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Retrospective dose evaluation in adults undergoing recurring CT examinations: Last five years experience in our institution
Abstracts/Physica Medica 32 (2016) e71–e96
for this reason TAVI dosimetric data are very rare and we have verified that our results are near the same of those presented in a recent publication (Catheterization and Cardiovascular Intervention, 2015, 85, 1256–1261). Conclusions: Automated methods of radiation dose data collection permit a detailed analysis of a great amount of data and an easy determination of local dose reference levels for interventional cardiology procedures. We have verified that our data are dosimetrically correct and that we have never exceeded the DAP threshold limit of 500 Gycm^2. http://dx.doi.org/10.1016/j.ejmp.2016.01.269 B.265 HOW TO DEFINE LOCAL DIAGNOSTIC REFERENCE LEVELS FOR CT, MG AND XA USING A DOSE TRACKING SOFTWARE C. Ghetti *,a, S. Filice a, O. Ortenzia a, F. Palleri a, M. Sireus b, G. Crisi c. a Department of Medical Physics, University Hospital of Parma, Parma, Italy; b University of Cagliari, Cagliari, Italy; c Department of Neuroradiology, University Hospital of Parma, Parma, Italy Introduction: Dose optimization in high dose radiological examinations is a mandatory issue: in this study local Diagnostic Reference Levels (lDRLs) for the most frequent procedures performed in our Radiology Department were established using a radiation dose tracking system in order to have an optimization tool and to face the requests of the new Euratom directive 2013/59. Materials and Method: Radiation dose data (CTDI, DLP, AGD, fluoro time, DAP) collection was realized using a dose tracking software (Radimetrics, Bayer) connected to 5 CT scanners, 2 clinical mammographic units and 5 angiographic systems. From the beginning of 2015 we have analyzed 27,700 CT acquisitions, 4600 mammographic radiograms, 2100 interventional procedures (cardiac, neuro and body). We have defined our lDRLS and we have compared our data with Dlgs 187/ 00 and with the recent literature. Results: For head, sinuses, dental, chest, cardiac, spine, chest-abdomen and CAP CT scans we have defined the 75thpercentiles of CTDIvol and DLPtot. We have established our lDRLS for CA, PTCA, CA+PTCA,TAVI, arteriography, vertebroplasty, IVC angiography, PTC+PTBD, PTA and varicocele in term of fluoro time, fluoro DAP and total DAP. We have evaluated the AGD mean and the 75th percentile for each mammographic radiogram, for the whole examination and for the magnification images. We have verified that most of our data are dosimetrically correct and we have focused which are the procedures that need an optimization. Conclusions: Automated methods of radiation dose data collection allow a fast and detailed analysis of a great amount of data and an easy determination of lDRLs for different radiological procedures. Alert, productivity and benchmarking tools, available in Radimetrics, enable to control in real time the dosimetric trend of our radiological examinations and to perform the necessary corrective actions. http://dx.doi.org/10.1016/j.ejmp.2016.01.270 B.266 EVALUATION OF THE VOLUMETRIC DOSE IN DIGITAL BREAST TOMOSYNTHESIS G. Asero a, P. Barone a, C. Greco *,b,c, A. Gueli a,c, L. Raffaele b,c, S. Spampinato a,c. a PH3DRA Laboratories, Dipartimento di Fisica e Astronomia, Università di Catania&INFN, Sez. CT, Catania, Italy; b Azienda Ospedaliero, Universitaria Policlinico Vittorio Emanuele, Catania, Italy; c Scuola di Specializzazione in Fisica Medica, Scuola Facoltà di Medicina, Università di Catania, Catania, Italy Introduction: Digital Breast Tomosynthesis (DBT) is often used in clinical exams to integrate the information obtained with conventional mammography and to investigate the breast thickness at different depths through image projections. The aim of this work is to analyse the dose distribution along the three dimensions, within a phantom that simulates the breast. Materials and Methods: To perform dose measurements, Gafchromic® XRQA2 films were used. To obtain a calibration curve that links absorbed dose with Pixel Value, different pieces of film (3 × 3 cm2) were irradiated with increasing known doses and digitised with a commercial flatbed scanner
