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CT scans
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Abstracts/Physica Medica 32 (2016) e97–e115
of this study was to measure FDG PET standardized uptake values (SUVs) change over time in three physiological compartments: liver, lung and Blood Pool (BP). Material and Methods: 100 patients enrolled in Dual Point clinical trial on Hodgkin disease were retrospectively evaluated. PET/CT imaging was performed at either 1 h (PET1) and at 2 h (PET2) after FDG administration. DICOM headers were analyzed to collect information on the scanning procedure. A three-dimensional region of interest (ROI) was drawn on the fused PET image to measure the mean SUV of the three compartments at PET1 (SUV1) and at PET2 (SUV2). DeltaSUV ((SUV2-SUV1)/SUV1) and normalized SUV (SUV/((SUV1 + SUV2)/2)) were calculated for each pair of data. Linear model has been applied to the data. Kolmogorov–Smirnov (KS) test was used to compare the model to the data. Results: Uptake time mean values were (72 ± 17) min and (133 ± 18) min for PET1 and PET2 respectively. The liver’s SUV1 and SUV2 for all patients were (1.82 ± 0.40) g/mL and (1.52 ± 0.35) g/mL respectively while the BP’s SUV1 and SUV2 were (1.37 ± 0.39) g/mL and (1.07 ± 0.36) g/mL respectively. Lung’s SUV1 was (0.40 ± 0.10) g/mL and SUV2 was (0.33 ± 0.09) g/mL. The mean liver, lung and BP SUVs were (−16 ± 8)% (range: −35% to 0%), (−23 ± 12)% (range: −57% to −1%) and (−18 ± 10)% (range: −61% to −1%). Mean SUV variations were respectively 0.25, 0.10, and 0.27 SUV/hour for liver, lung and BP SUVs. The normalized SUV mildly correlated to the uptake time (Pearson correlation coefficients were 0.63, 0.58 and 0.53 for liver, BP and lung respectively). SUV1 was recalculated using the linear model and compared to measured data. KS values were 0.10(p = 0.99), 0.12(p = 0.99) and 0.13(p = 0.99) for liver, lung and BP, respectively. Conclusion: SUV decreases over time in the physiological compartments. http://dx.doi.org/10.1016/j.ejmp.2016.01.338
C.333 APPLICATION OF LIDEA (LIVER DETECTION ALGORITHM) FOR PET/CT SCANS E. Bertone *,a, F. Bergesio a,b, A. Terulla a, P. Cerello c, S. Chauvie a. a Medical Physics Unit, ASO S. Croce e Carle, Cuneo, Italy; b School of Medical Physics, University of Torino, Torino, Italy; c INFN, Torino, Italy Introduction: The aim of this work was to study the distribution of liver SUV in a large population of patients undergoing whole-body 18FDG Positron Emission Tomography/Computed Tomography (PET/CT). Material and Methods: LIDEA (LIver DEtection Algorithm) is an algorithm that automatically detects the liver position in whole-body 18Ffluorine-deoxyglucose PET/CT and calculates the mean and the standard deviation of voxels’ Standardized Uptake Value inside it. Within this work we added other two metrics to describe image noise. Image Roughness (IR) measures the pixel to pixel variability in the single image, as the average in different ROI of the coefficient of variation (COV) of the pixel values. The Background variability (BV) is the noise quantification proposed in the NEMA NU-2 instructions and it is calculated as the COV of the ROI averages across the ROIs. Results: In the 630 analyzed PET scans, coming from more than 40 PET centers distributed in 21 countries, the algorithm identified the liver in 98.9% of the cases. The liver SUV was (2.01 ± 0.55). The distribution of liver SUV of the patients was not Gaussian (p = 4e−8 with the Shapiro–Wilk test). The values of the noise indexes were SD (0.32 ± 0.12), IR (0.16 ± 0.06) and BV (0.07 ± 0.05). Conclusion: The algorithm was used to retrieve average liver values in a large population of PET/CT scan and to analyze image noise with different metrics. These would be used to automatically define good/bad statistics scan within a framework of multi-center clinical trials. http://dx.doi.org/10.1016/j.ejmp.2016.01.339
C.334 DEPTH-OF-INTERACTION DISCRIMINATION TO CORRECT PARALLAX ERROR IN HIGH RESOLUTION PET M. Bettiol *,a, E. Preziosi b, C. Borrazzo a, M.N. Cinti a, A.J. Gonzalez c, R. Pani d. a Department of Molecular Medicine, Sapienza, Roma, Italy; b Doctorate School of Biology and Molecular Medicine – SAIMLAL Department, Morphofunctional Sciences – Biophysics, Roma, Italy; c Institute for Instrumentation in Molecular
