treatment time and intrafractional motion to treat spine patients presented with severe back pain. Five patients treated with spine stereotactic body radiation therapy (SBRT using 9 beams intensity modulated radiation therapy (IMRT were retrospectively selected for this study. The patients were replanned using two arcs VMAT technique. The average mean dose was 104% ± 1.2% and 104.1% ± 1.0% in IMRT and VMAT, respectively (p = 0.9. Accordingly, the average conformal index (CI was 1.3 ± 0.1 and 1.5 ± 0.3, respectively (p = 0.5. The average dose gradient (DG distance was 1.5 ± 0.1 cm and 1.4 ± 0.1 cm, respectively (p = 0.3. The average spinal cord maximum dose was 11.6 ± 1.0 Gy and 11.8 ± 1.1 Gy (p = 0.8 and V10Gy was 7.4 ± 1.4 cc and 8.6 ± 1.7 cc (p = 0.4 for IMRT and VMAT, respectively. Accordingly, the average number of monitor units (MUs was 6771.7 ± 1323.3 MU and 3978 ± 576.7 MU respectively (p = 0.02. The use of VMAT for spine SBRT patients with severe back pain can reduce the treatment time and intrafractional motion.

  9. Volumetric Modulated Arc (Radio Therapy in Pets Treatment: The “La Cittadina Fondazione” Experience

    Directory of Open Access Journals (Sweden)

    Mario Dolera

    2018-01-01

    Full Text Available Volumetric Modulated Arc Therapy (VMAT is a modern technique, widely used in human radiotherapy, which allows a high dose to be delivered to tumor volumes and low doses to the surrounding organs at risk (OAR. Veterinary clinics takes advantage of this feature due to the small target volumes and distances between the target and the OAR. Sparing the OAR permits dose escalation, and hypofractionation regimens reduce the number of treatment sessions with a simpler manageability in the veterinary field. Multimodal volumes definition is mandatory for the small volumes involved and a positioning device precisely reproducible with a setup confirmation is needed before each session for avoiding missing the target. Additionally, the elaborate treatment plan must pursue hard constraints and objectives, and its feasibility must be evaluated with a per patient quality control. The aim of this work is to report results with regard to brain meningiomas and gliomas, trigeminal nerve tumors, brachial plexus tumors, adrenal tumors with vascular invasion and rabbit thymomas, in comparison with literature to determine if VMAT is a safe and viable alternative to surgery or chemotherapy alone, or as an adjuvant therapy in pets.

  10. High volumetric power density, non-enzymatic, glucose fuel cells.

    Science.gov (United States)

    Oncescu, Vlad; Erickson, David

    2013-01-01

    The development of new implantable medical devices has been limited in the past by slow advances in lithium battery technology. Non-enzymatic glucose fuel cells are promising replacement candidates for lithium batteries because of good long-term stability and adequate power density. The devices developed to date however use an "oxygen depletion design" whereby the electrodes are stacked on top of each other leading to low volumetric power density and complicated fabrication protocols. Here we have developed a novel single-layer fuel cell with good performance (2 μW cm⁻²) and stability that can be integrated directly as a coating layer on large implantable devices, or stacked to obtain a high volumetric power density (over 16 μW cm⁻³). This represents the first demonstration of a low volume non-enzymatic fuel cell stack with high power density, greatly increasing the range of applications for non-enzymatic glucose fuel cells.

  11. COMPARISON OF VOLUMETRIC REGISTRATION ALGORITHMS FOR TENSOR-BASED MORPHOMETRY.

    Science.gov (United States)

    Villalon, Julio; Joshi, Anand A; Toga, Arthur W; Thompson, Paul M

    2011-01-01

    Nonlinear registration of brain MRI scans is often used to quantify morphological differences associated with disease or genetic factors. Recently, surface-guided fully 3D volumetric registrations have been developed that combine intensity-guided volume registrations with cortical surface constraints. In this paper, we compare one such algorithm to two popular high-dimensional volumetric registration methods: large-deformation viscous fluid registration, formulated in a Riemannian framework, and the diffeomorphic "Demons" algorithm. We performed an objective morphometric comparison, by using a large MRI dataset from 340 young adult twin subjects to examine 3D patterns of correlations in anatomical volumes. Surface-constrained volume registration gave greater effect sizes for detecting morphometric associations near the cortex, while the other two approaches gave greater effects sizes subcortically. These findings suggest novel ways to combine the advantages of multiple methods in the future.

  12. Volumetric properties of ammonium nitrate in N,N-dimethylformamide

    International Nuclear Information System (INIS)

    Vranes, Milan; Dozic, Sanja; Djeric, Vesna; Gadzuric, Slobodan

    2012-01-01

    Highlights: ► We observed interactions and changes in the solution using volumetric properties. ► The greatest influence on the solvent–solvent interactions has temperature. ► The smallest influence temperature has on the ion–ion interactions. ► Temperature has no influence on concentrated systems and partially solvated melts. - Abstract: The densities of the ammonium nitrate in N,N-dimethylformamide (DMF) mixtures were measured at T = (308.15 to 348.15) K for different ammonium nitrate molalities in the range from (0 to 6.8404) mol·kg −1 . From the obtained density data, volumetric properties (apparent molar volumes and partial molar volumes) have been evaluated and discussed in the term of respective ionic and dipole interactions. From the apparent molar volume, determined at various temperatures, the apparent molar expansibility and the coefficients of thermal expansion were also calculated.

  13. Reference volumetric samples of gamma-spectroscopic sources

    International Nuclear Information System (INIS)

    Taskaev, E.; Taskaeva, M.; Grigorov, T.

    1993-01-01

    The purpose of this investigation is to determine the requirements for matrices of reference volumetric radiation sources necessary for detector calibration. The first stage of this determination consists in analysing some available organic and nonorganic materials. Different sorts of food, grass, plastics, minerals and building materials have been considered, taking into account the various procedures of their processing (grinding, screening, homogenizing) and their properties (hygroscopy, storage life, resistance to oxidation during gamma sterilization). The procedures of source processing, sample preparation, matrix irradiation and homogenization have been determined. A rotation homogenizing device has been elaborated enabling to homogenize the matrix activity irrespective of the vessel geometry. 33 standard volumetric radioactive sources have been prepared: 14 - on organic matrix and 19 - on nonorganic matrix. (author)

  14. Determination of uranium by a gravimetric-volumetric titration method

    International Nuclear Information System (INIS)

    Krtil, J.

    1998-01-01

    A volumetric-gravimetric modification of a method for the determination of uranium based on the reduction of uranium to U (IV) in a phosphoric acid medium and titration with a standard potassium dichromate solution is described. More than 99% of the stoichiometric amount of the titrating solution is weighed and the remainder is added volumetrically by using the Mettler DL 40 RC Memotitrator. Computer interconnected with analytical balances collects continually the data on the analyzed samples and evaluates the results of determination. The method allows to determine uranium in samples of uranium metal, alloys, oxides, and ammonium diuranate by using aliquot portions containing 30 - 100 mg of uranium with the error of determination, expressed as the relative standard deviation, of 0.02 - 0.05%. (author)

  15. Two-dimensional random arrays for real time volumetric imaging

    DEFF Research Database (Denmark)

    Davidsen, Richard E.; Jensen, Jørgen Arendt; Smith, Stephen W.

    1994-01-01

    real time volumetric imaging system, which employs a wide transmit beam and receive mode parallel processing to increase image frame rate. Depth-of-field comparisons were made from simulated on-axis and off-axis beamplots at ranges from 30 to 160 mm for both coaxial and offset transmit and receive......Two-dimensional arrays are necessary for a variety of ultrasonic imaging techniques, including elevation focusing, 2-D phase aberration correction, and real time volumetric imaging. In order to reduce system cost and complexity, sparse 2-D arrays have been considered with element geometries...... selected ad hoc, by algorithm, or by random process. Two random sparse array geometries and a sparse array with a Mills cross receive pattern were simulated and compared to a fully sampled aperture with the same overall dimensions. The sparse arrays were designed to the constraints of the Duke University...

  16. Volumetric determination of tumor size abdominal masses. Problems -feasabilities

    International Nuclear Information System (INIS)

    Helmberger, H.; Bautz, W.; Sendler, A.; Fink, U.; Gerhardt, P.

    1995-01-01

    The most important indication for clinically reliable volumetric determination of tumor size in the abdominal region is monitoring liver metastases during chemotherapy. Determination of volume can be effectively realized using 3D reconstruction. Therefore, the primary data set must be complete and contiguous. The mass should be depicted strongly enhanced and free of artifacts. At present, this prerequisite can only be complied with using thin-slice spiral CT. Phantom studies have proven that a semiautomatic reconstruction algorithm is recommendable. The basic difficulties involved in volumetric determination of tumor size are the problems in differentiating active malignant mass and changes in the surrounding tissue, as well as the lack of histomorphological correlation. Possible indications for volumetry of gastrointestinal masses in the assessment of neoadjuvant therapeutic concepts are under scientific evaluation. (orig./MG) [de

  17. CO2 Capacity Sorbent Analysis Using Volumetric Measurement Approach

    Science.gov (United States)

    Huang, Roger; Richardson, Tra-My Justine; Belancik, Grace; Jan, Darrell; Knox, Jim

    2017-01-01

    In support of air revitalization system sorbent selection for future space missions, Ames Research Center (ARC) has performed CO2 capacity tests on various solid sorbents to complement structural strength tests conducted at Marshall Space Flight Center (MSFC). The materials of interest are: Grace Davison Grade 544 13X, Honeywell UOP APG III, LiLSX VSA-10, BASF 13X, and Grace Davison Grade 522 5A. CO2 capacity was for all sorbent materials using a Micromeritics ASAP 2020 Physisorption Volumetric Analysis machine to produce 0C, 10C, 25C, 50C, and 75C isotherms. These data are to be used for modeling data and to provide a basis for continued sorbent research. The volumetric analysis method proved to be effective in generating consistent and repeatable data for the 13X sorbents, but the method needs to be refined to tailor to different sorbents.

  18. Volumetric formulation of lattice Boltzmann models with energy conservation

    OpenAIRE

    Sbragaglia, M.; Sugiyama, K.

    2010-01-01

    We analyze a volumetric formulation of lattice Boltzmann for compressible thermal fluid flows. The velocity set is chosen with the desired accuracy, based on the Gauss-Hermite quadrature procedure, and tested against controlled problems in bounded and unbounded fluids. The method allows the simulation of thermohydrodyamical problems without the need to preserve the exact space-filling nature of the velocity set, but still ensuring the exact conservation laws for density, momentum and energy. ...

  19. Volumetric Real-Time Imaging Using a CMUT Ring Array

    OpenAIRE

    Choe, Jung Woo; Oralkan, Ömer; Nikoozadeh, Amin; Gencel, Mustafa; Stephens, Douglas N.; O’Donnell, Matthew; Sahn, David J.; Khuri-Yakub, Butrus T.

    2012-01-01

    A ring array provides a very suitable geometry for forward-looking volumetric intracardiac and intravascular ultrasound imaging. We fabricated an annular 64-element capacitive micromachined ultrasonic transducer (CMUT) array featuring a 10-MHz operating frequency and a 1.27-mm outer radius. A custom software suite was developed to run on a PC-based imaging system for real-time imaging using this device.

  20. 3-dimensional charge collection efficiency measurements using volumetric tomographic reconstruction

    Energy Technology Data Exchange (ETDEWEB)

    Dobos, Daniel [CERN, Geneva (Switzerland)

    2016-07-01

    For a better understanding of the electrical field distribution of 3D semiconductor detectors and to allow efficiency based design improvements, a method to measure the 3D spatial charge collection efficiency of planar, 3D silicon and diamond sensors using 3D volumetric reconstruction techniques is possible. Simulation results and first measurements demonstrated the feasibility of this method and show that with soon available 10 times faster beam telescopes even small structures and efficiency differences will become measurable in few hours.

  1. Thermodynamic and volumetric databases and software for magnesium alloys

    Science.gov (United States)

    Kang, Youn-Bae; Aliravci, Celil; Spencer, Philip J.; Eriksson, Gunnar; Fuerst, Carlton D.; Chartrand, Patrice; Pelton, Arthur D.

    2009-05-01

    Extensive databases for the thermodynamic and volumetric properties of magnesium alloys have been prepared by critical evaluation, modeling, and optimization of available data. Software has been developed to access the databases to calculate equilibrium phase diagrams, heat effects, etc., and to follow the course of equilibrium or Scheil-Gulliver cooling, calculating not only the amounts of the individual phases, but also of the microstructural constituents.

  2. Volumetric 3D display using a DLP projection engine

    Science.gov (United States)

    Geng, Jason

    2012-03-01

    In this article, we describe a volumetric 3D display system based on the high speed DLPTM (Digital Light Processing) projection engine. Existing two-dimensional (2D) flat screen displays often lead to ambiguity and confusion in high-dimensional data/graphics presentation due to lack of true depth cues. Even with the help of powerful 3D rendering software, three-dimensional (3D) objects displayed on a 2D flat screen may still fail to provide spatial relationship or depth information correctly and effectively. Essentially, 2D displays have to rely upon capability of human brain to piece together a 3D representation from 2D images. Despite the impressive mental capability of human visual system, its visual perception is not reliable if certain depth cues are missing. In contrast, volumetric 3D display technologies to be discussed in this article are capable of displaying 3D volumetric images in true 3D space. Each "voxel" on a 3D image (analogous to a pixel in 2D image) locates physically at the spatial position where it is supposed to be, and emits light from that position toward omni-directions to form a real 3D image in 3D space. Such a volumetric 3D display provides both physiological depth cues and psychological depth cues to human visual system to truthfully perceive 3D objects. It yields a realistic spatial representation of 3D objects and simplifies our understanding to the complexity of 3D objects and spatial relationship among them.

  3. A Hierarchical Volumetric Shadow Algorithm for Single Scattering

    OpenAIRE

    Baran, Ilya; Chen, Jiawen; Ragan-Kelley, Jonathan Millar; Durand, Fredo; Lehtinen, Jaakko

    2010-01-01

    Volumetric effects such as beams of light through participating media are an important component in the appearance of the natural world. Many such effects can be faithfully modeled by a single scattering medium. In the presence of shadows, rendering these effects can be prohibitively expensive: current algorithms are based on ray marching, i.e., integrating the illumination scattered towards the camera along each view ray, modulated by visibility to the light source at each sample. Visibility...

  4. Systematic Parameterization, Storage, and Representation of Volumetric DICOM Data

    OpenAIRE

    Fischer, Felix; Selver, M. Alper; Gezer, Sinem; Dicle, O?uz; Hillen, Walter

    2015-01-01

    Tomographic medical imaging systems produce hundreds to thousands of slices, enabling three-dimensional (3D) analysis. Radiologists process these images through various tools and techniques in order to generate 3D renderings for various applications, such as surgical planning, medical education, and volumetric measurements. To save and store these visualizations, current systems use snapshots or video exporting, which prevents further optimizations and requires the storage of significant addi...

  5. In-Situ Spatial Variability Of Thermal Conductivity And Volumetric ...

    African Journals Online (AJOL)

    Studies of spatial variability of thermal conductivity and volumetric water content of silty topsoil were conduct-ed on a 0.6 ha site at Abeokuta, South-Western Nigeria. The thermal conductivity (k) was measured at depths of up to 0.06 m along four parallel profiles of 200 m long and at an average temperature of 25 C, using ...

  6. Energy and output dynamics in Bangladesh

    International Nuclear Information System (INIS)

    Paul, Biru Paksha; Uddin, Gazi Salah

    2011-01-01

    The relationship between energy consumption and output is still ambiguous in the existing literature. The economy of Bangladesh, having spectacular output growth and rising energy demand as well as energy efficiency in recent decades, can be an ideal case for examining energy-output dynamics. We find that while fluctuations in energy consumption do not affect output fluctuations, movements in output inversely affect movements in energy use. The results of Granger causality tests in this respect are consistent with those of innovative accounting that includes variance decompositions and impulse responses. Autoregressive distributed lag models also suggest a role of output in Bangladesh's energy use. Hence, the findings of this study have policy implications for other developing nations where measures for energy conservation and efficiency can be relevant in policymaking.

  7. Theoretical analysis of magnetic sensor output voltage

    International Nuclear Information System (INIS)

    Liu Haishun; Dun Chaochao; Dou Linming; Yang Weiming

    2011-01-01

    The output voltage is an important parameter to determine the stress state in magnetic stress measurement, the relationship between the output voltage and the difference in the principal stresses was investigated by a comprehensive application of magnetic circuit theory, magnetization theory, stress analysis as well as the law of electromagnetic induction, and a corresponding quantitative equation was derived. It is drawn that the output voltage is proportional to the difference in the principal stresses, and related to the angle between the principal stress and the direction of the sensor. This investigation provides a theoretical basis for the principle stresses measurement by output voltage. - Research highlights: → A comprehensive investigation of magnetic stress signal. → Derived a quantitative equation about output voltage and the principal stresses. → The output voltage is proportional to the difference of the principal stresses. → Provide a theoretical basis for the principle stresses measurement.

  8. Three-dimensional volumetric display by inclined-plane scanning

    Science.gov (United States)

    Miyazaki, Daisuke; Eto, Takuma; Nishimura, Yasuhiro; Matsushita, Kenji

    2003-05-01

    A volumetric display system based on three-dimensional (3-D) scanning that uses an inclined two-dimensional (2-D) image is described. In the volumetric display system a 2-D display unit is placed obliquely in an imaging system into which a rotating mirror is inserted. When the mirror is rotated, the inclined 2-D image is moved laterally. A locus of the moving image can be observed by persistence of vision as a result of the high-speed rotation of the mirror. Inclined cross-sectional images of an object are displayed on the display unit in accordance with the position of the image plane to observe a 3-D image of the object by persistence of vision. Three-dimensional images formed by this display system satisfy all the criteria for stereoscopic vision. We constructed the volumetric display systems using a galvanometer mirror and a vector-scan display unit. In addition, we constructed a real-time 3-D measurement system based on a light section method. Measured 3-D images can be reconstructed in the 3-D display system in real time.

  9. A volumetric three-dimensional digital light photoactivatable dye display

    Science.gov (United States)

    Patel, Shreya K.; Cao, Jian; Lippert, Alexander R.

    2017-07-01

    Volumetric three-dimensional displays offer spatially accurate representations of images with a 360° view, but have been difficult to implement due to complex fabrication requirements. Herein, a chemically enabled volumetric 3D digital light photoactivatable dye display (3D Light PAD) is reported. The operating principle relies on photoactivatable dyes that become reversibly fluorescent upon illumination with ultraviolet light. Proper tuning of kinetics and emission wavelengths enables the generation of a spatial pattern of fluorescent emission at the intersection of two structured light beams. A first-generation 3D Light PAD was fabricated using the photoactivatable dye N-phenyl spirolactam rhodamine B, a commercial picoprojector, an ultraviolet projector and a custom quartz imaging chamber. The system displays a minimum voxel size of 0.68 mm3, 200 μm resolution and good stability over repeated `on-off' cycles. A range of high-resolution 3D images and animations can be projected, setting the foundation for widely accessible volumetric 3D displays.

  10. Volumetric full-range magnetomotive optical coherence tomography

    Science.gov (United States)

    Ahmad, Adeel; Kim, Jongsik; Shemonski, Nathan D.; Marjanovic, Marina; Boppart, Stephen A.

    2014-01-01

    Abstract. Magnetomotive optical coherence tomography (MM-OCT) can be utilized to spatially localize the presence of magnetic particles within tissues or organs. These magnetic particle-containing regions are detected by using the capability of OCT to measure small-scale displacements induced by the activation of an external electromagnet coil typically driven by a harmonic excitation signal. The constraints imposed by the scanning schemes employed and tissue viscoelastic properties limit the speed at which conventional MM-OCT data can be acquired. Realizing that electromagnet coils can be designed to exert MM force on relatively large tissue volumes (comparable or larger than typical OCT imaging fields of view), we show that an order-of-magnitude improvement in three-dimensional (3-D) MM-OCT imaging speed can be achieved by rapid acquisition of a volumetric scan during the activation of the coil. Furthermore, we show volumetric (3-D) MM-OCT imaging over a large imaging depth range by combining this volumetric scan scheme with full-range OCT. Results with tissue equivalent phantoms and a biological tissue are shown to demonstrate this technique. PMID:25472770

  11. Reducing uncertainties in volumetric image based deformable organ registration

    International Nuclear Information System (INIS)

    Liang, J.; Yan, D.

    2003-01-01

    Applying volumetric image feedback in radiotherapy requires image based deformable organ registration. The foundation of this registration is the ability of tracking subvolume displacement in organs of interest. Subvolume displacement can be calculated by applying biomechanics model and the finite element method to human organs manifested on the multiple volumetric images. The calculation accuracy, however, is highly dependent on the determination of the corresponding organ boundary points. Lacking sufficient information for such determination, uncertainties are inevitable--thus diminishing the registration accuracy. In this paper, a method of consuming energy minimization was developed to reduce these uncertainties. Starting from an initial selection of organ boundary point correspondence on volumetric image sets, the subvolume displacement and stress distribution of the whole organ are calculated and the consumed energy due to the subvolume displacements is computed accordingly. The corresponding positions of the initially selected boundary points are then iteratively optimized to minimize the consuming energy under geometry and stress constraints. In this study, a rectal wall delineated from patient CT image was artificially deformed using a computer simulation and utilized to test the optimization. Subvolume displacements calculated based on the optimized boundary point correspondence were compared to the true displacements, and the calculation accuracy was thereby evaluated. Results demonstrate that a significant improvement on the accuracy of the deformable organ registration can be achieved by applying the consuming energy minimization in the organ deformation calculation

  12. Output Control Using Feedforward And Cascade Controllers

    Science.gov (United States)

    Seraji, Homayoun

    1990-01-01

    Report presents theoretical study of open-loop control elements in single-input, single-output linear system. Focus on output-control (servomechanism) problem, in which objective is to find control scheme that causes output to track certain command inputs and to reject certain disturbance inputs in steady state. Report closes with brief discussion of characteristics and relative merits of feedforward, cascade, and feedback controllers and combinations thereof.

  13. Trajectory optimization for dynamic couch rotation during volumetric modulated arc radiotherapy

    Science.gov (United States)

    Smyth, Gregory; Bamber, Jeffrey C.; Evans, Philip M.; Bedford, James L.

    2013-11-01

    Non-coplanar radiation beams are often used in three-dimensional conformal and intensity modulated radiotherapy to reduce dose to organs at risk (OAR) by geometric avoidance. In volumetric modulated arc radiotherapy (VMAT) non-coplanar geometries are generally achieved by applying patient couch rotations to single or multiple full or partial arcs. This paper presents a trajectory optimization method for a non-coplanar technique, dynamic couch rotation during VMAT (DCR-VMAT), which combines ray tracing with a graph search algorithm. Four clinical test cases (partial breast, brain, prostate only, and prostate and pelvic nodes) were used to evaluate the potential OAR sparing for trajectory-optimized DCR-VMAT plans, compared with standard coplanar VMAT. In each case, ray tracing was performed and a cost map reflecting the number of OAR voxels intersected for each potential source position was generated. The least-cost path through the cost map, corresponding to an optimal DCR-VMAT trajectory, was determined using Dijkstra’s algorithm. Results show that trajectory optimization can reduce dose to specified OARs for plans otherwise comparable to conventional coplanar VMAT techniques. For the partial breast case, the mean heart dose was reduced by 53%. In the brain case, the maximum lens doses were reduced by 61% (left) and 77% (right) and the globes by 37% (left) and 40% (right). Bowel mean dose was reduced by 15% in the prostate only case. For the prostate and pelvic nodes case, the bowel V50 Gy and V60 Gy were reduced by 9% and 45% respectively. Future work will involve further development of the algorithm and assessment of its performance over a larger number of cases in site-specific cohorts.

  14. A class solution for volumetric-modulated arc therapy planning in postprostatectomy radiotherapy

    International Nuclear Information System (INIS)

    Forde, Elizabeth; Bromley, Regina; Kneebone, Andrew; Eade, Thomas

    2014-01-01

    This study is aimed to test a postprostatectomy volumetric-modulated arc therapy (VMAT) planning class solution. The solution applies to both the progressive resolution optimizer algorithm version 2 (PRO 2) and the algorithm version 3 (PRO 3), addressing the effect of an upgraded algorithm. A total of 10 radical postprostatectomy patients received 68 Gy to 95% of the planning target volume (PTV), which was planned using VMAT. Each case followed a set of planning instructions; including contouring, field setup, and predetermined optimization parameters. Each case was run through both algorithms only once, with no user interaction. Results were averaged and compared against Radiation Therapy Oncology Group (RTOG) 0534 end points. In addition, the clinical target volume (CTV) D 100 , PTV D 99 , and PTV mean doses were recorded, along with conformity indices (CIs) (95% and 98%) and the homogeneity index. All cases satisfied PTV D 95 of 68 Gy and a maximum dose < 74.8 Gy. The average result for the PTV D 99 was 64.1 Gy for PRO 2 and 62.1 Gy for PRO 3. The average PTV mean dose for PRO 2 was 71.4 Gy and 71.5 Gy for PRO 3. The CTV D 100 average dose was 67.7 and 68.0 Gy for PRO 2 and PRO 3, respectively. The mean homogeneity index for both algorithms was 0.08. The average 95% CI was 1.17 for PRO 2 and 1.19 for PRO 3. For 98%, the average results were 1.08 and 1.12 for PRO 2 and PRO 3, respectively. All cases for each algorithm met the RTOG organs at risk dose constraints. A successful class solution has been established for prostate bed VMAT radiotherapy regardless of the algorithm used

  15. A class solution for volumetric-modulated arc therapy planning in postprostatectomy radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Forde, Elizabeth, E-mail: eforde@tcd.ie [Radiation Oncology Department, Northern Sydney Cancer Centre, St Leonards, New South Wales (Australia); Bromley, Regina [Radiation Oncology Department, Northern Sydney Cancer Centre, St Leonards, New South Wales (Australia); Institute of Medical Physics, School of Physics, University of Sydney, New South Wales (Australia); Kneebone, Andrew; Eade, Thomas [Radiation Oncology Department, Northern Sydney Cancer Centre, St Leonards, New South Wales (Australia); Northern Clinical School, University of Sydney, New South Wales (Australia)

    2014-10-01

    This study is aimed to test a postprostatectomy volumetric-modulated arc therapy (VMAT) planning class solution. The solution applies to both the progressive resolution optimizer algorithm version 2 (PRO 2) and the algorithm version 3 (PRO 3), addressing the effect of an upgraded algorithm. A total of 10 radical postprostatectomy patients received 68 Gy to 95% of the planning target volume (PTV), which was planned using VMAT. Each case followed a set of planning instructions; including contouring, field setup, and predetermined optimization parameters. Each case was run through both algorithms only once, with no user interaction. Results were averaged and compared against Radiation Therapy Oncology Group (RTOG) 0534 end points. In addition, the clinical target volume (CTV) D{sub 100}, PTV D{sub 99}, and PTV mean doses were recorded, along with conformity indices (CIs) (95% and 98%) and the homogeneity index. All cases satisfied PTV D{sub 95} of 68 Gy and a maximum dose < 74.8 Gy. The average result for the PTV D{sub 99} was 64.1 Gy for PRO 2 and 62.1 Gy for PRO 3. The average PTV mean dose for PRO 2 was 71.4 Gy and 71.5 Gy for PRO 3. The CTV D{sub 100} average dose was 67.7 and 68.0 Gy for PRO 2 and PRO 3, respectively. The mean homogeneity index for both algorithms was 0.08. The average 95% CI was 1.17 for PRO 2 and 1.19 for PRO 3. For 98%, the average results were 1.08 and 1.12 for PRO 2 and PRO 3, respectively. All cases for each algorithm met the RTOG organs at risk dose constraints. A successful class solution has been established for prostate bed VMAT radiotherapy regardless of the algorithm used.

  16. The dosimetric impact of dental implants on head-and-neck volumetric modulated arc therapy

    International Nuclear Information System (INIS)

    Lin, Mu-Han; Li Jinsheng; Price, Robert A Jr; Wang Lu; Ma, C-M; Lee, Chung-Chi

    2013-01-01

    This work aims to investigate the dosimetric impact of dental implants on volumetric modulated arc therapy (VMAT) for head-and-neck patients and to evaluate the effectiveness of using the material's electron-density ratio for the correction. An in-house Monte Carlo (MC) code was utilized for the dose calculation to account for the scattering and attenuation caused by the high-Z implant material. Three different dental implant materials were studied in this work: titanium, Degubond®4 and gold. The dose perturbations caused by the dental implant materials were first investigated in a water phantom with a 1 cm 3 insert. The per cent depth dose distributions of a 3 × 3 cm 2 photon field were compared with the insert material as water and the three selected dental implant materials. To evaluate the impact of the dental implant on VMAT patient dose calculation, four head-and-neck cases were selected. For each case, the VMAT plan was designed based on the artifact-corrected patient geometry using a treatment planning system (TPS) that was typically utilized for routine patient treatment. The plans were re-calculated using the MC code for five situations: uncorrected geometry, artifact-corrected geometry and artifact-corrected geometry with one of the three different implant materials. The isodose distributions and the dose–volume histograms were cross-compared with each other. To evaluate the effectiveness of using the material's electron-density ratio for dental implant correction, the implant region was set as water with the material's electron-density ratio and the calculated dose was compared with the MC simulation with the real material. The main effect of the dental implant was the severe attenuation in the downstream. The 1 cm 3 dental implant can lower the downstream dose by 10% (Ti) to 51% (Au) for a 3 × 3 cm 2 field. The TPS failed to account for the dose perturbation if the dental implant material was not precisely defined. For the VMAT patient dose

  17. Radiation Dose–Dependent Hippocampal Atrophy Detected With Longitudinal Volumetric Magnetic Resonance Imaging

    Energy Technology Data Exchange (ETDEWEB)

    Seibert, Tyler M.; Karunamuni, Roshan [Department of Radiation Medicine and Applied Sciences, University of California, San Diego, La Jolla, California (United States); Bartsch, Hauke [Department of Radiology, University of California, San Diego, La Jolla, California (United States); Kaifi, Samar [Department of Radiation Medicine and Applied Sciences, University of California, San Diego, La Jolla, California (United States); Krishnan, Anitha Priya [Department of Radiology, University of California, San Diego, La Jolla, California (United States); Dalia, Yoseph; Burkeen, Jeffrey; Murzin, Vyacheslav; Moiseenko, Vitali [Department of Radiation Medicine and Applied Sciences, University of California, San Diego, La Jolla, California (United States); Kuperman, Joshua; White, Nathan S. [Department of Radiology, University of California, San Diego, La Jolla, California (United States); Brewer, James B. [Department of Radiology, University of California, San Diego, La Jolla, California (United States); Department of Neurosciences, University of California, San Diego, La Jolla, California (United States); Farid, Nikdokht [Department of Radiology, University of California, San Diego, La Jolla, California (United States); McDonald, Carrie R. [Department of Psychiatry, University of California, San Diego, La Jolla, California (United States); Hattangadi-Gluth, Jona A., E-mail: jhattangadi@ucsd.edu [Department of Radiation Medicine and Applied Sciences, University of California, San Diego, La Jolla, California (United States)

    2017-02-01

    Purpose: After radiation therapy (RT) to the brain, patients often experience memory impairment, which may be partially mediated by damage to the hippocampus. Hippocampal sparing in RT planning is the subject of recent and ongoing clinical trials. Calculating appropriate hippocampal dose constraints would be improved by efficient in vivo measurements of hippocampal damage. In this study we sought to determine whether brain RT was associated with dose-dependent hippocampal atrophy. Methods and Materials: Hippocampal volume was measured with magnetic resonance imaging (MRI) in 52 patients who underwent fractionated, partial brain RT for primary brain tumors. Study patients had high-resolution, 3-dimensional volumetric MRI before and 1 year after RT. Images were processed using software with clearance from the US Food and Drug Administration and Conformité Européene marking for automated measurement of hippocampal volume. Automated results were inspected visually for accuracy. Tumor and surgical changes were censored. Mean hippocampal dose was tested for correlation with hippocampal atrophy 1 year after RT. Average hippocampal volume change was also calculated for hippocampi receiving high (>40 Gy) or low (<10 Gy) mean RT dose. A multivariate analysis was conducted with linear mixed-effects modeling to evaluate other potential predictors of hippocampal volume change, including patient (random effect), age, hemisphere, sex, seizure history, and baseline volume. Statistical significance was evaluated at α = 0.05. Results: Mean hippocampal dose was significantly correlated with hippocampal volume loss (r=−0.24, P=.03). Mean hippocampal volume was significantly reduced 1 year after high-dose RT (mean −6%, P=.009) but not after low-dose RT. In multivariate analysis, both RT dose and patient age were significant predictors of hippocampal atrophy (P<.01). Conclusions: The hippocampus demonstrates radiation dose–dependent atrophy after treatment for brain

  18. Validation and uncertainty analysis of a pre-treatment 2D dose prediction model

    Science.gov (United States)

    Baeza, Jose A.; Wolfs, Cecile J. A.; Nijsten, Sebastiaan M. J. J. G.; Verhaegen, Frank

    2018-02-01

    Independent verification of complex treatment delivery with megavolt photon beam radiotherapy (RT) has been effectively used to detect and prevent errors. This work presents the validation and uncertainty analysis of a model that predicts 2D portal dose images (PDIs) without a patient or phantom in the beam. The prediction model is based on an exponential point dose model with separable primary and secondary photon fluence components. The model includes a scatter kernel, off-axis ratio map, transmission values and penumbra kernels for beam-delimiting components. These parameters were derived through a model fitting procedure supplied with point dose and dose profile measurements of radiation fields. The model was validated against a treatment planning system (TPS; Eclipse) and radiochromic film measurements for complex clinical scenarios, including volumetric modulated arc therapy (VMAT). Confidence limits on fitted model parameters were calculated based on simulated measurements. A sensitivity analysis was performed to evaluate the effect of the parameter uncertainties on the model output. For the maximum uncertainty, the maximum deviating measurement sets were propagated through the fitting procedure and the model. The overall uncertainty was assessed using all simulated measurements. The validation of the prediction model against the TPS and the film showed a good agreement, with on average 90.8% and 90.5% of pixels passing a (2%,2 mm) global gamma analysis respectively, with a low dose threshold of 10%. The maximum and overall uncertainty of the model is dependent on the type of clinical plan used as input. The results can be used to study the robustness of the model. A model for predicting accurate 2D pre-treatment PDIs in complex RT scenarios can be used clinically and its uncertainties can be taken into account.

  19. SU-E-T-540: Volumetric Modulated Total Body Irradiation Using a Rotational Lazy Susan-Like Immobilization System

    International Nuclear Information System (INIS)

    Gu, X; Hrycushko, B; Lee, H; Lamphier, R; Jiang, S; Abdulrahman, R; Timmerman, R

    2014-01-01

    Purpose: Traditional extended SSD total body irradiation (TBI) techniques can be problematic in terms of patient comfort and/or dose uniformity. This work aims to develop a comfortable TBI technique that achieves a uniform dose distribution to the total body while reducing the dose to organs at risk for complications. Methods: To maximize patient comfort, a lazy Susan-like couch top immobilization system which rotates about a pivot point was developed. During CT simulation, a patient is immobilized by a Vac-Lok bag within the body frame. The patient is scanned head-first and then feet-first following 180° rotation of the frame. The two scans are imported into the Pinnacle treatment planning system and concatenated to give a full-body CT dataset. Treatment planning matches multiple isocenter volumetric modulated arc (VMAT) fields of the upper body and multiple isocenter parallel-opposed fields of the lower body. VMAT fields of the torso are optimized to satisfy lung dose constraints while achieving a therapeutic dose to the torso. The multiple isocenter VMAT fields are delivered with an indexed couch, followed by body frame rotation about the pivot point to treat the lower body isocenters. The treatment workflow was simulated with a Rando phantom, and the plan was mapped to a solid water slab phantom for point- and film-dose measurements at multiple locations. Results: The treatment plan of 12Gy over 8 fractions achieved 80.2% coverage of the total body volume within ±10% of the prescription dose. The mean lung dose was 8.1 Gy. All ion chamber measurements were within ±1.7% compared to the calculated point doses. All relative film dosimetry showed at least a 98.0% gamma passing rate using a 3mm/3% passing criteria. Conclusion: The proposed patient comfort-oriented TBI technique provides for a uniform dose distribution within the total body while reducing the dose to the lungs

  20. Volumetric tumor burden and its effect on brachial plexus dosimetry in head and neck intensity-modulated radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Romesser, Paul B.; Qureshi, Muhammad M.; Kovalchuk, Nataliya; Truong, Minh Tam, E-mail: mitruong@bu.edu

    2014-07-01

    To determine the effect of gross tumor volume of the primary (GTV-P) and nodal (GTV-N) disease on planned radiation dose to the brachial plexus (BP) in head and neck intensity-modulated radiotherapy (IMRT). Overall, 75 patients underwent definitive IMRT to a median total dose of 69.96 Gy in 33 fractions. The right BP and left BP were prospectively contoured as separate organs at risk. The GTV was related to BP dose using the unpaired t-test. Receiver operating characteristics curves were constructed to determine optimized volumetric thresholds of GTV-P and GTV-N corresponding to a maximum BP dose cutoff of > 66 Gy. Multivariate analyses were performed to account for factors associated with a higher maximal BP dose. A higher maximum BP dose (> 66 vs ≤ 66 Gy) correlated with a greater mean GTV-P (79.5 vs 30.8 cc; p = 0.001) and ipsilateral GTV-N (60.6 vs 19.8 cc; p = 0.014). When dichotomized by the optimized nodal volume, patients with an ipsilateral GTV-N ≥ 4.9 vs < 4.9 cc had a significant difference in maximum BP dose (64.2 vs 59.4 Gy; p = 0.001). Multivariate analysis confirmed that an ipsilateral GTV-N ≥ 4.9 cc was an independent predictor for the BP to receive a maximal dose of > 66 Gy when adjusted individually for BP volume, GTV-P, the use of a low anterior neck field technique, total planned radiation dose, and tumor category. Although both the primary and the nodal tumor volumes affected the BP maximal dose, the ipsilateral nodal tumor volume (GTV-N ≥ 4.9 cc) was an independent predictor for high maximal BP dose constraints in head and neck IMRT.

  1. SU-F-T-446: Improving Craniospinal Irradiation Technique Using Volumetric Modulated Arc Therapy (VMAT) Planning and Its Dosimetric Verification

    Energy Technology Data Exchange (ETDEWEB)

    Yang, X; Tejani, M; Jiang, X; Elder, E; Dhabaan, A [Emory University, Atlanta, GA (United States)

    2016-06-15

    Purpose: The purpose of this study is to investigate a volumetric modulated arc therapy (VMAT) treatment planning technique for supine craniospinal irradiation (CSI). Evaluate the suitability of VMAT for CSI with dosimetric measurements and compare it to 3D conformal planning using specific plan metrics such as dose conformity, homogeneity, and dose of organs at risk (OAR). Methods: Ten CSI patients treated with conventional 3D technique were re-planned with VMAT. The PTV was contoured to include the whole contents of the brain and spinal canal with a uniform margin of 5 mm. VMAT plans were generated with two partial arcs covering the brain, two partial arcs for the superior portion of the spinal cord and two partial arcs covering the remaining inferior portion of the spinal cord. Conformity index (CI), heterogeneity indexes (HI) and max and mean doses of OAR were compared to 3D plans. VMAT plans were delivered onto an anthropomorphic phantom loaded with Gafchromic films and OSLDs placed at specific positions to evaluate the plan dose at the junctions and as well as the plan dose distributions. Results: This VMAT technique was validated with a clinical study of 10 patients. The average CI was 1.03±0.02 for VMAT plans and 1.96±0.32 for conformal plans. And the average HI was 1.15±0.01 for VMAT plans and 1.51±0.21 for conformal plans. The mean and max doses to the all OARs for VMAT plans were significantly lower than conformal plans. The measured dose in phantom for VAMT plans was comparable to the calculated dose in Eclipse and the doses at junctions were verified. Conclusion: VMAT CSI was able to achieve better dose conformity and heterogeneity as well as significantly reducing the dose to Heart, esophagus and larynx. VMAT CSI appears to be a dosimterically advantageous, faster delivery, has better reproducibility CSI treatment.

  2. Constancy of radiation output during diagnostic X-ray exposures

    International Nuclear Information System (INIS)

    Ardran, G.M.; Crooks, H.E.; Birch, R.

