Difference between revisions of "Calibration Info"

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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> ^{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>{D}=(\text{Distance to faceplate} + 11.2cm)=41.2cm </math> , the exposure rate is calculated in Roentgen using <math> \dot R = \frac {\Gamma A }{ D^2} </math>. The gamma factor used for these calculations is <math> {\Gamma} = .33 \frac {(m^2)(R)}{(Ci)(hr)} </math>
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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> ^{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>{D}=(\text{Distance to faceplate} + 11.2cm)=41.2cm </math> , the exposure rate is calculated in Roentgen using <math> \dot R = \frac {\Gamma A }{ D^2} </math>. A gamma factor of <math> {\Gamma} = 0.33 \frac {(m^2)(R)}{(Ci)(hr)} </math> and activity of <math>{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>\int\limits_{t_0}^{t_f}\dot R\ dt </math>.
  
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<math>\mathbf{A} = 9.3 Ci </math> ,  <math>\mathbf{D}=(\text{Distance to faceplate} + 11.2cm) </math>
 
  
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There is an adjustment distance of 11.2cm which accounts for the distance from the faceplate to the surface of the  <math> ^{137}Cs</math> source
 
  
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Total exposures are calculated by <math>\int\limits_{t_0}^{t_f}\dot R\ dt </math>
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Total exposures are calculated by  
  
  

Revision as of 23:28, 15 May 2018

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] ^{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]{D}=(\text{Distance to faceplate} + 11.2cm)=41.2cm [/math] , the exposure rate is calculated in Roentgen using [math] \dot R = \frac {\Gamma A }{ D^2} [/math]. A gamma factor of [math] {\Gamma} = 0.33 \frac {(m^2)(R)}{(Ci)(hr)} [/math] and activity of [math]{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]\int\limits_{t_0}^{t_f}\dot R\ dt [/math].



Total exposures are calculated by




Click here for calibration data

Thesis

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