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Abdelkarim S. Allal - One of the best experts on this subject based on the ideXlab platform.
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TransitQA — A new method for transit dosimetry of Tomotherapy patients
Medical Physics, 2017Co-Authors: Olivier Pisaturo, Frédéric A. Miéville, Pierre-alain Tercier, Abdelkarim S. AllalAbstract:Purpose TransitQA is an innovative method for Tomotherapy transit dosimetry using the on-board detector (OBD). Our previously published model for Tomotherapy treatment plan verification (AirQA) has been enhanced to take into account patient and couch transmission. AirQA estimates the OBD signal during irradiation with nothing in the beam path from the leaf control sinogram, allowing us to check whether the planned treatment is correctly delivered by the machine. TransitQA allows us to check the treatment delivery with the patient on the couch, potentially showing the effects of changes in the patient anatomy and delivery errors. Methods Patient and couch transmission have been added to the model using the OBD projections of pre-treatment megavoltage computed tomography (MVCT). The difference in the energy spectra between the imaging and treatment beams has been corrected by an exponent from the MVCT projections consisting of the ratio of the mass attenuation coefficients. This exponent has been found to not vary significantly with the atomic number Z, allowing us to apply this procedure to heterogeneous media, such as patients. The attenuated OBD projections acquired during the treatment are compared to the model via a signed global Υ-index analysis. The Dose Criterion was 5% of the 95th percentile of the Dose distribution, and the distance to agreement (DTA) was 4 mm. Results Our method has been applied to a heterogeneous phantom with 98.1% of the points passing the Υ-evaluation test, showing that the model can predict the attenuated OBD projection. The method has been applied to two representative patients throughout the whole treatment, highlighting variations in the signal transmission and Υ-index. Conclusion This paper establishes the proof-of-concept of transit dosimetry for all patients treated by Tomotherapy. Moreover, this method can be used as a surrogate for in vivo dosimetry This article is protected by copyright. All rights reserved.
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48. Tomotherapy: From AirQA to TransitQA
Physica Medica, 2017Co-Authors: Pierre-alain Tercier, O. Pisaturo, Frédéric A. Miéville, Abdelkarim S. AllalAbstract:Introduction Since the acquisition of our Tomotherapy in 2011, we have developed a method of validating the treatment of patients without additional measuring instruments. The idea was to use the onboard detector (OBD). This previously published [1] model for Tomotherapy treatment plan verification (called AirQA) has been enhanced in order to take into account patient and couch transmission (we call it TransitQA). TransitQA is an innovative method for Tomotherapy transit dosimetry using the OBD. AirQA estimates the OBD signal during irradiation without anything in the beam path from the leaf control sinogram, allowing to check whether the planned treatment is correctly delivered by the machine. TransitQA allows to checks the treatment delivery with the patient on the couch, potentially showing the effects of changes in the patient anatomy and delivery errors. Methods AirQA was for us a well-controlled concept in 2015 [1] . Today more than 500 patient treatments have been validated by this method. This great experience has made it possible to go further in the project. Patient and couch transmission have been added to the model, using the OBD projections of the pre-treatment megavoltage computed tomography (MVCT). The difference in the energy spectra between the imaging and treatment beam has been corrected by an exponent on the MVCT projections, consisting in the ratio of the mass attenuation coefficients. This exponent has been found not to vary significantly with the atomic number Z, giving the opportunity to apply this procedure to heterogeneous media like patients. The attenuated OBD projections acquired during the treatment are compared to the model via a signed?-index analysis. The Dose Criterion was 5% of the 95th percentile of the Dose distribution and the distance to agreement was 4 mm. Results Our method has been applied to a heterogeneous phantom with 98.1% of point passing the gamma evaluation test, showing that the model is able to predict attenuated OBD projection. The method has been applied on two representative patients, during the whole treatment, showing a great sensitivity. Conclusions This talk describes the experience of the AirQA and also establishes the proof of concept of transit dosimetry for all patients treated by Tomotherapy. Moreover, this method called TransitQA can be a surrogate for in vivo dosimetry.
