Search

Aim: To evaluate the prognostic value of somatostatin receptor tumor burden (SRTB) at 68Ga-DOTATOC positron emission tomography/computed tomography (PET/CT) in patients with well-differentiated neuroendocrine tumors (WD-NETs). Methods: We retrospectively analyzed 68Ga-DOTATOC-PET/CT of 84 patients with histologically confirmed WD-NETs (51 G1, 30 G2 and 3 G3). For each PET/CT, all DOTATOC-avid lesions were independently segmented by 2 operators using a customized threshold based on the healthy liver maximum standardized uptake value (SUVmax) using LIFEx 5.1. Somatostatin receptor expressing tumor volume (SRETV) and total lesion somatostatin receptor expression (TLSRE=SRETV*SUVmean) were extracted for each lesion and then whole-body SRETV and TLSRE (SRETVwb and TLSREwb) were defined as the sum of SRETV and TLSRE of all segmented lesions in each patient, respectively. Time to progression (TTP) was defined as the combination of disease-free-survival in patients undergoing curative surgery (n = 10) and progression-free survival for patients with unresectable/metastatic disease (n = 74). TTP and overall survival (OS) were calculated by Kaplan-Meier analysis, log-rank test, and Cox's proportional hazard model. Results: After a median follow-up period of 15.5 months disease progression was confirmed in 35 patients (41.7%) and 14 patients died. Higher SRETVwb (>39.1ml) and TLSREwb (>306.8g) were significantly correlated with shorter median TTP (TTP = 12months vs not reached; p

Purpose To provide a guideline curriculum related to Artificial Intelligence (AI), for the education and training of European Medical Physicists (MPs). Materials and methods The proposed curriculum consists of two levels: Basic (introducing MPs to the pillars of knowledge, development and applications of AI, in the context of medical imaging and radiation therapy) and Advanced. Both are common to the subspecialties (diagnostic and interventional radiology, nuclear medicine, and radiation oncology). The learning outcomes of the training are presented as knowledge, skills and competences (KSC approach). Results For the Basic section, KSCs were stratified in four subsections: (1) Medical imaging analysis and AI Basics; (2) Implementation of AI applications in clinical practice; (3) Big data and enterprise imaging, and (4) Quality, Regulatory and Ethical Issues of AI processes. For the Advanced section instead, a common block was proposed to be further elaborated by each subspecialty core curriculum. The learning outcomes were also translated into a syllabus of a more traditional format, including practical applications. Conclusions This AI curriculum is the first attempt to create a guideline expanding the current educational framework for Medical Physicists in Europe. It should be considered as a document to top the sub-specialties’ curriculums and adapted by national training and regulatory bodies. The proposed educational program can be implemented via the European School of Medical Physics Expert (ESMPE) course modules and – to some extent – also by the national competent EFOMP organizations, to reach widely the medical physicist community in Europe.

Objective To identify the impact of segmentation methods and intensity discretization on radiomic features (RFs) extraction from 68Ga-DOTA-TOC PET images in patients with neuroendocrine tumors. Methods Forty-nine patients were retrospectively analyzed. Tumor contouring was performed manually by four different operators and with a semi-automatic edge-based segmentation (SAEB) algorithm. Three SUVmax fixed thresholds (20, 30, 40%) were applied. Fifty-one RFs were extracted applying two different intensity rescale factors for gray-level discretization: one absolute (AR60 = SUV from 0 to 60) and one relative (RR = min-max of the VOI SUV). Dice similarity coefficient (DSC) was calculated to quantify segmentation agreement between different segmentation methods. The impact of segmentation and discretization on RFs was assessed by intra-class correlation coefficients (ICC) and the coefficient of variance (COVL). The RFs’ correlation with volume and SUVmax was analyzed by calculating Pearson’s correlation coefficients. Results DSC mean value was 0.75 ± 0.11 (0.45–0.92) between SAEB and operators and 0.78 ± 0.09 (0.36–0.97), among the four manual segmentations. The study showed high robustness (ICC > 0.9): (a) in 64.7% of RFs for segmentation methods using AR60, improved by applying SUVmax threshold of 40% (86.5%); (b) in 50.9% of RFs for different SUVmax thresholds using AR60; and (c) in 37% of RFs for discretization settings using different segmentation methods. Several RFs were not correlated with volume and SUVmax. Conclusions RFs robustness to manual segmentation resulted higher in NET 68Ga-DOTA-TOC images compared to 18F-FDG PET/CT images. Forty percent SUVmax thresholds yield superior RFs stability among operators, however leading to a possible loss of biological information. SAEB segmentation appears to be an optimal alternative to manual segmentation, but further validations are needed. Finally, discretization settings highly impacted on RFs robustness and should always be stated.

