Maria Amor Duch - Academia.edu (original) (raw)

Papers by Maria Amor Duch

Research paper thumbnail of Low dose response results and detection limits of the EURADOS intercomparison IC2021area for passive H*(10) area dosemeters

Research paper thumbnail of EJP-CONCERT European Joint Programme for the Integration of Radiation Protection Research H 2020 – 662287 D 9 . 106 – Guidelines for implementing the workplace geometry and the radiation field map in the dosimetry application Part 1 : Workplace geometry

Research paper thumbnail of Feasibility study of computational occupational dosimetry: evaluating a proof-of-concept in an endovascular and interventional cardiology setting

Journal of Radiological Protection

Individual monitoring of radiation workers is essential to ensure compliance with legal dose limi... more Individual monitoring of radiation workers is essential to ensure compliance with legal dose limits and to ensure that doses are As Low As Reasonably Achievable. However, large uncertainties still exist in personal dosimetry and there are issues with compliance and incorrect wearing of dosimeters. The objective of the PODIUM (Personal Online Dosimetry Using Computational Methods) project was to improve personal dosimetry by an innovative approach: the development of an online dosimetry application based on computer simulations without the use of physical dosimeters. Occupational doses were calculated based on the use of camera tracking devices, flexible individualised phantoms and data from the radiation source. When combined with fast Monte Carlo simulation codes, the aim was to perform personal dosimetry in real-time. A key component of the PODIUM project was to assess and validate the methodology in interventional radiology workplaces where improvements in dosimetry are needed. T...

Research paper thumbnail of Overview of passive area dosimetry systems used in European countries

The European Radiation Dosimetry e.V. is a non-profit organization promoting research and develop... more The European Radiation Dosimetry e.V. is a non-profit organization promoting research and development and European cooperation in the field of the dosimetry of ionizing radiation. It is registered in the Register of Associations (Amtsgericht München, registry number VR 207982) and certified to be of non-profit character (Finanzamt München, notification from 2020-10-29). Liability Disclaimer No liability will be undertaken for completeness, editorial or technical mistakes, omissions as well as for correctness of the contents.

Research paper thumbnail of Coincidence summing corrections for volume samples using the PENELOPE/penEasy Monte Carlo code

Applied Radiation and Isotopes, 2014

Computation of coincidence summing corrections for peaks of 152 Eu and 134 Cs. The MC penEasy cod... more Computation of coincidence summing corrections for peaks of 152 Eu and 134 Cs. The MC penEasy code has been modified to include the coincidence summing effect. The correction factors have been obtained with PENELOPE/penEasy MC code. Results have been validated using an ICRM intercomparison.

Research paper thumbnail of Dose distributions in SBRT of lung tumors: Comparison between two different treatment planning algorithms and Monte-Carlo simulation including breathing motions

Acta Oncologica, 2006

In stereotactic body radiotherapy (SBRT) of lung tumors, dosimetric problems arise from: 1) the l... more In stereotactic body radiotherapy (SBRT) of lung tumors, dosimetric problems arise from: 1) the limited accuracy in the dose calculation algorithms in treatment planning systems, and 2) the motions with the respiration of the tumor during treatment. Longitudinal dose distributions have been calculated with Monte Carlo simulation (MC), a pencil beam algorithm (PB) and a collapsed cone algorithm (CC) for two spherical lung tumors (2 cm and 5 cm diameter) in lung tissue, in a phantom situation. Respiratory motions were included by a convolution method, which was validated. In the static situation, the PB significantly overestimates the dose, relative to MC, while the CC gives a relatively accurate estimate. Four different respiratory motion patterns were included in the dose calculation with the MC. A "narrowing" of the longitudinal dose profile of up to 20 mm (at about 90% dose level) is seen relative the static dose profile calculated with the PB.

