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Steciw S, Fallone BG, Yip E. Dose perturbations at tissue interfaces during parallel linac-MR treatments: The "Lateral Scatter Electron Return Effect" (LS-ERE). Med Phys 2024. [PMID: 39153227 DOI: 10.1002/mp.17363] [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: 04/15/2024] [Revised: 08/05/2024] [Accepted: 08/06/2024] [Indexed: 08/19/2024] Open
Abstract
BACKGROUND Magnetic resonance (MR) imaging devices have been integrated with medical linear accelerators (linac) in radiation therapy. Both perpendicular linac-MR (LMR-B⊥) and parallel (LMR-B∥) systems exist, where due to the MR's magnetic field dose can be perturbed in the patient. Dose perturbations from the electron return effect (ERE) and electron streaming effects (ESEs) are present in LMR-B⊥ systems, where a dose collimating effect has been observed in LMR-B∥ systems . PURPOSE To report on an asymmetric dose perturbation which is present at the interface between two different materials during treatment in parallel linac-MR (LMR-B∥) systems. To the best of our knowledge, these asymmetric dose effects, "Lateral Scattered Electron Return Effect" (LS-ERE) have not been previously reported. METHODS BEAMnrc and EGSnrc Monte Carlo (MC) radiation transport codes were used with the EEMF macro to emulate a 6 FFF beam from the 0.5-T Alberta linac-MR (LMR). Simulations were performed at 0.5 and 1.5 T in several different phantom material-interface combinations and field sizes including from modulated MLC-like fields. MC simulations quantified LS-ERE in patient CT datasets for the head, breast, and lung. LS-ERE cancellation techniques were investigated. LS-ERE asymmetries were quantified by subtracting an antiparallel dose from the parallel dose, dividing by two and normalizing to the global 0-T maximum dose. GafChromic film measurements were made in the 0.5-T Alberta LMR-B∥ system using solid water at the water-air interface to validate MC simulations. ERE was simulated for an emulated LMR-B⊥ system and compared to LMR-B∥ dose perturbations. RESULTS LS-ERE is mostly independent of field size for fields >1 × 1 cm2. For 5 × 5-cm2 fields at 0.5T/1.5T, LS-ERE asymmetries are ≤±6.9%/6.9% at bone-air and ≤±9.0%/7.0% at tissue-air for nonair doses, and ≤±4.1%/5.5% at tissue-lung interfaces. LS-ERE increases as the density gradient increases, where the magnitude and extent of LS-ERE are reduced as field strength increases. For a single 5 × 5-cm2 field at 0.5T/1.5T, the LS-ERE asymmetry is ≤±10.2%/8.5% at the tissue-air sinus interface for head, ≤±4.2%/5.3% at the spine-lung interface for the lung, and ≤±5.7%/4.9% at the skin-air interface for a breast tangent plan at 0.5T/1.5T. POP fields mostly remove LS-ERE asymmetries, with magnetic field reversal during treatment being the most effective method. Skin dose was investigated and compared to 0-T treatments for 0.5T/1.5T LMR-B∥ single field breast and head treatments. Including all dosimetric magnetic field perturbations, a 21%/24% and 22%/22% increase in skin dose to head and breast, respectively, was observed, of which LS-ERE is responsible for approximately 30% of the total. Measured LS-ERE asymmetries and dose enhancements at the water-air interface using GafChromic film were in excellent agreement with MC simulations. ERE in 1.5-T LMR-B⊥ systems are on average 5.5 times larger than total dose perturbations at 0.5 T in LMR-B∥ systems. CONCLUSION LS-ERE is present at the interface between materials and awareness of LS-ERE is crucial for proper TPS evaluation for LMR-B∥ treatments, especially in areas where large tissue density gradients exist.
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Affiliation(s)
- Stephen Steciw
- Medical Physics Division, Department of Oncology, University of Alberta, Edmonton, Alberta, Canada
- Department of Medical Physics, Cross Cancer Institute, Edmonton, Alberta, Canada
| | - Biagio G Fallone
- Medical Physics Division, Department of Oncology, University of Alberta, Edmonton, Alberta, Canada
- Department of Medical Physics, Cross Cancer Institute, Edmonton, Alberta, Canada
| | - Eugene Yip
- Medical Physics Division, Department of Oncology, University of Alberta, Edmonton, Alberta, Canada
- Department of Medical Physics, Cross Cancer Institute, Edmonton, Alberta, Canada
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Oliver PAK, Yip E, Tari SY, Wachowicz K, Reynolds M, Burke B, Warkentin B, Fallone BG. Skin dose investigations on a 0.5 T parallel rotating biplanar linac-MR using Monte Carlo simulations and measurements. Med Phys 2024. [PMID: 38873942 DOI: 10.1002/mp.17246] [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: 01/25/2024] [Revised: 05/06/2024] [Accepted: 05/30/2024] [Indexed: 06/15/2024] Open
Abstract
BACKGROUND The Alberta rotating biplanar linac-MR has a 0.5 T magnetic field parallel to the beamline. When developing a new linac-MR system, interactions of charged particles with the magnetic field necessitate careful consideration of skin dose and tissue interface effects. PURPOSE To investigate the effect of the magnetic field on skin dose using measurements and Monte Carlo (MC) simulations. METHODS We develop an MC model of our linac-MR, which we validate by comparison with ion chamber measurements in a water tank. Additionally, MC simulation results are compared with radiochromic film surface dose measurements on solid water. Variations in surface dose as a function of field size are measured using a parallel plate ion chamber in solid water. Using an anthropomorphic computational phantom with a 2 mm-thick skin layer, we investigate dose distributions resulting from three beam arrangements. Magnetic field on and off scenarios are considered for all measurements and simulations. RESULTS For a 20 × 20 cm2 field size,D 0.2 c c ${D_{0.2cc}}$ (the minimum dose to the hottest contiguous 0.2 cc volume) for the top 2 mm of a simple water phantom is 72% when the magnetic field is on, compared to 34% with magnetic field off (values are normalized to the central axis dose maximum). Parallel plate ion chamber measurements demonstrate that the relative increase in surface dose due to the magnetic field decreases with increasing field size. For the anthropomorphic phantom,D ∼ 0.2 c c ${D_{ \sim 0.2cc}}$ (minimum skin dose in the hottest 1 × 1 × 1 cm3 cube) shows relative increases of 20%-28% when the magnetic field is on compared to when it is off. With magnetic field off, skinD ∼ 0.2 c c ${D_{ \sim 0.2cc}}$ is 71%, 56%, and 21% for medial-lateral tangents, anterior-posterior beams, and a five-field arrangement, respectively. For magnetic field on, the corresponding skinD ∼ 0.2 c c ${D_{ \sim 0.2cc}}$ values are 91%, 67%, and 25%. CONCLUSIONS Using a validated MC model of our linac-MR, surface doses are calculated in various scenarios. MC-calculated skin dose varies depending on field sizes, obliquity, and the number of beams. In general, the parallel linac-MR arrangement results in skin dose enhancement due to charged particles spiraling along magnetic field lines, which impedes lateral motion away from the central axis. Nonetheless, considering the results presented herein, treatment plans can be designed to minimize skin dose by, for example, avoiding oblique beams and using a larger number of fields.
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Affiliation(s)
- Patricia A K Oliver
- Dept. of Medical Physics, Cross Cancer Institute, Edmonton, Alberta, Canada
- Dept. of Oncology, Medical Physics Division, University of Alberta, Edmonton, Alberta, Canada
- Dept. of Medical Physics, Nova Scotia Health and Dept. of Radiation Oncology, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Eugene Yip
- Dept. of Medical Physics, Cross Cancer Institute, Edmonton, Alberta, Canada
- Dept. of Oncology, Medical Physics Division, University of Alberta, Edmonton, Alberta, Canada
| | - Shima Y Tari
- Dept. of Medical Physics, Cross Cancer Institute, Edmonton, Alberta, Canada
- Dept. of Oncology, Medical Physics Division, University of Alberta, Edmonton, Alberta, Canada
| | - Keith Wachowicz
- Dept. of Medical Physics, Cross Cancer Institute, Edmonton, Alberta, Canada
- Dept. of Oncology, Medical Physics Division, University of Alberta, Edmonton, Alberta, Canada
| | - Michael Reynolds
- Dept. of Medical Physics, Cross Cancer Institute, Edmonton, Alberta, Canada
| | - Ben Burke
- Dept. of Medical Physics, Cross Cancer Institute, Edmonton, Alberta, Canada
- Dept. of Oncology, Medical Physics Division, University of Alberta, Edmonton, Alberta, Canada
| | - Brad Warkentin
- Dept. of Medical Physics, Cross Cancer Institute, Edmonton, Alberta, Canada
- Dept. of Oncology, Medical Physics Division, University of Alberta, Edmonton, Alberta, Canada
| | - Biagio G Fallone
- Dept. of Medical Physics, Cross Cancer Institute, Edmonton, Alberta, Canada
- Dept. of Oncology, Medical Physics Division, University of Alberta, Edmonton, Alberta, Canada
- MagnetTx Oncology Solutions, Edmonton, Alberta, Canada
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Kaiyum R, Schruder CW, Mermut O, Rink A. Investigation of cyanine-based infrared dyes as calibrants in radiochromic films. Med Phys 2023; 50:8034-8043. [PMID: 37633840 DOI: 10.1002/mp.16674] [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: 05/01/2023] [Revised: 07/03/2023] [Accepted: 07/29/2023] [Indexed: 08/28/2023] Open
Abstract
BACKGROUND Radiochromic material such as lithium pentacosa-10,12-diynoate (LiPCDA) has been suggested as the radiation-sensitive material for real-time in vivo fiber-optic dosimetry. In this configuration, micron-thick radiochromic coating would measure the absorbed dose, where a major challenge is the uncertainty in the active material thickness, necessitating calibration. A homogeneously incorporated inert infrared (IR) dye, which must also be stable in ambient conditions and against radiolysis, can be added to the radiochromic film to enable optical calibration. PURPOSE This study investigates four commercial cyanine-based dyes (IR-783, IR-806, IR-868, and IR-880) for use as an optical calibrant in fiber-optic radiochromic dosimeters. METHODS All dyes were dissolved in water to confirm solubility. IR-783 and IR-806 were dissolved in 10% w/w gelatin solution and coated onto a polyester substrate, which were then sandwiched between two layers of adhesives forming IR-783 and IR-806 films. A second batch of IR dyes in gelatin incorporated the LiPCDA, and was coated onto substrate and sandwiched between adhesive to form IR dye + LiPCDA films. The absorbance spectra of the films were measured periodically (176 and 102 days for IR-dye films, and IR dye + LiPCDA, respectively). The average percentage absorbance, normalized to day 1, was fit to either a single or a double exponential decay model to calculate the spectral stability lifetime (τ1 , τ2 ). Films were irradiated using a 6 MV LINAC beam with a standard setup of 100 source to axis distance (SAD), 10 cm × 10 cm field size and 1.5 cm depth. The change in absorbance of the IR-dye + LiPCDA films were measured after they were irradiated to 1, 2, 5, 10, and 20 Gy at 3 Gy/min. RESULTS Only IR-783 and IR-806 were sufficiently water soluble. In gelatin matrix, these dyes demonstrated a decrease in absorbance with time for IR-783 and IR-806 dyes, with IR-783 films having an average τ1 = 73 ± 7 days and IR-806 films τ1 = 7 ± 3 days. When combined with LiPCDA, IR-806 degraded, losing its original peak at ∼820 nm. Similarly, IR-783, combined with LiPCDA, showed signs of degradation; however, its original absorbance peak was still observed at ∼800 nm. In the IR-783 + LiPCDA films, the IR-783 dye had a τ = 4 ± 1 days, an order of magnitude faster than the IR-783 with no LiPCDA films. When exposed to x-ray irradiation, the IR-783 dye in the IR-783 + LiPCDA films showed no change in absorbance with increasing absorbed dose. In contrast, the LiPCDA in the films responded as expected, increasing in optical density with increased absorbed dose. CONCLUSIONS IR-783 and IR-806 dyes were observed to degrade over time following exponential decay curves. IR-806 could not be combined with the LiPCDA without degrading. The combination of IR-783 with LiPCDA demonstrated single exponential decay behavior at a comparatively faster rate than films that did not have LiPCDA. IR-783 was insensitive to ionizing radiation and thus may be suitable for thickness correction, but an alternative manufacturing procedure may need to be developed.
