Health Physics Unit

Manavalakurichi, India

Health Physics Unit

Manavalakurichi, India
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Soffientini C.D.,Polytechnic of Milan | De Bernardi E.,University of Milan Bicocca | Casati R.,Fondazione IRCCS Ca Granda Ospedale Maggiore Policlinico | Baselli G.,Polytechnic of Milan | And 2 more authors.
Medical physics | Year: 2017

PURPOSE: Design, realization, scan, and characterization of a phantom for PET Automatic Segmentation (PET-AS) assessment are presented. Radioactive zeolites immersed in a radioactive heterogeneous background simulate realistic wall-less lesions with known irregular shape and known homogeneous or heterogeneous internal activity.METHOD: Three different zeolite families were evaluated in terms of radioactive uptake homogeneity, necessary to define activity and contour ground truth. Heterogeneous lesions were simulated by the perfect matching of two portions of a broken zeolite, soaked in two different 18 F-FDG radioactive solutions. Heterogeneous backgrounds were obtained with tissue paper balls and sponge pieces immersed into radioactive solutions.RESULTS: Natural clinoptilolite proved to be the most suitable zeolite for the construction of artificial objects mimicking homogeneous and heterogeneous uptakes in 18 F-FDG PET lesions. Heterogeneous backgrounds showed a coefficient of variation equal to 269% and 443% of a uniform radioactive solution. Assembled phantom included eight lesions with volumes ranging from 1.86 to 7.24 ml and lesion to background contrasts ranging from 4.8:1 to 21.7:1.CONCLUSIONS: A novel phantom for the evaluation of PET-AS algorithms was developed. It is provided with both reference contours and activity ground truth, and it covers a wide range of volumes and lesion to background contrasts. The dataset is open to the community of PET-AS developers and utilizers. © 2016 American Association of Physicists in Medicine.

PubMed | Health Physics Unit, San Giovanni Calibita Hospital, FISMECO SRL, AOU Policlinico Modena and 9 more.
Type: Comparative Study | Journal: Journal of magnetic resonance imaging : JMRI | Year: 2016

To propose a magnetic resonance imaging (MRI) quality assurance procedure that can be used for multicenter comparison of different MR scanners for quantitative diffusion-weighted imaging (DWI).Twenty-six centers (35 MR scanners with field strengths: 1T, 1.5T, and 3T) were enrolled in the study. Two different DWI acquisition series (b-value ranges 0-1000 and 0-3000 s/mm(2) , respectively) were performed for each MR scanner. All DWI acquisitions were performed by using a cylindrical doped water phantom. Mean apparent diffusion coefficient (ADC) values as well as ADC values along each of the three main orthogonal directions of the diffusion gradients (x, y, and z) were calculated. Short-term repeatability of ADC measurement was evaluated for 26 MR scanners.A good agreement was found between the nominal and measured mean ADC over all the centers. More than 80% of mean ADC measurements were within 5% from the nominal value, and the highest deviation and overall standard deviation were 9.3% and 3.5%, respectively. Short-term repeatability of ADC measurement was found <2.5% for all MR scanners.A specific and widely accepted protocol for quality controls in DWI is still lacking. The DWI quality assurance protocol proposed in this study can be applied in order to assess the reliability of DWI-derived indices before tackling single- as well as multicenter studies.

Colagrande S.,University of Florence | Mazzoni L.N.,Health Physics Unit | Mazzoni E.,University of Florence | Pradella S.,University of Florence
Journal of Magnetic Resonance Imaging | Year: 2013

Purpose To prospectively evaluate the effect of gadoxetic acid (Gd-EOB-DTPA; Primovist, Bayer-Schering, Berlin, Germany) on quantitative diffusion-weighted imaging (DWI) using the Le Bihan IntraVoxel Incoherent Motion model and considering separately the following parameters: slow diffusion coefficient (D), fast diffusion coefficient (D*), perfusion fraction (PF), and apparent diffusion coefficient (ADC). Materials and Methods Twenty-four consecutive patients were submitted to the same magnetic resonance (MR)-DWI acquisition before and after gadoxetic acid administration. Patients were divided into four groups according to the time at which the DW sequence was repeated, then 5, 10, 15, 20 minutes after contrast agent administration. A total of 48 manually drawn regions of interest (ROIs) of about 1200 pixels were placed in the middle right liver lobe. The mean and standard deviation (SD) were calculated in each group/patient for every DWI-related parameter. Analysis of variance was performed (threshold P = 0.05). Bonferroni and Games-Howell post-hoc tests were applied if significant differences were found among groups; otherwise, data were averaged together. Results D, D*, PF, and ADC did not show any significant difference before and after contrast agent administration, at any time. Conclusion It is possible to perform DW acquisitions after gadoxetic acid administration without any significant variation of the values of DW-related parameters under consideration in this study. © 2013 Wiley Periodicals, Inc. Copyright © 2013 Wiley Periodicals, Inc.

