We investigated the performances of two computed tomography (CT) systems produced by the same manufacturers (Somatom Flash and Edge Siemens) with different detector technologies (Ultrafast Ceramic and Stellar) and different generation of iterative reconstruction (IR) algorithms (SAFIRE and ADMIRE). A homemade phantom was scanned and the images were reconstructed with filtered back-projection (FBP) and IR algorithms. In terms of image quality, the performances of the systems were checked using the low-contrast detectability, evaluated by a Channelized Hotelling Observer (CHO), and the noise power spectrum (NPS). The analysis with CHO showed the best performance of Edge respect to Flash system for both FBP and IR algorithms. This better behavior, which reaches 20%, has been ascribed to the Stellar detector. From the NPS analysis, the noise reduction due to Stellar detector was 57%, moreover ADMIRE algorithm preserves a more traditional CT image texture appearance versus SAFIRE due to a lower NPS peak shift.

The goal of this paper was the comparison of radiation dose and imaging quality before and after the Clarity IQ technology installation in a Philips AlluraXper FD20/20 angiography system using a Channelized Hotelling Observer model (CHO). The core characteristics of the Allura Clarity IQ technology are its real-time noise reduction algorithms (NRT) combined with state-of-the-art hardware; this technology allows to implement acquisition protocols able to significantly reduce patient entrance dose. To measure the system performances in terms of image quality we used a contrast detail phantom in a clinical scatter condition. A Leeds TO10 phantom has been imaged between two 10 cm thick homogeneous solid water slabs. Fluoroscopy images were acquired using a cerebral protocol at 3 dose levels (low, medium and high) with a field- of view (FOV) of 31 cm. Cineangiography images were acquired using a cerebral protocol at 2 fps. Thus, 4 acquisitions were obtained for the conventional technology and 4 acquisitions were taken after the Clarity IQ upgrade, for a total of 8 different image sets. A validated 40 Gabor channels CHO with an internal noise model compared the image sets. Human observers' studies were carried out to tune the internal noise parameter. We showed that the CHO did not detect any significant difference between any of the image sets acquired using the two technologies. Consequently, this x-ray imaging technology provides a non-inferior image quality with an average patient dose reduction of 57% and 28% respectively in cineangiography and fluoroscopy. The Clarity IQ installation has certainly allowed a considerable improvement in patient and staff safety, while maintaining the same image quality.

Purpose: The aim of this work was to evaluate the dosimetric impact of high-resolution thorax CT during COVID19 outbreak in the University Hospital of Parma. In two months we have performed a huge number of thorax CT scans collecting effective and equivalent organ doses and evaluating also the lifetime attributable risk (LAR) of lung and other major cancers. Materials and Method: From February 24th to April 28th, 3224 high-resolution thorax CT were acquired. For all patients we have examined the volumetric computed tomography dose index (CTDIvol), the dose length product (DLP), the size-specific dose estimate (SSDE) and effective dose (E103) using a dose tracking software (Radimetrics Bayer HealthCare). From the equivalent dose to organs for each patient, LAR for lung and major cancers were estimated following the method proposed in BEIR VII which considers age and sex differences. Results: Study population included 3224 patients, 1843 male and 1381 female, with an average age of 67 years. The average CTDIvol, SSDE and DLP, and E103 were 6.8 mGy, 8.7 mGy, 239 mGy.cm and 4.4 mSv respectively. The average LAR of all solid cancers was 2.1 cases per 10,000 patients, while the average LAR of leukemia was 0.2 cases per 10,000 patients. For both male and female the organ with a major cancer risk was lung. Conclusions: Despite the impressive increment in thoracic CT examinations due to COVID-19 outbreak, the high resolution low dose protocol used in our hospital guaranteed low doses and very low risk estimation in terms of LAR.

