- Email: [email protected]
70. Computer aided detection system for the automated classification of clustered microcalcifications in digital mammograms
106
Abstracts / Physica Medica 56 (2018) 59–132
and repeated for different angles between the longitudinal axis and the line formed by the center of the irradiated region in the phantom and the measurement point. The used survey meter was the ATOMTEX AT1121. Results. The scatter radiation (H*(10) in lSv/mA*min at 1 m distance from the center of the irradiated region in the phantom to the measurement point) was not isotropic at different angles for the same irradiation conditions. For radiation protection purpose only the maximum measured values are reported in the following table.
Collimation
80 KVp
1 KVp
125 KVp
140 KVp
SMALL MEDIUM LARGE
2 3 4
4 7 9
8 13 18
10 20 25
Conclusions. The reported H*(10) values give an idea of the scattered radiation from a kilovoltage CBCT installed on a VARIAN TRUEBEAM linac. A new CBCT installation with similar spectral features (e.g. same target and filtration) and outside a radiotherapy environment may benefit from these measurements for radiation protection purposes.
References 1. European Commission – Radiation Protection No 172. Cone beam CT for dental and maxillofacial radiology. 2012; ISSN 1681-6803. 2. International Commission on Radiological Protection. Radiological Protection in Cone Beam Computed Tomography (CBCT). ICRP Publication 129. 2015; Annals of the ICRP. https://doi.org/10.1016/j.ejmp.2018.04.078
Methods. In total 393 subjects have been recruited in the exposed group, they have completed study questionnaires on work history and risk factors for lens opacities and received an ophthalmological examination. As for the control group, 243 subjects have been recruited, completing the same questionnaire on risk factors for lens opacities and ophthalmological examination. Efforts have been made to develop 2 approaches to assess retrospectively the cumulative eye lens doses of the recruited cardiologists. The first approach is based on the individual work history in combination with published eye lens dose data, while the second approach is based on individual routine whole body dosimetry and its conversion to eye lens dose. Innovative approaches have been used for the statistical analysis by using a mixed linear regression and polytomous logistic regression approach, which permit a correct modelling of the lens opacities by taking into account the correlation of the soring outcomes of both eyes in the radio-induced risk estimation as well as dose estimation uncertainties. Results. More than 200 dose measurements have been performed in clinical practice to validate both calculation approaches. 1st approach resulted in the most satisfactory with an average ratio between measured and calculated eye lens dose of 0.96 [95%CI: 0.87-1.09] for the left eye and 0.50 [95%CI: 0.44-0.56] for the right eye. The analyses established a significant impact of radiation dose in the occurrence of PSC opacities with a relative risk for ICs of OR = 2.62 (95%CI 1.35–5.08). Conclusion. A linear no threshold model provided the better fit of the lens opacities dose-response relationship with an excess relative risk per Gy equal to 1.31 (95% CI 0.13–3.32). Acknowledgement The research has received funding from the European Atomic Energy Community’s Seventh Framework Programme FP7/2007– 2011 under grant agreement no 604984 (OPERRA). https://doi.org/10.1016/j.ejmp.2018.04.079
69. The European epidemiological study (EURALOC) on radiationinduced lens opacities among interventional cardiologists L. Struelens a, P. Covens b, M. Benadjaoud c, A. Auvinen d, E. Gianicolo e, A. Wegener f, J. Domienik g, E. Carinou h, O. Dragusin i, P. Teles j, A. Widmark k, O. Ciraj-Bjelac l, M. Grazia Andreassi m, R. Padovani n a
SCKCEN, Mol, Belgium VUB, Brussels, Belgium c IRSN, Fontenay-aux-Roses, France d STUK, Helsinki, Finland e University Mainz UMC, Mainz, Germany f University of Bonn-Medical Centre, Bonn, Germany g Nofer Institute of Occupational Medicine NIOM, Lodz, Poland h GAEC, Paraskevi, Greece i Entente des Hôpitaux Luxembourgeois FHL, Bertrange, Luxembourg j Centro de Ciências e Tecnologias Nucleares, Bobadela LRS, Portugal k NRPA, Østerås, Norway l University of Belgrade, Vinca Institute of Nuclear Sciences, Belgrade, Serbia m IFC-CNR, Pisa, Italy n ICTP, Trieste, Italy
70. Computer aided detection system for the automated classification of clustered microcalcifications in digital mammograms R. Massafra a, A. Fanizzi a, T. Basile b,c, R. Bellotti b,c, R. Carbonara c, D. La Forgia a, M. Moschetta c, P. Tamborra a, S. Tangaro b,c, L. Losurdo a, V. Didonna a
b
Purpose. Low dose radiation effect on the eye lens has been an area of interest in numerous epidemiological studies. The European epidemiological study EURALOC was conducted between December 2014 and May 2017 with the objective to investigate a possible dose-response relationship by targeting a sufficiently large study population with reasonably high exposure levels, namely interventional cardiologists (ICs).
