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Renaud J, Palmans H, Sarfehnia A, Seuntjens J. Absorbed dose calorimetry. ACTA ACUST UNITED AC 2020; 65:05TR02. [DOI: 10.1088/1361-6560/ab4f29] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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Palmans H, Andreo P, Huq MS, Seuntjens J, Christaki KE, Meghzifene A. Dosimetry of small static fields used in external photon beam radiotherapy: Summary of TRS‐483, the IAEA–AAPM international Code of Practice for reference and relative dose determination. Med Phys 2018; 45:e1123-e1145. [DOI: 10.1002/mp.13208] [Citation(s) in RCA: 123] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2017] [Revised: 07/24/2018] [Accepted: 07/30/2018] [Indexed: 12/18/2022] Open
Affiliation(s)
- Hugo Palmans
- Medical Radiation Science National Physical Laboratory Teddington TW11 0LWUK
- Department of Medical Physics EBG MedAustron GmbH A‐2700Wiener Neustadt Austria
| | - Pedro Andreo
- Department of Medical Physics and Nuclear Medicine Karolinska University Hospital SE‐17176Stockholm Sweden
| | - M. Saiful Huq
- Department of Radiation Oncology University of Pittsburgh School of Medicine and UPMC Hillman Cancer Center Pittsburgh PA15232USA
| | - Jan Seuntjens
- Medical Physics Unit McGill University Montréal QCH3A 0G4Canada
| | - Karen E. Christaki
- Dosimetry and Medical Radiation Physics Section International Atomic Energy Agency A‐1400Vienna Austria
| | - Ahmed Meghzifene
- Dosimetry and Medical Radiation Physics Section International Atomic Energy Agency A‐1400Vienna Austria
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Borowicz DM, Malicki J, Mytsin G, Shipulin K. Dose distribution at the Bragg peak: Dose measurements using EBT and RTQA gafchromic film set at two positions to the central beam axis. Med Phys 2017; 44:1538-1544. [PMID: 28196271 DOI: 10.1002/mp.12159] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2016] [Revised: 01/23/2017] [Accepted: 02/05/2017] [Indexed: 11/08/2022] Open
Abstract
AIM To evaluate the impact of radiochromic film positioning relative to the central beam axis (CAX) in proton beam therapy. Secondarily, to compare the dosimetric measurements obtained by RTQA and EBT film and to compare these to the doses calculated by the treatment planning system (TPS). METHODS The EBT and RTQA dosimetric radiochromic films were immersed in a water phantom and irradiated with a proton beam. The films were placed parallel to the CAX and at a 5° angle on the horizontal plane to assess the effect of film inclination on Bragg peak profiles. Calibration was performed by irradiating small pieces of film at doses ranging from 0.0 Gy to 3.5 Gy in increments of 0.5 Gy. The TPS was used to create treatment plans for two different geometrical targets (cylindrical and cuboidal). After irradiation, all film pieces were scanned on a flatbed scanner and red channel data were extracted from the 48-bit RGB images using ImageJ, Photoshop, Origin8, and Excel software. The dose distributions from the irradiated films were compared to the dose obtained from the TPS. Bragg peak profiles were abstracted from the irradiated films and compared. RESULTS The dosimetric measurements obtained by both EBT and RTQA positioned at a 5° to the CAX closely matched the dose calculated by the TPS for the cylindrical target. In contrast, dose distributions measured in the cuboidal targets were less precise. Gamma index (GI) values (3%/3 mm acceptance criteria for isodose >90% of dose) were 99.8% and 93% for EBT film placed at a 5° angle versus 47.1% and 80.8% for EBT film parallel to the beam. The dosimetric measurements in RTQA film positioned parallel to the CAX showed GI values with <27% agreement with the TPS-calculated dose. CONCLUSION Our finding show that RTQA film can be used to accurately measure doses in the proton beam at the region of Bragg peak; however, to obtain the most accurate readings, the film should be positioned at a small angle to the CAX.
