background:The anthropomorphic and anthropometric phantom developed by the research group NrI (Núcleo de radiações Ionizantes) can reproduce the effects of the interactions of radiation occurring in the human body. The whole internal radiation transport phenomena can be depicted by film dosimeters in breast rT. Our goal was to provide a dosimetric comparison of a radiation therapy (rT) plan in a 4MV 3D-conformal rT (4MV-3DcrT) and experimental data measured in a breast phantom. Materials and methods:The rT modality was two parallel opposing fields for the left breast with a prescribed dose of 2.0 Gy in 25 fractions. The therapy planning system (Tps) was performed on caT3D software. The dose readings at points of interest (pOI) pre-established in Tps were recorded. an anthropometric thorax-phantom with removal breast was used. eBT2 radiochromic films were inserted into the ipisilateral breast, contralateral breast, lungs, heart and skin. The irradiation was carried out on 4/80 Varian linear accelerator at 4MV. results:The mean dose at the Oar's presented statistically significant differences (p < 0.001) of 34.24%, 37.96% and 63.47% for ipsilateral lung, contralateral lung, and heart, respectively. The films placed at the skin-surface interface in the ipsilateral breast also showed statistically significant differences (p < 0.001) of 16.43%, -10.16%, -14.79% and 15.67% in the four quadrants, respectively. In contrast, the pTV dosimeters, representative of the left breast volume, encompassed by the electronic equilibrium, presented a non-significant difference with Tps, p = 0.20 and p = 0.90. conclusion:There was a non-significant difference of doses in pTV with electronic equilibrium; although no match is achieved outside electronic equilibrium.
The present research proposal aimed to measure absorbed dose in a thorax phantom with synthetic breasts provided by an Intensity-Modulate Radiation Therapy (IMRT) protocol in an arbitrary RT center. As methods, a thorax simulator was prepared by the Ionizing Radiation Research Group (NRI) and radiochromic films were used for dose measurements. Tomographic images were taken at NRI phantom. Expositions were procedure in the Elektra 6MV LINAC. Hypofractionated regime was considered with a dose fraction of 2,7Gy in 16 fractions at the prescribed dose of 43.2 Gy at 95% of PTV. The dose comparison from the treatment planning system (TPS), Xio (Elekta) and from the experimental data was performed. The internal two-dimensional dose maps in the breast, at the skin on the left and contra-lateral breasts, heart and lungs. The measurements showed that the internal mean doses taken at the synthetic breast presented mean dose above the prescribed dose. Moreover, in general, doses to organs at risk (OARs) were within the Memorial Sloan Kettering Cancer Center (MSKCC) criteria. The non-full reproduction of the build-up region in the films had occurred due to the assymetrical positioning of the films in the inner breast, in the addition to their non-constant distance from the skin. Hot regions were present, may be due to the beam angulation chosen and the increase of MUs in the IMRT plane. As conclusions, the films can supply details and information that TPS does not provide. Assertiveness in clinical IMRT protocols can improve the prognosis and effectiveness of breast cancer treatment bring-ing possible clinical benefits.
How come such a successful theory like Quantum Mechanics has so many mysteries? The history of this theory is replete with dubious interpretations and controversies. The knowledge of its predictions, however, caused the amazing technological revolution of the last hundred years. In its very beginning Einstein pointed out that there was something missing due to contradictions with the relativity theory. So, even though Quantum Mechanics explains all the physical phenomena, due to its mysteries, there were many attempts to find a way to "complete" it, e.g. hidden-variable theories. In this paper, we discuss some of these mysteries, with special attention to the concepts of physical reality imposed by quantum mechanics, the role of the observer, prediction limits, definition of collapse, and how to deal with correlated states (the basic strategy for quantum computers and quantum teleportation). The discussion is carried out by accepting that there is nothing important missing. We are just restricted by the limitations imposed by quantum mechanics. The mysteries are cleared out by a proper interpretation of these limitations. This is done by introducing two interpretation rules within the Copenhagen interpretation.
Why does such a successful theory like Quantum Mechanics have so many mysteries? The history of this theory is replete with dubious interpretations and controversies, and yet a knowledge of its predictions, however, contributed to the amazing technological revolution of the last hundred years. In its very beginning Einstein pointed out that there was something missing, due to contradictions with the relativity theory. So, even though Quantum Mechanics explains all the nanoscale physical phenomena, there were many attempts to find a way to "complete" it, e.g. hidden-variable theories. In this paper, we discuss some of those enigmas, with special attention to the concepts of physical reality imposed by quantum mechanics, the role of the observer, prediction limits, a definition of collapse, and how to deal with correlated states (the basic strategy for quantum computers and quantum teleportation). That discussion is carried out within the framework of accepting that there is in fact nothing important missing, rather we are just restricted by the limitations imposed by quantum mechanics. The mysteries are thus explained by a proper interpretation of those limitations, which is achieved by introducing two interpretation rules within the Copenhagen paradigm.
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