A quantitative analysis of the decreasing rate of the monomer and increasing rate of the polymerization was made by monitoring radiation level increments using Raman spectroscopy within the therapeutic radiation range for a normoxic polymethacrylic acid gel dosimeter. The gel dosimeter was synthesiz...
A quantitative analysis of the decreasing rate of the monomer and increasing rate of the polymerization was made by monitoring radiation level increments using Raman spectroscopy within the therapeutic radiation range for a normoxic polymethacrylic acid gel dosimeter. The gel dosimeter was synthesized by stirring materials such as gelatin, distilled water, methacrylic acid, hydroquinone and tetrakis phosphonium chloride at $50^{\circ}C$, and the synthesized gel was contained in a 10- mm diameter and 32-mm high vial to conduct measurement. 24 hours after gel synthesis, it was irradiated from 0 Gy to 20 Gy by 2 Gy using a Co-60 radiotherapy unit. With use of the Cryo FE-SEM, structural changes in the 0 Gy and 10 Gy gel dosimeters were investigated. The Raman spectra were acquired using 532-nm laser as the excitation source. In accordance with fitting the changes in C-COOH stretching (801 $cm^{-1}$), C=C stretching (1639 $cm^{-1}$) and vinyl $CH_2$ stretching (3114 $cm^{-1}$) vibrational modes for monomer and $CH_2$ bending vibrational mode (1451 $cm^{-1}$) for polymer, sensitive parameter S for each mode was calculated. The values of S for monomer bands and polymer band were ranged in $6.0{\pm}2.6$ Gy and $7.2{\pm}2.3$ Gy, respectively, which shows a relatively good conformity of the decreasing rate of monomer and the increasing rate of polymerization within the range of error.
A quantitative analysis of the decreasing rate of the monomer and increasing rate of the polymerization was made by monitoring radiation level increments using Raman spectroscopy within the therapeutic radiation range for a normoxic polymethacrylic acid gel dosimeter. The gel dosimeter was synthesized by stirring materials such as gelatin, distilled water, methacrylic acid, hydroquinone and tetrakis phosphonium chloride at $50^{\circ}C$, and the synthesized gel was contained in a 10- mm diameter and 32-mm high vial to conduct measurement. 24 hours after gel synthesis, it was irradiated from 0 Gy to 20 Gy by 2 Gy using a Co-60 radiotherapy unit. With use of the Cryo FE-SEM, structural changes in the 0 Gy and 10 Gy gel dosimeters were investigated. The Raman spectra were acquired using 532-nm laser as the excitation source. In accordance with fitting the changes in C-COOH stretching (801 $cm^{-1}$), C=C stretching (1639 $cm^{-1}$) and vinyl $CH_2$ stretching (3114 $cm^{-1}$) vibrational modes for monomer and $CH_2$ bending vibrational mode (1451 $cm^{-1}$) for polymer, sensitive parameter S for each mode was calculated. The values of S for monomer bands and polymer band were ranged in $6.0{\pm}2.6$ Gy and $7.2{\pm}2.3$ Gy, respectively, which shows a relatively good conformity of the decreasing rate of monomer and the increasing rate of polymerization within the range of error.
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제안 방법
A 3-dimensional network structure was shown in the 0 Gy SEM image of the gel dosimeter, and it was able to monitor changes in the structure from MAA to PMAA with being surrounded by the gelatin network structure when 10 Gy of radiation is irradiated.
And then, the polymerization occurs from MAA molecules by sequential radical reactions. The amount of dosage which derives full reaction was investigated by monitoring the polymerization process using Raman spectroscopy in this study. For better understanding on the behavior of the Raman bands resulted from the specific bonds in the process of polymerization, the spectra and the schematic diagram are shown in Fig.
7-9 Owing to its lower toxicity as a carcinogen in methacrylic acid (MAA) than AA, interest in gel dosimeters using this substance is increasing.4The study aims to synthesize a polymer gel and indentify radiation action mechanism of gel dosimeter in accordance with analysis of characteristic vibrational mode of MAA monomers through a Raman experiment, which will be applied as basic necessary data to secure a greatly enhanced polymer gel dosimeter.
대상 데이터
2(a) indicates the schematic diagram of Nano Raman Spectrometer. A 532 nm Diode Pumped Solid State Laser (DPSS) was used as a light source, and a Charge-Coupled Device (CCD) was applied for a detector. Data acquisited from the Raman Spectrometer were analyzed by Origin™(OriginLab Corp.
이론/모형
After irradiation of 0 Gy and 10 Gy to the polymer gel dosimeter, images were taken by SEM in a 5- μM scale.
Therefore, the results of the experiment herein were fitted by the monoexponential fitting function provided by OriginTM.
성능/효과
Raman spectroscopy was applied for the first time to the methacrylic acid based gel dosimeter, and it showed that the methacrylic acid based gel dosimeter is more sensitive than acrylamid acid based gel , being in good agreement with the results of NMR spectroscopy. Since it is possible to achieve the information at the molecular level from the application of vibration spectroscopy, i.
참고문헌 (19)
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Vlierberghe, S. V.; Cnudde, V.; Dubruel, P.; Masschaele, B.; Cosijns, A.; De Paepe, I.; Patric, J. S.; Jacobs, Hoorebeke, L. V.; Remon, J. P.; Schacht, E. Biomacromolecules 2007, 8, 331.
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