Análise de agrupamento para classificação de fontes usadas na braquiterapia intravascular

Abstract

There are several factors that are responsible for the most deaths caused by cardiovascular diseases, which are growing in almost all countries of the world. Acute myocardial infarction (AMI) is the one that occurs with the greatest extent, originating from the partial or total occlusion of one or more coronary arteries – the atherosclerosis. Throughout the years, various techniques were implemented to diagnose as well as to treat coronary diseases. In the search for a better quality of life and a less invasive treatment than the traditional surgeries for myocardial revascularization, angioplasty is applicable. Unfortunately, around 30% of the patients treated with angioplasty, in a period of just six months, come back to treatment due to restenosis – a reoccurrence of the narrowing or blockage in the blood vessel. Nowadays, Intravascular Brachytherapy – a technique with intravenous radiation – is the method of choice as it handles this phase in a satisfactory way, for it is observed the receding of the proliferative metabolism of restenosis. Thus, with the aim for radiological protection of both patients and professionals involved in the therapy, the distribution of doses for the monoenergetic electrons and photons were calculated for blood vessels of 4.5, 3.0 and 1.5 mm of diameter in several sources, using the MCNP4B code. In this context, the goal of this work was to classify theradioactive sources used in Intravascular Brachytherapy by employing Cluster Analyses with related dendograms and Cophenetic Correlation Coefficients. The results showed that the hierarchical techniques were effective in the classification of the electron-emitting radioactive sources (Cophenetic Correlation Coefficients varied from 0.81 to 0.99), whereas for the photons these techniques were not satisfactory (Cophenetic Correlation Coefficients varied from 0.64 to 0.78).