    1978-01-01

    Variation in X-ray output and quality during a diagnostic exposure can be undesirable and may result in unnecessary dose to the patient. When significant build-up or decay periods are present errors will arise if factors obtained under steady-state conditions are employed to estimate the exposure. These parameters must be taken into account when calibrating X-ray generators. A variable speed spinning film device and a spectrometry system have been used to measure the variations under fluoroscopic and radiographic conditions for a number of generators. Variations in output due to filament heating, voltage supply and rectification, cable capacity and target pitting have been demonstrated. At low fluoroscopic currents, large surges and long decays have been observed; the significance of these effects is considered. (author)

  3. SU-F-J-166: Volumetric Spatial Distortions Comparison for 1.5 Tesla Versus 3 Tesla MRI for Gamma Knife Radiosurgery Scans Using Frame Marker Fusion and Co-Registration Modes

    International Nuclear Information System (INIS)

    Neyman, G

    2016-01-01

    Purpose: To compare typical volumetric spatial distortions for 1.5 Tesla versus 3 Tesla MRI Gamma Knife radiosurgery scans in the frame marker fusion and co-registration frame-less modes. Methods: Quasar phantom by Modus Medical Devices Inc. with GRID image distortion software was used for measurements of volumetric distortions. 3D volumetric T1 weighted scans of the phantom were produced on 1.5 T Avanto and 3 T Skyra MRI Siemens scanners. The analysis was done two ways: for scans with localizer markers from the Leksell frame and relatively to the phantom only (simulated co-registration technique). The phantom grid contained a total of 2002 vertices or control points that were used in the assessment of volumetric geometric distortion for all scans. Results: Volumetric mean absolute spatial deviations relatively to the frame localizer markers for 1.5 and 3 Tesla machine were: 1.39 ± 0.15 and 1.63 ± 0.28 mm with max errors of 1.86 and 2.65 mm correspondingly. Mean 2D errors from the Gamma Plan were 0.3 and 1.0 mm. For simulated co-registration technique the volumetric mean absolute spatial deviations relatively to the phantom for 1.5 and 3 Tesla machine were: 0.36 ± 0.08 and 0.62 ± 0.13 mm with max errors of 0.57 and 1.22 mm correspondingly. Conclusion: Volumetric spatial distortions are lower for 1.5 Tesla versus 3 Tesla MRI machines localized with markers on frames and significantly lower for co-registration techniques with no frame localization. The results show the advantage of using co-registration technique for minimizing MRI volumetric spatial distortions which can be especially important for steep dose gradient fields typically used in Gamma Knife radiosurgery. Consultant for Elekta AB

  4. SU-F-J-166: Volumetric Spatial Distortions Comparison for 1.5 Tesla Versus 3 Tesla MRI for Gamma Knife Radiosurgery Scans Using Frame Marker Fusion and Co-Registration Modes

    Energy Technology Data Exchange (ETDEWEB)

    Neyman, G [The Cleveland Clinic Foundation, Cleveland, OH (United States)

    2016-06-15

    Purpose: To compare typical volumetric spatial distortions for 1.5 Tesla versus 3 Tesla MRI Gamma Knife radiosurgery scans in the frame marker fusion and co-registration frame-less modes. Methods: Quasar phantom by Modus Medical Devices Inc. with GRID image distortion software was used for measurements of volumetric distortions. 3D volumetric T1 weighted scans of the phantom were produced on 1.5 T Avanto and 3 T Skyra MRI Siemens scanners. The analysis was done two ways: for scans with localizer markers from the Leksell frame and relatively to the phantom only (simulated co-registration technique). The phantom grid contained a total of 2002 vertices or control points that were used in the assessment of volumetric geometric distortion for all scans. Results: Volumetric mean absolute spatial deviations relatively to the frame localizer markers for 1.5 and 3 Tesla machine were: 1.39 ± 0.15 and 1.63 ± 0.28 mm with max errors of 1.86 and 2.65 mm correspondingly. Mean 2D errors from the Gamma Plan were 0.3 and 1.0 mm. For simulated co-registration technique the volumetric mean absolute spatial deviations relatively to the phantom for 1.5 and 3 Tesla machine were: 0.36 ± 0.08 and 0.62 ± 0.13 mm with max errors of 0.57 and 1.22 mm correspondingly. Conclusion: Volumetric spatial distortions are lower for 1.5 Tesla versus 3 Tesla MRI machines localized with markers on frames and significantly lower for co-registration techniques with no frame localization. The results show the advantage of using co-registration technique for minimizing MRI volumetric spatial distortions which can be especially important for steep dose gradient fields typically used in Gamma Knife radiosurgery. Consultant for Elekta AB.

  5. DIST/AVC Out-Put Definition.

    Science.gov (United States)

    Wilkinson, Gene L.

    The first stage of development of a management information system for DIST/AVC (Division of Instructional Technology/Audio-Visual Center) is the definition of out-put units. Some constraints on the definition of output units are: 1) they should reflect goals of the organization, 2) they should reflect organizational structure and procedures, and…

  6. Fast multi-output relevance vector regression

    OpenAIRE

    Ha, Youngmin

    2017-01-01

    This paper aims to decrease the time complexity of multi-output relevance vector regression from O(VM^3) to O(V^3+M^3), where V is the number of output dimensions, M is the number of basis functions, and V

  7. Early-Transition Output Decline Revisited

    Directory of Open Access Journals (Sweden)

    Crt Kostevc

    2016-05-01

    Full Text Available In this paper we revisit the issue of aggregate output decline that took place in the early transition period. We propose an alternative explanation of output decline that is applicable to Central- and Eastern-European countries. In the first part of the paper we develop a simple dynamic general equilibrium model that builds on work by Gomulka and Lane (2001. In particular, we consider price liberalization, interpreted as elimination of distortionary taxation, as a trigger of the output decline. We show that price liberalization in interaction with heterogeneous adjustment costs and non-employment benefits lead to aggregate output decline and surge in wage inequality. While these patterns are consistent with actual dynamics in CEE countries, this model cannot generate output decline in all sectors. Instead sectors that were initially taxed even exhibit output growth. Thus, in the second part we consider an alternative general equilibrium model with only one production sector and two types of labor and distortion in a form of wage compression during the socialist era. The trigger for labor mobility and consequently output decline is wage liberalization. Assuming heterogeneity of workers in terms of adjustment costs and non-employment benefits can explain output decline in all industries.

  8. Assessing the psychological factors predicting workers' output ...

    African Journals Online (AJOL)

    The study investigated job security, communication skills, interpersonal relationship and emotional intelligence as correlates of workers' output among local government employees in Oyo State. The research adopted descriptive design of an expose facto type. The research instruments used includes Workers' output scale, ...

  9. Measure of the volumetric efficiency and evaporator device performance for a liquefied petroleum gas spark ignition engine

    International Nuclear Information System (INIS)

    Masi, Massimo; Gobbato, Paolo

    2012-01-01

    Highlights: ► Measure of the effect of LPG fuel on volumetric efficiency of a SI petrol ICE. ► Steady-state and transient performance of a LPG evaporator device on a SI ICE. ► Volume displaced by LPG causes slight performance loss in SI petrol engines. ► LPG reveals peak efficiency and high-efficiency range wider than petrol in SI ICE’s. ► One-stage pressure reducer for LPG performs satisfactorily during SI ICE transients. - Abstract: The use of Liquefied Petroleum Gas (LPG) as fuel for spark ignition engines originally designed to be gasoline fuelled is common practice in many countries. Despite this, some questions remain still open. The present paper deals with the two main problems related to LPG port-fuel SI engines: the volumetric efficiency drop and the LPG evaporator device performance. A passengers car SI engine equipped with a “third generation” kit for the dual-fuel operation was tested using a dynamometer test rig. A single-stage pressure reducer was selected as LPG evaporator, to take advantage of an additional pre-heating of the liquid LPG that allows higher power output than a two-stage device of the same size. Engine performance, volumetric efficiency and change of LPG thermodynamic states in the evaporator were measured both in steady-state and transient operation of the engine. Steady-state measurements show the advantage of LPG in terms of engine efficiency, and quantify the drop in steady-state brake torque due to the volume swept by gaseous fuel in the fresh charge admission process. On the other hand, transient measurements show that a single-stage evaporator device is capable to match overall simplicity and satisfactory performance during strong changes in engine load.

  10. A planning study investigating dual-gated volumetric arc stereotactic treatment of primary renal cell carcinoma

    Energy Technology Data Exchange (ETDEWEB)

    Devereux, Thomas, E-mail: thomas.devereux@petermac.org [Radiation Therapy Services, Peter MacCallum Cancer Centre, Melbourne (Australia); Pham, Daniel [Radiation Therapy Services, Peter MacCallum Cancer Centre, Melbourne (Australia); Kron, Tomas [Department of Physical Sciences, Peter MacCallum Cancer Centre, Melbourne (Australia); Sir Peter MacCallum Department of Oncology, Melbourne University, Melbourne (Australia); Foroudi, Farshad [Sir Peter MacCallum Department of Oncology, Melbourne University, Melbourne (Australia); Radiation Oncology and Cancer Imaging, Peter MacCallum Cancer Centre, Melbourne (Australia); Supple, Jeremy [School of Applied Sciences, Royal Melbourne Institute of Technology, Melbourne (Australia); Siva, Shankar [Sir Peter MacCallum Department of Oncology, Melbourne University, Melbourne (Australia); Radiation Oncology and Cancer Imaging, Peter MacCallum Cancer Centre, Melbourne (Australia)

    2015-04-01

    This is a planning study investigating the dosimetric advantages of gated volumetric-modulated arc therapy (VMAT) to the end-exhale and end-inhale breathing phases for patients undergoing stereotactic treatment of primary renal cell carcinoma. VMAT plans were developed from the end-inhale (VMATinh) and the end-exhale (VMATexh) phases of the breathing cycle as well as a VMAT plan and 3-dimensional conformal radiation therapy plan based on an internal target volume (ITV) (VMATitv). An additional VMAT plan was created by giving the respective gated VMAT plan a 50% weighting and summing the inhale and exhale plans together to create a summed gated plan. Dose to organs at risk (OARs) as well as comparison of intermediate and low-dose conformity was evaluated. There was no difference in the volume of healthy tissue receiving the prescribed dose for the planned target volume (PTV) (CI100%) for all the VMAT plans; however, the mean volume of healthy tissue receiving 50% of the prescribed dose for the PTV (CI50%) values were 4.7 (± 0.2), 4.6 (± 0.2), and 4.7 (± 0.6) for the VMATitv, VMATinh, and VMATexh plans, respectively. The VMAT plans based on the exhale and inhale breathing phases showed a 4.8% and 2.4% reduction in dose to 30 cm{sup 3} of the small bowel, respectively, compared with that of the ITV-based VMAT plan. The summed gated VMAT plans showed a 6.2% reduction in dose to 30 cm{sup 3} of the small bowel compared with that of the VMAT plans based on the ITV. Additionally, when compared with the inhale and the exhale VMAT plans, a 4% and 1.5%, respectively, reduction was observed. Gating VMAT was able to reduce the amount of prescribed, intermediate, and integral dose to healthy tissue when compared with VMAT plans based on an ITV. When summing the inhale and exhale plans together, dose to healthy tissue and OARs was optimized. However, gating VMAT plans would take longer to treat and is a factor that needs to be considered.

  11. Volumetric CT-images improve testing of radiological image interpretation skills

    Energy Technology Data Exchange (ETDEWEB)

    Ravesloot, Cécile J., E-mail: C.J.Ravesloot@umcutrecht.nl [Radiology Department at University Medical Center Utrecht, Heidelberglaan 100, 3508 GA Utrecht, Room E01.132 (Netherlands); Schaaf, Marieke F. van der, E-mail: M.F.vanderSchaaf@uu.nl [Department of Pedagogical and Educational Sciences at Utrecht University, Heidelberglaan 1, 3584 CS Utrecht (Netherlands); Schaik, Jan P.J. van, E-mail: J.P.J.vanSchaik@umcutrecht.nl [Radiology Department at University Medical Center Utrecht, Heidelberglaan 100, 3508 GA Utrecht, Room E01.132 (Netherlands); Cate, Olle Th.J. ten, E-mail: T.J.tenCate@umcutrecht.nl [Center for Research and Development of Education at University Medical Center Utrecht, Heidelberglaan 100, 3508 GA Utrecht (Netherlands); Gijp, Anouk van der, E-mail: A.vanderGijp-2@umcutrecht.nl [Radiology Department at University Medical Center Utrecht, Heidelberglaan 100, 3508 GA Utrecht, Room E01.132 (Netherlands); Mol, Christian P., E-mail: C.Mol@umcutrecht.nl [Image Sciences Institute at University Medical Center Utrecht, Heidelberglaan 100, 3508 GA Utrecht (Netherlands); Vincken, Koen L., E-mail: K.Vincken@umcutrecht.nl [Image Sciences Institute at University Medical Center Utrecht, Heidelberglaan 100, 3508 GA Utrecht (Netherlands)

    2015-05-15

    Rationale and objectives: Current radiology practice increasingly involves interpretation of volumetric data sets. In contrast, most radiology tests still contain only 2D images. We introduced a new testing tool that allows for stack viewing of volumetric images in our undergraduate radiology program. We hypothesized that tests with volumetric CT-images enhance test quality, in comparison with traditional completely 2D image-based tests, because they might better reflect required skills for clinical practice. Materials and methods: Two groups of medical students (n = 139; n = 143), trained with 2D and volumetric CT-images, took a digital radiology test in two versions (A and B), each containing both 2D and volumetric CT-image questions. In a questionnaire, they were asked to comment on the representativeness for clinical practice, difficulty and user-friendliness of the test questions and testing program. Students’ test scores and reliabilities, measured with Cronbach's alpha, of 2D and volumetric CT-image tests were compared. Results: Estimated reliabilities (Cronbach's alphas) were higher for volumetric CT-image scores (version A: .51 and version B: .54), than for 2D CT-image scores (version A: .24 and version B: .37). Participants found volumetric CT-image tests more representative of clinical practice, and considered them to be less difficult than volumetric CT-image questions. However, in one version (A), volumetric CT-image scores (M 80.9, SD 14.8) were significantly lower than 2D CT-image scores (M 88.4, SD 10.4) (p < .001). The volumetric CT-image testing program was considered user-friendly. Conclusion: This study shows that volumetric image questions can be successfully integrated in students’ radiology testing. Results suggests that the inclusion of volumetric CT-images might improve the quality of radiology tests by positively impacting perceived representativeness for clinical practice and increasing reliability of the test.

  12. Synoptic volumetric variations and flushing of the Tampa Bay estuary

    Science.gov (United States)

    Wilson, M.; Meyers, S. D.; Luther, M. E.

    2014-03-01

    Two types of analyses are used to investigate the synoptic wind-driven flushing of Tampa Bay in response to the El Niño-Southern Oscillation (ENSO) cycle from 1950 to 2007. Hourly sea level elevations from the St. Petersburg tide gauge, and wind speed and direction from three different sites around Tampa Bay are used for the study. The zonal (u) and meridional (v) wind components are rotated clockwise by 40° to obtain axial and co-axial components according to the layout of the bay. First, we use the subtidal observed water level as a proxy for mean tidal height to estimate the rate of volumetric bay outflow. Second, we use wavelet analysis to bandpass sea level and wind data in the time-frequency domain to isolate the synoptic sea level and surface wind variance. For both analyses the long-term monthly climatology is removed and we focus on the volumetric and wavelet variance anomalies. The overall correlation between the Oceanic Niño Index and volumetric analysis is small due to the seasonal dependence of the ENSO response. The mean monthly climatology between the synoptic wavelet variance of elevation and axial winds are in close agreement. During the winter, El Niño (La Niña) increases (decreases) the synoptic variability, but decreases (increases) it during the summer. The difference in winter El Niño/La Niña wavelet variances is about 20 % of the climatological value, meaning that ENSO can swing the synoptic flushing of the bay by 0.22 bay volumes per month. These changes in circulation associated with synoptic variability have the potential to impact mixing and transport within the bay.

  13. Agreement of mammographic measures of volumetric breast density to MRI.

    Directory of Open Access Journals (Sweden)

    Jeff Wang

    Full Text Available Clinical scores of mammographic breast density are highly subjective. Automated technologies for mammography exist to quantify breast density objectively, but the technique that most accurately measures the quantity of breast fibroglandular tissue is not known.To compare the agreement of three automated mammographic techniques for measuring volumetric breast density with a quantitative volumetric MRI-based technique in a screening population.Women were selected from the UCSF Medical Center screening population that had received both a screening MRI and digital mammogram within one year of each other, had Breast Imaging Reporting and Data System (BI-RADS assessments of normal or benign finding, and no history of breast cancer or surgery. Agreement was assessed of three mammographic techniques (Single-energy X-ray Absorptiometry [SXA], Quantra, and Volpara with MRI for percent fibroglandular tissue volume, absolute fibroglandular tissue volume, and total breast volume.Among 99 women, the automated mammographic density techniques were correlated with MRI measures with R(2 values ranging from 0.40 (log fibroglandular volume to 0.91 (total breast volume. Substantial agreement measured by kappa statistic was found between all percent fibroglandular tissue measures (0.72 to 0.63, but only moderate agreement for log fibroglandular volumes. The kappa statistics for all percent density measures were highest in the comparisons of the SXA and MRI results. The largest error source between MRI and the mammography techniques was found to be differences in measures of total breast volume.Automated volumetric fibroglandular tissue measures from screening digital mammograms were in substantial agreement with MRI and if associated with breast cancer could be used in clinical practice to enhance risk assessment and prevention.

  14. Agreement of mammographic measures of volumetric breast density to MRI.

    Science.gov (United States)

    Wang, Jeff; Azziz, Ania; Fan, Bo; Malkov, Serghei; Klifa, Catherine; Newitt, David; Yitta, Silaja; Hylton, Nola; Kerlikowske, Karla; Shepherd, John A

    2013-01-01

    Clinical scores of mammographic breast density are highly subjective. Automated technologies for mammography exist to quantify breast density objectively, but the technique that most accurately measures the quantity of breast fibroglandular tissue is not known. To compare the agreement of three automated mammographic techniques for measuring volumetric breast density with a quantitative volumetric MRI-based technique in a screening population. Women were selected from the UCSF Medical Center screening population that had received both a screening MRI and digital mammogram within one year of each other, had Breast Imaging Reporting and Data System (BI-RADS) assessments of normal or benign finding, and no history of breast cancer or surgery. Agreement was assessed of three mammographic techniques (Single-energy X-ray Absorptiometry [SXA], Quantra, and Volpara) with MRI for percent fibroglandular tissue volume, absolute fibroglandular tissue volume, and total breast volume. Among 99 women, the automated mammographic density techniques were correlated with MRI measures with R(2) values ranging from 0.40 (log fibroglandular volume) to 0.91 (total breast volume). Substantial agreement measured by kappa statistic was found between all percent fibroglandular tissue measures (0.72 to 0.63), but only moderate agreement for log fibroglandular volumes. The kappa statistics for all percent density measures were highest in the comparisons of the SXA and MRI results. The largest error source between MRI and the mammography techniques was found to be differences in measures of total breast volume. Automated volumetric fibroglandular tissue measures from screening digital mammograms were in substantial agreement with MRI and if associated with breast cancer could be used in clinical practice to enhance risk assessment and prevention.

  15. Method for Determining Volumetric Efficiency and Its Experimental Validation

    Directory of Open Access Journals (Sweden)

    Ambrozik Andrzej

    2017-12-01

    Full Text Available Modern means of transport are basically powered by piston internal combustion engines. Increasingly rigorous demands are placed on IC engines in order to minimise the detrimental impact they have on the natural environment. That stimulates the development of research on piston internal combustion engines. The research involves experimental and theoretical investigations carried out using computer technologies. While being filled, the cylinder is considered to be an open thermodynamic system, in which non-stationary processes occur. To make calculations of thermodynamic parameters of the engine operating cycle, based on the comparison of cycles, it is necessary to know the mean constant value of cylinder pressure throughout this process. Because of the character of in-cylinder pressure pattern and difficulties in pressure experimental determination, in the present paper, a novel method for the determination of this quantity was presented. In the new approach, the iteration method was used. In the method developed for determining the volumetric efficiency, the following equations were employed: the law of conservation of the amount of substance, the first law of thermodynamics for open system, dependences for changes in the cylinder volume vs. the crankshaft rotation angle, and the state equation. The results of calculations performed with this method were validated by means of experimental investigations carried out for a selected engine at the engine test bench. A satisfactory congruence of computational and experimental results as regards determining the volumetric efficiency was obtained. The method for determining the volumetric efficiency presented in the paper can be used to investigate the processes taking place in the cylinder of an IC engine.

  16. Study and modeling of changes in volumetric efficiency of helix conveyors at different rotational speeds and inclination angels by ANFIS and statistical methods

    Directory of Open Access Journals (Sweden)

    A Zareei

    2017-05-01

    Full Text Available Introduction Spiral conveyors effectively carry solid masses as free or partly free flow of materials. They create good throughput and they are the perfect solution to solve the problems of transport, due to their simple structure, high efficiency and low maintenance costs. This study aims to investigate the performance characteristics of conveyors as function of auger diameter, rotational speed and handling inclination angle. The performance characteristic was investigated according to volumetric efficiency. In another words, the purpose of this study was obtaining a suitable model for volumetric efficiency changes of steep auger to transfer agricultural products. Three different diameters of auger, five levels of rotational speed and three slope angles were used to investigate the effects of changes in these parameters on volumetric efficiency of auger. The used method is novel in this area and the results show that performance by ANFIS models is much better than common statistical models. Materials and Methods The experiments were conducted in Department of Mechanical Engineering of Agricultural Machinery in Urmia University. In this study, SAYOS cultivar of wheat was used. This cultivar of wheat had hard seeds and the humidity was 12% (based on wet. Before testing, all foreign material was separated from the wheat such as stone, dust, plant residues and green seeds. Bulk density of wheat was 790 kg m-3. The auger shaft of the spiral conveyor was received its rotational force through belt and electric motor and its rotation leading to transfer the product to the output. In this study, three conveyors at diameters of 13, 17.5, and 22.5 cm, five levels of rotational speed at 100, 200, 300, 400, and 500 rpm and three handling angles of 10, 20, and 30º were tested. Adaptive Nero-fuzzy inference system (ANFIS is the combination of fuzzy systems and artificial neural network, so it has both benefits. This system is useful to solve the complex non

  17. High Output Piezo/Triboelectric Hybrid Generator

    Science.gov (United States)

    Jung, Woo-Suk; Kang, Min-Gyu; Moon, Hi Gyu; Baek, Seung-Hyub; Yoon, Seok-Jin; Wang, Zhong-Lin; Kim, Sang-Woo; Kang, Chong-Yun

    2015-03-01

    Recently, piezoelectric and triboelectric energy harvesting devices have been developed to convert mechanical energy into electrical energy. Especially, it is well known that triboelectric nanogenerators have a simple structure and a high output voltage. However, whereas nanostructures improve the output of triboelectric generators, its fabrication process is still complicated and unfavorable in term of the large scale and long-time durability of the device. Here, we demonstrate a hybrid generator which does not use nanostructure but generates much higher output power by a small mechanical force and integrates piezoelectric generator into triboelectric generator, derived from the simultaneous use of piezoelectric and triboelectric mechanisms in one press-and-release cycle. This hybrid generator combines high piezoelectric output current and triboelectric output voltage, which produces peak output voltage of ~370 V, current density of ~12 μA.cm-2, and average power density of ~4.44 mW.cm-2. The output power successfully lit up 600 LED bulbs by the application of a 0.2 N mechanical force and it charged a 10 μF capacitor to 10 V in 25 s. Beyond energy harvesting, this work will provide new opportunities for developing a small, built-in power source in self-powered electronics such as mobile electronics.

  18. High Output Piezo/Triboelectric Hybrid Generator

    Science.gov (United States)

    Jung, Woo-Suk; Kang, Min-Gyu; Moon, Hi Gyu; Baek, Seung-Hyub; Yoon, Seok-Jin; Wang, Zhong-Lin; Kim, Sang-Woo; Kang, Chong-Yun

    2015-01-01

    Recently, piezoelectric and triboelectric energy harvesting devices have been developed to convert mechanical energy into electrical energy. Especially, it is well known that triboelectric nanogenerators have a simple structure and a high output voltage. However, whereas nanostructures improve the output of triboelectric generators, its fabrication process is still complicated and unfavorable in term of the large scale and long-time durability of the device. Here, we demonstrate a hybrid generator which does not use nanostructure but generates much higher output power by a small mechanical force and integrates piezoelectric generator into triboelectric generator, derived from the simultaneous use of piezoelectric and triboelectric mechanisms in one press-and-release cycle. This hybrid generator combines high piezoelectric output current and triboelectric output voltage, which produces peak output voltage of ~370 V, current density of ~12 μA·cm−2, and average power density of ~4.44 mW·cm−2. The output power successfully lit up 600 LED bulbs by the application of a 0.2 N mechanical force and it charged a 10 μF capacitor to 10 V in 25 s. Beyond energy harvesting, this work will provide new opportunities for developing a small, built-in power source in self-powered electronics such as mobile electronics. PMID:25791299

  19. Synthesis of Volumetric Ring Antenna Array for Terrestrial Coverage Pattern

    Directory of Open Access Journals (Sweden)

    Alberto Reyna

    2014-01-01

    Full Text Available This paper presents a synthesis of a volumetric ring antenna array for a terrestrial coverage pattern. This synthesis regards the spacing among the rings on the planes X-Y, the positions of the rings on the plane X-Z, and uniform and concentric excitations. The optimization is carried out by implementing the particle swarm optimization. The synthesis is compared with previous designs by resulting with proper performance of this geometry to provide an accurate coverage to be applied in satellite applications with a maximum reduction of the antenna hardware as well as the side lobe level reduction.

  20. Synthesis of Volumetric Ring Antenna Array for Terrestrial Coverage Pattern

    Science.gov (United States)

    Reyna, Alberto; Panduro, Marco A.; Del Rio Bocio, Carlos

    2014-01-01

    This paper presents a synthesis of a volumetric ring antenna array for a terrestrial coverage pattern. This synthesis regards the spacing among the rings on the planes X-Y, the positions of the rings on the plane X-Z, and uniform and concentric excitations. The optimization is carried out by implementing the particle swarm optimization. The synthesis is compared with previous designs by resulting with proper performance of this geometry to provide an accurate coverage to be applied in satellite applications with a maximum reduction of the antenna hardware as well as the side lobe level reduction. PMID:24701150

  1. Volumetric and calorimetric properties of aqueous ionene solutions.

    Science.gov (United States)

    Lukšič, Miha; Hribar-Lee, Barbara

    2017-02-01

    The volumetric (partial and apparent molar volumes) and calorimetric properties (apparent heat capacities) of aqueous cationic polyelectrolyte solutions - ionenes - were studied using the oscillating tube densitometer and differential scanning calorimeter. The polyion's charge density and the counterion properties were considered as variables. The special attention was put to evaluate the contribution of electrostatic and hydrophobic effects to the properties studied. The contribution of the CH 2 group of the polyion's backbone to molar volumes and heat capacities was estimated. Synergistic effect between polyion and counterions was found.

  2. Volumetric 3D Display System with Static Screen

    Science.gov (United States)

    Geng, Jason

    2011-01-01

    Current display technology has relied on flat, 2D screens that cannot truly convey the third dimension of visual information: depth. In contrast to conventional visualization that is primarily based on 2D flat screens, the volumetric 3D display possesses a true 3D display volume, and places physically each 3D voxel in displayed 3D images at the true 3D (x,y,z) spatial position. Each voxel, analogous to a pixel in a 2D image, emits light from that position to form a real 3D image in the eyes of the viewers. Such true volumetric 3D display technology provides both physiological (accommodation, convergence, binocular disparity, and motion parallax) and psychological (image size, linear perspective, shading, brightness, etc.) depth cues to human visual systems to help in the perception of 3D objects. In a volumetric 3D display, viewers can watch the displayed 3D images from a completely 360 view without using any special eyewear. The volumetric 3D display techniques may lead to a quantum leap in information display technology and can dramatically change the ways humans interact with computers, which can lead to significant improvements in the efficiency of learning and knowledge management processes. Within a block of glass, a large amount of tiny dots of voxels are created by using a recently available machining technique called laser subsurface engraving (LSE). The LSE is able to produce tiny physical crack points (as small as 0.05 mm in diameter) at any (x,y,z) location within the cube of transparent material. The crack dots, when illuminated by a light source, scatter the light around and form visible voxels within the 3D volume. The locations of these tiny voxels are strategically determined such that each can be illuminated by a light ray from a high-resolution digital mirror device (DMD) light engine. The distribution of these voxels occupies the full display volume within the static 3D glass screen. This design eliminates any moving screen seen in previous

  3. CT volumetric measurements of the orbits in Graves' disease

    International Nuclear Information System (INIS)

    Krahe, T.; Schlolaut, K.H.; Poss, T.; Trier, H.G.; Lackner, K.; Bonn Univ.; Bonn Univ.

    1989-01-01

    The volumes of the four recti muscles and the orbital fat was measured by CT in 40 normal persons and in 60 patients with clinically confirmed Graves' disease. Compared with normal persons, 42 patients (70%) showed an increase in muscle volume and 28 patients (46.7%) an increase in the amount of fat. In nine patients (15%) muscle volume was normal, but the fat was increased. By using volumetric measurements, the amount of fat in the orbits in patients with Graves' disease could be determined. (orig.) [de

  4. Hierarchical anatomical brain networks for MCI prediction: revisiting volumetric measures.

    Directory of Open Access Journals (Sweden)

    Luping Zhou

    Full Text Available Owning to its clinical accessibility, T1-weighted MRI (Magnetic Resonance Imaging has been extensively studied in the past decades for prediction of Alzheimer's disease (AD and mild cognitive impairment (MCI. The volumes of gray matter (GM, white matter (WM and cerebrospinal fluid (CSF are the most commonly used measurements, resulting in many successful applications. It has been widely observed that disease-induced structural changes may not occur at isolated spots, but in several inter-related regions. Therefore, for better characterization of brain pathology, we propose in this paper a means to extract inter-regional correlation based features from local volumetric measurements. Specifically, our approach involves constructing an anatomical brain network for each subject, with each node representing a Region of Interest (ROI and each edge representing Pearson correlation of tissue volumetric measurements between ROI pairs. As second order volumetric measurements, network features are more descriptive but also more sensitive to noise. To overcome this limitation, a hierarchy of ROIs is used to suppress noise at different scales. Pairwise interactions are considered not only for ROIs with the same scale in the same layer of the hierarchy, but also for ROIs across different scales in different layers. To address the high dimensionality problem resulting from the large number of network features, a supervised dimensionality reduction method is further employed to embed a selected subset of features into a low dimensional feature space, while at the same time preserving discriminative information. We demonstrate with experimental results the efficacy of this embedding strategy in comparison with some other commonly used approaches. In addition, although the proposed method can be easily generalized to incorporate other metrics of regional similarities, the benefits of using Pearson correlation in our application are reinforced by the experimental

  5. Z-Index Parameterization for Volumetric CT Image Reconstruction via 3-D Dictionary Learning.

    Science.gov (United States)

    Bai, Ti; Yan, Hao; Jia, Xun; Jiang, Steve; Wang, Ge; Mou, Xuanqin

    2017-12-01

    Despite the rapid developments of X-ray cone-beam CT (CBCT), image noise still remains a major issue for the low dose CBCT. To suppress the noise effectively while retain the structures well for low dose CBCT image, in this paper, a sparse constraint based on the 3-D dictionary is incorporated into a regularized iterative reconstruction framework, defining the 3-D dictionary learning (3-DDL) method. In addition, by analyzing the sparsity level curve associated with different regularization parameters, a new adaptive parameter selection strategy is proposed to facilitate our 3-DDL method. To justify the proposed method, we first analyze the distributions of the representation coefficients associated with the 3-D dictionary and the conventional 2-D dictionary to compare their efficiencies in representing volumetric images. Then, multiple real data experiments are conducted for performance validation. Based on these results, we found: 1) the 3-D dictionary-based sparse coefficients have three orders narrower Laplacian distribution compared with the 2-D dictionary, suggesting the higher representation efficiencies of the 3-D dictionary; 2) the sparsity level curve demonstrates a clear Z-shape, and hence referred to as Z-curve, in this paper; 3) the parameter associated with the maximum curvature point of the Z-curve suggests a nice parameter choice, which could be adaptively located with the proposed Z-index parameterization (ZIP) method; 4) the proposed 3-DDL algorithm equipped with the ZIP method could deliver reconstructions with the lowest root mean squared errors and the highest structural similarity index compared with the competing methods; 5) similar noise performance as the regular dose FDK reconstruction regarding the standard deviation metric could be achieved with the proposed method using (1/2)/(1/4)/(1/8) dose level projections. The contrast-noise ratio is improved by ~2.5/3.5 times with respect to two different cases under the (1/8) dose level compared

  6. MO-AB-BRA-01: A Global Level Set Based Formulation for Volumetric Modulated Arc Therapy

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, D; Lyu, Q; Ruan, D; O’Connor, D; Low, D; Sheng, K [Department of Radiation Oncology, University of California Los Angeles, Los Angeles, CA (United States)

    2016-06-15

    Purpose: The current clinical Volumetric Modulated Arc Therapy (VMAT) optimization is formulated as a non-convex problem and various greedy heuristics have been employed for an empirical solution, jeopardizing plan consistency and quality. We introduce a novel global direct aperture optimization method for VMAT to overcome these limitations. Methods: The global VMAT (gVMAT) planning was formulated as an optimization problem with an L2-norm fidelity term and an anisotropic total variation term. A level set function was used to describe the aperture shapes and adjacent aperture shapes were penalized to control MLC motion range. An alternating optimization strategy was implemented to solve the fluence intensity and aperture shapes simultaneously. Single arc gVMAT plans, utilizing 180 beams with 2° angular resolution, were generated for a glioblastoma multiforme (GBM), lung (LNG), and 2 head and neck cases—one with 3 PTVs (H&N3PTV) and one with 4 PTVs (H&N4PTV). The plans were compared against the clinical VMAT (cVMAT) plans utilizing two overlapping coplanar arcs. Results: The optimization of the gVMAT plans had converged within 600 iterations. gVMAT reduced the average max and mean OAR dose by 6.59% and 7.45% of the prescription dose. Reductions in max dose and mean dose were as high as 14.5 Gy in the LNG case and 15.3 Gy in the H&N3PTV case. PTV coverages (D95, D98, D99) were within 0.25% of the prescription dose. By globally considering all beams, the gVMAT optimizer allowed some beams to deliver higher intensities, yielding a dose distribution that resembles a static beam IMRT plan with beam orientation optimization. Conclusions: The novel VMAT approach allows for the search of an optimal plan in the global solution space and generates deliverable apertures directly. The single arc VMAT approach fully utilizes the digital linacs’ capability in dose rate and gantry rotation speed modulation. Varian Medical Systems, NIH grant R01CA188300, NIH grant R43CA183390.

  7. Biological-based optimization and volumetric modulated arc therapy delivery for stereotactic body radiation therapy

    International Nuclear Information System (INIS)

    Diot, Quentin; Kavanagh, Brian; Timmerman, Robert; Miften, Moyed

    2012-01-01

    Purpose: To describe biological-based optimization and Monte Carlo (MC) dose calculation-based treatment planning for volumetric modulated arc therapy (VMAT) delivery of stereotactic body radiation therapy (SBRT) in lung, liver, and prostate patients. Methods: Optimization strategies and VMAT planning parameters using a biological-based optimization MC planning system were analyzed for 24 SBRT patients. Patients received a median dose of 45 Gy [range, 34-54 Gy] for lung tumors in 1-5 fxs and a median dose of 52 Gy [range, 48-60 Gy] for liver tumors in 3-6 fxs. Prostate patients received a fractional dose of 10 Gy in 5 fxs. Biological-cost functions were used for plan optimization, and its dosimetric quality was evaluated using the conformity index (CI), the conformation number (CN), the ratio of the volume receiving 50% of the prescription dose over the planning target volume (Rx/PTV50). The quality and efficiency of the delivery were assessed according to measured quality assurance (QA) passing rates and delivery times. For each disease site, one patient was replanned using physical cost function and compared to the corresponding biological plan. Results: Median CI, CN, and Rx/PTV50 for all 24 patients were 1.13 (1.02-1.28), 0.79 (0.70-0.88), and 5.3 (3.1-10.8), respectively. The median delivery rate for all patients was 410 MU/min with a maximum possible rate of 480 MU/min (85%). Median QA passing rate was 96.7%, and it did not significantly vary with the tumor site. Conclusions: VMAT delivery of SBRT plans optimized using biological-motivated cost-functions result in highly conformal dose distributions. Plans offer shorter treatment-time benefits and provide efficient dose delivery without compromising the plan conformity for tumors in the prostate, lung, and liver, thereby improving patient comfort and clinical throughput. The short delivery times minimize the risk of patient setup and intrafraction motion errors often associated with long SBRT treatment

  8. Determination Of Output Factor For Photon Beam Of The Mitsubishi EXL-14 Linear Accelerator

    International Nuclear Information System (INIS)

    Nurman R; Sri-Inang S; Dani

    2003-01-01

    This paper describes the determination of output factor for 6 MV photon beam of The Mitsubishi EXL-14 linear accelerator teletherapy unit. Determination of percentage depth dose curve has been done using Wallhofer dosemeter at source to surface distance, SSD of 100 cm and field size of 10 cm x 10 cm. Measurement of output has been carried out using a 0.6 cc ionization chamber inside a water phantom at depth of 5 cm with source to surface distance, SSD of 100 cm for square fields ranging in size 4 cm x 4 cm up to 10 cm x 10 cm. Output for rectangular fields which equal to the equivalent square fields were also determined. The results obtained shows that the deviations of the output for 12 cm x 3 cm and 19 cm x 7 cm were higher than ±2% to the output of the equivalent square fields. (author)

  9. Comparative study of dose descriptor in pediatric computed tomography exams

    International Nuclear Information System (INIS)

    Finatto, Jerusa Dalbosco; Silva, Ana Maria Marques da; Froner, Ana Paula Pastre; Pimentel, Juliana

    2014-01-01

    This work aims to investigate the dose descriptor, volumetric Computed Tomography Dose Index (CTDI), a pediatric patients sample undergoing to skull CT, comparing the results with the diagnostic reference levels of the literature. Were collected volumetric CTDI values of all skull CT exams performed retrospectively in children of 0-10 years of age in a period of 12 months in a large hospital size. Patients, in a total of 103, were divided into four groups, where the criterion of separation used was age, trying to use the same division used in international references dose descriptors. In all acquisitions we used the pediatric protocol and the Automatic Exposure Control (AEC) available on the equipment. The CDTI values, with and without the use of AEC for pediatric studies, were compared. There was a reduction of approximately 100% in the absorbed dose value due to the use of the AEC. From the data collected and analyzed in this work, it is concluded that the use of dose reduction systems is relevant, such as the Care Dose, to maintain volumetric CTDI values within the reference levels. Also it is important the observation of range of children age to the appropriate choice of parameters used in the test protocol. The values obtained are according to the diagnostic reference levels from the literature

  10. Evaluation of aluminum oxide dosimeters using OSL technique in dosimetry of clinical photon beams on volumetric modulated arc treatment

    International Nuclear Information System (INIS)

    Villani, Daniel

    2017-01-01

    Treatment using Volumetric Modulated Arc Radiation Therapy is the most modern modality of conformational radiotherapy so that, with the overlapping of several fields, the dose distributions provide a perfect conformation to the tumor, reducing the probability of complications in adjacent normal tissues. In this sense, many efforts are being invested to improve dose distribution compliance as well as the integration of imaging techniques for tumor screening and correction of inter and intrafraction variations. To this end, an intensive monitoring of the quality of the processes and a quality assurance program are fundamental for patient safety and compliance with current legislation; besides the use of different dosimetry methodologies for intercomparison and validation of the results. The aim of this study is to evaluate and compare the performance of aluminum oxide (Al_2O_3:C) OSL dosimeters manufactured by Landauer Inc. with those produced by Rexon™ in the dosimetry of high energy photon clinical bundles used in Volumetric Modulated Arc Therapy - (VMAT) using different simulating objects. The dosimeters were characterized for gamma radiation of the "6"0Co and for clinical photon beams of 6 MV typical of treatments by VMAT under conditions of electronic equilibrium and maximum dose respectively. Performance tests of the TL and OSL readers used and repeatability of the samples were evaluated. After all tests, the dosimeters were irradiated in the simulation of different radiotherapy treatments by VMAT and their responses compared to the planning system. All types of dosimeters presented satisfactory results in verifying the doses of this type of planning simulation. The Al_2O_3:C dosimeters presented compatible results and validated by the other dosimeters and ionization chamber. Regarding the best technique, the OSL InLight commercial system presents greater practicality and versatility for use and application in the clinical routine. (author)

  11. Fast in vivo volume dose reconstruction via reference dose perturbation

    International Nuclear Information System (INIS)

    Lu, Weiguo; Chen, Mingli; Mo, Xiaohu; Parnell, Donald; Olivera, Gustavo; Galmarini, Daniel

    2014-01-01

    Purpose: Accurate on-line reconstruction of in-vivo volume dose that accounts for both machine and patient discrepancy is not clinically available. We present a simple reference-dose-perturbation algorithm that reconstructs in-vivo volume dose fast and accurately. Methods: We modelled the volume dose as a function of the fluence map and density image. Machine (output variation, jaw/leaf position errors, etc.) and patient (setup error, weight loss, etc.) discrepancies between the plan and delivery were modelled as perturbation of the fluence map and density image, respectively. Delivered dose is modelled as perturbation of the reference dose due to change of the fluence map and density image. We used both simulated and clinical data to validate the algorithm. The planned dose was used as the reference. The reconstruction was perturbed from the reference and accounted for output-variations and the registered daily image. The reconstruction was compared with the ground truth via isodose lines and the Gamma Index. Results: For various plans and geometries, the volume doses were reconstructed in few seconds. The reconstruction generally matched well with the ground truth. For the 3%/3mm criteria, the Gamma pass rates were 98% for simulations and 95% for clinical data. The differences mainly appeared on the surface of the phantom/patient. Conclusions: A novel reference-dose-perturbation dose reconstruction model is presented. The model accounts for machine and patient discrepancy from planning. The algorithm is simple, fast, yet accurate, which makes online in-vivo 3D dose reconstruction clinically feasible.

  12. Evaluation of volumetric modulated arc therapy for cranial radiosurgery using multiple noncoplanar arcs

    International Nuclear Information System (INIS)

    Audet, Chantal; Poffenbarger, Brett A.; Chang, Pauling; Jackson, Paul S.; Lundahl, Robert E.; Ryu, Stephen I.; Ray, Gordon R.

