Dosimetric response evaluation of tooth enamel for accelerator-based neutron radiation

International Nuclear Information System (INIS)

Khan, R.F.H.; Rink, W.J.; Boreham, D.R.

2003-01-01

To study the neutron response of human tooth enamel, a number of experiments with an accelerator-based neutron source have been designed. The neutron beam was produced with the low gamma yield, 7 Li(p,n) 7 Be type thick target, using the 3 MV McMaster K.N. Van de Graaff accelerator. The dosimetry was done using a pre-calibrated snoopy type neutron dosimeter. Neutron irradiation induces a dosimetric signal in the tooth enamel at the same defect site as gamma produced damage with the same g-values (g parallel =1.9973, width 0.4 mT g perpendicular =2.002, width 0.3 mT). The dosimetric signal grows linearly with neutron dose from 6-35 Gy tissue dose. Dosimetric response in two different grain sizes (300-500 μm, and grains <4 mm) has shown increased dosimetric amplitude in the larger grains. Dose build up effect on tooth inside the mouth due to cheek was simulated by placing a 4 mm thick paraffin wax layer between the beam and tooth, but had little effect. These results show that for mean neutron energy of 280 keV, the relative neutron response of the human tooth enamel ranges from 8% to 12% of the equivalent gamma ray response

Establishment of 137Cs radiation fields for instrument calibration

International Nuclear Information System (INIS)

Albuquerque, M. da P.P.; Caldas, L.V.E.; Xavier, M.

1988-09-01

In order to study the energy dependence of clinical dosemeters, systems constituted of ionization chambers connected to special electrometers, many times their calibration with the gamma radiation of 137 Cs is necessary. In this case, the radiation field characterization is fundamental. The source used presents and activity of 38,8 Tbq and belongs to the Calibration Laboratory of IPEN. Dosimetric films, gammagraphy films, ionization chambers and Lucite phantons were used. At the calibration distance, 80 cm (detector-source detection), the homogeneity of a 10 X 10 cm 2 radiation field was equal 68%. (author) [pt

New routes of preparation of polyaniline films and dosimetric characterization for high-doses gamma radiation

International Nuclear Information System (INIS)

Pacheco, Ana Paula Lima

2003-08-01

This work presents a new conducting polymeric material based on polyaniline thin films that will be used in the confection of dosimetric devices. On preparation of the films a homogeneous and viscous solution of poly (acrylic acid) and MnO 2 is deposited on PMMA surface, which after dried, is immersed in an acid aniline solution. The films formed present low resistivity (6.10 2 Ωm), good mechanical resistance and adherence on the electrodes. The films were characterized by infrared spectroscopy, conductivity measurements and manganese elemental analyses. The resistance variations show linear correlation (r 2 = 0,9928) with gamma irradiation dose in the range of 1000 to 6000 Gy, with medium error less than 5% and sensitivity response. The dosimetric devices present as advantage real time measurements, low cost, use in calibration of industrial radioactive sources. Moreover, this composite could in future replace Fricke dosimeter and its applications. A calibration curve is showed for PANI dosimeter, here proposed, to use at high gamma doses. (author)

Dosimetric behavior of thermoluminescent dosimeters at low doses in diagnostic radiology

International Nuclear Information System (INIS)

Del Sol F, S.; Garcia S, R.; Guzman M, J.; Sanchez G, D.; Rivera M, T.; Ramirez R, G.; Gaona, E.

2015-10-01

Thermoluminescent (Tl) characteristics of TLD-100, LiF:Mg,Cu,P, and CaSO 4 : Dy the under homogeneous field of X-ray beams of diagnostic irradiation and its verification using thermoluminescent dosimetry is presented. The irradiations were performed utilizing an X-ray beam generated by a Radiology Mexican Company: MRH-II E GMX 325-AF SBV-1 model, with Rotating Anode X-Ray Tube installed in the Hospital Juarez Norte de Mexico in Mexico City. Different thermoluminescent characteristics of dosimetric material were studied, such as, batch homogeneity, Tl glow curve, Tl response as a function of X-ray dose, reproducibility and fading. Materials were calibrated in terms of absorbed dose to the standard calibration distance and positioned in a generic Phantom was used. Dose verification and comparison with the measurements made with that obtained by TLD-100 were analyzed. Preliminary results indicate the dosimetric peak appears at 243, 236 and 277 ± 5 degrees C respectively, these peaks are in agreement with that reported in the literature. Tl glow curve as a function of X-ray dose showed a linearity in the range from 1.76 mGy up to 14.70 mGy for all materials. Fading for a period of one month at room temperature showed low fading LiF:Mg,Cu,P, medium and high for TLD-100 and CaSO 4 : Dy. The results suggest that the three materials are suitable for measurements at low doses in radiodiagnostic, however, for its dosimetric characteristics are most effective for individual applications: personal dosimetry and monitors limb (LiF:Mg,Cu,P), clinical dosimetry and environmental (TLD-100 and CaSO 4 : Dy). (Author)

Definition and production of calibration standard neutron sources for radiation protection device calibration

International Nuclear Information System (INIS)

De Matos, E.

1987-01-01

To improve the characterization of radioprotection devices performances, it would be advisable to calibrate these devices in neutron spectra which are nearly like those met in practice (nuclear reactors, plutonium technology laboratories...). The purpose of this work is, in a first time, to choose the nature and the dimensions of the different shields used to achieve broad typical neutron spectra extending to lower energies from a 14.8 MeV neutron beam. The second step is the evaluation of spectral distribution and calculation of associated dosimetric quantities. For that, several spectrometric techniques are employed: on one hand, activation detectors and Bonner spheres method named rough spectrometry; on the other hand, an accurate spectrometry which uses recoil proton counters. The dosimetric quantities, especially the value of kerma deduced from these spectra must be in good agreement with those measured with a tissue equivalent ionization chamber [fr

Thermoluminescent dosimetric properties of Descalvado sand

International Nuclear Information System (INIS)

Teixeira, M.I.; Caldas, L.V.E.

2006-01-01

Sand samples proceeding from Descalvado, Sao Paulo, were studied with regard to their dosimetric properties using the thermoluminescence technique (TL) for high doses. These sand samples present steady physical and chemical characteristics to the end items, and they are used in the glass industry and for casting. The TL curves of the samples were obtained after an irradiation at the Gamma-Cell system ( 60 Co), of IPEN. The glow curves present two peaks at 80 C and 220 C approximately. Calibration curves were obtained for doses between 50 Gy and 5 kGy. The results indicate that the sand samples can be used for high-doses dosimetry in several areas of applications of ionizing radiation. (Author)

Thermoluminescent dosimetric properties of Descalvado sand

Energy Technology Data Exchange (ETDEWEB)

Teixeira, M.I.; Caldas, L.V.E

2006-07-01

Sand samples proceeding from Descalvado, Sao Paulo, were studied with regard to their dosimetric properties using the thermoluminescence technique (TL) for high doses. These sand samples present steady physical and chemical characteristics to the end items, and they are used in the glass industry and for casting. The TL curves of the samples were obtained after an irradiation at the Gamma-Cell system ({sup 60} Co), of IPEN. The glow curves present two peaks at 80 C and 220 C approximately. Calibration curves were obtained for doses between 50 Gy and 5 kGy. The results indicate that the sand samples can be used for high-doses dosimetry in several areas of applications of ionizing radiation. (Author)

Evaluation of the energy dependence of ionization chambers pencil type calibrated beam tomography standards

International Nuclear Information System (INIS)

Fontes, Ladyjane Pereira; Potiens, Maria da Penha A.

2015-01-01

The Instrument Calibration Laboratory of IPEN (LCI - IPEN) performs calibrations of pencil-type ionization chambers (IC) used in measures of dosimetric survey on clinical systems of Computed Tomography (CT). Many users make mistakes when using a calibrated ionization chamber in their CT dosimetry systems. In this work a methodology for determination of factors of correction for quality (Kq) through the calibration curve that is specific for each ionization chamber was established. Furthermore, it was possible to demonstrate the energy dependence on an pencil-type Ionization Chamber(IC) calibrated at the LCI - IPEN. (author)

Calibration of reference KAP-meters at SSDL and cross calibration of clinical KAP-meters

International Nuclear Information System (INIS)

Hetland, Per O.; Friberg, Eva G.; Oevreboe, Kirsti M.; Bjerke, Hans H.

2009-01-01

In the summer of 2007 the secondary standard dosimetry laboratory (SSDL) in Norway established a calibration service for reference air-kerma product meter (KAP-meter). The air-kerma area product, PKA, is a dosimetric quantity that can be directly related to the patient dose and used for risk assessment associated with different x-ray examinations. The calibration of reference KAP-meters at the SSDL gives important information on parameters influencing the calibration factor for different types of KAP-meters. The use of reference KAP-meters calibrated at the SSDL is an easy and reliable way to calibrate or verify the PKA indicated by the x-ray equipment out in the clinics. Material and methods. Twelve KAP-meters were calibrated at the SSDL by use of the substitution method at five diagnostic radiation qualities (RQRs). Results. The calibration factors varied from 0.94 to 1.18. The energy response of the individual KAP-meters varied by a total of 20% between the different RQRs and the typical chamber transmission factors ranged from 0.78 to 0.91. Discussion. It is important to use a calibrated reference KAP-meter and a harmonised calibration method in the PKA calibration in hospitals. The obtained uncertainty in the PKA readings is comparable with other calibration methods if the information in the calibration certificate is correct used, corrections are made and proper positioning of the KAP-chamber is performed. This will ensure a reliable estimate of the patient dose and a proper optimisation of conventional x-ray examinations and interventional procedures

High dose calibrations at the Pacific Northwest Laboratory

International Nuclear Information System (INIS)

McDonald, J.C.; Fox, R.A.

1988-10-01

The need is increasing for both high radiation exposures and calibration measurements that provide traceability of such exposures to national standards. The applications of high exposures include: electronic component damage studies, sterilization of medical products and food irradiation. Accurate high exposure measurements are difficult to obtain and cannot, in general, be carried out with a single dose measurement system or technique because of the wide range of doses and the variety of materials involved. This paper describes the dosimetric measurement and calibration techniques used at the Pacific Northwest Laboratory (PNL) that make use of radiochromic dye films, thermoluminescent dosimeters (TLDs), ionization chambers, and calorimetric dosimeters. The methods used to demonstrate the consistency of PNL calibrations with national standards will also be discussed. 4 refs

Dosimetry through the Secondary Laboratory of Dosimetric Calibration of Mexico; Dosimetria a traves del Laboratorio Secundario de Calibracion Dosimetrica de Mexico

Energy Technology Data Exchange (ETDEWEB)

Tovar M, V.M.; Alvarez R, J.T.; Medina O, V.P.; Vergara M, F.; Anaya M, R.; Cejudo A, J.; Salinas L, B. [ININ, A.P. 18-1027, 11801 Mexico D.F. (Mexico)

2004-07-01

In the beginnings of the sixty years an urgent necessity is presented mainly in the developing countries, of improving in important form the accuracy in the dosimetry of external faces in therapy of radiations (radiotherapy centers), mainly in the calibration of ''clinical dosemeters''. In 1976 the International Atomic Energy Agency, (IAEA), and the World Health Organization, (WHO), they carried out a mutual agreement with regard to the establishment and operation of a net of Secondary Patron Laboratories of Dosimetry, (LSCD). The necessity to establish measure patterns in the field of the dosimetry of the ionizing radiations, is necessary, to have an accuracy but high in the dosimetry of the radiation beams in therapy which is highly dependent of the dose given to the tumor of those patient with cancer. Similar levels of accuracy are required in protection measures to the radiation with an acceptable smaller accuracy, however, when the personal dosemeters are used to determine the doses received by the individuals under work conditions, such mensurations in therapy of radiations and radiological protection will have traceability through a chain of comparisons to primary or national patterns. The traceability is necessary to assure the accuracy and acceptability of the dosimetric measures, as well as, the legal and economic implications. The traceability is also necessary in the dosimetry of high dose like in the sterilization of different products. The main function of the LSCD is to provide a service in metrology of ionizing radiations, maintaining the secondary or national patterns, which have a traceability to the International System of measures, which is based for if same in the comparison of patterns in the Primary Laboratories of Dosimetry (LPD) under the auspice of the International Office of Weights and Measure (BIPM). The secondary and national patterns in the LSCD constitute in Mexico, the national patterns of the magnitudes in the

Dosimetric calibration of solid state detectors with low energy β sources

International Nuclear Information System (INIS)

Fidanzio, Andrea; Pia Toni, Maria; Capote, Roberto; Pena, Juan; Pasciuti, Katia; Bovi, Maurizio; Perrone, Franco; Azario, Luigi; Lazzeri, Mauro; Gaudino, Diego; Piermattei, Angelo

2008-01-01

A PTW Optidos plastic scintillation and a PTW natural diamond detectors were calibrated in terms of absorbed dose to water with β fields produced by 90 Sr + 90 Y and 85 Kr reference sources. Each source was characterized at the Italian National Metrological Institute - the Istituto Nazionale di Metrologia delle Radiazioni Ionizzanti of ENEA (ENEA-INMRI) - for two different series, 1 and 2, of ISO reference β-particle radiation fields. Beam flattening filters were used for the series 1 β fields to give uniform absorbed dose rates over a large area at a source-to-reference plane distance of 30 cm. The series 2 β fields were produced at source-to-reference plane distance of 10 cm, without the beam flattening filters, in order to obtain higher absorbed dose rates. The reference absorbed dose rate values were directly determined by the Italian national standard for β-particle dosimetry (a PTW extrapolation ionization chamber) for the series 1 β fields and by a calibrated transfer standard chamber, (a Capintec thin fixed-volume parallel plate ionization chamber) for the series 2 β fields. Finally the two solid state detectors were calibrated in terms of absorbed dose to water with the series 2 β field. The expanded uncertainties of the calibration coefficients obtained for the plastic scintillation dosimeter were 10% and 12% (2SD) for the 90 Sr + 90 Y and the 85 Kr sources, respectively. The expanded uncertainties obtained for the diamond dosimeter were 10% (2SD) and 16% (2SD) for the 90 Sr + 90 Y and the 85 Kr sources, respectively. The good results obtained with the 90 Sr + 90 Y and the 85 Kr β sources encourage to implement this procedure to calibrate this type of detectors at shorter distances and with other β sources of interest in brachytherapy, for example the 106 Ru source

Calibration of a tertiary standard in N-ISO qualities for radioprotection and personal dosimetry

International Nuclear Information System (INIS)

Rojas, Enrique; Seminario, Lizet

2013-01-01

Dosimetric calibration of radiation monitors and personal dosimeters in different radiological quantities are performed in order to obtain accurate measurements, for this reason the SSDL calculates the dosimetry calibration factor and its associated uncertainty, for each range of use. The calibration factor is performed using the known radiation field method and its uncertainty is calculated according to the ISO recommendations. The SSDL calculates the expanded uncertainty (U c ) with a coverage factor that provides a level of not less than 95 % of confidence. (authors).

Dosimetric system for prolonged manned flights

International Nuclear Information System (INIS)

Akatov, Yu.A.; Kovalev, E.E.; Sakovich, V.A.; Deme, Sh.; Fekher, I.; Nguen, V.D.

1991-01-01

Comments for the All-Union state standard 25645.202-83 named Radiation safety of a spacecraft crew during space flight. Requirements for personnel dosimetric control, are given. Devices for the dosimetric control used in manned space flights nowadays are reviewed. The performance principle and structure of the FEDOR dosimetric complex under development are discussed

Measuring conditions used for the calibration of ionization chambers at the BIPM

International Nuclear Information System (INIS)

Allisy-Roberts, P.J.; Burs, D.T.; Kessler, C.

2004-12-01

Information is presented on the experimental conditions used at the BIPM in the x- and γ-radiation beams for the calibration of secondary standards in terms of air kerma, absorbed dose in water and ambient dose equivalent, together with the uncertainties involved in the determination of these dosimetric quantities. (authors)

Dosimetric study in iodine-125 seeds for brachytherapy application

International Nuclear Information System (INIS)

Zeituni, Carlos Alberto

2008-01-01

The demand for iodine-125 seeds for use in brachytherapy treatments has experienced an increase along recent years in Brazil and all over the world. All iodine-125 seed must have its operational parameters measured and/or calculated every time changes in the production process are carried out. A complete dosimetric measurement is very expensive, and it is recommended that this procedure must be repeated at least once a year. Thus, this work developed a methodology for the entire dosimetric process. This methodology is based on the scarce information available in the literature, once almost all the methodology used in large industrial laboratories is commercial secret. The proposed methodology was tested using seeds of Amersham-Oncura-Ge Healthcare, which is the largest seed manufactory in the world. In this new methodology, an automatic reader was employed in order to reduce the time required in the selection process of the TLD-100 dosimeters used and a postprocessing of the obtained spectra was carried out. A total of 142 dosimeters were used and only 29 have been selected using the new methodology. Measurements were performed using slabs of Solid Water RW1 to simulate measuring in the 'water', using three different experimental apparatus and each measurement was repeated at least three times. The TLD-100 calibration was performed using a Dermopan II - Siemens. The measured values showed a good agreement with the ones available in the literature. Finally, these measured values were compared with calculated ones obtained by a semiempirical simulation program, showing a good agreement and, therefore, demonstrating the validity of the proposed methodology regarding dosimetric calculations. (author)

Variable transformation of calibration equations for radiation dosimetry

International Nuclear Information System (INIS)

Watanabe, Yoichi

2005-01-01

For radiation dosimetry, dosimetric equipment must be calibrated by using known doses. The calibration is done to determine an equation that relates the absorbed dose to a physically measurable quantity. Since the calibration equation is accompanied by unavoidable uncertainties, the doses estimated with such equations suffer from inherent uncertainties. We presented mathematical formulation of the calibration when the calibration relation is either linear or nonlinear. We also derived equations for the uncertainty of the estimated dose as a function of the uncertainties of the parameters in the equations and the measured physical quantity. We showed that a dosimeter with a linear calibration equation with zero dose-offset enables us to perform relative dosimetry without calibration data. Furthermore, a linear equation justifies useful data manipulations such as rescaling the dose and changing the dose-offset for comparing dose distributions. Considering that some dosimeters exhibit linear response with a large dose-offset or often nonlinear response, we proposed variable transformations of the measured physical quantity, namely, linear- and log-transformation methods. The proposed methods were tested with Kodak X-Omat V radiographic film and BANG (registered) polymer gel dosimeter. We demonstrated that the variable transformation methods could lead to linear equations with zero dose-offset and could reduce the uncertainty of the estimated dose

Laboratory for the Dosimetric Equipment Calibration at the Institute of Nuclear Physics in Cracow

International Nuclear Information System (INIS)

Bilski, P.; Budzanowski, M.; Horwacik, T.; Marczewska, B.; Nowak, T.; Olko, P.; Ryba, E.; Zbroja, K.

2000-12-01

A new calibration laboratory has been developed at the INP, Cracow, Poland. The laboratory is located in a hall of dimension 9 m (length) x 4 m (wide) x 4.5 m (height). For calibration purposes the Cs-137 source of activity 185 MBq / 5 Ci / is applied, placed in the 16 cm thick lead capsule. The beam is collimated using a collimator with a constant opening of 20 o . The source is placed 2 m above the ground to avoid albedo scattering. This source covers a dose rate range from 17 mGy/h to 290 μGy/h. For low-dose calibration 0.05 Ci source is applied. The positioning of the source and opening of the collimator is pneumatically controlled. The dosimeters to be calibrated are placed onto a vehicle with DC motor positioned by PC computer. The vehicle is remotely positioned with the precision of one millimetre at the distance from the source between 1 and 7 meters. The vehicle positioning is controlled electronically and additionally checked via TV-camera. Exact dosimeter positioning is performed with a medical cross-laser and with a telescope device. The construction of the vehicle allows for performing of angular irradiations. On the axis of the vehicle 320 keV Phillips X-ray tube is installed which may be used as an irradiation source. UNIDOS dosimeter with PTW ionisation chambers is used for determination of the dose rate. This calibration stand is designed for calibration of personal dosimeters, calibration of active devices for radiation protections and for research on the newly developed thermoluminescent materials. (author)

Monte Carlo generation of dosimetric parameters for eye plaque dosimetry

International Nuclear Information System (INIS)

Cutajar, D.L.; Green, J.A.; Guatelli, S.; Rosenfeld, A.B.

2010-01-01

Full text: The Centre for Medical Radiation Physics have undertaken the dcvelopment of a quality assurance tool, using silicon pixelated detectors, for the calibration of eye plaques prior to insertion. Dosimetric software to correlate the measured and predicted dose rates has been constructed. The dosimetric parameters within the software, for both 1-125 and Ru-I 06 based eye plaques, were optimised using the Geant4 Monte Carlo toolkit. Methods For 1-125 based plaques, an novel application was developed to generate TG-43 parameters for any seed input. TG-43 parameters were generated for an Oncura model 6711 seed, with data points every millimetre up to 25 mm in the radial direction, and every 5 degrees in polar angle, and correlated to published data. For the Ru106 based plaques, an application was developed to generate dose rates about a Bebig model CCD plaque. Toroids were used to score the deposited dose, taking advantage of the cylindrical symmetry of the plaque, with radii in millimetre increments up to 25 mm, and depth from the plaque surface in millimetre increments up to 25 mm. Results TheTG43 parameters generated for the 6711 seed correlate well with published TG43 data at the given intervals, with radial dose function within 3%, and anisotropy function within 5% for angles greater than 30 degrees. The Ru-l 06 plaque data correlated well with the Bebig protocol of measurement. Conclusion Geant4 is a useful Monte Carlo tool for the generation of dosimetric data for eye plaque dosimetry. which may improve the quality assurance of eye plaque treatment. (author)

Calibrations and evaluation of the quality assurance during 1999 at the National Laboratory for ionising radiation

International Nuclear Information System (INIS)

Grindborg, Jan-Erik; Israelsson, Karl-Erik; Kylloenen, Jan-Erik; Samuelson, Goeran

2000-06-01

The Swedish Radiation Protection Institute is the National Laboratory for the dosimetric quantities kerma, absorbed dose and dose equivalent. The activity is based on established calibration procedures and a quality assurance program for the used standards. This report gives a brief summary of the calibrations performed during 1999 and a more detailed description and analysis of the quality assurance during this year. The report makes it easier to draw conclusions about the long-term stability and possible malfunctions

Upgrading the Medical Physics Calibration Laboratory Towards ISO/IEC 17025: Radiation Standards and Calibration in Diagnostic Radiology

International Nuclear Information System (INIS)

Asmaliza Hashim; Muhammad Jamal Md Isa; Abd Aziz Mhd Ramli; Wan Hazlinda Ismail; Norhayati Abdullah; Shahrul Azlan Azizan; Siti Sara Deraman; Nor Azlin Azraai; Md Khairusalih Md Zin

2010-01-01

Calibration of quality control (QC) test tools used in diagnostic radiology is legally required under the Ministry of Health (MOH) requirement. The Medical Physics Calibration Laboratory of the Malaysian Nuclear Agency is the national focal point for the calibration of quality control test tools used in diagnostic radiology. The Medical Physics Calibration Laboratory has measurement traceability to primary standard dosimetry laboratory (Physikalisch-Technische Bundesanstalt (PTB)), thus providing an interface between the primary standard dosimetry laboratory and Malaysian hospitals, clinics and license class H holder. The Medical Physics Calibration Laboratory facility is comprised of a constant potential x-ray system with a capability of 160 kV tube and a series of reference and working standard ion chambers. The stability of reference and working standard ion chambers was measured using strontium-90. Dosimetric instruments used in diagnostic radiology is calibrated in terms of air kerma to comply with an International Code of Practices of dosimetry for example IAEA's Technical Report Series number 457. The new series of standard radiation qualities was established based on ISO/IEC 61267. The measurement of beam homogeneity was measured using film and ion chamber to define the field size at certain distance and kV output was measured using the spectrometer and non-invasive kVp meter. The uncertainties measurement was determined with expended uncertainties to a level of confidence of approximately 95% (coverage factor k=2). This paper describes the available facility and the effort of the Medical Physics Calibration Laboratory to upgrade the laboratory towards ISO/IEC 17025. (author)

Calibration and intercomparison of neutron moderation spectrometers

International Nuclear Information System (INIS)

Rimpler, A.; Hermanska, J.; Prouza, Z.

1989-01-01

Results have been reported of comparative measurements of neutron fields from bare PuBe and Cf sources using multisphere (Bonner) spectrometers. The experiments were carried out by the Institute of Biophysics and Nuclear Medicine at Charles University in Prague and the National Board for Atomic Safety and Radiation Protection in Berlin. Both sides agreed upon uniform measuring conditions and calibration factors thus rendering possible the comparability of the dosimetric parameters which have been determined and verified, respectively, to an accuracy of ± 10%. 20 refs., 10 tabs., 2 figs. (author)

Dosimetric measurements of an n-butyl cyanoacrylate embolization material for arteriovenous malformations

Energy Technology Data Exchange (ETDEWEB)

Labby, Zacariah E., E-mail: zelabby@humonc.wisc.edu [Department of Human Oncology, University of Wisconsin–Madison, 600 Highland Avenue, Madison, Wisconsin 53792 (United States); Chaudhary, Neeraj [Division of Neurointerventional Radiology, Departments of Radiology and Neurosurgery, University of Michigan Hospital and Health Systems, 1500 East Medical Center Drive, Ann Arbor, Michigan 48109 (United States); Gemmete, Joseph J. [Division of Neurointerventional Radiology, Departments of Radiology, Neurosurgery, and Otolaryngology, University of Michigan Hospital and Health Systems, 1500 East Medical Center Drive, Ann Arbor, Michigan 48109 (United States); Pandey, Aditya S. [Department of Neurosurgery, University of Michigan Hospital and Health Systems, 1500 East Medical Center Drive, Ann Arbor, Michigan 48109 (United States); Roberts, Donald A. [Radiation Physics Division, Department of Radiation Oncology, University of Michigan Hospital and Health Systems, 1500 East Medical Center Drive, Ann Arbor, Michigan 48109 (United States)

2015-04-15

Purpose: The therapeutic regimen for cranial arteriovenous malformations often involves both stereotactic radiosurgery and endovascular embolization. Embolization agents may contain tantalum or other contrast agents to assist the neurointerventionalists, leading to concerns regarding the dosimetric effects of these agents. This study investigated dosimetric properties of n-butyl cyanoacrylate (n-BCA) plus lipiodol with and without tantalum powder. Methods: The embolization agents were provided cured from the manufacturer with and without added tantalum. Attenuation measurements were made for the samples and compared to the attenuation of a solid water substitute using a 6 MV photon beam. Effective linear attenuation coefficients (ELAC) were derived from attenuation measurements made using a portal imager and derived sample thickness maps projected in an identical geometry. Probable dosimetric errors for calculations in which the embolized regions are overridden with the properties of water were calculated using the ELAC values. Interface effects were investigated using a parallel plate ion chamber placed at set distances below fixed samples. Finally, Hounsfield units (HU) were measured using a stereotactic radiosurgery CT protocol, and more appropriate HU values were derived from the ELAC results and the CT scanner’s HU calibration curve. Results: The ELAC was 0.0516 ± 0.0063 cm{sup −1} and 0.0580 ± 0.0091 cm{sup −1} for n-BCA without and with tantalum, respectively, compared to 0.0487 ± 0.0009 cm{sup −1} for the water substitute. Dose calculations with the embolized region set to be water equivalent in the treatment planning system would result in errors of −0.29% and −0.93% per cm thickness of n-BCA without and with tantalum, respectively. Interface effects compared to water were small in magnitude and limited in distance for both embolization materials. CT values at 120 kVp were 2082 and 2358 HU for n-BCA without and with tantalum, respectively

SU-F-T-215: An Investigation Of Multi-Scanner CT Hounsfield Unit Calibration for Pencil Beam Scanning Proton Therapy Using 3D Gamma Analysis

International Nuclear Information System (INIS)

Zhang, J; Li, X; Liu, G; Liu, Q; Liang, J; Ding, X

2016-01-01

Purpose: We compare and investigate the dosimetric impacts on pencil beam scanning (PBS) proton treatment plans generated with CT calibration curves from four different CT scanners and one averaged ‘global’ CT calibration curve. Methods: The four CT scanners are located at three different hospital locations within the same health system. CT density calibration curves were collected from these scanners using the same CT calibration phantom and acquisition parameters. Mass density to HU value tables were then commissioned in a commercial treatment planning system. Five disease sites were chosen for dosimetric comparisons at brain, lung, head and neck, adrenal, and prostate. Three types of PBS plans were generated at each treatment site using SFUD, IMPT, and robustness optimized IMPT techniques. 3D dose differences were investigated using 3D Gamma analysis. Results: The CT calibration curves for all four scanners display very similar shapes. Large HU differences were observed at both the high HU and low HU regions of the curves. Large dose differences were generally observed at the distal edges of the beams and they are beam angle dependent. Out of the five treatment sites, lung plans exhibits the most overall range uncertainties and prostate plans have the greatest dose discrepancy. There are no significant differences between the SFUD, IMPT, and the RO-IMPT methods. 3D gamma analysis with 3%, 3 mm criteria showed all plans with greater than 95% passing rate. Two of the scanners with close HU values have negligible dose difference except for lung. Conclusion: Our study shows that there are more than 5% dosimetric differences between different CT calibration curves. PBS treatment plans generated with SFUD, IMPT, and the robustness optimized IMPT has similar sensitivity to the CT density uncertainty. More patient data and tighter gamma criteria based on structure location and size will be used for further investigation.

Calibration of ionization chambers and determination of the absorbed doses

International Nuclear Information System (INIS)

RANDRIANTSEHENO, H.F

1996-01-01

In order to further improve the accuracy of dosimetric measurements in radiation therapy, the IAEA and WHO supported the establishment of Secondary Standard Dosimetry Laboratory (SSDLs). These SSDLs bridge the gap between the primary measurement standards and the user of ionizing radiation by providing the latter with calibrations against the SSDLs' secondary standards and by giving technical advice and assistance. However, a properly calibrated dosimeter is just necessary first condition for the determination of the dose. It has been demonstrated that the success or failure of radiation treatment depends on the absorbed dose delivered to the tumour and that this should not vary by more than a few per cent from described values. [fr

Determination of the scattered radiation at the Neutron Calibration Laboratory of IPEN using the shadow cone method

Energy Technology Data Exchange (ETDEWEB)

Alvarenga, Tallyson S.; Caldas, Linda V.E. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), São Paulo, SP (Brazil); Freitas, Bruno M. [Coordenacao de Pos-Graduacao e Pesquisa de Engenharia (PEN/COPPE/UFRJ), Rio de Janeiro, RJ (Brazil). Programa de Engenharia Nuclear; Fonseca, Evaldo S.; Pereira, Walsan W., E-mail: talvarenga@ipen.br, E-mail: lcaldas@ipen.br, E-mail: bfreitas@con.ufrj.br, E-mail: walsan@ird.gov.br, E-mail: evaldo@ird.gov.br [Instituto de Radioprotecao e Dosimetria (IRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil)

2017-07-01

Because of the increase in the demand for the calibration of neutron detectors, there is a need for new calibration services. In this context, the Calibration Laboratory of Instituto de Pesquisas Energéticas e Nucleares (IPEN), São Paulo, which already offers calibration services of radiation detectors with standard X, gamma, beta and alpha beams, has recently projected a new test laboratory for neutron detectors. This work evaluated the contribution of dispersed neutron radiation in this laboratory, using the cone shadow method and a Bonner sphere spectrometer to take the measurements at a distance of 100 cm from the neutron source. The dosimetric quantities H⁎(10) and H⁎(10) were obtained at the laboratory, allowing the calibration of detectors. (author)

Determination of the scattered radiation at the Neutron Calibration Laboratory of IPEN using the shadow cone method

International Nuclear Information System (INIS)

Alvarenga, Tallyson S.; Caldas, Linda V.E.; Freitas, Bruno M.

2017-01-01

Because of the increase in the demand for the calibration of neutron detectors, there is a need for new calibration services. In this context, the Calibration Laboratory of Instituto de Pesquisas Energéticas e Nucleares (IPEN), São Paulo, which already offers calibration services of radiation detectors with standard X, gamma, beta and alpha beams, has recently projected a new test laboratory for neutron detectors. This work evaluated the contribution of dispersed neutron radiation in this laboratory, using the cone shadow method and a Bonner sphere spectrometer to take the measurements at a distance of 100 cm from the neutron source. The dosimetric quantities H⁎(10) and H⁎(10) were obtained at the laboratory, allowing the calibration of detectors. (author)

Dosimetric commissioning and system for stereotactic radiation treatments based on linear accelerators with dynamic micromultilaminas collimators

International Nuclear Information System (INIS)

Ascension, Yudy; Alfonso, Rodolfo; Silvestre, Ileana

2009-01-01

Once installed and accepted, a system for stereotactic radiosurgery / stereotactic radiotherapy (CERs / RTE) requires, before starting to be used clinically in patients undergoing a process of commissioning dosimetry, which evaluates all geometric parameters, physical, Dosimetric and technical impact on the precision and accuracy of treatment to administer, and therefore its effectiveness. This process includes training and familiarization of the multidisciplinary team (medical physicists, radiation oncologists, neurosurgeons, dosimetrists, biomedical engineers) with the equipment and techniques used, the quality assurance program and special radiation protection standards for this technology. The aim of this work is to prepare the pre-clinical dosimetric conditions to ensure the quality and radiation safety of treatment with CER RTE. Treatment with CER RTE INOR has a linear accelerator equipped with a micro-multileaf collimator dynamic tertiary (dMLC 3Dline). The system aceleradordMLC geometric and dosimetric was calibrated, using ionization chambers miniature, diode and film dosimetry. The immobilization of the patient and location of the lesion is made by both invasive stereotactic frames and relocatable. The computerized planning of the CER / TEN is done with the ERGO system, for which commissioning is designed test cases of increasing complexity, using planes and anthropomorphic dummies, which help assess the accuracy of the dosimetric calculations and accuracy of the system as a whole. We compared the results of the planning system with measurements, showing that the discrepancies are within tolerances, so it is concluded that from the standpoint of physical dosimetry, the system-under-ERGO accelerator MLC is eligible for clinical use. (author)

parameters affecting the calibration uniformity and traceability of gamma measuring devices

International Nuclear Information System (INIS)

Youssef, S.K.; Henaish, B.A.

1985-01-01

One of the problems which usually defeats the dosimetric evaluations performed by the health and safety experts is the absence of the reproducibility and accuracy of the used measuring devices systems. Furthermore, the traceability of the dose evaluation done by the users themselves are not achieved. Also the uniformity and homogeneity between the various users dosimeters and that available at specified central organization are not maintained. The present manuscript is scoping to deal with such various problems such as: a) dosimeter accuracy, b) traceability of the various users dosimeters and measuring devices. This paper also suggests a programme for the minimum facilities which are required for operating a central calibration laboratory. the responsibility of that central calibration lab., beside the linking chain between the different users and that calibration lab. are stated and discussed in detail. Furthermore, the authors experiences gained in operating the secondary standards calibration laboratory are also reviewed. 2 fig

Dosimetric methodology for extremities of individuals occupationally exposed to beta radiation using the optically stimulated luminescence technique

International Nuclear Information System (INIS)

Pinto, Teresa Cristina Nathan Outeiro

2010-01-01

A dosimetric methodology was established for the determination of extremity doses of individuals occupationally exposed to beta radiation, using Al 2 O 3 :C detectors and the optically stimulated luminescence (OSL) reader system microStar, Landauer. The main parts of the work were: characterization of the dosimetric material Al 2 O 3 :C using the OSL technique; establishment of the dose evaluation methodology; dose rate determination of beta radiation sources; application of the established method in a practical test with individuals occupationally exposed to beta radiation during a calibration simulation of clinical applicators; validation of the methodology by the comparison between the dose results of the practical test using the OSL and the thermoluminescence (TL) techniques. The results show that both the OSL Al-2O 3 :C detectors and the technique may be utilized for individual monitoring of extremities and beta radiation. (author)

Researches, development and characterization of dosimetric materials for monitoring in irradiation processes with high doses

International Nuclear Information System (INIS)

Galante, Ana Maria Sisti

2003-01-01

Dosimetric materials that can be produced in Brazil with material acquired in the national market to replace the imported dosimeters used in radiation processing were developed in this work. Mixtures of potassium nitrate and sensitizers compounds as manganese dioxide, barium nitrate and potassium bromide were prepared in the pellet form. Dosimetric characteristics such as dose-response useful range, sensitivity, environmental conditions and dose rate influences were evaluated in 60 Co gamma radiation fields. Dyed polymethylmethacrylate detectors were also produced and its dosimetric characteristics were evaluated. The main characteristics evaluated in this case were: dose response useful range sensitivity, environmental conditions, dose rate influences and radiation energy dependence in gamma radiation fields and accelerated electrons beam of 0.8 to 1.5 MeV. The applied analytic technique was spectrophotometry. The calibration was performed in the irradiation facilities belonging to IPEN and certified by the International Atomic Energy Agency by means of the program IDAS (International Dose Assurance Service ) using the Fricke dosimeter. The mixture of potassium nitrate and manganese dioxide presented the best results and a wide dose range between 200 and 600 kGy. The response of the developed polymethylmethacrylate detectors are similar to the imported detectors and the dose range is characteristic to each detector and depends on the dye added in its formulation. (author)

Laboratory for Calibration of Gamma Radiation Measurement Instruments (LabCal) of Institute of Chemical, Biological, Radiological and Nuclear Defense (IDQBRN) from Brazilian Army Technology Center (CTEx)

International Nuclear Information System (INIS)

Amorim, Aneuri de; Balthar, Mario Cesar V.; Santos, Avelino; Vilela, Paulo Ricardo T. de; Oliveira, Luciano Santa Rita; Penha, Paulo Eduardo C. de Oliveira; Gonzaga, Roberto Neves; Andrade, Edson Ramos de; Oliveira, Celio Jorge Vasques de; Fagundes, Luiz Cesar S.

2016-01-01

This paper describes the calibration laboratory deployment steps (LABCAL) gamma ionizing radiation measuring instruments in the Army Technology Center, CTEx. Initially the calibration of radiation monitors will be held in the dosimetric quantity air kerma and operational quantity ambient dose equivalent H*(d). The LABCAL / CTEx has not yet authorized by CASEC / CNEN. This laboratory aims to calibrate the ionizing radiation instruments used by the Brazilian Army. (author)

A dosimetric intercomparison of brachytherapy facilities in Ireland, Scotland and the North of England

International Nuclear Information System (INIS)

Heeney, Conor; McClean, Brendan; Kelly, Colin

2005-01-01

Background and purpose: A dosimetric intercomparison of brachytherapy remote afterloading units in Ireland, Scotland and the North of England has been carried out involving 9 radiotherapy centres, and sampling 5 HDR and 6 LDR units. Materials and methods: Absolute calibrations have been performed in air on both HDR and LDR sources. The results are expressed in terms of a ratio of local to calibrated value. Frequency distributions were obtained for the multi-source LDR units by individually measuring each source. Using these distributions the effect of non-uniform source strength on the dose rate at Manchester point A was assessed for a typical clinical brachytherapy insertion for carcinoma of the cervix. Both frequency and dose rate distribution curves were modeled using normal statistics and characterised in terms of the mean (μ) and standard deviation (σ). Results: Evaluation of the HDR units indicated a mean ratio of 1.008 (±0.01) while for LDR the mean ratio was 0.997 (±0.02). The LDR frequency distributions demonstrated a variation of σ values extending from 1.4 to 3.0% of μ. It was shown that this non-uniformity in source strength introduced an uncertainty in the treatment planning process of between 0.8 and 1.8% when compared to the assumption of uniform source strength. Conclusions: The results of this intercomparison indicate dosimetric consistency between centres for both LDR and HDR units. The distribution of LDR source strengths were within expected limits and the resultant dose rate distributions were considered clinically acceptable

Update of the Picker C9 irradiator control system of the gamma II room of the secondary laboratory of dosimetric calibration; Actualizacion del sistema de control del irradiador Picker C9 de la sala gamma II del laboratorio secundario de calibracion dosimetrica

Energy Technology Data Exchange (ETDEWEB)

Simon S, L. E.

2016-07-01

The Picker C9 irradiator is responsible for the calibration of different radiological equipment and the control system that maintains it in operation is designed in the graphical programming software LabVIEW (Laboratory Virtual Instrumentation Engineering Workbench), being its major advantages: the different types of communication, easy interconnection with other software and the recognition of different hardware devices, among others. Operation of the irradiator control system is performed with the NI-Usb-6008 (DAQ) data acquisition module of the National Instruments Company. The purpose of this work is to update the routines that make the Picker C9 control system of the gamma II room of the secondary laboratory of dosimetric calibration, using the graphic programming software LabVIEW, as well as to configure the new acquisition hardware of data that is implemented to control the Picker C9 irradiator system and ensure its operation. (Author)

Dosimetry and Calibration Section

International Nuclear Information System (INIS)

Otto, T.

1999-01-01

The Dosimetry and Calibration Section fulfils two tasks within CERN's Radiation Protection Group: the Individual Dosimetry Service monitors more than 5000 persons potentially exposed to ionizing radiation on the CERN sites, and the Calibration Laboratory verifies throughout the year, at regular intervals, over 1000 instruments, monitors, and electronic dosimeters used by RP Group. The establishment of a Quality Assurance System for the Individual Dosimetry Service, a requirement of the new Swiss Ordinance for personal dosimetry, put a considerable workload on the section. Together with an external consultant it was decided to identify and then describe the different 'processes' of the routine work performed in the dosimetry service. The resulting Quality Manual was submitted to the Federal Office for Public Health in Bern in autumn. The CERN Individual Dosimetry Service will eventually be officially endorsed after a successful technical test in March 1999. On the technical side, the introduction of an automatic development machine for gamma films was very successful. It processes the dosimetric films without an operator being present, and its built-in regeneration mechanism keeps the concentration of the processing chemicals at a constant level

Comparative dosimetric study in the estimation of the dose rate of the Transelektro LGI-01 irradiator

International Nuclear Information System (INIS)

Carrasco A, H.; Urena N, F.F.

2004-01-01

The 60 Co TRANSELEKTRO, model LGI-0 1, Hungarian, is similar to the Canadian Gamma cell. The evaluation of the dose ratio in the geometric center of the exposition chamber of the LGI-0 1 is presented in this paper. In order to do this two types of dosimeters were used: the alanine, and the L8-C 1 red acrylic (Canadian). Three dosimeters of each type were irradiated at 1, 2, 3, 4, 5, 6, 7 and 8 h. The respective intensities and absorbencies were measured and used to determine the proper absorbed doses and the dose ratio. The results obtained with both dosimeters were compared with the ratio dose that was reported by the Secondary Laboratory of Dosimetric Calibration of the Metrology Department of the ININ, which used a ionization chamber for the calibration of the LGI-0 1. The alanine dosemeter showed a ± 1.3% dispersion while with the acrylic dosemeter the dispersion was of ± 3.2%, with respect to the value reported by the authorized Calibration Laboratory. This paper was also used to update the calibration table of the L8-C1 red acrylic. (Author)

Dosimetric Characteristics of a LKB:Cu,Mg Solid Thermoluminescence Detector

International Nuclear Information System (INIS)

Alajerami Yasser Saleh Mustafa; Hashim Suhairul; Ramli Ahmad Termizi; Saleh Muneer Aziz; Kadir Ahmad Bazlie Bin Abdul; Saripan, Mohd. Iqbal

2013-01-01

We present the main thermoluminescence characteristics of a newly borate glass dosimeter modified with lithium and potassium carbonate (LKB) and co-doped with CuO and MgO. An enhancement of about three times has been shown with the increment of 0.1mol% MgO as a co-dopant impurity. The effects of dose linearity, storage capacity, effective atomic number and energy dose response are studied. The proposed dosimeter shows a simple glow curve, good linearity up to 10 3 Gy, close effective atomic number and photon energy independence. The current results suggest using the proposed dosimeter in different dosimetric applications

Dosimetric behavior of thermoluminescent dosimeters at low doses in diagnostic radiology; Comportamiento dosimetrico de dosimetros termoluminiscentes a bajas dosis en radiodiagnostico

Energy Technology Data Exchange (ETDEWEB)

Del Sol F, S.; Garcia S, R.; Guzman M, J.; Sanchez G, D.; Rivera M, T. [IPN, Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada, Av. Legaria 694, Col. Irrigacion, 11500 Mexico D. F. (Mexico); Ramirez R, G. [Hospital Juarez de Mexico, Av. IPN 5160, Col. Magdalena de las Salinas, 07760 Mexico D. F. (Mexico); Gaona, E., E-mail: susi2489@hotmail.com [Universidad Autonoma Metropolitana, Unidad Xochimilco, Calz. del Hueso 1100, Col. Villa Quietud, 04960 Mexico D. F. (Mexico)

2015-10-15

Thermoluminescent (Tl) characteristics of TLD-100, LiF:Mg,Cu,P, and CaSO{sub 4}: Dy the under homogeneous field of X-ray beams of diagnostic irradiation and its verification using thermoluminescent dosimetry is presented. The irradiations were performed utilizing an X-ray beam generated by a Radiology Mexican Company: MRH-II E GMX 325-AF SBV-1 model, with Rotating Anode X-Ray Tube installed in the Hospital Juarez Norte de Mexico in Mexico City. Different thermoluminescent characteristics of dosimetric material were studied, such as, batch homogeneity, Tl glow curve, Tl response as a function of X-ray dose, reproducibility and fading. Materials were calibrated in terms of absorbed dose to the standard calibration distance and positioned in a generic Phantom was used. Dose verification and comparison with the measurements made with that obtained by TLD-100 were analyzed. Preliminary results indicate the dosimetric peak appears at 243, 236 and 277 ± 5 degrees C respectively, these peaks are in agreement with that reported in the literature. Tl glow curve as a function of X-ray dose showed a linearity in the range from 1.76 mGy up to 14.70 mGy for all materials. Fading for a period of one month at room temperature showed low fading LiF:Mg,Cu,P, medium and high for TLD-100 and CaSO{sub 4}: Dy. The results suggest that the three materials are suitable for measurements at low doses in radiodiagnostic, however, for its dosimetric characteristics are most effective for individual applications: personal dosimetry and monitors limb (LiF:Mg,Cu,P), clinical dosimetry and environmental (TLD-100 and CaSO{sub 4}: Dy). (Author)

Dosimetric control of radiotherapy treatments by Monte Carlo simulation of transmitted portal dose image

International Nuclear Information System (INIS)

Badel, Jean-Noel

2009-01-01

This research thesis addresses the dosimetric control of radiotherapy treatments by using amorphous silicon digital portal imagery. In a first part, the author reports the analysis of the dosimetric abilities of the imager (iViewGT) which is used in the radiotherapy department. The stability of the imager response on a short and on a long term has been studied. A relationship between the image grey level and the dose has been established for a reference irradiation field. The influence of irradiation parameters on the grey level variation with respect to the dose has been assessed. The obtained results show the possibility to use this system for dosimetry provided that a precise calibration is performed while taking the most influencing irradiation parameters into account, i.e. photon beam nominal energy, field size, and patient thickness. The author reports the development of a Monte Carlo simulation to model the imager response. It models the accelerator head by a generalized source point. Space and energy distributions of photons are calculated. This modelling can also be applied to the calculation of dose distribution within a patient, or to study physical interactions in the accelerator head. Then, the author explores a new approach to dose portal image prediction within the frame of an in vivo dosimetric control. He computes the image transmitted through the patient by Monte Carlo simulation, and measures the portal image of the irradiation field without the patient. Validation experiments are reported, and problems to be solved are highlighted (computation time, improvement of the collimator simulation) [fr

Dosimetric essay in dental radiology

International Nuclear Information System (INIS)

Lopez Salaberry, M.

1998-01-01

A neck study was observated in the tiroids glands,laryngeal zone, sensitive organs for the ionizing radiation for increase dental xray exams. Was selected 29th patients with radiography prescription complete (in the Odontology Faculty Clinics Uruguaian). It took radiographies with and without tiroids necklace and apron lead using dosemeters. Dosimetric studies had demonstrated good dose between patients. For measuring the radiation dose have been used TLD thermoluminescence dosimetric and Harshaw 6600 for read it. The thyroids necklace use and odontology postgrading for training course for dentistry was the two recommendations advised

The dosimetric control in radiotherapy

International Nuclear Information System (INIS)

Veres, A.

2009-01-01

The author first presents the thermoluminescent dosimetry method developed by the Equal-Estro Laboratory to control radiotherapy systems, according to which dosimeters are mailed by the radiotherapy centres to the laboratory, and then analyzed with respect to the level of dose bias. In a second part, he discusses the different techniques used for the dosimetric control of new radiotherapy methods (intensity-modulated radiation therapy, tomo-therapy) for which film dosimetry is applied. He also evokes the development of new phantoms and the development of a method for the dosimetric control of proton beams

Dosimetric validation of Monaco treatment planning system on an Elekta VersaHD linear accelerator.

Science.gov (United States)

Narayanasamy, Ganesh; Saenz, Daniel L; Defoor, Dewayne; Papanikolaou, Niko; Stathakis, Sotirios

2017-11-01

The purpose of this study is to perform dosimetric validation of Monaco treatment planning system version 5.1. The Elekta VersaHD linear accelerator with high dose rate flattening filter-free photon modes and electron energies was used in this study. The dosimetric output of the new Agility head combined with the FFF photon modes warranted this investigation into the dosimetric accuracy prior to clinical usage. A model of the VersaHD linac was created in Monaco TPS by Elekta using commissioned beam data including percent depth dose curves, beam profiles, and output factors. A variety of 3D conformal fields were created in Monaco TPS on a combined Plastic water/Styrofoam phantom and validated against measurements with a calibrated ion chamber. Some of the parameters varied including source to surface distance, field size, wedges, gantry angle, and depth for all photon and electron energies. In addition, a series of step and shoot IMRT, VMAT test plans, and patient plans on various anatomical sites were verified against measurements on a Delta 4 diode array. The agreement in point dose measurements was within 2% for all photon and electron energies in the homogeneous phantom and within 3% for photon energies in the heterogeneous phantom. The mean ± SD gamma passing rates of IMRT test fields yielded 93.8 ± 4.7% based on 2% dose difference and 2 mm distance-to-agreement criteria. Eight previously treated IMRT patient plans were replanned in Monaco TPS and five measurements on each yielded an average gamma passing rate of 95% with 6.7% confidence limit based on 3%, 3 mm gamma criteria. This investigation on dosimetric validation ensures accuracy of modeling VersaHD linac in Monaco TPS thereby improving patient safety. © 2017 The Authors. Journal of Applied Clinical Medical Physics published by Wiley Periodicals, Inc. on behalf of American Association of Physicists in Medicine.

Blood compounds irradiation process: assessment of absorbed dose using Fricke and Thermoluminescent dosimetric systems

Energy Technology Data Exchange (ETDEWEB)

Soares, Gabriela de Amorim; Squair, Peterson Lima; Pinto, Fausto Carvalho; Belo, Luiz Claudio Meira; Grossi, Pablo Andrade [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN-CNEN/MG), Belo Horizonte, MG (Brazil)], e-mail: gas@cdtn.br, e-mail: pls@cdtn.br, e-mail: fcp@cdtn.br, e-mail: lcmb@cdtn.br, e-mail: pabloag@cdtn.br

2009-07-01

The assessment of gamma absorbed doses in irradiation facilities allows the quality assurance and control of the irradiation process. The liability of dose measurements is assign to the metrological procedures adopted including the uncertainty evaluation. Fricke and TLD 800 dosimetric systems were used to measure absorbed dose in the blood compounds using the methodology presented in this paper. The measured absorbed doses were used for evaluating the effectiveness of the irradiation procedure and the gamma dose absorption inside the irradiation room of a gamma irradiation facility. The radiation eliminates the functional and proliferative capacities of donor T-lymphocytes, preventing Transfusion associated graft-versus-host disease (TA-GVHD), a possible complication of blood transfusions. The results show the applicability of such dosimetric systems in quality assurance programs, assessment of absorbed doses in blood compounds and dose uniformity assign to the blood compounds irradiation process by dose measurements in a range between 25 Gy and 100 Gy. (author)

Blood compounds irradiation process: assessment of absorbed dose using Fricke and Thermoluminescent dosimetric systems

International Nuclear Information System (INIS)

Soares, Gabriela de Amorim; Squair, Peterson Lima; Pinto, Fausto Carvalho; Belo, Luiz Claudio Meira; Grossi, Pablo Andrade

2009-01-01

The assessment of gamma absorbed doses in irradiation facilities allows the quality assurance and control of the irradiation process. The liability of dose measurements is assign to the metrological procedures adopted including the uncertainty evaluation. Fricke and TLD 800 dosimetric systems were used to measure absorbed dose in the blood compounds using the methodology presented in this paper. The measured absorbed doses were used for evaluating the effectiveness of the irradiation procedure and the gamma dose absorption inside the irradiation room of a gamma irradiation facility. The radiation eliminates the functional and proliferative capacities of donor T-lymphocytes, preventing Transfusion associated graft-versus-host disease (TA-GVHD), a possible complication of blood transfusions. The results show the applicability of such dosimetric systems in quality assurance programs, assessment of absorbed doses in blood compounds and dose uniformity assign to the blood compounds irradiation process by dose measurements in a range between 25 Gy and 100 Gy. (author)

Development of a dosimetric system for emergency situation involving person of the public

International Nuclear Information System (INIS)

Costa, Zelia Maria da

1999-01-01

A dosimetric system was developed for emergency situation based on electron spin resonance spectrometry (E.S.R.) and some materials such as tooth enamel, bovine bone, CaCO 3 and sugar as detector. The purpose of this work was to find common materials, which are both reliable and sensitive and make possible quickly to assess the absorbed dose. The research includes the collection and preparation of samples, the evaluation, treatment and interpretation of ESR signal and the procedure for dose reconstruction. The calibration of the dosemeter was performed using gamma radiation from a Co-60 source. The results obtained confirm the variability of the use of this system in case of an accident. (author)

Applications of sensitivity function to dosimetric data adjustments

International Nuclear Information System (INIS)

Nakazawa, Masaharu

1984-01-01

Sensitivity functions are applied to the dosimetric field in the spectrum unfolding technique, also called as the data adjustment technique which are statistical estimation procedures of the neutron spectrum or relating dosimetric quantities basing on the reaction-rate data measurements. Using the practical formulae and numerical examples of the sensitivity functions in the dosimetric data adjustments, two comments are made that (1) present sensitivity values are highly depending on the initial spectrum inputs and (2) more attention should be paid to the dependency of the sensitivity on the very uncertain covariance data inputs of the initial neutron spectrum. (author)

Evolution of dosimetric phantoms

International Nuclear Information System (INIS)

Reddy, A.R.

2010-01-01

In this oration evolution of the dosimetric phantoms for radiation protection and for medical use is briefly reviewed. Some details of the development of Indian Reference Phantom for internal dose estimation are also presented

Calibrations and evaluation of the quality assurance during 1999 at the National Laboratory for ionising radiation; Kalibrerings- och normalieverksamheten vid Riksmaetplats 06 under 1999

Energy Technology Data Exchange (ETDEWEB)

Grindborg, Jan-Erik; Israelsson, Karl-Erik; Kylloenen, Jan-Erik; Samuelson, Goeran

2000-06-01

The Swedish Radiation Protection Institute is the National Laboratory for the dosimetric quantities kerma, absorbed dose and dose equivalent. The activity is based on established calibration procedures and a quality assurance program for the used standards. This report gives a brief summary of the calibrations performed during 1999 and a more detailed description and analysis of the quality assurance during this year. The report makes it easier to draw conclusions about the long-term stability and possible malfunctions.

RPL-SC dosimetric system for measuring gamma and neutron irradiation in case of emergency

International Nuclear Information System (INIS)

Khristova, M. G.

1993-01-01

A RPL-SC dosimetric system is designed based on radiophotoluminescence (RPL) and on the effect of fast neutron bombardment of silicon semiconductor (SC) diodes. The experimental prototype consists of a computerized automatic measurement system and an individual dosimetric cassette accommodating RPL and SC detectors. The equipment includes: a device for measurement of the direct voltage of Si diodes and the RPL light emitted by RPL detectors; a compartment with dosimetric cassettes to be measured; a manipulator with three positions executing automatic measurement of cassettes; a computer and a printer. The system operates in both manual and automatic modes. In the manual mode each step of the manipulator is set up by the operator who changes the ranges after they have been filled to capacity and registers the results. In the automatic mode the whole process of maintaining the supply and control voltage, of manipulator's operation, measuring, data recording and data processing are controlled by a specially designed computer programme. Main technical parameters: 1) Measurement range of absorbed dose: gamma rays - 10 -3 to 10 2 Gy; thermal neutrons - 10 -3 to 10 2 Gy; fast neutrons - 10 to 30 Gy. 2) Energy range: gamma rays - 0.04 to 1.25 MeV; thermal neutrons - 0.024 eV; fast neutrons - 0.3 to 14 MeV. 3) Relative measurement error - ±15% 4) Recurrent measurement of one and the same dose. 5) Measurement time of 1 detector - 15 sec. (author)

Experimental and theoretical determination of dosimetric characteristics of IsoAid ADVANTAGETM125I brachytherapy source

International Nuclear Information System (INIS)

Meigooni, Ali S.; Hayes, Joshua L.; Zhang Hualin; Sowards, Keith

2002-01-01

125 I brachytherapy sources are being used for interstitial implants in tumor sites such as the prostate. Recently, the ADVANTAGE TM 125 I, Model IAI-125, source became commercially available for interstitial brachytherapy treatment. Dosimetric characteristics (dose rate constant, radial dose function, and anisotropy function) of this source were experimentally and theoretically determined, following the AAPM Task Group 43 recommendations. Derivation of the dose rate constant was based on recent NIST WAFAC calibration performed in accordance with their 1999 standard. Measurements were performed in Solid Water TM phantom using LiF thermoluminescent dosimeters. The theoretical calculations were performed in both Solid Water TM and water using the PTRAN Monte Carlo code. The results indicated that a dose rate constant of the new source in water was 0.98±0.03 cGy h -1 U -1 . The radial dose function of the new source was measured in Solid Water TM and calculated both in water and Solid Water TM at distances up to 10.0 cm. The anisotropy function, F(r,θ), of the new source was measured and calculated in Solid Water TM at distances of 2 cm, 3 cm, 5 cm, and 7 cm and also was calculated in water at distances ranging from 1 cm to 7 cm from the source. From the anisotropy function, the anisotropy factors and anisotropy constant were derived. The anisotropy constant of the ADVANTAGE TM 125 I source in water was found to be 0.97±0.03. The dosimetric characteristics of this new source compared favorably with those from the Amersham Health Model 6711 source. Complete dosimetric parameters of the new source are presented in this paper

Hot pixel generation in active pixel sensors: dosimetric and micro-dosimetric response

Science.gov (United States)

Scheick, Leif; Novak, Frank

2003-01-01

The dosimetric response of an active pixel sensor is analyzed. heavy ions are seen to damage the pixel in much the same way as gamma radiation. The probability of a hot pixel is seen to exhibit behavior that is not typical with other microdose effects.

SU-E-T-128: Dosimetric Characteristics of Gafchromic EBT3 Films for Megavoltage Photon and Proton Beams.

Science.gov (United States)

Hayashi, N; Kato, H; Yada, R; Matsunaga, T; Ehara, I; Adachi, Y

2012-06-01

Gafchromic film for quantitative analysis was renewed from EBT2 to EBT3 film in November 2011. The purpose of this study is to investigate the relevant characteristics of EBT3 film for its application in dosimetric verification for IMRT/VMAT or proton therapy. We investigated the characteristics of EBT3 film with comparison of previous EBT2 film. The experiments in this study composed two categories. At first, the photo spectroscopy for the irradiated film was compared between EBT2 and EBT3. The film 1 day after the irradiation was analyzed by a photo spectrometer (SR520: JASCO Corporation, Japan). Secondly, we investigated several calibration curves which obtained by same batch. The films were calibrated by irradiation the films to 13 dose steps. The irradiated films were scanned by a flatbed scanner (ES-10000XL, Epson-Seiko Corporation, Japan). The difference on scan orientation was evaluated alternate portrait and landscape directions. The photon and proton beams were delivered from Clinac 21EX (Varian) and Mitsubishi machine, respectively. The peak absorption wavelength of EBT3 film and its response at all active range were basically same with that of EBT2 film. The peak wavelength of photo absorption in EBT3 was observed at 585 and 634 nm. The fog optical density was increased due to the hazy matte polyester for active layer. However, there is no change the tendency of the calibration curve responding to megavoltage photon and proton beams. The scan orientation dependency of EBT3 film was observed with similar to EBT2 film. The optical density of portrait orientation was 10% higher than that of landscape orientation. The dosimetric characteristics of EBT3 film were basically same with EBT2 film. With regard to the matte polyester, the creation of Newton's rings during scanning procedure was reduced. However, the suitable scan protocol should be used for accurate film dosimetry. © 2012 American Association of Physicists in Medicine.

Dosimetric and geometric evaluation of a novel stereotactic radiotherapy device for breast cancer: The GammaPod Trade-Mark-Sign

Energy Technology Data Exchange (ETDEWEB)

Mutaf, Yildirim D.; Yi, Byong Yong; Prado, Karl; D' Souza, Warren D.; Regine, William F.; Feigenberg, Steven J. [Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, Maryland 21201 (United States); Zhang Jin [Xcision Medical Systems, Columbia, Maryland 21045 (United States); Yu, Cedric X. [Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, Maryland 21201 and Xcision Medical Systems, Columbia, Maryland 21045 (United States)

2013-04-15

Purpose: A dedicated stereotactic gamma irradiation device, the GammaPod Trade-Mark-Sign from Xcision Medical Systems, was developed specifically to treat small breast cancers. This study presents the first evaluation of dosimetric and geometric characteristics from the initial prototype installed at University of Maryland Radiation Oncology Department. Methods: The GammaPod Trade-Mark-Sign stereotactic radiotherapy device is an assembly of a hemi-spherical source carrier containing 36 {sup 60}Co sources, a tungsten collimator, a dynamically controlled patient support table, and the breast immobilization system which also functions as a stereotactic frame. The source carrier contains the sources in six columns spaced longitudinally at 60 Degree-Sign intervals and it rotates together with the variable-size collimator to form 36 noncoplanar, concentric arcs focused at the isocenter. The patient support table enables motion in three dimensions to position the patient tumor at the focal point of the irradiation. The table moves continuously in three cardinal dimensions during treatment to provide dynamic shaping of the dose distribution. The breast is immobilized using a breast cup applying a small negative pressure, where the immobilization cup is embedded with fiducials also functioning as the stereotactic frame for the breast. Geometric and dosimetric evaluations of the system as well as a protocol for absorbed dose calibration are provided. Dosimetric verifications of dynamically delivered patient plans are performed for seven patients using radiochromic films in hypothetical preop, postop, and target-in-target treatment scenarios. Results: Loaded with 36 {sup 60}Co sources with cumulative activity of 4320 Ci, the prototype GammaPod Trade-Mark-Sign unit delivers 5.31 Gy/min at the isocenter using the largest 2.5 cm diameter collimator. Due to the noncoplanar beam arrangement and dynamic dose shaping features, the GammaPod Trade-Mark-Sign device is found to deliver

Establishment of a dosimetric system for high doses using glasses

International Nuclear Information System (INIS)

Correa Quezada, Valeria de la Asuncion

1997-01-01

A routine dosimetric system was developed using commercial glass samples. The dosimetric characteristics of national and imported samples were studied: batch uniformity, response repeatability, reutilization, absorbed dose response, detection range, response stability as a function of absorbed dose, storage temperature and thermal treatments pre- and post-irradiation, using the optical absorption technique. As an application, the dosimetric system was tested in a flower irradiation process at IPEN. All the obtained results show the usefulness of the proposed system for high dose dosimetry. (author)

New routes of preparation of polyaniline films and dosimetric characterization for high-doses gamma radiation; Novas rotas de preparacao de filmes de polianilina e caracterizacao dosimetrica para radiacao gama em altas doses

Energy Technology Data Exchange (ETDEWEB)

Pacheco, Ana Paula Lima

2003-08-15

This work presents a new conducting polymeric material based on polyaniline thin films that will be used in the confection of dosimetric devices. On preparation of the films a homogeneous and viscous solution of poly (acrylic acid) and MnO{sub 2} is deposited on PMMA surface, which after dried, is immersed in an acid aniline solution. The films formed present low resistivity (6.10{sup 2} {omega}m), good mechanical resistance and adherence on the electrodes. The films were characterized by infrared spectroscopy, conductivity measurements and manganese elemental analyses. The resistance variations show linear correlation (r{sup 2} = 0,9928) with gamma irradiation dose in the range of 1000 to 6000 Gy, with medium error less than 5% and sensitivity response. The dosimetric devices present as advantage real time measurements, low cost, use in calibration of industrial radioactive sources. Moreover, this composite could in future replace Fricke dosimeter and its applications. A calibration curve is showed for PANI dosimeter, here proposed, to use at high gamma doses. (author)

Calibrating page sized Gafchromic EBT3 films

International Nuclear Information System (INIS)

Crijns, W.; Maes, F.; Heide, U. A. van der; Van den Heuvel, F.

2013-01-01

cost effectiveness and dosimetric accuracy. The validation resulted in dose errors of 1%–2% for the two different time points, with a maximal absolute dose error around 0.05 Gy. The lateral correction reduced the RMSE values on the sides of the film to the RMSE values at the center of the film. Conclusions: EBT3 Gafchromic films were calibrated for large field dosimetry with a limited number of page sized films and simple static calibration fields. The transmittance was modeled as a linear combination of two transmittance states, and associated with dose using a rational calibration function. Additionally, the lateral scan effect was resolved in the calibration function itself. This allows the use of page sized films. Only two calibration films were required to estimate both the dose and the lateral response. The calibration films were used over the course of a week, with residual dose errors ⩽2% or ⩽0.05 Gy.

Development of the Nation-Wide Dosimetric Monitoring Network in Ukraine

International Nuclear Information System (INIS)

Chumak, V.; Boguslavskaya, A.; Musijachenko, A.

2004-01-01

Development of the nation-wide network for monitoring and registration of individual doses is being in progress in Ukraine. The need for urgent action is caused by the fact, that despite wide use of nuclear energy and radiation sources in industry and medicine, there is no centralized dose accounting system in Ukraine, existing dosimetry services operate obsolete manual TLD readers and no methodological unity is observed by the dosimetry services. Presently the mixed dosimetric monitoring is practiced in Ukraine. Nuclear power plants and some major nuclear facilities have their own dosimetry services responsible for dosimetric monitoring of workers. Rest of occupationally exposed persons is monitored by territorial dosimetry laboratories affiliated to sanitary and epidemiology supervision bodies. In total these services cover about 38,000 occupationally exposed workers, including 5,500 in medicine, 16,400 employees of five nuclear power plants and about 16,000 workers dealing with other sources of occupational exposure (industry, research, military). It is prescribed by the governmental decree that three-level united state system assigned to covering all aspects of efficient dosimetric monitoring should be established. The tasks of the system, in particular, are: securing methodical unity of individual dosimetric monitoring; scientific and methodological guidance of individual dosimetric control; procurement of common technical policy regarding nomenclature and operation of instrumentation; implementation of quality assurance programs; development and support of information infrastructure for logging, storage and access to data on individual dosimetric monitoring, in particular - keeping the national registry of individual doses; training and certification of personnel engaged in the system of individual dosimetric monitoring. In its development, the national system will be guided by international experience and will be established according to the best practices

EPR of gamma irradiated solid sucrose and UV spectra of its solution. An attempt for calibration of solid state/EPR dosimetry

International Nuclear Information System (INIS)

Yordanov, N.D.; Karakirova, Y.

2007-01-01

A simple new approach for independent calibration of solid state/EPR (SS/EPR) dosimetry system is reported. It is based on the fact that: (i) gamma-irradiation of solid sucrose (sugar) induces stable EPR detectable free radicals accompanied by UV detectable brown colour stable in the solid state and in solution; (ii) both the EPR intensity of gamma-irradiated solid sucrose and its solution UV absorbance linearly depend on the absorbed dose high energy radiation and may be independently used for dosimetric purpose; (iii) UV spectrometers are calibrated. The correlation between EPR response and absorbed dose radiation of solid sucrose and UV absorption of its solutions is used in the present communication for calibration purpose. The procedure of sucrose extraction from sucrose-paraffin dosimeters is described. The calibration procedure may be applied to any other (alanine, self-calibrated, etc.) SS/EPR dosimeters, simultaneously irradiated with sucrose

Computerized dosimetric system for studying radiation fields of afterloading apparatus

International Nuclear Information System (INIS)

Andryushin, O.S.; Gorshkov, M.I.

1988-01-01

Works on designing a computerized dosimetric scanner (CODOS) for studying radiation fields of remote therapeutic apparatus, providing dosimetric data input from semiconductor transducers and ionization chambers directly into the computer memory were carried out. The basic problems were to provide reproducibility and accuracy of the initial dosimetric data, formation of the data bank on LUEhV-15M1 accelerator bremsstrahlung and electron radiation fields. An extra problem was to provide isodose curves for manual scheduling of radiotherapy. The 15 VUMS-28-025 complex based on Elektronika-60 computer was chosen as a host computer, photodiodes were used as a semiconductor detector, the 70108 rod chamber and VA-J-18 dosemeters were used as an ionization chamber. The results of studies with the CODOS system have been shown that it meets the dosimetric requirements for therapeutic apparatus

Laboratory for Calibration of Gamma Radiation Measurement Instruments (LabCal) of Institute of Chemical, Biological, Radiological and Nuclear Defense (IDQBRN) from Brazilian Army Technology Center (CTEx); Laboratorio de Calibracao de Instrumentode Medicao de Radiacao Gama (LabCal) do IDQBRN do CTEx

Energy Technology Data Exchange (ETDEWEB)

Amorim, Aneuri de; Balthar, Mario Cesar V.; Santos, Avelino; Vilela, Paulo Ricardo T. de; Oliveira, Luciano Santa Rita; Penha, Paulo Eduardo C. de Oliveira; Gonzaga, Roberto Neves; Andrade, Edson Ramos de; Oliveira, Celio Jorge Vasques de; Fagundes, Luiz Cesar S., E-mail: aneurideamorim@gmail.com [Centro Tecnologico do Exercito (DQBRN/CTEx), Rio de Janeiro, RJ (Brazil). Instituto de Defesa Quimica, Biologica, Radiologica e Nuclear

2016-07-01

This paper describes the calibration laboratory deployment steps (LABCAL) gamma ionizing radiation measuring instruments in the Army Technology Center, CTEx. Initially the calibration of radiation monitors will be held in the dosimetric quantity air kerma and operational quantity ambient dose equivalent H*(d). The LABCAL / CTEx has not yet authorized by CASEC / CNEN. This laboratory aims to calibrate the ionizing radiation instruments used by the Brazilian Army. (author)

Dosimetric accuracy of Kodak EDR2 film for IMRT verifications.

Science.gov (United States)

Childress, Nathan L; Salehpour, Mohammad; Dong, Lei; Bloch, Charles; White, R Allen; Rosen, Isaac I

2005-02-01

Patient-specific intensity-modulated radiotherapy (IMRT) verifications require an accurate two-dimensional dosimeter that is not labor-intensive. We assessed the precision and reproducibility of film calibrations over time, measured the elemental composition of the film, measured the intermittency effect, and measured the dosimetric accuracy and reproducibility of calibrated Kodak EDR2 film for single-beam verifications in a solid water phantom and for full-plan verifications in a Rexolite phantom. Repeated measurements of the film sensitometric curve in a single experiment yielded overall uncertainties in dose of 2.1% local and 0.8% relative to 300 cGy. 547 film calibrations over an 18-month period, exposed to a range of doses from 0 to a maximum of 240 MU or 360 MU and using 6 MV or 18 MV energies, had optical density (OD) standard deviations that were 7%-15% of their average values. This indicates that daily film calibrations are essential when EDR2 film is used to obtain absolute dose results. An elemental analysis of EDR2 film revealed that it contains 60% as much silver and 20% as much bromine as Kodak XV2 film. EDR2 film also has an unusual 1.69:1 silver:halide molar ratio, compared with the XV2 film's 1.02:1 ratio, which may affect its chemical reactions. To test EDR2's intermittency effect, the OD generated by a single 300 MU exposure was compared to the ODs generated by exposing the film 1 MU, 2 MU, and 4 MU at a time to a total of 300 MU. An ion chamber recorded the relative dose of all intermittency measurements to account for machine output variations. Using small MU bursts to expose the film resulted in delivery times of 4 to 14 minutes and lowered the film's OD by approximately 2% for both 6 and 18 MV beams. This effect may result in EDR2 film underestimating absolute doses for patient verifications that require long delivery times. After using a calibration to convert EDR2 film's OD to dose values, film measurements agreed within 2% relative

Multi-Capacity Load Cell Concept

Directory of Open Access Journals (Sweden)

Seif. M. OSMAN

2014-09-01

Full Text Available Force measuring systems are usually used to calibrate force generated systems, it is not preferable to use load cells to measure forces less than 10 % of its nominal capacity. Several load cells are required to offer calibration facilities at sites to cover different ranges, this lead to difficulties in handling procedures, through the need for several carrying cases to carry this overweight in addition to the over cost of purchasing several load cells. This article concerns with introducing a new concept for designing a multi-capacity load cell as a new force standard in the field of measuring the force. This multi-capacity load cell will replace a set of load cells and reflects economically on the total cost and on easiness of handling procedures.

Calibration of activation detectors in a monoenergetic neutron beam. Contribution to criticality dosimetry

International Nuclear Information System (INIS)

Massoutie, Martine.