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Affiliation(s)
- Rohith Kaiyum
- Department of Physics and Astronomy, York University, Toronto, Canada
- TECHNA Institute, University Health Network, Toronto, Canada
| | - Christopher W Schruder
- Department of Physics and Astronomy, York University, Toronto, Canada
- TECHNA Institute, University Health Network, Toronto, Canada
| | - Ozzy Mermut
- Department of Physics and Astronomy, York University, Toronto, Canada
| | - Alexandra Rink
- Department of Medical Physics, Princess Margaret Cancer Centre, Toronto, Canada
- Department of Radiation Oncology, University of Toronto, Toronto, Canada
- Department of Medical Biophysics, University of Toronto, Toronto, Canada
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Liu K, Jorge PG, Tailor R, Moeckli R, Schüler E. Comprehensive evaluation and new recommendations in the use of Gafchromic EBT3 film. Med Phys 2023; 50:7252-7262. [PMID: 37403570 PMCID: PMC10766858 DOI: 10.1002/mp.16593] [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: 09/14/2022] [Revised: 06/06/2023] [Accepted: 06/11/2023] [Indexed: 07/06/2023] Open
Abstract
BACKGROUND Gafchromic film's unique properties of tissue-equivalence, dose-rate independence, and high spatial resolution make it an attractive choice for many dosimetric applications. However, complicated calibration processes and film handling limits its routine use. PURPOSE We evaluated the performance of Gafchromic EBT3 film after irradiation under a variety of measurement conditions to identify aspects of film handling and analysis for simplified but robust film dosimetry. METHODS The short- (from 5 min to 100 h) and long-term (months) film response was evaluated for clinically relevant doses of up to 50 Gy for accuracy in dose determination and relative dose distributions. The dependence of film response on film-read delay, film batch, scanner type, and beam energy was determined. RESULTS Scanning the film within a 4-h window and using a standard 24-h calibration curve introduced a maximum error of 2% over a dose range of 1-40 Gy, with lower doses showing higher uncertainty in dose determination. Relative dose measurements demonstrated <1 mm difference in electron beam parameters such as depth of 50% of the maximum dose value (R50 ), independent of when the film was scanned after irradiation or the type of calibration curve used (batch-specific or time-specific calibration curve) if the same default scanner was used. Analysis of films exposed over a 5-year period showed that using the red channel led to the lowest variation in the measured net optical density values for different film batches, with doses >10 Gy having the lowest coefficient of variation (<1.7%). Using scanners of similar design produced netOD values within 3% after exposure to doses of 1-40 Gy. CONCLUSIONS This is the first comprehensive evaluation of the temporal and batch dependence of Gafchromic EBT3 film evaluated on consolidated data over 8 years. The relative dosimetric measurements were insensitive to the type of calibration applied (batch- or time-specific) and in-depth time-dependent dosimetric signal behaviors can be established for film scanned outside of the recommended 16-24 h post-irradiation window. We generated guidelines based on our findings to simplify film handling and analysis and provide tabulated dose- and time-dependent correction factors to achieve this without reducing the accuracy of dose determination.
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Affiliation(s)
- Kevin Liu
- Division of Radiation Oncology, Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
- Graduate School of Biomedical Sciences, The University of Texas, Houston, Texas, USA
| | - Patrik Gonçalves Jorge
- Institute of Radiation Physics, Lausanne University Hospital and Lausanne University, Lausanne, Switzerland
| | - Ramesh Tailor
- Division of Radiation Oncology, Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
- Graduate School of Biomedical Sciences, The University of Texas, Houston, Texas, USA
| | - Raphaël Moeckli
- Institute of Radiation Physics, Lausanne University Hospital and Lausanne University, Lausanne, Switzerland
| | - Emil Schüler
- Division of Radiation Oncology, Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
- Graduate School of Biomedical Sciences, The University of Texas, Houston, Texas, USA
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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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Trivedi G, Singh PP, Oinam AS. Comparison of single catheter versus dual catheter-based EBT3 film calibration for the Ir-192 beam energy. Biomed Phys Eng Express 2023; 9. [PMID: 36796085 DOI: 10.1088/2057-1976/acbc80] [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: 09/16/2022] [Accepted: 02/16/2023] [Indexed: 02/18/2023]
Abstract
Purpose. Films and TLDs have been the common choices for passivein-vivodose measurement in radiotherapy. In the brachytherapy applications, it is very difficult to report and verify the dose at multiple localized high dose gradient regions and also the dose to organ at risk. This study was carried out to introduce a new and accurate calibration method for GafChromic EBT3 films irradiated using Ir-192 photon energy from miniature High Dose Rate (HDR) Brachytherapy source.Materials and methods. Film holder made of Styrofoam was used to hold the EBT3 film at its center. It was placed inside the mini water phantom and the films were irradiated by Ir-192 source of microSelectron HDR afterloading brachytherapy system. Two different setups: Single catheter-based film exposure and dual catheter-based film exposure were compared. The films scanned on a flatbed scanner were analysed in three different color channels: red, green, and blue using Image J software. The dose calibration graphs were generated using the third-order polynomial equations fitted on the data points from two different methods of calibration procedure. Maximum and mean dose difference between TPS calculated and measured was analyzed.Results. The measured dose difference from the TPS calculated doses were evaluated for the three groups of dose ranges (low, medium and high). In the high dose range, standard uncertainty of dose difference are ±2.3%, ±2.9%, and ±2.4% respectively for the red, green, and blue color channel when the TPS calculated dose was compared with single catheter based film calibration equation. Whereas it is observed as 1.3%, 1.4% and 3.1% for the red, green, and blue color channels respectively when compared with the dual catheter based film calibration equation. A test film was exposed to a TPS calculated dose of 666 cGy to validate the calibration equations, single catheter based film calibration equation estimated the dose difference as -9.2%, -7.8% and -3.6% respectively in the red, green, and blue color channels whereas the same were observed as 0.1%, 0.2% and 6.1% respectively when dual catheter based film calibration equation was applied.Conclusion.Source miniature size, reproducible positioning of the film and catheter system inside water medium are the major challenges in the film calibration with Ir-192 beam. To overcome these situations dual catheter-based film calibration was found more accurate and reproducible as compare to the single catheter based film calibration.
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Affiliation(s)
- Gaurav Trivedi
- Post Graduate Institute of Medical Education and Research, India.,Indian Institute of Technology, Ropar, India
| | | | - Arun S Oinam
- Post Graduate Institute of Medical Education and Research, India
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Yan H, De Jean P, Grafil E, Ashraf R, Niedermayr T, Astrahan M, Mruthyunjaya P, Beadle B, Xing L, Liu W. Radio-luminescent imaging for rapid, high-resolution eye plaque loading verification. Med Phys 2023; 50:142-151. [PMID: 36183146 DOI: 10.1002/mp.16003] [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: 06/25/2022] [Revised: 08/25/2022] [Accepted: 09/16/2022] [Indexed: 01/25/2023] Open
Abstract
BACKGROUND Eye plaque brachytherapy is currently an optimal therapy for intraocular cancers. Due to the lack of an effective and practical technique to measure the seed radioactivity distribution, current quality assurance (QA) practice according to the American Association of Physicists in Medicine TG129 only stipulates that the plaque assembly be visually inspected. Consequently, uniform seed activity is routinely adopted to avoid possible loading mistakes of differential seed loading. However, modulated dose delivery, which represents a general trend in radiotherapy to provide more personalized treatment for a given tumor and patient, requires differential activities in the loaded seeds. PURPOSE In this study, a fast and low-cost radio-luminescent imaging and dose calculating system to verify the seed activity distribution for differential loading was developed. METHODS A proof-of-concept system consisting of a thin scintillator sheet coupled to a camera/lens system was constructed. A seed-loaded plaque can be placed directly on the scintillator surface with the radioactive seeds facing the scintillator. The camera system collects the radioluminescent signal generated by the scintillator on its opposite side. The predicted dose distribution in the scintillator's sensitive layer was calculated using a Monte Carlo simulation with the planned plaque loading pattern of I-125 seeds. Quantitative comparisons of the distribution of relative measured signal intensity and that of the relative predicted dose in the sensitive layer were performed by gamma analysis, similar to intensity-modulated radiation therapy QA. RESULTS Data analyses showed high gamma (3%/0.3 mm, global, 20% threshold) passing rates for correct seed loadings and low passing rates with distinguished high gamma value area for incorrect loadings, indicating that possible errors may be detected. The measurement and analysis only required a few extra minutes, significantly shorter than the time to assay the extra verification seeds the physicist already must perform as recommended by TG129. CONCLUSIONS Radio-luminescent QA can be used to facilitate and assure the implementation of intensity-modulated, customized plaque loading.
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Affiliation(s)
- Huagang Yan
- School of Biomedical Engineering, Capital Medical University, Beijing, China
| | - Paul De Jean
- Luca Medical Systems Inc., Palo Alto, California, USA
| | - Elliot Grafil
- Luca Medical Systems Inc., Palo Alto, California, USA
| | - Ramish Ashraf
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California, USA
| | - Thomas Niedermayr
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California, USA
| | | | - Prithvi Mruthyunjaya
- Department of Ophthalmology, Stanford University School of Medicine, Stanford, California, USA
| | - Beth Beadle
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California, USA
| | - Lei Xing
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California, USA
| | - Wu Liu
- Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California, USA
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Personalized Superficial HDR Brachytherapy—Dosimetric Verification of Dose Distribution with Lead Shielding of Critical Organs in the Head and Neck Region. J Pers Med 2022; 12:jpm12091432. [PMID: 36143217 PMCID: PMC9504935 DOI: 10.3390/jpm12091432] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Revised: 08/27/2022] [Accepted: 08/30/2022] [Indexed: 11/21/2022] Open
Abstract
Background: Surface brachytherapy, usually characterized by a high dose gradient, allows the dose to be precisely deposited in the irradiated area while protecting critical organs. When the lesion is located in the nasal or ocular region, the organ of vision must be protected. The aim of this study was to verify the dose distributions near critical organs in the head and neck region during a brachytherapy procedure using lead shielding of the eye. Methods: Anthropomorphic phantom using 3D-printing technology was prepared. The doses deposited at a point in the lens of the eye and on the surface of the eyelid, directly under the lead shield were calculated and measured using EBT3 radiochromic films. Comparison of doses planned in the treatment planning system using the TG-43 formalism, TG-186 formalism, and measured were also performed. Results: Comparing the planned and calculated doses with TG186 formalism it can be assumed that the use of lead shields is a method for protecting the organ of vision from the adverse effects of ionizing radiation. Conclusions: The decision to use a lead shield during facial surface brachytherapy procedures should be made on a patient-by-patient basis and based on model-based calculation methods recommended by TG186.
