Servizio di Fisica Sanitaria
Servizio di Fisica Sanitaria
Ghetti C.,Servizio di Fisica Sanitaria |
Palleri F.,Servizio di Fisica Sanitaria |
Serreli G.,Servizio di Fisica Sanitaria |
Ortenzia O.,Servizio di Fisica Sanitaria
Journal of Applied Clinical Medical Physics | Year: 2013
Recently a new iterative reconstruction algorithm named Sinogram Affirmed Iterative Reconstruction (SAFIRE) has been released by Siemens. This algorithm works in the raw data domain with noise reduction as main purpose, providing five different strengths. In this study, the effect of SAFIRE on image quality has been investigated using selected phantoms and a comparison with standard filtered back projection (FBP) has been carried out. The following quantitative parameters have been evaluated: image noise, impact of different reconstruction kernels on noise reduction, noise power spectrum (NPS), contrast-to-noise ratio (CNR), spatial resolution, and linearity and accuracy of CT numbers. The influence of strengths on image quality parameters has also been examined. Results show that image noise reduction is independent of reconstruction kernel and strongly related to the strength of SAFIRE applied. The peak of NPS curve for SAFIRE reconstructions is shifted towards low frequencies; this effect is more marked at higher levels of strength. Contrast-to-noise ratio is always improved in SAFIRE reconstruction and increases with higher strength. At different dose levels SAFIRE preserves CT number accuracy, linearity, and spatial resolution, both in transversal and coronal planes. These results confirm that SAFIRE allows for image noise reduction with preserved image quality. First clinical data to validate this phantom analysis and confirm that commercially available iterative algorithms can play an effective role in dose containment.
Iori M.,Servizio di Fisica Sanitaria |
Cagni E.,Servizio di Fisica Sanitaria |
Paiusco M.,Servizio di Fisica Sanitaria |
Munro P.,Varian Medical Systems |
Nahum A.E.,Clatterbridge Center for Oncology
Medical Physics | Year: 2010
Purpose: The electronic portal imaging device (EPID) is a system for checking the patient setup; as a result of its integration with the linear accelerator and software customized for dosimetry, it is increasingly used for verification of the delivery of fixed-field intensity-modulated radiation therapy (IMRT). In order to extend such an approach to intensity-modulated arc therapy (IMAT), the combined use of an EPID system and a portal dose image prediction (PDIP) tool has been investigated. Methods: The dosimetric behavior of an EPID system, mechanically reinforced to maintain its positional stability during the accelerator gantry rotation, has been studied to assess its ability to measure portal dose distributions for IMAT treatment beams. In addition, the PDIP tool of a commercial treatment planning system, commonly used for static IMRT dosimetry, has been validated for simulating the PDIs of IMAT treatment fields. The method has been applied to the delivery verification of 23 treatment fields that were measured in their dual mode of IMRT and IMAT modalities. Results: The EPID system has proved to be appropriate for measuring the PDIs of IMAT fields; additionally the PDIP tool was able to simulate these accurately. The results are quite similar to those obtained for static IMRT treatment verification, although it was necessary to investigate the dependence of the EPID signal and of the accelerator monitor chamber response on variable dose rate. Conclusions: Our initial tests indicate that the EPID system, together with the PDIP tool, is a suitable device for the verification of IMAT plan delivery; however, additional tests are necessary to confirm these results. © 2010 American Association of Physicists in Medicine.
Gambitta P.,Unita di Chirurgia Endoscopica ed Ecoendoscopia Ospedale Niguarda Ca Granda |
Armellino A.,Unita di Chirurgia Endoscopica ed Ecoendoscopia Ospedale Niguarda Ca Granda |
Forti E.,Unita di Chirurgia Endoscopica ed Ecoendoscopia Ospedale Niguarda Ca Granda |
Vertemati M.,University of Milan |
And 2 more authors.
