What is the permissible percentage difference between the light field and the radiation field in relation to the Source-to-Image Distance (SID)?

The permissible percentage difference between the light field and the radiation field in relation to the Source-to-Image Distance (SID) is established to ensure that the area being radiated matches accurately with the image receptor area. The guideline allows a maximum difference of 2% of the SID. This ensures that patients are not exposed to unnecessary radiation due to misalignment or excessive radiation field margins.

In practical terms, this means that for a SID of 100 cm, the light field must align accurately within 2 cm of the radiation field. Maintaining this standard is critical for ensuring patient safety and optimizing image quality by ensuring that the right area is exposed during radiographic procedures. Such precision in alignment reduces the risk of radiation overexposure to the patient and improves the overall effectiveness of the imaging process.