Science Fisica Sanitaria

Genova, Italy

Science Fisica Sanitaria

Genova, Italy
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Schiapparelli P.,Science Fisica Sanitaria | Zefiro D.,Science Fisica Sanitaria | Massone F.,Science Fisica Sanitaria | Taccini G.,Science Fisica Sanitaria | Taccini G.,Italian National Cancer Institute
Medical Physics | Year: 2010

Purpose: The aim of this work is to present an updated implementation of total skin electron therapy (TSET) using IAEA TRS-398 code of practice for absolute dosimetry and taking advantage of the use of radiochromic films. The optimization of quality control tests is also included. Methods: A Varian 2100 C/D linear accelerator equipped with the special procedure HDTSe- (high dose rate total skin electron mode, E=6 MeV) was employed to perform TSET irradiations using the modified Stanford technique. The commissioning was performed following the AAPM report 23 recommendations. In particular, for dual-field beams irradiation, the optimal tilt angle was investigated and the dose distribution in the treatment plane was measured. For a complete six dual-field beams irradiation, the treatment skin dose on the surface of a cylindrical phantom was evaluated by radiochromic films and the B factor which relates the single dual-field skin dose to the six dual-field skin dose was assessed. Since the TRS-398 reference conditions do not meet the requirements of TSET absolute dosimetry, GafChromic EBT films were also employed to check and validate the application of the protocol. Simplified procedures were studied to verify beam constancy in PMMA phantoms without the more difficult setup of total skin irradiation. Results: The optimized geometrical setup for dual-field beams was: Tilt angle=±19°, SSD=353 cm, and the beam degrader (200×100×1 cm3) placed at 320 cm from the source. As regards to dose homogeneity in the treatment plane, for dual-field beams irradiation, the mean relative dose value was 97%±5% (normalizing to 100% at the calibration point level). For six dual-field beams irradiation, the multiplication factor B was 2.63. In addition, beam quality, dose rate, and bremsstrahlung contribution were also suitable for TSET treatments. The TRS-398 code of practice was used for TSET dosimetry, as dose measurements performed by ionization chamber and radiochromic film agreed within 2.5%. Simplified quality control tests and baseline values were presented in order to check flatness, symmetry, and field size with radiochromic films and output and beam quality constancy with ionization chamber. Short-term reproducibility and MU linearity tests were also included. Conclusions: Commissioning parameters met the requirements of TSET treatments and the matching of AAPM guidelines with the IAEA code of practice was successful. Frequent beam performance controls can be easily performed through the presented quality assurance tests. Radiochromic dosimetry facilitated the TSET commissioning and played a major role to validate the application of TRS-398. © 2010 American Association of Physicists in Medicine.


Gianesin B.,University of Genoa | Gianesin B.,National Institute of Nuclear Physics, Italy | Zefiro D.,Science Fisica Sanitaria | Paparo F.,Science Radiodiagnostica | And 11 more authors.
Magnetic Resonance in Medicine | Year: 2015

Purpose A preliminary assessment of the MRI-compatibility of metallic object possibly embedded within the patient is required before conducting the MRI examination. The Magnetic Iron Detector (MID) is a highly sensitive susceptometer that uses a weak magnetic field to measure iron overload in the liver. MID might be used to perform a screening procedure for MRI by determining the ferromagnetic/conductive properties of embedded metallic objects. Methods The study was composed by: (i) definition of MID sensitivity threshold; (ii) application of MID in a procedure to characterize the ferromagnetic/conductive properties of metallic foreign objects in 958 patients scheduled for MID examination. Results The detection threshold for ferromagnetic objects was found to be the equivalent of a piece of wire of length 2 mm and gauge 0.8 mm2 and, representing purely conductive objects, an aluminum sheet of area 2 × 2 cm2. Of 958 patients, 165 had foreign bodies of unknown nature. MID was able to detect those with ferromagnetic and/or conducting properties based on fluctuations in the magnetic and eddy current signals versus control. Conclusion The high sensitivity of MID makes it suitable for assessing the ferromagnetic/conductive properties of metallic foreign objects embedded within the body of patients scheduled for MRI. Magn Reson Med 73:2030-2037, 2015. © 2014 Wiley Periodicals, Inc.


