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Détails du magazine
Format
Magazine
eISSN
1508-5791
Première publication
25 Mar 2014
Période de publication
4 fois par an
Langues
Anglais

Chercher

Volume 61 (2016): Edition 1 (March 2016)

Détails du magazine
Format
Magazine
eISSN
1508-5791
Première publication
25 Mar 2014
Période de publication
4 fois par an
Langues
Anglais

Chercher

14 Articles
Accès libre

The IOERT IntraLine accelerator – the development, current state, and future plans

Publié en ligne: 17 Mar 2016
Pages: 3 - 9

Résumé

Abstract

Intraoperative electron radiation therapy (IOERT) is a cancer treatment method that combines oncologic surgery with electron beam radiotherapy. This method can reduce the duration of entire tumor treatment and increase its effectiveness. Moreover, shortening the treatment time significantly reduces the cost and accessibility of the therapy. As a result of interdisciplinary research, an innovative accelerator for IOERT, the IntraLine, was developed. In the course of this work, four patent applications were filed. Today, the work is half way through. In the near future, the device will be optimized. New mechanical design solutions will be developed. Mechanical optimization will significantly reduce the weight of the device. Accelerators control system, which today is in the demo phase, will also be significantly upgraded. This paper describes the stages of the IntraLine accelerator development, its current state and plans for the future R&D work, within the scope of our new Intra-Dose project.

Mots clés

  • radiotherapy
  • mobile electron accelerator
  • intraoperative electron radiation therapy (IOERT)
Accès libre

Accelerator and detector physics at the Bern medical cyclotron and its beam transport line

Publié en ligne: 17 Mar 2016
Pages: 11 - 14

Résumé

Abstract

The cyclotron laboratory for radioisotope production and multi-disciplinary research at the Bern University Hospital (Inselspital) is based on an 18-MeV proton accelerator, equipped with a specifically conceived 6-m long external beam line, ending in a separate bunker. This facility allows performing daily positron emission tomography (PET) radioisotope production and research activities running in parallel. Some of the latest developments on accelerator and detector physics are reported. They encompass novel detectors for beam monitoring and studies of low current beams.

Mots clés

  • beam monitoring
  • medical cyclotrons
  • particle accelerators
  • particle detectors
Accès libre

Prediction of the cumulated dose for external beam irradiation of prostate cancer patients with 3D-CRT technique

Publié en ligne: 17 Mar 2016
Pages: 15 - 18

Résumé

Abstract

Nowadays in radiotherapy, much effort is taken to minimize the irradiated volume and consequently minimize doses to healthy tissues. In our work, we tested the hypothesis that the mean dose distribution calculated from a few first fractions can serve as prediction of the cumulated dose distribution, representing the whole treatment. We made our tests for 25 prostate cancer patients treated with three orthogonal fields technique. We did a comparison of dose distribution calculated as a sum of dose distribution from each fraction with a dose distribution calculated with isocenter shifted for a mean setup error from a few first fractions. The cumulative dose distribution and predicted dose distributions are similar in terms of gamma (3 mm 3%) analysis, under condition that we know setup error from seven first fractions. We showed that the dose distribution calculated for the original plan with the isocenter shifted to the point, defined as the original isocenter corrected of the mean setup error estimated from the first seven fractions supports our hypothesis, i.e. can serve as a prediction for cumulative dose distribution.

Mots clés

  • 3D-CRT
  • cumulative dose
  • dose prediction
  • setup error
  • individualized margins
Accès libre

Application of instruments of nuclear physics to the calculation of theoretical dose distributions in various organs of the human body for beams used in hadrontherapy

Publié en ligne: 17 Mar 2016
Pages: 19 - 22

Résumé

Abstract

The area of interests of nuclear physics are studies of reactions, wherein atomic nuclei of projectile collide with target nuclei. An amount of energy lost by projectile nucleus during its passing through the target is a major issue – it is important to know how charged particles interact with matter. It is possible to afford this knowledge by using theoretical programs that calculate energy loss applying the Bethe-Bloch equation. Hadrontherapy, which is a field of still growing interest, is based on the interactions of charged particles with matter. Therefore, there exists a need of creating a simple model that could be used to the calculation of dose distributions in biological matter. Two programs (SRIM, Xeloss), used to the calculation of energy loss by nuclear physicist, have been adapted to determine the dose distributions in analogues of human tissues. Results of the calculations with those programs for beams used in hadrontherapy (e.g. 1H, 12C) will be compared with experimental data available in references.

