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Queyrel É, Lanaret M, Khalil T, Al Gahatany M, Chaix R, Lemaire JJ, Moisset X, Chassin V, Brun L, Dedieu V, Biau J. [Frameless trigeminal neuralgia radiosurgery with a dedicated linear accelerator: From equipment commissioning to initial clinical results]. Cancer Radiother 2024; 28:164-173. [PMID: 38490925 DOI: 10.1016/j.canrad.2023.07.017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Revised: 07/07/2023] [Accepted: 07/18/2023] [Indexed: 03/17/2024]
Abstract
PURPOSE Radiosurgery for the treatment of trigeminal neuralgia delivers a very high dose in a single fraction, over a few millimeters, at a single isocenter placed along the nerve. We present here the different steps that have been performed to validate small beams by conical collimators, and report the clinical results of the first patients treated on Novalis Tx®, frameless. MATERIAL AND METHODS First, the geometric accuracy of 4 and 6mm conical collimators was evaluated using Winston-Lutz tests; then dosimetric data acquisition was performed using high spatial resolution detectors (PTW 60019 microdiamond and a PTW 60017 E-diode). The corrective factors of the TRS 483 report were applied to calculate the collimator aperture factors. These dosimetric data were then compared with the data implemented in the iPlan® treatment planning system. Then end-to-end tests were performed to control the entire treatment process using an anthropomorphic phantom "STEEV". Between 2020 and 2022, 18 patients were treated for refractory trigeminal neuralgia on Novalis Tx®, frameless, with Exactrac® repositioning. A total of 17 patients were evaluated (one was lost to follow-up) using the BNI score for pain assessment and MRI with a median follow-up of 12 months. RESULTS The quality criteria of geometric and dosimetric accuracy were met for the 6-mm cone but not for the 4-mm cone. All patients were treated with a 6-mm cone with a dose of 90Gy prescribed at the isocenter at the root entry zone. Initial pain control was obtained in 70.5% of our patients, and 53% maintained pain control with a median follow-up of 12 months. All recurrences occurred within 3 to 6 months after radiosurgery. No brainstem toxicity was observed. Six patients had non-disabling facial hypoesthesia, half of whom already had pretreatment hypoesthesia. CONCLUSION The treatment of trigeminal neuralgia on a dedicated linear accelerator is a highly technical treatment whose accuracy and safety are paramount. The physical measurements allowed the commissioning of the technique with a 6mm cone. Our first clinical results are in accordance with the literature.
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Affiliation(s)
- É Queyrel
- Département de radiothérapie, centre Jean-Perrin, 58, rue Montalembert, 63011 Clermont-Ferrand cedex 1, France
| | - M Lanaret
- Département de physique médicale, centre Jean-Perrin, Clermont-Ferrand, France
| | - T Khalil
- Service de neurochirurgie, CHU de Clermont-Ferrand, Clermont-Ferrand, France
| | - M Al Gahatany
- Service de neurochirurgie, CHU de Clermont-Ferrand, Clermont-Ferrand, France
| | - R Chaix
- Service de neurochirurgie, CHU de Clermont-Ferrand, Clermont-Ferrand, France
| | - J-J Lemaire
- Service de neurochirurgie, CHU de Clermont-Ferrand, Clermont-Ferrand, France; Institut Pascal, CNRS, Clermont-Auvergne INP, université Clermont-Auvergne, Clermont-Ferrand, France; Inserm U1240 IMoST, université Clermont-Auvergne, Clermont-Ferrand, France
| | - X Moisset
- Service de neurologie, Neuro-Dol, CHU de Clermont-Ferrand, université Clermont-Auvergne, Inserm U1107, Clermont-Ferrand, France
| | - V Chassin
- Département de physique médicale, centre Jean-Perrin, Clermont-Ferrand, France
| | - L Brun
- Département de radiothérapie, centre Jean-Perrin, 58, rue Montalembert, 63011 Clermont-Ferrand cedex 1, France
| | - V Dedieu
- Département de physique médicale, centre Jean-Perrin, Clermont-Ferrand, France; Institut Pascal, CNRS, Clermont-Auvergne INP, université Clermont-Auvergne, Clermont-Ferrand, France; Inserm U1240 IMoST, université Clermont-Auvergne, Clermont-Ferrand, France
| | - J Biau
- Département de radiothérapie, centre Jean-Perrin, 58, rue Montalembert, 63011 Clermont-Ferrand cedex 1, France; Institut Pascal, CNRS, Clermont-Auvergne INP, université Clermont-Auvergne, Clermont-Ferrand, France; Inserm U1240 IMoST, université Clermont-Auvergne, Clermont-Ferrand, France.
