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El Gamal I, Dessureault J, McEwen MR. A novel calorimeter for synchrotron produced monochromatic x-ray beams. Med Phys 2023; 50:6543-6553. [PMID: 37287315 DOI: 10.1002/mp.16526] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Revised: 03/12/2023] [Accepted: 05/05/2023] [Indexed: 06/09/2023] Open
Abstract
BACKGROUND Electron synchrotrons produce x-ray beams with dose rates orders of magnitude greater than conventional x-ray tubes and with beam sizes on the order of a few millimeters. These characteristics put severe challenges on current dosimeters to accurately realize absorbed dose or air kerma. PURPOSE This work seeks to investigate the suitability of a novel aluminum-based calorimeter to determine absorbed dose to water with an uncertainty significantly smaller than currently possible with conventional detectors. A lower uncertainty in the determination of absolute dose rate would impact both therapeutic applications of synchrotron-produced x-ray beams and research investigations. METHODS A vacuum-based calorimeter prototype with an aluminum core was built, matching the beam profile of the 140 keV monochromatic x-ray beam, produced by the Canadian Light Source Biomedical Imaging and Therapy beamline. The choice of material and overall calorimeter design was optimized using FEM thermal modeling software while Monte Carlo radiation transport simulations were used to model the impact of interactions of the radiation beam with the detector components. RESULTS Corrections for both the thermal conduction and radiation transport effects were of the order of 3% and the simplicity of the geometry, combined with the monochromatic nature of the incident x-ray beam, meant that the uncertainty in each correction was ≤0.5%. The calorimeter performance was found to be repeatable over multiple irradiations of 1 Gy at the ± 0.6% level, and no systematic dependence on environmental effects or total dose was observed. CONCLUSION The combined standard uncertainty in the determination of absorbed dose to aluminum was estimated to be 0.8%, indicating that absorbed dose to water, the ultimate quantity of interest, could be determined with an uncertainty on the order of 1%. This value is an improvement over current techniques used for synchrotron dosimetry and comparable with the state-of-the art for conventional kV x-ray dosimetry.
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Affiliation(s)
- Islam El Gamal
- Metrology Research Centre, National Research Council Canada, Ottawa, Ontario, Canada
- Department of Physics, Carleton University, Ottawa, Ontario, Canada
| | - Jean Dessureault
- Metrology Research Centre, National Research Council Canada, Ottawa, Ontario, Canada
| | - Malcolm R McEwen
- Metrology Research Centre, National Research Council Canada, Ottawa, Ontario, Canada
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Chan MF, Park J, Aydin R, Lim SB. Technical note: Energy dependence of the Gafchromic EBT4 film: Dose-response curves for 70 kV, 6 MV, 6 MV FFF, 10 MV FFF, and 15 MV x-ray beams. Med Phys 2023; 50:3738-3745. [PMID: 36695666 PMCID: PMC10635410 DOI: 10.1002/mp.16240] [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: 10/17/2022] [Revised: 12/30/2022] [Accepted: 01/09/2023] [Indexed: 01/26/2023] Open
Abstract
BACKGROUND EBT4 was newly released for radiotherapy quality assurance to improve the signal-to-noise ratio in radiochromic film dosimetry. It is important to know its dose-response characteristics before its use in the clinic. PURPOSE This study aims to investigate and compare the dose-response curves of the Gafchromic EBT4 film for megavoltage and kilovoltage x-ray beams with different dose levels, scanning spatial resolutions, and sizes of region of interest (ROI). METHODS EBT4 film (Lot#07052201) calibration strips (3.5 × 20 cm2 ) were exposed to a 10×10 cm2 open field at doses of 0, 63, 125, 500, 750, 1000 cGy using 6 MV photon beam. EBT4 film strips from the same lot were then exposed to each x-ray beam (6 MV, 6 MV FFF, 10 MV FFF, 15 MV, and 70 kV) at six dose values (50, 100, 300, 600, 800, 1000 cGy). A full sheet (25 × 20 cm2 ) of EBT4 film was irradiated at each energy with 300 cGy for profile comparison with the treatment planning calculation. At two different spatial resolutions of 72 and 300 dpi, each film piece was scanned three consecutive times in the center of an Epson 10000XL flatbed scanner in 48-bit color. The scanned images were analyzed using FilmQA Pro. For each scanned image, an ROI of 2 × 2 cm2 at the field center was selected to obtain the average pixel value with its standard deviation in the ROI. An additional ROI of 1 cm diameter circle was also used to evaluate the impact of ROI shape and size, especially for FFF beams. The dose value, average dose-response value, and associated uncertainty were determined for each energy and relative responses were analyzed. The Student's t-test was performed to evaluate the statistical significance of the dose-response values with different color channels, ROI shapes, and spatial resolutions. RESULTS The dose-response curves for the five x-ray energies were compared in three color channels. Weak energy dependence was found among the megavoltage beams. No significant differences (average ∼1.1%) were observed for all doses in this study among 6 MV, 6 MV FFF, 10 MV FFF, and 15 MV beams, regardless of spatial resolution and color channel. However, a statistically significant difference in dose-response was observed up to 12% between 70 kV and 6 MV beams. CONCLUSIONS The dose-response curves for Gafchromic EBT4 films were nearly independent of the energy of the photon beams among 6 MV, 6 MV FFF, 10 MV FFF, and 15 MV. For very low-energy photons (e.g., 70 kV), a separate calibration from the same low-energy x-ray is necessary.
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Affiliation(s)
- Maria F. Chan
- Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, NY 10065
| | - Jeonghoon Park
- Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, NY 10065
| | | | - Seng-Boh Lim
- Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, NY 10065
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Li X, Su FC, Sarkar V, Zhao H, Ibanez S, Kunz JN, Nelson G, Jessica Huang Y. Impact of detector selection on commissioning of Leipzig surface applicators with improving immobilization in high-dose-rate brachytherapy. Brachytherapy 2022; 21:511-519. [PMID: 35256286 DOI: 10.1016/j.brachy.2022.01.007] [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: 09/21/2021] [Revised: 01/21/2022] [Accepted: 01/24/2022] [Indexed: 11/02/2022]
Abstract
PURPOSE Commission and treatment setup of Leipzig surface applicators, because of the steep dose gradient and lack of robust immobilization, is challenging. We aim to improve commissioning reliability by investigating the impact of detector choice on percentage depth dose (PDD) verifications, and to enhance accuracy and reproducibility in calibration/treatment setup through a simple and novel immobilization device. METHODS AND MATERIALS PDD distributions were measured with radiochromic films, optically stimulated luminescent dosimeters (OSLDs), a diode detector, and both cylindrical and parallel plate ionization chambers. The films were aligned to the applicators in parallel and transverse orientations. PDD data from a benchmarking Monte Carlo (MC) study were compared with the measured results, where surface doses were acquired from extrapolation. To improve setup accuracy and reproducibility, a custom-designed immobilization prototype device was made with cost-effective materials using a 3D printer. RESULTS The measured PDD data with different detectors had an overall good agreement (<±10%). The parallel plate ionization chamber reported unreliable doses for the smallest applicator. There was no remarkable dose difference between the two film setups. The two-in-one prototype device provided a rigid immobilization and a flexible positioning of the applicator. It enhanced accuracy and reproducibility in calibration and treatment setup. CONCLUSION We recommend using radiochromic films in the transverse orientation for a reliable and efficient PDD verification. The applicator's clinical applicability has been limited by a lack of robust immobilization. We expect this economical, easy-to-use prototype device can promote the use of Leipzig applicators in surface brachytherapy.
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Affiliation(s)
- Xing Li
- Department of Radiation Oncology, University of Utah, Salt Lake City, UT.
| | - Fan-Chi Su
- Department of Radiation Oncology, University of Utah, Salt Lake City, UT
| | - Vikren Sarkar
- Department of Radiation Oncology, University of Utah, Salt Lake City, UT
| | - Hui Zhao
- Department of Radiation Oncology, University of Utah, Salt Lake City, UT
| | - Sergio Ibanez
- Department of Radiation Oncology, University of Utah, Salt Lake City, UT
| | - Jeremy N Kunz
- Department of Radiation Oncology, University of Utah, Salt Lake City, UT
| | - Geoff Nelson
- Department of Radiation Oncology, University of Utah, Salt Lake City, UT
| | - Y Jessica Huang
- Department of Radiation Oncology, University of Utah, Salt Lake City, UT
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Synthesis and Characterization of a New Nanocomposite Film Based on Polyvinyl Alcohol Polymer and Nitro Blue Tetrazolium Dye as a Low Radiation Dosimeter in Medical Diagnostics Application. Polymers (Basel) 2021; 13:polym13111815. [PMID: 34072823 PMCID: PMC8197916 DOI: 10.3390/polym13111815] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Revised: 05/25/2021] [Accepted: 05/27/2021] [Indexed: 02/06/2023] Open
Abstract
Dosimetry is a field of increasing importance in diagnostic radiology. There has been a realization among healthcare professionals that the dose of radiation received by patients via modern medical X-ray examinations could induce acute damage to the skin and eyes. The present study highlights the synthesis of polyvinyl alcohol/nitro blue tetrazolium nanocomposite films (PVA/NBT) for radiation detection depending on chromic, optical, chemical and morphologic changes. First, we synthesized the nanocomposite film-based PVA doped with NBT and the different parameters of the preparation procedure were optimized. Then The films were exposed to different low X-ray doses on the scale of mGy level (0, 2, 4, 10 and 20 mGy). The sensitivity and the performance of the made composite films were evaluated via different characterization methods. Indeed, the response curve based on UV-Vis absorptions revealed a linear increase in absorbance with increased radiation doses (R = 0.998). FTIR analysis showed a clear chemical modification in recorded spectra after irradiation. X-ray diffraction assessment revealed clear structural changes in crystallinity after ionization treatment. SEM analysis showed a clear morphological modification of PVA/NBT films after irradiation. In addition, the prepared PVA/NBT films exhibited excellent pre- and post-irradiation stability in dark and light. Finally, the quantitative colorimetry study confirmed the performance of the prepared films and the different colorimetric coordinates, the total color difference (∆E) and the color strength (K/S) showed a linear increase with increasing X-ray doses. The made nanocomposite PVA/NBT film might offer promising potential for an effective highly sensitive medical dosimeter applied for very low doses in X-ray diagnostic radiology.
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Hermida-López M, Sánchez-Artuñedo D, Rodríguez M, Brualla L. Monte Carlo simulation of conical collimators for stereotactic radiosurgery with a 6 MV flattening-filter-free photon beam. Med Phys 2021; 48:3160-3171. [PMID: 33715167 DOI: 10.1002/mp.14837] [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: 11/15/2020] [Revised: 02/19/2021] [Accepted: 03/08/2021] [Indexed: 11/07/2022] Open
Abstract
PURPOSE Conical collimators, or cones, are tertiary collimators that attach to a radiotherapy linac and are suited for the stereotactic radiosurgery treatment of small brain lesions. The small diameter of the most used cones makes difficult the acquisition of the dosimetry data needed for the commissioning of treatment planning systems. Although many publications report dosimetric data of conical collimators for stereotactic radiosurgery, most of the works use different setups, which complicates comparisons. In other cases, the cone output factors reported do not take into account the effect of the small cone diameter on the detector response. Finally, few data exist on the dosimetry of cones with flattening-filter-free (FFF) beams from modern linac models. This work aims at obtaining a dosimetric characterization of the conical collimators manufactured by Brainlab AG (Munich, Germany) in a 6 MV FFF beam from a TrueBeam STx linac (Varian Medical Systems). METHODS Percentage depth dose curves, lateral dose profiles and cone output factors were obtained using Monte Carlo simulations for the cones with diameters of 4, 5, 6, 7.5, 8, 10, 12.5, 15, 17.5, 20, 25, and 30 mm. The simulation of the linac head was carried out with the PRIMO Monte Carlo software, and the simulations of the cones and the water phantom were run with the general-purpose Monte Carlo code PENELOPE. The Monte Carlo model was validated by comparing the simulation results with measurements performed for the cones of 4, 5, and 7.5 mm of diameter using a stereotactic field diode, a microDiamond detector and EBT3 radiochromic film. In addition, for those cones, simulations and measurements were done for comparison purposes, by reproducing the experimental setups from the available publications. RESULTS The experimental data acquired for the cones of 4, 5, and 7.5 mm validated the developed Monte Carlo model. The simulations accurately reproduced the experimental depths of maximum dose and the dose ratio at 20- and 10-cm depth (PDD20/10 ). A good agreement was obtained between simulated and experimental lateral dose profiles: The differences in the full-width at half-maximum were smaller than 0.2 mm, and the differences in the penumbra 80%-20% were smaller than 0.25 mm. The difference between the simulated and the average of the experimental output factors for the cones of 4, 5, and 7.5 mm of diameter was 0.0%, 0.0%, and 3.0%, respectively, well within the statistical uncertainty of the simulations (4.4% with coverage factor k = 2). It was also found that the simulated cone output factors agreed within 2% with the average of output factors reported in the literature for a variety of setup conditions, detectors, beam qualities, and cone manufacturers. CONCLUSION A Monte Carlo model of cones for stereotactic radiosurgery has been developed and validated. The cone dosimetry dataset obtained in this work, consisting of percentage depth doses, lateral dose profiles and output factors, is useful to benchmark data acquired for the commissioning of cone-based radiosurgery treatment planning systems.
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Affiliation(s)
- Marcelino Hermida-López
- Servei de Física i Protecció Radiològica, Hospital Universitari Vall d'Hebron, Vall d'Hebron Barcelona Hospital Campus, Passeig Vall d'Hebron 119-129, Barcelona, 08035, Spain
| | - David Sánchez-Artuñedo
- Servei de Física i Protecció Radiològica, Hospital Universitari Vall d'Hebron, Vall d'Hebron Barcelona Hospital Campus, Passeig Vall d'Hebron 119-129, Barcelona, 08035, Spain
| | - Miguel Rodríguez
- Centro Médico Paitilla, Calle 53 y ave. Balboa, Panama City, Panama.,Instituto de Investigaciones Científicas y de Alta Tecnología, INDICASAT-AIP, City of Knowledge, Building 219, Panama City, Panama
| | - Lorenzo Brualla
- West German Proton Therapy Centre Essen (WPE), Hufelandstr. 55, Essen, 45147, Germany.,West German Cancer Centre (WTZ), Hufelandstr. 55, Essen, 45147, Germany.,Faculty of Medicine, University of Duisburg-Essen, Hufelandstr. 55, Essen, 45147, Germany
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Niroomand‐Rad A, Chiu‐Tsao S, Grams MP, Lewis DF, Soares CG, Van Battum LJ, Das IJ, Trichter S, Kissick MW, Massillon‐JL G, Alvarez PE, Chan MF. Report of AAPM Task Group 235 Radiochromic Film Dosimetry: An Update to TG‐55. Med Phys 2020; 47:5986-6025. [DOI: 10.1002/mp.14497] [Citation(s) in RCA: 64] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Revised: 09/15/2020] [Accepted: 09/17/2020] [Indexed: 12/12/2022] Open
Affiliation(s)
| | | | | | | | | | | | - Indra J. Das
- Radiation Oncology Northwestern University Memorial Hospital Chicago IL USA
| | - Samuel Trichter
- New York‐Presbyterian HospitalWeill Cornell Medical Center New York NY USA
| | | | - Guerda Massillon‐JL
- Instituto de Fisica Universidad Nacional Autonoma de Mexico Mexico City Mexico
| | - Paola E. Alvarez
- Imaging and Radiation Oncology Core MD Anderson Cancer Center Houston TX USA
| | - Maria F. Chan
- Memorial Sloan Kettering Cancer Center Basking Ridge NJ USA
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Prentou E, Lekatou A, Pantelis E, Karaiskos P, Papagiannis P. On the use of EBT3 film for relative dosimetry of kilovoltage X ray beams. Phys Med 2020; 74:56-65. [PMID: 32417711 DOI: 10.1016/j.ejmp.2020.04.025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Revised: 04/14/2020] [Accepted: 04/26/2020] [Indexed: 11/25/2022] Open
Abstract
EBT3 films were evaluated for relative dosimetry in water, in the energy range of therapeutic kV X ray beams. A film batch was calibrated in air for all nine beam qualities of a clinical unit (XStrahl 200). Monte Carlo (MC) simulations using MCNP v.6 facilitated the calculation of the film absorbed dose (f), and beam quality (kbq) energy dependences in air. Results were found in agreement with corresponding data in the literature. Film samples from the same batch were irradiated in water along the central beam axis for each beam quality. Experimental percentage depth dose (PDD) results obtained using calibration data in air showed quality and depth dependent differences from corresponding MC simulations. These differences increased beyond film dosimetry uncertainty (<3.3%), reaching up to 8% at increased depth. The observed differences reduced only slightly when spectral variation as a function of measurement point was accounted for, using photon effective energy. PDD measurements and corresponding MC results facilitated the determination of f and kbq in water. Results showed that the origin of the observed differences between experimental and MC PDD results is the difference between film response in air and water, as a result of radiation field perturbation from the film oriented along the central beam axis. This implies a directional dependence of film response which necessitates that the angular distribution of photons impinging on the film is the same in the calibration and measurement geometries.
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Affiliation(s)
- E Prentou
- Medical Physics Laboratory, Medical School, National and Kapodistrian University of Athens, Greece
| | - A Lekatou
- Medical Physics Laboratory, Medical School, National and Kapodistrian University of Athens, Greece
| | - E Pantelis
- Medical Physics Laboratory, Medical School, National and Kapodistrian University of Athens, Greece
| | - P Karaiskos
- Medical Physics Laboratory, Medical School, National and Kapodistrian University of Athens, Greece
| | - P Papagiannis
- Medical Physics Laboratory, Medical School, National and Kapodistrian University of Athens, Greece.
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Massillon-Jl G, Cabrera-Santiago A, Xicohténcatl-Hernández N. Relative efficiency of Gafchromic EBT3 and MD-V3 films exposed to low-energy photons and its influence on the energy dependence. Phys Med 2019; 61:8-17. [PMID: 31151584 DOI: 10.1016/j.ejmp.2019.04.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/17/2018] [Revised: 04/10/2019] [Accepted: 04/11/2019] [Indexed: 11/17/2022] Open
Abstract
Energy-dependence of Gafchromic films exposed to low-energy photons has been reported to be a function of absorbed-dose. However, these studies are based on a relative-response, R, which considers the absorbed-dose in water and not within the film sensitive-volume. This work investigated the relative-efficiency, REfilm, (ratio of absorbed-dose required to produce the same net optical density (netOD) by 60Co gamma and by x-ray) of Gafchromic EBT3 and MD-V3 films exposed to five x-ray beams from 20 kV to 160 kV and 60Co gamma rays. A factor that accounts for the energy-dependence, fx,Q,med, based on REfilm, phantom-material and depth at which the films are placed during irradiation was used to remove the influence of absorbed dose. Values of REfilm indicated that the absorbed dose from 60Co gamma rays needs to be 4 and 3 times larger than those from 20 kV x-rays to produce the same netOD within the EBT3 and MD-V3 sensitive volumes, respectively. Thus, saturation could help explain why Gafchromic films show under-response to very low doses from low-energy photon beams, regardless of film model. Furthermore, REfilm, was found to be nearly independent of netOD and colour-channels. Consequently, fx,Q,med is independent of the absorbed dose and colour-channels. In contrast, besides the variation with the photon energy, fx,Q,med varied with film model, depth and phantom material used during the irradiation. Thus, the results suggest that fx,Q,med is a more reliable wide-ranging parameter for evaluating the degree of energy-dependence of the film rather than the relative-response method commonly considered.
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Affiliation(s)
- Guerda Massillon-Jl
- Instituto de Física, Universidad Nacional Autónoma de México, 04510 Coyoacan, Mexico City, Mexico.
| | - Alexis Cabrera-Santiago
- Instituto de Física, Universidad Nacional Autónoma de México, 04510 Coyoacan, Mexico City, Mexico
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Marants R, Vandervoort E, Cygler JE. Evaluation of the 4D RADPOS dosimetry system for dose and position quality assurance of CyberKnife. Med Phys 2018; 45:4030-4044. [PMID: 30043980 DOI: 10.1002/mp.13102] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2018] [Revised: 07/09/2018] [Accepted: 07/10/2018] [Indexed: 02/28/2024] Open
Abstract
PURPOSE The Synchrony respiratory motion tracking of the CyberKnife system purports to provide real-time tumor motion compensation during robotic radiosurgery. Such a complex delivery system requires thorough quality assurance. In this work, RADPOS applicability as a dose and position quality assurance tool for CyberKnife treatments is assessed quantitatively for different phantom types and breathing motions, which increase in complexity to more closely resemble clinical situations. METHODS Two radiotherapy treatment experiments were performed where dose and position were measured with the RADPOS probe housed within a Solid Water phantom. For the first experiment, a Solid Water breast phantom was irradiated using isocentric beam delivery while stationary or moving sinusoidally in the anterior/posterior direction. For the second experiment, a phantom consisting of a Solid Water tumor in lung equivalent material was irradiated using isocentric and non-isocentric beam delivery while either stationary or moving. The phantom movement was either sinusoidal or based on a real patient's breathing waveform. For each experiment, RADPOS dose measurements were compared to EBT3 GafChromic film dose measurements and the CyberKnife treatment planning system's (TPS) Monte Carlo and ray-tracing dose calculation algorithms. RADPOS position measurements were compared to measurements made by the CyberKnife system and to the predicted breathing motion models used by the Synchrony respiratory motion compensation. RESULTS For the static and dynamic (i.e., sinusoidal motion) cases of the breast experiment, RADPOS, film and the TPS agreed at the 2.0% level within 1.1 σ of estimated combined uncertainties. RADPOS position measurements were in good agreement with LED and fiducial position measurements, where the average standard deviation (SD) of the differences between any two of the three position datasets was ≤0.5 mm for all directions. For the 10 mm peak to peak amplitude sinusoidal motion of the breast experiment, the average Synchrony correlation errors were ≤0.2 mm, indicative of an accurate predictive model. For all the cases of the lung experiment, RADPOS and film measurements agreed with each other at the 2.0% level within 1.5 σ of estimated experimental uncertainties provided that the measurements were corrected for imaging dose. The measured dose for RADPOS and film were 4.0% and 3.4% higher, respectively, than the TPS for the most complex dynamic cases (i.e., irregular motion) considered for the lung experiment. Assessment of the Synchrony correlation models by RADPOS showed that model accuracy declined as motion complexity increased; the SD of the differences between RADPOS and model position data measurements was ≤0.8 mm for sinusoidal motion but increased to ≤2.6 mm for irregular patient waveform motion. These results agreed with the Synchrony correlation errors reported by the CyberKnife system. CONCLUSIONS RADPOS is an accurate and precise QA tool for dose and position measurements for CyberKnife deliveries with respiratory motion compensation.
