characterization of a polymer gel dosimetry system based on N-isopropylacrylamide and N-N? methylenebisacrylamide

FACUNDO MATTEA; MIRIAM STRUMIA; MAURO VALENTE

MONTEVIDEO

Congreso; X - LATIN AMERICAN SYMPOSIUM OF NUCLEAR PHYSICS AND APPLICATIONS; 2013

COM LATINOAMERICANA DE FISICA - JEFFERSON LAB USA - UNIV. REPUBLICA URUGUAY

Diagnostic radiology and radiotherapy are the most used techniques to detect andtreat several pathologies like tumor and cancer diseases. According to availableevidence [1] at least 52% of cancer patients should receive radiotherapy during theirtreatment. The process of radiotherapy is complex and involves understanding of theprinciples of medical physics, radiobiology, radiation safety, dosimetry, radiotherapyplanning, simulation and interaction of radiation therapy with other treatmentmodalities. One of the key aspects of radiotherapy is to determine the real dose anorgan or tissue is exposed. For that purpose, if the irradiation conditions are welldefined and known in relation to the anatomy of the patient, Monte Carlo simulationsof the energy deposition can be performed. However, if those conditions are notfulfilled, it is also possible to measure the organ dose directly with the use of suitablephantoms and dosimeters [2]. Among the different types of dosimeters, polymericones are of great interest because of their capability to mimic soft-tissue whilemaintaining a specific shape presenting high dose sensitivity and the ability to retain3D spatial dose distribution for long periods of time after being exposed [3]. A typicalpolymer gel dosimeter is a complex aqueous composition of physical gel-formingagent, monomers, and oxygen scavengers. The concentration of each componentaffects the sensitivity and the response of the dosimeter to radiation. Therefore, an in-depth study on the preparation methodology is essential for the development of newdosimeters.In this work the preparation and characterization of a polymeric dosimeter based onthe monomers N-isopropylacrylamide (NIPAM), N-N?-methylenebisacrylamide (BIS)and an aqueous gelatin matrix containing Tetrakis(hydroxymethyl)phosphoniumchloride (THPC) as oxygen scavenger is studied. Different characterizationtechniques, such as X-ray Raman spectroscopy, confocal and scanning electronicmicroscopy, and absorbance/transmitance analysis of the different dosimeters afterbeing irradiated are presented and analyzed from a physical and chemical point ofview, in the interest of proposing new materials for specific treatment purposes.[1] G. Delaney, S. Jacob, C. Featherstone, M. Barton, The role of radiotherapy in cancertreatment, Cancer, 104 (2005) 1129-37.[2] A. Meghzifene, D.R. Dance, D. McLean, H.-M. Kramer, Dosimetry in diagnosticradiology, European Journal of Radiology, 76 (2010) 11-14.[3] C. Baldock, Y.D. Deene, S. Doran, G. Ibbott, A. Jirasek, M. Lepage, K.B. McAuley, M.Oldham, L.J.