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Oliver-Cañamás L, Vijande J, Candela-Juan C, Gimeno-Olmos J, Pujades-Claumarchirant MC, Rovira-Escutia JJ, Ballester F, Perez-Calatayud J. A User-Friendly System for Mailed Dosimetric Audits of 192Ir or 60Co HDR Brachytherapy Sources. Cancers (Basel) 2023; 15:cancers15092484. [PMID: 37173950 PMCID: PMC10177083 DOI: 10.3390/cancers15092484] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Revised: 04/21/2023] [Accepted: 04/24/2023] [Indexed: 05/15/2023] Open
Abstract
OBJECTIVES The main goal of this work is to design and characterize a user-friendly methodology to perform mailed dosimetric audits in high dose rate (HDR) brachytherapy for systems using either Iridium-192 (192Ir) or Cobalt-60 (60Co) sources. METHODS A solid phantom was designed and manufactured with four catheters and a central slot to place one dosimeter. Irradiations with an Elekta MicroSelectron V2 for 192Ir, and with a BEBIG Multisource for 60Co were performed for its characterization. For the dose measurements, nanoDots, a type of optically stimulated luminescent dosimeters (OSLDs), were characterized. Monte Carlo (MC) simulations were performed to evaluate the scatter conditions of the irradiation set-up and to study differences in the photon spectra of different 192Ir sources (Microselectron V2, Flexisource, BEBIG Ir2.A85-2 and Varisource VS2000) reaching the dosimeter in the irradiation set-up. RESULTS MC simulations indicate that the surface material on which the phantom is supported during the irradiations does not affect the absorbed dose in the nanoDot. Generally, differences below 5% were found in the photon spectra reaching the detector when comparing the Microselectron V2, the Flexisource and the BEBIG models. However, differences up to 20% are observed between the V2 and the Varisource VS2000 models. The calibration coefficients and the uncertainty in the dose measurement were evaluated. CONCLUSIONS The system described here is able to perform dosimetric audits in HDR brachytherapy for systems using either 192Ir or 60Co sources. No significant differences are observed between the photon spectra reaching the detector for the MicroSelectron V2, the Flexisource and the BEBIG 192Ir sources. For the Varisource VS2000, a higher uncertainty is considered in the dose measurement to allow for the nanoDot response.
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Affiliation(s)
- Laura Oliver-Cañamás
- Servei de Radiofísica i Protecció Radiològica, Consorci Hospitalari Provincial de Castelló (CHPC), 12002 Castelló de la Plana, Spain
| | - Javier Vijande
- Departamento de Física Atómica, Molecular y Nuclear, Universitat de Valencia (UV), 46100 Burjassot, Spain
- Unidad Mixta de Investigación en Radiofísica e Instrumentación Nuclear en Medicina (IRIMED), Instituto de Investigación Sanitaria La Fe (IIS-La Fe), Universitat de Valencia (UV), 46026 València, Spain
- Instituto de Física Corpuscular, Instituto de Física Corpuscular-IFIC (UV-CSIC), 46100 Burjassot, Spain
| | | | - Jose Gimeno-Olmos
- Unitat de Radiofísica, Servei d'Oncologia Radioteràpica, Hospital Universitari i Politècnic La Fe, 46026 València, Spain
| | | | - Juan J Rovira-Escutia
- Servei de Radiofísica i Protecció Radiològica, Consorci Hospital General Universitari de València, 46014 València, Spain
| | - Facundo Ballester
- Departamento de Física Atómica, Molecular y Nuclear, Universitat de Valencia (UV), 46100 Burjassot, Spain
- Unidad Mixta de Investigación en Radiofísica e Instrumentación Nuclear en Medicina (IRIMED), Instituto de Investigación Sanitaria La Fe (IIS-La Fe), Universitat de Valencia (UV), 46026 València, Spain
| | - Jose Perez-Calatayud
- Unidad Mixta de Investigación en Radiofísica e Instrumentación Nuclear en Medicina (IRIMED), Instituto de Investigación Sanitaria La Fe (IIS-La Fe), Universitat de Valencia (UV), 46026 València, Spain
- Unitat de Radiofísica, Servei d'Oncologia Radioteràpica, Hospital Universitari i Politècnic La Fe, 46026 València, Spain
- Hospital Clínica Benidorm, 03501 Benidorm, Spain
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Entezam A, Fielding A, Bradley D, Fontanarosa D. Absorbed dose calculation for a realistic CT-derived mouse phantom irradiated with a standard Cs-137 cell irradiator using a Monte Carlo method. PLoS One 2023; 18:e0280765. [PMID: 36730280 PMCID: PMC9928120 DOI: 10.1371/journal.pone.0280765] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2022] [Accepted: 01/07/2023] [Indexed: 02/03/2023] Open
Abstract
