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For a few years at the Azienda Ospedaliero - Universitaria “Policlinico - Vittorio Emanuele” of Catania (Italy), ocular melanoma brachytherapic treatments with Ru-106 plaques have been made. This type of treatment is planned using the specific Treatment Planning System (TPS) BEBIG “Plaque Simulator” software that simulates the delivered dose distribution from the source used on the eye tissue. Improving dosimetry for ophthalmic therapeutic applications is worthwhile. Accurate dose measurements require detectors of adequate dimensions with respect to small distances involved. The main objective of the work is the improvement of dosimetry accuracy with a high sensitivity and spatial resolution system such as EBT2 Gafchromic ® film. The relative depth dose, the 2D and 3D distributions, the source uniformity and asymmetry were obtained using custom tissue equivalent phantom. Experimental results were compared with manufacturer’s calibration certificate data, TPS calculated values and Monte Carlo simulation results.

Purpose A multi-centre study to evaluate performances of PET/CT scanners and to draft a unique QC protocol for five departments was performed. The variability in quantitation of PET acceptance tests was investigated to define acceptance limits of these data establishing reference values and new tolerances to compare with the technical specifications provided by the manufacturer. Methods Spatial resolution, scatter fraction, sensitivity, count rate loss and random coincidence estimation, Noise Equivalent Count Rate (NECR) and Image quality parameters were calculated following NEMA NU2-2012 [1] standard on the new PET/CT scanners Biograph mCT Siemens installed in five different nuclear medicine departments. For each parameter, we assessed the consistency of the related data. Results The acceptance test results demonstrated comparable output for all parameters investigated. A summarize schematic results were proposed and their relative variations and tolerances were discussed. As expected, the spatial resolution showed the least variability amongst all features related to its operator-independent preparation and strictly depending on equipment construction. Conversely, the sensitivity was the most variable parameter correlated to very low activity concentration required by NEMA protocol. We reported, for one scanner, an unexpected value in the count rate accuracy test (relative mean error @ peak NEC), despite the consistency of the values of peak NEC rate obtained. Conclusions Based on this investigation, new tolerances of performance measurements were calculated and suggested employing a common platform for quality assurance procedures to minimize variability of physical reference values. The results showed the need for a multi-centre inter-comparison especially in the tests without the tolerances of technical specifications suggested by the manufacturer.

The tissue equivalent composition of the Gafchromic films makes them particularly suitable for the mapping of 2D and 3D treatment fields. This paper presents the results obtained using MD-55 film for the verification of real radiotherapy treatments through proton beam irradiation of suitable phantoms at the Clatterbridge Centre for Oncology (CCO) in Bebington (UK). After exposure, the variation in optical density of the films was measured using a CCD100 Microdensitometer (source at 665 nm). Holes of calibrated diameter, made during the assembly phase of the phantom, are identified by the MIRA software, used for data analysis, and allow the rendering of the films. The surface dose distributions were obtained from the variation in optical density of each of the films making up the phantom. Their elaboration to duplicate their position within the phantom, performed by 3D-doctor software, allows the volumetric reconstruction of the dose distribution.