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using a standard protocol for film dosimetry (72 dpi, 48 bit colour depth). To obtain the two- and three-dimensional dosimetric information, a homemade phantom, assembled with10 × 10 cm2 slices of 5 mm solid water (ten slices) and eleven slices of XR-QA2 films was used. Dose maps as a function of depth were obtained from DBT exposures in AEC modality. The films were digitised with the scanner (150 dpi, 48 bit colour depth), Image J and Origin software were used, respectively, for red channel data extraction and dose values analysis. Results: After the image acquisition, a ROI was selected in central position in order to obtain the dose values useful to Percentage Depth Dose (PDD) reconstruction. A (16,04 ± 0,80) mGy surface dose, considered in the reference area (6 cm from chest wall), was obtained while at the maximum depth a dose of (0,96 ± 0,05) mGy was evaluated. Furthermore, the 2D map of each sheet results within 10%. An increment of the dose values is imputable to the Hall effect that amplifies the energy absorption in the chest wall. Conclusions: The dosimetry performed by XR-QA2 Gafchromic® films showed that the 2D and 3D distributions during a mammography exam in DBT modality are uniform along the direction of the support plane of the breast. The PDD behaviour shows a dose decrement with respect to depth. http://dx.doi.org/10.1016/j.ejmp.2016.01.271
B.267 RETROSPECTIVE DOSE EVALUATION IN ADULTS UNDERGOING RECURRING CT EXAMINATIONS: LAST FIVE YEARS EXPERIENCE IN OUR INSTITUTION S. Grisotto *,a, E. Mazzarella a, M. Borroni a, R. Gallo b, F.G. Greco b, E. Pignoli a, A. Marchianò b. a Fisica Medica, Fondazione IRCCS Istituto Nazionale dei Tumori, Milano, Italy; b Radiologia, Fondazione IRCCS Istituto Nazionale dei Tumori, Milano, Italy Introduction: A retrospective study of dosimetric data of most frequently performed adult CT examinations has been implemented to determine the impact of new available technologies in dose reduction. Materials and Methods: Dosimetric data of CT scans of adult patients repeating the same diagnostic examination in the last five years have been compared to each other. Head, chest and chest-abdomen examinations performed on Siemens Somatom Sensation CT scanner until November 2011 and on Siemens Definition Flash CT scanner (replacing the previous one) have been considered. For both CT scanners exams have been performed using tube current modulation system Care Dose 4D (except in the case of head examinations for which it has been introduced in spring 2014). Sinogram-Affirmed Iterative Reconstruction (SAFIRE) has also been implemented on the newer CT device. Reference and effective mAs, mean CTDIvol and DLP provided by the scanners have been recorded for each exam verifying patient size constancy over time. Size specific dose estimate (SSDE) corrected for water equivalent diameter (WED) has been calculated from AP and LL patient dimensions measured from images. Image quality has been evaluated by means of HU standard deviation in ROIs drawn in the same uniform regions of the image. About 30 patients have been analyzed for each type of examination. Results: For head examinations the use of Care Dose 4D and SAFIRE has enabled a mean dose reduction of about 17% at constant image quality. For chest examinations it has been possible to reduce both dose and noise by about 30%. For chest-abdomen examinations only a slight dose reduction has been shown because aggressive dose reduction could compromise lesion detectability. Conclusions: The introduction of tube current modulation and iterative reconstruction has generally proved to be very effective at reducing dose, most of all to patients undergoing frequent CT examinations over time. http://dx.doi.org/10.1016/j.ejmp.2016.01.272
B.268 PROJECT OF AN AUTOMATIC SYSTEM FOR TRADITIONAL RADIOLOGY EQUIPMENTS AND IMAGE DETECTORS QUALITY CONTROLS S. Grisotto * ,a , E. Mazzarella a , M. Borroni a , F.G. Greco b , E. Pignoli a , A. Marchianò b. a Fisica Medica, Fondazione IRCCS Istituto Nazionale dei Tumori, Milano, Italy; b Radiologia, Fondazione IRCCS Istituto Nazionale dei Tumori, Milano, Italy