1981-05-01

Activation detectors have been calibrated for critical dosimetry applications. Measurements are made using a monoenergetic neutron flux. 14 MeV neutrons obtained par (D-T) reaction are produced by 150 kV accelerator. Neutron flux determined by different methods leads us to obtain an accuracy better than 6%. The present dosimetric system (Activation Neutron Spectrometer - SNAC) gives few informations in the (10 keV - 2 MeV) energetic range. The system has been improved and modified so that SNAC detectors must be read out by gamma spectrometer [fr

Calibrating page sized Gafchromic EBT3 films

Energy Technology Data Exchange (ETDEWEB)

Crijns, W.; Maes, F.; Heide, U. A. van der; Van den Heuvel, F. [Department of Radiation Oncology, University Hospitals Leuven, Herestraat 49, 3000 Leuven (Belgium); Department ESAT/PSI-Medical Image Computing, Medical Imaging Research Center, KU Leuven, Herestraat 49, 3000 Leuven (Belgium); Department of Radiation Oncology, The Netherlands Cancer Institute-Antoni van Leeuwenhoek Hospital, Plesmanlaan 121, 1066 CX Amsterdam (Netherlands); Department of Radiation Oncology, University Hospitals Leuven, Herestraat 49, 3000 Leuven (Belgium)

2013-01-15

balance between cost effectiveness and dosimetric accuracy. The validation resulted in dose errors of 1%-2% for the two different time points, with a maximal absolute dose error around 0.05 Gy. The lateral correction reduced the RMSE values on the sides of the film to the RMSE values at the center of the film. Conclusions: EBT3 Gafchromic films were calibrated for large field dosimetry with a limited number of page sized films and simple static calibration fields. The transmittance was modeled as a linear combination of two transmittance states, and associated with dose using a rational calibration function. Additionally, the lateral scan effect was resolved in the calibration function itself. This allows the use of page sized films. Only two calibration films were required to estimate both the dose and the lateral response. The calibration films were used over the course of a week, with residual dose errors Less-Than-Or-Slanted-Equal-To 2% or Less-Than-Or-Slanted-Equal-To 0.05 Gy.

A fast dual wavelength laser beam fluid-less optical CT scanner for radiotherapy 3D gel dosimetry II: dosimetric performance

Science.gov (United States)

Ramm, Daniel

2018-02-01

New clinical radiotherapy dosimetry systems need comprehensive demonstration of measurement quality. Practicality and reliability are other important aspects for clinical dosimeters. In this work the performance of an optical CT scanner for true 3D dosimetry is assessed using a radiochromic gel dosimeter. The fluid-less scanner utilised dual lasers to avoid the necessity for pre-irradiation scans and give greater robustness of image quality, enhancing practicality. Calibration methods using both cuvettes and reconstructed volumes were developed. Dosimetric accuracy was similar for dual and single wavelength measurements, except that cuvette calibration reliability was reduced for dual wavelength without pre-irradiation scanning. Detailed performance parameters were specified for the dosimetry system indicating the suitability for clinical use. The most significant limitations of the system were due to the gel dosimeter rather than the optical CT scanner. Quality assurance guidelines were developed to maintain dosimetry system performance in routine use.

Dosimetric characteristics of biological effect of sulfur-35

International Nuclear Information System (INIS)

Borisova, V.V.

1990-01-01

Experimental materials related to evaluation of dosimetric characteristics of sulfur-35 are presented. Hemogenic organs are subjected to greatest influence especially in the first hours after radionuclide entry into the organism. Comparison is made of absorbed doses in blood with observed blastomogen effect of hemogenic organs. It is noted, that quantitative evaluation of relative biological efficiency of low energy beta-emitters should be performed with account of dosimetric peculiarities of the nuclides mentioned above. 10 refs.; 3 tabs

Evaluation of the need for radiotherapy calibrations in the United States

International Nuclear Information System (INIS)

Lanzl, L.H.; Rozenfeld, M.; r.

1977-01-01

The custody, maintenance, and development of the United States national standards of measurement, together with the provision of calibration services related to these standards, has been assigned to the National Bureau of Standards (NBS) of the U. S. Department of Commerce. It may be that the present system of promulgation of radiation standards is no longer adequate for the United States. Ionizing radiation is being used increasingly for the treatment of cancer patients. At present, approximately 325,000 new cancer patients per year are given radiation treatment at over 1500 centers. With this growing use of ionizing radiations, an increased awareness of the importance of accurate and precise dosimetry has developed. To determine the adequacy of these dosimetric needs, the AAPM has initiated a national study which is being conducted by means of a mailed questionnaire, and by a limited number of site visits to individuals who are in charge of radiation therapy centers as well as to those who do the actual calibrations

Discussion on concepts for radiological dosimetric quantities in the Japan Health Physics Society

International Nuclear Information System (INIS)

Takahashi, Fumiaki; Oda, Keiji

2007-01-01

Many dosimetric quantities have been used for radiation protection purpose. The International Commission on Radiological Protection (ICRP) has recommended protection quantities and the International Commission on Radiation Units and Measurements (ICRU) has introduced operational quantities to provide a reasonable estimate of the protection quantities. Enthusiastic discussions are continuously made on the issues of the dosimetric quantities, such as basic biological data for the definition of these quantities and applicability of the quantities to actual radiation protection practice. At the moment, some changes are being proposed concerning dosimetric quantities in the draft recommendations of ICRP, opened for consultation in recent years. Thus, the Japan Health Physics Society (JHPS) established the Expert Committee on concepts of Dosimetric Quantities used in radiological protection (ECDQ) in April 2005 to reviewed and discuss issues in the dosimetric quantities. (author)

Calibration of working standard ionization chambers and dose standardization

International Nuclear Information System (INIS)

Abd Elmahoud, A. A. B.

2011-01-01

Measurements were performed for the calibration of two working standard ionization chambers in the secondary standard dosimetry laboratory of Sudan. 600 cc cylindrical former type and 1800 cc cylindrical radical radiation protection level ionization chambers were calibrated against 1000 cc spherical reference standard ionization chamber. The chamber were calibrated at X-ray narrow spectrum series with beam energies ranged from (33-116 KeV) in addition to 1''3''7''Cs beam with 662 KeV energy. The chambers 0.6 cc and 0.3 cc therapy level ionization were used for dose standardization and beam output calibrations of cobalt-60 radiotherapy machine located at the National Cancer Institute, University of Gazira. Concerning beam output measurements for 6''0''Co radiotherapy machine, dosimetric measurements were performed in accordance with the relevant per IAEA dosimetry protocols TRS-277 and TRS-398. The kinetic energy released per unit mass in air (air kerma) were obtained by multiplying the corrected electrometer reading (nC/min) by the calibration factors (Gy/n C) of the chambers from given in the calibration certificate. The uncertainty of measurements of air kerma were calculated for the all ionization chambers (combined uncertainty) the calibration factors of these ionization chambers then were calculated by comparing the reading of air kerma of secondary standard ionization chambers to than from radical and farmer chambers. The result of calibration working standard ionization chambers showed different calibration factors ranged from 0.99 to 1.52 for different radiation energies and these differences were due to chambers response and specification. The absorbed dose to to water calculated for therapy ionization chamber using two code of practice TRS-277 and TRS-398 as beam output for 6''0''Co radiotherapy machine and it can be used as a reference for future beam output calibration in radiotherapy dosimetry. The measurement of absorbed dose to water showed that the

Study of a new dosimetric radio-thermoluminescent systems

International Nuclear Information System (INIS)

Cazac, T.C.

1980-01-01

This is the first Romanian study to investigate conditions to obtain the radio-thermo-luminescent systems: MgB 4 O 7 :A(A-Nd,Sm,Eu,Dy,Tb,Dy+Sm and Tb+Sm) MgF 2 A (A=Mn,Dy,Tb,Sm,Li), their essential dosimetric characters, as well as the (MgF 2 =Mn) thermophosphorus mixture with a ( 6 LiF) lithium target. An investigation was developed upon a new category of radio-thermoluminescent detectors with low radiation energy dependence and fading, magnesjum boride activated by several elements of the lanthanides class (Nd,Sm,Eu,Dy,Tb). A new radio-thermoluminescent dosimetric system with high sensitivity and moderate dependence on energy radiation - (Mnsup(2+)) manganese activated magnesium fluoride - was also studied. The author explored application of investigated detectors MgF 2 =Mn, MgB 4 O 7 =Dy and MgB 4 O 7 :Tb in neutron dosimetry in complex gamma-neutron fields. It is deemed that by using the dosimetric systems reported in the thesis in order to measure gamma, beta and neutron radiation doses, dosimetric control can be ensured both in professional dosimetry and in nuclear accident dosimetry, as well as in various basic and applicative investigations. A modest contribution is thus made towards achieving the national nuclear program through an extension of the thermophosphorus range with practical applications in nuclear radiation dosimetry. (author)

Prevention of transfusion-associated graft-versus-host disease by irradiation: technical aspect of a new ferrous sulphate dosimetric system.

Directory of Open Access Journals (Sweden)

Lucas Sacchini Del Lama

Full Text Available Irradiation of whole blood and blood components before transfusion is currently the only accepted method to prevent Transfusion-Associated Graft-Versus-Host-Disease (TA-GVHD. However, choosing the appropriate technique to determine the dosimetric parameters associated with blood irradiation remains an issue. We propose a dosimetric system based on the standard Fricke Xylenol Gel (FXG dosimeter and an appropriate phantom. The modified dosimeter was previously calibrated using a (60Co teletherapy unit and its validation was accomplished with a (137Cs blood irradiator. An ionization chamber, standard FXG, radiochromic film and thermoluminescent dosimeters (TLDs were used as reference dosimeters to determine the dose response and dose rate of the (60Co unit. The dose distributions in a blood irradiator were determined with the modified FXG, the radiochromic film, and measurements by TLD dosimeters. A linear response for absorbed doses up to 54 Gy was obtained with our system. Additionally, the dose rate uncertainties carried out with gel dosimetry were lower than 5% and differences lower than 4% were noted when the absorbed dose responses were compared with ionization chamber, film and TLDs.

Prevention of Transfusion-Associated Graft-versus-Host Disease by Irradiation: Technical Aspect of a New Ferrous Sulphate Dosimetric System

Science.gov (United States)

Del Lama, Lucas Sacchini; de Góes, Evamberto Garcia; Petchevist, Paulo César Dias; Moretto, Edson Lara; Borges, José Carlos; Covas, Dimas Tadeu; de Almeida, Adelaide

2013-01-01

Irradiation of whole blood and blood components before transfusion is currently the only accepted method to prevent Transfusion-Associated Graft-Versus-Host-Disease (TA-GVHD). However, choosing the appropriate technique to determine the dosimetric parameters associated with blood irradiation remains an issue. We propose a dosimetric system based on the standard Fricke Xylenol Gel (FXG) dosimeter and an appropriate phantom. The modified dosimeter was previously calibrated using a 60Co teletherapy unit and its validation was accomplished with a 137Cs blood irradiator. An ionization chamber, standard FXG, radiochromic film and thermoluminescent dosimeters (TLDs) were used as reference dosimeters to determine the dose response and dose rate of the 60Co unit. The dose distributions in a blood irradiator were determined with the modified FXG, the radiochromic film, and measurements by TLD dosimeters. A linear response for absorbed doses up to 54 Gy was obtained with our system. Additionally, the dose rate uncertainties carried out with gel dosimetry were lower than 5% and differences lower than 4% were noted when the absorbed dose responses were compared with ionization chamber, film and TLDs. PMID:23762345

Dosimetric effects of edema in permanent prostate seed implants: a rigorous solution

International Nuclear Information System (INIS)

Chen Zhe; Yue Ning; Wang Xiaohong; Roberts, Kenneth B.; Peschel, Richard; Nath, Ravinder

2000-01-01

Purpose: To derive a rigorous analytic solution to the dosimetric effects of prostate edema so that its impact on the conventional pre-implant and post-implant dosimetry can be studied for any given radioactive isotope and edema characteristics. Methods and Materials: The edema characteristics observed by Waterman et al (Int. J. Rad. Onc. Biol. Phys, 41:1069-1077; 1998) was used to model the time evolution of the prostate and the seed locations. The total dose to any part of prostate tissue from a seed implant was calculated analytically by parameterizing the dose fall-off from a radioactive seed as a single inverse power function of distance, with proper account of the edema-induced time evolution. The dosimetric impact of prostate edema was determined by comparing the dose calculated with full consideration of prostate edema to that calculated with the conventional dosimetry approach where the seed locations and the target volume are assumed to be stationary. Results: A rigorous analytic solution on the relative dosimetric effects of prostate edema was obtained. This solution proved explicitly that the relative dosimetric effects of edema, as found in the previous numerical studies by Yue et. al. (Int. J. Radiat. Oncol. Biol. Phys. 43, 447-454, 1999), are independent of the size and the shape of the implant target volume and are independent of the number and the locations of the seeds implanted. It also showed that the magnitude of relative dosimetric effects is independent of the location of dose evaluation point within the edematous target volume. It implies that the relative dosimetric effects of prostate edema are universal with respect to a given isotope and edema characteristic. A set of master tables for the relative dosimetric effects of edema were obtained for a wide range of edema characteristics for both 125 I and 103 Pd prostate seed implants. Conclusions: A rigorous analytic solution of the relative dosimetric effects of prostate edema has been

X radiation qualities characterization following the standard IEC 61267 recommendations at the calibration laboratory of IPEN

International Nuclear Information System (INIS)

Franciscatto, Priscila Cerutti

2009-01-01

This work presents a methodology for the X radiation qualities characterization following the new recommendations of the standard 61267 of the International Electrotechnical Commission (IEC) to establish a new procedure for calibration of dosimetric systems used in the field of diagnostic radiology. The reference qualities radiation of IEC 61267: RQR 2 to RQR 10, RQA 2 to RQA 10, RQB 2 to RQB 10 and RQN 2 to RQN 10 were implanted at the calibration laboratory of IPEN (LCI). Their characteristics were analyzed through measurements of beam parameters such as: Practical peak voltage (PPV), specific additional filtrations for each qualities (high purity aluminum of about 99.9%), 1st and 2nd Half Value Layers, homogeneity coefficient. The inherent filtration of the X ray tube was also determined. With the establishment of these radiation qualities, the LCI will be ready to calibrate the measuring instruments of radiation in the new qualities, allowing an improvement in radiological services offered by IPEN. (author)

Gamma dosimetric parameters in some skeletal muscle relaxants

Science.gov (United States)

Manjunatha, H. C.

2017-09-01

We have studied the attenuation of gamma radiation of energy ranging from 84 keV to 1330 keV (^{170}Tm, ^{22}Na,^{137}Cs, and ^{60}Co) in some commonly used skeletal muscle relaxants such as tubocurarine chloride, gallamine triethiodide, pancuronium bromide, suxamethonium bromide and mephenesin. The mass attenuation coefficient is measured from the attenuation experiment. In the present work, we have also proposed the direct relation between mass attenuation coefficient (μ /ρ ) and mass energy absorption coefficient (μ _{en}/ρ ) based on the nonlinear fitting procedure. The gamma dosimetric parameters such as mass energy absorption coefficient (μ _{en}/ρ ), effective atomic number (Z_{eff}), effective electron density (N_{el}), specific γ-ray constant, air kerma strength and dose rate are evaluated from the measured mass attentuation coefficient. These measured gamma dosimetric parameters are compared with the theoretical values. The measured values agree with the theoretical values. The studied gamma dosimetric values for the relaxants are useful in medical physics and radiation medicine.

Vessel calibration for accurate material accountancy at RRP

International Nuclear Information System (INIS)

Yanagisawa, Yuu; Ono, Sawako; Iwamoto, Tomonori

2004-01-01

RRP has a 800t·Upr capacity a year to re-process, where would be handled a large amount of nuclear materials as solution. A large scale plant like RRP will require accurate materials accountancy system, so that the vessel calibration with high-precision is very important as initial vessel calibration before operation. In order to obtain the calibration curve, it is needed well-known each the increment volume related with liquid height. Then we performed at least 2 or 3 times run with water for vessel calibration and careful evaluation for the calibration data should be needed. We performed vessel calibration overall 210 vessels, and the calibration of 81 vessels including IAT and OAT were held under presence of JSGO and IAEA inspectors taking into account importance on the material accountancy. This paper describes outline of the initial vessel calibration and calibration results based on back pressure measurement with dip tubes. (author)

Characterization of responses and comparison of calibration factor for commercial MOSFET detectors.

Science.gov (United States)

Bharanidharan, Ganesan; Manigandan, Durai; Devan, Krishnamurthy; Subramani, Vellaiyan; Gopishankar, Natanasabapathi; Ganesh, Tharmar; Joshi, Rakeshchander; Rath, Gourakishore; Velmurugan, Jagadeesan; Aruna, Prakasarao; Ganesan, Singaravelu

2005-01-01

A commercial metal oxide silicon field effect transistor (MOSFET) dosimeter of model TN502-RD has been characterized for its linearity, reproducibility, field size dependency, dose rate dependency, and angular dependency for Cobalt-60 (60Co), 6-MV, and 15-MV beam energies. The performance of the MOSFET clearly shows that it is highly reproducible, independent of field size and dose rate. Furthermore, MOSFET has a very high degree of linearity, with r-value>0.9 for all 3 energies. The calibration factor for 2 similar MOSFET detectors of model TN502-RD were also estimated and compared for all 3 energies. The calibration factor between the 2 similar MOSFET detectors shows a variation of about 1.8% for 60Co and 15 MV, and for 6 MV it shows variation of about 2.5%, indicating that calibration should be done whenever a new MOSFET is used. However, the detector shows considerable angular dependency of about 8.8% variation. This may be due to the variation in radiation sensitivity between flat and bubble sides of the MOSFET, and indicates that positional care must be taken while using MOSFET for stereotactic radiosurgery and stereotactic radiotherapy dosimetric applications.

Secondary calibration laboratory for dosimetry in levels of therapy at the University of Santiago

International Nuclear Information System (INIS)

Gomez Rodriguez, F.; Gonzalez Castano, D. M.; Pazos Alvarez, A.

2011-01-01

A basic inherent benefits provided by the existence of a traceability chain radiation in any application, add the legal requirement for hospitals as pointed to by the RO. 1566/1998, which sets quality standards in radiotherapy. The decree attributed to hospital specialists radio physics in article 10 the responsibility for determining the acceptance and initial reference state of radiation generating equipment for therapeutic purposes, and the establishment and implementation of quality control programs associated and technical and physical aspects of radiation dosimetry. Different international organizations such as ICRU and IAEA recommendations on maintaining the accuracy of the dose delivered to patients in general, should be placed at least 5% considering the whole chain irradiation. In order to achieve this purpose it is necessary to establish programs of quality control and calibration dosimetric regular basis. The protocol of the IAEA TRS398 recommended dose calibration in water because it is a quantity of interest closest to clinical use and allows a relative uncertainty in the calibration environment reduced to 1%.. (Author)

Characterization of TLD-100 in powders for dosimetric quality control of 192 Ir sources used in brachytherapy of high dose rate

International Nuclear Information System (INIS)

Loaiza C, S.P.

2007-01-01

The Secondary Standard Dosimetric at the National Institute of Nuclear Research (ININ) calibrated a lot of powdered TLD-100 (LiF:Mg,Ti) in terms of absorbed dose to water D w for the energy of: 60 Co, 137C s, X rays of 250 and 50 kVp. Later on, it is carried out an interpolation of the calibration for the energy of the 192 Ir. This calibration is part of a dosimetric quality control program, to solve the problems of traceability for the measurements carried out by the users of 192 Ir sources employed in the treatments of High Dose Rate Brachytherapy (HDR) at the Mexican Republic. The calibrations of the radiation beams are made with the following protocols: IAEA TRS-398 for the 60 Co for D w , using a secondary standard ionization chamber PTW N30013 calibrated in D w by the National Research Council (NRC, Canada). AAPM TG-43 for D w in terms of the strength kerma Sk, calibrating this last one quantity for the 137 Cs radioactive source, with a well chamber HDR 1000 PLUS traceable to the University of Wisconsin (US). AAPM TG-61 for X ray of 250 and 50 kVp for D w start to Ka using field standard a Farmer chamber PTW 30001 traceable to K for the Central Laboratory of Electric Industries (CLEI, France). The calibration curves (CC) they built for the response of the powder TLD: R TLD vs D w : For the energy of 60 Co, 137 Cs, X rays of 250 and 50 kVp. Fitting them with the least square method weighed by means of a polynomial of second grade that corrects the supra linearity of the response. iii. Each one of the curves was validated with a test by lack of fitting and for the Anderson Darling normality test, using the software MINITAB in both cases. iv. The sensibility factor (F s ) for each energy corresponds to the slope of the CC, v. The F s for the two 192 Ir sources used are interpolated: one for a Micro Selectron source and the other one a Vari Source source. Finally, a couple of capsules were sent to two hospitals that have the HDR Brachytherapy with sources of 192

Automation of dosimeters calibration for radiotherapy in secondary dosimetric calibration laboratory of the CPHR; Automatizacion de la calibracion de dosimetros de radioterapia en el laboratorio secundario de calibracion dosimetrica del CPHR

Energy Technology Data Exchange (ETDEWEB)

Acosta, Andy L. Romero; Lores, Stefan Gutierrez, E-mail: c19btm@frcuba.co.cu [Centro de Proteccion e Higiene de las Radiaciones (CPHR), La Habana (Cuba)

2013-11-01

This paper presents the design and implementation of an automated system for measurements in the calibration of reference radiation dosimeters. It was made a software application that performs the acquisition of the measured values of electric charge, calculated calibration coefficient and automates the calibration certificate issuance. These values are stored in a log file on a PC. The use of the application improves control over the calibration process, helps to humanize the work and reduces personnel exposure. The tool developed has been applied to the calibration of dosimeters radiation patterns in the LSCD of the Centro de Proteccion e Higiene de las Radiaciones, Cuba.

Computerized tomography in Community of Madrid. Reference dosimetric measurements

International Nuclear Information System (INIS)

Ruiz Sanz, S.; Calzado, A.; Melchor, M.; Marco, M.

1994-01-01

A total of about 43 computed tomography scanners were operating in the Autonomous Community of Madrid during 1991. A sample of 14 facilities was selected to perform dosimetric measurements in order to obtain characteristic dose profiles. From these, some quantities as the computed tomography dose index and the enhancement factor were calculated and analysed for the most common technique settings. Relations were established between the dosimetric results and technical characteristics of the scanners. (Author)

First approval procedure of the TL dosimetric service of the NPP in Slovenia

International Nuclear Information System (INIS)

Janzekovic, H.; Krizman, M.; Pucelj, B.; Stuhec, M.; Zdesar, U.

2001-01-01

The individual dosimetry of exposed workers in a NPP is one of the essential parts which demonstrates the radiation protection standards achieved in a facility. According to the current legislation the Ministry of Health of the Republic of Slovenia has the authority to grant approvals to personal dosimetric services which perform the dosimetric monitoring of workers in Slovenia. Due to the fact that the detailed approval procedure is not given in national regulations, the Ministry of Health in 2000 established a group of experts with the task to prepare technical and organising requirements for such approval. Based on international documents [1,2,3] the Approval procedure for the thermoluminescence dosimetric (TL) services was created. Following this procedure the assessment of the TL dosimetric service in the NPP was performed. The problems related to the technical and organising requirements with the emphasise on the QA/QC criteria of the TL dosimetric service will be discussed.(author)

Conception of CTMSP ionizing radiation calibration laboratory

International Nuclear Information System (INIS)

Silva, Raimundo Dias da; Kibrit, Eduardo

2009-01-01

The present paper describes the implantation process of an ionizing radiation calibration laboratory in a preexistent installation in CTMSP (bunker) approved by CNEN to operate with gamma-ray for non destructive testing. This laboratory will extend and improve the current metrological capacity for the attendance to the increasing demand for services of calibration of ionizing radiation measuring instruments. Statutory and regulatory requirements for the licensing of the installation are presented and deeply reviewed. (author)

SU-E-T-123: Dosimetric Comparison Between Portrait and Landscape Orientations in Radiochromic Film Dosimetry

International Nuclear Information System (INIS)

Kakinohana, Y; Toita, T; Kasuya, G; Ariga, T; Heianna, J; Murayama, S

2014-01-01

Purpose: To compare the dosimetric properties of radiochromic films with different orientation. Methods: A sheet of EBT3 film was cut into eight pieces with the following sizes: 15×15 cm2 (one piece), 5x15 cm 2 (two) and 4×5 cm 2 (five). A set of two EBT3 sheets was used at each dose level. Two sets were used changing the delivered doses (1 and 2 Gy). The 5×15 cm 2 pieces were rotated by 90 degrees in relation to each other, such that one had landscape orientation and the other had portrait orientation. All 5×15 cm2 pieces were irradiated with their long side aligned with the x-axis of the radiation field. The 15×15 cm 2 pieces were irradiated rotated at 90 degrees to each other. Five pieces, (a total of ten from two sheets) were used to obtain a calibration curve. The irradiated films were scanned using an Epson ES-2200 scanner and were analyzed using ImageJ software. In this study, no correction was applied for the nonuniform scanner signal that is evident in the direction of the scanner lamp. Each film piece was scanned both in portrait and landscape orientations. Dosimetric comparisons of the beam profiles were made in terms of the film orientations (portrait and landscape) and scanner bed directions (perpendicular and parallel to the scanner movement). Results: In general, portrait orientation exhibited higher noise than landscape and was adversely affected to a great extent by the nonuniformity in the direction of the scanner lamp. A significant difference in the measured field widths between the perpendicular and parallel directions was found for both orientations. Conclusion: Without correction for the nonuniform scanner signal in the direction of the scanner lamp, a landscape orientation is preferable. A more detailed investigation is planned to evaluate quantitatively the effect of orientation on the dosimetric properties of a film

SU-E-T-123: Dosimetric Comparison Between Portrait and Landscape Orientations in Radiochromic Film Dosimetry

Energy Technology Data Exchange (ETDEWEB)

Kakinohana, Y [University of the Ryukyus, Okinawa (Japan); Toita, T; Kasuya, G; Ariga, T; Heianna, J; Murayama, S [University of the Ryukyus, Nishihara-cho, Okinawa (Japan)

2014-06-01

Purpose: To compare the dosimetric properties of radiochromic films with different orientation. Methods: A sheet of EBT3 film was cut into eight pieces with the following sizes: 15×15 cm2 (one piece), 5x15 cm{sup 2} (two) and 4×5 cm{sup 2} (five). A set of two EBT3 sheets was used at each dose level. Two sets were used changing the delivered doses (1 and 2 Gy). The 5×15 cm{sup 2} pieces were rotated by 90 degrees in relation to each other, such that one had landscape orientation and the other had portrait orientation. All 5×15 cm2 pieces were irradiated with their long side aligned with the x-axis of the radiation field. The 15×15 cm{sup 2} pieces were irradiated rotated at 90 degrees to each other. Five pieces, (a total of ten from two sheets) were used to obtain a calibration curve. The irradiated films were scanned using an Epson ES-2200 scanner and were analyzed using ImageJ software. In this study, no correction was applied for the nonuniform scanner signal that is evident in the direction of the scanner lamp. Each film piece was scanned both in portrait and landscape orientations. Dosimetric comparisons of the beam profiles were made in terms of the film orientations (portrait and landscape) and scanner bed directions (perpendicular and parallel to the scanner movement). Results: In general, portrait orientation exhibited higher noise than landscape and was adversely affected to a great extent by the nonuniformity in the direction of the scanner lamp. A significant difference in the measured field widths between the perpendicular and parallel directions was found for both orientations. Conclusion: Without correction for the nonuniform scanner signal in the direction of the scanner lamp, a landscape orientation is preferable. A more detailed investigation is planned to evaluate quantitatively the effect of orientation on the dosimetric properties of a film.

Comparison of dosimetric methods for virtual wedge analysis

International Nuclear Information System (INIS)

Bailey, M.; Nelson, V.; Collins, O.; West, M.; Holloway, L.; Rajapaske, S.; Arts, J.; Varas, J.; Cho, G.; Hill, R.

2004-01-01

Full text: The Siemens Virtual Wedge (Concord, USA) creates wedged beam profile by moving a single collimator jaw across the specified field size whilst varying the dose rate and jaw speed for use in the delivery of radiotherapy treatments. The measurement of the dosimetric characteristics of the Siemens Virtual Wedge poses significant challenges to medical physicists. This study investigates several different methods for measuring and analysing the virtual wedge for data collection for treatment planning systems and ongoing quality assurance. The beam profiles of the Virtual Wedge (VW) were compared using several different dosimetric methods. Open field profiles were measured with Kodak X-Omat V (Rochester, NY, USA) radiographic film and compared with measurements made using the Sun Nuclear Profiler with a Motorized Drive Assembly (MDA) (Melbourne, FL, USA) and the Scanditronix Wellhofer CC13 ionisation chamber and 24 ion Chamber Array (CA24) (Schwarzenbruck, Germany). The resolution of each dosimetric method for open field profiles was determined. The Virtual Wedge profiles were measured with radiographic film the Profiler and the Scanditronix Wellhofer CA 24 ion Chamber Array at 5 different depths. The ease of setup, time taken, analysis and accuracy of measurement were all evaluated to determine the method that would be both appropriate and practical for routine quality assurance of the Virtual Wedge. The open field profiles agreed within ±2% or 2mm for all dosimetric methods. The accuracy of the Profiler and CA24 are limited to half of the step size selected for each of these detectors. For the VW measurements a step size of 2mm was selected for the Profiler and the CA24. The VW profiles for all dosimetric methods agreed within ±2% or 2mm for the main wedged section of the profile. The toe and heel ends of the wedges showed the significant discrepancies dependent upon the dosimetry method used, up to 7% for the toe end with the CA24. The dosimetry of the

A comparison of the quality assurance of four dosimetric tools for intensity modulated radiation therapy

International Nuclear Information System (INIS)

Son, Jaeman; Baek, Taesung; Lee, Boram; Shin, Dongho; Park, Sung Yong; Park, Jeonghoon; Lim, Young Kyung; Lee, Se Byeong; Kim, Jooyoung; Yoon, Myonggeun

2015-01-01

This study was designed to compare the quality assurance (QA) results of four dosimetric tools used for intensity modulated radiation therapy (IMRT) and to suggest universal criteria for the passing rate in QA, irrespective of the dosimetric tool used. Thirty fields of IMRT plans from five patients were selected, followed by irradiation onto radiochromic film, a diode array (Mapcheck), an ion chamber array (MatriXX) and an electronic portal imaging device (EPID) for patient-specific QA. The measured doses from the four dosimetric tools were compared with the dose calculated by the treatment planning system. The passing rates of the four dosimetric tools were calculated using the gamma index method, using as criteria a dose difference of 3% and a distance-to-agreement of 3 mm. The QA results based on Mapcheck, MatriXX and EPID showed good agreement, with average passing rates of 99.61%, 99.04% and 99.29%, respectively. However, the average passing rate based on film measurement was significantly lower, 95.88%. The average uncertainty (1 standard deviation) of passing rates for 6 intensity modulated fields was around 0.31 for film measurement, larger than those of the other three dosimetric tools. QA results and consistencies depend on the choice of dosimetric tool. Universal passing rates should depend on the normalization or inter-comparisons of dosimetric tools if more than one dosimetric tool is used for patient specific QA

A comparison of the quality assurance of four dosimetric tools for intensity modulated radiation therapy.

Science.gov (United States)

Son, Jaeman; Baek, Taesung; Lee, Boram; Shin, Dongho; Park, Sung Yong; Park, Jeonghoon; Lim, Young Kyung; Lee, Se Byeong; Kim, Jooyoung; Yoon, Myonggeun

2015-09-01

This study was designed to compare the quality assurance (QA) results of four dosimetric tools used for intensity modulated radiation therapy (IMRT) and to suggest universal criteria for the passing rate in QA, irrespective of the dosimetric tool used. Thirty fields of IMRT plans from five patients were selected, followed by irradiation onto radiochromic film, a diode array (Mapcheck), an ion chamber array (MatriXX) and an electronic portal imaging device (EPID) for patient-specific QA. The measured doses from the four dosimetric tools were compared with the dose calculated by the treatment planning system. The passing rates of the four dosimetric tools were calculated using the gamma index method, using as criteria a dose difference of 3% and a distance-to-agreement of 3 mm. The QA results based on Mapcheck, MatriXX and EPID showed good agreement, with average passing rates of 99.61%, 99.04% and 99.29%, respectively. However, the average passing rate based on film measurement was significantly lower, 95.88%. The average uncertainty (1 standard deviation) of passing rates for 6 intensity modulated fields was around 0.31 for film measurement, larger than those of the other three dosimetric tools. QA results and consistencies depend on the choice of dosimetric tool. Universal passing rates should depend on the normalization or inter-comparisons of dosimetric tools if more than one dosimetric tool is used for patient specific QA.

Some dosimetric properties of the LiF:Mg,Ti evaluated by the automatic 6600 thermoluminescent reader

Energy Technology Data Exchange (ETDEWEB)

Ben-Shachar, B; Weinstein, M; German, U [Israel Atomic Energy Commission, Beersheba (Israel). Nuclear Research Center-Negev

1996-12-01

Some dosimetric properties of the new LiF:Mg,Ti TLD cards were checked, when evaluated by the new automatic 6600 TLD reader. The cards were calibrated to a dose of 1.0 mGy by five identical irradiations, and the TL-dose response was measured for a range of 75 - 1100 mGy. A very high accuracy was found for the three kind of chips measured (TLD-100, TLD-700 and TLD-600) and a low minimum measurable dose (MMD) was found, too. There is a good fit between the analytical evaluation and the theoretical calculation of the MMD. The results obtained are much better than those of the LiF:Mg,Ti cards evaluated by the older automatic 2271 reader used in the last two decades (authors).

Dosimetric monitoring at time of Chernobyl clean-up. A retrospective view

International Nuclear Information System (INIS)

Chumak, V.V.; Bakhanova, E.V.; Musijachenko, N.V.; Krjuchkov, V.P.

2000-01-01

Although at time of the accident many thousands of individuals were subjected to personal dosimetric monitoring, a status of dosimetric support of clean-up activities performed in 1986-1987 remains one of the most uncertain radiological issues related to Chernobyl accident. It is known that the scope, practical coverage and methodologies of dosimetry at time of the accident significantly varied. Unfortunately, the dose records available now in a number registries and databases are lacking direct indications of the methods of dosimetry, locations of work and tasks performed by liquidators. Moreover, data record linkage in many cases is problematic due to lack of unique identifiers in the databases of concern. However, this information, collected in course of dosimetric monitoring is extremely valuable for epidemiological consideration of this cohort and, therefore, cannot be neglected because of problems with strait forward application of this data. Retrospective consideration of dosimetric monitoring data was conducted along several lines. First, data sets (in some cases impersonal), related to the known dosimetric practices were studied in order to determine regularities in their dose distributions, evaluate possible distortions caused by extraneous admixtures to dose arrays and evaluate possible contribution of falsified dose records. Another effort was directed towards individualization of information regarding affiliation and tasks of the liquidators included into the State Chernobyl Registry (SCR), which is, essentially, the main pool of subjects for observation in the framework of post Chernobyl epidemiological studies. The SCR in its original shape was missing this crucial information. In order to recover this information gap, a wide scale postal survey of liquidators was undertaken. Those persons who are included into the State Chernobyl Registry and have official dose records were asked to respond to a simple five-entry questionnaire, dealing with their

Research on Overconfidence in Decision-Making for the Capacity Recovery of Damaged Power Systems

Directory of Open Access Journals (Sweden)

Xing Bao

2014-01-01

Full Text Available This paper studies the influence of two types of overconfident behavior, overestimation and overprecision, on decision of capacity recovery when power system’s critical capacity is seriously damaged. A newsvendor model is used to prove that increasing regulatory punishment for electricity shortage and providing subsidy for capacity recovery are conducive measures to calibrate insufficient service level caused by an overconfident manager. The research also finds that the manager’s overprecision behavior both negatively and positively influences the decision of capacity recovery, and a calibration method could motivate manager to recover more capacity by tuning up the ratio of punishment and subsidy. However, the effectiveness of the calibration mentioned above is inevitably weakened due to the less capacity recovery given by an overestimated manager. This research also indicates that the manager should pay close attention to the random disturbance whose distribution peak is left skewed, and correspondingly more capacity recovery should be given to improve the service level of power system during the disruption.

Transport and dosimetric solutions for the ELIMED laser-driven beam line

Energy Technology Data Exchange (ETDEWEB)

Cirrone, G.A.P. [INFN-LNS, Via S. Sofia 62 - 95125 Catania (Italy); Romano, F. [INFN-LNS, Via S. Sofia 62 - 95125 Catania (Italy); Medical Physics School, University of Catania, Via S. Sofia 64 - 95125 Catania (Italy); Scuderi, V. [INFN-LNS, Via S. Sofia 62 - 95125 Catania (Italy); Institute of Physics ASCR, v.v.i. (FZU), ELI-Beamlines Project, Na Slovance 2, 182 21 Prague (Czech Republic); Amato, A. [INFN-LNS, Via S. Sofia 62 - 95125 Catania (Italy); Candiano, G. [INFN-LNS, Via S. Sofia 62 - 95125 Catania (Italy); Medical Physics School, University of Catania, Via S. Sofia 64 - 95125 Catania (Italy); Cuttone, G. [INFN-LNS, Via S. Sofia 62 - 95125 Catania (Italy); Giove, D. [INFN Sezione di Milano, Via Celoria 16, Milano (Italy); Korn, G.; Krasa, J. [Institute of Physics ASCR, v.v.i. (FZU), ELI-Beamlines Project, Na Slovance 2, 182 21 Prague (Czech Republic); Leanza, R. [INFN-LNS, Via S. Sofia 62 - 95125 Catania (Italy); Universitá degli Studi di Catania, Dipartimento di Fisica e Astronomia, Via S. Sofia 64, Catania (Italy); Manna, R. [INFN-LNS, Via S. Sofia 62 - 95125 Catania (Italy); Maggiore, M. [INFN-LNL, Viale dell' Universitá 2 - 35020 Legnaro (PD) (Italy); Marchese, V. [INFN-LNS, Via S. Sofia 62 - 95125 Catania (Italy); Margarone, D. [Institute of Physics ASCR, v.v.i. (FZU), ELI-Beamlines Project, Na Slovance 2, 182 21 Prague (Czech Republic); Milluzzo, G. [INFN-LNS, Via S. Sofia 62 - 95125 Catania (Italy); Universitá degli Studi di Catania, Dipartimento di Fisica e Astronomia, Via S. Sofia 64, Catania (Italy); Petringa, G. [INFN-LNS, Via S. Sofia 62 - 95125 Catania (Italy); Sabini, M.G. [INFN-LNS, Via S. Sofia 62 - 95125 Catania (Italy); Azienda Ospedaliera Cannizzaro, Via Messina 829 - 95100 Catania (Italy); Schillaci, F. [INFN-LNS, Via S. Sofia 62 - 95125 Catania (Italy); Medical Physics School, University of Catania, Via S. Sofia 64 - 95125 Catania (Italy); and others

2015-10-01

Within 2017, the ELIMED (ELI-Beamlines MEDical applications) transport beam-line and dosimetric systems for laser-generated beams will be installed at the ELI-Beamlines facility in Prague (CZ), inside the ELIMAIA (ELI Multidisciplinary Applications of laser–Ion Acceleration) interaction room. The beam-line will be composed of two sections: one in vacuum, devoted to the collecting, focusing and energy selection of the primary beam and the second in air, where the ELIMED beam-line dosimetric devices will be located. This paper briefly describes the transport solutions that will be adopted together with the main dosimetric approaches. In particular, the description of an innovative Faraday Cup detector with its preliminary experimental tests will be reported.

Improvements in critical dosimetric endpoints using the Contura multilumen balloon breast brachytherapy catheter to deliver accelerated partial breast irradiation: preliminary dosimetric findings of a phase iv trial.

Science.gov (United States)

Arthur, Douglas W; Vicini, Frank A; Todor, Dorin A; Julian, Thomas B; Lyden, Maureen R

2011-01-01

Dosimetric findings in patients treated with the Contura multilumen balloon (MLB) breast brachytherapy catheter to deliver accelerated partial breast irradiation (APBI) on a multi-institutional Phase IV registry trial are presented. Computed tomography-based three-dimensional planning with dose optimization was performed. For the trial, new ideal dosimetric goals included (1) ≥95% of the prescribed dose (PD) covering ≥90% of the target volume, (2) a maximum skin dose ≤125% of the PD, (3) maximum rib dose ≤145% of the PD, and (4) the V150 ≤50 cc and V200 ≤10 cc. The ability to concurrently achieve these dosimetric goals using the Contura MLB was analyzed. 144 cases were available for review. Using the MLB, all dosimetric criteria were met in 76% of cases. Evaluating dosimetric criteria individually, 92% and 89% of cases met skin and rib dose criteria, respectively. In 93% of cases, ideal target volume coverage goals were met, and in 99%, dose homogeneity criteria (V150 and V200) were satisfied. When skin thickness was ≥5 mm to <7 mm, the median skin dose was limited to 120.1% of the PD, and when skin thickness was <5 mm, the median skin dose was 124.2%. When rib distance was <5 mm, median rib dose was reduced to 136.5% of the PD. When skin thickness was <7 mm and distance to rib was <5 mm, median skin and rib doses were jointly limited to 120.6% and 142.1% of the PD, respectively. The Contura MLB catheter provided the means of achieving the imposed higher standard of dosimetric goals in the majority of clinical scenarios encountered. Copyright © 2011 Elsevier Inc. All rights reserved.

Studies on dosimetric tests applying source irradiation force of Cs-137 for using in chambers for calibration and TLD type dosimeters

International Nuclear Information System (INIS)

Ribeiro, Laila Lorena X.; Barbosa, Rugles Cesar; Correa, Rosangela S.

2011-01-01

The West Central region of Brazil does not have a basic infrastructure for research, development, training programs, and personnel dosimetry education. All of them applied to environmental, industrial and medical uses. Service deployment for irradiance of TLD, via 137 Cs irradiator J. L. SHEPHERD model 28-8A (444 activity GBq) in CRCN-CO, it is necessary to introduce procedures for calibration of the radiator and other procedures related to dosimetry and calibration. Such procedures should be repeated periodically, as necessary to introduce techniques that make the service of the CRCN-CO a template, and that meet all standards requirements for radioprotection and operation of dosimetry and calibration. The objective of this work was to evaluate the radiation field of Cs-137, and the automatic system which systematizes the calibration procedures attached to a system control target for the radiator/calibration of monitors, and portable dosimeters. (author)

Personal dosimetric monitoring in Ukraine: current status and further development

International Nuclear Information System (INIS)

Chumak, V. V.; Musijachenkom, A. V.; Boguslavskaya, A. I.

2003-01-01

Presently Ukraine has mixed system for dosimetric monitoring. Nuclear power plants and some major nuclear facilities have their own dosimetry services, which are responsible for regular dosimetric monitoring of workers. Rest of occupationally exposed persons is monitored by dosimetry laboratories affiliated to the territorial authorities for sanitary and epidemiology supervision. In 2002-2003 Ukrainian Ministry of Health performed survey of the status of dosimetric monitoring and inventory of critical groups requiring such monitoring. Dosimetry services in Ukraine cover about 38,000 occupationally exposed workers, including 9,100 medical professionals, 16,400 employees of 5 nuclear power plants and ca.12,400 workers dealing with other sources of occupational exposure (industry, research). Territorial dosimetry services operate in 13 of 24 regions of Ukraine, using DTU-01 manual TLD readers produced with one exception in 1988-1990. The coverage of critical groups by dosimetric monitoring is variable and ranges from 38% to 100% depending on the region. Personnel of nuclear power plants (about 16,400 workers) is monitored by their own dosimetry services achieving absolute coverage of the main staff and temporary workers. Current inadequate status of dosimetric monitoring infrastructure in Ukraine demands an urgent elaboration of the united state system for monitoring and recording of individual doses. The proposed plan would allows to bring dosimetry infrastructure in Ukraine to the modern state which would be compatible with existing and future European and international radiation protection networks. Unitary structure of Ukraine, strong administrative command and good communications between regions of the country are positive factors in favour of efficient implementation of the proposed plan. Deficiencies are associated with limited funding of this effort. (authors)

The use of a virtual reality simulator to explore and understand the impact of Linac mis-calibrations

Science.gov (United States)

Beavis, Andrew W.; Ward, James W.

2014-03-01

Purpose: In recent years there has been interest in using Computer Simulation within Medical training. The VERT (Virtual Environment for Radiotherapy Training) system is a Flight Simulator for Radiation Oncology professionals, wherein fundamental concepts, techniques and problematic scenarios can be safely investigated. Methods: The system provides detailed simulations of several Linacs and the ability to display DICOM treatment plans. Patients can be mis-positioned with 'set-up errors' which can be explored visually, dosimetrically and using IGRT. Similarly, a variety of Linac calibration and configuration parameters can be altered manually or randomly via controlled errors in the simulated 3D Linac and its component parts. The implication of these can be investigated by following through a treatment scenario or using QC devices available within a Physics software module. Results: One resultant exercise is a systematic mis-calibration of 'lateral laser height' by 2mm. The offset in patient alignment is easily identified using IGRT and once corrected by reference to the 'in-room monitor'. The dosimetric implication is demonstrated to be 0.4% by setting a dosimetry phantom by the lasers (and ignoring TSD information). Finally, the need for recalibration can be shown by the Laser Alignment Phantom or by reference to the front pointer. Conclusions: The VERT system provides a realistic environment for training and enhancing understanding of radiotherapy concepts and techniques. Linac error conditions can be explored in this context and valuable experience gained in a controlled manner in a compressed period of time.

Dosimetric monitoring in Ukraine - present status and path to the future

International Nuclear Information System (INIS)

Chumak, V.; Boguslavskaya, A.

2005-01-01

Full text: Ukraine is the country which utilizes radiation in many peaceful areas. So, nuclear energy sector includes 15 power units (including two new units commissioned in 2004), nuclear fuel cycle also include uranium mines, radiation sources are widely used in industry, science and medicine. As a result, about 50,000 occupationally exposed workers require dosimetric monitoring. However, presently dosimetry services in Ukraine cover only about 38,000 occupationally exposed workers, including 9,100 medical professionals, 16,400 employees of 5 nuclear power plants and ca. 12,400 workers dealing with other sources of occupational exposure (industry, research). Territorial dosimetry services, responsible for dosimetric monitoring in industry and medicine operate in 13 of 25 oblasts (regions) of Ukraine. The coverage of critical groups by dosimetric monitoring is variable and ranges from 38 % to 100 % depending on the oblast. With rare exception, instrumentation is represented by outdated manual TLD systems (inaccurate and insufficiently sensitive) capable of measurement of deep photon dose only; no personal monitoring of beta and neutron exposure is possible now. Quality assurance is limited to the annual metrological attestation of the dosimetric instruments. No information exchange infrastructure and dosimetric registry are in place. The dosimetric data is stored in home-made data environments or even in paper log-books, no data on individual doses is conveyed to central depository, which could be easily accessible for regulating authorities. Although the standing law requires elaboration of the United System for monitoring and registration individual doses, little was done so far, mainly due to lack of domestic funding. However, intention is strong to build such network in accordance with the best practice, covering not only the aspects of physical measurement and data storage, but also quality assurance, accreditation programs and training of the local personnel

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

International Nuclear Information System (INIS)

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

2007-01-01

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

Dosimetric assessment of the PRESAGE dosimeter for a proton pencil beam

International Nuclear Information System (INIS)

Wuu, C-S; Qian, X; Xu, Y; Adamovics, J; Cascio, E; Lu, H-M

2013-01-01

The objective of this study is to assess the feasibility of using PRESAGE dosimeters for proton pencil beam dosimetry. Two different formulations of phantom materials were tested for their suitability in characterizing a single proton pencil beam. The dosimetric response of PRESAGE was found to be linear up to 4Gy. First-generation optical CT scanner, OCTOPUS TM was used to implement dose distributions for proton pencil beams since it provides most accurate readout. Percentage depth dose curves and beam profiles for two proton energy, 110 MeV, and 93 MeV, were used to evaluate the dosimetric performance of two PRESAGE phantom formulas. The findings from this study show that the dosimetric properties of the phantom materials match with basic physics of proton beams.

Dosimetric impact of gastrointestinal air column in radiation treatment of pancreatic cancer.

Science.gov (United States)

Estabrook, Neil C; Corn, Jonathan B; Ewing, Marvene M; Cardenes, Higinia R; Das, Indra J

2018-02-01

Dosimetric evaluation of air column in gastrointestinal (GI) structures in intensity modulated radiation therapy (IMRT) of pancreatic cancer. Nine sequential patients were retrospectively chosen for dosimetric analysis of air column in the GI apparatus in pancreatic cancer using cone beam CT (CBCT). The four-dimensional CT (4DCT) was used for target and organs at risk (OARs) and non-coplanar IMRT was used for treatment. Once a week, these patients underwent CBCT for air filling, isocentre verification and dose calculations retrospectively. Abdominal air column variation was as great as ±80% between weekly CBCT and 4DCT. Even with such a large air column in the treatment path for pancreatic cancer, changes in anteroposterior dimension were minimal (2.8%). Using IMRT, variations in air column did not correlate dosimetrically with large changes in target volume. An average dosimetric deviation of mere -3.3% and a maximum of -5.5% was observed. CBCT revealed large air column in GI structures; however, its impact is minimal for target coverage. Because of the inherent advantage of segmentation in IMRT, where only a small fraction of a given beam passes through the air column, this technique might have an advantage over 3DCRT in treating upper GI malignancies where the daily air column can have significant impact. Advances in knowledge: Radiation treatment of pancreatic cancer has significant challenges due to positioning, imaging of soft tissues and variability of air column in bowels. The dosimetric impact of variable air column is retrospectively studied using CBCT. Even though, the volume of air column changes by ± 80%, its dosimetric impact in IMRT is minimum.

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

Energy Technology Data Exchange (ETDEWEB)

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

2007-07-21

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

Dosimetric systems of high dose, dose rate and dose uniformity in food and medical products

International Nuclear Information System (INIS)

Vargas, J.; Vivanco, M.; Castro, E.

2014-08-01

In the Instituto Peruano de Energia Nuclear (IPEN) we use the chemical dosimetry Astm-E-1026 Fricke as a standard dosimetric system of reference and different routine dosimetric systems of high doses, according to the applied doses to obtain the desired effects in the treated products and the doses range determined for each type of dosimeter. Fricke dosimetry is a chemical dosimeter in aqueous solution indicating the absorbed dose by means an increase in absorbance at a specific wavelength. A calibrated spectrophotometer with controlled temperature is used to measure absorbance. The adsorbed dose range should cover from 20 to 400 Gy, the Fricke solution is extremely sensitive to organic impurities, to traces of metal ions, in preparing chemical products of reactive grade must be used and the water purity is very important. Using the referential standard dosimetric system Fricke, was determined to March 5, 2013, using the referential standard dosimetric system Astm-1026 Fricke, were irradiated in triplicate Fricke dosimeters, to 5 irradiation times (20; 30; 40; 50 and 60 seconds) and by linear regression, the dose rate of 5.400648 kGy /h was determined in the central point of the irradiation chamber (irradiator Gamma cell 220 Excel), applying the decay formula, was compared with the obtained results by manufacturers by means the same dosimetric system in the year of its manufacture, being this to the date 5.44691 kGy /h, with an error rate of 0.85. After considering that the dosimetric solution responds to the results, we proceeded to the irradiation of a sample of 200 g of cereal instant food, 2 dosimeters were placed at the lateral ends of the central position to maximum dose and 2 dosimeters in upper and lower ends as minimum dose, they were applied same irradiation times; for statistical analysis, the maximum dose rate was 6.1006 kGy /h and the minimum dose rate of 5.2185 kGy /h; with a dose uniformity of 1.16. In medical material of micro pulverized bone for

IPIP: A new approach to inverse planning for HDR brachytherapy by directly optimizing dosimetric indices

International Nuclear Information System (INIS)

Siauw, Timmy; Cunha, Adam; Atamtuerk, Alper; Hsu, I-Chow; Pouliot, Jean; Goldberg, Ken

2011-01-01

Purpose: Many planning methods for high dose rate (HDR) brachytherapy require an iterative approach. A set of computational parameters are hypothesized that will give a dose plan that meets dosimetric criteria. A dose plan is computed using these parameters, and if any dosimetric criteria are not met, the process is iterated until a suitable dose plan is found. In this way, the dose distribution is controlled by abstract parameters. The purpose of this study is to develop a new approach for HDR brachytherapy by directly optimizing the dose distribution based on dosimetric criteria. Methods: The authors developed inverse planning by integer program (IPIP), an optimization model for computing HDR brachytherapy dose plans and a fast heuristic for it. They used their heuristic to compute dose plans for 20 anonymized prostate cancer image data sets from patients previously treated at their clinic database. Dosimetry was evaluated and compared to dosimetric criteria. Results: Dose plans computed from IPIP satisfied all given dosimetric criteria for the target and healthy tissue after a single iteration. The average target coverage was 95%. The average computation time for IPIP was 30.1 s on an Intel(R) Core TM 2 Duo CPU 1.67 GHz processor with 3 Gib RAM. Conclusions: IPIP is an HDR brachytherapy planning system that directly incorporates dosimetric criteria. The authors have demonstrated that IPIP has clinically acceptable performance for the prostate cases and dosimetric criteria used in this study, in both dosimetry and runtime. Further study is required to determine if IPIP performs well for a more general group of patients and dosimetric criteria, including other cancer sites such as GYN.

Preliminary dosimetric methodology for a new cobalt-60 irradiator for radioinduced necrosis

International Nuclear Information System (INIS)

Moura, Eduardo S.; Mosca, Rodrigo C.; Zeituni, Carlos A.; Rostelato, Maria Elisa C.M.; Mathor, Monica B.; Sakuraba, Roberto K.; Goncalves, Vinicius D.

2011-01-01

The use of ionizing radiation in medical procedures, as radiotherapy, is a well-established clinical process and it has been used for several decades with good clinical results and continuous technology development for treatment optimization. On the contrary, some injuries such as necrosis, may occur with patients, due to wrong administration of the absorbed dose or with expected side effects. To evaluate how these injuries could be investigated and how they can be treated, a new Cobalto-60 irradiator was developed to induce radionecrosis in mice. This irradiator is composed by a cylindrical size and it was set up with eleven Cobalt-60 sources aligned in the surface of a cylindrical lead. This alignment guarantees a small dose focal area in a longitudinal table, with proper frames for positioning mice precisely during the irradiations period. The dosimetric procedure will measure the absorbed dose in the dose focal area, delimited the area of irradiation with penumbra regions (gradients absorbed dose profiles) and others anatomical regions of the mice with high radiosensitivity. Possible dosimetric procedures and related devices will be present in this work,. The obtained dosimetric data will be applied to ensure the accurate period of radiation of a given position. This preliminary study assures that the fundamental dosimetric process of this new Cobalt-60 irradiator and it predicates that dosimetric processes area feasible to be conducted. (author)

Preliminary dosimetric methodology for a new cobalt-60 irradiator for radioinduced necrosis

Energy Technology Data Exchange (ETDEWEB)

Moura, Eduardo S.; Mosca, Rodrigo C.; Zeituni, Carlos A.; Rostelato, Maria Elisa C.M.; Mathor, Monica B., E-mail: esmoura@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Sakuraba, Roberto K.; Goncalves, Vinicius D. [Hospital Israelita Albert Einstein (HIAE), Sao Paulo, SP (Brazil)

2011-07-01

The use of ionizing radiation in medical procedures, as radiotherapy, is a well-established clinical process and it has been used for several decades with good clinical results and continuous technology development for treatment optimization. On the contrary, some injuries such as necrosis, may occur with patients, due to wrong administration of the absorbed dose or with expected side effects. To evaluate how these injuries could be investigated and how they can be treated, a new Cobalto-60 irradiator was developed to induce radionecrosis in mice. This irradiator is composed by a cylindrical size and it was set up with eleven Cobalt-60 sources aligned in the surface of a cylindrical lead. This alignment guarantees a small dose focal area in a longitudinal table, with proper frames for positioning mice precisely during the irradiations period. The dosimetric procedure will measure the absorbed dose in the dose focal area, delimited the area of irradiation with penumbra regions (gradients absorbed dose profiles) and others anatomical regions of the mice with high radiosensitivity. Possible dosimetric procedures and related devices will be present in this work,. The obtained dosimetric data will be applied to ensure the accurate period of radiation of a given position. This preliminary study assures that the fundamental dosimetric process of this new Cobalt-60 irradiator and it predicates that dosimetric processes area feasible to be conducted. (author)

Correction of count losses due to deadtime on a DST-XLi (SMVi-GE) camera during dosimetric studies in patients injected with iodine-131

International Nuclear Information System (INIS)

Delpon, G.; Ferrer, L.; Lisbona, A.; Bardies, M.

2002-01-01

In dosimetric studies performed after therapeutic injection, it is essential to correct count losses due to deadtime on the gamma camera. This note describes four deadtime correction methods, one based on the use of a standard source without preliminary calibration, and three requiring specific calibration and based on the count rate observed in different spectrometric windows (20%, 20% plus a lower energy window and the full spectrum of 50-750 keV). Experiments were conducted on a phantom at increasingly higher count rates to check correction accuracy with the different methods. The error was less than +7% with a standard source, whereas count-rate-based methods gave more accurate results. On the assumption that the model was paralysable, preliminary calibration allowed an observed count rate curve to be plotted as a function of the real count rate. The use of the full spectrum led to a 3.0% underestimation for the highest activity imaged. As count losses depend on photon flux independent of energy, the use of the full spectrum during measurement allowed scatter conditions to be taken into account. A protocol was developed to apply this correction method to whole-body acquisitions. (author)

Effective atomic numbers and electron density of dosimetric material

Directory of Open Access Journals (Sweden)

Kaginelli S

2009-01-01

Full Text Available A novel method for determination of mass attenuation coefficient of x-rays employing NaI (Tl detector system and radioactive sources is described.in this paper. A rigid geometry arrangement and gating of the spectrometer at FWHM position and selection of absorber foils are all done following detailed investigation, to minimize the effect of small angle scattering and multiple scattering on the mass attenuation coefficient, m/r, value. Firstly, for standardization purposes the mass attenuation coefficients of elemental foils such as Aluminum, Copper, Molybdenum, Tantalum and Lead are measured and then, this method is utilized for dosimetric interested material (sulfates. The experimental mass attenuation coefficient values are compared with the theoretical values to find good agreement between the theory and experiment within one to two per cent. The effective atomic numbers of the biological substitute material are calculated by sum rule and from the graph. The electron density of dosimetric material is calculated using the effective atomic number. The study has discussed in detail the attenuation coefficient, effective atomic number and electron density of dosimetric material/biological substitutes.

Dosimetric system for measurement of radioactive contaminations

International Nuclear Information System (INIS)

Litynski, Z.; Pienkos, J.P.; Witkowski, J.; Zadrozny, S.

1985-01-01

A dosimetric system for personnel dosimetry and monitoring measuring a contamination without time delay and dead time is described. The system ensures many-point measurement and minimalization of background radiation influence. 1 fig. (A.S.)

A real-time in vivo dosimetric verification method for high-dose rate intracavitary brachytherapy of nasopharyngeal carcinoma

Energy Technology Data Exchange (ETDEWEB)

Qi Zhenyu; Deng Xiaowu; Cao Xinping; Huang Shaomin; Lerch, Michael; Rosenfeld, Anatoly [State Key Laboratory of Oncology in South China, Sun Yat-sen University Cancer Center, Guangzhou 510060 (China) and Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW 2522 (Australia); State Key Laboratory of Oncology in South China, Sun Yat-sen University Cancer Center, Guangzhou 510060 (China); Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW 2522 (Australia)

2012-11-15

Purpose: A real-time in vivo dosimetric verification method using metal-oxide-semiconductor field effect transistor (MOSFET) dosimeters has been developed for patient dosimetry in high-dose rate (HDR) intracavitary brachytherapy of nasopharyngeal carcinoma (NPC). Methods: The necessary calibration and correction factors for MOSFET measurements in {sup 192}Iridium source were determined in a water phantom. With the detector placed inside a custom-made nasopharyngeal applicator, the actual dose delivered to the tumor was measured in vivo and compared to the calculated values using a commercial brachytherapy planning system. Results: Five MOSFETs were independently calibrated with the HDR source, yielding calibration factors of 0.48 {+-} 0.007 cGy/mV. The maximum sensitivity variation was no more than 7% in the clinically relevant distance range of 1-5 cm from the source. A total of 70 in vivo measurements in 11 NPC patients demonstrated good agreement with the treatment planning. The mean differences between the planned and the actually delivered dose within a single treatment fraction were -0.1%{+-} 3.8% and -0.1%{+-} 3.7%, respectively, for right and left side assessments. The maximum dose deviation was less than 8.5%. Conclusions: In vivo measurement using the real-time MOSFET dosimetry system is possible to evaluate the actual dose to the tumor received by the patient during a treatment fraction and thus can offer another line of security to detect and prevent large errors.

A simple topography-driven, calibration-free runoff generation model

Science.gov (United States)

Gao, H.; Birkel, C.; Hrachowitz, M.; Tetzlaff, D.; Soulsby, C.; Savenije, H. H. G.

2017-12-01

Determining the amount of runoff generation from rainfall occupies a central place in rainfall-runoff modelling. Moreover, reading landscapes and developing calibration-free runoff generation models that adequately reflect land surface heterogeneities remains the focus of much hydrological research. In this study, we created a new method to estimate runoff generation - HAND-based Storage Capacity curve (HSC) which uses a topographic index (HAND, Height Above the Nearest Drainage) to identify hydrological similarity and partially the saturated areas of catchments. We then coupled the HSC model with the Mass Curve Technique (MCT) method to estimate root zone storage capacity (SuMax), and obtained the calibration-free runoff generation model HSC-MCT. Both the two models (HSC and HSC-MCT) allow us to estimate runoff generation and simultaneously visualize the spatial dynamic of saturated area. We tested the two models in the data-rich Bruntland Burn (BB) experimental catchment in Scotland with an unusual time series of the field-mapped saturation area extent. The models were subsequently tested in 323 MOPEX (Model Parameter Estimation Experiment) catchments in the United States. HBV and TOPMODEL were used as benchmarks. We found that the HSC performed better in reproducing the spatio-temporal pattern of the observed saturated areas in the BB catchment compared with TOPMODEL which is based on the topographic wetness index (TWI). The HSC also outperformed HBV and TOPMODEL in the MOPEX catchments for both calibration and validation. Despite having no calibrated parameters, the HSC-MCT model also performed comparably well with the calibrated HBV and TOPMODEL, highlighting the robustness of the HSC model to both describe the spatial distribution of the root zone storage capacity and the efficiency of the MCT method to estimate the SuMax. Moreover, the HSC-MCT model facilitated effective visualization of the saturated area, which has the potential to be used for broader

Contura Multi-Lumen Balloon Breast Brachytherapy Catheter: Comparative Dosimetric Findings of a Phase 4 Trial

Energy Technology Data Exchange (ETDEWEB)

Arthur, Douglas W., E-mail: darthur@mcvh-vcu.edu [Department of Radiation Oncology, Virginia Commonwealth University, Richmond, Virginia (United States); Vicini, Frank A. [Michigan Healthcare Professionals/21st Century Oncology, Farmington Hills, Michigan (United States); Todor, Dorin A. [Department of Radiation Oncology, Virginia Commonwealth University, Richmond, Virginia (United States); Julian, Thomas B. [Allegheny General Hospital, Temple University School of Medicine, Pittsburgh, Pennsylvania (United States); Cuttino, Laurie W.; Mukhopadhyay, Nitai D. [Department of Radiation Oncology, Virginia Commonwealth University, Richmond, Virginia (United States)

2013-06-01

Purpose: Final dosimetric findings of a completed, multi-institutional phase 4 registry trial using the Contura Multi-Lumen Balloon (MLB) breast brachytherapy catheter to deliver accelerated partial breast irradiation (APBI) in patients with early-stage breast cancer are presented. Methods and Materials: Three dosimetric plans with identical target coverage were generated for each patient for comparison: multilumen multidwell (MLMD); central-lumen multidwell (CLMD); and central-lumen single-dwell (CLSD) loading of the Contura catheter. For this study, a successful treatment plan achieved ideal dosimetric goals and included the following: ≥95% of the prescribed dose (PD) covering ≥95% of the target volume (TV); maximum skin dose ≤125% of the PD; maximum rib dose ≤145% of the PD; and V150 ≤50 cc and V200 ≤10 cc. Results: Between January 2008 and February 2011, 23 institutions participated. A total of 318 patients were available for dosimetric review. Using the Contura MLB, all dosimetric criteria were met in 78.93% of cases planned with MLMD versus 55.38% with the CLMD versus 37.66% with the CLSD (P≤.0001). Evaluating all patients with the full range of skin to balloon distance represented, median maximum skin dose was reduced by 12% and median maximum rib dose by 13.9% when using MLMD-based dosimetric plans compared to CLSD. The dosimetric benefit of MLMD was further demonstrated in the subgroup of patients where skin thickness was <5 mm, where MLMD use allowed a 38% reduction in median maximum skin dose over CLSD. For patients with rib distance <5 mm, the median maximum rib dose reduction was 27%. Conclusions: Use of the Contura MLB catheter produced statistically significant improvements in dosimetric capabilities between CLSD and CLMD treatments. This device approach demonstrates the ability not only to overcome the barriers of limited skin thickness and close rib proximity, but to consistently achieve a higher standard of dosimetric planning goals.

Contura Multi-Lumen Balloon breast brachytherapy catheter: comparative dosimetric findings of a phase 4 trial.

Science.gov (United States)

Arthur, Douglas W; Vicini, Frank A; Todor, Dorin A; Julian, Thomas B; Cuttino, Laurie W; Mukhopadhyay, Nitai D

2013-06-01

Final dosimetric findings of a completed, multi-institutional phase 4 registry trial using the Contura Multi-Lumen Balloon (MLB) breast brachytherapy catheter to deliver accelerated partial breast irradiation (APBI) in patients with early-stage breast cancer are presented. Three dosimetric plans with identical target coverage were generated for each patient for comparison: multilumen multidwell (MLMD); central-lumen multidwell (CLMD); and central-lumen single-dwell (CLSD) loading of the Contura catheter. For this study, a successful treatment plan achieved ideal dosimetric goals and included the following: ≥ 95% of the prescribed dose (PD) covering ≥ 95% of the target volume (TV); maximum skin dose ≤ 125% of the PD; maximum rib dose ≤ 145% of the PD; and V150 ≤50 cc and V200 ≤ 10 cc. Between January 2008 and February 2011, 23 institutions participated. A total of 318 patients were available for dosimetric review. Using the Contura MLB, all dosimetric criteria were met in 78.93% of cases planned with MLMD versus 55.38% with the CLMD versus 37.66% with the CLSD (P ≤.0001). Evaluating all patients with the full range of skin to balloon distance represented, median maximum skin dose was reduced by 12% and median maximum rib dose by 13.9% when using MLMD-based dosimetric plans compared to CLSD. The dosimetric benefit of MLMD was further demonstrated in the subgroup of patients where skin thickness was <5 mm, where MLMD use allowed a 38% reduction in median maximum skin dose over CLSD. For patients with rib distance <5 mm, the median maximum rib dose reduction was 27%. Use of the Contura MLB catheter produced statistically significant improvements in dosimetric capabilities between CLSD and CLMD treatments. This device approach demonstrates the ability not only to overcome the barriers of limited skin thickness and close rib proximity, but to consistently achieve a higher standard of dosimetric planning goals. Copyright © 2013 Elsevier Inc. All rights

Personal dosimetry service of TECNATOM: measurement system and methodology of calibration

International Nuclear Information System (INIS)

Marchena, Paloma; Bravo, Borja

2008-01-01

Full text: The implementation of a new integrated and practical working tool called ALEDIN within the Personal Dosimetry Service (PDS) of TECNATOM, have harmonized the methodology for the counting acquisition, detector calibration and data analysis using a friendly Windows (registered mark) environment. The knowledge of this methodology, due to the fact that is the final product of a R and D project, will help the users and the Regulatory Body for a better understanding of the internal activity measurement in individuals, allowing a more precise error identification and correction, and improving the whole process of the internal dosimetry. The development and implementation of a new calibration system of the whole body counters using NaI (Tl) detectors and the utilization of a new humanoid anthropometric phantom, BOMAB type, with a uniform radioactive source distributions, allow a better energy and activity calibration for different counting geometries covering a wide range of gamma spectra from low energies, less than 100 keV to about 2000 keV for the high energies spectra. This new calibration methodology implied the development of an improved system for the determination of the isotopic activity. This new system has been integrated in a Windows (registered mark) environment, applicable for counting acquisition and data analysis in the whole body counters WBC in cross connection with the INDAC software, which allow the interpretation of the measured activity as committed effective dose following all the new ICRP recommendations and dosimetric models for internal dose and bioassay measurements. (author)

Evaluation of the dosimetric performance characteristic of fluoroscopy system used in medicine

International Nuclear Information System (INIS)

Qi Xuesong; Wei Kedao; Cheng Yuxi; Zhou Qifu; Ge Lijuan; Hou Changsong

2001-01-01

Objective: To discuss establishment of diagnostic reference dose value in fluoroscopic examinations for survey of 16 different types of fluoroscopy systems. Methods: Choosing dosimetric characteristic parameters including: IIESDR, ESDR (typical value) and ESDR max (ESDR maximum), and DAP, which was calibrated in situ on the X-ray unit. Results: Results of dose survey are summarized in three tables, from these we could get wide changes in accordance with those in many other countries resulting from maximum and minimum of IIESDR, ESDR and ESDRmax when measurements were performed at same entrance field size on I.I. Image Intensifier of the 15 fluoroscopy systems and under conditions of ABC. And also we could get less changes of DAP mean values, though differences for patient weight, technological parameters of fluoroscopic exam setting, fluoroscopic time and number of film were more remarkable. Conclusions: Measurements on IIESDR, ESDR (typical value) and ESDRmax (ESDR maximum) are not satisfied as diagnostic reference level. But it is suggested that DAP values, in fluoroscopic exam, are used as a tool to achieve this. (author)

Comparison and utilization of two dosimetric systems for e-beam industrial irradiation

Energy Technology Data Exchange (ETDEWEB)

Fortes, Marcio Z., E-mail: mzamboti@aceletron.com.b [Aceletron Irradiacao Industrial, Rio de Janeiro, RJ (Brazil). Gerencia Tecnica e Operacoes; Sousa, Fernando N.C. de; Boente, Otavio C., E-mail: fernando.nuno@aceletron.com.b, E-mail: otavio@aceletron.com.b [Aceletron Irradiacao Industrial, Rio de Janeiro, RJ (Brazil). Gerencia de Desenvolvimento de Produtos; Sousa, Nuno R.A., E-mail: engenheiro.nuno.sousa@gmail.co [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Dept. de Engenharia Mecanica

2009-07-01

The utilization of electron linear accelerators (LINAC's) for industrial irradiation of several products like turf, sterilization of medical products, cosmetics, polymers, food, and gems, can only be successful if a reliable dosimetric system is chosen. There are several different available technologies and two were selected for this study. The first one uses alanine dosimeters which can be read with electron spin resonance spectrometers (ESR); the second uses B3 radiochromic dosimeters which are read with a spectrophotometer. This study presents a comparison of both technologies in the dose range of 1 to 80 kGy, taking into account initial cost, precision, reading time, calibration, among others, for a typical 24 hour production run, and for normal operational routines and tests. It is shown that each system has its own advantages and disadvantages, and that both can be used in an e-beam installation. However, for industrial applications it is necessary to optimize the process, so it is presented which dosimeter is used for each routine application. (author)

Improvement in the dosimetric CaSO4: Dy obtention method

International Nuclear Information System (INIS)

Campos, L.L.; Frutuoso, P.H.; Souto, V.J.

1989-08-01

With the purpose of saving up in the dosimetric CaSO 4 : Dy production, a new method was developed to obtain single crystals. In this method the nitrogen flux used to carry the acid vapour was substituted by compressed air. It was compared all dosimetric properties of the crystals. There is no alteration in the glow curve. The sensitivity is the same in both cases and the lower detection limit is 3.8 x 10 -8 C.Kg -1 (150 μR) [pt

Calibration of a spectrometry multisphere system for neutron fields

International Nuclear Information System (INIS)

Carelli, Jorge L.; Cruzate, Juan A.; Papadopulos, Susana B.; Gregori, Beatriz N.; Ciocci Brazzano, Ligia

2005-01-01

In this work it is presented the calibration of the neutrons spectrometric system of the Nuclear Regulatory Authority (ARN) in the Institut de Protection et Sure te Nucleaires (Ipn), Labourite dadaist et de Recherche s en Dosimetric Extern e, Cadarache, France. The multisphere system is composed of 9 polyethylene spheres of high density, with a gaseous detector of 3 He and associate electronics. The matrix of energy response to the system neutrons was obtained applying the MCNPX code for the range of energies between thermal and 100 MeV with cross sections taken from library ENDF/B-VI. The neutron spectra of the multisphere system were obtained applying the deconvolution code LOUHI82. The relationship between the theoretical responses and the experiences obtained with the AmBe and 252 Cf sources are also presented in this work [es

Thermoluminescent Dosimeter as the Gamma Component of a Nuclear Accident Dosimeter; Utilisation du Dosimetre Thermoluminescent Comme Element Detecteur Gamma d'un Dosimetre pour les cas d'Accident Nucleaire; 0422 0415 0420 041c 0414 ; Los Detectores de Termoluminiscencia Como Elemento Gammametrico de un Dosimetro para Casos de Accidente Nuclear

Energy Technology Data Exchange (ETDEWEB)

Handloser, J. S. [Edgerton, Germeshausen and Grier, Inc., Santa Barbara, CA (United States)

1965-06-15

dans les dosimetres a utiliser en cas d'accident. Il a essaye diverses sortes de dosimetres en verre, de dosimetres a films, de dosimetres chimiques et de dosimetres a polymerisation, mais le dosimetre thermoluminescent est celui qui presente le plus d'avantages. En raison de sa grande etendue de mesure, le dosimetre thermoluminescent peut etre utilise a la fois comme appareil de controle radiologique quotidien et comme dosimetre en cas d'accident. Ce systeme rend inutile remploi d'instruments speciaux pour la dosimetrie des accidents et permet d'utiliser a cette fin les instruments bien calibres d'usage quotidien. Habituellement, l'etendue de mesure d'un dosimetre thermoluminescent est de 5 mr a 100 000 r, avec une reproductibilite de {+-} 10%. L'auteur a concu et fabrique un modele unique de dosimetre a fluorure de calcium avec dispositif de lecture pouvant mesurer de 5 mr a 5000 r. La lecture du dosimetre est realisee par chauffage du phosphore et mesure de la lumiere emise. On dispose d'instruments de lecture a six echelles de graduation et des systemes entierement automatises sont prevus. La lecture a l'aide de chacun de ces appareils ne prend pas plus de 20 s par dosimetre. Un autre avantage du dosimetre thermoluminescent est sa faible reponse aux neutrons. La reponse aux neutrons varie selon le type du support et le type de phosphore. Un modele de dosimetre au fluorure de calcium a une reponse aux neutrons de 0.27 x 10{sup -9} rad/n/cm{sup 2}. L'auteur examine deux formes physiques de dosimetres thermoluminescents. Le premier est un dosimetre a chauffage interne place sous vide dans une capsule de verre; il a approximativement les dimensions suivantes: diametre 1 cm, longueur 6 cm. Le second modele est constitue par un tube de verre de faible section dans lequel le phosphore est scelle. Ce dosimetre a un diametre de 0,8 mm et une longueur de 6 mm. L'auteur a concu des ecrans de correction de la reponse a l 'energie pour ces deux types de dosimetres. (author

Organ motion study and dosimetric impact of respiratory gating radiotherapy for esophageal cancer

International Nuclear Information System (INIS)

Lorchel, F.

