The Gafchromic EBT was recently introduced in film dosimetry for external beam therapy (EBT). The high spatial resolution, weak energy dependence, and near-tissue equivalence of EBT films make them suitable for measurement of dose distributions in radiotherapy, especially intensity-modulated radiation therapy (IMRT). Starting with a sensitometric curve and dose uncertainty relative to the flatbed scanner, the goal of this study was to find an efficient method of correcting for light scattering, and to compare dose distribution supplied by Gafchromic EBT with the distribution obtained with a 2D ion-chamber detector system. Light scattering was analyzed for different levels of dose, and was found to depend on the red-scale value as well as the position of the pixel on the scanner. Many "uniform" films were exposed at different levels of dose to create a two-dimensional matrix correction to take this effect into account. The dose distribution obtained for three clinical beams (10 x 10, 15 x 15 cm open fields and 12 x 12 cm wedge 60 degrees field) were in agreement with those supplied by the 2D array. Gamma index <1 (using 5 mm distance and 5% dose as constraints) for the three fields considered was reached in an average of 98% of the points.
The performances of the systems proved to be site specific, depending on the DVF type and the platforms and the procedures used at the various centers. The pelvis was the most challenging site for most of the algorithms, which failed to achieve sub-voxel accuracy. Improved reproducibility was observed among the centers using the same hybrid registration algorithm.
This retrospective multicenter analysis was aimed to evaluate clinical activity and tolerability of eribulin in pretreated metastatic breast cancer patients in clinical practice. Patients treated with eribulin from January 2012 to July 2013 were enrolled in the observational study from 10 italian hospitals. Tumor and toxicity evaluation were performed according to Agenzia Italiana Farmaco. One-hundred and thirteen patients were included in the study. Median age 62 years old. 71.7 % of the patients had visceral involvement and the majority had a burden of disease involving two or more organs with a median number of 2 (1–6). The median number of previous chemotherapy regimens for advanced disease was 3 (1–10). Median number of eribulin cycles was 4 (1–27). Overall response rate was 24 % (95 % CI 16.0–31.8). Clinical benefit rate, was 35.4 % (95 % CI 26.6–44.2). At a median follow-up of 29.6 months (8.3–41.9) the median progression free survival was 3.3 months (0.6–26.7; 95 % CI 2.4–4.2), and the median overall survival 11.6 months (0.6–33.3; 95 % CI 8.7–14.5). No correlation was recorded between subtypes in terms of ORR and CBR. Toxicity was manageable. Main common grade 3–4 toxicities were neutropenia (19.4 %), febrile neutropenia (0.9 %), asthenia (3.5 %), abnormal liver function test (1.8 %), stomatitis (0.9 %). Our results confirm that treatment with eribulin is feasible and safe in real-world patients.
When using an electronic portal imaging device (EPID) for dosimetric verifications, the calibration of the sensitive area is of paramount importance. Two calibration methods are generally adopted: one, empirical, based on an external reference dosimeter or on multiple narrow beam irradiations, and one based on the EPID response simulation. In this paper we present an alternative approach based on an intercalibration procedure, independent from external dosimeters and from simulations, and is quick and easy to perform. Each element of a detector matrix is characterized by a different gain; the aim of the calibration procedure is to relate the gain of each element to a reference one. The method that we used to compute the relative gains is based on recursive acquisitions with the EPID placed in different positions, assuming a constant fluence of the beam for subsequent deliveries. By applying an established procedure and analysis algorithm, the EPID calibration was repeated in several working conditions. Data show that both the photons energy and the presence of a medium between the source and the detector affect the calibration coefficients less than 1%. The calibration coefficients were then applied to the acquired images, comparing the EPID dose images with films. Measurements were performed with open field, placing the film at the level of the EPID. The standard deviation of the distribution of the point‐to‐point difference is 0.6%. An approach of this type for the EPID calibration has many advantages with respect to the standard methods — it does not need an external dosimeter, it is not related to the irradiation techniques, and it is easy to implement in the clinical practice. Moreover, it can be applied in case of transit or nontransit dosimetry, solving the problem of the EPID calibration independently from the dose reconstruction method.PACS number: 87.56.‐v
Our results suggest a link between iNKT cells, basal ADCC activity, genotypes in FCGR2A and FCGR3A, and efficacy of cetuximab in KRAS wt mCRC patients.
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