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Ciarrocchi E, Ravera E, Cavalieri A, Celentano M, Del Sarto D, Di Martino F, Linsalata S, Massa M, Masturzo L, Moggi A, Morrocchi M, Pensavalle JH, Bisogni MG. Plastic scintillator-based dosimeters for ultra-high dose rate (UHDR) electron radiotherapy. Phys Med 2024; 121:103360. [PMID: 38692114 DOI: 10.1016/j.ejmp.2024.103360] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/10/2023] [Revised: 03/28/2024] [Accepted: 04/19/2024] [Indexed: 05/03/2024] Open
Abstract
This paper reports the development of dosimeters based on plastic scintillating fibers imaged by a charge-coupled device camera, and their performance evaluation through irradiations with the electron Flash research accelerator located at the Centro Pisano Flash Radiotherapy. The dosimeter prototypes were composed of a piece of plastic scintillating fiber optically coupled to a clear optical fiber which transported the scintillation signal to the readout systems (an imaging system and a photodiode). The following properties were tested: linearity, capability to reconstruct the percentage depth dose curve in solid water and to sample in time the single beam pulse. The stem effect contribution was evaluated with three methods, and a proof-of-concept one-dimensional array was developed and tested for online beam profiling. Results show linearity up to 10 Gy per pulse, and good capability to reconstruct both the timing and spatial profiles of the beam, thus suggesting that plastic scintillating fibers may be good candidates for low-energy electron Flash dosimetry.
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Affiliation(s)
- E Ciarrocchi
- University of Pisa, Department of Physics, Pisa, Italy; National Institute of Nuclear Physics, Section of Pisa, Pisa, Italy
| | - E Ravera
- University of Pisa, Department of Physics, Pisa, Italy; National Institute of Nuclear Physics, Section of Pisa, Pisa, Italy
| | - A Cavalieri
- University of Pisa, Department of Physics, Pisa, Italy; National Institute of Nuclear Physics, Section of Pisa, Pisa, Italy
| | - M Celentano
- University of Pisa, Department of Physics, Pisa, Italy; Azienda ospedaliero-universitaria pisana, U.O. Fisica Sanitaria, Pisa, Italy; Centro Pisano ricerca e implementazione clinical Flash Radiotherapy (CPFR-CISUP), Pisa, Italy
| | - D Del Sarto
- National Institute of Nuclear Physics, Section of Pisa, Pisa, Italy; Azienda ospedaliero-universitaria pisana, U.O. Fisica Sanitaria, Pisa, Italy; Centro Pisano ricerca e implementazione clinical Flash Radiotherapy (CPFR-CISUP), Pisa, Italy; University of Pisa, Center for Instrument Sharing of the University of Pisa (CISUP), Pisa, Italy
| | - F Di Martino
- National Institute of Nuclear Physics, Section of Pisa, Pisa, Italy; Azienda ospedaliero-universitaria pisana, U.O. Fisica Sanitaria, Pisa, Italy; Centro Pisano ricerca e implementazione clinical Flash Radiotherapy (CPFR-CISUP), Pisa, Italy
| | - S Linsalata
- Azienda ospedaliero-universitaria pisana, U.O. Fisica Sanitaria, Pisa, Italy
| | - M Massa
- National Institute of Nuclear Physics, Section of Pisa, Pisa, Italy
| | - L Masturzo
- University of Pisa, Department of Physics, Pisa, Italy; Azienda ospedaliero-universitaria pisana, U.O. Fisica Sanitaria, Pisa, Italy; Centro Pisano ricerca e implementazione clinical Flash Radiotherapy (CPFR-CISUP), Pisa, Italy; SIT Sordina IORT Technologies, Aprilia, Italy
| | - A Moggi
- National Institute of Nuclear Physics, Section of Pisa, Pisa, Italy
| | - M Morrocchi
- University of Pisa, Department of Physics, Pisa, Italy; National Institute of Nuclear Physics, Section of Pisa, Pisa, Italy.
| | - J H Pensavalle
- University of Pisa, Department of Physics, Pisa, Italy; Azienda ospedaliero-universitaria pisana, U.O. Fisica Sanitaria, Pisa, Italy; Centro Pisano ricerca e implementazione clinical Flash Radiotherapy (CPFR-CISUP), Pisa, Italy; SIT Sordina IORT Technologies, Aprilia, Italy
| | - M G Bisogni
- University of Pisa, Department of Physics, Pisa, Italy; National Institute of Nuclear Physics, Section of Pisa, Pisa, Italy; Centro Pisano ricerca e implementazione clinical Flash Radiotherapy (CPFR-CISUP), Pisa, Italy
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Wahabi JM, Ung NM, Mahdiraji GA, Wong JHD. Development and characterisation of a plastic scintillator dosemeter in high-energy photon beams. RADIATION PROTECTION DOSIMETRY 2024; 200:264-273. [PMID: 38123475 DOI: 10.1093/rpd/ncad303] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2023] [Revised: 10/22/2023] [Accepted: 11/15/2023] [Indexed: 12/23/2023]
Abstract
The radioluminescent (RL) dosemeter is excellent for real-time radiation measurement and can be used in various applications. A plastic scintillator is often the choice sensor because of its size and tissue equivalency. This study aims to characterise a novel plastic scintillator irradiated with high-energy photon beams. An RL dosimetry system was developed using the plastic scintillator. The RL dosimetry system was irradiated using a linear accelerator to characterise the dose linearity, dose rate, energy dependency and depth dose. The developed system showed a linear response toward the dose and dose rate. An energy dependency factor of 1.06 was observed. Depth dose measurement showed a mean deviation of 1.21% from the treatment planning system. The response and characteristics of the plastic scintillator show that it may be used as an alternative in an RL dosimetry system.
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Affiliation(s)
- Janatul M Wahabi
- Department of Biomedical Imaging, Faculty of Medicine, Universiti Malaya, Kuala Lumpur 50603, Malaysia
- Ministry of Health Malaysia, Putrajaya 62590, Malaysia
| | - N M Ung
- Clinical Oncology Unit, Faculty of Medicine, Universiti Malaya, Kuala Lumpur 50603, Malaysia
| | | | - Jeannie H D Wong
- Department of Biomedical Imaging, Faculty of Medicine, Universiti Malaya, Kuala Lumpur 50603, Malaysia
- Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW 2522, Australia
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Birajdar S, Zhang W, Santos A, Hickson K, Afshar Vahid S. Real-time in vivo dose measurement using ruby-based fibre optic dosimetry during internal radiation therapy. Phys Eng Sci Med 2023; 46:1205-1213. [PMID: 37395926 PMCID: PMC10480264 DOI: 10.1007/s13246-023-01288-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2022] [Accepted: 06/06/2023] [Indexed: 07/04/2023]
Abstract
In vivo dosimetry (IVD) in a commonly used liver cancer treatment of selective internal radiation therapy (SIRT) has been done based on the post-treatment image-based dosimetry approach. Real-time IVD is necessary to verify the dose delivery and detect errors during the treatment for better patient outcomes. This study aims to develop a fibre optic dosimeter (FOD) for in vivo real-time dose rate measurement during internal beta radiation therapy, e.g., SIRT. A ruby fibre optic probe was prepared and studied the radioluminescence (RL) characteristics, including its major challenge of stem effect arising from Cherenkov radiation and luminescence from the irradiated fibre. The stem signal was suppressed adequately using the stem removal technique of optical filtering, and only 2.3 ± 1.1% stem signal was contributed to the measured RL signal. A linear dose rate response was observed during the exposure of the ruby probe to varying dose rates using a 6 MeV electron beam and a positron-emitting radionuclide fluorine-18. The ruby exhibited a temporally non-constant RL signal, which increased the RL signal by 0.84 ± 0.29 counts/sec2 during the irradiation of the maximum dose rate used in this study of 9 Gy/min for 2 min. The ability of ruby FOD to measure the absolute dose rate with sufficient stem effect suppression and the linear RL dose rate response indicates its suitability for real-time IVD during internal beta radiation therapy. Future work will investigate the time-dependent RL characteristic of ruby and validate post-treatment image-based dosimetry using ruby-based FOD.
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Affiliation(s)
- S Birajdar
- Laser Physics and Photonic Devices Laboratories, UNISA STEM, The University of South Australia, Adelaide, SA, 5095, Australia.
| | - W Zhang
- Laser Physics and Photonic Devices Laboratories, UNISA STEM, The University of South Australia, Adelaide, SA, 5095, Australia
| | - A Santos
- Department of Radiation Oncology, Royal Adelaide Hospital, Adelaide, SA, 5000, Australia
- School of Physical Sciences, The University of Adelaide, Adelaide, SA 5005, Australia
- Australian Bragg Centre for Proton Therapy and Research, Adelaide, SA, 5000, Australia
| | - K Hickson
- Medical Physics & Radiation Protection Group, SA Medical Imaging, Adelaide, SA, 5000, Australia
- Allied Health & Human Performance, University of South Australia, Adelaide, SA, 5001, Australia
| | - S Afshar Vahid
- Laser Physics and Photonic Devices Laboratories, UNISA STEM, The University of South Australia, Adelaide, SA, 5095, Australia
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Preliminary study on radioluminescence dose rate measurement of α-Al2O3:C coupled to SiPM. RADIAT MEAS 2022. [DOI: 10.1016/j.radmeas.2022.106851] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Xie T, He B, Shi Q, Qian J, Hao W, Li S, Lewis E, Sun W. Measurement of scattered rays from different materials using an inorganic scintillator based optical fiber sensor and its application in radiotherapy. Biomed Phys Eng Express 2022; 8. [PMID: 34991079 DOI: 10.1088/2057-1976/ac48e3] [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: 09/18/2021] [Accepted: 01/06/2022] [Indexed: 11/12/2022]
Abstract
Measurements using an Optical Fiber OFS including an inorganic scintillator placed on the surface of a phantom show that the particle energy distribution inside the phantom remains unchanged. The backscattered intensity measured using an Optical Fiber Sensor (OFS) exhibits a linear relationship with the total radiation dose delivered to the phantom, and this relationship shows that the OFS can be used for indirect dose measurement when located on the surface of the phantom i.e. that arising from the energetic backscattered electrons and photons. Such a device can therefore be used as a clinicalin-vivodosimeter, being located on the patient's body surface. In addition, the measurement results for the same OFS located inside and outside the radiation field of a compound water based phantom are analyzed. The differences in measurement of the fluorescence signal in response to various tissue materials representing bone or tumor tissue in the irradiation field are strongly related to the material's ability to block the scattered rays from the water phantom, as well as the scattered x-rays generated by the material located within the phantom.