2007-04-01

Chemoradiotherapy is now the standard treatment for locally advanced or inoperable esophageal carcinoma. In this indication, conformal radiotherapy is generally used. However, prognosis remains poor for these patients. Respiratory gating radiotherapy can decrease healthy tissues irradiation and allows escalation dose in lung, liver and breast cancer. In order to improve radiotherapy technique, we propose to study the feasibility of respiratory gating for esophageal cancer. We will study the respiratory motions of esophageal cancer to optimize target volume delineation, especially the internal margin (I.M.). We will test the correlation between tumour and chest wall displacements to prove that esophageal cancer motions are induced by respiration. This is essential before using free breathing respiratory gating systems. We will work out the dosimetric impact of respiratory gating using various dosimetric analysis parameters. We will compare dosimetric plans at end expiration, end inspiration and deep inspiration with dosimetric plan in free-breathing condition. This will allow us to establish the best respiratory phase to irradiate for each gating system. This dosimetric study will be completed with linear quadratic equivalent uniform dose (E.U.D.) calculation for each volume of interest. Previously, we will do a theoretical study of histogram dose volume gradation to point up its use. (author)

Spectrometric methods used in the calibration of radiodiagnostic measuring instruments

Energy Technology Data Exchange (ETDEWEB)

De Vries, W [Rijksuniversiteit Utrecht (Netherlands)

1995-12-01

Recently a set of parameters for checking the quality of radiation for use in diagnostic radiology was established at the calibration facility of Nederlands Meetinstituut (NMI). The establishment of the radiation quality required re-evaluation of the correction factors for the primary air-kerma standards. Free-air ionisation chambers require several correction factors to measure air-kerma according to its definition. These correction factors were calculated for the NMi free-air chamber by Monte Carlo simulations for monoenergetic photons in the energy range from 10 keV to 320 keV. The actual correction factors follow from weighting these mono-energetic correction factors with the air-kerma spectrum of the photon beam. This paper describes the determination of the photon spectra of the X-ray qualities used for the calibration of dosimetric instruments used in radiodiagnostics. The detector used for these measurements is a planar HPGe-detector, placed in the direct beam of the X-ray machine. To convert the measured pulse height spectrum to the actual photon spectrum corrections must be made for fluorescent photon escape, single and multiple compton scattering inside the detector, and detector efficiency. From the calculated photon spectra a number of parameters of the X-ray beam can be calculated. The calculated first and second half value layer in aluminum and copper are compared with the measured values of these parameters to validate the method of spectrum reconstruction. Moreover the spectrum measurements offer the possibility to calibrate the X-ray generator in terms of maximum high voltage. The maximum photon energy in the spectrum is used as a standard for calibration of kVp-meters.

Comparison of infusion pumps calibration methods

Science.gov (United States)

Batista, Elsa; Godinho, Isabel; do Céu Ferreira, Maria; Furtado, Andreia; Lucas, Peter; Silva, Claudia

2017-12-01

Nowadays, several types of infusion pump are commonly used for drug delivery, such as syringe pumps and peristaltic pumps. These instruments present different measuring features and capacities according to their use and therapeutic application. In order to ensure the metrological traceability of these flow and volume measuring equipment, it is necessary to use suitable calibration methods and standards. Two different calibration methods can be used to determine the flow error of infusion pumps. One is the gravimetric method, considered as a primary method, commonly used by National Metrology Institutes. The other calibration method, a secondary method, relies on an infusion device analyser (IDA) and is typically used by hospital maintenance offices. The suitability of the IDA calibration method was assessed by testing several infusion instruments at different flow rates using the gravimetric method. In addition, a measurement comparison between Portuguese Accredited Laboratories and hospital maintenance offices was performed under the coordination of the Portuguese Institute for Quality, the National Metrology Institute. The obtained results were directly related to the used calibration method and are presented in this paper. This work has been developed in the framework of the EURAMET projects EMRP MeDD and EMPIR 15SIP03.

Patient feature based dosimetric Pareto front prediction in esophageal cancer radiotherapy.

Science.gov (United States)

Wang, Jiazhou; Jin, Xiance; Zhao, Kuaike; Peng, Jiayuan; Xie, Jiang; Chen, Junchao; Zhang, Zhen; Studenski, Matthew; Hu, Weigang

2015-02-01

To investigate the feasibility of the dosimetric Pareto front (PF) prediction based on patient's anatomic and dosimetric parameters for esophageal cancer patients. Eighty esophagus patients in the authors' institution were enrolled in this study. A total of 2928 intensity-modulated radiotherapy plans were obtained and used to generate PF for each patient. On average, each patient had 36.6 plans. The anatomic and dosimetric features were extracted from these plans. The mean lung dose (MLD), mean heart dose (MHD), spinal cord max dose, and PTV homogeneity index were recorded for each plan. Principal component analysis was used to extract overlap volume histogram (OVH) features between PTV and other organs at risk. The full dataset was separated into two parts; a training dataset and a validation dataset. The prediction outcomes were the MHD and MLD. The spearman's rank correlation coefficient was used to evaluate the correlation between the anatomical features and dosimetric features. The stepwise multiple regression method was used to fit the PF. The cross validation method was used to evaluate the model. With 1000 repetitions, the mean prediction error of the MHD was 469 cGy. The most correlated factor was the first principal components of the OVH between heart and PTV and the overlap between heart and PTV in Z-axis. The mean prediction error of the MLD was 284 cGy. The most correlated factors were the first principal components of the OVH between heart and PTV and the overlap between lung and PTV in Z-axis. It is feasible to use patients' anatomic and dosimetric features to generate a predicted Pareto front. Additional samples and further studies are required improve the prediction model.

Validating dose rate calibration of radiotherapy photon beams through IAEA/WHO postal audit dosimetry service

International Nuclear Information System (INIS)

Jangda, A.Q.; Hussein, S.

2012-01-01

In external beam radiation therapy (EBRT), the quality assurance (QA) of the radiation beam is crucial to the accurate delivery of the prescribed dose to the patient. One of the dosimetric parameters that require monitoring is the beam output, specified as the dose rate on the central axis under reference conditions. The aim of this project was to validate dose rate calibration of megavoltage photon beams using the International Atomic Energy Agency (IAEA)/World Health Organisation (WHO) postal audit dosimetry service. Three photon beams were audited: a 6 MV beam from the low-energy linac and 6 and 18 MV beams from a dual high-energy linac. The agreement between our stated doses and the IAEA results was within 1% for the two 6 MV beams and within 2% for the 18 MV beam. The IAEA/WHO postal audit dosimetry service provides an independent verification of dose rate calibration protocol by an international facility. (author)

Validating dose rate calibration of radiotherapy photon beams through IAEA/WHO postal audit dosimetry service.

Science.gov (United States)

Jangda, Abdul Qadir; Hussein, Sherali

2012-05-01

In external beam radiation therapy (EBRT), the quality assurance (QA) of the radiation beam is crucial to the accurate delivery of the prescribed dose to the patient. One of the dosimetric parameters that require monitoring is the beam output, specified as the dose rate on the central axis under reference conditions. The aim of this project was to validate dose rate calibration of megavoltage photon beams using the International Atomic Energy Agency (IAEA)/World Health Organisation (WHO) postal audit dosimetry service. Three photon beams were audited: a 6 MV beam from the low-energy linac and 6 and 18 MV beams from a dual high-energy linac. The agreement between our stated doses and the IAEA results was within 1% for the two 6 MV beams and within 2% for the 18 MV beam. The IAEA/WHO postal audit dosimetry service provides an independent verification of dose rate calibration protocol by an international facility.

The features of radiation induced lung fibrosis related with dosimetric parameters

International Nuclear Information System (INIS)

Oh, Young-Taek; Noh, O Kyu; Jang, Hyunsoo; Chun, Mison; Park, Kyung Joo; Park, Kwang Joo; Kim, Mi-Hwa; Park, Hae-Jin

2012-01-01

Background and purpose: Radiation induced lung fibrosis (RILF) is a major complication after lung irradiation and is very important for long term quality of life and could result in fatal respiratory insufficiency. However, there has been little information on dosimetric parameters for radiotherapy planning in the aspect of RILF. The features of RILF related with dosimetric parameters were evaluated. Methods and materials: Forty-eight patients with non-small cell lung carcinoma who underwent post-operative radiation therapy (PORT) without adjuvant chemotherapy were analyzed. The degree of lung fibrosis was estimated by fibrosis volume and the dosimetric parameters were calculated from the plan of 3-dimensional conformal radiotherapy. Results: The fibrosis volume and V-dose as dosimetric parameters showed significant correlation and the correlation coefficient ranged from 0.602 to 0.683 (P < 0.01). The degree of the correlation line was steeper as the dose increase and threshold dose was not found. Mean lung dose (MLD) showed strong correlation with fibrosis volume (correlation coefficient = 0.726, P < 0.01). Conclusions: The fibrosis volume is continuously increased with V-dose as the reference dose increases. MLD is useful as a single parameter for comparing rival plans in the aspect of RILF.

Comparing Single-Point and Multi-point Calibration Methods in Modulated DSC

Energy Technology Data Exchange (ETDEWEB)

Van Buskirk, Caleb Griffith [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2017-06-14

Heat capacity measurements for High Density Polyethylene (HDPE) and Ultra-high Molecular Weight Polyethylene (UHMWPE) were performed using Modulated Differential Scanning Calorimetry (mDSC) over a wide temperature range, -70 to 115 °C, with a TA Instruments Q2000 mDSC. The default calibration method for this instrument involves measuring the heat capacity of a sapphire standard at a single temperature near the middle of the temperature range of interest. However, this method often fails for temperature ranges that exceed a 50 °C interval, likely because of drift or non-linearity in the instrument's heat capacity readings over time or over the temperature range. Therefore, in this study a method was developed to calibrate the instrument using multiple temperatures and the same sapphire standard.

The use of a virtual reality simulator to explore and understand the impact of Linac mis-calibrations

International Nuclear Information System (INIS)

Beavis, Andrew W; Ward, James W

2014-01-01

Purpose: In recent years there has been interest in using Computer Simulation within Medical training. The VERT (Virtual Environment for Radiotherapy Training) system is a Flight Simulator for Radiation Oncology professionals, wherein fundamental concepts, techniques and problematic scenarios can be safely investigated. Methods: The system provides detailed simulations of several Linacs and the ability to display DICOM treatment plans. Patients can be mis-positioned with 'set-up errors' which can be explored visually, dosimetrically and using IGRT. Similarly, a variety of Linac calibration and configuration parameters can be altered manually or randomly via controlled errors in the simulated 3D Linac and its component parts. The implication of these can be investigated by following through a treatment scenario or using QC devices available within a Physics software module. Results: One resultant exercise is a systematic mis-calibration of 'lateral laser height' by 2mm. The offset in patient alignment is easily identified using IGRT and once corrected by reference to the 'in-room monitor'. The dosimetric implication is demonstrated to be 0.4% by setting a dosimetry phantom by the lasers (and ignoring TSD information). Finally, the need for recalibration can be shown by the Laser Alignment Phantom or by reference to the front pointer. Conclusions: The VERT system provides a realistic environment for training and enhancing understanding of radiotherapy concepts and techniques. Linac error conditions can be explored in this context and valuable experience gained in a controlled manner in a compressed period of time.

Computational model for dosimetric purposes in dental procedures

International Nuclear Information System (INIS)

Kawamoto, Renato H.; Campos, Tarcisio R.

2013-01-01

This study aims to develop a computational model for dosimetric purposes the oral region, based on computational tools SISCODES and MCNP-5, to predict deterministic effects and minimize stochastic effects caused by ionizing radiation by radiodiagnosis. Based on a set of digital information provided by computed tomography, three-dimensional voxel model was created, and its tissues represented. The model was exported to the MCNP code. In association with SICODES, we used the Monte Carlo N-Particle Transport Code (MCNP-5) method to play the corresponding interaction of nuclear particles with human tissues statistical process. The study will serve as a source of data for dosimetric studies in the oral region, providing deterministic effect and minimize the stochastic effect of ionizing radiation

Establishment of dosimetric references for high energy X-ray beams of very small field sizes (≤ 1 cm2) used in radiotherapy

International Nuclear Information System (INIS)

Dufreneix, Stephane

2014-01-01

The French primary standard dosimetry laboratory 'Laboratoire National Henri Becquerel' is in charge of the establishment of dosimetric standards for ionizing radiation beams. Absolute dose measurements are thus available for X-Ray beams used in radiotherapy for field sizes between 10 and 2 cm. Since the miniaturization of absolute dosimeters is not possible for smaller field sizes, a dose area product (DAP) has been suggested as a substitute to the absorbed dose at a point.In order to measure a DAP with dosimeters which sensitive surface is larger than the beam, a graphite calorimeter with a sensitive surface of 3 cm diameter was designed, built and tested. An ionization chamber with the same diameter was realized and tested to transfer the dosimetric references to the end users. Its calibration factor in terms of DAP was determined in circular beams of 2, 1 and 0.75 cm diameter with an uncertainty smaller than 0.7 %. The two-Dimension relative dose distribution was measured thanks to a diamond dosimeter, a PinPoint ionization chamber and gafchromic films, using a specific protocol. Both approaches, respectively based on a PDS and an absorbed dose to water at a point, were in good agreement in the 2 cm beam. Correction factors determined from Monte Carlo simulations and measured dose distributions were needed for this comparison. The calibration factor of the large ionization chamber in the 1 and 0.75 cm diameter beams were in good agreement within the uncertainties but a gap of -2.6 % was found with the one established in the 2 cm diameter beam. As a result, the DAP can be used if the sensitive surface is much larger than the beam section. (author) [fr

Dosimetric essay in dental radiology; Experiencia dosimetrica en radiologia odontologica

Energy Technology Data Exchange (ETDEWEB)

Lopez Salaberry, M [Ministerio de Industria, Energia y Mineria, Montevideo (Uruguay). Direccion Nacional de Tecnologia Nuclear; Dato Carfagna, A; Rodriguez Dorgia, R [Universidad de la Republica, Facultad de Odontologia , Montevideo (Uruguay)

1999-12-31

A neck study was observated in the tiroids glands,laryngeal zone, sensitive organs for the ionizing radiation for increase dental xray exams. Was selected 29th patients with radiography prescription complete (in the Odontology Faculty Clinics Uruguaian). It took radiographies with and without tiroids necklace and apron lead using dosemeters. Dosimetric studies had demonstrated good dose between patients. For measuring the radiation dose have been used TLD thermoluminescence dosimetric and Harshaw 6600 for read it. The thyroids necklace use and odontology postgrading for training course for dentistry was the two recommendations advised

Radiometric and dosimetric characteristics of HgI2 detectors

International Nuclear Information System (INIS)

Zaletin, V.M.; Krivozubov, O.V.; Torlin, M.A.; Fomin, V.I.

1988-01-01

The characteristics of HgI 2 detectors in x-ray and gamma detection in applications to radiometric and dosimetric monitoring and as portable instruments for such purposes was considered. Blocks with mosaic and sandwich structures were prepared and tested against each other and, for comparative purposes, against CdTe detectors for relative sensitivities at various gamma-quanta energies. Sensitivity dependencies on gamma radiation energy were plotted for the detector materials and structures as were current dependencies on the dose rate of x rays. Results indicated that the mercury iodide detectors could be used in radiometric and dosimetric measurements at gamma quantum energies up to and in excess of 1000 KeV

Revision of the dosimetric parameters of the CSM11 LDR Cs-137 source.

Science.gov (United States)

Otal, Antonio; Martínez-Fernández, Juan Manuel; Granero, Domingo

2011-03-01

The clinical use of brachytherapy sources requires the existence of dosimetric data with enough of quality for the proper application of treatments in clinical practice. It has been found that the published data for the low dose rate CSM11 Cs-137 source lacks of smoothness in some regions because the data are too noisy. The purpose of this study was to calculate the dosimetric data for this source in order to provide quality dosimetric improvement of the existing dosimetric data of Ballester et al . [1]. In order to obtain the dose rate distributions Monte Carlo simulations were done using the GEANT4 code. A spherical phantom 40 cm in radius with the Cs-137 source located at the centre of the phantom was used. The results from Monte Carlo simulations were applied to derive AAPM Task Group 43 dosimetric parameters: anisotropy function, radial dose function, air kerma strength and dose rate constant. The dose rate constant obtained was 1.094 ± 0.002 cGy h -1 U -1 . The new calculated data agrees within experimental uncertainties with the existing data of Ballester et al . but without the statistical noise of that study. The obtained data presently fulfills all the requirements of the TG-43U1 update and thus it can be used in clinical practice.

Determination of Absorbed Dose Using a Dosimetric Film

International Nuclear Information System (INIS)

Scarlat, F.; Scarisoreanu, A.; Oane, M.; Badita, E.; Mitru, E.

2009-01-01

This paper presents the absorbed dose measurements by means of the irradiated dosimetric reference films. The dose distributions were made by MULTIDATA film densitometer using RTD-4 software, in INFLPR Linear Accelerator Department

Use of a dosimetric system using a SMT phototransistor in the measurement for some dosimetric parameters in conventional radiotherapy

International Nuclear Information System (INIS)

Silva, J.O. da; Magalhaes, C.M.S. de; Santos, L.A.P.

2008-01-01

For monitoring the delivered dose in the patient undergoing a cancer treatment with high-energy ionizing radiation beams is necessary to use appropriate dosimeters for the beam control quality and if it is possible, to obtain the dose information during the treatment. For this, semiconductor-based devices are used because of their high spatial resolution and to be easy to handle in spite of the ionization chambers. Nowadays the bipolar phototransistors are being proposed as ionizing radiation detectors for presenting, beyond these characteristics, the signal amplification factor (gain). So, the aim of this work is to present the use of a dosimetric system using a SMT phototransistor in the measurement for some dosimetric parameters in conventional radiotherapy: the field factor and the off-axis ratio. The phototransistors readings were compared with ones obtained from a PTW 23343 Markus chamber, under the same conditions. (author)

Internal dosimetric evaluation due to uranium aerosols

International Nuclear Information System (INIS)

Garcia Aguilar Juan; Delgado Avila Gustavo

1991-01-01

The present work has like object to carry out the internal dosimetric evaluation to the occupationally exposed personnel, due to the inhalation of aerosols of natural uranium and enriched in the pilot plant of nuclear fuel production of the National Institute of Nuclear Research

CaSO4: Dy + Teflon dosimetric pellets for X, beta and gamma radiation detection

International Nuclear Information System (INIS)

Campos, L.L.; Lima, M.F.

1987-08-01

CaSO 4 : Dy + TEFLON dosimetric pellets with high sensitivity and low cost for X, beta and gamma radiation monitoring were studied and developed by the Dosimetric Material Production Laboratory of the Radiological Protection Departament and are disposable for sale. The thickness of the pellets are suitable for X, beta and gamma radiation measurements. The dosimetric properties of these pellets were determined and presented in this work. The results show the usefulness of 0,20mm thick pellets for beta radiation monitoring and 0,80mm thick pellets for x and gamma radiation detection. (Author) [pt

Study of dosimetric systems-ferrous sulfate-ferric sulfate, glass slides and dyed aqueous solutions

International Nuclear Information System (INIS)

Fernandes, L.

1979-01-01

The effect of some variables which can effect the preparation of the ferrous sulfate used as dosimetric solution has been studied. Among these variables the purity of the water used for the preparation of the solution and the presence (or absence) of oxygen in the dosimetric solution were considered. The dose rate distribution according to the transverse and longitudinal sections of the Co 60 irradiator was studied experimentally, using the dosimetric solution, and theoretically, using a computer program (KIFE). The results obtained with the ferrous sulface dosimetric solution were used as reference for the study of the application of EM and MSG glass slide as a dosimetric system. For this purpose the effects of the weakening of the coloration induced in the glass by gamma rays (Co 60 ) and the relationship between the absorbed dose of radiation and the ratio between the variation in absorbation value and the thickness of the glass irradiated, were studied. A study was also made of the use of the dye indicators bromothymol-blue, methyl-orange, Congo-red, neutral-red and p-nitrophenol, in aqueous solution, for radiation dose measurements. The bleaching of each indicator solution, under gamma-radiation (Co 60 ) was studied in oxygen and nitrogen atmospheres.(Author) [pt

Calibration of instrument and personnel monitoring in radiological protection

International Nuclear Information System (INIS)

Abdul Aziz Mohamad Ramli; Wan Saffiey Wan Abdullah

1987-01-01

It is difficult to choose radioprotection equipments that are not too expensive and suit the purpose. Some of the dosimetric characteristics of good dosemeters outlined by ISO 4071-1978 (E) namely scale linearity, energy dependence, radiation quality dependence and angular dependence for some of the commercially available dosemeters are discussed. The calibration procedures practised at the National Secondary Standard Dosimetry Laboratory (SSDL), of the Nuclear Energy Unit (NEU) is also explained. The radiological equipments for personnel monitoring such as film badge and TLD are widely used to estimate the radiation dose delivered to the whole or partial body of a personnel. Both of the personnel monitoring procedures have been established at the NEU. The objective, use and maintenance of the devices are also discussed in detail. The evaluation of the monthly dose received by a personnel from various establishments in the country are also presented. (author). 17 figs

Overview of individual monitoring and calibration of radiation monitors in the country; Panorama da monitoração individual e calibração de monitores de radiação no país

Energy Technology Data Exchange (ETDEWEB)

Alencar, M.A.V.; Patrão, K.C.S.; Ferreira, P.R.R.; Matta, L.E.S.C.; Peres, S.S.; Silva, F.C.A. da, E-mail: vallim@ird.gov.br [Instituto de Radioproteção e Dosimetria (IRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil)

2017-07-01

Since 1995, the Institute of Radioprotection and Dosimetry (IRD/CNEN-RJ) has been responsible for the certification of instrument calibration laboratories and monitoring of occupationally exposed individuals (IOE), as well as monitoring and auditing the activities of eleven individual monitoring services (SMIE) and six instrument calibration laboratories (LCI) in the country. The work presents an overview of the number of IOE monitored and calibrated radiation monitors, from 2008 to 2016. The data were obtained through a census with the SMIE and LCI. The results show that in this period there was an increase of around 47% in the total number of IOE monitored and approximately 40% in the number of instrument calibrations. It was also observed the reduction of dosimetric film use and the beginning of OSLD monitoring.

Fundamental limits of radio interferometers: calibration and source parameter estimation

OpenAIRE

Trott, Cathryn M.; Wayth, Randall B.; Tingay, Steven J.

2012-01-01

We use information theory to derive fundamental limits on the capacity to calibrate next-generation radio interferometers, and measure parameters of point sources for instrument calibration, point source subtraction, and data deconvolution. We demonstrate the implications of these fundamental limits, with particular reference to estimation of the 21cm Epoch of Reionization power spectrum with next-generation low-frequency instruments (e.g., the Murchison Widefield Array -- MWA, Precision Arra...

Dosimetric monitoring in Ukraine - Present status and path to the future

International Nuclear Information System (INIS)

Chumak, V.; Boguslavskaya, A.

2007-01-01

Despite wide use of nuclear energy and radiation sources in industry and medicine, there is no centralised dose accounting system in Ukraine; existing dosimetry services operate obsolete manual thermoluminescence dosemeter (TLD) readers and do not meet modern proficiency standards. Currently, dosimetric monitoring is required for ∼42,000 occupationally exposed workers, including 9100 in medicine, 17,000 employees of nuclear power plants and ∼16,000 workers dealing with other sources of occupational exposure. This article presents the plan of elaboration of the United System for monitoring and registration of individual doses which has the aim of harmonisation of individual monitoring in Ukraine through securing methodical unity; scientific and methodological guidance of individual dosimetric control; procurement of common technical policy regarding nomenclature and operation of instrumentation; implementation of quality assurance programmes; development and support of information infrastructure, in particular operation of the national registry of individual doses; training and certification of personnel engaged in the system of individual dosimetric monitoring. (authors)

A new fully integrated X-ray irradiator system for dosimetric research

International Nuclear Information System (INIS)

Richter, D.; Mittelstraß, D.; Kreutzer, S.; Pintaske, R.; Dornich, K.; Fuchs, M.

2016-01-01

A fully housed X-ray irradiator was developed for use within lexsyg or Magnettech desktop equipment. The importance of hardening of the low energy photon radiation is discussed, its performance and feasibility is empirically shown and sustained by basic numerical simulations. Results of the latter for various materials are given for different X-ray source settings in order to provide estimates on the required setup for the irradiation of different geometries and materials. A Si-photodiode provides real-time monitoring of the X-ray-irradiator designed for use in dosimetric dating and other dosimetric application where irradiation of small samples or dosemeters is required. - Highlights: • Bench top X-ray irradiator provides variable dose-rates. • Simulation of low energy photon irradiation and hardening of X-ray. • Al-hardening for the irradiation of H_2O, BeO, Al_2O_3, quartz, feldspars and zircon. • Dosimetric dating equipment for luminescence and ESR.

ESR dosimetric properties of modern coral reef

Energy Technology Data Exchange (ETDEWEB)

Sharaf, M.A. E-mail: mokhtar_sharaf@yahoo.com; Hassan, Gamal M

2004-06-01

Modern coral reef samples from Egypt were irradiated with {sup 60}Co{gamma}-rays to study radicals for dosimetric materials with electron spin resonance (ESR). The ESR spectrum for the radical species in unirradiated coral is characterized by four signals with spectroscopic splitting factors of g=2.0056, 2.0030, 2.0006 and 1.997. The signal at g=2.0006{+-}0.0005 is ascribed to free rotation CO{sub 2}{sup -} radicals and used as a dosimetric one. The response to {gamma}-ray doses ranging from 5 to 10{sup 3} Gy and the thermal stability has been studied. The number of free radicals per 100 eV (G-value) was found to be 0.45 {+-} 0.1 and 0.9 {+-} 0.18 for coral and alanine, respectively. The lifetime of radicals and the activation energy were estimated from Arrhenius plots to be approximately 8 x 10{sup 5} {+-} 1.6 x 10{sup 5} years, and 1.12 eV, respectively.

Researches, development and characterization of dosimetric materials for monitoring in irradiation processes with high doses; Pesquisa, desenvolvimento e caracterizacao de materiais dosimetricos para monitoramento em processos de irradiacao com doses altas

Energy Technology Data Exchange (ETDEWEB)

Galante, Ana Maria Sisti

2003-07-01

Dosimetric materials that can be produced in Brazil with material acquired in the national market to replace the imported dosimeters used in radiation processing were developed in this work. Mixtures of potassium nitrate and sensitizers compounds as manganese dioxide, barium nitrate and potassium bromide were prepared in the pellet form. Dosimetric characteristics such as dose-response useful range, sensitivity, environmental conditions and dose rate influences were evaluated in {sup 60}Co gamma radiation fields. Dyed polymethylmethacrylate detectors were also produced and its dosimetric characteristics were evaluated. The main characteristics evaluated in this case were: dose response useful range sensitivity, environmental conditions, dose rate influences and radiation energy dependence in gamma radiation fields and accelerated electrons beam of 0.8 to 1.5 MeV. The applied analytic technique was spectrophotometry. The calibration was performed in the irradiation facilities belonging to IPEN and certified by the International Atomic Energy Agency by means of the program IDAS (International Dose Assurance Service ) using the Fricke dosimeter. The mixture of potassium nitrate and manganese dioxide presented the best results and a wide dose range between 200 and 600 kGy. The response of the developed polymethylmethacrylate detectors are similar to the imported detectors and the dose range is characteristic to each detector and depends on the dye added in its formulation. (author)

Multi-dimensional dosimetric verification of stereotactic radiotherapy for uveal melanoma using radiochromic EBT film

International Nuclear Information System (INIS)

Sturtewagen, E.; Fuss, M.; Georg, D.; Paelinck, L.; Wagter, C. de

2008-01-01

Since 1997, linac based stereotactic radiotherapy (SRT) of uveal melanoma has been continuously developed at the Department of Radiotherapy, Medical University Vienna. The aim of the present study was (i) to test a new type of radiochromic film (Gafchromic EBT) for dosimetric verification of class solutions for these treatments and (ii) to verify treatment plan acceptance criteria, which are based on gamma values statisitcs. An EPSON Expression 1680 Pro flat bed scanner was utilized for film reading. To establish a calibration curve, films were cut in squares of 2 x 2 cm 2 , positioned at 5 cm depth in a solid water phantom and were irradiated with different dose levels (0.5 and 5 Gy) in a 5 x 5 cm 2 field at 6 MV. A previously developed solid phantom (polystyrene) was used with overall dimensions corresponding to an average human head. EBT films were placed at four different depths (10, 20, 25 and 30 mm) and all films were irradiated simultaneously. Four different treatment plans were verified that resemble typical clinical situations. These plans differed in irradiation technique (conformal mMLC or circular arc SRT) and in tumour size (PTV of 1 or 2.5 cm 3 ). In-house developed software was applied to calculate gamma (γ) index values and to perform several statistical operations (e.g. γ-area histograms). At depths of 10 mm γ 1% (γ-value where 1% of the points have an equal or higher value in the region of interest) were between 1-3 and maximum γ > 1 (% of γ-values > 1 in the region of interest) areas were almost 30%. At larger depths, i.e. more close to the isocenter, γ 1% was > 1 areas were mostly < 5%. Average γ values were about 0.5. Besides the compromised accuracy in the buildup region, previously defined IMRT acceptance criteria [Stock et al., Phys. Med. Biol. 50 (2005) 399-411] could be applied as well to SRT. Radiochromic EBT films, in combination with a flat-bed scanner, were found to be an ideal multidimensional dosimetric tool for treatment

Dosimetric effects of rotational offsets in stereotactic body radiation therapy (SBRT) for lung cancer

International Nuclear Information System (INIS)

Yang, Yun; Catalano, Suzanne; Kelsey, Chris R.; Yoo, David S.; Yin, Fang-Fang; Cai, Jing

2014-01-01

To quantitatively evaluate dosimetric effects of rotational offsets in stereotactic body radiation therapy (SBRT) for lung cancer. Overall, 11 lung SBRT patients (8 female and 3 male; mean age: 75.0 years) with medially located tumors were included. Treatment plans with simulated rotational offsets of 1°, 3°, and 5° in roll, yaw, and pitch were generated and compared with the original plans. Both clockwise and counterclockwise rotations were investigated. The following dosimetric metrics were quantitatively evaluated: planning target volume coverage (PTV V 100% ), max PTV dose (PTV D max ), percentage prescription dose to 0.35 cc of cord (cord D 0.35 cc ), percentage prescription dose to 0.35 cc and 5 cc of esophagus (esophagus D 0.35 cc and D 5 cc ), and volume of the lungs receiving at least 20 Gy (lung V 20 ). Statistical significance was tested using Wilcoxon signed rank test at the significance level of 0.05. Overall, small differences were found in all dosimetric matrices at all rotational offsets: 95.6% of differences were 100% , PTV D max , cord D 0.35 cc , esophagus D 0.35 cc , esophagus D 5 cc , and lung V 20 was − 8.36%, − 6.06%, 11.96%, 8.66%, 6.02%, and − 0.69%, respectively. No significant correlation was found between any dosimetric change and tumor-to-cord/esophagus distances (R 2 range: 0 to 0.44). Larger dosimetric changes and intersubject variations were observed at larger rotational offsets. Small dosimetric differences were found owing to rotational offsets up to 5° in lung SBRT for medially located tumors. Larger intersubject variations were observed at larger rotational offsets

Dosimetric commissioning and quality assurance of scanned ion beams at the Italian National Center for Oncological Hadrontherapy

Energy Technology Data Exchange (ETDEWEB)

Mirandola, Alfredo, E-mail: mirandola@cnao.it; Molinelli, S.; Vilches Freixas, G.; Mairani, A.; Gallio, E.; Panizza, D.; Russo, S.; Ciocca, M. [Fondazione CNAO, strada Campeggi 53, Pavia 27100 (Italy); Donetti, M. [INFN, Torino 10125, Italy and Fondazione CNAO, strada Campeggi 53, Pavia 27100 (Italy); Magro, G. [INFN–Dipartimento di Fisica, Università degli Studi di Pavia, Via U. Bassi 6, Pavia 27100, Italy and Fondazione CNAO, strada Campeggi 53, Pavia 27100 (Italy); Giordanengo, S. [INFN, Torino 10125 (Italy); Orecchia, R. [Fondazione CNAO, strada Campeggi 53, Pavia 27100, Italy and Radiotherapy Division, European Institute of Oncology, Via Ripamonti 435, Milano 20141 (Italy)

2015-09-15

Purpose: To describe the dosimetric commissioning and quality assurance (QA) of the actively scanned proton and carbon ion beams at the Italian National Center for Oncological Hadrontherapy. Methods: The laterally integrated depth-dose-distributions (IDDs) were acquired with the PTW Peakfinder, a variable depth water column, equipped with two Bragg peak ionization chambers. FLUKA Monte Carlo code was used to generate the energy libraries, the IDDs in water, and the fragment spectra for carbon beams. EBT3 films were used for spot size measurements, beam position over the scan field, and homogeneity in 2D-fields. Beam monitor calibration was performed in terms of number of particles per monitor unit using both a Farmer-type and an Advanced Markus ionization chamber. The beam position at the isocenter, beam monitor calibration curve, dose constancy in the center of the spread-out-Bragg-peak, dose homogeneity in 2D-fields, beam energy, spot size, and spot position over the scan field are all checked on a daily basis for both protons and carbon ions and on all beam lines. Results: The simulated IDDs showed an excellent agreement with the measured experimental curves. The measured full width at half maximum (FWHM) of the pencil beam in air at the isocenter was energy-dependent for both particle species: in particular, for protons, the spot size ranged from 0.7 to 2.2 cm. For carbon ions, two sets of spot size are available: FWHM ranged from 0.4 to 0.8 cm (for the smaller spot size) and from 0.8 to 1.1 cm (for the larger one). The spot position was accurate to within ±1 mm over the whole 20 × 20 cm{sup 2} scan field; homogeneity in a uniform squared field was within ±5% for both particle types at any energy. QA results exceeding tolerance levels were rarely found. In the reporting period, the machine downtime was around 6%, of which 4.5% was due to planned maintenance shutdowns. Conclusions: After successful dosimetric beam commissioning, quality assurance measurements

Dosimetric commissioning and quality assurance of scanned ion beams at the Italian National Center for Oncological Hadrontherapy

International Nuclear Information System (INIS)

Mirandola, Alfredo; Molinelli, S.; Vilches Freixas, G.; Mairani, A.; Gallio, E.; Panizza, D.; Russo, S.; Ciocca, M.; Donetti, M.; Magro, G.; Giordanengo, S.; Orecchia, R.

2015-01-01

Purpose: To describe the dosimetric commissioning and quality assurance (QA) of the actively scanned proton and carbon ion beams at the Italian National Center for Oncological Hadrontherapy. Methods: The laterally integrated depth-dose-distributions (IDDs) were acquired with the PTW Peakfinder, a variable depth water column, equipped with two Bragg peak ionization chambers. FLUKA Monte Carlo code was used to generate the energy libraries, the IDDs in water, and the fragment spectra for carbon beams. EBT3 films were used for spot size measurements, beam position over the scan field, and homogeneity in 2D-fields. Beam monitor calibration was performed in terms of number of particles per monitor unit using both a Farmer-type and an Advanced Markus ionization chamber. The beam position at the isocenter, beam monitor calibration curve, dose constancy in the center of the spread-out-Bragg-peak, dose homogeneity in 2D-fields, beam energy, spot size, and spot position over the scan field are all checked on a daily basis for both protons and carbon ions and on all beam lines. Results: The simulated IDDs showed an excellent agreement with the measured experimental curves. The measured full width at half maximum (FWHM) of the pencil beam in air at the isocenter was energy-dependent for both particle species: in particular, for protons, the spot size ranged from 0.7 to 2.2 cm. For carbon ions, two sets of spot size are available: FWHM ranged from 0.4 to 0.8 cm (for the smaller spot size) and from 0.8 to 1.1 cm (for the larger one). The spot position was accurate to within ±1 mm over the whole 20 × 20 cm"2 scan field; homogeneity in a uniform squared field was within ±5% for both particle types at any energy. QA results exceeding tolerance levels were rarely found. In the reporting period, the machine downtime was around 6%, of which 4.5% was due to planned maintenance shutdowns. Conclusions: After successful dosimetric beam commissioning, quality assurance measurements

ESR dosimetric properties of some biomineral materials

International Nuclear Information System (INIS)

Hassan, Gamal M.; Sharaf, M.A.

2005-01-01

Dosimetric properties of g-irradiated modern coral and bioactive glass (Bio-G) samples analyzed with electron spin resonance (ESR) have been separately reported (Hassan et al., 2004; Sharaf and Hassan, 2004) and compared with alanine. These are combined here to allow a three-way comparison between these materials

ESR dosimetric properties of some biomineral materials

Energy Technology Data Exchange (ETDEWEB)

Hassan, Gamal M. [Department of Ionizing Radiation Metrology, National Institute for Standards (NIS), Tersa Street, El-Haram, El-Giza, P.O. Box 136 Giza, El-Giza (Egypt)]. E-mail: gamalhassan65@hotmail.com; Sharaf, M.A. [Department of Ionizing Radiation Metrology, National Institute for Standards (NIS), Tersa Street, El-Haram, El-Giza, P.O. Box 136 Giza, El-Giza (Egypt)

2005-02-01

Dosimetric properties of g-irradiated modern coral and bioactive glass (Bio-G) samples analyzed with electron spin resonance (ESR) have been separately reported (Hassan et al., 2004; Sharaf and Hassan, 2004) and compared with alanine. These are combined here to allow a three-way comparison between these materials.

Examining the relationship between pre- and postimplant geometry in prostate low-dose-rate brachytherapy and its correlation with dosimetric quality using the similarity concept.

Science.gov (United States)

Todor, Dorin A; Anscher, Mitchell S; Karlin, Jeremy D; Hagan, Michael P

2014-01-01

This is a retrospective study in which we define multiple metrics for similarity and then inquire on the relationship between similarity and currently used dosimetric quantities describing preimplant and postimplant plans. We analyzed a unique cohort of 94 consecutively performed prostate seed implant patients, associated with excellent dosimetric and clinical outcomes. For each patient, an ultrasound (US) preimplant and two CT postimplant (Day 0 and Day 30) studies were available. Measures for similarity were created and computed using feature vectors based on two classes of moments: first, invariant to rotation and translation, and the second polar-radius moments invariant to rotation, translation, and scaling. Both similarity measures were calibrated using controlled perturbations (random and systematic) of seed positions and contours in different size implants, thus producing meaningful numerical threshold values used in the clinical analysis. An important finding is that similarity, for both seed distributions and contours, improves significantly when scaling invariance is added to translation and rotation. No correlation between seed and contours similarity was found. In the setting of preplanned prostate seed implants using preloaded needles, based on our data, similarity between preimplant and postimplant plans does not correlate with either minimum dose to 90% of the volume of the prostate or analogous similarity metrics for prostate contours. We have developed novel tools and metrics, which will allow practitioners to better understand the relationship between preimplant and postimplant plans. Geometrical similarity between a preplan and an actual implant, although useful, does not seem to be necessary to achieve minimum dose to 90% of the volume of the prostate-good dosimetric implants. Copyright © 2014 American Brachytherapy Society. All rights reserved.

Geometric factors influencing dosimetric sparing of the parotid glands using IMRT

International Nuclear Information System (INIS)

Hunt, Margie A.; Jackson, Andrew; Narayana, Ashwatha; Lee, Nancy

2006-01-01

Purpose/Objective: To determine the relationship between the parotid volume, parotid-planning target volume (PTV) overlap, and dosimetric sparing of the parotid with intensity-modulated radiation therapy (IMRT). Methods and Materials: Parotid data were collected retrospectively for 51 patients treated with simultaneous boost IMRT. Unresectable patients received 54 or 59.4 Gy to subclinical disease, 70 Gy to gross disease. Patients treated postoperatively received 54, 60, and 66 Gy to low-risk, high-risk, and tumor bed regions. Volume and mean dose of each gland and gland segments outside of and overlapping the PTV were collected. Proximity of each gland to each PTV was recorded. Results: Dosimetric sparing (mean dose ≤26.5 Gy) was achieved in 66 of 71 glands with ≤21% parotid-PTV overlap and 8 of 23 glands with >21% overlap (p = 21%. Median mean dose was 25.9 Gy to glands overlapping PTV 54 or PTV 59 alone and 30.0 Gy to those abutting PTV 7 (p 7 was associated with higher parotid dose, satisfactory sparing was achieved in 24 of 43 ipsilateral glands. Conclusions: Dosimetric sparing of the parotid is feasible when the parotid-PTV overlap is less than approximately 20%. With more overlap, sparing may result in low doses within the overlap region, possibly leading to inadequate PTV coverage. Gland proximity to the high-dose PTV is associated with higher mean dose but does not always preclude dosimetric sparing

Calibration factor or calibration coefficient?

International Nuclear Information System (INIS)

Meghzifene, A.; Shortt, K.R.

2002-01-01

Full text: The IAEA/WHO network of SSDLs was set up in order to establish links between SSDL members and the international measurement system. At the end of 2001, there were 73 network members in 63 Member States. The SSDL network members provide calibration services to end-users at the national or regional level. The results of the calibrations are summarized in a document called calibration report or calibration certificate. The IAEA has been using the term calibration certificate and will continue using the same terminology. The most important information in a calibration certificate is a list of calibration factors and their related uncertainties that apply to the calibrated instrument for the well-defined irradiation and ambient conditions. The IAEA has recently decided to change the term calibration factor to calibration coefficient, to be fully in line with ISO [ISO 31-0], which recommends the use of the term coefficient when it links two quantities A and B (equation 1) that have different dimensions. The term factor should only be used for k when it is used to link the terms A and B that have the same dimensions A=k.B. However, in a typical calibration, an ion chamber is calibrated in terms of a physical quantity such as air kerma, dose to water, ambient dose equivalent, etc. If the chamber is calibrated together with its electrometer, then the calibration refers to the physical quantity to be measured per electrometer unit reading. In this case, the terms referred have different dimensions. The adoption by the Agency of the term coefficient to express the results of calibrations is consistent with the 'International vocabulary of basic and general terms in metrology' prepared jointly by the BIPM, IEC, ISO, OIML and other organizations. The BIPM has changed from factor to coefficient. The authors believe that this is more than just a matter of semantics and recommend that the SSDL network members adopt this change in terminology. (author)

Comparative dosimetric study in the estimation of the dose rate of the Transelektro LGI-01 irradiator; Estudio dosimetrico comparativo en la estimacion de la razon de dosis del irradiador Transelektro LGI-01

Energy Technology Data Exchange (ETDEWEB)

Carrasco A, H.; Urena N, F.F. [ININ, A.P. 18-1027, 11801 Mexico D.F. (Mexico)

2004-07-01

The {sup 60} Co TRANSELEKTRO, model LGI-0 1, Hungarian, is similar to the Canadian Gamma cell. The evaluation of the dose ratio in the geometric center of the exposition chamber of the LGI-0 1 is presented in this paper. In order to do this two types of dosimeters were used: the alanine, and the L8-C 1 red acrylic (Canadian). Three dosimeters of each type were irradiated at 1, 2, 3, 4, 5, 6, 7 and 8 h. The respective intensities and absorbencies were measured and used to determine the proper absorbed doses and the dose ratio. The results obtained with both dosimeters were compared with the ratio dose that was reported by the Secondary Laboratory of Dosimetric Calibration of the Metrology Department of the ININ, which used a ionization chamber for the calibration of the LGI-0 1. The alanine dosemeter showed a {+-} 1.3% dispersion while with the acrylic dosemeter the dispersion was of {+-} 3.2%, with respect to the value reported by the authorized Calibration Laboratory. This paper was also used to update the calibration table of the L8-C1 red acrylic. (Author)

Dosimetric effects of rotational offsets in stereotactic body radiation therapy (SBRT) for lung cancer

Energy Technology Data Exchange (ETDEWEB)

Yang, Yun; Catalano, Suzanne; Kelsey, Chris R.; Yoo, David S.; Yin, Fang-Fang; Cai, Jing, E-mail: jing.cai@duke.edu

2014-04-01

To quantitatively evaluate dosimetric effects of rotational offsets in stereotactic body radiation therapy (SBRT) for lung cancer. Overall, 11 lung SBRT patients (8 female and 3 male; mean age: 75.0 years) with medially located tumors were included. Treatment plans with simulated rotational offsets of 1°, 3°, and 5° in roll, yaw, and pitch were generated and compared with the original plans. Both clockwise and counterclockwise rotations were investigated. The following dosimetric metrics were quantitatively evaluated: planning target volume coverage (PTV V{sub 100%}), max PTV dose (PTV D{sub max}), percentage prescription dose to 0.35 cc of cord (cord D{sub 0.35} {sub cc}), percentage prescription dose to 0.35 cc and 5 cc of esophagus (esophagus D{sub 0.35} {sub cc} and D{sub 5} {sub cc}), and volume of the lungs receiving at least 20 Gy (lung V{sub 20}). Statistical significance was tested using Wilcoxon signed rank test at the significance level of 0.05. Overall, small differences were found in all dosimetric matrices at all rotational offsets: 95.6% of differences were < 1% or < 1 Gy. Of all rotational offsets, largest change in PTV V{sub 100%}, PTV D{sub max}, cord D{sub 0.35} {sub cc}, esophagus D{sub 0.35} {sub cc}, esophagus D{sub 5} {sub cc}, and lung V{sub 20} was − 8.36%, − 6.06%, 11.96%, 8.66%, 6.02%, and − 0.69%, respectively. No significant correlation was found between any dosimetric change and tumor-to-cord/esophagus distances (R{sup 2} range: 0 to 0.44). Larger dosimetric changes and intersubject variations were observed at larger rotational offsets. Small dosimetric differences were found owing to rotational offsets up to 5° in lung SBRT for medially located tumors. Larger intersubject variations were observed at larger rotational offsets.

Basic principles and practices of integrated dosimetric passportization of the settlements in Ukraine

International Nuclear Information System (INIS)

Lyikhtar'ov, Yi.A.; Kovgan, L.M.; Masyuk, S.V.; Yivanova, O.M.; Chepurnij, M.Yi.; Bojko, Z. N.; Gerasimenko, V.B.

2015-01-01

The objective of the review is to demonstrate the results of dosimetric passportization (performed in 1991- 2014) for the settlements of Ukraine which suffered from radioactive contamination caused by the Chornobyl accident. The dosimetric passportization played a key role in the National program on the liquidation of after- math of the Chornobyl accident through all stages of the current radiation situation control and decision support touching upon various types of interventions and social benefits to the population of radioactively contaminated areas. The works being performed under dosimetric passportization did not have analogues among the researches which took place after other large-scale industrial and municipal accidents as well their scales as the duration of both radio-ecological and dosimetric monitoring. The new methodological approaches to the assessment of so-called passport doses of a settlement as well as to the definition of the concept of annual dose being the dose used to make decisions for providing both direct and indirect emergency countermeasures for the settlements of Ukraine became pioneering ones. During all the post-accident period there were issued sixteen collections of general dosimetric passportization data which accumulate the results of hundreds of thousands spectrometric, radiochemical and radiation levels measurements and WBC measurements carried out in 1991-2014. The annual passport doses calculated on the basis of these measurements (including their components) are unique information that quantifies the level and time dynamics of the radiation situation for each of the 2161 settlements of 74 districts in 12 regions during all the post-accident period. Thanks to the works of dosimetric passportization of the settlements of Ukraine there were created databases to be unique in their structure and content with quantitative characteristics of the territorial and temporal distribution, the dynamics of changes of a number of important

Using LabVIEW to facilitate calibration and verification for respiratory impedance plethysmography.

Science.gov (United States)

Ellis, W S; Jones, R T

1991-12-01

A system for calibrating the Respitrace impedance plethysmograph was developed with the capacity to quantitatively verify the accuracy of calibration. LabVIEW software was used on a Macintosh II computer to create a user-friendly environment, with the added benefit of reducing development time. The system developed enabled a research assistant to calibrate the Respitrace within 15 min while achieving an accuracy within the normally accepted 10% deviation when the Respitrace output is compared to a water spirometer standard. The system and methods described were successfully used in a study of 10 subjects smoking cigarettes containing marijuana or cocaine under four conditions, calibrating all subjects to 10% accuracy within 15 min.

Dosimetric comparison of intensity modulated radiosurgery with dynamic conformal arc radiosurgery for small cranial lesions

Directory of Open Access Journals (Sweden)

Juan F Calvo-Ortega

2016-01-01

Conclusions: We have shown that IMRS provides the dosimetric advantages compared with DCARS. Based on the dosimetric findings in this study, fixed gantry IMRS technique can be adopted as a standard procedure for cranial SRS when micro-MLC technology is not available on the linear accelerator.

Thermoluminescence dosimetric characteristics of thulium doped ZnB2O4 phosphor

International Nuclear Information System (INIS)

Annalakshmi, O.; Jose, M.T.; Madhusoodanan, U.; Subramanian, J.; Venkatraman, B.; Amarendra, G.; Mandal, A.B.

2014-01-01

Polycrystalline powder samples of rare earth doped Zinc borates were synthesized by high temperature solid state diffusion technique. Dosimetric characteristics of the phosphor like thermoluminescence glow curve, TL emission spectra, dose–response, fading studies, reproducibility and reusability studies were carried out on the synthesized phosphors. Among the different rare earth doped phosphors, thulium doped zinc borate was found to have a higher sensitivity. Hence detailed dosimetric characteristics of this phosphor were carried out. It is observed that the dose–response is linear from 10 mGy to 10 3 Gy in this phosphor. EPR measurements were carried out on unirradiated, gamma irradiated and annealed phosphors to identify the defect centers responsible for thermoluminescence. A TL model is proposed based on the EPR studies in these materials. Kinetic parameters were evaluated for the dosimetric peaks using various methods. The experimental results show that this phosphor can have potential applications in radiation dosimetry applications. -- Highlights: • Polycrystalline powder samples of rare earth doped zinc borates were synthesized. • Thulium was observed to be the most efficient dopant in ZnB 2 O 4 lattice. • TL intensity of the dosimetric peak is around 20 times that of TLD-100. • Based on EPR studies a TL mechanism is proposed in zinc borate. • Deconvolution of the glow curve carried out

Dosimetric characterization of a bi-directional micromultileaf collimator for stereotactic applications.

Science.gov (United States)

Bucciolini, M; Russo, S; Banci Buonamici, F; Pini, S; Silli, P

2002-07-01

A 6 MV photon beam from Linac SL75-5 has been collimated with a new micromultileaf device that is able to shape the field in the two orthogonal directions with four banks of leaves. This is the first clinical installation of the collimator and in this paper the dosimetric characterization of the system is reported. The dosimetric parameters required by the treatment planning system used for the dose calculation in the patient are: tissue maximum ratios, output factors, transmission and leakage of the leaves, penumbra values. Ionization chambers, silicon diode, radiographic films, and LiF thermoluminescent dosimeters have been employed for measurements of absolute dose and beam dosimetric data. Measurements with different dosimeters supply results in reasonable agreement among them and consistent with data available in literature for other models of micromultileaf collimator; that permits the use of the measured parameters for clinical applications. The discrepancies between results obtained with the different detectors (around 2%) for the analyzed parameters can be considered an indication of the accuracy that can be reached by current stereotactic dosimetry.

Dosimetric study for characterization of a postal system of quality control in brachytherapy

International Nuclear Information System (INIS)

Alves, Victor Gabriel Leandro; Queiroz Filho, Pedro Pacheco de; Santos, Denison de Souza; Begalli, Marcia

2009-01-01

This work presents a dosimetric study of a postal system, to be developed for measurements of brachytherapy. It was projected a PMMA phantom with orifices for insertion of the high dose 192 Ir source and the T L dosemeters. The system was characterized with using of Monte Carlo simulations, using the dosimetric magnitudes defined at the T G-43 of AAPM, as function of radial dose g(f)

Characterization of different qualities in X-rays, for instruments calibration in radiological protection

International Nuclear Information System (INIS)

Cejudo A, J.; Tovar M, V. M.; Vergara M, F.

2010-09-01

In the Secondary Laboratory of Dosimetric Calibration in Mexico was realized the qualities characterization of the series X-rays RQR reported in the International Code of Practices in Dosimetry and Diagnostic Radiology No. 457, using attenuator filters of high purity aluminum and ionizing radiation equipment of inherent filtration of 4 mm Be with and emergent X-radiation beam of 40 grades. For the attenuation was used a geometric arrangement with three beam limiters and a monitor camera prepared on the established form in the mentioned technical report, and a spherical ionization chamber with collection volume of 3.6 cm 3 , aligning its geometric center with the focus of X-rays tube to get that the incident radiation direction will be perpendicular to the ionization chamber. From the perspective of the radiological protection is important to know the X-radiation quality for the application dedicated to the instruments calibration and can to give to these the traceability to a reference laboratory, this way the quality combination and reference chamber can give as a result a procedure for the evaluation of the entrance in surface dose to estimate the dose orientate levels, specified in the basic standards of safety. (Author)

Characteristic parameters analysis on diagnostic X-ray beams for dosemeter calibration

International Nuclear Information System (INIS)

Oliveira, Paulo Marcio Campos de

2008-01-01

Ionizing radiation metrology is the base to achieve reliable dose measurements in ali areas; it is also part of the framework that is established to assure radiation protection procedures in order to avoid or minimize the harmful biological effect that may be caused by ionizing radiation. A well done metrology means the use of reliable instruments that comply with standard performance requirements worldwide accepted. Those instruments are expected to be calibrated by Metrology Laboratories under well defined conditions. The International Electrotechnical Commission (IEC) in Standard 61267 established the reference radiations for medical diagnostic x-ray equipment that are recommended to be used for calibrating dosimetric systems for diagnostic dosimetry. In this work, X-ray beam qualities were established in a Calibration Laboratory and their characteristics were analyzed through the measurement of beam parameters like inherent tube filtration, beam uniformity and field size, energy spectra and peak voltage for additional filtration with 94.425 por cent and 99.999 por cent purity filters. Also, the first half-value layer and the homogeneity coefficient were measured for the three RQR 2, RQR 6 and RQR 10 IEC beam qualities and they were analyzed according to the IEC standard. Air-kerma measurements were carried out with an ionization chamber that had its reliability confirmed through repetition and reproducibility reading tests. In 50 sets of measurements the maximum standard deviation found of 10 successive readings was 0.19 %; the maximum shift of the reading mean value at a fixed geometry condition was 0.80 % with an overall standard deviation of 0.23 %. Results showed that the use of different purity filters did not cause a relevant influence on the beam energy spectra. An ionization chamber was also calibrated against a standard dosimeter in ali implemented reference radiations and the relevant sources of uncertainties were estimated. Calibration could be done

Management and processing of dosimetric data of workers exposed to ionizing radiation

International Nuclear Information System (INIS)

Rasoarimalala, T.

2012-01-01

The Madagascar - INSTN Radiation protection and Dosimetry Department use the reader HARSHAW TLD 6600 for workers doses reading. Although the performance of this device, manual works is required to store and to maintain the dosimetric data after reading and to note the TLDs sent to the establishments. To avoid these manual works, this present work proposes computer programs written in Python and using SQLite software. One of the programs in python retrieves dose values after reading and transfers directly these doses in the workers database. The use of SQLite software provides a way for the dosimetric data management and the TLDs movement monitoring. The other program assesses estimation of the dose received by worker through a trend curve for workers dosimetric monitoring. The calculated differences of this curve over the curve connecting all points are less than 20%, acceptable limit in radiation protection for TLDs. This present work presents then significances for the personnel occupying individual monitoring of ionizing radiation workers and for these workers too. [fr

Monitoring Dosimetric Impact of Weight Loss With Kilovoltage (KV) Cone Beam CT (CBCT) During Parotid-Sparing IMRT and Concurrent Chemotherapy

Energy Technology Data Exchange (ETDEWEB)

Ho, Kean Fatt, E-mail: hokeanfatt@hotmail.com [Academic Radiation Oncology, The Christie NHS Foundation Trust, Manchester (United Kingdom); Marchant, Tom; Moore, Chris; Webster, Gareth; Rowbottom, Carl [North Western Medical Physics, The Christie NHS Foundation Trust, Manchester (United Kingdom); Penington, Hazel [Wade Radiotherapy Research Centre, The Christie NHS Foundation Trust, Manchester (United Kingdom); Lee, Lip; Yap, Beng; Sykes, Andrew; Slevin, Nick [Department of Clinical Oncology, The Christie NHS Foundation Trust, Manchester (United Kingdom)

2012-03-01

Purpose: Parotid-sparing head-and-neck intensity-modulated radiotherapy (IMRT) can reduce long-term xerostomia. However, patients frequently experience weight loss and tumor shrinkage during treatment. We evaluate the use of kilovoltage (kV) cone beam computed tomography (CBCT) for dose monitoring and examine if the dosimetric impact of such changes on the parotid and critical neural structures warrants replanning during treatment. Methods and materials: Ten patients with locally advanced oropharyngeal cancer were treated with contralateral parotid-sparing IMRT concurrently with platinum-based chemotherapy. Mean doses of 65 Gy and 54 Gy were delivered to clinical target volume (CTV)1 and CTV2, respectively, in 30 daily fractions. CBCT was prospectively acquired weekly. Each CBCT was coregistered with the planned isocenter. The spinal cord, brainstem, parotids, larynx, and oral cavity were outlined on each CBCT. Dose distributions were recalculated on the CBCT after correcting the gray scale to provide accurate Hounsfield calibration, using the original IMRT plan configuration. Results: Planned contralateral parotid mean doses were not significantly different to those delivered during treatment (p > 0.1). Ipsilateral and contralateral parotids showed a mean reduction in volume of 29.7% and 28.4%, respectively. There was no significant difference between planned and delivered maximum dose to the brainstem (p = 0.6) or spinal cord (p = 0.2), mean dose to larynx (p = 0.5) and oral cavity (p = 0.8). End-of-treatment mean weight loss was 7.5 kg (8.8% of baseline weight). Despite a {>=}10% weight loss in 5 patients, there was no significant dosimetric change affecting the contralateral parotid and neural structures. Conclusions: Although patient weight loss and parotid volume shrinkage was observed, overall, there was no significant excess dose to the organs at risk. No replanning was felt necessary for this patient cohort, but a larger patient sample will be investigated

Monte Carlo simulations and dosimetric studies of an irradiation facility

Energy Technology Data Exchange (ETDEWEB)

Belchior, A. [Instituto Tecnologico e Nuclear, Estrada nacional no. 10, Apartado 21, 2686-953 Sacavem (Portugal)], E-mail: anabelchior@itn.pt; Botelho, M.L; Vaz, P. [Instituto Tecnologico e Nuclear, Estrada nacional no. 10, Apartado 21, 2686-953 Sacavem (Portugal)

2007-09-21

There is an increasing utilization of ionizing radiation for industrial applications. Additionally, the radiation technology offers a variety of advantages in areas, such as sterilization and food preservation. For these applications, dosimetric tests are of crucial importance in order to assess the dose distribution throughout the sample being irradiated. The use of Monte Carlo methods and computational tools in support of the assessment of the dose distributions in irradiation facilities can prove to be economically effective, representing savings in the utilization of dosemeters, among other benefits. One of the purposes of this study is the development of a Monte Carlo simulation, using a state-of-the-art computational tool-MCNPX-in order to determine the dose distribution inside an irradiation facility of Cobalt 60. This irradiation facility is currently in operation at the ITN campus and will feature an automation and robotics component, which will allow its remote utilization by an external user, under REEQ/996/BIO/2005 project. The detailed geometrical description of the irradiation facility has been implemented in MCNPX, which features an accurate and full simulation of the electron-photon processes involved. The validation of the simulation results obtained was performed by chemical dosimetry methods, namely a Fricke solution. The Fricke dosimeter is a standard dosimeter and is widely used in radiation processing for calibration purposes.

Conceptual study of calibration software for large scale input accountancy tank

International Nuclear Information System (INIS)

Uchikoshi, Seiji; Yasu, Kan-ichi; Watanabe, Yuichi; Matsuda, Yuji; Kawai, Akio; Tamura, Toshiyuki; Shimizu, Hidehiko.

1996-01-01

Demonstration experiments for large scale input accountancy tank are going to be under way by Nuclear Material Control Center. Development of calibration software for accountancy system with dip-tube manometer is an important task in the experiments. A conceptual study of the software has been carried out to construct high precision accountancy system. And, the study was based on ANSI N15.19-1989. Items of the study are overall configuration, correction method for influence of bubble formation, function model of calibration, and fitting method for calibration curve. Following remarks are the results of this study. 1) Overall configuration of the software was constructed. 2) It was shown by numerical solution, that the influence of bubble formation can be corrected using period of pressure wave. 3) Two function models of calibration for well capacity and for inner structure volume were prepared from tank design, and good fitness of the model for net capacity (balance of both models) was confirmed by fitting to designed shape of the tank. 4) The necessity of further consideration about both-variables-in-error-model and cumulative-error-model was recognized. We are going to develop a practical software on the basis of the results, and to verify it by the demonstration experiments. (author)

Dosimetric considerations and radiation protection of patients in interventional cardiology

International Nuclear Information System (INIS)

Ciraj-Bjelac, O.; Arandjic, D.; Kosutic, D.; Loncar, B.

2009-01-01

The paper summarizes results of measurements of relevant dosimetric quantities in interventional cardiology. Dosimetric data were collected for 117 coronary angiography (CA) procedures, 69 percutaneous coronary interventions (PCI) and 41 combined procedures (CA+PCI), taking into account two quantities: air kerma area product (KAP) d air kerma in international reference point (K IRP ). Mean KAP values were 78 Gy·cm 2 , 113 Gy·cm 2 and 141 Gy·cm 2 for CA, PCI i CA+PCI, respectively. Corresponding mean K IRP values were 1.2 Gy, 1.8 Gy and 2.2 Gy. With respect to high dose values, risk for stochastic effects and tissue reactions, dose management methods were proposed. (author) [sr

Potential benefits of dosimetric VMAT tracking verified with 3D film measurements

Energy Technology Data Exchange (ETDEWEB)

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

2016-05-15

Purpose: To evaluate three different plan adaptation strategies using 3D film-stack dose measurements of both focal boost and hypofractionated prostate VMAT treatments. The adaptation strategies (a couch shift, geometric tracking, and dosimetric tracking) were applied for three realistic intrafraction prostate motions. Methods: A focal boost (35 × 2.2 and 35 × 2.7 Gy) and a hypofractionated (5 × 7.25 Gy) prostate VMAT plan were created for a heterogeneous phantom that allows for internal prostate motion. For these plans geometric tracking and dosimetric tracking were evaluated by ionization chamber (IC) point dose measurements (zero-D) and measurements using a stack of EBT3 films (3D). The geometric tracking applied translations, rotations, and scaling of the MLC aperture in response to realistic prostate motions. The dosimetric tracking additionally corrected the monitor units to resolve variations due to difference in depth, tissue heterogeneity, and MLC-aperture. The tracking was based on the positions of four fiducial points only. The film measurements were compared to the gold standard (i.e., IC measurements) and the planned dose distribution. Additionally, the 3D measurements were converted to dose volume histograms, tumor control probability, and normal tissue complication probability parameters (DVH/TCP/NTCP) as a direct estimate of clinical relevance of the proposed tracking. Results: Compared to the planned dose distribution, measurements without prostate motion and tracking showed already a reduced homogeneity of the dose distribution. Adding prostate motion further blurs the DVHs for all treatment approaches. The clinical practice (no tracking) delivered the dose distribution inside the PTV but off target (CTV), resulting in boost dose errors up to 10%. The geometric and dosimetric tracking corrected the dose distribution’s position. Moreover, the dosimetric tracking could achieve the planned boost DVH, but not the DVH of the more homogeneously

Poster - 53: Improving inter-linac DMLC IMRT dose precision by fine tuning of MLC leaf calibration

International Nuclear Information System (INIS)

Nakonechny, Keith; Tran, Muoi; Sasaki, David; Beck, James; Poirier, Yannick; Malkoske, Kyle

2016-01-01

Purpose: To develop a method to improve the inter-linac precision of DMLC IMRT dosimetry. Methods: The distance between opposing MLC leaf banks (“gap size”) can be finely tuned on Varian linacs. The dosimetric effect due to small deviations from the nominal gap size (“gap error”) was studied by introducing known errors for several DMLC sliding gap sizes, and for clinical plans based on the TG119 test cases. The plans were delivered on a single Varian linac and the relationship between gap error and the corresponding change in dose was measured. The plans were also delivered on eight Varian 2100 series linacs (at two institutions) in order to quantify the inter-linac variation in dose before and after fine tuning the MLC calibration. Results: The measured dose differences for each field agreed well with the predictions of LoSasso et al. Using the default MLC calibration, the variation in the physical MLC gap size was determined to be less than 0.4 mm between all linacs studied. The dose difference between the linacs with the largest and smallest physical gap was up to 5.4% (spinal cord region of the head and neck TG119 test case). This difference was reduced to 2.5% after fine tuning the MLC gap calibration. Conclusions: The inter-linac dose precision for DMLC IMRT on Varian linacs can be improved using a simple modification of the MLC calibration procedure that involves fine adjustment of the nominal gap size.

Poster - 53: Improving inter-linac DMLC IMRT dose precision by fine tuning of MLC leaf calibration

Energy Technology Data Exchange (ETDEWEB)

Nakonechny, Keith; Tran, Muoi; Sasaki, David; Beck, James; Poirier, Yannick; Malkoske, Kyle [Simcoe-Muskoka Regional Cancer Centre (Canada)

2016-08-15

Purpose: To develop a method to improve the inter-linac precision of DMLC IMRT dosimetry. Methods: The distance between opposing MLC leaf banks (“gap size”) can be finely tuned on Varian linacs. The dosimetric effect due to small deviations from the nominal gap size (“gap error”) was studied by introducing known errors for several DMLC sliding gap sizes, and for clinical plans based on the TG119 test cases. The plans were delivered on a single Varian linac and the relationship between gap error and the corresponding change in dose was measured. The plans were also delivered on eight Varian 2100 series linacs (at two institutions) in order to quantify the inter-linac variation in dose before and after fine tuning the MLC calibration. Results: The measured dose differences for each field agreed well with the predictions of LoSasso et al. Using the default MLC calibration, the variation in the physical MLC gap size was determined to be less than 0.4 mm between all linacs studied. The dose difference between the linacs with the largest and smallest physical gap was up to 5.4% (spinal cord region of the head and neck TG119 test case). This difference was reduced to 2.5% after fine tuning the MLC gap calibration. Conclusions: The inter-linac dose precision for DMLC IMRT on Varian linacs can be improved using a simple modification of the MLC calibration procedure that involves fine adjustment of the nominal gap size.

Individual neutron dosimetry

International Nuclear Information System (INIS)

Mauricio, C.L.P.

1987-01-01

The most important concepts and development in individual neutron dosimetry are presented, especially the dosimetric properties of the albedo technique. The main problem in albedo dosimetry is to calibrate the dosemeter in the environs of each neutron source. Some of the most used calibration techniques are discussed. The IRD albedo dosemeter used in the routine neutron individual monitoring is described in detail. Its dosimetric properties and calibration methods are discussed. (Author) [pt

Dosimetric adaptive IMRT driven by fiducial points

International Nuclear Information System (INIS)

Crijns, Wouter; Van Herck, Hans; Defraene, Gilles; Van den Bergh, Laura; Haustermans, Karin; Slagmolen, Pieter; Maes, Frederik; Van den Heuvel, Frank

2014-01-01

Purpose: Intensity modulated radiotherapy (IMRT) and volumetric modulated arc therapy have become standard treatments but are more sensitive to anatomical variations than 3D conformal techniques. To correct for inter- and intrafraction anatomical variations, fast and easy to implement methods are needed. Here, the authors propose a full dosimetric IMRT correction that finds a compromise in-between basic repositioning (the current clinical practice) and full replanning. It simplifies replanning by avoiding a recontouring step and a full dose calculation. It surpasses repositioning by updating the preoptimized fluence and monitor units (MU) using a limited number of fiducial points and a pretreatment (CB)CT. To adapt the fluence the fiducial points were projected in the beam's eye view (BEV). To adapt the MUs, point dose calculation towards the same fiducial points were performed. The proposed method is intrinsically fast and robust, and simple to understand for operators, because of the use of only four fiducial points and the beam data based point dose calculations. Methods: To perform our dosimetric adaptation, two fluence corrections in the BEV are combined with two MU correction steps along the beam's path. (1) A transformation of the fluence map such that it is realigned with the current target geometry. (2) A correction for an unintended scaling of the penumbra margin when the treatment beams scale to the current target size. (3) A correction for the target depth relative to the body contour and (4) a correction for the target distance to the source. The impact of the correction strategy and its individual components was evaluated by simulations on a virtual prostate phantom. This heterogeneous reference phantom was systematically subjected to population based prostate transformations to simulate interfraction variations. Additionally, a patient example illustrated the clinical practice. The correction strategy was evaluated using both dosimetric

Dosimetric adaptive IMRT driven by fiducial points

Energy Technology Data Exchange (ETDEWEB)

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

2014-06-15

Purpose: Intensity modulated radiotherapy (IMRT) and volumetric modulated arc therapy have become standard treatments but are more sensitive to anatomical variations than 3D conformal techniques. To correct for inter- and intrafraction anatomical variations, fast and easy to implement methods are needed. Here, the authors propose a full dosimetric IMRT correction that finds a compromise in-between basic repositioning (the current clinical practice) and full replanning. It simplifies replanning by avoiding a recontouring step and a full dose calculation. It surpasses repositioning by updating the preoptimized fluence and monitor units (MU) using a limited number of fiducial points and a pretreatment (CB)CT. To adapt the fluence the fiducial points were projected in the beam's eye view (BEV). To adapt the MUs, point dose calculation towards the same fiducial points were performed. The proposed method is intrinsically fast and robust, and simple to understand for operators, because of the use of only four fiducial points and the beam data based point dose calculations. Methods: To perform our dosimetric adaptation, two fluence corrections in the BEV are combined with two MU correction steps along the beam's path. (1) A transformation of the fluence map such that it is realigned with the current target geometry. (2) A correction for an unintended scaling of the penumbra margin when the treatment beams scale to the current target size. (3) A correction for the target depth relative to the body contour and (4) a correction for the target distance to the source. The impact of the correction strategy and its individual components was evaluated by simulations on a virtual prostate phantom. This heterogeneous reference phantom was systematically subjected to population based prostate transformations to simulate interfraction variations. Additionally, a patient example illustrated the clinical practice. The correction strategy was evaluated using both dosimetric

A Monte Carlo dosimetric quality assurance system for dynamic intensity-modulated radiotherapy

International Nuclear Information System (INIS)

Takegawa, Hideki; Yamamoto, Tokihiro; Miyabe, Yuki; Teshima, Teruki; Kunugi, Tomoaki; Yano, Shinsuke; Mizowaki, Takashi; Nagata, Yasushi; Hiraoka, Masahiro

2005-01-01

We are developing a Monte Carlo (MC) dose calculation system, which can resolve dosimetric issues derived from multileaf collimator (MLC) design for routine dosimetric quality assurance (QA) of intensity-modulated radiotherapy (IMRT). The treatment head of the medical linear accelerator equipped with MLC was modeled using the EGS4 MC code. A graphical user interface (GUI) application was developed to implement MC dose computation in the CT-based patient model and compare the MC calculated results with those of a commercial radiotherapy treatment planning (RTP) system, Varian Eclipse. To reduce computation time, the EGS4 MC code has been parallelized on massive parallel processing (MPP) system using the message passing interface (MPI). The MC treatment head model and MLC model were validated by the measurement data sets of percentage depth dose (PDD) and off-center ratio (OCR) in the water phantom and the film measurements for the static and dynamic test patterns, respectively. In the treatment head model, the MC calculated results agreed with those of measurements for both of PDD and OCR. The MC could reproduce all of the MLC dosimetric effects. A quantitative comparison between the results of MC and Eclipse was successfully performed with the GUI application. Parallel speed-up became almost linear. An MC dosimetric QA system for dynamic IMRT has been developed, however there were large dose discrepancies between the MC and the measurement in the MLC model simulation, which are now being investigated. (author)

Basic Principles and Practices of Integrated Dosimetric Passportization of the Settlements in Ukraine.

