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76. Comparison between synthetic and digital mammography in different breast tomosynthesis systems
Abstracts / Physica Medica 56 (2018) 59–132
Images were acquired in automatic mode. MGDs were measured in accordance with the Mammo Protocol of the European Federation of Organisations for Medical Physics (EFOMP) [1]. Where available, Organ Doses (ODGs), calculated by manufacturers, were collected from the Header DICOM of the corresponding images and the differences with respect MGDs were evaluated. Results. All the MGDs values are within the EFOMP Mammo Protocol limits. Differences from MGDs and ODGs values are in between ±20% for the majority of systems, except for few ones. For 20 mm, 45 mm and 60 mm phantom thickness, the ranges of MGDs extend from 0.37 mGy to 1.00 mGy, 0.65 mGy to 2.40 mGy and from 1.33 mGy to 4.19 mGy respectively. As expected, MGDs show a strong dependence on FFDM system technology: the Photon Counting system has the lowest MGDs values, while the CR systems exhibit the highest ones. Conclusions. Our results confirm the importance of monitoring periodically the level of technology employed in a regional screening program by means of a dose survey, in order to promote a renewal of the FFDM imaging systems in accordance with the image quality preferences of the radiologists involved. This survey procedure would be functional also to guarantee the homogeneity of the Risk-Benefit Ratio. Reference 1. Gennaro G et al., EFOMP Mammo Working Group Protocol, March 2015. https://doi.org/10.1016/j.ejmp.2018.04.084
75. Image quality and dose measurements in digital breast tomosynthesis O. Ortenzia a, R. Rossi a, M. Bertolini b, A. Nitrosi b, C. Ghetti a a
Department of Medical Physics, University Hospital of Parma, Italy Department of Medical Physics, Santa Maria Nuova Hospital of Reggio Emilia, Italy
109
and increasing cancer detection-rate compared to 2D mammography [1]. The aim of this study is to compare different commercial DBT units in terms of image quality and dose using a set of new phantoms. Methods. The CDMAM phantom was used to compare the Contrast-Details curves in 2D and DBT mode principally for stability assessment. The TomophanTM phantom was used to perform measurements of Slice Sensitive Profile, slice-to-slice incrementation, chest-wall offset, z-axis geometry, Artefact Spread Function, low contrast detectability. An aluminium edge was employed to determine in plane MTF. The Pixmam phantom was used to estimate the AGD and to calculate SDNR. All measurements were performed on reconstructed images. Results. The contrast-details curves are represented in Fig 1 for all systems. The AGD and SDNR at 45 mm PMMA, the MTF0:5 in tubetravel and chest wall-nipple directions, the ASF, the SSP and CNRLC are shown in Table 1. Conclusions. Our results are in good agreement with recent literature reported [2,3]. It is not simple to compare DBT systems because there are many differences in terms of detection process (direct/indirect), scan angular range, reconstruction algorithms and the presence or not of the grid. The analysis of all collected data can be useful in a contest of a quality assurance program to define a set of values that could be used as benchmarks. References 1. Sarno A, Dedicated breast computed tomography: basic aspects. Med. Phys. (2015) 42(6), 2786-2804. 2. Rodrı`guez-Ruiz A, Evaluation of the technical performance of three different commercial digital breast tomosynthesis systems in the clinical environment. Phys. Medica (2016) 32(6), 767-777. 3. Maldera, A, Digital breast tomosynthesis: Dose and image quality assessment. Phys. Medica (2017) 33(1), 56-67. https://doi.org/10.1016/j.ejmp.2018.04.085
b
Purpose. DBT is a three-dimensional reconstruction technique of mammographic images that potentially offers the possibility to overcame the breast tissue-superposition reducing false-positive recalls
76. Comparison between synthetic and digital mammography in different breast tomosynthesis systems M. Bertolini a, P. Baldelli b, A. Contillo c, G. Della Gala d, P. Golinelli e, L. Pagan f, S. Rivetti d, A. Nitrosi a, A. Taibi c a
AUSL-IRCSS, Reggio Emilia, Italy Breastcheck, National Cancer Screening Service, Dublin, Ireland c Università degli Studi di Ferrara, Dipartimento di Fisica e Scienze della Terra, Ferrara, Italy d Ospedale di Sassuolo SpA, Fisica Medica, Sassuolo, Italy e AUSL Modena, Servizio Fisica Medica, Modena, Italy f AUSL Bologna, U.O. Fisica Sanitaria, Bologna, Italy b