    2011-01-01

    Purpose: To evaluate a commercial volumetric modulated arc therapy (VMAT), using multiple noncoplanar arcs, for linac-based cranial radiosurgery, as well as evaluate the combined accuracy of the VMAT dose calculations and delivery. Methods: Twelve patients with cranial lesions of variable size (0.1-29 cc) and two multiple metastases patients were planned (Eclipse RapidArc AAA algorithm, v8.6.15) using VMAT (1-6 noncoplanar arcs), dynamic conformal arc (DCA, ∼4 arcs), and IMRT (nine static fields). All plans were evaluated according to a conformity index (CI), healthy brain tissue doses and volumes, and the dose to organs at risk. A 2D dose distribution was measured (Varian Novalis Tx, HD120 MLC, 1000 MU/min, 6 MV beam) for the ∼4 arc VMAT treatment plans using calibrated film dosimetry. Results: The CI (0-1 best) average for all plans was best for ∼4 noncoplanar arc VMAT at 0.86 compared with ∼0.78 for IMRT and a single arc VMAT and 0.68 for DCA. The volumes of healthy brain receiving 50% of the prescribed target coverage dose or more (V 50% ) were lowest for the four arc VMAT [RA(4)] and DCA plans. The average ratio of the V 50% for the other plans to the RA(4) V 50% were 1.9 for a single noncoplanar arc VMAT [RA(1nc)], 1.4 for single full coplanar arc VMAT [RA(1f)] and 1.3 for IMRT. The V 50% improved significantly for single isocenter multiple metastases plan when two noncoplanar VMAT arcs were added to a full single coplanar one. The maximum dose to 5 cc of the outer 1 cm rim of healthy brain which one may want to keep below nonconsequential doses of 300-400 cGy, was 2-3 times greater for IMRT, RA(1nc) and RA(1f) plans compared with the multiple noncoplanar arc DCA and RA(4) techniques. Organs at risk near (0-4 mm) to targets were best spared by (i) single noncoplanar arcs when the targets are lateral to the organ at risk and (ii) by skewed nonvertical planes of IMRT fields when the targets are not lateral to the organ at risk. The highest dose gradient

  13. Comparative analysis of volumetric-modulated arc therapy and intensity-modulated radiotherapy for base of tongue cancer

    International Nuclear Information System (INIS)

    Nithya, L.; Arulraj, Kumar; Rathinamuthu, Sasikumar; Pandey, Manish Bhushan; Nambi Raj, N. Arunai

    2014-01-01

    The aim of this study was to compare the various dosimetric parameters of dynamic multileaf collimator (MLC) intensity modulated radiation therapy (IMRT) plans with volumetric modulated arc therapy (VMAT) plans for base of tongue cases. All plans were done in Monaco planning system for Elekta synergy linear accelerator with 80 MLC. IMRT plans were planned with nine stationary beams, and VMAT plans were done for 360° arc with single arc or dual arc. The dose to the planning target volumes (PTV) for 70, 63, and 56 Gy was compared. The dose to 95, 98, and 50% volume of PTV were analyzed. The homogeneity index (HI) and the conformity index (CI) of the PTV 70 were also analyzed. IMRT and VMAT plan showed similar dose coverage, HI, and CI. Maximum dose and dose to 1-cc volume of spinal cord, planning risk volume (PRV) cord, and brain stem were compared. IMRT plan and VMAT plan showed similar results except for the 1 cc of PRV cord that received slightly higher dose in VMAT plan. Mean dose and dose to 50% volume of right and left parotid glands were analyzed. VMAT plan gave better sparing of parotid glands than IMRT. In normal tissue dose analyses VMAT was better than IMRT. The number of monitor units (MU) required for delivering the good quality of the plan and the time required to deliver the plan for IMRT and VMAT were compared. The number of MUs for VMAT was higher than that of IMRT plans. However, the delivery time was reduced by a factor of two for VMAT compared with IMRT. VMAT plans yielded good quality of the plan compared with IMRT, resulting in reduced treatment time and improved efficiency for base of tongue cases. (author)

  14. Volumetric modulated arc therapy and breath-hold in image-guided locoregional left-sided breast irradiation

    International Nuclear Information System (INIS)

    Osman, Sarah O.S.; Hol, Sandra; Poortmans, Philip M.; Essers, Marion

    2014-01-01

    Purpose: To investigate the effects of using volumetric modulated arc therapy (VMAT) and/or voluntary moderate deep inspiration breath-hold (vmDIBH) in the radiation therapy (RT) of left-sided breast cancer including the regional lymph nodes. Materials and methods: For 13 patients, four treatment combinations were compared; 3D-conformal RT (i.e., forward IMRT) in free-breathing 3D-CRT(FB), 3D-CRT(vmDIBH), 2 partial arcs VMAT(FB), and VMAT(vmDIBH). Prescribed dose was 42.56 Gy in 16 fractions. For 10 additional patients, 3D-CRT and VMAT in vmDIBH only were also compared. Results: Dose conformity, PTV coverage, ipsilateral and total lung doses were significantly better for VMAT plans compared to 3D-CRT. Mean heart dose (D mean,heart ) reduction in 3D-CRT(vmDIBH) was between 0.9 and 8.6 Gy, depending on initial D mean,heart (in 3D-CRT(FB) plans). VMAT(vmDIBH) reduced the D mean,heart further when D mean,heart was still >3.2 Gy in 3D-CRT(vmDIBH). Mean contralateral breast dose was higher for VMAT plans (2.7 Gy) compared to 3DCRT plans (0.7 Gy). Conclusions: VMAT and 3D-CRT(vmDIBH) significantly reduced heart dose for patients treated with locoregional RT of left-sided breast cancer. When D mean,heart exceeded 3.2 Gy in 3D-CRT(vmDIBH) plans, VMAT(vmDIBH) resulted in a cumulative heart dose reduction. VMAT also provided better target coverage and reduced ipsilateral lung dose, at the expense of a small increase in the dose to the contralateral breast

  15. Comparative analysis of volumetric-modulated arc therapy and intensity-modulated radiotherapy for base of tongue cancer

    Directory of Open Access Journals (Sweden)

    L Nithya

    2014-01-01

    Full Text Available The aim of this study was to compare the various dosimetric parameters of dynamic multileaf collimator (MLC intensity modulated radiation therapy (IMRT plans with volumetric modulated arc therapy (VMAT plans for base of tongue cases. All plans were done in Monaco planning system for Elekta synergy linear accelerator with 80 MLC. IMRT plans were planned with nine stationary beams, and VMAT plans were done for 360° arc with single arc or dual arc. The dose to the planning target volumes (PTV for 70, 63, and 56 Gy was compared. The dose to 95, 98, and 50% volume of PTV were analyzed. The homogeneity index (HI and the conformity index (CI of the PTV 70 were also analyzed. IMRT and VMAT plan showed similar dose coverage, HI, and CI. Maximum dose and dose to 1-cc volume of spinal cord, planning risk volume (PRV cord, and brain stem were compared. IMRT plan and VMAT plan showed similar results except for the 1 cc of PRV cord that received slightly higher dose in VMAT plan. Mean dose and dose to 50% volume of right and left parotid glands were analyzed. VMAT plan gave better sparing of parotid glands than IMRT. In normal tissue dose analyses VMAT was better than IMRT. The number of monitor units (MU required for delivering the good quality of the plan and the time required to deliver the plan for IMRT and VMAT were compared. The number of MUs for VMAT was higher than that of IMRT plans. However, the delivery time was reduced by a factor of two for VMAT compared with IMRT. VMAT plans yielded good quality of the plan compared with IMRT, resulting in reduced treatment time and improved efficiency for base of tongue cases.

  16. Evidence That Androgens Modulate Human Thymic T Cell Output

    Science.gov (United States)

    Olsen, Nancy J.; Kovacs, William J.

    2010-01-01

    Background The thymus has long been recognized as a target for the actions of androgenic hormones, but it has only been recently recognized that alterations in circulating levels of gonadal steroids might affect thymic output of T cells. We had the opportunity to examine parameters of thymic cellular output in several hypogonadal men undergoing androgen replacement therapy. Methods Circulating naive (CD4+CD45RA+) T cells were quantitated by flow cytometric analysis of peripheral blood mononuclear cells (PBMCs). Cells bearing T cell receptor excision circles (TRECs) were quantitated using real-time PCR amplification of DNA isolated from PBMCs from normal men and from hypogonadal men before and after testosterone replacement therapy. Results CD4+CD45+ (“naïve”) T cells comprised 10.5% of lymphocytes in normal males; this proportion was greatly increased in two hypogonadal men (35.5% and 44.4%). One man was studied sequentially during treatment with physiologic doses of testosterone. CD4+CD45RA+ cells fell from 37.36% to 20.05% after one month and to 12.51% after 7 months of normalized androgen levels. In two hypogonadal patients TREC levels fell by 83% and 78% after androgen replacement therapy. Conclusions Our observations indicate that the hypogonadal state is associated with increased thymic output of T cells and that this increase in recent thymic emigrants in peripheral blood is reversed by androgen replacement. PMID:21218609

  17. Farm-Level Determinants of output Commercialization:

    African Journals Online (AJOL)

    MARC-AB

    Ethiopian Institute of Agricultural Research. አኀፅሮተ- ... haricot bean output commercialization among smallholder farmers in moisture-stress areas of ..... the American Agricultural Economics Association Annual Meeting, Orlando, Florida, July.

  18. Endogenous Money, Output and Prices in India

    OpenAIRE

    Das, Rituparna

    2009-01-01

    This paper proposes to quantify the macroeconometric relationships among the variables broad money, lending by banks, price, and output in India using simultaneous equations system keeping in view the issue of endogeneity.

  19. Scintillation camera with improved output means

    International Nuclear Information System (INIS)

    Lange, K.; Wiesen, E.J.; Woronowicz, E.M.

    1978-01-01

    In a scintillation camera system, the output pulse signals from an array of photomultiplier tubes are coupled to the inputs of individual preamplifiers. The preamplifier output signals are coupled to circuitry for computing the x and y coordinates of the scintillations. A cathode ray oscilloscope is used to form an image corresponding with the pattern in which radiation is emitted by a body. Means for improving the uniformity and resolution of the scintillations are provided. The means comprise biasing means coupled to the outputs of selected preamplifiers so that output signals below a predetermined amplitude are not suppressed and signals falling within increasing ranges of amplitudes are increasingly suppressed. In effect, the biasing means make the preamplifiers non-linear for selected signal levels

  20. Input-output rearrangement of isolated converters

    DEFF Research Database (Denmark)

    Madsen, Mickey Pierre; Kovacevic, Milovan; Mønster, Jakob Døllner

    2015-01-01

    This paper presents a new way of rearranging the input and output of isolated converters. The new arrangement posses several advantages, as increased voltage range, higher power handling capabilities, reduced voltage stress and improved efficiency, for applications where galvanic isolation...

  1. Multiple Input - Multiple Output (MIMO) SAR

    Data.gov (United States)

    National Aeronautics and Space Administration — This effort will research and implement advanced Multiple-Input Multiple-Output (MIMO) Synthetic Aperture Radar (SAR) techniques which have the potential to improve...

  2. Dosimetric impact of mixed-energy volumetric modulated arc therapy plans for high-risk prostate cancer

    Directory of Open Access Journals (Sweden)

    Shyam Pokharel

    2013-10-01

    Full Text Available Purpose: This study investigated the dosimetric impact of mixing low and high energy treatment plans for prostate cancer treated with volumetric modulated arc therapy (VMAT technique in the form of RapidArc.Methods: A cohort of 12 prostate cases involving proximal seminal vesicles and lymph nodes was selected for this retrospective study. For each prostate case, the single-energy plans (SEPs and mixed-energy plans (MEPs were generated.  First, the SEPs were created using 6 mega-voltage (MV energy for both the primary and boost plans. Second, the MEPs were created using 16 MV energy for the primary plan and 6 MV energy for the boost plan. The primary and boost MEPs used identical beam parameters and same dose optimization values as in the primary and boost SEPs for the corresponding case. The dosimetric parameters from the composite plans (SEPs and MEPs were evaluated. Results: The dose to the target volume was slightly higher (on average <1% in the SEPs than in the MEPs. The conformity index (CI and homogeneity index (HI values between the SEPs and MEPs were comparable. The dose to rectum and bladder was always higher in the SEPs (average difference up to 3.7% for the rectum and up to 8.4% for the bladder than in the MEPs. The mean dose to femoral heads was higher by about 0.8% (on average in the MEPs than in the SEPs. The number of monitor units and integral dose were higher in the SEPs compared to the MEPs by average differences of 9.1% and 5.5%, respectively.Conclusion: The preliminary results from this study suggest that use of mixed-energy VMAT plan for high-risk prostate cancer could potentially reduce the integral dose and minimize the dose to rectum and bladder, but for the higher femoral head dose.-----------------------------------------------Cite this article as:Pokharel S. Dosimetric impact of mixed-energy volumetric modulated arc therapy plans for high-risk prostate cancer. Int J Cancer Ther Oncol 2013;1(1:01011.DOI: http

  3. Automated volumetric breast density estimation: A comparison with visual assessment

    International Nuclear Information System (INIS)

    Seo, J.M.; Ko, E.S.; Han, B.-K.; Ko, E.Y.; Shin, J.H.; Hahn, S.Y.

    2013-01-01

    Aim: To compare automated volumetric breast density (VBD) measurement with visual assessment according to Breast Imaging Reporting and Data System (BI-RADS), and to determine the factors influencing the agreement between them. Materials and methods: One hundred and ninety-three consecutive screening mammograms reported as negative were included in the study. Three radiologists assigned qualitative BI-RADS density categories to the mammograms. An automated volumetric breast-density method was used to measure VBD (% breast density) and density grade (VDG). Each case was classified into an agreement or disagreement group according to the comparison between visual assessment and VDG. The correlation between visual assessment and VDG was obtained. Various physical factors were compared between the two groups. Results: Agreement between visual assessment by the radiologists and VDG was good (ICC value = 0.757). VBD showed a highly significant positive correlation with visual assessment (Spearman's ρ = 0.754, p < 0.001). VBD and the x-ray tube target was significantly different between the agreement group and the disagreement groups (p = 0.02 and 0.04, respectively). Conclusion: Automated VBD is a reliable objective method to measure breast density. The agreement between VDG and visual assessment by radiologist might be influenced by physical factors

  4. Scanners and drillers: Characterizing expert visual search through volumetric images

    Science.gov (United States)

    Drew, Trafton; Vo, Melissa Le-Hoa; Olwal, Alex; Jacobson, Francine; Seltzer, Steven E.; Wolfe, Jeremy M.

    2013-01-01

    Modern imaging methods like computed tomography (CT) generate 3-D volumes of image data. How do radiologists search through such images? Are certain strategies more efficient? Although there is a large literature devoted to understanding search in 2-D, relatively little is known about search in volumetric space. In recent years, with the ever-increasing popularity of volumetric medical imaging, this question has taken on increased importance as we try to understand, and ultimately reduce, errors in diagnostic radiology. In the current study, we asked 24 radiologists to search chest CTs for lung nodules that could indicate lung cancer. To search, radiologists scrolled up and down through a “stack” of 2-D chest CT “slices.” At each moment, we tracked eye movements in the 2-D image plane and coregistered eye position with the current slice. We used these data to create a 3-D representation of the eye movements through the image volume. Radiologists tended to follow one of two dominant search strategies: “drilling” and “scanning.” Drillers restrict eye movements to a small region of the lung while quickly scrolling through depth. Scanners move more slowly through depth and search an entire level of the lung before moving on to the next level in depth. Driller performance was superior to the scanners on a variety of metrics, including lung nodule detection rate, percentage of the lung covered, and the percentage of search errors where a nodule was never fixated. PMID:23922445

  5. Computational assessment of visual search strategies in volumetric medical images.

    Science.gov (United States)

    Wen, Gezheng; Aizenman, Avigael; Drew, Trafton; Wolfe, Jeremy M; Haygood, Tamara Miner; Markey, Mia K

    2016-01-01

    When searching through volumetric images [e.g., computed tomography (CT)], radiologists appear to use two different search strategies: "drilling" (restrict eye movements to a small region of the image while quickly scrolling through slices), or "scanning" (search over large areas at a given depth before moving on to the next slice). To computationally identify the type of image information that is used in these two strategies, 23 naïve observers were instructed with either "drilling" or "scanning" when searching for target T's in 20 volumes of faux lung CTs. We computed saliency maps using both classical two-dimensional (2-D) saliency, and a three-dimensional (3-D) dynamic saliency that captures the characteristics of scrolling through slices. Comparing observers' gaze distributions with the saliency maps showed that search strategy alters the type of saliency that attracts fixations. Drillers' fixations aligned better with dynamic saliency and scanners with 2-D saliency. The computed saliency was greater for detected targets than for missed targets. Similar results were observed in data from 19 radiologists who searched five stacks of clinical chest CTs for lung nodules. Dynamic saliency may be superior to the 2-D saliency for detecting targets embedded in volumetric images, and thus "drilling" may be more efficient than "scanning."

  6. Analytic Intermodel Consistent Modeling of Volumetric Human Lung Dynamics.

    Science.gov (United States)

    Ilegbusi, Olusegun; Seyfi, Behnaz; Neylon, John; Santhanam, Anand P

    2015-10-01

    Human lung undergoes breathing-induced deformation in the form of inhalation and exhalation. Modeling the dynamics is numerically complicated by the lack of information on lung elastic behavior and fluid-structure interactions between air and the tissue. A mathematical method is developed to integrate deformation results from a deformable image registration (DIR) and physics-based modeling approaches in order to represent consistent volumetric lung dynamics. The computational fluid dynamics (CFD) simulation assumes the lung is a poro-elastic medium with spatially distributed elastic property. Simulation is performed on a 3D lung geometry reconstructed from four-dimensional computed tomography (4DCT) dataset of a human subject. The heterogeneous Young's modulus (YM) is estimated from a linear elastic deformation model with the same lung geometry and 4D lung DIR. The deformation obtained from the CFD is then coupled with the displacement obtained from the 4D lung DIR by means of the Tikhonov regularization (TR) algorithm. The numerical results include 4DCT registration, CFD, and optimal displacement data which collectively provide consistent estimate of the volumetric lung dynamics. The fusion method is validated by comparing the optimal displacement with the results obtained from the 4DCT registration.

  7. [Benefits of volumetric to facial rejuvenation. Part 1: Fat grafting].

    Science.gov (United States)

    Bui, P; Lepage, C

    2017-10-01

    For a number of years, a volumetric approach using autologous fat injection has been implemented to improve cosmetic outcome in face-lift procedures and to achieve lasting rejuvenation. Autologous fat as filling tissue has been used in plastic surgery since the late 19th century, but has only recently been associated to face lift procedures. The interest of the association lies on the one hand in the pathophysiology of facial aging, involving skin sag and loss of volume, and on the other hand in the tissue induction properties of grafted fat, "rejuvenating" the injected area. The strict methodology consisting in harvesting, treating then injecting an autologous fat graft is known as LipoStructure ® or lipofilling. We here describe the technique overall, then region by region. It is now well known and seems simple, effective and reproducible, but is nevertheless delicate. For each individual, it is necessary to restore a harmonious face with well-distributed volumes. By associating volumetric to the face lift procedure, the plastic surgeon plays a new role: instead of being a tailor, cutting away excess skin, he or she becomes a sculptor, remodeling the face to restore the harmony of youth. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  8. Volumetric three-dimensional display system with rasterization hardware

    Science.gov (United States)

    Favalora, Gregg E.; Dorval, Rick K.; Hall, Deirdre M.; Giovinco, Michael; Napoli, Joshua

    2001-06-01

    An 8-color multiplanar volumetric display is being developed by Actuality Systems, Inc. It will be capable of utilizing an image volume greater than 90 million voxels, which we believe is the greatest utilizable voxel set of any volumetric display constructed to date. The display is designed to be used for molecular visualization, mechanical CAD, e-commerce, entertainment, and medical imaging. As such, it contains a new graphics processing architecture, novel high-performance line- drawing algorithms, and an API similar to a current standard. Three-dimensional imagery is created by projecting a series of 2-D bitmaps ('image slices') onto a diffuse screen that rotates at 600 rpm. Persistence of vision fuses the slices into a volume-filling 3-D image. A modified three-panel Texas Instruments projector provides slices at approximately 4 kHz, resulting in 8-color 3-D imagery comprised of roughly 200 radially-disposed slices which are updated at 20 Hz. Each slice has a resolution of 768 by 768 pixels, subtending 10 inches. An unusual off-axis projection scheme incorporating tilted rotating optics is used to maintain good focus across the projection screen. The display electronics includes a custom rasterization architecture which converts the user's 3- D geometry data into image slices, as well as 6 Gbits of DDR SDRAM graphics memory.

  9. Three-dimensional volumetric assessment of response to treatment

    International Nuclear Information System (INIS)

    Willett, C.G.; Stracher, M.A.; Linggood, R.M.; Leong, J.C.; Skates, S.J.; Miketic, L.M.; Kushner, D.C.; Jacobson, J.O.

    1988-01-01

    From 1981 to 1986, 12 patients with Stage I and II diffuse large cell lymphoma of the mediastinum were treated with 4 or more cycles of multiagent chemotherapy and for nine patients this was followed by mediastinal irradiation. The response to treatment was assessed by three-dimensional volumetric analysis utilizing thoracic CT scans. The initial mean tumor volume of the five patients relapsing was 540 ml in contrast to an initial mean tumor volume of 360 ml for the seven patients remaining in remission. Of the eight patients in whom mediastinal lymphoma volumes could be assessed 1-2 months after chemotherapy prior to mediastinal irradiation, the three patients who have relapsed had volumes of 292, 92 and 50 ml (mean volume 145 ml) in contrast to five patients who have remained in remission with residual volume abnormalities of 4-87 ml (mean volume 32 ml). Four patients in prolonged remission with CT scans taken one year after treatment have been noted to have mediastinal tumor volumes of 0-28 ml with a mean value of 10 ml. This volumetric technique to assess the extent of mediastinal large cell lymphoma from thoracic CT scans appears to be a useful method to quantitate the amount of disease at presentation as well as objectively monitor response to treatment. 13 refs.; 2 figs.; 1 table

  10. A spiral-based volumetric acquisition for MR temperature imaging.

    Science.gov (United States)

    Fielden, Samuel W; Feng, Xue; Zhao, Li; Miller, G Wilson; Geeslin, Matthew; Dallapiazza, Robert F; Elias, W Jeffrey; Wintermark, Max; Butts Pauly, Kim; Meyer, Craig H

    2018-06-01

    To develop a rapid pulse sequence for volumetric MR thermometry. Simulations were carried out to assess temperature deviation, focal spot distortion/blurring, and focal spot shift across a range of readout durations and maximum temperatures for Cartesian, spiral-out, and retraced spiral-in/out (RIO) trajectories. The RIO trajectory was applied for stack-of-spirals 3D imaging on a real-time imaging platform and preliminary evaluation was carried out compared to a standard 2D sequence in vivo using a swine brain model, comparing maximum and mean temperatures measured between the two methods, as well as the temporal standard deviation measured by the two methods. In simulations, low-bandwidth Cartesian trajectories showed substantial shift of the focal spot, whereas both spiral trajectories showed no shift while maintaining focal spot geometry. In vivo, the 3D sequence achieved real-time 4D monitoring of thermometry, with an update time of 2.9-3.3 s. Spiral imaging, and RIO imaging in particular, is an effective way to speed up volumetric MR thermometry. Magn Reson Med 79:3122-3127, 2018. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.

  11. Spatio-volumetric hazard estimation in the Auckland volcanic field

    Science.gov (United States)

    Bebbington, Mark S.

    2015-05-01

    The idea of a volcanic field `boundary' is prevalent in the literature, but ill-defined at best. We use the elliptically constrained vents in the Auckland Volcanic Field to examine how spatial intensity models can be tested to assess whether they are consistent with such features. A means of modifying the anisotropic Gaussian kernel density estimate to reflect the existence of a `hard' boundary is then suggested, and the result shown to reproduce the observed elliptical distribution. A new idea, that of a spatio-volumetric model, is introduced as being more relevant to hazard in a monogenetic volcanic field than the spatiotemporal hazard model due to the low temporal rates in volcanic fields. Significant dependencies between the locations and erupted volumes of the observed centres are deduced, and expressed in the form of a spatially-varying probability density. In the future, larger volumes are to be expected in the `gaps' between existing centres, with the location of the greatest forecast volume lying in the shipping channel between Rangitoto and Castor Bay. The results argue for tectonic control over location and magmatic control over erupted volume. The spatio-volumetric model is consistent with the hypothesis of a flat elliptical area in the mantle where tensional stresses, related to the local tectonics and geology, allow decompressional melting.

  12. Performance-scalable volumetric data classification for online industrial inspection

    Science.gov (United States)

    Abraham, Aby J.; Sadki, Mustapha; Lea, R. M.

    2002-03-01

    Non-intrusive inspection and non-destructive testing of manufactured objects with complex internal structures typically requires the enhancement, analysis and visualization of high-resolution volumetric data. Given the increasing availability of fast 3D scanning technology (e.g. cone-beam CT), enabling on-line detection and accurate discrimination of components or sub-structures, the inherent complexity of classification algorithms inevitably leads to throughput bottlenecks. Indeed, whereas typical inspection throughput requirements range from 1 to 1000 volumes per hour, depending on density and resolution, current computational capability is one to two orders-of-magnitude less. Accordingly, speeding up classification algorithms requires both reduction of algorithm complexity and acceleration of computer performance. A shape-based classification algorithm, offering algorithm complexity reduction, by using ellipses as generic descriptors of solids-of-revolution, and supporting performance-scalability, by exploiting the inherent parallelism of volumetric data, is presented. A two-stage variant of the classical Hough transform is used for ellipse detection and correlation of the detected ellipses facilitates position-, scale- and orientation-invariant component classification. Performance-scalability is achieved cost-effectively by accelerating a PC host with one or more COTS (Commercial-Off-The-Shelf) PCI multiprocessor cards. Experimental results are reported to demonstrate the feasibility and cost-effectiveness of the data-parallel classification algorithm for on-line industrial inspection applications.

  13. Volumetric Synthetic Aperture Imaging with a Piezoelectric 2-D Row-Column Probe

    DEFF Research Database (Denmark)

    Bouzari, Hamed; Engholm, Mathias; Christiansen, Thomas Lehrmann

    2016-01-01

    The synthetic aperture (SA) technique can be used for achieving real-time volumetric ultrasound imaging using 2-D row-column addressed transducers. This paper investigates SA volumetric imaging performance of an in-house prototyped 3 MHz λ/2-pitch 62+62 element piezoelectric 2-D row-column addres......The synthetic aperture (SA) technique can be used for achieving real-time volumetric ultrasound imaging using 2-D row-column addressed transducers. This paper investigates SA volumetric imaging performance of an in-house prototyped 3 MHz λ/2-pitch 62+62 element piezoelectric 2-D row...

  14. 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

    . This is the first method to estimate volumetric time-varying images from single MV cine EPID images, and has the potential to provide volumetric information with no additional imaging dose to the patient.

  15. SU-G-BRC-04: Collimator Angle Optimization in Volumetric Modulated Arc Therapy

    Energy Technology Data Exchange (ETDEWEB)

    Andersen, A; Johnson, C; Bartlett, G; Das, I [Indiana University- School of Medicine, Indianapolis, IN (United States)

    2016-06-15

    Purpose: Volumetric modulated arc therapy (VMAT) has revolutionized radiation treatment by decreasing treatment time and monitor units, thus reducing scattered and whole body radiation dose. As the collimator angle changes the apparent leaf gap becomes larger which can impact plan quality, organ at risk (OAR) sparing as well as IMRT QA passing rate which is investigated. Methods: Two sites (prostate and head and neck) that have maximum utilization of VMAT were investigated. Two previously treated VMAT patients were chosen. For each patient 10 plans were created by maintaining constant optimization constraints while varying collimator angles from 0-90 deg at an interval of 10 degrees for the first arc and the appropriate complimentary angle for the second arc. Plans were created with AAA algorithm using 6 MV beam on a Varian IX machine with Millennium 120 MLC. The dose-volume histogram (DVH) for each plan was exported and dosimetric parameters (D98, D95, D50, D2) as well homogeneity index (HI) and conformity index (CI) were computed. Each plan was validated for QA using ArcCheck with gamma index passing criteria of 2%/2 mm and 3%/3 mm. Additionally, normal tissue complication probability (NTCP) for each OAR was computed using Uzan-Nahum software. Results: The CI values for both sites had no impact as target volume coverage in every collimator angle were the same since it was optimized for adequate coverage. The HI which is representative of DVH gradient or dose uniformity in PTV showed a clear trend in both sites. The NTCP for OAR (brain and cochlea) in H&N plan and (bladder and rectum) in prostate plan showed a distinct superiority for collimator angles between 15-30 deg. The gamma passing rates were not correlated with angle. Conclusion: Based on CI, HI, NTCP and gamma passing index, it can be concluded that collimator angles should be maintained within 15–30 deg.

  16. SU-G-BRC-04: Collimator Angle Optimization in Volumetric Modulated Arc Therapy

    International Nuclear Information System (INIS)

    Andersen, A; Johnson, C; Bartlett, G; Das, I

    2016-01-01

    Purpose: Volumetric modulated arc therapy (VMAT) has revolutionized radiation treatment by decreasing treatment time and monitor units, thus reducing scattered and whole body radiation dose. As the collimator angle changes the apparent leaf gap becomes larger which can impact plan quality, organ at risk (OAR) sparing as well as IMRT QA passing rate which is investigated. Methods: Two sites (prostate and head and neck) that have maximum utilization of VMAT were investigated. Two previously treated VMAT patients were chosen. For each patient 10 plans were created by maintaining constant optimization constraints while varying collimator angles from 0-90 deg at an interval of 10 degrees for the first arc and the appropriate complimentary angle for the second arc. Plans were created with AAA algorithm using 6 MV beam on a Varian IX machine with Millennium 120 MLC. The dose-volume histogram (DVH) for each plan was exported and dosimetric parameters (D98, D95, D50, D2) as well homogeneity index (HI) and conformity index (CI) were computed. Each plan was validated for QA using ArcCheck with gamma index passing criteria of 2%/2 mm and 3%/3 mm. Additionally, normal tissue complication probability (NTCP) for each OAR was computed using Uzan-Nahum software. Results: The CI values for both sites had no impact as target volume coverage in every collimator angle were the same since it was optimized for adequate coverage. The HI which is representative of DVH gradient or dose uniformity in PTV showed a clear trend in both sites. The NTCP for OAR (brain and cochlea) in H&N plan and (bladder and rectum) in prostate plan showed a distinct superiority for collimator angles between 15-30 deg. The gamma passing rates were not correlated with angle. Conclusion: Based on CI, HI, NTCP and gamma passing index, it can be concluded that collimator angles should be maintained within 15–30 deg.

  17. Volumetric modulated arc therapy for delivery of hypofractionated stereotactic lung radiotherapy: A dosimetric and treatment efficiency analysis

    International Nuclear Information System (INIS)

    McGrath, Samuel D.; Matuszak, Martha M.; Yan Di; Kestin, Larry L.; Martinez, Alvaro A.; Grills, Inga S.

    2010-01-01

    Purpose/objective(s): Volumetric modulated arc therapy (VMAT) allows for intensity-modulated radiation delivery during gantry rotation with dynamic MLC motion, variable dose rates and gantry speed modulation. We compared VMAT plans with 3D-CRT for hypofractionated lung radiotherapy. Materials/methods: Twenty-one 3D-CRT plans for Stage IA lung cancer previously treated stereotactically were selected. VMAT plans were generated by optimizing machine aperture shape and radiation intensity at 10 deg. intervals. A partial arc range of 180 deg. was manually selected to coincide with tumor location. The arc was resampled down to 5 deg. intervals to ensure dose calculation accuracy. Identical planning objectives were used for VMAT/3D-CRT. Parameters assessed included dose to PTV and organs-at-risk (OAR), monitor units, and multiple conformity and homogeneity indices. Plans were delivered to a phantom for time comparison. Results: Lung V 20/12.5/10/5 were less with VMAT (relative reduction 4.5%, p = .02; 3.2%, p = .01; 2.6%, p = .01; 4.2%, p = .03, respectively). Mean/maximum-doses to PTV, dose to additional OARs, 95% isodose line conformity, and target volume homogeneity were equivalent. VMAT improved conformity at both the 80% (1.87 vs. 1.93, p = .08) and 50% isodose lines (5.19 vs. 5.65, p = .01). Treatment times were reduced significantly with VMAT (mean 6.1 vs. 11.9 min, p < .01). Conclusions: Single arc VMAT planning achieves highly conformal dose distributions while controlling dose to critical structures, including significant reduction in lung dose volume parameters. Employing a VMAT technique decreases treatment times by 37-63%, reducing the chance of error introduced by intrafraction variation. The quality and efficiency of VMAT is ideally suited for stereotactic lung radiotherapy delivery.

  18. SU-E-T-604: Dosimetric Dependence On the Collimator Angle in Prostate Volumetric Modulated Arc Therapy

    International Nuclear Information System (INIS)

    Khan, M; Rehman, J; Khan, M; Chow, J

    2014-01-01

    Purpose: The purpose of this study is to investigate the dose-volume variations of planning target volume (PTV) and organs-at-risk (OARs) in prostate volumetric modulated arc therapy (VMAT) when using different collimator angles. It is because collimator angle awareness is essential for planner to produce an optimal prostate VMAT plan in a rational time. Methods: Single-arc VMAT plans at different collimator angles (0o, 15o, 30o, 45o, 60o, 75o and 90o) were created systematically using a Harold heterogeneous pelvis phantom. For each change of collimator angle, a new plan was re-optimized for that angle. The prescription dose was 78 Gy per 39 fractions. Conformity index (CI), homogeneity index (HI), gradient index, machine monitor unit, dose-volume histogram, the mean and maximum doses of the PTV were calculated and analyzed. On the other hand, dose-volume histogram, the mean and maximum doses of the OARs such as bladder, rectum and femoral heads for different collimator angles were determined from the plans. Results: There was no significance difference, based on the plan dose-volume evaluation criteria, found in the VMAT optimizations for all studied collimator angles. Higher CI and lower HI were found for the 45o collimator angle. In addition, the 15o collimator angle provided lower HI similar to the 45o collimator angle. The 75o and 90o collimator angle were found good for the rectum sparing, and the 75o and 30o collimator angle were found good for the right and left femur sparing, respectively. The PTV dose coverage for each plan was comparatively independent of the collimator angle. Conclusion: The dosimetric results in this study are useful to the planner to select different collimator angles to improve the PTV coverage and OAR sparing in prostate VMAT

  19. SU-E-T-604: Dosimetric Dependence On the Collimator Angle in Prostate Volumetric Modulated Arc Therapy

    Energy Technology Data Exchange (ETDEWEB)

    Khan, M; Rehman, J; Khan, M [The Islaimia University of Bahawalpur, Bahawalpur, Punjab (Pakistan); Chow, J [Princess Margaret Cancer Center, Toronto, ON (Canada)

    2014-06-01

    Purpose: The purpose of this study is to investigate the dose-volume variations of planning target volume (PTV) and organs-at-risk (OARs) in prostate volumetric modulated arc therapy (VMAT) when using different collimator angles. It is because collimator angle awareness is essential for planner to produce an optimal prostate VMAT plan in a rational time. Methods: Single-arc VMAT plans at different collimator angles (0o, 15o, 30o, 45o, 60o, 75o and 90o) were created systematically using a Harold heterogeneous pelvis phantom. For each change of collimator angle, a new plan was re-optimized for that angle. The prescription dose was 78 Gy per 39 fractions. Conformity index (CI), homogeneity index (HI), gradient index, machine monitor unit, dose-volume histogram, the mean and maximum doses of the PTV were calculated and analyzed. On the other hand, dose-volume histogram, the mean and maximum doses of the OARs such as bladder, rectum and femoral heads for different collimator angles were determined from the plans. Results: There was no significance difference, based on the plan dose-volume evaluation criteria, found in the VMAT optimizations for all studied collimator angles. Higher CI and lower HI were found for the 45o collimator angle. In addition, the 15o collimator angle provided lower HI similar to the 45o collimator angle. The 75o and 90o collimator angle were found good for the rectum sparing, and the 75o and 30o collimator angle were found good for the right and left femur sparing, respectively. The PTV dose coverage for each plan was comparatively independent of the collimator angle. Conclusion: The dosimetric results in this study are useful to the planner to select different collimator angles to improve the PTV coverage and OAR sparing in prostate VMAT.

  20. Critical structure sparing in stereotactic ablative radiotherapy for central lung lesions: helical tomotherapy vs. volumetric modulated arc therapy.

    Directory of Open Access Journals (Sweden)

    Alexander Chi

    Full Text Available BACKGROUND: Helical tomotherapy (HT and volumetric modulated arc therapy (VMAT are both advanced techniques of delivering intensity-modulated radiotherapy (IMRT. Here, we conduct a study to compare HT and partial-arc VMAT in their ability to spare organs at risk (OARs when stereotactic ablative radiotherapy (SABR is delivered to treat centrally located early stage non-small-cell lung cancer or lung metastases. METHODS: 12 patients with centrally located lung lesions were randomly chosen. HT, 2 & 8 arc (Smart Arc, Pinnacle v9.0 plans were generated to deliver 70 Gy in 10 fractions to the planning target volume (PTV. Target and OAR dose parameters were compared. Each technique's ability to meet dose constraints was further investigated. RESULTS: HT and VMAT plans generated essentially equivalent PTV coverage and dose conformality indices, while a trend for improved dose homogeneity by increasing from 2 to 8 arcs was observed with VMAT. Increasing the number of arcs with VMAT also led to some improvement in OAR sparing. After normalizing to OAR dose constraints, HT was found to be superior to 2 or 8-arc VMAT for optimal OAR sparing (meeting all the dose constraints (p = 0.0004. All dose constraints were met in HT plans. Increasing from 2 to 8 arcs could not help achieve optimal OAR sparing for 4 patients. 2/4 of them had 3 immediately adjacent structures. CONCLUSION: HT appears to be superior to VMAT in OAR sparing mainly in cases which require conformal dose avoidance of multiple immediately adjacent OARs. For such cases, increasing the number of arcs in VMAT cannot significantly improve OAR sparing.

  1. Volumetric response analysis during chemoradiation as predictive tool for optimizing treatment strategy in locally advanced unresectable NSCLC

    International Nuclear Information System (INIS)

    Bral, Samuel; Duchateau, Michael; De Ridder, Mark; Everaert, Hendrik; Tournel, Koen; Schallier, Denis; Verellen, Dirk; Storme, Guy

    2009-01-01

    Purpose: To study the feasibility of measuring volumetric changes in the primary tumor on megavoltage-computed tomography (MVCT) during chemoradiation and to examine the correlation with local response. Patients and methods: Fifteen consecutive patients with stage III, inoperable, locally advanced non-small cell lung cancer (NSCLC) were treated in a prospective dose escalation study protocol of concurrent chemoradiation. They were monitored for acute toxicity and evaluated with daily MVCT imaging. The volumetric changes were fitted to a negative exponential resulting in a regression coefficient (RC). Local response evaluation was done with positron emission tomography using the radio-labeled glucose analogue F18 fluorodeoxyglucose (FDG-PET). Results: The mean volume decrease (±standard deviation) was 73% (±18%). With a mean treatment time of 42 days this treatment schedule resulted in a mean decrease of 1.74%/day. Of the 13 evaluable patients seven developed a metabolic complete remission (MCR). The mean RC of the patients with MCR is 0.050 versus a mean RC of 0.023 in non-responders (p = 0.0074). Using a proposed cut-off value for the RC of 0.03 80% of the non-responders will be detected correctly while misclassifying 16.4% of patients who will eventually achieve an MCR. The total cumulative percentage of esophageal grade 3 or more toxicity was 46.7%. Conclusion: The RC derived from volumetric analysis of daily MVCT is prognostic and predictive for local response in patients treated with chemoradiation for a locally advanced NSCLC. Because this treatment schedule is toxic in nearly half of the patient population, MVCT is a tool in the implementation of patient-individualized treatment strategies.

  2. Long-term stability of beam quality and output of conventional X-ray units

    OpenAIRE

    Fukuda, Atsushi; Matsubara, Kosuke; Miyati, Toshiaki

    2015-01-01

    Conventional diagnostic X-ray units are used for radiographic imaging in many countries. For obtaining entrance surface doses, a numerical dose determination method has been applied in Japan. Although this technique is effective, it has to account for errors, particularly fluctuations, due to the beam quality and output of X-ray tubes. As a part of our quality control procedures, we recorded the entrance surface air kerma, tube voltage, and half-value layer measurements made for four diagnost...

  3. Estimating pediatric entrance skin dose from digital radiography examination using DICOM metadata: A quality assurance tool

    Energy Technology Data Exchange (ETDEWEB)

    Brady, S. L., E-mail: samuel.brady@stjude.org; Kaufman, R. A., E-mail: robert.kaufman@stjude.org [Department of Diagnostic Imaging, St. Jude Children’s Research Hospital, Memphis, Tennessee 38105 (United States)

    2015-05-15

    Purpose: To develop an automated methodology to estimate patient examination dose in digital radiography (DR) imaging using DICOM metadata as a quality assurance (QA) tool. Methods: Patient examination and demographical information were gathered from metadata analysis of DICOM header data. The x-ray system radiation output (i.e., air KERMA) was characterized for all filter combinations used for patient examinations. Average patient thicknesses were measured for head, chest, abdomen, knees, and hands using volumetric images from CT. Backscatter factors (BSFs) were calculated from examination kVp. Patient entrance skin air KERMA (ESAK) was calculated by (1) looking up examination technique factors taken from DICOM header metadata (i.e., kVp and mA s) to derive an air KERMA (k{sub air}) value based on an x-ray characteristic radiation output curve; (2) scaling k{sub air} with a BSF value; and (3) correcting k{sub air} for patient thickness. Finally, patient entrance skin dose (ESD) was calculated by multiplying a mass–energy attenuation coefficient ratio by ESAK. Patient ESD calculations were computed for common DR examinations at our institution: dual view chest, anteroposterior (AP) abdomen, lateral (LAT) skull, dual view knee, and bone age (left hand only) examinations. Results: ESD was calculated for a total of 3794 patients; mean age was 11 ± 8 yr (range: 2 months to 55 yr). The mean ESD range was 0.19–0.42 mGy for dual view chest, 0.28–1.2 mGy for AP abdomen, 0.18–0.65 mGy for LAT view skull, 0.15–0.63 mGy for dual view knee, and 0.10–0.12 mGy for bone age (left hand) examinations. Conclusions: A methodology combining DICOM header metadata and basic x-ray tube characterization curves was demonstrated. In a regulatory era where patient dose reporting has become increasingly in demand, this methodology will allow a knowledgeable user the means to establish an automatable dose reporting program for DR and perform patient dose related QA testing for

  4. Residual gravimetric method to measure nebulizer output.

    Science.gov (United States)

    Vecellio None, Laurent; Grimbert, Daniel; Bordenave, Joelle; Benoit, Guy; Furet, Yves; Fauroux, Brigitte; Boissinot, Eric; De Monte, Michele; Lemarié, Etienne; Diot, Patrice

    2004-01-01

    The aim of this study was to assess a residual gravimetric method based on weighing dry filters to measure the aerosol output of nebulizers. This residual gravimetric method was compared to assay methods based on spectrophotometric measurement of terbutaline (Bricanyl, Astra Zeneca, France), high-performance liquid chromatography (HPLC) measurement of tobramycin (Tobi, Chiron, U.S.A.), and electrochemical measurements of NaF (as defined by the European standard). Two breath-enhanced jet nebulizers, one standard jet nebulizer, and one ultrasonic nebulizer were tested. Output produced by the residual gravimetric method was calculated by weighing the filters both before and after aerosol collection and by filter drying corrected by the proportion of drug contained in total solute mass. Output produced by the electrochemical, spectrophotometric, and HPLC methods was determined after assaying the drug extraction filter. The results demonstrated a strong correlation between the residual gravimetric method (x axis) and assay methods (y axis) in terms of drug mass output (y = 1.00 x -0.02, r(2) = 0.99, n = 27). We conclude that a residual gravimetric method based on dry filters, when validated for a particular agent, is an accurate way of measuring aerosol output.

