Dados do Trabalho

Título

THE USE OF RADIOLOGICAL CONTRAST MEDIUM IN RADIOTHERAPY PLANNING – APPLICABILITY FROM THE TECHNICAL POINT OF VIEW

Introdução

The contrast medium used in computed tomography (CT) is iodinated contrast, a radiodense substance that allows for the differentiation of different structures. As with CT scans for diagnosis (CTD), in CT for radiotherapy planning (CTRP) the contrast may be indicated by the radiotherapist. Thus, knowledge about the contrast mechanism of action and its various phases of circulation in the body are important for image acquisition. There is still no well-established consensus in the literature regarding the indication of certain contrast phases for CTRP.

Objetivo

The objective of this work was to describe the different phases of contrast circulation, based on pre-established protocols for CTD, in order to elucidate the main questions about its technical application in CTRP.

Método

Contrast-enhanced tomographic images were compared using a 16-channel multislice tomography, showing the differences between the contrasting phases.

Resultados

The results showed that the contrast medium is usually injected intravenously, using an injection pump. Each phase of contrasting has its indication: the arterial allows the ideal visualization of the arteries, useful for angiotomography exams, assessment of arteriovenous malformations and tumors with arterial vascularization, such as hepatic, neuroendocrine and renal neoplasms, some thyroid tumors and melanoma. The pancreatic phase may be useful for diagnosing pancreatic tumors or acute pancreatitis. The venous phase highlights the venous system, infections, inflammations and enhance a large part of brain, cervical, muscle, bone, thoracic and pelvic neoplasms, assesses lymph node involvement and the plane of cleavage of the lesions.The equilibrium phase, indicated in few cases, is the period in which the plasma contrast concentration resembles that of the interstitium. The late and excretory phases are used to assess renal excretion and, in some cases, to complement the diagnosis of adrenal, biliary and urothelial tumors.

Conclusão

Given the above, it was found that, in CTD, the performance of several contrast phases is of great relevance for the initial diagnosis of neoplasms, but in CTRP, multiphase exams are not common, and the venous phase is generally indicated, as long as there are no specific criteria to evaluate structures and neoplasms with predominantly arterial vascularization.

Palavras-chave

computed tomography; radiological contrast; radiotherapy planning.