title: A novel thin NIPAM gel cassette dosimeter for photon-beam radiotherapy.
abstract: The response of thin polymer gel cassettes (called NIPAM gels) to ionizing radiation was investigated in this study. The NIPAM gels were prepared from gelatin, N-isopropyl acrylamide, tetrakis (hydroxymethyl) phosphoniumchloride, and N,N'-methylene-bis-acrylamide. Gel cassettes were irradiated in a phantom using a linear accelerator, and the polymerization morphology of irradiated NIPAM gel was characterized using scanning electron microscopy. The dose-response sensitivity of the NIPAM gels was evaluated using the differences in optical densities. The optical densities were obtained using a computer-controlled CCD camera that was connected to a planar illumination source for acquisition of optical transmission images. The central axis depth dose profiles of the phantom were extracted, and a comparison with ionization chamber measurements demonstrated similarities in profiles. The sensitivity, linearity of the response, accuracy, and reproducibility of the polymer gel cassettes were acceptable. However, the profiles of the half-blocked field irradiation showed no significant dispersion in the visible region. This study also extensively investigated the spatial stability of the NIPAM gel. The results showed that the gel cassette response remains stable for up to three months after irradiation.
authors.affiliation: Department of Medical Imaging and Radiological Sciences, Central Taiwan University of Science and Technology, Beitun District, Taichung City, Taiwan, Republic of China. llhsieh@ctust.edu.tw
authors.forename: Ling-Ling
authors.initials: LL
authors.lastname: Hsieh
authors.forename: Kai-Yuan
authors.initials: KY
authors.lastname: Cheng
authors.forename: Bor-Tsung
authors.initials: BT
authors.lastname: Hsieh
mesh_terms: D000178:Acrylamides; D005782:Gels; D008855:Microscopy, Electron, Scanning; D010100:Oxygen / Q000009:adverse effects; D017785:Photons; D011874:Radiometry / Q000379:methods*; D011878:Radiotherapy / Q000379:methods* / Q000592:standards
chemical_list: D000178:Acrylamides; D005782:Gels; C067295:N-isopropylacrylamide; D010100:Oxygen