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Palmans H, Lourenço A, Medin J, Vatnitsky S, Andreo P. Current best estimates of beam quality correction factors for reference dosimetry of clinical proton beams. Phys Med Biol 2022; 67. [DOI: 10.1088/1361-6560/ac9172] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Accepted: 09/12/2022] [Indexed: 11/12/2022]
Abstract
Abstract
Objective. To review the currently available data on beam quality correction factors,
k
Q
,
for ionization chambers in clinical proton beams and derive their current best estimates for the updated recommendations of the IAEA TRS-398 Code of Practice. Approach. The reviewed data come from 20 publications from which
k
Q
values can be derived either directly from calorimeter measurements, indirectly from comparison with other chambers or from Monte Carlo calculated overall chamber factors,
f
Q
.
For cylindrical ionization chambers, a distinction is made between data obtained in the centre of a spread-out Bragg peak and those obtained in the plateau region of single-energy fields. For the latter, the effect of depth dose gradients has to be considered. To this end an empirical model for previously published displacement correction factors for single-layer scanned beams was established, while for unmodulated scattered beams experimental data were used. From all the data, chamber factors,
f
Q
,
and chamber perturbation correction factors,
p
Q
,
were then derived and analysed. Main results. The analysis showed that except for the beam quality dependence of the water-to-air mass stopping power ratio and, for cylindrical ionization chambers in unmodulated beams, of the displacement correction factor, there is no remaining beam quality dependence of the chamber perturbation correction factors
p
Q
.
Based on this approach, average values of the beam quality independent part of the perturbation factors were derived to calculate
k
Q
values consistent with the data in the literature. Significance. The resulting data from this analysis are current best estimates of
k
Q
values for modulated scattered beams and single-layer scanned beams used in proton therapy. Based on this, a single set of harmonized values is derived to be recommended in the update of IAEA TRS-398.
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2
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Medin J, Andreo P, Palmans H. Experimental determination of kQfactors for two types of ionization chambers in scanned proton beams. Phys Med Biol 2022; 67. [PMID: 35081517 DOI: 10.1088/1361-6560/ac4efa] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Accepted: 01/26/2022] [Indexed: 11/12/2022]
Abstract
Objective.Experimental determination of beam qualitykQfactors for two types of Farmer ionization chambers, NE2571 and IBA FC65-G, in a scanned proton beam for three nominal energies (140 MeV, 180 MeV and 220 MeV) based on water calorimetry.Approach.Beam quality correction factors were determined comparing the results obtained with water calorimetry and ionometry. Water calorimetry was performed to determine the absorbed dose at a depth of measurement in water of 5 g cm-2, limited by the extension of the calorimeter glass vessel used. For the ionometry, two chambers of each type were included in the study. The ionization chambers were calibrated in terms of absorbed dose to water in60Co at the Swedish Secondary Standard Dosimetry Laboratory, directly traceable to the BIPM, and were used according to the IAEA TRS-398 Code of Practice.Main results. ThekQvalues determined in the present work have been compared with the values tabulated in TRS-398 and its forthcoming update and also with those obtained in previous water calorimetric measurements and Monte Carlo calculations. All results were found to agree within the combined uncertainties of the different data.Significance. It is expected that the present work will serve as an experimental contribution tokQ-factors for the two chamber types and three scanned proton beam qualities used.
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Affiliation(s)
- Joakim Medin
- Department of Hematology, Oncology, and Radiation Physics, Skåne University Hospital, Lund, Sweden.,Department of Medical Radiation Physics, Clinical Sciences, Lund, Lund University, Lund, Sweden
| | - Pedro Andreo
- Department of Medical Radiation Physics and Nuclear Medicine, Karolinska University Hospital, Stockholm, Sweden.,Department of Oncology-Pathology, Karolinska Institutet, Stockholm, Sweden
| | - Hugo Palmans
- MedAustron Ion Therapy Center, Wiener Neustadt, Austria.,National Physical Laboratory, Teddington, United Kingdom
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Hartmann GH, Andreo P, Kapsch RP, Zink K. Cema-based formalism for the determination of absorbed dose for high-energy photon beams. Med Phys 2021; 48:7461-7475. [PMID: 34613620 DOI: 10.1002/mp.15266] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Revised: 07/26/2021] [Accepted: 09/23/2021] [Indexed: 11/08/2022] Open
Abstract
PURPOSE Determination of absorbed dose is well established in many dosimetry protocols and considered to be highly reliable using ionization chambers under reference conditions. If dosimetry is performed under other conditions or using other detectors, however, open questions still remain. Such questions frequently refer to appropriate correction factors. A converted energy per mass (cema)-based approach to formulate such correction factors offers a good understanding of the specific response of a detector for dosimetry under various measuring conditions and thus an estimate of pros and cons of its application. METHODS Determination of absorbed dose requires the knowledge of the beam quality correction factor kQ,Qo , where Q denotes the quality of a user beam and Qo is the quality of the radiation used for calibration. In modern Monte Carlo (MC)-based methods, kQ,Qo is directly derived from the MC-calculated dose conversion factor, which is the ratio between the absorbed dose at a point of interest in water and the mean absorbed dose in the sensitive volume of an ion chamber. In this work, absorbed dose is approximated by the fundamental quantity cema. This approximation allows the dose conversion factor to be substituted by the cema conversion factor. Subsequently, this factor is decomposed into a product of cema ratios. They are identified as the stopping power ratio water to the material in the sensitive detector volume, and as the correction factor for the fluence perturbation of the secondary charged particles in the detector cavity caused by the presence of the detector. This correction factor is further decomposed with respect to the perturbation caused by the detector cavity and that caused by external detector properties. The cema-based formalism was subsequently tested by MC calculations of the spectral fluence of the secondary charged particles (electrons and positrons) under various conditions. RESULTS MC calculations demonstrate that considerable fluence perturbation may occur particularly under non-reference conditions. Cema-based correction factors to be applied in a 6-MV beam were obtained for a number of ionization chambers and for three solid-state detectors. Feasibility was shown at field sizes of 4 × 4 and 0.5 cm × 0.5 cm. Values of the cema ratios resulting from the decomposition of the dose conversion factor can be well correlated with detector response. Under the small field conditions, the internal fluence correction factor of ionization chambers is considerably dependent on volume averaging and thus on the shape and size of the cavity volume. CONCLUSIONS The cema approach is particularly useful at non-reference conditions including when solid-state detectors are used. Perturbation correction factors can be expressed and evaluated by cema ratios in a comprehensive manner. The cema approach can serve to understand the specific response of a detector for dosimetry to be dependent on (a) radiation quality, (b) detector properties, and (c) electron fluence changes caused by the detector. This understanding may also help to decide which detector is best suited for a specific measurement situation.