Science.gov (United States)

Likhtarov, I A; Kovgan, L M; Masiuk, S V; Ivanova, O M; Chepurny, M I; Boyko, Z N; Gerasymenko, V B

2015-12-01

The purpose of the review is to demonstrate the results of dosimetric passportization (performed in 1991-2014) for the settlements of Ukraine which suffered from radioactive contamination caused by the Chornobyl accident. The dosimetric passportization played a key role in the National program on the liquidation of aftermath of the Chornobyl accident directed on recovery through all stages of the current radiation situation control and decision support touching upon various types of interventions and social benefits to the population of radioactively contaminated areas. The works being performed under dosimetric passportization did not have analogues among the researches which took place after other large-scale industrial and municipal accidents as well their scales as the duration of both radio-ecological and dosimetric monitoring.The new methodological approaches to the assessment of so-called passport doses of a settlement as well as to the definition of the concept of annual dose being the dose used to make decisions for providing both direct and indirect emergency countermeasures for the settlements of Ukraine became pioneering ones. During all the post-accident period there were issued sixteen collections of general dosimetric passportization data which accumulate the results of hundreds of thousands spectrometric, radiochemical and radiation levels measurements and WBC measurements carried out in 1991-2014.The annual passport doses calculated on the basis of these measurements (including their components) are unique information that quantifies the level and time dynamics of the radiation situation for each of the 2161 settlements of 74 raions in 12 oblasts during all the post-accident period. Thanks to the works of dosimetric passportization of the settlements of Ukraine there were created databases to be unique in their structure and content with quantitative characteristics of the territorial and temporal distribution, the dynamics of changes of a number

Neutron Spectrometry for Radiation Protection Purposes

International Nuclear Information System (INIS)

McDonald, Joseph C.

2001-01-01

Determination of the dose equivalent is required for radiation protection purposes, however such a determination is quite difficult for neutron radiation. In order to perform accurate dosimetric determinations, it is necessary to acquire information about the neutron fluence spectrum in the workplace as well as the reference radiations used to calibrate dosimetric instruments. This information can then be used to select the appropriate dosimetric instrument, the optimum calibration condition or to establish correction factors that account for the differences in calibration and workplace conditions. For quite some time, neutron spectrometry has been used for these purposes. A brief review of the applications of spectrometers in radiation protection and some recommendations for further development are given here

Neutron spectrometry for radiation protection purposes

CERN Document Server

McDonald, J C; Alberts, W G

2002-01-01

Determination of the dose equivalent is required for radiation protection purposes, however such a determination is quite difficult for neutron radiation. In order to perform accurate dosimetric determinations, it is advantageous to acquire information about the neutron fluence spectrum in the workplace as well as the reference radiations used to calibrate dosimetric instruments. This information can then be used to select the appropriate dosimetric instrument, the optimum calibration condition or to establish correction factors that account for the differences in calibration and workplace conditions. For quite some time, neutron spectrometry has been used for these purposes. A brief review of the applications of spectrometers in radiation protection and some recommendations for further development are given here.

Dosimetric response of united, commercially available CTA foils for 60Co gamma rays

International Nuclear Information System (INIS)

Peimel-Stuglik, Z.

2001-01-01

The usefulness of two kinds of untinted CTA foils: Fuji CTR-125 dosimetric foil and technical CTA-T foil, produced by 'Zaklady Chemiczne, 'Gorzow Wielkopolski' as support for light-sensitive layers of amateur photo-films, for 60 Co gamma ray dosimetry was investigated. In spite of rather bad physical parameters of the technical foil (spread of foil thickness, high and different initial absorbance) the dosimetric response of both foils for 60 Co gamma rays was similar. The CTA-T foil can be used for routine dosimetry providing that dosimetric signals have to be calculated exactly as recommended by the ASTM (American Society for Testing and Materials) standard, i.e. as the difference of absorbance of irradiated and (the same) non-irradiated foil. Any other approach may lead to high errors of dose evaluation. The last is true also for other CTA foils, especially after long self-life. (author)

Dosimetric optimization of worksite involving the installation of VATS containing highly active effluent

International Nuclear Information System (INIS)

Legee, F.; Busani, J.; Madigand, Y.; Pailloux, J.

1996-01-01

Within the framework of safety improvements at the CEA, CEA-FAR, concerned to formalize the ALARA initiative, has carried out for information and training purpose and to create awareness a dosimetric assessment of the worksite where new storage vats for highly active effluents are to be installed. The approach used for this worksite is global. Techniques used were all complementary, ensuring constant elaboration, experiment follow-up and feedback of a worksite at a relatively low dosimetric cost (an estimated 36 men.mSv brought down to 30 men.mSv through implementation of the ALARA principle). This type of global conception of radioprotection involving all the employees (head of project, project managers, companies, radioprotection employees...) which today proves its worth on a modest worksite must now be extended to worksites of a broader scope (several hundreds of men.mSv) where fulfillment of the dosimetric objectives is a major stake. (author)

SU-E-T-442: Geometric Calibration and Verification of a GammaPod Breast SBRT System

Energy Technology Data Exchange (ETDEWEB)

Yu, C [Univ Maryland School of Medicine, Baltimore, MD (United States); Xcision Medical Systems, Columbia, MD (United States); Niu, Y; Maton, P; Hoban, P [Xcision Medical Systems, Columbia, MD (United States); Mutaf, Y [Univ Maryland School of Medicine, Baltimore, MD (United States)

2015-06-15

Purpose: The first GammaPod™ unit for prone stereotactic treatment of early stage breast cancer has recently been installed and calibrated. Thirty-six rotating circular Co-60 beams focus dose at an isocenter that traverses throughout a breast target via continuous motion of the treatment table. The breast is immobilized and localized using a vacuum-assisted stereotactic cup system that is fixed to the table during treatment. Here we report on system calibration and on verification of geometric and dosimetric accuracy. Methods: Spatial calibration involves setting the origin of each table translational axis within the treatment control system such that the relationship between beam isocenter and table geometry is consistent with that assumed by the treatment planning system. A polyethylene QA breast phantom inserted into an aperture in the patient couch is used for calibration and verification. The comparison is performed via fiducial-based registration of measured single-isocenter dose profiles (radiochromic film) with kernel dose profiles. With the table calibrations applied, measured relative dose distributions were compared with TPS calculations for single-isocenter and dynamic (many-isocenter) treatment plans. Further, table motion accuracy and linearity was tested via comparison of planned control points with independent encoder readouts. Results: After table calibration, comparison of measured and calculated single-isocenter dose profiles show agreement to within 0.5 mm for each axis. Gamma analysis of measured vs calculated profiles with 3%/2mm criteria yields a passing rate of >99% and >98% for single-isocenter and dynamic plans respectively. This also validates the relative dose distributions produced by the TPS. Measured table motion accuracy was within 0.05 mm for all translational axes. Conclusion: GammaPod table coordinate calibration is a straightforward process that yields very good agreement between planned and measured relative dose distributions

Effect of stereotactic dosimetric end points on overall survival for Stage I non–small cell lung cancer: A critical review

Energy Technology Data Exchange (ETDEWEB)

Mulryan, Kathryn; Leech, Michelle; Forde, Elizabeth, E-mail: eforde@tcd.ie

2015-01-01

Stereotactic body radiation therapy (SBRT) delivers a high biologically effective dose while minimizing toxicities to surrounding tissues. Within the scope of clinical trials and local practice, there are inconsistencies in dosimetrics used to evaluate plan quality. The purpose of this critical review was to determine if dosimetric parameters used in SBRT plans have an effect on local control (LC), overall survival (OS), and toxicities. A database of relevant trials investigating SBRT for patients with early-stage non–small cell lung cancer was compiled, and a table of dosimetric variables used was created. These parameters were compared and contrasted for LC, OS, and toxicities. Dosimetric end points appear to have no effect on OS or LC. Incidences of rib fractures correlate with a lack of dose-volume constraints (DVCs) reported. This review highlights the great disparity present in clinical trials reporting dosimetrics, DVCs, and toxicities for lung SBRT. Further evidence is required before standard DVCs guidelines can be introduced. Dosimetric end points specific to stereotactic treatment planning have been proposed but require further investigation before clinical implementation.

Development of dose calibrators Tandem systems and establishment of beta dosimetry in nuclear medicine

International Nuclear Information System (INIS)

Cecatti, Sonia Garcia Pereira

2004-01-01

A quality control program at Nuclear Medicine Services includes the checking of all equipment used for diagnostics and treatment, and the individual monitoring of the workers occupationally exposed to ionizing radiations. In this work the main quality control tests were performed with three dose calibrators using standard radiation sources of 57 Co, 133 Ba, 137 Cs and 60 Co. Tandem systems of dose calibrators were established and characterized using four cylindrical absorbers of different materials for an additional quality control test in Nuclear Medicine. The main utility of this new test is the possibility of impurity detection in radiopharmaceuticals, when the ratio of the measurements with different absorbers is different from that obtained at the laboratory in ideal conditions. The dosimetric characteristics of three types of CaS0 4 :Dy + Teflon pellets were studied for an appropriate choice of the material to be used for individual monitoring of workers. The thermoluminescent detectors were irradiated using beta sources of 90 Sr+ 90 Y, 204 TI, 147 Pm, 153 Sm and 32 P. A wrist badge for beta individual monitoring was developed for workers that handle beta radiopharmaceuticals in Nuclear Medicine Services. (author)

Simulation of The ICRP-30 Dosimetric Model for the Respiratory Tract

International Nuclear Information System (INIS)

Giaddui, T.; Atia, M. A.

2004-01-01

Matlab was used to write a simulation program (ACID1) to simulate the ICRP-30 dosimetric model for the respiratory tract. The program (a new version of the one presented at the sixth Arab conference held in Cairo 2002) calculates a series of dosimetric quantities for the reference man as a result of the inhalation of any radionuclide. The program also plots the variation of activity with time for all organs and provided with a graphical user interface to make it friendly user. The results obtained by this program was compared with similar results obtained by other source and found to be very close. (Authors)

Dosimetric evaluation of the OneDoseTM MOSFET for measuring kilovoltage imaging dose from image-guided radiotherapy procedures.

Science.gov (United States)

Ding, George X; Coffey, Charles W

2010-09-01

The purpose of this study is to investigate the feasibility of using a single-use dosimeter, OneDose MOSFET designed for in vivo patient dosimetry, for measuring the radiation dose from kilovoltage (kV) x rays resulting from image-guided procedures. The OneDose MOSFET dosimeters were precalibrated by the manufacturer using Co-60 beams. Their energy response and characteristics for kV x rays were investigated by using an ionization chamber, in which the air-kerma calibration factors were obtained from an Accredited Dosimetry Calibration Laboratory (ADCL). The dosimetric properties have been tested for typical kV beams used in image-guided radiation therapy (IGRT). The direct dose reading from the OneDose system needs to be multiplied by a correction factor ranging from 0.30 to 0.35 for kilovoltage x rays ranging from 50 to 125 kVp, respectively. In addition to energy response, the OneDose dosimeter has up to a 20% reduced sensitivity for beams (70-125 kVp) incident from the back of the OneDose detector. The uncertainty in measuring dose resulting from a kilovoltage beam used in IGRT is approximately 20%; this uncertainty is mainly due to the sensitivity dependence of the incident beam direction relative to the OneDose detector. The ease of use may allow the dosimeter to be suitable for estimating the dose resulting from image-guided procedures.

Centro de Proteccion e Higiene de las Radiaciones (CPHR) Holguin Territorial Office Scientific Technical Co-operation in the field of ionizing radiation metrology: Results and perspectives

International Nuclear Information System (INIS)

Morales, J.A.; Bravo, R.

1993-01-01

This paper presents an overview of the activities carried out in order to organic a dosimetric calibration territorial service to be performed mainly with Secretaria Ejecutiva Para Asuntos Nucleares (SEAN) personnel and model facilities. This paper emphasizes the results of the calibration which will performed this service in joint association with CPHR specialist and Holguin Territorial Office (june 1993). The perspective of co-operation in this field starting up the CPHR dosimetric calibration secondary laboratory are presented

Multi-lane Roundabout Capacity Evaluation

Directory of Open Access Journals (Sweden)

Ammar Šarić

2017-07-01

Full Text Available Although two-lane roundabouts theoretically exhibit excellent operating performance, in practice, safety problems arise because of inappropriate driving behavior. Turbo roundabouts, which are characterized by a much higher level of safety, are alternatives to classic two-lane roundabouts, but the capacity-related benefits derived from such roundabouts remain an open issue. Accordingly, this study uses an equilibrium traffic flow allocation approach to evaluate multi-lane roundabout capacity based on gap acceptance theory. Capacity levels are calculated and compared for different gap acceptance parameters, including local parameters, and different traffic flow scenarios. It is found that the capacity of minor approaches on turbo roundabouts is always higher than on two-lane roundabouts, but that the main approaches on two-lane roundabouts exhibit better performance in terms of fully equilibrium traffic allocation. This state, however, cannot be achieved for every demand scenario. The results depend strongly on traffic movements and gap acceptance parameters indicating the need for local calibration processes.

Computer Generated Hologram System for Wavefront Measurement System Calibration

Science.gov (United States)

Olczak, Gene

2011-01-01

Computer Generated Holograms (CGHs) have been used for some time to calibrate interferometers that require nulling optics. A typical scenario is the testing of aspheric surfaces with an interferometer placed near the paraxial center of curvature. Existing CGH technology suffers from a reduced capacity to calibrate middle and high spatial frequencies. The root cause of this shortcoming is as follows: the CGH is not placed at an image conjugate of the asphere due to limitations imposed by the geometry of the test and the allowable size of the CGH. This innovation provides a calibration system where the imaging properties in calibration can be made comparable to the test configuration. Thus, if the test is designed to have good imaging properties, then middle and high spatial frequency errors in the test system can be well calibrated. The improved imaging properties are provided by a rudimentary auxiliary optic as part of the calibration system. The auxiliary optic is simple to characterize and align to the CGH. Use of the auxiliary optic also reduces the size of the CGH required for calibration and the density of the lines required for the CGH. The resulting CGH is less expensive than the existing technology and has reduced write error and alignment error sensitivities. This CGH system is suitable for any kind of calibration using an interferometer when high spatial resolution is required. It is especially well suited for tests that include segmented optical components or large apertures.

Course on dosimetric protocols

International Nuclear Information System (INIS)

1988-01-01

Several papers about dosimeters calibration are presented. The emphasis is given to the quality control for clinical dosemeters. The calibration necessary for Secondary Standard Pattern Laboratory are shown and the installations and shields for an linear accelerator room are cited. (E.G.) [pt

Dosimetric quality of postal kit used for evaluation in IRD/CNEN of radiation protection parameters in dental radiology in the State of Rio de Janeiro; Qualidade dosimetrica do kit postal utilizado pelo IRD/CNEN para a avaliacao dos parametros de radioprotecao em radiologia odontologica no Estado do Rio de Janeiro

Energy Technology Data Exchange (ETDEWEB)

Coutinho, Soray Abbud; Mota, Helvecio C; Dovales, Ana Cristina M [Instituto de Radioprotecao e Dosimetria (IRD), Rio de Janeiro, RJ (Brazil). Dept. de Fisica Medica

2001-07-01

This work shows the results of a comparison between the skin entrance doses determined using an ionization chamber or a postal kit routinely used for the evaluation of radiation protection parameters in dental radiology in the state of Rio de Janeiro. By using the dosimetric kit, entrance skin dose is determined from two thermoluminescent dosimeters (TLDs) - previously calibrated in a {sup 137} Cs source - by using calibration factors determined in TLDs irradiated in air, on a water phantom and on an aluminium filter. The correspondence between the doses obtained with different methods was evaluated for three different X-ray spectra as radiation source. Results indicate that calibration factors used are adequate and that the kit has enough sensibility and reproducibility, measuring properly the skin entrance dose in dental X-rays. (author)

PLEIADES ABSOLUTE CALIBRATION : INFLIGHT CALIBRATION SITES AND METHODOLOGY

Directory of Open Access Journals (Sweden)

S. Lachérade

2012-07-01

Full Text Available In-flight calibration of space sensors once in orbit is a decisive step to be able to fulfil the mission objectives. This article presents the methods of the in-flight absolute calibration processed during the commissioning phase. Four In-flight calibration methods are used: absolute calibration, cross-calibration with reference sensors such as PARASOL or MERIS, multi-temporal monitoring and inter-bands calibration. These algorithms are based on acquisitions over natural targets such as African deserts, Antarctic sites, La Crau (Automatic calibration station and Oceans (Calibration over molecular scattering or also new extra-terrestrial sites such as the Moon and selected stars. After an overview of the instrument and a description of the calibration sites, it is pointed out how each method is able to address one or several aspects of the calibration. We focus on how these methods complete each other in their operational use, and how they help building a coherent set of information that addresses all aspects of in-orbit calibration. Finally, we present the perspectives that the high level of agility of PLEIADES offers for the improvement of its calibration and a better characterization of the calibration sites.

SU-F-SPS-10: The Dosimetric Comparison of GammaKnife and Cyberknife Treatment Plans for Brain SRS Treatment

International Nuclear Information System (INIS)

Sanli, E; Mabhouti, H; Cebe, M; Codel, G; Pacaci, P; Serin, E; Kucuk, N; Kucukmorkoc, E; Doyuran, M; Canoglu, D; Altinok, A; Acar, H; Caglar Ozkok, H

2016-01-01

Purpose: Brain stereotactic radiosurgery (SRS) involves the use of precisely directed, single session radiation to create a desired radiobiologic response within the brain target with acceptable minimal effects on surrounding structures or tissues. In this study, the dosimetric comparison of GammaKnife perfection and Cyberknife M6 treatment plans were made. Methods: Treatment plannings were done for GammaKnife perfection unit using Gammaplan treatment planning system (TPS) on the CT scan of head and neck randophantom simulating the treatment of sterotactic treatments for one brain metastasis. The dose distribution were calculated using TMR 10 algorithm. The treatment planning for the same target were also done for Cyberknife M6 machine using Multiplan (TPS) with Monte Carlo algorithm. Using the same film batch, the net OD to dose calibration curve was obtained using both machine by delivering 0- 800 cGy. Films were scanned 48 hours after irradiation using an Epson 1000XL flatbed scanner. Dose distribution were measured using EBT3 film dosimeter. The measured and calculated doses were compared. Results: The dose distribution in the target and 2 cm beyond the target edge were calculated on TPSs and measured using EBT3 film. For cyberknife treatment plans, the gamma analysis passing rates between measured and calculated dose distributions were 99.2% and 96.7% for target and peripheral region of target respectively. For gammaknife treatment plans, the gamma analysis passing rates were 98.9% and 93.2% for target and peripheral region of target respectively. Conclusion: The study shows that dosimetrically comparable plans are achievable with Cyberknife and GammaKnife. Although TMR 10 algorithm predicts the target dose

SU-F-SPS-10: The Dosimetric Comparison of GammaKnife and Cyberknife Treatment Plans for Brain SRS Treatment

Energy Technology Data Exchange (ETDEWEB)

Sanli, E; Mabhouti, H; Cebe, M; Codel, G; Pacaci, P; Serin, E; Kucuk, N; Kucukmorkoc, E; Doyuran, M; Canoglu, D; Altinok, A; Acar, H; Caglar Ozkok, H [Medipol University, Istanbul, Istanbul (Turkey)

2016-06-15

Purpose: Brain stereotactic radiosurgery (SRS) involves the use of precisely directed, single session radiation to create a desired radiobiologic response within the brain target with acceptable minimal effects on surrounding structures or tissues. In this study, the dosimetric comparison of GammaKnife perfection and Cyberknife M6 treatment plans were made. Methods: Treatment plannings were done for GammaKnife perfection unit using Gammaplan treatment planning system (TPS) on the CT scan of head and neck randophantom simulating the treatment of sterotactic treatments for one brain metastasis. The dose distribution were calculated using TMR 10 algorithm. The treatment planning for the same target were also done for Cyberknife M6 machine using Multiplan (TPS) with Monte Carlo algorithm. Using the same film batch, the net OD to dose calibration curve was obtained using both machine by delivering 0- 800 cGy. Films were scanned 48 hours after irradiation using an Epson 1000XL flatbed scanner. Dose distribution were measured using EBT3 film dosimeter. The measured and calculated doses were compared. Results: The dose distribution in the target and 2 cm beyond the target edge were calculated on TPSs and measured using EBT3 film. For cyberknife treatment plans, the gamma analysis passing rates between measured and calculated dose distributions were 99.2% and 96.7% for target and peripheral region of target respectively. For gammaknife treatment plans, the gamma analysis passing rates were 98.9% and 93.2% for target and peripheral region of target respectively. Conclusion: The study shows that dosimetrically comparable plans are achievable with Cyberknife and GammaKnife. Although TMR 10 algorithm predicts the target dose.

Dosimetric methodology of the ICRP

International Nuclear Information System (INIS)

Eckerman, K.F.

1994-01-01

Establishment of guidance for the protection of workers and members of the public from radiation exposures necessitates estimation of the radiation dose to tissues of the body at risk. The dosimetric methodology formulated by the International Commission on Radiological Protection (ICRP) is intended to be responsive to this need. While developed for radiation protection, elements of the methodology are often applied in addressing other radiation issues; e.g., risk assessment. This chapter provides an overview of the methodology, discusses its recent extension to age-dependent considerations, and illustrates specific aspects of the methodology through a number of numerical examples

Dosimetric intercomparison in Cobalt 60 unities using TLD-100 crystals and CaSO4: Dy + Ptfe

International Nuclear Information System (INIS)

Gaona, E.; Azorin N, J.; Perez P, M.A.; Castillo H, M.; Flores F, F.; Guzman R, L.V.

1999-01-01

The purpose of this work is to design and construct a phantom in basis of thermoplastic polymer of methyl methacrylate that is reutilizable and which allows to do an analysis of the absorbed doses in thermoluminescent crystals (Tl) exposed to cobalt 60 to establish the dosimetric intercomparison in cobalt units which allows to do the follow-up of the Quality assurance programs, standardization of calibration procedures, dosimetry and TLD post intercomparison in radiotherapy. This work allows also prove new thermoluminescent materials of national manufacture developed by Juan Azorin and collaborators as the CaSO 4 : Dy + Ptfe. This is a first study which is realized in Mexico with the system crystal-phantom for aims to intercomparison in cobalt 60 units. In this work participate eight unities of cobalt 60 of different trades belonging at four radiotherapy centers. The results of the dose intercomparison of the eight unities of cobalt 60 were in the range 0.95-1.13, taking in account that the values between 0.95 and 1.05 were considered acceptable in terms of the requirements by the standing legislation. (Author)

Model dosimetric for Radon and Daughters

International Nuclear Information System (INIS)

Puerta, J.A.; Cardenas, H.F.

1998-01-01

You elaborates a model dosimetric for radon and their products of decline of short half life starting from the new model of the breathing tract of the publication 66 of the ICRP and the use of the systemic models proposed in the publication 67, 68 and 69 of the same commission. The correlated used methodology the incorporation of these radionuclides with the activity in organs and you excrete, considering the difference of metabolic behavior of the products of decline and of their predecessor

The effects of pre-dose and annealing temperature on some dosimetric properties of thermoluminescence of quartz

International Nuclear Information System (INIS)

Lin Zhikai

1996-02-01

The following aspects of dosimetric properties of quartz sample were studied. (1) The changes in dosimetric sensitivity of quartz with different pre-doses under different annealing temperature; (2) the option of optimal annealing temperature which can make the dosimetric sensitivity of quartz to restore its original level; (3) The changes in dosimetric sensitivity of quartz with different annealing time at 500 degree C for 8 h; (4) Repeated experiments were carried out in order to prove whether the sensitivity of quartz can restore its original level at annealing temperature 700 degree C for 3 h. It has been found that at 700 degree C for 3 h gave the least sensitivity change and the sensitivity of quartz almost restored its original level. Repeated experiments with four kinds of quartz sample confirmed this conclusion. The dramatic change of TL glow curve occurred only at the condition of annealing temperature 900 degree C for 1 h. This result was different from that obtained by D. J. Huntley et al. (1988). (3 refs., 4 figs., 1 tab.)

Conception of the Instrument Calibration Laboratory of Ionizing Radiation Measurement (LACIMRI) of CTMSP - Sao Paulo, SP

International Nuclear Information System (INIS)

Silva, Raimundo Dias da; Kibrit, Eduardo

2009-01-01

The present work describes the phases of implantation of calibration laboratory of ionizing radiation measurement instruments at the CTMSP, Sao Paulo, in a priory approved by CNEN, Brazil. That laboratory will allow and enhance the present metrological capacity for the attendance to the growing demand for calibration services of the instruments

SU-G-TeP3-11: Radiobiological-Cum-Dosimetric Quality Assurance of Complex Radiotherapy Plans

Energy Technology Data Exchange (ETDEWEB)

Paudel, N; Narayanasamy, G; Zhang, X; Penagaricano, J; Morrill, S [University of Arkansas for Medical Sciences, Little Rock, AR (United States); Mavroidis, P [University North Carolina, Chapel Hill, NC (United States); Pyakuryal, A [National Cancer Institute, Rockville, MD (United States); Han, E [UT MD Anderson Cancer Center, Houston, TX (United States); Liang, X [University of Florida Health Proton Therapy Institute, Jacksonville, FL (United States); Kim, D [Kyung Hee University Hospital, Seol (Korea, Republic of)

2016-06-15

Purpose: Dosimetric gamma-analysis used for QA of complex radiotherapy plans tests the dosimetric equivalence of a delivered plan with the treatment planning system (TPS) optimized plan. It does not examine whether a dosimetric difference results in any radiobiological difference. This study introduces a method to test the radiobiological and dosimetric equivalence between a delivered and the TPS optimized plan. Methods: Six head and neck and seven lung cancer VMAT or IMRT plans optimized for patient treatment were calculated and delivered to an ArcCheck phantom. ArcCheck measured dose distributions were compared with the TPS calculated dose distributions using a 2-D gamma-analysis. Dose volume histograms (DVHs) for various patient structures were obtained by using measured data in 3DVH software and compared against the TPS calculated DVHs using 3-D gamma analysis. DVH data were used in the Poisson model to calculate tumor control probability (TCP) for the treatment targets and in the sigmoid dose response model to calculate normal tissue complication probability (NTCP) for the normal structures. Results: Two-D and three-D gamma passing rates among six H&N patient plans differed by 0 to 2.7% and among seven lung plans by 0.1 to 4.5%. Average ± SD TCPs based on measurement and TPS were 0.665±0.018 and 0.674±0.044 for H&N, and 0.791±0.027 and 0.733±0.031 for lung plans, respectively. Differences in NTCPs were usually negligible. The differences in dosimetric results, TCPs and NTCPs were insignificant. Conclusion: The 2-D and 3-D gamma-analysis based agreement between measured and planned dose distributions may indicate their dosimetric equivalence. Small and insignificant differences in TCPs and NTCPs based on measured and planned dose distributions indicate the radiobiological equivalence between the measured and optimized plans. However, patient plans showing larger differences between 2-D and 3-D gamma-analysis can help us make a more definite conclusion

Thermoluminescence dosimetric characteristics of thulium doped ZnB{sub 2}O{sub 4} phosphor

Energy Technology Data Exchange (ETDEWEB)

Annalakshmi, O. [Radiological Safety Division, Indira Gandhi Centre for Atomic Research, Kalpakkam-603102 (India); Jose, M.T., E-mail: mtj@igcar.gov.in [Radiological Safety Division, Indira Gandhi Centre for Atomic Research, Kalpakkam-603102 (India); Madhusoodanan, U. [Radiological Safety Division, Indira Gandhi Centre for Atomic Research, Kalpakkam-603102 (India); Subramanian, J. [Central Leather Research Institute, Council of Scientific and Industrial Research, Chennai (India); Venkatraman, B. [Radiological Safety Division, Indira Gandhi Centre for Atomic Research, Kalpakkam-603102 (India); Amarendra, G. [Materials Physics Division, Indira Gandhi Centre for Atomic Research, Kalpakkam-603102 (India); Mandal, A.B. [Central Leather Research Institute, Council of Scientific and Industrial Research, Chennai (India)

2014-02-15

Polycrystalline powder samples of rare earth doped Zinc borates were synthesized by high temperature solid state diffusion technique. Dosimetric characteristics of the phosphor like thermoluminescence glow curve, TL emission spectra, dose–response, fading studies, reproducibility and reusability studies were carried out on the synthesized phosphors. Among the different rare earth doped phosphors, thulium doped zinc borate was found to have a higher sensitivity. Hence detailed dosimetric characteristics of this phosphor were carried out. It is observed that the dose–response is linear from 10 mGy to 10{sup 3} Gy in this phosphor. EPR measurements were carried out on unirradiated, gamma irradiated and annealed phosphors to identify the defect centers responsible for thermoluminescence. A TL model is proposed based on the EPR studies in these materials. Kinetic parameters were evaluated for the dosimetric peaks using various methods. The experimental results show that this phosphor can have potential applications in radiation dosimetry applications. -- Highlights: • Polycrystalline powder samples of rare earth doped zinc borates were synthesized. • Thulium was observed to be the most efficient dopant in ZnB{sub 2}O{sub 4} lattice. • TL intensity of the dosimetric peak is around 20 times that of TLD-100. • Based on EPR studies a TL mechanism is proposed in zinc borate. • Deconvolution of the glow curve carried out.

Development of a dosimetric system for emergency situation involving person of the public; Desenvolvimento de um sistema dosimetrico para situacoes de emergencia envolvendo pessoas do publico em geral

Energy Technology Data Exchange (ETDEWEB)

Costa, Zelia Maria da

1999-07-01

A dosimetric system was developed for emergency situation based on electron spin resonance spectrometry (E.S.R.) and some materials such as tooth enamel, bovine bone, CaCO{sub 3} and sugar as detector. The purpose of this work was to find common materials, which are both reliable and sensitive and make possible quickly to assess the absorbed dose. The research includes the collection and preparation of samples, the evaluation, treatment and interpretation of ESR signal and the procedure for dose reconstruction. The calibration of the dosemeter was performed using gamma radiation from a Co-60 source. The results obtained confirm the variability of the use of this system in case of an accident. (author)

Dosimetric improvements following 3D planning of tangential breast irradiation

International Nuclear Information System (INIS)

Aref, Amr; Thornton, Dale; Youssef, Emad; He, Tony; Tekyi-Mensah, Samuel; Denton, Lori; Ezzell, Gary

2000-01-01

Purpose: To evaluate the dosimetric difference between a simple radiation therapy plan utilizing a single contour and a more complex three-dimensional (3D) plan utilizing multiple contours, lung inhomogeneity correction, and dose-based compensators. Methods and Materials: This is a study of the radiation therapy (RT) plans of 85 patients with early breast cancer. All patients were considered for breast-conserving management and treated by conventional tangential fields technique. Two plans were generated for each patient. The first RT plan was based on a single contour taken at the central axis and utilized two wedges. The second RT plan was generated by using the 3D planning system to design dose-based compensators after lung inhomogeneity correction had been made. The endpoints of the study were the comparison between the volumes receiving greater than 105% and greater than 110% of the reference dose, as well as the magnitude of the treated volume maximum dose. Dosimetric improvement was defined to be of significant value if the volume receiving > 105% of one plan was reduced by at least 50% with the absolute difference between the volumes being 5% or greater. The dosimetric improvements in 49 3D plans (58%) were considered of significant value. Patients' field separation and breast size did not predict the magnitude of improvement in dosimetry. Conclusion: Dose-based compensator plans significantly reduced the volumes receiving > 105%, >110%, and volume maximum dose.

Calibration

International Nuclear Information System (INIS)

Greacen, E.L.; Correll, R.L.; Cunningham, R.B.; Johns, G.G.; Nicolls, K.D.

1981-01-01

Procedures common to different methods of calibration of neutron moisture meters are outlined and laboratory and field calibration methods compared. Gross errors which arise from faulty calibration techniques are described. The count rate can be affected by the dry bulk density of the soil, the volumetric content of constitutional hydrogen and other chemical components of the soil and soil solution. Calibration is further complicated by the fact that the neutron meter responds more strongly to the soil properties close to the detector and source. The differences in slope of calibration curves for different soils can be as much as 40%

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

International Nuclear Information System (INIS)

Greer, Peter B.; Popescu, Carmen C.

2003-01-01

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

Evaluation of the influence of the TH-GEM detector components in dosimetric measurements of standard mammography beams

Energy Technology Data Exchange (ETDEWEB)

Silva, Natália F.; Castro, Maysa C.; Caldas, Linda V.E., E-mail: nsilva@ipen.br, E-mail: maysadecastro@gmail.com, E-mail: fbelonsi@gmail.com, E-mail: lcaldas@ipen.br [Instituto de Pesquisas Energéticas e Nucleares (IPEN/CNEN-SP), São Paulo, SP (Brazil); Silva, Tiago F.; Cintra, Felipe B.; Luz, Hugo N. da, E-mail: tfsilva@if.usp.br, E-mail: hugonluz@if.usp.br [Universidade de São Paulo (IF/USP), São Paulo, SP (Brazil). Instituto de Física

2017-07-01

GEM detectors have found applications in many areas due to their simplicity of construction, low cost, ruggedness and diversity of shape. A dosimeter with these qualities presents utility in several applications, as for example in diagnostic and therapeutic medicine, industrial radiography and nuclear meters. Furthermore, the high sensitivity provided by GEM detectors may extend their applications in low dose dosimetry. Based on these facts, it may be interesting to produce a prototype of a portable TH-GEM type detector with characteristics suitable for dosimetric use in X-rays with low and medium energies. The precise determination of the dosimeter characteristics is very important for laboratories of instrument calibration, as well as to determine how the various components of the detector may influence on the energy deposited in the sensitive volume. In this work, the results obtained about the influence of each one of the components present in this type of detector in standard mammography beams is presented. The code MCNP5 was used. The results allowed the adaptation of the detector to the desired conditions. (author)

Dosimetric Comparison in Breast Radiotherapy of 4 MV and 6 MV on Physical Chest Simulator

Energy Technology Data Exchange (ETDEWEB)

Donato da Silva, Sabrina; Passos Ribeiro Campos, Tarcisio [Nuclear Engineering Department, Federal University of Minas Gerais, Belo Horizonte (Brazil); Batista Nogueira, Luciana [Anatomy and Imaging Department, Federal University of Minas Gerais, Belo Horizonte (Brazil); Lima Souza Castro, Andre [Nuclear Engineering Department, Federal University of Minas Gerais, Belo Horizonte (Brazil); Institute of Radiation San Francisco, Belo Horizonte (Brazil); Alves de oliveira, Marcio; Galvao Dias, Humberto [Cancer Hospital in Uberlandia, Uberlandia (Brazil)

2015-07-01

According to the World Health Organization (2014) breast cancer is the main cause of death by cancer in women worldwide. The biggest challenge of radiotherapy in the treatment of cancer is to deposit the entire prescribed dose homogeneously in the breast, sparing the surrounding tissue. In this context, this paper aimed at evaluating and comparing internal dose distribution in the mammary gland based on experimental procedures submitted to two distinct energy spectra produced in breast cancer radiotherapy. The methodology consisted of reproducing opposite parallel fields used in the treatment of breast tumors in a chest phantom. This simulator with synthetic breast, composed of equivalent tissue material (TE), was previously developed by the NRI Research Group (UFMG). The computer tomography (CT) scan of the simulator was obtained antecedently. The radiotherapy planning systems (TPS) in the chest phantom were performed in the ECLIPSE system from Varian Medical Systems and CAT 3D system from MEVIS. The irradiations were reproduced in the Varian linear accelerator, model SL- 20 Precise, 6 MV energy and Varian linear accelerator, 4 MV Clinac 6x SN11 model. Calibrations of the absorbed dose versus optical density from radiochromic films were generated in order to obtain experimental dosimetric distribution at the films positioned within the glandular and skin equivalent tissues of the chest phantom. The spatial dose distribution showed equivalence with the TPS on measurement data performed in the 6 MV spectrum. The average dose found in radiochromic films placed on the skin ranged from 49 to 79%, and from 39 to 49% in the mammary areola, for the prescribed dose. Dosimetric comparisons between the spectra of 4 and 6 MV, keeping the constant geometry of the fields applied in the same phantom, will be presented showing their equivalence in breast radiotherapy, as well as the variations will be discussed. To sum up, the dose distribution has reached the value expected in

Effect of photon energy spectrum on dosimetric parameters of brachytherapy sources.

Science.gov (United States)

Ghorbani, Mahdi; Mehrpouyan, Mohammad; Davenport, David; Ahmadi Moghaddas, Toktam

2016-06-01

The aim of this study is to quantify the influence of the photon energy spectrum of brachytherapy sources on task group No. 43 (TG-43) dosimetric parameters. Different photon spectra are used for a specific radionuclide in Monte Carlo simulations of brachytherapy sources. MCNPX code was used to simulate 125I, 103Pd, 169Yb, and 192Ir brachytherapy sources. Air kerma strength per activity, dose rate constant, radial dose function, and two dimensional (2D) anisotropy functions were calculated and isodose curves were plotted for three different photon energy spectra. The references for photon energy spectra were: published papers, Lawrence Berkeley National Laboratory (LBNL), and National Nuclear Data Center (NNDC). The data calculated by these photon energy spectra were compared. Dose rate constant values showed a maximum difference of 24.07% for 103Pd source with different photon energy spectra. Radial dose function values based on different spectra were relatively the same. 2D anisotropy function values showed minor differences in most of distances and angles. There was not any detectable difference between the isodose contours. Dosimetric parameters obtained with different photon spectra were relatively the same, however it is suggested that more accurate and updated photon energy spectra be used in Monte Carlo simulations. This would allow for calculation of reliable dosimetric data for source modeling and calculation in brachytherapy treatment planning systems.

Dosimetric investigations in mammography

International Nuclear Information System (INIS)

Metges, P.J.; Lorrain, S.

1981-01-01

The development film-screen detectors in radiological equipment has led us to study how to improve standard mammographic pictures (focus 0.3 x 0.3 mm, focus-film distance: 65) of thick and dense breasts by the use of an anti-scatter grid and by magnification. A dosimetric study was necessary to assess the doses delivered during mammographic examinations carried out according to various procedures. The results led to modify breast examination procedures and use an anti-scatter grid for breasts thicker than 4 cm or known as dense. The dose increase due to a better quality image is the lowest provided depth penetration is increased by 2 kV as compared to a standard picture. Absorbed doses on the X-ray axis, at 3 cm depth, are below 0.1 rad [fr

Quality control of dosimetric systems using thermoluminescent crystals

International Nuclear Information System (INIS)

Mahecha, L.; Plazas, M. C.; Machado, M.; Perea, M. D.

2006-01-01

To achieve an optimal tumoral control to prostate cancer in early and locally advanced stages, it is necessary to increase the dose with a low mobility probability at the vesicle an rectal level. This is achieved through conformal radiotherapy. The Instituto Nacional de Cancerologia uses this technique, but two questions arise from the medical-physicists and medical radio-oncologist: In accordance with clinical protocols, the conformal radiotherapy delivers a low dose to the adjacent healthy tissues. What experimental method exists that can prove with certainly the veracity of this affirmation?. And, Do the dosimetric simulation system calculate suitable the dose for each tissues?. Through thermoluminescent dosimetry and the use of a physical simulator,we measured the absorbed dose at the target volume and the adjacent tissues using conformal and conventional radiotherapy. We proved that organs such as the rectum and bladder, receiver a minor dose in conformal radiotherapy, hence reducing their mobility probability. In addition, the readings from the thermoluminescent dosimeters and the doses calculated by the ECLIPSE dosimetric system were compared, concluding that the patient's prescribed dose is effectively delivered as recommended by the quality control program in radiotherapy. (Author)

Dosimetric verification of the intensity-modulated radiation therapy

International Nuclear Information System (INIS)

Zou Huawei; Jia Mingxuan; Wu Rong; Xiao Fuda; Dong Xiaoqi

2004-01-01

Objective: To discuss the methods of the dosimetric verification in the intensity-modulated radiation therapy (IMRT) and insure correct execution of the IMRT planning in the clinical practice. Methods: The CMSFOCUS9200 inverse planning system was used to provide optimized 5-field IMRT treatment plans for the patients. A phantom was made from true water-equivalent material. The doses of the interesting points and isodose distributions of the interesting planes in the phantom were calculated using patients' treatment plan. The phantom was placed on the couch of the accelerator and was irradiated using the phantom's treatment planning data. The doses of interesting points were measured using a 0.23 cc chamber and the isodose distributions of interesting planes were measured using RIT 113 film dosimetry system in the phantom. The results were compared with those from calculation in planning system for verification. Results: The doses and isodose distributions measured by the chamber and the film were consistent with those predicted by the planning. The error between the measured dose and calculated dose in the interesting points was less than 3%. Conclusion: The dosimetric verification of IMRT is a reliable measure in the course of its implementation. (authors)

Dose reader of dosimetric foil; Czytnik dawki folii dozymetrycznej

Energy Technology Data Exchange (ETDEWEB)

Machaj, B.; Strzalkowski, J.; Smolko, K.

1997-12-31

Read out the absorbance of a dosimetric foil is accomplished by two beam spectrophotometer. Such a solution makes possible the compensation of light source instabilities and ensures higher stability of the dose reader. The error of absorbance measurement caused by the instabilities does not exceed 0.0004 A. (author). 3 refs, 3 figs.

Response of the 'patient dose calibrator' chamber for incident positions and sizes of X-ray fields

International Nuclear Information System (INIS)

Oliveira, Cassio M.; Abrantes, Marcos Eugenio S.; Ferreira, Flavia C. Bastos; Lacerda, Marco A. de Souza; Alonso, Thessa C.; Silva, Teogenes A. da; Oliveira, Paulo Marcio C.

2009-01-01

The evaluation of patient doses is an important tool for optimizing radiodiagnostic medical procedures with conventional X-ray equipment and for improving the quality of the radiographic image. The Patient Dose Calibrator (PDC) chamber is a dosimetric instrument that is used in the evaluation of the air kerma-area product (P KA ) quantity aiming the reduction of patient doses. The objective this work was to study the P KA variation caused by different field incident positions and sizes of the X-ray beam on the PDC chamber. Results showed that the PDC chamber has repeatability lower than 0.6%, beam position dependence of 3% and linearity response within ± 6%; these characteristics are to be taken into account during evaluation of the radiological protection conditions of conventional x-ray equipment. (author)

Biologic data, models, and dosimetric methods for internal emitters

International Nuclear Information System (INIS)

Weber, D.A.

1990-01-01

The absorbed radiation dose from internal emitters has been and will remain a pivotal factor in assessing risk and therapeutic utility in selecting radiopharmaceuticals for diagnosis and treatment. Although direct measurements of absorbed dose and dose distributions in vivo have been and will continue to be made in limited situations, the measurement of the biodistribution and clearance of radiopharmaceuticals in human subjects and the use of this data is likely to remain the primary means to approach the calculation and estimation of absorbed dose from internal emitters over the next decade. Since several approximations are used in these schema to calculate dose, attention must be given to inspecting and improving the application of this dosimetric method as better techniques are developed to assay body activity and as more experience is gained in applying these schema to calculating absorbed dose. Discussion of the need for considering small scale dosimetry to calculate absorbed dose at the cellular level will be presented in this paper. Other topics include dose estimates for internal emitters, biologic data mathematical models and dosimetric methods employed. 44 refs

Use of secondary phosphorescence for determination of the dose absorbed in dosimetric phosphors

CERN Document Server

Yaek, I V

2002-01-01

The measuring method of optically stimulated persistence (OSP) based on both the time division of the stimulating irradiation and luminescent response registration was applied for the radiation dosimetry. It was shown that the stimulation by the short-wave radiation crossing with spectrum of the dosimetric phosphor is possible. The spectrum of the stimulation of industry dosimetric phosphors was measured. The characteristics of the OSP registration for the phosphors which has manganese Mn sup 2 sup + as the activator is considered. Decay time of inner center luminescence is 40-50 ms. This method is used for the dosimetry of the natural quartzes to determine their age.

SU-F-T-30: Comprehensive Dosimetric Characterization of the Novel Direction Modulation Brachytherapy (DMBT) Tandem Applicator Using Monte Carlo Simulations

Energy Technology Data Exchange (ETDEWEB)

Safigholi, H; Mashouf, S; Soliman, Abraam; Owrangi, A; Song, W Y [Deprtment of Medical Physics, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, ON (Canada); Han, D [Deprtment of Medical Physics, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, ON (Canada); Department of Radiation Oncology, University of California San Francisco, San Francisco, CA (United States)

2016-06-15

Purpose: To characterize the dosimetric properties/distributions of the novel proposed direction modulated brachytherapy (DMBT) tandem applicator in combination with 192Ir HDR source, and compare against conventional tandem design, using Monte Carlo simulations. Methods: The proposed DMBT tandem applicator is designed for image-guided adaptive brachytherapy, especially MRI, of cervical cancer. It has 6 peripheral holes of 1.3-mm width, grooved along a 5.4-mm diameter nonmagnetic tungsten alloy rod of density 18.0 g/cc, capable of generating directional dose profiles – leading to enhanced dose sculpting capacity through inverse planning. In-water dosimetric parameters for the DMBT and conventional tandems have been calculated for various radial distances away and around the tandems. For the DMBT tandem, the cumulative dose from the 192Ir source occupying 1) one and 2) all six holes in equal dwell times was calculated and normalized to match the dose rate of the open source (in conventional tandem) at 1 cm from the center. This is done to compare and contrast the characteristic dose distributions to that of the isotropic TG43-based 192Ir source. Results: All dose rates were normalized at 1-cm radius from the center of the applicators, containing source(s). The normalized dose rates at 0.5, 3.0, and 5.0-cm radiuses were then 388, 11.3, and 4.1% for conventional tandem, 657, 8.1, and 2.7% for DMBT tandem with the source in one hole at front entrance, and 436, 10.9, and 3.8% for DMBT tandem with the source in all six holes. For the DMBT tandem case with the source in one hole, the backside transmissions were 47, 2.4, and 0.9%, respectively. Conclusion: The DMBT tandem is able to generate closely similar dosimetric characteristics as that of the single-channel conventional tandem if needed (with the source occupying all six holes), at the same time, generate directional radiation profile(s) for favorably enabling 3D dose sculpting capability.

Development and calibration of a portable detection device for in vivo measurement of high-energy photon emitters incorporated by humans

International Nuclear Information System (INIS)

Soares, A.B.; Arbach, M.N.; Lucena, E.A.; Dantas, A.L.A.; Dantas, B.M.

2017-01-01

This work presents the evaluation of the applicability and sensitivity of a portable detection device specially designed for in vivo measurement of high-energy photon emitters in the human body. The calibration was performed at the In-Vivo Monitoring Laboratory of the IRD. The equipment consists of a lead-collimated NaI (Tl) 3″ x 3″ scintillation detector assembled on a tripod. The detector and its compact associated electronics are connected via USB cable to a portable PC. Spectrum acquisition and analysis is controlled by specific commercially available software. The calibration was performed using a standard liquid source of 152 Eu contained in 3 L polyethylene bottles. The evaluation of the system is based on the estimation of the minimum committed effective doses associated to the minimum detectable activities, calculated using current biokinetic and dosimetric models available in the literature. The dose detection limits for selected radionuclides of interest in an emergency scenario have shown to be far below 1 mSv allowing the system to be useful in accident situations. (author)

Development and calibration of a portable detection device for in vivo measurement of high-energy photon emitters incorporated by humans

Energy Technology Data Exchange (ETDEWEB)

Soares, A.B.; Arbach, M.N.; Lucena, E.A.; Dantas, A.L.A.; Dantas, B.M., E-mail: alexandrebaso@globo.com [Instituto de Radioproteção e Dosimetria (IRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil). Lab. de Monitoração Interna

2017-07-01

This work presents the evaluation of the applicability and sensitivity of a portable detection device specially designed for in vivo measurement of high-energy photon emitters in the human body. The calibration was performed at the In-Vivo Monitoring Laboratory of the IRD. The equipment consists of a lead-collimated NaI (Tl) 3″ x 3″ scintillation detector assembled on a tripod. The detector and its compact associated electronics are connected via USB cable to a portable PC. Spectrum acquisition and analysis is controlled by specific commercially available software. The calibration was performed using a standard liquid source of {sup 152}Eu contained in 3 L polyethylene bottles. The evaluation of the system is based on the estimation of the minimum committed effective doses associated to the minimum detectable activities, calculated using current biokinetic and dosimetric models available in the literature. The dose detection limits for selected radionuclides of interest in an emergency scenario have shown to be far below 1 mSv allowing the system to be useful in accident situations. (author)

Dosimetric verification for primary focal hypermetabolism of nasopharyngeal carcinoma patients treated with dynamic intensity-modulated radiation therapy.

Science.gov (United States)

Xin, Yong; Wang, Jia-Yang; Li, Liang; Tang, Tian-You; Liu, Gui-Hong; Wang, Jian-She; Xu, Yu-Mei; Chen, Yong; Zhang, Long-Zhen

2012-01-01

To make sure the feasibility with (18F)FDG PET/CT to guided dynamic intensity-modulated radiation therapy (IMRT) for nasopharyngeal carcinoma patients, by dosimetric verification before treatment. Chose 11 patients in III~IVA nasopharyngeal carcinoma treated with functional image-guided IMRT and absolute and relative dosimetric verification by Varian 23EX LA, ionization chamber, 2DICA of I'mRT Matrixx and IBA detachable phantom. Drawing outline and making treatment plan were by different imaging techniques (CT and (18F)FDG PET/CT). The dose distributions of the various regional were realized by SMART. The absolute mean errors of interest area were 2.39%±0.66 using 0.6 cc ice chamber. Results using DTA method, the average relative dose measurements within our protocol (3%, 3 mm) were 87.64% at 300 MU/min in all filed. Dosimetric verification before IMRT is obligatory and necessary. Ionization chamber and 2DICA of I'mRT Matrixx was the effective dosimetric verification tool for primary focal hyper metabolism in functional image-guided dynamic IMRT for nasopharyngeal carcinoma. Our preliminary evidence indicates that functional image-guided dynamic IMRT is feasible.

Patient-specific dosimetric endpoints based treatment plan quality control in radiotherapy

International Nuclear Information System (INIS)

Song, Ting; Zhou, Linghong; Staub, David; Chen, Mingli; Lu, Weiguo; Tian, Zhen; Jia, Xun; Li, Yongbao; Jiang, Steve B; Gu, Xuejun

2015-01-01

In intensity modulated radiotherapy (IMRT), the optimal plan for each patient is specific due to unique patient anatomy. To achieve such a plan, patient-specific dosimetric goals reflecting each patient’s unique anatomy should be defined and adopted in the treatment planning procedure for plan quality control. This study is to develop such a personalized treatment plan quality control tool by predicting patient-specific dosimetric endpoints (DEs). The incorporation of patient specific DEs is realized by a multi-OAR geometry-dosimetry model, capable of predicting optimal DEs based on the individual patient’s geometry. The overall quality of a treatment plan is then judged with a numerical treatment plan quality indicator and characterized as optimal or suboptimal. Taking advantage of clinically available prostate volumetric modulated arc therapy (VMAT) treatment plans, we built and evaluated our proposed plan quality control tool. Using our developed tool, six of twenty evaluated plans were identified as sub-optimal plans. After plan re-optimization, these suboptimal plans achieved better OAR dose sparing without sacrificing the PTV coverage, and the dosimetric endpoints of the re-optimized plans agreed well with the model predicted values, which validate the predictability of the proposed tool. In conclusion, the developed tool is able to accurately predict optimally achievable DEs of multiple OARs, identify suboptimal plans, and guide plan optimization. It is a useful tool for achieving patient-specific treatment plan quality control. (paper)

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

Energy Technology Data Exchange (ETDEWEB)

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

2016-06-15

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

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

International Nuclear Information System (INIS)

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

2016-01-01

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

Measurements of air kerma index in computed tomography: a comparison among methodologies

International Nuclear Information System (INIS)

Alonso, T. C.; Mourao, A. P.; Da Silva, T. A.

2016-10-01

Computed tomography (CT) has become the most important and widely used technique for diagnosis purpose. As CT exams impart high doses to patients in comparison to other radiologist techniques, reliable dosimetry is required. Dosimetry in CT is done in terms of air kerma index in air or in a phantom measured by a pencil ionization chamber under a single X-ray tube rotation. In this work, a comparison among CT dosimetric quantities measured by an UNFORS pencil ionization chamber, MTS-N RADOS thermoluminescent dosimeters and GAFCHROMIC XR-CT radiochromic film was done. The three dosimetric systems were properly calibrated in X-ray reference radiations in a calibration laboratory. CT dosimetric quantities were measured in CT Bright Speed GE Medical Systems Inc., scanner in a PMMA trunk phantom and a comparison among the three dosimetric techniques was done. (Author)

Measurements of air kerma index in computed tomography: a comparison among methodologies

Energy Technology Data Exchange (ETDEWEB)

Alonso, T. C.; Mourao, A. P.; Da Silva, T. A., E-mail: alonso@cdtn.br [Universidade Federal de Minas Gerais, Programa de Ciencia y Tecnicas Nucleares, Av. Pres. Antonio Carlos 6627, Pampulha, 31270-901 Belo Horizonte, Minas Gerais (Brazil)

2016-10-15

Computed tomography (CT) has become the most important and widely used technique for diagnosis purpose. As CT exams impart high doses to patients in comparison to other radiologist techniques, reliable dosimetry is required. Dosimetry in CT is done in terms of air kerma index in air or in a phantom measured by a pencil ionization chamber under a single X-ray tube rotation. In this work, a comparison among CT dosimetric quantities measured by an UNFORS pencil ionization chamber, MTS-N RADOS thermoluminescent dosimeters and GAFCHROMIC XR-CT radiochromic film was done. The three dosimetric systems were properly calibrated in X-ray reference radiations in a calibration laboratory. CT dosimetric quantities were measured in CT Bright Speed GE Medical Systems Inc., scanner in a PMMA trunk phantom and a comparison among the three dosimetric techniques was done. (Author)

Medical linear accelerator mounted mini-beam collimator: design, fabrication and dosimetric characterization.

Science.gov (United States)

Cranmer-Sargison, G; Crewson, C; Davis, W M; Sidhu, N P; Kundapur, V

2015-09-07

The goal of this work was to design, build and experimentally characterize a linear accelerator mounted mini-beam collimator for use at a nominal 6 MV beam energy. Monte Carlo simulation was used in the design and dosimetric characterization of a compact mini-beam collimator assembly mounted to a medical linear accelerator. After fabrication, experimental mini-beam dose profiles and central axis relative output were measured and the results used to validate the simulation data. The simulation data was then used to establish traceability back to an established dosimetric code of practice. The Monte Carlo simulation work revealed that changes in collimator blade width have a greater influence on the valley-to-peak dose ratio than do changes in blade height. There was good agreement between the modeled and measured profile data, with the exception of small differences on either side of the central peak dose. These differences were found to be systematic across all depths and result from limitations associated with the collimator fabrication. Experimental mini-beam relative output and simulation data agreed to better than ± 2.0%, which is well within the level of uncertainty required for dosimetric traceability of non-standard field geometries. A mini-beam collimator has now been designed, built and experimentally characterized for use with a commercial linear accelerator operated at a nominal 6 MV beam energy.

SU-F-T-19: The Consistency Dosimetric Analysis of the Accelerated Breast Brachytherapy

Energy Technology Data Exchange (ETDEWEB)

Pinder, J; Chandrasekara, S; Pella, S [21st Century Oncology, Boca Raton, FL (United States)

2016-06-15

Purpose: To assess the best approach in accept a treatment plan for APBI Savi patients. Should we run a treatment verification test prior to delivering it to the patient? Should we check each CT scan in regards to the initial one in dosimetrical terms? Do we need deformable registration and adaptive planning for each fraction? These are the questions we want to answer running a dosimetric analysis of the dose variances for APBI treatments who receive 10 fractions and no re-planning has been done being considered unnecessary with today’s means of assessment. Methods: A retrospective analysis of 30 patients treated with SAVI applicators were considered for this study. The CT scans taken before each treatment were imported in the treatment planning system and registered with the initial CT scan. The images were fused together with respective to the applicator, using landmark registration. Dosimetric evaluations were performed. Dose received by skin, ribs and PTV on CT images with respect to the initial treatment plan were recorded including maximum, average and minimum dose Results: All the structures displayed changes in volume over the 10 fractions of treatment. The cavities reduction in volume was considerable with a maximum reduction of over 10%. The PTV-eval is covered better due to this fact while the critical organs manifest an increase in the total and maximum dose delivered. Ribs and skin surface that are required by B39 protocol to be monitored can acquire maximum doses of 20% to 30% respectively. Conclusion: A dosimetric evaluation prior to the initial treatment and prior to each of the 10 fractions is proven to be necessary. Deformable registration and adaptive planning have to be studied more and eventually implemented for every patient who received more than one fraction of any type of brachytherapy treatment. Immobilization ad localization methods must be improved and studied further.

Secondary calibration laboratory for dosimetry in levels of therapy at the University of Santiago; Laboratorio secundario de calibracion para dosimetria en niveles de terapia en la Universidad de Santiago

Energy Technology Data Exchange (ETDEWEB)

Gomez Rodriguez, F.; Gonzalez Castano, D. M.; Pazos Alvarez, A.

2011-07-01

A basic inherent benefits provided by the existence of a traceability chain radiation in any application, add the legal requirement for hospitals as pointed to by the RO. 1566/1998, which sets quality standards in radiotherapy. The decree attributed to hospital specialists radio physics in article 10 the responsibility for determining the acceptance and initial reference state of radiation generating equipment for therapeutic purposes, and the establishment and implementation of quality control programs associated and technical and physical aspects of radiation dosimetry. Different international organizations such as ICRU and IAEA recommendations on maintaining the accuracy of the dose delivered to patients in general, should be placed at least 5% considering the whole chain irradiation. In order to achieve this purpose it is necessary to establish programs of quality control and calibration dosimetric regular basis. The protocol of the IAEA TRS398 recommended dose calibration in water because it is a quantity of interest closest to clinical use and allows a relative uncertainty in the calibration environment reduced to 1%.. (Author)

Monte Carlo dosimetric characterization of the Flexisource Co-60 high-dose-rate brachytherapy source using PENELOPE.

Science.gov (United States)

Almansa, Julio F; Guerrero, Rafael; Torres, Javier; Lallena, Antonio M

60 Co sources have been commercialized as an alternative to 192 Ir sources for high-dose-rate (HDR) brachytherapy. One of them is the Flexisource Co-60 HDR source manufactured by Elekta. The only available dosimetric characterization of this source is that of Vijande et al. [J Contemp Brachytherapy 2012; 4:34-44], whose results were not included in the AAPM/ESTRO consensus document. In that work, the dosimetric quantities were calculated as averages of the results obtained with the Geant4 and PENELOPE Monte Carlo (MC) codes, though for other sources, significant differences have been quoted between the values obtained with these two codes. The aim of this work is to perform the dosimetric characterization of the Flexisource Co-60 HDR source using PENELOPE. The MC simulation code PENELOPE (v. 2014) has been used. Following the recommendations of the AAPM/ESTRO report, the radial dose function, the anisotropy function, the air-kerma strength, the dose rate constant, and the absorbed dose rate in water have been calculated. The results we have obtained exceed those of Vijande et al. In particular, the absorbed dose rate constant is ∼0.85% larger. A similar difference is also found in the other dosimetric quantities. The effect of the electrons emitted in the decay of 60 Co, usually neglected in this kind of simulations, is significant up to the distances of 0.25 cm from the source. The systematic and significant differences we have found between PENELOPE results and the average values found by Vijande et al. point out that the dosimetric characterizations carried out with the various MC codes should be provided independently. Copyright © 2017 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.

Correlation between gamma index passing rate and clinical dosimetric difference for pre-treatment 2D and 3D volumetric modulated arc therapy dosimetric verification.

Science.gov (United States)

Jin, X; Yan, H; Han, C; Zhou, Y; Yi, J; Xie, C

2015-03-01

To investigate comparatively the percentage gamma passing rate (%GP) of two-dimensional (2D) and three-dimensional (3D) pre-treatment volumetric modulated arc therapy (VMAT) dosimetric verification and their correlation and sensitivity with percentage dosimetric errors (%DE). %GP of 2D and 3D pre-treatment VMAT quality assurance (QA) with different acceptance criteria was obtained by ArcCHECK® (Sun Nuclear Corporation, Melbourne, FL) for 20 patients with nasopharyngeal cancer (NPC) and 20 patients with oesophageal cancer. %DE were calculated from planned dose-volume histogram (DVH) and patients' predicted DVH calculated by 3DVH® software (Sun Nuclear Corporation). Correlation and sensitivity between %GP and %DE were investigated using Pearson's correlation coefficient (r) and receiver operating characteristics (ROCs). Relatively higher %DE on some DVH-based metrics were observed for both patients with NPC and oesophageal cancer. Except for 2%/2 mm criterion, the average %GPs for all patients undergoing VMAT were acceptable with average rates of 97.11% ± 1.54% and 97.39% ± 1.37% for 2D and 3D 3%/3 mm criteria, respectively. The number of correlations for 3D was higher than that for 2D (21 vs 8). However, the general correlation was still poor for all the analysed metrics (9 out of 26 for 3D 3%/3 mm criterion). The average area under the curve (AUC) of ROCs was 0.66 ± 0.12 and 0.71 ± 0.21 for 2D and 3D evaluations, respectively. There is a lack of correlation between %GP and %DE for both 2D and 3D pre-treatment VMAT dosimetric evaluation. DVH-based dose metrics evaluation obtained from 3DVH will provide more useful analysis. Correlation and sensitivity of %GP with %DE for VMAT QA were studied for the first time.

The accident of stereotaxic radiosurgery at the University hospital center of Toulouse. Expert report n.2. Dosimetric and clinical evaluation. Risk analysis

International Nuclear Information System (INIS)

2008-01-01

The regional center of stereotaxic radiosurgery (C.R.R.S.) of the University hospital center (C.H.U.) of Toulouse is equipped since april 2006 with a Novalis accelerator (Brainlab) devoted to radiosurgery and intra skull stereotaxic radiotherapy.In april 2007, during an intercomparison of dosimetry files coming from various sites, the Brainlab society detects an anomaly. The analysis made by the society concludes to the use of an unsuited detector for the measurement of a dosimetry parameter during the accelerator initial calibration. Following this error, 145 patients (on 172 patients treated since the center opening) suffer of an overdose whom importance is variable. On the 26. june 2007 the Authority of nuclear safety (Asn) requires an expertise on the following points: checking of the experimental protocols of micro-beams calibration before and after correction of the dysfunction; analysis at the theoretical level of the neurological complications risk at long term for the exposed patients. The second point of this request is the subject of this report. It gives the synthesis of the whole of information, at the clinical and dosimetric level and outlines successively: the expertise methodology; the cohort of patients treated at the C.R.R.S.; the parameters of the risk analysis of neurological complications; the different risk analysis according the pathologies treated at the C.R.R.S.; the recommendations. (N.C.)

Dosimetric evaluation of proton stereotactic radiosurgery

International Nuclear Information System (INIS)

Min, Byung Jun; Shin, Dong Ho; Yoo, Seung Hoon; Jeong, Hojin; Lee, Se Byeong

2011-01-01

Surgical excision, conventional external radiotherapy, and chemotherapy could prolong survival in patients with small intracranial tumors. However, surgical excision for meningiomas located in the region of the base of skull or re-resection is often difficult. Moreover, treatment is needed for patients with recurrent tumors or postoperative residual tumors. Conventional external radiotherapy is popular and has significantly increased for treating brain tumors. Stereotactic radiosurgery is an effective alternative treatment technique to microsurgical resection such as benign brain tumor or vestibular Schwannomas. In general, the dose to OAR of 3D conformal plan is lower than that of conformal arc and dynamic conformal arc plans. However, any of OARs was not reached to tolerance dose. Although mean dose of the healthy brain tissue for 3D conformal plan was slightly higher than that of arc plans, the doses of the healthy brain tissue at V10 and V20 were significantly low for dynamic conformal arc plan. The dosimetric differences were the greatest at lower doses. In contrast, 3D conformal plan was better spare at higher doses. In this study, a dosimetric evaluation of proton stereotactic radiosurgery for brain lesion tumors was using fixed and arc beams. A brass block fitted to the PTV structure was modeled for dynamic conformal collimator. Although all treatment plans offer a very good coverage of the PTV, we found that proton arc plans had significantly better conformity to the PTV than static 3D conformal plan. The V20 dose of normal brain for dynamic conformal arc therapy is dramatically reduced compare to those for other therapy techniques.

Dosimetric quantities and basic data for the evaluation of generalised derived limits

International Nuclear Information System (INIS)

Harrison, N.T.; Simmonds, J.R.

1980-12-01

The procedures, dosimetric quantities and basic data to be used for the evaluation of Generalised Derived Limits (GDLs) in environmental materials and of Generalised Derived Limits for discharges to atmosphere are described. The dosimetric considerations and the appropriate intake rates for both children and adults are discussed. In most situations in the nuclear industry and in those institutions, hospitals and laboratories which use relatively small quantities of radioactive material, the Generalised Derived Limits provide convenient reference levels against which the results of environmental monitoring can be compared, and atmospheric discharges can be assessed. They are intended for application when the environmental contamination or discharge to atmosphere is less than about 5% of the Generalised Derived Limit; above this level, it will usually be necessary to undertake a more detailed site-specific assessment. (author)

Dosimetric systems developed in Brazil for the radiation processes quality control

International Nuclear Information System (INIS)

Galante, Ana Maria Sisti; Campos, Leticia Lucente

2011-01-01

In order to apply new technologies to the industrial processing of materials aiming economy, efficiency, speed and high quality, ionizing radiation has been used in medicine, archaeology, chemistry, food preservation and other areas. For this reason, the dosimetry area looks for improve current dosimeters and develop new materials for application on quality control of these processes. In Brazil, the research in the dosimetry area occurs with great speed providing many different dosimetric systems. The chemical dosimetry is the most used technique in routine dosimetry, which requires fast and accurate responses. This technique involves determination of absorbed dose by measuring chemical changes radiation induced in the materials. Different dosimetric systems were developed at IPEN for application on radiation process quality and all of them present excellent results; the low cost of these materials allows a more effective dose control, therefore, a larger area or volume can be monitored. (author).

Using measurable dosimetric quantities to characterize the inter-structural tradeoff in inverse planning

Science.gov (United States)

Liu, Hongcheng; Dong, Peng; Xing, Lei

2017-08-01

Traditional inverse planning relies on the use of weighting factors to balance the conflicting requirements of different structures. Manual trial-and-error determination of weighting factors has long been recognized as a time-consuming part of treatment planning. The purpose of this work is to develop an inverse planning framework that parameterizes the dosimetric tradeoff among the structures with physically meaningful quantities to simplify the search for clinically sensible plans. In this formalism, instead of using weighting factors, the permissible variation range of the prescription dose or dose volume histogram (DVH) of the involved structures are used to characterize the ‘importance’ of the structures. The inverse planning is then formulated into a convex feasibility problem, called the dosimetric variation-controlled model (DVCM), whose goal is to generate plans with dosimetric or DVH variations of the structures consistent with the pre-specified values. For simplicity, the dosimetric variation range for a structure is extracted from a library of previous cases which possess similar anatomy and prescription. A two-phase procedure (TPP) is designed to solve the model. The first phase identifies a physically feasible plan to satisfy the prescribed dosimetric variation, and the second phase automatically improves the plan in case there is room for further improvement. The proposed technique is applied to plan two prostate cases and two head-and-neck cases and the results are compared with those obtained using a conventional CVaR approach and with a moment-based optimization scheme. Our results show that the strategy is able to generate clinically sensible plans with little trial and error. In all cases, the TPP generates a very competitive plan as compared to those obtained using the alternative approaches. Particularly, in the planning of one of the head-and-neck cases, the TPP leads to a non-trivial improvement in the resultant dose distribution�

Postoperative telegammatherapy of breast cancer (Dosimetric studies)

Energy Technology Data Exchange (ETDEWEB)

Todorov, J; Mitrov, G [Nauchno-Izsledovatelski Onkologichen Inst., Sofia (Bulgaria); Konstantinov, B; Dobrev, D [Meditsinska Akademiya, Sofia (Bulgaria). Nauchen Inst. po Rentgenologiya i Radiobiologiya

1977-01-01

The method employed for postoperative radiation therapy of breast cancer at the Radiologic Clinic of the Medical Academy in Sofia is described. Results are reported and discussed of dosimetric studies carried out with the T-100 on heterogeneous tissue-equivalent Rando phantom for dose distributions in the regional lymph basin and the underlying tissues and organs. The results show coincidence between calculated and measured doses in the regional lymph basin and the thoracic wall. It was demonstrated that maximal radiation loading (3600 to 5500 rad) occurs in the apical and the hilar lung area.

The use of megavoltage CT (MVCT) images for dose recomputations

International Nuclear Information System (INIS)

Langen, K M; Meeks, S L; Poole, D O; Wagner, T H; Willoughby, T R; Kupelian, P A; Ruchala, K J; Haimerl, J; Olivera, G H

2005-01-01

Megavoltage CT (MVCT) images of patients are acquired daily on a helical tomotherapy unit (TomoTherapy, Inc., Madison, WI). While these images are used primarily for patient alignment, they can also be used to recalculate the treatment plan for the patient anatomy of the day. The use of MVCT images for dose computations requires a reliable CT number to electron density calibration curve. In this work, we tested the stability of the MVCT numbers by determining the variation of this calibration with spatial arrangement of the phantom, time and MVCT acquisition parameters. The two calibration curves that represent the largest variations were applied to six clinical MVCT images for recalculations to test for dosimetric uncertainties. Among the six cases tested, the largest difference in any of the dosimetric endpoints was 3.1% but more typically the dosimetric endpoints varied by less than 2%. Using an average CT to electron density calibration and a thorax phantom, a series of end-to-end tests were run. Using a rigid phantom, recalculated dose volume histograms (DVHs) were compared with plan DVHs. Using a deformed phantom, recalculated point dose variations were compared with measurements. The MVCT field of view is limited and the image space outside this field of view can be filled in with information from the planning kVCT. This merging technique was tested for a rigid phantom. Finally, the influence of the MVCT slice thickness on the dose recalculation was investigated. The dosimetric differences observed in all phantom tests were within the range of dosimetric uncertainties observed due to variations in the calibration curve. The use of MVCT images allows the assessment of daily dose distributions with an accuracy that is similar to that of the initial kVCT dose calculation

Dosimetric response of united, commercially available CTA foils for sup 6 sup 0 Co gamma rays

CERN Document Server

Peimel-Stuglik, Z

2001-01-01

The usefulness of two kinds of untinted CTA foils: Fuji CTR-125 dosimetric foil and technical CTA-T foil, produced by 'Zaklady Chemiczne, 'Gorzow Wielkopolski' as support for light-sensitive layers of amateur photo-films, for sup 6 sup 0 Co gamma ray dosimetry was investigated. In spite of rather bad physical parameters of the technical foil (spread of foil thickness, high and different initial absorbance) the dosimetric response of both foils for sup 6 sup 0 Co gamma rays was similar. The CTA-T foil can be used for routine dosimetry providing that dosimetric signals have to be calculated exactly as recommended by the ASTM (American Society for Testing and Materials) standard, i.e. as the difference of absorbance of irradiated and (the same) non-irradiated foil. Any other approach may lead to high errors of dose evaluation. The last is true also for other CTA foils, especially after long self-life.

Dosimetric characteristics of Li2B4O7:Cu,Ag,P solid TL detectors

International Nuclear Information System (INIS)

Proki, M.

2002-01-01

The main dosimetric characteristics are presented of newly prepared tissue-equivalent, highly sensitive thermoluminescent detector, Li 2 B 4 O 7 :Cu,Ag,P in the form of sintered pellets, developed at the Institute of Nuclear Sciences, Vin a . As a result of an advancement in the preparation procedure by the sensitising of basic copper activated lithium borate TL material, significant improvement in the TL sensitivity of Li 2 B 4 O 7 :Cu,Ag,P was gained. The glow curve of Li 2 B 4 O 7 :Cu,Ag,P consists of well defined main dosimetric peak situated at about 185-190 deg. C with the TL sensitivity which is about four to five times higher than that of LiF:Mg,Ti (TLD-100). From the experimental results a very wide linear dose response range, up to 10 3 Gy is evident. Dosimetric characteristics make sintered solid Li 2 B 4 O 7 :Cu,Ag,P TL detectors very promising for different dosimetry applications particularly in medical dosimetry and also for individual monitoring. (author)

Our calibrated model has poor predictive value: An example from the petroleum industry

Energy Technology Data Exchange (ETDEWEB)

Carter, J.N. [Department of Earth Science and Engineering, Imperial College, London (United Kingdom)]. E-mail: j.n.carter@ic.ac.uk; Ballester, P.J. [Department of Earth Science and Engineering, Imperial College, London (United Kingdom); Tavassoli, Z. [Department of Earth Science and Engineering, Imperial College, London (United Kingdom); King, P.R. [Department of Earth Science and Engineering, Imperial College, London (United Kingdom)

2006-10-15

It is often assumed that once a model has been calibrated to measurements then it will have some level of predictive capability, although this may be limited. If the model does not have predictive capability then the assumption is that the model needs to be improved in some way. Using an example from the petroleum industry, we show that cases can exit where calibrated models have limited predictive capability. This occurs even when there is no modelling error present. It is also shown that the introduction of a small modelling error can make it impossible to obtain any models with useful predictive capability. We have been unable to find ways of identifying which calibrated models will have some predictive capacity and those which will not.

