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Cellular and subcellular dosimetry of radioisotopes used for pet imaging
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Abstracts / Physica Medica 32 (2016) 222–250
assessed using a phantom of 4 tubes filled with 99mTc solution with different activities. Our results demonstrate accurate quantitative information even for 10 s scans. The system was tested using a mouse injected with 99mTc-MDP for bone imaging, a mouse injected with 99mTc-DMSA for kidneys imaging and finally a mouse injected with 99mTc-MIBI for heart imaging. Conclusion. A new low-cost system, suitable for scintigraphic mouse imaging has been developed and evaluated using phantoms and small animals. Its dimensions and cost make it a unique solution for groups activated in the field of small animal nuclear imaging. http://dx.doi.org/10.1016/j.ejmp.2016.07.507
AUTOMATIC BONE MARROW SEGMENTATION FOR PETCT IMAGING IN MULTIPLE MYELOMA P. Leydon a,*, M. O’Connell b, D. Greene c, K. Curran a a Complex & Adaptive Systems Laboratory, University College Dublin, Ireland b The Mater Private Dublin, Ireland c Insight: Centre for Data Analytics, University College Dublin, Ireland ⇑ Corresponding author.
Introduction. Multiple myeloma (MM) is a malignant hematologic disorder characterized by bone marrow infiltration with neoplastic plasma cells. Approximately 10% of all hematologic cancers are related to MM. Whole-body 18F-FDG PETCT is an extremely useful imaging tool for the assessment of patients with MM. The novel approach developed in this research automatically segments bone marrow regions of interest on both the PET and CT datasets. Purpose. To automate bone marrow segmentation in PET. Materials and methods. Firstly, affine linear transforms are applied to the PET dataset and it is aligned to the CT images. Next, a binary mask is created based on a pixel threshold value of cortical bone. A series of image processing steps are performed to remove noise and fill gaps that correspond to bone marrow locations. This process results in a binary mask relating to bone marrow only which can then be applied to the registered PET dataset. Conclusion. The proposed method offers a fully automated and completely objective approach for segmentation of anatomical regions relating to bone marrow. With further development, this method could be used to evaluate clinical images in order to develop a database of PETCT images against which quantitative statistical comparisons between patients with normal bone marrow metabolism and those with myeloma can be made, establishing a baseline against which future scans may be referenced. In cases where the suspicion of myeloma exists, the tools could be used to support the diagnosis of the disease, and may be useful in staging of the disease in cases positive for myeloma. http://dx.doi.org/10.1016/j.ejmp.2016.07.508
CELLULAR AND SUBCELLULAR DOSIMETRY OF RADIOISOTOPES USED FOR PET IMAGING Hocine Nora a,*, Faivre Lionel b, Sarda-Mantel Laure c a
Institut de Radioprotection et de Sûreté Nucléaire, France INSERM, APHP, France c INSERM, IUH, Paris Diderot University, APHP, France ⇑ Corresponding author. b
Introduction. PET/CT imaging may be a useful method to follow and monitor the homing of hematopoietic stem and progenitor cells (HSPC) after HSPC injection in mice. To improve the method of HSPC