Research paper thumbnail of Validation of organ dose calculations with PyMCGPU-IR in realistic interventional set-ups

Physica medica : PM : an international journal devoted to the applications of physics to medicine and biology : official journal of the Italian Association of Biomedical Physics, 2021

INTRODUCTION Interventional radiology procedures are associated with high skin dose exposure. The... more INTRODUCTION Interventional radiology procedures are associated with high skin dose exposure. The 2013/59/EURATOM Directive establishes that the equipment used for interventional radiology must have a device or a feature informing the practitioner of relevant parameters for assessing patient dose at the end of the procedure. This work presents and validates PyMCGPU-IR, a patient dose monitoring tool for interventional cardiology and radiology procedures based on MC-GPU. MC-GPU is a freely available Monte Carlo (MC) code of photon transport in a voxelized geometry which uses the computational power of commodity Graphics Processing Unit cards (GPU) to accelerate calculations. METHODOLOGIES PyMCGPU-IR was validated against two different experimental set-ups. The first one consisted of skin dose measurements for different beam angulations on an adult Rando Alderson anthropomorphic phantom. The second consisted of organ dose measurements in three clinical procedures using the Rando Alder...

Research paper thumbnail of See Profile

— LiF:Mg,Cu,P is emerging as a very interesting TL material with significant advantages over the ... more — LiF:Mg,Cu,P is emerging as a very interesting TL material with significant advantages over the most widely accepted material, LiF:Mg,Ti. This study aims to demonstrate that some of its characteristics such as the lack of supralinearity make it useful for radiation therapy dosimetry. It has been verified that the residual signal is lower than 1.5 % after an initial dose of 1 Gy and that the energy response for several high energy photon and electron beams used in radiotherapy is within 62.5 % with respect to 60Co. A wide range of dose linearity from 0 to 10 Gy has been found for the beams considered. The influence of temperature (22 ° C, 45 ° C) during irradiation and storage is also analysed. Finally the performance of LiF:Mg,Cu,P is compared to LiF:Mg,Ti. It is shown that commercially available LiF:Mg,Cu,P is suitable for clinical applications and that some of the drawbacks reported in previous work can be overcome.

Research paper thumbnail of Midplane dose determination during total body irradiation using in vivo dosimetry

Radiotherapy and Oncology, 1998

Background and purpose: During TBI techniques an accurate determination of the dose distribution ... more Background and purpose: During TBI techniques an accurate determination of the dose distribution is very dif®cult when using commercial treatment planning systems. In order to determine the midplane dose, an algorithm was developed based on the use of in vivo dosimetry. Materials and methods: Scanditronix EDP-30 diodes were placed at the entrance and the exit surface for in vivo dosimetry. The proposed algorithm was validated ®rstly in a regular and homogeneous phantom of different thickness with an ionization chamber and TL dosimeters and secondly in an Alderson anthropomorphic phantom with TL dosimeters. In this study, in vivo measurements were evaluated in 60 patients and furthermore, in 20 of them, the midplane dose calculated with this algorithm was compared with the method described by Rizzotti A, Compri C, Garusi GF. Dose evaluation to patients irradiated by 60 Co beams, by means of direct measurement on the incident and on the exit surfaces. Radiother. Oncol. 1985;3:279±283. Results: No differences were found between the two methods. The differences between dose values calculated with both methods and dose values measured with the ionization chamber and TL dosimeters were within^2% and^4%, respectively, in the regular and homogeneous phantom and within^2% in the Alderson phantom. The algorithm was useful in calculating the midplane dose when heterogeneities as lungs were present. Even when partial transmission blocks were used to reduce the dose to the lungs, the algorithm with modi®ed correction factors gave a midplane lung dose in the Alderson phantom within 1.3% of the measurements with TL dosimeters. For 360 patients' measurements in each A-P and P-A ®eld, the relative deviations were analyzed between the measured and calculated entrance, exit dose and midplane dose and the prescribed dose, always applying the temperature correction factor. These deviations at the entrance dose were within^4%. Greater deviations were found for the exit dose measurements. Deviations larger than^10% corresponded in general to obese patients, with a thickness over 25 cm. The relative deviations between the total received and prescribed midplane doses in 60 patients were within^3%. Conclusions: The results indicate excellent correspondence between the total prescribed and calculated midplane doses using this algorithm while also no signi®cant differences were found when the Rizzotti method was used. Comparison between doses measured with TL dosimeters in the core of Alderson phantom lungs and doses calculated from in vivo measurements showed that the proposed algorithm could be used in the presence of heterogeneities even when partial transmission blocks were used. The temperature correction factor must be applied in order to avoid a 2±3% dose overestimation.