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Affiliation(s)
- Günther H Hartmann
- Division of Medical Physics in Radiation Oncology, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Pedro Andreo
- Department of Medical Radiation Physics and Nuclear Medicine, Karolinska University Hospital, Stockholm, Sweden.,Department of Oncology-Pathology, Karolinska Institutet, Stockholm, Sweden
| | | | - Klemens Zink
- Institut fuer Medizinische Physik und Strahlenschutz (IMPS), University of Applied Sciences, Giessen, Giessen, Germany.,Department for Radiotherapy and Radiooncology, University Medical Center Giessen-Marburg, Marburg, Germany.,Marburg Iontherapy Center (MIT), Marburg, Germany
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Andreo P. Corrigendum: Data for the dosimetry of low- and medium-energy kV x rays (2019 Phys. Med. Biol.64205019). Phys Med Biol 2021; 66. [PMID: 34356035 DOI: 10.1088/1361-6560/ac16eb] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Accepted: 07/22/2021] [Indexed: 11/12/2022]
Affiliation(s)
- Pedro Andreo
- Department of Medical Radiation Physics and Nuclear Medicine, Karolinska University Hospital, and Department of Oncology-Pathology, Karolinska Institutet SE-171 76 Stockholm, Sweden
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Poludniowski G, Omar A, Bujila R, Andreo P. Technical Note: SpekPy v2.0-a software toolkit for modeling x-ray tube spectra. Med Phys 2021; 48:3630-3637. [PMID: 33993511 DOI: 10.1002/mp.14945] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Revised: 04/16/2021] [Accepted: 05/07/2021] [Indexed: 01/22/2023] Open
Abstract
PURPOSE SpekPy is a free toolkit for modeling x-ray tube spectra with the Python programming language. In this article, the advances in version 2.0 (v2) of the software are described, including additional target materials and more accurate modeling of the heel effect. Use of the toolkit is also demonstrated. METHODS The predictions of SpekPy are illustrated in comparison to experimentally determined spectra: three radiation quality reference (RQR) series tungsten spectra and one mammography spectrum with a molybdenum target. The capability of the software to correctly model changes in tube output with tube potential is also assessed, using the example of a GE RevolutionTM CT scanner (GE Healthcare, Waukesha, WI, USA) and specifications in the system's Technical Reference Manual. Furthermore, we note that there are several physics models available in SpekPy. These are compared on and off the central axis, to illustrate the differences. RESULTS SpekPy agrees closely with the experimental spectra over a wide range of tube potentials, both visually and in terms of first and second half-value layers (HVLs) (within 2% here). The CT scanner spectrum output (normalized to 120 kV tube potential) agreed within 4% over the range of 70 to 140 kV. The default physics model (casim) is adequate in most situations. The advanced option (kqp) should be used if high accuracy is desired for modeling the anode heel effect, as it fully includes the effects of bremsstrahlung anisotropy. CONCLUSIONS SpekPy v2 can reliably predict on- and off-axis spectra for tungsten and molybdenum targets. SpekPy's open-source MIT license allows users the freedom to incorporate this powerful toolkit into their own projects.
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Affiliation(s)
- Gavin Poludniowski
- Medical Radiation Physics and Nuclear Medicine, Karolinska University Hospital, Stockholm, Sweden.,Department of Clinical Science, Intervention and Technology, Karolinska Institutet, Stockholm, Sweden
| | - Artur Omar
- Medical Radiation Physics and Nuclear Medicine, Karolinska University Hospital, Stockholm, Sweden.,Department of Oncology and Pathology, Karolinska Institutet, Stockholm, Sweden
| | - Robert Bujila
- Medical Radiation Physics and Nuclear Medicine, Karolinska University Hospital, Stockholm, Sweden.,GE Healthcare, Waukesha, WI, 53188, USA
| | - Pedro Andreo
- Medical Radiation Physics and Nuclear Medicine, Karolinska University Hospital, Stockholm, Sweden.,Department of Oncology and Pathology, Karolinska Institutet, Stockholm, Sweden
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6
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Valdes-Cortez C, Ballester F, Vijande J, Gimenez V, Gimenez-Alventosa V, Perez-Calatayud J, Niatsetski Y, Andreo P. Depth-dose measurement corrections for the surface electronic brachytherapy beams of an Esteya ® unit: a Monte Carlo study. Phys Med Biol 2020; 65. [DOI: 10.1088/1361-6560/ab9773] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Accepted: 05/28/2020] [Indexed: 11/12/2022]
Abstract
Abstract
Three different correction factors for measurements with the parallel-plate ionization chamber PTW T34013 on the Esteya electronic brachytherapy unit have been investigated. This chamber type is recommended by AAPM TG-253 for depth-dose measurements in the 69.5 kV x-ray beam generated by the Esteya unit.