Computed tomography (CT) derived Monte Carlo (MC) phantoms allow dose determination within small animal models that is not feasible with in-vivo dosimetry. The aim of this study was to develop a CT-derived MC phantom generated from a mouse with a xenograft tumour that could then be used to calculate both the dose heterogeneity in the tumour volume and out of field scattered dose for pre-clinical small animal irradiation experiments. A BEAMnrc Monte-Carlo model has been built of our irradiation system that comprises a lead collimator with a 1 cm diameter aperture fitted to a Cs-137 gamma irradiator. The MC model of the irradiation system was validated by comparing the calculated dose results with dosimetric film measurement in a polymethyl methacrylate (PMMA) phantom using a 1D gamma-index analysis. Dose distributions in the MC mouse phantom were calculated and visualized on the CT-image data. Dose volume histograms (DVHs) were generated for the tumour and organs at risk (OARs). The effect of the xenographic tumour volume on the scattered out of field dose was also investigated. The defined gamma index analysis criteria were met, indicating that our MC simulation is a valid model for MC mouse phantom dose calculations. MC dose calculations showed a maximum out of field dose to the mouse of 7% of Dmax. Absorbed dose to the tumour varies in the range 60%-100% of Dmax. DVH analysis demonstrated that tumour received an inhomogeneous dose of 12 Gy-20 Gy (for 20 Gy prescribed dose) while out of field doses to all OARs were minimized (1.29 Gy-1.38 Gy). Variation of the xenographic tumour volume exhibited no significant effect on the out of field scattered dose to OARs. The CT derived MC mouse model presented here is a useful tool for tumour dose verifications as well as investigating the doses to normal tissue (in out of field) for preclinical radiobiological research.
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Affiliation(s)
- Amir Entezam
- School of Clinical Sciences, Queensland University of Technology, Brisbane, QLD, Australia
- Centre for Biomedical Technologies, Queensland University of Technology, Brisbane, QLD, Australia
- Translational Research Institute, The University of Queensland, Brisbane, QLD, Australia
- * E-mail:
| | - Andrew Fielding
- Centre for Biomedical Technologies, Queensland University of Technology, Brisbane, QLD, Australia
- School of Chemistry and Physics, Faculty of Science, Queensland University of Technology, Brisbane, QLD, Australia
| | - David Bradley
- Centre for Applied Physics and Radiation Technologies, Sunway University, PJ, Malaysia
- Department of Physics, University of Surrey, Guildford, United Kingdom
| | - Davide Fontanarosa
- School of Clinical Sciences, Queensland University of Technology, Brisbane, QLD, Australia
- Centre for Biomedical Technologies, Queensland University of Technology, Brisbane, QLD, Australia
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Seo IH, Lee J, Na D, Kyung H, Yang J, Lee S, Jeon SJ, Choi JW, Lee KY, Yi J, Han J, Yoo M, Kim SH. The Anti-Tumor Effect of Boron Neutron Capture Therapy in Glioblastoma Subcutaneous Xenograft Model Using the Proton Linear Accelerator-Based BNCT System in Korea. Life (Basel) 2022; 12:life12081264. [PMID: 36013445 PMCID: PMC9410173 DOI: 10.3390/life12081264] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2022] [Revised: 08/16/2022] [Accepted: 08/17/2022] [Indexed: 04/08/2023] Open
Abstract
Boron neutron capture therapy (BNCT) is a radiation therapy that selectively kills cancer cells and is being actively researched and developed around the world. In Korea, development of the proton linear accelerator-based BNCT system has completed development, and its anti-cancer effect in the U-87 MG subcutaneous xenograft model has been evaluated. To evaluate the efficacy of BNCT, we measured 10B-enriched boronophenylalanine (BPA) uptake in U-87 MG, FaDu, and SAS cells and evaluated cell viability by clonogenic assays. In addition, the boron concentration in the tumor, blood, and skin on the U-87 MG xenograft model was measured, and the tumor volume was measured for 4 weeks after BNCT. In vitro, the intracellular boron concentration was highest in the order of SAS, FaDu, and U-87 MG, and cell survival fractions decreased depending on the BPA treatment concentration and neutron irradiation dose. In vivo, the tumor volume was significantly decreased in the BNCT group compared to the control group. This study confirmed the anti-cancer effect of BNCT in the U-87 MG subcutaneous xenograft model. It is expected that the proton linear accelerator-based BNCT system developed in Korea will be a new option for radiation therapy for cancer treatment.
