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Jermain PR, Muir B, McEwen M, Niu Y, Pang D. Accurate machine-specific reference and small-field dosimetry for a self-shielded neuro-radiosurgical system. Med Phys 2024; 51:4423-4433. [PMID: 38695760 DOI: 10.1002/mp.17111] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2024] [Revised: 03/14/2024] [Accepted: 04/18/2024] [Indexed: 06/05/2024] Open
Abstract
BACKGROUND The newly available ZAP-X stereotactic radiosurgical system is designed for the treatment of intracranial lesions, with several unique features that include a self-shielding, gyroscopic gantry, wheel collimation, non-orthogonal kV imaging, short source-axis distance, and low-energy megavoltage beam. Systematic characterization of its radiation as well as other properties is imperative to ensure its safe and effective clinical application. PURPOSE To accurately determine the radiation output of the ZAP-X with a special focus on the smaller diameter cones and an aim to provide useful recommendations on quantification of small field dosimetry. METHODS Six different types of detectors were used to measure relative output factors at field sizes ranging from 4 to 25 mm, including the PTW microSilicon and microdiamond diodes, Exradin W2 plastic scintillator, Exradin A16 and A1SL ionization chambers, and the alanine dosimeter. The 25 mm cone served as the reference field size. Absolute dose was determined with both TG-51-based dosimetry using a calibrated PTW Semiflex ion chamber and measurements using alanine dosimeters. RESULTS The average radiation output factors (maximum deviation from the average) measured with the microDiamond, microSilicon, and W2 detectors were: for the 4 mm cone, 0.741 (1.0%); for the 5 mm cone: 0.817 (1.0%); for the 7.5 mm cone: 0.908 (1.0%); for the 10 mm cone: 0.946 (0.4%); for the 12.5 mm cone: 0.964 (0.2%); for the 15 mm cone: 0.976 (0.1%); for the 20 mm cone: 0.990 (0.1%). For field sizes larger than 10 mm, the A1SL and A16 micro-chambers also yielded consistent output factors within 1.5% of those obtained using the microSilicon, microdiamond, and W2 detectors. The absolute dose measurement obtained with alanine was within 1.2%, consistent with combined uncertainties, compared to the PTW Semiflex chamber for the 25 mm reference cone. CONCLUSION For field sizes less than 10 mm, the microSilicon diode, microDiamond detector, and W2 scintillator are suitable devices for accurate small field dosimetry of the ZAP-X system. For larger fields, the A1SL and A16 micro-chambers can also be used. Furthermore, alanine dosimetry can be an accurate verification of reference and absolute dose typically measured with ion chambers. Use of multiple suitable detectors and uncertainty analyses were recommended for reliable determination of small field radiation outputs.
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Affiliation(s)
- Peter R Jermain
- Department of Radiation Medicine, Medstar Georgetown University Hospital, Washington, District of Columbia, USA
| | - Bryan Muir
- Metrology Research Centre, National Research Council, Ottawa, Ontario, Canada
| | - Malcolm McEwen
- Metrology Research Centre, National Research Council, Ottawa, Ontario, Canada
| | - Ying Niu
- Department of Radiation Medicine, Medstar Georgetown University Hospital, Washington, District of Columbia, USA
| | - Dalong Pang
- Department of Radiation Medicine, Medstar Georgetown University Hospital, Washington, District of Columbia, USA
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2
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Peters I, Nelson V, Deshpande S, Walker A, Hiatt J, Roach D, Erven T, Rajapakse S, Gray A. The assessment of the clinical impact of using a single set of radiotherapy planning data for two kilovoltage therapy units. Phys Eng Sci Med 2024; 47:49-59. [PMID: 37843767 DOI: 10.1007/s13246-023-01339-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2022] [Accepted: 09/14/2023] [Indexed: 10/17/2023]
Abstract
Kilovoltage therapy units are used for superficial radiotherapy treatment delivery. Peer reviewed studies for MV linear accelerators describe tolerances to dosimetrically match multiple linear accelerators enabling patient treatment on any matched machine. There is an absence of literature on using a single planning data set for multiple kilovoltage units which have limited ability for beam adjustment. This study reviewed kilovoltage dosimetry and treatment planning scenarios to evaluate the feasibility of using ACPSEM annual QA tolerances to determine whether two units (of the same make and model) were dosimetrically matched. The dosimetric characteristics, such as measured half value layer (HVL), percentage depth dose (PDD), applicator factor and output variation with stand-off distance for each kV unit were compared to assess the agreement. Independent planning data based on the measured HVL for each beam energy from each kV unit was prepared. Monitor unit (MU) calculations were performed using both sets of planning data for approximately 200 clinical scenarios and compared with an overall agreement between units of < 2%. Additionally, a dosimetry measurement comparison was completed at each site for a subset of nine scenarios. All machine characterisation measurements were within the ACPSEM Annual QA tolerances, and dosimetric testing was within 2.5%. This work demonstrates that using a single set of planning data for two kilovoltage units is feasible, resulting in a clinical impact within published uncertainty.
