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Das IJ, Khan AU, Dogan SK, Longo M. Grid/lattice therapy: consideration of small field dosimetry. Br J Radiol 2024; 97:1088-1098. [PMID: 38552328 PMCID: PMC11135801 DOI: 10.1093/bjr/tqae060] [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: 02/14/2024] [Revised: 03/11/2024] [Accepted: 03/14/2024] [Indexed: 05/31/2024] Open
Abstract
Small-field dosimetry used in special procedures such as gamma knife, Cyberknife, Tomotherapy, IMRT, and VMAT has been in evolution after several radiation incidences with very significant (70%) errors due to poor understanding of the dosimetry. IAEA-TRS-483 and AAPM-TG-155 have provided comprehensive information on small-fields dosimetry in terms of code of practice and relative dosimetry. Data for various detectors and conditions have been elaborated. It turns out that with a suitable detectors dose measurement accuracy can be reasonably (±3%) achieved for 6 MV beams for fields >1×1 cm2. For grid therapy, even though the treatment is performed with small fields created by either customized blocks, multileaf collimator (MLC), or specialized devices, it is multiple small fields that creates combined treatment. Hence understanding the dosimetry in collection of holes of small field is a separate challenge that needs to be addressed. It is more critical to understand the scattering conditions from multiple holes that form the treatment grid fields. Scattering changes the beam energy (softer) and hence dosimetry protocol needs to be properly examined for having suitable dosimetric parameters. In lieu of beam parameter unavailability in physical grid devices, MLC-based forward and inverse planning is an alternative path for bulky tumours. Selection of detectors in small field measurement is critical and it is more critical in mixed beams created by scattering condition. Ramification of small field concept used in grid therapy along with major consideration of scattering condition is explored. Even though this review article is focussed mainly for dosimetry for low-energy megavoltage photon beam (6 MV) but similar procedures could be adopted for high energy beams. To eliminate small field issues, lattice therapy with the help of MLC is a preferrable choice.
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Affiliation(s)
- Indra J Das
- Department of Radiation Oncology, Northwest Memorial Hospital, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, United States
| | - Ahtesham Ullah Khan
- San Bortolo Hospital, Medical Physics Department, Viale F. Rodolfi 37, 36100 Vicenza, Italy
| | - Serpil K Dogan
- Department of Radiation Oncology, Northwest Memorial Hospital, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, United States
| | - Mariaconcetta Longo
- San Bortolo Hospital, Medical Physics Department, Viale F. Rodolfi 37, 36100 Vicenza, Italy
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Kannan M, Saminathan S, Shwetha B, Chandraraj V, Raj DG, Ganesh KM. Validation of Microionization Chambers in Small-field Dosimetry. J Med Phys 2024; 49:285-293. [PMID: 39131427 PMCID: PMC11309149 DOI: 10.4103/jmp.jmp_9_24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2024] [Revised: 02/21/2024] [Accepted: 03/03/2024] [Indexed: 08/13/2024] Open
Abstract
Aim This study aims to validate the Razor Nano Chamber (RNC) and Razor Chamber (RC) dosimetric characteristics in a small field. The dosimetric parameters of the two chambers were compared. Materials and Methods The chamber characteristics of leakage (pre and post), stability, energy dependency, dose linearity, dose rate effect, stem effect, angular dependency, ion recombination effect, and polarity effect were studied. Relative dose measurements of the percentage depth dose, profile measurement, and output factor (OF) measurements were performed for small fields. All measurements were performed in a Theratron 780E telecobalt unit and an Elekta Versa HD™ Linear Accelerator. Results and Discussion The measured pre- and postirradiation leakage and energy dependency were within 0.5% of the acceptable limit. In the stability check, the standard error and standard error of mean were 0.047% and 0.068%, respectively, for both RNC and RC. The deviation in the angular responses of the RNC and RC ion chambers was negligible. In the ion recombination measurements, both the RNC and RC were overestimated for the 10 flattening filter-free photon beam. In small fields, there were no significant differences in the kpol values for either chamber. The RNC showed good agreement in the relative dose measurements compared to the RC. Conclusion RNC and RC showed good agreement in small-field dosimetry. The RNC angular dependency and OF showed a superior response compared to the RC because of the small volume spherical shape and high spatial resolution, which gives a reduced penumbra and no volume averaging effect.