Mots clés

  • carbon ions
  • hadrontherapy
  • hydrogen ions
  • SRIM
  • Xeloss
Accès libre

Ambient dose equivalent measurements in secondary radiation fields at proton therapy facility CCB IFJ PAN in Krakow using recombination chambers

Publié en ligne: 17 Mar 2016
Pages: 23 - 28

Résumé

Abstract

This work presents recombination methods used for secondary radiation measurements at the Facility for Proton Radiotherapy of Eye Cancer at the Institute for Nuclear Physics, IFJ, in Krakow (Poland). The measurements of H*(10) were performed, with REM-2 tissue equivalent chamber in two halls of cyclotrons AIC-144 and Proteus C-235 and in the corridors close to treatment rooms. The measurements were completed by determination of gamma radiation component, using a hydrogen-free recombination chamber. The results were compared with the measurements using rem meter types FHT 762 (WENDI-II) and NM2 FHT 192 gamma probe and with stationary dosimetric system.

Mots clés

  • recombination chambers
  • workplace monitoring
  • proton therapy
Accès libre

Synthesis of 11C-methionine through gas phase iodination using Synthra MeIPlus synthesis module

Publié en ligne: 17 Mar 2016
Pages: 29 - 33

Résumé

Abstract

A method of 11C-methionine synthesis using ‘bubbling’ method is presented. 11C-methionine was synthesized via 11C methylation from L-cysteine thiolactone (2 mg) in a 300 μL solution of 2:1:1 (v/v) 1 M NaOH, ethanol, and water at ambient temperature (85°C, 5 min). The radiochemical purity of radiotracer was higher than 99% and enantiomeric purity (L-11C-methionine) was 91.6 ± 0.4%. The final product met the requirements of European Pharmacopoeia monograph. The proposed 11C-methionine synthesis is a reliable tool for routine manufacturing in clinical applications and animal studies.

Mots clés

  • C-methionine
  • C-radiopharmaceuticals
  • gas phase iodination
Accès libre

Application of the compress sensing theory for improvement of the TOF resolution in a novel J-PET instrument

Publié en ligne: 17 Mar 2016
Pages: 35 - 39

Résumé

Abstract

Nowadays, in positron emission tomography (PET) systems, a time of flight (TOF) information is used to improve the image reconstruction process. In TOF-PET, fast detectors are able to measure the difference in the arrival time of the two gamma rays, with the precision enabling to shorten significantly a range along the line-of-response (LOR) where the annihilation occurred. In the new concept, called J-PET scanner, gamma rays are detected in plastic scintillators. In a single strip of J-PET system, time values are obtained by probing signals in the amplitude domain. Owing to compressive sensing (CS) theory, information about the shape and amplitude of the signals is recovered. In this paper, we demonstrate that based on the acquired signals parameters, a better signal normalization may be provided in order to improve the TOF resolution. The procedure was tested using large sample of data registered by a dedicated detection setup enabling sampling of signals with 50-ps intervals. Experimental setup provided irradiation of a chosen position in the plastic scintillator strip with annihilation gamma quanta.

Mots clés

  • compressed sensing
  • positron emission tomography
  • time of flight
Accès libre

Compressed sensing in MRI – mathematical preliminaries and basic examples

Publié en ligne: 17 Mar 2016
Pages: 41 - 43

Résumé

Abstract

In magnetic resonance imaging (MRI), k-space sampling, due to physical restrictions, is very time-consuming. It cannot be much improved using classical Nyquist-based sampling theory. Recent developments utilize the fact that MR images are sparse in some representations (i.e. wavelet coefficients). This new theory, created by Candès and Romberg, called compressed sensing (CS), shows that images with sparse representations can be recovered from randomly undersampled k-space data, by using nonlinear reconstruction algorithms (i.e. l1-norm minimization). Throughout this paper, mathematical preliminaries of CS are outlined, in the form introduced by Candès. We describe the main conditions for measurement matrices and recovery algorithms and present a basic example, showing that while the method really works (reducing the time of MR examination), there are some major problems that need to be taken into consideration.