a
I.R.C.C.S. ‘‘Giovanni Paolo II”, National Cancer Centre, Bari, Italy National Institute for Nuclear Physics – INFN, Bari Division, Bari, Italy c University of Bari ‘‘Aldo Moro”, Bari, Italy b
Purpose . Mammography is the most effective and low-cost method for the early detection of breast cancers. The aim of this study was to develop an automated model in order to improve detection and characterization of clustered microcalcifications on full-field digital mammograms (FFDM). Methods. We analyzed 98 digital mammograms extracted from the public database Breast Cancer Digital Repository with 276 microcalcification clusters; these images were previously evaluated in double blind by two radiologists which had identified the microcalcification clusters. We identified some regions of interest (ROI) on mammograms after pre-processing by using the Circular Hough Transform algorithm in order to recognize circles corresponding to the microcalcifications. Then, we selected morphological and morphometric features for each ROI, such as Speeded Up Robust Feature, as well as classic statistical features based on Haar Transform. These features were used for giving instructions to a Random Forest classifier in order to recognize – riga clustered microcalcifications normal
Abstracts / Physica Medica 56 (2018) 59–132 Table 1 Demographic and detection performances results. Breast density classification
Mean age ± Std
Sensitivity
False Positive per image
Under 50% 51–75% Over 75% Total
58,84 ± 10,63 51,25 ± 11,07 45,38 ± 3,56 53,26 ± 11,37
93,33% 90,91% 88,41% 90,48%
3,27 3,51 4,73 3,54
and abnormal ROIs. Finally, we tested the performance of – riga this automated model in cross-validation and with statistical measurements. Results. Statistical results (Table 1) showed good performance of proposed model in automatic detection of breast clustered microcalcifications on FFDM (sensitivity over 90% with 3.54 false positives – riga per image), even in young patients with dense breast tissue (sensitivity over 88%) and according to published data [1]. Also classification performance of clustered microcalcifications (AUC 98,6 ± 0,1, Accuracy 97,6 ± 0,2%, Sensitivity 97,7 ± 0,4%, Specificity 96,2 ± 0,4%) was comparable with the state of the art [2]. Conclusions. The proposed automated model enables to improve detection of clustered microcalcifications that could be characterized by difficult diagnostic interpretation especially when occurred in dense breast parenchyma. The proposed model results highly performing and comparable to the state-of-art approaches.