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Affiliation(s)
- Tianci Xie
- Key Lab of In-fiber Integrated Optics, Ministry Education of China, Harbin Engineering University, Harbin 150001, People's Republic of China
| | - Bo He
- Key Lab of In-fiber Integrated Optics, Ministry Education of China, Harbin Engineering University, Harbin 150001, People's Republic of China
| | - Qieming Shi
- Key Lab of In-fiber Integrated Optics, Ministry Education of China, Harbin Engineering University, Harbin 150001, People's Republic of China
| | - Jinqian Qian
- Key Lab of In-fiber Integrated Optics, Ministry Education of China, Harbin Engineering University, Harbin 150001, People's Republic of China
| | - Wenjing Hao
- Key Lab of In-fiber Integrated Optics, Ministry Education of China, Harbin Engineering University, Harbin 150001, People's Republic of China
| | - Song Li
- Key Lab of In-fiber Integrated Optics, Ministry Education of China, Harbin Engineering University, Harbin 150001, People's Republic of China
| | - Elfed Lewis
- Optical Fiber Sensors Research Centre, University of Limerick, Castletroy, Limerick, Ireland
| | - Weimin Sun
- Key Lab of In-fiber Integrated Optics, Ministry Education of China, Harbin Engineering University, Harbin 150001, People's Republic of China
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Linares Rosales HM, Couture G, Archambault L, Beddar S, Després P, Beaulieu L. On the use of machine learning methods for mPSD calibration in HDR brachytherapy. Phys Med 2021; 91:73-79. [PMID: 34717139 DOI: 10.1016/j.ejmp.2021.10.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/11/2021] [Revised: 07/15/2021] [Accepted: 10/02/2021] [Indexed: 11/17/2022] Open
Abstract
We sought to evaluate the feasibility of using machine learning (ML) algorithms for multipoint plastic scintillator detector (mPSD) calibration in high-dose-rate (HDR) brachytherapy. Dose measurements were conducted under HDR brachytherapy conditions. The dosimetry system consisted of an optimized 1-mm-core mPSD and a compact assembly of photomultiplier tubes coupled with dichroic mirrors and filters. An 192Ir source was remotely controlled and sent to various positions in a homemade PMMA holder, ensuring 0.1-mm positional accuracy. Dose measurements covering a range of 0.5 to 12 cm of source displacement were carried out according to TG-43 U1 recommendations. Individual scintillator doses were decoupled using a linear regression model, a random forest estimator, and artificial neural network algorithms. The dose predicted by the TG-43U1 formalism was used as the reference for system calibration and ML algorithm training. The performance of the different algorithms was evaluated using different sample sizes and distances to the source for the mPSD system calibration. We found that the calibration conditions influenced the accuracy in predicting the measured dose. The decoupling methods' deviations from the expected TG-43 U1 dose generally remained below 20%. However, the dose prediction with the three algorithms was accurate to within 7% relative to the dose predicted by the TG-43 U1 formalism when measurements were performed in the same range of distances used for calibration. In such cases, the predictions with random forest exhibited minimal deviations (<2%). However, the performance random forest was compromised when the predictions were done beyond the range of distances used for calibration. Because the linear regression algorithm can extrapolate the data, the dose prediction by the linear regression was less influenced by the calibration conditions than random forest. The linear regression algorithm's behavior along the distances to the source was smoother than those for the random forest and neural network algorithms, but the observed deviations were more significant than those for the neural network and random forest algorithms. The number of available measurements for training purposes influenced the random forest and neural network models the most. Their accuracy tended to converge toward deviation values close to 1% from a number of dwell positions greater than 100. In performing HDR brachytherapy dose measurements with an optimized mPSD system, ML algorithms are good alternatives for precise dose reporting and treatment assessment during this kind of cancer treatment.
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Affiliation(s)
- Haydee M Linares Rosales
- Département de physique, de génie physique et d'optique et Centre de recherche sur le cancer, Université Laval, Québec, Canada; Département de radio-oncologie et Axe Oncologie du CRCHU de Québec, CHU de Québec - Université Laval, QC, Canada.
| | - Gabriel Couture
- Département de physique, de génie physique et d'optique et Centre de recherche sur le cancer, Université Laval, Québec, Canada; Département de radio-oncologie et Axe Oncologie du CRCHU de Québec, CHU de Québec - Université Laval, QC, Canada
| | - Louis Archambault
- Département de physique, de génie physique et d'optique et Centre de recherche sur le cancer, Université Laval, Québec, Canada; Département de radio-oncologie et Axe Oncologie du CRCHU de Québec, CHU de Québec - Université Laval, QC, Canada
| | - Sam Beddar
- Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, TX, United States; The University of Texas MD Anderson UTHealth Graduate School of Biomedical Sciences, Houston, TX, United States
| | - Philippe Després
- Département de physique, de génie physique et d'optique et Centre de recherche sur le cancer, Université Laval, Québec, Canada; Département de radio-oncologie et Axe Oncologie du CRCHU de Québec, CHU de Québec - Université Laval, QC, Canada
| | - Luc Beaulieu
- Département de physique, de génie physique et d'optique et Centre de recherche sur le cancer, Université Laval, Québec, Canada; Département de radio-oncologie et Axe Oncologie du CRCHU de Québec, CHU de Québec - Université Laval, QC, Canada
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Simiele E, Viscariello N, DeWerd L. Monte Carlo modeling of the influence of strong magnetic fields on the stem-effect in plastic scintillation detectors used in radiotherapy dosimetry. Med Phys 2021; 48:1381-1394. [PMID: 33283279 DOI: 10.1002/mp.14637] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Revised: 10/03/2020] [Accepted: 11/23/2020] [Indexed: 11/07/2022] Open
Abstract
PURPOSE To investigate the impact of strong magnetic fields on the stem-effect in plastic scintillation detectors (PSDs) using Monte Carlo methods. METHODS Prior to building the light guide model, the properties of the Čerenkov process in GEANT4 were investigated by simulating depth-dose and depth-Čerenkov emission profiles in water as functions of Čerenkov process input parameters. In addition, profile simulations were performed for magnetic field strengths ranging from 0 T to 1.5 T. A PMMA light guide was constructed in GEANT4 using data from the manufacturer and literature. Simulations were performed with the model as functions of depth and fiber-beam angle where the simulated stem-effect spectrum and the Čerenkov light ratio (CLR) were scored and compared to measured data in the literature. The light guide optical properties were iteratively adjusted until agreement between the simulated and measured data was achieved. Simulations were performed with the validated model as functions of depth and magnetic field strength and the simulated data were compared to measured data in the literature. The model was also used to evaluate the sensitivity of the CLR to the various optical properties of the light guide in different irradiation conditions. RESULTS No significant changes in the depth-dose or depth-Čerenkov emission profiles were observed with step-size restrictions imposed by the Čerenkov process input parameters, which was attributed to the condensed history algorithm and transport parameters used in this work. Similar changes in the depth-dose and depth-Čerenkov emission profiles were observed with increasing magnetic field strength, which indicates the Čerenkov process is not adversely impacted by the presence of the magnetic field. Following optimization of the light guide optical properties, agreement within two standard deviations was observed between the simulated and measured optical data for all validation geometries considered. Agreement within one standard deviation was observed between the simulated and measured data for all depths and field strengths ≥0 T whereas discrepancies were observed for magnetic field strengths <-0.35 T. These significant differences were attributed to insufficient measurement data for this irradiation configuration during model validation. Of the light guide optical properties investigated, the fluorescence signal had the greatest impact on the CLR sensitivity to the magnetic field. CONCLUSIONS No significant change in the Čerenkov emission per dose in water was observed for magnetic field strengths up to 1.5 T. The nominal fiber fluorescence signal was found to have a significant impact on the CLR sensitivity to varying irradiation conditions where changes up to 11.7% were observed whereas the mirror reflectivity and fiber attenuation had a modest impact with maximum CLR changes of 2.6% and 1.2% relative to 0 T, respectively. The results of this work suggest light guides with low fiber fluorescence should be used with PSDs for dosimetry measurements in magnetic fields to minimize the impact of the magnetic field on the CLR correction.