  5. Output characteristics of Stirling thermoacoustic engine

    International Nuclear Information System (INIS)

    Sun Daming; Qiu Limin; Wang Bo; Xiao Yong; Zhao Liang

    2008-01-01

    A thermoacoustic engine (TE), which converts thermal energy into acoustic power by the thermoacoustic effect, shows several advantages due to the absence of moving parts, such as high reliability and long lifetime associated with reduced manufacturing costs. Power output and efficiency are important criteria of the performance of a TE. In order to increase the acoustic power output and thermal efficiency of a Stirling TE, the acoustic power distribution in the engine is studied with the variable load method. It is found that the thermal efficiency is independent of the output locations along the engine under the same acoustic power output. Furthermore, when the pressure ratio is kept constant at one location along the TE, it is beneficial to increasing the thermal efficiency by exporting more acoustic power. With nitrogen of 2.5 MPa as working gas and the pressure ratio at the compliance of 1.20 in the experiments, the acoustic power is measured at the compliance and the resonator simultaneously. The maximum power output, thermal efficiency and exergy efficiency reach 390.0 W, 11.2% and 16.0%, which are increased by 51.4%, 24.4% and 19.4%, respectively, compared to those with a single R-C load with 750 ml reservoir at the compliance. This research will be instructive for increasing the efficiency and making full use of the acoustic energy of a TE

  6. Estimation of international output-energy relation. Effects of alternative output measures

    International Nuclear Information System (INIS)

    Shrestha, R.M.

    2000-01-01

    This paper analyzes the output-energy relationship with alternative measures of output and energy. Our analysis rejects the hypothesis of non-diminishing returns to energy consumption when GDP at purchasing power parities is used as the output measure unlike the case with GNP at market exchange rates. This finding also holds when energy input includes the usage of both commercial and traditional fuels. 13 refs

  7. From Static Output Feedback to Structured Robust Static Output Feedback: A Survey

    OpenAIRE

    Sadabadi , Mahdieh ,; Peaucelle , Dimitri

    2016-01-01

    This paper reviews the vast literature on static output feedback design for linear time-invariant systems including classical results and recent developments. In particular, we focus on static output feedback synthesis with performance specifications, structured static output feedback, and robustness. The paper provides a comprehensive review on existing design approaches including iterative linear matrix inequalities heuristics, linear matrix inequalities with rank constraints, methods with ...

  8. Dose limits

    International Nuclear Information System (INIS)

    Fitoussi, L.

    1987-12-01

    The dose limit is defined to be the level of harmfulness which must not be exceeded, so that an activity can be exercised in a regular manner without running a risk unacceptable to man and the society. The paper examines the effects of radiation categorised into stochastic and non-stochastic. Dose limits for workers and the public are discussed

  9. Natural convection in wavy enclosures with volumetric heat sources

    International Nuclear Information System (INIS)

    Oztop, H.F.; Varol, Y.; Abu-Nada, E.; Chamkha, A.

    2011-01-01

    In this paper, the effects of volumetric heat sources on natural convection heat transfer and flow structures in a wavy-walled enclosure are studied numerically. The governing differential equations are solved by an accurate finite-volume method. The vertical walls of enclosure are assumed to be heated differentially whereas the two wavy walls (top and bottom) are kept adiabatic. The effective governing parameters for this problem are the internal and external Rayleigh numbers and the amplitude of wavy walls. It is found that both the function of wavy wall and the ratio of internal Rayleigh number (Ra I ) to external Rayleigh number (Ra E ) affect the heat transfer and fluid flow significantly. The heat transfer is predicted to be a decreasing function of waviness of the top and bottom walls in case of (IRa/ERa)>1 and (IRa/ERa)<1. (authors)

  10. Quantitative volumetric Raman imaging of three dimensional cell cultures

    KAUST Repository

    Kallepitis, Charalambos

    2017-03-22

    The ability to simultaneously image multiple biomolecules in biologically relevant three-dimensional (3D) cell culture environments would contribute greatly to the understanding of complex cellular mechanisms and cell–material interactions. Here, we present a computational framework for label-free quantitative volumetric Raman imaging (qVRI). We apply qVRI to a selection of biological systems: human pluripotent stem cells with their cardiac derivatives, monocytes and monocyte-derived macrophages in conventional cell culture systems and mesenchymal stem cells inside biomimetic hydrogels that supplied a 3D cell culture environment. We demonstrate visualization and quantification of fine details in cell shape, cytoplasm, nucleus, lipid bodies and cytoskeletal structures in 3D with unprecedented biomolecular specificity for vibrational microspectroscopy.

  11. Thermal expansion and volumetric changes during indium phosphide melting

    International Nuclear Information System (INIS)

    Glazov, V.M.; Davletov, K.; Nashel'skij, A.Ya.; Mamedov, M.M.

    1977-01-01

    The results of the measurements of a thermal expansion were summed up at various temperatures as a diagram in coordinates (Δ 1/1) approximately F(t). It was shown that an appreciable deviation of the relationship (Δ1/1) approximately f(t) from the linear law corresponded to a temperature of 500-550 deg C. It was noted that the said deviation was related to an appreciable thermal decomposition of indium phosphide as temperature increased. The strength of the inter-atomic bond of indium phosphide was calculated. Investigated were the volumetric changes of indium phosphide on melting. The resultant data were analyzed with the aid of the Clausius-Clapeyron equation

  12. Volumetric multimodality neural network for brain tumor segmentation

    Science.gov (United States)

    Silvana Castillo, Laura; Alexandra Daza, Laura; Carlos Rivera, Luis; Arbeláez, Pablo

    2017-11-01

    Brain lesion segmentation is one of the hardest tasks to be solved in computer vision with an emphasis on the medical field. We present a convolutional neural network that produces a semantic segmentation of brain tumors, capable of processing volumetric data along with information from multiple MRI modalities at the same time. This results in the ability to learn from small training datasets and highly imbalanced data. Our method is based on DeepMedic, the state of the art in brain lesion segmentation. We develop a new architecture with more convolutional layers, organized in three parallel pathways with different input resolution, and additional fully connected layers. We tested our method over the 2015 BraTS Challenge dataset, reaching an average dice coefficient of 84%, while the standard DeepMedic implementation reached 74%.

  13. Green chemistry volumetric titration kit for pharmaceutical formulations: Econoburette

    Directory of Open Access Journals (Sweden)

    Man Singh

    2009-08-01

    Full Text Available Stopcock SC and Spring Sp models of Econoburette (Calibrated, RTC (NR, Ministry of Small Scale Industries, Government of India, developed for semimicro volumetric titration of pharmaceutical formulations are reported. These are economized and risk free titration where pipette is replaced by an inbuilt pipette and conical flask by inbuilt bulb. A step of pipetting of stock solution by mouth is deleted. It is used to allow solution exposure to user’s body. This risk is removed and even volatile and toxic solutions are titrated with full proof safety. Econoburette minimizes use of materials and time by 90 % and prevent discharge of polluting effluent to environment. Few acid and base samples are titrated and an analysis of experimental expenditure is described in the papers.

  14. Volumetric dispenser for small particles from plural sources

    International Nuclear Information System (INIS)

    Bradley, R.A.; Miller, W.H.; Sease, J.D.

    1975-01-01

    Apparatus is described for rapidly and accurately dispensing measured volumes of small particles from a supply hopper. The apparatus includes an adjustable, vertically oriented measuring tube and orifice member defining the volume to be dispensed, a ball plug valve for selectively closing the bottom end of the orifice member, and a compression valve for selectively closing the top end of the measuring tube. A supply hopper is disposed above and in gravity flow communication with the measuring tube. Properly sequenced opening and closing of the two valves provides accurate volumetric discharge through the ball plug valve. A dispensing system is described wherein several appropriately sized measuring tubes, orifice members, and associated valves are arranged to operate contemporaneously to facilitate blending of different particles

  15. Optimization approaches to volumetric modulated arc therapy planning

    Energy Technology Data Exchange (ETDEWEB)

    Unkelbach, Jan, E-mail: junkelbach@mgh.harvard.edu; Bortfeld, Thomas; Craft, David [Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114 (United States); Alber, Markus [Department of Medical Physics and Department of Radiation Oncology, Aarhus University Hospital, Aarhus C DK-8000 (Denmark); Bangert, Mark [Department of Medical Physics in Radiation Oncology, German Cancer Research Center, Heidelberg D-69120 (Germany); Bokrantz, Rasmus [RaySearch Laboratories, Stockholm SE-111 34 (Sweden); Chen, Danny [Department of Computer Science and Engineering, University of Notre Dame, Notre Dame, Indiana 46556 (United States); Li, Ruijiang; Xing, Lei [Department of Radiation Oncology, Stanford University, Stanford, California 94305 (United States); Men, Chunhua [Department of Research, Elekta, Maryland Heights, Missouri 63043 (United States); Nill, Simeon [Joint Department of Physics at The Institute of Cancer Research and The Royal Marsden NHS Foundation Trust, London SM2 5NG (United Kingdom); Papp, Dávid [Department of Mathematics, North Carolina State University, Raleigh, North Carolina 27695 (United States); Romeijn, Edwin [H. Milton Stewart School of Industrial and Systems Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States); Salari, Ehsan [Department of Industrial and Manufacturing Engineering, Wichita State University, Wichita, Kansas 67260 (United States)

    2015-03-15

    Volumetric modulated arc therapy (VMAT) has found widespread clinical application in recent years. A large number of treatment planning studies have evaluated the potential for VMAT for different disease sites based on the currently available commercial implementations of VMAT planning. In contrast, literature on the underlying mathematical optimization methods used in treatment planning is scarce. VMAT planning represents a challenging large scale optimization problem. In contrast to fluence map optimization in intensity-modulated radiotherapy planning for static beams, VMAT planning represents a nonconvex optimization problem. In this paper, the authors review the state-of-the-art in VMAT planning from an algorithmic perspective. Different approaches to VMAT optimization, including arc sequencing methods, extensions of direct aperture optimization, and direct optimization of leaf trajectories are reviewed. Their advantages and limitations are outlined and recommendations for improvements are discussed.

  16. Stability and Volumetric Properties of Asphalt Mixture Containing Waste Plastic

    Directory of Open Access Journals (Sweden)

    Abd Kader Siti Aminah

    2017-01-01

    Full Text Available The objectives of this study are to determine the optimum bitumen content (OBC for every percentage added of waste plastics in asphalt mixtures and to investigate the stability properties of the asphalt mixtures containing waste plastic. Marshall stability and flow values along with density, air voids in total mix, voids in mineral aggregate, and voids filled with bitumen were determined to obtain OBC at different percentages of waste plastic, i.e., 4%, 6%, 8%, and 10% by weight of bitumen as additive. Results showed that the OBC for the plastic-modified asphalt mixtures at 4%, 6%, 8%, and 10% are 4.98, 5.44, 5.48, and 5.14, respectively. On the other hand, the controlled specimen’s shows better volumetric properties compared to plastic mixes. However, 4% additional of waste plastic indicated better stability than controlled specimen.

  17. Quantitative volumetric Raman imaging of three dimensional cell cultures

    Science.gov (United States)

    Kallepitis, Charalambos; Bergholt, Mads S.; Mazo, Manuel M.; Leonardo, Vincent; Skaalure, Stacey C.; Maynard, Stephanie A.; Stevens, Molly M.

    2017-03-01

    The ability to simultaneously image multiple biomolecules in biologically relevant three-dimensional (3D) cell culture environments would contribute greatly to the understanding of complex cellular mechanisms and cell-material interactions. Here, we present a computational framework for label-free quantitative volumetric Raman imaging (qVRI). We apply qVRI to a selection of biological systems: human pluripotent stem cells with their cardiac derivatives, monocytes and monocyte-derived macrophages in conventional cell culture systems and mesenchymal stem cells inside biomimetic hydrogels that supplied a 3D cell culture environment. We demonstrate visualization and quantification of fine details in cell shape, cytoplasm, nucleus, lipid bodies and cytoskeletal structures in 3D with unprecedented biomolecular specificity for vibrational microspectroscopy.

  18. Impact of Volumetric Modulated Arc Therapy Technique on Treatment With Partial Breast Irradiation

    International Nuclear Information System (INIS)

    Qiu Jianjian; Chang Zheng; Wu, Q. Jackie; Yoo, Sua; Horton, Janet; Yin Fangfang

    2010-01-01

    Purpose: To investigate the technical feasibility of volumetric modulated arc therapy (V-MAT) in the delivery of partial breast irradiation (PBI). Methods and Materials: V-MAT and the standard, three-dimensional conformal radiotherapy (3D-CRT), were compared retrospectively in 8 patients previously treated with PBI. These patients' plans were replanned with a single partial arc using V-MAT that included partial blocking to minimize normal tissue dose. Dosimetric parameters were calculated to evaluate plan quality. Quality assurance studies included verifying both the point and the multiple planar doses. Total monitor units and delivery time were also evaluated, and collision clearance was analyzed. Results: Volumes of ipsilateral lung irradiated to 10 Gy (V10) and 20 Gy (V20) by V-MAT were significantly less than those of 3D-CRT (p = 0.03 for V10 and p = 0.025 for V20). The volume of ipsilateral breast irradiated to 5 Gy was significantly less by using V-MAT than with 3D-CRT (p = 0.02), with a ratio of integrated dose of <1.00. The total mean monitor units (489 ± 38) for V-MAT were significantly less than those for 3D-CRT (634 ± 123) (p = 0.017), with a 23% reduction. The average machine delivery time was 1.21 ± 0.10 min for the V-MAT plans and 6.28 ± 1.40 min for the 3D-CRT plans, resulting in a reduction factor of 80.1%. The conformity indexes were 1.3 in the V-MAT plans and 1.5 in the 3D-CRT plans (p = 0.102). Conclusions: V-MAT technology is feasible for PBI patients. Compared to a conventional 3D-CRT technique, it is more efficient, offers equivalent or better dose conformity, delivers lower doses to the ipsilateral lung and breast, and may potentially reduce intrafractional motion.

  19. Problems in Modelling Charge Output Accelerometers

    Directory of Open Access Journals (Sweden)

    Tomczyk Krzysztof

    2016-12-01

    Full Text Available The paper presents major issues associated with the problem of modelling change output accelerometers. The presented solutions are based on the weighted least squares (WLS method using transformation of the complex frequency response of the sensors. The main assumptions of the WLS method and a mathematical model of charge output accelerometers are presented in first two sections of this paper. In the next sections applying the WLS method to estimation of the accelerometer model parameters is discussed and the associated uncertainties are determined. Finally, the results of modelling a PCB357B73 charge output accelerometer are analysed in the last section of this paper. All calculations were executed using the MathCad software program. The main stages of these calculations are presented in Appendices A−E.

  20. Benchmark calculations for evaluation methods of gas volumetric leakage rate

    International Nuclear Information System (INIS)

    Asano, R.; Aritomi, M.; Matsuzaki, M.

    1998-01-01

    A containment function of radioactive materials transport casks is essential for safe transportation to prevent the radioactive materials from being released into environment. Regulations such as IAEA standard determined the limit of radioactivity to be released. Since is not practical for the leakage tests to measure directly the radioactivity release from a package, as gas volumetric leakages rates are proposed in ANSI N14.5 and ISO standards. In our previous works, gas volumetric leakage rates for several kinds of gas from various leaks were measured and two evaluation methods, 'a simple evaluation method' and 'a strict evaluation method', were proposed based on the results. The simple evaluation method considers the friction loss of laminar flow with expansion effect. The strict evaluating method considers an exit loss in addition to the friction loss. In this study, four worked examples were completed for on assumed large spent fuel transport cask (Type B Package) with wet or dry capacity and at three transport conditions; normal transport with intact fuels or failed fuels, and an accident in transport. The standard leakage rates and criteria for two kinds of leak test were calculated for each example by each evaluation method. The following observations are made based upon the calculations and evaluations: the choked flow model of ANSI method greatly overestimates the criteria for tests ; the laminar flow models of both ANSI and ISO methods slightly overestimate the criteria for tests; the above two results are within the design margin for ordinary transport condition and all methods are useful for the evaluation; for severe condition such as failed fuel transportation, it should pay attention to apply a choked flow model of ANSI method. (authors)

  1. Short-term mechanisms influencing volumetric brain dynamics

    Directory of Open Access Journals (Sweden)

    Nikki Dieleman

    2017-01-01

    Full Text Available With the use of magnetic resonance imaging (MRI and brain analysis tools, it has become possible to measure brain volume changes up to around 0.5%. Besides long-term brain changes caused by atrophy in aging or neurodegenerative disease, short-term mechanisms that influence brain volume may exist. When we focus on short-term changes of the brain, changes may be either physiological or pathological. As such determining the cause of volumetric dynamics of the brain is essential. Additionally for an accurate interpretation of longitudinal brain volume measures by means of neurodegeneration, knowledge about the short-term changes is needed. Therefore, in this review, we discuss the possible mechanisms influencing brain volumes on a short-term basis and set-out a framework of MRI techniques to be used for volumetric changes as well as the used analysis tools. 3D T1-weighted images are the images of choice when it comes to MRI of brain volume. These images are excellent to determine brain volume and can be used together with an analysis tool to determine the degree of volume change. Mechanisms that decrease global brain volume are: fluid restriction, evening MRI measurements, corticosteroids, antipsychotics and short-term effects of pathological processes like Alzheimer's disease, hypertension and Diabetes mellitus type II. Mechanisms increasing the brain volume include fluid intake, morning MRI measurements, surgical revascularization and probably medications like anti-inflammatory drugs and anti-hypertensive medication. Exercise was found to have no effect on brain volume on a short-term basis, which may imply that dehydration caused by exercise differs from dehydration by fluid restriction. In the upcoming years, attention should be directed towards studies investigating physiological short-term changes within the light of long-term pathological changes. Ultimately this may lead to a better understanding of the physiological short-term effects of

  2. WE-D-303-02: Applications of Volumetric Images Generated with a Respiratory Motion Model Based On An External Surrogate Signal

    International Nuclear Information System (INIS)

    Hurwitz, M; Williams, C; Dhou, S; Lewis, J; Mishra, P

    2015-01-01

    Purpose: Respiratory motion can vary significantly over the course of simulation and treatment. Our goal is to use volumetric images generated with a respiratory motion model to improve the definition of the internal target volume (ITV) and the estimate of delivered dose. Methods: Ten irregular patient breathing patterns spanning 35 seconds each were incorporated into a digital phantom. Ten images over the first five seconds of breathing were used to emulate a 4DCT scan, build the ITV, and generate a patient-specific respiratory motion model which correlated the measured trajectories of markers placed on the patients’ chests with the motion of the internal anatomy. This model was used to generate volumetric images over the subsequent thirty seconds of breathing. The increase in the ITV taking into account the full 35 seconds of breathing was assessed with ground-truth and model-generated images. For one patient, a treatment plan based on the initial ITV was created and the delivered dose was estimated using images from the first five seconds as well as ground-truth and model-generated images from the next 30 seconds. Results: The increase in the ITV ranged from 0.2 cc to 6.9 cc for the ten patients based on ground-truth information. The model predicted this increase in the ITV with an average error of 0.8 cc. The delivered dose to the tumor (D95) changed significantly from 57 Gy to 41 Gy when estimated using 5 seconds and 30 seconds, respectively. The model captured this effect, giving an estimated D95 of 44 Gy. Conclusion: A respiratory motion model generating volumetric images of the internal patient anatomy could be useful in estimating the increase in the ITV due to irregular breathing during simulation and in assessing delivered dose during treatment. This project was supported, in part, through a Master Research Agreement with Varian Medical Systems, Inc. and Radiological Society of North America Research Scholar Grant #RSCH1206

  3. Investigating output and energy variations and their relationship to delivery QA results using Statistical Process Control for helical tomotherapy.

    Science.gov (United States)

    Binny, Diana; Mezzenga, Emilio; Lancaster, Craig M; Trapp, Jamie V; Kairn, Tanya; Crowe, Scott B

    2017-06-01

    The aims of this study were to investigate machine beam parameters using the TomoTherapy quality assurance (TQA) tool, establish a correlation to patient delivery quality assurance results and to evaluate the relationship between energy variations detected using different TQA modules. TQA daily measurement results from two treatment machines for periods of up to 4years were acquired. Analyses of beam quality, helical and static output variations were made. Variations from planned dose were also analysed using Statistical Process Control (SPC) technique and their relationship to output trends were studied. Energy variations appeared to be one of the contributing factors to delivery output dose seen in the analysis. Ion chamber measurements were reliable indicators of energy and output variations and were linear with patient dose verifications. Crown Copyright © 2017. Published by Elsevier Ltd. All rights reserved.

  4. 40 CFR 80.157 - Volumetric additive reconciliation (“VAR”), equipment calibration, and recordkeeping requirements.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 16 2010-07-01 2010-07-01 false Volumetric additive reconciliation (â... ADDITIVES Detergent Gasoline § 80.157 Volumetric additive reconciliation (“VAR”), equipment calibration, and... other comparable VAR supporting documentation. (ii) For a facility which uses a gauge to measure the...

  5. 40 CFR 80.170 - Volumetric additive reconciliation (VAR), equipment calibration, and recordkeeping requirements.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 16 2010-07-01 2010-07-01 false Volumetric additive reconciliation... ADDITIVES Detergent Gasoline § 80.170 Volumetric additive reconciliation (VAR), equipment calibration, and...) For a facility which uses a gauge to measure the inventory of the detergent storage tank, the total...

  6. Volumetric Arterial Wall Shear Stress Calculation Based on Cine Phase Contrast MRI

    NARCIS (Netherlands)

    Potters, Wouter V.; van Ooij, Pim; Marquering, Henk; VanBavel, Ed; Nederveen, Aart J.

    2015-01-01

    PurposeTo assess the accuracy and precision of a volumetric wall shear stress (WSS) calculation method applied to cine phase contrast magnetic resonance imaging (PC-MRI) data. Materials and MethodsVolumetric WSS vectors were calculated in software phantoms. WSS algorithm parameters were optimized

  7. Reliability and Energy Output of Bifacial Modules

    Energy Technology Data Exchange (ETDEWEB)

    Van Aken, B.B.; Jansen, M.J.; Dekker, N.J.J. [ECN Solar Energy, Petten (Netherlands)

    2013-06-15

    Although flash tests under standard test conditions yields lower power due to transmittance of the back sheet, bifacial modules are expected to outperform their monofacial equivalents in terms of yearly energy output in the field. We compare flash tests for bifacial modules with and without a light scattering panel directly behind the modules: 3% more power output is obtained. We also report on the damp-heat reliability of modules with transparent back sheet. Finally we will present the results of an outdoor study comparing modules with transparent back sheet and modules with state-of-the-art AR coating on the front glass.

  8. Explaining output volatility: The case of taxation

    DEFF Research Database (Denmark)

    Posch, Olaf

    the second moment of output growth rates without (long-run) effects on the first moment. Taking the model to the data, we exploit observed heterogeneity patterns to estimate effects of tax rates on macro volatility using panel estimation, explicitly modeling the unobserved variance process. We find a strong......This paper studies the effects of taxation on output volatility in OECD countries to shed light on the sources of observed heterogeneity over time and across countries. To this end, we derive tax effects on macro aggregates in a stochastic neoclassical model. As a result, taxes are shown to affect...... positive effects....

  9. The light output of BGO crystals

    International Nuclear Information System (INIS)

    Gong Zhufang; Ma Wengan; Lin Zhirong; Wang Zhaomin; Xu Zhizong; Fan Yangmei

    1987-01-01

    The dependence of light output on the surface treatment of BGO crystals has been tested. The results of experiments and Monte Carlo calculation indicate that for a tapered BGO crystal the best way to improve the uniformity and the energy resolution and to obtain higher light output is roughing the surface coupled to photomultiplier tube. The authors also observed that different wrapping method can effect its uniformity and resolutoin. Monte Carlo calculation indicates that the higher one of the 'double peaks' is the photoelectron peak of γ rays

  10. Efficacy of robust optimization plan with partial-arc VMAT for photon volumetric-modulated arc therapy: A phantom study.

    Science.gov (United States)

    Miura, Hideharu; Ozawa, Shuichi; Nagata, Yasushi

    2017-09-01

    This study investigated position dependence in planning target volume (PTV)-based and robust optimization plans using full-arc and partial-arc volumetric modulated arc therapy (VMAT). The gantry angles at the periphery, intermediate, and center CTV positions were 181°-180° (full-arc VMAT) and 181°-360° (partial-arc VMAT). A PTV-based optimization plan was defined by 5 mm margin expansion of the CTV to a PTV volume, on which the dose constraints were applied. The robust optimization plan consisted of a directly optimized dose to the CTV under a maximum-uncertainties setup of 5 mm. The prescription dose was normalized to the CTV D 99% (the minimum relative dose that covers 99% of the volume of the CTV) as an original plan. The isocenter was rigidly shifted at 1 mm intervals in the anterior-posterior (A-P), superior-inferior (S-I), and right-left (R-L) directions from the original position to the maximum-uncertainties setup of 5 mm in the original plan, yielding recalculated dose distributions. It was found that for the intermediate and center positions, the uncertainties in the D 99% doses to the CTV for all directions did not significantly differ when comparing the PTV-based and robust optimization plans (P > 0.05). For the periphery position, uncertainties in the D 99% doses to the CTV in the R-L direction for the robust optimization plan were found to be lower than those in the PTV-based optimization plan (P plan's efficacy using partial-arc VMAT depends on the periphery CTV position. © 2017 The Authors. Journal of Applied Clinical Medical Physics published by Wiley Periodicals, Inc. on behalf of American Association of Physicists in Medicine.

  11. Evaluation of DQA for tomography using 3D volumetric phantom

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Sang Uk [Dept. of Radiation Oncology, Catholic University of Incheon St. Mary' s Hospital, Incheon (Korea, Republic of); Kim, Jeong Koo [Dept. of Radiological Science, Hanseo University, Seosan (Korea, Republic of)

    2016-12-15

    The study investigates the necessity of 3 dimensional dose distribution evaluation instead of point dose and 2 dimensional dose distribution evaluation. Treatment plans were generated on the RANDO phantom to measure the precise dose distribution of the treatment site 0.5, 1, 1.5, 2, 2.5, 3 cm with the prescribed dose; 1,200 cGy, 5 fractions. Gamma analysis (3%/3 mm, 2%/2 mm) of dose distribution was evaluated with gafchromic EBT2 film and ArcCHECK phantom. The average error of absolute dose was measured at 0.76±0.59% and 1.37±0.76% in cheese phantom and ArcCHECK phantom respectively. The average passing ratio for 3%/3 mm were 97.72±0.02% and 99.26±0.01% in gafchromic EBT2 film and ArcCHECK phantom respectively. The average passing ratio for 2%/2 mm were 94.21±0.02% and 93.02±0.01% in gafchromic EBT2 film and ArcCHECK phantom respectively. There was a more accurate dose distribution of 3D volume phantom than cheese phantom in patients DQA using tomotherapy. Therefor it should be evaluated simultaneously 3 dimensional dose evaluation on target and peripheral area in rotational radiotherapy such as tomotherapy.

  12. Volumetric Modulated Arc Therapy for Spine Radiosurgery: Superior Treatment Planning and Delivery Compared to Static Beam Intensity Modulated Radiotherapy.

    Science.gov (United States)

    Zach, Leor; Tsvang, Lev; Alezra, Dror; Ben Ayun, Maoz; Harel, Ran

    2016-01-01

    Spine stereotactic radiosurgery (SRS) delivers an accurate and efficient high radiation dose to vertebral metastases in 1-5 fractions. We aimed to compare volumetric modulated arc therapy (VMAT) to static beam intensity modulated radiotherapy (IMRT) for spine SRS. Ten spine lesions of previously treated SRS patients were planned retrospectively using both IMRT and VMAT with a prescribed dose of 16 Gy to 100% of the planning target volume (PTV). The plans were compared for conformity, homogeneity, treatment delivery time, and safety (spinal cord dose). All evaluated parameters favored the VMAT plan over the IMRT plans. D min in the IMRT was significantly lower than in the VMAT plan (7.65 Gy/10.88 Gy, p DSC) was found to be significantly better for the VMAT plans compared to the IMRT plans (0.77/0.58, resp., p  value < 0.01), and an almost 50% reduction in the net treatment time was calculated for the VMAT compared to the IMRT plans (6.73 min/12.96 min, p < 0.001). In our report, VMAT provides better conformity, homogeneity, and safety profile. The shorter treatment time is a major advantage and not only provides convenience to the painful patient but also contributes to the precision of this high dose radiation therapy.

  13. Volumetric Modulated Arc Therapy for Spine Radiosurgery: Superior Treatment Planning and Delivery Compared to Static Beam Intensity Modulated Radiotherapy

    Directory of Open Access Journals (Sweden)

    Leor Zach

    2016-01-01

    Full Text Available Purpose. Spine stereotactic radiosurgery (SRS delivers an accurate and efficient high radiation dose to vertebral metastases in 1–5 fractions. We aimed to compare volumetric modulated arc therapy (VMAT to static beam intensity modulated radiotherapy (IMRT for spine SRS. Methods and Materials. Ten spine lesions of previously treated SRS patients were planned retrospectively using both IMRT and VMAT with a prescribed dose of 16 Gy to 100% of the planning target volume (PTV. The plans were compared for conformity, homogeneity, treatment delivery time, and safety (spinal cord dose. Results. All evaluated parameters favored the VMAT plan over the IMRT plans. Dmin in the IMRT was significantly lower than in the VMAT plan (7.65 Gy/10.88 Gy, p<0.001, the Dice Similarity Coefficient (DSC was found to be significantly better for the VMAT plans compared to the IMRT plans (0.77/0.58, resp., p  value<0.01, and an almost 50% reduction in the net treatment time was calculated for the VMAT compared to the IMRT plans (6.73 min/12.96 min, p<0.001. Conclusions. In our report, VMAT provides better conformity, homogeneity, and safety profile. The shorter treatment time is a major advantage and not only provides convenience to the painful patient but also contributes to the precision of this high dose radiation therapy.

  14. SU-F-J-54: Towards Real-Time Volumetric Imaging Using the Treatment Beam and KV Beam

    Energy Technology Data Exchange (ETDEWEB)

    Chen, M; Rozario, T; Liu, A; Jiang, S; Lu, W [UT Southwestern Medical Center, Dallas, TX (United States)

    2016-06-15

    Purpose: Existing real-time imaging uses dual (orthogonal) kV beam fluoroscopies and may result in significant amount of extra radiation to patients, especially for prolonged treatment cases. In addition, kV projections only provide 2D information, which is insufficient for in vivo dose reconstruction. We propose real-time volumetric imaging using prior knowledge of pre-treatment 4D images and real-time 2D transit data of treatment beam and kV beam. Methods: The pre-treatment multi-snapshot volumetric images are used to simulate 2D projections of both the treatment beam and kV beam, respectively, for each treatment field defined by the control point. During radiation delivery, the transit signals acquired by the electronic portal image device (EPID) are processed for every projection and compared with pre-calculation by cross-correlation for phase matching and thus 3D snapshot identification or real-time volumetric imaging. The data processing involves taking logarithmic ratios of EPID signals with respect to the air scan to reduce modeling uncertainties in head scatter fluence and EPID response. Simulated 2D projections are also used to pre-calculate confidence levels in phase matching. Treatment beam projections that have a low confidence level either in pre-calculation or real-time acquisition will trigger kV beams so that complementary information can be exploited. In case both the treatment beam and kV beam return low confidence in phase matching, a predicted phase based on linear regression will be generated. Results: Simulation studies indicated treatment beams provide sufficient confidence in phase matching for most cases. At times of low confidence from treatment beams, kV imaging provides sufficient confidence in phase matching due to its complementary configuration. Conclusion: The proposed real-time volumetric imaging utilizes the treatment beam and triggers kV beams for complementary information when the treatment beam along does not provide sufficient

  15. Determination of the 4 mm Gamma Knife helmet relative output factor using a variety of detectors

    International Nuclear Information System (INIS)

    Tsai, J.-S.; Rivard, Mark J.; Engler, Mark J.; Mignano, John E.; Wazer, David E.; Shucart, William A.

    2003-01-01

    Though the 4 mm Gamma Knife helmet is used routinely, there is disagreement in the Gamma Knife users community on the value of the 4 mm helmet relative output factor. A range of relative output factors is used, and this variation may impair observations of dose response and optimization of prescribed dose. To study this variation, measurements were performed using the following radiation detectors: silicon diode, diamond detector, radiographic film, radiochromic film, and TLD cubes. To facilitate positioning of the silicon diode and diamond detector, a three-dimensional translation micrometer was used to iteratively determine the position of maximum detector response. Positioning of the films and TLDs was accomplished by manufacturing custom holders for each technique. Results from all five measurement techniques indicate that the 4 mm helmet relative output factor is 0.868±0.014. Within the experimental uncertainties, this value is in good agreement with results obtained by other investigators using diverse techniques

  16. System analysis of formation and perception processes of three-dimensional images in volumetric displays

    Science.gov (United States)

    Bolshakov, Alexander; Sgibnev, Arthur

    2018-03-01

    One of the promising devices is currently a volumetric display. Volumetric displays capable to visualize complex three-dimensional information as nearly as possible to its natural – volume form without the use of special glasses. The invention and implementation of volumetric display technology will expand opportunities of information visualization in various spheres of human activity. The article attempts to structure and describe the interrelation of the essential characteristics of objects in the area of volumetric visualization. Also there is proposed a method of calculation of estimate total number of voxels perceived by observers during the 3D demonstration, generated using a volumetric display with a rotating screen. In the future, it is planned to expand the described technique and implement a system for estimation the quality of generated images, depending on the types of biplanes and their initial characteristics.

  17. Design, Implementation and Characterization of a Quantum-Dot-Based Volumetric Display

    Science.gov (United States)

    Hirayama, Ryuji; Naruse, Makoto; Nakayama, Hirotaka; Tate, Naoya; Shiraki, Atsushi; Kakue, Takashi; Shimobaba, Tomoyoshi; Ohtsu, Motoichi; Ito, Tomoyoshi

    2015-02-01

    In this study, we propose and experimentally demonstrate a volumetric display system based on quantum dots (QDs) embedded in a polymer substrate. Unlike conventional volumetric displays, our system does not require electrical wiring; thus, the heretofore unavoidable issue of occlusion is resolved because irradiation by external light supplies the energy to the light-emitting voxels formed by the QDs. By exploiting the intrinsic attributes of the QDs, the system offers ultrahigh definition and a wide range of colours for volumetric displays. In this paper, we discuss the design, implementation and characterization of the proposed volumetric display's first prototype. We developed an 8 × 8 × 8 display comprising two types of QDs. This display provides multicolour three-type two-dimensional patterns when viewed from different angles. The QD-based volumetric display provides a new way to represent images and could be applied in leisure and advertising industries, among others.

  18. Investigating the effect of clamping force on the fatigue life of bolted plates using volumetric approach

    International Nuclear Information System (INIS)

    Esmaeili, F.; Chakherlou, T. N.; Zehsaz, M.; Hasanifard, S.

    2013-01-01

    In this paper, the effects of bolt clamping force on the fatigue life for bolted plates made from Al7075-T6 have been studied on the values of notch strength reduction factor obtained by volumetric approach. To attain stress distribution around the notch (hole) which is required for volumetric approach, nonlinear finite element simulations were carried out. To estimate the fatigue life, the available smooth S-N curve of Al7075-T6 and the notch strength reduction factor obtained from volumetric method were used. The estimated fatigue life was compared with the available experimental test results. The investigation shows that there is a good agreement between the life predicted by the volumetric approach and the experimental results for various specimens with different amount of clamping forces. Volumetric approach and experimental results showed that the fatigue life of bolted plates improves because of the compressive stresses created around the plate hole due to clamping force.

  19. Communicating doses of pediatric liquid medicines to parents/caregivers: a comparison of written dosing directions on prescriptions with labels applied by dispensed pharmacy.

    Science.gov (United States)

    Shah, Rita; Blustein, Leona; Kuffner, Ed; Davis, Lisa

    2014-03-01

    To identify and compare volumetric measures used by healthcare providers in communicating dosing instructions for pediatric liquid prescriptions to parents/caregivers. Dosing instructions were retrospectively reviewed for the 10 most frequently prescribed liquid medications dispensed from 4 community pharmacies for patients aged ≤ 12 years during a 3-month period. Volumetric measures on original prescriptions (ie, milliliters, teaspoons) were compared with those utilized by the pharmacist on the pharmacy label dispensed to the parent/caregiver. Of 649 prescriptions and corresponding pharmacy labels evaluated, 68% of prescriptions and 62% of pharmacy labels communicated dosing in milliliters, 24% of prescriptions and 29% of pharmacy labels communicated dosing in teaspoonfuls, 7% of prescriptions and 0% of pharmacy labels communicated dosing in other measures (ie, milligrams, cubic centimeters, "dose"), and 25% of dispensed pharmacy labels did not reflect units as written in the prescription. Volumetric measures utilized by healthcare professionals in dosing instructions for prescription pediatric oral liquid medications are not consistent. Healthcare professionals and parents/caregivers should be educated on safe dosing practices for liquid pediatric medications. Generalizability to the larger pediatric population may vary depending on pharmacy chain, location, and medications evaluated. Copyright © 2014 Mosby, Inc. All rights reserved.

  20. Output formatting in Apple-Soft Basic

    International Nuclear Information System (INIS)

    Navale, A.S.

    1987-01-01

    Personal computers are being used extensively in various fields. BASIC is a very popular and widely used language in personal computers. Apple computer is one of the popular machines used for scientific and engineering applications. Presenting output from computers in a neat and easy to read form is very important. Languages like FORTRAN have utility command 'FORMAT' which takes care of the formatting of the output in user-defined form. In some versions of BASIC a PRINT USING facility is available but it is not as powerful as the FORTRAN statement 'FORMAT'. Applesoft basic does not have even this PRINT USING command. Programmers have to write their own program segments to handle output formatting in Applesoft BASIC. Generally, such user written programs are of limited use as they cannot be used easily with other programs. A general purpose and easily transportable subroutine in Applesoft BASIC is presented here for handling output formatting in user-defined structure. The subroutine is nearly as powerful as the FORMAT statement in FORTRAN. It can also be used in other versions of BASIC with very little modifications. 3 tables, 4 refs. (author)

  1. On output regulation for linear systems

    NARCIS (Netherlands)

    Saberi, Ali; Stoorvogel, Antonie Arij; Sannuti, Peddapullaiah

    For both continuous- and discrete-time systems, we revisit the output regulation problem for linear systems. We generalize the problem formulation in order • to expand the class of reference or disturbance signals, • to utilize the derivative or feedforward information of reference signals whenever

  2. Fast Output-sensitive Matrix Multiplication

    DEFF Research Database (Denmark)

    Jacob, Riko; Stöckel, Morten

    2015-01-01

    We consider the problem of multiplying two $U \\times U$ matrices $A$ and $C$ of elements from a field $\\F$. We present a new randomized algorithm that can use the known fast square matrix multiplication algorithms to perform fewer arithmetic operations than the current state of the art for output...

  3. Predicting Color Output of Additive Manufactured Parts

    DEFF Research Database (Denmark)

    Eiríksson, Eyþór Rúnar; Pedersen, David Bue; Aanæs, Henrik

    2015-01-01

    In this paper we address the colorimetric performance of a multicolor additive manufacturing process. A method on how to measure and characterize color performance of said process is presented. Furthermore, a method on predicting the color output is demonstrated, allowing for previsualization...

  4. Multiple output timing and trigger generator

    Energy Technology Data Exchange (ETDEWEB)

    Wheat, Robert M. [Los Alamos National Laboratory; Dale, Gregory E [Los Alamos National Laboratory

    2009-01-01

    In support of the development of a multiple stage pulse modulator at the Los Alamos National Laboratory, we have developed a first generation, multiple output timing and trigger generator. Exploiting Commercial Off The Shelf (COTS) Micro Controller Units (MCU's), the timing and trigger generator provides 32 independent outputs with a timing resolution of about 500 ns. The timing and trigger generator system is comprised of two MCU boards and a single PC. One of the MCU boards performs the functions of the timing and signal generation (the timing controller) while the second MCU board accepts commands from the PC and provides the timing instructions to the timing controller. The PC provides the user interface for adjusting the on and off timing for each of the output signals. This system provides 32 output or timing signals which can be pre-programmed to be in an on or off state for each of 64 time steps. The width or duration of each of the 64 time steps is programmable from 2 {micro}s to 2.5 ms with a minimum time resolution of 500 ns. The repetition rate of the programmed pulse train is only limited by the time duration of the programmed event. This paper describes the design and function of the timing and trigger generator system and software including test results and measurements.

  5. What shapes output of policy reform?

    DEFF Research Database (Denmark)

    Carlsen, Kirsten

    This thesis deals with the factors shaping forest policy output during the stages implementation and bases its main message on empirical findings from the forestry sector in Ghana. Policy and institutional factors are important underlying causes for deforestation, especially in the tropics. Fores...

  6. Monetary policy and regional output in Brazil

    Directory of Open Access Journals (Sweden)

    Rafael Rockenbach da Silva Guimarães

    2014-03-01

    Full Text Available This work presents an analysis of whether the effects of the Brazilian monetary policy on regional outputs are symmetric. The strategy developed combines the techniques of principal component analysis (PCA to decompose the variables that measure regional economic activity into common and region-specific components and vector autoregressions (VAR to observe the behavior of these variables in response to monetary policy shocks. The common component responds to monetary policy as expected. Additionally, the idiosyncratic components of the regions showed no impact of monetary policy. The main finding of this paper is that the monetary policy responses on regional output are symmetrical when the regional output decomposition is performed, and the responses are asymmetrical when this decomposition is not performed. Therefore, performing the regional output decomposition corroborates the economic intuition that monetary policy has no impact on region-specific issues. Once monetary policy affects the common component of the regional economic activity and does not impact its idiosyncratic components, it can be considered symmetrical.

  7. Comparison of cardiac output measurement techniques

    DEFF Research Database (Denmark)

    Espersen, K; Jensen, E W; Rosenborg, D

    1995-01-01

    Simultaneously measured cardiac output obtained by thermodilution (TD), transcutaneous suprasternal ultrasonic Doppler (DOP), CO2-rebreathing (CR) and the direct Fick method (FI) were compared in eleven healthy subjects in a supine position (SU), a sitting position (SI), and during sitting exercise...