Mots clés

  • compressed sensing
  • magnetic resonance imaging
  • sampling theory
  • sparsity
Accès libre

Numerical model of thyroid counter

Publié en ligne: 17 Mar 2016
Pages: 45 - 47

Résumé

Abstract

The aim of this study was to develop a numerical model of spectrometric thyroid counter, which is used for the measurements of internal contamination by in vivo method. The modeled detector is used for a routine internal exposure monitoring procedure in the Radiation Protection Measurements Laboratory of National Centre for Nuclear Research (NCBJ). This procedure may also be used for monitoring of occupationally exposed nuclear medicine personnel. The developed model was prepared using Monte Carlo code FLUKA 2011 ver. 2b.6 Apr-14 and FLAIR ver. 1.2-5 interface. It contains a scintillation NaI(Tl) detector, the collimator and the thyroid water phantom with a reference source of iodine 131I. The geometry of the model was designed and a gamma energy spectrum of iodine 131I deposited in the detector was calculated.

Mots clés

  • iodine
  • Monte Carlo
  • FLUKA
  • gamma spectrometry
  • thyroid phantom
Accès libre

Analysis of dosimetric peaks of MgB4O7:Dy (40% Teflon) versus LiF:Mg,Ti TL detectors

Publié en ligne: 17 Mar 2016
Pages: 49 - 52

Résumé

Abstract

Magnesium tetraborate doped with dysprosium (MgB4O7:Dy) is known as a good thermoluminophor for personal dosimetry of gamma ray and X-ray radiation because of its high sensitivity and close tissue equivalence. This material can be produced by different routes. The sintered pastilles of magnesium tetraborate mixed with Teflon (40%) used in this work were manufactured at the Federal University of Sergipe, Department of Physics by the solid-state synthesis. Magnesium tetraborate was already used for high-dose dosimetry, exhibiting linearity for a wide range of doses. In this work, the authors examined its main characteristics prior to potential use of detectors in everyday dosimetry, comparing this material to a widely used LiF:Mg,Ti phosphor. The following tests influencing dosimetric peaks of MgB4O7:Dy were presented: (1) the shape of the glow curves, (2) annealing conditions and post-irradiation annealing and its influence for background of the detectors, (3) the choice of the heating rates at the read-out and (4) the threshold dose, that is, the lowest possible dose to be measured. Similar tests were performed with LiF:Mg,Ti detectors, produced and widely used in Poland. The results were compared and discussed.

Mots clés

  • thermoluminescent detectors
  • MgBO:Dy
  • LiF:Mg,Ti
Accès libre

The threshold contrast thickness evaluated with different CDMAM phantoms and software

Publié en ligne: 17 Mar 2016
Pages: 53 - 59

Résumé

Abstract

The image quality in digital mammography is described by specifying the thickness and diameter of disks with threshold visibility. The European Commission recommends the CDMAM phantom as a tool to evaluate threshold contrast visibility in digital mammography [1, 2]. Inaccuracy of the manufacturing process of CDMAM 3.4 phantoms (Artinis Medical System BV), as well as differences between software used to analyze the images, may lead to discrepancies in the evaluation of threshold contrast visibility. The authors of this work used three CDMAM 3.4 phantoms with serial numbers 1669, 1840, and 1841 and two mammography systems of the same manufacturer with an identical types of detectors. The images were analyzed with EUREF software (version 1.5.5 with CDCOM 1.6. exe file) and Artinis software (version 1.2 with CDCOM 1.6. exe file). The differences between the observed thicknesses of the threshold contrast structures, which were caused by differences between the CDMAM 3.4 phantoms, were not reproduced in the same way on two mammography units of the same type. The thickness reported by the Artinis software (version 1.2 with CDCOM 1.6. exe file) was generally greater than the one determined by the EUREF software (version 1.5.5 with CDCOM 1.6. exe file), but the ratio of the results depended on the phantom and diameter of the structure. It was not possible to establish correction factors, which would allow correction of the differences between the results obtained for different CDMAM 3.4 phantoms, or to correct the differences between software. Great care must be taken when results of the tests performed with different CDMAM 3.4 phantoms and with different software application are interpreted.