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Affiliation(s)
- Iliana Peters
- South Western Sydney Local Health District, Liverpool and Macarthur Cancer Therapy Centres, Sydney, NSW, Australia.
| | - Vinod Nelson
- South Western Sydney Local Health District, Liverpool and Macarthur Cancer Therapy Centres, Sydney, NSW, Australia
| | - Shrikant Deshpande
- South Western Sydney Local Health District, Liverpool and Macarthur Cancer Therapy Centres, Sydney, NSW, Australia
- Ingham Institute for Applied Medical Research, Liverpool, NSW, Australia
- South West Sydney Clinical School, School of Medicine, University of New South Wales, Sydney, NSW, Australia
| | - Amy Walker
- South Western Sydney Local Health District, Liverpool and Macarthur Cancer Therapy Centres, Sydney, NSW, Australia
- Ingham Institute for Applied Medical Research, Liverpool, NSW, Australia
- South West Sydney Clinical School, School of Medicine, University of New South Wales, Sydney, NSW, Australia
- Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW, Australia
| | - Joshua Hiatt
- South Western Sydney Local Health District, Liverpool and Macarthur Cancer Therapy Centres, Sydney, NSW, Australia
| | - Dale Roach
- South Western Sydney Local Health District, Liverpool and Macarthur Cancer Therapy Centres, Sydney, NSW, Australia
| | - Tania Erven
- South Western Sydney Local Health District, Liverpool and Macarthur Cancer Therapy Centres, Sydney, NSW, Australia
| | - Satya Rajapakse
- South Western Sydney Local Health District, Liverpool and Macarthur Cancer Therapy Centres, Sydney, NSW, Australia
| | - Alison Gray
- South Western Sydney Local Health District, Liverpool and Macarthur Cancer Therapy Centres, Sydney, NSW, Australia
- Ingham Institute for Applied Medical Research, Liverpool, NSW, Australia
- South West Sydney Clinical School, School of Medicine, University of New South Wales, Sydney, NSW, Australia
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Aspradakis MM, Buchillier T, Kohler G, Kottler C, Krayenbühl J. SSRMP Recommendations No 9: Reference dosimetry in low and medium energy x-ray beams. Z Med Phys 2023; 33:601-617. [PMID: 37202239 PMCID: PMC10751714 DOI: 10.1016/j.zemedi.2022.12.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Revised: 12/18/2022] [Accepted: 12/19/2022] [Indexed: 05/20/2023]
Abstract
The SSRMP recommendations on reference dosimetry in kilovolt beams as used in radiation therapy were revised to establish current practice in Switzerland. The recommendations specify the dosimetry formalism, reference class dosimeter systems and conditions used for the calibration of low and medium energy x-ray beams. Practical guidance is provided on the determination of the beam quality specifier and all corrections required for converting instrument readings to absorbed dose to water. Guidance is also provided on the determination of relative dose under non-reference conditions and on the cross calibration of instruments. The effect of lack of electron equilibrium and influence of contaminant electrons when using thin window plane parallel chambers at x-ray tube potentials higher than 50kV is elaborated in an appendix. In Switzerland the calibration of the reference system used for dosimetry is regulated by law. METAS and IRA are the authorities providing this calibration service to the radiotherapy departments. The last appendix of these recommendations summarise this calibration chain.
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Affiliation(s)
| | - Thierry Buchillier
- Institut de radiophysique (IRA), Rue du Grand-Pré 1, 1007 Lausanne, Switzerland
| | - Götz Kohler
- Klinik für Strahlentherapie und Radioonkologie, Universitätsspital Basel, Petersgraben 4, 4031 Basel, Switzerland
| | - Christian Kottler
- Eidgenössisches Institut für Metrologie (METAS), Lindenweg 50, 3003 Bern-Wabern, Switzerland
| | - Jérôme Krayenbühl
- Klinik für Radio-Onkologie, Universitätsspital Zürich, Rämistrasse 100, 8091 Zurich, Switzerland
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Shahhoseini E, Nakayama M, Panettieri V, Hall C, Feltis B, Geso M. Effects of synchrotron-based X-rays and gold nanoparticles on normal and cancer cell morphology and migration. JOURNAL OF SYNCHROTRON RADIATION 2023; 30:359-367. [PMID: 36891849 PMCID: PMC10000794 DOI: 10.1107/s1600577522012024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/31/2022] [Accepted: 12/21/2022] [Indexed: 06/18/2023]
Abstract
It has been shown lately that gold nanoparticles (AuNPs) and ionizing radiation (IR) have inhibitory effects on cancer cell migration while having promoting effects on normal cells' motility. Also, IR increases cancer cell adhesion with no significant effects on normal cells. In this study, synchrotron-based microbeam radiation therapy, as a novel pre-clinical radiotherapy protocol, is employed to investigate the effects of AuNPs on cell migration. Experiments were conducted utilizing synchrotron X-rays to investigate cancer and normal cell morphology and migration behaviour when they are exposed to synchrotron broad beams (SBB) and synchrotron microbeams (SMB). This in vitro study was conducted in two phases. In phase I two cancer cell lines - human prostate (DU145) and human lung (A549) - were exposed to various doses of SBB and SMB. Based on the phase I results, in phase II two normal cell lines were studied: human epidermal melanocytes (HEM) and human primary colon epithelial (CCD841), along with their respective cancerous counterparts, human primary melanoma (MM418-C1) and human colorectal adenocarcinoma (SW48). The results show that radiation-induced damage in cells' morphology becomes visible with SBB at doses greater than 50 Gy, and incorporating AuNPs increases this effect. Interestly, under the same conditions, no visible morphological changes were observed in the normal cell lines post-irradiation (HEM and CCD841). This can be attributed to the differences in cell metabolic and reactive oxygen species levels between normal and cancer cells. The outcome of this study highlights future applications of synchrotron-based radiotherapy, where it is possible to deliver extremely high doses to cancer tissues whilst preserving surrounding normal tissues from radiation-induced damage.