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Affiliation(s)
| | - Jeongwoo Lee
- A-BNCT Center, Dawonmedax, Incheon 21988, Korea
- Department of Pharmacy, ERICA Campus, Hanyang University, Ansan 15588, Korea
| | - Dasom Na
- A-BNCT Center, Dawonmedax, Incheon 21988, Korea
| | | | - Jieun Yang
- A-BNCT Center, Dawonmedax, Incheon 21988, Korea
| | | | | | | | | | - Jungyu Yi
- A-BNCT Center, Dawonmedax, Incheon 21988, Korea
- Department of Nuclear Engineering, Hanyang University, Seoul 04763, Korea
| | - Jaehwan Han
- A-BNCT Center, Dawonmedax, Incheon 21988, Korea
| | | | - Se Hyun Kim
- A-BNCT Center, Dawonmedax, Incheon 21988, Korea
- Correspondence: ; Tel.: +82-2-6251-4468
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Saini A, Pandey VP, Singh A, Kumar P. Evaluating impact of medium variation on dose calculated through planning system in a low cost in-house phantom. Biomed Phys Eng Express 2022; 8. [PMID: 35144251 DOI: 10.1088/2057-1976/ac53bc] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Accepted: 02/10/2022] [Indexed: 11/12/2022]
Abstract
Purpose:In radiotherapy, accuracy in dose estimation of dose calculation methods is critical. The influence of deformity on radiation dose calculations derived by planning system is evaluated in present study. The goal of study was to create a low-cost inhomogeneous phantom for measuring absorbed dose using an Ionisation chamber and Gafchromic film, which was validated using treatment planning system (TPS) dose outcome.Methods and Materials:The central axis dose calculations were computed using Pencil Beam Convolution algorithm (PBC), Collapsed Cone Convolution (CCC) and Monte Carlo (MC) algorithm in the Monaco treatment planning system using an In-house phantom (20x20x20cm3) made up of acrylic sheet containing water and inhomogeneous material wooden powder equivalent to lung. Phantom was scanned in Computed Tomography (CT) scanner and image set was sent to the planning workstation. The depth dose evaluations were performed using ionization chamber and Gafchromic film with same beam settings and monitor units in every setup. Following that, the calculated doses obtained from TPS and measured depth doses were compared.Results:The results was reported for photon energies 6MV, 10MV, 15MV, 6FFF and 10FFF at varying field sizes of 4X4 cm2, 5x5 cm2, 10x10 cm2, and 15x15 cm2. MC maximum dose variation predicted was 2.06% in 15MV of measured chamber dose and -2.06% of measured gafchromic film dose in 6MVFFF. CCC maximum dose variation predicted was 2.68% of measured chamber dose in 6MV and 3.31% of measured gafchromic film dose in 6MV whereas PB maximum dose variation predicted was -5.94% in 15MV of measured chamber dose and -11.6% of measured gafchromic film dose in 6MVFFF.Conclusion:Low-cost in-house phantoms can be utilised to assess point and planar doses during patient-specific quality assurance in centres that don't have accessibility to phantoms due to the high cost of commercially available tools.