References 1. Wang J, Nishikawa RM, Yang Y. Improving the accuracy in detection of clustered microcalcifications with a context-sensitive classification model. Med Phys 2016;43(1):159–70. 2. Guo YN, Dong M, Yang Z, Gao X, Wang K, Luo C. A new method of detecting micro-calcification clusters in mammograms using contourlet transform and non-linking simplified PCNN. Comput Methods Programs Biomed 2016;130:31–45. https://doi.org/10.1016/j.ejmp.2018.04.080
71. Contrast-enhanced spectral mammography. Analysis of region of interest based on gray levels: a preliminary multicenter study in Puglia (Italy) L. Losurdo c, S. Tangaro a,b, V. Didonna c, T.M.A. Basile a,b, R. Bellotti a,b, R. Carbonara b, F. Cinelli d, A. Fanizzi c, F. Fiorentino d, A. Gorgoglione d, M. Moschetta b, P. Tamborra c, D. La Forgia c, R. Massafra c a
National Institute for Nuclear Physics – INFN, Bari Division, Bari, Italy University of Bari ‘‘Aldo Moro”, Bari, Italy c I.R.C.C.S. ‘‘Giovanni Paolo II”, National Cancer Centre, Bari, Italy d I.R.C.C.S. ‘‘Casa Sollievo della Sofferenza”, S. Giovanni Rotondo, Foggia, Italy b
Purpose. Contrast-Enhanced Spectral Mammography (CESM) allows the acquisition of low- and high-energy digital mammograms with Dual-Energy technique after a single injection of iodinated contrast medium (CM) obtaining the production of recombined mammographic images [1,2]. The aim of this paper is to characterize ROI and measure the gray-level parenchymal background in order to improve the lesion detection in CESM. Methods. We have selected 42 patients positive to the methodic for the presence of at least one findings after histological examination.We have evaluated 65 lesions (52 malignant and 13 benign) from 0.5 to 13.5 cm.
107
Primary and secondary (if present) lesions have been identified and their diameters have been measured in axial projection. Regions including the parenchymal background and the non-contrasted background were also marked in both low-energy and recombined images.For each region the statistical parameters of gray levels were recorded by CESM instrumentation and have been elaborated by multivariate statistics and machine learning techniques in order to characterize each region and define a background intensity indicator, not yet defined objectively. Results. The analysis on our available dataset seems to underline significant differences between ROIs with lesions and regions marked on the parenchymal background with respect to the coefficient of variation, i.e. standard deviation of the gray levels of the marked area compared to the mean value of the same) in recombined images.We have found an increase of the coefficient of ROIs greater than 20% with respect to the coefficient of the regions marked on parenchymal background in 57 lesions. Conclusions. As preliminary results, an indicator to detect the parenchymal background can be identified as the coefficient of variation. Data collection is currently ongoing because a more massive data sample will be useful to increase the sensitivity in the lesion detection by CESM device, even in patients with a medium-high value of background. References 1. Lobbes MBI, Smidt ML, et al.. Contrast enh. mammography: techniques, current results, and potential indications. Clin Radiol 2013;68:935–44. 2. Vestito A., La Forgia D. Ancona A. et al. Contrast Enhanced Spectral Mammography: la nostra esperienza. Il giornale italiano di Radiologia Medica 2014; 1: 1002-1008. https://doi.org/10.1016/j.ejmp.2018.04.081
72. Digital breast tomosynthesis: Flat panel and photon counting detector comparison A. Loria a, P. Signorotto a, M. Campoleoni b, N. Paruccini c, R. Villa c, E. Venturini d, P. Panizza d, A. del Vecchio a a IRCCS San Raffaele Scientific Institute, Medical Physics Department, Milan, Italy b Fondazione IRCCS Ca’ Granda Ospedale Maggiore Policlinico, Medical Physics Department, Milan, Italy c ASST Ospedale San Gerardo, Medical Physics Department, Monza, Italy d IRCCS San Raffaele Scientific Institute, Breast Radiology Department, Milan, Italy
Purpose. In this study three digital breast tomosynthesis (DBT) devices equipped with different flat panel detectors (FPD) and a prototype equipped with a scan-spectral photon counting detector (PCD) are compared. The aim is to evaluate if a PCD device can guarantee a comparable or even better image quality delivering lower radiation doses than FPD devices. Methods. Image quality performances were evaluated exposing two image quality DBT phantoms, Tomophan and Agatha and a homemade phantom for the evaluation of low contrast detectability (LCD). Exposures were performed in automatic exposure control (AEC) mode, both with standard (ST) and high resolution (HR) modality when available. Images with the lowest achievable postprocessing were analyzed. Geometric distortion, signal-differenceto-noise ratio (SDNR), LCD with the statistical method, in-plane resolution in terms of modulation transfer function (MTF) in scan and sub-scan directions, slice-sensitivity profile (SSP) and artifact spread function (ASF) were evaluated.