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Affiliation(s)
- Elham Shahhoseini
- Medical Radiation, RMIT University, 289 McKimmies Road, Bundoora, Victoria 3083, Australia
| | - Masao Nakayama
- Division of Radiation Oncology, Kobe University, 7-5-2 Kusunokicho Chuou-ku, Kobe 650-0017, Japan
| | - Vanessa Panettieri
- Alfred Health Radiation Oncology, 55 Commercial Road, Melbourne, Victoria 3004, Australia
| | - Chris Hall
- ANSTO, Australian Synchrotron, 800 Blackburn Road, Clayton, Victoria 3168, Australia
| | - Bryce Feltis
- Human Bioscience, RMIT University, 289 McKimmies Road, Bundoora, Victoria 3083, Australia
| | - Moshi Geso
- Medical Radiation, RMIT University, 289 McKimmies Road, Bundoora, Victoria 3083, Australia
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Nikandrovs M, McClean B, Shields L, McCavana P, Vintró LL. Clinical treatment planning for kilovoltage radiotherapy using EGSnrc and Python. J Appl Clin Med Phys 2023; 24:e13832. [PMID: 36444164 PMCID: PMC9924114 DOI: 10.1002/acm2.13832] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Revised: 09/22/2022] [Accepted: 10/05/2022] [Indexed: 12/02/2022] Open
Abstract
Kilovoltage radiotherapy dose calculations are generally performed with manual point dose calculations based on water dosimetry. Tissue heterogeneities, irregular surfaces, and introduction of lead cutouts for treatment are either not taken into account or crudely approximated in manual calculations. Full Monte Carlo (MC) simulations can account for these limitations but require a validated treatment unit model, accurately segmented patient tissues and a treatment planning interface (TPI) to facilitate the simulation setup and result analysis. EGSnrc was used in this work to create a model of Xstrahl kilovoltage unit extending the range of energies, applicators, and validation parameters previously published. The novel functionality of the Python-based framework developed in this work allowed beam modification using custom lead cutouts and shields, commonly present in kilovoltage treatments, as well as absolute dose normalization using the output of the unit. 3D user-friendly planning interface of the developed framework facilitated non-co-planar beam setups for CT phantom MC simulations in DOSXYZnrc. The MC models of 49 clinical beams showed good agreement with measured and reference data, to within 2% for percentage depth dose curves, 4% for beam profiles at various depths, 2% for backscatter factors, 0.5 mm of absorber material for half-value layers, and 3% for output factors. End-to-end testing of the framework using custom lead cutouts resulted in good agreement to within 3% of absolute dose distribution between simulations and EBT3 GafChromic film measurements. Gamma analysis demonstrated poor agreement at the field edges which was attributed to the limitations of simulating smooth cutout shapes. Dose simulated in a heterogeneous phantom agreed to within 7% with measured values converted using the ratio of mass energy absorption coefficients of appropriate tissues and air.
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Affiliation(s)
- Mihails Nikandrovs
- School of PhysicsUniversity College DublinBelfieldIreland
- St. Lukes Radiation Oncology NetworkDublinIreland
| | - Brendan McClean
- Centre for Physics in Health and MedicineUniversity College DublinBelfieldDublinIreland
- St. Lukes Radiation Oncology NetworkDublinIreland
| | - Laura Shields
- Centre for Physics in Health and MedicineUniversity College DublinBelfieldDublinIreland
- St. Lukes Radiation Oncology NetworkDublinIreland
| | - Patrick McCavana
- Centre for Physics in Health and MedicineUniversity College DublinBelfieldDublinIreland
- St. Lukes Radiation Oncology NetworkDublinIreland
| | - Luis León Vintró
- School of PhysicsUniversity College DublinBelfieldIreland
- Centre for Physics in Health and MedicineUniversity College DublinBelfieldDublinIreland
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Xiong Z, Zhong Y, Banks TI, Reynolds R, Chiu T, Tan J, Zhang Y, Parsons D, Yan Y, Godley A, Stojadinovic S. Machine characterization and central axis depth dose data of a superficial x-ray radiotherapy unit. Biomed Phys Eng Express 2022; 9. [PMID: 36541531 DOI: 10.1088/2057-1976/aca611] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2022] [Accepted: 11/23/2022] [Indexed: 11/27/2022]
Abstract
Objectives. The purpose of this study is to present data from the clinical commissioning of an Xstrahl 150 x-ray unit used for superficial radiotherapy,Methods. Commissioning tasks included vendor acceptance tests, timer reproducibility, linearity and end-effect measurements, half-value layer (HVL) measurements, inverse square law verification, head-leakage measurements, and beam output calibration. In addition, percent depth dose (PDD) curves were determined for different combinations of filter/kV settings and applicators. Automated PDD water phantom scans were performed utilizing four contemporary detectors: a microDiamond detector, a microSilicon detector, an EDGE detector, and a PinPoint ionization chamber. The measured PDD data were compared to the published values in BJR Supplement 25,Results. The x-ray unit's mechanical, safety, and radiation characteristics