Radiography and Imaging
Core concepts
Understand image production, radiation safety, and quality assurance. Know the types of intraoral images (periapical, bitewing, occlusal) and extraoral images (panoramic, cephalometric, CBCT), and what each is used to evaluate. Learn the principles of ALARA, collimation, filtration, lead aprons and thyroid collars, and the selection criteria that justify an exposure. Understand film and digital sensor handling, processing errors, and how to recognize common artifacts. Know the appearance of normal anatomy and common pathology on images.
Traps to watch
Questions test the difference between technique errors and processing errors: elongation and foreshortening are angulation problems, while a blank or fogged image suggests processing or exposure issues. Another trap is confusing what a bitewing shows (coronal interproximal areas and crestal bone) with what a periapical shows (full tooth and apex). Radiation safety traps involve the misconception that digital imaging eliminates the need for precautions - it reduces dose but does not remove the need for shielding and collimation. CBCT dose is higher than conventional intraoral imaging.
Worked rule of thumb
For any image-quality question, identify whether the problem is patient positioning, beam angulation, exposure settings, or processing. Each produces a distinct pattern. Example: overlapping contacts on a bitewing indicate incorrect horizontal angulation, not a processing fault.
Quality assurance
Follow a routine QA schedule for equipment, sensors, and processors, and document results.