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Jean-françois Adam - One of the best experts on this subject based on the ideXlab platform.

  • Towards in vivo dosimetry for contrast enhanced synchrotron Stereotactic Radiation Therapy based on iodine x-ray spectroscopy
    Biomedical Physics & Engineering Express, 2018
    Co-Authors: Dimitri Reynard, Richard P. Hugtenburg, François Estève, Jean-françois Adam
    Abstract:

    The first trial applications of Contrast-Enhanced Synchrotron Stereotactic Radiation Therapy (SSRT) is underway since June 2012 at the European Synchrotron Radiation Facility (ESRF) in Grenoble (France). The phase I-II clinical trial is designed to test the feasibility and safety of SSRT through a dose escalation protocol. Contrast enhanced radioTherapy achieves localized dose enhancement due to higher photoelectric effect rate in the target. This increase is obtained through the preferential uptake of high-Z media (iodine) in the tumoral area combined with irRadiations with medium energy synchrotron x-rays. In vivo dosimetry (i.e. experimental dosimetry in real time during the treatment) would be a serious added value to the project, in terms of online dose monitoring and quality control. It is challenging to perform in vivo dosimetry with the currently available conventional clinical techniques. In this work we investigated a method using x-ray fluorescence detection to derive the iodine concentration contained in a tumor during the treatment of a patient, as a first step towards in vivo dosimetry. A mean iodine concentration of 0.33 ± 0.22 mg/ml has been retrieved in the tumor of the patient compared to 2 mg/ml expected would correspond to 3% local dose enhancement in the tumor. Further work will be performed to improve the attenuation correction method. The expected amount of iodine should be 2 mg/ml in the tumor (20% dose enhancement). This method is suitable to detect iodine in the target but has some problem in quantifying the real amount of iodine present during the irRadiation.

  • Dosimetry protocol for the forthcoming clinical trials in synchrotron Stereotactic Radiation Therapy (SSRT).
    Medical Physics, 2011
    Co-Authors: Yolanda Prezado, François Estève, Hélène Elleaume, P. Berkvens, Mathias Vautrin, I. Martínez-rovira, Alberto Bravin, Jean-françois Adam
    Abstract:

    PURPOSE: An adequate dosimetry protocol for synchrotron Radiation and the specific features of the ID17 Biomedical Beamline at the European Synchrotron Radiation Facility are essential for the preparation of the forthcoming clinical trials in the synchrotron Stereotactic Radiation Therapy (SSRT). The main aim of this work is the definition of a suitable protocol based on standards of dose absorbed to water. It must allow measuring the absolute dose with an uncertainty within the recommended limits for patient treatment of 2%-5%. METHODS: Absolute dosimetry is performed with a thimble ionization chamber (PTW semiflex 31002) whose center is positioned at 2 g cm(-2) equivalent depth in water. Since the available synchrotron beam at the ESRF Biomedical Beamline has a maximum height of 3 mm, a scanning method was employed to mimic a uniform exposition of the ionization chamber. The scanning method has been shown to be equivalent to a broad beam irRadiation. Different correction factors have been assessed by using Monte Carlo simulations. RESULTS: The absolute dose absorbed to water at 80 keV was measured in reference conditions with a 2% global uncertainty, within the recommended limits. The dose rate was determined to be in the range between 14 and 18 Gy/min, that is to say, a factor two to three times higher than the 6 Gy/min achievable in RapidArc or VMAT machines. The dose absorbed to water was also measured in a RW3 solid water phantom. This phantom is suitable for quality assurance purposes since less than 2% average difference with respect to the water phantom measurements was found. In addition, output factors were assessed for different field sizes. CONCLUSIONS: A dosimetry protocol adequate for the specific features of the SSRT technique has been developed. This protocol allows measuring the absolute dose absorbed to water with an accuracy of 2%. It is therefore satisfactory for patient treatment.

