Which type of radiograph is free from geometrical distortion?

The concept of geometrical distortion in radiography refers to the inaccuracies that can occur in the representation of structures due to the angles and positions involved in taking X-rays. Intraoral radiographs, which are taken inside the mouth, can often exhibit some level of geometrical distortion due to the varying distances and angles between the X-ray source, the object (teeth), and the film or sensor.

Extraoral radiographs, on the other hand, are taken from outside the mouth and include images like panoramic or cephalometric X-rays. While these may minimize some distortions inherent in intraoral imaging, they are still subject to geometric distortions due to factors such as the positioning of the patient and the X-ray machine.

Both intraoral and extraoral radiographs cannot be entirely free from geometrical distortion because of the physical principles applied when creating these images. Therefore, the answer indicating that "none" of the types of radiographs are free from geometrical distortion is correct, highlighting the inherent limitations that exist in both intraoral and extraoral imaging techniques.