Purpose. Purpose of this work is to compare image quality of Synthetic Mammography (SM) and Full Field Digital Mammography (FFDM) in four different Digital Breast Tomosynthesis (DBT) systems by using a semi-anthropomorphic phantom. Methods. Four DBT systems (FujiFilm, GE, Hologic, IMS) were characterized by means of the semi-anthropomorphic CIRS-BR3D
DBT System
AGD* (mGy)
SDNR⁄
MTF0:5 (mm1 Þ Chest-wall nipple dir
MTF0:5 (mm1 Þ Tube-travel dir
ASF FWHM (mm)
SSP FWHM (mm)
CNRLC
Hologic Tomo Fujifilm ST Fujifilm HR GE SenoClaire GE Pristina
1.14 1.18 2.28 1.40 1.22
4.13 4.66 3.20 4.69 3.76
3.03 1.49 2.40 3.39 4.15
2.96 1.06 1.31 1.62 1.66
6.10 9.14 3.66 3.14 2.96
3.50/3.50 5.00/5.25 2.00/2.25 2.25/2.25 3.00/2.25
3.34 2.44 2.96 2.76 2.83
*At 45mm PMMA.
110
Abstracts / Physica Medica 56 (2018) 59–132
phantom. The phantom contains clusters of microcalcifications, fibers and masses embedded in a breast equivalent tissue having a heterogeneous background. For each DBT system two images (DBT and FFDM) were acquired applying clinical setup conditions. FFDM acquisitions were repeated in manual mode for each system with a fixed exposure ratio between DBT and FFDM. Comparative analyses were carried out on the contrasts and sizes of micro calcifications, on the contrasts and shapes of masses, and on the noise power spectrum of the background. The FFDM image acquired in clinical setup conditions was considered the gold standard of the metric. Results. Considering the micro calcifications, contrasts were generally preserved by SM with respect to FFDM, while the sizes of the smaller details slightly increased, probably due to the blurring caused by the filtration stages of the tomographic reconstruction. Regarding the masses, no globally significant differences were noticeable in the contrasts, and the shapes were generally well preserved as well. Finally, concerning the noise power spectra, significant variations only appeared in the high frequency regime, in accordance with the above-mentioned blurring. Conclusions. This preliminary analysis confirms for all systems the criticality of the synthetic image in terms of spatial resolution and noise but does not highlight significant differences in the detection capability of the details of interest. Further investigations will be made considering the DBT + SM combination compared to DBT + FFDM, as well as by extending the present analysis to other mammographic phantoms. https://doi.org/10.1016/j.ejmp.2018.04.086
77. Normalized glandular dose coefficients in mammography, digital breast tomosynthesis and breast dedicated CT A. Sarno a,b, G. Mettivier a,b, F. Di Lillo a,b, R.M. Tucciariello a, K. Bliznakova c, P. Russo a,b a
Università degli Studi di Napoli ‘‘Federico II”, Dipartimento di Fisica ‘‘E. Pancini” Napoli I-80126, Italy b INFN, Napoli I-80126, Italy c Technical University of Varna, Varna, Bulgaria Purpose. To compute, via GEANT4 based Monte Carlo (MC) simulations, normalized glandular dose (DgN) coefficients for mean glandular dose (MGD) estimates in 2D and 3D X-ray breast imaging. Methods. We developed a Monte Carlo code for DgN calculation (MGD/air kerma, mGy/mGy) in mammography, digital breast tomosynthesis (DBT) and breast CT. The code is based on GEANT4 toolkit ver. 10.00 with the low-energy physics list Option4, and it was validated vs. data from the AAPM-TG195 report and vs. measurements. The geometry of the available scanners were replicated and the breast was modelled as a cylinder with a semi-circular cross section (in mammography and DBT), and as a pendant cylinder in breast CT. The skin thickness was 1.45 mm. The MC simulations were run for monoenergetic beams in the energy range usually adopted in clinic and research. The monoenergetic DgN curves were fitted with 8th-order polynomial curves, and then the polyenergetic DgN coefficients were calculated. Results. We obtained a full set of monoenergetic DgN coefficients for mammography, DBT and breast CT. The monoenergetic DgN fitting curves showed a fitting R2 higher than 0.9998. The polyenergetic DgN coefficients were computed for a large cohort of spectra used in the routine clinical practice. The data were comparable with those present in literature.