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Affiliation(s)
- E Simiele
- Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, 53705, USA
| | - N Viscariello
- Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, 53705, USA
| | - L DeWerd
- Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, 53705, USA
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Ding L, Wu Q, Wang Q, Li Y, Perks RM, Zhao L. Advances on inorganic scintillator-based optic fiber dosimeters. EJNMMI Phys 2020; 7:60. [PMID: 33025267 PMCID: PMC7538482 DOI: 10.1186/s40658-020-00327-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2019] [Accepted: 09/03/2020] [Indexed: 12/19/2022] Open
Abstract
This article presents a new perspective on the development of inorganic scintillator-based fiber dosimeters (IOSFDs) for medical radiotherapy dosimetry (RTD) focusing on real-time in vivo dosimetry. The scintillator-based optical fiber dosimeters (SFD) are compact, free of electromagnetic interference, radiation-resistant, and robust. They have shown great potential for real-time in vivo RTD. Compared with organic scintillators (OSs), inorganic scintillators (IOSs) have larger X-ray absorption and higher light output. Variable IOSs with maximum emission peaks in the red part of the spectrum offer convenient stem effect removal. This article outlines the main advantages and disadvantages of utilizing IOSs for SFD fabrication. IOSFDs with different configurations are presented, and their use for dosimetry in X-ray RT, brachytherapy (BT), proton therapy (PT), and boron neutron capture therapy (BNCT) is reviewed. Challenges including the percentage depth dose (PDD) deviation from the standard ion chamber (IC) measurement, the angular dependence, and the Cherenkov effect are discussed in detail; methods to overcome these problems are also presented.
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Affiliation(s)
- Liang Ding
- School of Engineering, Cardiff University, Cardiff, UK
| | - Qiong Wu
- Department of Pharmacy, General Hospital of Southern Theatre Command, Guangzhou, China
| | - Qun Wang
- Department of Pharmacy, Shanghai Baoshan Luodian Hospital, Shanghai, China
| | - Yamei Li
- Department of Pharmacy, Shanghai Baoshan Luodian Hospital, Shanghai, China
| | | | - Liang Zhao
- Department of Pharmacy, Shanghai Baoshan Luodian Hospital, Shanghai, China
- Institute for Translational Medicine Research, Shanghai University, Shanghai, China
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Kim TJ, Cheng K, Zhang H, Liu S, Skinner L, Xing L. Second window near-infrared dosimeter (NIR2D) system for radiation dosimetry. Phys Med Biol 2020; 65:175013. [PMID: 32869751 DOI: 10.1088/1361-6560/ab9b56] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Fiber-coupled scintillation dosimeters are a cost-effective alternative to the conventional ion chambers in radiation dosimetry. However, stem effects from optical fibers such as Cerenkov radiation incur significant errors in the readout signal. Here we introduce a second near-infrared window dosimeter, dubbed as NIR2D, that can potentially be used as real-time radiation detector for clinical megavoltage beams. Lanthanide-based rare-earth NaYF4 nano-phosphors doped with both erbium and cerium elements were synthesized, and a compact 3D printed reader device integrated with a photodetector and data acquisition system was designed. The performance of the NIR2D was tested using a pre-clinical orthovoltage radiation source and a clinical megavoltage radiation source. The system was tested for dose linearity (100, 200, 600 MU), dose rate dependency (100, 200, 400, 600 MU min-1), and energy dependency (6, 10, 15 MV). Test results with the clinical linear accelerator demonstrated excellent dose linearity and dose rate independency when exposed to 6 MV linac beams-both data follows a linear trendline with R2 > 0.99. On the other hand, the NIR2D was energy dependent, where the readout dropped by 9% between 6 and 15 MV. For stem effects, we observed a finite Cerenkov contribution of 1%-3% when exposed between 100-600 MU min-1 (6 MV) and 3%-6% when exposed between 5-15 MV (600 MU min-1). While the stem effects were still observable, we expect that enhancing the current optical setup will simultaneously improve the scintillation signal and reduce the stem effects.
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Affiliation(s)
- Tae Jin Kim
- Department of Radiation Oncology, Stanford University, Stanford, CA 94305, United States of America. These authors contributed equally to this work
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Yada R, Maenaka K, Miyamoto S, Okada G, Sasakura A, Ashida M, Adachi M, Sato T, Wang T, Akasaka H, Mukumoto N, Shimizu Y, Sasaki R. Real-time in vivo dosimetry system based on an optical fiber-coupled microsized photostimulable phosphor for stereotactic body radiation therapy. Med Phys 2020; 47:5235-5249. [PMID: 32654194 DOI: 10.1002/mp.14383] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2020] [Revised: 06/21/2020] [Accepted: 06/30/2020] [Indexed: 12/11/2022] Open
Abstract
PURPOSE To develop an in vivo dosimeter system for stereotactic body radiation therapy (SBRT) that can perform accurate and precise real-time measurements, using a microsized amount of a photostimulable phosphor (PSP), BaFBr:Eu2+ . METHODS The sensitive volume of the PSP was 1.26 × 10-5 cm3 . The dosimeter system was designed to apply photostimulation to the PSP after the decay of noise signals, in synchronization with the photon beam pulse of a linear accelerator (LINAC), to eliminate the noise signals completely using a time separation technique. The noise signals included stem signals, and radioluminescence signals generated by the PSP. In addition, the dosimeter system was built on a storage-type dosimeter that could read out a signal after an arbitrary preset number of photon beam pulses were incident. First, the noise and photostimulated luminescence (PSL) signal decay times were measured. Subsequently, we confirmed that the PSL signals could be exclusively read out within the photon beam pulse interval. Finally, using a water phantom, the basic characteristics of the dosimeter system were demonstrated under SBRT conditions, and the feasibility for clinical application was investigated. The reproducibility, dose linearity, dose-rate dependence, temperature dependence, and angular dependence were evaluated. The feasibility was confirmed by measurements at various dose gradients and using a representative treatment plan for a metastatic liver tumor. A clinical plan was created with a two-arc beam volumetric modulated arc therapy using a 10 MV flattening filter-free photon beam. For the water phantom measurements, the clinical plan was compiled into a plan with a fixed gantry angle of 0°. To evaluate the energy dependence during SBRT, the percent depth dose (PDD) was measured and compared with those calculated via Monte Carlo (MC) simulations. RESULTS All the PSL signals could be read out while eliminating the noise signals within the minimum pulse interval of the LINAC. Stable real-time measurements could be performed with a time resolution of 56 ms (i.e., number of pulses = 20). The dose linearity was good in the dose range of 0.01-100 Gy. The measurements agreed within 1% at dose rates of 40-2400 cGy/min. The temperature and angular dependence were also acceptable since these dependencies had only a negligible effect on the measurements in SBRT. At a dose gradient of 2.21 Gy/mm, the measured dose agreed with that calculated using a treatment planning system (TPS) within the measurement uncertainties due to the probe position. For measurements using a representative treatment plan, the measured dose agreed with that calculated using the TPS within 0.5% at the center of the beam axis. The PDD measurements agreed with the MC calculations to within 1% for field sizes <5 × 5 cm2 . CONCLUSION The in vivo dosimeter system developed using BaFBr:Eu2+ is capable of real-time, accurate, and precise measurement under SBRT conditions. The probe is smaller than a conventional dosimeter, has excellent spatial resolution, and can be valuable in SBRT with a steep dose distribution over a small field. The developed PSP dosimeter system appears to be suitable for in vivo SBRT dosimetry.