Monte Carlo simulations using the PENELOPE-2018 system were performed to determine the absorbed dose deposited in water and in the chamber sensitive volume at different depths with a Type A uncertainty smaller than 0.1%. Chamber-to-chamber differences have been explored performing measurements using three different chambers. The range of conical applicators available, from 10 to 30 mm in diameter, has been explored.
Using a depth-independent global chamber perturbation correction factor without a shift of the effective point of measurement yielded differences between the absorbed dose to water and the corrected absorbed dose in the sensitive volume of the chamber of up to 1% and 0.6% for the 10 mm and 30 mm applicators, respectively. Calculations using a depth-dependent perturbation factor, including or excluding a shift of the effective point of measurement, resulted in depth-dose differences of about ± 0.5% or less for both applicators. The smallest depth-dose differences were obtained when a shift of the effective point of measurement was implemented, being displaced 0.4 mm towards the center of the sensitive volume of the chamber. The correction factors were obtained with combined uncertainties of 0.4% (k = 2). Uncertainties due to chamber-to-chamber differences are found to be lower than 2%.
The results emphasize the relevance of carrying out detailed Monte Carlo studies for each electronic brachytherapy device and ionization chamber used for its dosimetry.
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Giménez-Alventosa V, Giménez V, Ballester F, Vijande J, Andreo P. Monte Carlo calculation of beam quality correction factors for PTW cylindrical ionization chambers in photon beams. ACTA ACUST UNITED AC 2020; 65:205005. [DOI: 10.1088/1361-6560/ab9501] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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8
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Omar A, Andreo P, Poludniowski G. A model for the energy and angular distribution of x rays emitted from an x-ray tube. Part I. Bremsstrahlung production. Med Phys 2020; 47:4763-4774. [PMID: 32609887 DOI: 10.1002/mp.14359] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Revised: 05/01/2020] [Accepted: 05/14/2020] [Indexed: 11/07/2022] Open
Abstract
PURPOSE To develop an analytical model for bremsstrahlung production in a thick x-ray target (i.e., the x-ray tube anode) that takes into account the intrinsic bremsstrahlung angular distribution. METHODS X-ray spectrum models developed from theoretical principles have traditionally treated the angular distribution of the bremsstrahlung production as spherically uniform. This assumption stems from the rationale that electrons promptly attain a diffuse directional distribution in an x-ray target due to multiple scattering, thereby effectively masking the intrinsic bremsstrahlung angular distribution. In this work, a model that explicitly accounts for the angular distribution of the bremsstrahlung production is presented. The model combines Monte Carlo-calculated depth, energy, and angular distributions of electrons penetrating the x-ray target, and incorporates theoretical results for the differential bremsstrahlung cross section. The effects of using different simplified model assumptions for the electron penetration and the intrinsic bremsstrahlung angular distribution are analyzed for tungsten and molybdenum targets in the energy range 20-300 keV. RESULTS Typical assumptions of previous models are shown to introduce errors in calculated spectra. Particularly, it is shown that predictions of fluence and air kerma free-in-air can be overestimated by 15-30% (2-3% in aluminum half-value layer thickness) for clinically relevant beam qualities. The present model is able to reproduce comprehensive Monte Carlo calculations of the bremsstrahlung production generally to within 1%. CONCLUSIONS The bremsstrahlung model developed in this work is an improvement over previous models in that the main features of the electron penetration and the resulting bremsstrahlung are considered in detail. The model can be used for more accurate predictions of the energy and angular distribution of x rays emitted from an x-ray tube.
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Affiliation(s)
- Artur Omar
- Medical Radiation Physics and Nuclear Medicine, Karolinska University Hospital, Stockholm, 17176, Sweden.,Department of Oncology-Pathology, Karolinska Institutet, Stockholm, 17176, Sweden
| | - Pedro Andreo
- Medical Radiation Physics and Nuclear Medicine, Karolinska University Hospital, Stockholm, 17176, Sweden.,Department of Oncology-Pathology, Karolinska Institutet, Stockholm, 17176, Sweden
| | - Gavin Poludniowski
- Medical Radiation Physics and Nuclear Medicine, Karolinska University Hospital, Stockholm, 17176, Sweden.,Department of Oncology-Pathology, Karolinska Institutet, Stockholm, 17176, Sweden
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9
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Omar A, Andreo P, Poludniowski G. A model for the energy and angular distribution of x rays emitted from an x-ray tube. Part II. Validation of x-ray spectra from 20 to 300 kV. Med Phys 2020; 47:4005-4019. [PMID: 32593216 DOI: 10.1002/mp.14360] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Revised: 05/22/2020] [Accepted: 06/11/2020] [Indexed: 11/12/2022] Open
Abstract
PURPOSE To present and validate a complete x-ray emission model (bremsstrahlung and characteristic x-ray emission) for the energy range 20-300 kV. METHODS An analytical x-ray spectrum model that combines the bremsstrahlung emission model developed in Part I with a previously developed characteristic x-ray emission model is validated by comparison with Monte Carlo calculations, published measured spectra, and models developed by other authors. Furthermore, the assumptions and limitations of previous spectrum models are summarized, and their predictions are compared with results obtained by Monte Carlo simulations of x rays emitted from tungsten and molybdenum targets. RESULTS The model is able to reproduce narrow-beam Monte Carlo calculations to within 0.5% in terms of the first and second aluminum half-value layer thickness (HVL). Compared with measured spectra, the difference in HVL is < 2% for typical diagnostic and therapeutic beam qualities available at primary standard laboratories. Compared with previous spectrum models, the present model performs especially well for low kilovoltage x-ray beams (below 50 kV), and is reliable for a wider range of take-off angles, that is, the angle between the target surface and the direction of emission. The difference in model and Monte Carlo predictions of the energy-fluence weighted air kerma (i.e., the photon energy absorption in air) is < 0.5% using the present model, while previous spectrum models can differ by more than 10%. CONCLUSIONS The x-ray emission model developed in this work has been validated against Monte Carlo calculations and measured results. The model provides an efficient alternative to comprehensive Monte Carlo simulations and is an improvement over previous models. The model can be used to predict both central- and off-axis spectra, as well as off-axis effects such as the (anode) heel effect.