were within vendor-stated specifications. Across sixty commissioned x-ray beams, the PDDs determined in water using solid state detectors were in excellent agreement with the BJR 25 data. For the lower (<100 kVp) and medium-energy (≥100 kVp) superficial beams the average agreement was within [-3.6,+0.4]% and [-3.7,+1.4]% range, respectively. For the high-energy superficial (low-energy orthovoltage) x-rays at 150 kVp, the average difference for the largest 20 × 20 cm2collimator was (-0.7 ± 1.0)%,Conclusions. This study presents machine characterization data collected for clinical use of a superficial x-ray unit. Special focus was placed on utilizing contemporary detectors and techniques for the relative PDD measurements using a motorized water phantom. The results in this study confirm that the aggregate values published in the BJR 25 report still serve as a valid benchmark when comparing data from site-specific measurements, or the reference data for clinical utilization without such measurements,Advances in knowledge. This paper presents comprehensive data from the acceptance and commissioning of a modern kilovoltage superficial x-ray radiotherapy machine. Comparisons between the PDD data measured in this study using different detectors and BJR 25 data are highlighted.
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Affiliation(s)
- Zhenyu Xiong
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX, United States of America.,Department of Radiation Oncology, Rutgers Cancer Institute of New Jersey, Rutgers Robert Wood Johnson Medical School, New Brunswick, NJ, United States of America
| | - Yuncheng Zhong
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX, United States of America
| | - Thomas I Banks
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX, United States of America
| | - Robert Reynolds
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX, United States of America
| | - Tsuicheng Chiu
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX, United States of America
| | - Jun Tan
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX, United States of America
| | - You Zhang
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX, United States of America
| | - David Parsons
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX, United States of America
| | - Yulong Yan
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX, United States of America
| | - Andrew Godley
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX, United States of America
| | - Strahinja Stojadinovic
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX, United States of America
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Daniel J, Yousif Y, Zifodya J, Hill R. An evaluation of solid state detectors for the relative dosimetry of Kilovoltage x-ray beams. Med Phys 2022; 49:4082-4091. [PMID: 35179232 DOI: 10.1002/mp.15543] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Revised: 02/04/2022] [Accepted: 02/07/2022] [Indexed: 11/09/2022] Open
Abstract
INTRODUCTION Kilovoltage (kV) x-ray beams are an essential modality in radiotherapy. Solid state detectors are widely available in radiotherapy departments but their use for kV dosimetry has been limited to date. This study aimed to evaluate the dosimetric performance of a range of solid state detectors for kV dosimetry. METHOD Percentage depth doses (PDDs) and Relative Output Factors (ROFs) were measured on an XStrahl 300 unit (XStrahl-Ltd., UK) using 60, 100, 150 and 300 kVp x-ray beams. The fields were defined by circular applicators with field sizes of 2, 5, 8 and 10 cm diameter and square applicators of field sizes 10×10 and 20×20 cm2 . The following PTW dosimeters were used for measurements: Advanced Markus, PinPoint 3D and Semiflex ionization chambers; Photon, Electron and SRS diodes plus the microDiamond detector. All PDDs were normalized at 5 mm depth and ROFs were measured at 3 mm depth to avoid collisions with the end of the applicators. ROFs measured using chambers were corrected for polarity and ion-recombination effects. RESULTS AND DISCUSSION PDD measurements for 60,100 and 150 kVp beam exhibited good agreement between all diodes and the ionization chambers over the entire range of depths except in the first few millimeters near the surface. However, for the 300 kVp, all diode detectors exhibited an over-responding behaviour compared to reference depth dose data measured with the Advanced Markus chamber. Relative output factors with the diodes were higher than the Advanced Markus chamber at low energy, and the magnitude of these differences is inversely proportional to the field sizes. The PTW P diode showed the highest variation of up to 15% in the output factor compared to the Advanced Markus chamber. CONCLUSION This study evaluated the dosimetric performance of a range of solid state detectors in kV relative dosimetry. This study showed that diode detectors are a suitable replacement for ionization chambers for the PDD measurement of low energy kV beams (60-150 kVp) except for the PDD of 60 kVp with the smaller field sizes. However, an over-responding behaviour of diode detectors at 300 kVp beams shows that diode detectors are not suitable for the PDD measurement of high energy kV beams. Generally, all solid state detectors over responded to ROF measurements, indicating that it is not suitable for ROF measurements. In general, both shielded and unshielded diodes produced a similar dosimetric response, which demonstrates that the energy dependence of solid state detectors should be considered before they are used for any kV relative dosimetric measurements. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- John Daniel