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Kannan M, Saminathan S, Chandraraj V, Raj DG, Ganesh KM. Evaluation of International Atomic Energy Agency Technical Report Series-483 Detector-specific Output Correction Factor for Various Collimator Systems. J Med Phys 2023; 48:281-288. [PMID: 37969152 PMCID: PMC10642599 DOI: 10.4103/jmp.jmp_59_23] [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: 04/28/2023] [Revised: 06/25/2023] [Accepted: 07/01/2023] [Indexed: 11/17/2023] Open
Abstract
Aim In this study, a 6MV flattening filter (FF) and 6MV FF Free (FFF) photon beam small-field output factors (OF) were measured with various collimators using different detectors. The corrected OFs were compared with the treatment planning system (TPS) calculated OFs. Materials and Methods OF measurements were performed with four different types of collimators: Varian Millennium multi-leaf collimator (MLC), Elekta Agility MLC, Apex micro-MLC (mMLC) and a stereotactic cone. Ten detectors (four ionization chambers and six diodes) were used to perform the OF measurements at a depth of 10 cm with a source-to-surface distance of 90 cm. The corrected OF was calculated from the measurements. The corrected OFs were compared with existing TPS-generated OFs. Results The use of detector-specific output correction factor (OCF) in the PTW diode P detector reduced the OF uncertainty by <4.1% for 1 cm × 1 cm Sclin. The corrected OF was compared with TPS calculated OF; the maximum variation with the IBA CC01 chamber was 3.75%, 3.72%, 1.16%, and 0.90% for 5 mm stereotactic cone, 0.49 cm × 0.49 cm Apex mMLC, 1 cm × 1 cm Agility MLC, and 1 cm × 1 cm Millennium MLC, respectively. Conclusion The technical report series-483 protocol recommends that detector-specific OCF should be used to calculate the corrected OF from the measured OF. The implementation of OCF in the TPS commissioning will reduce the small-field OF variation by <3% for any type of detector.
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Affiliation(s)
- Mageshraja Kannan
- Department of Radiation Physics, Kidwai Memorial Institute of Oncology, Bengaluru, Karnataka, India
| | - Sathiyan Saminathan
- Department of Radiation Physics, Kidwai Memorial Institute of Oncology, Bengaluru, Karnataka, India
| | - Varatharaj Chandraraj
- Department of Radiation Physics, Kidwai Memorial Institute of Oncology, Bengaluru, Karnataka, India
| | - D. Gowtham Raj
- Department of Radiation Physics, Kidwai Memorial Institute of Oncology, Bengaluru, Karnataka, India
| | - K. M. Ganesh
- Department of Radiation Physics, Kidwai Memorial Institute of Oncology, Bengaluru, Karnataka, India
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Esteves J, Pivot O, Ribouton J, Jalade P, Zouaoui A, Desbat L, Rit S, Blanc F, Haefeli G, Hopchev P, Galvan JM, Lu GN, Pittet P. A novel QA phantom based on scintillating fiber ribbons with implementation of 2D dose tomography for small-field radiotherapy. Med Phys 2023; 50:619-632. [PMID: 35933612 PMCID: PMC10087208 DOI: 10.1002/mp.15902] [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: 03/08/2022] [Revised: 07/10/2022] [Accepted: 07/20/2022] [Indexed: 01/25/2023] Open
Abstract
