Questions: QUESTION 5 / 10
An x-ray exposure at 50 inches (127 cm) results in a beam intensity of 200 microgray ( μGy ). What is the new intensity for an x-ray exposure at 40 inches (102 cm)?
128 μGy
160 μGy
250 μGy
312 μGy
Transcript text: QUESTION $5 / 10$
An x-ray exposure at 50 inches $(127 \mathrm{~cm})$ results in a beam intensity of 200 microgray ( $\mu G y$ ). What is the new intensity for an $x$-ray exposure at 40 inches (102 cm )?
$128 \mu \mathrm{~Gy}$
$160 \mu \mathrm{~Gy}$
$250 \mu \mathrm{~Gy}$
$312 \mu \mathrm{~Gy}$
Solution
Solution Steps
Step 1: Understand the Inverse Square Law
The intensity of x-ray exposure is inversely proportional to the square of the distance from the source. This relationship is described by the inverse square law:
\[
I_1 \cdot d_1^2 = I_2 \cdot d_2^2
\]
where \( I_1 \) and \( I_2 \) are the intensities at distances \( d_1 \) and \( d_2 \), respectively.
Step 2: Identify Known Values
From the problem, we know:
\( I_1 = 200 \, \mu\text{Gy} \)
\( d_1 = 50 \, \text{inches} \)
\( d_2 = 40 \, \text{inches} \)
Step 3: Apply the Inverse Square Law
Substitute the known values into the inverse square law equation: