National Board Dental Hygiene Examination (NBDHE) Dental Hygienist Practice Test

To minimize image magnification in radiographs, which type of object-to-film distance should be used?

1. Shorter

2. Longer

3. Variable

4. Equal

The correct answer is: Shorter

To minimize image magnification in radiographs, a longer object-to-film distance should be utilized. This is because increasing the distance between the object being radiographed (such as a tooth or a group of teeth) and the film or sensor reduces the effects of magnification. When the object is farther away from the film, the diverging rays of radiation that reach the film create a smaller and more accurate representation of the object, thereby reducing its apparent size. In radiographic techniques, the geometry of the setup plays a critical role in image clarity and size. A longer object-to-film distance leads to a reduction in distortion and allows for a more accurate depiction of the actual dimensions of the object, thus improving diagnostic quality. Conversely, a shorter object-to-film distance would result in increased magnification and distortion, making it challenging to assess the true size and position of the structures being imaged.