  • Dosimetry protocol for the forthcoming clinical trials in synchrotron Stereotactic Radiation Therapy (SSRT)
    Medical physics, 2011
    Co-Authors: Yolanda Prezado, François Estève, Hélène Elleaume, P. Berkvens, Mathias Vautrin, I. Martínez-rovira, Alberto Bravin, Jean-françois Adam
    Abstract:

    Purpose: An adequate dosimetry protocol for synchrotron Radiation and the specific features of the ID17 Biomedical Beamline at the European Synchrotron Radiation Facility are essential for the preparation of the forthcoming clinical trials in the synchrotron Stereotactic Radiation Therapy (SSRT). The main aim of this work is the definition of a suitable protocol based on standards of dose absorbed to water. It must allow measuring the absolute dose with an uncertainty within the recommended limits for patient treatment of 2%-5%. Methods: Absolute dosimetry is performed with a thimble ionization chamber (PTW semiflex 31002) whose center is positioned at 2 g cm{sup -2} equivalent depth in water. Since the available synchrotron beam at the ESRF Biomedical Beamline has a maximum height of 3 mm, a scanning method was employed to mimic a uniform exposition of the ionization chamber. The scanning method has been shown to be equivalent to a broad beam irRadiation. Different correction factors have been assessed by using Monte Carlo simulations. Results: The absolute dose absorbed to water at 80 keV was measured in reference conditions with a 2% global uncertainty, within the recommended limits. The dose rate was determined to be in the range between 14 and 18more » Gy/min, that is to say, a factor two to three times higher than the 6 Gy/min achievable in RapidArc or VMAT machines. The dose absorbed to water was also measured in a RW3 solid water phantom. This phantom is suitable for quality assurance purposes since less than 2% average difference with respect to the water phantom measurements was found. In addition, output factors were assessed for different field sizes. Conclusions: A dosimetry protocol adequate for the specific features of the SSRT technique has been developed. This protocol allows measuring the absolute dose absorbed to water with an accuracy of 2%. It is therefore satisfactory for patient treatment.« less

François Estève - One of the best experts on this subject based on the ideXlab platform.

  • Towards in vivo dosimetry for contrast enhanced synchrotron Stereotactic Radiation Therapy based on iodine x-ray spectroscopy
    Biomedical Physics & Engineering Express, 2018
    Co-Authors: Dimitri Reynard, Richard P. Hugtenburg, François Estève, Jean-françois Adam
    Abstract:

    The first trial applications of Contrast-Enhanced Synchrotron Stereotactic Radiation Therapy (SSRT) is underway since June 2012 at the European Synchrotron Radiation Facility (ESRF) in Grenoble (France). The phase I-II clinical trial is designed to test the feasibility and safety of SSRT through a dose escalation protocol. Contrast enhanced radioTherapy achieves localized dose enhancement due to higher photoelectric effect rate in the target. This increase is obtained through the preferential uptake of high-Z media (iodine) in the tumoral area combined with irRadiations with medium energy synchrotron x-rays. In vivo dosimetry (i.e. experimental dosimetry in real time during the treatment) would be a serious added value to the project, in terms of online dose monitoring and quality control. It is challenging to perform in vivo dosimetry with the currently available conventional clinical techniques. In this work we investigated a method using x-ray fluorescence detection to derive the iodine concentration contained in a tumor during the treatment of a patient, as a first step towards in vivo dosimetry. A mean iodine concentration of 0.33 ± 0.22 mg/ml has been retrieved in the tumor of the patient compared to 2 mg/ml expected would correspond to 3% local dose enhancement in the tumor. Further work will be performed to improve the attenuation correction method. The expected amount of iodine should be 2 mg/ml in the tumor (20% dose enhancement). This method is suitable to detect iodine in the target but has some problem in quantifying the real amount of iodine present during the irRadiation.