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Affiliation(s)
- Dorota Maria Borowicz
- Department of Medical Physics, Greater Poland Cancer Centre, Poznan, Poland.,Laboratory of Nuclear Problems, Joint Institute for Nuclear Research, 141980, Dubna, Moscow region, Russia
| | - Julian Malicki
- Department of Medical Physics, Greater Poland Cancer Centre, Poznan, Poland.,Electroradiology Department, University of Medical Sciences, Poznan, Poland
| | - Gennady Mytsin
- Laboratory of Nuclear Problems, Joint Institute for Nuclear Research, 141980, Dubna, Moscow region, Russia
| | - Konstantin Shipulin
- Laboratory of Nuclear Problems, Joint Institute for Nuclear Research, 141980, Dubna, Moscow region, Russia
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Reis C, Nicolucci P. Assessment of ionization chamber correction factors in photon beams using a time saving strategy with PENELOPE code. Phys Med 2016; 32:297-304. [DOI: 10.1016/j.ejmp.2016.01.482] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/07/2015] [Revised: 01/20/2016] [Accepted: 01/22/2016] [Indexed: 10/22/2022] Open
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Ulkowski P, Bulski W, Chełmiński K. Long-term stability of radiotherapy dosimeters calibrated at the Polish Secondary Standard Dosimetry Laboratory. Appl Radiat Isot 2015; 104:181-5. [PMID: 26183579 DOI: 10.1016/j.apradiso.2015.04.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2014] [Revised: 02/19/2015] [Accepted: 04/16/2015] [Indexed: 11/16/2022]
Abstract
Unidos 10001, Unidos E (10008/10009) and Dose 1 electrometers from 14 radiotherapy centres were calibrated 3-4 times over a long period of time, together with Farmer type (PTW 30001, 30013, Nuclear Enterprises 2571 and Scanditronix-Wellhofer FC65G) cylindrical ionization chambers and plane-parallel type chambers (PTW Markus 23343 and Scanditronix-Wellhofer PPC05). On the basis of the long period of repetitive establishing of calibration coefficients for the same electrometers and ionization chambers, the accuracy of electrometers and the long-term stability of ionization chambers were examined. All measurements were carried out at the same laboratory, by the same staff, according to the same IAEA recommendations. A good accuracy and long-term stability of the dosimeters used in Polish radiotherapy centres was observed. These values were within 0.1% for electrometers and 0.2% for the chambers with electrometers. Furthermore, these values were not observed to vary over time. The observations confirm the opinion that the requirement of calibration of the dosimeters more often than every 2 years is not justified.
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Affiliation(s)
- Piotr Ulkowski
- Department of Medical Physics, The Maria Skłodowska-Curie Memorial Cancer Centre and Institute of Oncology, Roentgena 5, 02-781 Warsaw, Poland
| | - Wojciech Bulski
- Department of Medical Physics, The Maria Skłodowska-Curie Memorial Cancer Centre and Institute of Oncology, Roentgena 5, 02-781 Warsaw, Poland.
| | - Krzysztof Chełmiński
- Department of Medical Physics, The Maria Skłodowska-Curie Memorial Cancer Centre and Institute of Oncology, Roentgena 5, 02-781 Warsaw, Poland.
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Villegas F, Tilly N, Ahnesjö A. Monte Carlo calculated microdosimetric spread for cell nucleus-sized targets exposed to brachytherapy125I and192Ir sources and60Co cell irradiation. Phys Med Biol 2013; 58:6149-62. [DOI: 10.1088/0031-9155/58/17/6149] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Borowicz DM, Malicki J, Mytsin G, Shipulin K. Wax boluses and accuracy of EBT and RTQA radiochromic film detectors in radiotherapy with the JINR Phasotron proton beam. Rep Pract Oncol Radiother 2013; 19:12-8. [PMID: 24936315 DOI: 10.1016/j.rpor.2013.05.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2012] [Revised: 05/03/2013] [Accepted: 05/16/2013] [Indexed: 11/19/2022] Open
Abstract
AIM To present the results obtained using radiochromic films EBT and RTQA 1010P for the reconstruction the dose distributions for targets irradiated by proton beam and modified by wax boluses. BACKGROUND In Medico-Technical Complex at the Joint Institute for Nuclear Research in Dubna implemented technology of wax boluses. MATERIALS AND METHODS Wax boluses are easier to make and they give better dose distributions than boluses made from modeling clay previously used at our center. We irradiated two imaginary targets, one shaped as a cylinder and the other one as two cuboids. The evaluated calibration curve was used for calculation of the dose distributions measured by the EBT and RTQA radiochromic film. In both cases, the measured dose distributions were compared to the dose distributions calculated by the treatment planning system (TPS). We also compared dose distributions using three different conformity indices at a 95% isodose. RESULTS Better target coverage and better compliance of measurements (semiconductor detectors and radiochromic films) with calculated doses was obtained for cylindrical target than for cuboidal target. The 95% isodose covered well the tumor for both target shapes, while for cuboidal target larger volume around the target received therapeutic dose, due to the complicated target shape. The use wax boluses provided to be effective tool in modifying proton beam to achieve appropriate shape of isodose distribution. CONCLUSION EBT film yielded the best visual matching. Both EBT and RTQA films confirmed good conformity between calculated and measured doses, thus confirming that wax boluses used to modify the proton beam resulted in good dose distributions.
