Phenol compounds as new materials for electron spin resonance dosimetry in radiotherapy

Phenol compounds as new materials for electron spin resonance dosimetry in radiotherapy

Introduction: Among the various dosimetric techniques used for characterizing the radiation beams used in radiation therapy, the electron spin resonance (ESR) arouses increasing interest for applications in various therapy procedures. Free radicals are known to be produced when a compound is irradiated with ionizing radiations. The concentration of radiationinduced free radicals is proportional to the absorbed dose and this allows for dosimetric measurements through ESR technique which enables to quantitatively determine the radical concentration. In this work we report the ESR investigation of phenol pellets and thin films exposed to various types of radiation beams (clinical photon and el…

Dosimetric verification of stereotactic head treatments performed with Helical Tomotherapy using alanine dosimeters and gafchromic films

Impact of combination chemotherapy on toxicity in ovarian cancer: Systematic revision of literature and meta-analysis

The purpose of this statistical analysis is to demonstrate the real advantages in terms of cost-benefit of combination chemotherapy compared with single-agent chemotherapy. The trials, which are used in this meta-analysis, have been searched on PubMed database and they are phase II or randomized phase III studies with only chemotherapy regimens. In this meta-analysis were evaluated adverse effects with odds ratio (OR), which is expressed in 95% confidence intervals (95% CI). Only 4 studies contained all the set selection criteria and they were selected. The data, which were obtained, were analyzed using MedCalc Application. The combination therapy was more strongly linked to certain adverse…

Moving across the static magnetic field of a 1.5 T MRI scanner: Analysing compliance with Directive 2013/35/EU

Abstract Does the exposure of magnetic resonance imaging personnel to static magnetic fields fully comply with Directive 2013/35/EU? Despite the obligation to satisfy this question, a general answer cannot be provided, nor are final satisfying good practices methods for exposure assessment currently available. In order to contribute to fix this problem, three different 1.5 T scanners are analysed and – by a new theoretical insight – a positive answer is provided.

Correlation between ferrous ammonium sulfate concentration, sensitivity and stability of Fricke gel dosimeters exposed to clinical X-ray beams

Abstract This work describes the characterization of various Fricke-Agarose-Xylenol gels (FXG) dosimeters using NMR relaxometry and MRI analysis. Using X-rays from a clinical linear accelerator (LINAC), the gels were irradiated in the dose range from 0 Gy to 20 Gy. The photon sensitivity of the FXGs was measured in terms of NMR relaxation rates; its dependence on radiation dose was determined as a function of ferrous ammonium sulfate contents (from 0.5 mM to 5 mM). Furthermore, the stability of the NMR signal was monitored over several days after irradiation. These measurements were aided by Magnetic Resonance Imaging (MRI) scans which allowed three-dimensional (3D) dose mapping. In order t…

The response behaviour of LiF:Mg,Cu,P thermoluminescence dosimeters to high-energy electron beams used in radiotherapy

To ensure the effectiveness of radiation-therapy treatments, both in-phantom and in-patient reliable dose measurements are required. Thermoluminescence dosimeters are used commonly for both applications. Among the various available materials, the relatively new LiF:Mg,Cu,P phosphor is a suitable candidate for quality control of in vivo dosimetry in electron-beam therapy. The response behaviour of LiF:Mg,Cu,P chips to 6-21 MeV electron beams used in radiotherapy was studied. Batch homogeneity, dose linearity, sensitivity change after use, dose and dose-rate response, energy dependence and fading characteristics were investigated. The contribution from each factor to the overall uncertainty i…

Response charactterization of ammonium tartrate solid state pellets for ESR dosimetry with radiotherapeutic photon and electron beams.

