Absorbed Dose Calculation
How dose the DoseControl dosimetry system calculate dose?
A radiochromic dosimeter is a device that, when irradiated, exhibits a quantifiable change in Response that can be related to absorbed dose in a the dosimeter. Following ASTM 51261:2013 guidance, DoseControl software calculates the “absorbed dose” of a dosimeter based on the dosimeter’s Response (R) value, where R = f(Dose).
Response (R) = a + bx + cx^2 + dx^3 + ex^4
where R = (Ai-Ao)/T
Ao is the initial background Absorbance of the dosimeter prior to exposure to ionizing radiation.
Ai is the measured Absorbance of the dosimeter after exposure to ionizing radiation. The Absorbance is measured by the spectrophotometer.
T is the dosimeter batch thickness value.
R is the calculated Response value.
Calibrate your dosimetry system to achieve doses traceable to a certified standard
To establish a relationship between the dosimeter batch Response and Dose, you must calibrate your dosimetry system (also called ‘dosimeter batch calibration’). Dosimetry batch calibration is the process where the response of a dosimetry system is characterized through comparison with a traceable reference or standard. The calibration method for the dosimetry system is designed to ensure the integrity of the measurements made with the user’s dosimetry system. Routine dosimetry systems should be calibrated in accordance with the requirements of ISO/ASTM 51261.
The Calibration Laboratory will provide you with calibration curve coefficients, and you will enter this in the software in Setup - Calibrations.
DoseControl uses the calibration coefficients (provided by the Calibration Laboratory) to calculate dose using the equation R = f(Dose), as per ASTM 51261:2013. The calibration curve is derived in mathematical form, y= f(x), where dosimeter response is the dependent variable (y) and absorbed dose is the independent variable (x), such that y= a + bx + cx2 +dx3 +ex4.