PURPOSE To develop a novel instrument for real-time quality assurance (QA) procedures in radiotherapy. The system implements a scintillation-based phantom and associated signal acquisition and processing modules and aims to monitor two-dimensional (2D) dose distributions of small fields. MATERIALS AND METHODS For the proposed phantom, we have designed and realized a prototype implementing six high-resolution tissue-equivalent scintillating fiber ribbons stacked with in-plane 30° rotated orientations from each other. Each ribbon output is coupled to a silicon photodiode linear array (with an element pitch of 400 μm) to detect scintillating signal, which represents the projected irradiation profile perpendicular to the ribbon's orientation. For the system providing six acquired projected dose profiles at different orientations, we have developed a two-step signal processing method to perform 2D dose reconstruction. The first step is to determine irradiation field geometry parameters using a tomographic geometry approach, and the second one is to perform specific penumbra estimation. The QA system prototype has been tested on a Novalis TrueBeam STX with a 6-MV photon beam for small elliptic fields defined by 5- and 10-mm cone collimators and for 10 × 10- and 20 × 10-mm2 rectangular fields defined by the micro-multileaf collimator. Gamma index analysis using EBT3 films as reference has been carried out with tight 2%-dose-difference (DD)/700-μm-distance-to-agreement (DTA) as well as 1%-DD/1-mm-DTA criteria for evaluating the system performances. The testing also includes an evaluation of the proposed two-step field reconstruction method in comparison with two conventional methods: filtered back projection (FBP) and simultaneous iterative reconstruction technique (SIRT). RESULTS The reconstructed 2D dose distributions have gamma index pass rates higher than 95% for all the tested configurations as compared with EBT3 film measurements with both 2%-DD/700-μm-DTA and 1%-DD/1-mm criteria. 2D global gamma analysis shows that the two-step and FBP radiation field reconstruction methods systematically outperform the SIRT approach. Moreover, higher gamma index success rates are obtained with the two-step method than with FBP in the case of the fields defined with the stereotactic cones. CONCLUSIONS The proposed small-field QA system makes a use of six water-equivalent scintillating detectors (fiber ribbons) to acquire dose distribution. The developed two-step signal processing method performs tomographic 2D dose reconstruction. A system prototype has been built and tested using hospital facilities with small rectangular and elliptic fields. Testing results show 2D reconstructed dose distributions with high accuracy and resolution. Such a system could potentially be an alternative approach to film dosimetry for small-field QA, which is still widely used as reference in clinical practice.
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Affiliation(s)
- Josué Esteves
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS, INSA Lyon, Ecole Centrale de Lyon, CPE Lyon, INL, UMR5270, Villeurbanne, France
| | - Odran Pivot
- Univ. Grenoble Alpes, CNRS, Grenoble INP, TIMC, Grenoble, France
| | - Julien Ribouton
- Service de Radiophysique et Radiovigilance, Centre Hospitalier Lyon Sud, Hospices Civils de Lyon, Pierre-Bénite, France
| | - Patrice Jalade
- Service de Radiophysique et Radiovigilance, Centre Hospitalier Lyon Sud, Hospices Civils de Lyon, Pierre-Bénite, France
| | - Abdelaali Zouaoui
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS, INSA Lyon, Ecole Centrale de Lyon, CPE Lyon, INL, UMR5270, Villeurbanne, France
| | - Laurent Desbat
- Univ. Grenoble Alpes, CNRS, Grenoble INP, TIMC, Grenoble, France
| | - Simon Rit
- Univ Lyon, INSA-Lyon, Université Claude Bernard Lyon 1, UJM-Saint Etienne, CNRS, Inserm, CREATIS UMR 5220, U1294, CREATIS, Lyon, France
| | | | | | | | - Jean-Marc Galvan
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS, INSA Lyon, Ecole Centrale de Lyon, CPE Lyon, INL, UMR5270, Villeurbanne, France
| | - Guo-Neng Lu
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS, INSA Lyon, Ecole Centrale de Lyon, CPE Lyon, INL, UMR5270, Villeurbanne, France