Conclusions. A validated MC code for DgN estimates in 2D and 3D X-ray breast imaging has been presented. A breast model has been defined. Monoenergetic and polyenergetic DgN coefficients have been computed. A complete dataset containing monoenergetic DgN curve fit coefficients and polyenergetic DgN coefficients have been released. DgN differed, on average, 6% and 13%, in mammography and breast CT, respectively, from literature data in Refs. [1,2].
References 1. Nosratieh A et al.. Phys Med Biol 2015;60:7179–90. 2. Sechopoulos I et al.. Med Phys 2010;37:4110–20. https://doi.org/10.1016/j.ejmp.2018.04.087
78. Image quality metrics analysis to assess the reliability of injected activity reduction for 18F-FDG PET/MRI pediatric oncology examinations F. De Monte a, A. Zorz a, M. Branchini a, P. Zucchetta b, V. Bodanza b, F. Bui b, M. Paiusco a a
Veneto Institute of Oncology IOV – IRCCS, Medical Physics Department, Padua, Italy b Azienda Ospedaliera di Padova, Nuclear Medicine Department, Padua, Italy Purpose. the aim of this study was to evaluate the stability of image quality (IQ) metrics in pediatric 18F-FDG PET/MR acquisitions while decreasing statistical counts, mimicking an injected activity reduction. Methods. 21 18F-FDG PET/MR whole body acquisitions performed on an hybrid scanner (Biograph mMR, Siemens Healthcare) were retrospectively reconstructed with the e7-tools package. The full tracer activity (FTA) list-mode data (3 MBq/kg, 5 min/bed position) were truncated at 4, 3, 2.5, 2 and 1 min, simulating lower tracer activity (LTA) images corresponding to 2.4, 1.8, 1.5, 1.2 and 0.6 MBq/kg. Subjective IQ (score 1 to 5) and number of detectable lesions were assessed by two expert nuclear medicine physicians. SUV metrics (SUVmean, SUVmax and SUVpeak) and semi-quantitative parameters as contrast-to-noise ratio (CNR), normalized noise in liver (NN), metabolic tumor volume (MTV) and total lesion glycolysis (TLG) were evaluated on each image. Results. Results of subjective IQ evaluations are reported in figure 1; the assigned score decreased when reducing tracer activity, but remained acceptable till 1.5 MBq/kg. All the total 56 lesions were detected until 1.2 MBq/kg activity level, whereas 5 lesions were missed on the 0.6 MBq/kg image. Results of quantitative analysis are collected in table 1, espressed as a ratio of LTA and FTA values. Semi-quantitative parameters (except SUVpeak) and IQ metrics showed limited variation respect to the FTA image until 1.5 MBq/ kg image. Differences were not statistically significant in LTA images down to 1.5 MBq/kg with pairwise paired Wilcoxon and t-tests. SUVpeak is the parameter less affected by dose reduction (average difference for all LTA images inferior than 2%). NN showed a constant increase while decreasing statistical counts. Conclusions. An injected activity reduction up to 50% (1.5 MBq/kg) guarantees a stability in semi-quantitative parameters representing lesion detectability and tumor burden information.