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An efficient procedure for tomotherapy treatment plan verification using the on-board detector.
Physics in Medicine and Biology, 2015Co-Authors: O. Pisaturo, Frédéric A. Miéville, Pierre-alain Tercier, Abdelkarim S. AllalAbstract:In this work, a fast and simple procedure for tomotherapy treatment plan verification using the on-board detector (OBD) has been developed. This procedure allows verification of plans with static and dynamic jaws (TomoEDGE). A convolution-based calculation model has been derived in order to link the leaf control sinogram from the treatment planning system to the data acquired by the OBD during a static couch procedure. The convolution kernel has been optimized using simple plans calculated in the Tomotherapy Cheese phantom. The optimal kernel has been found to be a lorentzian function, whose parameter ? is 0.186 for the 1?cm jaw opening, 0.232 for the 2.5?cm jaw opening and 0.373 for the 5?cm jaw opening. The evaluation has been performed with a ?-index analysis. The Dose Criterion was 3% of the 95th percentile of the Dose distribution and the distance-to-agreement Criterion is 2?mm. In order to validate the procedure, it has been applied to around 50 clinical treatment plans, which had already been validated by the Delta4 phantom (Scandidos, Sweden). 96% of the tested plans have passed the criteria. Concerning the other 4%, significant discrepancies between the leaf pattern in the leaf control sinogram and the OBD data have been shown, which might be due to differences in the leaf open time. This corresponds also to a higher sensitivity of this method over the Delta4, adding the possibility of better monitoring the treatment delivery.
Takatoshi Hattori - One of the best experts on this subject based on the ideXlab platform.
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Issues on exemption levels for package surface contamination simply derived from IAEA TECDOC-1449 'Radiological aspects of non-fixed contamination of packages and conveyances'
Packaging Transport Storage and Security of Radioactive Material, 2020Co-Authors: Haruyuki Ogino, Takatoshi HattoriAbstract:AbstractThe present IAEA Transport Regulation on surface contamination (with limits specified in terms of Bq cm–2) is determined from a simple radiological model for the most hazardous radionuclides (Pu-239 for α emitters and Sr-90 for β emitters) and its extremely conservative model is applied for all other α and β emitters. In the International Atomic Energy Agency (IAEA) TECDOC-1449 report, the effect of radiation from non-fixed contamination on packages is evaluated and the Dose conversion coefficients [(mSv/y)/(Bq/cm2)] are calculated for each radionuclide. In this study, exemption levels for surface contamination are calculated with the Dose conversion coefficients specified in TECDOC-1449. The Dose Criterion for deriving the exemption level is chosen to be 0˙01 mSv/y, to maintain consistency with fundamental concepts adopted by the IAEA safety standards committees, namely, the Radiation Safety Standards Committee (RASSC), the Transport Safety Standards Committee (TRANSSC) and the Waste Safety Stand...
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Validity of generic scenarios used in derivation of exemption levels for surface contamination considering transport-specific aspects.
Radiation Protection Dosimetry, 2011Co-Authors: Haruyuki Ogino, Takatoshi HattoriAbstract:: The exemption levels for surface contamination in units of Bq cm(-2) were derived by developing a new universal Dose assessment model that consists of three generic scenarios assessed by considering manually, closely and remotely handled objects. In this paper, as part of the process of verifying the validity of these generic scenarios, annual Doses that arise from transport-specific aspects are calculated. The maximum annual Doses are found to be lower than 10 µSv, which is the bottom line of the exemption Dose Criterion. The result verifies the validity of the generic scenarios used in the previous derivation of exemption levels for surface contamination.