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Affiliation(s)
- Raanan Marants
- Department of Physics, Carleton University, Ottawa, ON, K1S 5B6, Canada
| | - Eric Vandervoort
- Department of Physics, Carleton University, Ottawa, ON, K1S 5B6, Canada
- Department of Medical Physics, The Ottawa Hospital Cancer Centre, Ottawa, ON, K1H 8L6, Canada
| | - Joanna E Cygler
- Department of Physics, Carleton University, Ottawa, ON, K1S 5B6, Canada
- Department of Medical Physics, The Ottawa Hospital Cancer Centre, Ottawa, ON, K1H 8L6, Canada
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Verification of high-dose-rate brachytherapy treatment planning dose distribution using liquid-filled ionization chamber array. J Contemp Brachytherapy 2018; 10:142-154. [PMID: 29789763 PMCID: PMC5961529 DOI: 10.5114/jcb.2018.75599] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2017] [Accepted: 03/23/2018] [Indexed: 11/23/2022] Open
Abstract
Purpose This study aims to investigate the dosimetric performance of a liquid-filled ionization chamber array in high-dose-rate (HDR) brachytherapy dosimetry. A comparative study was carried out with air-filled ionization chamber array and EBT3 Gafchromic films to demonstrate its suitability in brachytherapy. Material and methods The PTW OCTAVIUS detector 1000 SRS (IA 2.5-5 mm) is a liquid-filled ionization chamber array of area 11 x 11 cm2 and chamber spacing of 2.5-5 mm, whereas the PTW OCTAVIUS detector 729 (IA 10 mm) is an air vented ionization chamber array of area 27 x 27 cm2 and chamber spacing of 10 mm. EBT3 films were exposed to doses up to a maximum of 6 Gy and evaluated using multi-channel analysis. The detectors were evaluated using test plans to mimic a HDR intracavitary gynecological treatment. The plan was calculated and delivered with the applicator plane placed 20 mm from the detector plane. The acquired measurements were compared to the treatment plan. In addition to point dose measurement, profile/isodose, gamma analysis, and uncertainty analysis were performed. Detector sensitivity was evaluated by introducing simulated errors to the test plans. Results The mean point dose differences between measured and calculated plans were 0.2% ± 1.6%, 1.8% ± 1.0%, and 1.5% ± 0.81% for film, IA 10 mm, and IA 2.5-5 mm, respectively. The average percentage of passed gamma (global/local) values using 3%/3 mm criteria was above 99.8% for all three detectors on the original plan. For IA 2.5-5 mm, local gamma criteria of 2%/1 mm with a passing rate of at least 95% was found to be sensitive when simulated positional errors of 1 mm was introduced. Conclusion The dosimetric properties of IA 2.5-5 mm showed the applicability of liquid-filled ionization chamber array as a potential QA device for HDR brachytherapy treatment planning systems.
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León‐Marroquín EY, Lárraga‐Gutiérrez JM, Herrera‐González JA, Camacho‐López MA, Villarreal Barajas JE, García‐Garduño OA. Investigation of EBT3 radiochromic film's response to humidity. J Appl Clin Med Phys 2018; 19:283-290. [PMID: 29707904 PMCID: PMC5978557 DOI: 10.1002/acm2.12337] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2017] [Revised: 01/10/2018] [Accepted: 03/20/2018] [Indexed: 11/18/2022] Open
Abstract
PURPOSE The aim of this work is to investigate the effects of immersing EBT3 radiochromic film in water and to evaluate its contribution to the total uncertainty in dose determination. MATERIALS AND METHODS We used 3 cm × 3 cm EBT3 radiochromic films irradiated in the range of 0-70 Gy to study the impact of water immersion on the change in net optical density. These films were placed in a water container for a period of 24 h. The net optical density was measured before (0 h) and after of the immersion in water (1, 3, 6, 12, 18, and 24 h). The absorbance spectrum of the EBT3 radiochromic film was measured at 0 h and 24 h after immersion in water. The uncertainty in dose determination due to the effects of keeping the EBT3 radiochromic film submerged in water at 0, 1, and 24 h were recorded in the red, green, and blue channels. RESULTS We observed an increase in the net optical density as an effect on the film due to its immersion in water. The penetration of the water at the edges of the radiochromic film was observed to be a function of time during which the film remained in the water. On the other hand, the penetration of water at the edges of the film was found to be independent of irradiation dose. CONCLUSIONS EBT3 radiochromic film is found more resistant to water penetration through the edges than its predecessors. However, there is evidence that suggest that liquid water damage the Nylon cover layer of the film by changing its optical properties. Therefore, it is recommended to build a new calibration curve for radiochromic films for a specific situation involving dose measurements in liquid water.