radiolabelling and to select the best radioisotopes for this technique a cellular dosimetry is required. Purpose. This early research work is focused on using Monte Carlo code to estimate the dose at cellular and subcellular levels for 3 radioisotopes used in PET: F-18, Cu-64 and Zr-89. Methods. S-values (absorbed dose per unit cumulated activity) calculations using Monte Carlo (MC) simulations are carried out, nucleus (N), Cytoplasm (Cy), Cellular surface (CS) and radiation source were simulated. The cells are assumed to be spherical with the radii of the cell and cell nucleus ranging from 4 to 8 lm. Different source-to-target combinations are considered namely nucleus to nucleus (N N), cytoplasm-to-nucleus (N Cy) and cell surface-to-nucleus (N CS). The S-values (in Gy/Bq.s) were calculated for cell nucleus and cellular surface distribution of radioactivity. Results. A comparison of MC results with the MIRD values for studied configurations are carried out for the radioisotopes studied. We generally find the largest deviations with MIRD for geometries where the target is at some distance from the source and, therefore, the results depend more strongly upon the plasmic membrane penetration ability of particles. http://dx.doi.org/10.1016/j.ejmp.2016.07.509
INVERSION OF THE ATTENUATED RADON TRANSFORM USING CUBIC SPLINES Nicholas E. Protonotarios a,b,*, Athanassios S. Fokas a,c, Anastasios Gaitanis d, George A. Kastis a a
Research Center of Mathematics, Academy of Athens, Greece Department of Mathematics, National Technical University of Athens, Greece c Department of Applied Mathematics and Theoretical Physics, University of Cambridge, UK d Biomedical Research Foundation of the Academy of Athens, Greece ⇑ Corresponding author. b
Introduction. The mathematics of single photon emission computed tomography (SPECT) involve the inversion of a certain integral, namely the attenuated Radon transform. This integral is stored in the form of the so-called attenuated sinogram. Purpose. By modifying the original formulation introduced by one of the authors in 2006, we have presented a slightly different formulation of the Inverse Attenuated Radon Transform (IART), which we refer to as attenuated Spline Reconstruction Technique (aSRT). The purpose of this study is to evaluate aSRT using simulated SPECT/CT phantoms and compare it with the industry standard, filtered backprojection (FBP). Materials and methods. We have rederived the analytic formula of the IART, which involves the Hilbert transform of the attenuation correction coefficient as well as of two functions of the attenuated sinogram. For the numerical implementation of these Hilbert transforms we have employed an approximation of custom-made third degree piecewise polynomials, namely cubic splines. Relevant sinograms were generated in STIR (Software for Tomographic Imaging Reconstruction) and were acquired for 30, 60, 120, 180, and 360 projections over 360 degrees. Comparisons with FBP were evaluated using contrast and bias. Results. Our numerical tests suggest that the new technique can efficiently produce accurate reconstructions for real phantoms. Conclusion. aSRT provides an alternative to FBP, which incorporates the attenuation correction within the algorithm itself. G.A. Kastis acknowledges the financial support of the ”Alexander S. Onassis Public Benefit Foundation” under grant No. R ZL 001-0. Furthermore, this work was partially supported by the research pro-
Abstracts / Physica Medica 32 (2016) 222–250
assessed using a phantom of 4 tubes filled with 99mTc solution with different activities. Our results demonstrate accurate quantitative information even for 10 s scans. The system was tested using a mouse injected with 99mTc-MDP for bone imaging, a mouse injected with 99mTc-DMSA for kidneys imaging and finally a mouse injected with 99mTc-MIBI for heart imaging. Conclusion. A new low-cost system, suitable for scintigraphic mouse imaging has been developed and evaluated using phantoms and small animals. Its dimensions and cost make it a unique solution for groups activated in the field of small animal nuclear imaging. http://dx.doi.org/10.1016/j.ejmp.2016.07.507
AUTOMATIC BONE MARROW SEGMENTATION FOR PETCT IMAGING IN MULTIPLE MYELOMA P. Leydon a,*, M. O’Connell b, D. Greene c, K. Curran a a Complex & Adaptive Systems Laboratory, University College Dublin, Ireland b The Mater Private Dublin, Ireland c Insight: Centre for Data Analytics, University College Dublin, Ireland ⇑ Corresponding author.
