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La Radioterapia IntraOperatoria (IORT) È una modalità di trattamento in cui una singola dose di radiazioni è impartita direttamente al letto tumorale o al tumore durante l'intervento chirurgico, evitando di colpire i tessuti sani circostanti. Nel caso di irraggiamento alla mammella, una singola frazione di 21 Gy impartita al volume neoplastico durante la procedura chirurgica è equivalente ad una dose totale di 60 Gy che solitamente viene somministrata con la radioterapia frazionata. Questo lavoro riporta il confronto tra la risposta ESR di dosimetri di alanina e di camere a ionizzazione Markus per le misurazioni degli Output Factor (OF) di fasci di elettroni prodotti da un acceleratore lineare utilizzato per la IORT. Il confronto è stato completato dai calcoli Monte Carlo degli OFs determinati con il software di simulazione GEANT4 ed utilizzando l'applicazione dedicata alla IORT che consente di ottenere informazioni dettagliate sulla distribuzione di dose.

Among the various dosimetric techniques used for characterizing the radiation beams used in radiation therapy, the Electron Paramagnetic Resonance (EPR) arouses increasing interest for applications in various therapy procedures. When a compound is irradiated with ionizing radiations free radicals are produced and their concentration is proportional to the absorbed dose. This allows for dosi-metric measurements through EPR technique which is able to quantitatively de-termine the radical concentration. Our research group has started an investigation of the EPR response of some phenols compounds for possible dosimetric applications. In this work we report the EPR investigation of IRGANOX 1076 pellets and thin films exposed to various type of radiation beams. Phenols are compounds possessing a benzene ring attached to a OH group. After irradiation the final product is a stable phenoxy radical. The stability of such radi-cal can be improved by adding other alkyl chains which can be attached to the benzene ring. In particular, the phenol octadecyl3(3,5ditertbutyl4hydroxyphenyl) propionate (IRGANOX 1076) gave interesting results.

In questo lavoro sono presentate le misure effettuate tramite rilassometria NMR su campioni costituiti da una matrice gelatinosa drogata con ioni ferrosi comunemente chiamati dosimetri gel di tipo Fricke (FXG). La dosimetria con gel Fricke si basa sulla ossidazione degli ioni ferrosi (Fe2+) in ioni ferrici (Fe3+) all’interno di una matrice gelatinosa a seguito di irraggiamento (Schreiner, 2004). Tale processo è fortemente dipendente dalla dose somministrata (Marrale, 2014a). I dosimetri di Fricke sono tessuto-equivalenti, rispondono ad ogni tipo di radiazione ionizzante ed, assumendo la forma del contenitore in cui avviene la gelificazione, possono essere utilizzati per studiare l’effetto delle radiazioni su fantocci antropomorfi da essi costituiti. Inoltre, la matrice di gel rallenta la diffusione degli ioni ferrosi (Fe2+) e ferrici (Fe3+) in modo che, se il gel viene analizzato entro un paio di ore dall’irraggiamento, gli ioni ferrici rimangono prossimi al loro punto di produzione. Inoltre, il gel favorisce l’ossidazione degli ioni ferrosi durante l'irraggiamento, in modo da aumentare la resa chimica degli ioni ferrici e quindi la sensibilità dei dosimetri. Lo scopo di questo lavoro è l'analisi tramite risonanza magnetica nucleare (NMR) delle proprietà di rilassamento protonico dei gel dosimetrici da noi preparati al variare della concentrazione dei centri paramagnetici (Fe3+) prodotti al variare della dose di irraggiamento. I gel Fricke sono stati irradiati con fasci di fotoni (LINAC) nel range clinico tra 0 e 20 Gy. Le analisi NMR sono state affiancate da acquisizioni di imaging a Risonanza Magnetica Nucleare (MRI) utilizzata in ambito ospedaliero (Galante, 2008). Per valutare la sensibilità a fotoni, abbiamo studiato la dipendenza dei tempi di rilassamento nucleari dalla dose, dalla concentrazione di solfato di ammonio ferroso contenuto all’interno dei gel e dalla presenza di indicatori ottici degli ioni metallici. Inoltre, è stata monitorata la stabilità del segnale per diversi giorni dopo l'irraggiamento. Le acquisizioni MRI sono state finalizzate alla mappatura 3D della dose su fantocci estesi. Vengono presentati e discussi i risultati ottenuti in relazione ad applicazioni dei dosimetri gel Fricke in ambito radioterapico. Questo lavoro evidenzia come valutazioni dosimetriche non possono prescindere dall’ottimizzazione della concentrazione degli additivi.