| | - Patrick Pittet
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS, INSA Lyon, Ecole Centrale de Lyon, CPE Lyon, INL, UMR5270, Villeurbanne, France
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Church C, Parsons D, Syme A. Investigating the impacts of intrafraction motion on dosimetric outcomes when treating small targets with virtual cones. J Appl Clin Med Phys 2021; 22:60-71. [PMID: 34272811 PMCID: PMC8364282 DOI: 10.1002/acm2.13285] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Revised: 04/09/2021] [Accepted: 04/23/2021] [Indexed: 12/31/2022] Open
Abstract
Purpose Intrafraction patient motion is a well‐documented phenomenon in radiation therapy. In stereotactic radiosurgery applications in which target sizes can be very small and dose gradients very steep, patient motion can significantly impact the magnitude and positional accuracy of the delivered dose. This work investigates the impact of intrafraction motion on dose metrics for small targets when treated with a virtual cone. Materials and Methods Monte Carlo simulations were performed to calculate dose kernels for treatment apertures ranging from 1 × 2.5 mm2 to 10 × 10 mm2. The phantom was an 8.2‐cm diameter sphere and isotropic voxels had lengths of 0.25 mm. Simulated treatments consisted of 3 arcs: 1 axial arc (360° gantry rotation, couch angle 0°) and 2 oblique arcs (180° gantry rotation, couch angle ±45°). Dose distributions were calculated via superposition of the rotated kernels. Two different collimator orientations were considered to create a virtual cone: (a) each treatment arc was delivered twice, once each with a static collimator angle of ±45°, and (b) each treatment arc was delivered once, with dynamic collimator rotation throughout the arc. Two different intrafraction motion patterns were considered: (a) constant linear motion and (b) sudden, persistent motion. The impact of motion on dose distributions for target sizes ranging from 1 to 10 mm diameter spheres was quantified as a function of the aperture size used to treat the lesions. Results The impact of motion on both the target and the surrounding tissue was a function of both aperture shape and target size. When a 0.5‐mm linear drift along each dimension occurred during treatment, targets ≥5 mm saw less than a 10% decrease in coverage by the prescription dose. Smaller apertures accrued larger penalties with respect to dosimetric hotspots seen in the tissues surrounding the target volume during intrafraction motion. For example, treating a 4‐mm‐sized target that undergoes 2.60 mm (3D vector) of continuous linear motion, the D5 in the concentric shells that extend 1, 2, and 3 mm from the surface of the target was 39%, 24%, and 14% smaller, respectively when comparing the delivery of a larger aperture (6 × 10 mm2) to a smaller aperture (2 × 5 mm2). Using a static collimator for shaping a virtual cone during treatment minimized the dosimetric impact of motion in the majority of cases. For example, the volume that is covered by 70% or more of the prescription dose is smaller in 60.4% of cases when using the static collimator. The volume covered by 50, and 30% or more of the prescription dose is also smaller when treating with a static collimator, but the clinical significance of this finding is unknown. Conclusions In this work, the dosimetric trade‐offs between aperture size and target size when irradiating with virtual cones has been demonstrated. These findings provide information about the tradeoffs between target coverage and normal tissue sparing that may help inform clinical decision making when treating smaller targets with virtual cones.