Research paper thumbnail of Comparison of two extremity dosemeters based on LiF:Mg,Cu,P thin detectors for mixed beta-gamma fields

Radiation Protection Dosimetry, 2006

Two types of thin LiF:Mg,Cu,P detectors, GR-200F and MCP-Ns, have been characterised for use in t... more Two types of thin LiF:Mg,Cu,P detectors, GR-200F and MCP-Ns, have been characterised for use in the design of an extremity dosemeter for mixed beta-photon radiation fields. Both detectors consist of an extremely thin layer of sensitive material with effective thicknesses of 5 and 8 mg cm(-2), respectively, held in a 5 mg cm(-2) PVC ring holder. Dosimetric performance was analysed according to the ISO 12794 standard and compared with 240 mg cm(-2) TLD-100 measurements. In particular, the energy response was obtained for ISO narrow X-ray spectra, (137)Cs, (60)Co, (204)Tl and (90)Sr/(90)Y. From these measurements a mean calibration factor was calculated to estimate H(p)(0.07). Subsequently, the performance of the dosemeters was checked for a set of 10 different mixed photon and beta-photon fields. The study shows that the proposed dosemeters can estimate H(p)(0.07) in a wide range of mixed beta-photon fields with a maximum deviation from the given dose of 30% and an overall uncertainty of the order of 25% (k = 1). However, the results also highlight a large variability among the different thin detectors and, thus, the standard TLD-100 material is recommended whenever the workplace does not include low-energy beta radiation.

Research paper thumbnail of Measurements of eye lens doses in interventional radiology and cardiology: Final results of the ORAMED project

Radiation Measurements, 2011

Research paper thumbnail of SBRT of lung tumours: Monte Carlo simulation with PENELOPE of dose distributions including respiratory motion and comparison with different treatment planning systems

Physics in Medicine and Biology, 2007

The purpose of this work was to simulate with the Monte Carlo (MC) code PENELOPE the dose distrib... more The purpose of this work was to simulate with the Monte Carlo (MC) code PENELOPE the dose distribution in lung tumours including breathing motion in stereotactic body radiation therapy (SBRT). Two phantoms were modelled to simulate a pentagonal cross section with chestwall (unit density), lung (density 0.3 g cm(-3)) and two spherical tumours (unit density) of diameters respectively of 2 cm and 5 cm. The phase-space files (PSF) of four different SBRT field sizes of 6 MV from a Varian accelerator were calculated and used as beam sources to obtain both dose profiles and dose-volume histograms (DVHs) in different volumes of interest. Dose distributions were simulated for five beams impinging on the phantom. The simulations were conducted both for the static case and including the influence of respiratory motion. To reproduce the effect of breathing motion different simulations were performed keeping the beam fixed and displacing the phantom geometry in chosen positions in the cranial and caudal and left-right directions. The final result was obtained by combining the different position with two motion patterns. The MC results were compared with those obtained with three commercial treatment planning systems (TPSs), two based on the pencil beam (PB) algorithm, the TMS-HELAX (Nucletron, Sweden) and Eclipse (Varian Medical System, Palo Alto, CA), and one based on the collapsed cone algorithm (CC), Pinnacle(3) (Philips). Some calculations were also carried out with the analytical anisotropic algorithm (AAA) in the Eclipse system. All calculations with the TPSs were performed without simulated breathing motion, according to clinical practice. In order to compare all the TPSs and MC an absolute dose calibration in Gy/MU was performed. The analysis shows that the dose (Gy/MU) in the central part of the gross tumour volume (GTV) is calculated for both tumour sizes with an accuracy of 2-3% with PB and CC algorithms, compared to MC. At the periphery of the GTV the TPSs overestimate the dose up to 10%, while in the lung tissue close to the GTV PB algorithms overestimate the dose and the CC underestimates it. When clinically relevant breathing motions are included in the MC simulations, the static calculations with the TPSs still give a relatively accurate estimate of the dose in the GTV. On the other hand, the dose at the periphery of the GTV is overestimated, compared to the static case.