Purpose The aim of this study was the evaluation of dose indexes for O-arm (Medtronic, USA) [1] volumetric scans used during spinal surgery procedures and a comparison with traditional diagnostic CT scans acquired before and/or after spinal surgery. Methods The O-arm data set consists of 38 patients dose reports who underwent surgical vertebral stabilization (64 lumbar scans, 14 dorsal scans and 5cervical scans). Mean values for delivered mAs, CTDIvol and DLP were calculated for O-arm protocols. CT examinations used as benchmark were acquired on a Siemens Emotion 6 scanner and consist of 18 patients (12 dorsal-lumbar and 6cervical scans). The mean and 75th percentile of CTDI/DLP distributions for lumbar, dorsal and cervical spine procedures were compared with the same dosimetric indexes obtained for CT examinations. Results For O-arm lumbar scans (77% of total ), 7 protocols were used: 120 kV, 275(77–596) mAs, CTDIvol 24.1(6.8–52.3) mGy, DLP 386(109–837) mGycm. For dorsal scans 5 protocols were used: 120 kV, 200(62–469) mAs, CTDIvol 17.6(5.5–41.2) mGy, DLP 281(88–659) mGycm. For cervical scans 2 protocols were used: 120 kV, 68(38–98) mAs, CTDIvol 11(6.1–15.9) mGy, DLP 176(98–254) mGycm. The mean number of scans performed on O-arm for each patient was 2.2. The doses for O-Arm scans were lower than those for traditional CT examinations, with a reduction in lumbar area of −31, −55% for mean and 75th percentile of CTDIvol values and of −43,−59% for DLP; in dorsal area of −40,-59% for CTDIvol and of −50,−62% for DLP; in cervical area of −47,−15% for CTDIvol and −53,-50% for DLP. Conclusions The O-arm system in spine surgery allows accuracy, lower rate of screw misplacement, reduced surgical time, less discomfort for patients and lower dose indexes values than traditional CT scans. These results are preliminary and we plan to increase our statistic.

Purpose We have evaluated, using a software tool for monitoring and tracking radiation dose, the radiation exposures in hybrid myocardial perfusion imaging (MPI) before and after the optimization of the SPECT/CT acquisition protocol. Methods and materials Examination data was collected from a SPECT/CT scanner Siemens Symbia T6 using Radimetrics version 2.6 (Bayer HealthCare, Whippany, NY). Data of MPI performed between 1st March 2016 and 1st March 2017 have been extracted from the DICOM header and Dose Report files produced by the scanner and stored in PACS. All analysis were made for exams in two days (TD) and in single day (SD). CTDIvol, DLP, SSDE, administered activity and Effective Dose were collected. A new optimized acquisition protocol was created changing CT parameters (mAs and pitch) and defining a new administered dose activity card with a reduction of the administered dose of about 18% for TD protocol and of only 4% for SD protocol because it was already well optimised. Examinations performed between 29th May 2017 and 30th November 2017 have been extracted and all dosimetric param eters were compared between old and new protocol. Results The dose reduction for CT part of the MPI was approximately 52% for all the parameters analysed (CTDIvol, DLP, SSDE, Effective Dose) both for TD and SD protocol. The dose reduction for SPECT part was aligned with the reduction introduced in the new administered dose activity card. In MPI study we have achieved, with the new optimized protocol, a total dose reduction of about 30% in TD exams and of about 24% in SD exams (see table below). Conclusion Using a software tool for monitoring and tracking radiation dose was possible to monitor, in real time, radiation exposure in SPECT/CT exams and analyze how to optimize the protocol to reduce effective dose to the patients. We have evaluated, using a software tool for monitoring and tracking radiation dose, the radiation exposures in hybrid myocardial perfusion imaging (MPI) before and after the optimization of the SPECT/CT acquisition protocol. Examination data was collected from a SPECT/CT scanner Siemens Symbia T6 using Radimetrics version 2.6 (Bayer HealthCare, Whippany, NY). Data of MPI performed between 1st March 2016 and 1st March 2017 have been extracted from the DICOM header and Dose Report files produced by the scanner and stored in PACS. All analysis were made for exams in two days (TD) and in single day (SD). CTDIvol, DLP, SSDE, administered activity and Effective Dose were collected. A new optimized acquisition protocol was created changing CT parameters (mAs and pitch) and defining a new administered dose activity card with a reduction of the administered dose of about 18% for TD protocol and of only 4% for SD protocol because it was already well optimised. Examinations performed between 29th May 2017 and 30th November 2017 have been extracted and all dosimetric param eters were compared between old and new protocol. The dose reduction for CT part of the MPI was approximately 52% for all the parameters analysed (CTDIvol, DLP, SSDE, Effective Dose) both for TD and SD protocol. The dose reduction for SPECT part was aligned with the reduction introduced in the new administered dose activity card. In MPI study we have achieved, with the new optimized protocol, a total dose reduction of about 30% in TD exams and of about 24% in SD exams (see table below). Using a software tool for monitoring and tracking radiation dose was possible to monitor, in real time, radiation exposure in SPECT/CT exams and analyze how to optimize the protocol to reduce effective dose to the patients.