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RECONSIDERATION OF THE MINIMUM Dose CONSTRAINT FOR PUBLIC EXPOSURES IN RADIOLOGICAL PROTECTION
Radiation Protection Dosimetry, 2008Co-Authors: Takatoshi HattoriAbstract:By using a probabilistic approach, the effects of the Dose distribution of radiation due to man-made radioactive nuclides when added to those of natural background radiation have been studied. These results show that additional exposure to man-made radiation of up to 0.5 mSv y −1 (as a Dose constraint) would not significantly change the distribution of total public Doses. Taking into consideration such probabilistic analysis and rationales of derivations of exemption and clearance levels, it can be concluded that the minimum Dose constraint that requires optimisation in radiation protection, should be set to 0.1 mSv y −1 , which is one-order magnitude higher than 0.01 mSv y −1 , the current Dose Criterion for exemption and clearance.
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Lower Bound of Optimization in Radiological Protection System Taking Account of Practical Implementation of Clearance
11th International Conference on Environmental Remediation and Radioactive Waste Management Parts A and B, 2007Co-Authors: Takatoshi HattoriAbstract:The Dose Criterion used to derive clearance and exemption levels is of the order of 0.01 mSv/y based on the Basic Safety Standard (BSS) of the International Atomic Energy Agency (IAEA), the use of which has been agreed upon by many countries. It is important for human beings, who are facing the fact that global resources for risk reduction are limited, to carefully consider the practical implementation of radiological protection systems, particularly for low-radiation-Dose regions. For example, in direct gamma ray monitoring, to achieve clearance level compliance, difficult issues on how the uncertainty (error) of gamma measurement should be handled and also how the uncertainty (scattering) of the estimation of non-gamma emitters should be treated in clearance must be resolved. To resolve these issues, a new probabilistic approach has been proposed to establish an appropriate safety factor for compliance with the clearance level in Japan. This approach is based on the fundamental concept that 0.1 mSv/y should be complied with the 97.5th percentile of the probability distribution for the uncertainties of both the measurement and estimation of non-gamma emitters. The International Commission on Radiological Protection, ICRP published a new concept of the representative person in Publication 101 Part I. The representative person is a hypothetical person exposed to a Dose that is representative of those of highly exposed persons in a population. In a probabilistic Dose assessment, the ICRP recommends that the representative person should be defined such that the probability of exposure occurrence is lower than about 5% that of a person randomly selected from the population receiving a high Dose. From the new concept of the ICRP, it is reasonable to consider that the 95th percentile of the Dose distribution for the representative person is theoretically always lower than the Dose constraint. Using this established relationship, it can be concluded that the minimum Dose constraint that requires optimization in radiological protection should be set to the Dose Criterion of 0.1 mSv/y, considering the fundamental concept used in the clearance Criterion for resolving the issues on uncertainty in clearance.© 2007 ASME
Pierre-alain Tercier - One of the best experts on this subject based on the ideXlab platform.
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TransitQA — A new method for transit dosimetry of Tomotherapy patients
Medical Physics, 2017Co-Authors: Olivier Pisaturo, Frédéric A. Miéville, Pierre-alain Tercier, Abdelkarim S. AllalAbstract:Purpose TransitQA is an innovative method for Tomotherapy transit dosimetry using the on-board detector (OBD). Our previously published model for Tomotherapy treatment plan verification (AirQA) has been enhanced to take into account patient and couch transmission. AirQA estimates the OBD signal during irradiation with nothing in the beam path from the leaf control sinogram, allowing us to check whether the planned treatment is correctly delivered by the machine. TransitQA allows us to check the treatment delivery with the patient on the couch, potentially showing the effects of changes in the patient anatomy and delivery errors. Methods Patient and couch transmission have been added to the model using the OBD projections of pre-treatment megavoltage computed tomography (MVCT). The difference in the energy spectra between the imaging and treatment beams has been corrected by an exponent from the MVCT projections consisting of the ratio of the mass attenuation coefficients. This exponent has been found to not vary significantly with the atomic number Z, allowing us to apply this procedure to heterogeneous media, such as patients. The attenuated OBD projections acquired during the treatment are compared to the model via a signed global Υ-index analysis. The Dose Criterion was 5% of the 95th percentile of the Dose distribution, and the distance to agreement (DTA) was 4 mm. Results Our method has been applied to a heterogeneous phantom with 98.1% of the points passing the Υ-evaluation test, showing that the model can predict the attenuated OBD projection. The method has been applied to two representative patients throughout the whole treatment, highlighting variations in the signal transmission and Υ-index. Conclusion This paper establishes the proof-of-concept of transit dosimetry for all patients treated by Tomotherapy. Moreover, this method can be used as a surrogate for in vivo dosimetry This article is protected by copyright. All rights reserved.