Research paper thumbnail of Monte Carlo simulation of MOSFET detectors for high-energy photon beams using the PENELOPE code

Physics in Medicine and Biology, 2006

The aim of this work was the Monte Carlo (MC) simulation of the response of commercially availabl... more The aim of this work was the Monte Carlo (MC) simulation of the response of commercially available dosimeters based on metal oxide semiconductor field effect transistors (MOSFETs) for radiotherapeutic photon beams using the PENELOPE code. The studied Thomson&Nielsen TN-502-RD MOSFETs have a very small sensitive area of 0.04 mm(2) and a thickness of 0.5 microm which is placed on a flat kapton base and covered by a rounded layer of black epoxy resin. The influence of different metallic and Plastic water build-up caps, together with the orientation of the detector have been investigated for the specific application of MOSFET detectors for entrance in vivo dosimetry. Additionally, the energy dependence of MOSFET detectors for different high-energy photon beams (with energy >1.25 MeV) has been calculated. Calculations were carried out for simulated 6 MV and 18 MV x-ray beams generated by a Varian Clinac 1800 linear accelerator, a Co-60 photon beam from a Theratron 780 unit, and monoenergetic photon beams ranging from 2 MeV to 10 MeV. The results of the validation of the simulated photon beams show that the average difference between MC results and reference data is negligible, within 0.3%. MC simulated results of the effect of the build-up caps on the MOSFET response are in good agreement with experimental measurements, within the uncertainties. In particular, for the 18 MV photon beam the response of the detectors under a tungsten cap is 48% higher than for a 2 cm Plastic water cap and approximately 26% higher when a brass cap is used. This effect is demonstrated to be caused by positron production in the build-up caps of higher atomic number. This work also shows that the MOSFET detectors produce a higher signal when their rounded side is facing the beam (up to 6%) and that there is a significant variation (up to 50%) in the response of the MOSFET for photon energies in the studied energy range. All the results have shown that the PENELOPE code system can successfully reproduce the response of a detector with such a small active area.

Research paper thumbnail of The Effect of Tungsten Particle Sizes on X-ray Attenuation Properties

Equipment used for personal radiation protection, which consists of polymeric materials with radi... more Equipment used for personal radiation protection, which consists of polymeric materials with radiopaque powder additives, may cause serious ergonomic problems because of their heavy weights. In this study, X-ray attenuation of the materials developed by using nano and micro sized tungsten particles were experimentally measured in accordance with medical x-ray standards and additionally evaluated with Monte Carlo simulations. It has been observed that materials with nanoparticles reach higher radiation protection values compared to the samples with micro sized powders, although they have the same weight ratios of additive powders. Moreover, the experimental studies showed that while the difference between radiation attenuation of micro and nano sized materials is higher at low energies (30 kV), it decreases at high energies (80 kV and 100 kV). When the simulation results and experimental results were compared, it was seen that the experimental data converged to the simulation results...

Research paper thumbnail of Validation of the MC-GPU Monte Carlo code against the PENELOPE/penEasy code system and benchmarking against experimental conditions for typical radiation qualities and setups in interventional radiology and cardiology

Research paper thumbnail of Material characterization and Monte Carlo simulation of lead and non-lead X-Ray shielding materials

Radiation Physics and Chemistry

Research paper thumbnail of Medically-derived radionuclides levels in seven heterogeneous urban wastewater treatment plants: The role of operating conditions and catchment area

Science of The Total Environment

Research paper thumbnail of EURADOS intercomparison of passive H *(10) area dosemeters 2014

Research paper thumbnail of Status of passive environmental dosimetry in Europe

Radiation Measurements

• Solid state dosemeters are widely used for Environmental Radiation Monitoring (ERM). • An EURAD... more • Solid state dosemeters are widely used for Environmental Radiation Monitoring (ERM). • An EURADOS subgroup (WG3-SG2) which works on passive ERM was inaugurated in 2014. • On the basis of a survey, data on the status of ERM in Europe was obtained. • The survey helped to design the first EURADOS intercomparison of area dosemeters. • Some open questions have been identified (terminology, uncertainty assessment…).