Mots clés

  • CDMAM phantom
  • digital mammography
  • threshold visibility
Accès libre

Application of the Böhm chamber for reference beta dose measurements and the calibration of personal dosimeters

Publié en ligne: 17 Mar 2016
Pages: 61 - 67

Résumé

Abstract

Thermoluminescent dosimeters (TLDs) currently used in personal and area dosimetry are often utilized to measure doses of ionizing radiation in fields with a more complex structure and therefore they should be calibrated in relation to different radiation types. The results of such calibration presented for UD-813 TLDs allowed for evaluation of their capability in relation to different radiation types like the beta and photon radiation of different energies and neutron radiation generated by the 241Am-Be source. The detector response for 60 keV photons was 10% higher than for the 662 keV gamma radiation of 137Cs. There were also response differences in relation to photon and beta radiation between detectors with an enhanced concentration of lithium 6Li and boron 10B and detectors containing a natural level of these isotopes. Measurements of the reference beta doses were performed with the help of the Böhm chamber. This method is relatively more complicated compared to determining the reference photon and neutron doses and is described thoroughly in this paper. The corrected current measured by the Böhm chamber for the chosen parameters was a linear function for an entire available range of the chamber depths. The percentage of errors related to the evaluated reference beta doses were below 2% despite a rather large number of corrections that should be taken into account. The calibration distances varied from 11 cm to 50 cm. For this range and beta particle energy, the absorption of radiation in the air was negligible and their attenuation had a predominantly geometric character.

Mots clés

  • beta radiation
  • Böhm chamber
  • mixed fields
  • Panasonic TLDs
Accès libre

New amino bisphosphonate compound for skeletal imaging: Comparison study with methylenediphosphonic acid (MDP) and (1-hydroxyethane-1,1-diyl) diphosphonic acid (HEDP)

Publié en ligne: 17 Mar 2016
Pages: 69 - 74

Résumé

Abstract

A novel bisphosphonate derivative (1-aminoethane-1,1-diyl)diphosphonic acid (AEDP) has been prepared and successfully labeled with 99mTc at high labeling yields. The in vivo biodistribution of 99mTc-AEDP has been investigated and compared with two reference compounds Tc-99m methylene diphosphonate (99mTc-MDP) and Tc-99m (1-hydroxyethylidene) diphosphonate (99mTc-HEDP). The biodistribution studies have demonstrated a high uptake of the radiotracer 99mTc-AEDP in the bone and a rapid clearance from the blood (such as the two technetium-labeled bone imaging agents in current use: 99mTc-MDP and 99mTc-HEDP). Additionally, the scintigraphic images of 99mTc-AEDP in normal rats have revealed high selective skeletal uptake.

Mots clés

  • aminoethylidenediphosphonic acid
  • biodistribution
  • bisphosphonates
  • bone imaging agent
  • radiolabeling
Accès libre

Preliminary PM2.5 and PM10 fractions source apportionment complemented by statistical accuracy determination

Publié en ligne: 17 Mar 2016
Pages: 75 - 83

Résumé

Abstract

Samples of PM10 and PM2.5 fractions were collected between the years 2010 and 2013 at the urban area of Krakow, Poland. Numerous types of air pollution sources are present at the site; these include steel and cement industries, traffic, municipal emission sources and biomass burning. Energy dispersive X-ray fluorescence was used to determine the concentrations of the following elements: Cl, K, Ca, Ti, Mn, Fe, Ni, Cu, Zn, Br, Rb, Sr, As and Pb within the collected samples. Defining the elements as indicators, airborne particulate matter (APM) source profiles were prepared by applying principal component analysis (PCA), factor analysis (FA) and multiple linear regression (MLR). Four different factors identifying possible air pollution sources for both PM10 and PM2.5 fractions were attributed to municipal emissions, biomass burning, steel industry, traffic, cement and metal industry, Zn and Pb industry and secondary aerosols. The uncertainty associated with each loading was determined by a statistical simulation method that took into account the individual elemental concentrations and their corresponding uncertainties. It will be possible to identify two or more sources of air particulate matter pollution for a single factor in case it is extremely difficult to separate the sources.