Abstracts / Physica Medica 56 (2018) 59–132
and repeated for different angles between the longitudinal axis and the line formed by the center of the irradiated region in the phantom and the measurement point. The used survey meter was the ATOMTEX AT1121. Results. The scatter radiation (H*(10) in lSv/mA*min at 1 m distance from the center of the irradiated region in the phantom to the measurement point) was not isotropic at different angles for the same irradiation conditions. For radiation protection purpose only the maximum measured values are reported in the following table.
Collimation
80 KVp
1 KVp
125 KVp
140 KVp
SMALL MEDIUM LARGE
2 3 4
4 7 9
8 13 18
10 20 25
Conclusions. The reported H*(10) values give an idea of the scattered radiation from a kilovoltage CBCT installed on a VARIAN TRUEBEAM linac. A new CBCT installation with similar spectral features (e.g. same target and filtration) and outside a radiotherapy environment may benefit from these measurements for radiation protection purposes.
References 1. European Commission – Radiation Protection No 172. Cone beam CT for dental and maxillofacial radiology. 2012; ISSN 1681-6803. 2. International Commission on Radiological Protection. Radiological Protection in Cone Beam Computed Tomography (CBCT). ICRP Publication 129. 2015; Annals of the ICRP. https://doi.org/10.1016/j.ejmp.2018.04.078
Methods. In total 393 subjects have been recruited in the exposed group, they have completed study questionnaires on work history and risk factors for lens opacities and received an ophthalmological examination. As for the control group, 243 subjects have been recruited, completing the same questionnaire on risk factors for lens opacities and ophthalmological examination. Efforts have been made to develop 2 approaches to assess retrospectively the cumulative eye lens doses of the recruited cardiologists. The first approach is based on the individual work history in combination with published eye lens dose data, while the second approach is based on individual routine whole body dosimetry and its conversion to eye lens dose. Innovative approaches have been used for the statistical analysis by using a mixed linear regression and polytomous logistic regression approach, which permit a correct modelling of the lens opacities by taking into account the correlation of the soring outcomes of both eyes in the radio-induced risk estimation as well as dose estimation uncertainties. Results. More than 200 dose measurements have been performed in clinical practice to validate both calculation approaches. 1st approach resulted in the most satisfactory with an average ratio between measured and calculated eye lens dose of 0.96 [95%CI: 0.87-1.09] for the left eye and 0.50 [95%CI: 0.44-0.56] for the right eye. The analyses established a significant impact of radiation dose in the occurrence of PSC opacities with a relative risk for ICs of OR = 2.62 (95%CI 1.35–5.08). Conclusion. A linear no threshold model provided the better fit of the lens opacities dose-response relationship with an excess relative risk per Gy equal to 1.31 (95% CI 0.13–3.32). Acknowledgement The research has received funding from the European Atomic Energy Community’s Seventh Framework Programme FP7/2007– 2011 under grant agreement no 604984 (OPERRA). https://doi.org/10.1016/j.ejmp.2018.04.079
69. The European epidemiological study (EURALOC) on radiationinduced lens opacities among interventional cardiologists L. Struelens a, P. Covens b, M. Benadjaoud c, A. Auvinen d, E. Gianicolo e, A. Wegener f, J. Domienik g, E. Carinou h, O. Dragusin i, P. Teles j, A. Widmark k, O. Ciraj-Bjelac l, M. Grazia Andreassi m, R. Padovani n a
SCKCEN, Mol, Belgium VUB, Brussels, Belgium c IRSN, Fontenay-aux-Roses, France d STUK, Helsinki, Finland e University Mainz UMC, Mainz, Germany f University of Bonn-Medical Centre, Bonn, Germany g Nofer Institute of Occupational Medicine NIOM, Lodz, Poland h GAEC, Paraskevi, Greece i Entente des Hôpitaux Luxembourgeois FHL, Bertrange, Luxembourg j Centro de Ciências e Tecnologias Nucleares, Bobadela LRS, Portugal k NRPA, Østerås, Norway l University of Belgrade, Vinca Institute of Nuclear Sciences, Belgrade, Serbia m IFC-CNR, Pisa, Italy n ICTP, Trieste, Italy
70. Computer aided detection system for the automated classification of clustered microcalcifications in digital mammograms R. Massafra a, A. Fanizzi a, T. Basile b,c, R. Bellotti b,c, R. Carbonara c, D. La Forgia a, M. Moschetta c, P. Tamborra a, S. Tangaro b,c, L. Losurdo a, V. Didonna a
b
Purpose. Low dose radiation effect on the eye lens has been an area of interest in numerous epidemiological studies. The European epidemiological study EURALOC was conducted between December 2014 and May 2017 with the objective to investigate a possible dose-response relationship by targeting a sufficiently large study population with reasonably high exposure levels, namely interventional cardiologists (ICs).