Gianaria E.,University of Turin | Gallio E.,Science Fisica Sanitaria
Proceedings - 23rd Euromicro International Conference on Parallel, Distributed, and Network-Based Processing, PDP 2015 | Year: 2015

Radiography is nowadays a common medical exam, used for diagnosing several diseases, but has the disadvantage of exposing people to a dose of radiation. For this reason, it is important to study methods for reducing such dose. In this paper we present a digital X-ray simulation tool that simulates a radiological exam on a virtual patient. The software builds a physically-realistic radiography in real-time thanks to GPGPU programming and CUDA technology. It aims to be used in radiological departments, for testing new dose reduction procedures and training health operators. We validated the software comparing the results with real radiographic images, and we tested it on different graphic cards obtaining running times that are 35 to 250 times faster than the corresponding CPU implementation. © 2015 IEEE.


Gallio E.,Science Fisica Sanitaria | Rampado O.,Science Fisica Sanitaria | Gianaria E.,University of Turin | Bianchi S.D.,University of Turin | Ropolo R.,Science Fisica Sanitaria
PLoS ONE | Year: 2015

Conventional radiology is performed by means of digital detectors, with various types of technology and different performance in terms of efficiency and image quality. Following the arrival of a new digital detector in a radiology department, all the staff involved should adapt the procedure parameters to the properties of the detector, in order to achieve an optimal result in terms of correct diagnostic information and minimum radiation risks for the patient. The aim of this study was to develop and validate a software capable of simulating a digital X-ray imaging system, using graphics processing unit computing. All radiological image components were implemented in this application: an X-ray tube with primary beam, a virtual patient, noise, scatter radiation, a grid and a digital detector. Three different digital detectors (two digital radiography and a computed radiography systems) were implemented. In order to validate the software, we carried out a quantitative comparison of geometrical and anthropomorphic phantom simulated images with those acquired. In terms of average pixel values, the maximum differences were below 15%, while the noise values were in agreement with a maximum difference of 20%. The relative trends of contrast to noise ratio versus beam energy and intensity were well simulated. Total calculation times were below 3 seconds for clinical images with pixel size of actual dimensions less than 0.2 mm. The application proved to be efficient and realistic. Short calculation times and the accuracy of the results obtained make this software a useful tool for training operators and dose optimisation studies.This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.


Rampado O.,Science Fisica Sanitaria | Bianchi S.D.,University of Turin | Peruzzo Cornetto A.,Science Fisica Sanitaria | Rossetti V.,Science Fisica Sanitaria | Ropolo R.,Science Fisica Sanitaria
Physica Medica | Year: 2014

Dental CT dose evaluations are commonly performed using thermoluminescent dosimeters (TLD) inside anthropomorphic phantoms. Radiochromic films with good sensitivity in the X-ray diagnostic field have recently been developed and are commercially available as GAFCHROMIC XR-QA. There are potential advantages in the use of radiochromic films such as a more comprehensive dosimetry thanks to the adjustable size of the film samples. The purpose of this study was to investigate the feasibility of using radiochromic films for dental CT dose evaluations. Film samples were cut with a width of 5. mm and a length of 25. mm (strips), the same size as the Alderson Rando anthropomorphic phantom holes used in this study. Dental CT dose measurements were performed using simultaneously both TLD and radiochromic strips in the same phantom sites. Two equipment types were considered for dental CT examinations: a 16 slice CT and a cone beam CT. Organ equivalent doses were then obtained averaging the measurements from the sites of the same organ and effective doses were calculated using ICRP 103 weighting factors. The entire procedure was repeated four times for each CT in order to compare also the repeatability of the two dosimeter types. A linear correlation was found between the absorbed dose evaluated with radiochromic films and with TLD, with slopes of 0.930 and 0.944 (correlation r> 0.99). The maximum difference between the two dosimeter's measurements was 25%, whereas the average difference was 7%. The measurement repeatability was comparable for the two dosimeters at cumulative doses above 15. mGy (estimated uncertainty at 1 sigma level of about 5%), whereas below this threshold radiochromic films show a greater dispersion of data, of about 10% at 1 sigma level. We obtained, using respectively Gafchromic and TLD measurements, effective dose values of 107. μSv and 117. μSv (i.e. difference of 8.6%) for the cone beam CT and of 523. μSv and 562. μSv (i.e. difference of 7%) for the multislice CT.This study demonstrates the feasibility of radiochromic films for dental CT dosimetry, pointing out a good agreement with the results obtained using TLD, with potential advantages and the chance of a more extensive dose investigation. © 2012 Associazione Italiana di Fisica Medicina.