La RadioTerapia IntraOperatoria (IORT) è una modalità di trattamento in cui una singola dose di radiazioni è impartita direttamente al letto tumorale o al tumore durante l'intervento chirurgico, evitando di colpire i tessuti sani circostanti. La fabbricazione di acceleratori lineari mobili per elettroni dedicati alla IORT ha permesso una grande diffusione di questa tecnica radioterapica. Lo scopo di questo lavoro è il confronto tra la risposta di dosimetri di alanina letti tramite Risonanza Elettronica di Spin (ESR) e di camere a ionizzazione Markus per le misurazioni degli Output Factors (OFs) di fasci di elettroni prodotti da un acceleratore lineare utilizzato per la IORT. Gli OFs dei fasci di elettroni convenzionali ad alta energia sono normalmente misurati utilizzando camera di ionizzazione secondo protocolli dosimetrici internazionali. Tuttavia, i fasci elettronici utilizzati in IORT presentano caratteristiche quali (quali impulso di dose, spettro energetico e distribuzione angolare molto diversa dai fasci solitamente utilizzate in radioterapia esterna), per cui l'applicazione diretta di protocolli dosimetrici internazionali può introdurre ulteriori incertezze dosimetriche. Gli OFs ottenuti mediante dosimetri di alanina letti tramite ESR sono stati confrontati con quelli ottenuti con camere a ionizzazione di tipo Markus. Il confronto è stato completato da simulazioni Monte Carlo utilizzando l’applicazione dedicata alla IORT di Geant4 che consente di ottenere informazioni dettagliate sulla distribuzione di dose.

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 [1]. Free radicals are known to be produced when a compound is irradiated with ionizing radiations. The concentration of radiation-induced free radicals is proportional to the absorbed dos e and this allows for dosimetric measurements through ESR technique which able to quantitatively determine the radical concentration [2]. Our research group has started an investigation of the ESR response of some phenols compounds for possible ESR dosimetric ap plications suitable features, such as high efficiency of radiation-matter energy transfer and radical stability at room temperature [3-5]. In this work we report the ESR investigation of IRGANOX 1076 pellets a nd thin films exposed to various type of radiation beams (clinical photon and electron beams, neutron-photon mixed field).

The aminoacid L-a-alanine has attracted considerable interest for use in radiation ESR dosimetry and has been formally accepted as a secondary standard for high-dose (kGy) and transfer dosimetry . The accuracy of the method is quite high, largely due to the low dependence of the alanine response on various irradiation parameters (photon energies above 100 keV, dose rate, temperature, etc.). Furthermore, this system presents alinear response to dose, fairly high sensitivity, tissue equivalence, absence of fading, small dimensions, ruggedn ess, and non-destructive readout. In this work, we examined the energy dependence of alanine ESR dosimeters in the low energy X-photon energy range between 1 keV and 40 keV, which was not previously described. Furthermore, we analyzed the response enhancement of alanine loaded with gadolinium oxide. The ESR measurements were complemented by the information provided by a reference ionization chamber and a by semiconductor detection systems.