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Affiliation(s)
- Ryuichi Yada
- Division of Radiation Oncology, Kobe University Graduate School of Medicine, 7-5-2 Kusunokicho, Chuouku, Kobe, Hyogo, 650-0017, Japan
| | - Kazusuke Maenaka
- Department of Electrical Engineering and Computer Science, Graduate School of Engineering, University of Hyogo, 2167 Shosha, Himeji, Hyogo, 671-2280, Japan
| | - Shuji Miyamoto
- Laboratory of Advanced Science and Technology for Industry, University of Hyogo, 3-1-2 Kouto, Kamigoricho, Akogun, Hyogo, 678-1205, Japan
| | - Go Okada
- Co-creative Research Center of Industrial Science and Technology, Kanazawa Institute of Technology, 3-1 Yatsukaho, Hakusan, Ishikawa, 924-0838, Japan
| | - Aki Sasakura
- Meisyo Kiko Co., Ltd, 148 Numa, Hikamicho, Tamba, Hyogo, 669-3634, Japan
| | - Motoi Ashida
- Meisyo Kiko Co., Ltd, 148 Numa, Hikamicho, Tamba, Hyogo, 669-3634, Japan
| | - Masashi Adachi
- Meisyo Kiko Co., Ltd, 148 Numa, Hikamicho, Tamba, Hyogo, 669-3634, Japan
| | - Tatsuhiko Sato
- Nuclear Science and Engineering Center, Japan Atomic Energy Agency, 2-4 Shirakata, Tokai, Ibaraki, 319-1195, Japan
| | - Tianyuan Wang
- Division of Radiation Oncology, Kobe University Graduate School of Medicine, 7-5-2 Kusunokicho, Chuouku, Kobe, Hyogo, 650-0017, Japan
| | - Hiroaki Akasaka
- Division of Radiation Oncology, Kobe University Graduate School of Medicine, 7-5-2 Kusunokicho, Chuouku, Kobe, Hyogo, 650-0017, Japan
| | - Naritoshi Mukumoto
- Division of Radiation Oncology, Kobe University Graduate School of Medicine, 7-5-2 Kusunokicho, Chuouku, Kobe, Hyogo, 650-0017, Japan
| | - Yasuyuki Shimizu
- Division of Radiation Oncology, Kobe University Graduate School of Medicine, 7-5-2 Kusunokicho, Chuouku, Kobe, Hyogo, 650-0017, Japan
| | - Ryohei Sasaki
- Division of Radiation Oncology, Kobe University Graduate School of Medicine, 7-5-2 Kusunokicho, Chuouku, Kobe, Hyogo, 650-0017, Japan
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11
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Linares Rosales HM, Archambault L, Beddar S, Beaulieu L. Dosimetric performance of a multipoint plastic scintillator dosimeter as a tool for real‐time source tracking in high dose rate Ir brachytherapy. Med Phys 2020; 47:4477-4490. [DOI: 10.1002/mp.14246] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Revised: 04/03/2020] [Accepted: 05/11/2020] [Indexed: 11/08/2022] Open
Affiliation(s)
- Haydee M. Linares Rosales
- Département de physique de génie physique et d’optique et Centre de recherche sur le cancer Université Laval Québec Canada
- Département de radio‐oncologie et Axe Oncologie du CRCHU de Québec CHU de Québec ‐ Université Laval Québec QC Canada
| | - Louis Archambault
- Département de physique de génie physique et d’optique et Centre de recherche sur le cancer Université Laval Québec Canada
- Département de radio‐oncologie et Axe Oncologie du CRCHU de Québec CHU de Québec ‐ Université Laval Québec QC Canada
| | - Sam Beddar
- Department of Radiation Physics The University of Texas MD Anderson Cancer Center Houston TX USA
- The University of Texas MD Anderson UTHealth Graduate School of Biomedical Sciences Houston TX USA
| | - Luc Beaulieu
- Département de physique de génie physique et d’optique et Centre de recherche sur le cancer Université Laval Québec Canada
- Département de radio‐oncologie et Axe Oncologie du CRCHU de Québec CHU de Québec ‐ Université Laval Québec QC Canada
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12
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Simiele E, Kapsch RP, Ankerhold U, Culberson W, DeWerd L. Technical note: characterization of spectral changes with measurement geometry and magnetic field strength in light guides used for scintillation dosimetry. ACTA ACUST UNITED AC 2020; 65:11NT01. [DOI: 10.1088/1361-6560/ab8afa] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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13
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Bradley D, Zubair H, Oresegun A, Louay G, Zin HM, Ung N, Abdul-Rashid H. Time-resolved dose measurements of linear accelerator pulses using a fibre optic sensor: Applications and challenges. Radiat Phys Chem Oxf Engl 1993 2020. [DOI: 10.1016/j.radphyschem.2019.03.016] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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14
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Alharbi M, Martyn M, O'Keeffe S, Therriault-Proulx F, Beaulieu L, Foley M. Benchmarking a novel inorganic scintillation detector for applications in radiation therapy. Phys Med 2019; 68:124-131. [DOI: 10.1016/j.ejmp.2019.11.018] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/01/2019] [Revised: 10/29/2019] [Accepted: 11/18/2019] [Indexed: 11/29/2022] Open
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15
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Suarez MA, Lim T, Robillot L, Maillot V, Lihoreau T, Bontemps P, Pazart L, Grosjean T. Miniaturized fiber dosimeter of medical ionizing radiations on a narrow optical fiber. OPTICS EXPRESS 2019; 27:35588-35599. [PMID: 31878728 DOI: 10.1364/oe.27.035588] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2019] [Accepted: 11/08/2019] [Indexed: 06/10/2023]
Abstract
Fiber dosimeters have recently drawn much interest for measuring in vivo and in real time the dose of medical radiations. This paper presents the first miniaturized fiber dosimeter integrated at the end of a narrow 125 μm outer diameter optical fiber. Miniaturization is rendered possible by exploiting the concept of a leaky wave optical antenna for interfacing the scintillators and the fiber and by taking advantage of the low propagation loss of narrow silica fibers and high detection yield of single-pixel photon counters. Upon irradiation at 6 MV in air, our fiber probe leads to a linear detection response with a signal-to-noise ratio as high as 195. Although implemented with inorganic scintillators and fiber, our miniaturized fiber probe induces minimum screening effects on ionizing radiations over a negligible area (0.153 mm2). Our nano-optically driven approach may thus result in ultra-compact fiber dosimeters of negligible footprint in the radiotherapeutic processes, even with non-water equivalent fibers and scintillators. This opens new opportunities for a large panel of therapies relying on ionizing radiations (photons or charged particles).
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Santos AMC, Gowda R, Bezak E, Afshar V S. Evaluation of a real-time optically stimulated luminescence beryllium oxide (BeO) fibre-coupled dosimetry system with a superficial 140 kVp X-ray beam. Phys Med 2019; 65:167-171. [PMID: 31494370 DOI: 10.1016/j.ejmp.2019.08.021] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/19/2019] [Revised: 06/18/2019] [Accepted: 08/29/2019] [Indexed: 11/16/2022] Open
Abstract
The purpose of this study was to investigate the potential of real-time optically stimulated luminescence (rtOSL) measurements of a beryllium oxide (BeO) ceramic fibre-coupled luminescence dosimetry system. By pulsing the stimulation laser during the exposure to ionizing radiation, an rtOSL dose-rate measurement can be obtained which could be stem effect free. A portable rtOSL BeO ceramic fibre-coupled dosimetry system is presented and characterized using a constant dose-rate superficial 140 kVp X-ray beam. The rtOSL was measured for dose-rates between 0.29 and 3.88 Gy/min, controlled by varying the source to surface distance. After correcting for OSL decay during the exposure, a linear dose-rate response of the change in rtOSL (ΔrtOSL) was observed. The ΔrtOSL was also observed to be stem effect free.
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Affiliation(s)
- Alexandre M Caraça Santos
- Department of Radiation Oncology, Royal Adelaide Hospital, Adelaide, South Australia 5000, Australia; School of Physical Sciences and Institute for Photonics and Advanced Sensing, University of Adelaide, Adelaide, South Australia 5005, Australia.
| | - Raghu Gowda
- Department of Radiation Oncology, Royal Adelaide Hospital, Adelaide, South Australia 5000, Australia
| | - Eva Bezak
- School of Physical Sciences and Institute for Photonics and Advanced Sensing, University of Adelaide, Adelaide, South Australia 5005, Australia; Cancer Research Institute and the School of Health Sciences, University of South Australia, Adelaide, South Australia 5001, Australia
| | - Shahraam Afshar V
- School of Physical Sciences and Institute for Photonics and Advanced Sensing, University of Adelaide, Adelaide, South Australia 5005, Australia; Division of Information Technology, Engineering and Environment, School of Engineering, The University of South Australia, Adelaide, South Australia 5000, Australia
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17
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Linares Rosales HM, Duguay-Drouin P, Archambault L, Beddar S, Beaulieu L. Optimization of a multipoint plastic scintillator dosimeter for high dose rate brachytherapy. Med Phys 2019; 46:2412-2421. [PMID: 30891803 DOI: 10.1002/mp.13498] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2018] [Revised: 01/16/2019] [Accepted: 02/18/2019] [Indexed: 11/08/2022] Open
Abstract
PURPOSE This study is devoted to optimizing and characterizing the response of a multipoint plastic scintillator detector (mPSD) for application to in vivo dosimetry in high dose rate (HDR) brachytherapy. METHODS An exhaustive analysis was carried out in order to obtain an optimized mPSD design that maximizes the scintillation light collection produced by the interaction of ionizing photons. More than 20 prototypes of mPSD were built and tested in order to determine the appropriate order of scintillators relative to the photodetector (distal, center, or proximal) as well as their length as a function of the scintillation light emitted. The available detecting elements are the BCF-60, BCF-12, and BCF-10 scintillators (Saint Gobain Crystals, Hiram, OH, USA), separated from each other by segments of Eska GH-4001 clear optical fibers (Mitsubishi Rayon Co., Ltd., Tokyo, Japan). The contribution of each scintillator to the total spectrum was determined by irradiations in the low energy range (<120 keV). For the best mPSD design, a numerical optimization was done in order to select the optical components [dichroic mirrors, filters, and photomultipliers tubes (PMTs)] that best match the light emission profile. Calculations were performed taking into account the measured scintillation spectrum and light yield, the manufacturer-reported transmission and attenuation of the optical components, and the experimentally characterized PMT noise. The optimized dosimetric system was used for HDR brachytherapy measurements. The system was independently controlled from the 192 Ir source via LabVIEW and read simultaneously using an NI-DAQ board. Dose measurements as a function of distance from the source were carried out according to TG-43U1 recommendations. The system performance was quantified in terms of signal to noise ratio (SNR) and signal to background ratio (SBR). RESULTS For best overall light-yield emission, it was determined that BCF-60 should be placed at the distal position, BCF-12 in the center, and BCF-10 at the proximal position with respect to the photodetector. This configuration allowed for optimized light transmission through the collecting fiber and avoided inter-scintillator excitation and self-absorption effects. The optimal scintillator length found was of 3, 6, and 7 mm for BCF-10, BCF- 12, and BCF-60, respectively. The optimized luminescence system allowed for signal deconvolution using a multispectral approach, extracting the dose to each element while taking into account the Cerenkov stem effect. Differences between the mPSD measurements and TG-43U1 remain below 5% in the range of 0.5 to 6.5 cm from the source. The dosimetric system can properly differentiate the scintillation signal from the background for a wide range of dose rate conditions; the SNR was found to be above 5 for dose rates above 22 mGy/s while the minimum SBR measured was 1.8 at 6 mGy/s. CONCLUSION Based on the spectral response at different conditions, an mPSD was constructed and optimized for HDR brachytherapy dosimetry. It is sensitive enough to allow multiple simultaneous measurements over a clinically useful distance range, up to 6.5 cm from the source. This study constitutes a baseline for future applications enabling real-time dose measurements and source position reporting over a wide range of dose rate conditions.