  8. A deep learning approach for pose estimation from volumetric OCT data.

    Science.gov (United States)

    Gessert, Nils; Schlüter, Matthias; Schlaefer, Alexander

    2018-05-01

    Tracking the pose of instruments is a central problem in image-guided surgery. For microscopic scenarios, optical coherence tomography (OCT) is increasingly used as an imaging modality. OCT is suitable for accurate pose estimation due to its micrometer range resolution and volumetric field of view. However, OCT image processing is challenging due to speckle noise and reflection artifacts in addition to the images' 3D nature. We address pose estimation from OCT volume data with a new deep learning-based tracking framework. For this purpose, we design a new 3D convolutional neural network (CNN) architecture to directly predict the 6D pose of a small marker geometry from OCT volumes. We use a hexapod robot to automatically acquire labeled data points which we use to train 3D CNN architectures for multi-output regression. We use this setup to provide an in-depth analysis on deep learning-based pose estimation from volumes. Specifically, we demonstrate that exploiting volume information for pose estimation yields higher accuracy than relying on 2D representations with depth information. Supporting this observation, we provide quantitative and qualitative results that 3D CNNs effectively exploit the depth structure of marker objects. Regarding the deep learning aspect, we present efficient design principles for 3D CNNs, making use of insights from the 2D deep learning community. In particular, we present Inception3D as a new architecture which performs best for our application. We show that our deep learning approach reaches errors at our ground-truth label's resolution. We achieve a mean average error of 14.89 ± 9.3 µm and 0.096 ± 0.072° for position and orientation learning, respectively. Copyright © 2018 Elsevier B.V. All rights reserved.

  9. Controllable dose

    International Nuclear Information System (INIS)

    Alvarez R, J.T.; Anaya M, R.A.

    2004-01-01

    With the purpose of eliminating the controversy about the lineal hypothesis without threshold which found the systems of dose limitation of the recommendations of ICRP 26 and 60, at the end of last decade R. Clarke president of the ICRP proposed the concept of Controllable Dose: as the dose or dose sum that an individual receives from a particular source which can be reasonably controllable by means of any means; said concept proposes a change in the philosophy of the radiological protection of its concern by social approaches to an individual focus. In this work a panorama of the foundations is presented, convenient and inconveniences that this proposal has loosened in the international community of the radiological protection, with the purpose of to familiarize to our Mexican community in radiological protection with these new concepts. (Author)

  10. Monte Carlo based electron treatment planning and cutout output factor calculations

    Science.gov (United States)

    Mitrou, Ellis

    Electron radiotherapy (RT) offers a number of advantages over photons. The high surface dose, combined with a rapid dose fall-off beyond the target volume presents a net increase in tumor control probability and decreases the normal tissue complication for superficial tumors. Electron treatments are normally delivered clinically without previously calculated dose distributions due to the complexity of the electron transport involved and greater error in planning accuracy. This research uses Monte Carlo (MC) methods to model clinical electron beams in order to accurately calculate electron beam dose distributions in patients as well as calculate cutout output factors, reducing the need for a clinical measurement. The present work is incorporated into a research MC calculation system: McGill Monte Carlo Treatment Planning (MMCTP) system. Measurements of PDDs, profiles and output factors in addition to 2D GAFCHROMICRTM EBT2 film measurements in heterogeneous phantoms were obtained to commission the electron beam model. The use of MC for electron TP will provide more accurate treatments and yield greater knowledge of the electron dose distribution within the patient. The calculation of output factors could invoke a clinical time saving of up to 1 hour per patient.

  11. Re-irradiation of metastatic spinal cord compression: A feasibility study by volumetric-modulated arc radiotherapy for in-field recurrence creating a dosimetric hole on the central canal

    International Nuclear Information System (INIS)

    Mancosu, Pietro; Navarria, Piera; Bignardi, Mario; Cozzi, Luca; Fogliata, Antonella; Lattuada, Paola; Santoro, Armando; Urso, Gaetano; Vigorito, Sabrina; Scorsetti, Marta

    2010-01-01

    When local recurrences arise within an irradiated region involving metastatic spinal cord compression, the dose limit to the spinal cord reduces the chance to re-treat the patient by 3D-conformational RT technique. The possibility of using volumetric modulated arc RT by RapidArc was evaluated for dose sparing at spinal cord level and preserving target coverage. A clinically satisfactory PTV coverage and dose sparing to the spinal cord were obtained. An upcoming trial on patients will provide clinical outcomes.

  12. SU-F-T-377: Monte Carlo Re-Evaluation of Volumetric-Modulated Arc Plans of Advanced Stage Nasopharygeal Cancers Optimized with Convolution-Superposition Algorithm

    Energy Technology Data Exchange (ETDEWEB)

    Lee, K; Leung, R; Law, G; Wong, M; Lee, V; Tung, S; Cheung, S; Chan, M [Tuen Mun Hospital, Hong Kong (Hong Kong)

    2016-06-15

    Background: Commercial treatment planning system Pinnacle3 (Philips, Fitchburg, WI, USA) employs a convolution-superposition algorithm for volumetric-modulated arc radiotherapy (VMAT) optimization and dose calculation. Study of Monte Carlo (MC) dose recalculation of VMAT plans for advanced-stage nasopharyngeal cancers (NPC) is currently limited. Methods: Twenty-nine VMAT prescribed 70Gy, 60Gy, and 54Gy to the planning target volumes (PTVs) were included. These clinical plans achieved with a CS dose engine on Pinnacle3 v9.0 were recalculated by the Monaco TPS v5.0 (Elekta, Maryland Heights, MO, USA) with a XVMC-based MC dose engine. The MC virtual source model was built using the same measurement beam dataset as for the Pinnacle beam model. All MC recalculation were based on absorbed dose to medium in medium (Dm,m). Differences in dose constraint parameters per our institution protocol (Supplementary Table 1) were analyzed. Results: Only differences in maximum dose to left brachial plexus, left temporal lobe and PTV54Gy were found to be statistically insignificant (p> 0.05). Dosimetric differences of other tumor targets and normal organs are found in supplementary Table 1. Generally, doses outside the PTV in the normal organs are lower with MC than with CS. This is also true in the PTV54-70Gy doses but higher dose in the nasal cavity near the bone interfaces is consistently predicted by MC, possibly due to the increased backscattering of short-range scattered photons and the secondary electrons that is not properly modeled by the CS. The straight shoulders of the PTV dose volume histograms (DVH) initially resulted from the CS optimization are merely preserved after MC recalculation. Conclusion: Significant dosimetric differences in VMAT NPC plans were observed between CS and MC calculations. Adjustments of the planning dose constraints to incorporate the physics differences from conventional CS algorithm should be made when VMAT optimization is carried out directly

  13. Quantitative comparison of volumetric modulated arc therapy and intensity modulated radiotherapy plan quality in sino-nasal cancer

    International Nuclear Information System (INIS)

    Sankaralingam, Marimuthu; Glegg, Martin; Smith, Suzanne; James, Allan; Rizwanullah, Mohammed

    2012-01-01

    The aim of this study was to compare various dosimetric parameters of dynamic mlc intensity modulated radiotherapy (IMRT) plans with volumetric modulated arc therapy (VMAT) plans for sino-nasal cancers, which are rare and complex tumors to treat with radiotherapy. IMRT using five fields, coplanar in the sagittal plane and VMAT employing two coplanar arc plans were created for five patients. The plans were assessed by comparing Conformity Index and Sigma Index (dose homogeneity) in the Planning Target Volume (PTV) and through comparison of dose-volume characteristics to the following organs at risk (OARs): Spinal cord, brainstem, eye, ipsilateral and contralateral optic nerve and the volume of brain receiving 10% of the prescribed dose (V 10% ). The total monitor units required to deliver the plan were also compared. Conformity Index was found to be superior in VMAT plans for three patients and in IMRT plans for two patients. Dose homogeneity within the PTV was better with VMAT plans for all five cases. The mean difference in Sigma Index was 0.68%. There was no significant difference in dose between IMRT and VMAT plans for any of the OARs assessed in these patients. The monitor units were significantly reduced in the VMAT plan in comparison to the IMRT plan for four out of five patients, with mean reduction of 66%. It was found in this study that for the treatment of sino-nasal cancer, VMAT produced minimal, and statistically insignificant improvement in dose homogeneity within the PTV when compared with IMRT. VMAT plans were delivered using significantly fewer monitor units. We conclude in this study that VMAT does not offer significant improvement of treatment for sino-nasal cancer over the existing IMRT techniques, but the findings may change with a larger sample of patients in this rare condition. (author)

  14. Volumetric Spectroscopic Imaging of Glioblastoma Multiforme Radiation Treatment Volumes

    Energy Technology Data Exchange (ETDEWEB)

    Parra, N. Andres [Department of Radiation Oncology, University of Miami Miller School of Medicine, Miami, Florida (United States); Maudsley, Andrew A. [Department of Radiology, University of Miami Miller School of Medicine, Miami, Florida (United States); Gupta, Rakesh K. [Department of Radiology and Imaging, Fortis Memorial Research Institute, Gurgaon, Haryana (India); Ishkanian, Fazilat; Huang, Kris [Department of Radiation Oncology, University of Miami Miller School of Medicine, Miami, Florida (United States); Walker, Gail R. [Biostatistics and Bioinformatics Core Resource, Sylvester Cancer Center, University of Miami Miller School of Medicine, Miami, Florida (United States); Padgett, Kyle [Department of Radiation Oncology, University of Miami Miller School of Medicine, Miami, Florida (United States); Department of Radiology, University of Miami Miller School of Medicine, Miami, Florida (United States); Roy, Bhaswati [Department of Radiology and Imaging, Fortis Memorial Research Institute, Gurgaon, Haryana (India); Panoff, Joseph; Markoe, Arnold [Department of Radiation Oncology, University of Miami Miller School of Medicine, Miami, Florida (United States); Stoyanova, Radka, E-mail: RStoyanova@med.miami.edu [Department of Radiation Oncology, University of Miami Miller School of Medicine, Miami, Florida (United States)

    2014-10-01

    Purpose: Magnetic resonance (MR) imaging and computed tomography (CT) are used almost exclusively in radiation therapy planning of glioblastoma multiforme (GBM), despite their well-recognized limitations. MR spectroscopic imaging (MRSI) can identify biochemical patterns associated with normal brain and tumor, predominantly by observation of choline (Cho) and N-acetylaspartate (NAA) distributions. In this study, volumetric 3-dimensional MRSI was used to map these compounds over a wide region of the brain and to evaluate metabolite-defined treatment targets (metabolic tumor volumes [MTV]). Methods and Materials: Volumetric MRSI with effective voxel size of ∼1.0 mL and standard clinical MR images were obtained from 19 GBM patients. Gross tumor volumes and edema were manually outlined, and clinical target volumes (CTVs) receiving 46 and 60 Gy were defined (CTV{sub 46} and CTV{sub 60}, respectively). MTV{sub Cho} and MTV{sub NAA} were constructed based on volumes with high Cho and low NAA relative to values estimated from normal-appearing tissue. Results: The MRSI coverage of the brain was between 70% and 76%. The MTV{sub NAA} were almost entirely contained within the edema, and the correlation between the 2 volumes was significant (r=0.68, P=.001). In contrast, a considerable fraction of MTV{sub Cho} was outside of the edema (median, 33%) and for some patients it was also outside of the CTV{sub 46} and CTV{sub 60}. These untreated volumes were greater than 10% for 7 patients (37%) in the study, and on average more than one-third (34.3%) of the MTV{sub Cho} for these patients were outside of CTV{sub 60}. Conclusions: This study demonstrates the potential usefulness of whole-brain MRSI for radiation therapy planning of GBM and revealed that areas of metabolically active tumor are not covered by standard RT volumes. The described integration of MTV into the RT system will pave the way to future clinical trials investigating outcomes in patients treated based on

  15. Volumetric and MGMT parameters in glioblastoma patients: Survival analysis

    International Nuclear Information System (INIS)

    Iliadis, Georgios; Kotoula, Vassiliki; Chatzisotiriou, Athanasios; Televantou, Despina; Eleftheraki, Anastasia G; Lambaki, Sofia; Misailidou, Despina; Selviaridis, Panagiotis; Fountzilas, George

    2012-01-01

    In this study several tumor-related volumes were assessed by means of a computer-based application and a survival analysis was conducted to evaluate the prognostic significance of pre- and postoperative volumetric data in patients harboring glioblastomas. In addition, MGMT (O 6 -methylguanine methyltransferase) related parameters were compared with those of volumetry in order to observe possible relevance of this molecule in tumor development. We prospectively analyzed 65 patients suffering from glioblastoma (GBM) who underwent radiotherapy with concomitant adjuvant temozolomide. For the purpose of volumetry T1 and T2-weighted magnetic resonance (MR) sequences were used, acquired both pre- and postoperatively (pre-radiochemotherapy). The volumes measured on preoperative MR images were necrosis, enhancing tumor and edema (including the tumor) and on postoperative ones, net-enhancing tumor. Age, sex, performance status (PS) and type of operation were also included in the multivariate analysis. MGMT was assessed for promoter methylation with Multiplex Ligation-dependent Probe Amplification (MLPA), for RNA expression with real time PCR, and for protein expression with immunohistochemistry in a total of 44 cases with available histologic material. In the multivariate analysis a negative impact was shown for pre-radiochemotherapy net-enhancing tumor on the overall survival (OS) (p = 0.023) and for preoperative necrosis on progression-free survival (PFS) (p = 0.030). Furthermore, the multivariate analysis confirmed the importance of PS in PFS and OS of patients. MGMT promoter methylation was observed in 13/23 (43.5%) evaluable tumors; complete methylation was observed in 3/13 methylated tumors only. High rate of MGMT protein positivity (> 20% positive neoplastic nuclei) was inversely associated with pre-operative tumor necrosis (p = 0.021). Our findings implicate that volumetric parameters may have a significant role in the prognosis of GBM patients. Furthermore

  16. Dosimetric effects of sectional adjustments of collimator angles on volumetric modulated arc therapy for irregularly-shaped targets.

    Directory of Open Access Journals (Sweden)

    Beom Seok Ahn

    Full Text Available To calculate an optimal collimator angle at each of sectional arcs in a full-arc volumetric modulated arc therapy (VMAT plan and evaluate dosimetric quality of these VMAT plans comparing full-arc VMAT plans with a fixed collimator angle.Seventeen patients who had irregularly-shaped target in abdominal, head and neck, and chest cases were selected retrospectively. To calculate an optimal collimator angle at each of sectional arcs in VMAT, integrated MLC apertures which could cover all shapes of target determined by beam's-eye view (BEV within angular sections were obtained for each VMAT plan. The angular sections were 40°, 60°, 90° and 120°. When the collimator settings were rotated at intervals of 2°, we obtained the optimal collimator angle to minimize area size difference between the integrated MLC aperture and collimator settings with 5 mm-margins to the integrated MLC aperture. The VMAT plans with the optimal collimator angles (Colli-VMAT were generated in the EclipseTM. For comparison purposes, one full-arc VMAT plans with a fixed collimator angles (Std-VMAT were generated. The dose-volumetric parameters and total MUs were evaluated.The mean dose-volumetric parameters for target volume of Colli-VMAT were comparable to Std-VMAT. Colli-VMAT improved sparing of most normal organs but for brain stem, compared to Std-VMAT for all cases. There were decreasing tendencies in mean total MUs with decreasing angular section. The mean total MUs for Colli-VMAT with the angular section of 40° (434 ± 95 MU, 317 ± 81 MU, and 371 ± 43 MU for abdominal, head and neck, and chest cases, respectively were lower than those for Std-VMAT (654 ± 182 MU, 517 ± 116 MU, and 533 ± 25 MU, respectively.For an irregularly-shaped target, Colli-VMAT with the angular section of 40° reduced total MUs and improved sparing of normal organs, compared to Std-VMAT.

  17. Quality assurance in CT: implementation of the updated national diagnostic reference levels using an automated CT dose monitoring system.

    Science.gov (United States)

    Appel, E; Kröpil, P; Bethge, O T; Aissa, J; Thomas, C; Antoch, G; Boos, J

    2018-03-20

    To evaluate the implementation of the updated computed tomography (CT) diagnostic reference levels (DRLs) from the German Federal Office for Radiation Protection into clinical routine using an automatic CT dose monitoring system. CT radiation exposure was analysed before and after implementing the updated national DRLs into routine clinical work in 2016. After the implementation process, institutional CT protocols were mapped to the anatomical regions for which DRLs were provided. Systematically, protocols that exceeded the thresholds were optimised and analysed in detail. The CT radiation output parameters analysed were volumetric CT dose index (CTDIvol) and dose-length product (DLP). Three radiologists evaluated subjective image quality using a three-point Likert scale. The study included 94,258 CT series (from 27,103 CT examinations) in adult patients performed in 2016. When averaged over all body regions with available DRL, institutional CTDIvol/DLP values were always below the DRLs (65.2±32.9%/67.3±41.5% initially; 59.4±32%/60.5±39.9% after optimisation). Values exceeding the national DRLs were found for pelvis (n=268; CTDIvol 107.7±65.7%/DLP 106.3±79.3%), lumbar spine (n=91; 160.8±74.7%/175.2±104.1%), and facial bones (n=527; 108±39%/152.7±75.7%). After optimisation, CTDIvol and DLP were 87.9±73%/87.8±80.8% for the pelvis, 67.8±33.2%/74.5±50.6% for the lumbar spine and 95.1±45.8%/133.3±74.6% for the viscerocranium. An automatic CT dose monitoring system enabled not only comprehensive monitoring of a DRL implementation process but can also help to optimise radiation exposure. Copyright © 2018 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.

  18. Dose-rate effects of low-dropout voltage regulator at various biases

    International Nuclear Information System (INIS)

    Wang Yiyuan; Zheng Yuzhan; Gao Bo; Chen Rui; Fei Wuxiong; Lu Wu; Ren Diyuan

    2010-01-01

    A low-dropout voltage regulator, LM2941, was irradiated by 60 Co γ-rays at various dose rates and biases for investigating the total dose and dose rate effects. The radiation responses show that the key electrical parameters, including its output and dropout voltage, and the maximum output current, are sensitive to total dose and dose rates, and are significantly degraded at low dose rate and zero bias. The integrated circuits damage change with the dose rates and biases, and the dose-rate effects are relative to its electric field. (authors)

  19. Comparison of volumetric modulated arc therapy and intensity modulated radiation therapy for whole brain hippocampal sparing treatment plans based on radiobiological modeling

    Directory of Open Access Journals (Sweden)

    Ethan Kendall

    2018-01-01

    Full Text Available Introduction: In this article, we report the results of our investigation on comparison of radiobiological aspects of treatment plans with linear accelerator-based intensity-modulated radiation therapy and volumetric-modulated arc therapy for patients having hippocampal avoidance whole-brain radiation therapy. Materials and Methods: In this retrospective study using the dose-volume histogram, we calculated and compared biophysical indices of equivalent uniform dose, tumor control probability, and normal tissue complication probability (NTCP for 15 whole-brain radiotherapy patients. Results and Discussions: Dose-response models for tumors and critical structures were separated into two groups: mechanistic and empirical. Mechanistic models formulate mathematically with describable relationships while empirical models fit data through empirical observations to appropriately determine parameters giving results agreeable to those given by mechanistic models. Conclusions: Techniques applied in this manuscript could be applied to any other organs or types of cancer to evaluate treatment plans based on radiobiological modeling.

  20. Single-chip CMUT-on-CMOS front-end system for real-time volumetric IVUS and ICE imaging.

    Science.gov (United States)

    Gurun, Gokce; Tekes, Coskun; Zahorian, Jaime; Xu, Toby; Satir, Sarp; Karaman, Mustafa; Hasler, Jennifer; Degertekin, F Levent

    2014-02-01

    Intravascular ultrasound (IVUS) and intracardiac echography (ICE) catheters with real-time volumetric ultrasound imaging capability can provide unique benefits to many interventional procedures used in the diagnosis and treatment of coronary and structural heart diseases. Integration of capacitive micromachined ultrasonic transducer (CMUT) arrays with front-end electronics in single-chip configuration allows for implementation of such catheter probes with reduced interconnect complexity, miniaturization, and high mechanical flexibility. We implemented a single-chip forward-looking (FL) ultrasound imaging system by fabricating a 1.4-mm-diameter dual-ring CMUT array using CMUT-on-CMOS technology on a front-end IC implemented in 0.35-μm CMOS process. The dual-ring array has 56 transmit elements and 48 receive elements on two separate concentric annular rings. The IC incorporates a 25-V pulser for each transmitter and a low-noise capacitive transimpedance amplifier (TIA) for each receiver, along with digital control and smart power management. The final shape of the silicon chip is a 1.5-mm-diameter donut with a 430-μm center hole for a guide wire. The overall front-end system requires only 13 external connections and provides 4 parallel RF outputs while consuming an average power of 20 mW. We measured RF A-scans from the integrated single- chip array which show full functionality at 20.1 MHz with 43% fractional bandwidth. We also tested and demonstrated the image quality of the system on a wire phantom and an ex vivo chicken heart sample. The measured axial and lateral point resolutions are 92 μm and 251 μm, respectively. We successfully acquired volumetric imaging data from the ex vivo chicken heart at 60 frames per second without any signal averaging. These demonstrative results indicate that single-chip CMUT-on-CMOS systems have the potential to produce realtime volumetric images with image quality and speed suitable for catheter-based clinical applications.

  1. Survey of computed tomography doses in head and chest protocols

    International Nuclear Information System (INIS)

    Souza, Giordana Salvi de; Silva, Ana Maria Marques da

    2016-01-01

    Computed tomography is a clinical tool for the diagnosis of patients. However, the patient is subjected to a complex dose distribution. The aim of this study was to survey dose indicators in head and chest protocols CT scans, in terms of Dose-Length Product(DLP) and effective dose for adult and pediatric patients, comparing them with diagnostic reference levels in the literature. Patients were divided into age groups and the following image acquisition parameters were collected: age, kV, mAs, Volumetric Computed Tomography Dose Index (CTDIvol) and DLP. The effective dose was found multiplying DLP by correction factors. The results were obtained from the third quartile and showed the importance of determining kV and mAs values for each patient depending on the studied region, age and thickness. (author)

  2. Cardiac output measurement instruments controlled by microprocessors

    International Nuclear Information System (INIS)

    Spector, M.; Barritault, L.; Boeri, C.; Fauchet, M.; Gambini, D.; Vernejoul, P. de

    The nuclear medicine and biophysics laboratory of the Necker-Enfants malades University Hospital Centre has built a microprocessor controlled Cardiac flowmetre. The principle of the cardiac output measurement from a radiocardiogram is well established. After injection of a radioactive indicator upstream from the heart cavities the dilution curve is obtained by the use of a gamma-ray precordial detector. This curve normally displays two peaks due to passage of the indicator into the right and left sides of the heart respectively. The output is then obtained from the stewart Hamilton principle once recirculation is eliminated. The graphic method used for the calculation however is long and tedious. The decreasing fraction of the dilution curve is projected in logarithmic space in order to eliminate recirculation by determining the mean straight line from which the decreasing exponential is obtained. The principle of the use of microprocessors is explained (electronics, logics) [fr

  3. Unregulated heat output of a storage heater

    OpenAIRE

    Lysak, Oleg Віталійович

    2017-01-01

    In the article the factors determining the heat transfer between the outer surfaces of a storage heater and the ambient air. This heat exchange is unregulated, and its definition is a precondition for assessing heat output range of this type of units. It was made the analysis of the literature on choosing insulating materials for each of the external surfaces of storage heaters: in foreign literature, there are recommendations on the use of various types of insulation depending on the type of...

  4. Computing multiple-output regression quantile regions

    Czech Academy of Sciences Publication Activity Database

    Paindaveine, D.; Šiman, Miroslav

    2012-01-01

    Roč. 56, č. 4 (2012), s. 840-853 ISSN 0167-9473 R&D Projects: GA MŠk(CZ) 1M06047 Institutional research plan: CEZ:AV0Z10750506 Keywords : halfspace depth * multiple-output regression * parametric linear programming * quantile regression Subject RIV: BA - General Mathematics Impact factor: 1.304, year: 2012 http://library.utia.cas.cz/separaty/2012/SI/siman-0376413.pdf

  5. Galois connection for multiple-output operations

    Czech Academy of Sciences Publication Activity Database

    Jeřábek, Emil

    2018-01-01

    Roč. 79 (2018), č. článku 17. ISSN 0002-5240 EU Projects: European Commission(XE) 339691 - FEALORA Institutional support: RVO:67985840 Keywords : clones and coclones * Galois connection * multiple-output operations Subject RIV: BA - General Mathematics OBOR OECD: Pure mathematics Impact factor: 0.625, year: 2016 https://link.springer.com/ article /10.1007%2Fs00012-018-0499-7

  6. Carnot efficiency at divergent power output

    Science.gov (United States)

    Polettini, Matteo; Esposito, Massimiliano

    2017-05-01

    The widely debated feasibility of thermodynamic machines achieving Carnot efficiency at finite power has been convincingly dismissed. Yet, the common wisdom that efficiency can only be optimal in the limit of infinitely slow processes overlooks the dual scenario of infinitely fast processes. We corroborate that efficient engines at divergent power output are not theoretically impossible, framing our claims within the theory of Stochastic Thermodynamics. We inspect the case of an electronic quantum dot coupled to three particle reservoirs to illustrate the physical rationale.

  7. Galois connection for multiple-output operations

    Czech Academy of Sciences Publication Activity Database

    Jeřábek, Emil

    2018-01-01

    Roč. 79, č. 2 (2018), č. článku 17. ISSN 0002-5240 EU Projects: European Commission(XE) 339691 - FEALORA Institutional support: RVO:67985840 Keywords : clones and coclones * Galois connection * multiple-output operations Subject RIV: BA - General Mathematics OBOR OECD: Pure mathematics Impact factor: 0.625, year: 2016 https://link.springer.com/article/10.1007%2Fs00012-018-0499-7

  8. Tangential Volumetric Modulated Radiotherapy - A New Technique for Large Scalp Lesions with a Case Study in Lentigo Maligna

    Directory of Open Access Journals (Sweden)

    E. Daniel Santos

    2015-06-01

    Full Text Available Introduction: Dose homogeneity within and dose conformity to the target volume can be a challenge to achieve when treating large area scalp lesions. Traditionally High Dose Rate (HDR brachytherapy (BT scalp moulds have been considered the ultimate conformal therapy. We have developed a new technique, Tangential Volumetric Modulated Arc Therapy (TVMAT that treats with the beam tangential to the surface of the scalp. In the TVMAT plan the collimating jaws protect dose-sensitive tissue in close proximity to the planning target volume (PTV. Not all the PTV is within the beam aperture as defined by the jaws during all the beam-on time. We report the successful treatment of one patient. Methods: A patient with biopsy proven extensive lentigo maligna on the scalp was simulated and three plans were created; one using a HDR brachytherapy surface mould, another using a conventional VMAT technique and a third using our new TVMAT technique. The patient was prescribed 55 Gy in 25 fractions. Plans were optimised so that PTV V100% = 100%. Plans were compared using Dose-Value Histogram (DVH analysis, and homogeneity and conformity indices. Results: BT, VMAT and TVMAT PTV median coverage was 105.51%, 103.46% and 103.62%, with homogeneity index of 0.33, 0.07 and 0.07 and the conformity index of 0.30, 0.69 and 0.83 respectively. The median dose to the left hippocampus was 11.8 Gy, 9.0 Gy and 0.6 Gy and the median dose to the right hippocampus was 12.6 Gy, 9.4 Gy and 0.7 Gy for the BT, VMAT and TVMAT respectively. Overall TVMAT delivered the least doses to the surrounding organs, BT delivered the highest. Conclusions: TVMAT was superior to VMAT which was in turn superior to BT in PTV coverage, conformity and homogeneity and delivery of dose to the surrounding organs at risk. The patient was successfully treated to full dose with TVMAT. TVMAT was verified as being the best amongst the three techniques in a second patient.

  9. Toward a Philosophy and Theory of Volumetric Nonthermal Processing.

    Science.gov (United States)

    Sastry, Sudhir K

    2016-06-01

    Nonthermal processes for food preservation have been under intensive investigation for about the past quarter century, with varying degrees of success. We focus this discussion on two volumetrically acting nonthermal processes, high pressure processing (HPP) and pulsed electric fields (PEF), with emphasis on scientific understanding of each, and the research questions that need to be addressed for each to be more successful in the future. We discuss the character or "philosophy" of food preservation, with a question about the nature of the kill step(s), and the sensing challenges that need to be addressed. For HPP, key questions and needs center around whether its nonthermal effectiveness can be increased by increased pressures or pulsing, the theoretical treatment of rates of reaction as influenced by pressure, the assumption of uniform pressure distribution, and the need for (and difficulties involved in) in-situ measurement. For PEF, the questions include the rationale for pulsing, difficulties involved in continuous flow treatment chambers, the difference between electroporation theory and experimental observations, and the difficulties involved in in-situ measurement and monitoring of electric field distribution. © 2016 Institute of Food Technologists®

  10. Determination of delta ferrite volumetric fraction in austenitic stainless steel

    International Nuclear Information System (INIS)

    Almeida Macedo, W.A. de.

    1983-01-01

    Measurements of delta ferrite volumetric fraction in AISI 304 austenitic stainless steels were done by X-ray diffraction, quantitative metallography (point count) and by means of one specific commercial apparatus whose operational principle is magnetic-inductive: The Ferrite Content Meter 1053 / Institut Dr. Foerster. The results obtained were comparated with point count, the reference method. It was also investigated in these measurements the influence of the martensite induced by mechanical deformation. Determinations by X-ray diffraction, by the ratio between integrated intensities of the ferrite (211) and austenite (311) lines, are in excelent agreement with those taken by point count. One correction curve for the lectures of the commercial equipment in focus was obtained, for the range between zero and 20% of delta ferrite in 18/8 stainless steels. It is demonstrated that, depending on the employed measurement method and surface finishing of the material to be analysed, the presence of martensite produced by mechanical deformation of the austenitic matrix is one problem to be considered. (Author) [pt

  11. Volumetric real-time imaging using a CMUT ring array.

    Science.gov (United States)

    Choe, Jung Woo; Oralkan, Ömer; Nikoozadeh, Amin; Gencel, Mustafa; Stephens, Douglas N; O'Donnell, Matthew; Sahn, David J; Khuri-Yakub, Butrus T

    2012-06-01

    A ring array provides a very suitable geometry for forward-looking volumetric intracardiac and intravascular ultrasound imaging. We fabricated an annular 64-element capacitive micromachined ultrasonic transducer (CMUT) array featuring a 10-MHz operating frequency and a 1.27-mm outer radius. A custom software suite was developed to run on a PC-based imaging system for real-time imaging using this device. This paper presents simulated and experimental imaging results for the described CMUT ring array. Three different imaging methods--flash, classic phased array (CPA), and synthetic phased array (SPA)--were used in the study. For SPA imaging, two techniques to improve the image quality--Hadamard coding and aperture weighting--were also applied. The results show that SPA with Hadamard coding and aperture weighting is a good option for ring-array imaging. Compared with CPA, it achieves better image resolution and comparable signal-to-noise ratio at a much faster image acquisition rate. Using this method, a fast frame rate of up to 463 volumes per second is achievable if limited only by the ultrasound time of flight; with the described system we reconstructed three cross-sectional images in real-time at 10 frames per second, which was limited by the computation time in synthetic beamforming.

  12. Intuitive Exploration of Volumetric Data Using Dynamic Galleries.

    Science.gov (United States)

    Jönsson, Daniel; Falk, Martin; Ynnerman, Anders

    2016-01-01

    In this work we present a volume exploration method designed to be used by novice users and visitors to science centers and museums. The volumetric digitalization of artifacts in museums is of rapidly increasing interest as enhanced user experience through interactive data visualization can be achieved. This is, however, a challenging task since the vast majority of visitors are not familiar with the concepts commonly used in data exploration, such as mapping of visual properties from values in the data domain using transfer functions. Interacting in the data domain is an effective way to filter away undesired information but it is difficult to predict where the values lie in the spatial domain. In this work we make extensive use of dynamic previews instantly generated as the user explores the data domain. The previews allow the user to predict what effect changes in the data domain will have on the rendered image without being aware that visual parameters are set in the data domain. Each preview represents a subrange of the data domain where overview and details are given on demand through zooming and panning. The method has been designed with touch interfaces as the target platform for interaction. We provide a qualitative evaluation performed with visitors to a science center to show the utility of the approach.

  13. Femoral head osteonecrosis: Volumetric MRI assessment and outcome

    International Nuclear Information System (INIS)

    Bassounas, Athanasios E.; Karantanas, Apostolos H.; Fotiadis, Dimitrios I.; Malizos, Konstantinos N.

    2007-01-01

    Effective treatment of femoral head osteonecrosis (FHON) requires early diagnosis and accurate assessment of the disease severity. The ability to predict in the early stages the risk of collapse is important for selecting a joint salvage procedure. The aim of the present study was to evaluate the outcome in patients treated with vascularized fibular grafts in relation to preoperative MR imaging volumetry. We studied 58 patients (87 hips) with FHON. A semi-automated octant-based lesion measurement method, previously described, was performed on the T1-w MR images. The mean time of postoperative follow-up was 7.8 years. Sixty-three hips were successful and 24 failed and converted to total hip arthroplasty within a period of 2-4 years after the initial operation. The rate of failures for hips of male patients was higher than in female patients. The mean lesion size was 28% of the sphere equivalent of the femoral head, 24 ± 12% for the successful hips and 37 ± 9% for the failed (p < 0.001). The most affected octants were antero-supero-medial (58 ± 26%) and postero-supero-medial (54 ± 31%). All but postero-infero-medial and postero-infero-lateral octants, showed statistically significant differences in the lesion size between patients with successful and failed hips. In conclusion, the volumetric analysis of preoperative MRI provides useful information with regard to a successful outcome in patients treated with vascularized fibular grafts

  14. A volumetric flow sensor for automotive injection systems

    International Nuclear Information System (INIS)

    Schmid, U; Krötz, G; Schmitt-Landsiedel, D

    2008-01-01

    For further optimization of the automotive power train of diesel engines, advanced combustion processes require a highly flexible injection system, provided e.g. by the common rail (CR) injection technique. In the past, the feasibility to implement injection nozzle volumetric flow sensors based on the thermo-resistive measurement principle has been demonstrated up to injection pressures of 135 MPa (1350 bar). To evaluate the transient behaviour of the system-integrated flow sensors as well as an injection amount indicator used as a reference method, hydraulic simulations on the system level are performed for a CR injection system. Experimentally determined injection timings were found to be in good agreement with calculated values, especially for the novel sensing element which is directly implemented into the hydraulic system. For the first time pressure oscillations occurring after termination of the injection pulse, predicted theoretically, could be verified directly in the nozzle. In addition, the injected amount of fuel is monitored with the highest resolution ever reported in the literature

  15. Volumetric associations between uncinate fasciculus, amygdala, and trait anxiety

    Directory of Open Access Journals (Sweden)

    Baur Volker

    2012-01-01

    Full Text Available Abstract Background Recent investigations of white matter (WM connectivity suggest an important role of the uncinate fasciculus (UF, connecting anterior temporal areas including the amygdala with prefrontal-/orbitofrontal cortices, for anxiety-related processes. Volume of the UF, however, has rarely been investigated, but may be an important measure of structural connectivity underlying limbic neuronal circuits associated with anxiety. Since UF volumetric measures are newly applied measures, it is necessary to cross-validate them using further neural and behavioral indicators of anxiety. Results In a group of 32 subjects not reporting any history of psychiatric disorders, we identified a negative correlation between left UF volume and trait anxiety, a finding that is in line with previous results. On the other hand, volume of the left amygdala, which is strongly connected with the UF, was positively correlated with trait anxiety. In addition, volumes of the left UF and left amygdala were inversely associated. Conclusions The present study emphasizes the role of the left UF as candidate WM fiber bundle associated with anxiety-related processes and suggests that fiber bundle volume is a WM measure of particular interest. Moreover, these results substantiate the structural relatedness of UF and amygdala by a non-invasive imaging method. The UF-amygdala complex may be pivotal for the control of trait anxiety.

  16. Parkinson's disease: diagnostic utility of volumetric imaging

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Wei-Che; Chen, Meng-Hsiang [Kaohsiung Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Department of Diagnostic Radiology, Kaohsiung (China); Chou, Kun-Hsien [National Yang-Ming University, Brain Research Center, Taipei (China); Lee, Pei-Lin [National Yang-Ming University, Department of Biomedical Imaging and Radiological Sciences, Taipei (China); Tsai, Nai-Wen; Lu, Cheng-Hsien [Kaohsiung Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Department of Neurology, Kaohsiung (China); Chen, Hsiu-Ling [Kaohsiung Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Department of Diagnostic Radiology, Kaohsiung (China); National Yang-Ming University, Department of Biomedical Imaging and Radiological Sciences, Taipei (China); Hsu, Ai-Ling [National Taiwan University, Institute of Biomedical Electronics and Bioinformatics, Taipei (China); Huang, Yung-Cheng [Kaohsiung Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Department of Nuclear Medicine, Kaohsiung (China); Lin, Ching-Po [National Yang-Ming University, Brain Research Center, Taipei (China); National Yang-Ming University, Department of Biomedical Imaging and Radiological Sciences, Taipei (China)

    2017-04-15

    This paper aims to examine the effectiveness of structural imaging as an aid in the diagnosis of Parkinson's disease (PD). High-resolution T{sub 1}-weighted magnetic resonance imaging was performed in 72 patients with idiopathic PD (mean age, 61.08 years) and 73 healthy subjects (mean age, 58.96 years). The whole brain was parcellated into 95 regions of interest using composite anatomical atlases, and region volumes were calculated. Three diagnostic classifiers were constructed using binary multiple logistic regression modeling: the (i) basal ganglion prior classifier, (ii) data-driven classifier, and (iii) basal ganglion prior/data-driven hybrid classifier. Leave-one-out cross validation was used to unbiasedly evaluate the predictive accuracy of imaging features. Pearson's correlation analysis was further performed to correlate outcome measurement using the best PD classifier with disease severity. Smaller volume in susceptible regions is diagnostic for Parkinson's disease. Compared with the other two classifiers, the basal ganglion prior/data-driven hybrid classifier had the highest diagnostic reliability with a sensitivity of 74%, specificity of 75%, and accuracy of 74%. Furthermore, outcome measurement using this classifier was associated with disease severity. Brain structural volumetric analysis with multiple logistic regression modeling can be a complementary tool for diagnosing PD. (orig.)

  17. Normative biometrics for fetal ocular growth using volumetric MRI reconstruction.

    Science.gov (United States)

    Velasco-Annis, Clemente; Gholipour, Ali; Afacan, Onur; Prabhu, Sanjay P; Estroff, Judy A; Warfield, Simon K

    2015-04-01

    To determine normative ranges for fetal ocular biometrics between 19 and 38 weeks gestational age (GA) using volumetric MRI reconstruction. The 3D images of 114 healthy fetuses between 19 and 38 weeks GA were created using super-resolution volume reconstructions from MRI slice acquisitions. These 3D images were semi-automatically segmented to measure fetal orbit volume, binocular distance (BOD), interocular distance (IOD), and ocular diameter (OD). All biometry correlated with GA (Volume, Pearson's correlation coefficient (CC) = 0.9680; BOD, CC = 0.9552; OD, CC = 0.9445; and IOD, CC = 0.8429), and growth curves were plotted against linear and quadratic growth models. Regression analysis showed quadratic models to best fit BOD, IOD, and OD and a linear model to best fit volume. Orbital volume had the greatest correlation with GA, although BOD and OD also showed strong correlation. The normative data found in this study may be helpful for the detection of congenital fetal anomalies with more consistent measurements than are currently available. © 2015 John Wiley & Sons, Ltd. © 2015 John Wiley & Sons, Ltd.

  18. Determination of delta ferrite volumetric fraction in austenitic stainless steels

    International Nuclear Information System (INIS)

    Almeida Macedo, W.A. de.

    1983-01-01

    Measurements of delta ferrite volumetric fraction in AISI 304 austenitic stainless steels were done by X-ray difraction, quantitative metallography (point count) and by means of one specific commercial apparatus whose operational principle is magnetic-inductive: The Ferrite Content Meter 1053 / Institut Dr. Forster. The results obtained were comparated with point count, the reference method. It was also investigated in these measurements the influence of the martensite induced by mechanical deformation. Determinations by X-ray diffraction, by the ratio between integrated intensities of the ferrite (211) and austenite (311) lines, are in excelent agreement with those taken by point count. One correction curve for the lectures of the commercial equipment in focus was obtained, for the range between zero and 20% of delta ferrite in 18/8 stainless steels. It is demonstrated that, depending on the employed measurement method and surface finishing of the material to be analysed, the presence of martensite produced by mechanical deformation of the austenitic matrix is one problem to be considered. (Author) [pt

  19. A volumetric flow sensor for automotive injection systems

    Science.gov (United States)

    Schmid, U.; Krötz, G.; Schmitt-Landsiedel, D.

    2008-04-01

    For further optimization of the automotive power train of diesel engines, advanced combustion processes require a highly flexible injection system, provided e.g. by the common rail (CR) injection technique. In the past, the feasibility to implement injection nozzle volumetric flow sensors based on the thermo-resistive measurement principle has been demonstrated up to injection pressures of 135 MPa (1350 bar). To evaluate the transient behaviour of the system-integrated flow sensors as well as an injection amount indicator used as a reference method, hydraulic simulations on the system level are performed for a CR injection system. Experimentally determined injection timings were found to be in good agreement with calculated values, especially for the novel sensing element which is directly implemented into the hydraulic system. For the first time pressure oscillations occurring after termination of the injection pulse, predicted theoretically, could be verified directly in the nozzle. In addition, the injected amount of fuel is monitored with the highest resolution ever reported in the literature.

  20. Region-of-interest volumetric visual hull refinement

    KAUST Repository

    Knoblauch, Daniel

    2010-01-01

    This paper introduces a region-of-interest visual hull refinement technique, based on flexible voxel grids for volumetric visual hull reconstructions. Region-of-interest refinement is based on a multipass process, beginning with a focussed visual hull reconstruction, resulting in a first 3D approximation of the target, followed by a region-of-interest estimation, tasked with identifying features of interest, which in turn are used to locally refine the voxel grid and extract a higher-resolution surface representation for those regions. This approach is illustrated for the reconstruction of avatars for use in tele-immersion environments, where head and hand regions are of higher interest. To allow reproducability and direct comparison a publicly available data set for human visual hull reconstruction is used. This paper shows that region-of-interest reconstruction of the target is faster and visually comparable to higher resolution focused visual hull reconstructions. This approach reduces the amount of data generated through the reconstruction, allowing faster post processing, as rendering or networking of the surface voxels. Reconstruction speeds support smooth interactions between the avatar and the virtual environment, while the improved resolution of its facial region and hands creates a higher-degree of immersion and potentially impacts the perception of body language, facial expressions and eye-to-eye contact. Copyright © 2010 by the Association for Computing Machinery, Inc.

  1. Fetal brain volumetry through MRI volumetric reconstruction and segmentation

    Science.gov (United States)

    Estroff, Judy A.; Barnewolt, Carol E.; Connolly, Susan A.; Warfield, Simon K.