Imaging, I3M-CSIC, Valencia, Spain; d Department of Sciences and Medical and Surgical Biotechnologies, Sapienza, Roma, Italy Introduction: High resolution PET systems are often limited by the parallax error due to the lack of information about the Depth of Interaction (DoI) inside the crystal of the incoming gamma-photons. In this work, an effortless DoI estimator suitable for monolithic scintillation crystals has been proposed. This development was done in the framework of the MindView PET/MRI brain imaging European Project. Materials and Methods: A test PET module with a 50 × 50 × 20 mm monolithic Lutetium Yttrium oxyorthosilicate (LYSO) crystal coupled to a 12 × 12 SiPM array has been employed. Experimental measurements from a 45 degree slanted pencil beam of 511 keV gamma photons have been performed. The purpose of the slanted beam is to obtain an image in which there is a direct correlation between the interaction position and the DoI. In addition, for calibration and validation of the method, the Geant4 simulation has been also used. DoI estimation has been performed via a novel parameter related to the shape of scintillation light distribution produced by the gamma photon interaction inside the crystal. Furthermore, we show an innovative, DoIdependent, position algorithm based on the manipulation of the same distribution. Results: The proposed method provides a DoI resolution of about 5 mm. This leads to a parallax error reduction of about 75% in case of 30 mm diameter PET system. Moreover, thanks to the DoI-dependent position algorithm, the detector spatial resolution is improved of a factor of 15%. As a consequence of these results, the overall spatial resolution improves from 20 to 60% in respect to a PET system without DoI-dependent corrections. Conclusion: In respect to a high efficiency PET module without DoIdependent corrections, the proposed methods allow an improvement in overall spatial resolution ranging from 20% to 60%, depending on sourcering center distance. Moreover, this method is particularly engaging since it is simple to implement and does not require additional hardware equipment. http://dx.doi.org/10.1016/j.ejmp.2016.01.340
C.335 GEOMETRY VARIABILITY IN THE MEASUREMENT OF GAMMA, BETA AND ALPHA EMITTERS IN RADIONUCLIDE CALIBRATORS C. Bianchi *,a, S.A. Abd Hamid b, P. Colleoni a, S. Andreoli a. a A.O. Papa Giovanni XXIII, Bergamo, Italy; b The Brunei Cancer Centre, Brunei Darussalam, Brunei Introduction: The aim of this work is to study the variability of radionuclide calibrators outcome with different source volume and container. Measurements were carried out together with a medical physicist of The Brunei Cancer Centre, during a IAEA fellowship in our hospital. Material and Methods: The variation in calibrator response was studied varying the solution volume in a glass vial and syringes (from 1 to 10 mL). Activity measured in the syringe was compared with activity difference in the vial before and after withdrawal and with the value determined from the vial activity concentration. Volumes were determined by weighting vial with a precision scale. Measurements were made with 2 calibrators (Capintec CRC15R and 15PET) and with 5 isotopes: 99mTc, 123I, 131I, 223Ra, 90Y. Because 90Y is incorporated in a resin microsphere and the withdrawal of a uniform solution is difficult, no syringe measurements were made. Results: As expected, with 99mTc, the calibrator outcome does not significantly vary with the change in volume (<1% from 0.5 to 30 mL) and with different volume syringes (<1.2%). The same behavior is observed for 223Ra, in which the α radiation does not influence the calibrator response with different volume and syringes. Variation in the outcome is observed for 123I, because of a production of characteristic x-rays. The maximum variation is 4% for volume in the vial ranging from 0.5 to 13 mL and the activity measured in syringes deviates from the vial one not less than 20%. The 90Y source self attenuation is important: for a volume of 1 mL the calibrator outcome is 19% higher than 5 mL; over 6 mL volume the variability is lower. With 131I β emissions calibrator response slightly changes between vial and syringes (<4%).