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Affiliation(s)
- Haydee M Linares Rosales
- Département de physique, de génie physique et d'optique et Centre de recherche sur le cancer, Université Laval, Québec City, QC, Canada.,Département de radio-oncologie et Axe Oncologie du CRCHU de Québec, CHU de Québec - Université Laval, Québec City, QC, Canada
| | - Patricia Duguay-Drouin
- Département de physique, de génie physique et d'optique et Centre de recherche sur le cancer, Université Laval, Québec City, QC, Canada.,Département de radio-oncologie et Axe Oncologie du CRCHU de Québec, CHU de Québec - Université Laval, Québec City, QC, Canada
| | - Louis Archambault
- Département de physique, de génie physique et d'optique et Centre de recherche sur le cancer, Université Laval, Québec City, QC, Canada.,Département de radio-oncologie et Axe Oncologie du CRCHU de Québec, CHU de Québec - Université Laval, Québec City, QC, Canada
| | - Sam Beddar
- Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, TX, 77003, USA
| | - Luc Beaulieu
- Département de physique, de génie physique et d'optique et Centre de recherche sur le cancer, Université Laval, Québec City, QC, Canada.,Département de radio-oncologie et Axe Oncologie du CRCHU de Québec, CHU de Québec - Université Laval, Québec City, QC, Canada
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Archer J, Madden L, Li E, Wilkinson D, Rosenfeld AB. An algorithmic approach to single-probe Cherenkov removal in pulsed x-ray beams. Med Phys 2019; 46:1833-1839. [PMID: 30629742 DOI: 10.1002/mp.13383] [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: 06/12/2018] [Revised: 11/21/2018] [Accepted: 01/05/2019] [Indexed: 11/06/2022] Open
Abstract
PURPOSE The removal of Cherenkov light in an optical dosimetry system is an important process to ensure accurate dosimetry without compromising spatial resolution. Many solutions have been presented in the literature, each with advantages and disadvantages. We present a methodology to remove Cherenkov light from a scintillator fiber optic dosimeter in a pulsed megavoltage x-ray beam using the temporal waveform across the pulse. METHODS A sample waveform of Cherenkov light can be measured by exposing only the fiber to the beam. By assuming that the Cherenkov waveform closely matches the intensity of incident radiation, this waveform can be convoluted with the instantaneous scintillation response function to generate an expected scintillation signal. By finding the least-squares fit between these two functions and the experimental data, the estimated Cherenkov contribution can be subtracted off the net signal. This can be applied for arbitrarily complex Cherenkov waveforms (within the 2 ns timing resolution of the data acquisition), and in fact, the results suggest more fluctuations in the waveforms provide a better fit to data. RESULTS Four beam profiles for different field sizes and energies were found with this method. They closely matched references data measured with ionization chamber with average differences across the beam no more than 4%. Noisy waveforms are assumed to be the primary cause of differences between the analyzed scintillator and IC results. We propose methods for improving the results and optimizing the data acquisition and analysis processes. CONCLUSIONS These results demonstrate that it is possible and effective with a single probe to use function fitting of expected data to experimental to remove a complicated Cherenkov signal from the net light signal in pulsed-beam optical dosimetry.
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Affiliation(s)
- James Archer
- Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW, 2522, Australia
| | - Levi Madden
- Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW, 2522, Australia
| | - Enbang Li
- Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW, 2522, Australia
| | - Dean Wilkinson
- Illawarra Cancer Care Centre, Wollongong Hospital, Wollongong, NSW, 2500, Australia
| | - Anatoly B Rosenfeld
- Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW, 2522, Australia.,Illawarra Health and Medical Research Institute, University of Wollongong, Wollongong, NSW, 2522, Australia
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Monajemi TT, Ruiz EA. Application of plastic scintillating fibres to surface dosimetry in megavoltage photon and electron beams: considerations for Cerenkov correction. ACTA ACUST UNITED AC 2018; 63:185003. [DOI: 10.1088/1361-6560/aad9b6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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20
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Archer J, Madden L, Li E, Carolan M, Rosenfeld A. A comparison of temporal Cherenkov separation techniques in pulsed signal scintillator dosimetry. Biomed Phys Eng Express 2018; 4. [DOI: 10.1088/2057-1976/aacf56] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2018] [Accepted: 06/27/2018] [Indexed: 11/12/2022]
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21
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Zhang X, Tang X, Shu D, Gong C, Geng C, Ai Y, Yu H, Shao W. Theoretical calculation and measurement accuracy of Cerenkov optic-fiber dosimeter under electron and photon radiation therapies. RADIAT MEAS 2018. [DOI: 10.1016/j.radmeas.2018.01.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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22
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Teichmann T, Sponner J, Radtke J, Henniger J. Gated discrimination of the stem signal in pulsed radiation fields for a fiber optic dosimetry system based on the radioluminescence of beryllium oxide. RADIAT MEAS 2017. [DOI: 10.1016/j.radmeas.2017.03.046] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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23
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Martínez N, Rucci A, Marcazzó J, Molina P, Santiago M, Cravero W. Characterization of YVO4:Eu3+ scintillator as detector for Fiber Optic Dosimetry. RADIAT MEAS 2017. [DOI: 10.1016/j.radmeas.2017.03.015] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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24
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Temporally separating Cherenkov radiation in a scintillator probe exposed to a pulsed X-ray beam. Phys Med 2017; 42:185-188. [DOI: 10.1016/j.ejmp.2017.09.134] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/14/2017] [Revised: 09/06/2017] [Accepted: 09/23/2017] [Indexed: 11/19/2022] Open
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25
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Jennings MW, Rutten TP, Ottaway DJ. Evaluation of the signal quality of an inexpensive CMOS camera towards imaging a high-resolution plastic scintillation detector array. RADIAT MEAS 2017. [DOI: 10.1016/j.radmeas.2017.07.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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26
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Veronese I, Chiodini N, Cialdi S, d’Ippolito E, Fasoli M, Gallo S, La Torre S, Mones E, Vedda A, Loi G. Real-time dosimetry with Yb-doped silica optical fibres. Phys Med Biol 2017; 62:4218-4236. [DOI: 10.1088/1361-6560/aa642f] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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27
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Papaconstadopoulos P, Archambault L, Seuntjens J. Experimental investigation on the accuracy of plastic scintillators and of the spectrum discrimination method in small photon fields. Med Phys 2017; 44:654-664. [DOI: 10.1002/mp.12064] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2016] [Revised: 09/23/2016] [Accepted: 12/05/2016] [Indexed: 11/05/2022] Open
Affiliation(s)
- Pavlos Papaconstadopoulos
- McGill University; Medical Physics Unit, Department of Radiation Oncology, SMBD Jewish General Hospital; 3755 Côte-Ste-Catherine Road Montréal, Québec H3T 1E2 Canada
| | - Louis Archambault
- Département de Physique, de Génie Physique et d’ Optique; Université Laval; Quèbec G1K 7P4 Canada
- Département de Radio-Oncologie; Hotel-Dieu de Québec, Centre Hospitalier Universitaire de Quèbec; Quèbec G1R 2J6 Canada
| | - Jan Seuntjens
- McGill University; Medical Physics Unit, Cedars Cancer Centre; 1001 Décarie Montréal, Québec H4A 3J1 Canada
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Qin Z, Hu Y, Ma Y, Lin W, Luo X, Zhao W, Sun W, Zhang D, Chen Z, Wang B, Lewis E. Water-equivalent fiber radiation dosimeter with two scintillating materials. BIOMEDICAL OPTICS EXPRESS 2016; 7:4919-4927. [PMID: 28018715 PMCID: PMC5175541 DOI: 10.1364/boe.7.004919] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2016] [Revised: 10/15/2016] [Accepted: 10/25/2016] [Indexed: 06/06/2023]
Abstract
An inorganic scintillating material plastic optical fiber (POF) dosimeter for measuring ionizing radiation during radiotherapy applications is reported. It is necessary that an ideal dosimeter exhibits many desirable qualities, including water equivalence, energy independence, reproducibility, dose linearity. There has been much recent research concerning inorganic dosimeters. However, little reference has been made to date of the depth-dose characteristics of dosimeter materials. In the case of inorganic scintillating materials, they are predominantly non water-equivalent, with their effective atomic weight (Zeff) being typically much greater than that of water. This has been a barrier in preventing inorganic scintillating material dosimeter from being used in actual clinical applications. In this paper, we propose a parallel-paired fiber light guide structure to solve this problem. Two different inorganic scintillating materials are embedded separately in the parallel-paired fiber. It is shown that the information of water depth and absorbed dose at the point of measurement can be extracted by utilizing their different depth-dose properties.