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Affiliation(s)
- Mageshraja Kannan
- Department of Radiation Physics, Kidwai Memorial Institute of Oncology, Bengaluru, Karnataka, India
| | - Sathiyan Saminathan
- Department of Radiation Physics, Kidwai Memorial Institute of Oncology, Bengaluru, Karnataka, India
| | - B. Shwetha
- Department of Radiation Physics, Kidwai Memorial Institute of Oncology, Bengaluru, Karnataka, India
| | - Varatharaj Chandraraj
- Department of Radiation Physics, Kidwai Memorial Institute of Oncology, Bengaluru, Karnataka, India
| | - D. Gowtham Raj
- Department of Radiation Physics, Kidwai Memorial Institute of Oncology, Bengaluru, Karnataka, India
| | - K. M. Ganesh
- Department of Radiation Physics, Kidwai Memorial Institute of Oncology, Bengaluru, Karnataka, India
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Small field output factor measurement and verification for CyberKnife robotic radiotherapy and radiosurgery system using 3D polymer gel, ionization chamber, diode, diamond and scintillator detectors, Gafchromic film and Monte Carlo simulation. Appl Radiat Isot 2023; 192:110576. [PMID: 36473319 DOI: 10.1016/j.apradiso.2022.110576] [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: 08/22/2022] [Revised: 11/19/2022] [Accepted: 11/21/2022] [Indexed: 11/24/2022]
Abstract
The dosimetry of small fields has become tremendously important with the advent of intensity-modulated radiation therapy (IMRT) and stereotactic radiosurgery, where small field segments or very small fields are used to treat tumors. With high dose gradients in the stereotactic radiosurgery or radiotherapy treatment, small field dosimetry becomes challenging due to the lack of lateral electronic equilibrium in the field, x-ray source occlusion, and detector volume averaging. Small volume and tissue-equivalent detectors are recommended to overcome the challenges. With the lack of a perfect radiation detector, studies on available detectors are ongoing with reasonable disagreement and uncertainties. The joint IAEA and AAPM international code of practice (CoP) for small field dosimetry, TRS 483 (Alfonso et al., 2017) provides guidelines and recommendations for the dosimetry of small static fields in external beam radiotherapy. The CoP provides a methodology for field output factor (FOF) measurements and use of field output correction factors for a series of small field detectors and strongly recommends additional measurements, data collection and verification for CyberKnife (CK) robotic stereotactic radiotherapy/radiosurgery system using the listed detectors and more new detectors so that the FOFs can be implemented clinically. The present investigation is focused on using 3D gel along with some other commercially available detectors for the measurement and verification of field output factors (FOFs) for the small fields available in the CK system. The FOF verification was performed through a comparison with published data and Monte Carlo simulation. The results of this study have proved the suitability of an in-house developed 3D polymer gel dosimeter, several commercially available detectors, and Gafchromic films as a part of small field dosimetric measurements for the CK system.
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Evaluation of calibration methods of Exradin W2 plastic scintillation detector for CyberKnife small-field dosimetry. RADIAT MEAS 2022. [DOI: 10.1016/j.radmeas.2022.106821] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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Azadeh P, Amiri S, Mostaar A, Yaghobi Joybari A, Paydar R. Evaluation of MAGIC-f polymer gel dosimeter for dose profile measurement in small fields and stereotactic irradiation. Radiat Phys Chem Oxf Engl 1993 2022. [DOI: 10.1016/j.radphyschem.2022.109991] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Falco MD, Fusella M, Clemente S, Fiandra C, Gallio E, Garibaldi C, Bagalà P, Borzì G, Casale M, Casati M, Consorti R, Delana A, Esposito M, Malatesta T, Menghi E, Reggiori G, Russo S, Stasi M, Mancosu P. The influence of basic plan parameters on calculated small field output factors - A multicenter study. Phys Med 2021; 88:98-103. [PMID: 34217003 DOI: 10.1016/j.ejmp.2021.06.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Revised: 06/02/2021] [Accepted: 06/04/2021] [Indexed: 10/21/2022] Open
Abstract
PURPOSE The influence of basic plan parameters such as slice thickness, grid resolution, algorithm type and field size on calculated small field output factors (OFs) was evaluated in a multicentric study. METHODS AND MATERIALS Three computational homogeneous water phantoms with slice thicknesses (ST) 1, 2 and 3 mm were shared among twenty-one centers to calculate OFs for 1x1, 2x2 and 3x3 cm2 field sizes (FSs) (normalized to 10x10 cm2 FS), with their own treatment planning system (TPS) and the energy clinically used for stereotactic body radiation therapy delivery. OFs were calculated for each combination of grid resolution (GR) (1, 2 and 3 mm) and ST and finally compared with the OFs measured for the TPS commissioning. A multivariate analysis was performed to test the effect of basic plan parameters on calculated OFs. RESULTS A total of 509 data points were collected. Calculated OFs are slightly higher than measured ones. The multivariate analysis showed that Center, GR, algorithm type, and FS are predictive variables of the difference between calculated and measured OFs (p < 0.001). As FS decreases, the spread in the difference between calculated and measured OFs became larger when increasing the GR. Monte Carlo and Analytical Anisotropic Algorithms, presented a dependence on GR (p < 0.01), while Collapsed Cone Convolution and Acuros did not. The effect of the ST was found to be negligible. CONCLUSIONS Modern TPSs slightly overestimate the calculated small field OFs compared with measured ones. Grid resolution, algorithm, center number and field size influence the calculation of small field OFs.