- North West Cancer Centre, Tamworth, NSW, Australia
| | | | | | - Robin Hill
- Department of Radiation Oncology, Chris O'Brien Lifehouse, Sydney, Australia.,Institute of Medical Physics, School of Physics, University of Sydney, Australia.,Biomedical Innovation, Chris O'Brien Lifehouse, Missenden Rd, Camperdown, Sydney, Australia
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Kavun Y, Eskalen H, Kerli S, Kavgaci M. Fabrication and characterization of GdxFe 2O 3(100-x) /PVA (x=0, 5, 10, 20) composite films for radiation shielding. Appl Radiat Isot 2021; 177:109918. [PMID: 34481318 DOI: 10.1016/j.apradiso.2021.109918] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Revised: 07/18/2021] [Accepted: 08/23/2021] [Indexed: 01/16/2023]
Abstract
Purpose of this study is to investigate effect of gadolinium (Gd) content of GdxFe2O3(100-x), (x = 0, 5, 10, 20) composite system on structural, thermal, optical and radiation protection of poly (vinyl alchool) PVA based nanocomposite film. In this study, Gd doped Fe2O3 nanopowders (with Gd = 0, 5, 10 and 20) were synthesized by spray pyrolysis method. The characterization of these powders have been obtained by using X-ray diffractometer (XRD), scanning electron microscopy (SEM), and Uv-vis spectrometer. After then, GdxFe2O3(100-x)/PVA (x = 0, 5, 10, 20) polymer composite systems were prepared by solution casting technique. The structural, thermal and optical properties of obtained polymer composites have been examined. The irradiation properties of 6 MeV energized X-ray via cLINAC to obtain radiation shielding performance of these different percentage (0, 5, 10, and 20%) Gd doped Fe2O3 PVA thin films were also investigated. By using obtained results, the Linear Attenuation Coefficient (LAC), Half Value Layer (HVL), Tenth Value Layer (TVL), Mass Attenuation Coefficient (MAC). Also, theoretically Zeff value have been calculated. According to all obtained results, it has been seen that the different percentages (0, 5, 10, and 20%) Gd doped Fe2O3 PVA thin films can be used as radiation shielding material.
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Affiliation(s)
- Yusuf Kavun
- Vocational School of Health Services, Dept. of Medical Imaging Techniques, Kahramanmaras Sutcu Imam Univ, Kahramanmaras, Turkey.
| | - Hasan Eskalen
- Vocational School of Health Services, Department of Opticianry, Kahramanmaraş Sütçu İmam University, Kahramanmaraş, Turkey
| | - Süleyman Kerli
- Department of Energy Systems Engineering, İstiklal University, Kahramanmaraş, Turkey
| | - Mustafa Kavgaci
- Department of Physics, Kahramanmaras Sutcu Imam Univ, Kahramanmaras, Turkey
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Kaveckyte V, Carlsson Tedgren Å, Fernández-Varea JM. Impact of the I-value of diamond on the energy deposition in different beam qualities. Phys Med Biol 2021; 66. [PMID: 34014176 DOI: 10.1088/1361-6560/ac028f] [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: 02/01/2021] [Accepted: 05/18/2021] [Indexed: 11/12/2022]
Abstract
Diamond detectors are increasingly employed in dosimetry. Their response has been investigated by means of Monte Carlo (MC) methods, but there is no consensus on what mass densityρ, mean excitation energyIand number of conduction electrons per atomnceto use in the simulations. The ambiguity occurs due to its seeming similarity with graphite (both are carbon allotropes). Except for the difference inρbetween crystalline graphite (2.265 g cm-3) and diamond (3.515 g cm-3), their dielectric properties are assumed to be identical. This is incorrect, and the two materials should be distinguished: (ρ= 2.265 g cm-3,I= 81.0 eV,nce= 1) for graphite and (ρ= 3.515 g cm-3,I= 88.5 eV,nce= 0) for diamond. Simulations done with the MC codepenelopeshow that the energy imparted in diamond decreases by up to 1% with respect to 'pseudo-diamond' (ρ= 3.515 g cm-3,I= 81.0 eV,nce= 0) depending on the beam quality and cavity thickness. The energy imparted changed the most in cavities that are small compared with the range of electrons. The difference in the density-effect term relative to graphite was the smallest for diamond owing to an interplay effect thatρ,Iandncehave on this term, in contrast to pseudo-diamond media when eitherρorIalone were adjusted. The study also presents a parameterized density-effect correction function for diamond that may be used by MC codes like EGSnrc. Theestarprogram assumes thatnce= 2 for all carbon-based materials, hence it delivers an erroneous density-effect correction term for graphite and diamond. Despite the small changes of the energy imparted in diamond simulated with two differentIvalues and expected close-to-negligible deviation from the published small-field output correction data, it is important to pay attention to material properties and model the medium faithfully.