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Biglin ER, Aitkenhead AH, Price GJ, Chadwick AL, Santina E, Williams KJ, Kirkby KJ. A preclinical radiotherapy dosimetry audit using a realistic 3D printed murine phantom. Sci Rep 2022; 12:6826. [PMID: 35474242 PMCID: PMC9042835 DOI: 10.1038/s41598-022-10895-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Accepted: 04/05/2022] [Indexed: 11/08/2022] Open
Abstract
Preclinical radiation research lacks standardized dosimetry procedures that provide traceability to a primary standard. Consequently, ensuring accuracy and reproducibility between studies is challenging. Using 3D printed murine phantoms we undertook a dosimetry audit of Xstrahl Small Animal Radiation Research Platforms (SARRPs) installed at 7 UK centres. The geometrically realistic phantom accommodated alanine pellets and Gafchromic EBT3 film for simultaneous measurement of the dose delivered and the dose distribution within a 2D plane, respectively. Two irradiation scenarios were developed: (1) a 10 × 10 mm2 static field targeting the pelvis, and (2) a 5 × 5 mm2 90° arc targeting the brain. For static fields, the absolute difference between the planned dose and alanine measurement across all centres was 4.1 ± 4.3% (mean ± standard deviation), with an overall range of - 2.3 to 10.5%. For arc fields, the difference was - 1.2% ± 6.1%, with a range of - 13.1 to 7.7%. EBT3 dose measurements were greater than alanine by 2.0 ± 2.5% and 3.5 ± 6.0% (mean ± standard deviation) for the static and arc fields, respectively. 2D dose distributions showed discrepancies to the planned dose at the field edges. The audit demonstrates that further work on preclinical radiotherapy quality assurance processes is merited.
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Affiliation(s)
- Emma R Biglin
- Division of Cancer Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, 3rd floor Proton Beam Therapy Centre, Oak Road, Manchester, M20 4BX, UK.
| | - Adam H Aitkenhead
- Division of Cancer Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, 3rd floor Proton Beam Therapy Centre, Oak Road, Manchester, M20 4BX, UK
- Christie Medical Physics and Engineering, The Christie NHS Foundation Trust, Manchester, UK
| | - Gareth J Price
- Division of Cancer Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, 3rd floor Proton Beam Therapy Centre, Oak Road, Manchester, M20 4BX, UK
- The Christie NHS Foundation Trust, Manchester, UK
| | - Amy L Chadwick
- Division of Cancer Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, 3rd floor Proton Beam Therapy Centre, Oak Road, Manchester, M20 4BX, UK
- The Christie NHS Foundation Trust, Manchester, UK
| | - Elham Santina
- Division of Cancer Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, 3rd floor Proton Beam Therapy Centre, Oak Road, Manchester, M20 4BX, UK
- The Christie NHS Foundation Trust, Manchester, UK
| | - Kaye J Williams
- Division of Pharmacy and Optometry, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK
| | - Karen J Kirkby
- Division of Cancer Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, 3rd floor Proton Beam Therapy Centre, Oak Road, Manchester, M20 4BX, UK
- The Christie NHS Foundation Trust, Manchester, UK
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10
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Abu Mhanna HY, Omar AF, Radzi YM, Akhdar HF, Al Ewaidat H. Expired EBT3 Films’ Sensitivity for the Measurement of X-ray and UV Radiation: An Optical Analysis. MATERIALS 2022; 15:ma15082903. [PMID: 35454597 PMCID: PMC9027090 DOI: 10.3390/ma15082903] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Revised: 03/15/2022] [Accepted: 04/13/2022] [Indexed: 11/25/2022]
Abstract
The aim of this study is to compare the optical responses of external beam therapy 3 (EBT3) films exposed to X-rays and solar ultraviolet rays (SUV-rays), as a dose control technique in the clinical sector for various radiation types, energies, and absorbed doses up to 4 Gy. In this study, EBT3 films with three different expiry dates were prepared and cut into pieces of size 2 by 2 cm2. The first group was exposed to 90 kVp X-rays, while the second group was exposed to the SUV-rays at noon. The analysis was performed using a visible Jaz spectrometer and an EPSON Perfection V370 Photo scanner to obtain the absorbance, the net reflective optical density (ROD) and the red-green-blue (RGB) values of the samples. The results have shown that spectroscopic measurements of the exposed expired EBT3 films with these radiation sources are able to produce primary peaks and secondary peaks at λ = 641.74 nm and λ = 585.98 nm for X-rays, and at λ = 637.93 nm and λ = 584.45 nm for SUV-rays, respectively. According to these findings, compared to 2021 films that expired shortly before the trial start date; 2018 films responded better to the absorbed dose than 2016 films when exposed to both X-ray and SUV-rays. In terms of energy dependence, the expired EBT3 2018 had the largest net ROD value. Using L*a*b* indices extracted from the RGB data, and despite that EBT3 films have expiry dates according to the manufacturer; all the films exhibited a substantial colour change, indicating that these films are still usable for clinical and research purposes.
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Affiliation(s)
- Hamad Yahia Abu Mhanna
- School of Physics, Universiti Sains Malaysia, Penang 11800, Malaysia;
- Correspondence: (H.Y.A.M.); (A.F.O.); (H.F.A.)
| | - Ahmad Fairuz Omar
- School of Physics, Universiti Sains Malaysia, Penang 11800, Malaysia;
- Correspondence: (H.Y.A.M.); (A.F.O.); (H.F.A.)
| | - Yasmin Md Radzi
- School of Physics, Universiti Sains Malaysia, Penang 11800, Malaysia;
| | - Hanan Fawaz Akhdar
- Physics Department, College of Science, Imam Mohammad Ibn Saud Islamic University (IMSIU), Riyadh 13318, Saudi Arabia
- Correspondence: (H.Y.A.M.); (A.F.O.); (H.F.A.)
| | - Haytham Al Ewaidat
- Department of Allied Medical Sciences-Radiologic Technology, Faculty of Applied Medical Sciences, Jordan University of Science and Technology, Irbid 22110, Jordan;
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11
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Huang L, Gaballa H, Chang J. Evaluating dosimetric accuracy of the 6 MV calibration on EBT3 film in the use of Ir-192 high dose rate brachytherapy. J Appl Clin Med Phys 2022; 23:e13571. [PMID: 35226398 PMCID: PMC9121041 DOI: 10.1002/acm2.13571] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2021] [Revised: 02/05/2022] [Accepted: 02/07/2022] [Indexed: 12/03/2022] Open
Abstract
Purpose To evaluate the dosimetric accuracy of EBT3 film calibrated with a 6 MV beam for high dose rate brachytherapy and propose a novel method for direct film calibration with an Ir‐192 source. Methods The 6 MV calibration was performed in water on a linear accelerator (linac). The Ir‐192 calibration was accomplished by irradiating the film wrapped around a cylinder applicator with an Ir‐192 source. All films were scanned 1‐day post‐irradiation to acquire calibration curves for all three (red, blue, and green) channels. The Ir‐192 calibration films were also used for single‐dose comparison. Moreover, an independent test film under a H.A.M. applicator was irradiated and the 2D dose distribution was obtained separately for each calibration using the red channel data. Gamma analysis and point‐by‐point profile comparison were performed to evaluate the performance of both calibrations. The uncertainty budget for each calibration system was analyzed. Results The red channel had the best performance for both calibration systems in the single‐dose comparison. We found a significant 4.89% difference from the reference for doses <250 cGy using the 6 MV calibration, while the difference was only 0.87% for doses >600 cGy. Gamma analysis of the 2D dose distribution showed the Ir‐192 calibration had a higher passing rate of 91.9% for the 1 mm/2% criterion, compared to 83.5% for the 6 MV calibration. Most failing points were in the low‐dose region (<200 cGy). The point‐by‐point profile comparison reported a discrepancy of 2%–3.6% between the Ir‐192 and 6 MV calibrations in this low‐dose region. The linac‐ and Ir‐192‐based dosimetry systems had an uncertainty of 4.1% (k = 2) and 5.66% (k = 2), respectively. Conclusions Direct calibration of EBT3 films with an Ir‐192 source is feasible and reliable, while the dosimetric accuracy of 6 MV calibration depends on the dose range. The Ir‐192 calibration should be used when the measurement dose range is below 250 cGy.
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Affiliation(s)
- Lyu Huang
- Department of Radiation Medicine, Center for Advanced Medicine, Northwell Health, New Hyde Park, New York, USA
| | - Hani Gaballa
- Department of Radiation Medicine, Center for Advanced Medicine, Northwell Health, New Hyde Park, New York, USA
| | - Jenghwa Chang
- Department of Radiation Medicine, Center for Advanced Medicine, Northwell Health, New Hyde Park, New York, USA.,Department of Radiation Medicine, Donald and Barbara Zucker School of Medicine at Hofstra/Northwell, New Hyde Park, New York, USA.,Department of Physics and Astronomy, Hofstra University, Hempstead, New York, USA
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12
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Méndez I, Rovira-Escutia JJ, Casar B. A protocol for accurate radiochromic film dosimetry using Radiochromic.com. Radiol Oncol 2021; 55:369-378. [PMID: 34384012 PMCID: PMC8366735 DOI: 10.2478/raon-2021-0034] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Accepted: 07/01/2021] [Indexed: 11/21/2022] Open
Abstract
BACKGROUND Radiochromic films have many applications in radiology and radiation therapy. Generally, the dosimetry system for radiochromic film dosimetry is composed of radiochromic films, flatbed scanner, and film analysis software. The purpose of this work is to present the effectiveness of a protocol for accurate radiochromic film dosimetry using Radiochromic.com as software for film analysis. MATERIALS AND METHODS Procedures for image acquisition, lot calibration, and dose calculation are explained and analyzed. Radiochromic.com enables state-of-the-art models and corrections for radiochromic film dosimetry, such as the Multigaussian model for multichannel film dosimetry, and lateral, inter-scan, and re-calibration corrections of the response. RESULTS The protocol presented here provides accurate dose results by mitigating the sources of uncertainty that affect radiochromic film dosimetry. CONCLUSIONS Appropriate procedures for film and scanner handling in combination with Radiochromic.com as software for film analysis make easy and accurate radiochromic film dosimetry feasible.
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Affiliation(s)
- Ignasi Méndez
- Department for dosimetry and quality of radiological procedures, Institute of Oncology Ljubljana, Ljubljana, Slovenia
| | | | - Bozidar Casar
- Department for dosimetry and quality of radiological procedures, Institute of Oncology Ljubljana, Ljubljana, Slovenia
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13
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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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14
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Hall AV, Musa OM, Hood DK, Apperley DC, Yufit DS, Steed JW. Alkali Metal Salts of 10,12-Pentacosadiynoic Acid and Their Dosimetry Applications. CRYSTAL GROWTH & DESIGN 2021. [PMID: 34054354 DOI: 10.1021/acs.cgd.1c00300] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Wide-dose-range 2D radiochromic films for radiotherapy, such as GAFchromic EBT, are based on the lithium salt of 10,12-pentacosadiynoic acid (Li-PCDA) as the photosensitive component. We show that there are two solid forms of Li-PCDA-a monohydrated form A and an anhydrous form B. The form used in commercial GAFchromic films is form A due to its short needle-shaped crystals, which provide favorable coating properties. Form B provides an enhanced photoresponse compared to that of form A, but adopts a long needle crystal morphology, which is difficult to process. The two forms were characterized by powder X-ray diffraction, Fourier transform infrared spectroscopy, CP-MAS 13C solid-state NMR spectroscopy, and thermogravimetric analysis. In sum, these data suggest a chelating bridging bidentate coordination mode for the lithium ions. The sodium salt of PCDA (Na-PCDA) is also reported, which is an ionic cocrystal with a formula of Na+PCDA-·3PCDA. The PCDA and PCDA- ligands display monodentate and bridging bidentate coordination to the sodium ion in contrast to the coordination sphere of the Li-PCDA forms. In contrast to its lithium analogues, Na-PCDA is photostable.