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Affiliation(s)
- Artur Omar
- Medical Radiation Physics and Nuclear Medicine, Karolinska University Hospital, Stockholm, 17176, Sweden.,Department of Oncology-Pathology, Karolinska Institutet, Stockholm, 17176, Sweden
| | - Pedro Andreo
- Medical Radiation Physics and Nuclear Medicine, Karolinska University Hospital, Stockholm, 17176, Sweden.,Department of Oncology-Pathology, Karolinska Institutet, Stockholm, 17176, Sweden
| | - Gavin Poludniowski
- Medical Radiation Physics and Nuclear Medicine, Karolinska University Hospital, Stockholm, 17176, Sweden.,Department of Oncology-Pathology, Karolinska Institutet, Stockholm, 17176, Sweden
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Andreo P, Burns DT, Kapsch RP, McEwen M, Vatnitsky S, Andersen CE, Ballester F, Borbinha J, Delaunay F, Francescon P, Hanlon MD, Mirzakhanian L, Muir B, Ojala J, Oliver CP, Pimpinella M, Pinto M, de Prez LA, Seuntjens J, Sommier L, Teles P, Tikkanen J, Vijande J, Zink K. Determination of consensus k Q values for megavoltage photon beams for the update of IAEA TRS-398. ACTA ACUST UNITED AC 2020; 65:095011. [DOI: 10.1088/1361-6560/ab807b] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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11
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12
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Hartmann GH, Andreo P. Fluence calculation methods in Monte Carlo dosimetry simulations. Z Med Phys 2019; 29:239-248. [DOI: 10.1016/j.zemedi.2018.08.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2018] [Revised: 07/04/2018] [Accepted: 08/26/2018] [Indexed: 11/25/2022]
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Palmans H, Andreo P, Huq MS, Seuntjens J, Christaki KE, Meghzifene A. Reply to "Comments on the TRS-483 Protocol on Small field Dosimetry" [Med. Phys. 45(12), 5666-5668 (2018)]. Med Phys 2019; 45:5669-5671. [PMID: 30536943 DOI: 10.1002/mp.13235] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2018] [Revised: 09/24/2018] [Accepted: 09/24/2018] [Indexed: 11/09/2022] Open
Affiliation(s)
- Hugo Palmans
- Medical Radiation Science, National Physical Laboratory, Teddington, TW11 0LW, UK.,Department of Medical Physics, EBG MedAustron GmbH, A-2700, Wiener Neustadt, Austria
| | - Pedro Andreo
- Department of Medical Physics and Nuclear Medicine, Karolinska University Hospital, SE-17176, Stockholm, Sweden
| | - M Saiful Huq
- Department of Radiation Oncology, UPMC Hillman Cancer Center, University of Pittsburgh School of Medicine, Pittsburgh, PA, 15232, USA
| | - Jan Seuntjens
- Medical Physics Unit, McGill University, Montréal, QC, H3A 0G4, Canada
| | - Karen E Christaki
- Dosimetry and Medical Radiation Physics Section, International Atomic Energy Agency, A-1400, Vienna, Austria
| | - Ahmed Meghzifene
- Dosimetry and Medical Radiation Physics Section, International Atomic Energy Agency, A-1400, Vienna, Austria
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Brualla L, Rodriguez M, Sempau J, Andreo P. PENELOPE/PRIMO-calculated photon and electron spectra from clinical accelerators. Radiat Oncol 2019; 14:6. [PMID: 30634994 PMCID: PMC6330451 DOI: 10.1186/s13014-018-1186-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Accepted: 11/19/2018] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The availability of photon and electron spectra in digital form from current accelerators and Monte Carlo (MC) systems is scarce, and one of the packages widely used refers to linacs with a reduced clinical use nowadays. Such spectra are mainly intended for the MC calculation of detector-related quantities in conventional broad beams, where the use of detailed phase-space files (PSFs) is less critical than for MC-based treatment planning applications, but unlike PSFs, spectra can easily be transferred to other computer systems and users. METHODS A set of spectra for a range of Varian linacs has been calculated using the PENELOPE/PRIMO MC system. They have been extracted from PSFs tallied for field sizes of 10 cm × 10 cm and 15 cm × 15 cm for photon and electron beams, respectively. The influence of the spectral bin width and of the beam central axis region used to extract the spectra have been analyzed. RESULTS Spectra have been compared to those by other authors showing good agreement with those obtained using the, now superseded, EGS4/BEAM MC code, but significant differences with the most widely used photon data set. Other spectra, particularly for electron beams, have not been published previously for the machines simulated in this work. The influence of the bin width on the spectrum mean energy for 6 and 10 MV beams has been found to be negligible. The size of the region used to extract the spectra yields differences of up to 40% for the mean energies in 10 MV beams, but the maximum difference for TPR 20,10 values derived from depth-dose distributions does not exceed 2% relative to those obtained using the PSFs. This corresponds to kQ differences below 0.2% for a typical Farmer-type chamber, considered to be negligible for reference dosimetry. Different configurations for using electron spectra have been compared for 6 MeV beams, concluding that the geometry used for tallying the PSFs used to extract the spectra must be accounted for in subsequent calculations using the spectra as a source. CONCLUSIONS An up-to-date set of consistent spectra for Varian accelerators suitable for the calculation of detector-related quantities in conventional broad beams has been developed and made available in digital form.