for this reason TAVI dosimetric data are very rare and we have verified that our results are near the same of those presented in a recent publication (Catheterization and Cardiovascular Intervention, 2015, 85, 1256–1261). Conclusions: Automated methods of radiation dose data collection permit a detailed analysis of a great amount of data and an easy determination of local dose reference levels for interventional cardiology procedures. We have verified that our data are dosimetrically correct and that we have never exceeded the DAP threshold limit of 500 Gycm^2. http://dx.doi.org/10.1016/j.ejmp.2016.01.269 B.265 HOW TO DEFINE LOCAL DIAGNOSTIC REFERENCE LEVELS FOR CT, MG AND XA USING A DOSE TRACKING SOFTWARE C. Ghetti *,a, S. Filice a, O. Ortenzia a, F. Palleri a, M. Sireus b, G. Crisi c. a Department of Medical Physics, University Hospital of Parma, Parma, Italy; b University of Cagliari, Cagliari, Italy; c Department of Neuroradiology, University Hospital of Parma, Parma, Italy Introduction: Dose optimization in high dose radiological examinations is a mandatory issue: in this study local Diagnostic Reference Levels (lDRLs) for the most frequent procedures performed in our Radiology Department were established using a radiation dose tracking system in order to have an optimization tool and to face the requests of the new Euratom directive 2013/59. Materials and Method: Radiation dose data (CTDI, DLP, AGD, fluoro time, DAP) collection was realized using a dose tracking software (Radimetrics, Bayer) connected to 5 CT scanners, 2 clinical mammographic units and 5 angiographic systems. From the beginning of 2015 we have analyzed 27,700 CT acquisitions, 4600 mammographic radiograms, 2100 interventional procedures (cardiac, neuro and body). We have defined our lDRLS and we have compared our data with Dlgs 187/ 00 and with the recent literature. Results: For head, sinuses, dental, chest, cardiac, spine, chest-abdomen and CAP CT scans we have defined the 75thpercentiles of CTDIvol and DLPtot. We have established our lDRLS for CA, PTCA, CA+PTCA,TAVI, arteriography, vertebroplasty, IVC angiography, PTC+PTBD, PTA and varicocele in term of fluoro time, fluoro DAP and total DAP. We have evaluated the AGD mean and the 75th percentile for each mammographic radiogram, for the whole examination and for the magnification images. We have verified that most of our data are dosimetrically correct and we have focused which are the procedures that need an optimization. Conclusions: Automated methods of radiation dose data collection allow a fast and detailed analysis of a great amount of data and an easy determination of lDRLs for different radiological procedures. Alert, productivity and benchmarking tools, available in Radimetrics, enable to control in real time the dosimetric trend of our radiological examinations and to perform the necessary corrective actions. http://dx.doi.org/10.1016/j.ejmp.2016.01.270 B.266 EVALUATION OF THE VOLUMETRIC DOSE IN DIGITAL BREAST TOMOSYNTHESIS G. Asero a, P. Barone a, C. Greco *,b,c, A. Gueli a,c, L. Raffaele b,c, S. Spampinato a,c. a PH3DRA Laboratories, Dipartimento di Fisica e Astronomia, Università di Catania&INFN, Sez. CT, Catania, Italy; b Azienda Ospedaliero, Universitaria Policlinico Vittorio Emanuele, Catania, Italy; c Scuola di Specializzazione in Fisica Medica, Scuola Facoltà di Medicina, Università di Catania, Catania, Italy Introduction: Digital Breast Tomosynthesis (DBT) is often used in clinical exams to integrate the information obtained with conventional mammography and to investigate the breast thickness at different depths through image projections. The aim of this work is to analyse the dose distribution along the three dimensions, within a phantom that simulates the breast. Materials and Methods: To perform dose measurements, Gafchromic® XRQA2 films were used. To obtain a calibration curve that links absorbed dose with Pixel Value, different pieces of film (3 × 3 cm2) were irradiated with increasing known doses and digitised with a commercial flatbed scanner
