Proton CT setup at CV-28 of IEN/CNEN

• Autor(a) principal: Evseev,I.
• Data de Publicação: 2005
• Outros Autores: Assis,J. Teixeira de, Yevseyeva,O., Vinagre Filho,U.M., Setti,J.A.P., Schelin,H.R., Paschuk,S.A., Klock,M.C.L., Schulte,R.W., Lopes,R.T.
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Brazilian Journal of Physics
• Texto Completo: http://old.scielo.br/scielo.php?script=sci_arttext&pid=S0103-97332005000500006

Although the idea of proton Computed Tomography (pCT) is not new, it is currently not available. It is still unknown if the image quality of pCT is sufficient for localizing tumors and if the accuracy of proton range calculations surpass that of X-ray CT based range calculations without significantly increasing the patient exposure. The spatial resolution of pCT is limited mainly by multiple Coulomb scattering, while the contrast resolution is affected principally by the statistical nature of the proton energy loss mechanism. Both effects are more pronounced and thus easier to study at the low proton energies available at CV-28. An experimental setup for pCT at CV-28 was elaborated by our team. The first-generation CT scheme was assumed as the most adequate for the existing CV-28 proton "pencil" beam. All equipment, which includes the collimators for the initial and outgoing proton beam, the tomographic turntable, and the ORTEC L-035-025-5 proton detector, was assembled onto the support bar of the ORTEC vacuum chamber. A water-filled glass tube of 5 mm external diameter with a 1 mm diameter polyethylene rod on the central axis was chosen as the first sample to be studied. Later, the water will be substituted by tissue-equivalent solutions of different densities to study the contrast resolution. A Monte Carlo simulation of the experiment, assuming 25 MeV monochromatic proton beam, was made using the SRIM-2003.20 code. The simulation permitted to choose the critical parameters for the setup, such as the beam collimation, the steps of translation and rotation of the turntable, and the required statistics for an accurate measurement of proton energy.