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Affiliation(s)
- Lorenzo Brualla
- West German Proton Therapy Centre Essen (WPE), Essen, D-45147, Germany. .,West German Cancer Center (WTZ), Essen, D-45147, Germany. .,University Hospital Essen, Essen, D-45147, Germany. .,Universität Duisburg-Essen, Medizinische Fakultät, Essen, D-45147, Germany.
| | - Miguel Rodriguez
- Centro Médico Paitilla, Panama City, 0816-03075, Panama.,Instituto de Investigaciones Científicas y de Alta Tecnología, INDICASAT-AIP, City of Knowledge, Building 219, Panama City, Panama
| | - Josep Sempau
- Department of Physics and Institute of Energy Technologies, Universitat Politècnica de Catalunya, Barcelona, E-08028, Spain
| | - Pedro Andreo
- Department of Medical Radiation Physics and Nuclear Medicine, Karolinska University Hospital, and Department of Oncology-Pathology, Karolinska Institutet, Stockholm, SE-171 76, Sweden
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Palmans H, Andreo P, Huq MS, Seuntjens J, Christaki KE, Meghzifene A. Dosimetry of small static fields used in external photon beam radiotherapy: Summary of TRS‐483, the IAEA–AAPM international Code of Practice for reference and relative dose determination. Med Phys 2018; 45:e1123-e1145. [DOI: 10.1002/mp.13208] [Citation(s) in RCA: 123] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2017] [Revised: 07/24/2018] [Accepted: 07/30/2018] [Indexed: 12/18/2022] Open
Affiliation(s)
- Hugo Palmans
- Medical Radiation Science National Physical Laboratory Teddington TW11 0LWUK
- Department of Medical Physics EBG MedAustron GmbH A‐2700Wiener Neustadt Austria
| | - Pedro Andreo
- Department of Medical Physics and Nuclear Medicine Karolinska University Hospital SE‐17176Stockholm Sweden
| | - M. Saiful Huq
- Department of Radiation Oncology University of Pittsburgh School of Medicine and UPMC Hillman Cancer Center Pittsburgh PA15232USA
| | - Jan Seuntjens
- Medical Physics Unit McGill University Montréal QCH3A 0G4Canada
| | - Karen E. Christaki
- Dosimetry and Medical Radiation Physics Section International Atomic Energy Agency A‐1400Vienna Austria
| | - Ahmed Meghzifene
- Dosimetry and Medical Radiation Physics Section International Atomic Energy Agency A‐1400Vienna Austria
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Andreo P, Benmakhlouf H. Comment on ‘Origins of the changing detector response in small megavoltage photon radiation fields’. Phys Med Biol 2018; 63:198001. [DOI: 10.1088/1361-6560/aae0e3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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17
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Bär E, Andreo P, Lalonde A, Royle G, Bouchard H. Optimized I-values for use with the Bragg additivity rule and their impact on proton stopping power and range uncertainty. Phys Med Biol 2018; 63:165007. [PMID: 29999493 DOI: 10.1088/1361-6560/aad312] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Novel imaging modalities can improve the estimation of patient elemental compositions for particle treatment planning. The mean excitation energy (I-value) is a main contributor to the proton range uncertainty. To minimize their impact on beam range errors and quantify their uncertainties, the currently used I-values proposed in 1982 are revisited. The study aims at proposing a new set of optimized elemental I-values for use with the Bragg additivity rule (BAR) and establishing uncertainties on the optimized I-values and the BAR. We optimize elemental I-values for the use in compounds based on measured material I-values. We gain a new set of elemental I-values and corresponding uncertainties, based on the experimental uncertainties and our uncertainty model. We evaluate uncertainties on I-values and relative stopping powers (RSP) of 70 human tissues, taking into account statistical correlations between tissues and water. The effect of new I-values on proton beam ranges is quantified using Monte Carlo simulations. Our elemental I-values describe measured material I-values with higher accuracy than ICRU-recommended I-values (RMSE: 6.17% (ICRU), 5.19% (this work)). Our uncertainty model estimates an uncertainty component from the BAR to 4.42%. Using our elemental I-values, we calculate the I-value of water as 78.73 ± 2.89 eV, being consistent with ICRU 90 (78 ± 2 eV). We observe uncertainties on tissue I-values between 1.82-3.38 eV, and RSP uncertainties between 0.002%-0.44%. With transport simulations of a proton beam in human tissues, we observe range uncertainties between 0.31% and 0.47%, as compared to current estimates of 1.5%. We propose a set of elemental I-values well suited for human tissues in combination with the BAR. Our model establishes uncertainties on elemental I-values and the BAR, enabling to quantify uncertainties on tissue I-values, RSP as well as particle range. This work is particularly relevant for Monte Carlo simulations where the interaction probabilities are reconstructed from elemental compositions.