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Affiliation(s)
- Maria Daniela Falco
- Department of Radiation Oncology, "G. D'Annunzio" University, "SS. Annunziata" Hospital, Chieti, Italy
| | - Marco Fusella
- Medical Physics Department, Veneto Institute of Oncology IOV-IRCCS, via Gattamelata 64, Padova, Italy
| | - Stefania Clemente
- Unit of Medical Physic and Radioprotection. Azienda Ospedaliera Universitaria Federico II, Naples, Italy
| | - Christian Fiandra
- Department of Oncology - Radiation Oncology, University of Turin, Turin, Italy
| | - Elena Gallio
- Department of Oncology - Radiation Oncology, University of Turin, Turin, Italy
| | - Cristina Garibaldi
- IEO, European Institute of Oncology IRCCS, Unit of Radiation Research, Milan, Italy
| | - Paolo Bagalà
- Universita' Campus Bio-medico di Roma, Via Alvaro del Portillo, 200 Rome, Italy
| | | | - Michelina Casale
- Struttura Semplice di Fisica Sanitaria Azienda Ospedaliera "Santa Maria" Terni, Italy
| | - Marta Casati
- MedicalPhysics Unit, Azienda Ospedaliero-Universitaria Careggi, Florence, Italy
| | - Rita Consorti
- Medical Physics Unit, S. Filippo Neri Hospital, ASL Roma 1, Rome, Italy
| | - Anna Delana
- Servizio di Fisica Sanitaria Ospedale S. Chiara A.P.S.S. Trento, Italy
| | - Marco Esposito
- Medical Physics Unit, Azienda USL Toscana Centro, Florence, Italy
| | - Tiziana Malatesta
- Fisica Medica, Ospedale Fatebenefratelli S.Giovanni Calibita- Rome, Italy
| | - Enrico Menghi
- Medical Physics Unit, Istituto Romagnolo per lo Studio dei Tumori "Dino Amadori" - IRST S.r.l.Istituto di Ricovero e Cura a Carattere Scientifico, Meldola (FC), Italy
| | - Giacomo Reggiori
- Medical Physics Unit of Radiation Oncology Dept., Humanitas Clinical and Research Hospital, Rozzano-Milan, Italy
| | - Serenella Russo
- Medical Physics Unit, Azienda USL Toscana Centro, Florence, Italy.