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Affiliation(s)
- Amy V Hall
- Department of Chemistry, Durham University, Lower Mountjoy, Stockton Road, Durham DH1 3LE, U.K
| | - Osama M Musa
- Ashland LLC, 1005 Route 202/206, Bridgewater, New Jersey 08807, United States
| | - David K Hood
- Ashland LLC, 1005 Route 202/206, Bridgewater, New Jersey 08807, United States
| | - David C Apperley
- Department of Chemistry, Durham University, Lower Mountjoy, Stockton Road, Durham DH1 3LE, U.K
| | - Dmitry S Yufit
- Department of Chemistry, Durham University, Lower Mountjoy, Stockton Road, Durham DH1 3LE, U.K
| | - Jonathan W Steed
- Department of Chemistry, Durham University, Lower Mountjoy, Stockton Road, Durham DH1 3LE, U.K
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15
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Hall AV, Musa OM, Hood DK, Apperley DC, Yufit DS, Steed JW. Alkali Metal Salts of 10,12-Pentacosadiynoic Acid and Their Dosimetry Applications. CRYSTAL GROWTH & DESIGN 2021; 21:2416-2422. [PMID: 34054354 PMCID: PMC8154271 DOI: 10.1021/acs.cgd.1c00031] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Revised: 03/17/2021] [Indexed: 05/22/2023]
Abstract
Wide-dose-range 2D radiochromic films for radiotherapy, such as GAFchromic EBT, are based on the lithium salt of 10,12-pentacosadiynoic acid (Li-PCDA) as the photosensitive component. We show that there are two solid forms of Li-PCDA-a monohydrated form A and an anhydrous form B. The form used in commercial GAFchromic films is form A due to its short needle-shaped crystals, which provide favorable coating properties. Form B provides an enhanced photoresponse compared to that of form A, but adopts a long needle crystal morphology, which is difficult to process. The two forms were characterized by powder X-ray diffraction, Fourier transform infrared spectroscopy, CP-MAS 13C solid-state NMR spectroscopy, and thermogravimetric analysis. In sum, these data suggest a chelating bridging bidentate coordination mode for the lithium ions. The sodium salt of PCDA (Na-PCDA) is also reported, which is an ionic cocrystal with a formula of Na+PCDA-·3PCDA. The PCDA and PCDA- ligands display monodentate and bridging bidentate coordination to the sodium ion in contrast to the coordination sphere of the Li-PCDA forms. In contrast to its lithium analogues, Na-PCDA is photostable.
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Affiliation(s)
- Amy V. Hall
- Department
of Chemistry, Durham University, Lower Mountjoy, Stockton Road, Durham DH1 3LE, U.K.
| | - Osama M. Musa
- Ashland
LLC, 1005 Route 202/206, Bridgewater, New Jersey 08807, United States
| | - David K. Hood
- Ashland
LLC, 1005 Route 202/206, Bridgewater, New Jersey 08807, United States
| | - David C. Apperley
- Department
of Chemistry, Durham University, Lower Mountjoy, Stockton Road, Durham DH1 3LE, U.K.
| | - Dmitry S. Yufit
- Department
of Chemistry, Durham University, Lower Mountjoy, Stockton Road, Durham DH1 3LE, U.K.
| | - Jonathan W. Steed
- Department
of Chemistry, Durham University, Lower Mountjoy, Stockton Road, Durham DH1 3LE, U.K.
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16
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Radiochromic Films for the Two-Dimensional Dose Distribution Assessment. APPLIED SCIENCES-BASEL 2021. [DOI: 10.3390/app11052132] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Radiochromic films are mainly used for two-dimensional dose verification in photon, electron, and proton therapy treatments. Moreover, the radiochromic film types available today allow their use in a wide dose range, corresponding to applications from low-medical diagnostics to high-dose beam profile measurements in charged particle medical accelerators. An in-depth knowledge of the characteristics of radiochromic films, of their operating principles, and of the dose reading techniques is of paramount importance to exploit all the features of this interesting and versatile radiation detection system. This short review focuses on these main aspects by considering the most recent works on the subject.
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17
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Lozares S, Font JA, Gandía A, Campos A, Flamarique S, Ibáñez R, Villa D, Alba V, Jiménez S, Hernández M, Casamayor C, Vicente I, Hernando E, Rubio P. In vivo dosimetry in low-voltage IORT breast treatments with XR-RV3 radiochromic film. Phys Med 2021; 81:173-181. [PMID: 33465753 DOI: 10.1016/j.ejmp.2020.12.011] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Revised: 12/12/2020] [Accepted: 12/16/2020] [Indexed: 12/30/2022] Open
Abstract
PURPOSE The objectives of the study were to establish a procedure for in vivo film-based dosimetry for intraoperative radiotherapy (IORT), evaluate the typical doses delivered to organs at risk, and verify the dose prescription. MATERIALS AND METHODS In vivo dose measurements were studied using XR-RV3 radiochromic films in 30 patients with breast cancer undergoing IORT using the Axxent® device (Xoft Inc.). The stability of the radiochromic films in the energy ranges used was verified by taking measurements at different depths. The stability of the scanner response was tested, and 5 different calibration curves were constructed for different beam qualities. Six pieces of film were placed in each of the 30 patients. All the pieces were correctly sterilized and checked to ensure that the process did not affect the outcome. All calibration and dose measurements were analyzed using the Radiochromic.com software application. RESULTS The doses were measured for 30 patients. The doses in contact with the applicator (prescription zone) were 19.8 ± 0.9 Gy. In the skin areas, the doses were as follows: 1-2 cm from the applicator, 1.86 ± 0.77 Gy; 2-5 cm, 0.73 ± 0.14 Gy; and greater than 5 cm, 0.28 ± 0.17 Gy. The dose delivered to the pectoral muscle (tungsten shielding disc) was 0.51 ± 0.27 Gy. CONCLUSIONS The study demonstrated the viability of XR-RV3 films for in vivo dose measurement in the dose and energy ranges applied in a complex procedure, such as breast IORT. The doses in organs at risk were far below the tolerances for cases such as those studied.
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Affiliation(s)
- Sergio Lozares
- Medical Physics Department. Miguel Servet University Hospital Zaragoza, Spain.
| | - Jose A Font
- Medical Physics Department. Miguel Servet University Hospital Zaragoza, Spain
| | - Almudena Gandía
- Medical Physics Department. Miguel Servet University Hospital Zaragoza, Spain
| | - Arantxa Campos
- Radiation Oncology Department. Miguel Servet University Hospital Zaragoza, Spain
| | - Sonia Flamarique
- Radiation Oncology Department. Miguel Servet University Hospital Zaragoza, Spain
| | - Reyes Ibáñez
- Radiation Oncology Department. Miguel Servet University Hospital Zaragoza, Spain
| | - David Villa
- Medical Physics Department. Miguel Servet University Hospital Zaragoza, Spain
| | - Verónica Alba
- Medical Physics Department. Miguel Servet University Hospital Zaragoza, Spain
| | - Sara Jiménez
- Medical Physics Department. Miguel Servet University Hospital Zaragoza, Spain
| | - Mónica Hernández
- Medical Physics Department. Miguel Servet University Hospital Zaragoza, Spain
| | - Carmen Casamayor
- Endocrine, Bariatric and Breast Surgery Unit. General and Digestive Surgery Department. Miguel Servet University Hospital Zaragoza, Spain
| | - Isabel Vicente
- Breast Unit. Gynaecology Department. Miguel Servet University Hospital Zaragoza, Spain
| | - Ernesto Hernando
- Endocrine, Bariatric and Breast Surgery Unit. General and Digestive Surgery Department. Miguel Servet University Hospital Zaragoza, Spain
| | - Patricia Rubio
- Breast Unit. Gynaecology Department. Miguel Servet University Hospital Zaragoza, Spain
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18
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Robinson SM, Esplen N, Wells D, Bazalova-Carter M. Monte Carlo simulations of EBT3 film dose deposition for percentage depth dose (PDD) curve evaluation. J Appl Clin Med Phys 2020; 21:314-324. [PMID: 33155768 PMCID: PMC7769387 DOI: 10.1002/acm2.13078] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Revised: 08/04/2020] [Accepted: 10/05/2020] [Indexed: 02/04/2023] Open
Abstract
Purpose To use Monte Carlo (MC) calculations to evaluate the effects of Gafchromic EBT3 film orientation on percentage depth dose (PDD) curves. Methods Dose deposition in films placed in a water phantom, and oriented either parallel or perpendicular with respect to beam axis, were simulated with MC and compared to PDDs scored in a homogenous water phantom. The effects of introducing 0.01–1.00 mm air gaps on each side of the film as well as a small 1°‐3° tilt for film placed in parallel orientation were studied. PDDs scored based on two published EBT3 film compositions were compared. Three photon beam energies of 120 kVp, 220 kVp, and 6 MV and three field sizes between 1 × 1 and 5 × 5 cm2 were considered. Experimental PDDs for a 6‐MV 3 × 3 cm2 beam were acquired. Results PDD curves for films in perpendicular orientation more closely agreed to water PDDs than films placed in parallel orientation. The maximum difference between film and water PDD for films in parallel orientation was −12.9% for the 220 kVp beam. For the perpendicular film orientation, the maximum difference decreased to 5.7% for the 120 kVp beam. The inclusion of an air gap had the largest effect on the 6‐MV 1 × 1 cm2 beam, for which the dose in the buildup region was underestimated by 21.2% compared to the simulation with no air gap. A 2° film tilt decreased the difference between the parallel film and homogeneous water phantom PDDs from −5.0% to −0.5% for the 6 MV 3 × 3 cm2 beam. The “newer” EBT3 film composition resulted in larger PDD discrepancies than the previous composition. Experimental film data qualitatively agreed with MC simulations. Conclusions PDD measurements with films should either be performed with film in perpendicular orientation to the beam axis or in parallel orientation with a ~ 2º tilt and no air gaps.
