Room: Exhibit Hall | Forum 3
Purpose: To improve the sensitivity and dose linearity of the 3D radiochromic dosimeter by adding yellow pigment.
Methods: Radiochromic polyurethane dosimeters were fabricated by mixing polyurethane, leuco dye, initiator, and solvent. For the polyurethane, we used three types of polyurethane with Shore hardness values of 30A (Clear Flex 30), 50A (Clear Flex 50), and 80D (Crystal Clear 200). After that, we fabricated another set of radiochromic polyurethane dosimeters identical to those described above but added a yellow pigment (Tartrazine, FD&C Yellow No. 5). Therefore, a total of six types of dosimeters were tested in this study (Shore hardness of 30A, 50A, and 80D with and without the yellow pigment). Doses of 10 cGy, 20 cGy, 50 cGy, 80 cGy, 100 cGy, 150 cGy, 200 cGy and 300 cGy were delivered to each dosimeters with 6 MV photon beams of Trilogy (600 MU/min). After irradiation, optical densities were acquired with optical-CT. The sensitivity and dose linearity of each type of dosimeters were analyzed.
Results: As increasing the Shore hardness, the sensitivity and the dose linearity of the dosimeter increased in general. The sensitivity of the dosimeter with Shore hardness of 80D showed 0.0349 Î”OD/Gy without the yellow pigment. By adding the yellow pigment, the sensitivity increased up to 0.0658 Î”OD/Gy. The dosimeter with Shore hardness of 80D showed higher dose linearity than those of 30A and 50A, showing R2 value of 0.9965. By adding the yellow pigment, this dose linearity was also improved exhibiting R2 value of 0.9993.
Conclusion: The radiochromic polyurethane fabricated with polyurethane having Shore hardness of 80D showed the highest sensitivity and dose linearity by adding the yellow pigment.