World Journal of Gastroenterology | Year: 2014
AIM: To investigate the impact of endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) in association with a multidisciplinary team evaluation for the detection of gastrointestinal malignancies. METHODS: A cohort of 1019 patients with suspected malignant lesions adjacent to the gastrointestinal tract received EUS-FNA after a standardized multidisciplinary team evaluation (MTE) and were divided into 4 groups according to their specific malignant risk score (MRS). Patients with a MRS of 0 (without detectable risk of malignancy) received only EUS without FNA. For patients with a MRS score ranging from 1 (low risk) - through 2 (intermediate risk) - to 3 (high risk), EUS-FNA cytology of the lesion was planned for a different time and was prioritized for those patients at higher risk for cancer. The accuracy, efficiency and quality assessment for the early detection of patients with potentially curable malignant lesions were evaluated for the whole cohort and in the different classes of MRSs. The time to definitive cytological diagnosis (TDCD), accuracy, sensitivity, specificity, positive and negative predictive values, and the rate of inconclusive tests were calculated for all patients and for each MRS group. RESULTS: A total of 1019 patients with suspected malignant lesions were evaluated by EUS-FNA. In 515 patients of 616 with true malignant lesions the tumor was diagnosed by EUS-FNA; 421 patients with resectable lesions received early surgical treatment, and 94 patients received chemo-radiotherapy. The overall diagnostic accuracy for the 1019 lesions in which a final diagnosis was obtained by EUS-FNA was 0.95. When patients were stratified by MTE into 4 classes of MRSs, a higher rate of patients in the group with higher cancer risk (MRS-3) received early treatment and EUS-FNA showed the highest level of accuracy (1.0). TDCD was also shorter in the MRS-3 group. The number of patients who received surgical treatment or chemo-radiotherapy was significantly higher in the MRS-3 patient group (36.3% in MRS-3, 10.7% in MRS-2, and 3.5% in MRS-1). CONCLUSION: EUS-FNA can effectively detect a curable malignant lesions at an earlier time and at a higher rate in patients with a higher cancer risk that were evaluated using MTE. © 2014 Baishideng Publishing Group Inc. All rights reserved.
Broggi S.,Servizio di Fisica Sanitaria |
Cantone M.C.,University of Milan |
Chiara A.,Servizio di Radioterapia |
Di Muzio N.,Servizio di Radioterapia |
And 3 more authors.
Journal of Applied Clinical Medical Physics | Year: 2013
The aim of this paper was the application of the failure mode and effects analysis (FMEA) approach to assess the risks for patients undergoing radiotherapy treatments performed by means of a helical tomotherapy unit. FMEA was applied to the preplanning imaging, volume determination, and treatment planning stages of the tomotherapy process and consisted of three steps: 1) identification of the involved subprocesses; 2) identification and ranking of the potential failure modes, together with their causes and effects, using the risk probability number (RPN) scoring system; and 3) identification of additional safety measures to be proposed for process quality and safety improvement. RPN upper threshold for little concern of risk was set at 125. A total of 74 failure modes were identified: 38 in the stage of preplanning imaging and volume determination, and 36 in the stage of planning. The threshold of 125 for RPN was exceeded in four cases: one case only in the phase of preplanning imaging and volume determination, and three cases in the stage of planning. The most critical failures appeared related to (i) the wrong or missing definition and contouring of the overlapping regions, (ii) the wrong assignment of the overlap priority to each anatomical structure, (iii) the wrong choice of the computed tomography calibration curve for dose calculation, and (iv) the wrong (or not performed) choice of the number of fractions in the planning station. On the basis of these findings, in addition to the safety strategies already adopted in the clinical practice, novel solutions have been proposed for mitigating the risk of these failures and to increase patient safety.