Intracranial stereotactic radiosurgery (SRS) is a technique to deliver an ablative radiation dose with an extremely sharp dose gradient to small brain tumors. This tecnique allows to deliver high doses of radiation to the tumor sparing the surrounding healthy tissue. In this study the accuracy of the dose delivered in a SRS session by a non conventional radiotherapy machine, the TomoTherapy Hi-Art System, was investigated using an "end-to-end" test. This is perfome d by means of alanine Electron Paramagnetic Resonance (EPR) pe llets. The response of these dosimeters is compared to that of gafchromic films which are particularly suitable for two-dimensional dose verification providing accurate estimate of the distribution and of the gradients of the absorbed dose.

La radioterapia stereotassica extra-cranica (Stereotactic Body Radiation Therapy) consente di somministrare una dose ablativa ad un volume bersaglio non encefalico mediante un numero ridotto di frazioni. La riduzione nel numero di frazioni comporta necessariamente un aumento della precisione ed accuratezza in tutte le fasi del trattamento, dalla simulazione CT alla pianificazione ed all’erogazione della dose terapeutica. Dal punto di vista dosimetrico i trattamenti SBRT sono caratterizzati innanzitutto da un elevato grado di conformazione e soprattutto dalla presenza di gradienti di dose particolarmente ripidi necessari per minimizzare la dose ai tessuti sani circostanti ed agli organi a rischio posti nelle vicinanze del volume da irradiare. A seconda dello scenario clinico vengono utilizzate tecniche 3D-CRT (3D-Conformal Radiation Therapy) o IMRT (Intensity Modulated Radiotherapy). Questo lavoro mette a confronto, nel caso di irradiazione polmonare, due diverse tecniche ad intensità modulata: una tecnica statica Step-and-Shoot ed una tecnica volumetrica dinamica, la Tomoterapia Elicoidale (HT, Helicoidal TomoTherapy).

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 imaging investigations of Fricke Xylenol Gel characterized by gelatinous matrix of Agarose for possible applications in clinical photon beams used for radiation therapy. Materials and Methods: NMR relaxometry measurements were performed using an mq-ProFiler single-side relaxometer (Bruker Biospin). MRI imaging was realized on a 1.5 T Achieva scanner (Philips) with an eight channel head coil. The gels were irradiated in the clinical dose range (0– 20 Gy) with a Siemens Primus Low linear accelerator. Results: The main dosimetric features of the NMR signal were investigated. The linearity of the response with dose was observed. In order to assess the photon sensitivity we analyzed the dependence of NMR relaxation time on radiation dose with varying ferrous ammonium sulfate content inside FXG. The ferrous ammonium sulfate content which maximizes sensitivity is 1.75 mM. Furthermore, signal stability was followed for several days after irradiation. Aldo for MRI analysis the dose calibration curves were obtained also with MRI scanner. Moreover, a depth dose profile was reconstructed. Conclusions: We can conclude that FXG dosimeters with optimal ferrous ammonium sulfate content can be regarded as a valuable dosimetric tool to achieve fast information on spatial dose distribution.

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 electron beams, mix field neutrons/photons). Phenols are compounds possessing a benzene ring attached to a OH group. After irradiation the final product is a stable phenoxy radical. Materials and methods: Thanks to their size, the phenolic films here presented are good devices for the dosimetry of beams with high dose gradient and which require accurate knowledge of the precise dose delivered. Photon and electron irradiations at various energies were performed with the Siemens Primus Lowlinear accelerator present at ARNAS Ospedale Civico di Palermo, Italy. Thermal neutron irradiations were performed at the thermal neutron column at the Triga Mark II reactor of LENA (Laboratorio Energia Nucleare Applicata) of Pavia, Italy. ESR dosimeters were readout by means of a Bruker ECS106 spectrometer equipped with a TE102 rectangular cavity at room temperature. Results: The dose response of both pellets and films was found to be linear for all beams used in the dose range analyzed. The signal is very stable in the first days after irradiation. The possibility of obtaining depth dose profile was investigated. Conclusions: In conclusion, the phenols show radiometric features that designate it as a new material for EPR.