Our objective was to evaluate the prognostic value of somatostatin receptor tumor burden on

Aim: To evaluate if conventional Positron emission tomography (PET) parameters and radiomic features (RFs) extracted by 18F-FDG-PET/CT can differentiate among different histological subtypes of lung neuroendocrine neoplasms (Lu-NENs). Methods: Forty-four naïve-treatment patients on whom 18F-FDG-PET/CT was performed for histologically confirmed Lu-NEN (n = 46) were retrospectively included. Manual segmentation was performed by two operators allowing for extraction of four conventional PET parameters (SUVmax, SUVmean, metabolic tumor volume (MTV), and total lesion glycolysis (TLG)) and 41 RFs. Lu-NENs were classified into two groups: lung neuroendocrine tumors (Lu-NETs) vs. lung neuroendocrine carcinomas (Lu-NECs). Lu-NETs were classified according to histological subtypes (typical (TC)/atypical carcinoid (AC)), Ki67-level, and TNM staging. The least absolute shrink age and selection operator (LASSO) method was used to select the most predictive RFs for classification and Pearson correlation analysis was performed between conventional PET parameters and selected RFs. Results: PET parameters, in particular, SUVmax (area under the curve (AUC) = 0.91, cut-off = 5.16) were higher in Lu-NECs vs. Lu-NETs (p &lt, 0.001). Among RFs, HISTO_Entropy_log10 was the most predictive (AUC = 0.90), but correlated with SUVmax/SUVmean (r = 0.95/r = 0.94, respectively). No statistical differences were found between conventional PET parameters and RFs (p &gt, 0.05) and TC vs. AC classification. Conventional PET parameters were correlated with N+ status in Lu-NETs. Conclusion: In our study, conventional PET parameters were able to distinguish Lu-NECs from Lu-NETs, but not TC from AC. RFs did not provide additional information.

The purpose of this study was to verify the maintenance of low-contrast detectability at different CT dose reduction levels, in patients of different sizes, as a consequence of the application of iterative reconstruction at different strengths combined with tube current modulation. Anthropomorphic abdominal phantoms of two sizes (small and large) were imaged at a fixed noise with iterative algorithm ASIR-V percentages in the range between 0 and 70% and corresponding dose reductions in the range of 0–83%. A total of 1400 images with and without liver low-contrast simulated lesions were evaluated by five radiologists, using the receiver operating characteristics (ROC) paradigm and evaluating the area under the ROC curve (AUC). The human observer results were then compared with AUC obtained with a channelized Hotelling observer (CHO). CNR values were also calculated. For the small phantom, the AUC values lie between 0.90 and 0.93 for human evaluations of images acquired without iterative reconstruction, with 30% ASIR-V and with 50% ASIR-V. The AUC decreased significantly to 0.81 (p = 0.0001) at 70% ASIR-V. The CHO results were in coherence with human observer scores. Also, similar results were observed for the large size phantom. CNR values were stable for the different ASIR-V percentages. The iterative algorithm maintained the low-contrast detectability up to a dose reduction of about 70%, following application of a 50% ASIR-V combined with automatic tube current modulation, regardless of the phantom size. At further dose reductions using greater iterative percentages, a significant decrease in detectability was observed.

Purpose To perform a systematic review on the research on the application of artificial intelligence (AI) to imaging published in Italy and identify its fields of application, methods and results. Materials and Methods A Pubmed search was conducted using terms Artificial Intelligence, Machine Learning, Deep learning, imaging, and Italy as affiliation, excluding reviews and papers outside time interval 2015–2020. In a second phase, participants of the working group AI4MP on Artificial Intelligence of the Italian Association of Physics in Medicine (AIFM) searched for papers on AI in imaging. Results The Pubmed search produced 794 results. 168 studies were selected, of which 122 were from Pubmed search and 46 from the working group. The most used imaging modality was MRI (44%) followed by CT(12%) ad radiography/mammography (11%). The most common clinical indication were neurological diseases (29%) and diagnosis of cancer (25%). Classification was the most common task for AI (57%) followed by segmentation (16%). 65% of studies used machine learning and 35% used deep learning. We observed a rapid increase of research in Italy on artificial intelligence in the last 5 years, peaking at 155% from 2018 to 2019. Conclusions We are witnessing an unprecedented interest in AI applied to imaging in Italy, in a diversity of fields and imaging techniques. Further initiatives are needed to build common frameworks and databases, collaborations among different types of institutions, and guidelines for research on AI.

Background There is lack of guidance on specific CT protocols for imaging patients with coronavirus disease 2019 (COVID-19) pneumonia. Purpose To assess international variations in CT utilization, protocols, and radiation doses in patients with COVID-19 pneumonia. Materials and Methods In this retrospective data collection study, the International Atomic Energy Agency (IAEA) coordinated a survey between May and July 2020 regarding CT utilization, protocols, and radiation doses from 62 healthcare sites in 34 countries across five continents for CT exams performed in COVID-19 pneumonia. The questionnaire obtained information on local prevalence, method of diagnosis, most frequent imaging, indications for CT, and specific policies on use of CT in COVID-19 pneumonia. Collected data included general information (patient age, weight, clinical indication), CT equipment (CT make and model, year of installation, number of detector rows), scan protocols (body region, scan phases, tube current and potential), and radiation dose descriptors (CT dose index (CTDIvol) and dose length product (DLP)). Descriptive statistics and generalized estimating equations were performed. Results Data from 782 patients (median age (interquartile range) of 59(15) years) from 54 healthcare sites in 28 countries were evaluated. Less than one-half of the healthcare sites used CT for initial diagnosis of COVID-19 pneumonia and three-fourth used CT for assessing disease severity. CTDIvol varied based on CT vendors (7-11mGy, p

Objective To identify the impact of segmentation methods and intensity discretization on radiomic features (RFs) extraction from 68Ga-DOTA-TOC PET images in patients with neuroendocrine tumors. Methods Forty-nine patients were retrospectively analyzed. Tumor contouring was performed manually by four different operators and with a semi-automatic edge-based segmentation (SAEB) algorithm. Three SUVmax fixed thresholds (20, 30, 40%) were applied. Fifty-one RFs were extracted applying two different intensity rescale factors for gray-level discretization: one absolute (AR60 = SUV from 0 to 60) and one relative (RR = min-max of the VOI SUV). Dice similarity coefficient (DSC) was calculated to quantify segmentation agreement between different segmentation methods. The impact of segmentation and discretization on RFs was assessed by intra-class correlation coefficients (ICC) and the coefficient of variance (COVL). The RFs’ correlation with volume and SUVmax was analyzed by calculating Pearson’s correlation coefficients. Results DSC mean value was 0.75 ± 0.11 (0.45–0.92) between SAEB and operators and 0.78 ± 0.09 (0.36–0.97), among the four manual segmentations. The study showed high robustness (ICC > 0.9): (a) in 64.7% of RFs for segmentation methods using AR60, improved by applying SUVmax threshold of 40% (86.5%); (b) in 50.9% of RFs for different SUVmax thresholds using AR60; and (c) in 37% of RFs for discretization settings using different segmentation methods. Several RFs were not correlated with volume and SUVmax. Conclusions RFs robustness to manual segmentation resulted higher in NET 68Ga-DOTA-TOC images compared to 18F-FDG PET/CT images. Forty percent SUVmax thresholds yield superior RFs stability among operators, however leading to a possible loss of biological information. SAEB segmentation appears to be an optimal alternative to manual segmentation, but further validations are needed. Finally, discretization settings highly impacted on RFs robustness and should always be stated. Supplementary Information The online version contains supplementary material available at 10.1186/s40658-021-00367-6.

Objectives: (1.1) to evaluate the association between baseline 18F-FDG PET/CT semi-quantitative parameters of the primary lesion with progression free survival (PFS), overall survival (OS) and response to immunotherapy, in advanced non-small cell lung carcinoma (NSCLC) patients eligible for immunotherapy, (1.2) to evaluate the application of radiomics analysis of the primary lesion to identify features predictive of response to immunotherapy, (1.3) to evaluate if tumor burden assessed by 18F-FDG PET/CT (N and M factors) is associated with PFS and OS. Materials and Methods: we retrospectively analyzed clinical records of advanced NCSLC patients (stage IIIb/c or stage IV) candidate to immunotherapy who performed 18F-FDG PET/CT before treatment to stage the disease. Fifty-seven (57) patients were included in the analysis (F:M 17:40, median age = 69 years old). Notably, 38/57 of patients had adenocarcinoma (AC), 10/57 squamous cell carcinoma (SCC) and 9/57 were not otherwise specified (NOS). Overall, 47.4% patients were stage IVA, 42.1% IVB and 8.8% IIIB. Immunotherapy was performed as front-line therapy in 42/57 patients and as second line therapy after chemotherapy platinum-based in 15/57. The median follow up after starting immunotherapy was 10 months (range: 1.5&ndash, 68.6). Therapy response was assessed by RECIST 1.1 criteria (CT evaluation every 4 cycles of therapy) in 48/57 patients or when not feasible by clinical and laboratory data (fast disease progression or worsening of patient clinical condition in nine patients). Radiomics analysis was performed by applying regions of interest (ROIs) of the primary tumor delineated manually by two operators and semi-automatically applying a threshold at 40% of SUVmax. Results: (1.1) metabolic tumor volume (MTV) (p = 0.028) and total lesion glycolysis (TLG) (p = 0.035) were significantly associated with progressive vs. non-progressive disease status. Patients with higher values of MTV and TLG had higher probability of disease progression, compared to those patients presenting with lower values. SUVmax did not show correlation with PD status, PFS and OS. MTV (p = 0.027) and TLG (p = 0.022) also resulted in being significantly different among PR, SD and PD groups, while SUVmax was confirmed to not be associated with response to therapy (p = 0.427). (1.2) We observed the association of several radiomics features with PD status. Namely, patients with high tumor volume, TLG and heterogeneity expressed by &ldquo, skewness&rdquo, and &ldquo, kurtosis&rdquo, had a higher probability of failing immunotherapy. (1.3) M status at 18F-FDG PET/CT was significantly associated with PFS (p = 0.002) and OS (p = 0.049). No significant associations were observed for N status. Conclusions: 18F-FDG PET/CT performed before the start of immunotherapy might be an important prognostic tool able to predict the disease progression and response to immunotherapy in patients with advanced NSCLC, since MTV, TLG and radiomics features (volume and heterogeneity) are associated with disease progression.

The aim of this study was to evaluate the impact on dose reduction and image quality of the new iterative reconstruction technique: adaptive statistical iterative reconstruction (ASIR-V).Fifty consecutive oncologic patients acted as case controls undergoing during their follow-up a computed tomography scan both with ASIR and ASIR-V. Each study was analyzed in a double-blinded fashion by 2 radiologists. Both quantitative and qualitative analyses of image quality were conducted.Computed tomography scanner radiation output was 38% (29%-45%) lower (P0.0001) for the ASIR-V examinations than for the ASIR ones. The quantitative image noise was significantly lower (P0.0001) for ASIR-V. Adaptive statistical iterative reconstruction-V had a higher performance for the subjective image noise (P = 0.01 for 5 mm and P = 0.009 for 1.25 mm), the other parameters (image sharpness, diagnostic acceptability, and overall image quality) being similar (P0.05).Adaptive statistical iterative reconstruction-V is a new iterative reconstruction technique that has the potential to provide image quality equal to or greater than ASIR, with a dose reduction around 40%.