| | - Michele Stasi
- Medical Physics Department, A.O. Ordine Mauriziano, Turin, Italy
| | - Pietro Mancosu
- Medical Physics Unit of Radiation Oncology Dept., Humanitas Clinical and Research Hospital, Rozzano-Milan, Italy
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Das IJ, Francescon P, Moran JM, Ahnesjö A, Aspradakis MM, Cheng CW, Ding GX, Fenwick JD, Saiful Huq M, Oldham M, Reft CS, Sauer OA. Report of AAPM Task Group 155: Megavoltage photon beam dosimetry in small fields and non-equilibrium conditions. Med Phys 2021; 48:e886-e921. [PMID: 34101836 DOI: 10.1002/mp.15030] [Citation(s) in RCA: 53] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Revised: 05/06/2021] [Accepted: 06/02/2021] [Indexed: 12/14/2022] Open
Abstract
Small-field dosimetry used in advance treatment technologies poses challenges due to loss of lateral charged particle equilibrium (LCPE), occlusion of the primary photon source, and the limited choice of suitable radiation detectors. These challenges greatly influence dosimetric accuracy. Many high-profile radiation incidents have demonstrated a poor understanding of appropriate methodology for small-field dosimetry. These incidents are a cause for concern because the use of small fields in various specialized radiation treatment techniques continues to grow rapidly. Reference and relative dosimetry in small and composite fields are the subject of the International Atomic Energy Agency (IAEA) dosimetry code of practice that has been published as TRS-483 and an AAPM summary publication (IAEA TRS 483; Dosimetry of small static fields used in external beam radiotherapy: An IAEA/AAPM International Code of Practice for reference and relative dose determination, Technical Report Series No. 483; Palmans et al., Med Phys 45(11):e1123, 2018). The charge of AAPM task group 155 (TG-155) is to summarize current knowledge on small-field dosimetry and to provide recommendations of best practices for relative dose determination in small megavoltage photon beams. An overview of the issue of LCPE and the changes in photon beam perturbations with decreasing field size is provided. Recommendations are included on appropriate detector systems and measurement methodologies. Existing published data on dosimetric parameters in small photon fields (e.g., percentage depth dose, tissue phantom ratio/tissue maximum ratio, off-axis ratios, and field output factors) together with the necessary perturbation corrections for various detectors are reviewed. A discussion on errors and an uncertainty analysis in measurements is provided. The design of beam models in treatment planning systems to simulate small fields necessitates special attention on the influence of the primary beam source and collimating devices in the computation of energy fluence and dose. The general requirements for fluence and dose calculation engines suitable for modeling dose in small fields are reviewed. Implementations in commercial treatment planning systems vary widely, and the aims of this report are to provide insight for the medical physicist and guidance to developers of beams models for radiotherapy treatment planning systems.
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Affiliation(s)
- Indra J Das
- Department of Radiation Oncology, Northwestern Memorial Hospital, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - Paolo Francescon
- Department of Radiation Oncology, Ospedale Di Vicenza, Vicenza, Italy
| | - Jean M Moran
- Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, New York, NY, USA
| | - Anders Ahnesjö
- Medical Radiation Sciences, Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden
| | - Maria M Aspradakis
- Institute of Radiation Oncology, Cantonal Hospital of Graubünden, Chur, Switzerland
| | - Chee-Wai Cheng
- Department of Radiation Oncology, University Hospitals Cleveland Medical Center, Cleveland, OH, USA
| | - George X Ding
- Department of Radiation Oncology, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - John D Fenwick
- Molecular and Clinical Cancer Medicine, Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool, UK
| | - M Saiful Huq
- Department of Radiation Oncology, University of Pittsburgh, School of Medicine and UPMC Hillman Cancer Center, Pittsburgh, PA, USA
| | - Mark Oldham
- Department of Radiation Oncology, Duke University Medical Center, Durham, NC, USA
| | - Chester S Reft
- Department of Radiation Oncology, University of Chicago, Chicago, IL, USA
| | - Otto A Sauer
- Department of Radiation Oncology, Klinik fur Strahlentherapie, University of Würzburg, Würzburg, Germany
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Gonod M, Chacon Avila C, Suarez MA, Crouzilles J, Laskri S, Vinchant JF, Aubignac L, Grosjean T. Miniaturized scintillator dosimeter for small field radiation therapy. Phys Med Biol 2021; 66. [PMID: 33971635 DOI: 10.1088/1361-6560/abffbb] [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: 12/31/2020] [Accepted: 05/10/2021] [Indexed: 11/11/2022]
