- Email: [email protected]
Database to CT scan to reduce doses with iterative reconstructions (SAFIRE)
e12
Abstracts of the SFPM Annual Meeting 2013 / Physica Medica 29 (2013) e1–e46
signal normalization of metabolites (acquisition time = 9 mn) even in the presence of brain disorder which water content cannot be directly known. References [1] Amadon, 2010. [2] Deoni, 2004. [3] Maudsley, 2006. http://dx.doi.org/10.1016/j.ejmp.2013.08.040
35 DUAL ENERGY CT FOR SIMULTANEOUS AND QUANTITATIVE IMAGING OF IODINATED CONTRAST AGENT AND GADOLINIUM NANOPARTICLES: A PERSPECTIVE FOR INCREASING THE THERAPEUTIC EFFICACY OF NANOPARTICLES F. Taupin, F. Marticke, C. Le Nezet, H Elleaume. ESRF, Grenoble, France Introduction: Tumoral radiosensitivity enhanced by nanoparticles (NPs) has widely been described in vitro (Butterworth) (Brun). In vivo, results are more reserved and strongly depend on the NPs distribution within the tumor. Dual energy CT has been developed at the European synchrotron medical beamline in order to study this distribution. The method allows mapping and separating three mixed elements (Vinegar). The practical application presented here, aims at characterizing the distribution of gadolinium NPs (GdNPs) directly injected in a brain tumor and comparing it to the tumor volume (imaged through iodinated contrast agent (CA)). This characterization would allow optimizing the treatment planning combining NPs and external irradiation. Material and methods: GdNPs are directly injected in a rat bearing glioma, followed by the intravenous injection of iodine CA. The brain is then simultaneously scanned by two monochromatic X-rays beams, with mean energies bracketing the iodine K-edge (33.17 keV). Images are then reconstructed by filtered back-projection method. The three searched elements (healthy tissues, tumor (iodine) and Gd) are separated using Granton et al. formalism. Finally, the volumes are segmented for measuring the overlap of the tumor with GdNPs. The elements concentrations and elimination constants are also calculated. Results: Dual energy CT allows simultaneous imaging of GdNPs and iodine CA in brain tumors. Simultaneous images acquisition at both energies allows measuring the tumor overlap by GdNPs, avoiding complex non-rigid image registration and movement artifacts. Direct injection was efficient for increasing the NPs concentration in the brain tumor (compared to intravenous injection) and for slowing down their elimination (3 times less compared to CA). Moreover, the method has been shown to be relevant for optimizing direct injection parameters of radiosensitizing drugs. Conclusion: The optimization of the tumor covering by radiosensitizing NPs is possible with dual energy CT. This appears as an encouraging perspective for increasing their therapeutic efficacy in vivo. Acknowledgments ANR Raphaelo, Labex Primes Bibliography [1] Brun. Biointerfaces 2009;72(1):128–34. [2] Butterworth. Nanotechnology 2010;21(9):2951101.
[3] Vinegar. Rev. Scient. Instrum. 1987;58(1):96. [4] Granton. Med. Phys. 2008;35(11):5030.