Our calibrated model has poor predictive value: An example from the petroleum industry

International Nuclear Information System (INIS)

Carter, J.N.; Ballester, P.J.; Tavassoli, Z.; King, P.R.

2006-01-01

It is often assumed that once a model has been calibrated to measurements then it will have some level of predictive capability, although this may be limited. If the model does not have predictive capability then the assumption is that the model needs to be improved in some way. Using an example from the petroleum industry, we show that cases can exit where calibrated models have limited predictive capability. This occurs even when there is no modelling error present. It is also shown that the introduction of a small modelling error can make it impossible to obtain any models with useful predictive capability. We have been unable to find ways of identifying which calibrated models will have some predictive capacity and those which will not

In-Flight Calibration of GF-1/WFV Visible Channels Using Rayleigh Scattering

Directory of Open Access Journals (Sweden)

Xingfeng Chen

2017-05-01

Full Text Available China is planning to launch more and more optical remote-sensing satellites with high spatial resolution and multistep gains. Field calibration, the current operational method of satellite in-flight radiometric calibration, still does not have enough capacity to meet these demands. Gaofen-1 (GF-1, as the first satellite of the Chinese High-resolution Earth Observation System, has been specially arranged to obtain 22 images over clean ocean areas using the Wide Field Viewing camera. Following this, Rayleigh scattering calibration was carried out for the visible channels with these images after the appropriate data processing steps. To guarantee a high calibration precision, uncertainty was analyzed in advance taking into account ozone, aerosol optical depth (AOD, seawater salinity, chlorophyll concentration, wind speed and solar zenith angle. AOD and wind speed were found to be the biggest error sources, which were also closely coupled to the solar zenith angle. Therefore, the best sample data for Rayleigh scattering calibration were selected at the following solar zenith angle of 19–22° and wind speed of 5–13 m/s to reduce the reflection contributed by the water surface. The total Rayleigh scattering calibration uncertainties of visible bands are 2.44% (blue, 3.86% (green, and 4.63% (red respectively. Compared with the recent field calibration results, the errors are −1.69% (blue, 1.83% (green, and −0.79% (red. Therefore, the Rayleigh scattering calibration can become an operational in-flight calibration method for the high spatial resolution satellites.

Radioecological and dosimetric consequences of the Chernobyl accident in France

International Nuclear Information System (INIS)

Renaud, Ph.; Beaugelin, K.; Maubert, H.; Ledenvic, Ph.

1997-11-01

This study has as objective a survey of the radioecological and dosimetric consequences of the Chernobyl accident in France, as well as a prognosis for the years to come. It was requested by the Direction of Nuclear Installation Safety (DSIN) in relation to different organisms which effected measurements after this accident. It is based on the use of combined results of measurements and modelling by means of the code ASTRAL developed at IPSN. Various measurements obtained from five authorities and institutions, were made available, such as: activity of air and water, soil, processed food, agricultural and natural products. However, to achieve the survey still a modelling is needed. ASTRAL is a code for evaluating the ecological consequences of an accident. It allows establishing the correspondence between the soil Remnant Surface Activities (RSA, in Bq.m -2 ), the activity concentration of the agricultural production and the individual and collective doses resulting from external and internal exposures (due to inhalation and ingestion of contaminated nurture). The results of principal synthesis documents on the Chernobyl accident and its consequences were also used. The report is structured in nine sections, as follows: 1.Introduction; 2.Objective and methodology; 3.Characterization of radioactive depositions; 4;Remnant surface activities; 5.Contamination of agricultural products and foods; 6.Contamination of natural, semi-natural products and of drinking water; 7.Dosimetric evaluations; 8.Proposals for the environmental surveillance; 9.Conclusion. Finally, after ten years, one concludes that at present the dosimetric consequences of the Chernobyl accident in France were rather limited. For the period 1986-2046 the average individual effective dose estimated for the most struck zone is lower than 1500 μSv, which represents almost 1% of the average natural exposure for the same period. At present, the cesium 137 levels are at often inferior to those recorded before

Another look at volume self-calibration: calibration and self-calibration within a pinhole model of Scheimpflug cameras

International Nuclear Information System (INIS)

Cornic, Philippe; Le Besnerais, Guy; Champagnat, Frédéric; Illoul, Cédric; Cheminet, Adam; Le Sant, Yves; Leclaire, Benjamin

2016-01-01

We address calibration and self-calibration of tomographic PIV experiments within a pinhole model of cameras. A complete and explicit pinhole model of a camera equipped with a 2-tilt angles Scheimpflug adapter is presented. It is then used in a calibration procedure based on a freely moving calibration plate. While the resulting calibrations are accurate enough for Tomo-PIV, we confirm, through a simple experiment, that they are not stable in time, and illustrate how the pinhole framework can be used to provide a quantitative evaluation of geometrical drifts in the setup. We propose an original self-calibration method based on global optimization of the extrinsic parameters of the pinhole model. These methods are successfully applied to the tomographic PIV of an air jet experiment. An unexpected by-product of our work is to show that volume self-calibration induces a change in the world frame coordinates. Provided the calibration drift is small, as generally observed in PIV, the bias on the estimated velocity field is negligible but the absolute location cannot be accurately recovered using standard calibration data. (paper)

Determination of dosimetric quantities in pediatric abdominal computed tomography scans

Energy Technology Data Exchange (ETDEWEB)

Jornada, Tiago da Silva [Universidade Federal de Sao Paulo (UNIFESP), Sao Paulo, SP (Brazil). Escola Paulista de Medicina. Dept. de Diagnostipo por Imagem; Silva, Teogenes Augusto da, E-mail: silvata@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)

2014-09-15

Objective: aiming at contributing to the knowledge on doses in computed tomography (CT), this study has the objective of determining dosimetric quantities associated with pediatric abdominal CT scans, comparing the data with diagnostic reference levels (DRL). Materials and methods: the study was developed with a Toshiba Asteion single-slice CT scanner and a GE BrightSpeed multi-slice CT unit in two hospitals. Measurements were performed with a pencil-type ionization chamber and a 16 cm-diameter polymethylmethacrylate trunk phantom. Results: No significant difference was observed in the values for weighted air kerma index (C{sub W}), but the differences were relevant in values for volumetric air kerma index (C{sub VOL}), air kerma-length product (P{sub KL,CT}) and effective dose. Conclusion: Only the CW values were lower than the DRL, suggesting that dose optimization might not be necessary. However, P{sub KL,CT} and effective dose values stressed that there still is room for reducing pediatric radiation doses. The present study emphasizes the importance of determining all dosimetric quantities associated with CT scans. (author)

Determination of dosimetric quantities in pediatric abdominal computed tomography scans*

Science.gov (United States)

Jornada, Tiago da Silva; da Silva, Teógenes Augusto

2014-01-01

Objective Aiming at contributing to the knowledge on doses in computed tomography (CT), this study has the objective of determining dosimetric quantities associated with pediatric abdominal CT scans, comparing the data with diagnostic reference levels (DRL). Materials and methods The study was developed with a Toshiba Asteion single-slice CT scanner and a GE BrightSpeed multi-slice CT unit in two hospitals. Measurements were performed with a pencil-type ionization chamber and a 16 cm-diameter polymethylmethacrylate trunk phantom. Results No significant difference was observed in the values for weighted air kerma index (CW), but the differences were relevant in values for volumetric air kerma index (CVOL), air kerma-length product (PKL,CT) and effective dose. Conclusion Only the CW values were lower than the DRL, suggesting that dose optimization might not be necessary. However, PKL,CT and effective dose values stressed that there still is room for reducing pediatric radiation doses. The present study emphasizes the importance of determining all dosimetric quantities associated with CT scans. PMID:25741103

Study on the neutron dosimetric characteristics of Tissue Equivalent Proportional Counter

Energy Technology Data Exchange (ETDEWEB)

Nunomiya, T.; Kim, E.; Kurosawa, T.; Taniguchi, S.; Nakamura, T. [Tohoku Univ., Sendai (Japan). Cyclotron and Radioisotope Center; Tsujimura, N.; Momose, T.; Shinohara, K. [Japan Nuclear Cycle Development Inst., Environment and Safety Division, Tokai Works, Tokai, Ibaraki (Japan)

1999-03-01

The neutron dosimetric characteristics of TEPC (Tissue Equivalent Proportional Counter) has been investigated under a cooperative study between Tohoku University and JNC since 1997. This TEPC is a spherical, large volume, single-wire proportional counter (the model LETSW-5, manufactured by Far West Technology, Inc.) and filled with a tissue equivalent gas in a spherical detector of the A-150 tissue equivalent plastic. The TEPC can measure the spectra of absorbed dose in LET and easily estimate the tissue equivalent dose to neutron. This report summarizes the dosimetric characteristics of TEPC to the monoenergetic neutrons with energy from 8 keV to 15 MeV. It is found that TEPC can estimate the ambient dose equivalent, H*(10), with an accuracy from 0.9 to 2 to the neutron above 0.25 MeV and TEPC has a good counting efficiency enough to measure neutron doses with low dose rate at the stray neutron fields. (author)

Dosimetric tests for treatment planning commissioning in 3DCRT; Testes dosimetricos para comissionamento de sistemas de planejamento em radioterapia 3DCRT

Energy Technology Data Exchange (ETDEWEB)

Goncalves, Leandro R.; Pieri, Karen; Silva, Marco A.; Santos, Gabriela R.; Sales, Camila P.; Rubo, Rodrigo A.; Nakandakari, Marcos V.N.; Cunha, Ana Paula V; Santos, Caroline Z.; Rodrigues, Laura N.; Furnari, Laura, E-mail: leandrorg11@hotmail.com [Universidade de Sao Paulo (USP), SP (Brazil). Hospital das Clinicas. Servico de Radioterapia

2012-12-15

The radiotherapy evolution from 2D treatments to 3D conformal treatments was possible after the advent the treatment planning systems commercially available and tridimensional images techniques like computed tomography. These systems have tools that allow delineate anatomical structures from tomographic images. Calculations dose tools allow the planner evaluate the dose received in the anatomical structures. When these systems are acquired or an upgrade is made many dosimetric and non-dosimetric tests need to be performed to know the system limitations and correct functioning and to verify the correct dosimetric data insertion. This study was based in International Atomic Energy Agency protocols, Task Groups documents from American Association of Physics in Medicine, and other papers. A dosimetric test set was done to commissioning the Eclipse 10.0.28 (Varian Medical Systems) treatments planning system This version has two photon calculation algorithm (Pencil Beam Convolution and Analytical Anisotropic Algorithm – AAA) and Gaussian Pencil Beam algorithm for electron beams. However, tests for AAA it was not performed. In this study was possible to conclude that the dosimetric data was correctly added in the treatment planning system. Some results allowed to understand the algorithm limitations to calculate dose distributions in specifics situations, that was not clinically relevant in our routine. (author)

Dosimetric characteristics of the Novoste Beta-Cath 90Sr/Y source trains at submillimeter distances

International Nuclear Information System (INIS)

Roa, Dante E.; Song Haijun; Yue Ning; D'Errico, Francesco; Nath, Ravinder

2004-01-01

Measurements were performed on the 30, 40, and 60 mm 90 Sr/Y β-emitter source trains used in the Novoste Beta-Cath system to determine their dosimetric characteristics at submillimeter distances and provide the necessary TG-60 parameters for mapping their dose distributions. These measurements were carried out in a Solid Water TM phantom where MD55-2 Gafchromic TM films were placed in direct contact with a 5 French (F) catheter used for the 30 and 60 mm source trains and a 3.5F catheter used for thinner 30 and 40 mm source trains. A data set consisted of three pieces of Gafchromic film irradiated for periods of 1.5, 5, and 10 minutes, respectively. This 3-film irradiation technique provided reliable dose data at short, intermediate and long distances from a source train. Three data sets per source train were collected in this study. For the 30 mm source train with a 5F catheter, data were collected with the source axis at proximal (0.41 mm) and distal (1.19 mm) positions to the film surface in order to investigate dosimetric effects due to the off centering of the source train lumen within the catheter. Absolute doses were determined by calibrating the Gafchromic film in a high-energy electron beam from a radiotherapy accelerator. The absolute dose rates at a distance of 2 mm along the source trains transverse axis were found to be within 13.7% of the values provided by Novoste. Radial dose functions were within 13% compared to 90 Sr/Y source train data constructed from Soares' 90 Sr/Y single seed data and within 17% and 25% compared to Monte Carlo data by Ye et al., and Wang et al., respectively. Discrepancies of 33% and 19% were observed at short radial distances (≤1 mm) between the Novoste Monte Carlo and the 3.5F and 5F catheter measured data, respectively. The source off centering data showed higher dose contribution from the source train at its distal rather than proximal position. Radial dose function comparisons between the Novoste Monte Carlo and the

Calibration uncertainty

DEFF Research Database (Denmark)

Heydorn, Kaj; Anglov, Thomas

2002-01-01

Methods recommended by the International Standardization Organisation and Eurachem are not satisfactory for the correct estimation of calibration uncertainty. A novel approach is introduced and tested on actual calibration data for the determination of Pb by ICP-AES. The improved calibration...

A national dosimetric audit of IMRT

International Nuclear Information System (INIS)

Budgell, Geoff; Berresford, Joe; Trainer, Michael; Bradshaw, Ellie; Sharpe, Peter; Williams, Peter

2011-01-01

Background and purpose: A dosimetric audit of IMRT has been carried out within the UK between June 2009 and March 2010 in order to provide an independent check of safe implementation and to identify problems in the modelling and delivery of IMRT. Methods and materials: A mail based audit involving film and alanine dosimeters was utilized. Measurements were made for each individual field in an IMRT plan isocentrically in a flat water-equivalent phantom at a depth of 5 cm. The films and alanine dosimeters were processed and analysed centrally; additional ion chamber measurements were made by each participating centre. Results: 57 of 62 centres participated, with a total of 78 plans submitted. For the film measurements, all 176 fields from the less complex IMRT plans (including prostate and breast plans) achieved over 95% pixels passing a gamma criterion of 3%/3 mm within the 20% isodose. For the more complex IMRT plans (mainly head and neck) 8/245 fields (3.3%) achieved less than 95% pixels passing a 4%/4 mm gamma criterion. Of the alanine measurements, 4/78 (5.1%) of the measurements differed by >5% from the dose predicted by the treatment planning system. Three of these were large deviations of -77.1%, -29.1% and 14.1% respectively. Excluding the three measurements outside 10%, the mean difference was 0.05% with a standard deviation of 1.5%. The out of tolerance results have been subjected to further investigations. Conclusions: A dosimetric audit has been successfully carried out of IMRT implementation by over 90% of UK radiotherapy departments. The audit shows that modelling and delivery of IMRT is accurate, suggesting that the implementation of IMRT has been carried out safely.

Research on SOC Calibration of Large Capacity Lead Acid Battery

Science.gov (United States)

Ye, W. Q.; Guo, Y. X.

2018-05-01

Large capacity lead-acid battery is used in track electric locomotive, and State of Charge (SOC) is an important quantitative parameter of locomotive power output and operating mileage of power emergency recovery vehicle. But State of Charge estimation has been a difficult part in the battery management system. In order to reduce the SOC estimation error better, this paper uses the linear relationship of Open Circuit Voltage (OCV) and State of Charge to fit the SOC-OCV curve equation by MATLAB. The method proposed in this paper is small, easy to implement and can be used in the battery non-working state SOC estimation correction, improve the estimation accuracy of SOC.

Development and calibration of a portable detection system for in vivo monitoring of {sup 131}I incorporation by humans

Energy Technology Data Exchange (ETDEWEB)

Lucena, Eder A.; Dantas, Ana Leticia A.; Dantas, Bernardo M. [Instituto de Radioprotecao e Dosimetria (IRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil)], e-mail: eder@ird.gov.br

2009-07-01

{sup 131}I is one of the most frequently used radionuclides for diagnosis and therapy of thyroid diseases in nuclear medicine. Its increasing use for medical purposes creates a demand for feasible methodologies applied to the control of internal exposure by workers. In vivo monitoring of {sup 131}I incorporation is of great value for the evaluation of occupational exposure during its medical application and also in the case of accidents and incidents in nuclear power plants for the monitoring of workers and population. This work presents the development of a portable device specially designed for in vivo measurement of {sup 131}I in the thyroid. It is also presented the results of the calibration performed in different nuclear medicine centers where {sup 131}I is routinely manipulated for therapeutic purposes. The equipment consists in a NaI(Tl)3''x3'' detector installed in a lead collimator and assembled on a tripod. The detection system was calibrated with the IRD-Neck-Thyroid phantom for the determination of the calibration factors for direct in vivo quantification of {sup 131}I in the thyroid. In order to evaluate the applicability and limitations of the system, committed effective doses associated to the minimum detectable activities were calculated using current biokinetic and dosimetric models available in the literature. Dose detection limits have shown to be far below 1 mSv for the most likely incorporation scenarios. (author)

TU-D-9A-01: TG176: Dosimetric Effects of Couch Tops and Immobilization Devices

International Nuclear Information System (INIS)

Olch, A

2014-01-01

The dosimetric impact from devices external to the patient is a complex combination of increased skin dose, reduced tumor dose, and altered dose distribution. Although small monitor unit or dose corrections are routinely made for blocking trays, ion chamber correction factors, or tissue inhomogeneities, the dose perturbation of the treatment couch top or immobilization devices are often overlooked. These devices also increase surface dose, an effect which is also often ignored or underestimated. These concerns have grown recently due to the increased use of monolithic carbon fiber couch tops which are optimal for imaging for patient position verification but cause attenuation and increased surface dose compared to the ‘tennis racket’ style couch top they often replace. Also, arc delivery techniques have replaced stationary gantry techniques which cause a greater fraction of the dose to be delivered from posterior angles. A host of immobilization devices are available and used to increase patient positioning reproducibility, and these also have attenuation and skin dose implications which are often ignored. This report of Task Group 176 serves to present a survey of published data that illustrates the magnitude of the dosimetric effects of a wide range of devices external to the patient. The report also provides methods for modeling couch tops in treatment planning systems so the physicist can accurately compute the dosimetric effects for indexed patient treatments. Both photon and proton beams are considered. A discussion on avoidance of high density structures during beam planning is also provided. An important aspect of this report are the recommendations we make to clinical physicists, treatment planning system vendors, and device vendors on how to make measurements of skin dose and attenuation, how to report these values, and for the vendors, an appeal is made to work together to provide accurate couch top models in planning systems. Learning Objectives

Dosimetric Consequences of Interobserver Variability in Delineating the Organs at Risk in Gynecologic Interstitial Brachytherapy

International Nuclear Information System (INIS)

Damato, Antonio L.; Townamchai, Kanopkis; Albert, Michele; Bair, Ryan J.; Cormack, Robert A.; Jang, Joanne; Kovacs, Arpad; Lee, Larissa J.; Mak, Kimberley S.; Mirabeau-Beale, Kristina L.; Mouw, Kent W.; Phillips, John G.; Pretz, Jennifer L.; Russo, Andrea L.; Lewis, John H.; Viswanathan, Akila N.

2014-01-01

Purpose: To investigate the dosimetric variability associated with interobserver organ-at-risk delineation differences on computed tomography in patients undergoing gynecologic interstitial brachytherapy. Methods and Materials: The rectum, bladder, and sigmoid of 14 patients treated with gynecologic interstitial brachytherapy were retrospectively contoured by 13 physicians. Geometric variability was calculated using κ statistics, conformity index (CI gen ), and coefficient of variation (CV) of volumes contoured across physicians. Dosimetric variability of the single-fraction D 0.1cc and D 2cc was assessed through CV across physicians, and the standard deviation of the total EQD2 (equivalent dose in 2 Gy per fraction) brachytherapy dose (SD TOT ) was calculated. Results: The population mean ± 1 standard deviation of κ, CI gen , and volume CV were, respectively: 0.77 ± 0.06, 0.70 ± 0.08, and 20% ± 6% for bladder; 0.74 ± 06, 0.67 ± 0.08, and 20% ± 5% for rectum; and 0.33 ± 0.20, 0.26 ± 0.17, and 82% ± 42% for sigmoid. Dosimetric variability was as follows: for bladder, CV = 31% ± 19% (SD TOT = 72 ± 64 Gy) for D 0.1cc and CV = 16% ± 10% (SD TOT = 9 ± 6 Gy) for D 2cc ; for rectum, CV = 11% ± 5% (SD TOT = 16 ± 17 Gy) for D 0.1cc and CV = 7% ± 2% (SD TOT = 4 ± 3 Gy) for D 2cc ; for sigmoid, CV = 39% ± 28% (SD TOT = 12 ± 18 Gy) for D 0.1cc and CV = 34% ± 19% (SD TOT = 4 ± 4 Gy) for D 2cc. Conclusions: Delineation of bladder and rectum by 13 physicians demonstrated substantial geometric agreement and resulted in good dosimetric agreement for all dose-volume histogram parameters except bladder D 0.1cc. Small delineation differences in high-dose regions by the posterior bladder wall may explain these results. The delineation of sigmoid showed fair geometric agreement. The higher dosimetric variability for sigmoid compared with rectum and bladder did not correlate with higher variability in the total brachytherapy dose but rather may be due to the

Tenon hospital 3-D dosimetric methodology for radiosurgery of complex AVMs

International Nuclear Information System (INIS)

Lefkopoulos, D.; Schlienger, M.; Plazas, M.C.; Laugier, A.

1990-01-01

This paper presents the methodology of the irradiation treatment planning for the calculation of the 3-D dose distribution developed at the Tenon Hospital since four years. This dosimetric method is independent of the Linac irradiation technique, thus is can be used with any other type of radiosurgery technique. (author)

A dynamic capacity degradation model and its applications considering varying load for a large format Li-ion battery

International Nuclear Information System (INIS)

Ouyang, Minggao; Feng, Xuning; Han, Xuebing; Lu, Languang; Li, Zhe; He, Xiangming

2016-01-01

Highlights: • A dynamic capacity degradation model for large format Li-ion battery is proposed. • The change of the model parameters directly link with the degradation mechanisms. • The model can simulate the fading behavior of Li-ion battery under varying loads. • The model can help evaluate the longevity of a battery system under specific load. • The model can help predict the evolution of cell variations within a battery pack. - Abstract: The capacity degradation of the lithium ion battery should be well predicted during battery system design. Therefore, high-fidelity capacity degradation models that are suitable for the task of capacity prediction are required. This paper proposes a novel capacity degradation model that can simulate the degradation dynamics under varying working conditions for large-format lithium ion batteries. The degradation model is built based on a mechanistic and prognostic model (MPM) whose parameters are closely linked with the degradation mechanisms of lithium ion batteries. Chemical kinetics was set to drive the parameters of the MPM to change as capacity degradation continues. With the dynamic parameters of the MPM, the capacity predicted by the degradation model decreases as the cycle continues. Accelerated aging tests were conducted on three types of commercial lithium ion batteries to calibrate the capacity degradation model. The good fit with the experimental data indicates that the model can capture the degradation mechanisms well for different types of commercial lithium ion batteries. Furthermore, the calibrated model can be used to (1) evaluate the longevity of a battery system under a specific working load and (2) predict the evolution of cell variations within a battery pack when different cell works at different conditions. Correlated applications are discussed using the calibrated degradation model.

Dosimetric verification for radiotherapy quality audit under reference and non-reference conditions in Jiangsu province

International Nuclear Information System (INIS)

Wang Jin; Yu Ningle; Yang Chunyong; Du Xiang; Chen Wei; Luo Suming

2014-01-01

Objective: To verify the methodology for auditing dosimetric parameters in reference and non-reference conditions with thermoluminescent dosimeters (TLDs). Methods: Under reference and non-reference conditions, the established TLD methods were used to observe the absorbed dose variations with depth, SSD, field size and 45 wedges for 10 photon beams at 5 hospitals. Dosimetric parameters, including doses at D_m_a_x points in axis, on 5 electron beams of 9 MeV were measured. The measurement results were compared between the TLDs and plane parallel ionization chambers. Results: For 6 MV photon beams, the relative deviation of between finger ionization chamber method and TLD chips was in the range of -1.7% to 5.4% under on-axis non-reference conditions, and -6.3% to -0.6% under off-axis non-reference conditions, respectively, all within the range of ≤ ±7% as required by the IAEA. The relative deviation between plane parallel chamber and TLD method was -2.3% to 3.7%, within ±5% as required by the IAEA. Conclusions: It is convenient and feasible to use TLD method for quality audits of dosimetric parameters in radiotherapy. (authors)

Development of an algorithm simulator of the planar radioactive source for dosimetric evaluations in accidents with radiopharmaceuticals used in nuclear medicine

International Nuclear Information System (INIS)

Claudino, Gutemberg L. Sales; Vieira, Jose Wilson; Leal Neto, Viriato; Lima, Fernando R. Andrade

2013-01-01

Objective of this work is to develop an algorithm simulator for dosimetric evaluation of accidents that may happen in Nuclear Medicine using PDF NT (Probability Density Functions). A software was developed using C# and WPF technology, in the integrated environment of Microsoft Visual Studio to organize and present the dosimetric results

Exposure-rate calibration using large-area calibration pads

International Nuclear Information System (INIS)

Novak, E.F.

1988-09-01

The US Department of Energy (DOE) Office of Remedial Action and Waste Technology established the Technical Measurements Center (TMC) at the DOE Grand Junction Projects Office (GJPO) in Grand Junction, Colorado, to standardize, calibrate, and compare measurements made in support of DOE remedial action programs. A set of large-area, radioelement-enriched concrete pads was constructed by the DOE in 1978 at the Walker Field Airport in Grand Junction for use as calibration standards for airborne gamma-ray spectrometer systems. The use of these pads was investigated by the TMC as potential calibration standards for portable scintillometers employed in measuring gamma-ray exposure rates at Uranium Mill Tailings Remedial Action (UMTRA) project sites. Data acquired on the pads using a pressurized ionization chamber (PIC) and three scintillometers are presented as an illustration of an instrumental calibration. Conclusions and recommended calibration procedures are discussed, based on the results of these data

Development and design of an antropomorphic model for electron dosimetric purposes

International Nuclear Information System (INIS)

Geske, G.; Geske, J.

1977-01-01

After discussing some problems related to the planning of therapeutic irradiation with fast electron the benifit of phantoms for electron dosimetric purposes is pointed out. The selection of tissue-equivalent materials for constructing a phantom is dicussed in detail. Finally, a model representing the upper part of a female body is described. (author)

Dosimetric complication probability and acoustic analysis of vocal cord region in oropharyngeal carcinoma treated with voice-sparing intensity modulated radiotherapy

International Nuclear Information System (INIS)

Jain, S.; Gupta, T.; Agarwal, J.P.; Baccher, G.; Shrivastava, S.K.; Reenadevi; Master, J.

2008-01-01

Radiation to larynx has long been associated with speech and voice dysfunction. The objective is to study dosimetric parameters and complication probability of vocal cord region (VCR) and the effect of voice-sparing (VS) in the patients treated with intensity modulated radiotherapy (IMRT). The secondary objective is to describe the post-radiation acoustic voice characteristics and correlate them with the dosimetric parameters. (author)

Quantitative analysis of patient-specific dosimetric IMRT verification

International Nuclear Information System (INIS)

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

2005-01-01

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

Beyond Californium-A Neutron Generator Alternative for Dosimetry and Instrument Calibration in the U.S.

Science.gov (United States)

Piper, Roman K; Mozhayev, Andrey V; Murphy, Mark K; Thompson, Alan K

2017-09-01

Evaluations of neutron survey instruments, area monitors, and personal dosimeters rely on reference neutron radiations, which have evolved from the heavy reliance on (α,n) sources to a shared reliance on (α,n) and the spontaneous fission neutrons of californium-252 (Cf). Capable of producing high dose equivalent rates from an almost point source geometry, the characteristics of Cf are generally more favorable when compared to the use of (α,n) and (γ,n) sources or reactor-produced reference neutron radiations. Californium-252 is typically used in two standardized configurations: unmoderated, to yield a fission energy spectrum; or with the capsule placed within a heavy-water moderating sphere to produce a softened spectrum that is generally considered more appropriate for evaluating devices used in nuclear power plant work environments. The U.S. Department of Energy Cf Loan/Lease Program, a longtime origin of affordable Cf sources for research, testing and calibration, was terminated in 2009. Since then, high-activity sources have become increasingly cost-prohibitive for laboratories that formerly benefited from that program. Neutron generators, based on the D-T and D-D fusion reactions, have become economically competitive with Cf and are recognized internationally as important calibration and test standards. Researchers from the National Institute of Standards and Technology and the Pacific Northwest National Laboratory are jointly considering the practicality and technical challenges of implementing neutron generators as calibration standards in the U.S. This article reviews the characteristics of isotope-based neutron sources, possible isotope alternatives to Cf, and the rationale behind the increasing favor of electronically generated neutron options. The evaluation of a D-T system at PNNL has revealed characteristics that must be considered in adapting generators to the task of calibration and testing where accurate determination of a dosimetric quantity is

Dosimetric Impact of Intrafractional Patient Motion in Pediatric Brain Tumor Patients

International Nuclear Information System (INIS)

Beltran, Chris; Trussell, John; Merchant, Thomas E.

2010-01-01

The purpose of this study was to determine the dosimetric consequences of intrafractional patient motion on the clinical target volume (CTV), spinal cord, and optic nerves for non-sedated pediatric brain tumor patients. The patients were immobilized for treatment using a customized thermoplastic full-face mask and bite-block attached to an array of reflectors. The array was optically tracked by infra-red cameras at a frequency of 10 Hz. Patients were localized based on skin/mask marks and weekly films were taken to ensure proper setup. Before each noncoplanar field was delivered, the deviation from baseline of the array was recorded. The systematic error (SE) and random error (RE) were calculated. Direct simulation of the intrafractional motion was used to quantify the dosimetric changes to the targets and critical structures. Nine patients utilizing the optical tracking system were evaluated. The patient cohort had a mean of 31 ± 1.5 treatment fractions; motion data were acquired for a mean of 26 ± 6.2 fractions. The mean age was 15.6 ± 4.1 years. The SE and RE were 0.4 and 1.1 mm in the posterior-anterior, 0.5 and 1.0 mm in left-right, and 0.6 and 1.3 mm in superior-inferior directions, respectively. The dosimetric effects of the motion on the CTV were negligible; however, the dose to the critical structures was increased. Patient motion during treatment does affect the dose to critical structures, therefore, planning risk volumes are needed to properly assess the dose to normal tissues. Because the motion did not affect the dose to the CTV, the 3-mm PTV margin used is sufficient to account for intrafractional motion, given the patient is properly localized at the start of treatment.

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

International Nuclear Information System (INIS)

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

2006-01-01

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

Prospective assessment of dosimetric/physiologic-based models for predicting radiation pneumonitis

International Nuclear Information System (INIS)

Kocak, Zafer; Borst, Gerben R.; Zeng Jing; Zhou Sumin; Hollis, Donna R.; Zhang Junan; Evans, Elizabeth S.; Folz, Rodney J.; Wong, Terrence; Kahn, Daniel; Belderbos, Jose S.A.; Lebesque, Joos V.; Marks, Lawrence B.

2007-01-01

Purpose: Clinical and 3D dosimetric parameters are associated with symptomatic radiation pneumonitis rates in retrospective studies. Such parameters include: mean lung dose (MLD), radiation (RT) dose to perfused lung (via SPECT), and pre-RT lung function. Based on prior publications, we defined pre-RT criteria hypothesized to be predictive for later development of pneumonitis. We herein prospectively test the predictive abilities of these dosimetric/functional parameters on 2 cohorts of patients from Duke and Netherlands Cancer Institute (NKI). Methods and Materials: For the Duke cohort, 55 eligible patients treated between 1999 and 2005 on a prospective IRB-approved study to monitor RT-induced lung injury were analyzed. A similar group of patients treated at the NKI between 1996 and 2002 were identified. Patients believed to be at high and low risk for pneumonitis were defined based on: (1) MLD; (2) OpRP (sum of predicted perfusion reduction based on regional dose-response curve); and (3) pre-RT DLCO. All doses reflected tissue density heterogeneity. The rates of grade ≥2 pneumonitis in the 'presumed' high and low risk groups were compared using Fisher's exact test. Results: In the Duke group, pneumonitis rates in patients prospectively deemed to be at 'high' vs. 'low' risk are 7 of 20 and 9 of 35, respectively; p = 0.33 one-tailed Fisher's. Similarly, comparable rates for the NKI group are 4 of 21 and 6 of 44, respectively, p = 0.41 one-tailed Fisher's. Conclusion: The prospective model appears unable to accurately segregate patients into high vs. low risk groups. However, considered retrospectively, these data are consistent with prior studies suggesting that dosimetric (e.g., MLD) and functional (e.g., PFTs or SPECT) parameters are predictive for RT-induced pneumonitis. Additional work is needed to better identify, and prospectively assess, predictors of RT-induced lung injury

WE-G-BRA-04: Common Errors and Deficiencies in Radiation Oncology Practice

Energy Technology Data Exchange (ETDEWEB)

Kry, S; Dromgoole, L; Alvarez, P; Lowenstein, J; Molineu, A; Taylor, P; Followill, D [UT MD Anderson Cancer Center, Houston, TX (United States)

2015-06-15

Purpose: Dosimetric errors in radiotherapy dose delivery lead to suboptimal treatments and outcomes. This work reviews the frequency and severity of dosimetric and programmatic errors identified by on-site audits performed by the IROC Houston QA center. Methods: IROC Houston on-site audits evaluate absolute beam calibration, relative dosimetry data compared to the treatment planning system data, and processes such as machine QA. Audits conducted from 2000-present were abstracted for recommendations, including type of recommendation and magnitude of error when applicable. Dosimetric recommendations corresponded to absolute dose errors >3% and relative dosimetry errors >2%. On-site audits of 1020 accelerators at 409 institutions were reviewed. Results: A total of 1280 recommendations were made (average 3.1/institution). The most common recommendation was for inadequate QA procedures per TG-40 and/or TG-142 (82% of institutions) with the most commonly noted deficiency being x-ray and electron off-axis constancy versus gantry angle. Dosimetrically, the most common errors in relative dosimetry were in small-field output factors (59% of institutions), wedge factors (33% of institutions), off-axis factors (21% of institutions), and photon PDD (18% of institutions). Errors in calibration were also problematic: 20% of institutions had an error in electron beam calibration, 8% had an error in photon beam calibration, and 7% had an error in brachytherapy source calibration. Almost all types of data reviewed included errors up to 7% although 20 institutions had errors in excess of 10%, and 5 had errors in excess of 20%. The frequency of electron calibration errors decreased significantly with time, but all other errors show non-significant changes. Conclusion: There are many common and often serious errors made during the establishment and maintenance of a radiotherapy program that can be identified through independent peer review. Physicists should be cautious, particularly

WE-G-BRA-04: Common Errors and Deficiencies in Radiation Oncology Practice

International Nuclear Information System (INIS)

Kry, S; Dromgoole, L; Alvarez, P; Lowenstein, J; Molineu, A; Taylor, P; Followill, D

2015-01-01

Purpose: Dosimetric errors in radiotherapy dose delivery lead to suboptimal treatments and outcomes. This work reviews the frequency and severity of dosimetric and programmatic errors identified by on-site audits performed by the IROC Houston QA center. Methods: IROC Houston on-site audits evaluate absolute beam calibration, relative dosimetry data compared to the treatment planning system data, and processes such as machine QA. Audits conducted from 2000-present were abstracted for recommendations, including type of recommendation and magnitude of error when applicable. Dosimetric recommendations corresponded to absolute dose errors >3% and relative dosimetry errors >2%. On-site audits of 1020 accelerators at 409 institutions were reviewed. Results: A total of 1280 recommendations were made (average 3.1/institution). The most common recommendation was for inadequate QA procedures per TG-40 and/or TG-142 (82% of institutions) with the most commonly noted deficiency being x-ray and electron off-axis constancy versus gantry angle. Dosimetrically, the most common errors in relative dosimetry were in small-field output factors (59% of institutions), wedge factors (33% of institutions), off-axis factors (21% of institutions), and photon PDD (18% of institutions). Errors in calibration were also problematic: 20% of institutions had an error in electron beam calibration, 8% had an error in photon beam calibration, and 7% had an error in brachytherapy source calibration. Almost all types of data reviewed included errors up to 7% although 20 institutions had errors in excess of 10%, and 5 had errors in excess of 20%. The frequency of electron calibration errors decreased significantly with time, but all other errors show non-significant changes. Conclusion: There are many common and often serious errors made during the establishment and maintenance of a radiotherapy program that can be identified through independent peer review. Physicists should be cautious, particularly

Dosimetric Evaluation of Automatic Segmentation for Adaptive IMRT for Head-and-Neck Cancer

International Nuclear Information System (INIS)

Tsuji, Stuart Y.; Hwang, Andrew; Weinberg, Vivian; Yom, Sue S.; Quivey, Jeanne M.; Xia Ping

2010-01-01

Purpose: Adaptive planning to accommodate anatomic changes during treatment requires repeat segmentation. This study uses dosimetric endpoints to assess automatically deformed contours. Methods and Materials: Sixteen patients with head-and-neck cancer had adaptive plans because of anatomic change during radiotherapy. Contours from the initial planning computed tomography (CT) were deformed to the mid-treatment CT using an intensity-based free-form registration algorithm then compared with the manually drawn contours for the same CT using the Dice similarity coefficient and an overlap index. The automatic contours were used to create new adaptive plans. The original and automatic adaptive plans were compared based on dosimetric outcomes of the manual contours and on plan conformality. Results: Volumes from the manual and automatic segmentation were similar; only the gross tumor volume (GTV) was significantly different. Automatic plans achieved lower mean coverage for the GTV: V95: 98.6 ± 1.9% vs. 89.9 ± 10.1% (p = 0.004) and clinical target volume: V95: 98.4 ± 0.8% vs. 89.8 ± 6.2% (p 3 of the spinal cord 39.9 ± 3.7 Gy vs. 42.8 ± 5.4 Gy (p = 0.034), but no difference for the remaining structures. Conclusions: Automatic segmentation is not robust enough to substitute for physician-drawn volumes, particularly for the GTV. However, it generates normal structure contours of sufficient accuracy when assessed by dosimetric end points.

Dosimetric and patient correlates of quality of life after prostate stereotactic ablative radiotherapy

International Nuclear Information System (INIS)

Elias, Evelyn; Helou, Joelle; Zhang, Liying; Cheung, Patrick; Deabreu, Andrea; D’Alimonte, Laura; Sethukavalan, Perakaa; Mamedov, Alexandre; Cardoso, Marlene; Loblaw, Andrew

2014-01-01

Background and purpose: Initial results of Stereotactic Ablative Body Radiotherapy (SABR) in the treatment of localized prostate cancer appear promising however long-term quality of life (QOL) outcomes and dosimetric correlates are necessary. Material and methods: A phase I/II study was performed where low risk prostate cancer patients received SABR 35 Gy in 5 fractions, once weekly. Patient self-reported QOL was measured using the Expanded Prostate Cancer Index Composite (EPIC) at baseline and q6 month up to 5 years. Urinary, bowel and sexual domains were analyzed. A minimally clinical important change (MCIC) was defined as 0.5 ∗ standard deviation of the baseline. Univariate and multivariate logistic regression were used to identify dosimetric predictors of MCIC. Results: 84 patients were included. The median follow-up was 50.8 months (interquartile range [IQR], 44.7–56.3). 17.9%, 26.2% and 37.5% of patients reported worse QOL on follow up in the urinary, bowel and sexual domains respectively. On univariate analysis Rectal V31.8 > 10%, D1cc > 35 Gy were associated with bowel MCIC, penile bulb (PB) V35 > 4%, V20 > 40% with sexual MCIC. Of these factors only rectal D1cc and PB V35 were predictors of worse QOL on multivariate analysis. Conclusions: Long-term single-institution QOL outcomes are encouraging. Rigorous dosimetric constraints are needed to keep bothersome side effects low

Calibration of an accountability tank by bubbling pressure method: correction factors to be taken into account

International Nuclear Information System (INIS)

Cauchetier, Ph.

1993-01-01

To obtain the needed precision in the calibration of an accountability tank by bubbling pressure method, it requires to use very slow bubbling. The measured data (mass and pressure) must be transformed into physical sizes of the vessel (height and cubic capacity). All corrections to take in account (buoyancy, calibration curve of the sensor, density of the liquid, weight of the gas column, bubbling overpressure, temperature...) are reviewed and valuated. We give the used equations. (author). 3 figs., 1 tab., 2 refs

Measurement of dosimetric parameters for Hi-ART helical tomotherapy unit

International Nuclear Information System (INIS)

Wang Yunlai; Sha Xiangyou; Dai Xiangkun; Ma Lin; Feng Linchun; Qu Baolin

2008-01-01

Objective: To develop a measurement method of dosimetric parameters for Hi-ART tomotherapy unit. Methods: Percentage depth doses and beam profiles were measured using the dedicated mini water phantom, and compared to the results of 6 MV X-ray from Primus accelerator. Following the AAPM TG51 protocol, absolute dose calibration was carried out under SSD of 8.5 cm at depth of 1.5 cm for field of 5 cm x 40 cm. The output linearity and reproducibility were evaluated. The output variation with the gantry rotation was also investigated using 0.6 cm 3 ion chamber in cylindrical perplex phantom and on-board MVCT detectors. Leaf fluence output factors were quantified for the leaf of interest and its adjacent leaves. Results: The buildup depth was around 1.0 cm. The PDD values at 10 cm for Hi-ART and Primus were 59.7% and 64.7%, respectively. Varying with the field width, the lateral and longitudinal beam profiles were not so homogeneous as the Primus fields. The measured dose rate was 848.38 cGy/min. The fitted linear function between the readings of dosimeter and the irradiated time was R(nC) =-0.017 + 0.256· t(sec), with a relative coefficient of 0.999. The maximum deviation and standard deviation of output were 1.6% and less than 0.5%; The maximum deviation and standard deviation of output changed by gantry angle were 1.1% and 0.5%, respectively. Leaf fluence output factors did not increase significantly when leaves were opened beyond the two adjacent leaves. Conclusions: Hi-ART Tomotherapy unit has a very high dose output and inhomogeneous beam profiles owing to its special design of the treatment head. This may be useful in dose calculation and treatment delivery. (authors)

Dosimetric characteristics of a TLD dosemeter with extremities

International Nuclear Information System (INIS)

Molina P, D.; Diaz B, E.; Lien V, R.

1999-01-01

It was designed a TLD dosemeter for the monitoring of the extremities. This one consists in a metallic ring with a circular orifice where is arranged a T L detector of LiF: Mg,Ti (Model JR1152C) 5 x 5 x 0.8 mm 3 covered by a polyethylene fine layer. In this work were studied the dosimetric properties of the dosemeter for its application in the dosimetry of extremities for photonic radiation. the results obtained allow conclude that the designed dosemeter can be used for the extremities monitoring. (Author)

Dosimetric evaluation of Radiotherapy units wit 60Co

International Nuclear Information System (INIS)

Leon, B. Salinas de; Tovar M, V.; Becerril V, A.

2000-01-01

The SSDL network of the IAEA performs, every year, quality audit tests for radiotherapy services ( 60 Co units and linear accelerators), and for national SSDL as well. Because of the SSDL-Mexico results in these tests and due to our enthusiasm and confidence in our work, a parallel test has been done , which is described in this talk as well as the results. Nowadays, a second parallel test goes up, which could confirm our optimism and open the possibility to our country to start a national dosimetric audit of 60 Co radiotherapy units. (Author)

Intercomparison and calibration of dose calibrators used in nuclear medicine facilities

CERN Document Server

Costa, A M D

2003-01-01

The aim of this work was to establish a working standard for intercomparison and calibration of dose calibrators used in most of nuclear medicine facilities for the determination of the activity of radionuclides administered to patients in specific examinations or therapeutic procedures. A commercial dose calibrator, a set of standard radioactive sources, and syringes, vials and ampoules with radionuclide solutions used in nuclear medicine were utilized in this work. The commercial dose calibrator was calibrated for radionuclide solutions used in nuclear medicine. Simple instrument tests, such as linearity response and variation response with the source volume at a constant source activity concentration were performed. This instrument may be used as a reference system for intercomparison and calibration of other activity meters, as a method of quality control of dose calibrators utilized in nuclear medicine facilities.

Dosimetric characterization of GafChromic EBT film and its implication on film dosimetry quality assurance

International Nuclear Information System (INIS)

Fuss, Martina; Sturtewagen, Eva; Wagter, Carlos De; Georg, Dietmar

2007-01-01

scanner, presents a versatile system for high-precision dosimetry in two dimensions, provided that the intrinsic behaviour of the film reading device is taken into account. EBT film itself presents substantial improvements on formerly available models of radiographic and a radiochromic film and its dosimetric characteristics allow us to measure absorbed dose levels in a large variety of situations with a single calibration curve

Estimation of MIMO channel capacity from phase-noise impaired measurements

DEFF Research Database (Denmark)

Pedersen, Troels; Yin, Xuefeng; Fleury, Bernard Henri

2008-01-01

Due to the significantly reduced cost and effort for system calibration time-division multiplexing (TDM) is a commonly used technique to switch between the transmit and receive antennas in multiple-input multiple-output (MIMO) radio channel sounding. Nonetheless, Baum et al. [1], [2] have shown t...... matrix. It is shown by means of Monte Carlo simulations assuming a measurementbased phase noise model, that the MIMO channel capacity can be estimated accurately for signal to noise ratios up to about 35 dB......Due to the significantly reduced cost and effort for system calibration time-division multiplexing (TDM) is a commonly used technique to switch between the transmit and receive antennas in multiple-input multiple-output (MIMO) radio channel sounding. Nonetheless, Baum et al. [1], [2] have shown...... that phase noise of the transmitter and receiver local oscillators, when it is assumed to be a white Gaussian random process, can cause large errors of the estimated channel capacity of a low-rank MIMO channel when the standard channel matrix estimator is used. Experimental evidence shows that consecutive...

Impact of SPECT corrections on 3D-dosimetry for liver transarterial radioembolization using the patient relative calibration methodology

Energy Technology Data Exchange (ETDEWEB)

Pacilio, Massimiliano, E-mail: mpacilio@scamilloforlanini.rm.it; Basile, Chiara [Department of Medical Physics, Azienda Ospedaliera San Camillo Forlanini, Rome 00152 (Italy); Ferrari, Mahila; Botta, Francesca; Cremonesi, Marta [Department of Medical Physics, Istituto Europeo di Oncologia, Milan 20141 (Italy); Chiesa, Carlo [Department of Nuclear Medicine, Istituto Nazionale Tumori IRCCS Foundation, Milan 20133 (Italy); Lorenzon, Leda; Becci, Domenico [Postgraduate School of Medical Physics, “Sapienza” University of Rome, Rome 00185 (Italy); Mira, Marta [Post graduate Health Physics School, University of Milan, Milan 20122 (Italy); Torres, Leonel Alberto; Vergara Gil, Alex [Department of Nuclear Medicine, Clinical Research Division of the Center of Isotopes (DIC-CENTIS), Havana 11100 (Cuba); Coca Perez, Marco [Department of PET-CT and Nuclear Medicine, Imaging Center Medscan-Concepciòn, Concepciòn 4070061 (Chile); Ljungberg, Michael [Department of Medical Radiation Physics, University of Lund, Lund 22100 (Sweden); Pani, Roberto [Department of Medico-surgical Sciences and Biotecnologies, “Sapienza” University of Rome, Rome 00185 (Italy)

2016-07-15

Purpose: Many centers aim to plan liver transarterial radioembolization (TARE) with dosimetry, even without CT-based attenuation correction (AC), or with unoptimized scatter correction (SC) methods. This work investigates the impact of presence vs absence of such corrections, and limited spatial resolution, on 3D dosimetry for TARE. Methods: Three voxelized phantoms were derived from CT images of real patients with different body sizes. Simulations of {sup 99m}Tc-SPECT projections were performed with the SIMIND code, assuming three activity distributions in the liver: uniform, inside a “liver’s segment,” or distributing multiple uptaking nodules (“nonuniform liver”), with a tumoral liver/healthy parenchyma ratio of 5:1. Projection data were reconstructed by a commercial workstation, with OSEM protocol not specifically optimized for dosimetry (spatial resolution of 12.6 mm), with/without SC (optimized, or with parameters predefined by the manufacturer; dual energy window), and with/without AC. Activity in voxels was calculated by a relative calibration, assuming identical microspheres and {sup 99m}Tc-SPECT counts spatial distribution. 3D dose distributions were calculated by convolution with {sup 90}Y voxel S-values, assuming permanent trapping of microspheres. Cumulative dose-volume histograms in lesions and healthy parenchyma from different reconstructions were compared with those obtained from the reference biodistribution (the “gold standard,” GS), assessing differences for D95%, D70%, and D50% (i.e., minimum value of the absorbed dose to a percentage of the irradiated volume). γ tool analysis with tolerance of 3%/13 mm was used to evaluate the agreement between GS and simulated cases. The influence of deep-breathing was studied, blurring the reference biodistributions with a 3D anisotropic gaussian kernel, and performing the simulations once again. Results: Differences of the dosimetric indicators were noticeable in some cases, always negative

A custom made phantom for dosimetric audit and quality assurance of three-dimensional conformal radiotherapy

International Nuclear Information System (INIS)

Radaideh, K.M.; Matalqah, L.M.; Matalqah, L.M.; Tajuddin, A.A.; Luen, F.W.L.; Bauk, S.; Abdel Munem, E.M.E.

2012-01-01

The ultimate check of the actual dose delivered to a patient in radiotherapy can be achieved by using dosimetric measurements. The aims of this study were to develop and evaluate a custom handmade head and neck phantom for evaluation of Three-Dimensional Conformal Radiation Therapy (3D-CRT) dose planning and delivery. A phantom of head and neck region of a medium built male patient with nasopharyngeal cancer was constructed from Perspex material. Primary and secondary Planning Target Volume (PTV) and twelve Organs at Risk (OAR) were delineated using Treatment Planning System (TPS) guided by computed tomography printout transverse images. One hundred and seven (107) holes distributed among the organs were loaded with Rod-shaped Thermoluminescent dosimeters (LiF:Mg, Ti TLDs) after common and individual calibration. Head and neck phantom was imaged, planned and irradiated conformally (3D-CRT) by linear accelerator (LINAC Siemens Artiste). The planned predicted doses by TPS at PTV and OAR regions were obtained and compared with the TLD measured doses using the phantom. Repeated TLD measurements were reproducible with a percent standard deviation of < 3.5 %. Moreover, the average of dose discrepancies between TLDs reading and TPS predicted doses were found to be < 5.3 %. The phantom's preliminary results have proved to be a valuable tool for 3D-CRT treatment dose verification. (author)

Dosimetric studies in diagnostic radiology

International Nuclear Information System (INIS)

Mohamadain, K. E. M.

2004-04-01

A dosimetric study in pediatric radiology and adult patients was currently being carried out at the pediatrics units of two large hospitals in Rio de Janeiro city: IPPMG (Instituto de Pediatric e Puericultura Martagao Gesteira, University hospital of federal University of Rio de Janeiro), IFF (Instituto Fernandes Figueira, FIOCRUZ) and Hospital Geral de Bonsucesso, a large public hospital in Rio de Janeiro city (HGB) Brazil. The dosimetric study was also performed at three pediatrics units in Sudan, namely, Ahmed Gasim, Khartoum and Omdurman hospitals. For chest x-ray examination the entrance skin dose(ESD) for AP, PA and LAT projections of pediatric patients, and the scattered dose at the thyroid, ovary and gonads have been obtained with thermoluminescent dosimeters (TLD) and with use of a software package Dosecal in thr Brazilian hospitals, and with the software dosecal in the Sudanese hospitals.The aim of this work was to estimate the entrance skin dose (ESD), the effective dose (ED) and the body organ dose (BOD) for chest x-ray exposure in pediatric patients, and different exams for adults patients, and to compare the results obtained in the tow Countries Sudan and Brazil with the reference dose level. For ESD evaluation of the chest x-ray, three different TL dosimeters have been used, namely LiF: Mg, Ti (TLD 100) CaSo 4 : Dy and LiF:Mg, Cu,P (TLD 100 H). The age intervals considered were: 0-1 years, 1-5 years, 5-10 years and 10-15 years. The results obtained with all dosimeters were in good agreement with, those obtained by the dosecal software, especially for AP and PA projection. However, some discrepancies were found for the LAT projection. The results within Brazil were some what consistent while in Sudan, large difference were observed, it was also noted that the doses in Brazil hospitals were less than the reference dose levels while in Sudanese hospitals the doses were higher than the reference dose levels. For adult patients only the software dosecal

Dosimetric properties of MOS transistors

International Nuclear Information System (INIS)

Frank, H.; Petr, I.

1977-01-01

The structure of MOS transistors is described and their characteristics given. The experiments performed and data in the literature show the following dosimetric properties of MOS transistors: while for low gamma doses the transistor response to exposure is linear, it shows saturation for higher doses (exceeding 10 3 Gy in tissue). The response is independent of the energy of radiation and of the dose rate (within 10 -2 to 10 5 Gy/s). The spontaneous reduction with time of the spatial charge captured by the oxide layer (fading) is small and acceptable from the point of view of dosimetry. Curves are given of isochronous annealing of the transistors following irradiation with 137 Cs and 18 MeV electrons for different voltages during irradiation. The curves show that in MOS transistors irradiated with high-energy electrons the effect of annealing is less than in transistors irradiated with 137 Cs. In view of the requirement of using higher temperatures (approx. 400 degC) for the complete ''erasing'' of the captured charge, unsealed systems must be used for dosimetric purposes. The effect was also studied of neutron radiation, proton radiation and electron radiation on the MOS transistor structure. For MOS transistor irradiation with 14 MeV neutrons from a neutron generator the response was 4% of that for gamma radiation at the same dose equivalent. The effect of proton radiation was studied as related to the changes in MOS transistor structure during space flights. The response curve shapes are similar to those of gamma radiation curves. The effect of electron radiation on the MOS structure was studied by many authors. The experiments show that for each thickness of the SiO 2 layer an electron energy exists at which the size of the charge captured in SiO 2 is the greatest. All data show that MOS transistors are promising for radiation dosimetry. The main advantage of MOS transistors as gamma dosemeters is the ease and speed of evaluation, low sensitivity to neutron

Dosimetric characterization of a 2-D array of 223 solid state detectors for daily morning checks in Tomo Therapy equipment

International Nuclear Information System (INIS)

Reyes S, U.; Sosa A, M.; Vega C, H. R.

2015-10-01

Tomo Therapy is a new technique for the cancer treatment; however, the equipment must meet nearly all mechanical and dosimetric characteristics of a conventional linear accelerator for medical use. Daily quality controls are vital to the good operation of the equipment and thus guarantee excellent quality in the daily delivery of treatments. This paper presents the procedure of the dosimetric characterization of a two-dimensional array of 223 solid state detectors, called TomoDose of the Sun Nuclear Company. Dosimetric important criteria are established to perform these checks quickly and accurately. Dosimetric tests proposed are: repeatability, linearity, dependence of Sad and SSD. Some results are compared with readings of the ionization chamber Exradim A1SL. Finally the results of 30 consecutive days are presented to establish criteria for evidence of dose, field size, symmetry and flattening of the radiation beam on Tomo Therapy equipment. Expected values for daily verification are: Dose constancy of 194.89 c Gy, σ= 1.31 c Gy, symmetry in the X axis of -0.19 %, σ=0.08 %, symmetry in the Y axis of 1.66 %, σ= 0.05 %, flattened in the X axis of 25.71 %, σ= 0.05 % and flattened in the Y axis of 6.41 %, σ= 10.23 %. Field sizes obtained were 40.45 cm in the X axis and 5.10 on the Y axis, with standard deviations of 0.02 cm and 0.01 cm, respectively. TomoDose dosimetric values, compared to the values obtained with ionization chamber, presented differences smaller than 2%. (Author)

High Accuracy Transistor Compact Model Calibrations

Energy Technology Data Exchange (ETDEWEB)

Hembree, Charles E. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Mar, Alan [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Robertson, Perry J. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)

2015-09-01

Typically, transistors are modeled by the application of calibrated nominal and range models. These models consists of differing parameter values that describe the location and the upper and lower limits of a distribution of some transistor characteristic such as current capacity. Correspond- ingly, when using this approach, high degrees of accuracy of the transistor models are not expected since the set of models is a surrogate for a statistical description of the devices. The use of these types of models describes expected performances considering the extremes of process or transistor deviations. In contrast, circuits that have very stringent accuracy requirements require modeling techniques with higher accuracy. Since these accurate models have low error in transistor descriptions, these models can be used to describe part to part variations as well as an accurate description of a single circuit instance. Thus, models that meet these stipulations also enable the calculation of quantifi- cation of margins with respect to a functional threshold and uncertainties in these margins. Given this need, new model high accuracy calibration techniques for bipolar junction transis- tors have been developed and are described in this report.

Introduction dosimetric data of cobalt-60 unit in planning new Win-PTL- 3D

International Nuclear Information System (INIS)

Gonzalez Perez, Yelina; Rodriguez Zayas, Michael; Perez Guevara, Adrian; Sanchez Zamora, Luis; Reyes Gonzalez, Tommy; Sola Rodriguez, Yeline; Caballero, Roberto; Cruz Marcane, Viviana

2009-01-01

3D planning is based on the individual and image reconstruction formation of fields, allowing better absorption of dose volume White minimizing damage to surrounding healthy tissue. During the clinical implementation of the Win-PLT software includes validation from the implementation of dosimetric acceptance tests through a series of precise experimental measurements, reflecting different clinical situations (test cases). For the commissioning characterized the photon beam Cobalt Unit 60, taking measurements with a set consisting of a phantom dosimetric automatic ionization chambers and electrometer Tandem. The measured data are used to power the TPS through WINCOM auxiliary program that lets you adjust a number of parameters to model the photon beam. This adjustment is made by comparing the PDD curves and profiles of experimental data with modeled data. The test cases performed are in compliance with the requirements proposed in the geometric of the AAPM TG55. The modeling of beam dosimetry data was successful, since the discrepancies were within the criteria TRS-430. The cases involved events where points near the edge of the field and in the presence of blocking a discrepancy outside the tolerance, suggesting not to use these items for purposes of limitation. Win TPS-PLT is suitable for clinical use with the photon beam Cobalt Unit 60, backed by the reliability that dropped on the results of beam modeling and verification of dosimetric calculations. (Author)

Dosimetric Impact of Primary Planning Parameters in Dynamic Conformal Arc Technique for Lung SBRT

Energy Technology Data Exchange (ETDEWEB)

Park, Ji Yeon; Suh, Tae Suk [Dept. of Biomedical Engineering, The Catholic University of Korea, Seoul (Korea, Republic of); Kim, Si Yong [Dept. of Radiation Oncology, Mayo Clinic, Jacksonvile (United States); Lee, Jeong Woo [Dept. of Radiation Oncology, Konkuk University Medical Center, Seoul (Korea, Republic of); Choi, Kyoung Sik [Dept. of Radiation Oncology, Anyang SAM Hospital, Anyang (Korea, Republic of)

2011-04-15

As one of the stereotactic body radiation therapy (SBRT) techniques, dynamic conformal arc therapy (DCAT) is commonly adopted to efficiently deliver conformal doses. However, as the DCAT uses numerous beams at individual control points, the dosimetric errors generated from each beam can be accumulated and manifested. In SBRT, therefore, due to the high fractional dose within a few fractions to moving target, the determination of the applied plan parameters can be critical and the evaluation of dosimetric impact of planning parameters would play an important role in DCAT planning process. In this study, we systematically evaluated the dosimetric influence caused by the variable grid size and the angular increment in DCAT for lung SBRT. Dose variations with different parameters were estimated for spherical and elongated tumors on an anthropomorphic phantom. The systematic analysis of the generated dose variation would guide to determine appropriate plan parameters and to estimate the dose errors in planning process in a clinical perspective of DCAT. It was found that two plan parameters, grid size and angular increment, in DCAT could cause non-negligible dose uncertainty. Coarse grid size led patients to get unnecessary overdose. Coarse angular increment could make significantly inaccurate prediction of OAR dose, resulting in either over- or under- estimation depending on the location of OAR relative to the isocenter.

Matched-pair analysis and dosimetric variations of two types of software for interstitial permanent brachytherapy for prostate cancer

Energy Technology Data Exchange (ETDEWEB)

Ishiyama, Hiromichi, E-mail: hishiyam@kitasato-u.ac.jp [Department of Radiology, Kitasato University School of Medicine, Sagamihara, Kanagawa (Japan); Nakamura, Ryuji [Department of Radiology, Iwate Medical University, Morioka, Iwate (Japan); Satoh, Takefumi [Department of Urology, Kitasato University School of Medicine, Sagamihara, Kanagawa (Japan); Tanji, Susumu [Department of Urology, Iwate Medical University, Morioka, Iwate (Japan); Teh, Bin S. [Department of Radiation Oncology, The Methodist Hospital, Houston, TX (United States); Uemae, Mineko [Division of Radiation Oncology, Kitasato University Hospital, Sagamihara, Kanagawa (Japan); Baba, Shiro [Department of Urology, Kitasato University School of Medicine, Sagamihara, Kanagawa (Japan); Hayakawa, Kazushige [Department of Radiology, Kitasato University School of Medicine, Sagamihara, Kanagawa (Japan)

2012-04-01

The purpose of this study was to determine whether identical dosimetric results could be achieved using different planning software for permanent interstitial brachytherapy for prostate cancer. Data from 492 patients treated with brachytherapy were used for matched-pair analysis. Interplant and Variseed were used as software for ultrasound-based treatment planning. Institution, neoadjuvant hormonal therapy, prostate volume, and source strength were used for factors to match the 2 groups. The study population comprised of 126 patients with treatment planning using Interplant software and 127 matched patients using Variseed software. Dosimetric results were compared between the 2 groups. The Variseed group showed significantly higher values for dose covering 90% of prostate volume (pD90), prostate volume covered by 150% of prescription dose (pV150), and dose covering 30% of the urethra (uD30) compared with the Interplant group. Our results showed that use of different software could lead to different dosimetric results, which might affect the clinical outcomes.

Investigation of dosimetric characteristics of the high sensitivity LiF:Mg,Cu,P Thermoluminescent Dosemeter and its applications in diagnostic radiology - a review

International Nuclear Information System (INIS)

Fung, K.L.

2004-01-01

This study investigated the dosimetric properties of the high sensitivity TLD (Thermoluminescent Dosemeter) of LiF:Mg,Cu,P and its applications in diagnostic radiology. A reproducible readout and annealing regime for this high sensitivity TLD was developed in the initial part of this study with the newly installed automatic TLD Reader system. Basic dosimetric characteristics of this T.L. dosemeter were then investigated. This paved the foundation for subsequent selected novel application studies in diagnostic radiology. This study exploits the favourable dosimetric properties of these T.L. dosemeters in some selected novel dosimetric applications in diagnostic radiology with an anthropomorphic phantom. The applications studied in radiological procedures included: dose reduction in lumbar spine radiography utilizing the 'anode heel effect'; gonad dose variation with kV p in chest radiography; foetal dose comparison between computed tomography (CT) and computed radiography (CR) in X-ray pelvimetry; lens dose reduction with bismuth eye-shields in CT brain studies; foetal dose assessment of early pregnancy in common high risk radiological examinations. It is anticipated that the unique and favourable dosimetric performance of LiF:Mg,Cu,P T.L. phosphor will be exploited further in measurements of low level dose received by patients and staff in diagnostic radiological procedures such as paediatric X-ray examinations

Investigation of dosimetric characteristics of the high sensitivity LiF:Mg,Cu,P Thermoluminescent Dosemeter and its applications in diagnostic radiology - a review

Energy Technology Data Exchange (ETDEWEB)

Fung, K.L. E-mail: orkarl@polyu.edu.hk

2004-05-01

This study investigated the dosimetric properties of the high sensitivity TLD (Thermoluminescent Dosemeter) of LiF:Mg,Cu,P and its applications in diagnostic radiology. A reproducible readout and annealing regime for this high sensitivity TLD was developed in the initial part of this study with the newly installed automatic TLD Reader system. Basic dosimetric characteristics of this T.L. dosemeter were then investigated. This paved the foundation for subsequent selected novel application studies in diagnostic radiology. This study exploits the favourable dosimetric properties of these T.L. dosemeters in some selected novel dosimetric applications in diagnostic radiology with an anthropomorphic phantom. The applications studied in radiological procedures included: dose reduction in lumbar spine radiography utilizing the 'anode heel effect'; gonad dose variation with kV{sub p} in chest radiography; foetal dose comparison between computed tomography (CT) and computed radiography (CR) in X-ray pelvimetry; lens dose reduction with bismuth eye-shields in CT brain studies; foetal dose assessment of early pregnancy in common high risk radiological examinations. It is anticipated that the unique and favourable dosimetric performance of LiF:Mg,Cu,P T.L. phosphor will be exploited further in measurements of low level dose received by patients and staff in diagnostic radiological procedures such as paediatric X-ray examinations.

Energy absorption buildup factors for thermoluminescent dosimetric materials and their tissue equivalence

DEFF Research Database (Denmark)

Manohara, S.R.; Hanagodimath, S.M.; Gerward, Leif

2010-01-01

Gamma ray energy-absorption buildup factors were computed using the five-parameter geometric progression (G-P) fitting formula for seven thermoluminescent dosimetric (TLD) materials in the energy range 0.015-15 MeV, and for penetration depths up to 40 mfp (mean free path). The generated energy-absorption...

Decree of the 17 July 2013 related to the medical supervision form and to the dosimetric follow-up of workers exposed to ionizing radiations

International Nuclear Information System (INIS)

Combrexelle, J.D.; Ligeard, C.; Gandil, P.

2013-01-01

This legal text addresses the delivery modalities and content of the individual medical supervision form, the implementation modalities and conditions for the reference individual dosimetric follow-up, the implementation modalities and conditions for the operational individual dosimetric follow-up, the access to dosimetry individual results. Appendices address the modalities of the individual dosimetric follow-up, the dosimetry for internal exposure follow-up, the dosimetry for external exposure follow-up, the dosimetry for the follow-up of professional exposure to natural radioactivity, and the technical modalities of information exchange

Comprehensive Australasian multicentre dosimetric intercomparison: issues, logistics and recommendations.

Science.gov (United States)

Ebert, M A; Harrison, K M; Cornes, D; Howlett, S J; Joseph, D J; Kron, T; Hamilton, C S; Denham, J W

2009-02-01

The present paper describes the logistics of the 2004-2008 Australasian Level III Dosimetry Intercomparison. Dosimetric intercomparisons (or 'audits') can be used in radiotherapy to evaluate the accuracy and quality of radiation delivery. An intercomparison was undertaken in New Zealand and Australia to evaluate the feasibility and logistics of ongoing dosimetric intercomparisons that evaluate all steps in the radiotherapy treatment process, known as a 'Level III' intercomparison. The study commenced in 2002 with the establishment of a study team, definition of the study protocol, acquisition of appropriate equipment and recruitment of participating radiotherapy centres. Measurements were undertaken between October 2004 and March 2008, and included collation of data on time, costs and logistics of the study. Forty independent Australian and New Zealand radiotherapy centres agreed to participate. Measurement visits were made to 37 of these centres. Data is presented on the costs of the study and the level of support required. The study involved the participation of 16 staff at the study centre who invested over 4000 hours in the study, and of over 200 professionals at participating centres. Recommendations are provided for future phantom-based intercomparisons. It is hoped that the present paper will be of benefit to any centres or groups contemplating similar activities by identifying the processes involved in establishing the study, the potential hazards and pitfalls, and expected resource requirements.

Dosimetric Consequences of Interobserver Variability in Delineating the Organs at Risk in Gynecologic Interstitial Brachytherapy

Energy Technology Data Exchange (ETDEWEB)

Damato, Antonio L., E-mail: adamato@lroc.harvard.edu [Department of Radiation Oncology, Dana-Farber Cancer Institute/Brigham and Women' s Hospital, Boston, Massachusetts (United States); Townamchai, Kanopkis [Department of Radiation Oncology, Dana-Farber Cancer Institute/Brigham and Women' s Hospital, Boston, Massachusetts (United States); Albert, Michele [Department of Radiation Oncology, Saint Anne' s Hospital Regional Cancer Center, Fall River, Massachusetts (United States); Bair, Ryan J. [Department of Radiology, Brigham and Women' s Hospital, Boston, Massachusetts (United States); Cormack, Robert A. [Department of Radiation Oncology, Dana-Farber Cancer Institute/Brigham and Women' s Hospital, Boston, Massachusetts (United States); Jang, Joanne [Department of Radiation Oncology, Beth Israel Deaconess Medical Center, Boston, Massachusetts (United States); Kovacs, Arpad [Department of Radiology, Brigham and Women' s Hospital, Boston, Massachusetts (United States); Lee, Larissa J. [Department of Radiation Oncology, Dana-Farber Cancer Institute/Brigham and Women' s Hospital, Boston, Massachusetts (United States); Mak, Kimberley S.; Mirabeau-Beale, Kristina L.; Mouw, Kent W.; Phillips, John G.; Pretz, Jennifer L.; Russo, Andrea L. [Harvard Radiation Oncology Program, Harvard Medical School, Boston, Massachusetts (United States); Lewis, John H.; Viswanathan, Akila N. [Department of Radiation Oncology, Dana-Farber Cancer Institute/Brigham and Women' s Hospital, Boston, Massachusetts (United States)

2014-07-01

Purpose: To investigate the dosimetric variability associated with interobserver organ-at-risk delineation differences on computed tomography in patients undergoing gynecologic interstitial brachytherapy. Methods and Materials: The rectum, bladder, and sigmoid of 14 patients treated with gynecologic interstitial brachytherapy were retrospectively contoured by 13 physicians. Geometric variability was calculated using κ statistics, conformity index (CI{sub gen}), and coefficient of variation (CV) of volumes contoured across physicians. Dosimetric variability of the single-fraction D{sub 0.1cc} and D{sub 2cc} was assessed through CV across physicians, and the standard deviation of the total EQD2 (equivalent dose in 2 Gy per fraction) brachytherapy dose (SD{sup TOT}) was calculated. Results: The population mean ± 1 standard deviation of κ, CI{sub gen}, and volume CV were, respectively: 0.77 ± 0.06, 0.70 ± 0.08, and 20% ± 6% for bladder; 0.74 ± 06, 0.67 ± 0.08, and 20% ± 5% for rectum; and 0.33 ± 0.20, 0.26 ± 0.17, and 82% ± 42% for sigmoid. Dosimetric variability was as follows: for bladder, CV = 31% ± 19% (SD{sup TOT} = 72 ± 64 Gy) for D{sub 0.1cc} and CV = 16% ± 10% (SD{sup TOT} = 9 ± 6 Gy) for D{sub 2cc}; for rectum, CV = 11% ± 5% (SD{sup TOT} = 16 ± 17 Gy) for D{sub 0.1cc} and CV = 7% ± 2% (SD{sup TOT} = 4 ± 3 Gy) for D{sub 2cc}; for sigmoid, CV = 39% ± 28% (SD{sup TOT} = 12 ± 18 Gy) for D{sub 0.1cc} and CV = 34% ± 19% (SD{sup TOT} = 4 ± 4 Gy) for D{sub 2cc.} Conclusions: Delineation of bladder and rectum by 13 physicians demonstrated substantial geometric agreement and resulted in good dosimetric agreement for all dose-volume histogram parameters except bladder D{sub 0.1cc.} Small delineation differences in high-dose regions by the posterior bladder wall may explain these results. The delineation of sigmoid showed fair geometric agreement. The higher dosimetric variability for sigmoid compared with rectum and bladder did not correlate with

Validation of a densimeter calibration procedure for a secondary calibration laboratory

International Nuclear Information System (INIS)

Alpizar Herrera, Juan Carlos

2014-01-01

A survey was conducted to quantify the need for calibration of a density measurement instrument at the research units at the Sede Rodrigo Facio of the Universidad de Costa Rica. A calibration procedure was documented for the instrument that presented the highest demand in the survey by the calibration service. A study of INTE-ISO/IEC 17025: 2005 and specifically in section 5.4 of this standard was done, to document the procedure for calibrating densimeters. Densimeter calibration procedures and standards were sought from different national and international sources. The method of hydrostatic weighing or Cuckow method was the basis of the defined procedure. Documenting the calibration procedure and creating other documents was performed for data acquisition log, intermediate calculation log and calibration certificate copy. A veracity test was performed using as reference laboratory a laboratory of calibration secondary national as part of the validation process of the documented procedure. The results of the E_n statistic of 0.41; 0.34 and 0.46 for the calibration points 90%, 50% and 10% were obtained for the densimeter scale respectively. A reproducibility analysis of the method was performed with satisfactory results. Different suppliers were contacted to estimate the economic costs of the equipment and materials, needed to develop the documented method of densimeter calibration. The acquisition of an analytical balance was recommended, instead of a precision scale, in order to improve the results obtained with the documented method [es

Calibration of differential scanning calorimeters: A comparison between indium and diphenylacetic acid

International Nuclear Information System (INIS)

Charsley, E.L.; Laye, P.G.; Markham, H.M.; Le Goff, T.

2010-01-01

The close proximity in melting temperature of the LGC Limited DSC standards indium and diphenylacetic acid, has enabled a direct assessment to be made of any differences resulting from the use of a metal or an organic compound in the calibration of DSC equipment. Following calibration with indium, the equilibrium fusion temperatures for diphenylacetic acid, were determined by both the stepwise heating and extrapolation to zero heating rate methods. The results were in excellent agreement with the certificate values and established that indium may be used as a calibrant when making accurate DSC measurements on organic materials in the same temperature range and that it has the advantage that it is non-volatile and can be used a number of times without significant change. Similar agreement was obtained in the measurement of the enthalpy of fusion, although the larger heat capacity change on fusion of diphenylacetic acid resulted in a greater uncertainty than with indium.