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Affiliation(s)
- Vaiva Kaveckyte
- Department of Health, Medicine and Caring Sciences, Linköping University, SE-58185 Linköping, Sweden.,Department of Medical Radiation Physics and Nuclear Medicine, Karolinska University Hospital, SE-17176 Stockholm, Sweden
| | - Åsa Carlsson Tedgren
- Department of Health, Medicine and Caring Sciences, Linköping University, SE-58185 Linköping, Sweden.,Department of Medical Radiation Physics and Nuclear Medicine, Karolinska University Hospital, SE-17176 Stockholm, Sweden
| | - José M Fernández-Varea
- Facultat de Física (FQA and ICC), Universitat de Barcelona, Diagonal 645, E-08028 Barcelona, Catalonia, Spain
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Muñoz Arango E, Beltrán Gómez C, Alaminos-Bouza A, de Almeida CE. Integrating X-ray kV millimetric field dosimetry with a synthetic diamond detector into the treatment planning system commissioning of a preclinical irradiator. Med Phys 2021; 48:4038-4052. [PMID: 33797098 DOI: 10.1002/mp.14869] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Revised: 02/28/2021] [Accepted: 03/07/2021] [Indexed: 11/09/2022] Open
Abstract
PURPOSE Small animal irradiators are equipped with x-ray beams and cone collimators with millimeter dimensions to be used in preclinical research. The use of small fields in the kV energy range may require the application of energy-dependent, field size-dependent, or depth-dependent correction factors to the dosimetric data acquired for treatment planning system (TPS) commissioning purposes to obtain accurate dose values. Considering that these corrections are also detector dependent, the suitability of a synthetic single-crystal diamond detector for small-field relative dosimetry in a preclinical irradiator (220-kVp) was evaluated to avoid the necessity of applying correction factors during TPS commissioning. METHODS The detector response was assessed during the transition for field sizes ranging from 20 × 20 mm2 to 3 × 3 mm2 , using the small animal radiation research platform (SARRP). The percentage depth dose distributions (PDDs), lateral profiles and output factors (OFs) were measured. The PDDs for the synthetic diamond detector were compared to the distributions acquired using a small-volume microchamber (0.016 cm3 ) and with Monte Carlo calculations using the MC3D in-house software package. The profiles and OFs were compared to the data from a silicon solid-state detector and to radiochromic film data provided by the manufacturer; for the OF determination, measurements made using a microchamber were added for comparison. The performance of several detectors used as references was previously validated for relative dosimetry in preclinical irradiators. A commercial TPS was commissioned for the factor-based algorithm, using the data acquired with the diamond detector, and no additional correction factors were applied. To verify the performance of the TPS and the accuracy of the dosimetric methodology, radiochromic film irradiation in water was conducted, and two-dimensional (2D) dose distributions in the coronal and axial planes were compared under different gamma criteria. RESULTS Compared with the microchamber and MC3D distributions, the agreement of the PDDs using the synthetic diamond detector was better than 2%. The profile data exhibited very good agreement compared with the data from the silicon detector, with an average and a maximum difference of 0.31 and 0.39 mm in the penumbras, respectively. Compared with the data from the radiochromic film, the average and maximum differences were equal to 0.77 and 0.89 mm, respectively. Very good agreement, within 1%, was obtained between the OFs measured with the synthetic diamond detector and the radiochromic film, compared only for the cone collimators. The validation of the TPS commissioning using gamma criteria compared to film showed an average passing rate of 100% and 93.2% with a global gamma criterion of 1 mm/3% for the coronal and axial planes, respectively, including the 3 × 3 mm2 field size and penumbra regions. CONCLUSIONS Synthetic diamond is a suitable detector for the complete relative dosimetry of small x-ray fields. The commissioning of the TPS with its own beam dosimetric data exhibited encouraging results even in a 3 × 3 mm2 field and penumbra region. This methodology allows for the prediction of 2D dose distributions with an accuracy in water ranging from 3 to 5% compared to the 2D distribution from film dosimetry.
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Affiliation(s)
- Erika Muñoz Arango
- Departamento de Ciências Radiológicas DCR, Universidade do Estado do Rio de Janeiro (UERJ), Rio de Janeiro, RJ, 20550-900, Brazil
| | | | | | - Carlos Eduardo de Almeida
- Departamento de Ciências Radiológicas DCR, Universidade do Estado do Rio de Janeiro (UERJ), Rio de Janeiro, RJ, 20550-900, Brazil
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Khan AU, Culberson WS, DeWerd LA. Characterizing a PTW microDiamond detector in kilovoltage radiation beams. Med Phys 2020; 47:4553-4562. [DOI: 10.1002/mp.14330] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Revised: 05/12/2020] [Accepted: 06/08/2020] [Indexed: 12/16/2022] Open
Affiliation(s)
- Ahtesham Ullah Khan
- Department of Medical Physics School of Medicine and Public Health University of Wisconsin‐Madison Madison Wisconsin53705USA
| | - Wesley S. Culberson
- Department of Medical Physics School of Medicine and Public Health University of Wisconsin‐Madison Madison Wisconsin53705USA
| | - Larry A. DeWerd
- Department of Medical Physics School of Medicine and Public Health University of Wisconsin‐Madison Madison Wisconsin53705USA
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Evaluation of dosimetric parameters of small fields of 6 MV flattening filter free photon beam measured using various detectors against Monte Carlo simulation. JOURNAL OF RADIOTHERAPY IN PRACTICE 2020. [DOI: 10.1017/s1460396920000114] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
