Radiographic
Testing

Radiographic Testing

Radiographic Testing Formula

Commonly used RT Formula are provided for reference

Featured Formula Remarks
Inverse Square law
I1 I2 = D22 D21
Where,
I1 and I2 are the intensities at distances D1 and D2, respectively.
Current (Vs) Time
I1 I2 = T2 T1
Where,
I = milliamperage
T= time (exposure)
Current (Vs) Distance
I1 I2 = D21 D22
Where,
I = milliamperage
D= distance
Time (Vs) Distance
T1 T2 = D21 D22
Where,
T = time
D= distance
Activity (Vs) Distance
A1 A2 = D21 D22
Where,
A = activity of isotope in curies
D= distance
Time (Vs) Density
T2 T1 = Dn2 Dn1
Where,
Calculate a Time (T2) to achieve a desired Density (Dn2) versus unacceptable Density (Dn1) (too light or too dark)
Time (Vs) Curies
T2 T1 = Ci2 Ci1
Where,
Calculate a new Exposure Time (T2) when the number of curies (Ci2) changes
Degree of Enlargement
S0 S1 = D0 D1
Where,
Degree of Enlargement
S1 = Size of image (Shadow)
Do = Source to object distance
D1 = Source to film distance
Half Value Layer (HVL)
HVL = 0.693 š
Where,
HVL = Half Value Layer
š = linear attenuation coefficient
Ā½ Value and 1/10 value Relationship
3.33 HVL = 1 TVL
Where,
HVL = Half-value layer
TVL = Tenth-value layer
Geometric Unsharpness
Ug = FT D0
Where,
Ug = Geometric Unsharpness
F = Focal Spot Size
T = Object to film distance
Do = Source to Object distance
Attenuation
Ix = I0 e-št
Where,
Ix = Final Intensity
Io = Original Intensity
š = Absorption coefficient
T = thickness of material
Dose Rate (DR)
DR = D T
Where,
DR = Dose Rate
D = Dose
T = Time
Radiographic Density (D)
D = log (I0It)
Where,
D = Film density
I0 = Incident intensity
It = Transmitted intensity
Focal Spot Size (FSS)
FSS = āˆšL2 + d2
Where,
d = Source diameter
L = Source Length
Parallax method (Defect Depth Formula Similar Triangle Relationship)
d = bt a + b
Where,
d = distance of flaw above film plane
b = change in position of flaw image
a = source shift
t = focus to film distance
Chart - Exposure Chart for Iridium 192 Source
Exposure Chart for Iridium 192 Source
Chart - Exposure Chart for X-Ray
Exposure Chart for X-Ray
Chart - Half Value Layer (HVL) and Tenth Value Layer (TVL) Tables
Half Value Layer (HVL) and Tenth Value Layer (TVL) Tables

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