(1) Background: Bone tissue engineering is a promising tool to develop new smart solutions for regeneration of complex bone districts, from orthopedic to oral and maxillo-facial fields. In this respect, a crucial characteristic for biomaterials is the ability to fully integrate within the patient body. In this work, we developed a novel radiological approach, in substitution to invasive histology, for evaluating the level of osteointegration and osteogenesis, in both qualitative and quantitative manners. (2) SmartBone&reg, a composite xeno-hybrid bone graft, was selected as the base material because of its remarkable effectiveness in clinical practice. Using pre- and post-surgery computed tomography (CT), we built 3D models that faithfully represented the patient&rsquo, s anatomy, with special attention to the bone defects. (3) Results: This way, it was possible to assess whether the new bone formation respected the natural geometry of the healthy bone. In all cases of the study (four dental, one maxillo-facial, and one orthopedic) we evaluated the presence of new bone formation and volumetric increase. (4) Conclusion: The newly established radiological protocol allowed the tracking of SmartBone&reg, effective integration and bone regeneration. Moreover, the patient&rsquo, s anatomy was completely restored in the defect area and functionality completely rehabilitated without foreign body reaction or inflammation.

This document aims to support the dental professional in choosing the adequate diagnostic technique, minimising the radiation dose in observance of the As Low As Reasonably Achievable (ALARA) principle (7). This principle states that the biological cost can only be justifed when the beneft, that is, the diagnosis, outweighs the risk related to radiation exposure. In this guideline paper, we report recommendations for radiologists, medical physicists, paediatrician, dentists and maxillofacial surgeons, with reference to the specifc felds.

Purpose This study investigated the benefits of implementing a cluster analysis technique to extract relevant information from a computed tomography (CT) dose registry archive. Methods A CT patient dose database consisting of about 12,000 examinations and 29,000 single scans collected from three CT systems was interrogated. The database was divided into six subsets according to the equipment and the reference phantoms in the definition of the dose indicators. Hierarchical (single, average, and complete linkage, Ward) and not hierarchical (K-means) clustering methods were implemented using R software. The suitable number of clusters for each CT system was determined by analysing the dendrogram, the within clusters sum of squares, and the cluster content. Summary statistics were produced for each cluster, and the outliers of the dose indicator distribution were investigated. Results Ward clustering identified the most common combinations of scanning parameters for each group. The optimal number of clusters for each CT equipment system ranged from 5 to 15. The main diagnostic applications were then extracted from each cluster. Outlier analysis of the dose indicator distribution of each cluster revealed potential improper settings that resulted in increased patient dose. Conclusions Clustering methods applied to CT patient dose archives provide a quick and effective overview of the main combinations of currently used exposure parameters and the consequences for dose indicator distributions, also when protocol labels and/or study descriptions are not homogeneous.

Purpose: The aim of this study was to evaluate various approaches for assessing patient organdoses resulting from radiotherapy cone-beam CT(CBCT), by the use of thermoluminescent dosimeter(TLD) measurements in anthropomorphic phantoms, a Monte Carlo based dose calculation software, and different dose indicators as presently defined. Methods: Dose evaluations were performed on a CBCT Elekta XVI (Elekta, Crawley, UK) for different protocols and anatomical regions. The first part of the study focuses on using pcxmcsoftware (pcxmc 2.0, STUK, Helsinki, Finland) for calculating organdoses, adapting the input parameters to simulate the exposure geometry, and beamdose distribution in an appropriate way. The calculated doses were compared to readouts of TLDs placed in an anthropomorphic Rando phantom. After this validation, the software was used for analyzing organdose variability associated with patients’ differences in size and gender. At the same time, various dose indicators were evaluated: kerma area product (KAP), cumulative air-kerma at the isocenter (Kair), cone-beam dose index, and central cumulative dose. The latter was evaluated in a single phantom and in a stack of three adjacent computed tomography dose index phantoms. Based on the different dose indicators, a set of coefficients was calculated to estimate organdoses for a range of patient morphologies, using their equivalent diameters. Results: Maximum organdoses were about 1 mGy for head and neck and 25 mGy for chest and pelvis protocols. The differences between pcxmc and TLDsdoses were generally below 10% for organs within the field of view and approximately 15% for organs at the boundaries of the radiationbeam. When considering patient size and gender variability, differences in organdoses up to 40% were observed especially in the pelvic region; for the organs in the thorax, the maximum differences ranged between 20% and 30%. Phantom dose indexes provided better correlation with organdoses than Kair and KAP, with average ratios ranging between 0.9 and 1.1 and variations for different organs and protocols below 20%. The triple phantom setup allowed us to take into account scatter dose contributions, but nonetheless, the correlation with the evaluated organdoses was not improved with this method. Conclusions: The simulation of rotational geometry and of asymmetric beam distribution by means of pcxmc 2.0 enabled us to determine patient organdoses depending on weight, height and gender. Alternatively, the measurement of an in phantom dose indicator combined with proper correction coefficients can be a useful tool for a first dose estimation of in-field organs. The data and coefficients provided in this study can be applied to any patient undergoing a scan by an Elekta XVI equipment.