Research paper thumbnail of Natural and artificial radionuclides in sludge, sand, granular activated carbon and reverse osmosis brine from a metropolitan drinking water treatment plant

Journal of Environmental Radioactivity

Research paper thumbnail of Low dose response results and detection limits of the EURADOS intercomparison IC2021area for passive H*(10) area dosemeters

Research paper thumbnail of EJP-CONCERT European Joint Programme for the Integration of Radiation Protection Research H 2020 – 662287 D 9 . 106 – Guidelines for implementing the workplace geometry and the radiation field map in the dosimetry application Part 1 : Workplace geometry

Research paper thumbnail of Feasibility study of computational occupational dosimetry: evaluating a proof-of-concept in an endovascular and interventional cardiology setting

Journal of Radiological Protection

Individual monitoring of radiation workers is essential to ensure compliance with legal dose limi... more Individual monitoring of radiation workers is essential to ensure compliance with legal dose limits and to ensure that doses are As Low As Reasonably Achievable. However, large uncertainties still exist in personal dosimetry and there are issues with compliance and incorrect wearing of dosimeters. The objective of the PODIUM (Personal Online Dosimetry Using Computational Methods) project was to improve personal dosimetry by an innovative approach: the development of an online dosimetry application based on computer simulations without the use of physical dosimeters. Occupational doses were calculated based on the use of camera tracking devices, flexible individualised phantoms and data from the radiation source. When combined with fast Monte Carlo simulation codes, the aim was to perform personal dosimetry in real-time. A key component of the PODIUM project was to assess and validate the methodology in interventional radiology workplaces where improvements in dosimetry are needed. T...

Research paper thumbnail of Overview of passive area dosimetry systems used in European countries

The European Radiation Dosimetry e.V. is a non-profit organization promoting research and develop... more The European Radiation Dosimetry e.V. is a non-profit organization promoting research and development and European cooperation in the field of the dosimetry of ionizing radiation. It is registered in the Register of Associations (Amtsgericht München, registry number VR 207982) and certified to be of non-profit character (Finanzamt München, notification from 2020-10-29). Liability Disclaimer No liability will be undertaken for completeness, editorial or technical mistakes, omissions as well as for correctness of the contents.

Research paper thumbnail of Coincidence summing corrections for volume samples using the PENELOPE/penEasy Monte Carlo code

Applied Radiation and Isotopes, 2014

Computation of coincidence summing corrections for peaks of 152 Eu and 134 Cs. The MC penEasy cod... more Computation of coincidence summing corrections for peaks of 152 Eu and 134 Cs. The MC penEasy code has been modified to include the coincidence summing effect. The correction factors have been obtained with PENELOPE/penEasy MC code. Results have been validated using an ICRM intercomparison.

Research paper thumbnail of Dose distributions in SBRT of lung tumors: Comparison between two different treatment planning algorithms and Monte-Carlo simulation including breathing motions

Acta Oncologica, 2006

In stereotactic body radiotherapy (SBRT) of lung tumors, dosimetric problems arise from: 1) the l... more In stereotactic body radiotherapy (SBRT) of lung tumors, dosimetric problems arise from: 1) the limited accuracy in the dose calculation algorithms in treatment planning systems, and 2) the motions with the respiration of the tumor during treatment. Longitudinal dose distributions have been calculated with Monte Carlo simulation (MC), a pencil beam algorithm (PB) and a collapsed cone algorithm (CC) for two spherical lung tumors (2 cm and 5 cm diameter) in lung tissue, in a phantom situation. Respiratory motions were included by a convolution method, which was validated. In the static situation, the PB significantly overestimates the dose, relative to MC, while the CC gives a relatively accurate estimate. Four different respiratory motion patterns were included in the dose calculation with the MC. A "narrowing" of the longitudinal dose profile of up to 20 mm (at about 90% dose level) is seen relative the static dose profile calculated with the PB.