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Affiliation(s)
- Esther Bär
- Chemical, Medical and Environmental Science Department, National Physical Laboratory, Hampton Road, Teddington TW11 0LW, United Kingdom. Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, London WC1E 6BT, United Kingdom
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Abstract
BACKGROUND The use of the Monte Carlo (MC) method in radiotherapy dosimetry has increased almost exponentially in the last decades. Its widespread use in the field has converted this computer simulation technique in a common tool for reference and treatment planning dosimetry calculations. METHODS This work reviews the different MC calculations made on dosimetric quantities, like stopping-power ratios and perturbation correction factors required for reference ionization chamber dosimetry, as well as the fully realistic MC simulations currently available on clinical accelerators, detectors and patient treatment planning. CONCLUSIONS Issues are raised that include the necessity for consistency in the data throughout the entire dosimetry chain in reference dosimetry, and how Bragg-Gray theory breaks down for small photon fields. Both aspects are less critical for MC treatment planning applications, but there are important constraints like tissue characterization and its patient-to-patient variability, which together with the conversion between dose-to-water and dose-to-tissue, are analysed in detail. Although these constraints are common to all methods and algorithms used in different types of treatment planning systems, they make uncertainties involved in MC treatment planning to still remain "uncertain".
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Affiliation(s)
- Pedro Andreo
- Department of Medical Radiation Physics and Nuclear Medicine, Karolinska University Hospital, and Department of Oncology-Pathology, Karolinska Institutet, Stockholm, SE-171 76, Sweden.
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Gimenez-Alventosa V, Gimenez V, Ballester F, Vijande J, Andreo P. Correction factors for ionization chamber measurements with the 'Valencia' and 'large field Valencia' brachytherapy applicators. Phys Med Biol 2018; 63:125004. [PMID: 29726409 DOI: 10.1088/1361-6560/aac27a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Treatment of small skin lesions using HDR brachytherapy applicators is a widely used technique. The shielded applicators currently available in clinical practice are based on a tungsten-alloy cup that collimates the source-emitted radiation into a small region, hence protecting nearby tissues. The goal of this manuscript is to evaluate the correction factors required for dose measurements with a plane-parallel ionization chamber typically used in clinical brachytherapy for the 'Valencia' and 'large field Valencia' shielded applicators. Monte Carlo simulations have been performed using the PENELOPE-2014 system to determine the absorbed dose deposited in a water phantom and in the chamber active volume with a Type A uncertainty of the order of 0.1%. The average energies of the photon spectra arriving at the surface of the water phantom differ by approximately 10%, being 384 keV for the 'Valencia' and 343 keV for the 'large field Valencia'. The ionization chamber correction factors have been obtained for both applicators using three methods, their values depending on the applicator being considered. Using a depth-independent global chamber perturbation correction factor and no shift of the effective point of measurement yields depth-dose differences of up to 1% for the 'Valencia' applicator. Calculations using a depth-dependent global perturbation factor, or a shift of the effective point of measurement combined with a constant partial perturbation factor, result in differences of about 0.1% for both applicators. The results emphasize the relevance of carrying out detailed Monte Carlo studies for each shielded brachytherapy applicator and ionization chamber.
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Affiliation(s)
- V Gimenez-Alventosa
- Instituto de Instrumentación para Imagen Molecular (I3M), Centro Mixto CSIC-Universitat Politècnica de València, 46022 Valencia, Spain
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Baer E, Andreo P, Lalonde A, Royle G, Bouchard H. OC-0084: A novel method to estimate mean excitation energies and their uncertainties for particle therapy. Radiother Oncol 2018. [DOI: 10.1016/s0167-8140(18)30394-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
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21
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Andreo P. The physics of small megavoltage photon beam dosimetry. Radiother Oncol 2018; 126:205-213. [DOI: 10.1016/j.radonc.2017.11.001] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2017] [Revised: 10/16/2017] [Accepted: 11/01/2017] [Indexed: 10/18/2022]
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Benmakhlouf H, Andreo P. Spectral distribution of particle fluence in small field detectors and its implication on small field dosimetry. Med Phys 2017; 44:713-724. [DOI: 10.1002/mp.12042] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2016] [Revised: 11/14/2016] [Accepted: 11/27/2016] [Indexed: 11/07/2022] Open
Affiliation(s)
- Hamza Benmakhlouf
- Department of Medical Radiation Physics and Nuclear Medicine; Karolinska University Hospital; SE-17176 Stockholm Sweden
| | - Pedro Andreo
- Department of Medical Radiation Physics and Nuclear Medicine; Karolinska University Hospital; SE-17176 Stockholm Sweden
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Andreo P, Benmakhlouf H. Role of the density, density effect and mean excitation energy in solid-state detectors for small photon fields. Phys Med Biol 2017; 62:1518-1532. [DOI: 10.1088/1361-6560/aa562e] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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24
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Giménez-Alventosa V, Antunes PCG, Vijande J, Ballester F, Pérez-Calatayud J, Andreo P. Collision-kerma conversion between dose-to-tissue and dose-to-water by photon energy-fluence corrections in low-energy brachytherapy. Phys Med Biol 2016; 62:146-164. [PMID: 27991455 DOI: 10.1088/1361-6560/aa4f6a] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The AAPM TG-43 brachytherapy dosimetry formalism, introduced in 1995, has become a standard for brachytherapy dosimetry worldwide; it implicitly assumes that charged-particle equilibrium (CPE) exists for the determination of absorbed dose to water at different locations, except in the vicinity of the source capsule. Subsequent dosimetry developments, based on Monte Carlo calculations or analytical solutions of transport equations, do not rely on the CPE assumption and determine directly the dose to different tissues. At the time of relating dose to tissue and dose to water, or vice versa, it is usually assumed that the photon fluence in water and in tissues are practically identical, so that the absorbed dose in the two media can be related by their ratio of mass energy-absorption coefficients. In this work, an efficient way to correlate absorbed dose to water and absorbed dose to tissue in brachytherapy calculations at clinically relevant distances for low-energy photon emitting seeds is proposed. A correction is introduced that is based on the ratio of the water-to-tissue photon energy-fluences. State-of-the art Monte Carlo calculations are used to score photon fluence differential in energy in water and in various human tissues (muscle, adipose and bone), which in all cases include a realistic modelling of low-energy brachytherapy sources in order to benchmark the formalism proposed. The energy-fluence based corrections given in this work are able to correlate absorbed dose to tissue and absorbed dose to water with an accuracy better than 0.5% in the most critical cases (e.g. bone tissue).
