ACTA

Optical Scanner for 3D Radiotherapy Polymer Gel Dosimetry

P. Sobotka^a, M. Kozicki^b, P. Maras^c, Ł. Boniecki^a, K. Kacperski^d and A.W. Domański^a
^aFaculty of Physics, Warsaw University of Technology, Koszykowa 75, 00-662 Warsaw, Poland
^bDepartment of Man-Made Fibres and European Centre of Bio- and Nano-Technology (ECBNT), Łódź University of Technology, S. Żeromskiego 116, 90-924 Łódź, Poland
^cTeletherapy Department, Copernicus Hospital, Pabianicka 62, 93-513 Łódź, Poland
^dMaria Skłodowska-Curie Memorial Cancer Center and Institute of Oncology, Department of Medical Physics, W.K. Roentgena 5, 02-781 Warsaw, Poland

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Sophisticated techniques employed in radiotherapy for irradiation of tumours require comprehensive dosimetry allowing for precise, high resolution measurements of radiation dose distribution in three dimensions and verification of treatment planning systems. Polymer gel dosimetry has been shown to be a unique technique for such the purpose. If exposed to ionizing radiation, radical polymerisation and crosslinking of monomeric components take place in a 3D polymer gel dosimeter, leading to the formation of large polymeric structures that scatter visible light. This feature allows for optical observation of the effects of the absorbed dose and its distribution. Presently, magnetic resonance imaging is employed most often for the analysis of the 3D polymer gel dosimeters. However, much attention is also being given to the development of optical computed tomography since this technique is hoped to serve as a substitute for expensive and not easily available magnetic resonance imaging. The optical scanner presented in this work consists of a laser diode, a scanning system and a signal detector. A 3D polymer gel dosimeter is measured in an immersion liquid in order to reduce deflection of the light from the dosimeter phantom. The very first results were obtained with the newly constructed scanner and PABIG^nx 3D polymer gel dosimeter, which was inhomogeneously irradiated with ¹⁹²Ir brachytherapy source. The results have been contrasted with those for the magnetic resonance imaging and are presented in this work together with the description of the developed instrument. Currently, the optimization of the optical scanner is performed.

DOI: 10.12693/APhysPolA.122.969
PACS numbers: 87.50.Gi, 42.66.Si, 87.53.Bn