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Affiliation(s)
- Amit Saini
- Chitkara Institute of Engineering and Technology, Chitkara University, Rajpura, Punjab, 140401, INDIA
| | - V P Pandey
- Department of Medical Physics, Hind Institute of Medical Sciences, Safedabad, Barabanki, Lucknow, Uttar Pradesh, 225003, INDIA
| | - Avtar Singh
- Chitkara Institute of Engineering and Technology, Chitkara University, Rajpura, Punjab, 140401, INDIA
| | - Pankaj Kumar
- Chitkara University, Centre for Liquid Crystal Research, Chitkara University Research and Innovation Network, Rajpura, Punjab, 140401, INDIA
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Kruszyna-Mochalska M, Skrobala A, Romanski P, Ryczkowski A, Suchorska W, Kulcenty K, Piotrowski I, Borowicz D, Matuszak N, Malicki J. Development of a quasi-humanoid phantom to perform dosimetric and radiobiological measurements for out-of-field doses from external beam radiation therapy. J Appl Clin Med Phys 2022; 23:e13514. [PMID: 35104047 PMCID: PMC8992956 DOI: 10.1002/acm2.13514] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Revised: 11/28/2021] [Accepted: 12/08/2021] [Indexed: 12/16/2022] Open
Abstract
Our understanding of low dose, out‐of‐field radiation and their radiobiological effects are limited, in part due to the rapid technological advances in external beam radiotherapy, especially for non‐coplanar and dynamic techniques. Reliable comparisons of out‐of‐field doses produced by advanced radiotherapy techniques are difficult due to the limitations of commercially available phantoms. There is a clear need for a functional phantom to accurately measure the dosimetric and radiobiological characteristics of out‐of‐field doses, which would in turn allow clinicians and medical physicists to optimize treatment parameters. We designed, manufactured, and tested the performance of a quasi‐humanoid (Q‐H) adult phantom. To test the physics parameters, we used computed tomography (CT) scans of assembled Q‐H phantom. Static open field and dynamic techniques were measured both in‐ and out‐of‐field with ionization chambers and radiochromic films for two configurations (full solid and with water‐filled containers). In the areas simulating soft tissues, lung, and bones, median Hounsfield units and densities were, respectively: 129.8, ‐738.7, 920.8 HU and 1.110, 0.215, 1.669 g/cm3. Comparison of the measured to treatment planning systems (TPS) in‐field dose values for the sample volumetric arc therapy (VMAT) (6 MV flattening filter‐free (FFF)) plan, 96.4% of analyzed points passed the gamma evaluation criteria (L2%/2 mm, threshold (TH) 10%) and less than 1.50% for point dose verification. In the two phantom configurations: full poly(methyl) methacrylate (PMMA) and with water container, the off‐axis median doses for open field, relative to the central axis of the beam (CAX) were similar, respectively: 0.900% versus 0.907% (15 cm distance to CAX); 0.096% versus 0.120% (35 cm); 0.018% versus 0.018% (52 cm); 0.009% versus 0.008% (74 cm). For VMAT 6 MV FFF, doses relative the CAX were, respectively: 0.667% (15 cm), 0.062% (35 cm), 0.019% (52 cm), 0.016% (74 cm). The Q‐H phantom meets the International Commission on Radiation Units and Measurements (ICRU) and American Association of Physicists in Medicine (AAPM) recommended phantom criteria, providing medical physicists with a reliable, comprehensive system to perform dose calculation and measurements and to assess the impact on radiobiological response and on the risk of secondary tumor induction.