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Affiliation(s)
- Zhuang Qin
- Key Lab of In-fiber Integrated Optics, Ministry Education of China, Harbin Engineering University, Harbin 150001, China
| | - Yaosheng Hu
- Key Lab of In-fiber Integrated Optics, Ministry Education of China, Harbin Engineering University, Harbin 150001, China
| | - Yu Ma
- Key Lab of In-fiber Integrated Optics, Ministry Education of China, Harbin Engineering University, Harbin 150001, China
| | - Wei Lin
- Key Lab of In-fiber Integrated Optics, Ministry Education of China, Harbin Engineering University, Harbin 150001, China
| | - Xianping Luo
- Key Lab of In-fiber Integrated Optics, Ministry Education of China, Harbin Engineering University, Harbin 150001, China
| | - Wenhui Zhao
- Key Lab of In-fiber Integrated Optics, Ministry Education of China, Harbin Engineering University, Harbin 150001, China
| | - Weimin Sun
- Key Lab of In-fiber Integrated Optics, Ministry Education of China, Harbin Engineering University, Harbin 150001, China
| | - Daxin Zhang
- Comprehensive Cancer Center, First Affiliated Hospital of Harbin Medical University, Harbin 150001, China
| | - Ziyin Chen
- Comprehensive Cancer Center, First Affiliated Hospital of Harbin Medical University, Harbin 150001, China
| | - Boran Wang
- Harbin YIAOMI Technology Development Co., Ltd, Harbin 150001, China
| | - Elfed Lewis
- Optical Fibre Sensors Research Centre, University of Limerick, Castletroy, Limerick, Ireland
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29
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Beaulieu L, Beddar S. Review of plastic and liquid scintillation dosimetry for photon, electron, and proton therapy. Phys Med Biol 2016; 61:R305-R343. [DOI: 10.1088/0031-9155/61/20/r305] [Citation(s) in RCA: 97] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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30
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Zhuang Q, Yaosheng H, Yu M, Wenhui Z, Weimin S, Daxin Z, Ziyin C, Elfed L. Embedded structure fiber-optic radiation dosimeter for radiotherapy applications. OPTICS EXPRESS 2016; 24:5172-5185. [PMID: 29092344 DOI: 10.1364/oe.24.005172] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
An investigation into a novel in-vivo PMMA (polymethyl methacrylate) plastic fiber-optic dosimeter for monitoring low doses of ionizing radiotherapy radiation in real time and for integrating measurements is presented. The fabricated optical fiber tip possessed an embedded structure. A scintillation material, terbium-doped gadolinium oxysulfide (Gd2O2S:Tb), capable of emitting visible light at around 545 nm which is ideal for transmission through the PMMA when exposed to ionizing radiation was embedded in the PMMA plastic fiber. The dose rate of incident ionizing radiation is measured by analyzing the signal intensity emitted from the scintillation material which propagates through the fiber to a distal MPPC (multi-pixel photon counter). The dosimeter exhibits good repeatability with an excellent linear relationship between the fiber-optic dosimeter output and the absorbed radiation dose with an outstanding isotropic response in its radial angular dependence.
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31
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Scintillation properties of the YVO4:Eu3+ compound in powder form: its application to dosimetry in radiation fields produced by pulsed mega-voltage photon beams. Z Med Phys 2015; 25:368-374. [DOI: 10.1016/j.zemedi.2015.04.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2014] [Revised: 04/01/2015] [Accepted: 04/04/2015] [Indexed: 11/23/2022]
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32
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Darafsheh A, Zhang R, Kanick SC, Pogue BW, Finlay JC. Spectroscopic separation of Čerenkov radiation in high-resolution radiation fiber dosimeters. JOURNAL OF BIOMEDICAL OPTICS 2015; 20:095001. [PMID: 26334972 DOI: 10.1117/1.jbo.20.9.095001] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2015] [Accepted: 07/31/2015] [Indexed: 06/05/2023]
Abstract
We have investigated Čerenkov radiation generated in phosphor-based optical fiber dosimeters irradiated with clinical electron beams. We fabricated two high-spatial resolution fiber-optic probes, with 200 and 400 μm core diameters, composed of terbium-based phosphor tips. A generalizable spectroscopic method was used to separate Čerenkov radiation from the transmitted signal by the fiber based on the assumption that the recorded signal is a linear superposition of two basis spectra: characteristic luminescence of the phosphor medium and Čerenkov radiation. We performed Monte Carlo simulations of the Čerenkov radiation generated in the fiber and found a strong dependence of the recorded Čerenkov radiation on the numerical aperture of the fiber at shallow phantom depths; however, beyond the depth of maximum dose that dependency is minimal. The simulation results agree with the experimental results for Čerenkov radiation generated in fibers. The spectroscopic technique used in this work can be used for development of high-spatial resolution fiber micro dosimeters and for optical characterization of various scintillating materials, such as phosphor nanoparticles, in ionizing radiation fields of high energy.
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Affiliation(s)
- Arash Darafsheh
- University of Pennsylvania, Department of Radiation Oncology, 3400 Civic Center Boulevard, Philadelphia, Pennsylvania 19104, United States
| | - Rongxiao Zhang
- Dartmouth College, Department of Physics and Astronomy, Hanover, New Hampshire 03755, United States
| | - Stephen Chad Kanick
- Dartmouth College, Thayer School of Engineering, Hanover, New Hampshire 03755, United States
| | - Brian W Pogue
- Dartmouth College, Department of Physics and Astronomy, Hanover, New Hampshire 03755, United StatescDartmouth College, Thayer School of Engineering, Hanover, New Hampshire 03755, United States
| | - Jarod C Finlay
- University of Pennsylvania, Department of Radiation Oncology, 3400 Civic Center Boulevard, Philadelphia, Pennsylvania 19104, United States
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O'Keeffe S, McCarthy D, Woulfe P, Grattan MWD, Hounsell AR, Sporea D, Mihai L, Vata I, Leen G, Lewis E. A review of recent advances in optical fibre sensors for in vivo dosimetry during radiotherapy. Br J Radiol 2015; 88:20140702. [PMID: 25761212 PMCID: PMC4628446 DOI: 10.1259/bjr.20140702] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2014] [Revised: 02/19/2015] [Accepted: 03/10/2015] [Indexed: 11/05/2022] Open
Abstract
This article presents an overview of the recent developments and requirements in radiotherapy dosimetry, with particular emphasis on the development of optical fibre dosemeters for radiotherapy applications, focusing particularly on in vivo applications. Optical fibres offer considerable advantages over conventional techniques for radiotherapy dosimetry, owing to their small size, immunity to electromagnetic interferences, and suitability for remote monitoring and multiplexing. The small dimensions of optical fibre-based dosemeters, together with being lightweight and flexible, mean that they are minimally invasive and thus particularly suited to in vivo dosimetry. This means that the sensor can be placed directly inside a patient, for example, for brachytherapy treatments, the optical fibres could be placed in the tumour itself or into nearby critical tissues requiring monitoring, via the same applicators or needles used for the treatment delivery thereby providing real-time dosimetric information. The article outlines the principal sensor design systems along with some of the main strengths and weaknesses associated with the development of these techniques. The successful demonstration of these sensors in a range of different clinical environments is also presented.
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Affiliation(s)
- S O'Keeffe
- Optical Fibre Sensors Research Centre, Department of Electronic and Computer Engineering, University of Limerick, Limerick, Ireland
| | - D McCarthy
- Optical Fibre Sensors Research Centre, Department of Electronic and Computer Engineering, University of Limerick, Limerick, Ireland
| | - P Woulfe
- Department of Radiotherapy Physics, Galway Clinic, Galway, Ireland
| | - M W D Grattan
- Radiotherapy Physics, Northern Ireland Cancer Centre, Belfast Health and Social Care Trust, Belfast, UK
| | - A R Hounsell
- Radiotherapy Physics, Northern Ireland Cancer Centre, Belfast Health and Social Care Trust, Belfast, UK
| | - D Sporea
- Laser Metrology Laboratory, National Institute for Laser, Plasma and Radiation Physics, Magurele, Romania
| | - L Mihai
- Laser Metrology Laboratory, National Institute for Laser, Plasma and Radiation Physics, Magurele, Romania
| | - I Vata
- “Horia Hulubei” National Institute of Physics and Nuclear Engineering, Magurele, Romania
| | - G Leen
- Optical Fibre Sensors Research Centre, Department of Electronic and Computer Engineering, University of Limerick, Limerick, Ireland
| | - E Lewis
- Optical Fibre Sensors Research Centre, Department of Electronic and Computer Engineering, University of Limerick, Limerick, Ireland
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Ishikawa M, Nagase N, Matsuura T, Hiratsuka J, Suzuki R, Miyamoto N, Sutherland KL, Fujita K, Shirato H. Development of a wavelength-separated type scintillator with optical fiber (SOF) dosimeter to compensate for the Cerenkov radiation effect. JOURNAL OF RADIATION RESEARCH 2015; 56:372-381. [PMID: 25618136 PMCID: PMC4380053 DOI: 10.1093/jrr/rru106] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2014] [Revised: 09/02/2014] [Accepted: 10/07/2014] [Indexed: 06/01/2023]
Abstract
The scintillator with optical fiber (SOF) dosimeter consists of a miniature scintillator mounted on the tip of an optical fiber. The scintillator of the current SOF dosimeter is a 1-mm diameter hemisphere. For a scintillation dosimeter coupled with an optical fiber, measurement accuracy is influenced by signals due to Cerenkov radiation in the optical fiber. We have implemented a spectral filtering technique for compensating for the Cerenkov radiation effect specifically for our plastic scintillator-based dosimeter, using a wavelength-separated counting method. A dichroic mirror was used for separating input light signals. Individual signal counting was performed for high- and low-wavelength light signals. To confirm the accuracy, measurements with various amounts of Cerenkov radiation were performed by changing the incident direction while keeping the Ir-192 source-to-dosimeter distance constant, resulting in a fluctuation of <5%. Optical fiber bending was also addressed; no bending effect was observed for our wavelength-separated SOF dosimeter.
