Patent ID: 6969860

Claim:
A PMMA dosimeter employing polymethylmethacrylate as substance sensitive to ionizing radiation, wherein said polymethylmethacrylate has a glass transition point Tg higher than 120Â° C., thereby giving the PMMA dosimeter characteristics for cobalt-60 ionizing radiation such that absorbance changing rate with measurement light wavelength of 320 nm per 1 kGy at dose of 140 kGy under 25Â° C. condition is not less than 0.003 ABS/mm and the maximum absorbance ABS max and the minimum absorbance ABS min at dose of 140 kGy under a temperature condition range from 10Â° C. to 50Â° C. meet a formula ABS max /ABS min â‰¦1.06.