Images were acquired in automatic mode. MGDs were measured in accordance with the Mammo Protocol of the European Federation of Organisations for Medical Physics (EFOMP) [1]. Where available, Organ Doses (ODGs), calculated by manufacturers, were collected from the Header DICOM of the corresponding images and the differences with respect MGDs were evaluated. Results. All the MGDs values are within the EFOMP Mammo Protocol limits. Differences from MGDs and ODGs values are in between ±20% for the majority of systems, except for few ones. For 20 mm, 45 mm and 60 mm phantom thickness, the ranges of MGDs extend from 0.37 mGy to 1.00 mGy, 0.65 mGy to 2.40 mGy and from 1.33 mGy to 4.19 mGy respectively. As expected, MGDs show a strong dependence on FFDM system technology: the Photon Counting system has the lowest MGDs values, while the CR systems exhibit the highest ones. Conclusions. Our results confirm the importance of monitoring periodically the level of technology employed in a regional screening program by means of a dose survey, in order to promote a renewal of the FFDM imaging systems in accordance with the image quality preferences of the radiologists involved. This survey procedure would be functional also to guarantee the homogeneity of the Risk-Benefit Ratio. Reference 1. Gennaro G et al., EFOMP Mammo Working Group Protocol, March 2015. https://doi.org/10.1016/j.ejmp.2018.04.084
75. Image quality and dose measurements in digital breast tomosynthesis O. Ortenzia a, R. Rossi a, M. Bertolini b, A. Nitrosi b, C. Ghetti a a
Department of Medical Physics, University Hospital of Parma, Italy Department of Medical Physics, Santa Maria Nuova Hospital of Reggio Emilia, Italy
109
and increasing cancer detection-rate compared to 2D mammography [1]. The aim of this study is to compare different commercial DBT units in terms of image quality and dose using a set of new phantoms. Methods. The CDMAM phantom was used to compare the Contrast-Details curves in 2D and DBT mode principally for stability assessment. The TomophanTM phantom was used to perform measurements of Slice Sensitive Profile, slice-to-slice incrementation, chest-wall offset, z-axis geometry, Artefact Spread Function, low contrast detectability. An aluminium edge was employed to determine in plane MTF. The Pixmam phantom was used to estimate the AGD and to calculate SDNR. All measurements were performed on reconstructed images. Results. The contrast-details curves are represented in Fig 1 for all systems. The AGD and SDNR at 45 mm PMMA, the MTF0:5 in tubetravel and chest wall-nipple directions, the ASF, the SSP and CNRLC are shown in Table 1. Conclusions. Our results are in good agreement with recent literature reported [2,3]. It is not simple to compare DBT systems because there are many differences in terms of detection process (direct/indirect), scan angular range, reconstruction algorithms and the presence or not of the grid. The analysis of all collected data can be useful in a contest of a quality assurance program to define a set of values that could be used as benchmarks. References 1. Sarno A, Dedicated breast computed tomography: basic aspects. Med. Phys. (2015) 42(6), 2786-2804. 2. Rodrı`guez-Ruiz A, Evaluation of the technical performance of three different commercial digital breast tomosynthesis systems in the clinical environment. Phys. Medica (2016) 32(6), 767-777. 3. Maldera, A, Digital breast tomosynthesis: Dose and image quality assessment. Phys. Medica (2017) 33(1), 56-67. https://doi.org/10.1016/j.ejmp.2018.04.085
b
Purpose. DBT is a three-dimensional reconstruction technique of mammographic images that potentially offers the possibility to overcame the breast tissue-superposition reducing false-positive recalls
76. Comparison between synthetic and digital mammography in different breast tomosynthesis systems M. Bertolini a, P. Baldelli b, A. Contillo c, G. Della Gala d, P. Golinelli e, L. Pagan f, S. Rivetti d, A. Nitrosi a, A. Taibi c a
AUSL-IRCSS, Reggio Emilia, Italy Breastcheck, National Cancer Screening Service, Dublin, Ireland c Università degli Studi di Ferrara, Dipartimento di Fisica e Scienze della Terra, Ferrara, Italy d Ospedale di Sassuolo SpA, Fisica Medica, Sassuolo, Italy e AUSL Modena, Servizio Fisica Medica, Modena, Italy f AUSL Bologna, U.O. Fisica Sanitaria, Bologna, Italy b
