Answer: The answer is 2. Capture less of the diverging beam.
Explanation: When the anatomy of interest is placed closer to the image receptor, the diverging beam is more likely to be captured by the image receptor. This can lead to increased scatter radiation, which can degrade the image quality.
To reduce scatter radiation, technologists may move the anatomy of interest away from the image receptor slightly. This will help to ensure that less of the diverging beam is captured by the image receptor.
The other options are not valid reasons for changing from the practice of placing the anatomy of interest as close as possible to the image receptor:
1. Improve radiographic brightness: Placing the anatomy of interest closer to the image receptor will actually improve radiographic brightness, because the x-rays will have to travel through less tissue to reach the image receptor.
3. Increase exposure indicators: Exposure indicators are used to measure the amount of radiation that is delivered to the patient. Placing the anatomy of interest closer to the image receptor will not affect the exposure indicators.
4. Reduce scatter to the image receptor: Scatter radiation is radiation that is deflected away from its original path by interaction with matter. Placing the anatomy of interest closer to the image receptor will actually increase scatter to the image receptor, because the diverging beam is more likely to be captured by the image receptor.
Therefore, the only valid reason for changing from the practice of placing the anatomy of interest as close as possible to the image receptor is to reduce scatter radiation.