  • Synchrotron Stereotactic Radiation Therapy: A Report on Phase 1/2 Clinical Trial Achievements, Ongoing Developments, and Long-Term Prospects
    International Journal of Radiation Oncology*Biology*Physics, 2016
    Co-Authors: J.f. Adam, François Estève, Jacques Balosso, Michel Renier, Hélène Elleaume, P. Berkvens, Christian Nemoz, Thierry Brochard, A Tessier, Camille Verry
    Abstract:

    International audienceTherapeutic applications of synchrotron X rays are becoming a reality. The first phase I/II clinical study of synchrotron Stereotactic Radiation Therapy (SSRT) consists of a dose-escalation protocol to show the feasibility and safety of the technique. Oligo-brain-metastatic patients have been irradiated since June 2012 using 80 keV high-flux quasiparallel monochromatic x-ray beams, in the presence of iodinated compounds injected immediately before irRadiation. A localized dose enhancement occurs in the target at this energy, due to the photoelectric effect

  • Dosimetry protocol for the forthcoming clinical trials in synchrotron Stereotactic Radiation Therapy (SSRT).
    Medical Physics, 2011
    Co-Authors: Yolanda Prezado, François Estève, Hélène Elleaume, P. Berkvens, Mathias Vautrin, I. Martínez-rovira, Alberto Bravin, Jean-françois Adam
    Abstract:

    PURPOSE: An adequate dosimetry protocol for synchrotron Radiation and the specific features of the ID17 Biomedical Beamline at the European Synchrotron Radiation Facility are essential for the preparation of the forthcoming clinical trials in the synchrotron Stereotactic Radiation Therapy (SSRT). The main aim of this work is the definition of a suitable protocol based on standards of dose absorbed to water. It must allow measuring the absolute dose with an uncertainty within the recommended limits for patient treatment of 2%-5%. METHODS: Absolute dosimetry is performed with a thimble ionization chamber (PTW semiflex 31002) whose center is positioned at 2 g cm(-2) equivalent depth in water. Since the available synchrotron beam at the ESRF Biomedical Beamline has a maximum height of 3 mm, a scanning method was employed to mimic a uniform exposition of the ionization chamber. The scanning method has been shown to be equivalent to a broad beam irRadiation. Different correction factors have been assessed by using Monte Carlo simulations. RESULTS: The absolute dose absorbed to water at 80 keV was measured in reference conditions with a 2% global uncertainty, within the recommended limits. The dose rate was determined to be in the range between 14 and 18 Gy/min, that is to say, a factor two to three times higher than the 6 Gy/min achievable in RapidArc or VMAT machines. The dose absorbed to water was also measured in a RW3 solid water phantom. This phantom is suitable for quality assurance purposes since less than 2% average difference with respect to the water phantom measurements was found. In addition, output factors were assessed for different field sizes. CONCLUSIONS: A dosimetry protocol adequate for the specific features of the SSRT technique has been developed. This protocol allows measuring the absolute dose absorbed to water with an accuracy of 2%. It is therefore satisfactory for patient treatment.

  • Dosimetry protocol for the forthcoming clinical trials in synchrotron Stereotactic Radiation Therapy (SSRT)
    Medical physics, 2011
    Co-Authors: Yolanda Prezado, François Estève, Hélène Elleaume, P. Berkvens, Mathias Vautrin, I. Martínez-rovira, Alberto Bravin, Jean-françois Adam
    Abstract:

    Purpose: An adequate dosimetry protocol for synchrotron Radiation and the specific features of the ID17 Biomedical Beamline at the European Synchrotron Radiation Facility are essential for the preparation of the forthcoming clinical trials in the synchrotron Stereotactic Radiation Therapy (SSRT). The main aim of this work is the definition of a suitable protocol based on standards of dose absorbed to water. It must allow measuring the absolute dose with an uncertainty within the recommended limits for patient treatment of 2%-5%. Methods: Absolute dosimetry is performed with a thimble ionization chamber (PTW semiflex 31002) whose center is positioned at 2 g cm{sup -2} equivalent depth in water. Since the available synchrotron beam at the ESRF Biomedical Beamline has a maximum height of 3 mm, a scanning method was employed to mimic a uniform exposition of the ionization chamber. The scanning method has been shown to be equivalent to a broad beam irRadiation. Different correction factors have been assessed by using Monte Carlo simulations. Results: The absolute dose absorbed to water at 80 keV was measured in reference conditions with a 2% global uncertainty, within the recommended limits. The dose rate was determined to be in the range between 14 and 18more » Gy/min, that is to say, a factor two to three times higher than the 6 Gy/min achievable in RapidArc or VMAT machines. The dose absorbed to water was also measured in a RW3 solid water phantom. This phantom is suitable for quality assurance purposes since less than 2% average difference with respect to the water phantom measurements was found. In addition, output factors were assessed for different field sizes. Conclusions: A dosimetry protocol adequate for the specific features of the SSRT technique has been developed. This protocol allows measuring the absolute dose absorbed to water with an accuracy of 2%. It is therefore satisfactory for patient treatment.« less