Purpose. Purpose of this work is to compare image quality of Synthetic Mammography (SM) and Full Field Digital Mammography (FFDM) in four different Digital Breast Tomosynthesis (DBT) systems by using a semi-anthropomorphic phantom. Methods. Four DBT systems (FujiFilm, GE, Hologic, IMS) were characterized by means of the semi-anthropomorphic CIRS-BR3D
DBT System
AGD* (mGy)
SDNR⁄
MTF0:5 (mm1 Þ Chest-wall nipple dir
MTF0:5 (mm1 Þ Tube-travel dir
ASF FWHM (mm)
SSP FWHM (mm)
CNRLC
Hologic Tomo Fujifilm ST Fujifilm HR GE SenoClaire GE Pristina
1.14 1.18 2.28 1.40 1.22
4.13 4.66 3.20 4.69 3.76
3.03 1.49 2.40 3.39 4.15
2.96 1.06 1.31 1.62 1.66
6.10 9.14 3.66 3.14 2.96
3.50/3.50 5.00/5.25 2.00/2.25 2.25/2.25 3.00/2.25
3.34 2.44 2.96 2.76 2.83
*At 45mm PMMA.
110
Abstracts / Physica Medica 56 (2018) 59–132
phantom. The phantom contains clusters of microcalcifications, fibers and masses embedded in a breast equivalent tissue having a heterogeneous background. For each DBT system two images (DBT and FFDM) were acquired applying clinical setup conditions. FFDM acquisitions were repeated in manual mode for each system with a fixed exposure ratio between DBT and FFDM. Comparative analyses were carried out on the contrasts and sizes of micro calcifications, on the contrasts and shapes of masses, and on the noise power spectrum of the background. The FFDM image acquired in clinical setup conditions was considered the gold standard of the metric. Results. Considering the micro calcifications, contrasts were generally preserved by SM with respect to FFDM, while the sizes of the smaller details slightly increased, probably due to the blurring caused by the filtration stages of the tomographic reconstruction. Regarding the masses, no globally significant differences were noticeable in the contrasts, and the shapes were generally well preserved as well. Finally, concerning the noise power spectra, significant variations only appeared in the high frequency regime, in accordance with the above-mentioned blurring. Conclusions. This preliminary analysis confirms for all systems the criticality of the synthetic image in terms of spatial resolution and noise but does not highlight significant differences in the detection capability of the details of interest. Further investigations will be made considering the DBT + SM combination compared to DBT + FFDM, as well as by extending the present analysis to other mammographic phantoms. https://doi.org/10.1016/j.ejmp.2018.04.086
77. Normalized glandular dose coefficients in mammography, digital breast tomosynthesis and breast dedicated CT A. Sarno a,b, G. Mettivier a,b, F. Di Lillo a,b, R.M. Tucciariello a, K. Bliznakova c, P. Russo a,b a
Università degli Studi di Napoli ‘‘Federico II”, Dipartimento di Fisica ‘‘E. Pancini” Napoli I-80126, Italy b INFN, Napoli I-80126, Italy c Technical University of Varna, Varna, Bulgaria Purpose. To compute, via GEANT4 based Monte Carlo (MC) simulations, normalized glandular dose (DgN) coefficients for mean glandular dose (MGD) estimates in 2D and 3D X-ray breast imaging. Methods. We developed a Monte Carlo code for DgN calculation (MGD/air kerma, mGy/mGy) in mammography, digital breast tomosynthesis (DBT) and breast CT. The code is based on GEANT4 toolkit ver. 10.00 with the low-energy physics list Option4, and it was validated vs. data from the AAPM-TG195 report and vs. measurements. The geometry of the available scanners were replicated and the breast was modelled as a cylinder with a semi-circular cross section (in mammography and DBT), and as a pendant cylinder in breast CT. The skin thickness was 1.45 mm. The MC simulations were run for monoenergetic beams in the energy range usually adopted in clinic and research. The monoenergetic DgN curves were fitted with 8th-order polynomial curves, and then the polyenergetic DgN coefficients were calculated. Results. We obtained a full set of monoenergetic DgN coefficients for mammography, DBT and breast CT. The monoenergetic DgN fitting curves showed a fitting R2 higher than 0.9998. The polyenergetic DgN coefficients were computed for a large cohort of spectra used in the routine clinical practice. The data were comparable with those present in literature.