e79
using a standard protocol for film dosimetry (72 dpi, 48 bit colour depth). To obtain the two- and three-dimensional dosimetric information, a homemade phantom, assembled with10 × 10 cm2 slices of 5 mm solid water (ten slices) and eleven slices of XR-QA2 films was used. Dose maps as a function of depth were obtained from DBT exposures in AEC modality. The films were digitised with the scanner (150 dpi, 48 bit colour depth), Image J and Origin software were used, respectively, for red channel data extraction and dose values analysis. Results: After the image acquisition, a ROI was selected in central position in order to obtain the dose values useful to Percentage Depth Dose (PDD) reconstruction. A (16,04 ± 0,80) mGy surface dose, considered in the reference area (6 cm from chest wall), was obtained while at the maximum depth a dose of (0,96 ± 0,05) mGy was evaluated. Furthermore, the 2D map of each sheet results within 10%. An increment of the dose values is imputable to the Hall effect that amplifies the energy absorption in the chest wall. Conclusions: The dosimetry performed by XR-QA2 Gafchromic® films showed that the 2D and 3D distributions during a mammography exam in DBT modality are uniform along the direction of the support plane of the breast. The PDD behaviour shows a dose decrement with respect to depth. http://dx.doi.org/10.1016/j.ejmp.2016.01.271
B.267 RETROSPECTIVE DOSE EVALUATION IN ADULTS UNDERGOING RECURRING CT EXAMINATIONS: LAST FIVE YEARS EXPERIENCE IN OUR INSTITUTION S. Grisotto *,a, E. Mazzarella a, M. Borroni a, R. Gallo b, F.G. Greco b, E. Pignoli a, A. Marchianò b. a Fisica Medica, Fondazione IRCCS Istituto Nazionale dei Tumori, Milano, Italy; b Radiologia, Fondazione IRCCS Istituto Nazionale dei Tumori, Milano, Italy Introduction: A retrospective study of dosimetric data of most frequently performed adult CT examinations has been implemented to determine the impact of new available technologies in dose reduction. Materials and Methods: Dosimetric data of CT scans of adult patients repeating the same diagnostic examination in the last five years have been compared to each other. Head, chest and chest-abdomen examinations performed on Siemens Somatom Sensation CT scanner until November 2011 and on Siemens Definition Flash CT scanner (replacing the previous one) have been considered. For both CT scanners exams have been performed using tube current modulation system Care Dose 4D (except in the case of head examinations for which it has been introduced in spring 2014). Sinogram-Affirmed Iterative Reconstruction (SAFIRE) has also been implemented on the newer CT device. Reference and effective mAs, mean CTDIvol and DLP provided by the scanners have been recorded for each exam verifying patient size constancy over time. Size specific dose estimate (SSDE) corrected for water equivalent diameter (WED) has been calculated from AP and LL patient dimensions measured from images. Image quality has been evaluated by means of HU standard deviation in ROIs drawn in the same uniform regions of the image. About 30 patients have been analyzed for each type of examination. Results: For head examinations the use of Care Dose 4D and SAFIRE has enabled a mean dose reduction of about 17% at constant image quality. For chest examinations it has been possible to reduce both dose and noise by about 30%. For chest-abdomen examinations only a slight dose reduction has been shown because aggressive dose reduction could compromise lesion detectability. Conclusions: The introduction of tube current modulation and iterative reconstruction has generally proved to be very effective at reducing dose, most of all to patients undergoing frequent CT examinations over time. http://dx.doi.org/10.1016/j.ejmp.2016.01.272
B.268 PROJECT OF AN AUTOMATIC SYSTEM FOR TRADITIONAL RADIOLOGY EQUIPMENTS AND IMAGE DETECTORS QUALITY CONTROLS S. Grisotto * ,a , E. Mazzarella a , M. Borroni a , F.G. Greco b , E. Pignoli a , A. Marchianò b. a Fisica Medica, Fondazione IRCCS Istituto Nazionale dei Tumori, Milano, Italy; b Radiologia, Fondazione IRCCS Istituto Nazionale dei Tumori, Milano, Italy