The purpose of this study was to optimize an aorta angiographic CT protocol, by investigating the best combination of tube current modulation, iterative algorithm strength and kV reduction. Anthropomorphic phantoms of three sizes were imaged by CT with different values of noise index, of iterative algorithm ASIR percentages and kV in the range 80–120. Quantitative noise and contrast noise ratios were evaluated at different phantom locations. Three radiologists assessed the subjective image quality by comparing the image series with the one acquired with the reference protocol (120 kV, slice thickness 0.625, noise index 28, ASIR 40 %). Although the highest CNR values were obtained for the 80 kV acquisitions, qualitative scores were higher for 100 and 120 kV at the same noise index. An optimized protocol was established with a NI of 39.2, ASIR 60 %, 100 kV for small- and medium-sized patients and 120 kV for large-sized patients, with a dose reduction of 47 %. When different dose reduction parameters are available, anthropomorphic phantoms of different sizes help to find the optimal combination. For aorta studies, 100 kV with relative high values of noise indexes and iterative levels provides the best balance between dose reduction and image quality.

The aim of this study was to evaluate images quality and radiation doses of Cone Beam Computed Tomography (CBCT) for dental and maxillofacial imaging testing five different acquisition protocols. Dose measurements of different acquisition protocols were calculated for Pax Zenith three-dimensional (3D) Cone Beam (Vatech, Korea) and for conventional orthopantomography (OPT) and cephalometric skull imaging Ortophos (Sirona Dental Systems, Bernsheim, Germany). The absorbed organ doses were measured using an anthropomorphic phantom loaded with thermoluminescent dosimeters at 58 sites related to sensitive organs. Five different CBCT protocols were evaluated for image quality and radiation doses. They differed in FOV, image resolution, kVp, mA, acquisition time in seconds and radiation dose. Measurements were then carried out with the orthopantomograph. Equivalent and effective doses were calculated. The reference protocol with large FOV, high resolution quality images, 95 kVp, 5 mA and acquisition time of 24 s resulted in a DAP value of 1556 mGy cm2 instead the protocol with reduced kVp from 95 to 80 kVp translated into a value of DAP inferior to 35% (from 1556 to 1013 mGy cm2). Going from a high resolution to a normal resolution, there was a reduction of the acquisition time to 15 s which allowed further dose reduction of approximately 40% (628 mGy cm2); this protocol resulted in a value of effective dose of 35 microSievert (μSv). Moreover, the effect of changing FOV has been evaluated, considering two scans with a reduced FOV (160 × 140 and 120 × 90 mm, respectively). CBCT low-dose protocol with large FOV, normal resolution quality images, 80 kVp, 5 mA and acquisition time of 15 s resulted in a value of effective dose of 35 microSievert (μSv). This protocol allows the study of maxillofacial region with high quality of images and a very low radiation dose and, therefore, could be proposed in selected case where a complete assessment of dental and maxillofacial region is useful for treatment planning.

Purpose The protocol for quality control of CBCT devices was produced as consensus among active MPEs of EFOMP, ESTRO and IAEA. It is available on-line since September 2017. In the beginning of 2018 we published an update including an appendix on patient dosimetry by EURADOS, comments by the German institute of standards (DIN) and remarks by users from countries that were not involved in the first edition, such as Austria, Costa Rica and Australia. This contribution gives a general overview of the guideline including insights about this recent update. Methods The guideline focuses on the measurement of objective image quality parameters and radiation output from any kind of CBCT device, including applications in dental radiology, C-arms and guidance systems in radiotherapy. Indications to use commercial or non-commercial phantoms and software are given, as well as to use ionization chambers or solid state dosemeters. The new EURADOS appendix includes an extensive review of patient dose data from recent research papers, organized by application and dose indicators: CTDI, DAP, effective dose, entrance surface dose, CTDIw, absorbed dose, D1-D2 and air kerma. The DIN has reviewed the details of the standards 6868–161 and 6868–15 for acceptance and constancy tests in dental CBCT. Individual comments have helped to clarify the measurements of radiation output and the methods to measure the modulation transfer function. Some colleagues have stressed the informative value of the appendices. Results The comments received were reviewed by the authors of the corresponding sections and discussed by the group in virtual meetings before being published as an update. The mentioned additions are meant to keep the document alive. They respond to questions raised by physicists that are starting to use the protocol inside and outside Europe. Conclusions The first presentation in the ECMP in Athens was followed by international presentations at ESTRO, ECR, IOMP and IRPA and national presentations in Italy, Spain, UK, Germany and other countries. Thanks to these voluntary efforts, physicists around the world are using and improving the document together. We also welcome your participation in this session and your feedback.