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Affiliation(s)
- Dorota Maria Borowicz
- Department of Medical Physics, Greater Poland Cancer Centre, 15 Garbary Street, 61-688 Poznan, Poland ; Laboratory of Nuclear Problems, Joint Institute for Nuclear Research, 6 Joliot-Curie Street, 141980 Dubna, Moscow Region, Russia
| | - Julian Malicki
- Department of Medical Physics, Greater Poland Cancer Centre, 15 Garbary Street, 61-688 Poznan, Poland ; Electroradiology Department, University of Medical Sciences, 15 Garbary Street, 61-688 Poznan, Poland
| | - Gennady Mytsin
- Laboratory of Nuclear Problems, Joint Institute for Nuclear Research, 6 Joliot-Curie Street, 141980 Dubna, Moscow Region, Russia
| | - Konstantin Shipulin
- Laboratory of Nuclear Problems, Joint Institute for Nuclear Research, 6 Joliot-Curie Street, 141980 Dubna, Moscow Region, Russia
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Kulkarni A, Kim B, Dugasani SR, Joshirao P, Kim JA, Vyas C, Manchanda V, Kim T, Park SH. A novel nanometric DNA thin film as a sensor for alpha radiation. Sci Rep 2013; 3:2062. [PMID: 23792924 PMCID: PMC3690391 DOI: 10.1038/srep02062] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2013] [Accepted: 06/07/2013] [Indexed: 11/09/2022] Open
Abstract
The unexpected nuclear accidents have provided a challenge for scientists and engineers to develop sensitive detectors, especially for alpha radiation. Due to the high linear energy transfer value, sensors designed to detect such radiation require placement in close proximity to the radiation source. Here we report the morphological changes and optical responses of artificially designed DNA thin films in response to exposure to alpha radiation as observed by an atomic force microscope, a Raman and a reflectance spectroscopes. In addition, we discuss the feasibility of a DNA thin film as a radiation sensing material. The effect of alpha radiation exposure on the DNA thin film was evaluated as a function of distance from an ²⁴¹Am source and exposure time. Significant reflected intensity changes of the exposed DNA thin film suggest that a thin film made of biomolecules can be one of promising candidates for the development of online radiation sensors.
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Affiliation(s)
- Atul Kulkarni
- Sungkyunkwan Advanced Institute of Nanotechnology (SAINT), Sungkyunkwan University, Suwon 440–746, Korea
- Department of Physics, Sungkyunkwan University, Suwon 440–746, Korea
- School of Mechanical Engineering, Sungkyunkwan University, Suwon 440–746, Korea
- These authors contributed equally to this work
| | - Byeonghoon Kim
- Sungkyunkwan Advanced Institute of Nanotechnology (SAINT), Sungkyunkwan University, Suwon 440–746, Korea
- Department of Physics, Sungkyunkwan University, Suwon 440–746, Korea
- These authors contributed equally to this work
| | - Sreekantha Reddy Dugasani
- Sungkyunkwan Advanced Institute of Nanotechnology (SAINT), Sungkyunkwan University, Suwon 440–746, Korea
- Department of Physics, Sungkyunkwan University, Suwon 440–746, Korea
- These authors contributed equally to this work
| | - Pranav Joshirao
- Department of Energy Science, Sungkyunkwan University, Suwon 440–746, Korea
| | - Jang Ah Kim
- Sungkyunkwan Advanced Institute of Nanotechnology (SAINT), Sungkyunkwan University, Suwon 440–746, Korea
- School of Mechanical Engineering, Sungkyunkwan University, Suwon 440–746, Korea
| | - Chirag Vyas
- Department of Energy Science, Sungkyunkwan University, Suwon 440–746, Korea
| | - Vijay Manchanda
- Department of Energy Science, Sungkyunkwan University, Suwon 440–746, Korea
| | - Taesung Kim
- Sungkyunkwan Advanced Institute of Nanotechnology (SAINT), Sungkyunkwan University, Suwon 440–746, Korea
- School of Mechanical Engineering, Sungkyunkwan University, Suwon 440–746, Korea
| | - Sung Ha Park
- Sungkyunkwan Advanced Institute of Nanotechnology (SAINT), Sungkyunkwan University, Suwon 440–746, Korea
- Department of Physics, Sungkyunkwan University, Suwon 440–746, Korea
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Magaddino V, Manser P, Frei D, Volken W, Schmidhalter D, Hirschi L, Fix MK. Validation of the Swiss Monte Carlo Plan for a static and dynamic 6 MV photon beam. Z Med Phys 2011; 21:124-34. [DOI: 10.1016/j.zemedi.2010.10.010] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2010] [Revised: 10/08/2010] [Accepted: 10/27/2010] [Indexed: 11/28/2022]