Abstract
The concept of a miniaturized inorganic scintillator detector is demonstrated in the analysis of the small static photon fields used in external radiation therapy. Such a detector is constituted by a 0.25 mm diameter and 0.48 mm long inorganic scintillating cell (1.6 × 10-5cm3detection volume) efficiently coupled to a narrow 125μm diameter silica optical fiber using a tiny photonic interface (an optical antenna). The response of our miniaturized scintillator detector (MSD) under 6 MV bremsstrahlung beam of various sizes (from 1 × 1 cm2to 4 × 4 cm2) is compared to that of two high resolution reference probes, namely, a micro-diamond detector and a dedicated silicon diode. The spurious Cerenkov signal transmitted through our bare detector is rejected with a basic spectral filtering. The MSD shows a linear response regarding the dose, a repeatability within 0.1% and a radial directional dependence of 0.36% (standard deviations). Beam profiling at 5 cm depth with the MSD and the micro-diamond detector shows a mismatch in the measurement of the full widths at 80% and 50% of the maximum which does not exceed 0.25 mm. The same difference range is found between the micro-diamond detector and a silicon diode. The deviation of the percentage depth dose between the MSD and micro-diamond detector remains below 2.3% within the first fifteen centimeters of the decay region for field sizes of 1 × 1 cm2, 2 × 2 cm2and 3 × 3 cm2(0.76% between the silicon diode and the micro-diamond in the same field range). The 2D dose mapping of a 0.6 × 0.6 cm2photon field evidences the strong 3D character of the radiation-matter interaction in small photon field regime. From a beam-probe convolution theory, we predict that our probe overestimates the beam width by 0.06%, making our detector a right compromise between high resolution, compactness, flexibility and ease of use. The MSD overcomes problem of volume averaging, stem effects, and despite its water non-equivalence it is expected to minimize electron fluence perturbation due to its extreme compactness. Such a detector thus has the potential to become a valuable dose verification tool in small field radiation therapy, and by extension in Brachytherapy, FLASH-radiotherapy and microbeam radiation therapy.
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Affiliation(s)
- Mathieu Gonod
- Centre Georges François Leclerc (CGFL)-Dijon, France
| | - Carlos Chacon Avila
- FEMTO-ST Institute-Optics Department-UMR 6174-University of Bourgogne Franche-Comté-CNRS-Besançon, France
| | - Miguel Angel Suarez
- FEMTO-ST Institute-Optics Department-UMR 6174-University of Bourgogne Franche-Comté-CNRS-Besançon, France
| | - Julien Crouzilles
- SEDI-ATI Fibres Optiques, 8 Rue Jean Mermoz, F-91080 Évry-Courcouronnes, France
| | - Samir Laskri
- SEDI-ATI Fibres Optiques, 8 Rue Jean Mermoz, F-91080 Évry-Courcouronnes, France
| | | | | | - Thierry Grosjean
- FEMTO-ST Institute-Optics Department-UMR 6174-University of Bourgogne Franche-Comté-CNRS-Besançon, France
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Rilling M, Allain G, Thibault S, Archambault L. Tomographic‐based 3D scintillation dosimetry using a three‐view plenoptic imaging system. Med Phys 2020; 47:3636-3646. [DOI: 10.1002/mp.14213] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Revised: 04/20/2020] [Accepted: 04/22/2020] [Indexed: 11/07/2022] Open
Affiliation(s)
- Madison Rilling
- Département de physique de génie physique et d’optique Faculté des sciences et de génie Université Laval 1045 avenue de la Médecine Québec QC G1V 0A6 Canada
- Centre d’optique photonique et laser Université Laval 2375 rue de la Terrasse Québec QC G1V 0A6 Canada
- Centre de recherche du CHU de Québec‐Université Laval Hôtel‐Dieu de Québec 11 Côte du Palais Québec QC G1R 2J6 Canada
- Centre de recherche sur le cancer de l’Université Laval 9 rue McMahon Québec QC G1R 3S3 Canada
| | - Guillaume Allain
- Département de physique de génie physique et d’optique Faculté des sciences et de génie Université Laval 1045 avenue de la Médecine Québec QC G1V 0A6 Canada
| | - Simon Thibault
- Département de physique de génie physique et d’optique Faculté des sciences et de génie Université Laval 1045 avenue de la Médecine Québec QC G1V 0A6 Canada
| | - Louis Archambault
- Département de physique de génie physique et d’optique Faculté des sciences et de génie Université Laval 1045 avenue de la Médecine Québec QC G1V 0A6 Canada
- Centre de recherche du CHU de Québec‐Université Laval Hôtel‐Dieu de Québec 11 Côte du Palais Québec QC G1R 2J6 Canada
- Centre de recherche sur le cancer de l’Université Laval 9 rue McMahon Québec QC G1R 3S3 Canada