Purpose Daily images from CBCT could deliver significant dose to the patient, which should be considered and evaluated. It is essential to associate the absorbed dose delivered by the imaging procedures to the treatment of each patient. Aim of this work is to calculate organ doses for patients undergoing Cone Beam CT (CBCT) when treated with radiotherapy. Methods The system in use was an Elekta CBCT (XVI) and the protocols analysed were four: head, pelvis, chest and chest 4D with different parameters. The formula for organ dose calculation was obtained from Rampado et al. [1] where dose to organs were evaluated by means of Monte Carlo simulation in phantom; the effect of patient size were also accounted for. Dose to organs involved in CBCT scans is: D T = D W , 1 Ph · ( D T / D W , 1 Ph ) tab · a · e - bx where D W , 1 Ph is the measured dose in a phantom for the specific protocol, x is the effective diameter of the patient, ( D T / D W , 1 Ph ) tab , a and b are tabulated data from the article cited above. Patients were analyzed from March to June 2017. For each case were registered: the effective diameter from simulation CT, CBCT protocol, number of CBCT scans. Results Two hundred patients were considered. For head protocol, the mean CBCT doses were about 20 ± 10 mGy for all organs. Instead, doses of about 400 ± 150 mGy were evaluated for pelvis protocol. CBCT Doses for Chest 4D protocol were lower than other chest ones (about 50 ± 25 mGy vs 400 ± 150 mGy). This difference was due to number of CBCT scans/treatment fractions. Conclusions Doses from CBCT procedures should be accounted for; based on organ doses calculation, a program of dose optimization could be performed.

The aim of this study was to evaluate various approaches for assessing patient organ doses resulting from radiotherapy cone-beam CT (CBCT), by the use of thermoluminescent dosimeter (TLD) measurements in anthropomorphic phantoms, a Monte Carlo based dose calculation software, and different dose indicators as presently defined.Dose evaluations were performed on a CBCT Elekta XVI (Elekta, Crawley, UK) for different protocols and anatomical regions. The first part of the study focuses on using pcxmc software (pcxmc 2.0, STUK, Helsinki, Finland) for calculating organ doses, adapting the input parameters to simulate the exposure geometry, and beam dose distribution in an appropriate way. The calculated doses were compared to readouts of TLDs placed in an anthropomorphic Rando phantom. After this validation, the software was used for analyzing organ dose variability associated with patients' differences in size and gender. At the same time, various dose indicators were evaluated: kerma area product (KAP), cumulative air-kerma at the isocenter (Kair), cone-beam dose index, and central cumulative dose. The latter was evaluated in a single phantom and in a stack of three adjacent computed tomography dose index phantoms. Based on the different dose indicators, a set of coefficients was calculated to estimate organ doses for a range of patient morphologies, using their equivalent diameters.Maximum organ doses were about 1 mGy for head and neck and 25 mGy for chest and pelvis protocols. The differences between pcxmc and TLDs doses were generally below 10% for organs within the field of view and approximately 15% for organs at the boundaries of the radiation beam. When considering patient size and gender variability, differences in organ doses up to 40% were observed especially in the pelvic region; for the organs in the thorax, the maximum differences ranged between 20% and 30%. Phantom dose indexes provided better correlation with organ doses than Kair and KAP, with average ratios ranging between 0.9 and 1.1 and variations for different organs and protocols below 20%. The triple phantom setup allowed us to take into account scatter dose contributions, but nonetheless, the correlation with the evaluated organ doses was not improved with this method.The simulation of rotational geometry and of asymmetric beam distribution by means of pcxmc 2.0 enabled us to determine patient organ doses depending on weight, height and gender. Alternatively, the measurement of an in phantom dose indicator combined with proper correction coefficients can be a useful tool for a first dose estimation of in-field organs. The data and coefficients provided in this study can be applied to any patient undergoing a scan by an Elekta XVI equipment.

Purpose In this study, we investigated the applicability and effectiveness of a data mining technique applied to a CT patient dose archive. In particular, we proposed an automatic extraction of homogeneous groups of CT scans, with isolation of the differences in dose indicators due to the main exposure parameters combinations, compared to those linked to the anatomical variability of the patients. Methods A CT patient dose archive collected with a dose tracking software over the course of a calendar year was considered. It resulted in more than 10,000 examinations and 23,000 scans performed on three equipments, which differ both in terms of the technological generation and the type of diagnostic activity. Hierarchical and not hierarchical clustering methods were applied in the R environment considering different sets of quantitative variables, including only the exposure parameters more influent on image quality and patient dose and not considering the examinations and protocols textual labels. The proper number of cluster for each equipment was determined on the base of the dendrogram and of the within clusters sum of squares. Summary statistics were produced for each cluster and the outliers of the dose indicators distribution were analysed. Results Ward and k-means methods were more effective than other clustering methods. A consistent association between the clusters of homogeneous scanning parameters and the main diagnostic applications was found. Different optimal numbers of clusters, in the range 5–15, were individuated for the three considered equipments. The box and whiskers plots of the dose indicators reflected the homogeneity of the clusters exposure settings and allowed to rapidly identify the protocols with different dose levels. The outliers of the dose indicators distributions reached in some cases the 5% of the scans and many of them were operator’s changes of the standard protocols resulting in a patient dose increase. Conclusions Despite the numerical relevance of the examined datasets, the rapidity of execution and the communicative efficacy of the clustering method outputs are of great interest for the possible implementation of a routine tool for the optimization of the radiation dose in computed tomography.