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Affiliation(s)
- Spencer M Robinson
- Department of Physics and Astronomy, University of Victoria, Victoria, BC, Canada
| | - Nolan Esplen
- Department of Physics and Astronomy, University of Victoria, Victoria, BC, Canada
| | - Derek Wells
- Department of Physics and Astronomy, University of Victoria, Victoria, BC, Canada.,BC Cancer Vancouver Island Centre, Victoria, BC, Canada
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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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20
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Aldelaijan S, Devic S, Bekerat H, Papaconstadopoulos P, Schneider J, Seuntjens J, Cormack RA, Buzurovic IM. Positional and angular tracking of HDR 192 Ir source for brachytherapy quality assurance using radiochromic film dosimetry. Med Phys 2020; 47:6122-6139. [PMID: 33064876 DOI: 10.1002/mp.14540] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2020] [Revised: 08/31/2020] [Accepted: 09/25/2020] [Indexed: 11/06/2022] Open
Abstract
PURPOSE To quantify and verify the dosimetric impact of high-dose rate (HDR) source positional uncertainty in brachytherapy, and to introduce a model for three-dimensional (3D) position tracking of the HDR source based on a two-dimensional (2D) measurement. This model has been utilized for the development of a comprehensive source quality assurance (QA) method using radiochromic film (RCF) dosimetry including assessment of different digitization uncertainties. METHODS An algorithm was developed and verified to generate 2D dose maps of the mHDR-V2 192 Ir source (Elekta, Veenendaal, Netherlands) based on the AAPM TG-43 formalism. The limits of the dosimetric error associated with source (0.9 mm diameter) positional uncertainty were evaluated and experimentally verified with EBT3 film measurements for 6F (2.0 mm diameter) and 4F (1.3 mm diameter) size catheters at the surface (4F, 6F) and 10 mm further (4F only). To quantify this uncertainty, a source tracking model was developed to incorporate the unique geometric features of all isodose lines (IDLs) within any given 2D dose map away from the source. The tracking model normalized the dose map to its maximum, then quantified the IDLs using blob analysis based on features such as area, perimeter, weighted centroid, elliptic orientation, and circularity. The Pearson correlation coefficients (PCCs) between these features and source coordinates (x, y, z, θy , θz ) were calculated. To experimentally verify the accuracy of the tracking model, EBT3 film pieces were positioned within a Solid Water® (SW) phantom above and below the source and they were exposed simultaneously. RESULTS The maximum measured dosimetric variations on the 6F and 4F catheter surfaces were 39.8% and 36.1%, respectively. At 10 mm further, the variation reduced to 2.6% for the 4F catheter which is in agreement with the calculations. The source center (x, y) was strongly correlated with the low IDL-weighted centroid (PCC = 0.99), while the distance to source (z) was correlated with the IDL areas (PCC = 0.96) and perimeters (PCC = 0.99). The source orientation θy was correlated with the difference between high and low IDL-weighted centroids (PCC = 0.98), while θz was correlated with the elliptic orientation of the 60-90% IDLs (PCC = 0.97) for a maximum distance of z = 5 mm. Beyond 5 mm, IDL circularity was significant, therefore limiting the determination of θz (PCC ≤ 0.48). The measured positional errors from the film sets above and below the source indicated a source position at the bottom of the catheter (-0.24 ± 0.07 mm). CONCLUSIONS Isodose line features of a 2D dose map away from the HDR source can reveal its spatial coordinates. RCF was shown to be a suitable dosimeter for source tracking and dosimetry. This technique offers a novel source QA method and has the potential to be used for QA of commercial and customized applicators.
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Affiliation(s)
- Saad Aldelaijan
- Department of Radiation Oncology, Dana Farber/Brigham and Women's Cancer Center, Harvard Medical School, Boston, MA, 02115, USA.,Department of Biomedical Engineering, Montreal Neurological Institute, McGill University, Montréal, QC, H3A 2B4, Canada.,Medical Physics Unit, McGill University, Montréal, QC, H4A 3J1, Canada.,Department of Radiation Oncology, SMBD Jewish General Hospital, Montréal, QC, H3T 1E2, Canada.,Biomedical Physics Department, King Faisal Specialist Hospital & Research Centre, Riyadh, 12713, Saudi Arabia
| | - Slobodan Devic
- Medical Physics Unit, McGill University, Montréal, QC, H4A 3J1, Canada.,Department of Radiation Oncology, SMBD Jewish General Hospital, Montréal, QC, H3T 1E2, Canada
| | - Hamed Bekerat
- Department of Radiation Oncology, SMBD Jewish General Hospital, Montréal, QC, H3T 1E2, Canada
| | | | - James Schneider
- Department of Radiation Oncology, SMBD Jewish General Hospital, Montréal, QC, H3T 1E2, Canada
| | - Jan Seuntjens
- Medical Physics Unit, McGill University, Montréal, QC, H4A 3J1, Canada
| | - Robert A Cormack
- Department of Radiation Oncology, Dana Farber/Brigham and Women's Cancer Center, Harvard Medical School, Boston, MA, 02115, USA
| | - Ivan M Buzurovic
- Department of Radiation Oncology, Dana Farber/Brigham and Women's Cancer Center, Harvard Medical School, Boston, MA, 02115, USA
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Tiwari A, Sunderland J, Graves SA, Strand S, Flynn R. Absorbed dose distributions from beta-decaying radionuclides: Experimental validation of Monte Carlo tools for radiopharmaceutical dosimetry. Med Phys 2020; 47:5779-5790. [PMID: 32955755 DOI: 10.1002/mp.14463] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Revised: 06/22/2020] [Accepted: 08/04/2020] [Indexed: 11/05/2022] Open
Abstract
PURPOSE This study aims to experimentally validate the Monte Carlo generated absorbed doses from the beta particles emitted by 90 Y and 177 Lu using radiochromic EBT3 film-based dosimetry. METHODS Line sources of 90 Y and 177 Lu were inserted longitudinally through blocks of low-density polyethylene and tissue-equivalent slabs of cortical bone and lung equivalent plastics. Radiochromic film (Gafchromic EBT3) was laser cut to accommodate orthogonal line sources of radioactivity, and the film was sandwiched intimately between the rectangular blocks to achieve charged particle equilibrium. Line sources consisted of plastic capillary tube of length (13 ± 0.1) cm, with 0.42-mm inner diameter and a wall thickness of 0.21 mm. 90 Y line sources were prepared from a solution of dissolved 90 Y resin microspheres. 177 Lu line sources were prepared from an aliquot of 177 Lu-DOTATATE. Film exposures were conducted for durations ranging from 10 min to 38 h. Radiochromic film calibration was performed by irradiation with 6-MV-bremsstrahlung x rays from a calibrated linear accelerator, in accordance with literature recommendations. Experimental geometries were precisely simulated within the GATE Monte Carlo toolkit, which has previously been used for the generation of dose point kernels. RESULTS The mean percentage difference between measured and simulated absorbed doses were 5.04% and 7.21% for 90 Y and 177 Lu beta absorbed dose in the range of (0.1-10) Gy. Additionally, 1D gamma analysis using a local 10%/1 mm gamma criterion was performed to compare the absorbed dose distributions. The percentage of measurement points passing the gamma criterion, averaged over all tests, was 93.5%. CONCLUSIONS We report the experimental validation of Monte Carlo derived beta absorbed dose distributions for 90 Y and 177 Lu, solidifying the validity of using Monte Carlo-based methods for estimating absorbed dose from beta emitters. Overall, excellent agreement was observed between the experimental beta absorbed doses in the linear region of the radiochromic film and the GATE Monte Carlo simulations demonstrating that radiochromic film dosimetry has sufficient sensitivity and spatial resolution to be used as a tool for measuring beta decay absorbed dose distributions.
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Affiliation(s)
- Ashok Tiwari
- Department of Radiology, University of Iowa Hospitals and Clinics, 200 Hawkins Dr., Iowa City, IA, 52242-1077, USA.,Department of Physics, University of Iowa, 203 Van Allen Hall, Iowa City, IA, 52242-1479, USA
| | - John Sunderland
- Department of Radiology, University of Iowa Hospitals and Clinics, 200 Hawkins Dr., Iowa City, IA, 52242-1077, USA.,Department of Physics, University of Iowa, 203 Van Allen Hall, Iowa City, IA, 52242-1479, USA
| | - Stephen A Graves
- Department of Radiology, University of Iowa Hospitals and Clinics, 200 Hawkins Dr., Iowa City, IA, 52242-1077, USA.,Department of Radiation Oncology, University of Iowa Hospitals and Clinics, 200 Hawkins Dr., Iowa City, IA, 52242-1089, USA
| | - Sarah Strand
- Department of Radiation Oncology, University of Iowa Hospitals and Clinics, 200 Hawkins Dr., Iowa City, IA, 52242-1089, USA
| | - Ryan Flynn
- Department of Radiation Oncology, University of Iowa Hospitals and Clinics, 200 Hawkins Dr., Iowa City, IA, 52242-1089, USA
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22
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García-Hernández T, Vicedo-González A, Sánchez-Nieto B, Romero-Expósito M, Roselló-Ferrando J. PERIPHERAL SURFACE DOSE FROM A LINEAR ACCELERATOR: RADIOCHROMIC FILM EXPERIMENTAL MEASUREMENTS OF FLATTENING FILTER FREE VERSUS FLATTENED BEAMS. RADIATION PROTECTION DOSIMETRY 2020; 188:285-298. [PMID: 31922571 DOI: 10.1093/rpd/ncz286] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Revised: 11/06/2019] [Accepted: 11/26/2019] [Indexed: 06/10/2023]
Abstract
There is a growing interest in the use of flattening filter free (FFF) beams due to the shorter treatment times. The reduction of head scatter suggests a better radiation protection to radiotherapy patients, considering the expected decrease in peripheral surface dose (PSD). In this work, PSD of flattened (FF) and FFF-photon beams was compared. A radiochromic film calibration method to reduce energy dependence was used. PSD was measured at distances from 2 to 50 cm to the field border for different square field sizes, modifying relevant clinical parameters. Also, clinical breast and prostate stereotactic body radiotherapy (SBRT) plans were studied. For square beams, FFF PSD is lower compared with FF PSD (differences ranging from 3 to 64%) and 10 MV FFF yields to the lowest value, for distances greater than 5 cm. For SBRT plans, near and far away from the field border, there is a reduction of PSD for FFF-beams, but the behavior at intermediate distances should be checked depending on the case.
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Affiliation(s)
| | - Aurora Vicedo-González
- Departmento de Física Médica, ERESA Hospital General Universitario de Valencia, Valencia, Spain
| | | | | | - Joan Roselló-Ferrando
- Departmento de Física Médica, ERESA Hospital General Universitario de Valencia, Valencia, Spain
- Departamento de Fisiología, Universidad de Valencia, Valencia, Spain
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23
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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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24
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Murphy L. The dosimetric effect of variations in source position on treatments using Leipzig-style brachytherapy skin applicators. Biomed Phys Eng Express 2020; 6:015031. [PMID: 33438619 DOI: 10.1088/2057-1976/ab6ecf] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Leipzig-style skin brachytherapy applicators are an excellent choice for the treatment of small surface lesions, since they can be used with a high dose rate source to produce a tightly constrained treatment field on the desired area of the skin. The dosimetry of these applicators is challenging to independently verify due to their small dimensions, complex energy spectrum and steep dose gradients. In particular the close proximity of the brachytherapy source to the treatment region is cause for concern, since small variations in the position of the radioactive source may significantly affect the resulting dose distribution. The aim of this work was to assess the dosimetry of these applicators using three independently techniques and use these results to examine the effect of variation in source position on the dose distribution. Simulation of different sized applicators in conjunction with a Gammamed + Ir192 source was performed using the EGSnrc Monte Carlo code. Dose distributions at the prescription depth and at the surface generated by Monte Carlo were compared to the outputs of a commercially available treatment planning system and measurements using radiochromic film. Source displacements of up to 0.5 mm in the vertical direction, 0.65 mm in the horizontal direction, and rotations of the source by up to 5° were all simulated. Changes in dose of over 6% at the prescription point and reductions in coverage at the 100% isodose level of several millimetres were observed even for small shifts of the source from its intended position. This work demonstrates that variation in the position of the radiation source is the dominant source of uncertainty in the use of these types of applicators. Centres wishing to perform treatments using these applicators are advised to take steps to control the uncertainty and ensure it remains at an acceptable level.