AbstractPurpose:This study aims to evaluate dosimetric parameters like percentage depth dose, dosimetric field size, depth of maximum dose surface dose, penumbra and output factors measured using IBA CC01 pinpoint chamber, IBA stereotactic field diode (SFD), PTW microDiamond against Monte Carlo (MC) simulation for 6 MV flattening filter-free small fields.Materials and Methods:The linear accelerator used in the study was a Varian TrueBeam® STx. All field sizes were defined by jaws. The required shift to effective point of measurement was given for CC01, SFD and microdiamond for depth dose measurements. The output factor of a given field size was taken as the ratio of meter readings normalised to 10 × 10 cm2 reference field size without applying any correction to account for changes in detector response. MC simulation was performed using PRIMO (PENELOPE-based program). The phase space files for MC simulation were adopted from the MyVarian Website.Results and Discussion:Variations were seen between the detectors and MC, especially for fields smaller than 2 × 2 cm2 where the lateral charge particle equilibrium was not satisfied. Diamond detector was seen as most suitable for all measurements above 1 × 1 cm2. SFD was seen very close to MC results except for under-response in output factor measurements. CC01 was observed to be suitable for field sizes above 2 × 2 cm2. Volume averaging effect for penumbra measurements in CC01 was observed. No detector was found suitable for surface dose measurement as surface ionisation was different from surface dose due to the effect of perturbation of fluence. Some discrepancies in measurements and MC values were observed which may suggest effects of source occlusion, shift in focal point or mismatch between real accelerator geometry and simulation geometry.Conclusion:For output factor measurement, TRS483 suggested correction factor needs to be applied to account for the difference in detector response. CC01 can be used for field sizes above 2 × 2 cm2 and microdiamond detector is suitable for above 1 × 1 cm2. Below these field sizes, perturbation corrections and volume averaging corrections need to be applied.
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Muñoz Arango E, Peixoto JG, de Almeida CE. Small-field dosimetry with a high-resolution 3D scanning water phantom system for the small animal radiation research platform SARRP: a geometrical and quantitative study. ACTA ACUST UNITED AC 2020; 65:015012. [DOI: 10.1088/1361-6560/ab5c47] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Kaveckyte V, Persson L, Malusek A, Benmakhlouf H, Alm Carlsson G, Carlsson Tedgren Å. Investigation of a synthetic diamond detector response in kilovoltage photon beams. Med Phys 2019; 47:1268-1279. [PMID: 31880809 DOI: 10.1002/mp.13988] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Revised: 09/04/2019] [Accepted: 12/01/2019] [Indexed: 12/28/2022] Open
Abstract
PURPOSE An important characteristic of radiation dosimetry detectors is their energy response which consists of absorbed-dose and intrinsic energy responses. The former can be characterized using Monte Carlo (MC) simulations, whereas the latter (i.e., detector signal per absorbed dose to detector) is extracted from experimental data. Such a characterization is especially relevant when detectors are used in nonrelative measurements at a beam quality that differs from the calibration beam quality. Having in mind the possible application of synthetic diamond detectors (microDiamond PTW 60019, Freiburg, Germany) for nonrelative dosimetry of low-energy brachytherapy (BT) beams, we determined their intrinsic and absorbed-dose energy responses in 25-250 kV beams relative to a 60 Co beam, which is usually the reference beam quality for detector calibration in radiotherapy. MATERIAL AND METHODS Three microDiamond detectors and, for comparison, two silicon diodes (PTW 60017) were calibrated in terms of air-kerma free in air in six x-ray beam qualities (from 25 to 250 kV) and in terms of absorbed dose to water in a 60 Co beam at the national metrology laboratory in Sweden. The PENELOPE/penEasy MC radiation transport code was used to calculate the absorbed-dose energy response of the detectors (modeled based on blueprints) relative to air and water depending on calibration conditions. The MC results were used to extract the relative intrinsic energy response of the detectors from the overall energy response. Measurements using an independent setup with a single ophthalmic BEBIG I25.S16 125 I BT seed (effective photon energy of 28 keV) were used as a qualitative check of the extracted intrinsic energy response correction factors. Additionally, the impact of the thickness of the active volume as well as the presence of extra-cameral components on the absorbed-dose energy response of a microDiamond detector was studied using MC simulations. RESULTS The relative intrinsic energy response of the microDiamond detectors was higher by a factor of 2 in 25 and 50 kV beams compared to the 60 Co beam. The variation in the relative intrinsic energy response of silicon diodes was within 10% over the investigated photon energy range. The use of relative intrinsic energy response correction factors improved the agreement among the absorbed dose to water values determined using microDiamond detectors and silicon diodes, as well as with the TG-43 formalism-based calculations for the 125 I seed. MC study of microDiamond detector design features provided a possible explanation for inter-detector response variation at low-energy photon beams by differences in the effective thickness of the active volume. CONCLUSIONS MicroDiamond detectors had a non-negligible variation in the relative intrinsic energy response (factor of 2) which was comparable to that in the absorbed-dose energy response relative to water at low-energy photon beams. Silicon diodes, in contrast, had an absorbed-dose energy dependence on photon energy that varied by a factor of 6, whereas the intrinsic energy dependence on beam quality was within 10%. It is important to decouple these two responses for a full characterization of detector energy response especially when the user and reference beam qualities differ significantly, and MC alone is not enough.