a
I.R.C.C.S. ‘‘Giovanni Paolo II”, National Cancer Centre, Bari, Italy National Institute for Nuclear Physics – INFN, Bari Division, Bari, Italy c University of Bari ‘‘Aldo Moro”, Bari, Italy b
Purpose . Mammography is the most effective and low-cost method for the early detection of breast cancers. The aim of this study was to develop an automated model in order to improve detection and characterization of clustered microcalcifications on full-field digital mammograms (FFDM). Methods. We analyzed 98 digital mammograms extracted from the public database Breast Cancer Digital Repository with 276 microcalcification clusters; these images were previously evaluated in double blind by two radiologists which had identified the microcalcification clusters. We identified some regions of interest (ROI) on mammograms after pre-processing by using the Circular Hough Transform algorithm in order to recognize circles corresponding to the microcalcifications. Then, we selected morphological and morphometric features for each ROI, such as Speeded Up Robust Feature, as well as classic statistical features based on Haar Transform. These features were used for giving instructions to a Random Forest classifier in order to recognize – riga clustered microcalcifications normal
Abstracts / Physica Medica 56 (2018) 59–132 Table 1 Demographic and detection performances results. Breast density classification
Mean age ± Std
Sensitivity
False Positive per image
Under 50% 51–75% Over 75% Total
58,84 ± 10,63 51,25 ± 11,07 45,38 ± 3,56 53,26 ± 11,37
93,33% 90,91% 88,41% 90,48%
3,27 3,51 4,73 3,54
and abnormal ROIs. Finally, we tested the performance of – riga this automated model in cross-validation and with statistical measurements. Results. Statistical results (Table 1) showed good performance of proposed model in automatic detection of breast clustered microcalcifications on FFDM (sensitivity over 90% with 3.54 false positives – riga per image), even in young patients with dense breast tissue (sensitivity over 88%) and according to published data [1]. Also classification performance of clustered microcalcifications (AUC 98,6 ± 0,1, Accuracy 97,6 ± 0,2%, Sensitivity 97,7 ± 0,4%, Specificity 96,2 ± 0,4%) was comparable with the state of the art [2]. Conclusions. The proposed automated model enables to improve detection of clustered microcalcifications that could be characterized by difficult diagnostic interpretation especially when occurred in dense breast parenchyma. The proposed model results highly performing and comparable to the state-of-art approaches.