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Affiliation(s)
- Marta Kruszyna-Mochalska
- Electroradiology Department, University of Medical Sciences, Poznan, Poland.,Medical Physics Department, Greater Poland Cancer Centre, Poznan, Poland
| | - Agnieszka Skrobala
- Electroradiology Department, University of Medical Sciences, Poznan, Poland.,Medical Physics Department, Greater Poland Cancer Centre, Poznan, Poland
| | - Piotr Romanski
- Medical Physics Department, Greater Poland Cancer Centre, Poznan, Poland
| | - Adam Ryczkowski
- Electroradiology Department, University of Medical Sciences, Poznan, Poland.,Medical Physics Department, Greater Poland Cancer Centre, Poznan, Poland
| | - Wiktoria Suchorska
- Electroradiology Department, University of Medical Sciences, Poznan, Poland.,Radiobiology Laboratories, Medical Physics Department, Greater Poland Cancer Centre, Poznan, Poland
| | - Katarzyna Kulcenty
- Radiobiology Laboratories, Medical Physics Department, Greater Poland Cancer Centre, Poznan, Poland
| | - Igor Piotrowski
- Electroradiology Department, University of Medical Sciences, Poznan, Poland.,Radiobiology Laboratories, Medical Physics Department, Greater Poland Cancer Centre, Poznan, Poland
| | - Dorota Borowicz
- Medical Physics Department, Greater Poland Cancer Centre, Poznan, Poland
| | - Natalia Matuszak
- Electroradiology Department, University of Medical Sciences, Poznan, Poland
| | - Julian Malicki
- Electroradiology Department, University of Medical Sciences, Poznan, Poland.,Medical Physics Department, Greater Poland Cancer Centre, Poznan, Poland
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Joubert MM, van Eeden D, du Plessis FCP. The relation between XR-QA2 and RT-QA2 Gafchromic TMfilm optical density and absorbed dose in water produced by radionuclides. Biomed Phys Eng Express 2021; 7. [PMID: 33601352 DOI: 10.1088/2057-1976/abe7c3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Accepted: 02/18/2021] [Indexed: 11/12/2022]
Abstract
Purpose. In this study, Monte Carlo (MC) simulations were done to relate the dose-response of the film to that in water. The effect of backscattering materials (PMMA, lead, polystyrene, and air) was investigated on its influence on film density for radionuclides including Am-241, Tc-99m, I-131, Cs-137.Methods. A BEAMnrc MC simulation was designed to score a phase-space file (PSF) below the container of the radionuclide under consideration to use as an input file for the subsequent DOSXYZnrc MC simulation. The geometry of the container holding the radionuclide was built using the component modules available in BEAMnrc. BEAMDP was used to investigate the container effect on the radionuclide spectrum as well as the fluence. The DOSXYZnrc simulation produced the absorbed dose in XR-QA2 and RT-QA2 GafchromicTMfilms. The DOSXYZnrc simulations were repeated for the GafchromicTMfilm now replaced with water to get the absorbed dose in water. From these results, conversion factors for the dose in water to the film dose for the different radionuclides, Am-241, Tc-99m, I-131, and Cs-137 were obtained. The actual film dose was calculated using the specific gamma exposure constant (Γ) at a distance of 50 cm for a point source approximation. From the BEAMnrc simulations, the particle fluence was extracted from PSFs to correct for the fluence at 0.1 cm below the sources from the fluence 50 cm away since the inverse square law will not apply to finite-size sources. The absorbed dose profiles in the film were compared to the absorbed dose profiles from the MC simulations.Results. A fitting function based on the neutron depletion model fits the optical density versus absorbed film dose data well and can be used as a calibration tool to obtain the film dose from its optical density. Lead as a backscatter material results in a higher optical density change but a lower absorbed dose. The XR-QA2 GafchromicTMfilm is more sensitive than the RT-QA2 GafchromicTMfilm, showing a more responsive optical density (OD) change in the energy range of radionuclides used in this study. Conversion factors were determined to convert the dose in water to the dose in GafchromicTMfilm. The Am-241 and I-131 simulated absorbed dose in the film to dose in water does not fluctuate as much as the simulated absorbed dose in film and water when using Tc-99m and Cs-137. Validation was shown for the comparison of the film and MC simulation absorbed dose profiles.Conclusions. MC BEAMnrc simulations are useful to simulate radionuclides and their containers. BEAMDP extracted energy spectra showed that the radionuclide containers produced a Compton effect on the energy spectra and added filtration on the lower spectral photon components. Extracted fluence ratios from PSFs were used to calculate the absorbed dose value at 0.1 cm distance from the source. By using the fit function, the dose in the film can be determined for known optical density values. The effect of the backscatter materials showed that the XR-QA2 GafchromicTMfilm results in higher optical density values than the RT-QA2 GafchromicTMfilm. The absorbed dose in both the films is comparable but not for a radionuclide such as Am-241 with an activity of 74MBq. The lead backscatter material showed to be the most prominent in optical density enhancement, and the air equivalent material was the least prominent. The XR-QA2 GafchromicTMfilm is the most sensitive and will be the best option if working with low energies. The absorbed dose in the XR-QA2 GafchromicTMfilm also showed a good comparison to the absorbed dose in water for the Am-241 radionuclide with an activity of 74MBq. The absorbed dose in the films compares well to the MC simulated doses.