Introduction: Diffusion tensor imaging (DTI) is the most commonly used technique to extract microstructural features from a set of diffusionweighted images. In addition to the metrics obtained with DTI, diffusion kurtosis imaging (DKI) can provide non-Gaussian diffusion measures by means of the kurtosis tensor. DKI has shown to be more sensitive to tissue microstructural changes in both normal and pathological neural tissue. In a clinical setting, however, these benefits are often nullified by numerous acquisition artifacts. The aim of this study was compare two preprocessing software for DTI apply to DKI. Also, the major preprocessing, processing and post-processing procedures applied to DKI data are discussed. Materials and Methods: The reproducibility typical to DKI parameters obtained from the same dataset using two DTI analysis software tools was evaluated by the image quality measurements in regions of interest on 10 DKI datasets. The data were corrected for motion and eddy current artifacts using two different softwares: ExploreDTI (http://www.exploredti.com) and TORTOISE DIFF_PREP (https://science.nichd.nih.gov/confluence/ display/nihpd/TORTOISE). The data analysis was performed using in-house developed software implemented in Python. Results: The performances of these approaches were compared with Monte Carlo simulations. A quantitative analysis of differences of typical DKI maps obtained from data preprocessed with these two packages was performed and the advantages and disadvantages of each tool are highlighted. Conclusion: This work is aimed at providing useful indications for application of DKI in clinical settings where artifacts in diffusion weighted images are common and may affect DKI measurements and the lack of standard procedures for post-processing might become a significant issue for the use of DKI in clinical routine.

La sicurezza del paziente sottoposto a trattamenti terapeutici con radiazioni ionizzanti e il buon esito degli ultimi sono strettamente legati all’ottimizzazione delle procedure di esposizione alle radiazioni ionizzanti. In particolare è fondamentale arrecare il danno minore possibile ai tessuti sani che circondano la neoplasia da trattare. Rispetto ai campi di radiazione convenzionali utilizzati in radioterapia (fotoni), le particelle cariche pesanti (protoni e ioni carbonio) offrono diversi vantaggi quali la bassa dispersione laterale, l’alta efficacia biologica (RBE) nella regione del picco di Bragg ed un profilo di dose caratteristico in profondità del tutto differente da quello dei fotoni. Queste caratteristiche rendono particolarmente vantaggioso l’uso di queste particelle per il trattamento di tumori radio-resistenti localizzati vicino agli organi a rischio. Tra i rivelatori a stato solido usati in ambito dosimetrico, trovano largo utilizzo i dosimetri a Risonanza Elettronica di Spin (ESR) a base di alanina per le loro caratteristiche dosimetriche quali la tessuto-equivalenza per fotoni, la linearità di risposta alla dose in un ampio range, l’alta stabilità nel tempo del segnale radioindotto, la non distruttività della procedura di lettura, l’indipendenza dal dose-rate; inoltre non è richiesto alcun trattamento del campione prima della misura ESR e i dosimetri hanno un costo decisamente basso. Queste peculiarità, associate alla possibilità di riconoscere le varie componenti di un campo misto di radiazioni, rendono l'alanina un buon candidato per effettuare stime di dose durante l’uso di fasci di protoni e ioni carbonio. L'obiettivo principale del presente lavoro è quello di studiare la risposta di pellets di alanina analizzati tramite ESR irradiati con fasci di ioni carbonio utilizzati in ambito clinico. Nello specifico, per gli ioni carbonio sono stati condotti studi dosimetrici in acqua ed in presenza di disomogeneità del mezzo (come all'interfaccia osso-acqua) per simulare uno scenario quasi-clinico. Gli esperimenti sono stati condotti presso il Dipartimento di Biofisica del GSI Helmholtzzentrum in Germania utilizzando un fascio modulato attivamente usato per il trattamento di tumori in profondità. I risultati sperimentali sono stati modellizzati e confrontati con I dati del treatment plannig system (TPS).

