Browsing by Author "Ria, F"

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    Adaptability index: quantifying CT tube current modulation performance from dose and quality informatics
    (2017-03-17) Ria, F; Wilson, JM; Zhang, Y; Samei, E
    The balance between risk and benefit in modern CT scanners is governed by the automatic adaptation mechanisms that adjust x-ray flux for accommodating patient size to achieve certain image noise values. The effectiveness of this adaptation is an important aspect of CT performance and should ideally be characterized in the context of real patient cases. Objective of this study was to characterize CT performance with an index that includes image-noise and radiation dose across a clinical patient population. The study included 1526 examinations performed by three scanners, from two vendors, used for two clinical protocols (abdominopelvic and chest). The dose-patient size and noise-patient size dependencies were linearized, and a 3D-fit was performed for each protocol and each scanner with a planar function. In the fit residual plots the Root Mean Square Error (RMSE) values were estimated as a metric of CT adaptability across the patient population. The RMSE values were between 0.0344 HU1/2 and 0.0215 HU1/2: different scanners offer varying degrees of reproducibility of noise and dose across the population. This analysis could be performed with phantoms, but phantom data would only provide information concerning specific exposure parameters for a scan: instead, a general population comparison is a way to obtain new information related to the relevant clinical adaptability of scanner models. A theoretical relationship between image noise, CTDIvol and patient size was determined based on real patient data. This relationship may provide a new index related to the scanners' adaptability concerning image quality and radiation dose across a patient population. © (2017) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
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    Awareness of medical radiation exposure among patients: A patient survey as a first step for effective communication of ionizing radiation risks
    (Physica Medica, 2017-11) Ria, F; Bergantin, A; Vai, A; Bonfanti, P; Martinotti, AS; Redaelli, I; Invernizzi, M; Pedrinelli, G; Bernini, G; Papa, S; Samei, E
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    Comparative Assessment of the Absorbed Doses Resulted from Occupational Exposure and Computed Tomography
    (MEDICAL RADIOLOGY AND RADIATION SAFETY, 2023-02) Osipov, MV; Ria, F; Druzhinina, PS; Sokolnikov, ME
    A comparative assessment of the absorbed doses resulted from computed tomography (CT) examinations, and the dose resulted from occupational external gamma exposure of the “Mayak” workers was carried out. The patients’ diagnostic radiation dose was reconstructed using Monte-Carlo simulation on a population of 58 virtual adult phantoms across 13 CT protocol categories. Archival records of CT examinations of patients were used for the dose reconstruction. Information on technical parameters of scanning was extracted from DICOM files. The study sample has been linked to the Mayak worker register database to identify persons who had professional contact with ionizing radiation. Annual occupational dose records for the Mayak workers were obtained from the Dose-2013 dosimetry system. In this study, information on 212 patients was collected from 303 records. Among them, 42 Mayak employees were identified, including 24 persons who had non-zero dose of external gamma radiation, and 16 persons with internal alpha radiation dose due to occupational intake of 239Pu. Individual doses absorbed in the organs resulted from exposure to computed tomography and occupational activities has been compared. The results showed significant variability of the absorbed organ dose depending on the area of CT examination. The brain and lens were subjected to the highest radiation exposure during head CT. The average absorbed dose in brain was 24.5 mGy per single examination (the maximum brain dose accumulated over the entire study period was 82.3 mGy), and 27.7 mGy for the lens of the eye (the maximum lens dose reached 92.9 mGy). Relevant comparison of the absorbed dose of diagnostic and occupational exposure, accumulated during one year, has been performed. The average estimate of cumulative radiation dose absorbed in the organs during computed tomography was an order of magnitude lower than the one from occupational external gamma exposure of Mayak personnel, except brain dose. Annual CT dose equivalent of external gamma radiation was 2.82.
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    Comparing two different noise magnitude estimation methods in CT using virtual imaging trials
    (Medical Imaging 2022: Physics of Medical Imaging, 2022-04-04) Ria, F; Jadick, GL; Abadi, E; Solomon, JB; Samei, E
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    CT Scan Dosimetric Parameters Routine Monitoring: First Results of Radiation Dose Optimization Strategies Promptly Provided by a Multidisciplinary Team
    (2015-11-29) Ria, F; Bergantin, A; Redaelli, I; Invernizzi, M; Vai, A; Fazzini, D; Gozzi, G; Papa, S
    CONCLUSION Radiation dose reduction, while saving image quality could be easily implemented with this approach. Furthermore, the availability of a dosimetric data archive provides immediate feedbacks, related to the implemented optimization strategies. Background JCI Standards and European Legislation (EURATOM 59/2013) require the implementation of patient radiation protection programs in diagnostic radiology. Aim of this study is to demonstrate the possibility to reduce patients radiation exposure without decreasing image quality, through a multidisciplinary team (MT), which analyzes dosimetric data of diagnostic examinations. Evaluation Data from CT examinations performed with two different scanners (Siemens DefinitionTM and GE LightSpeed UltraTM) between November and December 2013 are considered. CT scanners are configured to automatically send images to DoseWatch© software, which is able to store output parameters (e.g. kVp, mAs, pitch ) and exposure data (e.g. CTDIvol, DLP, SSDE). Data are analyzed and discussed by a MT composed by Medical Physicists and Radiologists, to identify protocols which show critical dosimetric values, then suggest possible improvement actions to be implemented. Furthermore, the large amount of data available allows to monitor diagnostic protocols currently in use and to identify different statistic populations for each of them. Discussion We identified critical values of average CTDIvol for head and facial bones examinations (respectively 61.8 mGy, 151 scans; 61.6 mGy, 72 scans), performed with the GE LightSpeed CTTM. Statistic analysis allowed us to identify the presence of two different populations for head scan, one of which was only 10% of the total number of scans and corresponded to lower exposure values. The MT adopted this protocol as standard. Moreover, the constant output parameters monitoring allowed us to identify unusual values in facial bones exams, due to changes during maintenance service, which the team promptly suggested to correct. This resulted in a substantial dose saving in CTDIvol average values of approximately 15% and 50% for head and facial bones exams, respectively. Diagnostic image quality was deemed suitable for clinical use by radiologists.
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    Study to Define Frequency in Routine Analytical Controls in the Radiolabelling Process
    (OALib, 2017) Ria, F; Albini, G; Battista, S; Salvatore, V; Messere, R; Gandolfo, P; Armonino, R; Papa, S
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    Study to Define Frequency in Routine Analytical Controls in the Radiolabelling Process
    (OALib, 2017) Ria, F; Albini, G; Battista, S; Salvatore, V; Messere, R; Bergantin, A; Redaelli, I; Bonfanti, P; Martinotti, AS; Gandolfo, P; Papa, S