If a radiograph made with an exposure of 12mA per minute achieves a density of 0.8, what new exposure time is required to reach a density of 2.0?

To determine the new exposure time needed to achieve a desired density on a radiograph, we can use the principle of reciprocity in radiographic exposure. The density of a radiograph is directly related to the product of the mA (milliamperes) and the exposure time in minutes.

In this scenario, the initial radiograph is produced with 12 mA for one minute, resulting in a density of 0.8. The goal is to reach a density of 2.0. To find the necessary new exposure, we first recognize that the increase in density is proportional to the increase in the exposure product (mA × time).

The increase in density can be calculated as follows:

• Initial density: 0.8

• Desired density: 2.0

• Density increase factor: 2.0 / 0.8 = 2.5

This means we require 2.5 times the original exposure to achieve the desired density. Since the original exposure was 12 mA per minute, we calculate the new exposure:

New exposure = Original mA × Density increase factor

New exposure = 12 mA × 2.5 = 30 mA for one minute.

Now,