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Affiliation(s)
- Liam Murphy
- Department of Radiotherapy, NHS Grampian, Aberdeen, United Kingdom
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25
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Galván De la Cruz O, Rodríguez-Ávila M, Rivera-Montalvo T, García Garduño O. Measurement of percentage dose at the surface for a 6 MV photon beam. Rep Pract Oncol Radiother 2019; 24:585-592. [PMID: 31660051 PMCID: PMC6807031 DOI: 10.1016/j.rpor.2019.09.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2018] [Revised: 05/09/2019] [Accepted: 09/21/2019] [Indexed: 11/19/2022] Open
Abstract
AIM To evaluate if a radiochromic film (RF) Gafchromic EBT3 is suitable for surface dose measurements of radiotherapy treatments performed with a 6 MV linear accelerator. Two aspects of RF were analyzed, beam energy dependence and surface dose determination. BACKGROUND The measurements done at the surface or near the radiation source are done without charged electronic equilibrium and also have contribution of electron contamination. The detectors used for these measurements should not alter the dose to the target. To counteract these dosimetric problems it is proposed to do the measurements with radiochromic films which are thin detectors and have tissue equivalent properties. MATERIALS AND METHODS The measurements were done using a Novalis linear accelerator (LINAC) with nominal energy of 6 MV. To determine the surface dose, the total scatter factors (TSF) of three different field sizes were measured in a water phantom at 5 cm depth. Energy dependence of EBT3 was studied at three different depths, using a solid water phantom. The surface measurements were done with the RF for the same field sizes of the TSF measurements. The value of the percentage depth dose was calculated normalizing the doses measured in the RF with the LINAC output, at 5 cm depth, and the TSF. RESULTS The radiochromic films showed almost energy independence, the differences between the curves are 1.7% and 1.8% for the 1.5 cm and 10 cm depth, respectively. The percentage depth doses values at the surface measured for the 10 cm × 10 cm, 5 cm × 5 cm and 1 cm × 1 cm were 26.1 ± 1.3%, 21.3 ± 2.4% and 20.2 ± 2.6%, respectively. CONCLUSIONS The RF-EBT3 seems to be a detector suitable for measurements of the dose at the surface. This suggests that RF-EBT3 films might be good candidates as detectors for in vivo dosimetry.
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Affiliation(s)
- O.O. Galván De la Cruz
- Unidad de Radioneurocirugía, Instituto Nacional de Neurología y Neurocirugía, Insurgentes Sur 3877, México City, Mexico
- Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada, Unidad Legaria, Instituto Politécnico Nacional, Legaria 694, México city, México
| | - M.A. Rodríguez-Ávila
- Posgrado en Ciencias Físicas, Universidad Nacional Autónoma de México, Instituto de Física, Circuito de la Investigación Científica s/n. Ciudad Universitaria, 04510, Mexico City, México
| | - T. Rivera-Montalvo
- Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada, Unidad Legaria, Instituto Politécnico Nacional, Legaria 694, México city, México
| | - O.A. García Garduño
- Laboratorio de Física Médica, Instituto Nacional de Neurología y Neurocirugía, Insurgentes Sur 3877, México City, México
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26
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Devic S, Aldelaijan S, Bekerat H. Impact of inertia on possible fundamental drawbacks in radiochromic film dosimetry. Phys Med 2019; 66:133-134. [DOI: 10.1016/j.ejmp.2019.08.019] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/11/2019] [Revised: 08/23/2019] [Accepted: 08/25/2019] [Indexed: 10/25/2022] Open
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27
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Mirza JA, Hernández Millares R, Kim GI, Park SY, Lee J, Ye SJ. Characterization of radiochromic films as a micrometer-resolution dosimeter by confocal Raman spectroscopy. Med Phys 2019; 46:5238-5248. [PMID: 31442302 DOI: 10.1002/mp.13778] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2019] [Revised: 07/08/2019] [Accepted: 08/12/2019] [Indexed: 11/06/2022] Open
Abstract
PURPOSE Micrometer spatial resolution dosimetry has become inevitable for advanced radiotherapy techniques. A new approach using radiochromic films was developed to measure a radiation dose at a micrometer spatial resolution by confocal Raman spectroscopy. METHODS The commercial radiochromic films (RCF), EBT3 and EBT-XD, were irradiated with known doses using 50, 100, 200, and 300 kVp, and 6-MV x rays. The dose levels ranged from 0.3 to 50 Gy. The Raman mapping technique developed in our early study was used to readout an area of 100 × 100 µm2 on RCF with improved lateral and depth resolutions with confocal Raman spectrometry. The variation in Raman spectra of C-C-C deformation and C≡C stretching modes of diacetylene polymers around 676 and 2060 cm-1 , respectively, as a function of therapeutic x-ray doses, was measured. The single peak (SP) of C≡C and the peak ratio (PR) of C≡C band height to C-C-C band height with a spatial resolution of 10 µm on both types of RCF were evaluated, averaged, and plotted as a function of dose. An achievable spatial resolution, clinically useful dose range, dosimetric sensitivity, dose uniformity, and postirradiation stability as well as the orientation, energy, and dose rate dependence, of both types of RCFs, were characterized by the technique developed in this study. RESULTS A spatial resolution on RCF achieved by SP and PR methods was ~4.5 and ~2.9 µm, respectively. Raman spectroscopy data showed dose nonuniformity of ~11% in SP method and <3% in PR method. The SP method provided dose ranges of up to ~10 and ~20 Gy for EBT3 and EBT-XD films, respectively while the PR method up to ~30 and ~50 Gy. The PR method diminished the orientation effect. The percent difference between landscape and portrait orientations for the EBT3 and the EBT-XD films at 4 Gy had an acceptable level of 1.2% and 2.4%, respectively. With both SP and PR methods, the EBT3 and the EBT-XD films showed weak energy (within ~10% and ~3% for SP and PR methods, respectively) and dose rate dependence (within ~5% and ~3% for SP and PR methods, respectively) and had a stable response after 24-h postirradiation. CONCLUSIONS A technique for micrometer-resolution dosimetry was successfully developed by detecting radiation-induced Raman shift on EBT3 and EBT-XD. Both types of RCFs were suitable for micrometer-resolution dosimetry using CRS. With CRS both lateral and depth resolutions on RCF were improved. The PR method provided superior characteristics in dose uniformity, dose ranges, orientation dependence, and laser effect for both types of RCFs. The overall dosimetric characteristics of the RCFs determined by this technique were similar to those known by optical density scanning. The CRS with the PR method is advantageous over other the traditional scanning systems as a spatial resolution of <10 µm on RCF can be achieved with less deviations.
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Affiliation(s)
- Jamal Ahmad Mirza
- Department of Transdisciplinary Studies, Graduate School of Convergence Science and Technology, Program in Biomedical Radiation Sciences, Seoul National University, Seoul, 08826, Korea.,Isotope Production Division, Pakistan Institute of Nuclear Science and Technology, Nilore, Islamabad, 44000, Pakistan
| | - Rodrigo Hernández Millares
- Department of Transdisciplinary Studies, Graduate School of Convergence Science and Technology, Program in Biomedical Radiation Sciences, Seoul National University, Seoul, 08826, Korea
| | - Geon Il Kim
- Department of Transdisciplinary Studies, Graduate School of Convergence Science and Technology, Program in Biomedical Radiation Sciences, Seoul National University, Seoul, 08826, Korea.,School of Medicine, CHA University, Pocheon, 11160, Korea
| | - So-Yeon Park
- Department of Radiation Oncology, Veterans Health Service Medical Center, Seoul, 05368, Korea
| | - Jaegi Lee
- Department of Transdisciplinary Studies, Graduate School of Convergence Science and Technology, Program in Biomedical Radiation Sciences, Seoul National University, Seoul, 08826, Korea
| | - Sung-Joon Ye
- Department of Transdisciplinary Studies, Graduate School of Convergence Science and Technology, Program in Biomedical Radiation Sciences, Seoul National University, Seoul, 08826, Korea.,Biomedical Research Institute, Seoul National University Hospital, Seoul, 03080, Korea.,Robotics Research Laboratory for Extreme Environments, Advance Institutes of Convergence Technology, Seoul National University, Suwon, 16229, Korea
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28
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Van der Heggen D, Cooper DR, Tesson M, Joos JJ, Seuntjens J, Capobianco JA, Smet PF. Optically Stimulated Nanodosimeters with High Storage Capacity. NANOMATERIALS (BASEL, SWITZERLAND) 2019; 9:E1127. [PMID: 31387200 PMCID: PMC6723962 DOI: 10.3390/nano9081127] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Revised: 07/29/2019] [Accepted: 08/01/2019] [Indexed: 12/11/2022]
Abstract
In this work we report on the thermoluminescence (TL) and optically stimulated luminescence (OSL) properties of β-Na(Gd,Lu)F4:Tb3+ nanophosphors prepared via a standard high-temperature coprecipitation route. Irradiating this phosphor with X-rays not only produces radioluminescence but also leads to a bright green afterglow that is detectable up to hours after excitation has stopped. The storage capacity of the phosphor was found to be (2.83 ± 0.05) × 1016 photons/gram, which is extraordinarily high for nano-sized particles and comparable to the benchmark bulk phosphor SrAl2O4:Eu2+,Dy3+. By combining TL with OSL, we show that the relatively shallow traps, which dominate the TL glow curves and are responsible for the bright afterglow, can also be emptied optically using 808 or 980 nm infrared light while the deeper traps can only be emptied thermally. This OSL at therapeutically relevant radiation doses is of high interest to the medical dosimetry community, and is demonstrated here in uniform, solution-processable nanocrystals.
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Affiliation(s)
- David Van der Heggen
- LumiLab, Department of Solid State Sciences, Ghent University, Krijgslaan 281-S1, 9000 Gent, Belgium
| | - Daniel R Cooper
- Medical Physics Unit, McGill University, Cedars Cancer Centre, 1001 Décarie Blvd, Montreal, QC H4A 3J1, Canada
- Department of Chemistry and Biochemistry and Centre for NanoScience Research, Concordia University, 7141 Sherbrooke St. W., Montreal, QC H4B 1R6, Canada
| | - Madeleine Tesson
- Department of Chemistry and Biochemistry and Centre for NanoScience Research, Concordia University, 7141 Sherbrooke St. W., Montreal, QC H4B 1R6, Canada
| | - Jonas J Joos
- LumiLab, Department of Solid State Sciences, Ghent University, Krijgslaan 281-S1, 9000 Gent, Belgium
| | - Jan Seuntjens
- Medical Physics Unit, McGill University, Cedars Cancer Centre, 1001 Décarie Blvd, Montreal, QC H4A 3J1, Canada
| | - John A Capobianco
- Department of Chemistry and Biochemistry and Centre for NanoScience Research, Concordia University, 7141 Sherbrooke St. W., Montreal, QC H4B 1R6, Canada
| | - Philippe F Smet
- LumiLab, Department of Solid State Sciences, Ghent University, Krijgslaan 281-S1, 9000 Gent, Belgium.