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Affiliation(s)
- Elsa Y. León‐Marroquín
- Laboratorio de Fotomedicina, Biofotónica y Espectroscopia Láser de Pulsos Ultracortos, Facultad de MedicinaUniversidad Autónoma del Estado de MéxicoTolucaMéxico
| | - José M. Lárraga‐Gutiérrez
- Laboratorio de Física Médica & Unidad de RadiocirugíaInstituto Nacional de Neurología y NeurocirugíaMexico CityMéxico
| | - J. Alfredo Herrera‐González
- Laboratorio de Física Médica & Unidad de RadiocirugíaInstituto Nacional de Neurología y NeurocirugíaMexico CityMéxico
| | - Miguel A. Camacho‐López
- Laboratorio de Fotomedicina, Biofotónica y Espectroscopia Láser de Pulsos Ultracortos, Facultad de MedicinaUniversidad Autónoma del Estado de MéxicoTolucaMéxico
| | | | - Olivia A. García‐Garduño
- Laboratorio de Física Médica & Unidad de RadiocirugíaInstituto Nacional de Neurología y NeurocirugíaMexico CityMéxico
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Hermida-López M, Brualla L. Absorbed dose distributions from ophthalmic 106 Ru/ 106 Rh plaques measured in water with radiochromic film. Med Phys 2018; 45:1699-1707. [PMID: 29399810 DOI: 10.1002/mp.12777] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2017] [Revised: 12/19/2017] [Accepted: 01/06/2018] [Indexed: 11/08/2022] Open
Abstract
PURPOSE Brachytherapy with 106 Ru/106 Rh plaques offers good outcomes for small-to-medium choroidal melanomas and retinoblastomas. The dose measurement of the plaques is challenging, due to the small range of the emitted beta particles and steep dose gradients involved. The scarce publications on film dosimetry of 106 Ru/106 Rh plaques used solid phantoms. This work aims to develop a practical method for measuring the absorbed dose distribution in water produced by 106 Ru/106 Rh plaques using EBT3 radiochromic film. METHODS Experimental setups were developed to determine the dose distribution at a plane perpendicular to the symmetry axis of the plaque and at a plane containing the symmetry axis. One CCA and two CCX plaques were studied. The dose maps were obtained with the FilmQA Pro 2015 software, using the triple-channel dosimetry method. The measured dose distributions were compared to published Monte Carlo simulation and experimental data. RESULTS A good agreement was found between measurements and simulations, improving upon published data. Measured reference dose rates agreed within the experimental uncertainty with data obtained by the manufacturer using a scintillation detector, with typical differences below 5%. The attained experimental uncertainty was 4.1% (k = 1) for the perpendicular setup, and 7.9% (k = 1) for the parallel setup. These values are similar or smaller than those obtained by the manufacturer and other authors, without the need of solid phantoms that are not available to most users. CONCLUSIONS The proposed method may be useful to the users to perform quality assurance preclinical tests of 106 Ru/106 Rh plaques.
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Affiliation(s)
- Marcelino Hermida-López
- NCTeam, Strahlenklinik, Universitätsklinikum Essen, Essen, Germany.,Servei de Física i Protecció Radiològica, Hospital Universitari Vall d'Hebron, Institut de Recerca (VHIR), Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Lorenzo Brualla
- NCTeam, Strahlenklinik, Universitätsklinikum Essen, Essen, Germany
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13
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Hammer CG, Rosen BS, Fagerstrom JM, Culberson WS, DeWerd LA. Experimental investigation of GafChromic®
EBT3 intrinsic energy dependence with kilovoltage x rays, 137
Cs, and 60
Co. Med Phys 2017; 45:448-459. [DOI: 10.1002/mp.12682] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Revised: 10/13/2017] [Accepted: 11/07/2017] [Indexed: 11/10/2022] Open
Affiliation(s)
- Cliff G. Hammer
- Department of Medical Physics; School of Medicine and Public Health; University of Wisconsin-Madison; Madison WI 53705 USA
| | - Benjamin Saul Rosen
- Department of Radiation Oncology; University of Michigan; Ann Arbor MI 48109 USA
| | | | - Wesley S. Culberson
- Department of Medical Physics; School of Medicine and Public Health; University of Wisconsin-Madison; Madison WI 53705 USA
| | - Larry A. DeWerd
- Department of Medical Physics; School of Medicine and Public Health; University of Wisconsin-Madison; Madison WI 53705 USA
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14
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Mege JP, Wenzhao S, Veres A, Auzac G, Diallo I, Lefkopoulos D. Evaluation of MVCT imaging dose levels during helical IGRT: comparison between ion chamber, TLD, and EBT3 films. J Appl Clin Med Phys 2016; 17:143-157. [PMID: 26894346 PMCID: PMC5690206 DOI: 10.1120/jacmp.v17i1.5774] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2015] [Revised: 08/19/2015] [Accepted: 07/02/2015] [Indexed: 11/23/2022] Open
Abstract
The purpose of this investigation was to evaluate the dose on megavoltage CT (MVCT) images required for tomotherapy. As imaging possibilities are often used before each treatment and usually used several times before the session, we tried to evaluate the dose delivered during the procedure. For each scanning mode (fine, normal, and coarse), we first established the relative variation of these doses according to different technical parameters (explored length, patient setup). These dose variations measured with the TomoPhant, also known as Cheese phantom, showed the expected variations (due to the variation of scattered radiation) of 15% according to the explored length and ± 5% according to the phantom setup (due to the variation of the point of measurement in the bore). In order to estimate patient doses, an anthropomorphic phantom was used for thermoluminescent and film dosimetry. The degree of agreement between the two methods was very satisfactory (the differences correspond to 5 mGy per imaging session) for the three sites studied (head & neck, thorax, and abdomen). These measurements allowed us to estimate the delivered dose of between 1 cGy and 4 cGy according to the site and imaging mode. Finally, we attempted to investigate a way to calculate this delivered dose in our patients from the study conducted on a cylindrical phantom and by taking into account data from the initial kV-CT scan. The results we obtained were close to our measurements, with discrepancies below 5 mGy per MVCT.