Abstracts/Physica Medica 32 (2016) e97–e115
of this study was to measure FDG PET standardized uptake values (SUVs) change over time in three physiological compartments: liver, lung and Blood Pool (BP). Material and Methods: 100 patients enrolled in Dual Point clinical trial on Hodgkin disease were retrospectively evaluated. PET/CT imaging was performed at either 1 h (PET1) and at 2 h (PET2) after FDG administration. DICOM headers were analyzed to collect information on the scanning procedure. A three-dimensional region of interest (ROI) was drawn on the fused PET image to measure the mean SUV of the three compartments at PET1 (SUV1) and at PET2 (SUV2). DeltaSUV ((SUV2-SUV1)/SUV1) and normalized SUV (SUV/((SUV1 + SUV2)/2)) were calculated for each pair of data. Linear model has been applied to the data. Kolmogorov–Smirnov (KS) test was used to compare the model to the data. Results: Uptake time mean values were (72 ± 17) min and (133 ± 18) min for PET1 and PET2 respectively. The liver’s SUV1 and SUV2 for all patients were (1.82 ± 0.40) g/mL and (1.52 ± 0.35) g/mL respectively while the BP’s SUV1 and SUV2 were (1.37 ± 0.39) g/mL and (1.07 ± 0.36) g/mL respectively. Lung’s SUV1 was (0.40 ± 0.10) g/mL and SUV2 was (0.33 ± 0.09) g/mL. The mean liver, lung and BP SUVs were (−16 ± 8)% (range: −35% to 0%), (−23 ± 12)% (range: −57% to −1%) and (−18 ± 10)% (range: −61% to −1%). Mean SUV variations were respectively 0.25, 0.10, and 0.27 SUV/hour for liver, lung and BP SUVs. The normalized SUV mildly correlated to the uptake time (Pearson correlation coefficients were 0.63, 0.58 and 0.53 for liver, BP and lung respectively). SUV1 was recalculated using the linear model and compared to measured data. KS values were 0.10(p = 0.99), 0.12(p = 0.99) and 0.13(p = 0.99) for liver, lung and BP, respectively. Conclusion: SUV decreases over time in the physiological compartments. http://dx.doi.org/10.1016/j.ejmp.2016.01.338
C.333 APPLICATION OF LIDEA (LIVER DETECTION ALGORITHM) FOR PET/CT SCANS E. Bertone *,a, F. Bergesio a,b, A. Terulla a, P. Cerello c, S. Chauvie a. a Medical Physics Unit, ASO S. Croce e Carle, Cuneo, Italy; b School of Medical Physics, University of Torino, Torino, Italy; c INFN, Torino, Italy Introduction: The aim of this work was to study the distribution of liver SUV in a large population of patients undergoing whole-body 18FDG Positron Emission Tomography/Computed Tomography (PET/CT). Material and Methods: LIDEA (LIver DEtection Algorithm) is an algorithm that automatically detects the liver position in whole-body 18Ffluorine-deoxyglucose PET/CT and calculates the mean and the standard deviation of voxels’ Standardized Uptake Value inside it. Within this work we added other two metrics to describe image noise. Image Roughness (IR) measures the pixel to pixel variability in the single image, as the average in different ROI of the coefficient of variation (COV) of the pixel values. The Background variability (BV) is the noise quantification proposed in the NEMA NU-2 instructions and it is calculated as the COV of the ROI averages across the ROIs. Results: In the 630 analyzed PET scans, coming from more than 40 PET centers distributed in 21 countries, the algorithm identified the liver in 98.9% of the cases. The liver SUV was (2.01 ± 0.55). The distribution of liver SUV of the patients was not Gaussian (p = 4e−8 with the Shapiro–Wilk test). The values of the noise indexes were SD (0.32 ± 0.12), IR (0.16 ± 0.06) and BV (0.07 ± 0.05). Conclusion: The algorithm was used to retrieve average liver values in a large population of PET/CT scan and to analyze image noise with different metrics. These would be used to automatically define good/bad statistics scan within a framework of multi-center clinical trials. http://dx.doi.org/10.1016/j.ejmp.2016.01.339
C.334 DEPTH-OF-INTERACTION DISCRIMINATION TO CORRECT PARALLAX ERROR IN HIGH RESOLUTION PET M. Bettiol *,a, E. Preziosi b, C. Borrazzo a, M.N. Cinti a, A.J. Gonzalez c, R. Pani d. a Department of Molecular Medicine, Sapienza, Roma, Italy; b Doctorate School of Biology and Molecular Medicine – SAIMLAL Department, Morphofunctional Sciences – Biophysics, Roma, Italy; c Institute for Instrumentation in Molecular