Mots clés

  • chemical analysis
  • particulate matter
  • source identification
14 Articles
Accès libre

The IOERT IntraLine accelerator – the development, current state, and future plans

Publié en ligne: 17 Mar 2016
Pages: 3 - 9

Résumé

Abstract

Intraoperative electron radiation therapy (IOERT) is a cancer treatment method that combines oncologic surgery with electron beam radiotherapy. This method can reduce the duration of entire tumor treatment and increase its effectiveness. Moreover, shortening the treatment time significantly reduces the cost and accessibility of the therapy. As a result of interdisciplinary research, an innovative accelerator for IOERT, the IntraLine, was developed. In the course of this work, four patent applications were filed. Today, the work is half way through. In the near future, the device will be optimized. New mechanical design solutions will be developed. Mechanical optimization will significantly reduce the weight of the device. Accelerators control system, which today is in the demo phase, will also be significantly upgraded. This paper describes the stages of the IntraLine accelerator development, its current state and plans for the future R&D work, within the scope of our new Intra-Dose project.

Mots clés

  • radiotherapy
  • mobile electron accelerator
  • intraoperative electron radiation therapy (IOERT)
Accès libre

Accelerator and detector physics at the Bern medical cyclotron and its beam transport line

Publié en ligne: 17 Mar 2016
Pages: 11 - 14

Résumé

Abstract

The cyclotron laboratory for radioisotope production and multi-disciplinary research at the Bern University Hospital (Inselspital) is based on an 18-MeV proton accelerator, equipped with a specifically conceived 6-m long external beam line, ending in a separate bunker. This facility allows performing daily positron emission tomography (PET) radioisotope production and research activities running in parallel. Some of the latest developments on accelerator and detector physics are reported. They encompass novel detectors for beam monitoring and studies of low current beams.

Mots clés

  • beam monitoring
  • medical cyclotrons
  • particle accelerators
  • particle detectors
Accès libre

Prediction of the cumulated dose for external beam irradiation of prostate cancer patients with 3D-CRT technique

Publié en ligne: 17 Mar 2016
Pages: 15 - 18

Résumé

Abstract

Nowadays in radiotherapy, much effort is taken to minimize the irradiated volume and consequently minimize doses to healthy tissues. In our work, we tested the hypothesis that the mean dose distribution calculated from a few first fractions can serve as prediction of the cumulated dose distribution, representing the whole treatment. We made our tests for 25 prostate cancer patients treated with three orthogonal fields technique. We did a comparison of dose distribution calculated as a sum of dose distribution from each fraction with a dose distribution calculated with isocenter shifted for a mean setup error from a few first fractions. The cumulative dose distribution and predicted dose distributions are similar in terms of gamma (3 mm 3%) analysis, under condition that we know setup error from seven first fractions. We showed that the dose distribution calculated for the original plan with the isocenter shifted to the point, defined as the original isocenter corrected of the mean setup error estimated from the first seven fractions supports our hypothesis, i.e. can serve as a prediction for cumulative dose distribution.

Mots clés

  • 3D-CRT
  • cumulative dose
  • dose prediction
  • setup error
  • individualized margins
Accès libre

Application of instruments of nuclear physics to the calculation of theoretical dose distributions in various organs of the human body for beams used in hadrontherapy

Publié en ligne: 17 Mar 2016
Pages: 19 - 22

Résumé

Abstract

The area of interests of nuclear physics are studies of reactions, wherein atomic nuclei of projectile collide with target nuclei. An amount of energy lost by projectile nucleus during its passing through the target is a major issue – it is important to know how charged particles interact with matter. It is possible to afford this knowledge by using theoretical programs that calculate energy loss applying the Bethe-Bloch equation. Hadrontherapy, which is a field of still growing interest, is based on the interactions of charged particles with matter. Therefore, there exists a need of creating a simple model that could be used to the calculation of dose distributions in biological matter. Two programs (SRIM, Xeloss), used to the calculation of energy loss by nuclear physicist, have been adapted to determine the dose distributions in analogues of human tissues. Results of the calculations with those programs for beams used in hadrontherapy (e.g. 1H, 12C) will be compared with experimental data available in references.