Research paper thumbnail of Validation of organ dose calculations with PyMCGPU-IR in realistic interventional set-ups

Physica medica : PM : an international journal devoted to the applications of physics to medicine and biology : official journal of the Italian Association of Biomedical Physics, 2021

INTRODUCTION Interventional radiology procedures are associated with high skin dose exposure. The... more INTRODUCTION Interventional radiology procedures are associated with high skin dose exposure. The 2013/59/EURATOM Directive establishes that the equipment used for interventional radiology must have a device or a feature informing the practitioner of relevant parameters for assessing patient dose at the end of the procedure. This work presents and validates PyMCGPU-IR, a patient dose monitoring tool for interventional cardiology and radiology procedures based on MC-GPU. MC-GPU is a freely available Monte Carlo (MC) code of photon transport in a voxelized geometry which uses the computational power of commodity Graphics Processing Unit cards (GPU) to accelerate calculations. METHODOLOGIES PyMCGPU-IR was validated against two different experimental set-ups. The first one consisted of skin dose measurements for different beam angulations on an adult Rando Alderson anthropomorphic phantom. The second consisted of organ dose measurements in three clinical procedures using the Rando Alder...

Research paper thumbnail of See Profile

— LiF:Mg,Cu,P is emerging as a very interesting TL material with significant advantages over the ... more — LiF:Mg,Cu,P is emerging as a very interesting TL material with significant advantages over the most widely accepted material, LiF:Mg,Ti. This study aims to demonstrate that some of its characteristics such as the lack of supralinearity make it useful for radiation therapy dosimetry. It has been verified that the residual signal is lower than 1.5 % after an initial dose of 1 Gy and that the energy response for several high energy photon and electron beams used in radiotherapy is within 62.5 % with respect to 60Co. A wide range of dose linearity from 0 to 10 Gy has been found for the beams considered. The influence of temperature (22 ° C, 45 ° C) during irradiation and storage is also analysed. Finally the performance of LiF:Mg,Cu,P is compared to LiF:Mg,Ti. It is shown that commercially available LiF:Mg,Cu,P is suitable for clinical applications and that some of the drawbacks reported in previous work can be overcome.

Research paper thumbnail of Midplane dose determination during total body irradiation using in vivo dosimetry

Radiotherapy and Oncology, 1998

Background and purpose: During TBI techniques an accurate determination of the dose distribution ... more Background and purpose: During TBI techniques an accurate determination of the dose distribution is very dif®cult when using commercial treatment planning systems. In order to determine the midplane dose, an algorithm was developed based on the use of in vivo dosimetry. Materials and methods: Scanditronix EDP-30 diodes were placed at the entrance and the exit surface for in vivo dosimetry. The proposed algorithm was validated ®rstly in a regular and homogeneous phantom of different thickness with an ionization chamber and TL dosimeters and secondly in an Alderson anthropomorphic phantom with TL dosimeters. In this study, in vivo measurements were evaluated in 60 patients and furthermore, in 20 of them, the midplane dose calculated with this algorithm was compared with the method described by Rizzotti A, Compri C, Garusi GF. Dose evaluation to patients irradiated by 60 Co beams, by means of direct measurement on the incident and on the exit surfaces. Radiother. Oncol. 1985;3:279±283. Results: No differences were found between the two methods. The differences between dose values calculated with both methods and dose values measured with the ionization chamber and TL dosimeters were within^2% and^4%, respectively, in the regular and homogeneous phantom and within^2% in the Alderson phantom. The algorithm was useful in calculating the midplane dose when heterogeneities as lungs were present. Even when partial transmission blocks were used to reduce the dose to the lungs, the algorithm with modi®ed correction factors gave a midplane lung dose in the Alderson phantom within 1.3% of the measurements with TL dosimeters. For 360 patients' measurements in each A-P and P-A ®eld, the relative deviations were analyzed between the measured and calculated entrance, exit dose and midplane dose and the prescribed dose, always applying the temperature correction factor. These deviations at the entrance dose were within^4%. Greater deviations were found for the exit dose measurements. Deviations larger than^10% corresponded in general to obese patients, with a thickness over 25 cm. The relative deviations between the total received and prescribed midplane doses in 60 patients were within^3%. Conclusions: The results indicate excellent correspondence between the total prescribed and calculated midplane doses using this algorithm while also no signi®cant differences were found when the Rizzotti method was used. Comparison between doses measured with TL dosimeters in the core of Alderson phantom lungs and doses calculated from in vivo measurements showed that the proposed algorithm could be used in the presence of heterogeneities even when partial transmission blocks were used. The temperature correction factor must be applied in order to avoid a 2±3% dose overestimation.

