RadioTherapy. 80 wt% 90 wt% 3wt% 5wt% 3 wt% 10 wt% 1

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1 With rapid advances being made in radiotherapy treatment, three dimensional (3D) dose measurement techniques with great precision are required more than ever before. It is expected that polymer gel dosimeters will satisfy clinical needs as an effective detector that can measure the complex 3D dose distributions. Polymer gel dosimeters are devices that utilize the radiation-induced polymerization reactions of vinyl monomers in a gel to keep information about radiation dose. The 3D absorbed dose distribution can be deduced from the resulting polymer distribution using several imaging modalities, such as MRI, X-ray and optical CT. In this article, the fundamental characteristics of polymer gel dosimeter are reviewed along with the author s work. Keywords: Polymer gel dosimeter, MAGAT, PAGAT, MRI, Radiotherapy IMRT: Intensity Modulated Radiation Therapy SRT: Sterotactic RadioTherapy X CT 1 2 QC QA 3 1) 2 80 wt% 90 wt% 3wt% 5wt% 3 wt% 10 wt% 1 20 cmφ 20 Gy X Polymer gel dosimeter Shin-ichiro Hayashi (Hiroshima International University), , TEL: , FAX: , rin@hs.hirokoku-u.ac.jp Gy

2 X Gy MRI : Magnetic Resonance Imaging X CT X ray Computed Tomography CT Optical CT 3 3 6) Kennan 7) N,N - NMR R 1 (= 1/T 1 ) MRI X CT ) 4 H 2 O R (Radiolysis) (1) R + M RM (Initiation) (2) M + M MM (Propagation) (3) M + M (R ) MM (MR) (Termination) (4) R OH M R M 2 M M (1) (4) 11 15) MRI X CT CT 3 G 10 2 mol/j 16) C 17) PET MAG Bis PAG MAG 93 (2012) 24

3 THPC MAGAT Methacrylic Acid, Gelatin And THPC PAG Bis THPC PAGAT PolyAcrylamide, Gelatin And THPC 1 Monomer Methacrylic-acid-base Methacrylic acid (MA); CH 2 = C(CH 3 )COOH 2-Hydroxyethyl-methacrylate (HEMA); CH 2 = C(CH 3 )COC 2 H 5 OH Acrylamide-base 2 MAG, PAG MAGAT Water 87 wt% Methacrylic acid (MA) 5 wt% Gelatin 8 wt% THPC 2 mm PAGAT Water 89 wt% Acrylamide (AA) 3 wt% N,N -methylene-bisacrylamide (Bis) 3 wt% Gelatin 5 wt% THPC 5 mm Acrylamide (AA); CH 2 = CH-CO-NH 2 N-isopropylacrylamide (NIPAM); CH 2 = CH-CO-NH-CH 2 (CH 3 )CH 3 Cross-linker N,N -methylene-bisacrylamide (Bis); CH 2 = CH-CO-NH-CH 2 -NH-CO-CH=CH 2 Oxygen scavenger Ascorbic acid (AsA); C 4 H 3 O 4 -CH(OH)CH 2 OH Cupper Sulphate (CS); CuSO 4 Tetrakis-Hydroxymethyl-Phosphonium Chloride (THPC); P(CH 2 OH) + 4 Cl Tetrakis-Hydroxymethyl-Phosphonium Sulphate (THPS); [P(CH 2 OH) + 4 ] 2S 2 Polymerization inhibitor HydroQuinone (HQ); HO-C 6 H 4 -OH Gelling agent Gelatin (300Bloom) 2 MAGAT PAGAT MAGAT PAGAT MRI Bis N- NIPAM 18) BANGkit MGS Research MAG 500 g C 1 19) 23 C 3.3 X Varian CL ix 2 6MVX cm 3 5cm 5 cm 25

4 10 10 cm cm 2 2 Gy 20 Gy 1Gy/min 6Gy/min 1000 ml PET 3 MRI 2 X 3.4 MRI MRI 3 T 2 R 2 = 1/T 2 R 2 = 1 T 2 = 1 TE 2 TE 1 ln( S 1 S 2 ) (5) S 1 S 2 echo (sampling) time; TE 1 TE 2 MRI DICOM T 2 ImageJ (5) 20) R 2 4 MRI X CT 4 ImageJ R 2 X CT 1 MRI 10 1mm MRI 5mm X CT 21 24) CT MGS Research OCTOPUS IQ Modus Medical Devices 93 (2012) 26

5 VISTA MRI X CT CT MRI X 2 X MRI MAGAT PAGAT R 2 5 (Gy) R 2 MAGAT PAGAT 20 6 (a) MAGAT (b) PAGAT MAGAT PAGAT 7(a) (b) 1Gy 1 MAGAT 5 PAGAT MAGAT 6(a) PAGAT 6(b) 4.2 RTP: radiotherapy planning system, Eclipse 8.1 Varian 27

6 25) MAG PAG 7 (a) MAGAT, (b) PAGAT 8 PET 4 4 4cm 3 PTV 2 3Gy 6Gy PAGAT MAG IMRT 10 11, 26) PAG PAG, 5.2 PAG 21 24) PAG Bis PAG 93 (2012) 28

7 8 2 9 PAGAT Bis PAG 3wt% 21 23) MRI X CT 2 3 MRI 27) Fong 17) 29

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