Question

An exposure is made at 200 cm SID and has an intensity of 5 milliroentgens (mR), and a second exposure is made is at 100 cm SID. Calculate the intensity of the x-ray beam of the second exposure.

Answer 1

The intensity of X-ray beam of second exposure made at 100 cm SID is 20 mR.

Solution:

By using inverse square law formula, intensity of X-Ray beam made at different distances can be found.

`(I_(1))/(I_(2))=\left((D_(2))/(D_(1))\right)^(2)`

Where
`I_1` is the intensity of first exposure of X-ray-beam.

`I_2` is the intensity of second exposure of X-ray beam.

`D_1` is the distance at which first exposure is made.

`D_2` is the distance at which second exposure is made.

`\begin{array}{l}{(I_(1))/(I_(2))=\left((100)/(200)\right)^(2)} \\\\ {(5)/(I_(2))=(1)/(4)} \\\\ \bold{{I_(2)=20\ \mathrm{mR}}\end{array}}`