Calibration Info
To fully understand the relationship between PMT Counts and total exposure for the Nanodot OSLs, a custom calibration is needed. This calibration is used in lieu of the calibration created by the OSL reader, which is created using the pre-dosed OSLs from the manufacturer. To begin the calibration, a set of fifteen unexposed Nanodot OSLs is chosen at random and exposed to a 9.3Ci [math]\displaystyle{ ^{137}Cesium }[/math] source. Using a distance of 30cm from the faceplate of the source and also including the distance from the faceplate to the surface of the source, [math]\displaystyle{ {D}=(\text{Distance to faceplate} + 11.2cm)=41.2cm }[/math] , the exposure rate is calculated in Roentgen using [math]\displaystyle{ \dot R = \frac {\Gamma A }{ D^2} }[/math]. A gamma factor of [math]\displaystyle{ {\Gamma} = 0.33 \frac {(m^2)(R)}{(Ci)(hr)} }[/math] and activity of [math]\displaystyle{ {A} = 9.3 Ci }[/math] is used for these calculations. Using the exposure rate calculation, it is possible to find the total exposure by integrating over time, [math]\displaystyle{ \int\limits_{t_0}^{t_f}\dot R\ dt }[/math].
Total exposures are calculated by