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Affiliation(s)
- Vaiva Kaveckyte
- Radiation Physics, Department of Medical and Health Sciences, Linköping University, SE-581 85, Linköping, Sweden.,Department of Medical Radiation Physics and Nuclear Medicine, Karolinska University Hospital, SE-171 76, Stockholm, Sweden
| | - Linda Persson
- Swedish Radiation Safety Authority, SE-171 16, Stockholm, Sweden
| | - Alexandr Malusek
- Radiation Physics, Department of Medical and Health Sciences, Linköping University, SE-581 85, Linköping, Sweden
| | - Hamza Benmakhlouf
- Department of Medical Radiation Physics and Nuclear Medicine, Karolinska University Hospital, SE-171 76, Stockholm, Sweden
| | - Gudrun Alm Carlsson
- Radiation Physics, Department of Medical and Health Sciences, Linköping University, SE-581 85, Linköping, Sweden
| | - Åsa Carlsson Tedgren
- Radiation Physics, Department of Medical and Health Sciences, Linköping University, SE-581 85, Linköping, Sweden.,Department of Medical Radiation Physics and Nuclear Medicine, Karolinska University Hospital, SE-171 76, Stockholm, Sweden
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Johnstone CD, Therriault-Proulx F, Beaulieu L, Bazalova-Carter M. Characterization of a plastic scintillating detector for the Small Animal Radiation Research Platform (SARRP). Med Phys 2018; 46:394-404. [PMID: 30417377 DOI: 10.1002/mp.13283] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Revised: 10/07/2018] [Accepted: 10/30/2018] [Indexed: 11/09/2022] Open
Abstract
PURPOSE The purpose of this study was to characterize a small plastic scintillator developed for high resolution, real-time dosimetry of therapy and imaging x-ray beams delivered by an image-guided small animal irradiator. MATERIALS AND METHODS A 1 mm diameter, 1 mm long polystyrene BCF-60 scintillating fiber dosimeter was characterized with 220 kVp therapy and 40, 50, 60, 70, and 80 kVp imaging beams on the Small Animal Research Platform (SARRP). Scintillator output, sensitivity (charge per unit dose), linearity, and 0.2-mm resolution beam profile measurements were performed. A validated in-house Monte Carlo (MC) model of the SARRP was used to compute detailed energy spectra at locations of dosimetry, and validated scintillator measurement with MC simulations. Mass energy-absorption coefficients from the National Institute of Standards and Technology (NIST) tables convolved with MC-derived spectra were used in conjunction with Birks ionization quenching factors to correct scintillator output. An air kerma calibration method was employed to correct scintillator output for in-air beam profile measurements with open, 5 × 5, and 3 × 3 mm2 square field sizes, and compared to MC simulations. RESULTS Scintillator dose response showed excellent linearity (R2 ≥ 0.999) for all sensitivity measurements, including output as a function of tube current. Detector sensitivity was 2.41 μC Gy-1 for the 220 kVp therapy beam, and it ranged from 1.21 to 1.32 μC Gy-1 for the 40-80 imaging beams. Percentage difference in sensitivity between the therapy and imaging beams before sensitivity correction and after using the Birks quenching factors were 52.3% and 10.2%, respectively. Percentage differences between the therapy and imaging beam sensitivities after using the air kerma calibration method for in-air measurements was excellent and below 0.3%. In-air beam profile measurements agreed to MC simulations within a mean difference of 2.4% for the 5 × 5 and 3 × 3 mm2 field sizes, however, the scintillator showed signs of volume averaging at the penumbra edges. CONCLUSIONS A small plastic scintillator was characterized for therapy and imaging energies of a small animal irradiator, with output corrected for using an in-house MC model of the irradiator. The characterization of the scintillator detector system for small fields presents steps toward implementing real-time measurements for quality assurance and small animal treatment and imaging dose verification.
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Affiliation(s)
| | - François Therriault-Proulx
- Departement de Radio-Oncologie and Centre de recherche du CHU de Quebec, CHU de Quebec, Quebec, QC, G1R 3S1, Canada
| | - Luc Beaulieu
- Departement de Radio-Oncologie and Centre de recherche du CHU de Quebec, CHU de Quebec, Quebec, QC, G1R 3S1, Canada.,Departement de physique and Centre de recherche sur le Cancer, Université Laval, Quebec, QC, G1V 0A6, Canada
| | - Magdalena Bazalova-Carter
- Department of Physics and Astronomy, University of Victoria, Victoria, British Columbia, V8P 5C2, Canada
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Hill R, Healy B, Butler D, Odgers D, Gill S, Lye J, Gorjiara T, Pope D, Hill B. Australasian recommendations for quality assurance in kilovoltage radiation therapy from the Kilovoltage Dosimetry Working Group of the Australasian College of Physical Scientists and Engineers in Medicine. AUSTRALASIAN PHYSICAL & ENGINEERING SCIENCES IN MEDICINE 2018; 41:781-808. [DOI: 10.1007/s13246-018-0692-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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