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Affiliation(s)
- Masayori Ishikawa
- Department of Medical Physics and Engineering, Graduate School of Medicine, Hokkaido University, N-15 W-7 Kita-ku, Sapporo Hokkaido, 060-8638, Japan
| | - Naomi Nagase
- Department of Radiology, Kawasaki Medical School Hospital, 577 Matsushima, Kurashiki Okayama, 701-0192, Japan
| | - Taeko Matsuura
- Department of Medical Physics, Hokkaido University Hospital, N-14 W-5 Kita-ku, Sapporo Hokkaido, 060-8648, Japan
| | - Junichi Hiratsuka
- Department of Radiology, Kawasaki Medical School Hospital, 577 Matsushima, Kurashiki Okayama, 701-0192, Japan
| | - Ryusuke Suzuki
- Department of Medical Physics, Hokkaido University Hospital, N-14 W-5 Kita-ku, Sapporo Hokkaido, 060-8648, Japan
| | - Naoki Miyamoto
- Department of Medical Physics and Engineering, Graduate School of Medicine, Hokkaido University, N-15 W-7 Kita-ku, Sapporo Hokkaido, 060-8638, Japan
| | - Kenneth Lee Sutherland
- Department of Medical Physics and Engineering, Graduate School of Medicine, Hokkaido University, N-15 W-7 Kita-ku, Sapporo Hokkaido, 060-8638, Japan
| | - Katsuhisa Fujita
- Department of Radiology, Hokkaido University Hospital, N-14 W-5 Kita-ku, Sapporo Hokkaido, 060-8648, Japan
| | - Hiroki Shirato
- Department of Radiology, Graduate School of Medicine, Hokkaido University, N-15 W-7 Kita-ku, Sapporo Hokkaido, 060-8638, Japan
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Gagnon LP, Beddar S, Beaulieu L. Characterization of a fiber-taper charge-coupled device system for plastic scintillation dosimetry and comparison with the traditional lens system. RADIAT MEAS 2015. [DOI: 10.1016/j.radmeas.2015.01.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Glaser AK, Andreozzi JM, Davis SC, Zhang R, Pogue BW, Fox CJ, Gladstone DJ. Video-rate optical dosimetry and dynamic visualization of IMRT and VMAT treatment plans in water using Cherenkov radiation. Med Phys 2015; 41:062102. [PMID: 24877829 DOI: 10.1118/1.4875704] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE A novel technique for optical dosimetry of dynamic intensity-modulated radiation therapy (IMRT) and volumetric-modulated arc therapy (VMAT) plans was investigated for the first time by capturing images of the induced Cherenkov radiation in water. METHODS A high-sensitivity, intensified CCD camera (ICCD) was configured to acquire a two-dimensional (2D) projection image of the Cherenkov radiation induced by IMRT and VMAT plans, based on the Task Group 119 (TG-119) C-Shape geometry. Plans were generated using the Varian Eclipse treatment planning system (TPS) and delivered using 6 MV x-rays from a Varian TrueBeam Linear Accelerator (Linac) incident on a water tank doped with the fluorophore quinine sulfate. The ICCD acquisition was gated to the Linac target trigger pulse to reduce background light artifacts, read out for a single radiation pulse, and binned to a resolution of 512 × 512 pixels. The resulting videos were analyzed temporally for various regions of interest (ROI) covering the planning target volume (PTV) and organ at risk (OAR), and summed to obtain an overall light intensity distribution, which was compared to the expected dose distribution from the TPS using a gamma-index analysis. RESULTS The chosen camera settings resulted in 23.5 frames per second dosimetry videos. Temporal intensity plots of the PTV and OAR ROIs confirmed the preferential delivery of dose to the PTV versus the OAR, and the gamma analysis yielded 95.9% and 96.2% agreement between the experimentally captured Cherenkov light distribution and expected TPS dose distribution based upon a 3%/3 mm dose difference and distance-to-agreement criterion for the IMRT and VMAT plans, respectively. CONCLUSIONS The results from this initial study demonstrate the first documented use of Cherenkov radiation for video-rate optical dosimetry of dynamic IMRT and VMAT treatment plans. The proposed modality has several potential advantages over alternative methods including the real-time nature of the acquisition, and upon future refinement may prove to be a robust and novel dosimetry method with both research and clinical applications.
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Affiliation(s)
- Adam K Glaser
- Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire 03755
| | | | - Scott C Davis
- Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire 03755
| | - Rongxiao Zhang
- Department of Physics and Astronomy, Dartmouth College, Hanover, New Hampshire 03755
| | - Brian W Pogue
- Department of Physics and Astronomy and Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire 03755
| | - Colleen J Fox
- Norris Cotton Cancer Center, Dartmouth-Hitchcock Medical Center, Lebanon, New Hampshire 03766
| | - David J Gladstone
- Norris Cotton Cancer Center, Dartmouth-Hitchcock Medical Center, Lebanon, New Hampshire 03766
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Teymurazyan A, Rowlands JA, Pang G. Monte Carlo simulation of a quantum noise limited Čerenkov detector based on air-spaced light guiding taper for megavoltage x-ray imaging. Med Phys 2014; 41:041907. [PMID: 24694138 DOI: 10.1118/1.4867867] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE Electronic Portal Imaging Devices (EPIDs) have been widely used in radiation therapy and are still needed on linear accelerators (Linacs) equipped with kilovoltage cone beam CT (kV-CBCT) or MRI systems. Our aim is to develop a new high quantum efficiency (QE) Čerenkov Portal Imaging Device (CPID) that is quantum noise limited at dose levels corresponding to a single Linac pulse. METHODS Recently a new concept of CPID for MV x-ray imaging in radiation therapy was introduced. It relies on Čerenkov effect for x-ray detection. The proposed design consisted of a matrix of optical fibers aligned with the incident x-rays and coupled to an active matrix flat panel imager (AMFPI) for image readout. A weakness of such design is that too few Čerenkov light photons reach the AMFPI for each incident x-ray and an AMFPI with an avalanche gain is required in order to overcome the readout noise for portal imaging application. In this work the authors propose to replace the optical fibers in the CPID with light guides without a cladding layer that are suspended in air. The air between the light guides takes on the role of the cladding layer found in a regular optical fiber. Since air has a significantly lower refractive index (∼ 1 versus 1.38 in a typical cladding layer), a much superior light collection efficiency is achieved. RESULTS A Monte Carlo simulation of the new design has been conducted to investigate its feasibility. Detector quantities such as quantum efficiency (QE), spatial resolution (MTF), and frequency dependent detective quantum efficiency (DQE) have been evaluated. The detector signal and the quantum noise have been compared to the readout noise. CONCLUSIONS Our studies show that the modified new CPID has a QE and DQE more than an order of magnitude greater than that of current clinical systems and yet a spatial resolution similar to that of current low-QE flat-panel based EPIDs. Furthermore it was demonstrated that the new CPID does not require an avalanche gain in the AMFPI and is quantum noise limited at dose levels corresponding to a single Linac pulse.
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Affiliation(s)
- A Teymurazyan
- Imaging Research, Sunnybrook Health Sciences Centre, Department of Medical Biophysics, University of Toronto, Toronto M4N 3M5, Canada
| | - J A Rowlands
- Imaging Research, Sunnybrook Health Sciences Centre, Department of Medical Biophysics, University of Toronto, Toronto M4N 3M5, Canada; Thunder Bay Regional Research Institute (TBRRI), Thunder Bay P7A 7T1, Canada; and Department of Radiation Oncology, University of Toronto, Toronto M5S 3E2, Canada
| | - G Pang
- Imaging Research, Sunnybrook Health Sciences Centre, Department of Medical Biophysics, University of Toronto, Toronto M4N 3M5, Canada; Department of Radiation Oncology, University of Toronto, Toronto M5S 3E2, Canada; Odette Cancer Centre, Toronto M4N 3M5, Canada; and Department of Physics, Ryerson University, Toronto M5B 2K3, Canada
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Glaser AK, Zhang R, Gladstone DJ, Pogue BW. Optical dosimetry of radiotherapy beams using Cherenkov radiation: the relationship between light emission and dose. Phys Med Biol 2014; 59:3789-811. [PMID: 24938928 DOI: 10.1088/0031-9155/59/14/3789] [Citation(s) in RCA: 109] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Recent studies have proposed that light emitted by the Cherenkov effect may be used for a number of radiation therapy dosimetry applications. There is a correlation between the captured light and expected dose under certain conditions, yet discrepancies have also been observed and a complete examination of the theoretical differences has not been done. In this study, a fundamental comparison between the Cherenkov emission and absorbed dose was explored for x-ray photons, electrons, and protons using both a theoretical and Monte Carlo-based analysis. Based on the findings of where dose correlates with Cherenkov emission, it was concluded that for x-ray photons the light emission would be optimally suited for narrow beam stereotactic radiation therapy and surgery validation studies, for verification of dynamic intensity-modulated and volumetric modulated arc therapy treatment plans in water tanks, near monoenergetic sources (e.g., Co-60 and brachy therapy sources) and also for entrance and exit surface imaging dosimetry of both narrow and broad beams. For electron use, Cherenkov emission was found to be only suitable for surface dosimetry applications. Finally, for proton dosimetry, there exists a fundamental lack of Cherenkov emission at the Bragg peak, making the technique of little use, although post-irradiation detection of light emission from radioisotopes could prove to be useful.
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Affiliation(s)
- Adam K Glaser
- Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire 03755, USA
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Measurement of Cerenkov radiation induced by the gamma-rays of Co-60 therapy units using wavelength shifting fiber. SENSORS 2014; 14:7013-25. [PMID: 24755521 PMCID: PMC4029631 DOI: 10.3390/s140407013] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/31/2013] [Revised: 03/18/2014] [Accepted: 04/15/2014] [Indexed: 11/17/2022]
Abstract
In this study, a wavelength shifting fiber that shifts ultra-violet and blue light to green light was employed as a sensor probe of a fiber-optic Cerenkov radiation sensor. In order to characterize Cerenkov radiation generated in the developed wavelength shifting fiber and a plastic optical fiber, spectra and intensities of Cerenkov radiation were measured with a spectrometer. The spectral peaks of light outputs from the wavelength shifting fiber and the plastic optical fiber were measured at wavelengths of 500 and 510 nm, respectively, and the intensity of transmitted light output of the wavelength shifting fiber was 22.2 times higher than that of the plastic optical fiber. Also, electron fluxes and total energy depositions of gamma-ray beams generated from a Co-60 therapy unit were calculated according to water depths using the Monte Carlo N-particle transport code. The relationship between the fluxes of electrons over the Cerenkov threshold energy and the energy depositions of gamma-ray beams from the Co-60 unit is a near-identity function. Finally, percentage depth doses for the gamma-ray beams were obtained using the fiber-optic Cerenkov radiation sensor, and the results were compared with those obtained by an ionization chamber. The average dose difference between the results of the fiber-optic Cerenkov radiation sensor and those of the ionization chamber was about 2.09%.
