Fabrication of NIPAM Gel Dosimeters

NIPAM based gel dosimeters were fabricated using the gelatin (300 Bloom Type A, Sigma-Aldrich, St Louis, MO), NIPAM as the monomer (97% Wako, Osako, Japan), N,N’-methylene-bis-acrylamide (BIS) as the crosslinking agent (Sigma-Aldrich, St Louis, MO), and antioxidant tetrakis (hydroxymethyl) phosphonium chloride (THPC) as the antioxidant agent (TCI, Sigma-Aldrich, St Louis, MO). The weight percentages are listed in Table 1 [13 (link)]. The gelatin was added to deionized water, and the solution was stirred for 10 min at room temperature. The solution was then heated to 45°C. After it became transparent, the NIPAM and BIS were added and stirred until the components were dissolved. Then, the THPC was added and stirred for another 2 min. At last, the polymer gels were poured into a cylindrical container with a diameter and height of 10 cm. The NIPAM gel dosimeters were kept at 4°C for 6 hours before irradiation [14 ,15 ].