Mots clés

  • carbon ions
  • hadrontherapy
  • hydrogen ions
  • SRIM
  • Xeloss
Accès libre

Ambient dose equivalent measurements in secondary radiation fields at proton therapy facility CCB IFJ PAN in Krakow using recombination chambers

Publié en ligne: 17 Mar 2016
Pages: 23 - 28

Résumé

Abstract

This work presents recombination methods used for secondary radiation measurements at the Facility for Proton Radiotherapy of Eye Cancer at the Institute for Nuclear Physics, IFJ, in Krakow (Poland). The measurements of H*(10) were performed, with REM-2 tissue equivalent chamber in two halls of cyclotrons AIC-144 and Proteus C-235 and in the corridors close to treatment rooms. The measurements were completed by determination of gamma radiation component, using a hydrogen-free recombination chamber. The results were compared with the measurements using rem meter types FHT 762 (WENDI-II) and NM2 FHT 192 gamma probe and with stationary dosimetric system.

Mots clés

  • recombination chambers
  • workplace monitoring
  • proton therapy
Accès libre

Synthesis of 11C-methionine through gas phase iodination using Synthra MeIPlus synthesis module

Publié en ligne: 17 Mar 2016
Pages: 29 - 33

Résumé

Abstract

A method of 11C-methionine synthesis using ‘bubbling’ method is presented. 11C-methionine was synthesized via 11C methylation from L-cysteine thiolactone (2 mg) in a 300 μL solution of 2:1:1 (v/v) 1 M NaOH, ethanol, and water at ambient temperature (85°C, 5 min). The radiochemical purity of radiotracer was higher than 99% and enantiomeric purity (L-11C-methionine) was 91.6 ± 0.4%. The final product met the requirements of European Pharmacopoeia monograph. The proposed 11C-methionine synthesis is a reliable tool for routine manufacturing in clinical applications and animal studies.

Mots clés

  • C-methionine
  • C-radiopharmaceuticals
  • gas phase iodination
Accès libre

Application of the compress sensing theory for improvement of the TOF resolution in a novel J-PET instrument

Publié en ligne: 17 Mar 2016
Pages: 35 - 39

Résumé

Abstract

Nowadays, in positron emission tomography (PET) systems, a time of flight (TOF) information is used to improve the image reconstruction process. In TOF-PET, fast detectors are able to measure the difference in the arrival time of the two gamma rays, with the precision enabling to shorten significantly a range along the line-of-response (LOR) where the annihilation occurred. In the new concept, called J-PET scanner, gamma rays are detected in plastic scintillators. In a single strip of J-PET system, time values are obtained by probing signals in the amplitude domain. Owing to compressive sensing (CS) theory, information about the shape and amplitude of the signals is recovered. In this paper, we demonstrate that based on the acquired signals parameters, a better signal normalization may be provided in order to improve the TOF resolution. The procedure was tested using large sample of data registered by a dedicated detection setup enabling sampling of signals with 50-ps intervals. Experimental setup provided irradiation of a chosen position in the plastic scintillator strip with annihilation gamma quanta.

Mots clés

  • compressed sensing
  • positron emission tomography
  • time of flight
Accès libre

Compressed sensing in MRI – mathematical preliminaries and basic examples

Publié en ligne: 17 Mar 2016
Pages: 41 - 43

Résumé

Abstract

In magnetic resonance imaging (MRI), k-space sampling, due to physical restrictions, is very time-consuming. It cannot be much improved using classical Nyquist-based sampling theory. Recent developments utilize the fact that MR images are sparse in some representations (i.e. wavelet coefficients). This new theory, created by Candès and Romberg, called compressed sensing (CS), shows that images with sparse representations can be recovered from randomly undersampled k-space data, by using nonlinear reconstruction algorithms (i.e. l1-norm minimization). Throughout this paper, mathematical preliminaries of CS are outlined, in the form introduced by Candès. We describe the main conditions for measurement matrices and recovery algorithms and present a basic example, showing that while the method really works (reducing the time of MR examination), there are some major problems that need to be taken into consideration.