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40
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Glaser AK, Davis SC, McClatchy DM, Zhang R, Pogue BW, Gladstone DJ. Projection imaging of photon beams by the Čerenkov effect. Med Phys 2013; 40:012101. [PMID: 23298103 DOI: 10.1118/1.4770286] [Citation(s) in RCA: 81] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
PURPOSE A novel technique for beam profiling of megavoltage photon beams was investigated for the first time by capturing images of the induced Čerenkov emission in water, as a potential surrogate for the imparted dose in irradiated media. METHODS A high-sensitivity, intensified CCD camera (ICCD) was configured to acquire 2D projection images of Čerenkov emission from a 4 × 4 cm(2) 6 MV linear accelerator (LINAC) x-ray photon beam operating at a dose rate of 400 MU∕min incident on a water tank with transparent walls. The ICCD acquisition was gated to the LINAC sync pulse to reduce background light artifacts, and the measurement quality was investigated by evaluating the signal to noise ratio and measurement repeatability as a function of delivered dose. Monte Carlo simulations were used to derive a calibration factor for differences between the optical images and deposited dose arising from the anisotropic angular dependence of Čerenkov emission. Finally, Čerenkov-based beam profiles were compared to a percent depth dose (PDD) and lateral dose profile at a depth of d(max) from a reference dose distribution generated from the clinical Varian ECLIPSE treatment planning system (TPS). RESULTS The signal to noise ratio was found to be 20 at a delivered dose of 66.6 cGy, and proportional to the square root of the delivered dose as expected from Poisson photon counting statistics. A 2.1% mean standard deviation and 5.6% maximum variation in successive measurements were observed, and the Monte Carlo derived calibration factor resulted in Čerenkov emission images which were directly correlated to deposited dose, with some spatial issues. The dose difference between the TPS and PDD predicted by Čerenkov measurements was within 20% in the buildup region with a distance to agreement (DTA) of 1.5-2 mm and ±3% at depths beyond d(max). In the lateral profile, the dose difference at the beam penumbra was within ±13% with a DTA of 0-2 mm, ±5% in the central beam region, and 2%-3% in the beam umbra. CONCLUSIONS The results from this initial study demonstrate the first documented use of Čerenkov emission imaging to profile x-ray photon LINAC beams in water. The proposed modality has several potential advantages over alternative methods, and upon future refinement may prove to be a robust and novel dosimetry method.
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Affiliation(s)
- Adam K Glaser
- Thayer School of Engineering, Dartmouth College, Hanover, NH, USA.
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41
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Molina P, Sommer M, Kattner F, Henniger J. Response characterization of an Y2O3:Eu-based radioluminescence probe under 60Co irradiation. RADIAT MEAS 2013. [DOI: 10.1016/j.radmeas.2013.01.031] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Blake SJ, McNamara AL, Deshpande S, Holloway L, Greer PB, Kuncic Z, Vial P. Characterization of a novel EPID designed for simultaneous imaging and dose verification in radiotherapy. Med Phys 2013; 40:091902. [DOI: 10.1118/1.4816657] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
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Liu PZY, Suchowerska N, McKenzie DR. Twisted pair of optic fibers for background removal in radiation fields. APPLIED OPTICS 2013; 52:5500-5507. [PMID: 23913071 DOI: 10.1364/ao.52.005500] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2013] [Accepted: 07/02/2013] [Indexed: 06/02/2023]
Abstract
In many situations in which an optic fiber carries a signal through a radiation field, an unwanted background signal is produced consisting of fluorescent and/or Cerenkov light. This presents a major problem in the measurement of the light signal, for example, in scintillation dosimetry of medical therapeutic beams. In this paper, we demonstrate a new method of measuring and removing the background signal through the use of a twisted pair of optic fibers. The twisted pair consists of a fiber carrying the scintillation signal that is twisted with a second optic fiber to form a double helix. The two twisted fibers will experience the same radiation environment provided the periodicity of the twist is correlated to the dose rate gradient. An expression for the required twist periodicity is presented. A scintillation dosimeter with a twisted pair optic fiber was tested in a megavoltage beam and found to accurately measure its beam characteristics. The twisted pair approach is not restricted to medical applications and can be used in many situations in which optical signals are carried through radiation fields.
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Affiliation(s)
- P Z Y Liu
- School of Physics, University of Sydney, New South Wales, Australia.
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Beaulieu L, Goulet M, Archambault L, Beddar S. Current status of scintillation dosimetry for megavoltage beams. ACTA ACUST UNITED AC 2013. [DOI: 10.1088/1742-6596/444/1/012013] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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46
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Santos AMC, Mohammadi M, Asp J, Monro TM, Afshar V. S. Characterisation of a real-time fibre-coupled beryllium oxide (BeO) luminescence dosimeter in X-ray beams. RADIAT MEAS 2013. [DOI: 10.1016/j.radmeas.2013.03.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Therriault-Proulx F, Beaulieu L, Archambault L, Beddar S. On the nature of the light produced within PMMA optical light guides in scintillation fiber-optic dosimetry. Phys Med Biol 2013; 58:2073-84. [PMID: 23470253 DOI: 10.1088/0031-9155/58/7/2073] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The goal of this study was to evaluate the nature of the stem effect light produced within an optical fiber, to quantify its composition, and to evaluate the efficiency of the chromatic technique to remove the stem effect. Spectrometry studies were performed during irradiations of a bare PMMA optical fiber with kilovoltage x-rays from a superficial therapy unit, an Ir-192 high-dose-rate brachytherapy source, a Co-60 external-therapy unit, and megavoltage electrons and x-rays from a linear accelerator. Stem effect spectra can be accurately modeled by a linear combination of the Cerenkov light and fluorescence emitted spectra. Fluorescence light contributes more for lower-energy modalities. Cerenkov light contributes more as the energy increases above the threshold for its production. The chromatic stem effect removal technique is accurate in most of the situations. However, noticeable differences were obtained between very specific high-energy irradiation conditions. It would be advantageous to implement an additional channel in the chromatic stem effect removal chain or implement a spectral approach to independently remove the Cerenkov and the fluorescence components from the signal of interest. This would increase the accuracy and versatility of the actual chromatic stem effect removal technique.
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Affiliation(s)
- François Therriault-Proulx
- Department of Radiation Physics, Unit 94, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, TX 77030, USA
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Lee JJ, Liu PZY, McKenzie DR, Suchowerska N. A method to remove residual signals in fibre optic luminescence dosimeters. Phys Med Biol 2013; 58:1581-90. [PMID: 23417084 DOI: 10.1088/0031-9155/58/5/1581] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Whenever a fibre optic is used to convey a light signal through a radiation field, it is likely that an unwanted background signal will arise from Cerenkov or fluorescent light which will contaminate the signal. In luminescence dosimetry of high energy beams, when a fibre optic is used to convey the signal from the radiation field to the detector, Cerenkov light is the dominant contributor to the background signal and must be corrected for. In this work, a novel method is demonstrated to separate the signal from the unwanted background. A remotely operated shutter is used to block the signal, allowing the residual background in the fibre optic to be quantified. This background is subtracted from the total measurement acquired in a subsequent irradiation, enabling the luminescence signal to be extracted. Two types of shutter mechanism are considered: an electro-mechanical device to intercept the light path and an LCD device to block the light by cross-polarization. Both shutters were characterized and incorporated into a fibre optic dosimetry system used to measure the radiation dose produced by external beam radiation linear accelerators. The dosimeter using each of the shutters in turn was exposed to a 6 MV photon beam to determine their performance, including the measurement of field size dependent output factors. The mechanical shutter determined the output factors to within 0.29% of those measured with an ionization chamber, whereas the LCD shutter gave results that deviated by up to 2.4%. The switching precision of both shutters was good with standard deviations of less than 0.25% and both were able to completely block the light signal when closed. The use of shutters could therefore be applied to any fibre optic based system to quantify and remove a reproducible background arising from any source including ambient, fluorescent and Cerenkov light.
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Affiliation(s)
- J J Lee
- School of Physics, The University of Sydney, NSW 2006, Australia.
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Morin J, Béliveau-Nadeau D, Chung E, Seuntjens J, Thériault D, Archambault L, Beddar S, Beaulieu L. A comparative study of small field total scatter factors and dose profiles using plastic scintillation detectors and other stereotactic dosimeters: The case of the CyberKnife. Med Phys 2013; 40:011719. [DOI: 10.1118/1.4772190] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Yoo WJ, Shin SH, Han KT, Jeon D, Hong S, Kim SG, Sim HI, Jang KW, Cho S, Park BG, Lee B. Feasibility study on development of Cerenkov fiber-optic dosimeter for radiotherapy application. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2013; 2013:485-487. [PMID: 24109729 DOI: 10.1109/embc.2013.6609542] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
To obtain real-time dose information in photon-beam therapy using a clinical linear accelerator, we fabricated a novel Cerenkov fiber-optic dosimeter using two plastic optical fibers without employing a scintillator. In this study, the light intensity and spectrum of Cerenkov radiation induced by a high-energy photon beam were measured as functions of the irradiation angle and the length difference between the two plastic optical fibers in the dosimeter probe. Also, we obtained a percentage depth dose curve for a 6 MV photon beam with a field size of 10 × 10 cm(2) according to the depth of the solid water phantom. Based on the results of this study, it is anticipated that the proposed Cerenkov fiber-optic dosimeter can be developed as a useful dosimeter to accurately obtain dose information prior to conducting radiotherapy.
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