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48. Tomotherapy: From AirQA to TransitQA
Physica Medica, 2017Co-Authors: Pierre-alain Tercier, O. Pisaturo, Frédéric A. Miéville, Abdelkarim S. AllalAbstract:Introduction Since the acquisition of our Tomotherapy in 2011, we have developed a method of validating the treatment of patients without additional measuring instruments. The idea was to use the onboard detector (OBD). This previously published [1] model for Tomotherapy treatment plan verification (called AirQA) has been enhanced in order to take into account patient and couch transmission (we call it TransitQA). TransitQA is an innovative method for Tomotherapy transit dosimetry using the OBD. AirQA estimates the OBD signal during irradiation without anything in the beam path from the leaf control sinogram, allowing to check whether the planned treatment is correctly delivered by the machine. TransitQA allows to checks the treatment delivery with the patient on the couch, potentially showing the effects of changes in the patient anatomy and delivery errors. Methods AirQA was for us a well-controlled concept in 2015 [1] . Today more than 500 patient treatments have been validated by this method. This great experience has made it possible to go further in the project. Patient and couch transmission have been added to the model, using the OBD projections of the pre-treatment megavoltage computed tomography (MVCT). The difference in the energy spectra between the imaging and treatment beam has been corrected by an exponent on the MVCT projections, consisting in the ratio of the mass attenuation coefficients. This exponent has been found not to vary significantly with the atomic number Z, giving the opportunity to apply this procedure to heterogeneous media like patients. The attenuated OBD projections acquired during the treatment are compared to the model via a signed?-index analysis. The Dose Criterion was 5% of the 95th percentile of the Dose distribution and the distance to agreement was 4 mm. Results Our method has been applied to a heterogeneous phantom with 98.1% of point passing the gamma evaluation test, showing that the model is able to predict attenuated OBD projection. The method has been applied on two representative patients, during the whole treatment, showing a great sensitivity. Conclusions This talk describes the experience of the AirQA and also establishes the proof of concept of transit dosimetry for all patients treated by Tomotherapy. Moreover, this method called TransitQA can be a surrogate for in vivo dosimetry.
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An efficient procedure for tomotherapy treatment plan verification using the on-board detector.
Physics in Medicine and Biology, 2015Co-Authors: O. Pisaturo, Frédéric A. Miéville, Pierre-alain Tercier, Abdelkarim S. AllalAbstract:In this work, a fast and simple procedure for tomotherapy treatment plan verification using the on-board detector (OBD) has been developed. This procedure allows verification of plans with static and dynamic jaws (TomoEDGE). A convolution-based calculation model has been derived in order to link the leaf control sinogram from the treatment planning system to the data acquired by the OBD during a static couch procedure. The convolution kernel has been optimized using simple plans calculated in the Tomotherapy Cheese phantom. The optimal kernel has been found to be a lorentzian function, whose parameter ? is 0.186 for the 1?cm jaw opening, 0.232 for the 2.5?cm jaw opening and 0.373 for the 5?cm jaw opening. The evaluation has been performed with a ?-index analysis. The Dose Criterion was 3% of the 95th percentile of the Dose distribution and the distance-to-agreement Criterion is 2?mm. In order to validate the procedure, it has been applied to around 50 clinical treatment plans, which had already been validated by the Delta4 phantom (Scandidos, Sweden). 96% of the tested plans have passed the criteria. Concerning the other 4%, significant discrepancies between the leaf pattern in the leaf control sinogram and the OBD data have been shown, which might be due to differences in the leaf open time. This corresponds also to a higher sensitivity of this method over the Delta4, adding the possibility of better monitoring the treatment delivery.