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15
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Sipilä P, Ojala J, Kaijaluoto S, Jokelainen I, Kosunen A. Gafchromic EBT3 film dosimetry in electron beams - energy dependence and improved film read-out. J Appl Clin Med Phys 2016; 17:360-373. [PMID: 26894368 PMCID: PMC5690204 DOI: 10.1120/jacmp.v17i1.5970] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2015] [Revised: 10/14/2015] [Accepted: 09/27/2015] [Indexed: 11/23/2022] Open
Abstract
For megavoltage photon radiation, the fundamental dosimetry characteristics of Gafchromic EBT3 film were determined in 60Co gamma ray beam with addition of experimental and Monte Carlo (MC)-simulated energy dependence of the film for 6 MV photon beam and 6 MeV, 9 MeV, 12 MeV, and 16 MeV electron beams in water phantom. For the film read-out, two phase correction of scanner sensitivity was applied: a matrix correction for scanning area and dose-dependent correction by iterative procedure. With these corrections, the uniformity of response can be improved to be within ± 50 pixel values (PVs). To improve the read-out accuracy, a procedure with flipped film orientations was established. With the method, scanner uniformity can be improved further and dust particles, scratches and/or dirt on scan-ner glass can be detected and eliminated. Responses from red and green channels were averaged for read-out, which decreased the effect of noise present in values from separate channels. Since the signal level with the blue channel is considerably lower than with other channels, the signal variation due to different perturbation effects increases the noise level so that the blue channel is not recommended to be used for dose determination. However, the blue channel can be used for the detection of emulsion thickness variations for film quality evaluations with unexposed films. With electron beams ranging from 6 MeV to 16 MeV and at reference measurement conditions in water, the energy dependence of the EBT3 film is uniform within 0.5%, with uncertainties close to 1.6% (k = 2). Including 6 MV photon beam and the electron beams mentioned, the energy dependence is within 1.1%. No notable differences were found between the experimental and MC-simulated responses, indicating negligible change in intrinsic energy dependence of the EBT3 film for 6 MV photon beam and 6 MeV-16 MeV electron beams. Based on the dosimetric characteristics of the EBT3 film, the read-out procedure established, the nearly uniform energy dependence found and the estimated uncertainties, the EBT3 film was concluded to be a suitable 2D dosimeter for measuring electron or mixed photon/electron dose distributions in water phantom. Uncertainties of 3.7% (k = 2) for absolute and 2.3% (k = 2) for relative dose were estimated.
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16
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Marrazzo L, Zani M, Pallotta S, Arilli C, Casati M, Compagnucci A, Talamonti C, Bucciolini M. GafChromic(®) EBT3 films for patient specific IMRT QA using a multichannel approach. Phys Med 2015; 31:1035-1042. [PMID: 26429383 DOI: 10.1016/j.ejmp.2015.08.010] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/10/2015] [Revised: 07/28/2015] [Accepted: 08/22/2015] [Indexed: 10/23/2022] Open
Abstract
PURPOSE To evaluate EBT3 for pre-treatment patient specific quality assurance (QA). The method we propose combines the experience gained in our center with the guidelines of the protocol proposed by Lewis et al. in 2012. To compare the multichannel approach with the single channel dosimetry. METHODS Gafchromic® EBT3 films were irradiated both at linac and TomoTherapy and calibration curves were obtained. A series of irradiations with simple fields (uniform dose distributions on regular shaped targets) was performed. In a second stage, films were exposed to full clinical plans at linac (step and shoot IMRT and VMAT). At TomoTherapy dose maps were obtained for a clinical plan in three different coronal planes. Films were digitized using an Epson 10000XL scanner and FilmQA™ Pro software was employed for the analysis. RESULTS The measured calibration curves suggest that, at least for the two beams taken into account (6 MV linac and TomoTherapy), a single calibration can be successfully adopted for each film lot. The application of the multichannel optimization method strongly improves the results in terms of gamma passing rates of the comparison between measured and calculated maps. CONCLUSIONS Up to now EBT films, although attractive, were not preferred for routine patient specific QA due to their complex and time consuming processing and to the challenging work of characterization. The application of the mentioned protocol, together with some additional precautions, and the adoption of the multichannel optimization dosimetry, make this detector a handy and reliable tool for patient specific QA.