Seung Jae Huh - One of the best experts on this subject based on the ideXlab platform.

  • Physical properties of new collimator cone system for Stereotactic Radiation Therapy developed in samsung medical center.
    International Journal of Radiation Oncology Biology Physics, 2000
    Co-Authors: Dae Yong Kim, Yong Chan Ahn, Dong Rak Choi, In Hwan Yeo, Seung Jae Huh
    Abstract:

    Abstract Purpose: A new collimator cone system has been developed at the Samsung Medical Center that overcomes some of the limitations of present commercially supplied collimator cones. The physical properties of the newly developed cone system are described in this report. Methods and Materials: The new cones have relatively larger aperture sizes (3.0–7.0 cm in diameter) and are 16 cm in length. Each new cone is fabricated with cerrobend alloy melted and poured into a stainless steel housing that is permanently fixed to a mounting plate. The mounting plate of the new cone is designed to insert into the wedge mount slot of the gantry head. The mechanical accuracy of the central axis of the cone pointing to the isocenter was tested using film, a steel ball positioned at the isocenter by the mechanical isocenter device. For the evaluation of beam flatness and penumbra, off-axis ratios at 5 cm depth were measured by film dosimetry using polystyrene phantom. Results: The average error of the mechanical isocenter was 0.27 mm (± 0.16 mm). The beam flatness was excellent in the central region of the beam, and the average penumbra width was 3.35 mm (± 0.25 mm). The new cone design has more clearance between the patient’s head and the gantry, and can more easily be removed from the gantry head because it slides in and out of the wedge slot. This facilitates changing cone sizes during one treatment session, and makes the process of double exposure port films easier. Conclusions: A new collimator cone system for Stereotactic Radiation Therapy has been developed. The mechanical accuracy and physical properties are satisfactory for clinical use, and the new design permits a wider range of clinical applications for Stereotactic Radiation Therapy.

  • Design and development of new collimator cones for fractionated Stereotactic Radiation Therapy in Samsung medical center
    International journal of radiation oncology biology physics, 1999
    Co-Authors: Yong Chan Ahn, Dae Yong Kim, Dong Rak Choi, Seung Jae Huh, Hoon Lim, Y. Park, Moon Kyung Kim
    Abstract:

    Abstract Purpose: In Stereotactic radioTherapy using X-Knife system, the commercially supplied collimator cone system had a few mechanical limitations. The authors have developed new collimator cones to overcome these limitations and named them “SMC type” collimator cones. Methods: We made use of cadmium-free cerrobend alloy within the stainless steel cylinder housing. We made nine cones of relatively larger sizes (3.0 cm to 7.0 cm in diameter) and of shorter length with bigger clearance from the isocenter than the commercial cones. The cone housing and the collimator cones were designed to insert into the wedge mount of the gantry head to enable double-exposure linac-gram taking. Results: The mechanical accuracy of pointing to the isocenter was tested by ball test and cone rotation test, and the dosimetric measurements were performed, all of which were with satisfactory results. A new innovative quality assurance procedure using linac-grams on the patients at the actual treatment setup was attempted after taking 10 sets of AP and lateral linac-grams and the overall mechanical isocenter accuracy was excellent (average error = 0.4 ± 0.2 mm). Conclusions: We have developed the SMC type collimator cone system mainly for fractionated Stereotactic Radiation Therapy use with our innovative ideas. The new cones’ mechanical accuracy and physical properties were satisfactory for clinical use, and the verification of the isocenter accuracy on the actual treatment setup has become possible.