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Ahmadi M, Yeow JTW. Fabrication and characterization of a radiation sensor based on bacteriorhodopsin. Biosens Bioelectron 2011; 26:2171-6. [PMID: 20947328 DOI: 10.1016/j.bios.2010.09.029] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2010] [Revised: 09/13/2010] [Accepted: 09/14/2010] [Indexed: 11/15/2022]
Abstract
Available techniques of X-ray detection have been under development due to specific shortcomings such as finite lifetime, low sensitivity, and post-processing requirements. Here we report on the fabrication of an X-ray sensor based on bacteriorhodopsin (BR) with a radius of r=3mm as the sensing area on a flexible substrate. The flexible X-ray detector can be placed on the targeted area for real-time monitoring of radiation dosage. We show that BR sensor is a potential candidate for such a powerful sensing device. For this purpose, we measure the electrical current generated by the BR sensor under different radiation dosages, energies and dose rates. This averaged current is in the range of nanoampere and is proportional to the dose rate of the received X-ray. The current also increases with the increase of radiation energy. BR radiation sensor can be readily miniaturized and is relatively easy to fabricate. The capability for real-time data collection and reusability are other advantages of this radiation sensor.
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Affiliation(s)
- Morteza Ahmadi
- Waterloo Institute for Nanotechnology, University of Waterloo, 200 University Ave W, Waterloo, Ontario, Canada N2L 3G1
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O'Shea TP, Sawkey DL, Foley MJ, Faddegon BA. Monte Carlo commissioning of clinical electron beams using large field measurements. Phys Med Biol 2010; 55:4083-105. [DOI: 10.1088/0031-9155/55/14/009] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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González-Castaño DM, Hartmann GH, Sánchez-Doblado F, Gómez F, Kapsch RP, Pena J, Capote R. The determination of beam quality correction factors: Monte Carlo simulations and measurements. Phys Med Biol 2009; 54:4723-41. [DOI: 10.1088/0031-9155/54/15/006] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Sawkey DL, Faddegon BA. Determination of electron energy, spectral width, and beam divergence at the exit window for clinical megavoltage x-ray beams. Med Phys 2009; 36:698-707. [PMID: 19378730 DOI: 10.1118/1.3070547] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Monte Carlo simulations of x-ray beams typically take parameters of the electron beam in the accelerating waveguide to be free parameters. In this paper, a methodology is proposed and implemented to determine the energy, spectral width, and beam divergence of the electron source. All treatment head components were removed from the beam path, leaving only the exit window. With the x-ray target and flattener out of the beam, uncertainties in physical characteristics and relative position of the target and flattening filter, and in spot size, did not contribute to uncertainty in the energy. Beam current was lowered to reduce recombination effects. The measured dose distributions were compared with Monte Carlo simulation of the electron beam through the treatment head to extract the electron source characteristics. For the nominal 6 and 18 MV x-ray beams, the energies were 6.51 +/- 0.15 and 13.9 +/- 0.2 MeV, respectively, with the uncertainties resulting from uncertainties in the detector position in the measurement and in the stopping power in the simulations. Gaussian spectral distributions were used, with full widths at half maximum ranging from 20 +/- 4% at 6 MV to 13 +/- 4% at 18 MV required to match the fall-off portion of the percent-depth ionization curve. Profiles at the depth of maximum dose from simulations that used the manufacturer-specified exit window geometry and no beam divergence were 2-3 cm narrower than measured profiles. Two simulation configurations yielding the measured profile width were the manufacturer-specified exit window thickness with electron source divergences of 3.3 degrees at 6 MV and 1.8 degrees at 18 MV and an exit window 40% thicker than the manufacturer's specification with no beam divergence. With the x-ray target in place (and no flattener), comparison of measured to simulated profiles sets upper limits on the electron source divergences of 0.2 degrees at 6 MV and 0.1 degrees at 18 MV. A method of determining source characteristics without mechanical modification of the treatment head, and therefore feasible in clinics, is presented. The energies and spectral widths determined using this method agree with those determined with only the exit window in the beam path.