Ensuring long-term stability of infrared camera absolute calibration.

Science.gov (United States)

Kattnig, Alain; Thetas, Sophie; Primot, Jérôme

2015-07-13

Absolute calibration of cryogenic 3-5 µm and 8-10 µm infrared cameras is notoriously instable and thus has to be repeated before actual measurements. Moreover, the signal to noise ratio of the imagery is lowered, decreasing its quality. These performances degradations strongly lessen the suitability of Infrared Imaging. These defaults are often blamed on detectors reaching a different "response state" after each return to cryogenic conditions, while accounting for the detrimental effects of imperfect stray light management. We show here that detectors are not to be blamed and that the culprit can also dwell in proximity electronics. We identify an unexpected source of instability in the initial voltage of the integrating capacity of detectors. Then we show that this parameter can be easily measured and taken into account. This way we demonstrate that a one month old calibration of a 3-5 µm camera has retained its validity.

Dosimetry of ionizing radiation

International Nuclear Information System (INIS)

Musilek, L.; Seda, J.; Trousil, J.

1992-01-01

The publication deals with a major field of ionizing radiation dosimetry, viz., integrating dosimetric methods, which are the basic means of operative dose determination. It is divided into the following sections: physical and chemical effects of ionizing radiation; integrating dosimetric methods for low radiation doses (film dosimetry, nuclear emulsions, thermoluminescence, radiophotoluminescence, solid-state track detectors, integrating ionization dosemeters); dosimetry of high ionizing radiation doses (chemical dosimetric methods, dosemeters based on the coloring effect, activation detectors); additional methods applicable to integrating dosimetry (exoelectron emission, electron spin resonance, lyoluminescence, etc.); and calibration techniques for dosimetric instrumentation. (Z.S.). 422 refs

Dosimetric validation of planning system Eclipse 10 in partial breast irradiation treatments with IMRT

International Nuclear Information System (INIS)

Velazquez T, J. J.; Gutierrez M, J. G.; Ortiz A, C. S.; Chagoya G, A.; Gutierrez C, J. G.

2015-10-01

Partial breast irradiation is a new type of external radiation therapy to treat breast cancer in early clinical stages. Consist of administering to the channel surgical high doses of radiation in few treatment sessions. In this paper the dose calculations of the planning system Eclipse version 10 for a treatment of partial breast irradiation with X-rays beams (6 MV) intensity modulated were compared against the measurements made with OSL dosimeters and radio-chromic dye film. An anthropomorphic mannequin was used in which OSL dosimeters were collocated near the surface, an inside the radio-chromic dye film one plate; with this latest one dimensional dose distribution was measured. Previously dosimeters were calibrated irradiating them with a beam of X-rays 6 MV under the conditions specified in the IAEA-398 protocol. The OSL dosimeters were read in the Micro star Landauer equipment, the radio-chromic dye films were read with a scanner Epson 10000-Xl and analyzed with FilmCal and PTW Verisoft programs. The differences between measured and calculated dose were as follows: 3.6±1% for the OSL dosimeter and 96.3±1% of the analyzed points approved the gamma index criterion (3%, 3m m) when comparing the matrices of calculated dose and measured with the radio-chromic dye film. These results confirm the good dosimetric performance of planning system used under specific conditions used in the partial breast irradiation technique. (Author)

Dosimetric effects of an air cavity for the SAVI partial breast irradiation applicator

Energy Technology Data Exchange (ETDEWEB)

Richardson, Susan L.; Pino, Ramiro [Department of Radiation Oncology, Washington University School of Medicine, St. Louis, Missouri 63110 (United States); Department of Radiation Oncology, Methodist Hospital, Houston, Texas 77030 and Texas Cancer Clinic, San Antonio, Texas 78240 (United States)

2010-08-15

Purpose: To investigate the dosimetric effect of the air inside the SAVI partial breast irradiation device. Methods: The authors have investigated how the air inside the SAVI partial breast irradiation device changes the delivered dose from the homogeneously calculated dose. Measurements were made with the device filled with air and water to allow comparison to a homogenous dose calculation done by the treatment planning system. Measurements were made with an ion chamber, TLDs, and film. Monte Carlo (MC) simulations of the experiment were done using the EGSnrc suite. The MC model was validated by comparing the water-filled calculations to those from a commercial treatment planning system. Results: The magnitude of the dosimetric effect depends on the size of the cavity, the arrangement of sources, and the relative dwell times. For a simple case using only the central catheter of the largest device, MC results indicate that the dose at the prescription point 1 cm away from the air-water boundary is about 9% higher than the homogeneous calculation. Independent measurements in a water phantom with a similar air cavity gave comparable results. MC simulation of a realistic multidwell position plan showed discrepancies of about 5% on average at the prescription point for the largest device. Conclusions: The dosimetric effect of the air cavity is in the range of 3%-9%. Unless a heterogeneous dose calculation algorithm is used, users should be aware of the possibility of small treatment planning dose errors for this device and make modifications to the treatment delivery, if necessary.

EPR dosimetric properties of nano-barium sulfate

International Nuclear Information System (INIS)

Aboelezz, E.; Hassan, G.M.; Sharaf, M.A.; El-Khodary, A.

2015-01-01

Nano/micro BaSO 4 were prepared through the co-precipitation method to measure ionizing radiation doses using electron paramagnetic resonance (EPR). The nano-BaSO 4 sample was characterized using X-ray diffraction (XRD), and transmission electron microscopy (TEM) techniques. The dose response and fading properties of nano- and micro-phase BaSO 4 were compared in EPR spectra. The prepared nano- and micro-BaSO 4 samples have the same hole and electron centers, which may be attributed to SO 4 − and SO 3 − , respectively. The dosimetric signals for prepared nano- and micro-BaSO 4 have spectroscopic splitting factor (g) with values 2.0025±0.0006 and 2.0027±0.0006, respectively. The nanocrystalline sample has a linear γ-ray dose response over the range 0.4 Gy–1 kGy. The performance parameters which including detection limit and critical level calculated from weighted and unweighted least-squares fitting. The sensitivity of nano-BaSO 4 to γ-ray is one and a half times more than alanine. The lifetime and activation energy for nano-BaSO 4 were estimated by conducting a thermal stability study, and were 5.7±1.1×10 4 years and 0.73±0.14 eV, respectively. The combined and expanded uncertainties accompanying measurements were ±3.89% and ±7.78%, respectively. - Highlights: • Preparation of nano-BaSO 4 using the co-precipitation method. • Study of the dosimetric properties of nano-barium sulfate using the EPR technique. • Comparison between a new EPR dosimeter using nano-materials and standard alanine. • Calculation of the uncertainty budget for nano-BaSO 4

Reliability-Based Calibration of Load Duration Factors for Timber Structures

DEFF Research Database (Denmark)

Sørensen, John Dalsgaard; Svensson, Staffan; Stang, Birgitte Friis Dela

2005-01-01

John Dalsgaard Sørensen, Staffan Svensson, Birgitte Dela Stang : Reliability-Based Calibration of Load Duration Factors for Timber Structures     Abstract :   The load bearing capacity of timber structures decrease with time depending on the type of load and timber. Based on representative limit...... states and stochastic models for timber structures, load duration factors are calibrated using probabilistic methods. Load duration e.ects are estimated on basis of simulation of realizations of wind, snow and imposed loads in accordance with the load models in the Danish structural codes. Three damage...... accumulation models are considered, namely Gerhards model, Barrett and Foschi _ s model and Foschi and Yao _ s model. The parameters in these models are .tted by the Maximum Likelihood Method using data relevant for Danish structural timber and the statistical uncertainty is quanti .ed. The reliability...

ORNL calibrations facility

International Nuclear Information System (INIS)

Berger, C.D.; Gupton, E.D.; Lane, B.H.; Miller, J.H.; Nichols, S.W.

1982-08-01

The ORNL Calibrations Facility is operated by the Instrumentation Group of the Industrial Safety and Applied Health Physics Division. Its primary purpose is to maintain radiation calibration standards for calibration of ORNL health physics instruments and personnel dosimeters. This report includes a discussion of the radioactive sources and ancillary equipment in use and a step-by-step procedure for calibration of those survey instruments and personnel dosimeters in routine use at ORNL

SCIAMACHY Level 1 data: calibration concept and in-flight calibration

Science.gov (United States)

Lichtenberg, G.; Kleipool, Q.; Krijger, J. M.; van Soest, G.; van Hees, R.; Tilstra, L. G.; Acarreta, J. R.; Aben, I.; Ahlers, B.; Bovensmann, H.; Chance, K.; Gloudemans, A. M. S.; Hoogeveen, R. W. M.; Jongma, R. T. N.; Noël, S.; Piters, A.; Schrijver, H.; Schrijvers, C.; Sioris, C. E.; Skupin, J.; Slijkhuis, S.; Stammes, P.; Wuttke, M.

2006-11-01

The calibration of SCIAMACHY was thoroughly checked since the instrument was launched on-board ENVISAT in February 2002. While SCIAMACHY's functional performance is excellent since launch, a number of technical difficulties have appeared, that required adjustments to the calibration. The problems can be separated into three types: (1) Those caused by the instrument and/or platform environment. Among these are the high water content in the satellite structure and/or MLI layer. This results in the deposition of ice on the detectors in channels 7 and 8 which seriously affects the retrievals in the IR, mostly because of the continuous change of the slit function caused by scattering of the light through the ice layer. Additionally a light leak in channel 7 severely hampers any retrieval from this channel. (2) Problems due to errors in the on-ground calibration and/or data processing affecting for example the radiometric calibration. A new approach based on a mixture of on-ground and in-flight data is shortly described here. (3) Problems caused by principal limitations of the calibration concept, e.g. the possible appearance of spectral structures after the polarisation correction due to unavoidable errors in the determination of atmospheric polarisation. In this paper we give a complete overview of the calibration and problems that still have to be solved. We will also give an indication of the effect of calibration problems on retrievals where possible. Since the operational processing chain is currently being updated and no newly processed data are available at this point in time, for some calibration issues only a rough estimate of the effect on Level 2 products can be given. However, it is the intention of this paper to serve as a future reference for detailed studies into specific calibration issues.

Technique for production of calibrated metal hydride films

International Nuclear Information System (INIS)

Langley, R.A.; Browning, J.F.; Balsley, S.D.; Banks, J.C.; Doyle, B.L.; Wampler, W.R.; Beavis, L.C.

1999-01-01

A technique has been developed for producing calibrated metal hydride films for use in the measurement of high-energy (5--15 MeV) particle reaction cross sections for hydrogen and helium isotopes on hydrogen isotopes. Absolute concentrations of various hydrogen isotopes in the film is expected to be determined to better than ±2% leading to the capacity of accurately measuring various reaction cross sections. Hydrogen isotope concentrations from near 100% to 5% can be made accurately and reproducibly. This is accomplished with the use of high accuracy pressure measurements coupled with high accuracy mass spectrometric measurements of each constituent partial pressure of the gas mixture during loading of the metal occluder films. Various techniques are used to verify the amount of metal present as well as the amount of hydrogen isotopes; high energy ion scattering analysis, PV measurements before, during and after loading, and thermal desorption/mass spectrometry measurements. The most appropriate metal to use for the occluder film appears to be titanium but other occluder metals are also being considered. Calibrated gas ratio samples, previously prepared, are used for the loading gas. Deviations from this calibrated gas ratio are measured using mass spectrometry during and after the loading process thereby determining the loading of the various hydrogen isotopes. These techniques are discussed and pertinent issues presented

Dosimetric aspects of the treatment of metastatic bone pain with radiopharmaceuticals

International Nuclear Information System (INIS)

Garcia, T.; Marti, J. F.; Olivas, C.; Vercher, J. L.; Repetto, R.; Bello, P.

2014-01-01

Within the context of treatment of metastatic bone pain with bone seeking radiopharmaceuticals, this paper expounds the results of an analysis of available molecules (both approved for clinical use or still under study) intended to obtain a detailed comparison of their dosimetric characteristics. These can be used to supplement the list of already know differences between them, such as efficacy, appearance and length of the palliative effect, eventual tumoricidal effect, myelotoxicity, sale price and availability. Seven radiopharmaceuticals have been analysed, five of them are based on beta emission radionuclides: 3 2P, 1 53Sm, 1 86Re and 1 88Re and the other two ones are based on high Linear energy Transference emission radionuclides: 1 17mSn and 2 23Ra a series of estimates of the main dosimetric parameters for each radiopharmaceutical analysed have been obtained. The values obtained might be worth being incorporated to the risk/benefit analysis that precedes every choice of the specific radiopharmaceutical to be used with an individual patient. In this way, we hope these results will be of some help for those Nuclear Medicine specialists interested in the treatment of oncological bone pathologies. (Author)

On the use of advanced numerical models for the evaluation of dosimetric parameters and the verification of exposure limits at workplaces.

Science.gov (United States)

Catarinucci, L; Tarricone, L

2009-12-01

With the next transposition of the 2004/40/EC Directive, employers will become responsible for the electromagnetic field level at the workplace. To make this task easier, the scientific community is compiling practical guidelines to be followed. This work aims at enriching such guidelines, especially for the dosimetric issues. More specifically, some critical aspects related to the application of numerical dosimetric techniques for the verification of the safety limit compliance have been highlighted. In particular, three different aspects have been considered: the dosimetric parameter dependence on the shape and the inner characterisation of the exposed subject as well as on the numerical algorithm used, and the correlation between reference limits and basic restriction. Results and discussions demonstrate how, even by using sophisticated numerical techniques, in some cases a complex interpretation of the result is mandatory.

Comparison and uncertainty evaluation of different calibration protocols and ionization chambers for low-energy surface brachytherapy dosimetry

Energy Technology Data Exchange (ETDEWEB)

Candela-Juan, C., E-mail: ccanjuan@gmail.com [Radiation Oncology Department, La Fe University and Polytechnic Hospital, Valencia 46026 (Spain); Vijande, J. [Department of Atomic, Molecular, and Nuclear Physics, University of Valencia, Burjassot 46100, Spain and Instituto de Física Corpuscular (UV-CSIC), Paterna 46980 (Spain); García-Martínez, T. [Radiation Oncology Department, Hospital La Ribera, Alzira 46600 (Spain); Niatsetski, Y.; Nauta, G.; Schuurman, J. [Elekta Brachytherapy, Veenendaal 3905 TH (Netherlands); Ouhib, Z. [Radiation Oncology Department, Lynn Regional Cancer Center, Boca Raton Community Hospital, Boca Raton, Florida 33486 (United States); Ballester, F. [Department of Atomic, Molecular, and Nuclear Physics, University of Valencia, Burjassot 46100 (Spain); Perez-Calatayud, J. [Radiation Oncology Department, La Fe University and Polytechnic Hospital, Valencia 46026, Spain and Department of Radiotherapy, Clínica Benidorm, Benidorm 03501 (Spain)

2015-08-15

, differ by less than 1.1% for any applicator size when compared to the output factors that were measured with the A20 chamber. Conclusions: Measurements using both dosimetric protocols are consistent, once the overall uncertainties are considered. There is also consistency between measurements performed with both chambers calibrated in air. Both the T34013 and A20 chambers have negligible stem effect. Any x-ray surface brachytherapy system, including Esteya, can be characterized using either one of these calibration protocols and ionization chambers. Having less correction factors, lower uncertainty, and based on measurements, performed in closer to clinical conditions, the TRS-398 protocol seems to be the preferred option.

Dosimetric Implications of Residual Tracking Errors During Robotic SBRT of Liver Metastases

Energy Technology Data Exchange (ETDEWEB)

Chan, Mark [Department for Radiation Oncology, University Medical Center Schleswig-Holstein, Kiel (Germany); Tuen Mun Hospital, Hong Kong (China); Grehn, Melanie [Department for Radiation Oncology, University Medical Center Schleswig-Holstein, Lübeck (Germany); Institute for Robotics and Cognitive Systems, University of Lübeck, Lübeck (Germany); Cremers, Florian [Department for Radiation Oncology, University Medical Center Schleswig-Holstein, Lübeck (Germany); Siebert, Frank-Andre [Department for Radiation Oncology, University Medical Center Schleswig-Holstein, Kiel (Germany); Wurster, Stefan [Saphir Radiosurgery Center Northern Germany, Güstrow (Germany); Department for Radiation Oncology, University Medicine Greifswald, Greifswald (Germany); Huttenlocher, Stefan [Saphir Radiosurgery Center Northern Germany, Güstrow (Germany); Dunst, Jürgen [Department for Radiation Oncology, University Medical Center Schleswig-Holstein, Kiel (Germany); Department for Radiation Oncology, University Clinic Copenhagen, Copenhagen (Denmark); Hildebrandt, Guido [Department for Radiation Oncology, University Medicine Rostock, Rostock (Germany); Schweikard, Achim [Institute for Robotics and Cognitive Systems, University of Lübeck, Lübeck (Germany); Rades, Dirk [Department for Radiation Oncology, University Medical Center Schleswig-Holstein, Lübeck (Germany); Ernst, Floris [Institute for Robotics and Cognitive Systems, University of Lübeck, Lübeck (Germany); and others

2017-03-15

Purpose: Although the metric precision of robotic stereotactic body radiation therapy in the presence of breathing motion is widely known, we investigated the dosimetric implications of breathing phase–related residual tracking errors. Methods and Materials: In 24 patients (28 liver metastases) treated with the CyberKnife, we recorded the residual correlation, prediction, and rotational tracking errors from 90 fractions and binned them into 10 breathing phases. The average breathing phase errors were used to shift and rotate the clinical tumor volume (CTV) and planning target volume (PTV) for each phase to calculate a pseudo 4-dimensional error dose distribution for comparison with the original planned dose distribution. Results: The median systematic directional correlation, prediction, and absolute aggregate rotation errors were 0.3 mm (range, 0.1-1.3 mm), 0.01 mm (range, 0.00-0.05 mm), and 1.5° (range, 0.4°-2.7°), respectively. Dosimetrically, 44%, 81%, and 92% of all voxels differed by less than 1%, 3%, and 5% of the planned local dose, respectively. The median coverage reduction for the PTV was 1.1% (range in coverage difference, −7.8% to +0.8%), significantly depending on correlation (P=.026) and rotational (P=.005) error. With a 3-mm PTV margin, the median coverage change for the CTV was 0.0% (range, −1.0% to +5.4%), not significantly depending on any investigated parameter. In 42% of patients, the 3-mm margin did not fully compensate for the residual tracking errors, resulting in a CTV coverage reduction of 0.1% to 1.0%. Conclusions: For liver tumors treated with robotic stereotactic body radiation therapy, a safety margin of 3 mm is not always sufficient to cover all residual tracking errors. Dosimetrically, this translates into only small CTV coverage reductions.

Dosimetric Implications of Residual Tracking Errors During Robotic SBRT of Liver Metastases

International Nuclear Information System (INIS)

Chan, Mark; Grehn, Melanie; Cremers, Florian; Siebert, Frank-Andre; Wurster, Stefan; Huttenlocher, Stefan; Dunst, Jürgen; Hildebrandt, Guido; Schweikard, Achim; Rades, Dirk; Ernst, Floris

2017-01-01

Purpose: Although the metric precision of robotic stereotactic body radiation therapy in the presence of breathing motion is widely known, we investigated the dosimetric implications of breathing phase–related residual tracking errors. Methods and Materials: In 24 patients (28 liver metastases) treated with the CyberKnife, we recorded the residual correlation, prediction, and rotational tracking errors from 90 fractions and binned them into 10 breathing phases. The average breathing phase errors were used to shift and rotate the clinical tumor volume (CTV) and planning target volume (PTV) for each phase to calculate a pseudo 4-dimensional error dose distribution for comparison with the original planned dose distribution. Results: The median systematic directional correlation, prediction, and absolute aggregate rotation errors were 0.3 mm (range, 0.1-1.3 mm), 0.01 mm (range, 0.00-0.05 mm), and 1.5° (range, 0.4°-2.7°), respectively. Dosimetrically, 44%, 81%, and 92% of all voxels differed by less than 1%, 3%, and 5% of the planned local dose, respectively. The median coverage reduction for the PTV was 1.1% (range in coverage difference, −7.8% to +0.8%), significantly depending on correlation (P=.026) and rotational (P=.005) error. With a 3-mm PTV margin, the median coverage change for the CTV was 0.0% (range, −1.0% to +5.4%), not significantly depending on any investigated parameter. In 42% of patients, the 3-mm margin did not fully compensate for the residual tracking errors, resulting in a CTV coverage reduction of 0.1% to 1.0%. Conclusions: For liver tumors treated with robotic stereotactic body radiation therapy, a safety margin of 3 mm is not always sufficient to cover all residual tracking errors. Dosimetrically, this translates into only small CTV coverage reductions.

ESR Spectra of Some Silicate Minerals: A Search For New Dosimetric Materials

International Nuclear Information System (INIS)

Abdel-Monem, A.A.; Abdel-Razek, Y.A.; Rasheed, G. M.; Hassan, G.M.; Eissa, H.M.; Morsy, M.

2008-01-01

Two silicate minerals talc (Mg 3 Si 4 O 1 0 (OH) 2 ) and zircon (ZrSiO 4 ) having different crystal lattice structures were subjected to ESR dosimetric studies. Zircon shows anisotropic ESR signals at g xx =2.0168, g yy =2.0076 and g zz =2.0033, which have been identified as a hole center associated with Y 3+ substituted at Zr 4+ sites. Other characteristic signals have been observed and identified. The ESR signal at g=2.0033 showed positive response to γ-irradiation at 110 Gy and is suitable to be used for dosimetry and dating of natural zircons. Talc a magnesium sheeted silicate exhibits ESR derivative spectrum characterized the presence of Fe 3+ at g=4.28 and the HF-sixtet Mn 2+ signals due to possible substitution of Fe 3+ and Mn 2+ in the Mg 2+ octahedral sites, respectively. The enhancement of the Mn 2+ sixtet by γ-irradiation increases the area occupied by the signals which makes it difficult to use for dosimetric applications

Development of a dosimetric system for dental X-ray equipment quality control

International Nuclear Information System (INIS)

Melo, Francisco Almeida de

2002-08-01

An electronic instrument with digital readout was designed and constructed to provide fast, simple and non-invasive measurements of X-ray dental equipment parameters. This instrument is capable of evaluating the entrance dose, exposure time, tube voltage (kVp) and beam filtration. It consists of a set of five photodiodes connected each one in the photocurrent mode to the input of a designed integrating electrometer. Three of the detectors are fixed under aluminium filters with different thicknesses, one is fixed under a 0.3 mm copper filter and the other has no filtration. The readings of the three detectors under aluminium filters and of the bare detector permit the determination of the half-value layer, which is used to calculate the beam filtration. The ratio between the readings of the detector below the copper filter and the one without filtration is used to determine the tube voltage. The signal produced by the detector without filter is used to evaluate the patient entrance dose, and to active an electronic timer for measuring the real exposure time. The tests and calibration of the instrument in different voltages in the 59 - 70kVp range, showed that its response is both stable and reproducible to within 1%. The instrument response was compared to the one from a commercial non-invasive X-ray test equipment (Gammex RMI Multifunction kVp meter). The results showed that the response of the developed instrument is in good agreement with the RMI meter which is the standard equipment for such measurements. These results indicate that the dosimetric system is suitable for use in Dental Quality Assurance Programs. (author)

Production of LiF films for dosimetric thermoluminescence application

International Nuclear Information System (INIS)

Mauricio, Claudia Lucia de Pinho

2000-12-01

This work studies the LiF monolayer and multilayer polycrystalline film's dosimetric properties. The films were produced by electron beam evaporation technique in aluminium and stainless steel substrates maintained at several temperatures. As dosimetric variable, the intensity of the thermoluminescent (TL) glow curve of the films was used. effects of the substrate type and temperature; of the addition of layers of Mg F 2 NaF and Cu F 2 to the LiF films; and of thermal treatments in the TL response of the produced films were studied. The microstructural characterization of the films was accomplished through measures of scanning electronic microscopy and grazing incidence X-rays diffraction analysis. The dosimetric characterization was made of gamma radiation exposure in a 60 Co source, with kerma from 0,1 to 500 Gy. Studies of reproducibility, homogeneity, stability and other environmental effects were also made. LiF and Cu F 2 : LiF; Mg F 2 films were the only ones that presented mechanical stability and reproducibility of the TL emission. There is a strong indication of some correlation between the residual tension fields inside the films and the intensity of its TL emission peaks. LiF monolayer films present supralinear behaviour from 0,2 to 100 Gy. These films present a main TL glow peak around 150 deg C, whose half-time is about 30 days. Its volumetric sensitivity can reach about 60 times that of LiF powder and about 0,25 that of TLD100 (LiF:Mg, Ti commercial dosimeter from Harshaw Chemical Co.) The homogeneity and reproducibility inside a same film batch is better than 12% for 95% confidence level. Cu F 2 : LiF: Mg F 2 films present linear behaviour from 3 to 500 Gy and its main TL glow peak around 200 deg C did not present any fading for a a period of 30 days, in laboratory conditions. This glow peak is characteristic of the Mg doping of LiF, which confirms the diffusion of Mg ions from the Mg F 2 layer to the LiF layer. The TL volumetric sensitivity of these

Influence of Pro-Qura-generated Plans on Postimplant Dosimetric Quality: A Review of a Multi-Institutional Database

International Nuclear Information System (INIS)

Allen, Zachariah; Merrick, Gregory S.; Grimm, Peter; Blasko, John; Sylvester, John; Butler, Wayne; Chaudry, Usman-Ul-Haq; Sitter, Michael

2008-01-01

The influence of Pro-Qura-generated plans vs. community-generated plans on postprostate brachytherapy dosimetric quality was compared. In the Pro-Qura database, 2933 postplans were evaluated from 57 institutions. A total of 1803 plans were generated by Pro-Qura and 1130 by community institutions. Iodine-125 ( 125 I) plans outnumbered Palladium 103 ( 103 Pd) plans by a ratio of 3:1. Postimplant dosimetry was performed in a standardized fashion by overlapping the preimplant ultrasound and the postimplant computed tomography (CT). In this analysis, adequacy was defined as a V 100 > 80% and a D 90 of 90% to 140% for both isotopes along with a V 150 125 I and 103 Pd. The mean postimplant V 100 and D 90 were 88.6% and 101.6% vs. 89.3% and 102.3% for Pro-Qura and community plans, respectively. When analyzed in terms of the first 8 sequence groups (10 patients/sequence group) for each institution, Pro-Qura planning resulted in less postimplant variability for V 100 (86.2-89.5%) and for D 90 (97.4-103.2%) while community-generated plans had greater V 100 (85.3-91.2%) and D 90 (95.9-105.2%) ranges. In terms of sequence groups, postimplant dosimetry was deemed 'too cool' in 11% to 30% of cases and 'too hot' in 12% to 27%. On average, no clinically significant postimplant dosimetric differences were discerned between Pro-Qura and community-based planning. However, substantially greater variability was identified in the community-based plan cohort. It is possible that the Pro-Qura plan and/or the routine postimplant dosimetric evaluation may have influenced dosimetric outcomes at community-based centers

Spitzer/JWST Cross Calibration: IRAC Observations of Potential Calibrators for JWST

Science.gov (United States)

Carey, Sean J.; Gordon, Karl D.; Lowrance, Patrick; Ingalls, James G.; Glaccum, William J.; Grillmair, Carl J.; E Krick, Jessica; Laine, Seppo J.; Fazio, Giovanni G.; Hora, Joseph L.; Bohlin, Ralph

2017-06-01

We present observations at 3.6 and 4.5 microns using IRAC on the Spitzer Space Telescope of a set of main sequence A stars and white dwarfs that are potential calibrators across the JWST instrument suite. The stars range from brightnesses of 4.4 to 15 mag in K band. The calibration observations use a similar redundancy to the observing strategy for the IRAC primary calibrators (Reach et al. 2005) and the photometry is obtained using identical methods and instrumental photometric corrections as those applied to the IRAC primary calibrators (Carey et al. 2009). The resulting photometry is then compared to the predictions based on spectra from the CALSPEC Calibration Database (http://www.stsci.edu/hst/observatory/crds/calspec.html) and the IRAC bandpasses. These observations are part of an ongoing collaboration between IPAC and STScI investigating absolute calibration in the infrared.

Contribution of the SLDC to the metrology of the ionizing radiations dosimetry in Mexico

International Nuclear Information System (INIS)

Alvarez R, J. T.

2010-01-01

The Secondary Laboratory of Dosimetric Calibration (SLDC), assigned to the Metrology Department of Ionizing Radiations of the ININ had its beginnings in the eighties, with the purpose of having a specialized area to develop and to establish measure patterns of the dosimetric magnitudes and units. In the year 2000 the National Center of Metrology of the country, delegated its functions to the SLDC, as regards to develop and to maintain the national patterns in the area of ionizing radiations. In this chapter a brief review is presented on the magnitudes and units used in dosimetry and and absorbed dose, as well as some of the activities of dosimetric calibration that have been made by part of the SLDC to the radiotherapy centers in Mexico and some applications to the nuclear power plant of Laguna Verde. (Author)

Dosimetric Evaluation of Intensity Modulated Radiotherapy and 4-Field 3-D Conformal Radiotherapy in Prostate Cancer Treatment

Directory of Open Access Journals (Sweden)

Bora Uysal

2013-03-01

Full Text Available Objective: The purpose of this dosimetric study is the targeted dose homogeneity and critical organ dose comparison of 7-field Intensity Modulated Radiotherapy (IMRT and 3-D 4-field conformal radiotherapy. Study Design: Cross sectional study. Material and Methods: Twenty patients with low and moderate risk prostate cancer treated at Gülhane Military Medical School Radiation Oncology Department between January 2009 and December 2009 are included in this study. Two seperate dosimetric plans both for 7-field IMRT and 3D-CRT have been generated for each patient to comparatively evaluate the dosimetric status of both techniques and all the patients received 7-field IMRT. Results: Dose-comparative evaluation of two techniques revealed the superiority of IMRT technique with statistically significantly lower femoral head doses along with reduced critical organ dose-volume parameters of bladder V60 (the volume receiving 60 Gy and rectal V40 (the volume receiving 40 Gy and V60. Conclusion: It can be concluded that IMRT is an effective definitive management tool for prostate cancer with improved critical organ sparing and excellent dose homogenization in target organs of prostate and seminal vesicles.

The stars: an absolute radiometric reference for the on-orbit calibration of PLEIADES-HR satellites

Science.gov (United States)

Meygret, Aimé; Blanchet, Gwendoline; Mounier, Flore; Buil, Christian

2017-09-01

The accurate on-orbit radiometric calibration of optical sensors has become a challenge for space agencies who gather their effort through international working groups such as CEOS/WGCV or GSICS with the objective to insure the consistency of space measurements and to reach an absolute accuracy compatible with more and more demanding scientific needs. Different targets are traditionally used for calibration depending on the sensor or spacecraft specificities: from on-board calibration systems to ground targets, they all take advantage of our capacity to characterize and model them. But achieving the in-flight stability of a diffuser panel is always a challenge while the calibration over ground targets is often limited by their BDRF characterization and the atmosphere variability. Thanks to their agility, some satellites have the capability to view extra-terrestrial targets such as the moon or stars. The moon is widely used for calibration and its albedo is known through ROLO (RObotic Lunar Observatory) USGS model but with a poor absolute accuracy limiting its use to sensor drift monitoring or cross-calibration. Although the spectral irradiance of some stars is known with a very high accuracy, it was not really shown that they could provide an absolute reference for remote sensors calibration. This paper shows that high resolution optical sensors can be calibrated with a high absolute accuracy using stars. The agile-body PLEIADES 1A satellite is used for this demonstration. The star based calibration principle is described and the results are provided for different stars, each one being acquired several times. These results are compared to the official calibration provided by ground targets and the main error contributors are discussed.

Simultaneous calibration phantom commission and geometry calibration in cone beam CT

Science.gov (United States)

Xu, Yuan; Yang, Shuai; Ma, Jianhui; Li, Bin; Wu, Shuyu; Qi, Hongliang; Zhou, Linghong

2017-09-01

Geometry calibration is a vital step for describing the geometry of a cone beam computed tomography (CBCT) system and is a prerequisite for CBCT reconstruction. In current methods, calibration phantom commission and geometry calibration are divided into two independent tasks. Small errors in ball-bearing (BB) positioning in the phantom-making step will severely degrade the quality of phantom calibration. To solve this problem, we propose an integrated method to simultaneously realize geometry phantom commission and geometry calibration. Instead of assuming the accuracy of the geometry phantom, the integrated method considers BB centers in the phantom as an optimized parameter in the workflow. Specifically, an evaluation phantom and the corresponding evaluation contrast index are used to evaluate geometry artifacts for optimizing the BB coordinates in the geometry phantom. After utilizing particle swarm optimization, the CBCT geometry and BB coordinates in the geometry phantom are calibrated accurately and are then directly used for the next geometry calibration task in other CBCT systems. To evaluate the proposed method, both qualitative and quantitative studies were performed on simulated and realistic CBCT data. The spatial resolution of reconstructed images using dental CBCT can reach up to 15 line pair cm-1. The proposed method is also superior to the Wiesent method in experiments. This paper shows that the proposed method is attractive for simultaneous and accurate geometry phantom commission and geometry calibration.

SU-F-E-06: Dosimetric Characterization of Small Photons Beams of a Novel Linear Accelerator

Energy Technology Data Exchange (ETDEWEB)

Almonte, A; Polanco, G; Sanchez, E [Instituto Oncologico Dr. Heriberto Pieter, Santo Domingo, Distrito Nacional (Dominican Republic)

2016-06-15

Purpose: The aim of the present contribution was to measure the main dosimetric quantities of small fields produced by UNIQUE and evaluate its matching with the corresponding dosimetric data of one 21EX conventional linear accelerator (Varian) in operation at the same center. The second step was to evaluate comparative performance of the EDGE diode detector and the PinPoint micro-ionization chamber for dosimetry of small fields. Methods: UNIQUE is configured with MLC (120 leaves with 0.5 cm leaf width) and a single low photon energy of 6 MV. Beam data were measured with scanning EDGE diode detector (volume of 0.019 mm{sup 3}), a PinPoint micro-ionization chamber (PTW) and for larger fields (≥ 4×4cm{sup 2}) a PTW Semi flex chamber (0.125 cm{sup 3}) was used. The scanning system used was the 3D cylindrical tank manufactured by Sun Nuclear, Inc. The measurement of PDD and profiles were done at 100 cm SSD and 1.5 depth; the relative output factors were measured at 10 cm depth. Results: PDD and the profile data showed less than 1% variation between the two linear accelerators for fields size between 2×2 cm{sup 2} and 5×5cm{sup 2}. Output factor differences was less than 1% for field sizes between 3×3 cm{sup 2} and 10×10 cm{sup 2} and less of 1.5 % for fields of 1.5×1.5 cm{sup 2} and 2×2 cm{sup 2} respectively. The dmax value of the EDGE diode detector, measured from the PDD, was 8.347 mm for 0.5×0,5cm{sup 2} for UNIQUE. The performance of EDGE diode detector was comparable for all measurements in small fields. Conclusion: UNIQUE linear accelerator show similar dosimetrics characteristics as conventional 21EX Varian linear accelerator for small, medium and large field sizes.EDGE detector show good performance by measuring dosimetrics quantities in small fields typically used in IMRT and radiosurgery treatments.

Dosimetric Comparison of Helical Tomotherapy and Dynamic Conformal Arc Therapy in Stereotactic Radiosurgery for Vestibular Schwannomas

International Nuclear Information System (INIS)

Lee, Tsair-Fwu; Chao, Pei-Ju; Wang, Chang-Yu; Lan, Jen-Hong; Huang, Yu-Je; Hsu, Hsuan-Chih; Sung, Chieh-Cheng; Su, Te-Jen; Lian, Shi-Long; Fang, Fu-Min

2011-01-01

The dosimetric results of stereotactic radiosurgery (SRS) for vestibular schwannoma (VS) performed using dynamic conformal arc therapy (DCAT) with the Novalis system and helical TomoTherapy (HT) were compared using plan quality indices. The HT plans were created for 10 consecutive patients with VS previously treated with SRS using the Novalis system. The dosimetric indices used to compare the techniques included the conformity index (CI) and homogeneity index (HI) for the planned target volume (PTV), the comprehensive quality index (CQI) for nine organs at risk (OARs), gradient score index (GSI) for the dose drop-off outside the PTV, and plan quality index (PQI), which was verified using the plan quality discerning power (PQDP) to incorporate 3 plan indices, to evaluate the rival plans. The PTV ranged from 0.27-19.99 cm 3 (median 3.39 cm 3 ), with minimum required PTV prescribed doses of 10-16 Gy (median 12 Gy). Both systems satisfied the minimum required PTV prescription doses. HT conformed better to the PTV (CI: 1.51 ± 0.23 vs. 1.94 ± 0.34; p < 0.01), but had a worse drop-off outside the PTV (GSI: 40.3 ± 10.9 vs. 64.9 ± 13.6; p < 0.01) compared with DCAT. No significant difference in PTV homogeneity was observed (HI: 1.08 ± 0.03 vs. 1.09 ± 0.02; p = 0.20). HT had a significantly lower maximum dose in 4 OARs and significant lower mean dose in 1 OAR; by contrast, DCAT had a significantly lower maximum dose in 1 OAR and significant lower mean dose in 2 OARs, with the CQI of the 9 OARs = 0.92 ± 0.45. Plan analysis using PQI (HT 0.37 ± 0.12 vs. DCAT 0.65 ± 0.08; p < 0.01), and verified using the PQDP, confirmed the dosimetric advantage of HT. However, the HT system had a longer beam-on time (33.2 ± 7.4 vs. 4.6 ± 0.9 min; p < 0.01) and consumed more monitor units (16772 ± 3803 vs. 1776 ± 356.3; p < 0.01). HT had a better dose conformity and similar dose homogeneity but worse dose gradient than DCAT. Plan analysis confirmed the dosimetric advantage of HT

Study of dosimetric quantities and image quality in pediatric examinations of chest and abdomen computed tomography

International Nuclear Information System (INIS)

Jornada, Tiago da Silva

2013-01-01

This work had the objective to achieve the knowledge of the dosimetric quantities related to chest and abdomen computed tomography (CT) examinations of pediatric patients, in Belo Horizonte city. The reason of this work is based on the fact that the probability of health detriment in children, which it may be caused by radiation, is higher than in adults. Besides, although in many countries the knowledge and control of patient doses is a normal procedure, this safety culture does not exist in Brazil. Another objective of this work was to compare the dosimetric quantity values with the Diagnostic Reference Levels (DRLs); when it was needed, an optimization process was applied and the quality of the diagnostic image obtained with the optimized technical parameters was analyzed. This study was carried out in five hospitals, where the weighted air kerma index (Cw), the volumetric air kerma index (Cvol), the air kerma - length product (PKL,CT), the Effective Dose (E) and the Normalized Effective Dose (En) were determined; three methods were adopted for measurements: the ionization chamber inside a chest pediatric phantom, radiochromic films and the CT-EXPO software. The optimization process was applied to a single hospital through variations in the current (mA) and voltage (kV) of the x-ray tube for the protocols used for abdomen CT examinations. The analysis of the quality of the diagnostic image was done by Normal Distribution and ROC analysis; spatial resolution analysis was used through MTF determination and the noise level was judged in terms quantitative and qualitative. Results of the dosimetric quantities showed that they significantly differed between single-slice and multi-slice tomography units, but their values were always below the recommended DRLs. The optimized values of the dosimetric quantities obtained after the optimization process showed that it was possible to reduce the radiation exposure of pediatric patient without losing the image quality

Multi-subject atlas-based auto-segmentation reduces interobserver variation and improves dosimetric parameter consistency for organs at risk in nasopharyngeal carcinoma: A multi-institution clinical study

International Nuclear Information System (INIS)

Tao, Chang-Juan; Yi, Jun-Lin; Chen, Nian-Yong; Ren, Wei; Cheng, Jason; Tung, Stewart; Kong, Lin; Lin, Shao-Jun; Pan, Jian-Ji; Zhang, Guang-Shun; Hu, Jiang; Qi, Zhen-Yu; Ma, Jun; Lu, Jia-De; Yan, Di; Sun, Ying

2015-01-01

Background and purpose: To assess whether consensus guideline-based atlas-based auto-segmentation (ABAS) reduces interobserver variation and improves dosimetric parameter consistency for organs at risk (OARs) in nasopharyngeal carcinoma (NPC). Materials and methods: Eight radiation oncologists from 8 institutes contoured 20 OARs on planning CT images of 16 patients via manual contouring and manually-edited ABAS contouring. Interobserver variation [volume coefficient of variation (CV), Dice similarity coefficient (DSC), three-dimensional isocenter difference (3D-ICD)] and dosimetric parameters were compared between the two methods of contouring for each OAR. Results: Interobserver variation was significant for all OARs in manual contouring, resulting in significant dosimetric parameter variation (P < 0.05). Edited ABAS significantly improved multiple metrics and reduced dosimetric parameter variation for most OARs; brainstem, spinal cord, cochleae, temporomandibular joint (TMJ), larynx and pharyngeal constrictor muscle (PCM) obtained most benefit (range of mean DSC, volume CV and main ICD values was 0.36–0.83, 12.1–84.3%, 2.2–5.0 mm for manual contouring and 0.42–0.86, 7.2–70.6%, 1.2–3.5 mm for edited ABAS contouring, respectively; range of dose CV reduction: 1.0–3.0%). Conclusion: Substantial objective interobserver differences occur during manual contouring, resulting in significant dosimetric parameter variation. Edited ABAS reduced interobserver variation and improved dosimetric parameter consistency, particularly for brainstem, spinal cord, cochleae, TMJ, larynx and PCM

Dosimetric study to voxel model applied to cardiac exams in Nuclear medicine

International Nuclear Information System (INIS)

Cassola, V.F.; Silva, A.M. Marques da; Hoff, G.

2008-01-01

The objective of this study is to analyze the dosimetry in a simplified model of the region of interest of myocardial perfusion studies considering different descriptions of Tc-99m emission spectra. It aims to assess the implications of these different approaches in the description of Tc-99m spectrum, as well as their dosimetric implications

SPRT Calibration Uncertainties and Internal Quality Control at a Commercial SPRT Calibration Facility

Science.gov (United States)

Wiandt, T. J.

2008-06-01

The Hart Scientific Division of the Fluke Corporation operates two accredited standard platinum resistance thermometer (SPRT) calibration facilities, one at the Hart Scientific factory in Utah, USA, and the other at a service facility in Norwich, UK. The US facility is accredited through National Voluntary Laboratory Accreditation Program (NVLAP), and the UK facility is accredited through UKAS. Both provide SPRT calibrations using similar equipment and procedures, and at similar levels of uncertainty. These uncertainties are among the lowest available commercially. To achieve and maintain low uncertainties, it is required that the calibration procedures be thorough and optimized. However, to minimize customer downtime, it is also important that the instruments be calibrated in a timely manner and returned to the customer. Consequently, subjecting the instrument to repeated calibrations or extensive repeated measurements is not a viable approach. Additionally, these laboratories provide SPRT calibration services involving a wide variety of SPRT designs. These designs behave differently, yet predictably, when subjected to calibration measurements. To this end, an evaluation strategy involving both statistical process control and internal consistency measures is utilized to provide confidence in both the instrument calibration and the calibration process. This article describes the calibration facilities, procedure, uncertainty analysis, and internal quality assurance measures employed in the calibration of SPRTs. Data will be reviewed and generalities will be presented. Finally, challenges and considerations for future improvements will be discussed.

On the set up of a thermoluminescent dosimetric system

International Nuclear Information System (INIS)

Furetta, C.

2000-01-01

In this work are treated the following features: Introduction to the thermoluminescent dosimetric systems, their prerequisites, Initialisation procedure, Batch homogeneity, Procedure for batch homogeneity (IEC), Reference and field dosimeters, Thermal treatments and its general considerations, as well as its initialisation treatment, erasing treatment or standard annealing (also called pre-irradiation annealing), post-irradiation or pre-readout annealing. Also is presented the performance of the annealing study, with its suggested procedures such as: a first and second procedures. Finally, it is showed about experimental data of the annealing treatments and its diagrams. (Author)

Calibration and intercomparison methods of dose calibrators used in nuclear medicine facilities

International Nuclear Information System (INIS)

Costa, Alessandro Martins da

1999-01-01

Dose calibrators are used in most of the nuclear medicine facilities to determine the amount of radioactivity administered to a patient in a particular investigation or therapeutic procedure. It is therefore of vital importance that the equipment used presents good performance and is regular;y calibrated at a authorized laboratory. This occurs of adequate quality assurance procedures are carried out. Such quality control tests should be performed daily, other biannually or yearly, testing, for example, its accuracy and precision, the reproducibility and response linearity. In this work a commercial dose calibrator was calibrated with solution of radionuclides used in nuclear medicine. Simple instrument tests, such as response linearity and the response variation of the source volume increase at a constant source activity concentration, were performed. This instrument can now be used as a working standard for calibration of other dose calibrators/ An intercomparison procedure was proposed as a method of quality control of dose calibrators used in nuclear medicine facilities. (author)

On the use of advanced numerical models for the evaluation of dosimetric parameters and the verification of exposure limits at workplaces

International Nuclear Information System (INIS)

Catarinucci, L.; Tarricone, L.

2009-01-01

With the next transposition of the 2004/40/EC Directive, employers will become responsible for the electromagnetic field level at the workplace. To make this task easier, the scientific community is compiling practical guidelines to be followed. This work aims at enriching such guidelines, especially for the dosimetric issues. More specifically, some critical aspects related to the application of numerical dosimetric techniques for the verification of the safety limit compliance have been highlighted. In particular, three different aspects have been considered: the dosimetric parameter dependence on the shape and the inner characterisation of the exposed subject as well as on the numerical algorithm used, and the correlation between reference limits and basic restriction. Results and discussions demonstrate how, even by using sophisticated numerical techniques, in some cases a complex interpretation of the result is mandatory. (authors)

Mechanics of log calibration

International Nuclear Information System (INIS)

Waller, W.C.; Cram, M.E.; Hall, J.E.

1975-01-01

For any measurement to have meaning, it must be related to generally accepted standard units by a valid and specified system of comparison. To calibrate well-logging tools, sensing systems are designed which produce consistent and repeatable indications over the range for which the tool was intended. The basics of calibration theory, procedures, and calibration record presentations are reviewed. Calibrations for induction, electrical, radioactivity, and sonic logging tools will be discussed. The authors' intent is to provide an understanding of the sources of errors, of the way errors are minimized in the calibration process, and of the significance of changes in recorded calibration data

Dosimetric impact of a CT metal artefact suppression algorithm for proton, electron and photon therapies

International Nuclear Information System (INIS)

Wei Jikun; Sandison, George A; Hsi, W-C; Ringor, Michael; Lu Xiaoyi

2006-01-01

Accurate dose calculation is essential to precision radiation treatment planning and this accuracy depends upon anatomic and tissue electron density information. Modern treatment planning inhomogeneity corrections use x-ray CT images and calibrated scales of tissue CT number to electron density to provide this information. The presence of metal in the volume scanned by an x-ray CT scanner causes metal induced image artefacts that influence CT numbers and thereby introduce errors in the radiation dose distribution calculated. This paper investigates the dosimetric improvement achieved by a previously proposed x-ray CT metal artefact suppression technique when the suppressed images of a patient with bilateral hip prostheses are used in commercial treatment planning systems for proton, electron or photon therapies. For all these beam types, this clinical image and treatment planning study reveals that the target may be severely underdosed if a metal artefact-contaminated image is used for dose calculations instead of the artefact suppressed one. Of the three beam types studied, the metal artefact suppression is most important for proton therapy dose calculations, intermediate for electron therapy and least important for x-ray therapy but still significant. The study of a water phantom having a metal rod simulating a hip prosthesis indicates that CT numbers generated after image processing for metal artefact suppression are accurate and thus dose calculations based on the metal artefact suppressed images will be of high fidelity

Dosimetric characteristics of muscovite mineral studied under different annealing conditions

International Nuclear Information System (INIS)

Kalita, J M; Wary, G

2015-01-01

The annealing effect on the thermoluminescence (TL) characteristics of x-ray irradiated muscovite mineral relevant to dosimetry has been studied. For un-annealed and 473 K annealed samples an isolated TL peak has been observed at around 347 K; however, annealing at 573, 673 and 773 K two composite peaks have been recorded at around 347 and 408 K. Kinetic analysis reveals that there is a trap level at a depth of 0.71 eV, and due to annealing at 573 K (or above), a new trap level generates at 1.23 eV. The dosimetric characteristics, such as dose response, fading and reproducibility, have been studied in detail for all types of samples. The highest linear dose response has been observed from 10 to 2000 mGy in the 773 K annealed sample. Due to generation of the deep trap level, fading is found to reduce significantly just after annealing above 573 K. Reproducibility analysis shows that after 10 cycles of reuse the coefficient of variations in the results for 60, 180 and 1000 mGy dose irradiated 773 K annealed samples are found to be 1.78%, 1.37% and 1.58%, respectively. These analyses demand that after proper annealing muscovite shows important dosimetric features that are essentially required for a thermoluminescence dosimeter (TLD). (paper)

Scanner calibration revisited

Directory of Open Access Journals (Sweden)

Pozhitkov Alexander E

2010-07-01

Full Text Available Abstract Background Calibration of a microarray scanner is critical for accurate interpretation of microarray results. Shi et al. (BMC Bioinformatics, 2005, 6, Art. No. S11 Suppl. 2. reported usage of a Full Moon BioSystems slide for calibration. Inspired by the Shi et al. work, we have calibrated microarray scanners in our previous research. We were puzzled however, that most of the signal intensities from a biological sample fell below the sensitivity threshold level determined by the calibration slide. This conundrum led us to re-investigate the quality of calibration provided by the Full Moon BioSystems slide as well as the accuracy of the analysis performed by Shi et al. Methods Signal intensities were recorded on three different microarray scanners at various photomultiplier gain levels using the same calibration slide from Full Moon BioSystems. Data analysis was conducted on raw signal intensities without normalization or transformation of any kind. Weighted least-squares method was used to fit the data. Results We found that initial analysis performed by Shi et al. did not take into account autofluorescence of the Full Moon BioSystems slide, which led to a grossly distorted microarray scanner response. Our analysis revealed that a power-law function, which is explicitly accounting for the slide autofluorescence, perfectly described a relationship between signal intensities and fluorophore quantities. Conclusions Microarray scanners respond in a much less distorted fashion than was reported by Shi et al. Full Moon BioSystems calibration slides are inadequate for performing calibration. We recommend against using these slides.

Development and application of a dosimetric methodology of therapeutic X radiation beams using a tandem system

International Nuclear Information System (INIS)

Sartoris, Carla Eri

2001-01-01

In radiotherapy the use of orthovoltage X radiation beams is still recommended; to obtain satisfactory results, a periodic control is necessary to check the performance of the ionization chambers and the radiation beams characteristics. This control is performed by using standard dosimetric procedures, as for example the determination of half-value layers and the absorbed dose rates. A Tandem system was established in this work using a pair of ionization chambers (a thimble type and a superficial type) used for measures in a medical institution, in substitution to the routine conventional procedure of determination of half-value layers using absorbers. The results obtained show the application of this method in dosimetric procedures of orthovoltage beams (radiotherapy) as a complement for a quality control program. (author)

Investigation of dosimetric characteristics of the high sensitivity LiF:Mg,Cu,P thermoluminescent dosemeter and its applications in diagnostic radiology

International Nuclear Information System (INIS)

Fung, K.K.L.

2000-12-01

The recent introduction and development of the thermoluminescent (T.L.) phosphor material LiF:Mg,Cu,P (usually named TLD100H or GR200A) has aroused intense interest of scientists in the field of radiation dosimetry due to its very favourable dosimetric characteristics. Both conventional LiF:Mg,Ti (TLD100) and LiF:Mg,Cu,P T.L. phosphors are tissue-equivalent but GR200A outperforms in respect of its very much higher sensitivity, by a factor of greater than 25, and a dose detection threshold of less than 1 μGy. A reproducible readout and annealing regime was developed in the initial part of this study with the newly installed automatic TLD (Thermoluminescence Dosimetry) apparatus in the X-ray and Radiation Physics Laboratories of the Hong Kong Polytechnic University. Basic dosimetric characteristics of this T.L. dosemeter (supplied by Harshaw-Bicron Co.) were then investigated. This paved the foundation for subsequent selected novel application studies in diagnostic radiology. Dosimetric characteristics which included linearity, reproducibility, batch uniformity, energy response, and minimum detectable dose were studied using X-rays in the commonly used diagnostic radiology energy range. Favourable dosimetric characteristics were observed from this T.L. phosphor, which agrees well with published studies. The effect of the number of thermal treatment cycles in the initialisation process on dosimetric properties of this T.L. phosphor was also investigated. This study exploits the favourable dosimetric properties of these T.L. dosemeters in some selected novel dosimetric applications in diagnostic radiology with an anthropomorphic phantom using facilities both in these laboratories and also in radiology departments of various district hospitals in Hong Kong. Radiation absorbed dose from the direct or scattered beam, at critical sites inside and on the surface of the phantom, were measured in these radiological studies. The special focus in some of these studies was to

Investigation of dosimetric characteristics of the high sensitivity LiF:Mg,Cu,P thermoluminescent dosemeter and its applications in diagnostic radiology

Energy Technology Data Exchange (ETDEWEB)

Fung, K.K.L

2000-12-01

The recent introduction and development of the thermoluminescent (T.L.) phosphor material LiF:Mg,Cu,P (usually named TLD100H or GR200A) has aroused intense interest of scientists in the field of radiation dosimetry due to its very favourable dosimetric characteristics. Both conventional LiF:Mg,Ti (TLD100) and LiF:Mg,Cu,P T.L. phosphors are tissue-equivalent but GR200A outperforms in respect of its very much higher sensitivity, by a factor of greater than 25, and a dose detection threshold of less than 1 {mu}Gy. A reproducible readout and annealing regime was developed in the initial part of this study with the newly installed automatic TLD (Thermoluminescence Dosimetry) apparatus in the X-ray and Radiation Physics Laboratories of the Hong Kong Polytechnic University. Basic dosimetric characteristics of this T.L. dosemeter (supplied by Harshaw-Bicron Co.) were then investigated. This paved the foundation for subsequent selected novel application studies in diagnostic radiology. Dosimetric characteristics which included linearity, reproducibility, batch uniformity, energy response, and minimum detectable dose were studied using X-rays in the commonly used diagnostic radiology energy range. Favourable dosimetric characteristics were observed from this T.L. phosphor, which agrees well with published studies. The effect of the number of thermal treatment cycles in the initialisation process on dosimetric properties of this T.L. phosphor was also investigated. This study exploits the favourable dosimetric properties of these T.L. dosemeters in some selected novel dosimetric applications in diagnostic radiology with an anthropomorphic phantom using facilities both in these laboratories and also in radiology departments of various district hospitals in Hong Kong. Radiation absorbed dose from the direct or scattered beam, at critical sites inside and on the surface of the phantom, were measured in these radiological studies. The special focus in some of these studies was to

Practical realisation of individual dosimetric control of internal and external irradiation during works at 'Ukrytie' shelter

International Nuclear Information System (INIS)

Likhtarev, I.A.; Bondarenko, O.S.; Berkovskij, V.B.; Chumak, V.K.; Korneev, A.A.; Dmitrienko, A.V.

1999-01-01

Individual dosimetric control requires the minimisation of personnel irradiation doses and needs forecasting and planning of dose loads. System of individual dose control and its functions at 'Ukrytie' shelter are described

SU-F-BRB-15: Dosimetric Study of Radiation Therapy for Head/Neck Patients with Metallic Dental Fixtures

Energy Technology Data Exchange (ETDEWEB)

Lu, L; Allan, E; Putten, M Van; Gupta, N; Blakaj, D [OH State University, Columbus, OH (United States)

2015-06-15

Purpose: To investigate the dose contributions of scattered electrons from dental amalgams during head and neck radiotherapy, and to evaluate the protective role of dosimetric dental stents during treatment to prevent oral mucositis. Methods: A phantom was produced to accurately simulate the oral cavity and head. The oral cavity consisted of a tissue equivalent upper and lower jaw and complete set of teeth. A set of 4 mm ethylene copolymer dosimetric stents was made for the upper and lower teeth. Five removable gold caps were fitted to apposing right molars, and the phantom was crafted to accomodate horizontal and vertical film for 2D dosimetry and NanoDot dosimeter for recording point doses. The head was simulated using a small cylindrical glass water bath. CT simulation was performed on the phantom with and without metal fittings and, in each case, with and without the dental stent. The CT image sets were imported into Eclipse treatment planning system for contouring and treatment planning, and a 9-field IMRT treatment plan was developed for each scenario. These plans were delivered using a Varian TrueBeam linear accelerator. Doses were recorded using GafChromic EBT2 films and NanoDot dosimeters. Results: The measurements revealed a 43% relative increase in dose measured adjacent to the metal fixtures in the horizontal plane without the use of the dental stent. This equates to a total dose of 100 Gy to the oral mucosa during a standard course of definitive radiotherapy. To our knowledge, this is the first dosimetric analysis of dental stents using an anatomically realistic phantom and modern beam arrangement. Conclusion: These results support the use of dosimetric dental stents in head and neck radiotherapy for patients with metallic dental fixtures as a way to effectively reduce dose to nearby mucosal surfaces and, hence, reduce the risk and severity of mucositis.

SU-F-BRB-15: Dosimetric Study of Radiation Therapy for Head/Neck Patients with Metallic Dental Fixtures

International Nuclear Information System (INIS)

Lu, L; Allan, E; Putten, M Van; Gupta, N; Blakaj, D

2015-01-01

Purpose: To investigate the dose contributions of scattered electrons from dental amalgams during head and neck radiotherapy, and to evaluate the protective role of dosimetric dental stents during treatment to prevent oral mucositis. Methods: A phantom was produced to accurately simulate the oral cavity and head. The oral cavity consisted of a tissue equivalent upper and lower jaw and complete set of teeth. A set of 4 mm ethylene copolymer dosimetric stents was made for the upper and lower teeth. Five removable gold caps were fitted to apposing right molars, and the phantom was crafted to accomodate horizontal and vertical film for 2D dosimetry and NanoDot dosimeter for recording point doses. The head was simulated using a small cylindrical glass water bath. CT simulation was performed on the phantom with and without metal fittings and, in each case, with and without the dental stent. The CT image sets were imported into Eclipse treatment planning system for contouring and treatment planning, and a 9-field IMRT treatment plan was developed for each scenario. These plans were delivered using a Varian TrueBeam linear accelerator. Doses were recorded using GafChromic EBT2 films and NanoDot dosimeters. Results: The measurements revealed a 43% relative increase in dose measured adjacent to the metal fixtures in the horizontal plane without the use of the dental stent. This equates to a total dose of 100 Gy to the oral mucosa during a standard course of definitive radiotherapy. To our knowledge, this is the first dosimetric analysis of dental stents using an anatomically realistic phantom and modern beam arrangement. Conclusion: These results support the use of dosimetric dental stents in head and neck radiotherapy for patients with metallic dental fixtures as a way to effectively reduce dose to nearby mucosal surfaces and, hence, reduce the risk and severity of mucositis

Absolute radiometric calibration of Landsat using a pseudo invariant calibration site

Science.gov (United States)

Helder, D.; Thome, K.J.; Mishra, N.; Chander, G.; Xiong, Xiaoxiong; Angal, A.; Choi, Tae-young

2013-01-01

Pseudo invariant calibration sites (PICS) have been used for on-orbit radiometric trending of optical satellite systems for more than 15 years. This approach to vicarious calibration has demonstrated a high degree of reliability and repeatability at the level of 1-3% depending on the site, spectral channel, and imaging geometries. A variety of sensors have used this approach for trending because it is broadly applicable and easy to implement. Models to describe the surface reflectance properties, as well as the intervening atmosphere have also been developed to improve the precision of the method. However, one limiting factor of using PICS is that an absolute calibration capability has not yet been fully developed. Because of this, PICS are primarily limited to providing only long term trending information for individual sensors or cross-calibration opportunities between two sensors. This paper builds an argument that PICS can be used more extensively for absolute calibration. To illustrate this, a simple empirical model is developed for the well-known Libya 4 PICS based on observations by Terra MODIS and EO-1 Hyperion. The model is validated by comparing model predicted top-of-atmosphere reflectance values to actual measurements made by the Landsat ETM+ sensor reflective bands. Following this, an outline is presented to develop a more comprehensive and accurate PICS absolute calibration model that can be Système international d'unités (SI) traceable. These initial concepts suggest that absolute calibration using PICS is possible on a broad scale and can lead to improved on-orbit calibration capabilities for optical satellite sensors.

Characterization of TLD-100 in powders for dosimetric quality control of {sup 192} Ir sources used in brachytherapy of high dose rate; Caracterizacion de TLD-100 en polvo para control de calidad dosimetrico de fuentes de Ir{sup 192} usadas en braquiterapia de alta tasa de dosis

Energy Technology Data Exchange (ETDEWEB)

Loaiza C, S.P

2007-07-01

The Secondary Standard Dosimetric at the National Institute of Nuclear Research (ININ) calibrated a lot of powdered TLD-100 (LiF:Mg,Ti) in terms of absorbed dose to water D{sub w} for the energy of: {sup 60}Co, {sup 137C}s, X rays of 250 and 50 kVp. Later on, it is carried out an interpolation of the calibration for the energy of the {sup 192}Ir. This calibration is part of a dosimetric quality control program, to solve the problems of traceability for the measurements carried out by the users of {sup 192}Ir sources employed in the treatments of High Dose Rate Brachytherapy (HDR) at the Mexican Republic. The calibrations of the radiation beams are made with the following protocols: IAEA TRS-398 for the {sup 60}Co for D{sub w}, using a secondary standard ionization chamber PTW N30013 calibrated in D{sub w} by the National Research Council (NRC, Canada). AAPM TG-43 for D{sub w} in terms of the strength kerma Sk, calibrating this last one quantity for the {sup 137}Cs radioactive source, with a well chamber HDR 1000 PLUS traceable to the University of Wisconsin (US). AAPM TG-61 for X ray of 250 and 50 kVp for D{sub w} start to Ka using field standard a Farmer chamber PTW 30001 traceable to K for the Central Laboratory of Electric Industries (CLEI, France). The calibration curves (CC) they built for the response of the powder TLD: R{sub TLD} vs D{sub w}: For the energy of {sup 60}Co, {sup 137}Cs, X rays of 250 and 50 kVp. Fitting them with the least square method weighed by means of a polynomial of second grade that corrects the supra linearity of the response. iii. Each one of the curves was validated with a test by lack of fitting and for the Anderson Darling normality test, using the software MINITAB in both cases. iv. The sensibility factor (F{sub s}) for each energy corresponds to the slope of the CC, v. The F{sub s} for the two {sup 192}Ir sources used are interpolated: one for a Micro Selectron source and the other one a Vari Source source. Finally, a couple of

Silicon strip detector for a novel 2D dosimetric method for radiotherapy treatment verification

Science.gov (United States)

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

2012-05-01

The aim of this work is to characterize a silicon strip detector and its associated data acquisition system, based on discrete electronics, to obtain in a near future absorbed dose maps in axial planes for complex radiotherapy treatments, using a novel technique. The experimental setup is based on two phantom prototypes: the first one is a polyethylene slab phantom used to characterize the detector in terms of linearity, percent depth dose, reproducibility, uniformity and penumbra. The second one is a cylindrical phantom, specifically designed and built to recreate conditions close to those normally found in clinical environments, for treatment planning assessment. This system has been used to study the dosimetric response of the detector, in the axial plane of the phantom, as a function of its angle with respect to the irradiation beam. A software has been developed to operate the rotation of this phantom and to acquire signals from the silicon strip detector. As an innovation, the detector was positioned inside the cylindrical phantom parallel to the beam axis. Irradiation experiments were carried out with a Siemens PRIMUS linac operating in the 6 MV photon mode at the Virgen Macarena Hospital. Monte Carlo simulations were performed using Geant4 toolkit and results were compared to Treatment Planning System (TPS) calculations for the absorbed dose-to-water case. Geant4 simulations were used to estimate the sensitivity of the detector in different experimental configurations, in relation to the absorbed dose in each strip. A final calibration of the detector in this clinical setup was obtained by comparing experimental data with TPS calculations.

ARDENT to develop advanced dosimetric techniques

CERN Document Server

Antonella Del Rosso

2012-01-01

Earlier this week, the EU-supported Marie Curie training network ARDENT kicked off at a meeting held at CERN. The overall aim of the project is the development of advanced instrumentation for radiation dosimetry. The applications range from radiation measurements around particle accelerators, onboard commercial flights and in space, to the characterization of radioactive waste and medicine, where accurate dosimetry is of vital importance.   The ARDENT (Advanced Radiation Dosimetry European Network Training) project is both a research and a training programme, which aims at developing new dosimetric techniques while providing 15 Early-Stage Researchers (ESR) with state-of-the-art training. The project, coordinated by CERN, is funded by the European Union with a contribution of about 3.9 million euros over four years. The ARDENT initiative will focus on three main technologies: gas detectors, in particular Gas Electron Multipliers (GEM) and Tissue Equivalent Proportional Counters (TEPC); solid stat...

EchoSeed Model 6733 Iodine-125 brachytherapy source: Improved dosimetric characterization using the MCNP5 Monte Carlo code

Energy Technology Data Exchange (ETDEWEB)

Mosleh-Shirazi, M. A.; Hadad, K.; Faghihi, R.; Baradaran-Ghahfarokhi, M.; Naghshnezhad, Z.; Meigooni, A. S. [Center for Research in Medical Physics and Biomedical Engineering and Physics Unit, Radiotherapy Department, Shiraz University of Medical Sciences, Shiraz 71936-13311 (Iran, Islamic Republic of); Radiation Research Center and Medical Radiation Department, School of Engineering, Shiraz University, Shiraz 71936-13311 (Iran, Islamic Republic of); Comprehensive Cancer Center of Nevada, Las Vegas, Nevada 89169 (United States)

2012-08-15

This study primarily aimed to obtain the dosimetric characteristics of the Model 6733 {sup 125}I seed (EchoSeed) with improved precision and accuracy using a more up-to-date Monte-Carlo code and data (MCNP5) compared to previously published results, including an uncertainty analysis. Its secondary aim was to compare the results obtained using the MCNP5, MCNP4c2, and PTRAN codes for simulation of this low-energy photon-emitting source. The EchoSeed geometry and chemical compositions together with a published {sup 125}I spectrum were used to perform dosimetric characterization of this source as per the updated AAPM TG-43 protocol. These simulations were performed in liquid water material in order to obtain the clinically applicable dosimetric parameters for this source model. Dose rate constants in liquid water, derived from MCNP4c2 and MCNP5 simulations, were found to be 0.993 cGyh{sup -1} U{sup -1} ({+-}1.73%) and 0.965 cGyh{sup -1} U{sup -1} ({+-}1.68%), respectively. Overall, the MCNP5 derived radial dose and 2D anisotropy functions results were generally closer to the measured data (within {+-}4%) than MCNP4c and the published data for PTRAN code (Version 7.43), while the opposite was seen for dose rate constant. The generally improved MCNP5 Monte Carlo simulation may be attributed to a more recent and accurate cross-section library. However, some of the data points in the results obtained from the above-mentioned Monte Carlo codes showed no statistically significant differences. Derived dosimetric characteristics in liquid water are provided for clinical applications of this source model.

Study and mitigation of calibration factor instabilities in a water vapor Raman lidar

Directory of Open Access Journals (Sweden)

L. David

2017-07-01

Full Text Available We have investigated calibration variations in the Rameau water vapor Raman lidar. This lidar system was developed by the Institut National de l'Information Géographique et Forestière (IGN together with the Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS. It aims at calibrating Global Navigation Satellite System (GNSS measurements for tropospheric wet delays and sounding the water vapor variability in the lower troposphere. The Rameau system demonstrated good capacity in retrieving water vapor mixing ratio (WVMR profiles accurately in several campaigns. However, systematic short-term and long-term variations in the lidar calibration factor pointed to persistent instabilities. A careful testing of each subsystem independently revealed that these instabilities are mainly induced by mode fluctuations in the optic fiber used to couple the telescope to the detection subsystem and by the spatial nonuniformity of the photomultiplier photocathodes. Laboratory tests that replicate and quantify these instability sources are presented. A redesign of the detection subsystem is presented, which, combined with careful alignment procedures, is shown to significantly reduce the instabilities. Outdoor measurements were performed over a period of 5 months to check the stability of the modified lidar system. The calibration changes in the detection subsystem were monitored with lidar profile measurements using a common nitrogen filter in both Raman channels. A short-term stability of 2–3 % and a long-term drift of 2–3 % per month are demonstrated. Compared to the earlier Development of Methodologies for Water Vapour Measurement (DEMEVAP campaign, this is a 3-fold improvement in the long-term stability of the detection subsystem. The overall water vapor calibration factors were determined and monitored with capacitive humidity sensor measurements and with GPS zenith wet delay (ZWD data. The changes in the water vapor calibration factors

Harmonisation and dosimetric quality assurance in individual monitoring for external radiation

DEFF Research Database (Denmark)

Bartlett, D.T.; Ambrosi, P.; Back, C.

2001-01-01

The current situation amongst Member States is that there are widely differing national requirements for dosimetric services and for dosemeter performance. It is clear that with the free movement of workers within the European Union (EU) and the requirements for individual dosimetry given...... of individual monitoring using personal dosemeters and assisting movement towards harmonised procedures. An outline of the work of the action group is given and the term 'harmonisation' is discussed....

Present status of the dosimetric control of food irradiation in France

International Nuclear Information System (INIS)

Laizier, J.; Mosse, D.

1986-01-01

The irradiation of food arises much interest in France, although the process is still industrially used to a very limited extend, but every facts indicate a strong trend to the development of the uses. This arises new problems of dosimetric control. The efforts of the few last years to overcome those problems were focused along two axis: the development of a code of good practice and that of using more widely the alanine dosimeter

MO-A-BRC-01: TG167 Report - Introduction

Energy Technology Data Exchange (ETDEWEB)

Nath, R. [Yale University School of Medicine (United States)

2016-06-15

Although a multicenter, Phase III, prospective, randomized trial is the gold standard for evidence-based medicine, it is rarely used to evaluate innovative radiotherapy devices because of many practical and ethical reasons. It is usually sufficient to compare the dose distributions and dose rates for determining equivalence of the innovative device to an existing one. Thus, quantitative evaluation of the dosimetric characteristics of an innovative brachytherapy device or application is a critical part in which physicists are actively involved. The physicist’s role, along with physician colleagues, in this process is highlighted for innovative products or applications and includes evaluation of 1) dosimetric considerations for clinical implementation (including calibrations, dose calculations, and radiobiological aspects) to comply with existing societal dosimetric prerequisites for sources in routine clinical use, 2) risks and benefits from regulatory and safety perspectives, and 3) resource assessment and preparedness. Further, calibration methods should be traceable to a primary standards dosimetry laboratory such as NIST in the U.S. or to other primary standards dosimetry laboratory located elsewhere. Clinical users should follow standards as approved by their country’s regulatory agencies that approved such a brachytherapy device. Integration of this system into the medical source calibration infrastructure of secondary standard dosimetry laboratories such as the ADCLs is encouraged before a source is introduced into widespread routine clinical use. The AAPM and GEC-ESTRO have developed guidelines for the safe and consistent application of brachytherapy using innovative brachytherapy devices and applications. The current report covers regulatory approvals, calibration, dose calculations, radiobiological issues, and overall safety concerns that should be addressed during the commissioning stage preceding clinical use. These guidelines are based on review of

MO-A-BRC-02: TG167 Report - Detailed Description

Energy Technology Data Exchange (ETDEWEB)

Rivard, M.

