title = "Radiographic Testing (RT): X-Ray and Gamma-Ray"

content = """
Radiographic Testing (RT) uses penetrating radiation — X-rays or gamma rays — to create an image of a component's internal structure on film or a digital detector. At Ridgecrest Metalworks, RT is performed by a licensed radiography subcontractor on pressure vessels, lifting equipment welds, and other safety-critical components where volumetric defect detection (porosity, inclusions, lack of fusion) is required by code or customer specification.

X-ray RT uses an X-ray tube producing a controlled beam of X-ray photons. Tube voltage is selected based on material type and thickness: higher kV penetrates thicker or denser material. The part is placed between the X-ray source and the film or digital detector panel. Denser material (metal) absorbs more radiation, producing lighter areas on the film; voids, porosity, and low-density inclusions appear as darker areas on the film (or lighter on digital). The image captures a two-dimensional projection of the entire through-thickness volume.

Gamma-ray RT uses radioactive isotopes (Ir-192 for thicknesses 20–100 mm steel; Se-75 for thinner sections; Co-60 for very heavy sections) as the radiation source. Gamma sources are smaller and portable, enabling field radiography on pipelines and large structures. However, gamma sources cannot be switched off and require secure storage in shielded containers (camera/projector) and a licensed radioactive materials program.

RT setup and quality indicators:
- Image Quality Indicators (IQIs / penetrameters): Small reference devices (wire IQI or hole IQI) placed adjacent to the part on the source side. The smallest visible wire or hole verifies that the sensitivity specified by the standard is achieved.
- Geometric magnification and film-to-source distance (FSD) are calculated to maintain adequate image sharpness.
- Single-wall, double-wall, and panoramic techniques are selected based on part geometry.

Acceptance criteria for RT of welds are per the applicable standard: ASME Boiler and Pressure Vessel Code Section VIII for pressure vessels, ISO 10675 for structural welds, or customer-specific standards.

RT at Ridgecrest is fully outsourced. The radiographer operates under their own radiation protection procedures and NRC license. Ridgecrest provides the parts and work order; the radiographer provides the technique sheet, film interpretation, and written report. All RT films and digital images are retained in the quality record system for the retention period required by the applicable code.
"""

version = "0.0.1"