Begnozzi L.,UOC di Fisica Sanitaria |
Cantone M.C.,University of Milan |
Longobardi B.,Servizio di Fisica Sanitaria |
Veronese I.,University of Milan
Radioprotection | Year: 2014
In the last few years there has been significant development of radiation therapy (RT) equipment with advanced imaging and delivery techniques, as well as treatment planning systems. From this perspective, proactive approaches for risk assessment were identified as a powerful tool in modern radiation oncology. A multidisciplinary working group (WG) has been established in the framework of the Italian association for medical physics (AIFM) to promote the use of prospective approaches in the radiotherapy scientific community. This paper describes the main actions carried out by the WG in order to collect information about the engagement of Italian medical physicists in the risk management process, in reporting possible incidents in RT and in the procedures of collecting and analysing near misses. In particular, the main scope of the study was to evaluate the actual level of experience in use of proactive risk analysis tools in modern RT by medical physicists. Finally, the measures implemented by the WG in order to promote the use of such approaches, and consequently to contribute to enhancing safety and radiation protection culture in radiation oncology are described. © EDP Sciences 2013.
Tambasco N.,University of Perugia |
Muti M.,Servizio di Fisica Sanitaria |
Chiarini P.,Servizio di Neuroradiologia |
Tarducci R.,Servizio di Fisica Sanitaria |
And 7 more authors.
PLoS ONE | Year: 2014
Background and Purpose: Wearing-off is one of the most frequent problems encountered by levodopa-treated patients. Entacapone, a peripheral inhibitor of catechol-O-methyltransferase (COMT), reduces this motor complication by prolonging the effect of levodopa. We sought to understand the impact of COMT-inhibition on movement execution in PD patients with wearing-off by comparing functional magnetic resonance imaging (f-MRI) activation patterns prior to and during entacapone treatment. Our hypothesis was to determine whether changes in cortical activation are associated to COMT-inhibitor treatment. Methods: Nine levodopa-treated non-demented PD patients with wearing-off were prospectively studied in two f-MRI session, prior to and during entacapone treatment. A group of control subjects were also studied for comparison. Results: The patients significantly improved under COMT-inhibitor treatment based on home diaries. F-MRI results showed that at baseline the patients presented a bilateral activation of the primary motor, controlateral premotor cortex and supplementary motor area, as well as ipsilateral cerebellum. During treatment with entacapone, PD patients showed reductions in the activations of these cortical areas and a decreased activation in the ipsilateral cerebellum. Conclusions: Our preliminary findings indicate that f-MRI is able to detect cortical activation changes during long-term modulation of dopaminergic treatment in PD patients with wearing-off, and thus, this technique could be further investigated in advanced PD patients. © 2014 Tambasco et al.
Caproni S.,University of Perugia |
Muti M.,Servizio di Fisica Sanitaria |
Principi M.,Servizio di Neuroradiologia |
Ottaviano P.,Servizio di Neuroradiologia |
And 6 more authors.
PLoS ONE | Year: 2013
Motor impairment is the most relevant clinical feature in Parkinson's disease (PD). Functional imaging studies on motor impairment in PD have revealed changes in the cortical motor circuits, with particular involvement of the fronto-striatal network. The aim of this study was to assess brain activations during the performance of three different motor exercises, characterized by progressive complexity, using a functional fMRI multiple block paradigm, in PD patients and matched control subjects. Unlike from single-task comparisons, multi-task comparisons between similar exercises allowed to analyse brain areas involved in motor complexity planning and execution. Our results showed that in the single-task comparisons the involvement of primary and secondary motor areas was observed, consistent with previous findings based on similar paradigms. Most notably, in the multi-task comparisons a greater activation of supplementary motor area and posterior parietal cortex in PD patients, compared with controls, was observed. Furthermore, PD patients, compared with controls, had a lower activation of the basal ganglia and limbic structures, presumably leading to the impairment in the higher levels of motor control, including complexity planning and execution. The findings suggest that in PD patients occur both compensatory mechanisms and loss of efficiency and provide further insight into the pathophysiological role of distinct cortical and subcortical areas in motor dysfunction. © 2013 Caproni et al.