    2013-01-01

    Purpose Fetal MRI volumetry is a useful technique but it is limited by a dependency upon motion-free scans, tedious manual segmentation, and spatial inaccuracy due to thick-slice scans. An image processing pipeline that addresses these limitations was developed and tested. Materials and methods The principal sequences acquired in fetal MRI clinical practice are multiple orthogonal single-shot fast spin echo scans. State-of-the-art image processing techniques were used for inter-slice motion correction and super-resolution reconstruction of high-resolution volumetric images from these scans. The reconstructed volume images were processed with intensity non-uniformity correction and the fetal brain extracted by using supervised automated segmentation. Results Reconstruction, segmentation and volumetry of the fetal brains for a cohort of twenty-five clinically acquired fetal MRI scans was done. Performance metrics for volume reconstruction, segmentation and volumetry were determined by comparing to manual tracings in five randomly chosen cases. Finally, analysis of the fetal brain and parenchymal volumes was performed based on the gestational age of the fetuses. Conclusion The image processing pipeline developed in this study enables volume rendering and accurate fetal brain volumetry by addressing the limitations of current volumetry techniques, which include dependency on motion-free scans, manual segmentation, and inaccurate thick-slice interpolation. PMID:20625848

  2. An MRI-based semiautomated volumetric quantification of hip osteonecrosis

    International Nuclear Information System (INIS)

    Malizos, K.N.; Siafakas, M.S.; Karachalios, T.S.; Fotiadis, D.I.; Soucacos, P.N.

    2001-01-01

    Objective: To objectively and precisely define the spatial distribution of osteonecrosis and to investigate the influence of various factors including etiology. Design: A volumetric method is presented to describe the size and spatial distribution of necrotic lesions of the femoral head, using MRI scans. The technique is based on the definition of an equivalent sphere model for the femoral head. Patients: The gender, age, number of hips involved, disease duration, pain intensity, limping disability and etiology were correlated with the distribution of the pathologic bone. Seventy-nine patients with 122 hips affected by osteonecrosis were evaluated. Results: The lesion size ranged from 7% to 73% of the sphere equivalent. The lateral octants presented considerable variability, ranging from wide lateral lesions extending beyond the lip of the acetabulum, to narrow medial lesions, leaving a lateral supporting pillar of intact bone. Patients with sickle cell disease and steroid administration presented the largest lesions. The extent of the posterior superior medial octant involvement correlated with the symptom intensity, a younger age and male gender. Conclusion: The methodology presented here has proven a reliable and straightforward imaging tool for precise assessment of necrotic lesions. It also enables us to target accurately the drilling and grafting procedures. (orig.)

  3. Volumetric PIV behind mangrove-type root models

    Science.gov (United States)

    Kazemi, Amirkhosro; van de Riet, Keith; Curet, Oscar M.

    2017-11-01

    Mangrove trees form dense networks of prop roots in coastal intertidal zones. The interaction of mangroves with the tidal flow is fundamental in estuaries and shoreline by providing water filtration, protection against erosion and habitat for aquatic animals. In this work, we modeled the mangrove prop roots with a cluster of rigid circular cylinders (patch) to investigate its hydrodynamics. We conducted 2-D PIV and V3V in the near- and far-wake in the recirculating water channel. Two models were considered: (1) a rigid patch, and (2) a flexible patch modeled as rigid cylinders with a flexible hinge. We found that Strouhal number changes with porosity while the patch diameter is constant. Based on the wake signature, we defined an effective diameter length scale. The volumetric flow measurements revealed a regular shedding forming von Kármán vortices for the rigid patch while the flexible patch produced a less uniform wake where vortices were substantially distorted. We compare the wake structure between that 2-D PIV and V3V. This analysis of the hydrodynamics of mangrove-root like models can also be extended to understand other complex flows including bio-inspired coastal infrastructures, damping-wave systems, and energy harvesting devices.

  4. Volumetric neuroimaging in Usher syndrome: evidence of global involvement.

    Science.gov (United States)

    Schaefer, G B; Bodensteiner, J B; Thompson, J N; Kimberling, W J; Craft, J M

    1998-08-27

    Usher syndrome is a group of genetic disorders consisting of congenital sensorineural hearing loss and retinitis pigmentosa of variable onset and severity depending on the genetic type. It was suggested that the psychosis of Usher syndrome might be secondary to a metabolic degeneration involving the brain more diffusely. There have been reports of focal and diffuse atrophic changes in the supratentorial brain as well as atrophy of some of the structures of the posterior fossa. We previously performed quantitative analysis of magnetic resonance imaging studies of 19 Usher syndrome patients (12 with type I and 7 with type II) looking at the cerebellum and various cerebellar components. We found atrophy of the cerebellum in both types and sparing of cerebellar vermis lobules I-V in type II Usher syndrome patients only. We now have studied another group of 19 patients (with some overlap in the patients studied from the previous report) with Usher syndrome (8 with type I, 11 with type II). We performed quantitative volumetric measurements of various brain structures compared to age- and sex-matched controls. We found a significant decrease in intracranial volume and in size of the brain and cerebellum with a trend toward an increase in the size of the subarachnoid spaces. These data suggest that the disease process in Usher syndrome involves the entire brain and is not limited to the posterior fossa or auditory and visual systems.

  5. Burst firing enhances neural output correlation

    Directory of Open Access Journals (Sweden)

    Ho Ka eChan

    2016-05-01

    Full Text Available Neurons communicate and transmit information predominantly through spikes. Given that experimentally observed neural spike trains in a variety of brain areas can be highly correlated, it is important to investigate how neurons process correlated inputs. Most previous work in this area studied the problem of correlation transfer analytically by making significant simplifications on neural dynamics. Temporal correlation between inputs that arises from synaptic filtering, for instance, is often ignored when assuming that an input spike can at most generate one output spike. Through numerical simulations of a pair of leaky integrate-and-fire (LIF neurons receiving correlated inputs, we demonstrate that neurons in the presence of synaptic filtering by slow synapses exhibit strong output correlations. We then show that burst firing plays a central role in enhancing output correlations, which can explain the above-mentioned observation because synaptic filtering induces bursting. The observed changes of correlations are mostly on a long time scale. Our results suggest that other features affecting the prevalence of neural burst firing in biological neurons, e.g., adaptive spiking mechanisms, may play an important role in modulating the overall level of correlations in neural networks.

  6. Multi-model MPC with output feedback

    Directory of Open Access Journals (Sweden)

    J. M. Perez

    2014-03-01

    Full Text Available In this work, a new formulation is presented for the model predictive control (MPC of a process system that is represented by a finite set of models, each one corresponding to a different operating point. The general case is considered of systems with stable and integrating outputs in closed-loop with output feedback. For this purpose, the controller is based on a non-minimal order model where the state is built with the measured outputs and the manipulated inputs of the control system. Therefore, the state can be considered as perfectly known and, consequently, there is no need to include a state observer in the control loop. This property of the proposed modeling approach is convenient to extend previous stability results of the closed loop system with robust MPC controllers based on state feedback. The controller proposed here is based on the solution of two optimization problems that are solved sequentially at the same time step. The method is illustrated with a simulated example of the process industry. The rigorous simulation of the control of an adiabatic flash of a multi-component hydrocarbon mixture illustrates the application of the robust controller. The dynamic simulation of this process is performed using EMSO - Environment Model Simulation and Optimization. Finally, a comparison with a linear MPC using a single model is presented.

  7. Solar Power Station Output Inverter Control Design

    Directory of Open Access Journals (Sweden)

    J. Bauer

    2011-04-01

    Full Text Available The photovoltaic applications spreads in these days fast, therefore they also undergo great development. Because the amount of the energy obtained from the panel depends on the surrounding conditions, as intensity of the sun exposure or the temperature of the solar array, the converter must be connected to the panel output. The Solar system equipped with inverter can supply small loads like notebooks, mobile chargers etc. in the places where the supplying network is not present. Or the system can be used as a generator and it shall deliver energy to the supply network. Each type of the application has different requirements on the converter and its control algorithm. But for all of them the one thing is common – the maximal efficiency. The paper focuses on design and simulation of the low power inverter that acts as output part of the whole converter. In the paper the design of the control algorithm of the inverter for both types of inverter application – for islanding mode and for operation on the supply grid – is discussed. Attention is also paid to the design of the output filter that should reduce negative side effects of the converter on the supply network.

  8. DIFFERENTIAL ANALYSIS OF VOLUMETRIC STRAINS IN POROUS MATERIALS IN TERMS OF WATER FREEZING

    Directory of Open Access Journals (Sweden)

    Rusin Z.

    2013-06-01

    Full Text Available The paper presents the differential analysis of volumetric strain (DAVS. The method allows measurements of volumetric deformations of capillary-porous materials caused by water-ice phase change. The VSE indicator (volumetric strain effect, which under certain conditions can be interpreted as the minimum degree of phase change of water contained in the material pores, is proposed. The test results (DAVS for three materials with diversified microstructure: clinker brick, calcium-silicate brick and Portland cement mortar were compared with the test results for pore characteristics obtained with the mercury intrusion porosimetry.

  9. Comparison of surface contour and volumetric three-dimensional imaging of the musculoskeletal system

    International Nuclear Information System (INIS)

    Guilford, W.B.; Ullrich, C.G.; Moore, T.

    1988-01-01

    Both surface contour and volumetric three-dimensional image processing from CT data can provide accurate demonstration of skeletal anatomy. While realistic, surface contour images may obscure fine detail such as nondisplaced fractures, and thin bone may disappear. Volumetric processing can provide high detail, but the transparency effect is unnatural and may yield a confusing image. Comparison of both three-dimensional modes is presented to demonstrate those findings best shown with each and to illustrate helpful techniques to improve volumetric display, such as disarticulation of unnecessary anatomy, short-angle repeating rotation (dithering), and image combination into overlay displays

  10. A new method for measuring aerosol nebulizers output using radioactive tracers

    International Nuclear Information System (INIS)

    Gatnash, A.A.; Connolly, C.K.; Chandler, S.T.

    1998-01-01

    Reproducibility and comparability of bronchial challenge tests depends critically on accurate assessment of nebulizers output. Evaporation during nebulization means that simple weighing is inaccurate, overestimating the delivered dose of active ingredient. We wanted to quantify this effect in the context of intermittent nebulization, using a dosimeter as used in bronchial provocation tests. Output of three types of nebulizers, from the MEFAR dosimeter, was measured by radioactive tracer, using a standard solution of technetium-99m-pertechnetate (1.5 kBq x mL -1 ) in 4 mL of normal saline. The aerosol was impacted by suction onto a micro filter, and the radioactivity measured. Nebulizers were weighed before and after nebulization. Ratio of nebulized volume calculated from the radioactivity on the filter, to the total volume loss by weight, was expressed as nebulized ratio. The effect on output of two concentrations of methacholine, two tracers of different weights, and change in temperature, were assessed. Nebulized ratio varied between 44.1-71.6%. Results were more consistent within the same type of nebulizer than between different makes. Neither changes in molar concentration nor molecular weight affected nebulizer output or nebulized ratio. Mean nebulized ratio was 58.5%, showing that calibration by weighing, overestimates the delivered dose by a factor of approximately two. Measuring radioactivity eluted from a micro filter, onto which nebulized output had been impacted proved to be a satisfactory method of calibration. (au)

  11. Modelling simple helically delivered dose distributions

    International Nuclear Information System (INIS)

    Fenwick, John D; Tome, Wolfgang A; Kissick, Michael W; Mackie, T Rock

    2005-01-01

    In a previous paper, we described quality assurance procedures for Hi-Art helical tomotherapy machines. Here, we develop further some ideas discussed briefly in that paper. Simple helically generated dose distributions are modelled, and relationships between these dose distributions and underlying characteristics of Hi-Art treatment systems are elucidated. In particular, we describe the dependence of dose levels along the central axis of a cylinder aligned coaxially with a Hi-Art machine on fan beam width, couch velocity and helical delivery lengths. The impact on these dose levels of angular variations in gantry speed or output per linear accelerator pulse is also explored

  12. Commissioning and Acceptance Testing of the existing linear accelerator upgraded to volumetric modulated arc therapy

    Science.gov (United States)

    Varadharajan, Ekambaram; Ramasubramanian, Velayudham

    2013-01-01

    Aim The RapidArc commissioning and Acceptance Testing program will test and ensure accuracy in DMLC position, precise dose-rate control during gantry rotation and accurate control of gantry speed. Background Recently, we have upgraded our linear accelerator capable of performing IMRT which was functional from 2007 with image guided RapidArc facility. The installation of VMAT in the existing linear accelerator is a tedious process which requires many quality assurance procedures before the proper commissioning of the facility and these procedures are discussed in this study. Materials and methods Output of the machine at different dose rates was measured to verify its consistency at different dose rates. Monitor and chamber linearity at different dose rates were checked. DMLC QA comprising of MLC transmission factor measurement and dosimetric leaf gap measurements were performed using 0.13 cm3 and 0.65 cm3 Farmer type ionization chamber, dose 1 dosimeter, and IAEA 30 cm × 30 cm × 30 cm water phantom. Picket fence test, garden fence test, tests to check leaf positioning accuracy due to carriage movement, calibration of the leaves, leaf speed stability effects due to the acceleration and deceleration of leaves, accuracy and calibration of leaves in producing complex fields, effects of interleaf friction, etc. were verified using EDR2 therapy films, Vidar scanner, Omnipro accept software, amorphous silicon based electronic portal imaging device and EPIQA software.1–8 Results All the DMLC related quality assurance tests were performed and evaluated by film dosimetry, portal dosimetry and EPIQA.7 Conclusion Results confirmed that the linear accelerator is capable of performing accurate VMAT. PMID:24416566

  13. Commissioning and Acceptance Testing of the existing linear accelerator upgraded to volumetric modulated arc therapy.

    Science.gov (United States)

    Varadharajan, Ekambaram; Ramasubramanian, Velayudham

    2013-01-01

    The RapidArc commissioning and Acceptance Testing program will test and ensure accuracy in DMLC position, precise dose-rate control during gantry rotation and accurate control of gantry speed. Recently, we have upgraded our linear accelerator capable of performing IMRT which was functional from 2007 with image guided RapidArc facility. The installation of VMAT in the existing linear accelerator is a tedious process which requires many quality assurance procedures before the proper commissioning of the facility and these procedures are discussed in this study. Output of the machine at different dose rates was measured to verify its consistency at different dose rates. Monitor and chamber linearity at different dose rates were checked. DMLC QA comprising of MLC transmission factor measurement and dosimetric leaf gap measurements were performed using 0.13 cm(3) and 0.65 cm(3) Farmer type ionization chamber, dose 1 dosimeter, and IAEA 30 cm × 30 cm × 30 cm water phantom. Picket fence test, garden fence test, tests to check leaf positioning accuracy due to carriage movement, calibration of the leaves, leaf speed stability effects due to the acceleration and deceleration of leaves, accuracy and calibration of leaves in producing complex fields, effects of interleaf friction, etc. were verified using EDR2 therapy films, Vidar scanner, Omnipro accept software, amorphous silicon based electronic portal imaging device and EPIQA software.(1-8.) All the DMLC related quality assurance tests were performed and evaluated by film dosimetry, portal dosimetry and EPIQA.(7.) Results confirmed that the linear accelerator is capable of performing accurate VMAT.

  14. Early clinical experience of radiotherapy of prostate cancer with volumetric modulated arc therapy

    Directory of Open Access Journals (Sweden)

    Valli Mariacarla

    2010-06-01

    Full Text Available Abstract Background To report about initial clinical experience in radiation treatment of carcinoma of prostate with volumetric modulated arcs with the RapidArc (RA technology. Methods Forty-five patients with a median age of 72 ± 3, affected by prostate carcinoma (T1c: 22 patients, T2a-b: 17 patients, T3a-b: 6 patients. N0: 43 patients, N1-Nx: 2 patients, all M0, with initial PSA of 10.0 ± 3.0 ng/mL, were treated with RapidArc in a feasibility study. All patients were treated with single arc using 6MV photons. Dose prescription ranged between 76 (7 patients and 78 Gy (38 patients in 2Gy/fraction. Plan quality was assessed by means of Dose Volume Histogram (DVH analysis. Technical parameters of arcs and pre-treatment quality assurance results (Gamma Agreement Index, GAI are reported to describe delivery features. Early toxicity was scored (according to the Common Terminology Criteria of Adverse Effects scale, CTCAE, scale at the end of treatment together with biochemical outcome (PSA. Results From DVH data, target coverage was fulfilling planning objectives: V95% was in average higher than 98% and V107%~0.0% (D2%~104.0% in average. Homogeneity D5%-D95% ranged between 6.2 ± 1.0% to 6.7 ± 1.3%. For rectum, all planning objectives were largely met (e.g. V70Gy = 10.7 ± 5.5% against an objective of 2% = 79.4 ± 1.2Gy against an objective of 80.0Gy. Maximum dose to femurs was D2% = 36.7 ± 5.4Gy against an objective of 47Gy. Monitor Units resulted: MU/Gy = 239 ± 37. Average beam on time was 1.24 ± 0.0 minutes. Pre-treatment GAI resulted in 98.1 ± 1.1%. Clinical data were recorded as PSA at 6 weeks after RT, with median values of 0.4 ± 0.4 ng/mL. Concerning acute toxicity, no patient showed grade 2-3 rectal toxicity; 5/42 (12% patients experienced grade 2 dysuria; 18/41 (44% patients preserved complete or partial erectile function. Conclusion RapidArc proved to be a safe, qualitative and advantageous treatment modality for prostate cancer.

  15. Radiotherapy with volumetric modulated arc therapy for hepatocellular carcinoma patients ineligible for surgery or ablative treatments

    Energy Technology Data Exchange (ETDEWEB)

    Wang, P.M.; Chung, N.N.; Chang, F.L. [Cheng-Ching General Hospital, Taichung, Taiwan (China). Dept. of Radiation Oncology; Hsu, W.C. [Cheng-Ching General Hospital, Taichung, Taiwan (China). Dept. of Radiation Oncology; Asia Univ., Taichung, Taiwan (China). Dept. of Healthcare Administration; Fogliata, A.; Cozzi, L. [Oncology Institute of Southern Switzerland, Bellinzona (Switzerland)

    2013-04-15

    The aim of this article is to report the dosimetric and clinical findings in the treatment of primary hepatocellular carcinoma (HCC) with volumetric modulated arc therapy (VMAT, RapidArc). A total of 138 patients were investigated. Dose prescription ranged from 45-66 Gy. Most patients (88.4 %) presented AJCC stage III or IV and 83 % were N0-M0. All were classified as Barcelona Clinic Liver Cancer (BCLC) stage A-C. All patients were treated using 10 MV photons with single or multiple, coplanar or non-coplanar arcs, and cone-down technique in case of early response of tumors. The patients' median age was 66 years (range 27-87 years), 83 % were treated with 60 Gy (12 % at 45 Gy, 6 % at 66 Gy), 62 % with cone-down, 98 % with multiple arcs. The mean initial planning target volume (PTV) was 777 {+-} 632 cm{sup 3}; the mean final PTV (after the cone-down) was 583 {+-} 548 cm{sup 3}. High target coverage was achieved. The final PTV was V{sub 98%} > 98 %. Kidneys received on average 5 and 8 Gy (left and right), while the maximum dose to the spinal cord was 22 Gy; mean doses to esophagus and stomach were 23 Gy and 15 Gy, respectively. The average volume of healthy liver receiving more than 30 Gy was 294 {+-} 145 cm{sup 3}. Overall survival at 12 months was 45 %; median survival was 10.3 months (95 % confidence interval 7.2-13.3 months). Actuarial local control at 6 months was 95 % and 93.7 % at 12 months. The median follow-up was 9 months and a maximum of 28 months. This study showed from the dosimetric point of view the feasibility and technical appropriateness of RapidArc for the treatment of HCC. Clinical results were positive and might suggest, with appropriate care, to consider RapidArc as an additional therapeutic opportunity for these patients. (orig.)

  16. Cardiac Exposure in the Dynamic Conformal Arc Therapy, Intensity-Modulated Radiotherapy and Volumetric Modulated Arc Therapy of Lung Cancer.

    Directory of Open Access Journals (Sweden)

    Xin Ming

    Full Text Available To retrospectively evaluate the cardiac exposure in three cohorts of lung cancer patients treated with dynamic conformal arc therapy (DCAT, intensity-modulated radiotherapy (IMRT, or volumetric modulated arc therapy (VMAT at our institution in the past seven years.A total of 140 lung cancer patients were included in this institutional review board approved study: 25 treated with DCAT, 70 with IMRT and 45 with VMAT. All plans were generated in a same commercial treatment planning system and have been clinically accepted and delivered. The dose distribution to the heart and the effects of tumor laterality, the irradiated heart volume and the beam-to-heart distance on the cardiac exposure were investigated.The mean dose to the heart among all 140 plans was 4.5 Gy. Specifically, the heart received on average 2.3, 5.2 and 4.6 Gy in the DCAT, IMRT and VMAT plans, respectively. The mean heart doses for the left and right lung tumors were 4.1 and 4.8 Gy, respectively. No patients died with evidence of cardiac disease. Three patients (2% with preexisting cardiac condition developed cardiac disease after treatment. Furthermore, the cardiac exposure was found to increase linearly with the irradiated heart volume while decreasing exponentially with the beam-to-heart distance.Compared to old technologies for lung cancer treatment, modern radiotherapy treatment modalities demonstrated better heart sparing. But the heart dose in lung cancer radiotherapy is still higher than that in the radiotherapy of breast cancer and Hodgkin's disease where cardiac complications have been extensively studied. With strong correlations of mean heart dose with beam-to-heart distance and irradiated heart volume, cautions should be exercised to avoid long-term cardiac toxicity in the lung cancer patients undergoing radiotherapy.

  17. An Analysis of Plan Robustness for Esophageal Tumors: Comparing Volumetric Modulated Arc Therapy Plans and Spot Scanning Proton Planning

    International Nuclear Information System (INIS)

    Warren, Samantha; Partridge, Mike; Bolsi, Alessandra; Lomax, Anthony J.; Hurt, Chris; Crosby, Thomas; Hawkins, Maria A.

    2016-01-01

    Purpose: Planning studies to compare x-ray and proton techniques and to select the most suitable technique for each patient have been hampered by the nonequivalence of several aspects of treatment planning and delivery. A fair comparison should compare similarly advanced delivery techniques from current clinical practice and also assess the robustness of each technique. The present study therefore compared volumetric modulated arc therapy (VMAT) and single-field optimization (SFO) spot scanning proton therapy plans created using a simultaneous integrated boost (SIB) for dose escalation in midesophageal cancer and analyzed the effect of setup and range uncertainties on these plans. Methods and Materials: For 21 patients, SIB plans with a physical dose prescription of 2 Gy or 2.5 Gy/fraction in 25 fractions to planning target volume (PTV)_5_0_G_y or PTV_6_2_._5_G_y (primary tumor with 0.5 cm margins) were created and evaluated for robustness to random setup errors and proton range errors. Dose–volume metrics were compared for the optimal and uncertainty plans, with P<.05 (Wilcoxon) considered significant. Results: SFO reduced the mean lung dose by 51.4% (range 35.1%-76.1%) and the mean heart dose by 40.9% (range 15.0%-57.4%) compared with VMAT. Proton plan robustness to a 3.5% range error was acceptable. For all patients, the clinical target volume D_9_8 was 95.0% to 100.4% of the prescribed dose and gross tumor volume (GTV) D_9_8 was 98.8% to 101%. Setup error robustness was patient anatomy dependent, and the potential minimum dose per fraction was always lower with SFO than with VMAT. The clinical target volume D_9_8 was lower by 0.6% to 7.8% of the prescribed dose, and the GTV D_9_8 was lower by 0.3% to 2.2% of the prescribed GTV dose. Conclusions: The SFO plans achieved significant sparing of normal tissue compared with the VMAT plans for midesophageal cancer. The target dose coverage in the SIB proton plans was less robust to random setup errors and might be

  18. An Analysis of Plan Robustness for Esophageal Tumors: Comparing Volumetric Modulated Arc Therapy Plans and Spot Scanning Proton Planning

    Energy Technology Data Exchange (ETDEWEB)

    Warren, Samantha, E-mail: samantha.warren@oncology.ox.ac.uk [Cancer Research UK/Medical Research Council Oxford Institute for Radiation Oncology, Gray Laboratories, University of Oxford, Oxford (United Kingdom); Partridge, Mike [Cancer Research UK/Medical Research Council Oxford Institute for Radiation Oncology, Gray Laboratories, University of Oxford, Oxford (United Kingdom); Bolsi, Alessandra; Lomax, Anthony J. [Centre for Proton Therapy, Paul Scherrer Institute, Villigen (Switzerland); Hurt, Chris [Wales Cancer Trials Unit, School of Medicine, Heath Park, Cardiff (United Kingdom); Crosby, Thomas [Velindre Cancer Centre, Velindre Hospital, Cardiff (United Kingdom); Hawkins, Maria A. [Cancer Research UK/Medical Research Council Oxford Institute for Radiation Oncology, Gray Laboratories, University of Oxford, Oxford (United Kingdom)

    2016-05-01

    Purpose: Planning studies to compare x-ray and proton techniques and to select the most suitable technique for each patient have been hampered by the nonequivalence of several aspects of treatment planning and delivery. A fair comparison should compare similarly advanced delivery techniques from current clinical practice and also assess the robustness of each technique. The present study therefore compared volumetric modulated arc therapy (VMAT) and single-field optimization (SFO) spot scanning proton therapy plans created using a simultaneous integrated boost (SIB) for dose escalation in midesophageal cancer and analyzed the effect of setup and range uncertainties on these plans. Methods and Materials: For 21 patients, SIB plans with a physical dose prescription of 2 Gy or 2.5 Gy/fraction in 25 fractions to planning target volume (PTV){sub 50Gy} or PTV{sub 62.5Gy} (primary tumor with 0.5 cm margins) were created and evaluated for robustness to random setup errors and proton range errors. Dose–volume metrics were compared for the optimal and uncertainty plans, with P<.05 (Wilcoxon) considered significant. Results: SFO reduced the mean lung dose by 51.4% (range 35.1%-76.1%) and the mean heart dose by 40.9% (range 15.0%-57.4%) compared with VMAT. Proton plan robustness to a 3.5% range error was acceptable. For all patients, the clinical target volume D{sub 98} was 95.0% to 100.4% of the prescribed dose and gross tumor volume (GTV) D{sub 98} was 98.8% to 101%. Setup error robustness was patient anatomy dependent, and the potential minimum dose per fraction was always lower with SFO than with VMAT. The clinical target volume D{sub 98} was lower by 0.6% to 7.8% of the prescribed dose, and the GTV D{sub 98} was lower by 0.3% to 2.2% of the prescribed GTV dose. Conclusions: The SFO plans achieved significant sparing of normal tissue compared with the VMAT plans for midesophageal cancer. The target dose coverage in the SIB proton plans was less robust to random setup

  19. PPARα-dependent increase of mouse urine output by gemfibrozil and fenofibrate.

    Science.gov (United States)

    Song, Danjun; Luo, Min; Dai, Manyun; Bu, Shizhong; Wang, Weihua; Zhang, Burong; Gonzalez, Frank J; Liu, Aiming

    2017-02-01

    While gemfibrozil and fenofibrate are prescribed for anti-dyslipidemia treatment, a rational basis for the use of these drugs for treatment of dyslipidemia with concurrent metabolic syndrome has not been established. In this study, wild-type and Pparα-null mice were fed gemfibrozil- or fenofibrate-containing diets for 14 days. Urine output (24 h) was monitored, and urine, serum, and liver and kidney tissues were subjected to toxicity assessment. A 2-month challenge followed by a 2-week wash-out was performed for gemfibrozil to determine urine output and the potential toxicity. A therapeutically equivalent dose of gemfibrozil was more effective than fenofibrate in increasing urine output. This regulatory effect was not observed in Pparα-null mice. In contrast, hepatomegaly induced by fenofibrate was more pronounced than that of gemfibrozil. No significant toxicity was observed in liver or kidney in the 2-month treatment with gemfibrozil. These data demonstrated PPARα mediates the increased urine output by fibrates. Considering the relative action on hepatomegaly and the regulatory effect on urine output, gemfibrozil may be the preferable drug to increase urine output. These results revealed a new pharmacodynamic effect of clinically prescribed PPARα agonists and suggested the potential value of gemfibrozil in modification of blood pressure.

  20. Dose and dose rate monitor

    International Nuclear Information System (INIS)

    Novakova, O.; Ryba, J.; Slezak, V.; Svobodova, B.; Viererbl, L.

    1984-10-01

    The methods are discussea of measuring dose rate or dose using a scintillation counte. A plastic scintillator based on polystyrene with PBD and POPOP activators and coated with ZnS(Ag) was chosen for the projected monitor. The scintillators were cylindrical and spherical in shape and of different sizes; black polypropylene tubes were chosen as the best case for the probs. For the counter with different plastic scintillators, the statistical error 2σ for natural background was determined. For determining the suitable thickness of the ZnS(Ag) layer the energy dependence of the counter was measured. Radioisotopes 137 Cs, 241 Am and 109 Cd were chosen as radiation sources. The best suited ZnS(Ag) thickness was found to be 0.5 μm. Experiments were carried out to determine the directional dependence of the detector response and the signal to noise ratio. The temperature dependence of the detector response and its compensation were studied, as were the time stability and fatigue manifestations of the photomultiplier. The design of a laboratory prototype of a dose rate and dose monitor is described. Block diagrams are given of the various functional parts of the instrument. The designed instrument is easiiy portable, battery powered, measures dose rates from natural background in the range of five orders, i.e., 10 -2 to 10 3 nGy/s, and allows to determine a dose of up to 10 mGy. Accouracy of measurement in the energy range of 50 keV to 1 MeV is better than +-20%. (E.S.)

  1. Inkjet printing-based volumetric display projecting multiple full-colour 2D patterns

    Science.gov (United States)

    Hirayama, Ryuji; Suzuki, Tomotaka; Shimobaba, Tomoyoshi; Shiraki, Atsushi; Naruse, Makoto; Nakayama, Hirotaka; Kakue, Takashi; Ito, Tomoyoshi

    2017-04-01

    In this study, a method to construct a full-colour volumetric display is presented using a commercially available inkjet printer. Photoreactive luminescence materials are minutely and automatically printed as the volume elements, and volumetric displays are constructed with high resolution using easy-to-fabricate means that exploit inkjet printing technologies. The results experimentally demonstrate the first prototype of an inkjet printing-based volumetric display composed of multiple layers of transparent films that yield a full-colour three-dimensional (3D) image. Moreover, we propose a design algorithm with 3D structures that provide multiple different 2D full-colour patterns when viewed from different directions and experimentally demonstrate prototypes. It is considered that these types of 3D volumetric structures and their fabrication methods based on widely deployed existing printing technologies can be utilised as novel information display devices and systems, including digital signage, media art, entertainment and security.

  2. The Effect of Volumetric Porosity on Roughness Element Drag

    Science.gov (United States)

    Gillies, John; Nickling, William; Nikolich, George; Etyemezian, Vicken

    2016-04-01

    Much attention has been given to understanding how the porosity of two dimensional structures affects the drag force exerted by boundary-layer flow on these flow obstructions. Porous structures such as wind breaks and fences are typically used to control the sedimentation of sand and snow particles or create micro-habitats in their lee. Vegetation in drylands also exerts control on sediment transport by wind due to aerodynamic effects and interaction with particles in transport. Recent research has also demonstrated that large spatial arrays of solid three dimensional roughness elements can be used to reduce sand transport to specified targets for control of wind erosion through the effect of drag partitioning and interaction of the moving sand with the large (>0.3 m high) roughness elements, but porous elements may improve the effectiveness of this approach. A thorough understanding of the role porosity plays in affecting the drag force on three-dimensional forms is lacking. To provide basic understanding of the relationship between the porosity of roughness elements and the force of drag exerted on them by fluid flow, we undertook a wind tunnel study that systematically altered the porosity of roughness elements of defined geometry (cubes, rectangular cylinders, and round cylinders) and measured the associated change in the drag force on the elements under similar Reynolds number conditions. The elements tested were of four basic forms: 1) same sized cubes with tubes of known diameter milled through them creating three volumetric porosity values and increasing connectivity between the tubes, 2) cubes and rectangular cylinders constructed of brass screen that nested within each other, and 3) round cylinders constructed of brass screen that nested within each other. The two-dimensional porosity, defined as the ratio of total surface area of the empty space to the solid surface area of the side of the element presented to the fluid flow was conserved at 0.519 for

  3. Influence of Special Weather on Output of PV System

    Science.gov (United States)

    Zhang, Zele

    2018-01-01

    The output of PV system is affected by different environmental factors, therefore, it is important to study the output of PV system under different environmental conditions. Through collecting data on the spot, collecting the output of photovoltaic panels under special weather conditions, and comparing the collected data, the output characteristics of the photovoltaic panels under different weather conditions are obtained. The influence of weather factors such as temperature, humidity and irradiance on the output of photovoltaic panels was investigated.

  4. Dose modeling in ultraviolet phototherapy

    International Nuclear Information System (INIS)

    Grimes, David Robert; Robbins, Chris; O'Hare, Neil John

    2010-01-01

    Purpose: Ultraviolet phototherapy is widely used in the treatment of numerous skin conditions. This treatment is well established and largely beneficial to patients on both physical and psychological levels; however, overexposure to ultraviolet radiation (UVR) can have detrimental effects, such as erythemal responses and ocular damage in addition to the potentially carcinogenic nature of UVR. For these reasons, it is essential to control and quantify the radiation dose incident upon the patient to ensure that it is both biologically effective and has the minimal possible impact on the surrounding unaffected tissue. Methods: To date, there has been little work on dose modeling, and the output of artificial UVR sources is an area where research has been recommended. This work characterizes these sources by formalizing an approach from first principles and experimentally examining this model. Results: An implementation of a line source model is found to give impressive accuracy and quantifies the output radiation well. Conclusions: This method could potentially serve as a basis for a full computational dose model for quantifying patient dose.

  5. An MRI volumetric study for leg muscles in congenital clubfoot.

    Science.gov (United States)

    Ippolito, Ernesto; Dragoni, Massimiliano; Antonicoli, Marco; Farsetti, Pasquale; Simonetti, Giovanni; Masala, Salvatore

    2012-10-01

    To investigate both volume and length of the three muscle compartments of the normal and the affected leg in unilateral congenital clubfoot. Volumetric magnetic resonance imaging (VMRI) of the anterior, lateral and postero-medial muscular compartments of both the normal and the clubfoot leg was obtained in three groups of seven patients each, whose mean age was, respectively, 4.8 months, 11.1 months and 4.7 years. At diagnosis, all the unilateral congenital clubfeet had a Pirani score ranging from 4.5 to 5.5 points, and all of them had been treated according to a strict Ponseti protocol. All the feet had percutaneous lengthening of the Achilles tendon. A mean difference in both volume and length was found between the three muscular compartments of the leg, with the muscles of the clubfoot side being thinner and shorter than those of the normal side. The distal tendon of the tibialis anterior, peroneus longus and triceps surae (Achilles tendon) were longer than normal on the clubfoot side. Our study shows that the three muscle compartments of the clubfoot leg are thinner and shorter than normal in the patients of the three groups. The difference in the musculature volume of the postero-medial compartment between the normal and the affected side increased nine-fold from age group 2 to 3, while the difference in length increased by 20 %, thus, showing that the muscles of the postero-medial compartment tend to grow in both thickness and length much less than the muscles of the other leg compartments.

  6. Semiautomatic segmentation of liver metastases on volumetric CT images

    International Nuclear Information System (INIS)

    Yan, Jiayong; Schwartz, Lawrence H.; Zhao, Binsheng

    2015-01-01

    Purpose: Accurate segmentation and quantification of liver metastases on CT images are critical to surgery/radiation treatment planning and therapy response assessment. To date, there are no reliable methods to perform such segmentation automatically. In this work, the authors present a method for semiautomatic delineation of liver metastases on contrast-enhanced volumetric CT images. Methods: The first step is to manually place a seed region-of-interest (ROI) in the lesion on an image. This ROI will (1) serve as an internal marker and (2) assist in automatically identifying an external marker. With these two markers, lesion contour on the image can be accurately delineated using traditional watershed transformation. Density information will then be extracted from the segmented 2D lesion and help determine the 3D connected object that is a candidate of the lesion volume. The authors have developed a robust strategy to automatically determine internal and external markers for marker-controlled watershed segmentation. By manually placing a seed region-of-interest in the lesion to be delineated on a reference image, the method can automatically determine dual threshold values to approximately separate the lesion from its surrounding structures and refine the thresholds from the segmented lesion for the accurate segmentation of the lesion volume. This method was applied to 69 liver metastases (1.1–10.3 cm in diameter) from a total of 15 patients. An independent radiologist manually delineated all lesions and the resultant lesion volumes served as the “gold standard” for validation of the method’s accuracy. Results: The algorithm received a median overlap, overestimation ratio, and underestimation ratio of 82.3%, 6.0%, and 11.5%, respectively, and a median average boundary distance of 1.2 mm. Conclusions: Preliminary results have shown that volumes of liver metastases on contrast-enhanced CT images can be accurately estimated by a semiautomatic segmentation

  7. Hepatosplenic volumetric assessment at MDCT for staging liver fibrosis

    Energy Technology Data Exchange (ETDEWEB)

    Pickhardt, Perry J.; Malecki, Kyle; Hunt, Oliver F.; Beaumont, Claire; Kloke, John; Ziemlewicz, Timothy J.; Lubner, Meghan G. [University of Wisconsin School of Medicine and Public Health, Department of Radiology, Madison, WI (United States)

    2017-07-15

    To investigate hepatosplenic volumetry at MDCT for non-invasive prediction of hepatic fibrosis. Hepatosplenic volume analysis in 624 patients (mean age, 48.8 years; 311 M/313 F) at MDCT was performed using dedicated software and compared against pathological fibrosis stage (F0 = 374; F1 = 48; F2 = 40; F3 = 65; F4 = 97). The liver segmental volume ratio (LSVR) was defined by Couinaud segments I-III over segments IV-VIII. All pre-cirrhotic fibrosis stages (METAVIR F1-F3) were based on liver biopsy within 1 year of MDCT. LSVR and total splenic volumes increased with stage of fibrosis, with mean(±SD) values of: F0: 0.26 ± 0.06 and 215.1 ± 88.5 mm{sup 3}; F1: 0.25 ± 0.08 and 294.8 ± 153.4 mm{sup 3}; F2: 0.331 ± 0.12 and 291.6 ± 197.1 mm{sup 3}; F3: 0.39 ± 0.15 and 509.6 ± 402.6 mm{sup 3}; F4: 0.56 ± 0.30 and 790.7 ± 450.3 mm{sup 3}, respectively. Total hepatic volumes showed poor discrimination (F0: 1674 ± 320 mm{sup 3}; F4: 1631 ± 691 mm{sup 3}). For discriminating advanced fibrosis (≥F3), the ROC AUC values for LSVR, total liver volume, splenic volume and LSVR/spleen combined were 0.863, 0.506, 0.890 and 0.947, respectively. Relative changes in segmental liver volumes and total splenic volume allow for non-invasive staging of hepatic fibrosis, whereas total liver volume is a poor predictor. Unlike liver biopsy or elastography, these CT volumetric biomarkers can be obtained retrospectively on routine scans obtained for other indications. (orig.)

  8. Systematic Parameterization, Storage, and Representation of Volumetric DICOM Data.

    Science.gov (United States)

    Fischer, Felix; Selver, M Alper; Gezer, Sinem; Dicle, Oğuz; Hillen, Walter

    Tomographic medical imaging systems produce hundreds to thousands of slices, enabling three-dimensional (3D) analysis. Radiologists process these images through various tools and techniques in order to generate 3D renderings for various applications, such as surgical planning, medical education, and volumetric measurements. To save and store these visualizations, current systems use snapshots or video exporting, which prevents further optimizations and requires the storage of significant additional data. The Grayscale Softcopy Presentation State extension of the Digital Imaging and Communications in Medicine (DICOM) standard resolves this issue for two-dimensional (2D) data by introducing an extensive set of parameters, namely 2D Presentation States (2DPR), that describe how an image should be displayed. 2DPR allows storing these parameters instead of storing parameter applied images, which cause unnecessary duplication of the image data. Since there is currently no corresponding extension for 3D data, in this study, a DICOM-compliant object called 3D presentation states (3DPR) is proposed for the parameterization and storage of 3D medical volumes. To accomplish this, the 3D medical visualization process is divided into four tasks, namely pre-processing, segmentation, post-processing, and rendering. The important parameters of each task are determined. Special focus is given to the compression of segmented data, parameterization of the rendering process, and DICOM-compliant implementation of the 3DPR object. The use of 3DPR was tested in a radiology department on three clinical cases, which require multiple segmentations and visualizations during the workflow of radiologists. The results show that 3DPR can effectively simplify the workload of physicians by directly regenerating 3D renderings without repeating intermediate tasks, increase efficiency by preserving all user interactions, and provide efficient storage as well as transfer of visualized data.

  9. Blockwise conjugate gradient methods for image reconstruction in volumetric CT.

    Science.gov (United States)

    Qiu, W; Titley-Peloquin, D; Soleimani, M

    2012-11-01

    Cone beam computed tomography (CBCT) enables volumetric image reconstruction from 2D projection data and plays an important role in image guided radiation therapy (IGRT). Filtered back projection is still the most frequently used algorithm in applications. The algorithm discretizes the scanning process (forward projection) into a system of linear equations, which must then be solved to recover images from measured projection data. The conjugate gradients (CG) algorithm and its variants can be used to solve (possibly regularized) linear systems of equations Ax=b and linear least squares problems minx∥b-Ax∥2, especially when the matrix A is very large and sparse. Their applications can be found in a general CT context, but in tomography problems (e.g. CBCT reconstruction) they have not widely been used. Hence, CBCT reconstruction using the CG-type algorithm LSQR was implemented and studied in this paper. In CBCT reconstruction, the main computational challenge is that the matrix A usually is very large, and storing it in full requires an amount of memory well beyond the reach of commodity computers. Because of these memory capacity constraints, only a small fraction of the weighting matrix A is typically used, leading to a poor reconstruction. In this paper, to overcome this difficulty, the matrix A is partitioned and stored blockwise, and blockwise matrix-vector multiplications are implemented within LSQR. This implementation allows us to use the full weighting matrix A for CBCT reconstruction without further enhancing computer standards. Tikhonov regularization can also be implemented in this fashion, and can produce significant improvement in the reconstructed images. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

  10. Input and output constraints affecting irrigation development

    Science.gov (United States)

    Schramm, G.