PubMed | Health Physics Unit and Azienda Ospedaliero Universitaria Careggi
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

In this work we investigate the feasibility of employing a Channelized Hotelling model Observer (CHO) in a CT protocol optimization program with the aim at assuring that the scanners are working at their own best with regard to the quality of images and patient exposure. Although the benefit of using model observers in the clinical protocol optimization is evident, in the practice it is still to be investigated what are the pitfalls associated with this method. With this concern we focused on a clinical protocol for oncology of the abdomen. For the implementation of CHO, we designed a new phantom with the aim of minimizing the number of acquired images. After tuning the model according to a restricted data set, we applied it to the evaluation of a large data set of images obtained with different reconstruction algorithms and acquired on different scanners. Results were very encouraging about the usefulness of CHO for the mentioned purposes. For the first time, at our knowledge, the applicability of CHO was demonstrated for images reconstructed with both filtered back projection (FBP) and iterative (IR) algorithms on the same scanner as well as for images from different scanners, though produced by the same manufacturer. Instead it turned out that CHO was not applicable for the same purposes over images from another manufacturer.

Shanthi G.,Womens Christian College | Kumaran J.T.T.,NM Christian College | Raj G.A.G.,Scott Christian College | Maniyan C.G.,Health Physics Unit
Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment | Year: 2010

The study was carried out to evaluate the radioactivity concentration in the food crops grown in high-level natural radioactive area (HLNRA) in south west India. Food samples collected were analysed by means of a gamma spectroscopy and estimated annual dietary intakes of the radioisotopes 226Ra, 228Ra, 228Th and 40K. The annual intake of the food stuffs was estimated on the basis of their average annual consumption. Calculations were also made to determine the effective dose to an individual consuming such diets. The intakes of these radionuclides were calculated using the concentrations in south Indian foods and daily consumption rates of these foods. Daily intakes of these radionuclides were as follows: 226Ra, 0.001-1.87; 228Ra, 0.0023-1.26, 228Th, 0.01-14.09 40K, 0.46-49.39Bq/day. The daily internal dose resulting from ingestion of radionuclides in food was 4.92 μSv/day and the annual dose was 1.79 mSv/yr. The radionuclides with highest consumption is 40K. © 2009 Elsevier B.V. All rights reserved.

Meneghini R.,Health Physics Unit | Bagnara M.C.,Health Physics Unit
IFMBE Proceedings | Year: 2016

The estimation of committed effective dose from intakes of radionuclides for health workers is still a difficult task to assessors, due to the difficulties encountered in direct measuring and the choice of procedures to be used in calculating dose. We take into account the possible types of dosimetric measurements that should be used for the task, based on radionuclides handled by health workers and related to the expected dose. For the procedures to be used in calculating committed dose we propose the IAEA-IDEAS guidelines (“IDEAS general guidelines for the estimation of committed dose from incorporation monitoring data”, that are intended to be consistent with ICRP recommendations and guidance: they relate, where appropriate, to the currently recommended ICRP biokinetic and dosimetric models, as applied in ICRP Publications 68 and 78. These guidelines seem to be a good compromise between simplicity of use and evaluation precision, with respect to risk levels. The overall aims of the Guidelines can be summarised as: Harmonisation: by following the Guidelines any two assessors should obtain the same estimate of dose from a given data set Optimisation: the “best” estimate of dose should be obtained from the available data. Proportionality: the effort applied to the evaluation should be proportionate to the dose – the lower the dose, the simpler the process should be. Results: An analysis of suitable monitoring methods has been undertaken; also, a database of useful dosimetric and bio kinetic data for some of the most used unsealed radionuclides (health workers) has been collected, which therefore needs to be improved. Finally, the proposed procedures for dose evaluation are displayed in a flow chart approach. The aim is to offer a well-defined and useful working tool, which could be widely applicable in practical radio protection for health workers, seeking for harmonisation and optimisation. This tool should leads to the best dose assessment from a monitoring dataset, according to international standards, with accuracy level related to estimated risk. However, it is well-known that in real life great difficulties are encountered for health workers dose assessments, related to short radionuclide half-lives and to the poor measuring resources generally available in health physics laboratories. Therefore, a national working group has been started, with the aim to confront and face with these problems. © International Federation for Medical and Biological Engineering 2007.