References 1. Wang J, Nishikawa RM, Yang Y. Improving the accuracy in detection of clustered microcalcifications with a context-sensitive classification model. Med Phys 2016;43(1):159–70. 2. Guo YN, Dong M, Yang Z, Gao X, Wang K, Luo C. A new method of detecting micro-calcification clusters in mammograms using contourlet transform and non-linking simplified PCNN. Comput Methods Programs Biomed 2016;130:31–45. https://doi.org/10.1016/j.ejmp.2018.04.080
71. Contrast-enhanced spectral mammography. Analysis of region of interest based on gray levels: a preliminary multicenter study in Puglia (Italy) L. Losurdo c, S. Tangaro a,b, V. Didonna c, T.M.A. Basile a,b, R. Bellotti a,b, R. Carbonara b, F. Cinelli d, A. Fanizzi c, F. Fiorentino d, A. Gorgoglione d, M. Moschetta b, P. Tamborra c, D. La Forgia c, R. Massafra c a
National Institute for Nuclear Physics – INFN, Bari Division, Bari, Italy University of Bari ‘‘Aldo Moro”, Bari, Italy c I.R.C.C.S. ‘‘Giovanni Paolo II”, National Cancer Centre, Bari, Italy d I.R.C.C.S. ‘‘Casa Sollievo della Sofferenza”, S. Giovanni Rotondo, Foggia, Italy b
Purpose. Contrast-Enhanced Spectral Mammography (CESM) allows the acquisition of low- and high-energy digital mammograms with Dual-Energy technique after a single injection of iodinated contrast medium (CM) obtaining the production of recombined mammographic images [1,2]. The aim of this paper is to characterize ROI and measure the gray-level parenchymal background in order to improve the lesion detection in CESM. Methods. We have selected 42 patients positive to the methodic for the presence of at least one findings after histological examination.We have evaluated 65 lesions (52 malignant and 13 benign) from 0.5 to 13.5 cm.
107
Primary and secondary (if present) lesions have been identified and their diameters have been measured in axial projection. Regions including the parenchymal background and the non-contrasted background were also marked in both low-energy and recombined images.For each region the statistical parameters of gray levels were recorded by CESM instrumentation and have been elaborated by multivariate statistics and machine learning techniques in order to characterize each region and define a background intensity indicator, not yet defined objectively. Results. The analysis on our available dataset seems to underline significant differences between ROIs with lesions and regions marked on the parenchymal background with respect to the coefficient of variation, i.e. standard deviation of the gray levels of the marked area compared to the mean value of the same) in recombined images.We have found an increase of the coefficient of ROIs greater than 20% with respect to the coefficient of the regions marked on parenchymal background in 57 lesions. Conclusions. As preliminary results, an indicator to detect the parenchymal background can be identified as the coefficient of variation. Data collection is currently ongoing because a more massive data sample will be useful to increase the sensitivity in the lesion detection by CESM device, even in patients with a medium-high value of background. References 1. Lobbes MBI, Smidt ML, et al.. Contrast enh. mammography: techniques, current results, and potential indications. Clin Radiol 2013;68:935–44. 2. Vestito A., La Forgia D. Ancona A. et al. Contrast Enhanced Spectral Mammography: la nostra esperienza. Il giornale italiano di Radiologia Medica 2014; 1: 1002-1008. https://doi.org/10.1016/j.ejmp.2018.04.081
72. Digital breast tomosynthesis: Flat panel and photon counting detector comparison A. Loria a, P. Signorotto a, M. Campoleoni b, N. Paruccini c, R. Villa c, E. Venturini d, P. Panizza d, A. del Vecchio a a IRCCS San Raffaele Scientific Institute, Medical Physics Department, Milan, Italy b Fondazione IRCCS Ca’ Granda Ospedale Maggiore Policlinico, Medical Physics Department, Milan, Italy c ASST Ospedale San Gerardo, Medical Physics Department, Monza, Italy d IRCCS San Raffaele Scientific Institute, Breast Radiology Department, Milan, Italy
Purpose. In this study three digital breast tomosynthesis (DBT) devices equipped with different flat panel detectors (FPD) and a prototype equipped with a scan-spectral photon counting detector (PCD) are compared. The aim is to evaluate if a PCD device can guarantee a comparable or even better image quality delivering lower radiation doses than FPD devices. Methods. Image quality performances were evaluated exposing two image quality DBT phantoms, Tomophan and Agatha and a homemade phantom for the evaluation of low contrast detectability (LCD). Exposures were performed in automatic exposure control (AEC) mode, both with standard (ST) and high resolution (HR) modality when available. Images with the lowest achievable postprocessing were analyzed. Geometric distortion, signal-differenceto-noise ratio (SDNR), LCD with the statistical method, in-plane resolution in terms of modulation transfer function (MTF) in scan and sub-scan directions, slice-sensitivity profile (SSP) and artifact spread function (ASF) were evaluated.