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Affiliation(s)
- D L Sawkey
- Department of Radiation Oncology, University of California San Francisco, 1600 Divisadero Street, San Francisco, California 94143, USA.
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Castrillón SV, Henríquez FC. Comparison of IPSM 1990 photon dosimetry code of practice with IAEA TRS-398 and AAPM TG-51. J Appl Clin Med Phys 2009; 10:136-146. [PMID: 19223831 PMCID: PMC5720500 DOI: 10.1120/jacmp.v10i1.2810] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2008] [Accepted: 09/02/2008] [Indexed: 11/24/2022] Open
Abstract
Several codes of practice for photon dosimetry are currently used around the world, supported by different organizations. A comparison of IPSM 1990 with both IAEA TRS-398 and AAPM TG-51 has been performed. All three protocols are based on the calibration of ionization chambers in terms of standards of absorbed dose to water, as it is the case with other modern codes of practice. This comparison has been carried out for photon beams of nominal energies: 4 MV, 6 MV, 8 MV, 10 MV and 18 MV. An NE 2571 graphite ionization chamber was used in this study, cross-calibrated against an NE 2611A Secondary Standard, calibrated in the National Physical Laboratory (NPL). Absolute dose in reference conditions was obtained using each of these three protocols including: beam quality indices, beam quality conversion factors both theoretical and NPL experimental ones, correction factors for influence quantities and absolute dose measurements. Each protocol recommendations have been strictly followed. Uncertainties have been obtained according to the ISO Guide to the Expression of Uncertainty in Measurement. Absorbed dose obtained according to all three protocols agree within experimental uncertainty. The largest difference between absolute dose results for two protocols is obtained for the highest energy: 0.7% between IPSM 1990 and IAEA TRS-398 using theoretical beam quality conversion factors.
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Fourie OL. Comparison of linear accelerator photon outputs from the IAEA TRS-398 and TRS-277 codes of practice. AUSTRALASIAN PHYSICAL & ENGINEERING SCIENCES IN MEDICINE 2008; 31:24-31. [DOI: 10.1007/bf03178450] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Castro P, García-Vicente F, Mínguez C, Floriano A, Sevillano D, Pérez L, Torres JJ. Study of the uncertainty in the determination of the absorbed dose to water during external beam radiotherapy calibration. J Appl Clin Med Phys 2008; 9:70-86. [PMID: 18449162 PMCID: PMC5721533 DOI: 10.1120/jacmp.v9i1.2676] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2007] [Revised: 06/24/2007] [Accepted: 08/21/2007] [Indexed: 11/23/2022] Open
Abstract
To achieve a good clinical outcome in radiotherapy treatment, a certain accuracy in the dose delivered to the patient is required. Therefore, it is necessary to keep the uncertainty in each of the steps of the process inside some acceptable values, which implies as low a global uncertainty as possible. The work reported here focused on the uncertainty evaluation of absorbed dose to water in the routine calibration for clinical beams in the range of energies used in external‐beam radiotherapy. With this aim, we considered various uncertainty components (corrected electrometer reading, calibration factor, beam quality correction factor, and reference conditions) associated with beam calibration. Results show a typical uncertainty in the determination of absorbed dose to water during beam calibration of approximately 1.3% for photon beams and 1.5% for electron beams (k=1 in both cases) when the ND,w formalism is used and kQ,Q0 is calculated theoretically. These values may vary depending on the uncertainty provided by the standards laboratory for calibration factor, which is shown in the work. For primary standards based on clinical linear accelerator beam energies, the uncertainty in this step of the process could be placed close to 1.0%. We also discuss the possibility of an uncertainty reduction with the adoption of the absorbed dose to water formalism as compared with the air kerma formalism. PACS numbers: 87.53.Dq, 87.53.Hv
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Affiliation(s)
- Pablo Castro
- Servicio de Oncología Radioterápica, Departamento de Radiofísica, Hospital Universitario "La Princesa", Madrid, Spain
| | - Feliciano García-Vicente
- Servicio de Oncología Radioterápica, Departamento de Radiofísica, Hospital Universitario "La Princesa", Madrid, Spain