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Affiliation(s)
- Cody Church
- Department of Physics and Atmospheric Science, Dalhousie University, Halifax, NS, Canada
| | - David Parsons
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Alasdair Syme
- Department of Radiation Oncology, Department of Physics and Atmospheric Science, Dalhousie University, Halifax, NS, Canada
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Hermida-López M, Sánchez-Artuñedo D, Rodríguez M, Brualla L. Monte Carlo simulation of conical collimators for stereotactic radiosurgery with a 6 MV flattening-filter-free photon beam. Med Phys 2021; 48:3160-3171. [PMID: 33715167 DOI: 10.1002/mp.14837] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2020] [Revised: 02/19/2021] [Accepted: 03/08/2021] [Indexed: 11/07/2022] Open
Abstract
PURPOSE Conical collimators, or cones, are tertiary collimators that attach to a radiotherapy linac and are suited for the stereotactic radiosurgery treatment of small brain lesions. The small diameter of the most used cones makes difficult the acquisition of the dosimetry data needed for the commissioning of treatment planning systems. Although many publications report dosimetric data of conical collimators for stereotactic radiosurgery, most of the works use different setups, which complicates comparisons. In other cases, the cone output factors reported do not take into account the effect of the small cone diameter on the detector response. Finally, few data exist on the dosimetry of cones with flattening-filter-free (FFF) beams from modern linac models. This work aims at obtaining a dosimetric characterization of the conical collimators manufactured by Brainlab AG (Munich, Germany) in a 6 MV FFF beam from a TrueBeam STx linac (Varian Medical Systems). METHODS Percentage depth dose curves, lateral dose profiles and cone output factors were obtained using Monte Carlo simulations for the cones with diameters of 4, 5, 6, 7.5, 8, 10, 12.5, 15, 17.5, 20, 25, and 30 mm. The simulation of the linac head was carried out with the PRIMO Monte Carlo software, and the simulations of the cones and the water phantom were run with the general-purpose Monte Carlo code PENELOPE. The Monte Carlo model was validated by comparing the simulation results with measurements performed for the cones of 4, 5, and 7.5 mm of diameter using a stereotactic field diode, a microDiamond detector and EBT3 radiochromic film. In addition, for those cones, simulations and measurements were done for comparison purposes, by reproducing the experimental setups from the available publications. RESULTS The experimental data acquired for the cones of 4, 5, and 7.5 mm validated the developed Monte Carlo model. The simulations accurately reproduced the experimental depths of maximum dose and the dose ratio at 20- and 10-cm depth (PDD20/10 ). A good agreement was obtained between simulated and experimental lateral dose profiles: The differences in the full-width at half-maximum were smaller than 0.2 mm, and the differences in the penumbra 80%-20% were smaller than 0.25 mm. The difference between the simulated and the average of the experimental output factors for the cones of 4, 5, and 7.5 mm of diameter was 0.0%, 0.0%, and 3.0%, respectively, well within the statistical uncertainty of the simulations (4.4% with coverage factor k = 2). It was also found that the simulated cone output factors agreed within 2% with the average of output factors reported in the literature for a variety of setup conditions, detectors, beam qualities, and cone manufacturers. CONCLUSION A Monte Carlo model of cones for stereotactic radiosurgery has been developed and validated. The cone dosimetry dataset obtained in this work, consisting of percentage depth doses, lateral dose profiles and output factors, is useful to benchmark data acquired for the commissioning of cone-based radiosurgery treatment planning systems.
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Affiliation(s)
- Marcelino Hermida-López
- Servei de Física i Protecció Radiològica, Hospital Universitari Vall d'Hebron, Vall d'Hebron Barcelona Hospital Campus, Passeig Vall d'Hebron 119-129, Barcelona, 08035, Spain
| | - David Sánchez-Artuñedo
- Servei de Física i Protecció Radiològica, Hospital Universitari Vall d'Hebron, Vall d'Hebron Barcelona Hospital Campus, Passeig Vall d'Hebron 119-129, Barcelona, 08035, Spain
| | - Miguel Rodríguez
- Centro Médico Paitilla, Calle 53 y ave. Balboa, Panama City, Panama.,Instituto de Investigaciones Científicas y de Alta Tecnología, INDICASAT-AIP, City of Knowledge, Building 219, Panama City, Panama
| | - Lorenzo Brualla
- West German Proton Therapy Centre Essen (WPE), Hufelandstr. 55, Essen, 45147, Germany.,West German Cancer Centre (WTZ), Hufelandstr. 55, Essen, 45147, Germany.,Faculty of Medicine, University of Duisburg-Essen, Hufelandstr. 55, Essen, 45147, Germany
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Nedaie HA, Gholami S, Longo F, Banaee N, Hassani M, Sarfehnia A, Pang G. The effect of magnetic field on Linac based Stereotactic Radiosurgery dosimetric parameters. Biomed Phys Eng Express 2020; 7. [PMID: 35037902 DOI: 10.1088/2057-1976/abd2c4] [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: 05/27/2020] [Accepted: 12/11/2020] [Indexed: 11/11/2022]
Abstract
Objective: MR-linac machines are being developed for image-guided radiation therapy but the magnetic field of such machines could affect dose distributions. The purpose of this work was to evaluate the effect of a magnetic field on linac beam dosimetric parameters including penumbra for circular cones used in radiosurgery.Methods: Monte Carlo simulation was conducted for a linac machine with circular cones at 6 MV beam. A homogenous magnetic field of 1.5 T was applied transversely and parallel to the radiation beam. Percentage depth dose (PDD) and beam profiles in a water phantom with and without the magnetic field were calculated.Results: The results have shown that when the magnetic field is applied transversely, the PDDs in the water phantom differ in the buildup region and distant part of PDD curves. The beam profiles at three different depths are all significantly different from those without the magnetic field. The penumbra is greater when a magnetic field has been applied.Conclusion: Linear accelerator-based SRT and SRS use small circular cones. The beam penumbra for these cones can change in the presence of a magnetic field. The perturbation of dose distribution has been also observed in a patient plan due to the presence of a magnetic field. The results of this study show that dose distributions in the presence of a magnetic field must be considered for MR-guided radiotherapy treatments.