Introduction. Multiple myeloma (MM) is a malignant hematologic disorder characterized by bone marrow infiltration with neoplastic plasma cells. Approximately 10% of all hematologic cancers are related to MM. Whole-body 18F-FDG PETCT is an extremely useful imaging tool for the assessment of patients with MM. The novel approach developed in this research automatically segments bone marrow regions of interest on both the PET and CT datasets. Purpose. To automate bone marrow segmentation in PET. Materials and methods. Firstly, affine linear transforms are applied to the PET dataset and it is aligned to the CT images. Next, a binary mask is created based on a pixel threshold value of cortical bone. A series of image processing steps are performed to remove noise and fill gaps that correspond to bone marrow locations. This process results in a binary mask relating to bone marrow only which can then be applied to the registered PET dataset. Conclusion. The proposed method offers a fully automated and completely objective approach for segmentation of anatomical regions relating to bone marrow. With further development, this method could be used to evaluate clinical images in order to develop a database of PETCT images against which quantitative statistical comparisons between patients with normal bone marrow metabolism and those with myeloma can be made, establishing a baseline against which future scans may be referenced. In cases where the suspicion of myeloma exists, the tools could be used to support the diagnosis of the disease, and may be useful in staging of the disease in cases positive for myeloma. http://dx.doi.org/10.1016/j.ejmp.2016.07.508
CELLULAR AND SUBCELLULAR DOSIMETRY OF RADIOISOTOPES USED FOR PET IMAGING Hocine Nora a,*, Faivre Lionel b, Sarda-Mantel Laure c a
Institut de Radioprotection et de Sûreté Nucléaire, France INSERM, APHP, France c INSERM, IUH, Paris Diderot University, APHP, France ⇑ Corresponding author. b
Introduction. PET/CT imaging may be a useful method to follow and monitor the homing of hematopoietic stem and progenitor cells (HSPC) after HSPC injection in mice. To improve the method of HSPC
radiolabelling and to select the best radioisotopes for this technique a cellular dosimetry is required. Purpose. This early research work is focused on using Monte Carlo code to estimate the dose at cellular and subcellular levels for 3 radioisotopes used in PET: F-18, Cu-64 and Zr-89. Methods. S-values (absorbed dose per unit cumulated activity) calculations using Monte Carlo (MC) simulations are carried out, nucleus (N), Cytoplasm (Cy), Cellular surface (CS) and radiation source were simulated. The cells are assumed to be spherical with the radii of the cell and cell nucleus ranging from 4 to 8 lm. Different source-to-target combinations are considered namely nucleus to nucleus (N N), cytoplasm-to-nucleus (N Cy) and cell surface-to-nucleus (N CS). The S-values (in Gy/Bq.s) were calculated for cell nucleus and cellular surface distribution of radioactivity. Results. A comparison of MC results with the MIRD values for studied configurations are carried out for the radioisotopes studied. We generally find the largest deviations with MIRD for geometries where the target is at some distance from the source and, therefore, the results depend more strongly upon the plasmic membrane penetration ability of particles. http://dx.doi.org/10.1016/j.ejmp.2016.07.509
INVERSION OF THE ATTENUATED RADON TRANSFORM USING CUBIC SPLINES Nicholas E. Protonotarios a,b,*, Athanassios S. Fokas a,c, Anastasios Gaitanis d, George A. Kastis a a
Research Center of Mathematics, Academy of Athens, Greece Department of Mathematics, National Technical University of Athens, Greece c Department of Applied Mathematics and Theoretical Physics, University of Cambridge, UK d Biomedical Research Foundation of the Academy of Athens, Greece ⇑ Corresponding author. b
Introduction. The mathematics of single photon emission computed tomography (SPECT) involve the inversion of a certain integral, namely the attenuated Radon transform. This integral is stored in the form of the so-called attenuated sinogram. Purpose. By modifying the original formulation introduced by one of the authors in 2006, we have presented a slightly different formulation of the Inverse Attenuated Radon Transform (IART), which we refer to as attenuated Spline Reconstruction Technique (aSRT). The purpose of this study is to evaluate aSRT using simulated SPECT/CT phantoms and compare it with the industry standard, filtered backprojection (FBP). Materials and methods. We have rederived the analytic formula of the IART, which involves the Hilbert transform of the attenuation correction coefficient as well as of two functions of the attenuated sinogram. For the numerical implementation of these Hilbert transforms we have employed an approximation of custom-made third degree piecewise polynomials, namely cubic splines. Relevant sinograms were generated in STIR (Software for Tomographic Imaging Reconstruction) and were acquired for 30, 60, 120, 180, and 360 projections over 360 degrees. Comparisons with FBP were evaluated using contrast and bias. Results. Our numerical tests suggest that the new technique can efficiently produce accurate reconstructions for real phantoms. Conclusion. aSRT provides an alternative to FBP, which incorporates the attenuation correction within the algorithm itself. G.A. Kastis acknowledges the financial support of the ”Alexander S. Onassis Public Benefit Foundation” under grant No. R ZL 001-0. Furthermore, this work was partially supported by the research pro-