RT Film Selection 1

[Marc Stevenson]

Which criteria of RT Film selection is correct and why?

According to the Type of Source:-

For X-ray fine grain and for J-ray Ultra fine grain (Such as Agfa D4 and Kodak Industries MX)

OR

According to ASTM E1815, Which states the following:-

"Various codes and specifications require film selection based on a class (Type 1, 2, or 3) from a version of Guide E 94 dated before 1984. In Guide E 94 – 83,speed, contrast,and graininess were specified as limiting values, but only in a subjective way. In accordance with this guide, a range of films was classified in order of increasing speed and decreasing image quality (contrast and graininess). Image quality was optimized for a given speed. This test method has similar classes: Special, I, II, and III (see Table 3). The film systems that will generally fit this classification are of high-contrast technology. Image quality is optimized for every speed. Granularity increases with speed, and gradient is a maximum for the slower speed film systems."

 

[DekDee]

Marc,
Not sure what you are asking here ?
The codes/standards (and also project specifications) give you requirements for sensitivity and density.
Film choice is based on achieving whatever is required.
Regards,
Shane

 

[JR97]

Marc,

The whole film quality and grading has evolved somewhat over time. You are correct the specifications from 30 years ago went to great length to describe acceptable and unacceptable grades of film. DekDee is correct that most specifications have evolved to the point that it is up to the radiographer to determine which type film is needed for a given inspection to result in the required density and sensitivity. If I am shooting a piece that is thin relative to the energy level of the radiation, I am going to need to use a slower film (less grainliness, better grade) in order to get sensitivity. The film grade requirement evolution is similar to unsharpness. Most specifications would impose minimum unsharpness which would limit source size and source to object distance in order to produce readable radiographs. Today, most specifications list the unsharpness formula as a recommendation. The ability to see the applicable hole or wire in the IQI is the "proof in the pudding" that the radiographic parameters, including unsharpness and film grade, are adequate such that the radiograph accurately represents the part being inspected.

JR97

 

[Marc Stevenson]

Thank you for your responses @DekDee and @JR97. I appreciate it.

My company's standard states only the first part as a criteria of selection. That means if it is X-ray then fine grain film and if it is J-ray then ultra fine grain film.

Now it has been pointed out to me that this basis of selection is wrong and that the selection should be based on ASTM E1815.

As per my understanding of the quoted paragraph from ASTM E1815 it mentions that the selection based on graininess is outdated. Therefore, my company's standard is outdated as well and selection should be based on ASTM E1815.

Is my analysis correct or wrong?

 

[DekDee]

Marc,
Sorry but you are wrong.
This is an excerpt from ASTM E1815

4.3 Manufacturers of industrial radiographic film systems and developer chemistry will be the users of this test method. The result is a classification table as shown by the example given in Table 2. Another table also includes speed data for user information. Users of industrial radiographic film systems may also perform the tests and measurements outlined in this test method, provided that the required test equipment is used and the methodology is followed strictly.

I spent 4 years as an industrial radiographer and I have never heard of ASTM E1815 ???

Your company standards are an industry norm and they are there for a reason.
You don't generally need ultra-fine grain for x-ray to achieve the required density/sensitivity so why pay more money and have longer exposure time ?
Conversely, you may be able to achieve the required density/sensitivity using fine grain film on gamma radiography but why take the risk ?

Now it has been pointed out to me that this basis of selection is wrong and that the selection should be based on ASTM E1815.
Find this person and give him/her a good kick in the ass !!!!!

Regards,
Shane