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Affiliation(s)
- H Ali Nedaie
- Radiation Oncology Research Center, Cancer Institute, Tehran University of Medical Sciences, Tehran, Iran.,Department of Medical Physics and Biomedical Engineering, Tehran University of Medical Sciences, Tehran, Iran
| | - Somayeh Gholami
- Radiation Oncology Research Center, Cancer Institute, Tehran University of Medical Sciences, Tehran, Iran.,Department of Medical Physics and Biomedical Engineering, Tehran University of Medical Sciences, Tehran, Iran
| | - Francesco Longo
- Department of Physics, University of Trieste and INFN Trieste, Italy
| | - Nooshin Banaee
- Department of Medical Radiation, Engineering Faculty, Central Tehran Branch, Islamic Azad University, Tehran, Iran
| | - Mohssen Hassani
- Radiation Oncology Research Center, Cancer Institute, Tehran University of Medical Sciences, Tehran, Iran
| | - Arman Sarfehnia
- Odette Cancer Centre, Department of Radiation Oncology, University of Toronto, 2075 Bayview Avenue, Toronto M4N 3M5, Canada
| | - G Pang
- Odette Cancer Centre, Department of Radiation Oncology, University of Toronto, 2075 Bayview Avenue, Toronto M4N 3M5, Canada
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Gul A, Fukuda S, Mizuno H, Taku N, Kakakhel MB, Mirza SM. Feasibility study of using Stereotactic Field Diode for field output factors measurement and evaluating three new detectors for small field relative dosimetry of 6 and 10 MV photon beams. J Appl Clin Med Phys 2020; 21:23-36. [PMID: 33078544 PMCID: PMC7700919 DOI: 10.1002/acm2.13007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Revised: 06/29/2020] [Accepted: 07/10/2020] [Indexed: 11/23/2022] Open
Abstract
This study assesses the feasibility of using stereotactic field diode (SFD) as an alternate to gaf chromic films for field output factor (FF) measurement and further evaluating three new detectors for small field dosimetry. Varian 21EX linear accelerator was used to generate 6 and 10 MV beams of nominal square fields ranging from 0.5 × 0.5 cm2 to 10 × 10 cm2. One passive (EBT3 films) and five active detectors including IBA RAZOR diode(RD), SFD, RAZOR nanochamber (RNC), pinpoint chamber (PTW31023), and semiflex chamber (PTW31010) were employed. FFs were measured using films and SFD while beam profiles and percentage depth dose (PDD) distribution were acquired with active detectors. Polarity (kpol) and recombination (ks) effects of ion chambers were determined and corrected for output ratio measurement. Correction factors (CF) of RD, RNC, and PTW31023 in axial and radial orientation were also measured. Stereotactic field diode measured FFs have shown good agreement with films (with difference of <1%). RD and RNC measured beam profiles were within 3% deviation from the SFD values. Variation in kpol with field size for RNC and PTW31023 was up to 4% and 0.4% (for fields ≥ 1 × 1 cm2), respectively, while variation in ks of PTW31023 was <0.2 %. The maximum values of CF have been calculated to be 5.2%, 2.0%, 13.6%, and 25.5% for RD, RNC, PTW31023‐axial, and PTW31023‐radial respectively. This study concludes that SFD with appropriate CFs as given in TRS 483 may be used for measuring FFs as an alternate to EBT3 films. Whereas RD and RNC may be used for beam profile and PDD measurement in small fields. Considering the limit of usability of 2%, RNC may be used without CF for FF measurement in the smallfields investigated in this study.