P. Berkvens - One of the best experts on this subject based on the ideXlab platform.

  • Synchrotron Stereotactic Radiation Therapy: A Report on Phase 1/2 Clinical Trial Achievements, Ongoing Developments, and Long-Term Prospects
    2016
    Co-Authors: J.f. Adam, Jacques Balosso, Michel Renier, Hélène Elleaume, P. Berkvens, Christian Nemoz, Thierry Brochard, A Tessier, F. Estève, Camille Verry
    Abstract:

    Therapeutic applications of synchrotron X rays are becoming a reality. The first phase I/II clinical study of synchrotron Stereotactic Radiation Therapy (SSRT) consists of a dose-escalation protocol to show the feasibility and safety of the technique. Oligo-brain-metastatic patients have been irradiated since June 2012 using 80 keV high-flux quasiparallel monochromatic x-ray beams, in the presence of iodinated compounds injected immediately before irRadiation. A localized dose enhancement occurs in the target at this energy, due to the photoelectric effect.

  • Synchrotron Stereotactic Radiation Therapy: A Report on Phase 1/2 Clinical Trial Achievements, Ongoing Developments, and Long-Term Prospects
    International Journal of Radiation Oncology*Biology*Physics, 2016
    Co-Authors: J.f. Adam, François Estève, Jacques Balosso, Michel Renier, Hélène Elleaume, P. Berkvens, Christian Nemoz, Thierry Brochard, A Tessier, Camille Verry
    Abstract:

    International audienceTherapeutic applications of synchrotron X rays are becoming a reality. The first phase I/II clinical study of synchrotron Stereotactic Radiation Therapy (SSRT) consists of a dose-escalation protocol to show the feasibility and safety of the technique. Oligo-brain-metastatic patients have been irradiated since June 2012 using 80 keV high-flux quasiparallel monochromatic x-ray beams, in the presence of iodinated compounds injected immediately before irRadiation. A localized dose enhancement occurs in the target at this energy, due to the photoelectric effect

  • Dosimetry protocol for the forthcoming clinical trials in synchrotron Stereotactic Radiation Therapy (SSRT).
    Medical Physics, 2011
    Co-Authors: Yolanda Prezado, François Estève, Hélène Elleaume, P. Berkvens, Mathias Vautrin, I. Martínez-rovira, Alberto Bravin, Jean-françois Adam
    Abstract:

    PURPOSE: An adequate dosimetry protocol for synchrotron Radiation and the specific features of the ID17 Biomedical Beamline at the European Synchrotron Radiation Facility are essential for the preparation of the forthcoming clinical trials in the synchrotron Stereotactic Radiation Therapy (SSRT). The main aim of this work is the definition of a suitable protocol based on standards of dose absorbed to water. It must allow measuring the absolute dose with an uncertainty within the recommended limits for patient treatment of 2%-5%. METHODS: Absolute dosimetry is performed with a thimble ionization chamber (PTW semiflex 31002) whose center is positioned at 2 g cm(-2) equivalent depth in water. Since the available synchrotron beam at the ESRF Biomedical Beamline has a maximum height of 3 mm, a scanning method was employed to mimic a uniform exposition of the ionization chamber. The scanning method has been shown to be equivalent to a broad beam irRadiation. Different correction factors have been assessed by using Monte Carlo simulations. RESULTS: The absolute dose absorbed to water at 80 keV was measured in reference conditions with a 2% global uncertainty, within the recommended limits. The dose rate was determined to be in the range between 14 and 18 Gy/min, that is to say, a factor two to three times higher than the 6 Gy/min achievable in RapidArc or VMAT machines. The dose absorbed to water was also measured in a RW3 solid water phantom. This phantom is suitable for quality assurance purposes since less than 2% average difference with respect to the water phantom measurements was found. In addition, output factors were assessed for different field sizes. CONCLUSIONS: A dosimetry protocol adequate for the specific features of the SSRT technique has been developed. This protocol allows measuring the absolute dose absorbed to water with an accuracy of 2%. It is therefore satisfactory for patient treatment.