Compagnone G.,Servizio di Fisica Sanitaria |
Angelini P.,Servizio Sanita Pubblica |
Domenichelli S.,Servizio di Fisica Sanitaria |
Califano G.,Servizio di Fisica Sanitaria
Radiologia Medica | Year: 2010
Purpose. This paper illustrates the annual trends in medical radiation exposure due to conventional radiography (CR), computed tomography (CT) and nuclear medicine (NM) procedures of the Emilia-Romagna population from 2001 to 2006 Materials and methods. We gathered information about the type, number and mean doses of CR, CT, and NM examinations performed in 17 hospitals of the Emilia-Romagna region. In particular, numerical values of the following dosimetric parameters were requested: entrance skin dose for CR, CT dose index and dose-length product for CT and activity administered for NM. Lastly, the annual collective dose S and annual average per-caput dose were calculated. Results. The 13 diagnostic imaging procedures that were the greatest contributors to the Emilia-Romagna population dose between 2001 and 2006 were identified and, for the year 2006, their percentage contribution to total procedures and population dose are indicated. CR, CT and NM accounted for 12%, 78% and 10% of the dose, and 83%, 15% and 2% of total procedures, respectively. The annual trends of S and average per capita dose are shown, and the theory underlying the use of these parameters is briefly discussed. Conclusions. This type of study relies heavily on the analysis of field data and as such, the growing attention paid in recent years to procedure optimisation should continue, and expand even for the justification of the procedures themselves as justification has a significant impact on the reduction of S and per-caput doses. © Springer-Verlag 2010.
Ghetti C.,Servizio di Fisica Sanitaria
Journal of applied clinical medical physics / American College of Medical Physics | Year: 2013
Recently a new iterative reconstruction algorithm named Iterative Reconstruction (SAFIRE) has been released by Siemens. This algorithm works in the raw data domain with noise reduction as main purpose, providing five different strengths. In this study, the effect of SAFIRE on image quality has been investigated using selected phantoms and a comparison with standard filtered back projection (FBP) has been carried out. The following quantitative parameters have been evaluated: image noise, impact of different reconstruction kernels on noise reduction, noise power spectrum (NPS), contrast-to-noise ratio (CNR), spatial resolution, and linearity and accuracy of CT numbers. The influence of strengths on image quality parameters has also been examined. Results show that image noise reduction is independent of reconstruction kernel and strongly related to the strength of SAFIRE applied. The peak of NPS curve for SAFIRE reconstructions is shifted towards low frequencies; this effect is more marked at higher levels of strength. Contrast-to-noise ratio is always improved in SAFIRE reconstruction and increases with higher strength. At different dose levels SAFIRE preserves CT number accuracy, linearity, and spatial resolution, both in transversal and coronal planes. These results confirm that SAFIRE allows for image noise reduction with preserved image quality. First clinical data to validate this phantom analysis and confirm that commercially available iterative algorithms can play an effective role in dose containment.
PubMed | Servizio di Fisica Sanitaria and University of Pavia
Type: Journal Article | Journal: Radiation protection dosimetry | Year: 2015
Ionising radiation exposure of cells might induce the perturbation of cell functions and, in particular, the activation or inhibition of several important pathways. This perturbation can cause the deregulation of both intra- and extra-cellular signalling cascades (such as the inflammatory pathway) and alter not only the behaviour of directly exposed cells but also the neighbouring non-irradiated ones, through the so-called bystander effect. The aim of the present work was to investigate the complex nonlinear interactions between the inflammatory pathway and other strictly interlaced signalling pathways, such as Erk1/2 and Akt/PKB, focusing on the radiation-induced perturbation of such pathways in the dose range of 0-2 Gy. The results show how radiation affects these interconnected pathways and how confounding factors, such as the change of culture medium, can hide radiation-induced perturbations.