Purpose The recent introduction of dose tracking software has the potential to facilitate the collection of data and investigation of unusual high dose examinations. Furthermore, dosimetric data of radiological examination must be recorded and reported in order to face the request of the Euratom Directive 2013/59 [1]. We describe our experience with one of this software (Radimetrics version 2.5b, Bayer HealthCare [2]) that has been implemented to define local DRL for selected radiological examinations in Clinical Mammography and Computed Tomography, commonly considered crucial in terms of dosimetric impact. Methods We have collected Average Glandular Dose (AGD) for 2 clinical mammographic units; CTDIvol, Size-Specific Dose Estimate (SSDE), Dose Length Product (DLP) and total DLP (DLPtot) for 5 CT scanners. Data have been compared with Italian Regulation and with the recent literature. The 75th percentiles of the different dosimetric indices have been calculated. Results We have evaluated the 75th percentile of AGD for each radiogram on both mammography systems and the values are dosimetrically correct. The mean value of these results was defined as our local LDR. For exams performed with more than 5 acquisitions for breast, an alert message has been introduced in the Radimetrics system. Dosimetric data of the most common CT procedures performed on adult patients in our department have been analyzed. In most cases our values result lower or comparable with values reported in recent scientific literature and in Italian law. However, for some procedures we highlighted the need to reduce the number of scans in particular in CAP and chest-abdomen examinations performed on oncological patients. 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 local DRLs for different radiological procedures. The recent introduction of dose tracking software has the potential to facilitate the collection of data and investigation of unusual high dose examinations. Furthermore, dosimetric data of radiological examination must be recorded and reported in order to face the request of the Euratom Directive 2013/59 [1]. We describe our experience with one of this software (Radimetrics version 2.5b, Bayer HealthCare [2]) that has been implemented to define local DRL for selected radiological examinations in Clinical Mammography and Computed Tomography, commonly considered crucial in terms of dosimetric impact. We have collected Average Glandular Dose (AGD) for 2 clinical mammographic units; CTDIvol, Size-Specific Dose Estimate (SSDE), Dose Length Product (DLP) and total DLP (DLPtot) for 5 CT scanners. Data have been compared with Italian Regulation and with the recent literature. The 75th percentiles of the different dosimetric indices have been calculated. We have evaluated the 75th percentile of AGD for each radiogram on both mammography systems and the values are dosimetrically correct. The mean value of these results was defined as our local LDR. For exams performed with more than 5 acquisitions for breast, an alert message has been introduced in the Radimetrics system. Dosimetric data of the most common CT procedures performed on adult patients in our department have been analyzed. In most cases our values result lower or comparable with values reported in recent scientific literature and in Italian law. However, for some procedures we highlighted the need to reduce the number of scans in particular in CAP and chest-abdomen examinations performed on oncological patients. Automated methods of radiation dose data collection allow a fast and detailed analysis of a great amount of data and an easy determination of local DRLs for different radiological procedures.

Purpose We have evaluated the Mean Glandular Doses (MGDs) of Full Field Digital Mammography (FFDM) systems, actually implemented in the Emilia Romagna Screening Program, using the same Plexiglas phantoms. This work aims to evidence the relevance of a large survey to estimate the variability of the doses provided by different mammographic systems available in this screening program. Methods 75 FFDM systems, consisting of 1 Photon-Counting, 33 a-Se Direct, 30 CsI Indirect and 11 Computed Radiography (CR), were characterized by the average values of MGD (mGy) measurements of semi-circular phantom thicknesses of 20 mm, 45 mm and 60 mm. 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] Gennaro G et al., EFOMP Mammo Working Group Protocol, March 2015. Google Scholar ]. 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. We have evaluated the Mean Glandular Doses (MGDs) of Full Field Digital Mammography (FFDM) systems, actually implemented in the Emilia Romagna Screening Program, using the same Plexiglas phantoms. This work aims to evidence the relevance of a large survey to estimate the variability of the doses provided by different mammographic systems available in this screening program. 75 FFDM systems, consisting of 1 Photon-Counting, 33 a-Se Direct, 30 CsI Indirect and 11 Computed Radiography (CR), were characterized by the average values of MGD (mGy) measurements of semi-circular phantom thicknesses of 20 mm, 45 mm and 60 mm. 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] Gennaro G et al., EFOMP Mammo Working Group Protocol, March 2015. Google Scholar ]. 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. 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. 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.

The aim of this article was to characterise the performance of four different digital breast tomosynthesis (DBT) systems in terms of dose and image quality parameters. One of them, GE Pristina, has never been tested before. Average glandular doses were measured both in DBT and 2D full field digital mammography mode. Several phantoms were employed to perform signal difference to noise ratio, slice sensitivity profile, slice to slice incrementation, chest wall offset, z-axis geometry, artefact spread function, low contrast detectability, contrast detail evaluations, image uniformity and in-plane MTF in chest wall-nipple and in tube-travel directions. There are many differences in DBT systems explored: the angular range, detector type, reconstruction algorithms, and the presence or not of the grid. Even if it is not simple to calculate a global figure of merit, the analysis of all the 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.