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Affiliation(s)
- Livia Marrazzo
- Medical Physics Unit, Azienda Ospedaliero Universitaria Careggi, Florence, Italy.
| | - Margherita Zani
- Dipartimento di Scienze Biomediche, Sperimentali e Cliniche, Università degli Studi di Firenze, Florence, Italy
| | - Stefania Pallotta
- Medical Physics Unit, Azienda Ospedaliero Universitaria Careggi, Florence, Italy; Dipartimento di Scienze Biomediche, Sperimentali e Cliniche, Università degli Studi di Firenze, Florence, Italy
| | - Chiara Arilli
- Medical Physics Unit, Azienda Ospedaliero Universitaria Careggi, Florence, Italy
| | - Marta Casati
- Medical Physics Unit, Azienda Ospedaliero Universitaria Careggi, Florence, Italy
| | | | - Cinzia Talamonti
- Medical Physics Unit, Azienda Ospedaliero Universitaria Careggi, Florence, Italy; Dipartimento di Scienze Biomediche, Sperimentali e Cliniche, Università degli Studi di Firenze, Florence, Italy
| | - Marta Bucciolini
- Medical Physics Unit, Azienda Ospedaliero Universitaria Careggi, Florence, Italy; Dipartimento di Scienze Biomediche, Sperimentali e Cliniche, Università degli Studi di Firenze, Florence, Italy
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Bräuer-Krisch E, Adam JF, Alagoz E, Bartzsch S, Crosbie J, DeWagter C, Dipuglia A, Donzelli M, Doran S, Fournier P, Kalef-Ezra J, Kock A, Lerch M, McErlean C, Oelfke U, Olko P, Petasecca M, Povoli M, Rosenfeld A, Siegbahn EA, Sporea D, Stugu B. Medical physics aspects of the synchrotron radiation therapies: Microbeam radiation therapy (MRT) and synchrotron stereotactic radiotherapy (SSRT). Phys Med 2015; 31:568-83. [PMID: 26043881 DOI: 10.1016/j.ejmp.2015.04.016] [Citation(s) in RCA: 75] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Revised: 04/27/2015] [Accepted: 04/28/2015] [Indexed: 11/19/2022] Open
Abstract
Stereotactic Synchrotron Radiotherapy (SSRT) and Microbeam Radiation Therapy (MRT) are both novel approaches to treat brain tumor and potentially other tumors using synchrotron radiation. Although the techniques differ by their principles, SSRT and MRT share certain common aspects with the possibility of combining their advantages in the future. For MRT, the technique uses highly collimated, quasi-parallel arrays of X-ray microbeams between 50 and 600 keV. Important features of highly brilliant Synchrotron sources are a very small beam divergence and an extremely high dose rate. The minimal beam divergence allows the insertion of so called Multi Slit Collimators (MSC) to produce spatially fractionated beams of typically ∼25-75 micron-wide microplanar beams separated by wider (100-400 microns center-to-center(ctc)) spaces with a very sharp penumbra. Peak entrance doses of several hundreds of Gy are extremely well tolerated by normal tissues and at the same time provide a higher therapeutic index for various tumor models in rodents. The hypothesis of a selective radio-vulnerability of the tumor vasculature versus normal blood vessels by MRT was recently more solidified. SSRT (Synchrotron Stereotactic Radiotherapy) is based on a local drug uptake of high-Z elements in tumors followed by stereotactic irradiation with 80 keV photons to enhance the dose deposition only within the tumor. With SSRT already in its clinical trial stage at the ESRF, most medical physics problems are already solved and the implemented solutions are briefly described, while the medical physics aspects in MRT will be discussed in more detail in this paper.
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Affiliation(s)
- Elke Bräuer-Krisch
- ESRF-The European Synchrotron, 71, Avenue des Martyrs, Grenoble, France.
| | | | - Enver Alagoz
- University of Bergen Department of Physics and Technology, PB 7803 5020, Norway
| | - Stefan Bartzsch
- The Institute of Cancer Research, 15 Cotswold Rd, Sutton SM2 5NG, United Kingdom
| | - Jeff Crosbie
- RMIT University, Melbourne, VIC, 3001, Australia
| | | | - Andrew Dipuglia
- Centre for Medical Radiation Physics, University of Wollongong, Northfields Ave, NSW, Australia
| | - Mattia Donzelli
- ESRF-The European Synchrotron, 71, Avenue des Martyrs, Grenoble, France
| | - Simon Doran
- CRUK Cancer Imaging Centre, Institute of Cancer Research, 15 Cotswold Rd, Sutton Surrey, UK
| | - Pauline Fournier
- ESRF-The European Synchrotron, 71, Avenue des Martyrs, Grenoble, France; Centre for Medical Radiation Physics, University of Wollongong, Northfields Ave, NSW, Australia
| | - John Kalef-Ezra
- Medical Physics Laboratory, University of Ioannina, 451.10, Ioannina, Greece
| | - Angela Kock
- Sintef Minalab, Gaustadalléen 23C, 0373, Oslo, Norway
| | - Michael Lerch
- Centre for Medical Radiation Physics, University of Wollongong, Northfields Ave, NSW, Australia
| | - Ciara McErlean
- CRUK Cancer Imaging Centre, Institute of Cancer Research, 15 Cotswold Rd, Sutton Surrey, UK
| | - Uwe Oelfke
- The Institute of Cancer Research, 15 Cotswold Rd, Sutton SM2 5NG, United Kingdom
| | - Pawel Olko
- Institute of Nuclear Physics PAN, Radzikowskiego 152, 31-342, Krawkow, Poland
| | - Marco Petasecca
- Centre for Medical Radiation Physics, University of Wollongong, Northfields Ave, NSW, Australia
| | - Marco Povoli
- University of Oslo, Department of Physics, 0316, Oslo, Norway
| | - Anatoly Rosenfeld
- Centre for Medical Radiation Physics, University of Wollongong, Northfields Ave, NSW, Australia
| | - Erik A Siegbahn
- Department of Oncolgy-Pathology, Karolinska Institutet, S-177176, Stockholm, Sweden
| | - Dan Sporea
- National Institute for Laser, Plasma and Radiation Physics, Magurele, RO-077125, Romania
| | - Bjarne Stugu
- University of Bergen, Department of Physics and Technology, PB 7803, 5020, Bergen, Norway
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