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Affiliation(s)
- Vicent Giménez-Alventosa
- Department of Atomic, Molecular, and Nuclear Physics, University of Valencia, E46100 Burjassot, Spain
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25
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Andreo P, Palmans H. Comment on “Experimental determination of the PTW 60019 microDiamond dosimeter active area and volume” [Med. Phys. 43, 5205-5212 (2016)]. Med Phys 2016; 43:6667. [DOI: 10.1118/1.4966023] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Benmakhlouf H, Brualla L, Andreo P, Sempau J. SU-F-T-367: Using PRIMO, a PENELOPE-Based Software, to Improve the Small Field Dosimetry of Linear Accelerators. Med Phys 2016. [DOI: 10.1118/1.4956552] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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27
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Hohlfeld K, Andreo P, Mattsson O, Simoen JP. Dosimetry of High-Energy Photon Beams Based on Standards of Absorbed Dose to Water: Abstract. ACTA ACUST UNITED AC 2016. [DOI: 10.1093/jicru/1.1.8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
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Gomà C, Andreo P, Sempau J. OC-0078: Monte Carlo calculated beam quality correction factors for proton beams. Radiother Oncol 2016. [DOI: 10.1016/s0167-8140(16)31327-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Omar A, Bujila R, Fransson A, Andreo P, Poludniowski G. A framework for organ dose estimation in x-ray angiography and interventional radiology based on dose-related data in DICOM structured reports. Phys Med Biol 2016; 61:3063-83. [DOI: 10.1088/0031-9155/61/8/3063] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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Gomà C, Andreo P, Sempau J. Monte Carlo calculation of beam quality correction factors in proton beams using detailed simulation of ionization chambers. Phys Med Biol 2016; 61:2389-406. [DOI: 10.1088/0031-9155/61/6/2389] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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31
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Andreo P, Palmans H, Marteinsdóttir M, Benmakhlouf H, Carlsson-Tedgren Å. On the Monte Carlo simulation of small-field micro-diamond detectors for megavoltage photon dosimetry. Phys Med Biol 2015; 61:L1-L10. [DOI: 10.1088/0031-9155/61/1/l1] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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32
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Benmakhlouf H, Andreo P. SU-E-T-432: Field Size Influence On the Electron and Photon Spectra Within Small MV Field Detectors. Med Phys 2015. [DOI: 10.1118/1.4924793] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Benmakhlouf H, Johansson J, Paddick I, Andreo P. Monte Carlo calculated and experimentally determined output correction factors for small field detectors in Leksell Gamma Knife Perfexion beams. Phys Med Biol 2015; 60:3959-73. [DOI: 10.1088/0031-9155/60/10/3959] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Andreo P. Corrigendum: Dose to ‘water-like’ media or dose to tissue in MV photons radiotherapy treatment planning: still a matter of debate (2015 Phys. Med. Biol. 60 309–37). Phys Med Biol 2015. [DOI: 10.1088/0031-9155/60/6/2619] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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35
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Bortfeld T, Torresin A, Fiorino C, Andreo P, Gagliardi G, Jeraj R, Muren LP, Paiusco M, Thwaites D, Knöös T. The research versus clinical service role of medical physics. Radiother Oncol 2015; 114:285-8. [DOI: 10.1016/j.radonc.2015.02.003] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2015] [Accepted: 02/03/2015] [Indexed: 10/23/2022]
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Abstract
The difference between Monte Carlo Treatment Planning (MCTP) based on the assumption of 'water-like' tissues with densities obtained from CT procedures, or on tissue compositions derived from CT-determined densities, have been investigated. Stopping powers and electron fluences have been calculated for a range of media and body tissues for 6 MV photon beams, including changes in their physical data (density and stopping powers). These quantities have been used to determine absorbed doses using cavity theory. It is emphasized that tissue compositions given in ICRU or ICRP reports should not be given the standing of physical constants as they correspond to average values obtained for a limited number of human-body samples. It has been shown that mass stopping-power ratios to water are more dependent on patient-to-patient composition differences, and therefore on their mean excitation energies (I-values), than on mass density. Electron fluence in different media are also more dependent on media composition (and their I-values) than on density. However, as a consequence of the balance between fluence and stopping powers, doses calculated from their product are more constant than what the independent stopping powers and fluence variations suggest. Additionally, cancelations in dose ratios minimize the differences between the 'water-like' and 'tissue' approaches, yielding practically identical results except for bone, and to a lesser extent for adipose tissue. A priori, changing from one approach to another does not seem to be justified considering the large number of approximations and uncertainties involved throughout the treatment planning tissue segmentation and dose calculation procedures. The key issue continues to be the composition of tissues and their I-values, and as these cannot be obtained for individual patients, whatever approach is selected does not lead to significant differences from a water reference dose, the maximum of these being of the order of 5% for bone tissues. Considering, however, current developments in advanced dose calculation methods, planning in terms of dose-to-tissue should be the preferred choice, under the expectancy that progress in the field will gradually improve some of the crude approximations included in MCTP and numerical transport methods. The small differences obtained also show that a retrospective conversion from dose-to-tissue to dose-to-water, based on a widely used approach, would mostly increase the final uncertainty of the treatment planning process. It is demonstrated that, due to the difference between electron fluence distributions in water and in body tissues, the conversion requires an additional fluence correction that has so far been neglected. An improved expression for the conversion and data for the fluence correction factor are provided. These will be necessary even in a dose-to-tissue environment, for the normalization of the treatment plan to the reference dosimetry of the treatment unit, always calibrated in terms of absorbed dose to water.