Dietmar Georg - One of the best experts on this subject based on the ideXlab platform.
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interpretation and evaluation of the γ index and the γ index angle for the verification of imrt hybrid plans
Physics in Medicine and Biology, 2005Co-Authors: M Stock, Bernhard Kroupa, Dietmar GeorgAbstract:In IMRT, the method for a quantitative comparison of two-dimensional Dose distributions is still under development. The γ evaluation method proposed by Low et al is the most accepted approach and has been adapted by many groups. Based on the concept of Low et al we developed a software tool with an intelligent search algorithm to minimize the calculation time. For the interpretation of deviations a γ angle distribution and other tools (Dose difference map, profiles, γ area histograms, etc) are integrated in the software package. Ten hybrid plans are included in the verification study containing 6 IMRT head and neck cases, 2 IMRT prostate cases and one IMRT paravertebral case as well as a standard uniform intensity conformal 4 field box treatment for comparison. IMRT plans are realized with a segmental MLC delivery technique. The fields of a hybrid plan are applied at once and Dose distributions are measured with films in three planes of a verification phantom. All γ vector calculations are based on a 3% Dose Criterion and a 3 mm DTA acceptance Criterion. The mean value γmean (mean value in the γ distribution) of the various IMRT plans is 0.45 ± 0.10 (1 SD). On average, the percentage of points exceeding the acceptance criteria of γ ≤ 1 (γ>1) is 5.8 ± 5.4% (1 SD). The mean value of γ1% (1% of points have an equal or higher γ value) is 1.47 ± 0.59 (1 SD) for IMRT plans. In 5 out of 27 planes, γ>1 is substantially larger than the average. This is also indicated in γ area histograms. Planes with large areas outside the tolerance criteria were further evaluated using γ angle distributions. This additional information indicates that the large areas with high γ values are dominated by the Dose difference. It is shown that the deviations are influenced by tongue and groove effects. From the statistical evaluation of γ values (e.g. γ area histogram), acceptance criteria for IMRT hybrid plans can be defined. For the interpretation of the γ maps, distributions of the γ angle and traditional evaluation methods, such as Dose profiles, are still very useful.
Frédéric A. Miéville - One of the best experts on this subject based on the ideXlab platform.
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TransitQA — A new method for transit dosimetry of Tomotherapy patients
Medical Physics, 2017Co-Authors: Olivier Pisaturo, Frédéric A. Miéville, Pierre-alain Tercier, Abdelkarim S. AllalAbstract:Purpose TransitQA is an innovative method for Tomotherapy transit dosimetry using the on-board detector (OBD). Our previously published model for Tomotherapy treatment plan verification (AirQA) has been enhanced to take into account patient and couch transmission. AirQA estimates the OBD signal during irradiation with nothing in the beam path from the leaf control sinogram, allowing us to check whether the planned treatment is correctly delivered by the machine. TransitQA allows us to check the treatment delivery with the patient on the couch, potentially showing the effects of changes in the patient anatomy and delivery errors. Methods Patient and couch transmission have been added to the model using the OBD projections of pre-treatment megavoltage computed tomography (MVCT). The difference in the energy spectra between the imaging and treatment beams has been corrected by an exponent from the MVCT projections consisting of the ratio of the mass attenuation coefficients. This exponent has been found to not vary significantly with the atomic number Z, allowing us to apply this procedure to heterogeneous media, such as patients. The attenuated OBD projections acquired during the treatment are compared to the model via a signed global Υ-index analysis. The Dose Criterion was 5% of the 95th percentile of the Dose distribution, and the distance to agreement (DTA) was 4 mm. Results Our method has been applied to a heterogeneous phantom with 98.1% of the points passing the Υ-evaluation test, showing that the model can predict the attenuated OBD projection. The method has been applied to two representative patients throughout the whole treatment, highlighting variations in the signal transmission and Υ-index. Conclusion This paper establishes the proof-of-concept of transit dosimetry for all patients treated by Tomotherapy. Moreover, this method can be used as a surrogate for in vivo dosimetry This article is protected by copyright. All rights reserved.
