Cutting-edge R&D activities of CIRTEN in support of the Technology Park annexed to the Italian National Repository of radioactive waste

R&D activities taking place at the institutions belonging to Consorzio Interuniversitario per la Ricerca TEcnologica Nucleare are here presented and discussed. A special focus is on Technology Park annexed to the Italian National Repository of radioactive waste

Pilot scale validation campaign of gel dosimetry for pre-treatment quality assurance in stereotactic radiotherapy

Purpose: Complex stereotactic radiotherapy treatment plans require prior verification. A gel dosimetry system was developed and tested to serve as a high-resolution 3D dosimeter for Quality Assurance (QA) purposes.Materials and Methods: A modified version of a polyacrylamide polymer gel dosimeter based on chemical response inhibition was employed. Different sample geometries (cuvettes and phantoms) were manufactured for calibration and QA acquisitions. Irradiations were performed with a Varian Trilogy linac, and analyses of irradiated gel dosimeters were performed via MRI with a 1.5 T Philips Achieva at 1 mm3 or 2 mm3 isotropic spatial resolution. To assess reliability of polymer gel data, 54 stereotactic clinical treatment plans were delivered both on dosimetric gel phantoms and on the Delta4 dosimeter. Results from the two devices were evaluated through a global gamma index over a range of acceptance criteria and compared with each other.Results: A quantitative and tunable control of dosimetric gel response sensitivity was achieved through chemical inhibition. An optimized MRI analysis protocol allowed to acquire high resolution phantom dose data in time -frames of approximate to 1 h. Conversion of gel dosimeter data into absorbed dose was achieved through internal calibration. Polymer gel dosimeters (2 mm3 resolution) and Delta4 presented an agreement within 4.8 % and 2.7 % at the 3 %/1 mm and 2 %/2 mm gamma criteria, respectively.Conclusions: Gel dosimeters appear as promising tools for high resolution 3D QA. Added complexity of the gel dosimetry protocol may be justifiable in case of small target volumes and steep dose gradients

Cutting-edge R&D activities of CIRTEN in support of the Technology Park annexed to the Italian National Repository of radioactive waste

R&D activities taking place at the institutions belonging to Consorzio Interuniversitario per la Ricerca TEcnologica Nucleare are here presented and discussed. A special focus is on Technology Park annexed to the Italian National Repository of radioactive waste

Learning nuclear chemistry and radiochemistry through a massive open online course

A MOOC on Nuclear and RadioChemistry (NRC) has been developed within the EU-H2020 MEET-CINCH project, in order to attract more students towards the discipline and increase people awareness. The course is divided into five “weeks” highlighting the importance of radiochemistry and nuclear chemistry for environment, health, industry, nuclear energy and society. Each week consists of different modules covering all possible applications of NRC within the week topic. The module follows a pedagogical framework designed ad hoc, that gradually introduces the topic to students, giving them different examples and applications to understand the theoretical concepts and to acquire a technical terminology. Feedback obtained by the pilot edition showed very good results: despite the short duration of the course, 25% of the 203 users successfully completed the course achieving the Certificate of Accomplishment. The answers collected in the inital survey and the final customer satisfaction questionnaire showed that users belonged to the selected target group and greatly appreciated the presence of practical examples and the different lesson formats adopted. The MOOC objective of attracting new students towards NRC appears to be on a good track, however this can only be confirmed by monitoring the next MOOC editions

Practical role of polymerization inhibitors in polymer gel dosimeters

The fundamental role of pre-treatment quality assurance in radiotherapy is to verify the radiation treatment with respect to the planned dose distribution by means of a devoted dosimeter. This step is necessary to achieve the full clinical potential of the treatment by guaranteeing sparing of healthy tissues. In this study, the dose response of a modified version of the PAGAT polymer gel dosimeter, a chemical dosimeter capable of direct 3D dose measurements, has been characterized. The physical response of the dosimeter is proportional to polymerization efficiency between its constituting monomers. The effect of several polymerization inhibitors in controlling the chemical response of the gel was investigated. The addition of these compounds allows a tailoring of the range of dose response of the gel to the dose range used in clinical practice. Obtained results from optical and magnetic resonance imaging analyses of irradiated gels indicate that an accurate control of inhibitor concentration can lead to a significant extension of the useful dose range, from approximately 4 Gy for the reference composition up to 40 Gy when inhibitors are added, with no significant detriment on fundamental dosimetric parameters such as accuracy, dose resolution and stability of the dose response

Characterization of PAGAT dose response upon different irradiation conditions

Polymer gel dosimeters represent a promising instrument for tridimensional radiation dose measurement for highly conformal radiation therapy techniques. In this study, the dependence of the dose response of the polymeric gel dosimeter PAGAT was investigated as a function of different irradiation conditions and time elapsed after irradiation. An X-ray tube and Co-60 sources were used for irradiation. This allowed to assess variations in system dose response under different irradiation energies and dose rates - ranging from 1.4 Gy h-1 up to 0.14kGyh(-1). Analysis of irradiated samples was performed by UV-Vis optical measurements at different time intervals after irradiation. Significant variability in PAGAT dose response was observed for different irradiation conditions and considered dose rates

Characterization of Fricke-gelatin dosimeters for intraoperative Radiation Therapy dosimetry

In this work, the usability of Fricke gels in Intraoperative Radiation Therapy (IORT) dosimetry was investigated. Irradiated gel systems are characterized by means of UV/Vis spectrophotometric analysis in order to define the main dosimetric indexes of interest and to evaluate their post-irradiation stability. A measurement of Output Factors for different field sizes is also attempted to study the application of this system for routine quality control. Ad-hoc manufactured thin-layers of gel are employed to perform acquisitions of planar transverse dose profiles and to quantify the effect of Fe(III) diffusion. The Fricke gel system presents an adequate dosimetric performance, with excellent response linearity up to 30 Gy. Comparison of dosimetric response over a wide range of irradiation dose rates allows to conclude that the gel response is not influenced significantly by this parameter. Transverse dose profiles acquired with thin-layers present an agreement within 3% with reference values, even in very steep dose gradient regions. Finally, computed values for the diffusion coefficient of ferric ions are in good agreement with those reported in literature for dosimetric gels of similar composition. Overall performance of the gel system appears promising for further applications in IORT dosimetry