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Affiliation(s)
- Maria M Joubert
- Department of Medical Physics, University of the Free State, Bloemfontein 9301, South Africa
| | - Déte van Eeden
- Department of Medical Physics, University of the Free State, Bloemfontein 9301, South Africa
| | - Freek C P du Plessis
- Department of Medical Physics, University of the Free State, Bloemfontein 9301, South Africa
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A comparison of Monte Carlo, anisotropic analytical algorithm (AAA) and Acuros XB algorithms in assessing dosimetric perturbations during enhanced dynamic wedged radiotherapy deliveries in heterogeneous media. JOURNAL OF RADIOTHERAPY IN PRACTICE 2018. [DOI: 10.1017/s1460396918000262] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
AbstractBackgroundA comparison of anisotropic analytical algorithm (AAA) and Acuros XB (AXB) dose calculation algorithms with Electron Gamma Shower (EGSnrc) Monte Carlo (MC) for modelling lung and bone heterogeneities encountered during enhanced dynamic wedged (EDWs) radiotherapy dose deliveries was carried out.Materials and methodsIn three heterogenous slab phantoms: water–bone, lung–bone and bone–lung, wedged percentage depth doses with EGSnrc, AAA and AXB algorithms for 6 MV photons for various field sizes (5×5, 10×10 and 20×20 cm2) and EDW angles (15°, 30°, 45° and 60°) have been scored.ResultsFor all the scenarios, AAA and AXB results were within ±1% of the MC in the pre-inhomogeneity region. For water–bone AAA and AXB deviated by 6 and 1%, respectively. For lung–bone an underestimation in lung (AAA: 5%, AXB: 2%) and overestimation in bone was observed (AAA: 13%, AXB: 4%). For bone–lung phantom overestimation in bone (AAA: 7%, AXB: 1%), a lung underdosage (AAA: 8%, AXB: 5%) was found. Post bone up to 12% difference in the AAA and MC results was observed as opposed to 6% in case of AXB.ConclusionThis study demonstrated the limitation of the AAA (in certain scenarios) and accuracy of AXB for dose estimation inside and around lung and bone inhomogeneities. The dose perturbation effects were found to be slightly dependent on the field size with no obvious EDW dependence.
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Kurudirek M. Effective atomic number of soft tissue, water and air for interaction of various hadrons, leptons and isotopes of hydrogen. Int J Radiat Biol 2017; 93:1299-1305. [PMID: 28978247 DOI: 10.1080/09553002.2018.1388546] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
PURPOSE Characterization of soft tissue, water and air in terms of effective atomic number (Zeff) with respect to the interactions of hadrons, leptons and isotopes of hydrogen. METHOD Mass collision stopping powers (MCSPs) were calculated first using Bethe formula. Then, these values were used to estimate Zeff using linear-logarithmic interpolation. A scale equation was also used to calculate MCSP. RESULTS Variation in Zeff, over the 0.5-50 MeV energy range considered, is minimum for muon and pion (π meson) interactions (relative difference [RD] ≤ 7%), while maximum variation has been noticed in Zefffor heavy charged particles, i.e. alpha particle (RD ≤ 26%). The highest values of Zeff were obtained for muon particle, the lightest particle while the minimum values of Zeff were obtained for alpha particle interaction. Except for very low kinetic energies, water equivalence of soft tissue is very satisfactory (RD ≤ 3%). The Zeff of water relative to air was found to be almost constant at high energies. The present results should be valid for especially high energies where the Bethe formula can be applied. This applies to relatively higher energies (>2 MeV) for heavier particles such as alpha particles and applies to relatively lower energies (>0.5 MeV) for lighter particles such as protons. CONCLUSIONS In view of the importance of water equivalence in particle therapy, new data on Zeff in soft tissue, water and air for fundamental particle interaction should be important. Results revealed that soft tissue could be considered as water equivalent for interaction of various fundamental particles.
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Affiliation(s)
- Murat Kurudirek
- a Department of Physics, Faculty of Science , Ataturk University , Erzurum , Turkey
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