Mots clés

  • compressed sensing
  • magnetic resonance imaging
  • sampling theory
  • sparsity
Accès libre

Numerical model of thyroid counter

Publié en ligne: 17 Mar 2016
Pages: 45 - 47

Résumé

Abstract

The aim of this study was to develop a numerical model of spectrometric thyroid counter, which is used for the measurements of internal contamination by in vivo method. The modeled detector is used for a routine internal exposure monitoring procedure in the Radiation Protection Measurements Laboratory of National Centre for Nuclear Research (NCBJ). This procedure may also be used for monitoring of occupationally exposed nuclear medicine personnel. The developed model was prepared using Monte Carlo code FLUKA 2011 ver. 2b.6 Apr-14 and FLAIR ver. 1.2-5 interface. It contains a scintillation NaI(Tl) detector, the collimator and the thyroid water phantom with a reference source of iodine 131I. The geometry of the model was designed and a gamma energy spectrum of iodine 131I deposited in the detector was calculated.

Mots clés

  • iodine
  • Monte Carlo
  • FLUKA
  • gamma spectrometry
  • thyroid phantom
Accès libre

Analysis of dosimetric peaks of MgB4O7:Dy (40% Teflon) versus LiF:Mg,Ti TL detectors

Publié en ligne: 17 Mar 2016
Pages: 49 - 52

Résumé

Abstract

Magnesium tetraborate doped with dysprosium (MgB4O7:Dy) is known as a good thermoluminophor for personal dosimetry of gamma ray and X-ray radiation because of its high sensitivity and close tissue equivalence. This material can be produced by different routes. The sintered pastilles of magnesium tetraborate mixed with Teflon (40%) used in this work were manufactured at the Federal University of Sergipe, Department of Physics by the solid-state synthesis. Magnesium tetraborate was already used for high-dose dosimetry, exhibiting linearity for a wide range of doses. In this work, the authors examined its main characteristics prior to potential use of detectors in everyday dosimetry, comparing this material to a widely used LiF:Mg,Ti phosphor. The following tests influencing dosimetric peaks of MgB4O7:Dy were presented: (1) the shape of the glow curves, (2) annealing conditions and post-irradiation annealing and its influence for background of the detectors, (3) the choice of the heating rates at the read-out and (4) the threshold dose, that is, the lowest possible dose to be measured. Similar tests were performed with LiF:Mg,Ti detectors, produced and widely used in Poland. The results were compared and discussed.

Mots clés

  • thermoluminescent detectors
  • MgBO:Dy
  • LiF:Mg,Ti
Accès libre

The threshold contrast thickness evaluated with different CDMAM phantoms and software

Publié en ligne: 17 Mar 2016
Pages: 53 - 59

Résumé

Abstract

The image quality in digital mammography is described by specifying the thickness and diameter of disks with threshold visibility. The European Commission recommends the CDMAM phantom as a tool to evaluate threshold contrast visibility in digital mammography [1, 2]. Inaccuracy of the manufacturing process of CDMAM 3.4 phantoms (Artinis Medical System BV), as well as differences between software used to analyze the images, may lead to discrepancies in the evaluation of threshold contrast visibility. The authors of this work used three CDMAM 3.4 phantoms with serial numbers 1669, 1840, and 1841 and two mammography systems of the same manufacturer with an identical types of detectors. The images were analyzed with EUREF software (version 1.5.5 with CDCOM 1.6. exe file) and Artinis software (version 1.2 with CDCOM 1.6. exe file). The differences between the observed thicknesses of the threshold contrast structures, which were caused by differences between the CDMAM 3.4 phantoms, were not reproduced in the same way on two mammography units of the same type. The thickness reported by the Artinis software (version 1.2 with CDCOM 1.6. exe file) was generally greater than the one determined by the EUREF software (version 1.5.5 with CDCOM 1.6. exe file), but the ratio of the results depended on the phantom and diameter of the structure. It was not possible to establish correction factors, which would allow correction of the differences between the results obtained for different CDMAM 3.4 phantoms, or to correct the differences between software. Great care must be taken when results of the tests performed with different CDMAM 3.4 phantoms and with different software application are interpreted.