Recenti studi epidemiologici hanno evidenziato una incidenza di complicanze oculari (cataratte), per esposizione alle radiazioni ionizzanti del cristallino, superiore a quanto ritenuto in passato. Nella sua pubblicazione del 21 aprile 2011 dal titolo “Statement on Tissue Reactions”, sugli effetti tissutali deterministici non cancerogeni delle radiazioni ionizzanti, l’ICRP indica per il cristallino una dose soglia di 0,5 Gy e raccomanda, per esposizioni lavorative, il limite annuale di 20 mSv di dose equivalente come media su un periodo di 5 anni, senza che sia mai superato il valore di 50 mSv in ogni singolo anno. Questo valore è di gran lunga inferiore all’attuale limite di legge che è pari a 150 mSv/anno. Tali raccomandazioni impongono un approfondimento delle metodologie di valutazione della dose al cristallino al fine di assicurare un migliore controllo della dose a questo organo particolarmente esposto nei lavoratori che svolgono procedure interventistiche sotto guida radiologica. Scopo di questo lavoro è quello di definire una procedura operativa per l’attribuzione della dose al cristallino analizzando i vari fattori che possono influenzare tale attribuzione. In particolare: l’efficacia schermante dei dispositivi di protezione individuale (occhiali anti-X), la scelta del dosimetro e la correlazione tra la dose al cristallino e la dose ricevuta da altre parti del corpo.

This study is aimed at measuring the variation of functional connectivity between cortical brain regions after tDCS along time. For this purpose we enrolled 20 healthy right-handed subjects.

Intra-operative radiation therapy (IORT) is a treatment modality where a single high dose of radiation is delivered directly to the tumor bed or to the exposed tumor during the surgical intervention, while avoiding surrounding dose-limiting structures. Mobile electron linear accelerators dedicated to IORT have been manufactured which have promoted a local large diffusion of this radiotherapy modality. For breast irradiation, a single fraction of 21 Gy delivered on the target volume during the surgical procedure is equivalent to the total dosage (60 Gy) usually delivered during 30 external fractionated radiotherapy at 2Gy/fraction. Alternatively, a single dose of 10 Gy can be administered as Intra-Operative Boost to the tumor bed, followed by hypo-fractionated or conventional external beam whole breast radiotherapy. This work reports a comparison between the response of alanine and Markus ionization chamber carried out for measurements of the output factors (OF) of electron beams produced by a linear accelerator used for IORT. Output factors (OF) for conventional high-energy electron beams are normally measured using ionization chamber according to international dosimetry protocols. However, the electron beams used in IORT have characteristics of dose per pulse, energy spectrum and angular distribution quite different from beams usually used in external radiotherapy, so the direct application of international dosimetry protocols may introduce additional uncertainties in dosimetric determinations. The high dose per pulse could lead to an inaccuracy in dose measurements with ionization chamber, due to overestimation of ks recombination factor. Furthermore, the electron fields obtained with IORT-dedicated applicators have a wider energy spectrum and a wider angular distribution than the conventional fields, due to the presence of electrons scattered by the applicator’s wall. For this reason, a dosimetric system should be characterized by a minimum dependence from the beam energy and from angle of incidence of electrons. This become particularly critical for small and bevelled applicators. All of these reasons lead to investigate the use of detectors different from the ionization chamber for measuring the OFs. Furthermore, the complete characterization of the radiation field is achieved also by the use of Monte Carlo Geant4 simulations which allows to obtain detailed information on dose distributions. We compared the output factors obtained by means of alanine dosimeters and Markus ionization chamber. The results are characterized by a good agreement of response of alanine pellets and Markus ionization chamber and Monte Carlo results (within about 3%) for both flat and bevelled applicators.