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Affiliation(s)
- Attia Gul
- QST Hospital, National Institutes for Quantum and Radiological Science and Technology, Chiba, Japan.,Department of Physics & Applied Mathematics, Pakistan Institute of Engineering and Applied Sciences (PIEAS), Islamabad, Pakistan
| | - Shigekazu Fukuda
- QST Hospital, National Institutes for Quantum and Radiological Science and Technology, Chiba, Japan
| | - Hideyuki Mizuno
- QST Hospital, National Institutes for Quantum and Radiological Science and Technology, Chiba, Japan
| | - Nakaji Taku
- QST Hospital, National Institutes for Quantum and Radiological Science and Technology, Chiba, Japan
| | - M Basim Kakakhel
- Department of Physics & Applied Mathematics, Pakistan Institute of Engineering and Applied Sciences (PIEAS), Islamabad, Pakistan
| | - Sikander M Mirza
- Department of Physics & Applied Mathematics, Pakistan Institute of Engineering and Applied Sciences (PIEAS), Islamabad, Pakistan
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8
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Pittet P, Esteves J, Galvan J, Lu G, Blanc F, Haefeli G, Hopchev P, Rit S, Desbat L, Ribouton J, Jalade P. SciFi detector and associated method for real-time determination of profile and output factor for small fields in stereotactic radiotherapy. Med Phys 2020; 47:1930-1939. [PMID: 31943221 PMCID: PMC7216919 DOI: 10.1002/mp.14019] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Revised: 01/08/2020] [Accepted: 01/09/2020] [Indexed: 11/06/2022] Open
Abstract
PURPOSE For determining small-field profile and output factor during stereotactic radiotherapy quality assurance (QA) procedures, we propose a novel system based on the scintillating fiber (SciFi) detector with output image acquisition and processing to allow real-time monitoring of profile and output factor. MATERIALS AND METHODS The employed detector is a SciFi detector made of tissue-equivalent scintillating plastic fibers arranged in 6-layer fiber ribbons with a fiber pitch of 275 μm in each layer. The scintillating signal at the detector output is acquired by a sCMOS (scientific complementary metal-oxide-semiconductor) camera and represents the projected field profile along the fibers axis. An iterative reconstruction method of the field from its projected profile based on a priori knowledge of some features of the radiation field defined by the stereotactic cones is suggested. The detector with implemented data processing has been tested in clinical conditions, for determining beam profiles and output factors, using cone collimators of different sizes from 4 to 15 mm diameter. The detector under test was placed at 1.4 cm depth and 98.6 cm source to surface distance (SSD) in a water-equivalent phantom and irradiated by a 6 MV photon beam. RESULTS The reconstructed field profiles obtained from the detector are coherent with data from EBT3 radiochromic films, with differences within ±0.32 mm for both the FWHM and the penumbra region. For real-time determination of the field output factor, the measured data are also in good agreement with data independently determined by the French Institute for Radiological Protection and Nuclear Safety (IRSN) based on radiochromic films and thermoluminescent 1 × 1 mm2 micro-cubes dosimeters (TLD). The differences are within ±1.6% for all the tested cone sizes. CONCLUSIONS We propose and have tested a SciFi plastic scintillating detector with an optimized signal processing method to characterize small fields defined by cone collimators. It allows the determination of key field parameters such as full width at half maximum (FWHM) and field output factors. The results are consistent with those independently measured using TLD and radiochromic films. As the SciFi detector does not require a correction factor, it is in line with the International Atomic Energy Agency (IAEA) and the American Association of Physicists in Medicine (AAPM) TRS-483 recommendations, and can be suitable for online QA of small radiation fields used in photon beam radiotherapy, and is compatible with MRI-LINAC.