Research paper thumbnail of Comparison of two extremity dosemeters based on LiF:Mg,Cu,P thin detectors for mixed beta-gamma fields

Radiation Protection Dosimetry, 2006

Two types of thin LiF:Mg,Cu,P detectors, GR-200F and MCP-Ns, have been characterised for use in t... more Two types of thin LiF:Mg,Cu,P detectors, GR-200F and MCP-Ns, have been characterised for use in the design of an extremity dosemeter for mixed beta-photon radiation fields. Both detectors consist of an extremely thin layer of sensitive material with effective thicknesses of 5 and 8 mg cm(-2), respectively, held in a 5 mg cm(-2) PVC ring holder. Dosimetric performance was analysed according to the ISO 12794 standard and compared with 240 mg cm(-2) TLD-100 measurements. In particular, the energy response was obtained for ISO narrow X-ray spectra, (137)Cs, (60)Co, (204)Tl and (90)Sr/(90)Y. From these measurements a mean calibration factor was calculated to estimate H(p)(0.07). Subsequently, the performance of the dosemeters was checked for a set of 10 different mixed photon and beta-photon fields. The study shows that the proposed dosemeters can estimate H(p)(0.07) in a wide range of mixed beta-photon fields with a maximum deviation from the given dose of 30% and an overall uncertainty of the order of 25% (k = 1). However, the results also highlight a large variability among the different thin detectors and, thus, the standard TLD-100 material is recommended whenever the workplace does not include low-energy beta radiation.

Research paper thumbnail of Measurements of eye lens doses in interventional radiology and cardiology: Final results of the ORAMED project

Radiation Measurements, 2011

Research paper thumbnail of SBRT of lung tumours: Monte Carlo simulation with PENELOPE of dose distributions including respiratory motion and comparison with different treatment planning systems

Physics in Medicine and Biology, 2007

The purpose of this work was to simulate with the Monte Carlo (MC) code PENELOPE the dose distrib... more The purpose of this work was to simulate with the Monte Carlo (MC) code PENELOPE the dose distribution in lung tumours including breathing motion in stereotactic body radiation therapy (SBRT). Two phantoms were modelled to simulate a pentagonal cross section with chestwall (unit density), lung (density 0.3 g cm(-3)) and two spherical tumours (unit density) of diameters respectively of 2 cm and 5 cm. The phase-space files (PSF) of four different SBRT field sizes of 6 MV from a Varian accelerator were calculated and used as beam sources to obtain both dose profiles and dose-volume histograms (DVHs) in different volumes of interest. Dose distributions were simulated for five beams impinging on the phantom. The simulations were conducted both for the static case and including the influence of respiratory motion. To reproduce the effect of breathing motion different simulations were performed keeping the beam fixed and displacing the phantom geometry in chosen positions in the cranial and caudal and left-right directions. The final result was obtained by combining the different position with two motion patterns. The MC results were compared with those obtained with three commercial treatment planning systems (TPSs), two based on the pencil beam (PB) algorithm, the TMS-HELAX (Nucletron, Sweden) and Eclipse (Varian Medical System, Palo Alto, CA), and one based on the collapsed cone algorithm (CC), Pinnacle(3) (Philips). Some calculations were also carried out with the analytical anisotropic algorithm (AAA) in the Eclipse system. All calculations with the TPSs were performed without simulated breathing motion, according to clinical practice. In order to compare all the TPSs and MC an absolute dose calibration in Gy/MU was performed. The analysis shows that the dose (Gy/MU) in the central part of the gross tumour volume (GTV) is calculated for both tumour sizes with an accuracy of 2-3% with PB and CC algorithms, compared to MC. At the periphery of the GTV the TPSs overestimate the dose up to 10%, while in the lung tissue close to the GTV PB algorithms overestimate the dose and the CC underestimates it. When clinically relevant breathing motions are included in the MC simulations, the static calculations with the TPSs still give a relatively accurate estimate of the dose in the GTV. On the other hand, the dose at the periphery of the GTV is overestimated, compared to the static case.