  • Dosimetry protocol for the forthcoming clinical trials in synchrotron Stereotactic Radiation Therapy (SSRT)
    Medical physics, 2011
    Co-Authors: Yolanda Prezado, François Estève, Hélène Elleaume, P. Berkvens, Mathias Vautrin, I. Martínez-rovira, Alberto Bravin, Jean-françois Adam
    Abstract:

    Purpose: An adequate dosimetry protocol for synchrotron Radiation and the specific features of the ID17 Biomedical Beamline at the European Synchrotron Radiation Facility are essential for the preparation of the forthcoming clinical trials in the synchrotron Stereotactic Radiation Therapy (SSRT). The main aim of this work is the definition of a suitable protocol based on standards of dose absorbed to water. It must allow measuring the absolute dose with an uncertainty within the recommended limits for patient treatment of 2%-5%. Methods: Absolute dosimetry is performed with a thimble ionization chamber (PTW semiflex 31002) whose center is positioned at 2 g cm{sup -2} equivalent depth in water. Since the available synchrotron beam at the ESRF Biomedical Beamline has a maximum height of 3 mm, a scanning method was employed to mimic a uniform exposition of the ionization chamber. The scanning method has been shown to be equivalent to a broad beam irRadiation. Different correction factors have been assessed by using Monte Carlo simulations. Results: The absolute dose absorbed to water at 80 keV was measured in reference conditions with a 2% global uncertainty, within the recommended limits. The dose rate was determined to be in the range between 14 and 18more » Gy/min, that is to say, a factor two to three times higher than the 6 Gy/min achievable in RapidArc or VMAT machines. The dose absorbed to water was also measured in a RW3 solid water phantom. This phantom is suitable for quality assurance purposes since less than 2% average difference with respect to the water phantom measurements was found. In addition, output factors were assessed for different field sizes. Conclusions: A dosimetry protocol adequate for the specific features of the SSRT technique has been developed. This protocol allows measuring the absolute dose absorbed to water with an accuracy of 2%. It is therefore satisfactory for patient treatment.« less

Hélène Elleaume - One of the best experts on this subject based on the ideXlab platform.

  • Synchrotron Stereotactic Radiation Therapy: A Report on Phase 1/2 Clinical Trial Achievements, Ongoing Developments, and Long-Term Prospects
    2016
    Co-Authors: J.f. Adam, Jacques Balosso, Michel Renier, Hélène Elleaume, P. Berkvens, Christian Nemoz, Thierry Brochard, A Tessier, F. Estève, Camille Verry
    Abstract:

    Therapeutic applications of synchrotron X rays are becoming a reality. The first phase I/II clinical study of synchrotron Stereotactic Radiation Therapy (SSRT) consists of a dose-escalation protocol to show the feasibility and safety of the technique. Oligo-brain-metastatic patients have been irradiated since June 2012 using 80 keV high-flux quasiparallel monochromatic x-ray beams, in the presence of iodinated compounds injected immediately before irRadiation. A localized dose enhancement occurs in the target at this energy, due to the photoelectric effect.

  • Synchrotron Stereotactic Radiation Therapy: A Report on Phase 1/2 Clinical Trial Achievements, Ongoing Developments, and Long-Term Prospects
    International Journal of Radiation Oncology*Biology*Physics, 2016
    Co-Authors: J.f. Adam, François Estève, Jacques Balosso, Michel Renier, Hélène Elleaume, P. Berkvens, Christian Nemoz, Thierry Brochard, A Tessier, Camille Verry
    Abstract:

    International audienceTherapeutic applications of synchrotron X rays are becoming a reality. The first phase I/II clinical study of synchrotron Stereotactic Radiation Therapy (SSRT) consists of a dose-escalation protocol to show the feasibility and safety of the technique. Oligo-brain-metastatic patients have been irradiated since June 2012 using 80 keV high-flux quasiparallel monochromatic x-ray beams, in the presence of iodinated compounds injected immediately before irRadiation. A localized dose enhancement occurs in the target at this energy, due to the photoelectric effect