Fricke Xylenol Gel (FXG) dosimetric system is based on the radiation induced oxidation of ferrous (Fe2+) to ferric (Fe3+) 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. The gel matrix also contributes to the oxidation of ferrous ions during irradiation, increasing the chemical yield of ferric ions in aqueous solution and increasing the sensitivity of the dosimeter. The oxidation of ferrous ions also causes a reduction of the longitudinal nuclear magnetic relaxation time T1 which can be measured by means of Nuclear Magnetic Resonance Relaxometry (NMR) and Magnetic Resonance Imaging (MRI). The results presented are related to an experimental investigation conducted on Fricke Gels characterized by gelatinous matrix of Agarose or PVA. We performed NMR relaxometry investigations which allow for direct measurements of the relaxation times in samples exposed to clinical photon beams. The main dosimetric features of the NMR signal were investigated. The gels were irradiated in the clinical dose range between 0 and 20 Gy. In order to assess the photon sensitivitywe analyzed the dependence of NMR relaxation time on radiation dose with varying ferrous ammonium sulfate content inside FXGs. Furthermore, signal stability was followed for several days after irradiation. These measurements were preliminary to MRI analysis which can permit 3D dose mapping. In order to optimized the MRI response a systematic study was performed to optimize acquisition sequences and parameters. In particular, we analyzed for inversion recovery sequences the dependence of MRI signal on the repetition time TR and on the inversion time TI . The dose calibration curves are reported and discussed from the point of view of the dosimeter use in clinical radiotherapy. This work has highlighted that the optimization of additives inside gel matrix is fundamental for optimizing photon sensitivity of these POSTERS 355 detectors. We can conclude that FXG dosimeters with optimal ferrous ammonium sulfate content can be regarded as a valuable dosimetric tool to achieve fast information on spatial dose distribution.

BACKGROUND AND PURPOSE: We present functional connectivity (FC) changes found in the very first patients treated with the first Italian installation of a trans-cranial MRI-guided Focused Ultrasound Surgery (tcMRgFUS) certified system for functional neurosurgery. TcMRgFUS is a promising new technique for non-invasive treatment of neurologic disorders such as Essential Tremor, tremor associated to Parkinson's Disease and Neuropathic Pain. TcMRgFUS is able to focally target and destroy specific regions in the brain through intact skull, by using a high intensity focused ultrasound beam. Resting state functional Magnetic Resonance Imaging (RS-fMRI) analyses focuses on spontaneous low frequency fluctuations (< 0.1 Hz) in the BOLD signal and investigates synchronous activations between spatially independent brain regions (FC), occurring in the absence of a task or stimulus. METHOD AND MATERIALS: Patient enrollment was based on indication for functional neurosurgery and evidence of medication-refractory disease; we treated three patients, respectively affected by: neuropathic pain, intentional tremor due to ischemic lesion and essential tremor. A detailed medical history was collected together with a complete clinical examination and a neurophysiological assessment. TcMRgFUS treatments were performed by a neurosurgeon with proven experience in functional neurosurgery, and an experienced neuroradiologist, optimizing treatment parameters case by case. All patients underwent a 10’ RS-fMRI session immediately before and two days after the treatment. Functional connectivity data was analyzed by the use of the MELODIC tool from FMRIB Software Library (FSL) in a single-subject fashion, comparing post- and pre-treatment data. RESULTS: All the patients experienced an important and almost immediate improvement of their symptoms, with a complete recovery of the tremor and a partial pain relief in the patient with neuropathic pain. No adverse events were reported. We found modifications of FC within sensory-motor networks in all patients. CONCLUSION AND DISCUSSION: Although this is a very preliminary experience and our sample is very small, the FC changes we found pave the way to the use of RS-fMRI as a powerful tool to be correlated to clinical-neurologic outcomes.

The main gol of the present work is to investigate the response behaviour of alanine EPR pellets in clinical proton anc carbon ion beams. Proton irradiations were carried out at PSI (Switzerland) using both passive and active scattering modality, whereas, C ions irradiation were performed at GSI (Germany) adopting the raster scanning modality.