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Galavis PE, Hu L, Holmes S, Das IJ. Characterization of the plastic scintillation detector Exradin W2 for small field dosimetry. Med Phys 2019; 46:2468-2476. [DOI: 10.1002/mp.13501] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2018] [Revised: 03/11/2019] [Accepted: 03/11/2019] [Indexed: 11/10/2022] Open
Affiliation(s)
- Paulina E. Galavis
- Department of Radiation Oncology New York University, Langone Medical Center & Laura and Issac Perlmutter Cancer Center New York NY 10016USA
| | - Lei Hu
- Department of Radiation Oncology New York University, Langone Medical Center & Laura and Issac Perlmutter Cancer Center New York NY 10016USA
| | | | - Indra J. Das
- Department of Radiation Oncology New York University, Langone Medical Center & Laura and Issac Perlmutter Cancer Center New York NY 10016USA
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Fukui Y, Hamada Y, Noma K, Harada N. [Characterization of Small Volume Plastic Scintillation Detector]. Nihon Hoshasen Gijutsu Gakkai Zasshi 2019; 75:652-658. [PMID: 31327776 DOI: 10.6009/jjrt.2019_jsrt_75.7.652] [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] [Indexed: 06/10/2023]
Abstract
Some radiation detectors are used for quality assurance and measured to radiation dose for high precision external beam radiotherapy. Recently, plastic scintillation detectors for MeV X-ray measurement are commercially released. The purpose of this study was to evaluate the performance of a commercial plastic scintillation detector with respect to the dose linearity, dose rate dependence, and the output coefficient compared the ionization chamber and the semiconductor detector using each different X-ray energy with or without flattening filter. The result that the dose linearity of each detector showed a linear response in any detectors. Dose rate dependence of plastic scintillation detector was increased when setting dose rate was changed, especially setting to low dose rate. The output coefficient of plastic scintillation detector was equivalent as that of the semiconductor detector even in smallest irradiation field. In conclusion, it was suggested that the plastic scintillation detector is a suitable detector in dose verification measurements for high precision external beam radiotherapy, although we must be with care to low dose rate measurements.
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Affiliation(s)
- Yusuke Fukui
- Radiology Service, Shiga University of Medical Science Hospital
| | - Yuto Hamada
- Radiology Service, Shiga University of Medical Science Hospital (Current address: Canon Medical Systems Corporation)
| | - Kazuo Noma
- Radiology Service, Shiga University of Medical Science Hospital
| | - Naoki Harada
- Radiology Service, Shiga University of Medical Science Hospital
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Madden L, Archer J, Li E, Wilkinson D, Rosenfeld A. Temporal separation of Cerenkov radiation and scintillation using a clinical LINAC and artificial intelligence. Phys Med Biol 2018; 63:225004. [PMID: 30412477 DOI: 10.1088/1361-6560/aae938] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Convolutional neural network (CNN) type artificial intelligences were trained to estimate the Cerenkov radiation present in the temporal response of a LINAC irradiated scintillator-fiber optic dosimeter. The CNN estimate of Cerenkov radiation is subtracted from the combined scintillation and Cerenkov radiation temporal response of the irradiated scintillator-fiber optic dosimeter, giving the sole scintillation signal, which is proportional to the scintillator dose. The CNN measured scintillator dose was compared to the background subtraction measured scintillator dose and ionisation chamber measured dose. The dose discrepancy of the CNN measured dose was on average 1.4% with respect to the ionisation chamber measured dose, matching the 1.4% average dose discrepancy of the background subtraction measured dose with respect to the ionisation chamber measured dose. The developed CNNs had an average time of 3 ms to calculate scintillator dose, permitting the CNNs presented to be applicable for dosimetry in real time.
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Affiliation(s)
- Levi Madden
- Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW 2522, Australia
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Reggiori G, Stravato A, Mancosu P, Lobefalo F, Paganini L, Zucconi F, Palumbo V, Gaudino A, Scorsetti M, Tomatis S. Small field characterization of a Nanochamber prototype under flattening filter free photon beams. Phys Med 2018; 49:139-146. [DOI: 10.1016/j.ejmp.2017.08.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/09/2017] [Revised: 08/04/2017] [Accepted: 08/16/2017] [Indexed: 11/28/2022] Open
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