http://dx.doi.org/10.1016/j.ejmp.2013.08.041
36 DATABASE TO CT SCAN TO REDUCE DOSES WITH ITERATIVE RECONSTRUCTIONS (SAFIRE) A. Fernandez, J. Greffier, E. Langard, R. Bechet, F. Macri, J.-P. Beregi. CHU, Nîmes, France Purpose: To evaluate the impact of iterative reconstruction SAFIRE on quality image which can be used to reduce dose for CT scan acquisition in clinical practice. Materials and methods: 56 CT acquisitions (Somatom Definition AS+, Siemens) were performed on a phantom image quality in several voltages, mAs and pitchs for the same collimation. The raw data were reconstructed by filtered back projection and 5 levels of SAFIRE for two filters and three couples thickness/increment. A total database of 2016 combinations of parameters acquisition and reconstruction was obtained. Noise, signal, contrast to noise ratio (CNR), signal to noise ratio (SNR) and transverse spatial resolution were investigated. From this database, a software tool was developed to find the acquisition and reconstruction parameters for dose reduction while maintaining quality indices equivalent. Concordance of the results was performed on an anthropomorphic phantom for use in clinical practice. Results: Reducing the dose by changing the acquisition parameters deteriorated image quality indices, mainly due to the increase in noise. This decline was offset by couples thickness/increment and higher levels SAFIRE. Over the SAFIRE level increased more noise decreased ( 10% per level). The signal is stable, the RSB and RCB increased. SAFIRE did not influence the transverse spatial resolution. These results were confirmed with anthropomorphic phantom. The computer tool helping users from the initial settings, can propose to reduce the dose while maintaining adequate RSB and RCB. The best combinations of parameters were proposed. The use of this tool in routine had achieved dose reductions for patients. The thoracic and abdominal CTDIvol acquisitions showed differences respectively 82% and 64% from the values of NRD. Conclusion: Multiple combinations of parameters allowed the radiologist through a computer tool, to select a suitable CT scan acquisition with dose reduction in order to obtain adequate quality images.
http://dx.doi.org/10.1016/j.ejmp.2013.08.042
37 RADIOLOGY PATIENTS DOSE MASTERING OF KIRCHBERG HOSPITAL CENTER M. Grelot, Y. Benhdech, M. Braun, P. Sana, J. Henry, F. Mersch, B. Renou. Fédération des Hôpitaux Luxembourgeois (FHL), Bertrange, Hôpital Kirchberg, Steichen, Luxembourg Medical irradiation is the primary exposure source, artificial origin, of the population in industrialized countries (1.3 mSv per year per capita on average according to the IRSN 2010). However, Radiation protection of persons exposed for medical purposes is a relatively recent concern (directives: 84/466 & 97/43 Euratom). The notion of regulatory dose limit is inappropriate in the context of medical examinations, in effect, reduce and maintain exposure to radiation at a dose as low as reasonably possible, in accordance with
Abstracts of the SFPM Annual Meeting 2013 / Physica Medica 29 (2013) e1–e46
signal normalization of metabolites (acquisition time = 9 mn) even in the presence of brain disorder which water content cannot be directly known. References [1] Amadon, 2010. [2] Deoni, 2004. [3] Maudsley, 2006. http://dx.doi.org/10.1016/j.ejmp.2013.08.040
35 DUAL ENERGY CT FOR SIMULTANEOUS AND QUANTITATIVE IMAGING OF IODINATED CONTRAST AGENT AND GADOLINIUM NANOPARTICLES: A PERSPECTIVE FOR INCREASING THE THERAPEUTIC EFFICACY OF NANOPARTICLES F. Taupin, F. Marticke, C. Le Nezet, H Elleaume. ESRF, Grenoble, France Introduction: Tumoral radiosensitivity enhanced by nanoparticles (NPs) has widely been described in vitro (Butterworth) (Brun). In vivo, results are more reserved and strongly depend on the NPs distribution within the tumor. Dual energy CT has been developed at the European synchrotron medical beamline in order to study this distribution. The method allows mapping and separating three mixed elements (Vinegar). The practical application presented here, aims at characterizing the distribution of gadolinium NPs (GdNPs) directly injected in a brain tumor and comparing it to the tumor volume (imaged through iodinated contrast agent (CA)). This characterization would allow optimizing the treatment planning combining NPs and external irradiation. Material and methods: GdNPs are directly injected in a rat bearing glioma, followed by the intravenous injection of iodine CA. The brain is then simultaneously scanned by two monochromatic X-rays beams, with mean energies bracketing the iodine K-edge (33.17 keV). Images are then reconstructed by filtered back-projection method. The three searched elements (healthy tissues, tumor (iodine) and Gd) are separated using Granton et al. formalism. Finally, the volumes are segmented for measuring the overlap of the tumor with GdNPs. The elements concentrations and elimination constants are also calculated. Results: Dual energy CT allows simultaneous imaging of GdNPs and iodine CA in brain tumors. Simultaneous images acquisition at both energies allows measuring the tumor overlap by GdNPs, avoiding complex non-rigid image registration and movement artifacts. Direct injection was efficient for increasing the NPs concentration in the brain tumor (compared to intravenous injection) and for slowing down their elimination (3 times less compared to CA). Moreover, the method has been shown to be relevant for optimizing direct injection parameters of radiosensitizing drugs. Conclusion: The optimization of the tumor covering by radiosensitizing NPs is possible with dual energy CT. This appears as an encouraging perspective for increasing their therapeutic efficacy in vivo. Acknowledgments ANR Raphaelo, Labex Primes Bibliography [1] Brun. Biointerfaces 2009;72(1):128–34. [2] Butterworth. Nanotechnology 2010;21(9):2951101.