2016-06-15

Although a multicenter, Phase III, prospective, randomized trial is the gold standard for evidence-based medicine, it is rarely used to evaluate innovative radiotherapy devices because of many practical and ethical reasons. It is usually sufficient to compare the dose distributions and dose rates for determining equivalence of the innovative device to an existing one. Thus, quantitative evaluation of the dosimetric characteristics of an innovative brachytherapy device or application is a critical part in which physicists are actively involved. The physicist’s role, along with physician colleagues, in this process is highlighted for innovative products or applications and includes evaluation of 1) dosimetric considerations for clinical implementation (including calibrations, dose calculations, and radiobiological aspects) to comply with existing societal dosimetric prerequisites for sources in routine clinical use, 2) risks and benefits from regulatory and safety perspectives, and 3) resource assessment and preparedness. Further, calibration methods should be traceable to a primary standards dosimetry laboratory such as NIST in the U.S. or to other primary standards dosimetry laboratory located elsewhere. Clinical users should follow standards as approved by their country’s regulatory agencies that approved such a brachytherapy device. Integration of this system into the medical source calibration infrastructure of secondary standard dosimetry laboratories such as the ADCLs is encouraged before a source is introduced into widespread routine clinical use. The AAPM and GEC-ESTRO have developed guidelines for the safe and consistent application of brachytherapy using innovative brachytherapy devices and applications. The current report covers regulatory approvals, calibration, dose calculations, radiobiological issues, and overall safety concerns that should be addressed during the commissioning stage preceding clinical use. These guidelines are based on review of

MO-A-BRC-00: TG167: Clinical Recommendations for Innovative Brachytherapy Devices and Applicators

Energy Technology Data Exchange (ETDEWEB)

NONE

2016-06-15

Although a multicenter, Phase III, prospective, randomized trial is the gold standard for evidence-based medicine, it is rarely used to evaluate innovative radiotherapy devices because of many practical and ethical reasons. It is usually sufficient to compare the dose distributions and dose rates for determining equivalence of the innovative device to an existing one. Thus, quantitative evaluation of the dosimetric characteristics of an innovative brachytherapy device or application is a critical part in which physicists are actively involved. The physicist’s role, along with physician colleagues, in this process is highlighted for innovative products or applications and includes evaluation of 1) dosimetric considerations for clinical implementation (including calibrations, dose calculations, and radiobiological aspects) to comply with existing societal dosimetric prerequisites for sources in routine clinical use, 2) risks and benefits from regulatory and safety perspectives, and 3) resource assessment and preparedness. Further, calibration methods should be traceable to a primary standards dosimetry laboratory such as NIST in the U.S. or to other primary standards dosimetry laboratory located elsewhere. Clinical users should follow standards as approved by their country’s regulatory agencies that approved such a brachytherapy device. Integration of this system into the medical source calibration infrastructure of secondary standard dosimetry laboratories such as the ADCLs is encouraged before a source is introduced into widespread routine clinical use. The AAPM and GEC-ESTRO have developed guidelines for the safe and consistent application of brachytherapy using innovative brachytherapy devices and applications. The current report covers regulatory approvals, calibration, dose calculations, radiobiological issues, and overall safety concerns that should be addressed during the commissioning stage preceding clinical use. These guidelines are based on review of

MO-A-BRC-00: TG167: Clinical Recommendations for Innovative Brachytherapy Devices and Applicators

International Nuclear Information System (INIS)

2016-01-01

Although a multicenter, Phase III, prospective, randomized trial is the gold standard for evidence-based medicine, it is rarely used to evaluate innovative radiotherapy devices because of many practical and ethical reasons. It is usually sufficient to compare the dose distributions and dose rates for determining equivalence of the innovative device to an existing one. Thus, quantitative evaluation of the dosimetric characteristics of an innovative brachytherapy device or application is a critical part in which physicists are actively involved. The physicist’s role, along with physician colleagues, in this process is highlighted for innovative products or applications and includes evaluation of 1) dosimetric considerations for clinical implementation (including calibrations, dose calculations, and radiobiological aspects) to comply with existing societal dosimetric prerequisites for sources in routine clinical use, 2) risks and benefits from regulatory and safety perspectives, and 3) resource assessment and preparedness. Further, calibration methods should be traceable to a primary standards dosimetry laboratory such as NIST in the U.S. or to other primary standards dosimetry laboratory located elsewhere. Clinical users should follow standards as approved by their country’s regulatory agencies that approved such a brachytherapy device. Integration of this system into the medical source calibration infrastructure of secondary standard dosimetry laboratories such as the ADCLs is encouraged before a source is introduced into widespread routine clinical use. The AAPM and GEC-ESTRO have developed guidelines for the safe and consistent application of brachytherapy using innovative brachytherapy devices and applications. The current report covers regulatory approvals, calibration, dose calculations, radiobiological issues, and overall safety concerns that should be addressed during the commissioning stage preceding clinical use. These guidelines are based on review of

MO-A-BRC-01: TG167 Report - Introduction

International Nuclear Information System (INIS)

Nath, R.

2016-01-01

Although a multicenter, Phase III, prospective, randomized trial is the gold standard for evidence-based medicine, it is rarely used to evaluate innovative radiotherapy devices because of many practical and ethical reasons. It is usually sufficient to compare the dose distributions and dose rates for determining equivalence of the innovative device to an existing one. Thus, quantitative evaluation of the dosimetric characteristics of an innovative brachytherapy device or application is a critical part in which physicists are actively involved. The physicist’s role, along with physician colleagues, in this process is highlighted for innovative products or applications and includes evaluation of 1) dosimetric considerations for clinical implementation (including calibrations, dose calculations, and radiobiological aspects) to comply with existing societal dosimetric prerequisites for sources in routine clinical use, 2) risks and benefits from regulatory and safety perspectives, and 3) resource assessment and preparedness. Further, calibration methods should be traceable to a primary standards dosimetry laboratory such as NIST in the U.S. or to other primary standards dosimetry laboratory located elsewhere. Clinical users should follow standards as approved by their country’s regulatory agencies that approved such a brachytherapy device. Integration of this system into the medical source calibration infrastructure of secondary standard dosimetry laboratories such as the ADCLs is encouraged before a source is introduced into widespread routine clinical use. The AAPM and GEC-ESTRO have developed guidelines for the safe and consistent application of brachytherapy using innovative brachytherapy devices and applications. The current report covers regulatory approvals, calibration, dose calculations, radiobiological issues, and overall safety concerns that should be addressed during the commissioning stage preceding clinical use. These guidelines are based on review of

MO-A-BRC-02: TG167 Report - Detailed Description

International Nuclear Information System (INIS)

Rivard, M.

2016-01-01

Although a multicenter, Phase III, prospective, randomized trial is the gold standard for evidence-based medicine, it is rarely used to evaluate innovative radiotherapy devices because of many practical and ethical reasons. It is usually sufficient to compare the dose distributions and dose rates for determining equivalence of the innovative device to an existing one. Thus, quantitative evaluation of the dosimetric characteristics of an innovative brachytherapy device or application is a critical part in which physicists are actively involved. The physicist’s role, along with physician colleagues, in this process is highlighted for innovative products or applications and includes evaluation of 1) dosimetric considerations for clinical implementation (including calibrations, dose calculations, and radiobiological aspects) to comply with existing societal dosimetric prerequisites for sources in routine clinical use, 2) risks and benefits from regulatory and safety perspectives, and 3) resource assessment and preparedness. Further, calibration methods should be traceable to a primary standards dosimetry laboratory such as NIST in the U.S. or to other primary standards dosimetry laboratory located elsewhere. Clinical users should follow standards as approved by their country’s regulatory agencies that approved such a brachytherapy device. Integration of this system into the medical source calibration infrastructure of secondary standard dosimetry laboratories such as the ADCLs is encouraged before a source is introduced into widespread routine clinical use. The AAPM and GEC-ESTRO have developed guidelines for the safe and consistent application of brachytherapy using innovative brachytherapy devices and applications. The current report covers regulatory approvals, calibration, dose calculations, radiobiological issues, and overall safety concerns that should be addressed during the commissioning stage preceding clinical use. These guidelines are based on review of

Historical revision of the exposure magnitude and the dosimetric magnitudes used in radiological protection

International Nuclear Information System (INIS)

Gonzalez J, F.; Alvarez R, J. T.

2014-10-01

In this work a historical revision of the exposure magnitude development and their roentgen unit (1905 - 2011) is made, noting that it had their origin in the electric methods for the detection of the ionizing radiation in the period of 1895 at 1937. However, the ionization is not who better characterizes the physical, chemical and biological effects of the ionizing radiations, but is the energy deposited by this radiation in the interest bodies, which led historically to the development of dosimetric magnitudes in energy terms like they are: the absorbed dose D (1950), the kerma K (1958) and the equivalent dose H (1962). These dosimetric magnitudes culminated with the definition of the effective equivalent dose or effective dose which is not measurable and should be considered with the operative magnitudes ICRU: H environmental equivalent dose and/or H directional equivalent dose, which can be determined by means of a conversion coefficient that is applied to the exposure, kerma in air, fluence, etc. (Author)

A Study on the Holding Capacity Safety Factors for Torpedo Anchors

Directory of Open Access Journals (Sweden)

Luís V. S. Sagrilo

2012-01-01

Full Text Available The use of powerful numerical tools based on the finite-element method has been improving the prediction of the holding capacity of fixed anchors employed by the offshore oil industry. One of the main achievements of these tools is the reduction of the uncertainty related to the holding capacity calculation of these anchors. Therefore, it is also possible to reduce the values of the associated design safety factors, which have been calibrated relying on models with higher uncertainty, without impairing the original level of structural safety. This paper presents a study on the calibration of reliability-based safety factors for the design of torpedo anchors considering the statistical model uncertainty evaluated using results from experimental tests and their correspondent finite-element-based numerical predictions. Both working stress design (WSD and load and resistance factors design (LRFD design methodologies are investigated. Considering the WSD design methodology, the single safety is considerably lower than the value typically employed in the design of torpedo anchors. Moreover, a LRFD design code format for torpedo anchors is more appropriate since it leads to designs having less-scattered safety levels around the target value.

“Calibration-on-the-spot”: How to calibrate an EMCCD camera from its images

DEFF Research Database (Denmark)

Mortensen, Kim; Flyvbjerg, Henrik

2016-01-01

In order to count photons with a camera, the camera must be calibrated. Photon counting is necessary, e.g., to determine the precision of localization-based super-resolution microscopy. Here we present a protocol that calibrates an EMCCD camera from information contained in isolated, diffraction-......-limited spots in any image taken by the camera, thus making dedicated calibration procedures redundant by enabling calibration post festum, from images filed without calibration information....

Synthesis and characterization of CaF{sub 2}:Dy nanophosphor for dosimetric application

Energy Technology Data Exchange (ETDEWEB)

Bhadane, Mahesh S.; Dahiwale, S. S.; Bhoraskar, V. N.; Dhole, S. D., E-mail: sanjay@physics.unipune.ac.in [Department of Physics, University of Pune, Pune-411007 (India); Patil, B. J. [Department of Physics, Abasaheb Garware College, Pune-411004 (India); Kulkarni, M. S. [Radiation Safety Systems Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India); Bhatt, B. C. [Radiological Physics and Advisory Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India)

2015-06-24

In this work, nanoparticles (NPs) of dysprosium doped calcium fluoride (CaF{sub 2}:Dy) 1 mol % has been prepared using simple chemical co-precipitation method and its thermoluminescence (TL) dosimetric properties were studied. The synthesized nanoparticle sample was characterized by X-ray diffraction (XRD) and the particle size of face centered cubic phase NPs was found around 30 nm. The shape, morphology and size were also observed by scanning electron microscopy (SEM). From gamma irradiated CaF{sub 2}:Dy TL curves, it was observed that the total areas of all the glow peak intensities are dramatically changed with increase in annealing temperature. Further, TL glow curve of the CaF{sub 2}:Dy at 183 °C annealed at 400 °C, showed very sharp linear response in the dose range from 1 Gy to 750 Gy. This linear response of CaF{sub 2}:Dy nanophosphor as a function of gamma dose is very useful from radiation dosimetric point of view.

Calibration Modeling Methodology to Optimize Performance for Low Range Applications

Science.gov (United States)

McCollum, Raymond A.; Commo, Sean A.; Parker, Peter A.

2010-01-01

Calibration is a vital process in characterizing the performance of an instrument in an application environment and seeks to obtain acceptable accuracy over the entire design range. Often, project requirements specify a maximum total measurement uncertainty, expressed as a percent of full-scale. However in some applications, we seek to obtain enhanced performance at the low range, therefore expressing the accuracy as a percent of reading should be considered as a modeling strategy. For example, it is common to desire to use a force balance in multiple facilities or regimes, often well below its designed full-scale capacity. This paper presents a general statistical methodology for optimizing calibration mathematical models based on a percent of reading accuracy requirement, which has broad application in all types of transducer applications where low range performance is required. A case study illustrates the proposed methodology for the Mars Entry Atmospheric Data System that employs seven strain-gage based pressure transducers mounted on the heatshield of the Mars Science Laboratory mission.

The pitfalls of dosimetric commissioning for intensity modulated radiation therapy

International Nuclear Information System (INIS)

Tohyama, Naoki; Kodama, Takashi; Hatano, K.

2013-01-01

Intensity modulated radiation therapy (IMRT) allows higher radiation dose to be focused to the target volumes while minimizing the dose to OAR. To start of clinical treatment in IMRTvwe must perform commissioning strictly than 3D-conformal radiotherapy (CRT). In this report, pitfalls of dosimetric commissioning for intensity modulated radiation therapy were reviewed. Multileaf collimator (MLC) offsets and MLC transmissions are important parameters in commissioning of RTPS for IMRT. Correction of depth scaling and fluence scaling is necessary for dose measurement using solid phantom. (author)

Dosimetric systems of high dose, dose rate and dose uniformity in food and medical products; Sistemas dosimetricos de altas dosis, tasa de dosis y uniformidad de dosis en alimentos y producto medico

Energy Technology Data Exchange (ETDEWEB)

Vargas, J.; Vivanco, M.; Castro, E., E-mail: jvargas@ipen.gob.pe [Instituto Peruano de Energia Nuclear, Av. Canada 1470, San Borja, Lima (Peru)

2014-08-15

In the Instituto Peruano de Energia Nuclear (IPEN) we use the chemical dosimetry Astm-E-1026 Fricke as a standard dosimetric system of reference and different routine dosimetric systems of high doses, according to the applied doses to obtain the desired effects in the treated products and the doses range determined for each type of dosimeter. Fricke dosimetry is a chemical dosimeter in aqueous solution indicating the absorbed dose by means an increase in absorbance at a specific wavelength. A calibrated spectrophotometer with controlled temperature is used to measure absorbance. The adsorbed dose range should cover from 20 to 400 Gy, the Fricke solution is extremely sensitive to organic impurities, to traces of metal ions, in preparing chemical products of reactive grade must be used and the water purity is very important. Using the referential standard dosimetric system Fricke, was determined to March 5, 2013, using the referential standard dosimetric system Astm-1026 Fricke, were irradiated in triplicate Fricke dosimeters, to 5 irradiation times (20; 30; 40; 50 and 60 seconds) and by linear regression, the dose rate of 5.400648 kGy /h was determined in the central point of the irradiation chamber (irradiator Gamma cell 220 Excel), applying the decay formula, was compared with the obtained results by manufacturers by means the same dosimetric system in the year of its manufacture, being this to the date 5.44691 kGy /h, with an error rate of 0.85. After considering that the dosimetric solution responds to the results, we proceeded to the irradiation of a sample of 200 g of cereal instant food, 2 dosimeters were placed at the lateral ends of the central position to maximum dose and 2 dosimeters in upper and lower ends as minimum dose, they were applied same irradiation times; for statistical analysis, the maximum dose rate was 6.1006 kGy /h and the minimum dose rate of 5.2185 kGy /h; with a dose uniformity of 1.16. In medical material of micro pulverized bone for

Mevatron-74 10MeV photon beam: a study of dosimetric quantities

International Nuclear Information System (INIS)

Souza, C.N. de

1986-01-01

The Mevatron-74 linear accelerator dosimetric quantities were studied. In water and polystyrene measurements with an ionization chamber were done for following physical parameters: maximum dose depth and surface dose, field size dependence, central axis percentage depth dose, beam flatness and simmetry, and also verification the inverse square law for the distances normally used in therapy. Isodose curves were generated by the decrement lines method. (Author) [pt

Dosimetry characterization of the commercial CaF2 for beta radiation of 90Sr + 90Y

International Nuclear Information System (INIS)

Oliveira, Mercia L.; Caldas, Linda V.E.

2003-01-01

This work studies the dosimetric characteristics of the CaF 2 commercial dosimetry for detection of 90 Sr + 90 Y beta radiation for using in the calibration of flat and concave appliers. Were determined the repetitiousness and linearity of answers of the samples, and their calibration curves

Amorphous chalcogenide semiconductors for solid state dosimetric systems of high-energetic ionizing radiation

International Nuclear Information System (INIS)

Shpotyuk, O.

1997-01-01

The application possibilities of amorphous chalcogenide semiconductors use as radiation-sensitive elements of high-energetic (E > 1 MeV) dosimetric systems are analysed. It is shown that investigated materials are characterized by more wide region of registered absorbed doses and low temperature threshold of radiation information bleaching in comparison with well-known analogies based on coloring oxide glasses. (author)

Validation of the implementation of IMRT with three dosimetric methods of independent verification

International Nuclear Information System (INIS)

Tortosa Oliver, R. A.; Chinillach ferrando, N.; Alonso Arrizabalaga, S.; Campayo Esteban, J. M.; Morales Marco, J. C.; Soler Catalan, P.; Andreu Martinez, F. J.

2013-01-01

The TG119 is a simple and clear framework to verify the implementation of IMRT technique in a radiotherapy service. Verifications of this document recommended tests conducted with the three dosimetric methods listed above, allow to affirm that our Center is within the margins of tolerance considered suitable in the TG119 for the clinical implementation of IMRT. (Author)

Dosimetric and clinical results of three-dimensional conformal radiotherapy for locally recurrent nasopharyngeal carcinoma

International Nuclear Information System (INIS)

Zheng Xiaokang; Ma Jun; Chen Longhua; Xia Yunfei; Shi Yusheng

2005-01-01

Purpose: To assess the dosimetric and clinical results of three-dimensional conformal radiotherapy (3D CRT) for locally recurrent nasopharyngeal carcinoma (NPC). Methods: A total of 86 patients with locally recurrent NPC were retreated with 3D CRT. The median prescribed dose was 68 Gy with 2 Gy per fractionation. Dosimetric quality was evaluated with dose distribution in planning target volume (PTV) and specified organs at risk (OAR), dose conformity index (CI) and dose homogeneity index (HI). The actuarial rate of local failure-free (LFF), overall survival (OS) and major late toxicities (MLT) were estimated with Kaplan-Meier method. Multivariate analysis for prognosis was performed using the Cox regression proportional hazards model. Results: The mean dose to PTV averaged 66.8 Gy, and the dose to specified OAR was acceptable. The average value of CI and HI was 0.59 and 9.1%. The 5-year actuarial rate of LFF and OS was 71 and 40%, respectively. The 5-year actuarial incidence of MLT≥Grade 3 and ≥Grade 4 were 100 and 49%, respectively. The major prognostic factors were T stage and the size of gross tumor volume (GTV). Advanced T stage and large GTV volume were associated with poor LFF and OS and high risk of MLT. Conclusion: The dosimetric quality of 3D CRT for locally recurrent NPC is generally excellent. A relatively high local control was achieved with this technique. However, the incidence of late toxicities were not found to decrease as originally expected. Early diagnosis of the recurrence and reasonable definition of the target volume are crucial to achieve a better outcome

Examination of geometric and dosimetric accuracies of gated step-and-shoot intensity modulated radiation therapy

International Nuclear Information System (INIS)

Wiersma, R. D.; Xing, L.

2007-01-01

Due to the complicated technical nature of gated radiation therapy, electronic and mechanical limitations may affect the precision of delivery. The purpose of this study is to investigate the geometric and dosimetric accuracies of gated step-and-shoot intensity modulated radiation treatments (SS-IMRT). Unique segmental MLC plans are designed, which allow quantitative testing of the gating process. Both ungated and gated deliveries are investigated for different dose sizes, dose rates, and gating window times using a commercial treatment system (Varian Trilogy) together with a respiratory gating system [Varian Real-Time Position Management system]. Radiographic film measurements are used to study the geometric accuracy, where it is found that with both ungated and gated SS-IMRT deliveries the MLC leaf divergence away from planned is less than or equal to the MLC specified leaf tolerance value for all leafs (leaf tolerance being settable from 0.5-5 mm). Nevertheless, due to the MLC controller design, failure to define a specific leaf tolerance value suitable to the SS-IMRT plan can lead to undesired geometric effects, such as leaf motion of up to the maximum 5 mm leaf tolerance value occurring after the beam is turned on. In this case, gating may be advantageous over the ungated case, as it allows more time for the MLC to reach the intended leaf configuration. The dosimetric precision of gated SS-IMRT is investigated using ionization chamber methods. Compared with the ungated case, it is found that gating generally leads to increased dosimetric errors due to the interruption of the ''overshoot phenomena.'' With gating the average timing deviation for intermediate segments is found to be 27 ms, compared to 18 ms for the ungated case. For a plan delivered at 600 MU/min this would correspond to an average segment dose error of ∼0.27 MU and ∼0.18 MU for gated and ungated deliveries, respectively. The maximum dosimetric errors for individual intermediate segments are

Investigation on calibration parameter of mammography calibration facilities at MINT

International Nuclear Information System (INIS)

Asmaliza Hashim; Wan Hazlinda Ismail; Md Saion Salikin; Muhammad Jamal Md Isa; Azuhar Ripin; Norriza Mohd Isa

2004-01-01

A mammography calibration facility has been established in the Medical Physics Laboratory, Malaysian Institute for Nuclear Technology Research (MINT). The calibration facility is established at the national level mainly to provide calibration services for radiation measuring test instruments or test tools used in quality assurance programme in mammography, which is being implemented in Malaysia. One of the accepted parameters that determine the quality of a radiation beam is the homogeneity coefficient. It is determined from the values of the 1 st and 2 nd Half Value Layer (HVL). In this paper, the consistency of the mammography machine beam qualities that is available in MINT, is investigated and presented. For calibration purposes, five radiation qualities namely 23, 25, 28, 30 and 35 kV, selectable from the control panel of the X-ray machine is used. Important parameters that are set for this calibration facility are exposure time, tube current, focal spot to detector distance (FDD) and beam size at specific distance. The values of homogeneity coefficient of this laboratory for the past few years tip to now be presented in this paper. Backscatter radiations are also considered in this investigation. (Author)

Beam standardization of X radiation in computed tomography

International Nuclear Information System (INIS)

Maia, Ana F.; Caldas, Linda V.E.

2005-01-01

The ionization chamber used in dosimetric procedures in computed tomography beams (CT), is a cylindrical chamber, unsealed, with the sensitive length between 10 and 15 cm, named pencil ionization chamber. Because the doses involved in CT procedures are higher s than those in the procedures in radiology, it is very important to ensure the appropriate calibration of pencil ionization chambers and thus the accuracy of Dosimetric procedures. Recently, only the Calibration Laboratory, from Institute de Pesquisas Energeticas e Nucleares, had standards fields of conventional radiodiagnostic, but not arrived to include the energy range used in CT. In this work, will be shown the results obtained in standard field of radiodiagnostic - all qualities of radiodiagnostic of series RQR (direct beam) and RQA (attenuated beam) described in IEC 61267 norm - in an industrial X-ray equipment of the Calibration Laboratory. The recommended qualities for the calibration of TC chambers are the qualities RQA9 and RQR9. The other qualities will be used for calibration of other radiodiagnostic dosimeters and also for a larger study of the energy dependence of the pencil ionization chambers

Dosimetric evaluation of lithium carbonate (Li2CO3) as a dosemeter for gamma-radiation dose measurements.

Science.gov (United States)

Popoca, R; Ureña-Núñez, F

2009-06-01

This work reports the possibility of using lithium carbonate as a dosimetric material for gamma-radiation measurements. Carboxi-radical ions, CO(2)(-) and CO(3)(-), arise from the gamma irradiation of Li(2)CO(3), and these radical ions can be quantified by electron paramagnetic resonance (EPR) spectrometry. The EPR-signal response of gamma-irradiated lithium carbonate has been investigated to determine some dosimetric characteristics such as: peak-to-peak signal intensity versus gamma dose received, zero-dose response, signal fading, signal repeatability, batch homogeneity, dose rate effect and stability at different environmental conditions. Using the conventional peak-to-peak method of stable ion radicals, it is concluded that lithium carbonate could be used as a gamma dosemeter in the range of 3-100 Gy.

Dosimetric management during a criticality accident

International Nuclear Information System (INIS)

Lebaron-Jacobs, L.; Fottorino, R.; Racine, Y.; Miele, A.; Barbry, F.; Briot, F.; Distinguin, S.; Le Goff, J.P.; Berard, P.; Boisson, P.; Cavadore, D.; Lecoix, G.; Persico, M.H.; Rongier, E.; Challeton-De Vathaire, C.; Medioni, R.; Voisin, P.; Exmelin, L.; Flury-Herard, A.; Gaillard-Lecanu, E.; Lemaire, G.; Gonin, M.; Riasse, C.

2008-01-01

A working group from health occupational and clinical biochemistry services on French sites has issued essential data sheets on the guidelines to follow in managing the victims of a criticality accident. Since the priority of the medical management after a criticality accident is to assess the dose and the distribution of dose, some dosimetric investigations have been selected in order to provide a prompt response and to anticipate the final dose reconstruction. Comparison exercises between clinical biochemistry laboratories on French sites were carried out to confirm that each laboratory maintained the required operational methods for hair treatment and the appropriate equipment for 32 P activity in hair and 24 Na activity in blood measurements, and to demonstrate its ability to rapidly provide neutron dose estimates after a criticality accident. As a result, a relation has been assessed to estimate the dose and the distribution of dose according to the neutron spectrum following a criticality accident. (authors)

Dosimetric feature of natural biotite mineral

International Nuclear Information System (INIS)

Kalita, J.M.; Wary, G.

2015-01-01

A thermoluminescence (TL) study relevant to radiation dosimetry has been carried out for X-ray irradiated biotite mineral under un-annealed and different annealed (473, 573, 673 and 773 K) conditions. Some significant variations in dosimetric characteristics have been observed with annealing treatment. Due to generation of an additional shallow trap level at depth 0.78 eV in 673 and 773 K annealed samples, the dose response is found to improve. For the 773 K annealed sample, a linear dose response has been observed from 10 to 1100 mGy. The fading is ∼13 % within 5 d after irradiation and onward it reduces to 7 % up to 60 d. Reproducibility of this (773 K) sample is excellent. After 10 recycles the coefficient of variations in the results for the 60, 180 and 1000 mGy dose-irradiated samples are found to be 0.97, 1.31 and 1.03 %, respectively. The potential use of biotite as a natural X-ray dosemeter is discussed. (authors)

Dosimetric verification of a software for planning of radio therapeutical treatments

International Nuclear Information System (INIS)

Alfonso, R.; Huerta, U.; Alfonso, J.L.; Torres, M.

1995-01-01

A software for radiation treatment planning was recently developed by medical physicists at the Hermanos Ameijeiras Hospital in Havana. Selected locations in head and neck region were used to evaluate the reliability of calculated dose distributions in patients, taking as a reference the results of dosimetric measurements with TLD-700 powder in a RANDO type phantom. The different options is shown. Causes of discrepancies are analyzed and recommendations are made for the use of data acquisitions options

CT and MR image fusion using two different methods after prostate brachytherapy: impact on post-implant dosimetric assessment

International Nuclear Information System (INIS)

Servois, V.; El Khoury, C.; Lantoine, A.; Ollivier, L.; Neuenschwander, S.; Chauveinc, L.; Cosset, J.M.; Flam, T.; Rosenwald, J.C.

2003-01-01

To study different methods of CT and MR images fusion in patient treated by brachytherapy for localized prostate cancer. To compare the results of the dosimetric study realized on CT slices and images fusion. Fourteen cases of patients treated by 1125 were retrospectively studied. The CT examinations were realized with continuous section of 5 mm thickness, and MR images were obtained with a surface coil with contiguous section of 3 mm thickness. For the images fusion process, only the T2 weighted MR sequence was used. Two processes of images fusion were realized for each patient, using as reference marks the bones of the pelvis and the implanted seeds. A quantitative and qualitative appreciation was made by the operators, for each patient and both methods of images fusion. The dosimetric study obtained by a dedicated software was realized on CT images and all types of images fusion. The usual dosimetric indexes (D90, V 100 and V 150) were compared for each type of image. The quantitative results given by the software of images fusion showed a superior accuracy to the one obtained by the pelvic bony reference marks. Conversely, qualitative and quantitative results obtained by the operators showed a better accuracy of the images fusion based on iodine seeds. For two patients out of three presenting a D90 inferior to 145 Gy on CT examination, the D90 was superior to this norm when the dosimetry was based on images fusion, whatever the method used. The images fusion method based on implanted seed matching seems to be more precise than the one using bony reference marks. The dosimetric study realized on images fusion could allow to rectify possible errors, mainly due to difficulties in surrounding prostate contour delimitation on CT images. (authors)

Dosimetric Significance of the ICRP's Updated Guidance and Models, 1989-2003, and Implications for U.S. Federal Guidance

Energy Technology Data Exchange (ETDEWEB)

Leggett, R.W.

2003-09-10

Over the past two decades the U.S. Environmental Protection Agency (EPA) has issued a series of Federal guidance documents for the purpose of providing the Federal and State agencies with technical information to assist their implementation of radiation protection programs. Currently recommended dose conversion factors, annual limits on intake, and derived air concentrations for intake of radionuclides are tabulated in Federal Guidance Report No. 11 (FGR 11), published in 1988. The tabulations in FGR 11 were based on dosimetric quantities and biokinetic and dosimetric models of the International Commission on Radiological Protection (ICRP) developed for application to occupational exposures. Since the publication of FGR 11 the ICRP has revised some of its dosimetric quantities and its models for workers and has also developed age-specific models and dose conversion factors for intake of radionuclides by members of the public. This report examines the extent of the changes in the inhalation and ingestion dose coefficients of FGR 11 implied by the updated recommendations of the ICRP, both for workers and members of the public.

Dosimetric parameters for small field sizes using Fricke xylenol gel, thermoluminescent and film dosimeters, and an ionization chamber

International Nuclear Information System (INIS)

Guzman Calcina, Carmen S; Oliveira, Lucas N de; Almeida, Carlos E de; Almeida, Adelaide de

2007-01-01

Dosimetric measurements in small therapeutic x-ray beam field sizes, such as those used in radiosurgery, that have dimensions comparable to or smaller than the build-up depth, require special care to avoid incorrect interpretation of measurements in regions of high gradients and electronic disequilibrium. These regions occur at the edges of any collimated field, and can extend to the centre of small fields. An inappropriate dosimeter can result in an underestimation, which would lead to an overdose to the patient. We have performed a study of square and circular small field sizes of 6 MV photons using a thermoluminescent dosimeter (TLD), Fricke xylenol gel (FXG) and film dosimeters. PMMA phantoms were employed to measure lateral beam profiles (1 x 1, 3 x 3 and 5 x 5 cm 2 for square fields and 1, 2 and 4 cm diameter circular fields), the percentage depth dose, the tissue maximum ratio and the output factor. An ionization chamber (IC) was used for calibration and comparison. Our results demonstrate that high resolution FXG, TLD and film dosimeters agree with each other, and that an ionization chamber, with low lateral resolution, underestimates the absorbed dose. Our results show that, when planning small field radiotherapy, dosimeters with adequate lateral spatial resolution and tissue equivalence are required to provide an accurate basic beam data set to correctly calculate the absorbed dose in regions of electronic disequilibrium

Dosimetric confirmation of a software for the design of radiotherapy

International Nuclear Information System (INIS)

Alfonso, R.; Huerta, U.; Torres, M.; Alonso, J.L.

1995-01-01

A software for radiotherapy treatment has been recently designed by specialists in medical physics form Hermanos Ameijeiras Clinical and Surgical Hospital. Several locations in the distributions of dose calculations. The results of dosimetric measurements with TLD-700 powder in a human-like manikin were taken as reference. The different options available for the entry of patients shape data are explained. A comparison of the results of measurements with calculations, is presented. Causes of discrepancies are analyzed and recommendations regarding the usefulness of the different for the collection of data from patients are made

Dosimetry in radiodiagnosis. Individual irradiation card. Dosimetric application of electrets

International Nuclear Information System (INIS)

Lisbona, Albert.

1981-09-01

This study deals with a radiodiagnosis dosimetry, and contains two parts. First of all, the combination between a dosimetric data acquisition from an ionization chamber and a micro-computer allows the realization of individual irradiation card for a well established examination. The method is extensible to almost totality of radiological examinations. The second part describes the following of an original work about the application of electrets in radiodiagnosis dosimetry. At least a theorical study is shown; it takes account of different involving phenomena and allows a starting interpretation of experimental results [fr

Calibration Under Uncertainty.

Energy Technology Data Exchange (ETDEWEB)

Swiler, Laura Painton; Trucano, Timothy Guy

2005-03-01

This report is a white paper summarizing the literature and different approaches to the problem of calibrating computer model parameters in the face of model uncertainty. Model calibration is often formulated as finding the parameters that minimize the squared difference between the model-computed data (the predicted data) and the actual experimental data. This approach does not allow for explicit treatment of uncertainty or error in the model itself: the model is considered the %22true%22 deterministic representation of reality. While this approach does have utility, it is far from an accurate mathematical treatment of the true model calibration problem in which both the computed data and experimental data have error bars. This year, we examined methods to perform calibration accounting for the error in both the computer model and the data, as well as improving our understanding of its meaning for model predictability. We call this approach Calibration under Uncertainty (CUU). This talk presents our current thinking on CUU. We outline some current approaches in the literature, and discuss the Bayesian approach to CUU in detail.

Radioactivity measurement of 18F in 16 ml vials for calibration of radionuclide calibrators

International Nuclear Information System (INIS)

Wurdiyanto, Gatot; Marsoem, Pujadi; Candra, Hermawan; Wijono, Paidi

2012-01-01

Fluorine-18 is obtained through the reaction 18 O(p, n) 18 F using a cyclotron that is situated in a hospital in Jakarta. Standardization of the 18 F solution is performed by gamma spectrometry using calibration sources of 152 Eu, 60 Co and 137 Cs that have traceability to the International System of units (SI). The activities in the 16 ml vials that were used for calibrating the radionuclide calibrators were between 1 and 2 GBq, with expanded uncertainties of 3.8%. The expanded uncertainty, at a coverage factor of k=2, on the derived calibration factor for the radionuclide calibrator was 6.6%. - Highlights: ► PTKMR–BATAN as a NMI of Indonesia is required to have procedures to calibrate the radionuclide calibrators. ► Standardizations were carried out on a solution of [ 18 F]FDG using gamma spectrometry. ► The volume of 18 F solutions used was 16 ml because this is the volume often used in hospitals. ► The Secondary Standard ionization chamber is a CRC-7BT Capintec radionuclide calibrator. ► A dial setting for 16 ml of [ 18 F]FDG solution in a vial is 443 for the Capintec dose calibrator.

Safety Criteria and Standards for Bearing Capacity of Foundation

Directory of Open Access Journals (Sweden)

Yanlong Li

2017-01-01

Full Text Available This paper focuses on the evaluation standards of factor of safety for foundation stability analysis. The problem of foundation stability is analyzed via the methods of risk analysis of engineering structures and reliability-based design, and the factor of safety for foundation stability is determined by using bearing capacity safety-factor method (BSFM and strength safety-factor method (SSFM. Based on a typical example, the admissible factors of safety were calibrated with a target reliability index specified in relevant standards. Two safety criteria and their standards of bearing capacity of foundation for these two methods (BSFM and SSFM were established. The universality of the safety criteria and their standards for foundation reliability was verified based on the concept of the ratio of safety margin (RSM.

Internal dosimetric evaluation due to uranium aerosols; Evaluacion dosimetrica interna debido a aerosoles de uranio

Energy Technology Data Exchange (ETDEWEB)

Juan, Garcia Aguilar; Gustavo, Delgado Avila [Instituto Nacional de Investigaciones Nucleares, Salazar (Mexico)

1991-07-01

The present work has like object to carry out the internal dosimetric evaluation to the occupationally exposed personnel, due to the inhalation of aerosols of natural uranium and enriched in the pilot plant of nuclear fuel production of the National Institute of Nuclear Research.

Field calibration of cup anemometers

DEFF Research Database (Denmark)

Schmidt Paulsen, Uwe; Mortensen, Niels Gylling; Hansen, Jens Carsten

2007-01-01

A field calibration method and results are described along with the experience gained with the method. The cup anemometers to be calibrated are mounted in a row on a 10-m high rig and calibrated in the free wind against a reference cup anemometer. The method has been reported [1] to improve...... the statistical bias on the data relative to calibrations carried out in a wind tunnel. The methodology is sufficiently accurate for calibration of cup anemometers used for wind resource assessments and provides a simple, reliable and cost-effective solution to cup anemometer calibration, especially suited...

Characterization of different qualities in X-rays, for instruments calibration in radiological protection; Caracterizacion de diferentes calidades en rayos X, para calibracion de instrumentos en proteccion radiologica

Energy Technology Data Exchange (ETDEWEB)

Cejudo A, J.; Tovar M, V. M.; Vergara M, F., E-mail: jesus.cejudo@inin.gob.m [ININ, Departamento de Metrologia de Radiaciones Ionizantes, Laboratorio Secundario de Calibracion Dosimetrica, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico)

2010-09-15

In the Secondary Laboratory of Dosimetric Calibration in Mexico was realized the qualities characterization of the series X-rays RQR reported in the International Code of Practices in Dosimetry and Diagnostic Radiology No. 457, using attenuator filters of high purity aluminum and ionizing radiation equipment of inherent filtration of 4 mm Be with and emergent X-radiation beam of 40 grades. For the attenuation was used a geometric arrangement with three beam limiters and a monitor camera prepared on the established form in the mentioned technical report, and a spherical ionization chamber with collection volume of 3.6 cm{sup 3}, aligning its geometric center with the focus of X-rays tube to get that the incident radiation direction will be perpendicular to the ionization chamber. From the perspective of the radiological protection is important to know the X-radiation quality for the application dedicated to the instruments calibration and can to give to these the traceability to a reference laboratory, this way the quality combination and reference chamber can give as a result a procedure for the evaluation of the entrance in surface dose to estimate the dose orientate levels, specified in the basic standards of safety. (Author)

Calibration of Flick standards

International Nuclear Information System (INIS)

Thalmann, Ruedi; Spiller, Jürg; Küng, Alain; Jusko, Otto

2012-01-01

Flick standards or magnification standards are widely used for an efficient and functional calibration of the sensitivity of form measuring instruments. The results of a recent measurement comparison have shown to be partially unsatisfactory and revealed problems related to the calibration of these standards. In this paper the influence factors for the calibration of Flick standards using roundness measurement instruments are discussed in detail, in particular the bandwidth of the measurement chain, residual form errors of the device under test, profile distortions due to the diameter of the probing element and questions related to the definition of the measurand. The different contributions are estimated using simulations and are experimentally verified. Also alternative methods to calibrate Flick standards are investigated. Finally the practical limitations of Flick standard calibration are shown and the usability of Flick standards both to calibrate the sensitivity of roundness instruments and to check the filter function of such instruments is analysed. (paper)

Operational guidance for radiation emergency response organisations in Europe for using bio-dosimetric tools developed in EU MULTIBIODOSE project

International Nuclear Information System (INIS)

Jaworska, Alicja; Ainsbury, Elizabeth A.; Rothkamm, Kai; Fattibene, Paola; Lindholm, Carita; Oestreicher, Ursula; Romm, Horst; Thierens, Hubert; Vral, Anne; Trompier, Francois; Voisin, Philippe; Woda, Clemens; Wojcik, Andrzej

2015-01-01

In the event of a large-scale radiological emergency, the triage of individuals according to their degree of exposure forms an important initial step of the accident management. Although clinical signs and symptoms of a serious exposure may be used for radiological triage, they are not necessarily radiation specific and can lead to a false diagnosis. Biodosimetry is a method based on the analysis of radiation-induced changes in cells of the human body or in portable electronic devices and enables the unequivocal identification of exposed people who should receive medical treatment. The MULTIBIODOSE (MBD) consortium developed and validated several bio-dosimetric assays and adapted and tested them as tools for biological dose assessment in a mass-casualty event. Different bio-dosimetric assays were validated against the 'gold standard' of biological dosimetry-the dicentric assay. The assays were harmonised in such a way that, in an emergency situation, they can be run in parallel in a network of European laboratories. The aim of this guidance is to give a concise overview of the developed bio-dosimetric tools as well as how and when they can be used in an emergency situation. (authors)

Dosimetric characteristics of LKB:Cu,P solid TL detector

International Nuclear Information System (INIS)

Hashim, S.; Alajerami, Y.S.M.; Ghoshal, S.K.; Saleh, M.A.; Saripan, M.I.; Kadir, A.B.A.; Bradley, D.A.; Alzimami, K.

2014-01-01

The dosimetric characteristics of newly developed borate glass dosimeter modified with lithium and potassium carbonate (LKB) and co-doped with CuO and NH 4 H 2 PO 4 are reported. Broad peaks in the absence of any sharp peak confirms the amorphous nature of the prepared glass. A simple glow curve of Cu doped sample is observed with a single prominent peak (T m ) at 220 °C. The TL intensity response shows an enhancement of ∼100 times due to the addition of CuO (0.1 mol%) to LKB compound. A further enhancement of the intensity by a factor of 3 from the addition of 0.25 mol% NH 4 H 2 PO 4 as a co-dopant impurity is attributed to the creation of extra electron traps with consequent increase in energy transfer of radiation recombination centers. The TL yield performance of LKB:Cu,P with Z eff ≈8.92 is approximately seventeen times less sensitive compared to LiF:Mg,Ti (TLD-100). The proposed dosimeter shows good linearity up to 10 3 Gy, minimal fading and photon energy independence. These attractive features offered by our dosimeter is expected to pave the way towards dosimetric applications. - Highlights: • The NH 4 H 2 PO 4 impurities are cross linked with the CuO defect. • The addition of NH 4 H 2 PO 4 as a co-dopant improved the TL intensity by a factor of 3. • The proposed dosimeter shows good linearity up to 10 3 Gy. • Minimal fading and photon energy independence were observed

Dosimetric Analysis of Respiratory-Gated Radiotherapy for Hepatocellular Carcinoma

International Nuclear Information System (INIS)

Xi Mian; Zhang Li; Liu Mengzhong; Deng Xiaowu; Huang Xiaoyan; Liu Hui

2011-01-01

The purpose of this study was to define individualized internal target volume (ITV) for hepatocellular carcinoma (HCC) using 4D computed tomography (4DCT), and to determine the geometric and dosimetric benefits of respiratory gating. Gross tumor volumes (GTVs) were contoured on 10 respiratory phases of 4DCT images for 12 patients with HCC. Three treatment plans were prepared using different planning target volumes (PTVs): (1) PTV 3D , derived from a single helical clinical target volume (CTV) plus conventional margins; (2) PTV 10phases , derived from ITV 10phases , which encompassed all 10 CTVs plus an isotropic margin of 0.8 cm; (3) PTV gating , derived from ITV gating , which encompassed three CTVs within gating-window at end-expiration plus an isotropic margin of 0.8 cm. The PTV 3D was the largest volume for all patients. The ITV-based plans and gating plans spared more normal tissues than 3D plans, especially the liver. Without increasing normal tissue complication probability of the 3D plans, the ITV-based plans allowed for increasing the calculated dose from 50.8 Gy to 54.7 Gy on average, and the gating plans could further escalate the dose to 58.5 Gy. Compared with ITV-based plans, the dosimetric gains with gating plan strongly correlated with GTV mobility in the craniocaudal direction. The ITV-based plans can ensure target coverage with less irradiation of normal tissues compared with 3D plans. Respiratory-gated radiotherapy can further reduce the target volumes to spare more surrounding tissues and allow dose escalation, especially for patients with tumor mobility >1 cm.

Characterization of natural topaz for dosimetric applications in the therapeutic range

International Nuclear Information System (INIS)

Souza, Divanizia do Nascimento

2002-01-01

The thermoluminescence (TL) and the thermally stimulated exoelectron emission of Brazilian natural topaz samples from Minas Gerais were analysed aiming the use of this mineral for dosimetric applications. Topaz is an aluminium fluorosilicate with a fairly constant chemical composition of Al 2 SiO 4 (F,OH) 2 . The major variation in the structure among different samples is related to the OH/F concentration ratio. In the present work, samples cut from rolled pebbles, powdered samples and composites were used. The composites (dosimeters) were prepared with powdered topaz embedded in powdered Teflon or glass. The dosimetric characterization of the composites showed that the dosimeters present a linear response in the range of therapeutic doses, slow isothermic fading and a strong TL dependence with radiation energy. The TL was also combined with the X-ray diffraction, infrared and Raman spectroscopic techniques to identify the charge carrier traps and those of the recombination centres, that are essential aspects to understand the processes of light emission in natural colourless topaz. It was observed that the main charge trapping centers in the topaz are due to various OH-related defects, and that the thermal treatments can change the concentration of the recombination centers. Implantations with chromium, aluminium and iron ions into colourless samples were performed, and they were efficient to produce TL modifications in topaz. (author)

Synthesis Polarimetry Calibration

Science.gov (United States)

Moellenbrock, George

2017-10-01

Synthesis instrumental polarization calibration fundamentals for both linear (ALMA) and circular (EVLA) feed bases are reviewed, with special attention to the calibration heuristics supported in CASA. Practical problems affecting modern instruments are also discussed.

Comparison of the dosimetric parameters in linear accelerators with flattening filter-free (FFF) and flattening filter (FF)

International Nuclear Information System (INIS)

Souza, Anderson S.; Rostelato, Maria Elisa C.M.; Zeituni, Carlos A.; Moura, Eduardo S.; Rodrigues, Bruna T.; Souza, Daiane C.; Tiezzi, Rodrigo; Souza, Carla D.; Melo, Emerson R.; Camargo, Anderson R.; Batista, Talita Q.

2015-01-01

This paper discusses the main features associated with the dosimetric parameters between FFF and FF Linacs. A set of Varian TrueBeam Linac and Varian 23EX dosimetric measurements was acquired to perform the experimental measurements. The dose measurements were carried out in a water Blue phantom, with a waterproof ionization chambers: farmer ionization chamber (0.6 cm 3 ) and Exradin A1SL(0.053 cm 3 ) , for fields 5 x 5, 8 x 8, 10 x 10, 15 x 15, 30 x 30 cm 2 . The 6 MV FFF and FF was the energy used in this work. Percent Depth Dose (PDD) was the dosimetric parameters evaluated using a fixed Source Surface Distance of 100 cm. One depth were applied for the measurements, 10 cm (central axis) from the water surface. The 6 MV FFF showed less penetrating than the 6 MV FF. This is due to the removal flattening filter causes more lower energy photons on the central axis. The field sizes were equivalent for both FFF and FF. The main advantage in operate linear accelerators without flattening filter is due to the high doses rates delivered during the treatment. High doses rates could reduce the patient treatment time and may be beneficial for some treatment techniques such as IMRT and SRT. (author)

Sandia WIPP calibration traceability

Energy Technology Data Exchange (ETDEWEB)

Schuhen, M.D. [Sandia National Labs., Albuquerque, NM (United States); Dean, T.A. [RE/SPEC, Inc., Albuquerque, NM (United States)

1996-05-01

This report summarizes the work performed to establish calibration traceability for the instrumentation used by Sandia National Laboratories at the Waste Isolation Pilot Plant (WIPP) during testing from 1980-1985. Identifying the calibration traceability is an important part of establishing a pedigree for the data and is part of the qualification of existing data. In general, the requirement states that the calibration of Measuring and Test equipment must have a valid relationship to nationally recognized standards or the basis for the calibration must be documented. Sandia recognized that just establishing calibration traceability would not necessarily mean that all QA requirements were met during the certification of test instrumentation. To address this concern, the assessment was expanded to include various activities.

Sandia WIPP calibration traceability

International Nuclear Information System (INIS)

Schuhen, M.D.; Dean, T.A.

1996-05-01

This report summarizes the work performed to establish calibration traceability for the instrumentation used by Sandia National Laboratories at the Waste Isolation Pilot Plant (WIPP) during testing from 1980-1985. Identifying the calibration traceability is an important part of establishing a pedigree for the data and is part of the qualification of existing data. In general, the requirement states that the calibration of Measuring and Test equipment must have a valid relationship to nationally recognized standards or the basis for the calibration must be documented. Sandia recognized that just establishing calibration traceability would not necessarily mean that all QA requirements were met during the certification of test instrumentation. To address this concern, the assessment was expanded to include various activities

Amorphous chalcogenide semiconductors for solid state dosimetric systems of high-energetic ionizing radiation

Energy Technology Data Exchange (ETDEWEB)

Shpotyuk, O. [Pedagogical University, Czestochowa (Poland)]|[Institute of Materials, Lvov (Ukraine)

1997-12-31

The application possibilities of amorphous chalcogenide semiconductors use as radiation-sensitive elements of high-energetic (E > 1 MeV) dosimetric systems are analysed. It is shown that investigated materials are characterized by more wide region of registered absorbed doses and low temperature threshold of radiation information bleaching in comparison with well-known analogies based on coloring oxide glasses. (author). 16 refs, 1 tab.

Empirical component model to predict the overall performance of heating coils: Calibrations and tests based on manufacturer catalogue data

International Nuclear Information System (INIS)

Ruivo, Celestino R.; Angrisani, Giovanni

2015-01-01

Highlights: • An empirical model for predicting the performance of heating coils is presented. • Low and high heating capacity cases are used for calibration. • Versions based on several effectiveness correlations are tested. • Catalogue data are considered in approach testing. • The approach is a suitable component model to be used in dynamic simulation tools. - Abstract: A simplified methodology for predicting the overall behaviour of heating coils is presented in this paper. The coil performance is predicted by the ε-NTU method. Usually manufacturers do not provide information about the overall thermal resistance or the geometric details that are required either for the device selection or to apply known empirical correlations for the estimation of the involved thermal resistances. In the present work, heating capacity tables from the manufacturer catalogue are used to calibrate simplified approaches based on the classical theory of heat exchangers, namely the effectiveness method. Only two reference operating cases are required to calibrate each approach. The validity of the simplified approaches is investigated for a relatively high number of operating cases, listed in the technical catalogue of a manufacturer. Four types of coils of three sizes of air handling units are considered. A comparison is conducted between the heating coil capacities provided by the methodology and the values given by the manufacturer catalogue. The results show that several of the proposed approaches are suitable component models to be integrated in dynamic simulation tools of air conditioning systems such as TRNSYS or EnergyPlus

Dosimetry of Sr-90 ophthalmic applicators

International Nuclear Information System (INIS)

Reft, C.S.; Kuchnir, F.T.; Rosenberg, I.; Myrianthopoulos, L.C.

1990-01-01

Sr-90 ophthalmic applicators are commonly used for the treatment of superficial eye disorders. Although a variety of dosimetric devices such as film, thermoluminescent dosimeters (TLD's), ion chambers, and radiochromic foils have been used to measure the peak dose at the applicator surface, there is no internationally agreed upon calibration procedure. Recently, large discrepancies among calibrations of the same applicator at three institutions have been reported. Here we describe a technique to obtain the peak dose rate at the applicator surface using LiF TLD's. The technique can be used for the calibration of flat as well as curved surface applicators. Results for two flat and three concave applicators are presented. Our measurement of the surface dose rate for one of the flat applicators is compared with those obtained by four other institutions, each using different dosimetric devices

POLCAL - POLARIMETRIC RADAR CALIBRATION

Science.gov (United States)

Vanzyl, J.

1994-01-01

Calibration of polarimetric radar systems is a field of research in which great progress has been made over the last few years. POLCAL (Polarimetric Radar Calibration) is a software tool intended to assist in the calibration of Synthetic Aperture Radar (SAR) systems. In particular, POLCAL calibrates Stokes matrix format data produced as the standard product by the NASA/Jet Propulsion Laboratory (JPL) airborne imaging synthetic aperture radar (AIRSAR). POLCAL was designed to be used in conjunction with data collected by the NASA/JPL AIRSAR system. AIRSAR is a multifrequency (6 cm, 24 cm, and 68 cm wavelength), fully polarimetric SAR system which produces 12 x 12 km imagery at 10 m resolution. AIRSTAR was designed as a testbed for NASA's Spaceborne Imaging Radar program. While the images produced after 1991 are thought to be calibrated (phase calibrated, cross-talk removed, channel imbalance removed, and absolutely calibrated), POLCAL can and should still be used to check the accuracy of the calibration and to correct it if necessary. Version 4.0 of POLCAL is an upgrade of POLCAL version 2.0 released to AIRSAR investigators in June, 1990. New options in version 4.0 include automatic absolute calibration of 89/90 data, distributed target analysis, calibration of nearby scenes with calibration parameters from a scene with corner reflectors, altitude or roll angle corrections, and calibration of errors introduced by known topography. Many sources of error can lead to false conclusions about the nature of scatterers on the surface. Errors in the phase relationship between polarization channels result in incorrect synthesis of polarization states. Cross-talk, caused by imperfections in the radar antenna itself, can also lead to error. POLCAL reduces cross-talk and corrects phase calibration without the use of ground calibration equipment. Removing the antenna patterns during SAR processing also forms a very important part of the calibration of SAR data. Errors in the

Dosimetric measurement of the disintegration rate of fission products

International Nuclear Information System (INIS)

Solymosi, J.; Nagy, L.G.; Zagyvai, P.

1992-01-01

Investigations on the disintegration rate of fission products of 238 U and 239 Pu are presented. The intensity of the β-and γ-radiation of fission products were measured continously in an interval of 1-1300 hours following the fission, offering the possibility for determining the general and specific characteristics of the individual fission products. A universal measuring procedure was elaborated for the rapid in situ determination of the dosimetric features of fission products, which is suitable for the accurate evaluation and prediction of external absorbed dose even in case of fission products of various origin and unknown composition. (author) 6 refs.; 7 figs.; 1 tab

Radioecological and dosimetric consequences of Chernobyl accident in France

International Nuclear Information System (INIS)

Renaud, Ph.; Beaugelin, K.; Maubert, H.; Ledenvic, Ph.

1997-01-01

After ten years and the taking in account of numerous data, it can be affirmed that the dosimetric consequences of Chernobyl accident will have been limited in France. for the period 1986-2046, the individual middle efficient dose commitment, for the area the most reached by depositing is inferior to 1500 μSv, that represents about 1% of middle natural exposure in the same time. but mountains and forests can have more important surface activities than in plain. Everywhere else, it can be considered that the effects of Chernobyl accident are disappearing. the levels of cesium 137 are now often inferior to what they were before the accident. (N.C.)

SESAME: a software tool for the numerical dosimetric reconstruction of radiological accidents involving external sources and its application to the accident in Chile in December 2005.

Science.gov (United States)

Huet, C; Lemosquet, A; Clairand, I; Rioual, J B; Franck, D; de Carlan, L; Aubineau-Lanièce, I; Bottollier-Depois, J F

2009-01-01

Estimating the dose distribution in a victim's body is a relevant indicator in assessing biological damage from exposure in the event of a radiological accident caused by an external source. This dose distribution can be assessed by physical dosimetric reconstruction methods. Physical dosimetric reconstruction can be achieved using experimental or numerical techniques. This article presents the laboratory-developed SESAME--Simulation of External Source Accident with MEdical images--tool specific to dosimetric reconstruction of radiological accidents through numerical simulations which combine voxel geometry and the radiation-material interaction MCNP(X) Monte Carlo computer code. The experimental validation of the tool using a photon field and its application to a radiological accident in Chile in December 2005 are also described.

The evolution of root-zone moisture capacities after deforestation : A step towards hydrological predictions under change?

NARCIS (Netherlands)

Nijzink, R.C.; Hutton, Christopher; Pechlivanidis, Ilias; Capell, René; Arheimer, Berit; Freer, Jim; Han, Dawei; Wagener, Thorsten; McGuire, Kevin; Savenije, H.H.G.; Hrachowitz, M.

2016-01-01

The core component of many hydrological systems, the moisture storage capacity available to vegetation, is impossible to observe directly at the catchment scale and is typically treated as a calibration parameter or obtained from a priori available soil characteristics combined with estimates of

Dosimetric approaches: pregnancy and lactation

International Nuclear Information System (INIS)

Rojo, Ana M.

2001-01-01

The female nuclear medicine patient is of special concern to the evaluation of radiation dose since radiation protection point of view: a)- The females overall body size and organ sizes are generally smaller than those of her male counterpart (thus her radiation doses will be higher, given the same amounts of administered activity and similar biokinetics), the effective doses could be 25 per cent higher than a man; b)- Female gonads are inside the body instead of outside and are near several organs often important as source organs in internal dosimetry; female gonads doses could be up to 10 or 30 higher than male gonads (usually 3 order); c)- Risk of breast cancer is significantly higher among females than males; d)- During the pregnancy due to placental transfer of radiopharmaceuticals or radiation exposure from the urinary bladder the embryo/fetus could receive doses that must be avoid; e)- In the case of nursing infant is of special concern in such an analysis to determine the interruption period to avoid doses in the nursing infant. The dosimetric approaches to take account to assess internal doses in the pregnant woman and during the breast feeding are discussed. (author)

Dosimetric evaluation of a MOSFET detector for clinical application in photon therapy.

Science.gov (United States)

Kohno, Ryosuke; Hirano, Eriko; Nishio, Teiji; Miyagishi, Tomoko; Goka, Tomonori; Kawashima, Mitsuhiko; Ogino, Takashi

2008-01-01

Dosimetric characteristics of a metal oxide-silicon semiconductor field effect transistor (MOSFET) detector are studied with megavoltage photon beams for patient dose verification. The major advantages of this detector are its size, which makes it a point dosimeter, and its ease of use. In order to use the MOSFET detector for dose verification of intensity-modulated radiation therapy (IMRT) and in-vivo dosimetry for radiation therapy, we need to evaluate the dosimetric properties of the MOSFET detector. Therefore, we investigated the reproducibility, dose-rate effect, accumulated-dose effect, angular dependence, and accuracy in tissue-maximum ratio measurements. Then, as it takes about 20 min in actual IMRT for the patient, we evaluated fading effect of MOSFET response. When the MOSFETs were read-out 20 min after irradiation, we observed a fading effect of 0.9% with 0.9% standard error of the mean. Further, we applied the MOSFET to the measurement of small field total scatter factor. The MOSFET for dose measurements of small field sizes was better than the reference pinpoint chamber with vertical direction. In conclusion, we assessed the accuracy, reliability, and usefulness of the MOSFET detector in clinical applications such as pinpoint absolute dosimetry for small fields.

Calibrating nacelle lidars

Energy Technology Data Exchange (ETDEWEB)

Courtney, M.

2013-01-15

Nacelle mounted, forward looking wind lidars are beginning to be used to provide reference wind speed measurements for the power performance testing of wind turbines. In such applications, a formal calibration procedure with a corresponding uncertainty assessment will be necessary. This report presents four concepts for performing such a nacelle lidar calibration. Of the four methods, two are found to be immediately relevant and are pursued in some detail. The first of these is a line of sight calibration method in which both lines of sight (for a two beam lidar) are individually calibrated by accurately aligning the beam to pass close to a reference wind speed sensor. A testing procedure is presented, reporting requirements outlined and the uncertainty of the method analysed. It is seen that the main limitation of the line of sight calibration method is the time required to obtain a representative distribution of radial wind speeds. An alternative method is to place the nacelle lidar on the ground and incline the beams upwards to bisect a mast equipped with reference instrumentation at a known height and range. This method will be easier and faster to implement and execute but the beam inclination introduces extra uncertainties. A procedure for conducting such a calibration is presented and initial indications of the uncertainties given. A discussion of the merits and weaknesses of the two methods is given together with some proposals for the next important steps to be taken in this work. (Author)

Dosimetric predictors of hypothyroidism in oropharyngeal cancer patients treated with intensity-modulated radiation therapy

International Nuclear Information System (INIS)

Chyan, Arthur; Chen, Josephine; Shugard, Erin; Lambert, Louise; Quivey, Jeanne M; Yom, Sue S

2014-01-01

Radiation to the neck has long been associated with an elevated risk of hypothyroidism development. The goal of the present work is to define dosimetric predictors of hypothyroidism in oropharyngeal cancer (OPC) patients treated with intensity-modulated radiation therapy. Data for 123 patients, with a median follow up of 4.6 years, were retrospectively analyzed. Patients with elevated thyroid-stimulating hormone levels or with a clinical diagnosis were categorized as hypothyroid. Patient demographic parameters, thyroid volume, mean thyroid dose, the percent of thyroid volume receiving minimum specified dose levels (VxxGy), and the absolute thyroid volume spared from specified dose levels (VSxxGy) were analyzed. Normal-tissue complication probability (NTCP) was also calculated using several recently published models. Thyroid volume and many radiation dosimetric parameters were statistically different in the hypothyroid group. For the patients with initial thyroid volumes of 8 cc or greater, several dosimetric parameters were found to define subgroups at statistically significant lower risk of developing hypothyroidism. Patients with VS45 Gy of at least 3 cc, VS50 Gy at least 5 cc, VS50 Gy at least 6 cc, V50 Gy below 45%, V50 Gy below 55%, or mean thyroid dose below 49 Gy had a 28-38% estimated risk of hypothyroidism at 3 years compared to a 55% risk for the entire study group. Patients with a NTCP of less than 0.75 or 0.8, calculated using recently published models, were also observed to have a lower risk of developing hypothyroidism. Based on long-term follow up data for OPC patients treated with IMRT, we recommend plan optimization objectives to reduce the volume of thyroid receiving over 45 Gy to significantly decrease the risk of developing hypothyroidism. The online version of this article (doi:10.1186/s13014-014-0269-4) contains supplementary material, which is available to authorized users

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

International Nuclear Information System (INIS)

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

2008-01-01

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

Calibrated Properties Model

International Nuclear Information System (INIS)

Ahlers, C.; Liu, H.

2000-01-01

The purpose of this Analysis/Model Report (AMR) is to document the Calibrated Properties Model that provides calibrated parameter sets for unsaturated zone (UZ) flow and transport process models for the Yucca Mountain Site Characterization Project (YMP). This work was performed in accordance with the ''AMR Development Plan for U0035 Calibrated Properties Model REV00. These calibrated property sets include matrix and fracture parameters for the UZ Flow and Transport Model (UZ Model), drift seepage models, drift-scale and mountain-scale coupled-processes models, and Total System Performance Assessment (TSPA) models as well as Performance Assessment (PA) and other participating national laboratories and government agencies. These process models provide the necessary framework to test conceptual hypotheses of flow and transport at different scales and predict flow and transport behavior under a variety of climatic and thermal-loading conditions

Dosimetric effects of rotational output variation and x-ray target degradation on helical tomotherapy plans

International Nuclear Information System (INIS)

Staton, Robert J.; Langen, Katja M.; Kupelian, Patrick A.; Meeks, Sanford L.

2009-01-01

In this study, two potential sources of IMRT delivery error have been identified for helical tomotherapy delivery using the HiART system (TomoTherapy, Inc., Madison, WI): Rotational output variation and target degradation. The HiArt system is known to have output variation, typically about ±2%, due to the absence of a dose servo system. On the HiArt system, x-ray target replacement is required approximately every 10-12 months due to target degradation. Near the end of target life, the target thins and causes a decrease in the beam energy and a softening of the beam profile at the lateral edges of the beam. The purpose of this study is to evaluate the dosimetric effects of rotational output variation and target degradation by modeling their effects and incorporating them into recalculated treatment plans for three clinical scenarios: Head and neck, partial breast, and prostate. Models were created to emulate both potential sources of error. For output variation, a model was created using a sine function to match the amplitude (±2%), frequency, and phase of the measured rotational output variation data. A second model with a hypothetical variation of ±7% was also created to represent the largest variation that could exist without violating the allowable dose window in the delivery system. A measured beam profile near the end of target life was used to create a modified beam profile model for the target degradation. These models were then incorporated into the treatment plan by modifying the leaf opening times in the delivery sinogram. A new beam model was also created to mimic the change in beam energy seen near the end of target life. The plans were then calculated using a research version of the PLANNED ADAPTIVE treatment planning software from TomoTherapy, Inc. Three plans were evaluated in this study: Head and neck, partial breast, and prostate. The D 50 of organs at risk, the D 95 for planning target volumes (PTVs), and the local dose difference were used to

Dosimetry characterization of the commercial CaF{sub 2} for beta radiation of {sup 90}Sr + {sup 90}Y; Caracterizacao dosimetrica de CaF{sub 2} comercial para radiacao beta de {sup 90}Sr + {sup 90}Y

Energy Technology Data Exchange (ETDEWEB)

Oliveira, Mercia L.; Caldas, Linda V.E. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)], e-mail: mlolivei@ipen.br, e-mail: lcaldas@ipen.br

2003-07-01

This work studies the dosimetric characteristics of the CaF{sub 2} commercial dosimetry for detection of {sup 90}Sr + {sup 90}Y beta radiation for using in the calibration of flat and concave appliers. Were determined the repetitiousness and linearity of answers of the samples, and their calibration curves.

A Combined Tissue Kinetics and Dosimetric Model of Respiratory Tissue Exposed to Radiation

Energy Technology Data Exchange (ETDEWEB)

John R. Ford

2005-11-01

Existing dosimetric models of the radiation response of tissues are essentially static. Consideration of changes in the cell populations over time has not been addressed realistically. For a single acute dose this is not a concern, but for modeling chronic exposures or fractionated acute exposures, the natural turnover and progression of cells could have a significant impact on a variety of endpoints. This proposal addresses the shortcomings of current methods by combining current dose-based calculation techniques with information on the cell turnover for a model tissue. The proposed model will examine effects at the single-cell level for an exposure of a section of human bronchiole. The cell model will be combined with Monte Carlo calculations of doses to cells and cell nuclei due to varying dose-rates of different radiation qualities. Predictions from the model of effects on survival, apoptosis rates, and changes in the number of cycling and differentiating cells will be tested experimentally. The availability of dynamic dosimetric models of tissues at the single-cell level will be useful for analysis of low-level radiation exposures and in the development of new radiotherapy protocols.

Fast neutron irradiation effects on CR-39 nuclear track detector for dosimetric applications

International Nuclear Information System (INIS)

Kader, M.H.

2005-01-01

The effect of neutron irradiation on the dosimetric properties of CR-39 solid-state nuclear track detector have been investigated. CR-39 samples were irradiated with neutrons of energies follow a Maxwellian distribution centered about 2 MeV. These samples were irradiated with different doses in the range 0.1-1 Sv. The background and track density were measured as a function of etching time. In addition, the dependence of sensitivity of CR-39 detector on the neutrons dose has been investigated. The results show that the Sensitivity started to increase at 0.4 Sv neutrons dose, so this sample were chosen to be a subject for further study to investigate the effect of gamma dose on its properties. The sample irradiated with 0.4 Sv were exposed to different doses of gamma rays at levels between 10 and 80 kGy. The effect of gamma doses on the bulk etching rate VB, the track diameter and the sensitivity of the CR-39 samples was investigated. The results show that the dosimetric properties of CR-39 SSNTD are greatly affected by both neutron and gamma irradiation

Critical assessment of the deposition based dosimetric technique for radon/thoron decay products

International Nuclear Information System (INIS)

Mayya, Y.S.

2010-01-01

Inhalation doses due to radon ( 222 Rn) and thoron ( 220 Rn) are predominantly contributed by their decay products and not due to the gases themselves. Decay product measurements are being carried out essentially by either short-term active measurement like by air-sampling on a substrate followed by alpha or beta counting or by continuous active monitoring techniques based on silicon barrier detector. However, due to non-availability of satisfactory passive measurement techniques for the progeny species, it has been a usual practice to estimate the long time averaged progeny concentration from measured gas concentration using an assumed equilibrium factor. To be accurate, one is required to measure the equilibrium factor in situ along with the gas concentration. This being not practical, the assigned equilibrium factor (0.4 for indoor and 0.8 for outdoor for 222 Rn) approach has been an inevitable, though uncertain, part of the dosimetric strategies in both occupational and public domains. Further, in the case of thoron decay products however, equilibrium factor is of far more questionable validity. Thus, there is a need to shift from gas based dosimetric paradigm to that based on direct detection of progeny species

Dosimetric quality control in radiotherapy using TLD methodology

International Nuclear Information System (INIS)

Saravi, M.C.; Kessler, C.; Alvarez, P.E.; Feld, D.B.

2002-01-01

In the frame of the IAEA Co-ordinated Research Project 'Development of a Quality Assurance Program for Radiation Therapy Dosimetry in Developing Countries' a Dosimetric Quality Control Group was set up in Argentina in 1996, to develop a program in order to improve radiotherapy in the country. Nowadays, this Group, briefly called External Audit Group (EAG), is composed by the national Secondary Standard Dosimetry Laboratory (SSDL), which has the responsibility for dose determinations, traceability to international dosimetry chain and TLD measurements, and two Medical Physicists from CNEA who are working at the Oncology Hospital 'Marie Curie' in Buenos Aires. The present paper reports the activities performed by the EAG with external high energy photon beams in reference conditions and the results of two pilot studies on cobalt 60 beams in non-reference conditions. The first step of the program was to update the existing data base about the radiotherapy centres operating in the country. A form was sent to each of them in order to obtain basic information about their staff, number and type of treatment machines, brachytherapy sources, measuring devices, beam calibration, treatment planning system, simulator and other relevant data. 90 radiotherapy centres were registered in the EAG data base. Forms were completed by 75/90 centres. There are nowadays 69 cobalt 60 units and 42 LINACs operating in the country (18/42 LINACs producing high energy X ray and electron beams). EAG deals with measurements performed with mailed TLD irradiated at radiotherapy centres. Internal quality control on our TLD system is made during each audit by means of reference capsules irradiated by IAEA; external controls consist in blind tests performed by IAEA once a year. The correction factor, K en , determined at our SSDL for high energy X-rays was checked with the collaboration of IAEA and Prague National Radiation Protection Institute (PNRPI) by means of a blind test. Results for 4 MV, 6 MV

When high working memory capacity is and is not beneficial for predicting nonlinear processes.

Science.gov (United States)

Fischer, Helen; Holt, Daniel V

2017-04-01

Predicting the development of dynamic processes is vital in many areas of life. Previous findings are inconclusive as to whether higher working memory capacity (WMC) is always associated with using more accurate prediction strategies, or whether higher WMC can also be associated with using overly complex strategies that do not improve accuracy. In this study, participants predicted a range of systematically varied nonlinear processes based on exponential functions where prediction accuracy could or could not be enhanced using well-calibrated rules. Results indicate that higher WMC participants seem to rely more on well-calibrated strategies, leading to more accurate predictions for processes with highly nonlinear trajectories in the prediction region. Predictions of lower WMC participants, in contrast, point toward an increased use of simple exemplar-based prediction strategies, which perform just as well as more complex strategies when the prediction region is approximately linear. These results imply that with respect to predicting dynamic processes, working memory capacity limits are not generally a strength or a weakness, but that this depends on the process to be predicted.

Primary calibration in acoustics metrology

International Nuclear Information System (INIS)

Milhomem, T A Bacelar; Soares, Z M Defilippo

2015-01-01

SI unit in acoustics is realized by the reciprocity calibrations of laboratory standard microphones in pressure field, free field and diffuse field. Calibrations in pressure field and in free field are already consolidated and the Inmetro already done them. Calibration in diffuse field is not yet consolidated, however, some national metrology institutes, including Inmetro, are conducting researches on this subject. This paper presents the reciprocity calibration, the results of Inmetro in recent key comparisons and the research that is being developed for the implementation of reciprocity calibration in diffuse field

The dilemma of parotid gland and pharyngeal constrictor muscles preservation—Is daily online image guidance required? A dosimetric analysis

Energy Technology Data Exchange (ETDEWEB)

Duffy, Olivia; Forde, Elizabeth; Leech, Michelle, E-mail: leechm@tcd.ie

2017-04-01

With margin reduction common in head and neck radiotherapy, it is critical that the dosimetric effects of setup deviations are quantified. With past studies focusing on the quantification of positional and volumetric changes of organs at risk (OARs), this study aimed to measure the dose delivered to these the parotid gland (PG) and pharyngeal constrictor muscles (PCMs) using cone beam computed tomography (CBCT). Furthermore, this investigation sought to establish a potential time trend of change in dose delivered to target volumes secondary to ascertaining the need for daily image guidance (IG) to reduce the dose burden to these important OARs. Intensity modulated radiotherapy (IMRT) plans for 5 locally advanced head and neck patients' plans were created and mapped to weekly CBCTs. Each plan was recalculated without heterogeneity correction allowing for dosimetric comparison. Dosimetric endpoints recorded to assess the effect of positional variation were as per ICRU 83 and included D{sub 95} and D{sub 98} for the target volumes, mean dose (MD) and V{sub 30} {sub Gy} for the PGs, and V{sub 50} {sub Gy} and MD for the PCMs. Results were deemed statistically significant if p < 0.05. No significant time trends were established for these OARs. A significant decrease in V{sub 50} {sub Gy} was observed for all PCMs (p < 0.001) on all CBCTs relative to the original plan. Regarding target volumes, a highly significant decrease in MD (MD = 20 Gy, CI: −20.310 to −19.820) in D{sub 98} of the high-dose planning target volume (PTV [70 Gy]; PTVD{sub 98%} = 70 Gy) for case 3 was found (p ≤ 0.001). A nonpredictable, yet significant dosimetric effect was found. A clinically acceptable balance must be achieved between OAR dosimetry and target coverage as can be achieved by frequent IG.

SU-F-T-366: Dosimetric Parameters Enhancement of 120-Leaf Millennium MLC Using EGSnrc and IAEA Phase-Space Data

International Nuclear Information System (INIS)

Haddad, K; Alopoor, H

2016-01-01

Purpose: Recently, the multileaf collimators (MLC) have become an important part of any LINAC collimation systems because they reduce the treatment planning time and improves the conformity. Important factors that affects the MLCs collimation performance are leaves material composition and their thickness. In this study, we investigate the main dosimetric parameters of 120-leaf Millennium MLC including dose in the buildup point, physical penumbra as well as average and end leaf leakages. Effects of the leaves geometry and density on these parameters are evaluated Methods: From EGSnrc Monte Carlo code, BEAMnrc and DOSXYZnrc modules are used to evaluate the dosimetric parameters of a water phantom exposed to a Varian xi for 100cm SSD. Using IAEA phasespace data just above MLC (Z=46cm) and BEAMnrc, for the modified 120-leaf Millennium MLC a new phase space data at Z=52cm is produces. The MLC is modified both in leaf thickness and material composition. EGSgui code generates 521ICRU library for tungsten alloys. DOSXYZnrc with the new phase space evaluates the dose distribution in a water phantom of 60×60×20 cm3 with voxel size of 4×4×2 mm3. Using DOSXYZnrc dose distributions for open beam and closed beam as well as the leakages definition, end leakage, average leakage and physical penumbra are evaluated. Results: A new MLC with improved dosimetric parameters is proposed. The physical penumbra for proposed MLC is 4.7mm compared to 5.16 mm for Millennium. Average leakage in our design is reduced to 1.16% compared to 1.73% for Millennium, the end leaf leakage suggested design is also reduced to 4.86% compared to 7.26% of Millennium. Conclusion: The results show that the proposed MLC with enhanced dosimetric parameters could improve the conformity of treatment planning.