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Affiliation(s)
- Pedro Andreo
- Division of Medical Radiation Physics, Department of Physics, Stockholm University, Universitetsvägen 10, 114 18 Stockholm, Sweden. Department of Medical Physics, Karolinska University Hospital, PO Box 260, SE-171 76 Stockholm, Sweden
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Andreo P, Gómez C, Carrasco E, Martínez-Escámez I, Alguazas I, Andreo F. Quality Assurance Systems in Nursing. A turning point in the world of
nursing homes. Eur J Investig Health Psychol Educ 2014. [DOI: 10.1989/ejihpe.v1i1.94] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Developing and trying to achieve a high quality in the service nursing
personnel provide at nursing homes by means of implementing quality
assurance systems is a topic of general interest nowadays. These systems
have already proved to be effective in other fields. That is why the focus
of this study is to analyse the most relevant effects due to the
implementation of a quality assurance method based on standard UNE EN ISO
9001:2008 in the nursing service of four nursing homes. An analysis of more
than 200 answers of a satisfaction survey about the nursing service at four
nursing homes has been carried out. A study on the available bibliography
about the results obtained after having implemented a quality assurance
system in the nursing service at nursing homes has also been carried out.
Very positive results can be appreciated in the daily nursing practice at
nursing homes as a consequence of using a quality assurance system. Clinical
practice has improved considerably as a consequence. The study shows quality
assurance systems to be a useful tool at the service of nursing practice at
nursing homes. Positive effects resulting from the implementation of such
quality assurance systems are evident as it can be seen from satisfaction
surveys and health indicators.
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Benmakhlouf H, Sempau J, Andreo P. Output correction factors for nine small field detectors in 6 MV radiation therapy photon beams: A PENELOPE Monte Carlo study. Med Phys 2014; 41:041711. [DOI: 10.1118/1.4868695] [Citation(s) in RCA: 108] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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39
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Andreo P, Wulff J, Burns DT, Palmans H. Consistency in reference radiotherapy dosimetry: resolution of an apparent conundrum when60Co is the reference quality for charged-particle and photon beams. Phys Med Biol 2013; 58:6593-621. [DOI: 10.1088/0031-9155/58/19/6593] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Benmakhlouf H, Sempau J, Andreo P. SU-E-T-29: Monte Carlo Calculated Output Corrections Factors K(Q,f-Clin) for Varian_Clinac-IX 6MV Small Fields. Med Phys 2013. [DOI: 10.1118/1.4814463] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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41
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Meghzifene A, do Carmo Lopes M, Cheung KY, Constantinou C, Andreo P, Brandan ME, Castellanos ME, Ige TA, Frey GH. IAEA contribution to international harmonization of guidelines for clinical medical radiation physicists. Med Phys 2013. [DOI: 10.1118/1.4815410] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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42
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Palmans H, Al-Sulaiti L, Andreo P, Shipley D, Lühr A, Bassler N, Martinkovič J, Dobrovodský J, Rossomme S, Thomas RAS, Kacperek A. Fluence correction factors for graphite calorimetry in a low-energy clinical proton beam: I. Analytical and Monte Carlo simulations. Phys Med Biol 2013; 58:3481-99. [DOI: 10.1088/0031-9155/58/10/3481] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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44
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Benmakhlouf H, Fransson A, Andreo P. Influence of phantom thickness and material on the backscatter factors for diagnostic x-ray beam dosimetry. Phys Med Biol 2012; 58:247-60. [DOI: 10.1088/0031-9155/58/2/247] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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46
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Palmans H, Alfonso R, Andreo P, Capote R, Huq MS, Izewska J, Johansson J, Kilby W, Mackie TR, Meghzifene A, Rosser K, Seuntjens J, Ullrich W. Poster - Thur Eve - 46: The upcoming international code of practice for small static photon field dosimetry. Med Phys 2012; 39:4633. [DOI: 10.1118/1.4740154] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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47
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Palmans H, Alfonso R, Andreo P, Capote-Noy R, Huq MS, Izewska J, Johansson J, Kilby W, Mackie TR, Meghzifene A, Rosser K, Seuntjens J, Ullrich W. TH-E-BRB-05: Best in Physics (Therapy) - an International Code of Practice for the Dosimetry of Small Static Photon Fields. Med Phys 2012. [DOI: 10.1118/1.4736355] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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48
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Benmakhlouf H, Johansson J, Andreo P. SU-E-T-30: Monte Carlo Calculated Detector Corrections K(Q, F-Clin) for Determination of Output Factors for the Leksell Gamma Knife. Med Phys 2012. [DOI: 10.1118/1.4735085] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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49
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Andreo P, Burns DT, Salvat F. On the uncertainties of photon mass energy-absorption coefficients and their ratios for radiation dosimetry. Phys Med Biol 2012; 57:2117-36. [DOI: 10.1088/0031-9155/57/8/2117] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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50
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Benmakhlouf H, Bouchard H, Fransson A, Andreo P. Backscatter factors and mass energy-absorption coefficient ratios for diagnostic radiology dosimetry. Phys Med Biol 2011; 56:7179-204. [DOI: 10.1088/0031-9155/56/22/012] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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