[3] Vinegar. Rev. Scient. Instrum. 1987;58(1):96. [4] Granton. Med. Phys. 2008;35(11):5030.
http://dx.doi.org/10.1016/j.ejmp.2013.08.041
36 DATABASE TO CT SCAN TO REDUCE DOSES WITH ITERATIVE RECONSTRUCTIONS (SAFIRE) A. Fernandez, J. Greffier, E. Langard, R. Bechet, F. Macri, J.-P. Beregi. CHU, Nîmes, France Purpose: To evaluate the impact of iterative reconstruction SAFIRE on quality image which can be used to reduce dose for CT scan acquisition in clinical practice. Materials and methods: 56 CT acquisitions (Somatom Definition AS+, Siemens) were performed on a phantom image quality in several voltages, mAs and pitchs for the same collimation. The raw data were reconstructed by filtered back projection and 5 levels of SAFIRE for two filters and three couples thickness/increment. A total database of 2016 combinations of parameters acquisition and reconstruction was obtained. Noise, signal, contrast to noise ratio (CNR), signal to noise ratio (SNR) and transverse spatial resolution were investigated. From this database, a software tool was developed to find the acquisition and reconstruction parameters for dose reduction while maintaining quality indices equivalent. Concordance of the results was performed on an anthropomorphic phantom for use in clinical practice. Results: Reducing the dose by changing the acquisition parameters deteriorated image quality indices, mainly due to the increase in noise. This decline was offset by couples thickness/increment and higher levels SAFIRE. Over the SAFIRE level increased more noise decreased ( 10% per level). The signal is stable, the RSB and RCB increased. SAFIRE did not influence the transverse spatial resolution. These results were confirmed with anthropomorphic phantom. The computer tool helping users from the initial settings, can propose to reduce the dose while maintaining adequate RSB and RCB. The best combinations of parameters were proposed. The use of this tool in routine had achieved dose reductions for patients. The thoracic and abdominal CTDIvol acquisitions showed differences respectively 82% and 64% from the values of NRD. Conclusion: Multiple combinations of parameters allowed the radiologist through a computer tool, to select a suitable CT scan acquisition with dose reduction in order to obtain adequate quality images.
http://dx.doi.org/10.1016/j.ejmp.2013.08.042
37 RADIOLOGY PATIENTS DOSE MASTERING OF KIRCHBERG HOSPITAL CENTER M. Grelot, Y. Benhdech, M. Braun, P. Sana, J. Henry, F. Mersch, B. Renou. Fédération des Hôpitaux Luxembourgeois (FHL), Bertrange, Hôpital Kirchberg, Steichen, Luxembourg Medical irradiation is the primary exposure source, artificial origin, of the population in industrialized countries (1.3 mSv per year per capita on average according to the IRSN 2010). However, Radiation protection of persons exposed for medical purposes is a relatively recent concern (directives: 84/466 & 97/43 Euratom). The notion of regulatory dose limit is inappropriate in the context of medical examinations, in effect, reduce and maintain exposure to radiation at a dose as low as reasonably possible, in accordance with