SU-F-T-366: Dosimetric Parameters Enhancement of 120-Leaf Millennium MLC Using EGSnrc and IAEA Phase-Space Data

Energy Technology Data Exchange (ETDEWEB)

Haddad, K; Alopoor, H [Shiraz University, Shiraz, I.R. Iran (Iran, Islamic Republic of)

2016-06-15

Purpose: Recently, the multileaf collimators (MLC) have become an important part of any LINAC collimation systems because they reduce the treatment planning time and improves the conformity. Important factors that affects the MLCs collimation performance are leaves material composition and their thickness. In this study, we investigate the main dosimetric parameters of 120-leaf Millennium MLC including dose in the buildup point, physical penumbra as well as average and end leaf leakages. Effects of the leaves geometry and density on these parameters are evaluated Methods: From EGSnrc Monte Carlo code, BEAMnrc and DOSXYZnrc modules are used to evaluate the dosimetric parameters of a water phantom exposed to a Varian xi for 100cm SSD. Using IAEA phasespace data just above MLC (Z=46cm) and BEAMnrc, for the modified 120-leaf Millennium MLC a new phase space data at Z=52cm is produces. The MLC is modified both in leaf thickness and material composition. EGSgui code generates 521ICRU library for tungsten alloys. DOSXYZnrc with the new phase space evaluates the dose distribution in a water phantom of 60×60×20 cm3 with voxel size of 4×4×2 mm3. Using DOSXYZnrc dose distributions for open beam and closed beam as well as the leakages definition, end leakage, average leakage and physical penumbra are evaluated. Results: A new MLC with improved dosimetric parameters is proposed. The physical penumbra for proposed MLC is 4.7mm compared to 5.16 mm for Millennium. Average leakage in our design is reduced to 1.16% compared to 1.73% for Millennium, the end leaf leakage suggested design is also reduced to 4.86% compared to 7.26% of Millennium. Conclusion: The results show that the proposed MLC with enhanced dosimetric parameters could improve the conformity of treatment planning.

Theoretical and experimental determination of dosimetric characteristics for ADVANTAGETM Pd-103 brachytherapy source

International Nuclear Information System (INIS)

Meigooni, Ali S.; Dini, Sharifeh A.; Awan, Shahid B.; Dou, Kai; Koona, Rafiq A.

2006-01-01

ADVANTAGE TM Pd-103 brachytherapy source has been recently introduced by IsoAid TM for prostate permanent implants. Dosimetric characteristics (Dose rate constant, radial dose function, 2D-, and 1D-anisotropy functions) of this source model have been determined using both theoretical and experimental methods, following the updated TG-43U1 protocol. Derivation of the dose rate constant was based on recent NIST WAFAC calibration performed in accordance with the 1999 Standards. Measurements were performed in Solid Water TM using LiF TLD chips and the theoretical calculations were performed in Solid Water TM and liquid water phantom materials using PTRAN Monte Carlo code. The results of the Monte Carlo simulation have shown a dose rate constant of 0.69 cGy h -1 U -1 in liquid water and 0.67 cGy h -1 U -1 in Solid Water TM medium. The measured dose rate constant in Solid Water TM was found to be 0.68±8% cGy h -1 U -1 , which is in a good agreement (within ±5%) to the Monte Carlo simulated data. The 2D- and 1D-anisotropy functions of the ADVANTAGE TM Pd-103 source were calculated for radial distances ranging from 0.5 to 5.0 cm. Radial dose function was determined for radial distances ranging from 0.2 to 8.0 cm using line source approximation. All these calculations are based on L eff equal to 3.61 cm, calculated following TG-43U1 recommendations. The tabulated data for 2D-anisotropy function, 1D-anisotropy function, dose rate constant and radial dose function have been produced for clinical application of this source model

Estimation of Cyclic Interstory Drift Capacity of Steel Framed Structures and Future Applications for Seismic Design

Directory of Open Access Journals (Sweden)

Edén Bojórquez

2014-01-01

Full Text Available Several studies have been devoted to calibrate damage indices for steel and reinforced concrete members with the purpose of overcoming some of the shortcomings of the parameters currently used during seismic design. Nevertheless, there is a challenge to study and calibrate the use of such indices for the practical structural evaluation of complex structures. In this paper, an energy-based damage model for multidegree-of-freedom (MDOF steel framed structures that accounts explicitly for the effects of cumulative plastic deformation demands is used to estimate the cyclic drift capacity of steel structures. To achieve this, seismic hazard curves are used to discuss the limitations of the maximum interstory drift demand as a performance parameter to achieve adequate damage control. Then the concept of cyclic drift capacity, which incorporates information of the influence of cumulative plastic deformation demands, is introduced as an alternative for future applications of seismic design of structures subjected to long duration ground motions.

Calibrated Properties Model

International Nuclear Information System (INIS)

Ahlers, C.F.; Liu, H.H.

2001-01-01

The purpose of this Analysis/Model Report (AMR) is to document the Calibrated Properties Model that provides calibrated parameter sets for unsaturated zone (UZ) flow and transport process models for the Yucca Mountain Site Characterization Project (YMP). This work was performed in accordance with the AMR Development Plan for U0035 Calibrated Properties Model REV00 (CRWMS M and O 1999c). These calibrated property sets include matrix and fracture parameters for the UZ Flow and Transport Model (UZ Model), drift seepage models, drift-scale and mountain-scale coupled-processes models, and Total System Performance Assessment (TSPA) models as well as Performance Assessment (PA) and other participating national laboratories and government agencies. These process models provide the necessary framework to test conceptual hypotheses of flow and transport at different scales and predict flow and transport behavior under a variety of climatic and thermal-loading conditions

Radiometric Calibration of Osmi Imagery Using Solar Calibration

Directory of Open Access Journals (Sweden)

Dong-Han Lee

2000-12-01

Full Text Available OSMI (Ocean Scanning Multi-Spectral Imager raw image data (Level 0 were acquired and radiometrically corrected. We have applied two methods, using solar & dark calibration data from OSMI sensor and comparing with the SeaWiFS data, to the radiometric correction of OSMI raw image data. First, we could get the values of the gain and the offset for each pixel and each band from comparing the solar & dark calibration data with the solar input radiance values, calculated from the transmittance, BRDF (Bidirectional Reflectance Distribution Function and the solar incidence angle (¥â,¥è of OSMI sensor. Applying this calibration data to OSMI raw image data, we got the two odd results, the lower value of the radiometric corrected image data than the expected value, and the Venetian Blind Effect in the radiometric corrected image data. Second, we could get the reasonable results from comparing OSMI raw image data with the SeaWiFS data, and get a new problem of OSMI sensor.

An evaluation of the dosimetric performance characteristics of N-vinylpyrrolidone-based polymer gels

Energy Technology Data Exchange (ETDEWEB)

Papadakis, A E [Department of Medical Physics, Faculty of Medicine, University of Crete, PO Box 2208, Iraklion 71003, Crete (Greece); Maris, T G [Department of Medical Physics, Faculty of Medicine, University of Crete, PO Box 2208, Iraklion 71003, Crete (Greece); Zacharopoulou, F [Department of Medical Physics, Faculty of Medicine, University of Crete, PO Box 2208, Iraklion 71003, Crete (Greece); Pappas, E [Department of Medical Physics, Faculty of Medicine, University of Crete, PO Box 2208, Iraklion 71003, Crete (Greece); Zacharakis, G [Institute of Electronic Structure and Laser (IESL), Foundation for Research and Technology-Hellas (FORTH), PO Box 1527, Iraklion, Crete (Greece); Damilakis, J [Department of Medical Physics, Faculty of Medicine, University of Crete, PO Box 2208, Iraklion 71003, Crete (Greece)

2007-08-21

The aim of this work was to investigate the dosimetric performance properties of the N-vinylpyrrolidone argon (VIPAR) based polymer gel as a dosimetric tool in clinical radiotherapy. VIPAR gels with a larger concentration of gelatin than the standard recipe were manufactured and irradiated up to 68 Gy using a 6 and 18 MV linear accelerator. Using MRI, the R2-dose response was recorded at different imaging sessions within a 34 day time period post-irradiation. The R2-dose response was found to be linear between 5 and 68 Gy. Although dose sensitivity did not show significant variation with time, the measured R2-dose values showed an increasing trend, which was less evident beyond 17 days. At one day post-irradiation, calculated dose standard uncertainties at 20 Gy and 56 Gy were 2.2% and 1.7%, providing a dose resolution of 0.45 Gy and 0.97 Gy, respectively. Although these values fulfilled the 2% limit of ICRU, when gels were imaged at one day post-irradiation, it was shown that the temporal evolution of the R2 values deteriorated the per cent standard uncertainty and the dose resolution by {approx}57%, when imaged 17 days post-irradiation. Variation in the coagulation temperature of the gels did not impact the R2-dose sensitivity. This study has shown that the VIPAR gel has the properties of a dosimetric tool required in clinical radiotherapy, especially in applications where a wide dose dynamic range is employed. For results with the lowest per cent uncertainty and the optimum dose resolution, the dosimetry gels used in this work should be MR scanned at one day post-irradiation. Furthermore, a preliminary study on the R2-dose response of a new normoxic N-vinylpyrrolidone-based polymer gel showed that it could potentially replace the traditional VIPAR gel formulation, while preserving the wide dynamic dose response inherent to that monomer.

A spectrophotometric readout for γ irradiated alanine solution - a dosimetric application

International Nuclear Information System (INIS)

Marzouk, Asma

2007-01-01

Alanine is a stable dosimeter of reference in its solid state. Its installation in solution as being a dosimetric system of routine remains very useful. A follow-up of the behaviour of the irradiated alanine solution with 15 kGy according to the concentration is carried out by UV-Visible spectrophotometry. The results obtained prove the difficulty in analytical studies of the radiolysis of aqueous solutions by optical absorption due to the ambiguous broad spectra of the species and the reaction products. (Author). 47 refs

Method of accounting and suppressing the instability of dosimetric information

International Nuclear Information System (INIS)

Fejtek, Ya.

1977-01-01

To account for dosimetric information instability differential and integral correcting factors are proposed. The differential factor converts signals of dosimeters irradiated during short but different periods of time into equivalent signals related to a certain period of time. The factor excludes the effect of signal instability in the case of short exposures. The integral factor represents a generalization of the differential one for prolonged exposures. The statistical integral factor is derived. An example of processing experimental data using the analytical method developed is presented. The method is pointed out to have been introduced in the state personal dosimetry service in Czechoslovakia [ru

Dosimetric study of the total corporal irradiation with high energy photons: Comparison between a linac mevatron KD and a bomb of 60CO Rokus M-132

International Nuclear Information System (INIS)

Bernal, M. A.; Silvestre, I

2001-01-01

Several dosimetric aspects of a 6 0 Co beam and another of 15 MV R X, of a linear accelerator, used for the Whole-Body Irradiation (WBI), as part of the bone marrow transplants, are studied. The lineal accelerator offers better beam characteristics. The dosimetric field is bigger and offers smaller dimness, which facilitates a higher dose homogeneity along the patient [es

AFM lateral force calibration for an integrated probe using a calibration grating

International Nuclear Information System (INIS)

Wang, Huabin; Gee, Michelle L.

2014-01-01

Atomic force microscopy (AFM) friction measurements on hard and soft materials remain a challenge due to the difficulties associated with accurately calibrating the cantilever for lateral force measurement. One of the most widely accepted lateral force calibration methods is the wedge method. This method is often used in a simplified format but in so doing sacrifices accuracy. In the present work, we have further developed the wedge method to provide a lateral force calibration method for integrated AFM probes that is easy to use without compromising accuracy and reliability. Raw friction calibration data are collected from a single scan image by continuous ramping of the set point as the facets of a standard grating are scanned. These data are analysed to yield an accurate lateral force conversion/calibration factor that is not influenced by adhesion forces or load deviation. By demonstrating this new calibration method, we illustrate its reliability, speed and ease of execution. This method makes accessible reliable boundary lubrication studies on adhesive and heterogeneous surfaces that require spatial resolution of frictional forces. - Highlights: • We develop a simple and accurate method for lateral force calibration in AFM friction measurements. • We detail the basis of the method and illustrate how to use it and its reliability with example data. • Our method is easy, accurate and accounts for the affects of adhesion on friction measurements. • The method is applicable to integrated probes, as opposed to colloidal probes. • This allows accurate AFM friction measurements on spatially heterogeneous and adhesive surfaces

Monte Carlo calculations and experimental measurements of dosimetric parameters of the IRA-103Pd source

International Nuclear Information System (INIS)

Sadeghi, Mahdi; Hosseini, Hamed; Raisali, Gholamreza

2008-01-01

Full text: The use of 103 Pd seed sources for permanent prostate implantation has become a popular brachytherapy application. As recommended by AAPM the dosimetric characteristics of the new source must be determined using experimental and Monte Carlo simulations, before its use in clinical applications thus The goal of this report is the experimental and theoretical determination of the dosimetric characteristics of this source following the recommendations in the AAPM TG-43U1 protocol. Figure 1 shows the geometry of the IRA- 103 Pd source. The source consists of a cylindrical silver core, 0.3 cm long x 0.05 cm in diameter, onto which 0.5 nm layer of 103 Pd has been uniformly adsorbed. The effective active length of source is 0.3 cm and the silver core encapsulated inside a hollow titanium tube with 0.45 cm long, 0.07 cm and 0.08 inner and outer diameters and two caps. The Monte Carlo N-Particle (MCNP) code, version 4C, was used to determine the relevant dosimetric parameters of the source. The geometry of the Monte Carlo simulation performed in this study consisted of a sphere with 30 cm diameter. Dose distributions around this source were measured in two Perspex phantom using enough TLD chips. For these measurements, slabs of Perspex material were machined to accommodate the source and TLD chips. A value of 0.67± 1% cGy.h -1 .U -1 for, Λ, was calculated as the ratio of d(r 0 ,θ 0 ) and s K , that may be compared with Λ values obtained for 103 Pd sources. Result of calculations and measurements values of dosimetric parameters of the source including radial dose function, g(r), and anisotropy function, F(r,θ), has been shown in separate figures. The radial dose function, g(r), for the IRA- 103 Pd source and other 103 Pd sources is included in Fig. 2. Comparison between measured and Monte Carlo simulated dose function, g(r), and anisotropy function, F(r,θ), of this source demonstrated that they are in good agreement with each other and The value of Λ is

Syringe calibration factors and volume correction factors for the NPL secondary standard radionuclide calibrator

CERN Document Server

Tyler, D K

2002-01-01

The activity assay of a radiopharmaceutical administration to a patient is normally achieved via the use of a radionuclide calibrator. Because of the different geometries and elemental compositions between plastic syringes and glass vials, the calibration factors for syringes may well be significantly different from those for the glass containers. The magnitude of these differences depends on the energies of the emitted photons. For some radionuclides variations have been observed of 70 %, it is therefore important to recalibrate for syringes or use syringe calibration factors. Calibration factors and volume correction factors have been derived for the NPL secondary standard radionuclide calibrator, for a variety of commonly used syringes and needles, for the most commonly used medical radionuclide.

The GERDA calibration system

Energy Technology Data Exchange (ETDEWEB)

Baudis, Laura; Froborg, Francis; Tarka, Michael; Bruch, Tobias; Ferella, Alfredo [Physik-Institut, Universitaet Zuerich (Switzerland); Collaboration: GERDA-Collaboration

2012-07-01

A system with three identical custom made units is used for the energy calibration of the GERDA Ge diodes. To perform a calibration the {sup 228}Th sources are lowered from the parking positions at the top of the cryostat. Their positions are measured by two independent modules. One, the incremental encoder, counts the holes in the perforated steel band holding the sources, the other measures the drive shaft's angular position even if not powered. The system can be controlled remotely by a Labview program. The calibration data is analyzed by an iterative calibration algorithm determining the calibration functions for different energy reconstruction algorithms and the resolution of several peaks in the {sup 228}Th spectrum is determined. A Monte Carlo simulation using the GERDA simulation software MAGE has been performed to determine the background induced by the sources in the parking positions.

Characteristics and calibration of the transmission-type fast neutron moisture meter

International Nuclear Information System (INIS)

Banzai, K.

1984-01-01

With the Transmission-type Fast Neutron Moisture Meter, we did some experiments for calibration and the effective range of fast neutron scattering, and observed soil moisture process before and after making artificial rainfall at a lysimeter filled by decomposed granite. A fast neutron source of this meter is 252 Cf and capacity of 100 μ Ci. The neutron detector is NE-213 liquid scintilator which recovers a little flux of neutron source. For the customary thermal neutron meter, the effective range of neutron scattering is variable by soil moisture values surrounding the observation point, but this fast neutron, insert and transmission-type meter shows soil moisture in small capacity between a source and a detector. Experimental Results; 1) The calibration curve, calculated statistically from the relation of soil moisture and the count ratio in a 200 l drum packed with beads, gravel, sand and Kanto loam, became only one line. The correlation coefficient of this curve was 0.996 and the standard error was 1.94% with volumetric water content. 2) Count ratio started to decrease as observation point approached soil surface from the boundary of 6 cm depth in soil. Volumetric water content increased more than fact with the previous calibration curve. 3) We limited the detectable range to fast neutron, but a little scattering was seen surrounding the soil of a observation point. The effective range of horizontal scattering was a width of 20 cm with the center line connected between a source and a detector, with a circle of 5 cm diameter surrounding the source, and a circle of 10-15 cm diameter surrounding the detector. 4) Soil moisture before and after artificial rainfall was observed with this meter and by the measurement of a 100 cm 3 oven dried sampling vessel. Volumetric water content by the latter measurement, was more variable because sampling points were at a distance from the center of observation site and sampling technique was bad. Otherwise soil moisture values

RF impedance measurement calibration

International Nuclear Information System (INIS)

Matthews, P.J.; Song, J.J.

1993-01-01

The intent of this note is not to explain all of the available calibration methods in detail. Instead, we will focus on the calibration methods of interest for RF impedance coupling measurements and attempt to explain: (1). The standards and measurements necessary for the various calibration techniques. (2). The advantages and disadvantages of each technique. (3). The mathematical manipulations that need to be applied to the measured standards and devices. (4). An outline of the steps needed for writing a calibration routine that operated from a remote computer. For further details of the various techniques presented in this note, the reader should consult the references

Robot-assisted automatic ultrasound calibration.

Science.gov (United States)

Aalamifar, Fereshteh; Cheng, Alexis; Kim, Younsu; Hu, Xiao; Zhang, Haichong K; Guo, Xiaoyu; Boctor, Emad M

2016-10-01

Ultrasound (US) calibration is the process of determining the unknown transformation from a coordinate frame such as the robot's tooltip to the US image frame and is a necessary task for any robotic or tracked US system. US calibration requires submillimeter-range accuracy for most applications, but it is a time-consuming and repetitive task. We provide a new framework for automatic US calibration with robot assistance and without the need for temporal calibration. US calibration based on active echo (AE) phantom was previously proposed, and its superiority over conventional cross-wire phantom-based calibration was shown. In this work, we use AE to guide the robotic arm motion through the process of data collection; we combine the capability of the AE point to localize itself in the frame of the US image with the automatic motion of the robotic arm to provide a framework for calibrating the arm to the US image automatically. We demonstrated the efficacy of the automated method compared to the manual method through experiments. To highlight the necessity of frequent ultrasound calibration, it is demonstrated that the calibration precision changed from 1.67 to 3.20 mm if the data collection is not repeated after a dismounting/mounting of the probe holder. In a large data set experiment, similar reconstruction precision of automatic and manual data collection was observed, while the time was reduced by 58 %. In addition, we compared ten automatic calibrations with ten manual ones, each performed in 15 min, and showed that all the automatic ones could converge in the case of setting the initial matrix as identity, while this was not achieved by manual data sets. Given the same initial matrix, the repeatability of the automatic was [0.46, 0.34, 0.80, 0.47] versus [0.42, 0.51, 0.98, 1.15] mm in the manual case for the US image four corners. The submillimeter accuracy requirement of US calibration makes frequent data collections unavoidable. We proposed an automated

A Dosimetric Comparison of Dose Escalation with Simultaneous Integrated Boost for Locally Advanced Non-Small-Cell Lung Cancer

Directory of Open Access Journals (Sweden)

Wenjuan Yang

2017-01-01

Full Text Available Background. Many studies have demonstrated that a higher radiotherapy dose is associated with improved outcomes in non-small-cell lung cancer (NSCLC. We performed a dosimetric planning study to assess the dosimetric feasibility of intensity-modulated radiation therapy (IMRT with a simultaneous integrated boost (SIB in locally advanced NSCLC. Methods. We enrolled twenty patients. Five different dose plans were generated for each patient. All plans were prescribed a dose of 60 Gy to the planning tumor volume (PTV. In the three SIB groups, the prescribed dose was 69 Gy, 75 Gy, and 81 Gy in 30 fractions to the internal gross tumor volume (iGTV. Results. The SIB-IMRT plans were associated with a significant increase in the iGTV dose (P < 0.05, without increased normal tissue exposure or prolonged overall treatment time. Significant differences were not observed in the dose to the normal lung in terms of the V5 and V20 among the four IMRT plans. The maximum dose (Dmax in the esophagus moderately increased along with the prescribed dose (P < 0.05. Conclusions. Our results indicated that escalating the dose by SIB-IMRT is dosimetrically feasible; however, systematic evaluations via clinical trials are still warranted. We have designed a further clinical study (which is registered with ClinicalTrials.gov, number NCT02841228.

SPOTS Calibration Example

Directory of Open Access Journals (Sweden)

Patterson E.

2010-06-01

Full Text Available The results are presented using the procedure outlined by the Standardisation Project for Optical Techniques of Strain measurement to calibrate a digital image correlation system. The process involves comparing the experimental data obtained with the optical measurement system to the theoretical values for a specially designed specimen. The standard states the criteria which must be met in order to achieve successful calibration, in addition to quantifying the measurement uncertainty in the system. The system was evaluated at three different displacement load levels, generating strain ranges from 289 µstrain to 2110 µstrain. At the 289 µstrain range, the calibration uncertainty was found to be 14.1 µstrain, and at the 2110 µstrain range it was found to be 28.9 µstrain. This calibration procedure was performed without painting a speckle pattern on the surface of the metal. Instead, the specimen surface was prepared using different grades of grit paper to produce the desired texture.

Characteristic parameters analysis on diagnostic X-ray beams for dosemeter calibration; Analise de parametros caracteristicos de feixes de raios-X diagnostico para calibracao de dosimetros

Energy Technology Data Exchange (ETDEWEB)

Oliveira, Paulo Marcio Campos de

2008-07-01

Ionizing radiation metrology is the base to achieve reliable dose measurements in ali areas; it is also part of the framework that is established to assure radiation protection procedures in order to avoid or minimize the harmful biological effect that may be caused by ionizing radiation. A well done metrology means the use of reliable instruments that comply with standard performance requirements worldwide accepted. Those instruments are expected to be calibrated by Metrology Laboratories under well defined conditions. The International Electrotechnical Commission (IEC) in Standard 61267 established the reference radiations for medical diagnostic x-ray equipment that are recommended to be used for calibrating dosimetric systems for diagnostic dosimetry. In this work, X-ray beam qualities were established in a Calibration Laboratory and their characteristics were analyzed through the measurement of beam parameters like inherent tube filtration, beam uniformity and field size, energy spectra and peak voltage for additional filtration with 94.425 por cent and 99.999 por cent purity filters. Also, the first half-value layer and the homogeneity coefficient were measured for the three RQR 2, RQR 6 and RQR 10 IEC beam qualities and they were analyzed according to the IEC standard. Air-kerma measurements were carried out with an ionization chamber that had its reliability confirmed through repetition and reproducibility reading tests. In 50 sets of measurements the maximum standard deviation found of 10 successive readings was 0.19 %; the maximum shift of the reading mean value at a fixed geometry condition was 0.80 % with an overall standard deviation of 0.23 %. Results showed that the use of different purity filters did not cause a relevant influence on the beam energy spectra. An ionization chamber was also calibrated against a standard dosimeter in ali implemented reference radiations and the relevant sources of uncertainties were estimated. Calibration could be done

Neutron sources and its dosimetric characteristics

International Nuclear Information System (INIS)

Vega C, H.R.; Manzanares A, E.; Hernandez D, V.M.; Mercado S, G.A.; Gallego D, E.; Lorente F, A.

2005-01-01

By means of Monte Carlo methods the spectra of the produced neutrons 252 Cf, 252 Cf/D 2 O, 241 Am Be, 239 Pu Be, 140 La Be, 239 Pu 18 O 2 and 226 Ra Be have been calculated. With the information of the spectrum it was calculated the average energy of the neutrons of each source. By means of the fluence coefficients to dose it was determined, for each one of the studied sources, the fluence factors to dose. The calculated doses were H, H * (10), H p,sIab (10, 0 0 ), E AP and E ISO . During the phase of the calculations the sources were modeled as punctual and their characteristics were determined to 100 cm in the hole. Also, for the case of the sources of 239 Pu Be and 241 Am Be, were carried out calculations modeling the sources with their respective characteristics and the dosimetric properties were determined in a space full with air. The results of this last phase of the calculations were compared with the experimental results obtained for both sources. (Author)

Dosimetric characterization of KMgF3:Tb+PTFE

International Nuclear Information System (INIS)

Ramirez R, M. I.; Garcia S, L.; Villicana M, M.; Huirache A, R.; Apolinar C, J.; Gonzalez M, P. R.

2017-10-01

In this work the results obtained from the dosimetric characterization of the new radiation detectors of KMgF 3 :Tb+PTFE are presented. The host salt was obtained by means of the microwave technique, with the polycrystalline powder obtained, dosimeters were made in tablet form, using as Ptfe binder. The thermoluminescent response of these new detectors presented a linear behavior, in the dose range between 1 and 1000 Gy of 60 Co gamma radiation, the reproducibility test in the measurements, during ten cycles of heat treatment, irradiation and reading presented ± 3.7% Ds, in the stability test of thermoluminescent signal, during two months showed that the fading is practically null. Due to the results obtained, this new detector could be very useful for the dosimetry of ionizing radiation in different clinical applications. (Author)

A Study on Relative Radiometric Calibration without Calibration Field for YG-25

Directory of Open Access Journals (Sweden)

ZHANG Guo

2017-08-01

Full Text Available YG-25 is the first agility optical remote sensing satellite of China to acquire the sub-meter imagery of the earth. The side slither calibration technique is an on-orbit maneuver that has been used to flat-field image data acquired over the uniform calibration field. However, imaging to the single uniform calibration field cannot afford to calibrate the full dynamic response range of the sensor and reduces the efficiency. The paper proposes a new relative radiometric calibration method that a 90-degree yaw maneuver is performed over any non-uniform features of the Earth for YG-25. Meanwhile, we use an enhanced side slither image horizontal correction method based on line segment detector(LSDalgorithm to solve the side slither image over-shifted problem.The shifted results are compared with other horizontal correction method. The histogram match algorithm is used to calculate the relative gains of all detectors. The correctness and validity of the proposed method are validated by using the YG-25 on-board side slither data. The results prove that the mean streaking metrics of relative correction images of YG-25 is better 0.07%, the noticeable striping artifact and residual noise are removed, the calibration accuracy of side slither technique based on non-uniform features is superior to life image statistics of sensor's life span.

Pulse-based internal calibration of polarimetric SAR

DEFF Research Database (Denmark)

Dall, Jørgen; Skou, Niels; Christensen, Erik Lintz

1994-01-01

Internal calibration greatly diminishes the dependence on calibration target deployment compared to external calibration. Therefore the Electromagnetics Institute (EMI) at the Technical University of Denmark (TUD) has equipped its polarimetric SAR, EMISAR, with several calibration loops and devel......Internal calibration greatly diminishes the dependence on calibration target deployment compared to external calibration. Therefore the Electromagnetics Institute (EMI) at the Technical University of Denmark (TUD) has equipped its polarimetric SAR, EMISAR, with several calibration loops...

Site Calibration report

DEFF Research Database (Denmark)

Yordanova, Ginka; Vesth, Allan

The report describes site calibration measurements carried out on a site in Denmark. The measurements are carried out in accordance to Ref. [1]. The site calibration is carried out before a power performance measurement on a given turbine to clarify the influence from the terrain on the ratio...

Dosimetric properties of a novel brachytherapy balloon applicator for the treatment of malignant brain-tumor resection-cavity margins

International Nuclear Information System (INIS)

Dempsey, James F.; Williams, Jeffery A.; Stubbs, James B.; Patrick, Timothy J.; Williamson, Jeffrey F.

1998-01-01

Purpose: This paper characterizes the dosimetric properties of a novel balloon brachytherapy applicator for the treatment of the tissue surrounding the resection cavity of a malignant brain tumor. Methods and Materials: The applicator consists of an inflatable silicone balloon reservoir attached to a positionable catheter that is intraoperatively implanted into the resection cavity and postoperatively filled with a liquid radionuclide solution. A simple dosimetric model, valid in homogeneous media and based on results from Monte Carlo photon-transport simulations, was used to determine the dosimetric characteristics of spherical geometry balloons filled with photon-emitting radionuclide solutions. Fractional depth-dose (FDD) profiles, along with activity densities, and total activities needed to achieve specified dose rates were studied as a function of photon energy and source-containment geometry. Dose-volume histograms (DVHs) were calculated to compare idealized balloon-applicator treatments to conventional 125 I seed volume implants. Results: For achievable activity densities and total activities, classical low dose rate (LDR) treatments of residual disease at distances of up to 1 cm from the resection cavity wall are possible with balloon applicators having radii between 0.5 cm and 2.5 cm. The dose penetration of these applicators increases approximately linearly with balloon radius. The FDD profile can be made significantly more or less penetrating by combining selection of radionuclide with source-geometry manipulation. Comparisons with 125 I seed-implant DVHs show that the applicator can provide a more conformal therapy with no target tissue underdosing, less target tissue overdosing, and no healthy tissue ''hot spots;'' however, more healthy tissue volume receives a dose of the prescribed dosage or less. Conclusions: This device, when filled with 125 I solution, is suitable for classical LDR treatments and may be preferable to 125 I interstitial

WE-AB-209-02: A New Inverse Planning Framework with Principle-Based Modeling of Inter-Structural Dosimetric Tradeoffs

International Nuclear Information System (INIS)

Liu, H; Dong, P; Xing, L

2016-01-01

Purpose: Traditional radiotherapy inverse planning relies on the weighting factors to phenomenologically balance the conflicting criteria for different structures. The resulting manual trial-and-error determination of the weights has long been recognized as the most time-consuming part of treatment planning. The purpose of this work is to develop an inverse planning framework that parameterizes the inter-structural dosimetric tradeoff among with physically more meaningful quantities to simplify the search for a clinically sensible plan. Methods: A permissible dosimetric uncertainty is introduced for each of the structures to balance their conflicting dosimetric requirements. The inverse planning is then formulated as a convex feasibility problem, which aims to generate plans with acceptable dosimetric uncertainties. A sequential procedure (SP) is derived to decompose the model into three submodels to constrain the uncertainty in the planning target volume (PTV), the critical structures, and all other structures to spare, sequentially. The proposed technique is applied to plan a liver case and a head-and-neck case and compared with a conventional approach. Results: Our results show that the strategy is able to generate clinically sensible plans with little trial-and-error. In the case of liver IMRT, the fractional volumes to liver and heart above 20Gy are found to be 22% and 10%, respectively, which are 15.1% and 33.3% lower than that of the counterpart conventional plan while maintaining the same PTV coverage. The planning of the head and neck IMRT show the same level of success, with the DVHs for all organs at risk and PTV very competitive to a counterpart plan. Conclusion: A new inverse planning framework has been established. With physically more meaningful modeling of the inter-structural tradeoff, the technique enables us to substantially reduce the need for trial-and-error adjustment of the model parameters and opens new opportunities of incorporating prior

WE-AB-209-02: A New Inverse Planning Framework with Principle-Based Modeling of Inter-Structural Dosimetric Tradeoffs

Energy Technology Data Exchange (ETDEWEB)

Liu, H; Dong, P; Xing, L [Stanford University School of Medicine, Stanford, CA (United States)

2016-06-15

Purpose: Traditional radiotherapy inverse planning relies on the weighting factors to phenomenologically balance the conflicting criteria for different structures. The resulting manual trial-and-error determination of the weights has long been recognized as the most time-consuming part of treatment planning. The purpose of this work is to develop an inverse planning framework that parameterizes the inter-structural dosimetric tradeoff among with physically more meaningful quantities to simplify the search for a clinically sensible plan. Methods: A permissible dosimetric uncertainty is introduced for each of the structures to balance their conflicting dosimetric requirements. The inverse planning is then formulated as a convex feasibility problem, which aims to generate plans with acceptable dosimetric uncertainties. A sequential procedure (SP) is derived to decompose the model into three submodels to constrain the uncertainty in the planning target volume (PTV), the critical structures, and all other structures to spare, sequentially. The proposed technique is applied to plan a liver case and a head-and-neck case and compared with a conventional approach. Results: Our results show that the strategy is able to generate clinically sensible plans with little trial-and-error. In the case of liver IMRT, the fractional volumes to liver and heart above 20Gy are found to be 22% and 10%, respectively, which are 15.1% and 33.3% lower than that of the counterpart conventional plan while maintaining the same PTV coverage. The planning of the head and neck IMRT show the same level of success, with the DVHs for all organs at risk and PTV very competitive to a counterpart plan. Conclusion: A new inverse planning framework has been established. With physically more meaningful modeling of the inter-structural tradeoff, the technique enables us to substantially reduce the need for trial-and-error adjustment of the model parameters and opens new opportunities of incorporating prior

LANL MTI calibration team experience

Science.gov (United States)

Bender, Steven C.; Atkins, William H.; Clodius, William B.; Little, Cynthia K.; Christensen, R. Wynn

2004-01-01

The Multispectral Thermal Imager (MTI) was designed as an imaging radiometer with absolute calibration requirements established by Department of Energy (DOE) mission goals. Particular emphasis was given to water surface temperature retrieval using two mid wave and three long wave infrared spectral bands, the fundamental requirement was a surface temperature determination of 1K at the 68% confidence level. For the ten solar reflective bands a one-sigma radiometric performance goal of 3% was established. In order to address these technical challenges a calibration facility was constructed containing newly designed sources that were calibrated at NIST. Additionally, the design of the payload and its onboard calibration system supported post launch maintenance and update of the ground calibration. The on-orbit calibration philosophy also included vicarious techniques using ocean buoys, playas and other instrumented sites; these became increasingly important subsequent to an electrical failure which disabled the onboard calibration system. This paper offers various relevant lessons learned in the eight-year process of reducing to practice the calibration capability required by the scientific mission. The discussion presented will include observations pertinent to operational and procedural issues as well as hardware experiences; the validity of some of the initial assumptions will also be explored.

Vibration transducer calibration techniques

Science.gov (United States)

Brinkley, D. J.

1980-09-01

Techniques for the calibration of vibration transducers used in the Aeronautical Quality Assurance Directorate of the British Ministry of Defence are presented. Following a review of the types of measurements necessary in the calibration of vibration transducers, the performance requirements of vibration transducers, which can be used to measure acceleration, velocity or vibration amplitude, are discussed, with particular attention given to the piezoelectric accelerometer. Techniques for the accurate measurement of sinusoidal vibration amplitude in reference-grade transducers are then considered, including the use of a position sensitive photocell and the use of a Michelson laser interferometer. Means of comparing the output of working-grade accelerometers with that of previously calibrated reference-grade devices are then outlined, with attention given to a method employing a capacitance bridge technique and a method to be used at temperatures between -50 and 200 C. Automatic calibration procedures developed to speed up the calibration process are outlined, and future possible extensions of system software are indicated.

Energy calibration issues in nuclear resonant vibrational spectroscopy: observing small spectral shifts and making fast calibrations.

Science.gov (United States)

Wang, Hongxin; Yoda, Yoshitaka; Dong, Weibing; Huang, Songping D

2013-09-01

The conventional energy calibration for nuclear resonant vibrational spectroscopy (NRVS) is usually long. Meanwhile, taking NRVS samples out of the cryostat increases the chance of sample damage, which makes it impossible to carry out an energy calibration during one NRVS measurement. In this study, by manipulating the 14.4 keV beam through the main measurement chamber without moving out the NRVS sample, two alternative calibration procedures have been proposed and established: (i) an in situ calibration procedure, which measures the main NRVS sample at stage A and the calibration sample at stage B simultaneously, and calibrates the energies for observing extremely small spectral shifts; for example, the 0.3 meV energy shift between the 100%-(57)Fe-enriched [Fe4S4Cl4](=) and 10%-(57)Fe and 90%-(54)Fe labeled [Fe4S4Cl4](=) has been well resolved; (ii) a quick-switching energy calibration procedure, which reduces each calibration time from 3-4 h to about 30 min. Although the quick-switching calibration is not in situ, it is suitable for normal NRVS measurements.

Offshore newcomer : world-scale megaproject spawns international-calibre skills and facilities

International Nuclear Information System (INIS)

Sorensen, D.

1997-01-01

The development of Hibernia marked the beginning of Newfoundland's booming oil industry. The offshore platform located 300 km offshore in the Grand Banks of Newfoundland has an estimated 615 million barrels of recoverable reserves to be produced at a projected average rate of 135,000 barrels per day. Newfoundland personnel and facilities acquired much expertise during the building of the offshore facility and are ready to enter the world market for oil and gas services and supplies. Newfoundland's biggest operations are the fabrication yards at Bull Arm and Marystown which have the capacity for steel fabrication, concrete construction, outfitting installation, hook-up and commissioning of industrial facilities. Plans are currently underway for the Terra Nova project. Newfoundland also has a strong labor force, with international calibre skills. The capacity is here, and as confidence in that capability increases, Newfoundland firms are beginning to form partnerships with international firms. 6 figs

On chromatic and geometrical calibration

DEFF Research Database (Denmark)

Folm-Hansen, Jørgen

1999-01-01

The main subject of the present thesis is different methods for the geometrical and chromatic calibration of cameras in various environments. For the monochromatic issues of the calibration we present the acquisition of monochrome images, the classic monochrome aberrations and the various sources...... the correct interpolation method is described. For the chromatic issues of calibration we present the acquisition of colour and multi-spectral images, the chromatic aberrations and the various lens/camera based non-uniformities of the illumination of the image plane. It is described how the monochromatic...... to design calibration targets for both geometrical and chromatic calibration are described. We present some possible systematical errors on the detection of the objects in the calibration targets, if viewed in a non orthogonal angle, if the intensities are uneven or if the image blurring is uneven. Finally...

Dosimetric analysis of SMD phototransistor in dental phantom of different geometries

International Nuclear Information System (INIS)

Belinato, W.; Magalhaes, C. M. S.; Souza, D. N.; Santos, L. A. P.

2009-10-01

A commercial surface mount device (SMD) phototransistor, OP520, was inserted in two dental phantoms for dosimetric analysis. The irradiations were accomplished in a dental x-ray equipment of 80 kV using different exposition times. A standard ionization chamber was irradiated at the same conditions and the air kerma measured with it was compared with the electrical charge evaluated by the phototransistor. The results showed satisfactory correspondence among the detectors readings. Moreover, the phototransistor showed up quite sensitively for dental applications, allowing verifying the variations for the different phantoms configurations. (Author)

Calibration of triaxial fluxgate gradiometer

International Nuclear Information System (INIS)

Vcelak, Jan

2006-01-01

The description of simple and fast calibration procedures used for double-probe triaxial fluxgate gradiometer is provided in this paper. The calibration procedure consists of three basic steps. In the first step both probes are calibrated independently in order to reach constant total field reading in every position. Both probes are numerically aligned in the second step in order that the gradient reading is zero in homogenous magnetic field. The third step consists of periodic drift calibration during measurement. The results and detailed description of each calibration step are presented and discussed in the paper. The gradiometer is finally verified during the detection of the metal object in the measuring grid

Use of Balance Calibration Certificate to Calculate the Errors of Indication and Measurement Uncertainty in Mass Determinations Performed in Medical Laboratories

Directory of Open Access Journals (Sweden)

Adriana VÂLCU

2011-09-01

Full Text Available Based on the reference document, the article proposes the way to calculate the errors of indication and associated measurement uncertainties, by resorting to the general information provided by the calibration certificate of a balance (non-automatic weighing instruments, shortly NAWI used in medical field. The paper may be also considered a useful guideline for: operators working in laboratories accredited in medical (or other various fields where the weighing operations are part of their testing activities; test houses, laboratories, or manufacturers using calibrated non-automatic weighing instruments for measurements relevant for the quality of production subject to QM requirements (e.g. ISO 9000 series, ISO 10012, ISO/IEC 17025; bodies accrediting laboratories; accredited laboratories for the calibration of NAWI. Article refers only to electronic weighing instruments having maximum capacity up to 30 kg. Starting from the results provided by a calibration certificate it is presented an example of calculation.

Calibrating Legal Judgments

Directory of Open Access Journals (Sweden)

Frederick Schauer

2017-09-01

Full Text Available Objective to study the notion and essence of legal judgments calibration the possibilities of using it in the lawenforcement activity to explore the expenses and advantages of using it. Methods dialectic approach to the cognition of social phenomena which enables to analyze them in historical development and functioning in the context of the integrity of objective and subjective factors it determined the choice of the following research methods formallegal comparative legal sociological methods of cognitive psychology and philosophy. Results In ordinary life people who assess other peoplersaquos judgments typically take into account the other judgments of those they are assessing in order to calibrate the judgment presently being assessed. The restaurant and hotel rating website TripAdvisor is exemplary because it facilitates calibration by providing access to a raterrsaquos previous ratings. Such information allows a user to see whether a particular rating comes from a rater who is enthusiastic about every place she patronizes or instead from someone who is incessantly hard to please. And even when less systematized as in assessing a letter of recommendation or college transcript calibration by recourse to the decisional history of those whose judgments are being assessed is ubiquitous. Yet despite the ubiquity and utility of such calibration the legal system seems perversely to reject it. Appellate courts do not openly adjust their standard of review based on the previous judgments of the judge whose decision they are reviewing nor do judges in reviewing legislative or administrative decisions magistrates in evaluating search warrant representations or jurors in assessing witness perception. In most legal domains calibration by reference to the prior decisions of the reviewee is invisible either because it does not exist or because reviewing bodies are unwilling to admit using what they in fact know and employ. Scientific novelty for the first

High-resolution digital dosimetric system for spatial characterization of radiation fields using a thermoluminescent CaF2:Dy crystal

International Nuclear Information System (INIS)

Atari, N.A.; Svensson, G.K.

1986-01-01

A high-resolution digital dosimetric system has been developed for the spatial characterization of radiation fields. The system comprises the following: 0.5-mm-thick, 25-mm-diam CaF2:Dy thermoluminescent crystal; intensified charge coupled device video camera; video cassette recorder; and a computerized image processing subsystem. The optically flat single crystal is used as a radiation imaging device and the subsequent thermally stimulated phosphorescence is viewed by the intensified camera for further processing and analysis. Parameters governing the performance characteristics of the system were measured. A spatial resolution limit of 31 +/- 2 microns (1 sigma) corresponding to 16 +/- 1 line pairs/mm measured at the 4% level of the modulation transfer function has been achieved. The full width at half maximum of the line spread function measured independently by the slit method or derived from the edge response function was found to be 69 +/- 4 microns (1 sigma). The high resolving power, speed of readout, good precision, wide dynamic range, and the large image storage capacity make the system suitable for the digital mapping of the relative distribution of absorbed doses for various small radiation fields and the edges of larger fields

High-resolution digital dosimetric system for spatial characterization of radiation fields using a thermoluminescent CaF2:Dy crystal

International Nuclear Information System (INIS)

Atari, N.A.; Svensson, G.K.

1986-01-01

A high-resolution digital dosimetric system has been developed for the spatial characterization of radiation fields. The system comprises the following: 0.5-mm-thick, 25-mm-diam CaF 2 :Dy thermoluminescent crystal; intensified charge coupled device video camera; video cassette recorder; and a computerized image processing subsystem. The optically flat single crystal is used as a radiation imaging device and the subsequent thermally stimulated phosphorescence is viewed by the intensified camera for further processing and analysis. Parameters governing the performance characteristics of the system were measured. A spatial resolution limit of 31 +- 2 μm (1sigma) corresponding to 16 +- 1 line pair/mm measured at the 4% level of the modulation transfer function has been achieved. The full width at half maximum of the line spread function measured independently by the slit method or derived from the edge response function was found to be 69 +- 4 μm (1sigma). The high resolving power, speed of readout, good precision, wide dynamic range, and the large image storage capacity make the system suitable for the digital mapping of the relative distribution of absorbed doses for various small radiation fields and the edges of larger fields

Automatic 2D scintillation camera and computed tomography whole-body image registration to perform dosimetric calculations

International Nuclear Information System (INIS)

Cismondi, F.; Mosconi, S.L.

2008-01-01

Full text: In this work a software tool that has been developed to allow automatic registrations of 2D Scintillation Camera (SC) and Computed Tomography (CT) images is presented. This tool, used with a dosimetric software with Integrated Activity or Residence Time as input data, allows the user to assess physicians about effects of radiodiagnostic or radiotherapeutic practices that involves nuclear medicine 'open sources'. Images are registered locally and globally, maximizing Mutual Information coefficient between regions been registered. In the regional case whole-body images are segmented into five regions: head, thorax, pelvis, left and right legs. Each region has its own registration parameters, which are optimized through Powell-Brent minimization method that 'maximizes' Mutual Information coefficient. This software tool allows the user to draw ROIs, input isotope characteristics and finally calculate Integrated Activity or Residence Time in one or many specific organ. These last values can be introduced in many dosimetric software to finally obtain Absorbed Dose values. (author)

Determination of trapping parameters of dosimetric thermoluminescent glow peak of lithium triborate (LiB{sub 3}O{sub 5}) activated by aluminum

Energy Technology Data Exchange (ETDEWEB)

Kafadar, V. Emir [University of Gaziantep, Department of Engineering Physics, 27310 Gaziantep (Turkey); Yazici, A. Necmeddin, E-mail: yazici@gantep.edu.t [University of Gaziantep, Department of Engineering Physics, 27310 Gaziantep (Turkey); Yildirim, R. Gueler [University of Gaziantep, Department of Engineering Physics, 27310 Gaziantep (Turkey)

2009-07-15

Lithium triborate (LBO) is a newly developed ideal nonlinear optical (NLO) crystal used in laser weapon, welder, radar, tracker, surgery, communication, etc. The effective atomic number (Z{sub eff}=7.3) makes it a tissue equivalent material and this encourages studies on its thermoluminescence (TL) properties for a radiation dosimetry. The previous studies have shown that Al-doped LiB{sub 3}O{sub 5} is a promising thermoluminescent dosimetric (TLD) material for dosimetric purposes and continuous and systematic investigations to improve its quality to get ones suited for dosimeter applications are worthy. In the given study, the additive dose (AD), initial rise with partial cleaning (IR), variable heating rate (VHR), peak shape (PS), three-points method (TPM) and computerized glow deconvolution (CGCD) methods were used to determine the kinetic parameters, namely the order of kinetics (b), activation energy (E{sub a}) and the frequency factor (s) associated with the dosimetric thermoluminescent glow peak (P3) of Al-doped LiB{sub 3}O{sub 5} after different dose levels with beta-irradiation.

Mercury Continuous Emmission Monitor Calibration

Energy Technology Data Exchange (ETDEWEB)

John Schabron; Eric Kalberer; Ryan Boysen; William Schuster; Joseph Rovani

2009-03-12

Mercury continuous emissions monitoring systems (CEMs) are being implemented in over 800 coal-fired power plant stacks throughput the U.S. Western Research Institute (WRI) is working closely with the Electric Power Research Institute (EPRI), the National Institute of Standards and Technology (NIST), and the Environmental Protection Agency (EPA) to facilitate the development of the experimental criteria for a NIST traceability protocol for dynamic elemental mercury vapor calibrators/generators. These devices are used to calibrate mercury CEMs at power plant sites. The Clean Air Mercury Rule (CAMR) which was published in the Federal Register on May 18, 2005 and vacated by a Federal appeals court in early 2008 required that calibration be performed with NIST-traceable standards. Despite the vacature, mercury emissions regulations in the future will require NIST traceable calibration standards, and EPA does not want to interrupt the effort towards developing NIST traceability protocols. The traceability procedures will be defined by EPA. An initial draft traceability protocol was issued by EPA in May 2007 for comment. In August 2007, EPA issued a conceptual interim traceability protocol for elemental mercury calibrators. The protocol is based on the actual analysis of the output of each calibration unit at several concentration levels ranging initially from about 2-40 {micro}g/m{sup 3} elemental mercury, and in the future down to 0.2 {micro}g/m{sup 3}, and this analysis will be directly traceable to analyses by NIST. The EPA traceability protocol document is divided into two separate sections. The first deals with the qualification of calibrator models by the vendors for use in mercury CEM calibration. The second describes the procedure that the vendors must use to certify the calibrators that meet the qualification specifications. The NIST traceable certification is performance based, traceable to analysis using isotope dilution inductively coupled plasma

A Review of Sensor Calibration Monitoring for Calibration Interval Extension in Nuclear Power Plants

Energy Technology Data Exchange (ETDEWEB)

Coble, Jamie B.; Meyer, Ryan M.; Ramuhalli, Pradeep; Bond, Leonard J.; Hashemian, Hash; Shumaker, Brent; Cummins, Dara

2012-08-31

Currently in the United States, periodic sensor recalibration is required for all safety-related sensors, typically occurring at every refueling outage, and it has emerged as a critical path item for shortening outage duration in some plants. Online monitoring can be employed to identify those sensors that require calibration, allowing for calibration of only those sensors that need it. International application of calibration monitoring, such as at the Sizewell B plant in United Kingdom, has shown that sensors may operate for eight years, or longer, within calibration tolerances. This issue is expected to also be important as the United States looks to the next generation of reactor designs (such as small modular reactors and advanced concepts), given the anticipated longer refueling cycles, proposed advanced sensors, and digital instrumentation and control systems. The U.S. Nuclear Regulatory Commission (NRC) accepted the general concept of online monitoring for sensor calibration monitoring in 2000, but no U.S. plants have been granted the necessary license amendment to apply it. This report presents a state-of-the-art assessment of online calibration monitoring in the nuclear power industry, including sensors, calibration practice, and online monitoring algorithms. This assessment identifies key research needs and gaps that prohibit integration of the NRC-approved online calibration monitoring system in the U.S. nuclear industry. Several needs are identified, including the quantification of uncertainty in online calibration assessment; accurate determination of calibration acceptance criteria and quantification of the effect of acceptance criteria variability on system performance; and assessment of the feasibility of using virtual sensor estimates to replace identified faulty sensors in order to extend operation to the next convenient maintenance opportunity. Understanding the degradation of sensors and the impact of this degradation on signals is key to

Optimal Reliability-Based Code Calibration

DEFF Research Database (Denmark)

Sørensen, John Dalsgaard; Kroon, I. B.; Faber, Michael Havbro

1994-01-01

Calibration of partial safety factors is considered in general, including classes of structures where no code exists beforehand. The partial safety factors are determined such that the difference between the reliability for the different structures in the class considered and a target reliability...... level is minimized. Code calibration on a decision theoretical basis is also considered and it is shown how target reliability indices can be calibrated. Results from code calibration for rubble mound breakwater designs are shown....

Observation models in radiocarbon calibration

International Nuclear Information System (INIS)

Jones, M.D.; Nicholls, G.K.

2001-01-01

The observation model underlying any calibration process dictates the precise mathematical details of the calibration calculations. Accordingly it is important that an appropriate observation model is used. Here this is illustrated with reference to the use of reservoir offsets where the standard calibration approach is based on a different model to that which the practitioners clearly believe is being applied. This sort of error can give rise to significantly erroneous calibration results. (author). 12 refs., 1 fig

Calibration and Data Analysis of the MC-130 Air Balance

Science.gov (United States)

Booth, Dennis; Ulbrich, N.

2012-01-01

Design, calibration, calibration analysis, and intended use of the MC-130 air balance are discussed. The MC-130 balance is an 8.0 inch diameter force balance that has two separate internal air flow systems and one external bellows system. The manual calibration of the balance consisted of a total of 1854 data points with both unpressurized and pressurized air flowing through the balance. A subset of 1160 data points was chosen for the calibration data analysis. The regression analysis of the subset was performed using two fundamentally different analysis approaches. First, the data analysis was performed using a recently developed extension of the Iterative Method. This approach fits gage outputs as a function of both applied balance loads and bellows pressures while still allowing the application of the iteration scheme that is used with the Iterative Method. Then, for comparison, the axial force was also analyzed using the Non-Iterative Method. This alternate approach directly fits loads as a function of measured gage outputs and bellows pressures and does not require a load iteration. The regression models used by both the extended Iterative and Non-Iterative Method were constructed such that they met a set of widely accepted statistical quality requirements. These requirements lead to reliable regression models and prevent overfitting of data because they ensure that no hidden near-linear dependencies between regression model terms exist and that only statistically significant terms are included. Finally, a comparison of the axial force residuals was performed. Overall, axial force estimates obtained from both methods show excellent agreement as the differences of the standard deviation of the axial force residuals are on the order of 0.001 % of the axial force capacity.

Outpatient rehabilitation as an intervention to improve employees' physical capacity.

Science.gov (United States)

Ojala, Birgitta; Nygård, Clas-Håkan; Nikkari, Seppo T

2016-01-01

The aging of the workforce poses new challenges for maintaining work ability. Because of limited information on the effectiveness of vocational rehabilitation performed in traditional inpatient programs, extended interest in outpatient rehabilitation has risen in the past few years. We examined the effects of a new outpatient rehabilitation program where every participant defined their own goals to improve work ability by the aid of a goal-oriented multi-professional team. This report will focus on the employees' physical capacity during a nine-month program. A total of 605 municipal employees from different production areas of the City of Tampere took part in the outpatient rehabilitation program, implemented by the occupational health unit. Groups of 12 employees participated in eight one-day sessions at intervals of two to three weeks; the final follow-up was 9 months from the beginning. Submaximal aerobic capacity was tested by a calibrated cycle ergometer with a commercial program (Aino Fitware pro, Helsinki, Finland). Musculoskeletal tests assessed muscle strength, balance and mobility. During the 9-month follow-up of the rehabilitation program, the employees' physical capacity was improved. The follow-up test scores from a total of 329 employees were significantly higher in the submaximal aerobic capacity test (p health situation to take part in physical capacity tests; however they took part in the intervention. The new outpatient rehabilitation program organized by the occupational health unit had a positive influence on employees' physical capacity during a nine-month follow up.

Isobaric specific heat capacity of water and aqueous cesium chloride solutions for temperatures between 298 K and 370 K at p = 0.1 MPa

International Nuclear Information System (INIS)

Lourenco, M.J.V.; Santos, F.J.V.; Ramires, M.L.V.; Nieto de Castro, C.A.

2006-01-01

There has been some controversy regarding the uncertainty of measurements of thermal properties using differential scanning calorimeters, namely heat capacity of liquids. A differential scanning calorimeter calibrated in enthalpy and temperature was used to measure the isobaric specific heat capacity of water and aqueous solutions of cesium chloride, in the temperature range 298 K to 370 K, for molalities up 3.2 mol . kg -1 , at p = 0.1 MPa, with an estimated uncertainty (ISO definition) better than 1.1%, at a 95% confidence level. The measurements are completely traceable to SI units of energy and temperature. The results obtained were correlated as a function of temperature and molality and compared with other authors, obtained by different methods and permit to conclude that a DSC calibrated by Joule effect is capable of very accurate measurements of the isobaric heat capacity of liquids, traceable to SI units of measurement

Poster — Thur Eve — 74: Distributed, asynchronous, reactive dosimetric and outcomes analysis using DICOMautomaton

International Nuclear Information System (INIS)

Clark, Haley; Wu, Jonn; Moiseenko, Vitali; Thomas, Steven

2014-01-01

Many have speculated about the future of computational technology in clinical radiation oncology. It has been advocated that the next generation of computational infrastructure will improve on the current generation by incorporating richer aspects of automation, more heavily and seamlessly featuring distributed and parallel computation, and providing more flexibility toward aggregate data analysis. In this report we describe how a recently created — but currently existing — analysis framework (DICOMautomaton) incorporates these aspects. DICOMautomaton supports a variety of use cases but is especially suited for dosimetric outcomes correlation analysis, investigation and comparison of radiotherapy treatment efficacy, and dose-volume computation. We describe: how it overcomes computational bottlenecks by distributing workload across a network of machines; how modern, asynchronous computational techniques are used to reduce blocking and avoid unnecessary computation; and how issues of out-of-date data are addressed using reactive programming techniques and data dependency chains. We describe internal architecture of the software and give a detailed demonstration of how DICOMautomaton could be used to search for correlations between dosimetric and outcomes data

Post-pneumonectomy empyema and dosimetric CT scan. Report of two cases and review of literature

International Nuclear Information System (INIS)

Latorzeff, I.; Bachaud, J.M.; Aziza, R.; Arboucalot, F.; Berjaud, J.; Dahan, M.; Giron, J.

1999-01-01

Following a pneumonectomy for cancer, the patients are classically observed by clinical examination and standard chest X-ray. However, torpid empyemas can be missed when they occur after the period of hospitalization and when they are not accompanied by a fever, At the time of postoperative radiotherapy, the dosimetric CT scan constitutes the first examination providing objective information of the endo-thoracic content. It is therefore necessary on this occasion to assure the normality of the post-pneumonectomy pleural space while checking that the substituted liquid is homogeneous and above all that the internal mediastinal part of the cavity has a concave appearance. If that is not the case, an empyema should be suspected. The diagnosis, confirmed by a cyto-bacteriological examination of the pleural fluid, constitutes a counter-indication of the radiotherapy. We present two cases of post-pneumonectomy pauci-symptomatic empyema which were diagnosed during the course of postoperative radiotherapy when the initial dosimetric CT scan was pathologic and could have allowed an earlier diagnosis. (author)

Chilean Nuclear Energy Commission dosimetric information system

International Nuclear Information System (INIS)

Guerrero Vallejos, Patricia Andrea

1997-01-01

This thesis discusses the nuclear radiation that people who work with radioactive material is exposed to and its control by the Chilean Nuclear Energy Commission. A full analysis of the System is presented with information about the Commission and the Department of Nuclear and Radiological Safety which runs the System. Ana analysis of the System is presented in order to obtain requirements. Management flow diagrams, the processes involved and current problems experienced by the users are described. A design logic is modeled producing Data Flow Diagrams (DFD). based on this physical design, or, Model of Physical Data, is prepared including tables, attributes, types of data, primary and foreign keys. A description is presented of how the System is implemented, the tools that are used and how the testing phase is carried out. The Dosimetry System meets the criteria for a Software Engineering project, where the basic cycle was used as a working methodology. The System developed supports the dosimetric control of people exposed to radioactive material. (author)

Dosimetric assessment of swallowing examinations with videofluoroscopy

International Nuclear Information System (INIS)

Costa, M.M.B.; Canevaro, L.V.; Azevedo, A.C.P.

2001-01-01

Dosimetric analysis measurements of the Dose-Area-Product (DAP) of 7 individuals were estimated for the deglutition dynamic using the videofluoroscopic method. The aim of this study is to establish in a preliminary way, typical DAP values for this kind of study. The DAP values were obtained attaching to the X ray tube exit, an ionization chamber from PTW and a Diamentor M4 meter. The typical DAP values obtained during the videofluoroscopic evaluation of the deglutition dynamic, including its three phases, was: 4101 ± 881 cGy.cm 2 and the typical DAP rate was 577 ± 94 cGy.cm 2 /min. These values refer to a standard patient (1.57 cm height, 56 kg. weight) and a protocol that can be performed in about 7 minutes. The values, defined herein as typical refer to the used protocol. To our knowledge, the mean DAP rate is a good parameter to estimate radiation exposure from videofluoroscopic study of swallowing process. (author)

Dosimetric evaluation program for dental radiology practices

International Nuclear Information System (INIS)

Gregori, B.; Milat, J.; Fernandez, J.; Micinquevich, S.; Andrieu, J.

1992-01-01

The preliminary results of a program undertaken to estimate the doses to patients associated with dental radiology practices in Argentine, are presented. Information collected from the search demonstrated that the Dieck and coronal techniques are the most commonly used practices, while all the examinations are performed by using a circular collimator. For both practices, the dosimetric studies were carried out on a Rando Alderson phantom. All dose measurements were made using thermoluminescent detectors LiF and Ca 2 F. In addition, a mathematical model was developed by applying the Monte Carlo method to a MIRD-V phantom. Circular and rectangular collimators were used. Absorbed dose distribution on head and neck, as well as surface dose distribution, were estimated. The comparison of the performance of both collimators shows that the use of the rectangular one allows for a dose reduction of 80%. Besides, a good correlation between the physical and mathematical models applied was found. (author)

Calibration simulation. A calibration Monte-Carlo program for the OPAL jet chamber

International Nuclear Information System (INIS)

Biebel, O.

1989-12-01

A calibration Monte Carlo program has been developed as a tool to investigate the interdependence of track reconstruction and calibration constants. Three categories of calibration effects have been considered: The precise knowledge of sense wire positions, necessary to reconstruct the particle trajectories in the jet chamber. Included are the staggering and the sag of the sense wires as well as tilts and rotations of their support structures. The various contributions to the measured drift time, with special emphasis on the aberration due to the track angle and the presence of a transverse magnetic field. A very precise knowledge of the drift velocity and the Lorentz angle of the drift paths with respect to the drift field is also required. The effects degrading particle identification via energy loss dE/dx. Impurities of the gas mixture and saturation effects depending on the track angle as well as the influence of the pulse shaping-electronics have been studied. These effects have been parametrised with coefficients corresponding to the calibration constants required for track reconstruction. Excellent agreement with the input data has been achieved when determining calibration constants from Monte Carlo data generated with these parametrisations. (orig.) [de

Portable compact multifunction IR calibrator

International Nuclear Information System (INIS)

Wyatt, C.L.; Jacobsen, L.; Steed, A.

1988-01-01

A compact portable multifunction calibrator designed for future sensor systems is described which enables a linearity calibration for all detectors simultaneously using a near small-area source, a high-resolution mapping of the focal plane with 10 microrad setability and with a blur of less than 100 microrad, system spectral response calibration (radiometer) using a Michelson interferometer source, relative spectral response (spectrometer) using high-temperature external commercial blackbody simulators, and an absolute calibration using an internal low-temperature extended-area source. 5 references

Physiotherapy ultrasound calibrations

International Nuclear Information System (INIS)

Gledhill, M.

1996-01-01

Calibration of physiotherapy ultrasound equipment has long been a problem. Numerous surveys around the world over the past 20 years have all found that only a low percentage of the units tested had an output within 30% of that indicatd. In New Zealand, a survey carried out by the NRL in 1985 found that only 24% had an output, at the maximum setting, within + or - 20% of that indicated. The present performance Standard for new equipment (NZS 3200.2.5:1992) requires that the measured output should not deviate from that indicated by more than + or - 30 %. This may be tightened to + or - 20% in the next few years. Any calibration is only as good as the calibration equipment. Some force balances can be tested with small weights to simulate the force exerted by an ultrasound beam, but with others this is not possible. For such balances, testing may only be feasible with a calibrated source which could be used like a transfer standard. (author). 4 refs., 3 figs

Calibration and verification of numerical runoff and erosion model

Directory of Open Access Journals (Sweden)

Gabrić Ognjen

2015-01-01

Full Text Available Based on the field and laboratory measurements, and analogous with development of computational techniques, runoff and erosion models based on equations which describe the physics of the process are also developed. Based on the KINEROS2 model, this paper presents basic modelling principles of runoff and erosion processes based on the St. Venant's equations. Alternative equations for friction calculation, calculation of source and deposition elements and transport capacity are also shown. Numerical models based on original and alternative equations are calibrated and verified on laboratory scale model. According to the results, friction calculation based on the analytic solution of laminar flow must be included in all runoff and erosion models.

Development of portable flow calibrator

International Nuclear Information System (INIS)

Akiyama, Kiyomitsu; Iijima, Nobuo

1995-01-01

In the nuclear facilities, air sniffer system is often utilized to evaluate atmospheric concentration of radioactivity in the working environment. The system collects airborne dust on the filter during some sampling period. In this method, total air flow during the sampling period is an important parameter to evaluate the radioactivity concentration correctly. Therefore, calibration for the flow meter of air sniffer system must be done periodically according to Japan Industry Standards (JIS). As we have had to available device to calibrate the flow meter in the working area, we had to remove the flow meters from the installed place and carry them to another place where calibration can be made. This work required a great deal of labor. Now we have developed a portable flow calibrator for air sniffer system which enables us to make in-site calibration of the flow meter in the working area more easily. This report describes the outline of portable flow calibrator and it's experimental results. (author)

Beam's-Eye-View Dosimetrics-Guided Inverse Planning for Aperture-Modulated Arc Therapy

International Nuclear Information System (INIS)

Ma Yunzhi; Popple, Richard; Suh, Tae-Suk; Xing Lei

2009-01-01

Purpose: To use angular beam's-eye-view dosimetrics (BEVD) information to improve the computational efficiency and plan quality of inverse planning of aperture-modulated arc therapy (AMAT). Methods and Materials: In BEVD-guided inverse planning, the angular space spanned by a rotational arc is represented by a large number of fixed-gantry beams with angular spacing of ∼2.5 degrees. Each beam is assigned with an initial aperture shape determined by the beam's-eye-view (BEV) projection of the planning target volume (PTV) and an initial weight. Instead of setting the beam weights arbitrarily, which slows down the subsequent optimization process and may result in a suboptimal solution, a priori knowledge about the quality of the beam directions derived from a BEVD is adopted to initialize the weights. In the BEVD calculation, a higher score is assigned to directions that allow more dose to be delivered to the PTV without exceeding the dose tolerances of the organs at risk (OARs) and vice versa. Simulated annealing is then used to optimize the segment shapes and weights. The BEVD-guided inverse planning is demonstrated by using two clinical cases, and the results are compared with those of a conventional approach without BEVD guidance. Results: An a priori knowledge-guided inverse planning scheme for AMAT is established. The inclusion of BEVD guidance significantly improves the convergence behavior of AMAT inverse planning and results in much better OAR sparing as compared with the conventional approach. Conclusions: BEVD-guidance facilitates AMAT treatment planning and provides a comprehensive tool to maximally use the technical capacity of the new arc therapeutic modality.

Thermal inertia and energy efficiency – Parametric simulation assessment on a calibrated case study

International Nuclear Information System (INIS)

Aste, Niccolò; Leonforte, Fabrizio; Manfren, Massimiliano; Mazzon, Manlio

2015-01-01

Highlights: • We perform a parametric simulation study on a calibrated building energy model. • We introduce adaptive shadings and night free cooling in simulations. • We analyze the effect of thermal capacity on the parametric simulations results. • We recognize that cooling demand and savings scales linearly with thermal capacity. • We assess the advantage of medium-heavy over medium and light configurations. - Abstract: The reduction of energy consumption for heating and cooling services in the existing building stock is a key challenge for global sustainability today and buildings’ envelopes retrofit is one the main issues. Most of the existing buildings’ envelopes have low levels of insulation, high thermal losses due to thermal bridges and cracks, absence of appropriate solar control, etc. Further, in building refurbishment, the importance of a system level approach is often undervalued in favour of simplistic “off the shelf” efficient solutions, focused on the reduction of thermal transmittance and on the enhancement of solar control capabilities. In many cases, the importance of the dynamic thermal properties is often neglected or underestimated and the effective thermal capacity is not properly considered as one of the design parameters. The research presented aims to critically assess the influence of the dynamic thermal properties of the building fabric (roof, walls and floors) on sensible heating and cooling energy demand for a case study. The case study chosen is an existing office building which has been retrofitted in recent years and whose energy model has been calibrated according to the data collected in the monitoring process. The research illustrates the variations of the sensible thermal energy demand of the building in different retrofit scenarios, and relates them to the variations of the dynamic thermal properties of the construction components. A parametric simulation study has been performed, encompassing the use of

Evaluation of Specific Absorption Rate as a Dosimetric Quantity for Electromagnetic Fields Bioeffects

OpenAIRE

Panagopoulos, Dimitris J.; Johansson, Olle; Carlo, George L.

2013-01-01

PURPOSE: To evaluate SAR as a dosimetric quantity for EMF bioeffects, and identify ways for increasing the precision in EMF dosimetry and bioactivity assessment. METHODS: We discuss the interaction of man-made electromagnetic waves with biological matter and calculate the energy transferred to a single free ion within a cell. We analyze the physics and biology of SAR and evaluate the methods of its estimation. We discuss the experimentally observed non-linearity between electromagnetic exposu...

Fuel conditioning facility electrorefiner volume calibration

International Nuclear Information System (INIS)

Bucher, R.G.; Orechwa, Y.

1995-01-01

In one of the electrometallurgical process steps of the Fuel Conditioning Facility (FCF), die in-process nuclear material is dissolved in the electrorefiner tank in an upper layer of a mixture of liquid LiCl-KCl salt and a lower layer of liquid cadmium. The electrorefiner tank, as most process tanks, is not a smooth right-circular cylinder for which a single linear volume calibration curve could be fitted over the whole height of the tank. Rather, the tank contains many internal components, which cause systematic deviations from a single linear function. The nominal operating temperature of the electrorefiner is 500 degrees C although the salt and cadmium are introduced at 410 degrees C. The operating materials and temperatures preclude multiple calibration runs at operating conditions. In order to maximize the calibration information, multiple calibration runs were performed with water at room temperature. These data allow identification of calibration segments, and preliminary estimation of the calibration function and calibration uncertainties. The final calibration function is based on a combination of data from die water calibrations and the measurements made during the filling of the electrorefiner with salt and cadmium for operation

NIST high-dose calibration services

International Nuclear Information System (INIS)

Humphreys, J.C.

1989-01-01

There is a need for the standardization of high-dose measurements used in the radiation-processing industry in order to provide assured traceability to national standards. NIST provides dosimetry calibration services to this industry. One of these services involves administration of known absorbed doses of gamma rays to customer-supplied dosimeters. The dosimeters are packaged to provide electron equilibrium conditions and are irradiated in a standard 60 Co calibration facility; this provides a calibration of that batch of dosimeters. Another service consists of supplying to a customer calibrated transfer dosimeters for irradiation with the customer's radiation source. The irradiated transfer dosimeters are then returned to NIST for analysis; the results are reported to the customer, providing a calibration of the dose rate of the customer's source. (orig.)

TIME CALIBRATED OSCILLOSCOPE SWEEP CIRCUIT

Science.gov (United States)

Smith, V.L.; Carstensen, H.K.

1959-11-24

An improved time calibrated sweep circuit is presented, which extends the range of usefulness of conventional oscilloscopes as utilized for time calibrated display applications in accordance with U. S. Patent No. 2,832,002. Principal novelty resides in the provision of a pair of separate signal paths, each of which is phase and amplitude adjustable, to connect a high-frequency calibration oscillator to the output of a sawtooth generator also connected to the respective horizontal deflection plates of an oscilloscope cathode ray tube. The amplitude and phase of the calibration oscillator signals in the two signal paths are adjusted to balance out feedthrough currents capacitively coupled at high frequencies of the calibration oscillator from each horizontal deflection plate to the vertical plates of the cathode ray tube.

Dosimetric of extremities with Dosemeters thermoluminescent in Cuba

International Nuclear Information System (INIS)

Molina Perez, D.; Diaz Bernal, E.; Vera Alonso, L.

1998-01-01

From final of the year 1995 in the CPHR implement the service of monitoring of the extremities using Dosemeter thermoluminescent (TL). The dosemeter consists on a metallic ring with a circular hole where a detector of LiF:Mg,Ti is placed (model JR1152C) of 5x5x0.9 mm 3 , covered by a fine layer of polyethylene. In the work the characteristic dosimetric as of the dosemeter is studied it satisfies the main requirements for their use in the monitoring from the exhibition to radiation photonic of the extremities. The doses are also presented registered during the first two years of operation of the service. The results obtained until the moment point out to you practice them of nuclear medicine, radiotherapy and production of substances radioactive how as of more contribution

Fractionated stereotactic radiotherapy: A method to evaluate geometric and dosimetric uncertainties using radiochromic films

International Nuclear Information System (INIS)

Coscia, Gianluca; Vaccara, Elena; Corvisiero, Roberta; Cavazzani, Paolo; Ruggieri, Filippo Grillo; Taccini, Gianni

2009-01-01

In the authors' hospital, stereotactic radiotherapy treatments are performed with a Varian Clinac 600C equipped with a BrainLAB m3 micro-multileaf-collimator generally using the dynamic conformal arc technique. Patient immobilization during the treatment is achieved with a fixation mask supplied by BrainLAB, made with two reinforced thermoplastic sheets fitting the patient's head. With this work the authors propose a method to evaluate treatment geometric accuracy and, consequently, to determine the amount of the margin to keep in the CTV-PTV expansion during the treatment planning. The reproducibility of the isocenter position was tested by simulating a complete treatment on the anthropomorphic phantom Alderson Rando, inserting in between two phantom slices a high sensitivity Gafchromic EBT film, properly prepared and calibrated, and repeating several treatment sessions, each time removing the fixing mask and replacing the film inside the phantom. The comparison between the dose distributions measured on films and computed by TPS, after a precise image registration procedure performed by a commercial piece of software (FILMQA, 3cognition LLC (Division of ISP), Wayne, NJ), allowed the authors to measure the repositioning errors, obtaining about 0.5 mm in case of central spherical PTV and about 1.5 mm in case of peripheral irregular PTV. Moreover, an evaluation of the errors in the registration procedure was performed, giving negligible values with respect to the quantities to be measured. The above intrinsic two-dimensional estimate of treatment accuracy has to be increased for the error in the third dimension, but the 2 mm margin the authors generally use for the CTV-PTV expansion seems adequate anyway. Using the same EBT films, a dosimetric verification of the treatment planning system was done. Measured dose values are larger or smaller than the nominal ones depending on geometric irradiation conditions, but, in the authors' experimental conditions, always

Lidar to lidar calibration

DEFF Research Database (Denmark)

Fernandez Garcia, Sergio; Villanueva, Héctor