Co-60 Exposure Time Calculation
Basic for Co-60 Exposure Time Calculation
For calculate the exposure time, the fallowing steps should be imported
Exposure Time Calculation Formula is:
1. Calculate the present source activity in curies(Ci) from the decay charts.
2. Find thickness (cm) of the object.
3. Find HVT (cm) of object material, foe the given source by HVT Table.
4. Write RHM value (1.33 for Cobalt-60)
5. Find film factor (FF in Roentgen) from Given Table.
Film Factor Table of Co-60 (R)
| Source | NDT-65 | NDT-70 | Fast Film | Agfa D-7 | Agfa D-4 | Agfa D-5 | Agfa D-2 |
|---|---|---|---|---|---|---|---|
| Cobalt-60 | 3.0 | 2.0 | 1.8 | 2.5 | 8.0 | --- | 19.6 |
Substitute all these values in the following formula
Exposure Time Calculation Formula is:
\[
ET = \frac{FF * 2^{(T/HVT)} * SFD^2 * 60}{Ci * RHM * 100^2}
\]
where: ET = Exposure Time in Minutes
FF = Film Factor
T = Object Thickness
HVT = HVT (cm) of object material
SFD = Source to Film Distance in cm
Ci = Current Activity of Source in curies (Ci)
RHM = Source RHM value in Roentgen
It may be noted that this formula is not very accurate for higher thickness, particularly when using cobalt-60 source.
Calculate given formula below to calculate Co-60 Exposure Time Calculation.
NDT Check
For Co-60 Expose Time Calculation for Steel Object
The Result in Minutes is :