| | - Cristina Mínguez
- Servicio de Oncología Radioterápica, Departamento de Radiofísica, Hospital Universitario "La Princesa", Madrid, Spain
| | - Alejandro Floriano
- Servicio de Oncología Radioterápica, Departamento de Radiofísica, Hospital Universitario "La Princesa", Madrid, Spain
| | - David Sevillano
- Servicio de Oncología Radioterápica, Departamento de Radiofísica, Hospital Universitario "La Princesa", Madrid, Spain
| | - Leopoldo Pérez
- Servicio de Oncología Radioterápica, Departamento de Radiofísica, Hospital Universitario "La Princesa", Madrid, Spain
| | - Juan J Torres
- Servicio de Oncología Radioterápica, Departamento de Radiofísica, Hospital Universitario "La Princesa", Madrid, Spain
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Kapsch RP, Bruggmoser G, Christ G, Dohm OS, Hartmann GH, Schüle E. Experimental determination ofpCoperturbation factors for plane-parallel chambers. Phys Med Biol 2007; 52:7167-81. [DOI: 10.1088/0031-9155/52/23/026] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Butler DJ, Palmans H, Webb DV. Shift in absorbed dose for megavoltage photons when changing to TRS-398 in Australia. ACTA ACUST UNITED AC 2005; 28:159-64. [PMID: 16250469 DOI: 10.1007/bf03178709] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Australian primary standards of air kerma and absorbed dose are realized in 60Co gamma rays. To calibrate the megavoltage photon beams from linear accelerators, radiotherapy centres have their ionization chamber calibrated in a 60Co beam and then use a protocol to transfer this calibration to the higher energy. The radiotherapy community is in the process of changing from the ACPSEM Protocol (Second Edition 1998) based on an air kerma calibration to the IAEA's TRS-398 Code of Practice, based on an absorbed dose to water calibration. To evaluate the shift in absorbed dose resulting from the new protocol, the absorbed dose should be determined using both protocols and compared. We present a formula for this shift which can be used to check the result. To use this formula the centre needs to measure a displacement correction and know the ratio of the air kerma to absorbed dose to water calibration factors at 60Co. We calculate the change they should expect by using the average ratio of the air kerma and absorbed dose to water calibration factors for NE2571 and NE2561 chambers, based on Australian standards, and by estimating the displacement correction from published depth dose data. We find the absorbed dose in a megavoltage photon beam to increase by between 0.1 and 0.6% for NE2571 chambers and between 0.7 and 1.1% for NE2561 chambers, for beams up to 35 MV. The dose measured using TRS-398 is always higher.
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Affiliation(s)
- D J Butler
- Australian Radiation Protection and Nuclear Safety Agency, Yallambie, Australia.
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Abstract
Accurate simulation of large electron fields may lead to improved accuracy in Monte Carlo treatment planning while simplifying the commissioning procedure. We have used measurements made with wide-open jaws and no electron applicator to adjust simulation parameters. Central axis depth dose curves and profiles of 6-21 MeV electron beams measured in this geometry were used to estimate source and geometry parameters, including those that affect beam symmetry: incident beam direction and offset of the secondary scattering foil and monitor chamber from the beam axis. Parameter estimation relied on a comprehensive analysis of the sensitivity of the measured quantities, in the large field, to source and geometry parameters. Results demonstrate that the EGS4 Monte Carlo system is capable of matching dose distributions in the largest electron field to the least restrictive of 1 cGy or 1 mm, with D(max) of 100 cGy, over the full energy range. This match results in an underestimation of the bremsstrahlung dose of 10-20% at 15-21 MeV, exceeding the combined experimental and calculational uncertainty in this quantity of 3%. The simulation of electron scattering at energies of 15-21 MeV in EGS4 may be in error. The recently released EGSnrc/BEAMnrc system may provide a better match to measurement.
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Affiliation(s)
- B Faddegon
- Department of Radiation Oncology, University of California, San Francisco, CA 94143, USA.
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