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48. Tomotherapy: From AirQA to TransitQA
Physica Medica, 2017Co-Authors: Pierre-alain Tercier, O. Pisaturo, Frédéric A. Miéville, Abdelkarim S. AllalAbstract:Introduction Since the acquisition of our Tomotherapy in 2011, we have developed a method of validating the treatment of patients without additional measuring instruments. The idea was to use the onboard detector (OBD). This previously published [1] model for Tomotherapy treatment plan verification (called AirQA) has been enhanced in order to take into account patient and couch transmission (we call it TransitQA). TransitQA is an innovative method for Tomotherapy transit dosimetry using the OBD. AirQA estimates the OBD signal during irradiation without anything in the beam path from the leaf control sinogram, allowing to check whether the planned treatment is correctly delivered by the machine. TransitQA allows to checks the treatment delivery with the patient on the couch, potentially showing the effects of changes in the patient anatomy and delivery errors. Methods AirQA was for us a well-controlled concept in 2015 [1] . Today more than 500 patient treatments have been validated by this method. This great experience has made it possible to go further in the project. Patient and couch transmission have been added to the model, using the OBD projections of the pre-treatment megavoltage computed tomography (MVCT). The difference in the energy spectra between the imaging and treatment beam has been corrected by an exponent on the MVCT projections, consisting in the ratio of the mass attenuation coefficients. This exponent has been found not to vary significantly with the atomic number Z, giving the opportunity to apply this procedure to heterogeneous media like patients. The attenuated OBD projections acquired during the treatment are compared to the model via a signed?-index analysis. The Dose Criterion was 5% of the 95th percentile of the Dose distribution and the distance to agreement was 4 mm. Results Our method has been applied to a heterogeneous phantom with 98.1% of point passing the gamma evaluation test, showing that the model is able to predict attenuated OBD projection. The method has been applied on two representative patients, during the whole treatment, showing a great sensitivity. Conclusions This talk describes the experience of the AirQA and also establishes the proof of concept of transit dosimetry for all patients treated by Tomotherapy. Moreover, this method called TransitQA can be a surrogate for in vivo dosimetry.
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An efficient procedure for tomotherapy treatment plan verification using the on-board detector.
Physics in Medicine and Biology, 2015Co-Authors: O. Pisaturo, Frédéric A. Miéville, Pierre-alain Tercier, Abdelkarim S. AllalAbstract:In this work, a fast and simple procedure for tomotherapy treatment plan verification using the on-board detector (OBD) has been developed. This procedure allows verification of plans with static and dynamic jaws (TomoEDGE). A convolution-based calculation model has been derived in order to link the leaf control sinogram from the treatment planning system to the data acquired by the OBD during a static couch procedure. The convolution kernel has been optimized using simple plans calculated in the Tomotherapy Cheese phantom. The optimal kernel has been found to be a lorentzian function, whose parameter ? is 0.186 for the 1?cm jaw opening, 0.232 for the 2.5?cm jaw opening and 0.373 for the 5?cm jaw opening. The evaluation has been performed with a ?-index analysis. The Dose Criterion was 3% of the 95th percentile of the Dose distribution and the distance-to-agreement Criterion is 2?mm. In order to validate the procedure, it has been applied to around 50 clinical treatment plans, which had already been validated by the Delta4 phantom (Scandidos, Sweden). 96% of the tested plans have passed the criteria. Concerning the other 4%, significant discrepancies between the leaf pattern in the leaf control sinogram and the OBD data have been shown, which might be due to differences in the leaf open time. This corresponds also to a higher sensitivity of this method over the Delta4, adding the possibility of better monitoring the treatment delivery.