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Devic S, Liang L, Tomic N, Bekerat H, Morcos M, Popovic M, Watson P, Aldelaijan S, Seuntjens J. Dose measurements nearby low energy electronic brachytherapy sources using radiochromic film. Phys Med 2019; 64:40-44. [DOI: 10.1016/j.ejmp.2019.05.017] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/26/2019] [Revised: 05/24/2019] [Accepted: 05/25/2019] [Indexed: 11/25/2022] Open
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30
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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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31
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Smith BR, Pankuch M, Hammer CG, DeWerd LA, Culberson WS. LET response variability of Gafchromic TM EBT3 film from a 60 Co calibration in clinical proton beam qualities. Med Phys 2019; 46:2716-2728. [PMID: 30740699 DOI: 10.1002/mp.13442] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2018] [Revised: 11/01/2019] [Accepted: 02/02/2019] [Indexed: 11/11/2022] Open
Abstract
PURPOSE To establish a method of accurate dosimetry required to quantify the expected linear energy transfer (LET) quenching effect of EBT3 film used to benchmark the dose distribution for a given treatment field and specified measurement depth. In order to facilitate this technique, a full analysis of film calibration which considers LET variability at the plane of measurement and as a function of proton beam quality is demonstrated. Additionally, the corresponding uncertainty from the process was quantified for several measurement scenarios. MATERIALS AND METHODS The net change in optical density (OD) from a single version of Gafchromic TM EBT3 film was measured using an Epson flatbed scanner and NIST-traceable OD filters. Film OD response was characterized with respect to the known dose to water at the point of measurement for both a NIST-traceable 60 Co beam at the UWADCL and several clinical single-energy and spread-out Bragg peak (SOBP) proton beam qualities at the Northwestern Medicine Chicago Proton Center. Increasing proton LET environments were acquired by placing film at increasing depths of Gammex HE Solid Water® whose water-equivalent thickness was characterized prior to measurement. RESULTS A strong LET dependence was observed near the Bragg peak (BP) consistent with previous studies performed with earlier versions of EBT3 film. The influence of range straggling on the film's LET response appears to have a uniform effect toward the BP regardless of the nominal beam energy. Proximal to this depth, the film's response decreased with decreasing energy at the same dose-average LET. The opposite trend was observed for depths past the BP. Changes in the SOBP energy modulation showed a linear relationship between the film's relative response and dose-averaged LET. Relative effectiveness factors (RE) were observed to range between 2%-7% depending on the width of the SOBP and depth of the film. Using the field-specific calibration technique, a total k = 1 uncertainty in the absorbed dose to water was estimated to range from 4.68%-5.21%. CONCLUSION While EBT3 film's strong LET dependence is a common problem in proton beam dosimetry, this work has shown that the LET dependence can be taken into account by carefully considering the depth and energy modulation across the film using field-specific corrections. RE factors were determined with a combined k = 1 uncertainty of 3.57% for SOBP environments and between 3.17%-4.69% for uniform, monoenergetic fields proximal to the distal 80% of the BP.
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Affiliation(s)
- Blake R Smith
- Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, 53705, USA
| | - Mark Pankuch
- Division of Medical Physics, Northwestern Medicine Chicago Proton Center, 4455 Weaver Parkway, Warrenville, IL, 60555, USA
| | - Clifford G Hammer
- 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
| | - Wesley S Culberson
- Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, 53705, USA
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32
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Rodríguez C, Martínez LC. Radiochromic
EBT
2 and
EBT
3 sensitometry based on growth of two color phases of the polymer. Med Phys 2019; 46:1896-1904. [DOI: 10.1002/mp.13424] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Revised: 01/22/2019] [Accepted: 01/25/2019] [Indexed: 11/10/2022] Open
Affiliation(s)
- César Rodríguez
- Medical Physics and Radiation Protection Service Fuenlabrada University Hospital Camino del Molino, 2 Fuenlabrada Madrid 28942 Spain
| | - Luis Carlos Martínez
- Medical Physics and Radiation Protection Service 12 de Octubre University Hospital Av Cordoba s/n Madrid 28041 Spain
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33
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Akyol F, Sarigul N, Yeginer M, Yedekci Y, Utku H. Evaluation of NanoDot Optically Stimulated Luminescence Dosimeter for Cone-shaped Small-field Dosimetry of Cyberknife Stereotactic Radiosurgery Unit: A Monte Carlo Simulation and Dosimetric Verification Study. J Med Phys 2019; 44:27-34. [PMID: 30983768 PMCID: PMC6438048 DOI: 10.4103/jmp.jmp_96_18] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Aim The aim of this study was to investigate the adequacy of nanoDot optically stimulated luminescence (OSL) dosimeter for small field dosimetry before its in vivo applications in CyberKnife SRS unit. Materials and Methods A PTW 60018 SRS Diode, 60019 microDiamond, and Gafchromic EBT3 films were used along with a nanoDot carbon-doped aluminum oxide OSL dosimeter to collect and compare beam data. In addition, the EGSnrc/BEAMnrc code was employed to simulate 6-MV photon beams of CyberKnife SRS system. Results All detectors showed good consistency with each other in output factor measurements for cone sizes of 15 mm or more. The differences were maintained within 3% for these cones. However, OSL output factors showed higher discrepancies compared to those of other detectors for smaller cones wherein the difference reached nearly 40% for cone size of 5 mm. Depending on the performance of OSL dosimeter in terms of output factors, percentage depth doses (PDDs) were only measured for cones equal to or larger than 15 mm. The differences in PDD measurements were within 5% for depths in the range of 5-200 mm. Conclusion Its low reliable readings for cones smaller than 15 mm should be considered before its in vivo applications of Cyberknife system.
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Affiliation(s)
- Fadil Akyol
- Department of Radiation Oncology, Faculty of Medicine, Hacettepe University, Ankara, Turkey
| | - Neslihan Sarigul
- Institute of Nuclear Science, Hacettepe University, Ankara, Turkey
| | - Mete Yeginer
- Department of Radiation Oncology, Faculty of Medicine, Hacettepe University, Ankara, Turkey
| | - Yagiz Yedekci
- Department of Radiation Oncology, Faculty of Medicine, Hacettepe University, Ankara, Turkey
| | - Haluk Utku
- Institute of Nuclear Science, Hacettepe University, Ankara, Turkey
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Abstract
The change in optical properties of GafChromic films depends not only on the absorbed dose, but also on the linear energy transfer (LET) of the ionizing radiation. The influence of LET on the film dose-response relationship is especially important when films are applied for dosimetry of energetic charged particles. In the present study, we examined the response of the unlaminated EBT3 and MD-V3 films to proton, deuterium and helium beams with energies in the range of several megaelectronvolts (MeV). Films were exposed to doses up to 200 Gy and a model based on the bimolecular chemical reaction was chosen to fit the measured film signals. The LET in the active layers of the films and the dose correction factors were computed with Monte Carlo software TRIM. Signal quenching, observed for all ion beams in comparison to x-rays, was investigated as a function of the LET in the range of 10-100 keV µm-1. The response of the films got weaker with increasing the LET and showed no dependence on the ion species. The LET effect was quantified by introducing a modified expression for the relative effectiveness (RE) by which a unique RE value is assigned to a single LET. The RE defined in that way decreased from about 90% for LET of 10 keV µm-1 to less than 50% for LET of 100 keV µm-1. Similar behavior was observed for EBT3 and MD-V3 film models.
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Affiliation(s)
- V. Grilj
- Center for Radiological Research, Columbia University Irving Medical Center, New York, NY, USA
| | - D. J. Brenner
- Center for Radiological Research, Columbia University Irving Medical Center, New York, NY, USA
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Fagerstrom JM, DeWerd LA, Palmer B, Culberson WS. Prototype modulated orthovoltage stereotactic radiosurgery cones. RADIAT MEAS 2018. [DOI: 10.1016/j.radmeas.2018.09.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Méndez I, Polšak A, Hudej R, Casar B. The Multigaussian method: a new approach to mitigating spatial heterogeneities with multichannel radiochromic film dosimetry. Phys Med Biol 2018; 63:175013. [PMID: 30101754 DOI: 10.1088/1361-6560/aad9c1] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The main objective of multichannel radiochromic film dosimetry methods is to correct, or at least mitigate, spatial heterogeneities in the film-scanner response, especially variations in the active layer thickness. To this end, films can also be scanned prior to irradiation. In this study, the abilities of various single channel and multichannel methods to reduce spatial heterogeneities, with and without scanning before irradiation, were tested. Red, green and blue single channel models, two additive channel independent perturbation (CHIP) models and two multiplicative CHIP models were compared with the Multigaussian method. The Multigaussian method is a new approach to multichannel dosimetry, based on experimental findings. It assumes that the probability density function of the response vector formed by the pixel values of the different color channels, including irradiated and non-irradiated scans, follows a multivariate Gaussian distribution. The Multigaussian method provided more accurate doses than the other models under comparison, especially when incorporating the information of the film prior to irradiation. The relative dose differences between reference doses measured with MatriXX and film doses were examined. After applying inter-scan and lateral corrections, the lowest mean absolute errors were 0.8% and 1.0% for the Multigaussian method with and without the information of the scan before irradiation, respectively. Followed by the uniform multiplicative CHIP and red single channel models, using pixel values and net optical density, respectively, both with 1.1%.
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Affiliation(s)
- I Méndez
- Department of Medical Physics, Institute of Oncology Ljubljana, Zaloška cesta 2, Ljubljana 1000, Slovenia
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37
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Barten DLJ, Hoffmans D, Palacios MA, Heukelom S, van Battum LJ. Suitability of EBT3 GafChromic film for quality assurance in MR-guided radiotherapy at 0.35 T with and without real-time MR imaging. ACTA ACUST UNITED AC 2018; 63:165014. [DOI: 10.1088/1361-6560/aad58d] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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38
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Prentou E, Papagiannis P, Pantelis E, Zoros E, Karaiskos P. [OA153] EBT3 radiochromic film dosimetry in kV X-ray radiation therapy. Phys Med 2018. [DOI: 10.1016/j.ejmp.2018.06.225] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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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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40
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Parwaie W, Refahi S, Ardekani MA, Farhood B. Different Dosimeters/Detectors Used in Small-Field Dosimetry: Pros and Cons. JOURNAL OF MEDICAL SIGNALS & SENSORS 2018; 8:195-203. [PMID: 30181968 PMCID: PMC6116321 DOI: 10.4103/jmss.jmss_3_18] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
With the advent of complex and precise radiation therapy techniques, the use of relatively small fields is needed. Using such field sizes can cause uncertainty in dosimetry; therefore, special attention is required both in dose calculations and measurements. There are several challenges in small-field dosimetry such as the steep gradient of the radiation field, volume averaging effect, lack of charged particle equilibrium, partial occlusion of radiation source, beam alignment, and unable to use a reference dosimeter. Due to these challenges, special dosimeters are needed for small-field dosimetry, and this review article discusses this topic.