Imaging, I3M-CSIC, Valencia, Spain; d Department of Sciences and Medical and Surgical Biotechnologies, Sapienza, Roma, Italy Introduction: High resolution PET systems are often limited by the parallax error due to the lack of information about the Depth of Interaction (DoI) inside the crystal of the incoming gamma-photons. In this work, an effortless DoI estimator suitable for monolithic scintillation crystals has been proposed. This development was done in the framework of the MindView PET/MRI brain imaging European Project. Materials and Methods: A test PET module with a 50 × 50 × 20 mm monolithic Lutetium Yttrium oxyorthosilicate (LYSO) crystal coupled to a 12 × 12 SiPM array has been employed. Experimental measurements from a 45 degree slanted pencil beam of 511 keV gamma photons have been performed. The purpose of the slanted beam is to obtain an image in which there is a direct correlation between the interaction position and the DoI. In addition, for calibration and validation of the method, the Geant4 simulation has been also used. DoI estimation has been performed via a novel parameter related to the shape of scintillation light distribution produced by the gamma photon interaction inside the crystal. Furthermore, we show an innovative, DoIdependent, position algorithm based on the manipulation of the same distribution. Results: The proposed method provides a DoI resolution of about 5 mm. This leads to a parallax error reduction of about 75% in case of 30 mm diameter PET system. Moreover, thanks to the DoI-dependent position algorithm, the detector spatial resolution is improved of a factor of 15%. As a consequence of these results, the overall spatial resolution improves from 20 to 60% in respect to a PET system without DoI-dependent corrections. Conclusion: In respect to a high efficiency PET module without DoIdependent corrections, the proposed methods allow an improvement in overall spatial resolution ranging from 20% to 60%, depending on sourcering center distance. Moreover, this method is particularly engaging since it is simple to implement and does not require additional hardware equipment. http://dx.doi.org/10.1016/j.ejmp.2016.01.340
C.335 GEOMETRY VARIABILITY IN THE MEASUREMENT OF GAMMA, BETA AND ALPHA EMITTERS IN RADIONUCLIDE CALIBRATORS C. Bianchi *,a, S.A. Abd Hamid b, P. Colleoni a, S. Andreoli a. a A.O. Papa Giovanni XXIII, Bergamo, Italy; b The Brunei Cancer Centre, Brunei Darussalam, Brunei Introduction: The aim of this work is to study the variability of radionuclide calibrators outcome with different source volume and container. Measurements were carried out together with a medical physicist of The Brunei Cancer Centre, during a IAEA fellowship in our hospital. Material and Methods: The variation in calibrator response was studied varying the solution volume in a glass vial and syringes (from 1 to 10 mL). Activity measured in the syringe was compared with activity difference in the vial before and after withdrawal and with the value determined from the vial activity concentration. Volumes were determined by weighting vial with a precision scale. Measurements were made with 2 calibrators (Capintec CRC15R and 15PET) and with 5 isotopes: 99mTc, 123I, 131I, 223Ra, 90Y. Because 90Y is incorporated in a resin microsphere and the withdrawal of a uniform solution is difficult, no syringe measurements were made. Results: As expected, with 99mTc, the calibrator outcome does not significantly vary with the change in volume (<1% from 0.5 to 30 mL) and with different volume syringes (<1.2%). The same behavior is observed for 223Ra, in which the α radiation does not influence the calibrator response with different volume and syringes. Variation in the outcome is observed for 123I, because of a production of characteristic x-rays. The maximum variation is 4% for volume in the vial ranging from 0.5 to 13 mL and the activity measured in syringes deviates from the vial one not less than 20%. The 90Y source self attenuation is important: for a volume of 1 mL the calibrator outcome is 19% higher than 5 mL; over 6 mL volume the variability is lower. With 131I β emissions calibrator response slightly changes between vial and syringes (<4%).