    1981-05-01

    In many of the developing countries the expansion of irrigated agriculture is used as a major development tool for bringing about increases in agricultural output, rural economic growth and income distribution. Apart from constraints imposed by water availability, the major limitations considered to any acceleration of such programs are usually thought to be those of costs and financial resources. However, as is shown on the basis of empirical data drawn from Mexico, in reality the feasibility and effectiveness of such development programs is even more constrained by the lack of specialized physical and human factors on the input and market limitations on the output side. On the input side, the limited availability of complementary factors such as, for example, truly functioning credit systems for small-scale farmers or effective agricultural extension services impose long-term constraints on development. On the output side the limited availability, high risk, and relatively slow growth of markets for high-value crops sharply reduce the usually hoped-for and projected profitable crop mix that would warrant the frequently high costs of irrigation investments. Three conclusions are drawn: (1) Factors in limited supply have to be shadow-priced to reflect their high opportunity costs in alternative uses. (2) Re-allocation of financial resources from immediate construction of projects to longer-term increase in the supply of scarce, highly-trained manpower resources are necessary in order to optimize development over time. (3) Inclusion of high-value, high-income producing crops in the benefit-cost analysis of new projects is inappropriate if these crops could potentially be grown in already existing projects.

  11. Need and trends of volumetric tests in recurring inspection of pressurized components in pressurized water reactors

    International Nuclear Information System (INIS)

    Bergemann, W.

    1982-01-01

    On the basis of the types of stress occurring in nuclear power plants and of practical results it has been shown that cracks in primary circuit components arise due to operating stresses in both the materials surfaces and the bulk of the materials. For this reason, volumetric materials testing is necessary in addition to surface testing. An outlook is given on the trends of volumetric testing. (author)

  12. On output measurements via radiation pressure

    DEFF Research Database (Denmark)

    Leeman, S.; Healey, A.J.; Forsberg, F.

    1990-01-01

    It is shown, by simple physical argument, that measurements of intensity with a radiation pressure balance should not agree with those based on calorimetric techniques. The conclusion is ultimately a consequence of the circumstance that radiation pressure measurements relate to wave momentum, while...... calorimetric methods relate to wave energy. Measurements with some typical ultrasound fields are performed with a novel type of hydrophone, and these allow an estimate to be made of the magnitude of the discrepancy to be expected between the two types of output measurement in a typical case....

  13. On directional multiple-output quantile regression

    Czech Academy of Sciences Publication Activity Database

    Paindaveine, D.; Šiman, Miroslav

    2011-01-01

    Roč. 102, č. 2 (2011), s. 193-212 ISSN 0047-259X R&D Projects: GA MŠk(CZ) 1M06047 Grant - others:Commision EC(BE) Fonds National de la Recherche Scientifique Institutional research plan: CEZ:AV0Z10750506 Keywords : multivariate quantile * quantile regression * multiple-output regression * halfspace depth * portfolio optimization * value-at risk Subject RIV: BA - General Mathematics Impact factor: 0.879, year: 2011 http://library.utia.cas.cz/separaty/2011/SI/siman-0364128.pdf

  14. Uncertainties in predicting solar panel power output

    Science.gov (United States)

    Anspaugh, B.

    1974-01-01

    The problem of calculating solar panel power output at launch and during a space mission is considered. The major sources of uncertainty and error in predicting the post launch electrical performance of the panel are considered. A general discussion of error analysis is given. Examples of uncertainty calculations are included. A general method of calculating the effect on the panel of various degrading environments is presented, with references supplied for specific methods. A technique for sizing a solar panel for a required mission power profile is developed.

  15. Output-Sensitive Pattern Extraction in Sequences

    DEFF Research Database (Denmark)

    Grossi, Roberto; Menconi, Giulia; Pisanti, Nadia

    2014-01-01

    Genomic Analysis, Plagiarism Detection, Data Mining, Intrusion Detection, Spam Fighting and Time Series Analysis are just some examples of applications where extraction of recurring patterns in sequences of objects is one of the main computational challenges. Several notions of patterns exist...... or extend them causes a loss of significant information (where the number of occurrences changes). Output-sensitive algorithms have been proposed to enumerate and list these patterns, taking polynomial time O(nc) per pattern for constant c > 1, which is impractical for massive sequences of very large length...

  16. Utilization of INIS output in Czechoslovakia

    International Nuclear Information System (INIS)

    Stanik, Z.; Blazek, J.

    1978-01-01

    Information on INIS output materials - INIS magnetic tape, INIS Atomindex, full texts of non-conventional literature on microfiches. Complex is provided of INIS-SDI service by the Nuclear Information Centre for CSSR. The Unified Software System (USS) of the UVTEI-UTZ (the Central Technical Base of the Central Office for Scientific, Technical and Economic Information) is used for the automated processing of INIS magnetic tapes. A survey of INIS-SDI services in the years 1974 to 1978 is given. The further development of the system consists in the use of the terminal network, with direct access to the IAEA computer in Vienna. (author)

  17. Series asymmetric supercapacitors based on free-standing inner-connection electrodes for high energy density and high output voltage

    Science.gov (United States)

    Tao, Jiayou; Liu, Nishuang; Rao, Jiangyu; Ding, Longwei; Al Bahrani, Majid Raissan; Li, Luying; Su, Jun; Gao, Yihua

    2014-11-01

    Asymmetric supercapacitors (ASCs) based on free-standing membranes with high energy density and high output voltage are reported. MnO2 nanowire/carbon nanotube (CNT) composites and MoO3 nanobelt/CNT composites are selected as the anode and the cathode materials of the devices, respectively. The ASC has a high volumetric capacitance of 50.2 F cm-3 at a scan rate of 2 mV s-1 and a high operation voltage window of 2.0 V. Especially, after a middle layer with an inner-connection structure was inserted between the anode and the cathode, the output voltage of the whole device can achieve 4.0 V. The full cell of series ASCs (SASC) with an inner-connection middle layer has a high energy density of 28.6 mW h cm-3 at a power density of 261.4 mW cm-3, and exhibits excellent cycling performance of 99.6% capacitance retention over 10 000 cycles. This strategy of designing the hybridized structure for SASCs provides a promising route for next-generation SCs with high energy density and high output voltage.Asymmetric supercapacitors (ASCs) based on free-standing membranes with high energy density and high output voltage are reported. MnO2 nanowire/carbon nanotube (CNT) composites and MoO3 nanobelt/CNT composites are selected as the anode and the cathode materials of the devices, respectively. The ASC has a high volumetric capacitance of 50.2 F cm-3 at a scan rate of 2 mV s-1 and a high operation voltage window of 2.0 V. Especially, after a middle layer with an inner-connection structure was inserted between the anode and the cathode, the output voltage of the whole device can achieve 4.0 V. The full cell of series ASCs (SASC) with an inner-connection middle layer has a high energy density of 28.6 mW h cm-3 at a power density of 261.4 mW cm-3, and exhibits excellent cycling performance of 99.6% capacitance retention over 10 000 cycles. This strategy of designing the hybridized structure for SASCs provides a promising route for next-generation SCs with high energy density and high

  18. Correction of measured Gamma-Knife output factors for angular dependence of diode detectors and PinPoint ionization chamber.

    Science.gov (United States)

    Hršak, Hrvoje; Majer, Marija; Grego, Timor; Bibić, Juraj; Heinrich, Zdravko

    2014-12-01

    Dosimetry for Gamma-Knife requires detectors with high spatial resolution and minimal angular dependence of response. Angular dependence and end effect time for p-type silicon detectors (PTW Diode P and Diode E) and PTW PinPoint ionization chamber were measured with Gamma-Knife beams. Weighted angular dependence correction factors were calculated for each detector. The Gamma-Knife output factors were corrected for angular dependence and end effect time. For Gamma-Knife beams angle range of 84°-54°. Diode P shows considerable angular dependence of 9% and 8% for the 18 mm and 14, 8, 4 mm collimator, respectively. For Diode E this dependence is about 4% for all collimators. PinPoint ionization chamber shows angular dependence of less than 3% for 18, 14 and 8 mm helmet and 10% for 4 mm collimator due to volumetric averaging effect in a small photon beam. Corrected output factors for 14 mm helmet are in very good agreement (within ±0.3%) with published data and values recommended by vendor (Elekta AB, Stockholm, Sweden). For the 8 mm collimator diodes are still in good agreement with recommended values (within ±0.6%), while PinPoint gives 3% less value. For the 4 mm helmet Diodes P and E show over-response of 2.8% and 1.8%, respectively. For PinPoint chamber output factor of 4 mm collimator is 25% lower than Elekta value which is generally not consequence of angular dependence, but of volumetric averaging effect and lack of lateral electronic equilibrium. Diodes P and E represent good choice for Gamma-Knife dosimetry. Copyright © 2014 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

  19. Vector-model-supported optimization in volumetric-modulated arc stereotactic radiotherapy planning for brain metastasis

    International Nuclear Information System (INIS)

    Liu, Eva Sau Fan; Wu, Vincent Wing Cheung; Harris, Benjamin; Foote, Matthew; Lehman, Margot; Chan, Lawrence Wing Chi

    2017-01-01

    Long planning time in volumetric-modulated arc stereotactic radiotherapy (VMA-SRT) cases can limit its clinical efficiency and use. A vector model could retrieve previously successful radiotherapy cases that share various common anatomic features with the current case. The prsent study aimed to develop a vector model that could reduce planning time by applying the optimization parameters from those retrieved reference cases. Thirty-six VMA-SRT cases of brain metastasis (gender, male [n = 23], female [n = 13]; age range, 32 to 81 years old) were collected and used as a reference database. Another 10 VMA-SRT cases were planned with both conventional optimization and vector-model-supported optimization, following the oncologists' clinical dose prescriptions. Planning time and plan quality measures were compared using the 2-sided paired Wilcoxon signed rank test with a significance level of 0.05, with positive false discovery rate (pFDR) of less than 0.05. With vector-model-supported optimization, there was a significant reduction in the median planning time, a 40% reduction from 3.7 to 2.2 hours (p = 0.002, pFDR = 0.032), and for the number of iterations, a 30% reduction from 8.5 to 6.0 (p = 0.006, pFDR = 0.047). The quality of plans from both approaches was comparable. From these preliminary results, vector-model-supported optimization can expedite the optimization of VMA-SRT for brain metastasis while maintaining plan quality.

  20. Target tracking using DMLC for volumetric modulated arc therapy: A simulation study

    Energy Technology Data Exchange (ETDEWEB)

    Sun Baozhou; Rangaraj, Dharanipathy; Papiez, Lech; Oddiraju, Swetha; Yang Deshan; Li, H. Harold [Department of Radiation Oncology, School of Medicine, Washington University, 4921 Parkview Place, St. Louis, Missouri 63110 (United States); Department of Radiation Oncology, Southwestern Medical Center, University of Texas, Dallas, Texas 75390 (United States); Department of Radiation Oncology, School of Medicine, Washington University, 4921 Parkview Place, St. Louis, Missouri 63110 (United States)

    2010-12-15

    Purpose: Target tracking using dynamic multileaf collimator (DMLC) is a promising approach for intrafraction motion management in radiation therapy. The purpose of this work is to develop a DMLC tracking algorithm capable of delivering volumetric-modulated arc therapy (VMAT) to the targets that experience two-dimensional (2D) rigid motion in the beam's eye view. Methods: The problem of VMAT delivery to moving targets is formulated as a control problem with constraints. The relationships between gantry speed, gantry acceleration, MLC leaf-velocity, dose rate, and target motion are derived. An iterative search algorithm is developed to find numerical solutions for efficient delivery of a specific VMAT plan to the moving target using 2D DMLC tracking. The delivery of five VMAT lung plans is simulated. The planned and delivered fluence maps in the target-reference frame are calculated and compared. Results: The simulation demonstrates that the 2D tracking algorithm is capable of delivering the VMAT plan to a moving target fast and accurately without violating the machine constraints and the integrity of the treatment plan. The average delivery time is only 29 s longer than that of no-tracking delivery, 101 versus 72 s, respectively. The fluence maps are normalized to 200 MU and the average root-mean-square error between the desired and the delivered fluence is 2.1 MU, compared to 14.8 MU for no-tracking and 3.6 MU for one-dimensional tracking. Conclusions: A locally optimal MLC tracking algorithm for VMAT delivery is proposed, aiming at shortest delivery time while maintaining treatment plan invariant. The inconsequential increase of treatment time due to DMLC tracking is clinically desirable, which makes VMAT with DMLC tracking attractive in treating moving tumors.

  1. Vector-model-supported optimization in volumetric-modulated arc stereotactic radiotherapy planning for brain metastasis

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Eva Sau Fan [Department of Radiation Oncology, Princess Alexandra Hospital, Brisbane (Australia); Department of Health Technology and Informatics, The Hong Kong Polytechnic University (Hong Kong); Wu, Vincent Wing Cheung [Department of Health Technology and Informatics, The Hong Kong Polytechnic University (Hong Kong); Harris, Benjamin [Department of Radiation Oncology, Princess Alexandra Hospital, Brisbane (Australia); Foote, Matthew; Lehman, Margot [Department of Radiation Oncology, Princess Alexandra Hospital, Brisbane (Australia); School of Medicine, University of Queensland (Australia); Chan, Lawrence Wing Chi, E-mail: wing.chi.chan@polyu.edu.hk [Department of Health Technology and Informatics, The Hong Kong Polytechnic University (Hong Kong)

    2017-07-01

    Long planning time in volumetric-modulated arc stereotactic radiotherapy (VMA-SRT) cases can limit its clinical efficiency and use. A vector model could retrieve previously successful radiotherapy cases that share various common anatomic features with the current case. The prsent study aimed to develop a vector model that could reduce planning time by applying the optimization parameters from those retrieved reference cases. Thirty-six VMA-SRT cases of brain metastasis (gender, male [n = 23], female [n = 13]; age range, 32 to 81 years old) were collected and used as a reference database. Another 10 VMA-SRT cases were planned with both conventional optimization and vector-model-supported optimization, following the oncologists' clinical dose prescriptions. Planning time and plan quality measures were compared using the 2-sided paired Wilcoxon signed rank test with a significance level of 0.05, with positive false discovery rate (pFDR) of less than 0.05. With vector-model-supported optimization, there was a significant reduction in the median planning time, a 40% reduction from 3.7 to 2.2 hours (p = 0.002, pFDR = 0.032), and for the number of iterations, a 30% reduction from 8.5 to 6.0 (p = 0.006, pFDR = 0.047). The quality of plans from both approaches was comparable. From these preliminary results, vector-model-supported optimization can expedite the optimization of VMA-SRT for brain metastasis while maintaining plan quality.

  2. Feasibility of Single-Isocenter Volumetric Modulated Arc Radiosurgery for Treatment of Multiple Brain Metastases

    International Nuclear Information System (INIS)

    Clark, Grant M.; Popple, Richard A.; Young, P. Edward; Fiveash, John B.

    2010-01-01

    Purpose: To evaluate the relative plan quality of single-isocenter vs. multi-isocenter volumetric modulated arc therapy (VMAT) for radiosurgical treatment of multiple central nervous system metastases. Methods and Materials: VMAT plans were created using RapidArc technology for treatment of simulated patients with three brain metastases. The plans consisted of single-arc/single-isocenter, triple-arc (noncoplanar)/single-isocenter, and triple-arc (coplanar)/triple-isocenter configurations. All VMAT plans were normalized to deliver 100% of the 20-Gy prescription dose to all lesions. The plans were evaluated by calculation of Paddick and Radiation Therapy Oncology Group conformity index scores, Paddick gradient index scores, and 12-Gy isodose volumes. Results: All plans were judged clinically acceptable, but differences were observed in the dosimetric parameters, with the use of multiple noncoplanar arcs showing small improvements in the conformity indexes compared with the single-arc/single-isocenter and triple-arc (coplanar)/triple-isocenter plans. Multiple arc plans (triple-arc [noncoplanar]/single-isocenter and triple-arc [coplanar]/triple-isocenter) showed smaller 12-Gy isodose volumes in scenarios involving three metastases spaced closely together, with only small differences noted among all plans involving lesions spaced further apart. Conclusion: Our initial results suggest that single-isocenter VMAT plans can be used to deliver conformity equivalent to that of multiple isocenter VMAT techniques. For targets that are closely spaced, multiple noncoplanar single-isocenter arcs might be required. VMAT radiosurgery for multiple targets using a single isocenter can be efficiently delivered, requiring less than one-half the beam time required for multiple isocenter set ups. VMAT radiosurgery will likely replace multi-isocenter techniques for linear accelerator-based treatment of multiple targets.

  3. A quality assurance phantom for the performance evaluation of volumetric micro-CT systems

    Energy Technology Data Exchange (ETDEWEB)

    Du, Louise Y [Department of Medical Biophysics, University of Western Ontario, London, ON (Canada); Umoh, Joseph [Imaging Research Laboratories, Robarts Research Institute, London, ON (Canada); Nikolov, Hristo N [Imaging Research Laboratories, Robarts Research Institute, London, ON (Canada); Pollmann, Steven I [Imaging Research Laboratories, Robarts Research Institute, London, ON (Canada); Lee, Ting-Yim [Department of Medical Biophysics, University of Western Ontario, London, ON (Canada); Holdsworth, David W [Department of Medical Biophysics, University of Western Ontario, London, ON (Canada)

    2007-12-07

    Small-animal imaging has recently become an area of increased interest because more human diseases can be modeled in transgenic and knockout rodents. As a result, micro-computed tomography (micro-CT) systems are becoming more common in research laboratories, due to their ability to achieve spatial resolution as high as 10 {mu}m, giving highly detailed anatomical information. Most recently, a volumetric cone-beam micro-CT system using a flat-panel detector (eXplore Ultra, GE Healthcare, London, ON) has been developed that combines the high resolution of micro-CT and the fast scanning speed of clinical CT, so that dynamic perfusion imaging can be performed in mice and rats, providing functional physiological information in addition to anatomical information. This and other commercially available micro-CT systems all promise to deliver precise and accurate high-resolution measurements in small animals. However, no comprehensive quality assurance phantom has been developed to evaluate the performance of these micro-CT systems on a routine basis. We have designed and fabricated a single comprehensive device for the purpose of performance evaluation of micro-CT systems. This quality assurance phantom was applied to assess multiple image-quality parameters of a current flat-panel cone-beam micro-CT system accurately and quantitatively, in terms of spatial resolution, geometric accuracy, CT number accuracy, linearity, noise and image uniformity. Our investigations show that 3D images can be obtained with a limiting spatial resolution of 2.5 mm{sup -1} and noise of {+-}35 HU, using an acquisition interval of 8 s at an entrance dose of 6.4 cGy.

  4. A quality assurance phantom for the performance evaluation of volumetric micro-CT systems

    International Nuclear Information System (INIS)

    Du, Louise Y; Umoh, Joseph; Nikolov, Hristo N; Pollmann, Steven I; Lee, Ting-Yim; Holdsworth, David W

    2007-01-01

    Small-animal imaging has recently become an area of increased interest because more human diseases can be modeled in transgenic and knockout rodents. As a result, micro-computed tomography (micro-CT) systems are becoming more common in research laboratories, due to their ability to achieve spatial resolution as high as 10 μm, giving highly detailed anatomical information. Most recently, a volumetric cone-beam micro-CT system using a flat-panel detector (eXplore Ultra, GE Healthcare, London, ON) has been developed that combines the high resolution of micro-CT and the fast scanning speed of clinical CT, so that dynamic perfusion imaging can be performed in mice and rats, providing functional physiological information in addition to anatomical information. This and other commercially available micro-CT systems all promise to deliver precise and accurate high-resolution measurements in small animals. However, no comprehensive quality assurance phantom has been developed to evaluate the performance of these micro-CT systems on a routine basis. We have designed and fabricated a single comprehensive device for the purpose of performance evaluation of micro-CT systems. This quality assurance phantom was applied to assess multiple image-quality parameters of a current flat-panel cone-beam micro-CT system accurately and quantitatively, in terms of spatial resolution, geometric accuracy, CT number accuracy, linearity, noise and image uniformity. Our investigations show that 3D images can be obtained with a limiting spatial resolution of 2.5 mm -1 and noise of ±35 HU, using an acquisition interval of 8 s at an entrance dose of 6.4 cGy

  5. The Influence of Water and Mineral Oil On Volumetric Losses in a Hydraulic Motor

    Directory of Open Access Journals (Sweden)

    Śliwiński Pawel

    2017-04-01

    Full Text Available In this paper volumetric losses in hydraulic motor supplied with water and mineral oil (two liquids having significantly different viscosity and lubricating properties are described and compared. The experimental tests were conducted using an innovative hydraulic satellite motor, that is dedicated to work with different liquids, including water. The sources of leaks in this motor are also characterized and described. On this basis, a mathematical model of volumetric losses and model of effective rotational speed have been developed and presented. The results of calculation of volumetric losses according to the model are compared with the results of experiment. It was found that the difference is not more than 20%. Furthermore, it has been demonstrated that this model well describes in both the volumetric losses in the motor supplied with water and oil. Experimental studies have shown that the volumetric losses in the motor supplied with water are even three times greater than the volumetric losses in the motor supplied with oil. It has been shown, that in a small constant stream of water the speed of the motor is reduced even by half in comparison of speed of motor supplied with the same stream of oil.

  6. Influence of increment of gantry angle and number of arcs on esophageal volumetric modulated arc therapy planning in Monaco planning system: A planning study

    Directory of Open Access Journals (Sweden)

    L Nithya

    2014-01-01

    Full Text Available The objective of this study was to analyze the influence of the increment of gantry angle and the number of arcs on esophageal volumetric modulated arc therapy plan. All plans were done in Monaco planning system for Elekta Synergy linear accelerator with 80 multileaf collimator (MLC. Volumetric modulated arc therapy (VMAT plans were done with different increment of gantry angle like 15 o , 20 o , 30 o and 40 o . The remaining parameters were similar for all the plans. The results were compared. To compare the plan quality with number of arcs, VMAT plans were done with single and dual arc with increment of gantry angle of 20 o . The dose to gross tumor volume (GTV for 60 Gy and planning target volume (PTV for 48 Gy was compared. The dosimetric parameters D 98% , D 95% , D 50% and D max of GTV were analyzed. The homogeneity index (HI and conformity index (CI of GTV were studied and the dose to 98% and 95% of PTV was analyzed. Maximum dose to spinal cord and planning risk volume of cord (PRV cord was compared. The Volume of lung receiving 10 Gy, 20 Gy and mean dose was analyzed. The volume of heart receiving 30 Gy and 45 Gy was compared. The volume of normal tissue receiving greater than 2 Gy and 5 Gy was compared. The number of monitor units (MU required to deliver the plans were compared. The plan with larger increment of gantry angle proved to be superior to smaller increment of gantry angle plans in terms of dose coverage, HI, CI and normal tissue sparing. The number of arcs did not make any difference in the quality of the plan.

  7. World crude output overcomes Persian Gulf disruption

    International Nuclear Information System (INIS)

    Anon.

    1992-01-01

    Several OPEC producers made good on their promises to replace 2.7 MMbpd of oil exports that vanished from the world market after Iraq took over Kuwait. Even more incredibly, they accomplished this while a breathtaking 1.2- MMbopd reduction in Soviet output took place during the course of 1991. After Abu Dhabi, Indonesia, Iran, Libya, Nigeria, Saudi Arabia and Venezuela turned the taps wide open, their combined output rose 2.95 MMbopd. Put together with a 282,000-bopd increase by Norway and contributions from smaller producers, this enabled world oil production to remain within 400,000 bopd of its 1990 level. The 60.5-MMbopd average was off by just 0.7%. This paper reports that improvement took place in five of eight regions. Largest increases were in Western Europe and Africa. Greatest reductions occurred in Eastern Europe and the Middle East. Fifteen nations produced 1 MMbopd or more last year, compared with 17 during 1990

  8. Saturated output tabletop x-ray lasers

    International Nuclear Information System (INIS)

    Dunn, J.; Osterheld, A.L.; Nilsen, J.; Hunter, J.R.; Li, Y.; Faenov, A.Ya.; Pikuz, T.A.; Shlyaptsev, N.

    2000-01-01

    The high efficiency method of transient collisional excitation has been successfully demonstrated for Ne-like and Ni-like ion x-ray laser schemes with small 5-10 J laser facilities. Our recent studies using the tabletop COMET (Compact Multipulse Terawatt) laser system at the Lawrence Livermore National Laboratory (LLNL) have produced several x-ray lasers operating in the saturation regime. Output energy of 10-15 (micro)J corresponding to a gL product of 18 has been achieved on the Ni-like Pd 4d → 4p transition at 147 (angstrom) with a total energy of 5-7 J in a 600 ps pulse followed by a 1.2 ps pulse. Analysis of the laser beam angular profile indicates that refraction plays an important role in the amplification and propagation process in the plasma column. We report further improvement in the extraction efficiency by varying a number of laser driver parameters. In particular, the duration of the second short pulse producing the inversion has an observed effect on the x-ray laser output

  9. Guaranteeing high output of a mine

    Energy Technology Data Exchange (ETDEWEB)

    Shetser, M G

    1983-05-01

    Operation of the Im. Kalinina coal mine in the Central Donbass is evluated. Seventeen coal seams, on the average 0.87 m thick, are prone to methane and coal dust explosions and to rock bursts. Some of the seams are also prone to spontaneous combustion. Rock layers in the roofs are prone to rock falls. Mining depth ranges from 740 to 850 m. Another working level is being constructed at a depth of 960 m. The steep coal seams are mined by means of the ANShch shield systems and the KGU system (with the 'Poisk' cutter loader). Strata control methods used in the mine are evaluated. Design of timber cribbings used for strata control in inclined workings is shown in a scheme. Construction of coal chutes and strata control in coal chutes are also described. Operation of KGU-1 powered supports which have been used in the mine for 10 years is evaluated. Improved strata control permitted daily coal output from a working face to be increased from 135 t in 1979 to 169 t in 1982. Yearly coal output increased from 605,000 t to 760,000 t. Labor productivity increased from 21.1 t/month to 25.9 t/month per miner. (In Russian)

  10. Saturated output tabletop X-ray lasers

    Energy Technology Data Exchange (ETDEWEB)

    Dunn, J.; Osterheld, A.L.; Nilsen, J.; Hunter, J.R. [Lawrence Livermore National Lab., CA (United States); Yuelin Li [Lawrence Livermore National Lab., CA (United States); ILSA, Lawrence Livermore National Lab., Livermore, CA (United States); Faenov, A.Ya.; Pikuz, T.A. [Lawrence Livermore National Lab., CA (United States); MISDC of VNIIFTRI, Mendeleevo (Russian Federation); Shlyaptsev, V.N. [Lawrence Livermore National Lab., CA (United States); DAS, Univ. of California Davis-Livermore, Livermore, CA (United States)

    2001-07-01

    The high efficiency method of transient collisional excitation has been successfully demonstrated for Ne-like and Ni-like ion X-ray laser schemes with small 5-10 J laser facilities. Our recent studies using the tabletop COMET (compact multipulse terawatt) laser system at the Lawrence livermore national laboratory (LLNL) have produced several X-ray lasers operating in the saturation regime. Output energy of 10-15 {mu}J corresponding to a gL product of 18 has been achieved on the Ni-like Pd 4d{yields}4p transition at 147 A with a total energy of 5-7 J in a 600 ps pulse followed by a 1.2 ps pulse. Analysis of the laser beam angular profile indicates that refraction plays an important role in the amplification and propagation process in the plasma column. We report further improvement in the extraction efficiency by varying a number of laser driver parameters. In particular, the duration of the second short pulse producing the inversion has an observed effect on the X-ray laser output. (orig.)

  11. Determination of action thresholds for electromagnetic tracking system-guided hypofractionated prostate radiotherapy using volumetric modulated arc therapy

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Pengpeng; Mah, Dennis; Happersett, Laura; Cox, Brett; Hunt, Margie; Mageras, Gig [Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, New York, New York 10021 (United States); Department of Radiation Oncology, Montefiore Medical Center, Bronx, New York 10467 (United States); Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, New York, New York 10021 (United States); Department of Radiation Oncology, Memorial Sloan-Kettering Cancer Center, New York, New York 10021 (United States); Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, New York, New York 10021 (United States)

    2011-07-15

    Purpose: Hypofractionated prostate radiotherapy may benefit from both volumetric modulated arc therapy (VMAT) due to shortened treatment time and intrafraction real-time monitoring provided by implanted radiofrequency(RF) transponders. The authors investigate dosimetrically driven action thresholds (whether treatment needs to be interrupted and patient repositioned) in VMAT treatment with electromagnetic (EM) tracking. Methods: VMAT plans for five patients are generated for prescription doses of 32.5 and 42.5 Gy in five fractions. Planning target volume (PTV) encloses the clinical target volume (CTV) with a 3 mm margin at the prostate-rectal interface and 5 mm elsewhere. The VMAT delivery is modeled using 180 equi-spaced static beams. Intrafraction prostate motion is simulated in the plan by displacing the beam isocenter at each beam assuming rigid organ motion according to a previously recorded trajectory of the transponder centroid. The cumulative dose delivered in each fraction is summed over all beams. Two sets of 57 prostate motion trajectories were randomly selected to form a learning and a testing dataset. Dosimetric end points including CTV D95%, rectum wall D1cc, bladder wall D1cc, and urethra Dmax, are analyzed against motion characteristics including the maximum amplitude of the anterior-posterior (AP), superior-inferior (SI), and left-right components. Action thresholds are triggered when intrafraction motion causes any violations of dose constraints to target and organs at risk (OAR), so that treatment is interrupted and patient is repositioned. Results: Intrafraction motion has a little effect on CTV D95%, indicating PTV margins are adequate. Tight posterior and inferior action thresholds around 1 mm need to be set in a patient specific manner to spare organs at risk, especially when the prescription dose is 42.5 Gy. Advantages of setting patient specific action thresholds are to reduce false positive alarms by 25% when prescription dose is low, and

  12. Determination of action thresholds for electromagnetic tracking system-guided hypofractionated prostate radiotherapy using volumetric modulated arc therapy

    International Nuclear Information System (INIS)

    Zhang, Pengpeng; Mah, Dennis; Happersett, Laura; Cox, Brett; Hunt, Margie; Mageras, Gig

    2011-01-01

    Purpose: Hypofractionated prostate radiotherapy may benefit from both volumetric modulated arc therapy (VMAT) due to shortened treatment time and intrafraction real-time monitoring provided by implanted radiofrequency(RF) transponders. The authors investigate dosimetrically driven action thresholds (whether treatment needs to be interrupted and patient repositioned) in VMAT treatment with electromagnetic (EM) tracking. Methods: VMAT plans for five patients are generated for prescription doses of 32.5 and 42.5 Gy in five fractions. Planning target volume (PTV) encloses the clinical target volume (CTV) with a 3 mm margin at the prostate-rectal interface and 5 mm elsewhere. The VMAT delivery is modeled using 180 equi-spaced static beams. Intrafraction prostate motion is simulated in the plan by displacing the beam isocenter at each beam assuming rigid organ motion according to a previously recorded trajectory of the transponder centroid. The cumulative dose delivered in each fraction is summed over all beams. Two sets of 57 prostate motion trajectories were randomly selected to form a learning and a testing dataset. Dosimetric end points including CTV D95%, rectum wall D1cc, bladder wall D1cc, and urethra Dmax, are analyzed against motion characteristics including the maximum amplitude of the anterior-posterior (AP), superior-inferior (SI), and left-right components. Action thresholds are triggered when intrafraction motion causes any violations of dose constraints to target and organs at risk (OAR), so that treatment is interrupted and patient is repositioned. Results: Intrafraction motion has a little effect on CTV D95%, indicating PTV margins are adequate. Tight posterior and inferior action thresholds around 1 mm need to be set in a patient specific manner to spare organs at risk, especially when the prescription dose is 42.5 Gy. Advantages of setting patient specific action thresholds are to reduce false positive alarms by 25% when prescription dose is low, and

  13. A Monte Carlo Study on Multiple Output Stochastic Frontiers

    DEFF Research Database (Denmark)

    Henningsen, Géraldine; Henningsen, Arne; Jensen, Uwe

    , dividing all other output quantities by the selected output quantity, and using these ratios as regressors (OD). Another approach is the stochastic ray production frontier (SR) which transforms the output quantities into their Euclidean distance as the dependent variable and their polar coordinates......In the estimation of multiple output technologies in a primal approach, the main question is how to handle the multiple outputs. Often an output distance function is used, where the classical approach is to exploit its homogeneity property by selecting one output quantity as the dependent variable...... of both specifications for the case of a Translog output distance function with respect to different common statistical problems as well as problems arising as a consequence of zero values in the output quantities. Although, our results partly show clear reactions to statistical misspecifications...

  14. Translating Response During Therapy into Ultimate Treatment Outcome: A Personalized 4-Dimensional MRI Tumor Volumetric Regression Approach in Cervical Cancer

    International Nuclear Information System (INIS)

    Mayr, Nina A.; Wang, Jian Z.; Lo, Simon S.; Zhang Dongqing; Grecula, John C.; Lu Lanchun; Montebello, Joseph F.; Fowler, Jeffrey M.; Yuh, William T.C.

    2010-01-01

    Purpose: To assess individual volumetric tumor regression pattern in cervical cancer during therapy using serial four-dimensional MRI and to define the regression parameters' prognostic value validated with local control and survival correlation. Methods and Materials: One hundred and fifteen patients with Stage IB 2 -IVA cervical cancer treated with radiation therapy (RT) underwent serial MRI before (MRI 1) and during RT, at 2-2.5 weeks (MRI 2, at 20-25 Gy), and at 4-5 weeks (MRI 3, at 40-50 Gy). Eighty patients had a fourth MRI 1-2 months post-RT. Mean follow-up was 5.3 years. Tumor volume was measured by MRI-based three-dimensional volumetry, and plotted as dose(time)/volume regression curves. Volume regression parameters were correlated with local control, disease-specific, and overall survival. Results: Residual tumor volume, slope, and area under the regression curve correlated significantly with local control and survival. Residual volumes ≥20% at 40-50 Gy were independently associated with inferior 5-year local control (53% vs. 97%, p <0.001) and disease-specific survival rates (50% vs. 72%, p = 0.009) than smaller volumes. Patients with post-RT residual volumes ≥10% had 0% local control and 17% disease-specific survival, compared with 91% and 72% for <10% volume (p <0.001). Conclusion: Using more accurate four-dimensional volumetric regression analysis, tumor response can now be directly translated into individual patients' outcome for clinical application. Our results define two temporal thresholds critically influencing local control and survival. In patients with ≥20% residual volume at 40-50 Gy and ≥10% post-RT, the risk for local failure and death are so high that aggressive intervention may be warranted.

  15. Hair-sparing whole brain radiotherapy with volumetric arc therapy in patients treated for brain metastases: dosimetric and clinical results of a phase II trial

    International Nuclear Information System (INIS)

    De Puysseleyr, Annemieke; Ost, Piet; Van De Velde, Joris; Speleers, Bruno; Vercauteren, Tom; Goedgebeur, Anneleen; Van Hoof, Tom; Boterberg, Tom; De Neve, Wilfried; De Wagter, Carlos

    2014-01-01

    To report the dosimetric results and impact of volumetric arc therapy (VMAT) on temporary alopecia and hair-loss related quality of life (QOL) in whole brain radiotherapy (WBRT). The potential of VMAT-WBRT to reduce the dose to the hair follicles was assessed. A human cadaver was treated with both VMAT-WBRT and conventional opposed field (OF) WBRT, while the subcutaneously absorbed dose was measured by radiochromic films and calculated by the planning system. The impact of these dose reductions on temporary alopecia was examined in a prospective phase II trial, with the mean score of hair loss at 1 month after VMAT-WBRT (EORTC-QOL BN20) as a primary endpoint and delivering a dose of 20 Gy in 5 fractions. An interim analysis was planned after including 10 patients to rule out futility, defined as a mean score of hair loss exceeding 56.7. A secondary endpoint was the global alopecia areata severity score measured with the “Severity of Alopecia Tool” (SALT) with a scale of 0 (no hair loss) to 100 (complete alopecia). For VMAT-WBRT, the cadaver measurements demonstrated a dose reduction to the hair follicle volume of 20.5% on average and of 41.8% on the frontal-vertex-occipital medial axis as compared to OF-WBRT. In the phase II trial, a total of 10 patients were included before the trial was halted due to futility. The EORTC BN20 hair loss score following WBRT was 95 (SD 12.6). The average median dose to the hair follicle volume was 12.6 Gy (SD 0.9), corresponding to a 37% dose reduction compared to the prescribed dose. This resulted in a mean SALT-score of 75. Compared to OF-WBRT, VMAT-WBRT substantially reduces hair follicle dose. These dose reductions could not be related to an improved QOL or SALT score

  16. Dosimetric comparison of intensity-modulated radiotherapy (IMRT) and volumetric modulated arc therapy (VMAT) in total scalp irradiation: a single institutional experience

    International Nuclear Information System (INIS)

    Ostheimer, Christian; Huebsch, Patrick; Janich, Martin; Gerlach, Reinhard; Vordermark, Dirk

    2016-01-01

    Total scalp irradiation (TSI) is a rare but challenging indication. We previously reported that non-coplanar intensity-modulated radiotherapy (IMRT) was superior to coplanar IMRT in organ-at-risk (OAR) protection and target dose distribution. This consecutive treatment planning study compared IMRT with volumetric-modulated arc therapy (VMAT). A retrospective treatment plan databank search was performed and 5 patient cases were randomly selected. Cranial imaging was restored from the initial planning computed tomography (CT) and target volumes and OAR were redelineated. For each patients, three treatment plans were calculated (coplanar/non-coplanar IMRT, VMAT; prescribed dose 50 Gy, single dose 2 Gy). Conformity, homogeneity and dose volume histograms were used for plan. VMAT featured the lowest monitor units and the sharpest dose gradient (1.6 Gy/mm). Planning target volume (PTV) coverage and homogeneity was better in VMAT (coverage, 0.95; homogeneity index [HI], 0.118) compared to IMRT (coverage, 0.94; HI, 0.119) but coplanar IMRT produced the most conformal plans (conformity index [CI], 0.43). Minimum PTV dose range was 66.8% –88.4% in coplanar, 77.5%–88.2% in non-coplanar IMRT and 82.8%–90.3% in VMAT. Mean dose to the brain, brain stem, optic system (maximum dose) and lenses were 18.6, 13.2, 9.1, and 5.2 Gy for VMAT, 21.9, 13.4, 14.5, and 6.3 Gy for non-coplanar and 22.8, 16.5, 11.5, and 5.9 Gy for coplanar IMRT. Maximum optic chiasm dose was 7.7, 8.4, and 11.1 Gy (non-coplanar IMRT, VMAT, and coplanar IMRT). Target coverage, homogeneity and OAR protection, was slightly superior in VMAT plans which also produced the sharpest dose gradient towards healthy tissue

  17. Dosimetric comparison of intensity-modulated radiotherapy (IMRT) and volumetric modulated arc therapy (VMAT) in total scalp irradiation: a single institutional experience

    Energy Technology Data Exchange (ETDEWEB)

    Ostheimer, Christian; Huebsch, Patrick; Janich, Martin; Gerlach, Reinhard; Vordermark, Dirk [Dept. of Radiation Oncology, Faculty of Medicine, Martin Luther University Halle-Wittenberg, Halle (Germany)

    2016-12-15

    Total scalp irradiation (TSI) is a rare but challenging indication. We previously reported that non-coplanar intensity-modulated radiotherapy (IMRT) was superior to coplanar IMRT in organ-at-risk (OAR) protection and target dose distribution. This consecutive treatment planning study compared IMRT with volumetric-modulated arc therapy (VMAT). A retrospective treatment plan databank search was performed and 5 patient cases were randomly selected. Cranial imaging was restored from the initial planning computed tomography (CT) and target volumes and OAR were redelineated. For each patients, three treatment plans were calculated (coplanar/non-coplanar IMRT, VMAT; prescribed dose 50 Gy, single dose 2 Gy). Conformity, homogeneity and dose volume histograms were used for plan. VMAT featured the lowest monitor units and the sharpest dose gradient (1.6 Gy/mm). Planning target volume (PTV) coverage and homogeneity was better in VMAT (coverage, 0.95; homogeneity index [HI], 0.118) compared to IMRT (coverage, 0.94; HI, 0.119) but coplanar IMRT produced the most conformal plans (conformity index [CI], 0.43). Minimum PTV dose range was 66.8% –88.4% in coplanar, 77.5%–88.2% in non-coplanar IMRT and 82.8%–90.3% in VMAT. Mean dose to the brain, brain stem, optic system (maximum dose) and lenses were 18.6, 13.2, 9.1, and 5.2 Gy for VMAT, 21.9, 13.4, 14.5, and 6.3 Gy for non-coplanar and 22.8, 16.5, 11.5, and 5.9 Gy for coplanar IMRT. Maximum optic chiasm dose was 7.7, 8.4, and 11.1 Gy (non-coplanar IMRT, VMAT, and coplanar IMRT). Target coverage, homogeneity and OAR protection, was slightly superior in VMAT plans which also produced the sharpest dose gradient towards healthy tissue.

  18. Novel dosimetric phantom for quality assurance of volumetric modulated arc therapy

    International Nuclear Information System (INIS)

    Letourneau, Daniel; Publicover, Julia; Kozelka, Jakub; Moseley, Douglas J.; Jaffray, David A.