Solid state pellets (1 mm thick) for electron spin resonance (ESR) dosimetry were made using ammonium tartrate as the radiation-sensitive substance. Their behaviour was experimentally investigated as a function of dose with 60Co gamma rays. The calibration function obtained permits measurements of absorbed dose in the 2-50 Gy range, with a combined uncertainty of +/-4%. The lowest detectable dose was about 0.5 Gy. These properties are comparable with or even better than those of ESR dosimeters made from other materials. The time stability of the ESR signal of ammonium tartrate dosimeters at different storage conditions after irradiation was studied. A rather complex behaviour was observed, …

REVISITING ANTHROPOZOONOSES IN THE MEDITERRANEAN BASIN. A SINGLE-CENTRE PERSPECTIVE. A SOUTHERN ITALIAN EXPERIENCE

Zoonoses, often better defined with the term anthropozoonoses, are diseases that can be transmitted to humans either by direct contact with animals or through arthropod vector intervention. Microbial interaction between humans and animals constitutes an important public health challenge, particularly in the Mediterranean basin. The main reasons this challenge is still relevant today include the phenomenon of migration, of both humans and animals, and climate change, which tend to alter the geographical distribution of zoonosis or the zoonotic agent, as well as the distribution range of potential vectors. The Mediterranean area seems to be affected by plentiful and widely distributed zoonose…

Misure preliminari su scanner MRI 7T di stabilità nel tempo di Dosimetri gel di tipo Fricke

L’ottimizzazione delle procedure che utilizzano radiazioni ionizzanti in campo medico costituisce un elemento chiave per la sicurezza del paziente e l’esito dei trattamenti radioterapici. In particolare è fondamentale arrecare il minor danno possibile ai tessuti sani circostanti la neoplasia da trattare (Attix, 2004). La misurazione precisa della dose somministrata nei tessuti e la sua mappatura in tre dimensioni sono di fondamentale importanza in termini di riuscita e di pianificazione dei trattamenti radioterapici (Khan, 2009). In questo lavoro sono presentate le misure preliminari effettuate per testare la stabilità temporale di dosimetri gel di tipo Fricke tramite scanner pre-clinico 7T…

Tungiasis: A report of four new cases and a review of imported cases in Italy in the last thirty years

NUCLEAR MAGNETIC RESONANCE RELAXOMETRY AND IMAGING FOR DOSIMETRY WITH AGAROSE FRICKE GEL

Introduction: Fricke Xylenol Gel (FXG) dosimetric system is based on the radiation induced oxidation of ferrous to ferric ions. In this kind of gels it can occur that ferrous and ferric ions diffuse in the gel matrix. To preserve the spatial distribution of the dose from diffusion, Fricke gels must be undergoing measurement within a few hours of their irradiation. Thus, the spatial integrity of the dose distribution in the Fricke gel is maintained. The oxidation of ferrous ions also causes a reduction of the longitudinal nuclear magnetic relaxation time which can be measured by means of nuclear magnetic resonance (NMR) instrumentation. In this work we performed NMR relaxometry and MR imagin…

Nuclear magnetic resonance relaxometry and imaging for dosimetry with agarose Fricke gel

Accomplishing the requirements within the new decree 159/2016: Comparative study of eddy currents induced in a human phantom moving near different MRI scanners

Purpose. In order to provide adequate risk-reducing procedures for MRI personnel (radiographers, anaesthetists, physicists, nurses, technicians, cleaners, etc.), different studies have been developed in the past years. Further to those, in the present work risk assessment concerned with currents induced by non-uniform static magnetic fields in MRI operators performing different tasks in prox imity of the scanner has been investigated across a set of different 1.5 T MRI scanners. Methods. The first step has been to empirically map the magnetic field around the different scanners and to select a proper adult human body as a heterogeneous volume conductor model. Then, upon observing the way ta…

Thermoluminescence response of sodalime glass irradiated with photon and electron beams in the 1-20 Gy range

Abstract The thermoluminescence response of a watch commercial glass was studied after irradiation with photons and electrons, in the range 1–20 Gy, of interest in accidental dosimetry; a linear response was obtained with both beams. This result, together with the satisfactory time stability of the thermoluminescence signal, indicates this glass as a potential material for retrospective dosimetry applications.