PubMed | University of Turin and Science Fisica Sanitaria
Type: Journal Article | Journal: Physica medica : PM : an international journal devoted to the applications of physics to medicine and biology : official journal of the Italian Association of Biomedical Physics (AIFB) | Year: 2013

Dental CT dose evaluations are commonly performed using thermoluminescent dosimeters (TLD) inside anthropomorphic phantoms. Radiochromic films with good sensitivity in the X-ray diagnostic field have recently been developed and are commercially available as GAFCHROMIC XR-QA. There are potential advantages in the use of radiochromic films such as a more comprehensive dosimetry thanks to the adjustable size of the film samples. The purpose of this study was to investigate the feasibility of using radiochromic films for dental CT dose evaluations. Film samples were cut with a width of 5mm and a length of 25 mm (strips), the same size as the Alderson Rando anthropomorphic phantom holes used in this study. Dental CT dose measurements were performed using simultaneously both TLD and radiochromic strips in the same phantom sites. Two equipment types were considered for dental CT examinations: a 16 slice CT and a cone beam CT. Organ equivalent doses were then obtained averaging the measurements from the sites of the same organ and effective doses were calculated using ICRP 103 weighting factors. The entire procedure was repeated four times for each CT in order to compare also the repeatability of the two dosimeter types. A linear correlation was found between the absorbed dose evaluated with radiochromic films and with TLD, with slopes of 0.930 and 0.944 (correlation r>0.99). The maximum difference between the two dosimeters measurements was 25%, whereas the average difference was 7%. The measurement repeatability was comparable for the two dosimeters at cumulative doses above 15 mGy (estimated uncertainty at 1 sigma level of about 5%), whereas below this threshold radiochromic films show a greater dispersion of data, of about 10% at 1 sigma level. We obtained, using respectively Gafchromic and TLD measurements, effective dose values of 107 Sv and 117 Sv (i.e. difference of 8.6%) for the cone beam CT and of 523 Sv and 562 Sv (i.e. difference of 7%) for the multislice CT. This study demonstrates the feasibility of radiochromic films for dental CT dosimetry, pointing out a good agreement with the results obtained using TLD, with potential advantages and the chance of a more extensive dose investigation.


PubMed | University of Turin and Science Fisica Sanitaria
Type: Journal Article | Journal: PloS one | Year: 2015

Conventional radiology is performed by means of digital detectors, with various types of technology and different performance in terms of efficiency and image quality. Following the arrival of a new digital detector in a radiology department, all the staff involved should adapt the procedure parameters to the properties of the detector, in order to achieve an optimal result in terms of correct diagnostic information and minimum radiation risks for the patient. The aim of this study was to develop and validate a software capable of simulating a digital X-ray imaging system, using graphics processing unit computing. All radiological image components were implemented in this application: an X-ray tube with primary beam, a virtual patient, noise, scatter radiation, a grid and a digital detector. Three different digital detectors (two digital radiography and a computed radiography systems) were implemented. In order to validate the software, we carried out a quantitative comparison of geometrical and anthropomorphic phantom simulated images with those acquired. In terms of average pixel values, the maximum differences were below 15%, while the noise values were in agreement with a maximum difference of 20%. The relative trends of contrast to noise ratio versus beam energy and intensity were well simulated. Total calculation times were below 3 seconds for clinical images with pixel size of actual dimensions less than 0.2 mm. The application proved to be efficient and realistic. Short calculation times and the accuracy of the results obtained make this software a useful tool for training operators and dose optimisation studies.