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Affiliation(s)
- Wrya Parwaie
- Department of Medical Physics and Biomedical Engineering, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
| | - Soheila Refahi
- Department of Medical Physics, Faculty of Medicine, Ardabil University of Medical Sciences, Ardabil, Iran
| | - Mahdieh Afkhami Ardekani
- Department of Radiology, Faculty of Para-Medicine, Hormozgan University of Medical Sciences, Bandar Abbas, Iran
| | - Bagher Farhood
- Department of Radiology and Medical Physics, Faculty of Paramedical Sciences, Kashan University of Medical Sciences, Kashan, Iran
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41
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Watson PGF, Bekerat H, Papaconstadopoulos P, Davis S, Seuntjens J. An investigation into the INTRABEAM miniature x-ray source dosimetry using ionization chamber and radiochromic film measurements. Med Phys 2018; 45:4274-4286. [PMID: 29935088 DOI: 10.1002/mp.13059] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Revised: 05/22/2018] [Accepted: 06/15/2018] [Indexed: 02/28/2024] Open
Abstract
PURPOSE Intraoperative radiotherapy using The INTRABEAM System (Carl Zeiss Meditec AG, Jena, Germany), a miniature low-energy x-ray source, has proven to be an effective modality in the treatment of breast cancer. However, some uncertainties remain in its dosimetry. In this work, we investigated the INTRABEAM system dosimetry by performing ionization chamber and radiochromic film measurements of absorbed dose in a water phantom. METHODS Ionization chamber measurements were performed with a PTW 34013 parallel-plate soft x-ray chamber at source to detector distances of 5 to 30 mm calculated using (a) the dose formula consistent with the TARGIT breast protocol (TARGIT), (b) the formula recommended by the manufacturer (Zeiss), and (c) the recently proposed CQ formalism of Watson et al. (Physics in Medicine & Biology, 2018;63:015016) EBT3 Gafchromic film measurements were made at the same depths in water. To account for the energy dependence of EBT3 film, multiple dose response calibration curves were employed across a range of photon beam qualities relevant to the INTRABEAM spectrum in water. RESULTS At all depths investigated, the TARGIT dose was significantly lower than that measured by the Zeiss and CQ methods, as well as film. These dose differences ranged from 14% to as large as 80%. In general, the doses measured by film, and the Zeiss and CQ methods were in good agreement to within measurement uncertainties (5-6%). CONCLUSIONS These results suggest that the TARGIT dose underestimates the physical dose to water from the INTRABEAM source. Understanding the correlation between the TARGIT and physical dose is important for any studies wishing to make dosimetric comparisons between the INTRABEAM and other radiation emitting devices.
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Affiliation(s)
| | - Hamed Bekerat
- Medical Physics Unit, Department of Radiation Oncology, SMBD Jewish General Hospital, McGill University, Montreal, QC, Canada
| | - Pavlos Papaconstadopoulos
- Medical Physics Unit, Department of Radiation Oncology, SMBD Jewish General Hospital, McGill University, Montreal, QC, Canada
| | - Stephen Davis
- Medical Physics Unit, McGill University, Montreal, QC, Canada
| | - Jan Seuntjens
- Medical Physics Unit, McGill University, Montreal, QC, Canada
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42
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Comparison of dose response functions for EBT3 model GafChromic™ film dosimetry system. Phys Med 2018; 49:112-118. [DOI: 10.1016/j.ejmp.2018.05.014] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Revised: 05/10/2018] [Accepted: 05/11/2018] [Indexed: 11/24/2022] Open
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43
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Cho N, Tsiamas P, Velarde E, Tryggestad E, Jacques R, Berbeco R, McNutt T, Kazanzides P, Wong J. Validation of GPU-accelerated superposition-convolution dose computations for the Small Animal Radiation Research Platform. Med Phys 2018. [DOI: 10.1002/mp.12862] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Affiliation(s)
- Nathan Cho
- Department of Computer Science; Johns Hopkins University; Baltimore MD 21218 USA
| | - Panagiotis Tsiamas
- Department of Radiation Oncology; Brigham and Women's Hospital; Dana-Farber Cancer Institute and Harvard Medical School; Boston MA 02215 USA
| | - Esteban Velarde
- Department of Radiation Oncology and Molecular Radiation Sciences; Johns Hopkins University; Baltimore MD 21287 USA
| | - Erik Tryggestad
- Department of Radiation Oncology and Molecular Radiation Sciences; Johns Hopkins University; Baltimore MD 21287 USA
| | - Robert Jacques
- Department of Computer Science; Johns Hopkins University; Baltimore MD 21218 USA
| | - Ross Berbeco
- Department of Radiation Oncology; Brigham and Women's Hospital; Dana-Farber Cancer Institute and Harvard Medical School; Boston MA 02215 USA
| | - Todd McNutt
- Department of Radiation Oncology and Molecular Radiation Sciences; Johns Hopkins University; Baltimore MD 21287 USA
| | - Peter Kazanzides
- Department of Computer Science; Johns Hopkins University; Baltimore MD 21218 USA
| | - John Wong
- Department of Radiation Oncology and Molecular Radiation Sciences; Johns Hopkins University; Baltimore MD 21287 USA
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44
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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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45
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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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Liang LH, Tomic N, Vuong T, Aldelaijan S, Bekerat H, DeBlois F, Seuntjens J, Devic S. Physics aspects of the Papillon technique-Five decades later. Brachytherapy 2017; 17:234-243. [PMID: 29102741 DOI: 10.1016/j.brachy.2017.09.016] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Revised: 09/26/2017] [Accepted: 09/26/2017] [Indexed: 12/15/2022]
Abstract
PURPOSE The Papillon technique using 50-kVp soft X-rays to treat rectal adenocarcinomas was developed and clinically implemented in the 1960s. We describe differences between accurate dosimetry and clinical implementation of this technique that is extending from its very inception to date. METHODS AND MATERIALS A renaissance of the Papillon technique occurred with two recently introduced 50-kVp systems: Papillon+ by Ariane and a custom-made rectal applicator (consisting of a surface applicator inserted into a proctoscope) by iCAD's Xoft Axxent Electronic Brachytherapy (eBT) System (iCad, Inc., Sunnyvale, CA). In contrast to the initial design, we investigated the impact of introducing a plastic lid, which would provide more reproducible and more accurate dose delivery across the rectal adenocarcinoma patient population. We use both parallel-plate chamber and radiochromic film dosimeters to determine differences in basic dosimetry characteristics (beam half-value layers, outputs, percent depth doses, and profiles) between the Xoft Electronic Brachytherapy rectal applicator system with and without the plastic lid in place. RESULTS Compared to the open-cone applicator, the proposed applicator with the plastic lid produces a slightly harder (more penetrating) beam quality (half-value layer of 1.4 vs. 1.3-mm Al), but with reduced output (by 33%), and a slightly broader beam with flatness not worse than 3% and symmetry not worse than 2%. CONCLUSIONS In addition to characterizing beam properties modified by the possible introduction of the plastic cap, we also pointed out and addressed misconceptions in the use of radiochromic films for dose measurements at low-energy photon beams.
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Affiliation(s)
- Li Heng Liang
- Radiation Oncology Department, Jewish General Hospital, Montreal, Quebec, Canada; Medical Physics Unit, McGill University, Montreal, Quebec, Canada
| | - Nada Tomic
- Radiation Oncology Department, Jewish General Hospital, Montreal, Quebec, Canada; Medical Physics Unit, McGill University, Montreal, Quebec, Canada
| | - Te Vuong
- Radiation Oncology Department, Jewish General Hospital, Montreal, Quebec, Canada; Oncology Department, McGill University, Montreal, Quebec, Canada
| | - Saad Aldelaijan
- Medical Physics Unit, McGill University, Montreal, Quebec, Canada; Biological & Biomedical Engineering Department, Montreal Neurological Institute, Montréal, Québec, Canada; Biomedical Physics Department, King Faisal Specialist Hospital & Research Centre, Riyadh, Saudi Arabia
| | - Hamed Bekerat
- Radiation Oncology Department, Jewish General Hospital, Montreal, Quebec, Canada; Medical Physics Unit, McGill University, Montreal, Quebec, Canada
| | - Francois DeBlois
- Radiation Oncology Department, Jewish General Hospital, Montreal, Quebec, Canada; Medical Physics Unit, McGill University, Montreal, Quebec, Canada
| | - Jan Seuntjens
- Medical Physics Unit, McGill University, Montreal, Quebec, Canada; Oncology Department, McGill University, Montreal, Quebec, Canada
| | - Slobodan Devic
- Radiation Oncology Department, Jewish General Hospital, Montreal, Quebec, Canada; Medical Physics Unit, McGill University, Montreal, Quebec, Canada; Segal Cancer Centre, Jewish General Hospital, McGill University, Montréal, Québec, Canada.
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47
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Dose comparison between TG-43–based calculations and radiochromic film measurements of the Freiburg flap applicator used for high-dose-rate brachytherapy treatments of skin lesions. Brachytherapy 2017; 16:1065-1072. [DOI: 10.1016/j.brachy.2017.06.011] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2017] [Revised: 06/24/2017] [Accepted: 06/26/2017] [Indexed: 11/19/2022]
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48
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Calvo-Ortega JF, Pozo M, Moragues S, Casals J. Fast protocol for radiochromic film dosimetry using a cloud computing web application. Phys Med 2017; 39:1-8. [DOI: 10.1016/j.ejmp.2017.05.072] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/09/2017] [Revised: 05/22/2017] [Accepted: 05/31/2017] [Indexed: 11/29/2022] Open
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Commissioning of applicator-guided stereotactic body radiation therapy boost with high-dose-rate brachytherapy for advanced cervical cancer using radiochromic film dosimetry. Brachytherapy 2017; 16:893-902. [PMID: 28457741 DOI: 10.1016/j.brachy.2017.03.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Revised: 02/21/2017] [Accepted: 03/21/2017] [Indexed: 11/21/2022]
Abstract
PURPOSE To describe an EBT3 GAFCHROMIC film-based dosimetry method to be used in commissioning of a combined HDR brachytherapy (HDRB) and stereotactic body radiation therapy (SBRT) boost for treatment of advanced cervical cancer involving extensive residual disease after external beam treatment. METHODS AND MATERIALS A cube phantom was designed to firmly fit an intrauterine tandem applicator and EBT3 radiochromic film pieces. A high-risk clinical target volume (CTVHR, Total) was contoured with an extended arm at one side. The HDRB treatment was planned to cover the proximal CTVHR, Total with 7 Gy and the distal volume, referred to as CTVHR, Distal, was planned by SBRT for dose augmentation. After HDRB treatment delivery, SBRT treatment was delivered within 1 hour by image guidance using the applicator geometry. Intentional 1D and 2D misalignments were introduced to evaluate the effect on target volumes. In addition, effect of film reirradiation at different time gaps and dose levels was evaluated. RESULTS Film dosimetric accuracy, with up to 2 hours gap between irradiations, was shown to be unaffected. A 2%/2 mm gamma analysis between measured and planned doses showed agreement of >99%. Misalignments of more than 2 mm between applicator and SBRT isocenter resulted in suboptimal dose-volume histogram affecting mostly D98% and D90% of CTVHR, Distal. CONCLUSIONS Visualizing how target dose-volume metrics are affected by minor misalignments between SBRT and HDRB dose gradients, in light of achievable phantom-based experimental quality assurance level, encourages the clinical applicability of this technique. Radiochromic film was shown to be a valuable tool to commission procedures combining two different treatment planning systems and modalities with varying dose rates and energy ranges.
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50
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Pappas EP, Zoros E, Moutsatsos A, Peppa V, Zourari K, Karaiskos P, Papagiannis P. On the experimental validation of model-based dose calculation algorithms for192Ir HDR brachytherapy treatment planning. Phys Med Biol 2017; 62:4160-4182. [DOI: 10.1088/1361-6560/aa6a01] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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