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Affiliation(s)
- P. Pittet
- Institut des Nanotechnologies de Lyon INLCNRS UMR5270Université de LyonUniversité Claude Bernard Lyon 1F‐69100VilleurbanneFrance
| | - J. Esteves
- Institut des Nanotechnologies de Lyon INLCNRS UMR5270Université de LyonUniversité Claude Bernard Lyon 1F‐69100VilleurbanneFrance
| | - J.‐M. Galvan
- Institut des Nanotechnologies de Lyon INLCNRS UMR5270Université de LyonUniversité Claude Bernard Lyon 1F‐69100VilleurbanneFrance
| | - G.‐N. Lu
- Institut des Nanotechnologies de Lyon INLCNRS UMR5270Université de LyonUniversité Claude Bernard Lyon 1F‐69100VilleurbanneFrance
| | - F. Blanc
- Laboratoire de Physique des Hautes Energies LPHEEPFLCH‐1015LausanneSwitzerland
| | - G. Haefeli
- Laboratoire de Physique des Hautes Energies LPHEEPFLCH‐1015LausanneSwitzerland
| | - P. Hopchev
- Laboratoire de Physique des Hautes Energies LPHEEPFLCH‐1015LausanneSwitzerland
| | - S. Rit
- University LyonINSA‐LyonUniversité Claude Bernard Lyon 1CNRS UMR 5220Inserm U1206CREATISLyonFrance
| | - L. Desbat
- University Grenoble AlpesCNRSGrenoble INPTIMC‐IMAGF‐38000GrenobleFrance
| | - J. Ribouton
- Service de Radiophysique et RadiovigilanceHospices Civils de LyonCentre Hospitalier Lyon SudF‐69495Pierre‐BéniteFrance
| | - P. Jalade
- Service de Radiophysique et RadiovigilanceHospices Civils de LyonCentre Hospitalier Lyon SudF‐69495Pierre‐BéniteFrance
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Cardon T, Garnier N, Amblard R, Villeneuve R, Gerard A, Benabdesselam M, Serrano B. 82 Output ratios measurements in stereotactic radiosurgery using cones with a 6 MV FFF beam: comparison between 8 detectors. Phys Med 2019. [DOI: 10.1016/j.ejmp.2019.09.163] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
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10
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Fukui Y, Hamada Y, Noma K, Harada N. [Characterization of Small Volume Plastic Scintillation Detector]. Nihon Hoshasen Gijutsu Gakkai Zasshi 2019; 75:652-658. [PMID: 31327776 DOI: 10.6009/jjrt.2019_jsrt_75.7.652] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Some radiation detectors are used for quality assurance and measured to radiation dose for high precision external beam radiotherapy. Recently, plastic scintillation detectors for MeV X-ray measurement are commercially released. The purpose of this study was to evaluate the performance of a commercial plastic scintillation detector with respect to the dose linearity, dose rate dependence, and the output coefficient compared the ionization chamber and the semiconductor detector using each different X-ray energy with or without flattening filter. The result that the dose linearity of each detector showed a linear response in any detectors. Dose rate dependence of plastic scintillation detector was increased when setting dose rate was changed, especially setting to low dose rate. The output coefficient of plastic scintillation detector was equivalent as that of the semiconductor detector even in smallest irradiation field. In conclusion, it was suggested that the plastic scintillation detector is a suitable detector in dose verification measurements for high precision external beam radiotherapy, although we must be with care to low dose rate measurements.
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Affiliation(s)
- Yusuke Fukui
- Radiology Service, Shiga University of Medical Science Hospital
| | - Yuto Hamada
- Radiology Service, Shiga University of Medical Science Hospital (Current address: Canon Medical Systems Corporation)
| | - Kazuo Noma
- Radiology Service, Shiga University of Medical Science Hospital
| | - Naoki Harada
- Radiology Service, Shiga University of Medical Science Hospital
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