Mots clés

  • CDMAM phantom
  • digital mammography
  • threshold visibility
Accès libre

Application of the Böhm chamber for reference beta dose measurements and the calibration of personal dosimeters

Publié en ligne: 17 Mar 2016
Pages: 61 - 67

Résumé

Abstract

Thermoluminescent dosimeters (TLDs) currently used in personal and area dosimetry are often utilized to measure doses of ionizing radiation in fields with a more complex structure and therefore they should be calibrated in relation to different radiation types. The results of such calibration presented for UD-813 TLDs allowed for evaluation of their capability in relation to different radiation types like the beta and photon radiation of different energies and neutron radiation generated by the 241Am-Be source. The detector response for 60 keV photons was 10% higher than for the 662 keV gamma radiation of 137Cs. There were also response differences in relation to photon and beta radiation between detectors with an enhanced concentration of lithium 6Li and boron 10B and detectors containing a natural level of these isotopes. Measurements of the reference beta doses were performed with the help of the Böhm chamber. This method is relatively more complicated compared to determining the reference photon and neutron doses and is described thoroughly in this paper. The corrected current measured by the Böhm chamber for the chosen parameters was a linear function for an entire available range of the chamber depths. The percentage of errors related to the evaluated reference beta doses were below 2% despite a rather large number of corrections that should be taken into account. The calibration distances varied from 11 cm to 50 cm. For this range and beta particle energy, the absorption of radiation in the air was negligible and their attenuation had a predominantly geometric character.

Mots clés

  • beta radiation
  • Böhm chamber
  • mixed fields
  • Panasonic TLDs
Accès libre

New amino bisphosphonate compound for skeletal imaging: Comparison study with methylenediphosphonic acid (MDP) and (1-hydroxyethane-1,1-diyl) diphosphonic acid (HEDP)

Publié en ligne: 17 Mar 2016
Pages: 69 - 74

Résumé

Abstract

A novel bisphosphonate derivative (1-aminoethane-1,1-diyl)diphosphonic acid (AEDP) has been prepared and successfully labeled with 99mTc at high labeling yields. The in vivo biodistribution of 99mTc-AEDP has been investigated and compared with two reference compounds Tc-99m methylene diphosphonate (99mTc-MDP) and Tc-99m (1-hydroxyethylidene) diphosphonate (99mTc-HEDP). The biodistribution studies have demonstrated a high uptake of the radiotracer 99mTc-AEDP in the bone and a rapid clearance from the blood (such as the two technetium-labeled bone imaging agents in current use: 99mTc-MDP and 99mTc-HEDP). Additionally, the scintigraphic images of 99mTc-AEDP in normal rats have revealed high selective skeletal uptake.

Mots clés

  • aminoethylidenediphosphonic acid
  • biodistribution
  • bisphosphonates
  • bone imaging agent
  • radiolabeling
Accès libre

Preliminary PM2.5 and PM10 fractions source apportionment complemented by statistical accuracy determination

Publié en ligne: 17 Mar 2016
Pages: 75 - 83

Résumé

Abstract

Samples of PM10 and PM2.5 fractions were collected between the years 2010 and 2013 at the urban area of Krakow, Poland. Numerous types of air pollution sources are present at the site; these include steel and cement industries, traffic, municipal emission sources and biomass burning. Energy dispersive X-ray fluorescence was used to determine the concentrations of the following elements: Cl, K, Ca, Ti, Mn, Fe, Ni, Cu, Zn, Br, Rb, Sr, As and Pb within the collected samples. Defining the elements as indicators, airborne particulate matter (APM) source profiles were prepared by applying principal component analysis (PCA), factor analysis (FA) and multiple linear regression (MLR). Four different factors identifying possible air pollution sources for both PM10 and PM2.5 fractions were attributed to municipal emissions, biomass burning, steel industry, traffic, cement and metal industry, Zn and Pb industry and secondary aerosols. The uncertainty associated with each loading was determined by a statistical simulation method that took into account the individual elemental concentrations and their corresponding uncertainties. It will be possible to identify two or more sources of air particulate matter pollution for a single factor in case it is extremely difficult to separate the sources.

Mots clés

  • chemical analysis
  • particulate matter
  • source identification

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