Research paper thumbnail of Monte Carlo simulation of MOSFET detectors for high-energy photon beams using the PENELOPE code

Physics in Medicine and Biology, 2006

The aim of this work was the Monte Carlo (MC) simulation of the response of commercially availabl... more The aim of this work was the Monte Carlo (MC) simulation of the response of commercially available dosimeters based on metal oxide semiconductor field effect transistors (MOSFETs) for radiotherapeutic photon beams using the PENELOPE code. The studied Thomson&Nielsen TN-502-RD MOSFETs have a very small sensitive area of 0.04 mm(2) and a thickness of 0.5 microm which is placed on a flat kapton base and covered by a rounded layer of black epoxy resin. The influence of different metallic and Plastic water build-up caps, together with the orientation of the detector have been investigated for the specific application of MOSFET detectors for entrance in vivo dosimetry. Additionally, the energy dependence of MOSFET detectors for different high-energy photon beams (with energy >1.25 MeV) has been calculated. Calculations were carried out for simulated 6 MV and 18 MV x-ray beams generated by a Varian Clinac 1800 linear accelerator, a Co-60 photon beam from a Theratron 780 unit, and monoenergetic photon beams ranging from 2 MeV to 10 MeV. The results of the validation of the simulated photon beams show that the average difference between MC results and reference data is negligible, within 0.3%. MC simulated results of the effect of the build-up caps on the MOSFET response are in good agreement with experimental measurements, within the uncertainties. In particular, for the 18 MV photon beam the response of the detectors under a tungsten cap is 48% higher than for a 2 cm Plastic water cap and approximately 26% higher when a brass cap is used. This effect is demonstrated to be caused by positron production in the build-up caps of higher atomic number. This work also shows that the MOSFET detectors produce a higher signal when their rounded side is facing the beam (up to 6%) and that there is a significant variation (up to 50%) in the response of the MOSFET for photon energies in the studied energy range. All the results have shown that the PENELOPE code system can successfully reproduce the response of a detector with such a small active area.

Research paper thumbnail of The Effect of Tungsten Particle Sizes on X-ray Attenuation Properties

Equipment used for personal radiation protection, which consists of polymeric materials with radi... more Equipment used for personal radiation protection, which consists of polymeric materials with radiopaque powder additives, may cause serious ergonomic problems because of their heavy weights. In this study, X-ray attenuation of the materials developed by using nano and micro sized tungsten particles were experimentally measured in accordance with medical x-ray standards and additionally evaluated with Monte Carlo simulations. It has been observed that materials with nanoparticles reach higher radiation protection values compared to the samples with micro sized powders, although they have the same weight ratios of additive powders. Moreover, the experimental studies showed that while the difference between radiation attenuation of micro and nano sized materials is higher at low energies (30 kV), it decreases at high energies (80 kV and 100 kV). When the simulation results and experimental results were compared, it was seen that the experimental data converged to the simulation results...

Research paper thumbnail of Validation of the MC-GPU Monte Carlo code against the PENELOPE/penEasy code system and benchmarking against experimental conditions for typical radiation qualities and setups in interventional radiology and cardiology

Research paper thumbnail of Material characterization and Monte Carlo simulation of lead and non-lead X-Ray shielding materials

Radiation Physics and Chemistry

Research paper thumbnail of Medically-derived radionuclides levels in seven heterogeneous urban wastewater treatment plants: The role of operating conditions and catchment area

Science of The Total Environment

Research paper thumbnail of EURADOS intercomparison of passive H *(10) area dosemeters 2014

Research paper thumbnail of Status of passive environmental dosimetry in Europe

Radiation Measurements

• Solid state dosemeters are widely used for Environmental Radiation Monitoring (ERM). • An EURAD... more • Solid state dosemeters are widely used for Environmental Radiation Monitoring (ERM). • An EURADOS subgroup (WG3-SG2) which works on passive ERM was inaugurated in 2014. • On the basis of a survey, data on the status of ERM in Europe was obtained. • The survey helped to design the first EURADOS intercomparison of area dosemeters. • Some open questions have been identified (terminology, uncertainty assessment…).

Research paper thumbnail of Natural and artificial radionuclides in sludge, sand, granular activated carbon and reverse osmosis brine from a metropolitan drinking water treatment plant

Journal of Environmental Radioactivity