Radiograph overlay image of a bronze mirrior with an ancient repair.
Why And When To Use Radiography
Radiography is a stand alone examination, but it generally is an essential supporting technique for other tests. It can be used on everything from paper to gold, and can reveal such information as construction, damage, restoration, replacement, and even density, internal corrosion and hidden calligraphy.
- Radiography should often be one of the first scientific examinations performed on an object, since the information obtained may be needed to determine the next course of action.
- The material, size, and thickness of the object should be determined so that the appropriate technique (X-Ray or Gamma Ray) can be chosen.
- Objects of portable size should be evaluated to determine if it is better to move the object, or the equipment.
It is important to remember that, if the object is to be sampled for TL testing, a record of the exposure strength and time should be maintained. The effect of the typical quantity of irradiation is generally minimal, but if numerous exposures are made, maintaining the record, and providing it to the TL facility, can eliminate any future controversy over possible dose tampering.
Radiography can be essential in determining the condition of an object, not only for the purposes of conservation, but also as supporting science for use with almost all other forms of antiquities testing, such as thermoluminescence (TL). CT Scanning is a related technique which uses X-Rays, but the term radiography generally refers to X-Ray and Gamma Ray radiography.
- It is a non-destructive examination.
- X-Ray radiography services are readily accessible in many areas.
- Portable equipment exists which can be taken to the object.
- It requires only moderate training to understand most features on an image.
- Some X-Ray systems yield digital images, which are easily archived, and can easily be copied or emailed.
- Some software for use with digital X-Ray images can be used to extract significantly more information from a single image than is possible with an X-Ray film.
- It is generally only moderately expensive however depending on whether the object or the equipment is transported the cost may become substantial.
- When radiography is performed outside a shielded room, such as when the equipment is brought to the artifact, access to the area must be restricted to prevent over-exposure to the x-rays. The size of the restricted area can be quite large, although that is not the norm.