Shanthi G.,Womens Christian College | Thampi Thanka Kumaran J.,NM Christian College | Allen Gnana Raj G.,Scott Christian College | Maniyan C.G.,Health Physics Unit
Radiation Protection Dosimetry | Year: 2010

The concentration of natural radionuclides (. 226Ra, . 232Th and . 40K) in the soil samples were determined for 28 locations in Kanyakumari district of southwest India by means of gamma spectroscopy with NaI (Tl) detector. The mean activity concentrations for . 232Th and . 40K are greater than the world average values reported by United Nations Scientific Committee on Effects of Atomic Radiation for areas of normal background radiation. Radiological indices were estimated for the radiation of the natural radioactivity of all soil samples. Estimated mean total absorbed dose in air from activity concentration of . 226Ra, . 232Th and . 40K in high background radiation areas (HBRAs) is 200 ± 30 nGy h. -1 and in low background radiation areas (LBRAs) is 29 ± 14 nGy h. -1. Annual outdoor effective dose was also calculated for HBRA and LBRA. Also the representative level index, which resulted from the natural radionuclides in the soil samples were also estimated and given. © The Author 2010. Published by Oxford University Press. All rights reserved.

Shanthi G.,Womens Christian College | Thampi Thanka kumaran J.,NM Christian College | Allen Gnana raj G.,Scott Christian College | Maniyan C.G.,Health Physics Unit
Radiation Protection Dosimetry | Year: 2012

It is necessary to obtain the transfer factor (TF) of long-lived radionuclides because soil type and vegetation can affect TF. We studied the food crops commonly consumed by the general public of Kanyakumari district of south India. The main focus was on rice, fruits, vegetables and tapioca because the consumption of these is high. The soil to rice TF for the radionuclides, 226Ra, 232Th, 238U and 40 K are 8.8×10. -2, 14.2×10. -2, 5.8×10. -2 and 6.3×10. -2, respectively. The TF of tapioca for 226Ra, 232Th, 238U and 40 K are 6.2×10 -2, 11×10 -2, 1.9×10 -2 and 8.9×10 -2, respectively. For fruits and vegetables, the TFs are low. In the majority of the crops the non-edible parts accumulate more radionuclides than the edible parts. © The Author 2011. Published by Oxford University Press. All rights reserved.

Cook M.,Health Physics Unit | Kleinschmidt R.,Health Physics Unit
Australian Journal of Chemistry | Year: 2011

Radium is a naturally occurring alkaline earth metal that is present in soils, water, plants, and foods in low concentrations. In the analysis of radium in trace amounts, co-precipitation is the favoured way of separating an element from its matrix. In this case, radium is co-precipitated with barium. The purity and yield of the extraction is controlled by adsorption onto the barium sulfate precipitate and pH manipulation controls the solubility of certain products. This technique enables the removal of interfering lead-210 to yield a purified radium source for analysis, which is done using liquid scintillation spectrometry. The analytical results of spiked water samples are in good agreement with the known activities of radium-226 and radium-228 standard reference materials. Minimum detectable limits for radium-226 and radium-228 are calculated to be 0.01 and 0.06BqL -1, respectively. The method provides a fast, reliable, and accurate alternative to traditional radium isotope analysis based on α and gamma spectrometry. © 2011 CSIRO.

Mazzoni L.N.,Health Physics Unit | Lucarini S.,Azienda Ospedaliero Universitaria | Chiti S.,Azienda Ospedaliero Universitaria | Busoni S.,Health Physics Unit | And 2 more authors.
Journal of Magnetic Resonance Imaging | Year: 2014

Purpose To evaluate the dependence on the b-values adopted of apparent diffusion coefficient (ADC), perfusion fraction (PF), slow and fast diffusion coefficient (Dslow, Dfast), corrected diffusion coefficient (D) and kurtosis (K), in healthy peripheral (HP) and peripheral cancerous (PCa) prostate tissues. Materials and Methods Patients who underwent multiparametric prostate MR examination were retrospectively evaluated for possible inclusion. ADC, PF, Dslow, Dfast, D, and K were estimated both in HP and PCa tissues, using three different ranges of b-values: 0-2300, 0-1800, 0-800 s/mm2 (group A, B and C, respectively). Analysis of variance (ANOVA) and receiver operating characteristic (ROC) analysis were performed, to establish differences among groups and to evaluate sensitivity and specificity of every parameter in distinguishing HP and PCa tissues when calculated with different b-values. Results In all, 57 patients were included. ANOVA showed significant differences of all parameters between group A-B vs. C, both in HP and PCa tissues. In ROC analysis K showed the best area under the curve (AUC) when calculated in groups A and B (0.87 and 0.86), while it was comparable with the ADC one in group C (both 0.82). Conclusion A significant dependence on the adopted b-values of DWI parameters is shown. The best performance in distinguishing HP from PCa tissues was obtained by K, calculated using a high b-value sequence. J. Magn. Reson. Imaging 2014;39:512-518. © 2013 Wiley Periodicals, Inc. Copyright © 2013 Wiley Periodicals, Inc.

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