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Radiography Formula
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Inverse Square Law
Exposure -  Distance
Reciprocity Law

Where:

I1 = Intensity 1 at D1
I2 = Intensity 2 at D2
D1 = Distance 1 from source
D2 = Distance 2 from source

more information:
Inverse Square Law
Calculation

Where:

E1 = Exposure at D1
E2 = Exposure at D2
D1 = Distance 1 from source
D2 = Distance 2 from source

more information:
Exposure-Distance Calculation

Where:

C1 = Current 1
C2 = Current  2
T1 = Time 1 at C1
T2 = Time 2 at C2

more information:
Current-Time Reciprocity Calculation

Film Density - Exposure

Geometric
Magnification
Geometric Unsharpness

      
Note: This is an approximation and is only valid for the straight line portion of the film characteristic curve.  See more info section.
Where:

E1 = Exposure 1
E2 = Exposure 2
FD1 = Film Density at Exposure 1
FD2 = Film Density with Exposure 2

more information:
Film Density - Exposure Calculation

    


Where:

M = Magnification
a = Distance from source to object
b = Distance from object to detector
     

more information:
Geometric Magnification Calculation



Where:

Ug = Geometric unsharpness
f = Focal spot size
a = Distance from source to object
b = Distance from object to detector

more information:
Geometric Unsharpness Calculation

Indication Depth

Attenuation

Half-Value Layer

      
Where:

D = Defect depth from the film side of the part
t = Thickness of material
SD = Shift of defect image on the film
SM = Shift of surface marker on the film

more information:
Indication Depth Calculation

Where:

Ix = transmitted intensity
Io = Original intensity
m = Linear attenuation coefficient
x =

Distance in material or material thickness

more information:
Attenuation Calculation

Where:

HVL = Half-value layer
m = Linear attenuation coefficient
     

 

more information:
Half-Value Layer Calculation