Gafchromic® XR-QA films were developed for patient dosimetry in diagnostic radiology. A possible application of these films is the measurement of doses in computed tomography. In this study a method to evaluate the CTDI using Gafchromic XR-QA film and a flatbed scanner was developed and tested. Film samples were cut to dimensions of 6 × 170 mm 2 in order to have an integration area similar to that of a pencil ionization chamber, with the possibility of changing the integration length. Prior to exposing these films to a computed tomography beam, the angular dependence of the film dose response was investigated by exposing film strips to a static x-ray beam at different angles in the range 0°–180°. A difference of 49% was found between the response with the axis beam parallel to the film surface (90°) and with the axis beam perpendicular (0° and 180°). Integrating over a 360° exposure like the one in computed tomography, a difference of less than 2% was estimated, which is comparable with the measurement error obtainable with XR-QA film. A calibration with a CT beam in the scout mode was performed and film strips were then exposed to single axial scans and to helical scans both in air and in phantoms. Two different types of flatbed scanners were used to read the film samples, a Microtek ScanMaker 9800XL scanner and an Epson Expression 10000 XL scanner, and the accuracy of the results were compared. For beam collimations above 10 mm differences between CTDI measured by film and CTDI measured by ionization chamber below 9% were found for the Epson scanner, with an average estimated error at 1 σ level of 5%. For the Microtek scanner and for the same film samples, differences below 11% with an average error at 1 σ level of 8% were founded. The 1 σ uncertainty of the measured CTDI was provided by the method for each measurement, and it was shown that about the 95% of the differences between the CTDI measurements with radiochromic films and with the ionization chamber were below the estimated 2 σ uncertainty, for both scanners. After an accurate calibration procedure and the consideration of the uncertainty associated with the measurement, Gafchromic® XR-QA films can be used to evaluate the CTDI.

The purpose of this study was to evaluate the radiation dose to patients during radiological contrast studies performed after vertical banded gastroplasty (VBG) or Roux-en-Y gastric bypass (RYGBP) surgery in patients with morbid obesity.Dose evaluations were performed on a sample of 39 patients (32 women and 7 men) with a mean weight of 117 kg (range 68-175 kg) and a mean body mass index (BMI) of 43.7 (range 22.2-54.9). Between the second and seventh postoperative day, patients underwent radiological follow-up after oral administration of approximately 70 ml of water-soluble iodinated contrast material (Gastrografin) and images acquired in anteroposterior, right and left oblique projections with the patient upright and then supine. Exposure conditions, dose-area product (DAP) and entrance skin dose (ESD) were recorded for each procedure. On the basis of these data, the effective dose (ED) was calculated using simulation software based on the Monte Carlo method for determining the absorbed dose to organs. To assess the optimal exposure conditions and the dose contributions of fluoroscopy and radiography, the effective dose rates were also evaluated using Plexiglas phantoms of different thickness to simulate different patient sizes.The phantom measurements showed a fourfold dose increase when passing from normal-sized patients to obese patients. Mean DAP value obtained from in-vivo measurements was 70 Gy cm(2) (range 17-147 Gy cm(2)), and mean effective dose was 21 mSv (range 5-45 mSv).When performing radiological contrast studies in patients with morbid obesity, every possible precaution should be taken to minimise patient dose. Special care should be taken to evaluate justification of the radiological procedure.

This study was undertaken to evaluate patient dose in paediatric liver transplant recipients treated by percutaneous biliary drainage and bilioplasty procedures.Effective dose rates and entrance skin-dose (ESD) rates per minute of fluoroscopy were measured by using a plexiglas phantom (thickness 10 cm) simulating the patient and by varying the exposure parameters (type of pulsed fluoroscopy, image intensifier diameter, presence of diaphragms) to identify the technique delivering the lowest patient dose. In vivo measurements were performed during three interventional procedures.The effective dose rate proved to be lowest for a particular type of pulsed fluoroscopy, with maximum magnification and with field-limiting diaphragms. The in vivo measurements showed a maximum ESD value of around 50 MGY (the threshold for transient erythema is 2,000 MGY, ICRP 60). The effective dose values were in the range of 0.9-1.5 MSV.We established exposure parameters providing the desired image quality with the lowest dose for the equipment used and for a specific type of interventional procedure. The measured ESD values allow us to exclude the risk of deterministic effects on the skin. The effective dose values and considerations regarding the likelihood of radiation-induced cancer led to the conclusion that the radiological risk for the patient is largely justified by the benefits of these kinds of procedure.

The purpose of this paper is to describe the automation of quality control procedures on photo-stimulable imaging plates by means of an image-processing tool providing automatic reading of the images and automatic calculation of the quality parameters monitored.Quality-control procedures were performed according to the main available guidelines. The quality assurance programme was applied to several Kodak and Philips devices in four radiological departments. The automatic image-processing tool was developed using public domain software (Java-based ImageJ software) and contains both reading and computation procedures.The quality checks and algorithms described were successfully applied, proving useful for identification of defective plates and for implementation of the quality assurance programme. The use of automation allowed significant savings in the time required for quality checks.Completely automated image reading allows substantial economic and human resources savings, as it eliminates much of the transfer, reproduction, processing and filing procedures.