Conclusions. A validated MC code for DgN estimates in 2D and 3D X-ray breast imaging has been presented. A breast model has been defined. Monoenergetic and polyenergetic DgN coefficients have been computed. A complete dataset containing monoenergetic DgN curve fit coefficients and polyenergetic DgN coefficients have been released. DgN differed, on average, 6% and 13%, in mammography and breast CT, respectively, from literature data in Refs. [1,2].
References 1. Nosratieh A et al.. Phys Med Biol 2015;60:7179–90. 2. Sechopoulos I et al.. Med Phys 2010;37:4110–20. https://doi.org/10.1016/j.ejmp.2018.04.087
78. Image quality metrics analysis to assess the reliability of injected activity reduction for 18F-FDG PET/MRI pediatric oncology examinations F. De Monte a, A. Zorz a, M. Branchini a, P. Zucchetta b, V. Bodanza b, F. Bui b, M. Paiusco a a
Veneto Institute of Oncology IOV – IRCCS, Medical Physics Department, Padua, Italy b Azienda Ospedaliera di Padova, Nuclear Medicine Department, Padua, Italy Purpose. the aim of this study was to evaluate the stability of image quality (IQ) metrics in pediatric 18F-FDG PET/MR acquisitions while decreasing statistical counts, mimicking an injected activity reduction. Methods. 21 18F-FDG PET/MR whole body acquisitions performed on an hybrid scanner (Biograph mMR, Siemens Healthcare) were retrospectively reconstructed with the e7-tools package. The full tracer activity (FTA) list-mode data (3 MBq/kg, 5 min/bed position) were truncated at 4, 3, 2.5, 2 and 1 min, simulating lower tracer activity (LTA) images corresponding to 2.4, 1.8, 1.5, 1.2 and 0.6 MBq/kg. Subjective IQ (score 1 to 5) and number of detectable lesions were assessed by two expert nuclear medicine physicians. SUV metrics (SUVmean, SUVmax and SUVpeak) and semi-quantitative parameters as contrast-to-noise ratio (CNR), normalized noise in liver (NN), metabolic tumor volume (MTV) and total lesion glycolysis (TLG) were evaluated on each image. Results. Results of subjective IQ evaluations are reported in figure 1; the assigned score decreased when reducing tracer activity, but remained acceptable till 1.5 MBq/kg. All the total 56 lesions were detected until 1.2 MBq/kg activity level, whereas 5 lesions were missed on the 0.6 MBq/kg image. Results of quantitative analysis are collected in table 1, espressed as a ratio of LTA and FTA values. Semi-quantitative parameters (except SUVpeak) and IQ metrics showed limited variation respect to the FTA image until 1.5 MBq/ kg image. Differences were not statistically significant in LTA images down to 1.5 MBq/kg with pairwise paired Wilcoxon and t-tests. SUVpeak is the parameter less affected by dose reduction (average difference for all LTA images inferior than 2%). NN showed a constant increase while decreasing statistical counts. Conclusions. An injected activity reduction up to 50% (1.5 MBq/kg) guarantees a stability in semi-quantitative parameters representing lesion detectability and tumor burden information.