NOR regions of polychaete worms of the genus Ophryotrocha studied by chromosome banding techniques and FISH.

This article reports the results of cytogenetic analyses carried out on 10 species of polychaete worms belonging to the genus Ophryotrocha (Dorvilleidae). Nucleolar organizer regions (NORs) were characterized by Ag staining, C-banding, CMA3 staining, and ribosomal fluorescent in situ hybridization (rDNA FISH). Extensive intraspecific variation in NOR number and distribution were observed in O. costlowi, O. sp. macrovifera, O. notoglandulata, O.l. labronica, O. l. pacifica (2n = 6), O. p. puerilis, O. diadema (2n = 8), O. hartmanni, O. gracilis (2n = 10). In O. sp. robusta (2n = 10), Ag-NORs were always located on a single chromosome pair. CMA3 staining suggests a possible trend toward a GC-…

INTELLECTUAL DISABILITY, EPILEPSY AND MILD DYSMORPHISMS DUE 22q11.2 DISTAL DUPLICATION: CLINICAL AND MOLECULAR CHARACTERIZATION OF A 0.5 Mb MINIMAL CRITICAL REGION

INTELLECTUAL DISABILITY, EPILEPSY, MILD DYSMORPHISMS, 22q11.2 DISTAL DUPLICATION

34. Accomplishing the requirements within the new decree 159/2016: Comparative study of eddy currents induced in a human phantom moving near different MRI scanners

Purpose In order to provide adequate risk-reducing procedures for MRI personnel (radiographers, anaesthetists, physicists, nurses, technicians, cleaners, etc.), different studies have been developed in the past years. Further to those, in the present work risk assessment concerned with currents induced by non-uniform static magnetic fields in MRI operators performing different tasks in proximity of the scanner has been investigated across a set of different 1.5 T MRI scanners. Methods The first step has been to empirically map the magnetic field around the different scanners and to select a proper adult human body as a heterogeneous volume conductor model. Then, upon observing the way tasks…

Moving inside a MRI room: A risk assessment analysis

Moving across the stray magnetic field generated by a medical magnetic resonance imaging system may induce electric stimulation near or even beyond the threshold of physiological significance and adequate risk-reducing procedures for the involved personnel may be re quired. With this in mind, a set of different scanners has been analysed. Results suggest that a 1.5 T magnet may be expected in general to comply with the requirements of the currently in force European Electromagnetic Fields Directive for ensuring the health and safety of workers.

ALANINE/ESR DOSIMETRY FOR TOTAL BODY IRRADIATION USING AN ANTHROPOMORPHIC PHANTOM

Introduction: Total Body Irradiation (TBI) is a technique widely used in the radiation blood-oncology in the treatment of patients that need bone marrow transplantation or peripheral stem cell transplantation. This technique has some limitations such as the lack of homogeneity of the dose distribution (which may show variations of 20% in the different areas), irradiation of critical organs such as the lungs, the liver, the intestine and the eye-lens which can receive a dose comparable to that nominal and require appropriate shielding and a proper evaluation of the dose absorbed by them. The positive outcome of this type of radiation therapy is strictly related to a precise and accurate meas…

PVA-GTA Fricke gel dosimeters exposed to clinical photons beams: Nuclear Magnetic Resonance Relaxometry and Imaging

Fricke Gel (FXGs) dosimetric system is based on the radiation induced oxidation of ferrous to ferric ions. The application of Fricke gels for ionizing radiation dosimetry is continuously increasing worldwide due to their many favorable properties. However, one of their shortcomings is that ferrous and ferric ions diffuse in the gel matrix. To maintain the spatial integrity of the dose distribution, Fricke gels must be undergoing measurement within a few hours of their irradiation, so that ferric ions remain close to their point of production. Thus, the spatial integrity of the dose distribution in the Fricke gel is maintained (Schreiner, 2015). The gel matrix also contributes to the oxidati…