Radiation dosimetry method and associated apparatus

A method for monitoring exposure to radiation with compensation for variation in amount of detector material of a sensor, comprising:

• providing a radiation dosimeter including a layer of radiation sensitive material on a substrate, said radiation sensitive material having an optical absorbance which varies in dependence on thickness of said layer of radiation sensitive material, said layer of radiation sensitive material including a substantially radiation impervious substance having a determined local maximum absorbance value;
• exposing said layer of radiation sensitive material to a dose of radiation;
• after exposure of said layer of sensitive material to said dose of radiation, optically measuring an absorbance of the exposed layer of radiation sensitive material;
• measuring an absorbance of the radiation impervious substance in the exposed layer of radiation sensitive material;
• adjusting the determined absorbance of the radiation sensitive material in accordance with the measured value of the absorbance of the radiation impervious substance, to compensate for variation in a thickness of said layer of radiation sensitive material;
• and
• determining a radiation dose value from the adjusted absorbance value and its wavelength value.

An apparatus for determining exposure to radiation of an exposed radiation dosimeter including a layer of radiation sensitive material on a substrate, said radiation sensitive material having an optical absorbance which varies in accordance with degree of radiation exposure and wavelength and which also varies in dependence on temperature, comprising:

• optical sensing means for optically measuring a spectral absorbance of the exposed layer of radiation sensitive material within a range of wavelengths;
• spectral analysis means operatively connected to said optical sensing means for examining the measured spectral absorbance of said exposed layer of radiation sensitive material to determine an absorbance coordinate and a wavelength coordinate of a predetermined point on a spectral absorbance curve of said exposed layer of radiation sensitive material;
• and
• correlating means operatively connected to said spectral analysis means for determining a radiation dose value associated with said absorbance coordinate and said wavelength coordinate.

An apparatus for monitoring exposure to radiation of an exposed radiation dosimeter including a layer of radiation sensitive material on a substrate, with compensation for variation in thickness of said layer of radiation sensitive material, comprising:

• optical sensing means for optically measuring an absorbance of the radiation sensitive material in the exposed layer and for measuring an absorbance of the radiation impervious substance in the exposed layer;
• thickness compensating means operatively connected to said analysis means for adjusting the determined absorbance value of the radiation sensitive material and obtain a thickness corrected absorbance of the radiation sensitive material in accordance with the measured value of the absorbance of the radiation impervious substance, to compensate for variation in a thickness of said layer of radiation sensitive material;
• and
• analysis means operatively connected to said optical sensing means for determining a radiation dose value from the thickness corrected absorbance of the radiation sensitive material in said layer.