Introduction Current guidelines for quality control of CBCT devices consider the available applications (dental, radiotherapy, interventional radiology and guided surgery) as different entities. However, the data acquisition and reconstruction methods are similar. Henceforth, the evaluation parameters for image quality and dose can be unified. Purpose The purpose of this guideline (under discussion since January 2014 within an EFOMP working group) is to present an objective, practical and unifying procedure for quality control of all imaging CBCT applications Materials and methods The parameters used for image quality assessment are uniformity, accuracy of density values (or Hounsfield units where appropriate), geometrical evaluation, noise, low contrast resolution (including contrast to noise ratio) and high contrast resolution. Results Detailed procedures using free software and commercially available test phantoms are described. The dosimetric quantities under consideration are CTDI, kerma area product and detector incident air kerma. Recommended action levels and test frequency are indicated together with references wherever possible. Conclusion This guideline includes the minimum tests that should be performed to ensure reliable, safe and consistent performance of CBCT devices. This minimum has been sought to guarantee compatibility with all manufacturers and existing European documents (DIN 6868161, HPACRCE010 and RP 172 for dental applications). Disclosure Nothing to disclose.

Nella descrizione delle sequenze sono gia state introdotte numerose considerazioni riguardanti la qualia dell’immagine correlata ai diversi tipi di contrasto ottenibili. In questa sezione saranno fornite le definizioni degli indici di qualita dell’immagine e saranno considerati gli effetti su di essi delle variazioni dei principali parametri scelti all’atto dell’impostazione della modalita di acquisizione.

A differenza di altre metodiche radiologiche come la tomografia computerizzata (TC), la risonanza magnetica offre molteplici possibilita di contrasto.

Per indicare un protocollo di acquisizione in risonanza magnetica e utilizzato il termine sequenza. Il termine sta a indicare che l’azione dei diversi campi magnetici utilizzati, in particolare gli impulsi a radiofrequenza e dei gradienti, deve avvenire “in sequenza”, con tempi e durate specifiche per il tipo di contrasto che si desidera ottenere.

Con il termine “perfusione” ci si riferisce al rifornimento di ossigeno e sostanze nutrienti ai tessuti tramite il flusso sanguigno. Esso rappresenta, dunque, uno dei piu importanti parametri fisiologici: disturbi nella perfusione si trovano tra le principali cause di disabilita e mortalita. Solitamente utilizzate per la loro capacita diagnostica nella diagnosi diretta di alterazioni vascolari, le misurazioni perfusionali possono essere utili anche come marker per un piu ampio ventaglio di funzioni, fisiologiche o fisiopatologiche. La stretta relazione tra funzioni metaboliche e flusso sanguigno cerebrale permette anche la valutazione di funzioni cerebrali, tramite misurazioni di perfusione loco-regionali (fMRI), e l’aumentato grado di vascolarizzazione che avviene in alcune neoplasie permette di utilizzare la perfusione nel dare una misura del grado di aggressivita del tumore e per valutare la sua risposta alle terapie.

Non e ancora stato finora affrontato il tema della formazione dell’immagine, che si basa su concetti esclusivi e totalmente differenti da quelli di altre metodiche radiologiche. Il segnale proveniente dai tessuti sotto forma di radiofrequenze non e associato a un’informazione di tipo spaziale, come avviene in radiologia o in tomografia computerizzata (TC) dove il fascio radiogeno primario segue traiettorie rettilinee dalla sorgente al rivelatore. Le onde RF si propagano in ogni direzione dello spazio e sono rilevate dalle bobine, le quali misurano un segnale a prescindere dalla sua provenienza.

In una sala diagnostica RM sono presenti diverse sorgenti di rischio che possono provocare effetti di entita molto diverse tra loro, passando da lievi alterazioni fisiopatologiche conseguenti all’esposizione a radiazioni non ionizzanti e campi magnetici, fino ad arrivare a incidenti potenzialmente letali legati all’interferenza tra i campi magnetici ed eventuali dispositivi elettronici impiantati, oppure all’attrazione esercitata dal campo statico su oggetti ferromagnetici indebitamente introdotti nella sala del magnete. Si possono poi prendere in considerazione altri fattori di rischio di natura diversa legati, per esempio, alle elevate intensita di rumore presente durante l’acquisizione dell’immagine, o alle possibili conseguenze di malfunzionamenti nei dispositivi di controllo dei fluidi criogeni.

Per comprendere i meccanismi alla base della metodica di risonanza magnetica, occorre necessariamente considerare i principi fisici su cui essa si fonda. La denominazione stessa deriva dalla natura dei fenomeni coinvolti, relativi alle teorie dell’elettromagnetismo e al concetto di risonanza. Il termine “nucleare”, utilizzato in passato, data la natura magnetica dei nuclei atomici che genera il segnale, e oggi evitato perche evocativo di rischi e situazioni di pericolo inesistenti. Il protone, nucleo dell’atomo di idrogeno, e in effetti il protagonista della generazione del segnale necessario per la formazione dell’immagine e nella trattazione seguente si vedra come esso puo subire eccitazione e rilasciare energia in forma di campi elettromagnetici, misurabile con opportuni dispositivi. Poiche tutto questo avviene con intensita e tempi diversi per i diversi tessuti biologici, si viene a creare l’opportunita di ottenere un’informazione utile ai fini diagnostici.

La principale caratteristica delle immagini digitali e la possibilita di sottoporle a elaborazione numerica: i pixel possiedono caratteristiche di colore e luminosita associate a numeri, il cui valore puo essere modificato secondo opportuni algoritmi di trasformazione; le caratteristiche dell’immagine finale saranno frutto delle trasformazioni applicate.