  • Dosimetry protocol for the forthcoming clinical trials in synchrotron Stereotactic Radiation Therapy (SSRT).
    Medical Physics, 2011
    Co-Authors: Yolanda Prezado, François Estève, Hélène Elleaume, P. Berkvens, Mathias Vautrin, I. Martínez-rovira, Alberto Bravin, Jean-françois Adam
    Abstract:

    PURPOSE: An adequate dosimetry protocol for synchrotron Radiation and the specific features of the ID17 Biomedical Beamline at the European Synchrotron Radiation Facility are essential for the preparation of the forthcoming clinical trials in the synchrotron Stereotactic Radiation Therapy (SSRT). The main aim of this work is the definition of a suitable protocol based on standards of dose absorbed to water. It must allow measuring the absolute dose with an uncertainty within the recommended limits for patient treatment of 2%-5%. METHODS: Absolute dosimetry is performed with a thimble ionization chamber (PTW semiflex 31002) whose center is positioned at 2 g cm(-2) equivalent depth in water. Since the available synchrotron beam at the ESRF Biomedical Beamline has a maximum height of 3 mm, a scanning method was employed to mimic a uniform exposition of the ionization chamber. The scanning method has been shown to be equivalent to a broad beam irRadiation. Different correction factors have been assessed by using Monte Carlo simulations. RESULTS: The absolute dose absorbed to water at 80 keV was measured in reference conditions with a 2% global uncertainty, within the recommended limits. The dose rate was determined to be in the range between 14 and 18 Gy/min, that is to say, a factor two to three times higher than the 6 Gy/min achievable in RapidArc or VMAT machines. The dose absorbed to water was also measured in a RW3 solid water phantom. This phantom is suitable for quality assurance purposes since less than 2% average difference with respect to the water phantom measurements was found. In addition, output factors were assessed for different field sizes. CONCLUSIONS: A dosimetry protocol adequate for the specific features of the SSRT technique has been developed. This protocol allows measuring the absolute dose absorbed to water with an accuracy of 2%. It is therefore satisfactory for patient treatment.

  • Dosimetry protocol for the forthcoming clinical trials in synchrotron Stereotactic Radiation Therapy (SSRT)
    Medical physics, 2011
    Co-Authors: Yolanda Prezado, François Estève, Hélène Elleaume, P. Berkvens, Mathias Vautrin, I. Martínez-rovira, Alberto Bravin, Jean-françois Adam
    Abstract:

    Purpose: An adequate dosimetry protocol for synchrotron Radiation and the specific features of the ID17 Biomedical Beamline at the European Synchrotron Radiation Facility are essential for the preparation of the forthcoming clinical trials in the synchrotron Stereotactic Radiation Therapy (SSRT). The main aim of this work is the definition of a suitable protocol based on standards of dose absorbed to water. It must allow measuring the absolute dose with an uncertainty within the recommended limits for patient treatment of 2%-5%. Methods: Absolute dosimetry is performed with a thimble ionization chamber (PTW semiflex 31002) whose center is positioned at 2 g cm{sup -2} equivalent depth in water. Since the available synchrotron beam at the ESRF Biomedical Beamline has a maximum height of 3 mm, a scanning method was employed to mimic a uniform exposition of the ionization chamber. The scanning method has been shown to be equivalent to a broad beam irRadiation. Different correction factors have been assessed by using Monte Carlo simulations. Results: The absolute dose absorbed to water at 80 keV was measured in reference conditions with a 2% global uncertainty, within the recommended limits. The dose rate was determined to be in the range between 14 and 18more » Gy/min, that is to say, a factor two to three times higher than the 6 Gy/min achievable in RapidArc or VMAT machines. The dose absorbed to water was also measured in a RW3 solid water phantom. This phantom is suitable for quality assurance purposes since less than 2% average difference with respect to the water phantom measurements was found. In addition, output factors were assessed for different field sizes. Conclusions: A dosimetry protocol adequate for the specific features of the SSRT technique has been developed. This protocol allows measuring the absolute dose absorbed to water with an accuracy of 2%. It is therefore satisfactory for patient treatment.« less