Laser-driven proton has recently gained a great interest as an alternative to conventional and more expensive acceleration techniques. These ion beams have desirable qualities such as small source size, high luminosity and small emittance to be used in different physics fields. This is very promising specially for the future perspective of a new concept of hadrontherapy based on laser-based devices could be developed, replacing traditional accelerating machines. ELIMED (Medical Applications at Extreme Light Infrastructure) is a task-force originally born by an idea of ELI-Beams (Prague) and INFN-LNS (Italian Institute for Nuclear Physics of Catania) researchers. ELIMED main goal is to perform proof-of-principle experiments aimed to demonstrate that laser-accelerated high-energy proton beams (up to 70 MeV in the first phase) can be potentially used for the specific case of ocular proton therapy. In this work we report the investigation of the dosimetric features of alanine pellets exposed to protons produced by means of the CATANA (Centro di AdroTerapia e Applicazioni Nucleari Avanzate) proton therapy facility. This analysis is preliminary for the application of the alanine dosimeters in laser-driven proton beams. ESR spectrometry with alanine is now widely recognized as the most accurate method of transfer dosimetry in the industrial (kGy) dose range. It is well established for calibrating industrial radiation sources against national standards (NIST, IAEA, NPL) and for comparisons between national laboratories. The accuracy of the method is generally very high, largely due to the low sensitivity of the alanine response to irradiation variables (energy, dose rate, temperature, etc.), and the ability of ESR spectrometers to measure dosimeter signals very precisely. As a matter of fact, the main requirements for a suitable system such as: linear response to dose, sensitivity, tissue equivalence, absence of energy dependence, absence of fading, small dimensions, ruggedness, and nondestructive readout, to a large extent are met by the alanine/ESR dosimetry. Here we analyzed the performances of two different alanine/ESR systems (3 mm pellets and 0.1 mm films) irradiated with therapy proton beams (62 MeV). The LET dependence of the response was obtained from the analysis of pellet irradiated with a modulated beam. The energy dependence of the response was derived from the analysis of film stacks irradiated with pristine beams. Use of thin films allowed for a high resolution sampling of the proton slowing down mechanisms. Alanine measurements are compared with Markus parallel plate ionization chamber and are aided by Monte Carlo calculations for medical physics using GEANT4 code

Gel dosimeters for three-dimensional mapping of radiotherapy doses were introduced at Yale University in the mid-1980’s. Soon after, research and development in this field also started in Italy. Early work was done at the Istituto Superiore di Sanità, and at the Universities of Pisa and Milan. Several institutes now collaborate on this topic with the goal of developing new formulations of hydrogel matrices with improved characteristics of stability, sensitivity and spatial resolution compared to those of earlier Fricke-gel and polymer-gel systems. Contrary to earlier gels based on natural gelling agents, such as porcine skin gelatin and/or agarose, which suffer from limited batch -to-batch reproducibility, we chose to develop formulations based on synthetic poly vinyl alcohol chemically cross-linked with glutaraldehyde. Several gel formulations and production procedures were investigated and are illustrated. The properties of these gels were investigated through a variety of techniques, including curemetry to determine the influence of GTA concentration and temperature over gelation time as well as scanning optical absorption to determine the sensitivity of the detectors and the spatial stability of the response. Comparative results are presented for the formulations we investigated, including one that provides a lower detection limit in the order of 100 mGy and a linear respon se exceeding 30 Gy, which makes it suitable for the verification of complex 3D treatment plans. Compared to earlier version of the detectors, we also achieved a simplification of the manufacturing processes in order to facilitate the diffusion of this technology and its transition from the bench to the bedside

The aim of this work is the definition of an MRI protocol for Diffusion Kurtosis Imaging (DKI) by using a 1.5T clinical scanner and the development of a software for DKI analysis.

The main gol of the present work is to investigate the response behaviour of alanine EPR pellets in clinical proton anc carbon ion beams. Proton irradiations were carried out at PSI (Switzerland) using both passive and active scattering modality, whereas, C ions irradiation were performed at GSI (Germany) adopting the raster scanning modality.