Stecco A.,SCDU Radiologia | Pisani C.,SCDU Radioterapia | Quarta R.,SCDU Radiologia | Brambilla M.,Science Fisica Sanitaria | And 6 more authors.
Journal of Neuro-Oncology | Year: 2011

To analyse the role of MR diffusion-tensor imaging (DTI) and perfusion-weighted imaging (PWI) in characterising tumour boundaries in patients with glioblastoma multiforme. Seventeen patients with surgically treated WHO IV grade gliomas who were candidates for adjuvant chemo-radiotherapy were enrolled. Before (T0) and after radiation treatment (T1), they underwent DTI and PWI, and the apparent diffusion coefficient (ADC), fractional anisotropy (FA) and relative cerebral blood volume (rCBV) in the enhancing tumour, the hyperintense tissue adjacent to the enhancing tumour, and the normal-appearing white matter (NAWM) adjacent to the hyperintense areas were analysed. The enhancing tissue at T1 was retrospectively divided on the basis of whether or not it was also enhancing at T0. The controls were the corresponding contralateral areas, on which we normalized the rCBV values, calculating the rCBV ratio. In NAWM, we did not find any significant differences in FA, ADC or rCBV. In the hyperintense perilesional regions, FA was significantly lower and ADC significantly higher than in the unaffected contralateral tissue; there were no significant differences in the rCBV maps. The values of FA, ADC and rCBV in enhancing neoplastic tissue were all significantly different from those observed in the contralateral tissue. There was no significant difference in rCBV values between the areas enhancing at T0 and those not enhancing at T0 but enhancing at T1, which may indicate the neoplastic transformation of apparently normal brain tissue. DTI metrics identify ultrastructural changes in hyperintense perilesional areas, but these are not specific for neoplastic tissue. rCBV seemed to reflect an ultrastructural alteration that was not visible at T0, but became visible (as neoplastic progression) on conventional MR images at T1. These findings could help identify tissue at risk of tumour infiltration. © 2011 Springer Science+Business Media, LLC.


PubMed | Science Medicina Nucleare U, Science Fisica Sanitaria and Science Medicina Nucleare
Type: Journal Article | Journal: Physica medica : PM : an international journal devoted to the applications of physics to medicine and biology : official journal of the Italian Association of Biomedical Physics (AIFB) | Year: 2016

Radioembolization with 29 HCC patients were included in this study: 15 were treated with resin(mean injected activity 1.5GBq, range 0.8-2.7GBq) and 14 with glass microspheres (2.6GBq, range 1.3-4.1GBq). Average doses to tumours and normal liver tissues were calculated with AAPM, multi-compartmental MIRD and Voxel-based methods and consequently the BED values were obtained. Planar images were used for the AAPM method: Regardless of type of microspheres, both for tumours and normal liver tissues, no significant statistical differences were found between MIRD and Voxel for both doses and BED values. Conversely AAPM gave discordant results with respect to the other two methods (Mann-Whitney p-values0.01). For resin spheres the calculated tumour-to-normal tissue ratios on planar images were on average 14 times greater than those obtained on SPECT-CT images, while they were 4 times greater on glass. A linear correlation was observed between MIRD and Voxel BEDs.The AAPM method appears to be less precise for absorbed dose and BED estimation, while MIRD and voxel based dosimetry are more confident each other.


Belgrano M.,UCO di Radiologia | Bregant P.,Science Fisica Sanitaria | Djoguela M.F.,UCO di Radiologia | Toscano W.,UCO di Radiologia | And 2 more authors.
Radiologia Medica | Year: 2014

Purpose: This study was undertaken to compare the different acquisition protocols available in a last-generation multislice computed tomography scanner used for cardiovascular studies, with particular attention to dosimetric aspects. Materials and methods: Our study compared prospective and retrospective electrocardiographic-gating techniques for cardiac imaging. For each patient, we performed in vivo dose measurements, using Gafchromic film. We compared the effective dose values estimated from the experimental measurements and the dose data reported on the CT console. Image quality was also assessed. Results: Prospective acquisition allows for major dose savings compared to retrospective acquisition (mean effective dose, 4.5 mSv with prospective acquisition versus 27.5 mSv with retrospective acquisition). The agreement between the experimental and software-based dose estimates was excellent and showed below 10 % of variation of the measured dose. Conclusion: In patients with regular rhythm and a heart rate lower than 75 bpm, the prospective acquisition technique ensures adequate diagnostic results and allows for significant patient dose savings. © 2013 Italian Society of Medical Radiology.

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