    2009-01-01

    The objective of this work is to assess the suitability and performance of a new dosimeter system with a novel geometry for the quality assurance (QA) of volumetric modulated arc therapy (VMAT). The new dosimeter system consists of a hollow cylinder (15 and 25 cm inner and outer diameters) with 124 diodes embedded in the phantom's cylindrical wall forming four rings of detectors. For coplanar beams, the cylindrical geometry and the ring diode pattern offer the advantage of invariant perpendicular incidence on the beam central axis for any gantry angle and also have the benefit of increasing the detector density as both walls of the cylinder sample the beam. Other advantages include real-time readout and reduced weight with the hollow phantom shape. A calibration method taking into account the variation in radiation sensitivity of the diodes as a function of gantry angle was developed and implemented. In this work, the new dosimeter system was used in integrating mode to perform composite dose measurements along the cylindrical surface supporting the diodes. The reproducibility of the dosimeter response and the angular dependence of the diodes were assessed using simple 6 MV photon static beams. The performance of the new dosimeter system for VMAT QA was then evaluated using VMAT plans designed for a head and neck, an abdominal sarcoma, and a prostate patient. These plans were optimized with 90 control points (CPs) and additional versions of each plan were generated by increasing the number of CPs to 180 and 360 using linear interpolation. The relative dose measured with the dosimeter system for the VMAT plans was compared to the corresponding TPS dose map in terms of relative dose difference (%ΔD) and distance to agreement (DTA). The dosimeter system's sensitivity to gantry rotation offset and scaling errors as well as setup errors was also evaluated. For static beams, the dosimeter system offered good reproducibility and demonstrated small residual diode angular

  19. Dosimetric effect of multileaf collimator leaf width on volumetric modulated arc stereotactic radiotherapy for spine tumors

    Energy Technology Data Exchange (ETDEWEB)

    Amoush, Ahmad, E-mail: aamoush@augusta.edu [Augusta University, 1120 15th St, Augusta, GA 30912 (United States); Cleveland Clinic, 9500 Euclid Ave., Cleveland, OH 44195 (United States); Long, Huang [University of Utah, 1950 Circle of Hope, Salt Lake City, UT 84112 (United States); Subedi, Laxmi [Cleveland State University, 2121 Euclid Ave., Cleveland, OH 44115 (United States); Qi, Peng; Djemil, Toufik; Xia, Ping [Cleveland Clinic, 9500 Euclid Ave., Cleveland, OH 44195 (United States)

    2017-07-01

    This work aimed to study the dosimetric effect of multileaf collimator (MLC) leaf widths in treatment plans for patients receiving volumetric modulated arc therapy (VMAT) for spine stereotactic body radiation therapy (SBRT). Thirteen patients treated with spine SBRT were retrospectively selected for this study. The patients were treated following the protocol of the Radiation Therapy Oncology Group 0631 (RTOG 0631) for spine metastasis. The prescription dose was 16 Gy in 1 fraction to 90% of the target volume (V16 > 90%). The maximum spinal cord dose of 14 Gy and 10% of the spinal cord receiving < 10 Gy (V10) were the acceptable tolerance doses. For the purpose of this study, 2 dual-arc VMAT plans were created for each patient using 3 different MLC leaf widths: 2.5 mm, 4 mm, and 5 mm. The compliance with the RTOG 0631 protocol, conformity index (CI), dose gradient index (DGI), and number of monitor units (MUs) were compared. The average V16Gy of the targets was 91.8 ± 1.2%, 92.2 ± 2.1%, and 91.7 ± 2.3% for 2.5-mm, 4-mm, and 5-mm leaf widths, respectively (p = 0.78). Accordingly, the average CI was 1.45 ± 0.4, 1.47 ± 0.29, and 1.47 ± 0.31 (p = 0.98), respectively. The average DGI was 0.22 ± 0.04, 0.20 ± 0.06, and 0.22 ± 0.05, respectively (p = 0.77). The average maximum dose to the spinal cord was 12.45 ± 1.0 Gy, 12.80 ± 1.0 Gy, and 12.48 ± 1.1 (p = 0.62) and V10% of the spinal cord was 3.6 ± 2.1%, 5.6 ± 2.8%, and 5.5 ± 3.0% (p = 0.11) for 2.5-mm, 4-mm, and 5-mm leaf widths, respectively. Accordingly, the average number of MUs was 4341 ± 500 MU, 5019 ± 834 MU, and 4606 ± 691 MU, respectively (p = 0.053). The use of 2.5-mm, 4-mm, and 5-mm MLCs achieved similar VMAT plan quality as recommended by the RTOG 0631. The dosimetric parameters were also comparable for the 3 MLCs. In general, any of these leaf widths can be used for spine

  20. Weekly Cisplatin and Volumetric-Modulated Arc Therapy With Simultaneous Integrated Boost for Radical Treatment of Advanced Cervical Cancer in Elderly Patients: Feasibility and Clinical Preliminary Results

    Science.gov (United States)

    Mazzola, Rosario; Ricchetti, Francesco; Fiorentino, Alba; Levra, Niccolò Giaj; Fersino, Sergio; Di Paola, Gioacchino; Ruggieri, Ruggero

    2016-01-01

    Background: To evaluate the feasibility and clinical preliminary results of weekly cisplatin and volumetric-modulated arc therapy to the pelvis with simultaneous integrated boost to macroscopic disease in a cohort of elderly patients. Materials and Methods: Inclusion criteria of this prospective study were age ≥70 years, Karnofsky performance status 70 to 100, locally advanced histologically proven squamous cervical carcinoma, and patients unable to undergo brachytherapy. Radiation doses prescribed were 66 Gy to the macroscopic disease and 54 Gy to the pelvic nodes in 30 fractions. Weekly cisplatin dose was 40 mg/mq. Results: A total of 30 patients were recruited. Median follow-up was 32 months (range: 8-48 months). Median age was 72 years (range: 70-84 years). The 3-year overall survival and local control were 93% and 80%, respectively. The median time to progression was 24 months (range: 6-30 months). Analyzing clinical outcome grouping based on the stage of disease, II versus III, the 3-year overall survival was 100% and 85%, respectively. The 3-year local control was 91% for stage II and 67% for stage III. Acute and late toxicities were acceptable without severe events. Conclusion: Weekly cisplatin and volumetric-modulated arc therapy–simultaneous integrated boost for radical treatment of advanced cervical cancer in the current cohort of elderly patients were feasible. Long-term results and prospective randomized trials are advocated. PMID:27402633

  1. Dosimetric comparison between helical tomotherapy and volumetric modulated arc-therapy for non-anaplastic thyroid cancer treatment.

    Science.gov (United States)

    Khalifa, Jonathan; Vieillevigne, Laure; Boyrie, Sabrina; Ouali, Monia; Filleron, Thomas; Rives, Michel; Laprie, Anne

    2014-11-26

    To evaluate and compare dosimetric parameters of volumetric modulated arctherapy (VMAT) and helical tomotherapy (HT) for non-anaplastic thyroid cancer adjuvant radiotherapy. Twelve patients with non-anaplastic thyroid cancer at high risk of local relapse received adjuvant external beam radiotherapy with curative intent in our institution, using a two-dose level prescription with a simultaneous integrated boost approach. Each patient was re-planned by the same physicist twice using both VMAT and HT. Several dosimetric quality indexes were used: target coverage index (proportion of the target volume covered by the reference isodose), healthy tissue conformity index (proportion of the reference isodose volume including the target volume), conformation number (combining both previous indexes), Dice Similarity Coefficient (DSC), and homogeneity index ((D2%-D98%)/prescribed dose). Dose-volume histogram statistics were also compared. HT provided statistically better target coverage index and homogeneity index for low risk PTV in comparison with VMAT (respectively 0.99 vs. 0.97 (p=0.008) and 0.22 vs. 0.25 (p=0.016)). However, HT provided poorer results for healthy tissue conformity index, conformation number and DSC with low risk and high risk PTV. As regards organs at risk sparing, by comparison with VMAT, HT statistically decreased the D2% to medullary canal (25.3 Gy vs. 32.6 Gy (p=0.003)). Besides, HT allowed a slight sparing dose for the controlateral parotid (Dmean: 4.3 Gy vs. 6.6 Gy (p=0.032)) and for the controlateral sub-maxillary gland (Dmean: 29.1 Gy vs. 33.1 Gy (p=0.041)). Both VMAT and HT techniques for adjuvant treatment of non-anaplastic thyroid cancer provide globally attractive treatment plans with slight dosimetric differences. However, helical tomotherapy clearly provides a benefit in term of medullary canal sparing.

  2. Four-dimensional CT-based evaluation of volumetric modulated arc therapy for abdominal lymph node metastasis from hepatocellular carcinoma

    International Nuclear Information System (INIS)

    Zhang Li; Xi Mian; Deng Xiaowu; Li Qiaoqiao; Huang Xiaoyan; Liu Mengzhong

    2012-01-01

    This study aimed to identify the potential benefits and limitations of a new volumetric modulated arc therapy (VMAT) planning system in Monaco, compared with conventional intensity-modulated radiotherapy (IMRT) and three-dimensional conformal radiotherapy (3DCRT). Four-dimensional CT scans of 13 patients with abdominal lymph node metastasis from hepatocellular carcinoma were selected. Internal target volume was defined as the combined volume of clinical target volumes (CTVs) in the multiple four-dimensional computed tomography (4DCT) phases. Dose prescription was set to 45 Gy for the planning target volume (PTV) in daily 3.0-Gy fractions. The PTV dose coverage, organs at risk (OAR) doses, delivery parameters and treatment accuracy were assessed. Compared with 3DCRT, both VMAT and IMRT provided a systematic improvement in PTV coverage and homogeneity. Planning objectives were not fulfilled for the right kidney, in which the 3DCRT plans exceeded the dose constraints in two patients. Equivalent target coverage and sparing of OARs were achieved with VMAT compared with IMRT. The number of MU/fraction was 462±68 (3DCRT), 564±105 (IMRT) and 601±134 (VMAT), respectively. Effective treatment times were as follows: 1.8±0.2 min (3DCRT), 6.1±1.5 min (IMRT) and 4.8±1.0 min (VMAT). This study suggests that the VMAT plans generated in Monaco improved delivery efficiency for equivalent dosimetric quality to IMRT, and were superior to 3DCRT in target coverage and sparing of most OARs. However, the superiority of VMAT over IMRT in delivery efficiency is limited. (author)

  3. Dose rate constants for new dose quantities

    International Nuclear Information System (INIS)

    Tschurlovits, M.; Daverda, G.; Leitner, A.

    1992-01-01

    Conceptual changes and new quantities made is necessary to reassess dose rate quantities. Calculations of the dose rate constant were done for air kerma, ambient dose equivalent and directional dose equivalent. The number of radionuclides is more than 200. The threshold energy is selected as 20 keV for the dose equivalent constants. The dose rate constant for the photon equivalent dose as used mainly in German speaking countries as a temporary quantity is also included. (Author)

  4. Volumetric Forest Change Detection Through Vhr Satellite Imagery

    Science.gov (United States)

    Akca, Devrim; Stylianidis, Efstratios; Smagas, Konstantinos; Hofer, Martin; Poli, Daniela; Gruen, Armin; Sanchez Martin, Victor; Altan, Orhan; Walli, Andreas; Jimeno, Elisa; Garcia, Alejandro

    2016-06-01

    Quick and economical ways of detecting of planimetric and volumetric changes of forest areas are in high demand. A research platform, called FORSAT (A satellite processing platform for high resolution forest assessment), was developed for the extraction of 3D geometric information from VHR (very-high resolution) imagery from satellite optical sensors and automatic change detection. This 3D forest information solution was developed during a Eurostars project. FORSAT includes two main units. The first one is dedicated to the geometric and radiometric processing of satellite optical imagery and 2D/3D information extraction. This includes: image radiometric pre-processing, image and ground point measurement, improvement of geometric sensor orientation, quasiepipolar image generation for stereo measurements, digital surface model (DSM) extraction by using a precise and robust image matching approach specially designed for VHR satellite imagery, generation of orthoimages, and 3D measurements in single images using mono-plotting and in stereo images as well as triplets. FORSAT supports most of the VHR optically imagery commonly used for civil applications: IKONOS, OrbView - 3, SPOT - 5 HRS, SPOT - 5 HRG, QuickBird, GeoEye-1, WorldView-1/2, Pléiades 1A/1B, SPOT 6/7, and sensors of similar type to be expected in the future. The second unit of FORSAT is dedicated to 3D surface comparison for change detection. It allows users to import digital elevation models (DEMs), align them using an advanced 3D surface matching approach and calculate the 3D differences and volume changes between epochs. To this end our 3D surface matching method LS3D is being used. FORSAT is a single source and flexible forest information solution with a very competitive price/quality ratio, allowing expert and non-expert remote sensing users to monitor forests in three and four dimensions from VHR optical imagery for many forest information needs. The capacity and benefits of FORSAT have been tested in

  5. A Technique for Generating Volumetric Cine-Magnetic Resonance Imaging

    International Nuclear Information System (INIS)

    Harris, Wendy; Ren, Lei; Cai, Jing; Zhang, You; Chang, Zheng; Yin, Fang-Fang

    2016-01-01

    Purpose: The purpose of this study was to develop a techique to generate on-board volumetric cine-magnetic resonance imaging (VC-MRI) using patient prior images, motion modeling, and on-board 2-dimensional cine MRI. Methods and Materials: One phase of a 4-dimensional MRI acquired during patient simulation is used as patient prior images. Three major respiratory deformation patterns of the patient are extracted from 4-dimensional MRI based on principal-component analysis. The on-board VC-MRI at any instant is considered as a deformation of the prior MRI. The deformation field is represented as a linear combination of the 3 major deformation patterns. The coefficients of the deformation patterns are solved by the data fidelity constraint using the acquired on-board single 2-dimensional cine MRI. The method was evaluated using both digital extended-cardiac torso (XCAT) simulation of lung cancer patients and MRI data from 4 real liver cancer patients. The accuracy of the estimated VC-MRI was quantitatively evaluated using volume-percent-difference (VPD), center-of-mass-shift (COMS), and target tracking errors. Effects of acquisition orientation, region-of-interest (ROI) selection, patient breathing pattern change, and noise on the estimation accuracy were also evaluated. Results: Image subtraction of ground-truth with estimated on-board VC-MRI shows fewer differences than image subtraction of ground-truth with prior image. Agreement between normalized profiles in the estimated and ground-truth VC-MRI was achieved with less than 6% error for both XCAT and patient data. Among all XCAT scenarios, the VPD between ground-truth and estimated lesion volumes was, on average, 8.43 ± 1.52% and the COMS was, on average, 0.93 ± 0.58 mm across all time steps for estimation based on the ROI region in the sagittal cine images. Matching to ROI in the sagittal view achieved better accuracy when there was substantial breathing pattern change. The technique was robust against

  6. A Technique for Generating Volumetric Cine MRI (VC-MRI)

    Science.gov (United States)

    Harris, Wendy; Ren, Lei; Cai, Jing; Zhang, You; Chang, Zheng; Yin, Fang-Fang

    2016-01-01

    Purpose To develop a technique to generate on-board volumetric-cine MRI (VC-MRI) using patient prior images, motion modeling and on-board 2D-cine MRI. Methods One phase of a 4D-MRI acquired during patient simulation is used as patient prior images. 3 major respiratory deformation patterns of the patient are extracted from 4D-MRI based on principal-component-analysis. The on-board VC-MRI at any instant is considered as a deformation of the prior MRI. The deformation field is represented as a linear combination of the 3 major deformation patterns. The coefficients of the deformation patterns are solved by the data fidelity constraint using the acquired on-board single 2D-cine MRI. The method was evaluated using both XCAT simulation of lung cancer patients and MRI data from four real liver cancer patients. The accuracy of the estimated VC-MRI was quantitatively evaluated using Volume-Percent-Difference(VPD), Center-of-Mass-Shift(COMS), and target tracking errors. Effects of acquisition orientation, region-of-interest(ROI) selection, patient breathing pattern change and noise on the estimation accuracy were also evaluated. Results Image subtraction of ground-truth with estimated on-board VC-MRI shows fewer differences than image subtraction of ground-truth with prior image. Agreement between profiles in the estimated and ground-truth VC-MRI was achieved with less than 6% error for both XCAT and patient data. Among all XCAT scenarios, the VPD between ground-truth and estimated lesion volumes was on average 8.43±1.52% and the COMS was on average 0.93±0.58mm across all time-steps for estimation based on the ROI region in the sagittal cine images. Matching to ROI in the sagittal view achieved better accuracy when there was substantial breathing pattern change. The technique was robust against noise levels up to SNR=20. For patient data, average tracking errors were less than 2 mm in all directions for all patients. Conclusions Preliminary studies demonstrated the

  7. 3D Volumetric Analysis of Fluid Inclusions Using Confocal Microscopy

    Science.gov (United States)

    Proussevitch, A.; Mulukutla, G.; Sahagian, D.; Bodnar, B.

    2009-05-01

    Fluid inclusions preserve valuable information regarding hydrothermal, metamorphic, and magmatic processes. The molar quantities of liquid and gaseous components in the inclusions can be estimated from their volumetric measurements at room temperatures combined with knowledge of the PVTX properties of the fluid and homogenization temperatures. Thus, accurate measurements of inclusion volumes and their two phase components are critical. One of the greatest advantages of the Laser Scanning Confocal Microscopy (LSCM) in application to fluid inclsion analsyis is that it is affordable for large numbers of samples, given the appropriate software analysis tools and methodology. Our present work is directed toward developing those tools and methods. For the last decade LSCM has been considered as a potential method for inclusion volume measurements. Nevertheless, the adequate and accurate measurement by LSCM has not yet been successful for fluid inclusions containing non-fluorescing fluids due to many technical challenges in image analysis despite the fact that the cost of collecting raw LSCM imagery has dramatically decreased in recent years. These problems mostly relate to image analysis methodology and software tools that are needed for pre-processing and image segmentation, which enable solid, liquid and gaseous components to be delineated. Other challenges involve image quality and contrast, which is controlled by fluorescence of the material (most aqueous fluid inclusions do not fluoresce at the appropriate laser wavelengths), material optical properties, and application of transmitted and/or reflected confocal illumination. In this work we have identified the key problems of image analysis and propose some potential solutions. For instance, we found that better contrast of pseudo-confocal transmitted light images could be overlayed with poor-contrast true-confocal reflected light images within the same stack of z-ordered slices. This approach allows one to narrow

  8. Incremental Volumetric Remapping Method: Analysis and Error Evaluation

    International Nuclear Information System (INIS)

    Baptista, A. J.; Oliveira, M. C.; Rodrigues, D. M.; Menezes, L. F.; Alves, J. L.

    2007-01-01

    In this paper the error associated with the remapping problem is analyzed. A range of numerical results that assess the performance of three different remapping strategies, applied to FE meshes that typically are used in sheet metal forming simulation, are evaluated. One of the selected strategies is the previously presented Incremental Volumetric Remapping method (IVR), which was implemented in the in-house code DD3TRIM. The IVR method fundaments consists on the premise that state variables in all points associated to a Gauss volume of a given element are equal to the state variable quantities placed in the correspondent Gauss point. Hence, given a typical remapping procedure between a donor and a target mesh, the variables to be associated to a target Gauss volume (and point) are determined by a weighted average. The weight function is the Gauss volume percentage of each donor element that is located inside the target Gauss volume. The calculus of the intersecting volumes between the donor and target Gauss volumes is attained incrementally, for each target Gauss volume, by means of a discrete approach. The other two remapping strategies selected are based in the interpolation/extrapolation of variables by using the finite element shape functions or moving least square interpolants. The performance of the three different remapping strategies is address with two tests. The first remapping test was taken from a literature work. The test consists in remapping successively a rotating symmetrical mesh, throughout N increments, in an angular span of 90 deg. The second remapping error evaluation test consists of remapping an irregular element shape target mesh from a given regular element shape donor mesh and proceed with the inverse operation. In this second test the computation effort is also measured. The results showed that the error level associated to IVR can be very low and with a stable evolution along the number of remapping procedures when compared with the

  9. A Technique for Generating Volumetric Cine-Magnetic Resonance Imaging

    Energy Technology Data Exchange (ETDEWEB)

    Harris, Wendy [Medical Physics Graduate Program, Duke University, Durham, North Carolina (United States); Ren, Lei, E-mail: lei.ren@duke.edu [Medical Physics Graduate Program, Duke University, Durham, North Carolina (United States); Department of Radiation Oncology, Duke University Medical Center, Durham, North Carolina (United States); Cai, Jing [Medical Physics Graduate Program, Duke University, Durham, North Carolina (United States); Department of Radiation Oncology, Duke University Medical Center, Durham, North Carolina (United States); Zhang, You [Medical Physics Graduate Program, Duke University, Durham, North Carolina (United States); Chang, Zheng; Yin, Fang-Fang [Medical Physics Graduate Program, Duke University, Durham, North Carolina (United States); Department of Radiation Oncology, Duke University Medical Center, Durham, North Carolina (United States)

    2016-06-01

    Purpose: The purpose of this study was to develop a techique to generate on-board volumetric cine-magnetic resonance imaging (VC-MRI) using patient prior images, motion modeling, and on-board 2-dimensional cine MRI. Methods and Materials: One phase of a 4-dimensional MRI acquired during patient simulation is used as patient prior images. Three major respiratory deformation patterns of the patient are extracted from 4-dimensional MRI based on principal-component analysis. The on-board VC-MRI at any instant is considered as a deformation of the prior MRI. The deformation field is represented as a linear combination of the 3 major deformation patterns. The coefficients of the deformation patterns are solved by the data fidelity constraint using the acquired on-board single 2-dimensional cine MRI. The method was evaluated using both digital extended-cardiac torso (XCAT) simulation of lung cancer patients and MRI data from 4 real liver cancer patients. The accuracy of the estimated VC-MRI was quantitatively evaluated using volume-percent-difference (VPD), center-of-mass-shift (COMS), and target tracking errors. Effects of acquisition orientation, region-of-interest (ROI) selection, patient breathing pattern change, and noise on the estimation accuracy were also evaluated. Results: Image subtraction of ground-truth with estimated on-board VC-MRI shows fewer differences than image subtraction of ground-truth with prior image. Agreement between normalized profiles in the estimated and ground-truth VC-MRI was achieved with less than 6% error for both XCAT and patient data. Among all XCAT scenarios, the VPD between ground-truth and estimated lesion volumes was, on average, 8.43 ± 1.52% and the COMS was, on average, 0.93 ± 0.58 mm across all time steps for estimation based on the ROI region in the sagittal cine images. Matching to ROI in the sagittal view achieved better accuracy when there was substantial breathing pattern change. The technique was robust against

  10. Transient refractory material dissolution by a volumetrically-heated melt

    Energy Technology Data Exchange (ETDEWEB)

    Seiler, Jean Marie, E-mail: jean-marie.seiler@cea.fr [CEA, DEN, DTN, 17 Rue des Martyrs, 38054 Grenoble Cedex 9 (France); Ratel, Gilles [CEA, DEN, DTN, 17 Rue des Martyrs, 38054 Grenoble Cedex 9 (France); Combeau, Hervé [Institut Jean Lamour, UMR 7198, Lorraine University, Ecole des Mines de Nancy, Parc de Saurupt, 54042 Nancy Cedex (France); Gaus-Liu, Xiaoyang; Kretzschmar, Frank; Miassoedov, Alexei [Karlsruhe Institut of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany)

    2014-12-15

    Highlights: • We describe a test investigating ceramic dissolution by a molten non-eutectic melt. • The evolution of the interface temperature between melt and refractory is measured. • A theoretical model describing dissolution kinetics is proposed. • When dissolution stops, interface temperature is the liquidus temperature of the melt. - Abstract: The present work addresses the question of corium–ceramic interaction in a core catcher during a core-melt accident in a nuclear power plant. It provides an original insight into transient aspects concerning dissolution of refractory material by a volumetrically heated pool. An experiment with simulant material (LIVECERAM) is presented. Test results clearly show that dissolution of solid refractory material can occur in a non-eutectic melt at a temperature which is lower than the melting temperature of the refractory material. During the dissolution transient, the interface temperature rises above the liquidus temperature, corresponding to the instantaneous average composition of the melt pool. With constant power dissipation in the melt and external cooling of the core-catcher, a final steady-state situation is reached. Dissolution stops when the heat flux (delivered by the melt to the refractory) can be removed by conduction through the residual thickness of the ceramic, with T{sub interface} = T{sub liquidus} (calculated for the average composition of the final liquid pool). The final steady state corresponds to a uniform pool composition and uniform interface temperature distribution. Convection in the pool is governed by natural thermal convection and the heat flux distribution is therefore similar to what would be obtained for a single component pool. An interpretation of the experiment with two model-based approaches (0D and 1D) is presented. The mass transfer kinetics between the interface and the bulk is controlled by a diffusion sublayer within the boundary layer. During the dissolution transient

  11. The novel application of Benford's second order analysis for monitoring radiation output in interventional radiology.

    Science.gov (United States)

    Cournane, S; Sheehy, N; Cooke, J

    2014-06-01

    Benford's law is an empirical observation which predicts the expected frequency of digits in naturally occurring datasets spanning multiple orders of magnitude, with the law having been most successfully applied as an audit tool in accountancy. This study investigated the sensitivity of the technique in identifying system output changes using simulated changes in interventional radiology Dose-Area-Product (DAP) data, with any deviations from Benford's distribution identified using z-statistics. The radiation output for interventional radiology X-ray equipment is monitored annually during quality control testing; however, for a considerable portion of the year an increased output of the system, potentially caused by engineering adjustments or spontaneous system faults may go unnoticed, leading to a potential increase in the radiation dose to patients. In normal operation recorded examination radiation outputs vary over multiple orders of magnitude rendering the application of normal statistics ineffective for detecting systematic changes in the output. In this work, the annual DAP datasets complied with Benford's first order law for first, second and combinations of the first and second digits. Further, a continuous 'rolling' second order technique was devised for trending simulated changes over shorter timescales. This distribution analysis, the first employment of the method for radiation output trending, detected significant changes simulated on the original data, proving the technique useful in this case. The potential is demonstrated for implementation of this novel analysis for monitoring and identifying change in suitable datasets for the purpose of system process control. Copyright © 2013 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

  12. Dense Output for Strong Stability Preserving Runge–Kutta Methods

    KAUST Repository

    Ketcheson, David I.

    2016-12-10

    We investigate dense output formulae (also known as continuous extensions) for strong stability preserving (SSP) Runge–Kutta methods. We require that the dense output formula also possess the SSP property, ideally under the same step-size restriction as the method itself. A general recipe for first-order SSP dense output formulae for SSP methods is given, and second-order dense output formulae for several optimal SSP methods are developed. It is shown that SSP dense output formulae of order three and higher do not exist, and that in any method possessing a second-order SSP dense output, the coefficient matrix A has a zero row.

  13. Doses to Carotid Arteries After Modern Radiation Therapy for Hodgkin Lymphoma

    DEFF Research Database (Denmark)

    Maraldo, M.V.; Brodin, Nils Patrik; Aznar, Marianne Camille

    2013-01-01

    Hodgkin lymphoma (HL) survivors are at an increased risk of stroke because of carotid artery irradiation. However, for early-stage HL involved node radiation therapy (INRT) reduces the volume of normal tissue exposed to high doses. Here, we evaluate 3-dimensional conformal radiation therapy (3D......-CRT), volumetric-modulated arc therapy (VMAT), and proton therapy (PT) delivered as INRT along with the extensive mantle field (MF) by comparing doses to the carotid arteries and corresponding risk estimates....

  14. SimDoseCT: dose reporting software based on Monte Carlo simulation for a 320 detector-row cone-beam CT scanner and ICRP computational adult phantoms

    Science.gov (United States)

    Cros, Maria; Joemai, Raoul M. S.; Geleijns, Jacob; Molina, Diego; Salvadó, Marçal

    2017-08-01

    This study aims to develop and test software for assessing and reporting doses for standard patients undergoing computed tomography (CT) examinations in a 320 detector-row cone-beam scanner. The software, called SimDoseCT, is based on the Monte Carlo (MC) simulation code, which was developed to calculate organ doses and effective doses in ICRP anthropomorphic adult reference computational phantoms for acquisitions with the Aquilion ONE CT scanner (Toshiba). MC simulation was validated by comparing CTDI measurements within standard CT dose phantoms with results from simulation under the same conditions. SimDoseCT consists of a graphical user interface connected to a MySQL database, which contains the look-up-tables that were generated with MC simulations for volumetric acquisitions at different scan positions along the phantom using any tube voltage, bow tie filter, focal spot and nine different beam widths. Two different methods were developed to estimate organ doses and effective doses from acquisitions using other available beam widths in the scanner. A correction factor was used to estimate doses in helical acquisitions. Hence, the user can select any available protocol in the Aquilion ONE scanner for a standard adult male or female and obtain the dose results through the software interface. Agreement within 9% between CTDI measurements and simulations allowed the validation of the MC program. Additionally, the algorithm for dose reporting in SimDoseCT was validated by comparing dose results from this tool with those obtained from MC simulations for three volumetric acquisitions (head, thorax and abdomen). The comparison was repeated using eight different collimations and also for another collimation in a helical abdomen examination. The results showed differences of 0.1 mSv or less for absolute dose in most organs and also in the effective dose calculation. The software provides a suitable tool for dose assessment in standard adult patients undergoing CT

  15. Turbulent Output-Based Anisotropic Adaptation

    Science.gov (United States)

    Park, Michael A.; Carlson, Jan-Renee

    2010-01-01

    Controlling discretization error is a remaining challenge for computational fluid dynamics simulation. Grid adaptation is applied to reduce estimated discretization error in drag or pressure integral output functions. To enable application to high O(10(exp 7)) Reynolds number turbulent flows, a hybrid approach is utilized that freezes the near-wall boundary layer grids and adapts the grid away from the no slip boundaries. The hybrid approach is not applicable to problems with under resolved initial boundary layer grids, but is a powerful technique for problems with important off-body anisotropic features. Supersonic nozzle plume, turbulent flat plate, and shock-boundary layer interaction examples are presented with comparisons to experimental measurements of pressure and velocity. Adapted grids are produced that resolve off-body features in locations that are not known a priori.

  16. FEL system with homogeneous average output

    Energy Technology Data Exchange (ETDEWEB)

    Douglas, David R.; Legg, Robert; Whitney, R. Roy; Neil, George; Powers, Thomas Joseph

    2018-01-16

    A method of varying the output of a free electron laser (FEL) on very short time scales to produce a slightly broader, but smooth, time-averaged wavelength spectrum. The method includes injecting into an accelerator a sequence of bunch trains at phase offsets from crest. Accelerating the particles to full energy to result in distinct and independently controlled, by the choice of phase offset, phase-energy correlations or chirps on each bunch train. The earlier trains will be more strongly chirped, the later trains less chirped. For an energy recovered linac (ERL), the beam may be recirculated using a transport system with linear and nonlinear momentum compactions M.sub.56, which are selected to compress all three bunch trains at the FEL with higher order terms managed.

  17. Proportional chamber with data analog output

    International Nuclear Information System (INIS)

    Popov, V.E.; Prokof'ev, A.N.

    1977-01-01

    A proportional multiwier chamber is described. The chamber makes it possible to determine angles at wich a pion strikes a polarized target. A delay line, made of 60-core flat cable is used for removing signals from the chamber. From the delay line, signals are amplified and successively injected into shapers and a time-to-amplitude converter. An amplitude of the time-to amplitude converter output signal unambiguously determines the coordinate of a point at which a particle strikes the chamber plane. There are also given circuits of amplifiers, which consist of a preamplifier with gain 30 and a main amplifier with adjustable gain. Data on testing the chamber with the 450 MeV pion beam is demonstrated. The chamber features an efficiency of about 98 per cent under load of 2x10 5 s -1

  18. Optimizing microwave photodetection: input-output theory

    Science.gov (United States)

    Schöndorf, M.; Govia, L. C. G.; Vavilov, M. G.; McDermott, R.; Wilhelm, F. K.

    2018-04-01

    High fidelity microwave photon counting is an important tool for various areas from background radiation analysis in astronomy to the implementation of circuit quantum electrodynamic architectures for the realization of a scalable quantum information processor. In this work we describe a microwave photon counter coupled to a semi-infinite transmission line. We employ input-output theory to examine a continuously driven transmission line as well as traveling photon wave packets. Using analytic and numerical methods, we calculate the conditions on the system parameters necessary to optimize measurement and achieve high detection efficiency. With this we can derive a general matching condition depending on the different system rates, under which the measurement process is optimal.

  19. Improvement of Output Power of ECF Micromotor

    Science.gov (United States)

    Yokota, Shinichi; Kawamura, Kiyomi; Takemura, Kenjiro; Edamura, Kazuya

    Electro-conjugate fluid (ECF) is a kind of dielectric fluids, which produces jet-flow (ECF jet) when subjected to a high DC voltage. By using the ECF jet, a new type of micromotor with simple structure and lightweight can be realized. Up to now, we developed a disk-plate type ECF micromotor with inner diameter of 9 mm. In this study, we develope novel ECF micromotors with inner diameter of 5 mm in order to improve the output power density. First, we designed and produced the ECF micromotors with 4-layered and 8-layered disk plate rotors. Then, the performances of the motors are measured. The experimental results confirm the motor developed has a higher performance than the previous ones.

  20. Application of computer voice input/output

    International Nuclear Information System (INIS)

    Ford, W.; Shirk, D.G.

    1981-01-01

    The advent of microprocessors and other large-scale integration (LSI) circuits is making voice input and output for computers and instruments practical; specialized LSI chips for speech processing are appearing on the market. Voice can be used to input data or to issue instrument commands; this allows the operator to engage in other tasks, move about, and to use standard data entry systems. Voice synthesizers can generate audible, easily understood instructions. Using voice characteristics, a control system can verify speaker identity for security purposes. Two simple voice-controlled systems have been designed at Los Alamos for nuclear safeguards applicaations. Each can easily be expanded as time allows. The first system is for instrument control that accepts voice commands and issues audible operator prompts. The second system is for access control. The speaker's voice is used to verify his identity and to actuate external devices

  1. Advanced Output Coupling for High Power Gyrotrons

    Energy Technology Data Exchange (ETDEWEB)

    Read, Michael [Calabazas Creek Research, Inc., San Mateo, CA (United States); Ives, Robert Lawrence [Calabazas Creek Research, Inc., San Mateo, CA (United States); Marsden, David [Calabazas Creek Research, Inc., San Mateo, CA (United States); Collins, George [Calabazas Creek Research, Inc., San Mateo, CA (United States); Temkin, Richard [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Guss, William [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Lohr, John [General Atomics, La Jolla, CA (United States); Neilson, Jeffrey [Lexam Research, Redwood City, CA (United States); Bui, Thuc [Calabazas Creek Research, Inc., San Mateo, CA (United States)

    2016-11-28

    The Phase II program developed an internal RF coupler that transforms the whispering gallery RF mode produced in gyrotron cavities to an HE11 waveguide mode propagating in corrugated waveguide. This power is extracted from the vacuum using a broadband, chemical vapor deposited (CVD) diamond, Brewster angle window capable of transmitting more than 1.5 MW CW of RF power over a broad range of frequencies. This coupling system eliminates the Mirror Optical Units now required to externally couple Gaussian output power into corrugated waveguide, significantly reducing system cost and increasing efficiency. The program simulated the performance using a broad range of advanced computer codes to optimize the design. Both a direct coupler and Brewster angle window were built and tested at low and high power. Test results confirmed the performance of both devices and demonstrated they are capable of achieving the required performance for scientific, defense, industrial, and medical applications.

  2. Dose-response analysis using R

    DEFF Research Database (Denmark)

    Ritz, Christian; Baty, Florent; Streibig, Jens Carl

    2015-01-01

    Dose-response analysis can be carried out using multi-purpose commercial statistical software, but except for a few special cases the analysis easily becomes cumbersome as relevant, non-standard output requires manual programming. The extension package drc for the statistical environment R provides...

  3. Semi-automated volumetric analysis of artificial lymph nodes in a phantom study

    International Nuclear Information System (INIS)

    Fabel, M.; Biederer, J.; Jochens, A.; Bornemann, L.; Soza, G.; Heller, M.; Bolte, H.

    2011-01-01

    Purpose: Quantification of tumour burden in oncology requires accurate and reproducible image evaluation. The current standard is one-dimensional measurement (e.g. RECIST) with inherent disadvantages. Volumetric analysis is discussed as an alternative for therapy monitoring of lung and liver metastases. The aim of this study was to investigate the accuracy of semi-automated volumetric analysis of artificial lymph node metastases in a phantom study. Materials and methods: Fifty artificial lymph nodes were produced in a size range from 10 to 55 mm; some of them enhanced using iodine contrast media. All nodules were placed in an artificial chest phantom (artiCHEST ® ) within different surrounding tissues. MDCT was performed using different collimations (1–5 mm) at varying reconstruction kernels (B20f, B40f, B60f). Volume and RECIST measurements were performed using Oncology Software (Siemens Healthcare, Forchheim, Germany) and were compared to reference volume and diameter by calculating absolute percentage errors. Results: The software performance allowed a robust volumetric analysis in a phantom setting. Unsatisfying segmentation results were frequently found for native nodules within surrounding muscle. The absolute percentage error (APE) for volumetric analysis varied between 0.01 and 225%. No significant differences were seen between different reconstruction kernels. The most unsatisfactory segmentation results occurred in higher slice thickness (4 and 5 mm). Contrast enhanced lymph nodes showed better segmentation results by trend. Conclusion: The semi-automated 3D-volumetric analysis software tool allows a reliable and convenient segmentation of artificial lymph nodes in a phantom setting. Lymph nodes adjacent to tissue of similar density cause segmentation problems. For volumetric analysis of lymph node metastases in clinical routine a slice thickness of ≤3 mm and a medium soft reconstruction kernel (e.g. B40f for Siemens scan systems) may be a suitable

  4. Industrial output restriction and the Kyoto protocol. An input-output approach with application to Canada

    International Nuclear Information System (INIS)

    Lixon, Benoit; Thomassin, Paul J.; Hamaide, Bertrand

    2008-01-01

    The objective of this paper is to assess the economic impacts of reducing greenhouse gas emissions by decreasing industrial output in Canada to a level that will meet the target set out in the Kyoto Protocol. The study uses an ecological-economic Input-Output model combining economic components valued in monetary terms with ecologic components - GHG emissions - expressed in physical terms. Economic and greenhouse gas emissions data for Canada are computed in the same sectoral disaggregation. Three policy scenarios are considered: the first one uses the direct emission coefficients to allocate the reduction in industrial output, while the other two use the direct plus indirect emission coefficients. In the first two scenarios, the reduction in industrial sector output is allocated uniformly across sectors while it is allocated to the 12 largest emitting industries in the last one. The estimated impacts indicate that the results vary with the different allocation methods. The third policy scenario, allocation to the 12 largest emitting sectors, is the most cost effective of the three as the impacts of the Kyoto Protocol reduces Gross Domestic Product by 3.1% compared to 24% and 8.1% in the first two scenarios. Computed economic costs should be considered as upper-bounds because the model assumes immediate adjustment to the Kyoto Protocol and because flexibility mechanisms are not incorporated. The resulting upper-bound impact of the third scenario may seem to contradict those who claim that the Kyoto Protocol would place an unbearable burden on the Canadian economy. (author)

  5. Dense Output for Strong Stability Preserving Runge–Kutta Methods

    KAUST Repository

    Ketcheson, David I.; Loczi, Lajos; Jangabylova, Aliya; Kusmanov, Adil

    2016-01-01

    We investigate dense output formulae (also known as continuous extensions) for strong stability preserving (SSP) Runge–Kutta methods. We require that the dense output formula also possess the SSP property, ideally under the same step

  6. Whole Brain Radiotherapy With Hippocampal Avoidance and Simultaneous Integrated Boost for 1-3 Brain Metastases: A Feasibility Study Using Volumetric Modulated Arc Therapy

    International Nuclear Information System (INIS)

    Hsu, Fred; Carolan, Hannah; Nichol, Alan; Cao, Fred; Nuraney, Nimet; Lee, Richard; Gete, Ermias; Wong, Frances; Schmuland, Moira; Heran, Manraj; Otto, Karl

    2010-01-01

    Purpose: To evaluate the feasibility of using volumetric modulated arc therapy (VMAT) to deliver whole brain radiotherapy (WBRT) with hippocampal avoidance and a simultaneous integrated boost (SIB) for one to three brain metastases. Methods and Materials: Ten patients previously treated with stereotactic radiosurgery for one to three brain metastases underwent repeat planning using VMAT. The whole brain prescription dose was 32.25 Gy in 15 fractions, and SIB doses to brain metastases were 63 Gy to lesions ≥2.0 cm and 70.8 Gy to lesions 2 . Plans were optimized for conformity and target coverage while minimizing hippocampal and ocular doses. Plans were evaluated on target coverage, prescription isodose to target volume ratio, conformity number, homogeneity index, and maximum dose to prescription dose ratio. Results: Ten patients had 18 metastases. Mean values for the brain metastases were as follows: conformity number = 0.73 ± 0.10, target coverage = 0.98 ± 0.01, prescription isodose to target volume = 1.34 ± 0.19, maximum dose to prescription dose ratio = 1.09 ± 0.02, and homogeneity index = 0.07 ± 0.02. For the whole brain, the mean target coverage and homogeneity index were 0.960 ± 0.002 and 0.39 ± 0.06, respectively. The mean hippocampal dose was 5.23 ± 0.39 Gy 2 . The mean treatment delivery time was 3.6 min (range, 3.3-4.1 min). Conclusions: VMAT was able to achieve adequate whole brain coverage with conformal hippocampal avoidance and radiosurgical quality dose distributions for one to three brain metastases. The mean delivery time was under 4 min.

  7. MCNP output data analysis with ROOT (MODAR)

    Science.gov (United States)

    Carasco, C.

    2010-12-01

    MCNP Output Data Analysis with ROOT (MODAR) is a tool based on CERN's ROOT software. MODAR has been designed to handle time-energy data issued by MCNP simulations of neutron inspection devices using the associated particle technique. MODAR exploits ROOT's Graphical User Interface and functionalities to visualize and process MCNP simulation results in a fast and user-friendly way. MODAR allows to take into account the detection system time resolution (which is not possible with MCNP) as well as detectors energy response function and counting statistics in a straightforward way. New version program summaryProgram title: MODAR Catalogue identifier: AEGA_v1_1 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEGA_v1_1.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 150 927 No. of bytes in distributed program, including test data, etc.: 4 981 633 Distribution format: tar.gz Programming language: C++ Computer: Most Unix workstations and PCs Operating system: Most Unix systems, Linux and windows, provided the ROOT package has been installed. Examples where tested under Suse Linux and Windows XP. RAM: Depends on the size of the MCNP output file. The example presented in the article, which involves three two dimensional 139×740 bins histograms, allocates about 60 MB. These data are running under ROOT and include consumption by ROOT itself. Classification: 17.6 Catalogue identifier of previous version: AEGA_v1_0 Journal reference of previous version: Comput. Phys. Comm. 181 (2010) 1161 External routines: ROOT version 5.24.00 ( http://root.cern.ch/drupal/) Does the new version supersede the previous version?: Yes Nature of problem: The output of a MCNP simulation is an ascii file. The data processing is usually performed by copying and pasting the relevant parts of the ascii

  8. Effects of Measurement Error on the Output Gap in Japan

    OpenAIRE

    Koichiro Kamada; Kazuto Masuda

    2000-01-01

    Potential output is the largest amount of products that can be produced by fully utilizing available labor and capital stock; the output gap is defined as the discrepancy between actual and potential output. If data on production factors contain measurement errors, total factor productivity (TFP) cannot be estimated accurately from the Solow residual(i.e., the portion of output that is not attributable to labor and capital inputs). This may give rise to distortions in the estimation of potent...